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1.  Clinical results of XMR-assisted percutaneous transforaminal endoscopic lumbar discectomy 
Although percutaneous endoscopic lumbar discectomy (PELD) has shown favorable outcomes in the majority of lumbar discectomy cases, there were also some failures. The most common cause of failure is the incomplete removal of disc fragments. The skin entry point for the guide-needle trajectory and the optimal placement of the working sleeve are largely blind, which might lead to the inadequate removal of disc fragments. The objective of this study was to present our early experiences with image-guided PELD using a specially designed fluoroscope with magnetic resonance imaging-equipped operative suite (XMR) for the treatment of lumbar disc herniation.
This prospective study included 89 patients who had undergone PELD via the transforaminal approach using an XMR protocol. Pre- and postoperative examinations (at 12 weeks) included a detailed clinical history, visual analogue scale (VAS), Oswestry disability index (ODI), and radiological workups. The results were categorized as excellent, good, fair, and poor according to MacNab's criteria. At the final follow-up, the minimum follow-up time for the subjects was 2 years. The need for revision surgeries and postoperative complications were noted on follow-up.
Postoperative mean ODI decreased from 67.4% to 5.61%. Mean VAS score for back and leg pain improved significantly from 4 to 2.3 and from 7.99 to 1.04, respectively. Four (4.49%) patients underwent a second-stage PELD after intraoperative XMR had shown remnant fragments after the first stage. As per MacNab's criteria, 76 patients (85.4%) showed excellent, 8 (8.89%) good, 3 (3.37%) fair, and 2 (2.25) poor results. Four (4.49%) patients had remnant disc fragments on XMR, which were removed during the same procedure. All of these patients had either highly migrated or sequestrated disc fragments preoperatively. Four (4.49%) other patients needed a second, open surgery due to symptomatic postoperative hematoma (n = 2) and recurrent disc herniation (n = 2).
This prospective analysis indicates that XMR-assisted PELD provides a precise skin entry point. It also confirms that decompression occurs intraoperatively, which negates the need for a separate surgery and thus increases the success rate of PELD, particularly in highly migrated or sequestrated discs. However, further extensive experience is required to confirm the advantages and feasibility of PELD in terms of cost effectiveness.
PMCID: PMC3668223  PMID: 23705685
Percutaneous endoscopic lumbar discectomy; Incomplete disc removal; XMR-guided procedure; High success rate
2.  Comparison of two novel fluoroscopy-based stereotactic methods for cervical pedicle screw placement and review of the literature 
European Spine Journal  2008;17(4):564-575.
This experimental study was designed to compare two different fluoroscopy-based stereotactic surgical techniques for transcutaneous cervical pedicle screw (CPS) placement in the subaxial human cervical spine: (1) a custom-made aiming frame (AF) in combination with conventional fluoroscopy versus (2) a targeting device in combination with a computer-assisted image guidance system [i.e. virtual fluoroscopy (VF)]. Surgery was carried out on six preserved human total body specimens in a laboratory setting. Sixty pedicles (levels C3–C7) were measured in a multislice computed tomography (CT) image data set prior to surgery. Two groups consisting of three specimens and 30 pedicles each were defined according to the surgical technique. The AF consisted of radiolucent components with a fully adjustable arm for carrying the instruments necessary for placing the screws. The arm was angled according to the cervical pedicle axis, as determined by the preoperative CT scans and intraoperative lateral fluoroscopy. For VF, a targeting device was combined with a computer-assisted image-guided surgery unit. For both stereotactic techniques, 3.5 mm screws made of carbon fibre polyetheretherketone (ECF-PEEK) were inserted transcutaneously through stab incisions. Screw placement was assessed using a four-point grading system ranging from ideal (I) to unacceptable (III) where I = screw centred in pedicle, IIa = perforation of pedicle wall is less than one-fourth of the screw diameter, IIb = perforation of the pedicle wall is more than one-fourth of the screw diameter without contact to neurovascular structures, and III = CPS in contact with neurovascular structures. Fifty-eight pedicle screws could be evaluated without interfering metal artefacts according to the same CT protocol that was used preoperatively. The AF technique achieved a significantly smaller number of screws in contact with neurovascular structures compared with the VF technique (P = 0.021; Fisher’s exact test) (Grade I n = 15; 64.3% AF vs. n = 13; 43.3% VF and Grade III n = 2; 7.1% AF vs. n = 10; 33.3% VF). Although neither of the two techniques was capable of completely preventing CPS perforations, transcutaneous CPS placement with a conventional fluoroscopy-based stereotactic AF can be considered a less expensive alternative to VF. This AF technique is able to reduce the number and severity of lateral pedicle wall violations compared to screw placement via the wide standard posterior open midline approach to the subaxial cervical spine. The results of this study are discussed in context with those obtained from different published modifications, since the first technical description of this surgical technique in 1994 by Abumi and co-workers.
PMCID: PMC2295280  PMID: 18210169
Cervical spine; Morphometry; Cervical pedicle screws; Frame-based stereotaxis; Computer-assisted fluoroscopic navigation
3.  Percutaneous endoscopic lumbar discectomy for migrated disc herniation: classification of disc migration and surgical approaches 
European Spine Journal  2006;16(3):431-437.
Percutaneous endoscopic lumbar discectomy (PELD) for migrated disc herniations is technically demanding due to the absence of the technical guideline. The purposes of this study were to propose a radiologic classification of disc migration and surgical approaches of PELD according to the classification. A prospective study of 116 consecutive patients undergoing single-level PELD was conducted. According to preoperative MRI findings, disc migration was classified into four zones based on the direction and distance from the disc space: zone 1 (far up), zone 2 (near up), zone 3 (near down), zone 4 (far down). Two surgical approaches were used according to this classification. Near-migrated discs were treated with “half-and-half” technique, which involved positioning a beveled working sheath across the disc space to the epidural space. Far-migrated discs were treated with “epiduroscopic” technique, which involved introducing the endoscope into the epidural space completely. The mean follow-up period was 14.5 (range 9–20) months. According to the Macnab criteria, satisfactory results were as follows: 91.6% (98/107) in the down-migrated discs; 88.9% (8/9) in the up-migrated discs; 97.4% (76/78) in the near-migrated discs; and 78.9% (30/38) in the far-migrated discs. The mean VAS score decreased from 7.5 ± 1.7 preoperatively to 2.6 ± 1.8 at the final follow-up (P < 0.0001). There were no recurrence and no approach-related complications during the follow-up period. The proposed classification and approaches will provide appropriate surgical guideline of PELD for migrated disc herniation. Based on our results, open surgery should be considered for far-migrated disc herniations.
PMCID: PMC2200706  PMID: 16972067
Percutaneous endoscopic lumbar discectomy; Migrated disc herniation; Radiologic classification
4.  Clinical and radiological association with positive lumbar discography in patients with chronic low back pain 
Study design: Retrospective cohort study.
Objectives: To find out (1) if magnetic resonance imaging (MRI) findings associated with positive discography in patients with lumbar discogenic pain are caused by degenerative disc disease (DDD). (2) If clinical risk factors associated with positive discography in patients with lumbar discogenic pain are caused by DDD.
Methods: Thirty-three discographies were performed in 20 consecutive patients with chronic low back pain (LBP). All examinations were performed in the lumbar spine between L3 and S1. Patient assessment consisted of a clinical and radiological examination through a protocol that contained data on the history, visual analogue scale for pain (VAS), functional questionnaire (Oswestry), and MRI findings. Discography was considered positive using the Walsh's criteria. We examined the association between MRI and clinical findings with positive discography using logistic regression.
Results: Fourteen discographies (42%) were positive and 19 (58%) were negative. The mean age of patients with positive discography was 40.7 years (range, 25–56 years) and negative discography 43.1 years (range, 30–55 years). Men had a positive discography rate of 43.5% and women 40%. Patients with LBP had reduced odds of a positive discography compared with those with LBP and sciatica (OR = .5; 95% CI: 0.1–2.7); however, this association was not statistically significant. Patients with more than four previous episodes of pain versus patients with one to four episodes had greater odds of a positive discography (OR = 3.8; 95% CI: 0.07–184); but this association was not statistically significant. Patients with various pathologies on MRI had greater odds of a positive discography; however, these associations were not statistically significant either.
Conclusions: Patients with a chief complaint of LBP associated with sciatica, with more than four episodes of previous LBP exacerbations and the presence of a high intensity zone (HIZ) on MRI have a higher rate of positive discography. These findings are not statistically significant, probably due to a small sample size. During discography, we found the end point resistance to be more prevalent in asymptomatic discs.
PMCID: PMC3503511  PMID: 23236303
5.  Comparison of Percutaneous Endoscopic Lumbar Discectomy and Open Lumbar Microdiscectomy for Recurrent Disc Herniation 
The purpose of this study was to compare clinical and radiological outcomes of percutaneous endoscopic lumbar discectomy (PELD) and open lumbar microdiscectomy (OLM) for recurrent disc herniation.
Fifty-four patients, who underwent surgery, either PELD (25 patients) or repeated OLM (29 patients), due to recurrent disc herniation at L4-5 level, were divided into two groups according to the surgical methods. Excluded were patients with sequestrated disc, calcified disc, severe neurological deficit, or instability. Clinical outcomes were assessed using Visual Analogue Scale (VAS) score and Oswestry Disability Index (ODI). Radiological variables were assessed using plain radiography and/or magnetic resonance imaging.
Mean operating time and hospital stay were significantly shorter in PELD group (45.8 minutes and 0.9 day, respectively) than OLM group (73.8 minutes and 3.8 days, respectively) (p < 0.001). Complications occurred in 4% in PELD group and 10.3% in OLM group in the perioperative period. At a mean follow-up duration of 34.2 months, the mean improvements of back pain, leg pain, and functional improvement were 4.0, 5.5, and 40.9% for PELD group and 2.3, 5.1, and 45.0% for OLM group, respectively. Second recurrence occurred in 4% after PELD and 10.3% after OLM. Disc height did not change after PELD, but significantly decreased after OLM (p = 0.0001). Neither sagittal rotation angle nor volume of multifidus muscle changed significantly in both groups.
Both PELD and repeated OLM showed favorable outcomes for recurrent disc herniation, but PELD had advantages in terms of shorter operating time, hospital stay, and disc height preservation.
PMCID: PMC2803265  PMID: 20062565
Reherniation; Discectomy; Lumbar spine
6.  Risk of whole body radiation exposure and protective measures in fluoroscopically guided interventional techniques: a prospective evaluation 
BMC Anesthesiology  2003;3:2.
Fluoroscopic guidance is frequently utilized in interventional pain management. The major purpose of fluoroscopy is correct needle placement to ensure target specificity and accurate delivery of the injectate. Radiation exposure may be associated with risks to physician, patient and personnel. While there have been many studies evaluating the risk of radiation exposure and techniques to reduce this risk in the upper part of the body, the literature is scant in evaluating the risk of radiation exposure in the lower part of the body.
Radiation exposure risk to the physician was evaluated in 1156 patients undergoing interventional procedures under fluoroscopy by 3 physicians. Monitoring of scattered radiation exposure in the upper and lower body, inside and outside the lead apron was carried out.
The average exposure per procedure was 12.0 ± 9.8 seconds, 9.0 ± 0.37 seconds, and 7.5 ± 1.27 seconds in Groups I, II, and III respectively. Scatter radiation exposure ranged from a low of 3.7 ± 0.29 seconds for caudal/interlaminar epidurals to 61.0 ± 9.0 seconds for discography. Inside the apron, over the thyroid collar on the neck, the scatter radiation exposure was 68 mREM in Group I consisting of 201 patients who had a total of 330 procedures with an average of 0.2060 mREM per procedure and 25 mREM in Group II consisting of 446 patients who had a total of 662 procedures with average of 0.0378 mREM per procedure. The scatter radiation exposure was 0 mREM in Group III consisting of 509 patients who had a total 827 procedures. Increased levels of exposures were observed in Groups I and II compared to Group III, and Group I compared to Group II.
Groin exposure showed 0 mREM exposure in Groups I and II and 15 mREM in Group III. Scatter radiation exposure for groin outside the apron in Group I was 1260 mREM and per procedure was 3.8182 mREM. In Group II the scatter radiation exposure was 400 mREM and with 0.6042 mREM per procedure. In Group III the scatter radiation exposure was 1152 mREM with 1.3930 mREM per procedure.
Results of this study showed that scatter radiation exposure to both the upper and lower parts of the physician's body is present. Protection was offered by traditional measures to the upper body only.
PMCID: PMC194671  PMID: 12904269
7.  Radiation dose reduction in CT-guided sacroiliac joint injections to levels of pulsed fluoroscopy: a comparative study with technical considerations 
Journal of Pain Research  2012;5:265-269.
The sacroiliac (SI) joint is frequently the primary source of low back pain. Over the past decades, a number of different SI injection techniques have been used in its diagnosis and therapy. Despite the concerns regarding exposure to radiation, image-guided injection techniques are the preferred method to achieve safe and precise intra-articular needle placement. The following study presents a comparison of radiation doses, calculated for fluoroscopy and CT-guided SI joint injections in standard and low-dose protocol and presents the technical possibility of CT-guidance with maximum radiation dose reduction to levels of fluoroscopic-guidance for a precise intra-articular injection technique.
To evaluate the possibility of dose reduction in CT-guided sacroiliac joint injections to pulsed-fluoroscopy-guidance levels and to compare the doses of pulsed-fluoroscopy-, CT-guidance, and low-dose CT-guidance for intra-articular SI joint injections.
Study design
Comparative study with technical considerations.
A total of 30 CT-guided intra-articular SI joint injections were performed in January 2012 in a developed low-dose mode and the radiation doses were calculated. They were compared to 30 pulsed-fluoroscopy-guided SI joint injections, which were performed in the month before, and to five injections, performed in standard CT-guided biopsy mode for spinal interventions. The statistical significance was calculated with the SPSS software using the Mann–Whitney U-Test. Technical details and anatomical considerations were provided.
A significant dose reduction of average 94.01% was achieved using the low-dose protocol for CT-guided SI joint injections. The radiation dose could be approximated to pulsed-fluoroscopy- guidance levels.
Radiation dose of CT-guided SI joint injections can be decreased to levels of pulsed fluoroscopy with a precise intra-articular needle placement using the low-dose protocol. The technique is simple to perform, fast, and reproducible.
PMCID: PMC3442745  PMID: 23028237
sacroiliac joint pain; computed tomography; guided injections; low-dose protocol; sacroiliac joint injection; low back pain; radiation dose
8.  Percutaneous pedicle screw placement in the thoracic spine: A cadaveric study 
Asian Journal of Neurosurgery  2013;8(3):153-156.
Study Design:
A cadaveric study to determine the accuracy of percutaneous screw placement in the thoracic spine using standard fluoroscopic guidance.
Summary of Background Data:
While use of percutaneous pedicle screws in the lumbar spine has increased rapidly, its acceptance in the thoracic spine has been slower. As indications for pedicle screw fixation increase in the thoracic spine so will the need to perform accurate and safe placement of percutaneous screws with or without image navigation. To date, no study has determined the accuracy of percutaneous thoracic pedicle screw placement without use of stereotactic imaging guidance.
Materials and Methods:
Eighty-six thoracic pedicle screw placements were performed in four cadaveric thoracic spines from T1 to T12. At each level, Ferguson anterior–posterior fluoroscopy was used to localize the pedicle and define the entry point. Screw placement was attempted unless the borders of the pedicle could not be delineated solely using intraoperative fluoroscopic guidance. The cadavers were assessed using pre- and postprocedural computed tomography (CT) scans as well as dissected and visually inspected in order to determine the medial breach rate.
Ninety pedicles were attempted and 86 screws were placed. CT analysis of screw placement accuracy revealed that only one screw (1.2%) breached the medial aspect of the pedicle by more than 2 mm. A total of four screws (4.7%) were found to have breached medially by visual inspection (three Grade 1 and one Grade 2). One (1.2%) lateral breach was greater than 2 mm and no screw violated the neural foramen. The correlation coefficient of pedicle screw violations and pedicle diameter was found to be 0.96.
This cadaveric study shows that percutaneous pedicle screw placement can be performed in the thoracic spine without a significant increase in the pedicle breach rate as compared with standard open techniques. A small percentage (4.4%) of pedicles, especially high in the thoracic spine, may not be safely visualized.
PMCID: PMC3877502  PMID: 24403958
Minimally invasive surgery; pedicle screw; thoracic spine
9.  3D cone-beam CT guidance, a novel technique in renal biopsy—results in 41 patients with suspected renal masses 
European Radiology  2012;22(11):2547-2552.
To determine whether 3D cone-beam computed tomography (CBCT) guidance allows safe and accurate biopsy of suspected small renal masses (SRM), especially in hard-to-reach anatomical locations.
Materials and methods
CBCT guidance was used to perform 41 stereotactic biopsy procedures of lesions that were inaccessible for ultrasound guidance or CT guidance. In CBCT guidance, a 3D-volume data set is acquired by rotating a C-arm flat-panel detector angiosystem around the patient. In the data set, a needle trajectory is determined and, after co-registration, a fusion image is created from fluoroscopy and a slice from the data set, enabling the needle to be positioned in real time.
Of the 41 lesions, 22 were malignant, 17 were benign, and 2 were nondiagnostic. The two nondiagnostic lesions proved to be renal cell carcinoma. There was no growth during follow-up imaging of the benign lesions (mean 29 months). This resulted in a sensitivity, specificity, PPV, NPV, and accuracy of 91.7, 100, 100, 89.5, and 95.1%, respectively. Mean dose-area product value was 44.0 Gy·cm2 (range 16.5–126.5). There was one minor bleeding complication.
With CBCT guidance, safe and accurate biopsy of a suspected SRM is feasible, especially in hard-to-reach locations of the kidney.
Key Points
• Cone-beam computed tomography has potential advantages over conventional CT for interventional procedures.
• CBCT guidance incorporates 3D CBCT data, fluoroscopy, and guidance software.
• In hard-to-reach renal masses, CBCT guidance offers an alternative biopsy method.
• CBCT guidance offers good outcome and safety and has potential clinical significance.
PMCID: PMC3472072  PMID: 22660984
Percutaneous biopsy; Cone-beam CT; Small renal masses; Outcome; Hard-to-reach
10.  Ultrasound-Guided (Needle In-Plane) Perineural Catheter Insertion: The Effect of Catheter Insertion Distance on Postoperative Analgesia 
When using ultrasound guidance to place a perineural catheter for a continuous peripheral nerve block, keeping the needle-in plane and nerve in short-axis results in a perpendicular needle-to-nerve orientation. Many have opined that when placing a perineural catheter via the needle, the acute angle may result in the catheter bypassing the target nerve when advanced beyond the needle tip. Theoretically, greater catheter tip-to-nerve distances result in less local anesthetic-to-nerve contact during the subsequent perineural infusion, leading to inferior analgesia. While a potential solution may appear obvious—advancing the catheter tip only to the tip of the needle, leaving the catheter tip at the target nerve—this technique has not been prospectively evaluated. We therefore hypothesized that during needle in-plane ultrasound-guided perineural catheter placement, inserting the catheter a minimum distance (0-1 cm) past the needle tip is associated with improved postoperative analgesia compared with inserting the catheter a more-traditional 5-6 cm past the needle tip.
Preoperatively, subjects received a popliteal-sciatic perineural catheter for foot or ankle surgery using ultrasound guidance exclusively. Subjects were randomly assigned to have a single-orifice, flexible catheter inserted either 0-1 (n=50) or 5-6 cm (n=50) past the needle tip. All subjects received a single-injection mepivacaine (40 mL of 1.5% with epinephrine) nerve block via the needle, followed by catheter insertion and a ropivacaine 0.2% infusion (basal 6 mL/h, bolus 4 mL, 30 min lockout), through at least the day following surgery. The primary end point was average surgical pain as measured with a 0-10 numeric rating scale the day following surgery. Secondary end points included time for catheter insertion, incidence of catheter dislodgement, maximum (“worst”) pain scores, opioid requirements, fluid leakage at the catheter site, and the subjective degree of an insensate extremity.
Average pain scores the day following surgery for subjects of the 0-1 cm group was a median (interquartile) of 2.5 (0.0-5.0), compared with 2.0 (0.0-4.0) for subjects of the 5-6 cm group (p=0.42). Similarly, among the secondary end points, no statistically significant differences were found between the two treatment groups. There was a trend of more catheter dislodgements in the minimum-insertion group (5 vs. 1; p=0.20).
This study did not find evidence to support the hypothesis that for popliteal-sciatic perineural catheters placed using ultrasound guidance and a needle in-plane technique, inserting the catheter a minimum distance (0-1 cm) past the needle tip improves (or worsens) postoperative analgesia compared with inserting the catheter a more-traditional distance (5-6 cm). Caution is warranted if extrapolating these results to other catheter designs, ultrasound approaches, or anatomic insertion sites.
PMCID: PMC3085850  PMID: 21519311
11.  Comparative Study of the Outcomes of Percutaneous Endoscopic Lumbar Discectomy and Microscopic Lumbar Discectomy Using the Tubular Retractor System Based on the VAS, ODI, and SF-36 
Korean Journal of Spine  2012;9(3):215-222.
Percutaneous endoscopic lumbar discectomy (PELD) and microdiscectomy with the microscope endoscopic tubular retractor system(METRx-MD) are considered popular minimally invasive surgery (MIS) methods for the treatment of lumbar disc herniation. Many authors have also reported good clinical outcomes of these methods, but there are few comparative studies of them. This report compares the clinical outcomes of PELD and METRx-MD for lumbar disc herniation as MIS methods and discusses the efficacy of PELD.
Seventy-two patients who had undergone single-level unilateral discectomy using two different methods, PELD and METRx-MD, between 2009 and 2011 were given a follow-up examination prospectively. Thirty-seven of these patients underwent discectomy using PELD, and the remaining 35 patients underwent discectomy using METRx-MD. In addition to the general parameters, clinical outcomes were assessed as specific parameters using the Visual Analogue Scale (VAS) score, the Oswestry Disability Index (ODI), the Short-form 36 (SF-36), and the return-to-work time.
Sixty-seven percent (25/37) of the patients in the PELD group and 74%(26/35) in the METRx-MD group were included in follow-up more than 6 months post-operatively. The mean improvements in the VAS scores for the back pain, leg pain, and ODI were 2.6, 4.8, and 30.1% for the PELD group and 2.8, 4.6, and 33.2% for the METRx-MD group, respectively. The SF-36 physical health component subscale score improved from 40.6 pre-operatively to 68.3 at the last follow-up for the PELD group post-operatively, and from 48.5 to 65.1 in the mental component subscale (METRx-MD group: from 34.4 to 66.5 and from 44.87 to 56.7). Complications occurred in 3/37 patients in the PELD group and in 2/35 patients in the METRx-MD group in the peri-operative period. The mean return-to-work times were 37.5 days in the PELD group and 42.5 days in the METRx-MD group.
The outcomes for the PELD group are comparable to those for the METRx-MD group. It can thus be concluded that PELD for lumbar disk herniations may be performed safely and effectively. Also, PELD can be considered one of the treatment modalities of lumbar disk herniation.
PMCID: PMC4431005  PMID: 25983818
Percutaneous discectomy; Microdiscectomy; Lumbar disc herniation; VAS; ODI; SF-36
12.  Novel free-hand T1 pedicle screw method: Review of 44 consecutive cases 
Summary of Background Data:
Multilevel posterior cervical instrumented fusions are becoming more prevalent in current practice. Biomechanical characteristics of the cervicothoracic junction may necessitate extending the construct to upper thoracic segments. However, fixation in upper thoracic spine can be technically demanding owing to transitional anatomy while suboptimal placement facilitates vascular and neurologic complications. Thoracic instrumentation methods include free-hand, fluoroscopic guidance, and CT-based image guidance. However, fluoroscopy of upper thoracic spine is challenging secondary to vertebral geometry and patient positioning, while image-guided systems present substantial financial commitment and are not readily available at most centers. Additionally, imaging modalities increase radiation exposure to the patient and surgeon while potentially lengthening surgical time.
Materials and Methods:
Retrospective review of 44 consecutive patients undergoing a cervicothoracic fusion by a single surgeon using the novel free-hand T1 pedicle screw technique between June 2009 and November 2012. A starting point medial and cephalad to classic entry as well as new trajectory were utilized. No imaging modalities were employed during screw insertion. Postoperative CT scans were obtained on day 1. Screw accuracy was independently evaluated according to the Heary classification.
In total, 87 pedicle screws placed were at T1. Grade 1 placement occurred in 72 (82.8%) screws, Grade 2 in 4 (4.6%) screws and Grade 3 in 9 (10.3%) screws. All Grade 2 and 3 breaches were <2 mm except one Grade 3 screw breaching 2-4 mm laterally. Only two screws (2.3%) were noted to be Grade 4, both breaching medially by less than 2 mm. No new neurological deficits or returns to operating room took place postoperatively.
This modification of the traditional starting point and trajectory at T1 is safe and effective. It attenuates additional bone removal or imaging modalities while maintaining a high rate of successful screw placement compared to historical controls.
PMCID: PMC4173230  PMID: 25288835
Cervicothoracic; free-hand; pedicle screw; technique; thoracic; thoracic starting points
13.  Percutaneous discography: comparison of low-dose CT, fluoroscopy and MRI in the diagnosis of lumbar disc disruption 
European Spine Journal  2005;15(5):620-626.
Aim: To compare the diagnostic accuracy of low-dose computed tomography (CT), magnetic resonance imaging (MRI) and fluoroscopy in percutaneous discography in patients scheduled for lumbar spondylodesis. Material and methods: Within a prospective pilot study, 18 disc segments of 11 patients with radicular or pseudoradicular pain prior to anteroposterior spondylodesis were evaluated. After injection of a mixture of non-ionic iodine-containing contrast agent and gadolinium-based contrast medium into the disc spaces, all patients underwent conventional fluoroscopy, as well as low-dose CT and MRI. The occurrence of memory pain during contrast injection was recorded. CT, MRI and fluoroscopic images were analyzed independently by two readers blinded to the clinical findings. Results: There was 100% agreement between CT and MRI discography in the detection, localization and grading of degenerative changes. In contrast, conventional fluoroscopy identified only 9 of the 12 abnormal segments. Memory pain following puncture was identified in 3 of the 12 affected segments. Summary: Low-dose CT and MRI discography have a similar accuracy in the assessment of disc disruption and they are superior to fluoroscopic discography.
PMCID: PMC3489334  PMID: 16292635
Computed tomography; Low dose; Magnetic resonance imaging; Discography
14.  Outcomes of liver transplantation for end-stage biliary disease: A comparative study with end-stage liver disease 
AIM: To evaluate the outcomes of patients with end-stage biliary disease (ESBD) who underwent liver transplantation, to define the concept of ESBD, the criteria for patient selection and the optimal operation for decision-making.
METHODS: Between June 2002 and June 2014, 43 patients with ESBD from two Chinese organ transplantation centres were evaluated for liver transplantation. The causes of liver disease were primary biliary cirrhosis (n = 8), cholelithiasis (n = 8), congenital biliary atresia (n = 2), graft-related cholangiopathy (n = 18), Caroli’s disease (n = 2), iatrogenic bile duct injury (n = 2), primary sclerosing cholangitis (n = 1), intrahepatic bile duct paucity (n = 1) and Alagille’s syndrome (n = 1). The patients with ESBD were compared with an end-stage liver disease (ESLD) case control group during the same period, and the potential prognostic values of multiple demographic and clinical variables were assessed. The examined variables included recipient age, sex, pre-transplant clinical status, pre-transplant laboratory values, operation condition and postoperative complications, as well as patient and allograft survival rates. Survival analysis was performed using Kaplan-Meier curves, and the rates were compared using log-rank tests. All variables identified by univariate analysis with P values < 0.100 were subjected to multivariate analysis. A Cox proportional hazard regression model was used to determine the effect of the study variables on outcomes in the study group.
RESULTS: Patients in the ESBD group had lower model for end-stage liver disease (MELD)/paediatric end-stage liver disease (PELD) scores and a higher frequency of previous abdominal surgery compared to patients in the ESLD group (19.2 ± 6.6 vs 22.0 ± 6.5, P = 0.023 and 1.8 ± 1.3 vs 0.1 ± 0.2, P = 0.000). Moreover, the operation time and the time spent in intensive care were significantly higher in the ESBD group than in the ESLD group (527.4 ± 98.8 vs 443.0 ± 101.0, P = 0.000, and 12.74 ± 6.6 vs 10.0 ± 7.5, P = 0.000). The patient survival rate in the ESBD group was not significantly different from that of the ESBD group at 1, 3 and 5 years (ESBD: 90.7%, 88.4%, 79.4% vs ESLD: 84.9%, 80.92%, 79.0%, χ2 = 0.194, P = 0.660). The graft-survival rates were also similar between the two groups at 1, 3 and 5 years (ESBD: 90.7%, 85.2%, 72.7% vs ESLD: 84.9%, 81.0%, 77.5%, χ2 = 0.003, P = 0.958). Univariate analysis identified MELD/PELD score (HR = 1.213, 95%CI: 1.081-1.362, P = 0.001) and bleeding volume (HR = 0.103, 95%CI: 0.020-0.538, P = 0.007) as significant factors affecting the outcomes of patients in the ESBD group. However, multivariate analysis revealed that MELD/PELD score (HR = 1.132, 95%CI: 1.005-1.275, P = 0.041) was the only negative factor that was associated with short survival time.
CONCLUSION: MELD/PELD criteria do not adequately measure the clinical characteristics and staging of ESBD. The allocation system based on MELD/PELD criteria should be re-evaluated for patients with ESBD.
PMCID: PMC4445107  PMID: 26034365
Liver transplantation; End-stage biliary disease; Model for end-stage liver disease; Paediatric end-stage liver disease; Complication
15.  Role of high-field intraoperative magnetic resonance imaging on a multi-image fusion-guided stereotactic biopsy of the basal ganglia: A case report 
Oncology Letters  2014;9(1):223-226.
The aim of the present case study was to investigate the advantages of intraoperative magnetic resonance imaging (iMRI) on the real-time guidance and monitoring of a stereotactic biopsy. The study describes a patient with intracranial lesions, which were examined by conventional MRI and diffusion tensor imaging using a 1.5T intraoperative MRI system. The digital and pre-operative positron emission/computed tomography image data were transferred to a BrainLAB planning workstation, and a variety of images were automatically fused. The BrainLAB software was then used to reconstruct the corticospinal tract (CST) and create a three-dimensional display of the anatomical association between the CST and the brain lesions. A Leksell surgical planning workstation was used to identify the ideal target site and a reasonable needle track for the biopsy. The 1.5T iMRI was used to effectively monitor the intracranial condition during the brain biopsy procedure. Post-operatively, the original symptoms of the patient were not aggravated and no further neurological deficits were apparent. The histopathological diagnosis of non-Hodgkin’s B-cell lymphoma was made. Using high-field iMRI, the multi-image fusion-guided stereotactic brain biopsy allows for a higher positive rate of biopsy and a lower incidence of complications. The approach of combining multi-image fusion images with the frame-based stereotactic biopsy may be clinically useful for intracranial lesions of deep functional areas.
PMCID: PMC4246638  PMID: 25435963
intraoperative magnetic resonance imaging; multi-image fusion; stereotactic; biopsy
16.  Comparative Effectiveness of Frame-based, Frameless and Intraoperative MRI Guided Brain Biopsy Techniques 
World neurosurgery  2014;83(3):261-268.
Intraoperative MRI (IoMRI) guided brain biopsy provides a real time visual feedback of the lesion that is sampled during surgery. The objective of the study is to compare the diagnostic yield and safety profiles of ioMRI needle brain biopsy with two traditional brain biopsy methods: frame-based and frameless stereotactic brain biopsies.
A retrospective analysis from 288 consecutive needle brain biopsies in 277 patients undergoing stereotactic brain biopsy with any of the three biopsy methods at Brigham and Women's Hospital from 2000 to 2008 was performed. Variables such as age, sex, history of radiation and previous surgery, pathology results, complications and postoperative stays were analyzed.
Over the course of eight years, 288 brain biopsies were performed. 253 (87.8%) biopsies yielded positive diagnostic tissue. Young age (<40 years), history of brain radiation or surgery were significant negative predictors for a positive biopsy diagnostic yield. Excluding patients with prior radiation or surgeries, no significant difference in diagnostic yield was detected among the three groups, with frame-based, frameless and ioMRI guided needle biopsies yield 96.9%, 91.8% and 89.9% positive diagnostic yield, respectively. 19 biopsies (6.6%) were complicated by serious adverse events. The ioMRI-guided brain biopsy was associated with less serious adverse events and the shortest postoperative hospital stay.
Frame-based, frameless stereotactic and ioMRI guided brain needle biopsy have comparable diagnostic yield for patients with no prior treatments (either radiation or surgery). IoMRI guided brain biopsy is associated with fewer serious adverse events and shorter hospital stay.
PMCID: PMC4450019  PMID: 25088233
brain biopsy; frame-based; frameless stereotactic; intra-operative MRI
17.  Robotic System for MRI-Guided Stereotactic Neurosurgery 
Stereotaxy is a neurosurgical technique that can take several hours to reach a specific target, typically utilizing a mechanical frame and guided by preoperative imaging. An error in any one of the numerous steps or deviations of the target anatomy from the preoperative plan such as brain shift (up to 20 mm), may affect the targeting accuracy and thus the treatment effectiveness. Moreover, because the procedure is typically performed through a small burr hole opening in the skull that prevents tissue visualization, the intervention is basically “blind” for the operator with limited means of intraoperative confirmation that may result in reduced accuracy and safety. The presented system is intended to address the clinical needs for enhanced efficiency, accuracy, and safety of image-guided stereotactic neurosurgery for Deep Brain Stimulation (DBS) lead placement. The work describes a magnetic resonance imaging (MRI)-guided, robotically actuated stereotactic neural intervention system for deep brain stimulation procedure, which offers the potential of reducing procedure duration while improving targeting accuracy and enhancing safety. This is achieved through simultaneous robotic manipulation of the instrument and interactively updated in situ MRI guidance that enables visualization of the anatomy and interventional instrument. During simultaneous actuation and imaging, the system has demonstrated less than 15% signal-to-noise ratio (SNR) variation and less than 0.20% geometric distortion artifact without affecting the imaging usability to visualize and guide the procedure. Optical tracking and MRI phantom experiments streamline the clinical workflow of the prototype system, corroborating targeting accuracy with 3-axis root mean square error 1.38 ± 0.45 mm in tip position and 2.03 ± 0.58° in insertion angle.
PMCID: PMC4428978  PMID: 25376035
MRI-compatible robotics; robot-assisted surgery; image-guided therapy; stereotactic neurosurgery; deep brain stimulation
18.  An Evaluation of Image-Guided Technologies in the Placement of Anterior Thoracic Vertebral Body Screws in Spinal Trauma: A Cadaver Study 
Image guidance provides additional anatomic information to the surgeon, which may allow more accurate insertion of spinal implants. Imprecise placement of anterior thoracic screws places the spinal cord and paraspinal structures at risk for injury. Image guidance may afford a safety benefit to patients when anterior thoracic screws are required in the setting of spinal stabilization after trauma.
To compare the accuracy of anterior thoracic screw placement using standard fluoroscopy, computer-assisted fluoroscopic image guidance, Iso-C3D image guidance, and electromagnetic fluoroscopic image guidance.
Study Design:
A surgical simulation study in human cadaver spine specimens.
After an open thoracotomy approach, anterior thoracic screws were placed by experienced spine surgeons using 4 different image-guided techniques in 4 human cadaver thoracic spines. Screws were placed in the 9th, 10th, and 11th thoracic vertebrae of each specimen. The specimens were then examined with thin-cut computed tomography (CT) scans, and with sagittal and coronal reconstructions. Measurements included the distance of the screw from the spinal canal, the angle of the screw path in relation to a perpendicular to a line that bisects the spinous process, and the angle of screw divergence from the superior endplate.
There was no evidence of spinal canal penetrance with any of the image-guided techniques used to place anterior thoracic vertebral body screws. Screws inserted with standard fluoroscopy tended to aim anterolaterally by 18°. The image-guidance systems allowed more accurate placement of anterior thoracic screws in the transverse plane compared with standard fluoroscopy. There was no statistically significant difference in coronal plane screw angulation (angle of divergence with the superior endplate) between any of the imaging methods.
Spinal image-guidance systems may allow spine surgeons to place anterior thoracic screws more precisely, particularly in the axial plane. The improved accuracy of spinal implant insertion could ultimately provide a benefit to patient safety, especially in the setting of malaligned vertebral bodies after trauma.
PMCID: PMC1864896  PMID: 16396380
Image-guided surgery; StealthStation; FluoroNav; Iso-C3D; Spinal instrumentation; Thoracic spine fixation; Anterior thoracic screws; Spinal cord injuries; Trauma
19.  Alternative Method of Retrocrural Approach during Celiac Plexus Block Using a Bent Tip Needle 
The Korean Journal of Pain  2015;28(2):109-115.
This study sought to determine safe ranges of oblique angle, skin entry point and needle length by reviewing computed tomography (CT) scans and to evaluate the usefulness of a bent tip needle during celiac plexus block (CPB).
CT scans of 60 CPB patients were reviewed. Image of the uppermost margin of L2 vertebral body was used to measure the minimal and maximal oblique angles and the distances from the midline to skin puncture point. The imaginary needle trajectory distance was calculated by three-dimensional measurement. When the procedure was performed by using a 10° bent tip needle under a 20° oblique X-ray fluoroscopic view, the distance (GF/G'F) from the midline to the actual puncture site was measured.
The imaginary safe oblique angle range was 26.4-34.2° and 27.7-36.0° on the right and left, respectively. The distance from the midline to skin puncture point was 6.1-7.6 cm on the right and 6.3-7.6 cm on the left. The needle trajectory distance at minimal angle was 9.6-11.6 cm on the right and 9.5-11.5 cm on the left. The distance of GF/G'F was 5.1-6.5 cm and 5.0-6.4 cm on the right and left, respectively. All imaginary parameters were correlated with BMI except for GF/G'F. All complications were mild and transient.
We identified safe values of angles and distances using a straight needle. Furthermore, using a bent tip needle under a 20° oblique fluoroscopic view, we could safely perform CPB with smaller parameter values.
PMCID: PMC4387455  PMID: 25852832
Bent tip needle; Celiac plexus block; Fluoroscopy; Retrocrural approach; Visceral pain
20.  Electromagnetic Navigation in Minimally Invasive Spine Surgery: Results of a Cadaveric Study to Evaluate Percutaneous Pedicle Screw Insertion 
SAS Journal  2008;2(1):43-47.
This cadaveric study compared efficacy and safety of an electromagnetic (EM) guidance system versus conventional fluoroscopy for percutaneous pedicle screw fixation. As percutaneous pedicle screw fixation becomes increasingly common in spinal surgery, intraoperative imaging systems that maximize efficiency while minimizing radiation exposure and inaccurate trajectories will be progressively more important. Published studies have validated the safety of percutaneous screw fixation using conventional fluoroscopic guidance and frameless optical stereotaxy, though EM guidance systems have not been evaluated for percutaneous placement in the lumbosacral spine. The aim of the study was to evaluate the clinical applicability of an EM system for minimally invasive spine fusion in the lumbosacral spine.
Five human cadaveric specimens underwent bilateral lumbosacral percutaneous screw fixation from L1 to S1 using conventional anteroposterior (AP) and lateral fluoroscopic techniques on one side and 2-dimesional (2D) EM guidance on each matching side. Intraoperative efficiency was evaluated, and pedicle, vertebral, and critical breach rates were assessed on postoperative computed tomography (CT).
Overall mean fluoroscopy time per screw was 58.9 ± 44.7 seconds for conventional fluoroscopy compared to 27.4 ± 13.5 seconds for electromagnetic guidance (P = .0003). Pedicle, vertebral, and critical breach rates for the L1-S1 were 32.1%, 10.7%, and 25.0% for conventional fluoroscopy and 42.8%, 10.7%, and 14.1% for electromagnetic guidance (difference not statistically significant [ns]). In comparing critical breaches in the lumbar spine (L1-L5), there was a significant difference between 2-D EM guidance (0) and CF guidance (6) (P = .02).
Two-dimensional EM navigation provides a modality for lumbosacral percutaneous pedicle screw fixation that is more efficient and safer than conventional fluoroscopy. This data provides a foundation for further clinical trials of this technology.
Level of Evidence
Level 5 – Bench Research
PMCID: PMC4365653  PMID: 25802601
Minimally invasive spine fusion; percutaneous pedicle screw fixation; electromagnetic guidance
21.  Piriformis syndrome after percutaneous endoscopic lumbar discectomy via the posterolateral approach 
European Spine Journal  2011;20(10):1663-1668.
Percutaneous endoscopic lumbar discectomy (PELD) can be performed under local anesthesia with intravenous analgesics. To define the incidence of piriformis syndrome (PS) after PELD via the posterolateral approach under local anesthesia compared to that of general patients presenting with low back pain with/without lower leg pain. The incidence and time of occurrence of positive FAIR test after PELD within a 3-month follow-up period were evaluated retrospectively, and compared with the prevalence of general patients who visited the pain clinic for LBP with/without lower leg pain. Factors that may increase the incidence of PS after PELD were also evaluated. There was no patient with positive FAIR test immediately after PELD in the operation room and before walking. The prevalence of PS in general patients was 317/2,320 (13.7%); however, the incidence of PS after PELD within a 3-month follow-up period was 61/151 (40.4%), peaking at 32 days. High anxiety scale scores during operation led to increased incidence of PS after PELD. PELD under local anesthesia with high level of anxiety may increase the incidence of PS after walking, peaking around the first month, compared with the results for general patients with low back pain with/without lower leg pain.
PMCID: PMC3175870  PMID: 21416279
Diskectomy; Endoscopy; Lumbar vertebrae; Percutaneous; Piriformis syndrome
22.  Advanced Electrophysiologic Mapping Systems 
Executive Summary
To assess the effectiveness, cost-effectiveness, and demand in Ontario for catheter ablation of complex arrhythmias guided by advanced nonfluoroscopy mapping systems. Particular attention was paid to ablation for atrial fibrillation (AF).
Clinical Need
Tachycardia refers to a diverse group of arrhythmias characterized by heart rates that are greater than 100 beats per minute. It results from abnormal firing of electrical impulses from heart tissues or abnormal electrical pathways in the heart because of scars. Tachycardia may be asymptomatic, or it may adversely affect quality of life owing to symptoms such as palpitations, headaches, shortness of breath, weakness, dizziness, and syncope. Atrial fibrillation, the most common sustained arrhythmia, affects about 99,000 people in Ontario. It is associated with higher morbidity and mortality because of increased risk of stroke, embolism, and congestive heart failure. In atrial fibrillation, most of the abnormal arrhythmogenic foci are located inside the pulmonary veins, although the atrium may also be responsible for triggering or perpetuating atrial fibrillation. Ventricular tachycardia, often found in patients with ischemic heart disease and a history of myocardial infarction, is often life-threatening; it accounts for about 50% of sudden deaths.
Treatment of Tachycardia
The first line of treatment for tachycardia is antiarrhythmic drugs; for atrial fibrillation, anticoagulation drugs are also used to prevent stroke. For patients refractory to or unable to tolerate antiarrhythmic drugs, ablation of the arrhythmogenic heart tissues is the only option. Surgical ablation such as the Cox-Maze procedure is more invasive. Catheter ablation, involving the delivery of energy (most commonly radiofrequency) via a percutaneous catheter system guided by X-ray fluoroscopy, has been used in place of surgical ablation for many patients. However, this conventional approach in catheter ablation has not been found to be effective for the treatment of complex arrhythmias such as chronic atrial fibrillation or ventricular tachycardia. Advanced nonfluoroscopic mapping systems have been developed for guiding the ablation of these complex arrhythmias.
The Technology
Four nonfluoroscopic advanced mapping systems have been licensed by Health Canada:
CARTO EP mapping System (manufactured by Biosense Webster, CA) uses weak magnetic fields and a special mapping/ablation catheter with a magnetic sensor to locate the catheter and reconstruct a 3-dimensional geometry of the heart superimposed with colour-coded electric potential maps to guide ablation.
EnSite System (manufactured by Endocardial Solutions Inc., MN) includes a multi-electrode non-contact catheter that conducts simultaneous mapping. A processing unit uses the electrical data to computes more than 3,000 isopotential electrograms that are displayed on a reconstructed 3-dimensional geometry of the heart chamber. The navigational system, EnSite NavX, can be used separately with most mapping catheters.
The LocaLisa Intracardiac System (manufactured by Medtronics Inc, MN) is a navigational system that uses an electrical field to locate the mapping catheter. It reconstructs the location of the electrodes on the mapping catheter in 3-dimensional virtual space, thereby enabling an ablation catheter to be directed to the electrode that identifies abnormal electric potential.
Polar Constellation Advanced Mapping Catheter System (manufactured by Boston Scientific, MA) is a multielectrode basket catheter with 64 electrodes on 8 splines. Once deployed, each electrode is automatically traced. The information enables a 3-dimensional model of the basket catheter to be computed. Colour-coded activation maps are reconstructed online and displayed on a monitor. By using this catheter, a precise electrical map of the atrium can be obtained in several heartbeats.
Review Strategy
A systematic search of Cochrane, MEDLINE and EMBASE was conducted to identify studies that compared ablation guided by any of the advanced systems to fluoroscopy-guided ablation of tachycardia. English-language studies with sample sizes greater than or equal to 20 that were published between 2000 and 2005 were included. Observational studies on safety of advanced mapping systems and fluoroscopy were also included. Outcomes of interest were acute success, defined as termination of arrhythmia immediately following ablation; long-term success, defined as being arrhythmia free at follow-up; total procedure time; fluoroscopy time; radiation dose; number of radiofrequency pulses; complications; cost; and the cost-effectiveness ratio.
Quality of the individual studies was assessed using established criteria. Quality of the overall evidence was determined by applying the GRADE evaluation system. (3) Qualitative synthesis of the data was performed. Quantitative analysis using Revman 4.2 was performed when appropriate.
Quality of the Studies
Thirty-four studies met the inclusion criteria. These comprised 18 studies on CARTO (4 randomized controlled trials [RCTs] and 14 non-RCTs), 3 RCTs on EnSite NavX, 4 studies on LocaLisa Navigational System (1 RCT and 3 non-RCTs), 2 studies on EnSite and CARTO, 1 on Polar Constellation basket catheter, and 7 studies on radiation safety.
The quality of the studies ranged from moderate to low. Most of the studies had small sample sizes with selection bias, and there was no blinding of patients or care providers in any of the studies. Duration of follow-up ranged from 6 weeks to 29 months, with most having at least 6 months of follow-up. There was heterogeneity with respect to the approach to ablation, definition of success, and drug management before and after the ablation procedure.
Summary of Findings
Evidence is based on a small number of small RCTS and non-RCTS with methodological flaws.
Advanced nonfluoroscopy mapping/navigation systems provided real time 3-dimensional images with integration of anatomic and electrical potential information that enable better visualization of areas of interest for ablation
Advanced nonfluoroscopy mapping/navigation systems appear to be safe; they consistently shortened the fluoroscopy duration and radiation exposure.
Evidence suggests that nonfluoroscopy mapping and navigation systems may be used as adjuncts to rather than replacements for fluoroscopy in guiding the ablation of complex arrhythmias.
Most studies showed a nonsignificant trend toward lower overall failure rate for advanced mapping-guided ablation compared with fluoroscopy-guided mapping.
Pooled analyses of small RCTs and non-RCTs that compared fluoroscopy- with nonfluoroscopy-guided ablation of atrial fibrillation and atrial flutter showed that advanced nonfluoroscopy mapping and navigational systems:
Yielded acute success rates of 69% to 100%, not significantly different from fluoroscopy ablation.
Had overall failure rates at 3 months to 19 months of 1% to 40% (median 25%).
Resulted in a 10% relative reduction in overall failure rate for advanced mapping guided-ablation compared to fluoroscopy guided ablation for the treatment of atrial fibrillation.
Yielded added benefit over fluoroscopy in guiding the ablation of complex arrhythmia. The advanced systems were shown to reduce the arrhythmia burden and the need for antiarrhythmic drugs in patients with complex arrhythmia who had failed fluoroscopy-guided ablation
Based on predominantly observational studies, circumferential PV ablation guided by a nonfluoroscopy system was shown to do the following:
Result in freedom from atrial fibrillation (with or without antiarrhythmic drug) in 75% to 95% of patients (median 79%). This effect was maintained up to 28 months.
Result in freedom from atrial fibrillation without antiarrhythmic drugs in 47% to 95% of patients (median 63%).
Improve patient survival at 28 months after the procedure as compared with drug therapy.
Require special skills; patient outcomes are operator dependent, and there is a significant learning curve effect.
Complication rates of pulmonary vein ablation guided by an advanced mapping/navigation system ranged from 0% to 10% with a median of 6% during a follow-up period of 6 months to 29 months.
The complication rate of the study with the longest follow-up was 8%.
The most common complications of advanced catheter-guided ablation were stroke, transient ischemic attack, cardiac tamponade, myocardial infarction, atrial flutter, congestive heart failure, and pulmonary vein stenosis. A small number of cases with fatal atrial-esophageal fistula had been reported and were attributed to the high radiofrequency energy used rather than to the advanced mapping systems.
Economic Analysis
An Ontario-based economic analysis suggests that the cumulative incremental upfront costs of catheter ablation of atrial fibrillation guided by advanced nonfluoroscopy mapping could be recouped in 4.7 years through cost avoidance arising from less need for antiarrhythmic drugs and fewer hospitalization for stroke and heart failure.
Expert Opinion
Expert consultants to the Medical Advisory Secretariat noted the following:
Nonfluoroscopy mapping is not necessary for simple ablation procedures (e.g., typical flutter). However, it is essential in the ablation of complex arrhythmias including these:
Symptomatic, drug-refractory atrial fibrillation
Arrhythmias in people who have had surgery for congenital heart disease (e.g., macro re-entrant tachycardia in people who have had surgery for congenital heart disease).
Ventricular tachycardia due to myocardial infarction
Atypical atrial flutter
Advanced mapping systems represent an enabling technology in the ablation of complex arrhythmias. The ablation of these complex cases would not have been feasible or advisable with fluoroscopy-guided ablation and, therefore, comparative studies would not be feasible or ethical in such cases.
Many of the studies included patients with relatively simple arrhythmias (e.g., typical atrial flutter and atrial ventricular nodal re-entrant tachycardia), for which the success rates using the fluoroscopy approach were extremely high and unlikely to be improved upon using nonfluoroscopic mapping.
By age 50, almost 100% of people who have had surgery for congenital heart disease will develop arrhythmia.
Some centres are under greater pressure because of expertise in complex ablation procedures for subsets of patients.
The use of advanced mapping systems requires the support of additional electrophysiologic laboratory time and nursing time.
For patients suffering from symptomatic, drug-refractory atrial fibrillation and are otherwise healthy, catheter ablation offers a treatment option that is less invasive than is open surgical ablation.
Small RCTs that may have been limited by type 2 errors showed significant reductions in fluoroscopy exposure in nonfluoroscopy-guided ablation and a trend toward lower overall failure rate that did not reach statistical significance.
Pooled analysis suggests that advanced mapping systems may reduce the overall failure rate in the ablation of atrial fibrillation.
Observational studies suggest that ablation guided by complex mapping/navigation systems is a promising treatment for complex arrhythmias such as highly symptomatic, drug-refractory atrial fibrillation for which rate control is not an option
In people with atrial fibrillation, ablation guided by advanced nonfluoroscopy mapping resulted in arrhythmia free rates of 80% or higher, reduced mortality, and better quality of life at experienced centres.
Although generally safe, serious complications such as stroke, atrial-esophageal, and pulmonary vein stenosis had been reported following ablation procedures.
Experts advised that advanced mapping systems are also required for catheter ablation of:
Hemodynamically unstable ventricular tachycardia from ischemic heart disease
Macro re-entrant atrial tachycardia after surgical correction of congenital heart disease
Atypical atrial flutter
Catheter ablation of atrial fibrillation is still evolving, and it appears that different ablative techniques may be appropriate depending on the characteristics of the patient and the atrial fibrillation.
Data from centres that perform electrophysiological mapping suggest that patients with drug-refractory atrial fibrillation may be the largest group with unmet need for advanced mapping-guided catheter ablation in Ontario.
Nonfluoroscopy mapping-guided pulmonary vein ablation for the treatment of atrial fibrillation has a significant learning effect; therefore, it is advisable for the province to establish centres of excellence to ensure a critical volume, to gain efficiency and to minimize the need for antiarrhythmic drugs after ablation and the need for future repeat ablation procedures.
PMCID: PMC3379531  PMID: 23074499
23.  Computed tomography-guided vertebroplasty using a stereotactic guidance system (stereo-guide) 
In order to make it easy to perform computed tomography (CT)-guided vertebroplasty a stereotactic guidance system called the "stereo-guide" was designed. A method to perform CT-guided vertebroplasty using this system is described.
The device is a rectangular flat plastic block. One of the flat surfaces of the block has deeply grooved protractor markings at 5-degree intervals; ranging from 0 to 30 degrees. The procedure is performed on the CT table. Based on distances and angle measurements obtained from CT images the device is placed on an appropriate location on the back of the patient and the needle is advanced to the target through the pedicle guided by the grooves on the device. Ten procedures were performed in nine patients with lumbar and thoracic pathology.
The system was easy to use and proved to be accurate. No complication resulted from the procedure.
The stereo-guide proved to be simple and easy to use. Intraoperative scans helped to plan the trajectory and follow the injection of the cement.
PMCID: PMC2908353  PMID: 20657698
Computed tomography guidance; stereotactic; vertebral fracture; vertebroplasty
24.  Cardiac embolization of an implanted fiducial marker for hepatic stereotactic body radiotherapy: a case report 
In liver stereotactic body radiotherapy, reduction of normal tissue irradiation requires daily image guidance. This is typically accomplished by imaging a surrogate to the tumor. The surrogate is often an implanted metal fiducial marker. There are few reports addressing the specific risks of hepatic fiducial marker implantation. These risks are assumed to be similar to percutaneous liver biopsies which are associated with a 1-4% complication rate - almost always pain or bleeding. To the best of our knowledge, we present the first case of such a fiducial marker migrating to the heart.
Case presentation
An 81-year-old Caucasian man (5 years post-gastrectomy for a gastric adenocarcinoma) was referred post-second line palliative chemotherapy for radiotherapy of an isolated liver metastasis. It was decided to proceed with treatment and platinum fiducials were chosen for radiation targeting. Under local anesthesia, three Nester embolization coils (Cook Medical Inc., Bloomington, IN, USA) were implanted under computed tomography guidance. Before the placement of each coil, the location of the tip of the delivery needle was confirmed by computed tomography imaging. During the procedure, the third coil unexpectedly migrated through the hepatic vein to the inferior vena cava and lodged at the junction of the vena cava and the right atrium. The patient remained asymptomatic. He was immediately referred to angiography for extraction of the coil. Using fluoroscopic guidance, an EN Snare Retrieval System (Hatch Medical L.L.C., Snellville, GA, USA) was introduced through a jugular catheter; it successfully grasped the coil and the coil was removed. The patient was kept overnight for observation and no immediate or delayed complications were encountered due to the migration or retrieval of the coil. He subsequently went on to be treated using the remaining fiducials.
Implanted fiducial markers are increasingly used for stereotactic radiotherapy. There is sparse literature on the risks of such procedures. Although uncommon, the risk of migration does exist and therefore physicians (surgeons, oncologists and radiologists) and patients should be aware of this possibility.
PMCID: PMC2783068  PMID: 19946545
25.  Ultrasound as a Screening Tool for Performing Caudal Epidural Injections 
Iranian Journal of Radiology  2014;11(2):e13262.
The caudal approach to the epidural space has been used for decades to treat low back pain caused by lumbosacral root compression. The use of fluoroscopy during epidural steroid injection is the preferred method for placing the needle more accurately in the sacral hiatus, but it carries the risk of radiation hazard.
The aim of the study was to assess the anatomical structure of the sacral hiatus and the feasibility of caudal epidural injections under ultrasound guidance.
Patients and Methods:
Two hundred and forty patients (male = 100, female = 140) with low back pain and sciatica who were candidates for caudal epidural injection were enrolled into this study. Ultrasound images of the sacral hiatus and bilateral cornua were obtained by a real-time linear array ultrasound transducer. The distance between bilateral cornua and the anterior and posterior wall of the sacrum were measured at the base (sacral hiatus). Under the guide of ultrasonography, we defined the injection successful if turbulence of medication fluid was observed in the sacral canal, but correct placement of the needle and injectant was confirmed on fluoroscopic view as the gold standard technique.
The epidurogram showed that the injection was successful in 230 of the 240 patients (95.8%). In eight patients, the injection was not in the correct place in the sacral canal. The sacral hiatus could not be identified by ultrasound images in only two patients who had a closed sacral hiatus identified by fluoroscopy. The mean distance of the sacral hiatus was 4.7 ± 1.7 mm and the mean distance between bilateral cornua was 18.0 ± 2.8 mm. The mean duration of the procedure was 10.8 ± 6.8 minutes. No major complication was observed in the next month.
In conclusion, ultrasound could be used as a safe, fast and reliable modality to observe the anatomic variation of the sacral hiatus and to perform caudal epidural injections.
PMCID: PMC4090639  PMID: 25035698
Anesthesia, Caudal; Ultrasonography; Low Back Pain

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