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1.  Multidetector CT imaging of pleura: comparison of two contrast infusion protocols 
The British Journal of Radiology  2011;84(1005):796-799.
Objectives
Imaging of the pleura by multidetector CT (MDCT) can be challenging. There is no clear evidence or guidelines on contrast infusion parameters for imaging pleura. We compared two contrast protocols for assessing pleural pathology on MDCT.
Methods
This was a prospective study in which consecutive patients with MDCT for suspected pleural disease on chest radiograph were randomised into two groups. The first group received 150 ml of intravenous contrast at a rate of 2.5 ml s–1 and the second group received 100 ml at 2 ml s–1. Images were acquired after a 60 s delay. Hounsfield units of the pleura, thoracic aorta, main pulmonary artery, portal vein and superior mesenteric artery were measured and analysed by two independent readers.
Results
40 patients (20 in each group) who had pleural enhancement on MDCT were included for final analysis. The mean pleural enhancement value was 83 HU (Group A) vs 59 HU (Group B) (p = 0.0004). The mean aortic enhancement was 241 HU (A) vs 141 HU (B) (p<0.0001); main pulmonary artery enhancement was 208 HU (A) vs 139 HU (B) (p<0.0002); portal venous enhancement was 169 HU (A) vs 115 HU (B) (p<0.0001); and the superior mesenteric artery enhancement was 215 HU (A) vs 128 HU (B) (p<0.0001).
Conclusion
Enhancement of the pleura and major vessels was significantly higher in the group receiving more contrast at a greater infusion rate. This technique of a single scan through the entire pleural surface with a delayed acquisition is promising. When pleural disease is suspected, contrast infusion protocols should be modified to achieve the best results and clinicians should be encouraged to specifically request a “pleural CT”.
doi:10.1259/bjr/55980445
PMCID: PMC3473793  PMID: 21159803
2.  Imaging investigation of pancreatic cystic lesions and proposal for therapeutic guidelines 
World Journal of Radiology  2012;4(8):372-378.
AIM: To propose a diagnostic algorithm for preoperatively predicting the need for surgical intervention.
METHODS: The study included 56 patients (27 men and 29 women) with a final diagnosis of cystic pancreatic lesions. The following materials were used: ultrasonic equipment with 3.5 and 7 MHz linear, convex and biopsical transducers. Multidetector computed tomography (MDCT) investigations were performed using a 16-slice scanner. Images were obtained following the oral administration of 200 mL water and 100 mL intravenous iopamidol (300 mg/mL) administered by pump injector at a rate of 3 mL/s (40 and 60 s post-injection, respectively) using 0.5 mm detectors, reconstructed at 1 mm (pancreatic phase) or 2 mm (portal venous phase) increments. The table feed was 10 mm per rotation. Images were acquired in the pancreatic and portal venous phases of contrast enhancement. The “Chiba” needles 18, 20, 22, 23 G and an automatic aspiration system were used in conjunction with the following methods of guiding the interventional procedures: (1)“free-hand” biopsy and puncture method under ultrasound (US) or computed tomography (CT) control; (2) guiding method using biopsical transducer.
RESULTS: All 56 patients in this study underwent at least two cuts imaging survey methods, such as US, CT or magnetic resonance imaging (MRI). The most common preoperative diagnostic examination was US scan - 56 patients (100%). MDCT studies were conducted in 49 (87.50%) and MRI in 13 (23.21%). More than half of patients surveyed (37) underwent some type of interventional procedure: 25-fine-needle aspiration and 29-fine needle aspiration biopsy (FNAB), as part of the examination. Thirty-four patients of all 56 patients underwent surgery because of histological evidence of malignancy after the FNAB for cystic lesions of the pancreas. Distal pancreatectomy with splenectomy was the most common operative approach in 13 patients, followed by Whipple resection in 11 and distal pancreatectomy without splenectomy in 7. Three patients were treated with total pancreatectomy due to the presence of a multifocal mucinous neoplasm. Comparing the diagnostic results of US examination with those of MDCT examination and histological verification true positive results were found in 31 patients, true negative in 11 patients, false positive in 5 and false negative in 9 patients. Accordingly we estimated the power of the diagnostic imaging methods for cystic lesions of the pancreas. A specificity of 68.75%, sensitivity of 79.48%, accuracy of 75.00%, positive predictive value of 86.11% and negative predictive value of 55% were obtained. The power increased after applying invasive procedures with immunohistochemical analysis of CEA and P-53 (Fig. 4). In 15 patients with cytological feature of malignant tumour cells, the tumour markers were positive. In our opinion the higher the percentage of reacting cells the higher the percent of malignancy. In patients with clear symptoms and/or clear imaging features of malignant or premalignant cystic neoplasm, the need for surgery was confirmed by histological verification in 34 (60.71%) of cases.
CONCLUSION: By using the proposed algorithm, cystic mucinous tumors of the pancreas were detected and proper operative interventions would have been rendered with fewer diagnostic examinations.
doi:10.4329/wjr.v4.i8.372
PMCID: PMC3430734  PMID: 22937216
Pancreatic cystic neoplasm; Diagnostic intervention; Fine-needle biopsy
3.  Detection of small (≤ 2 cm) pancreatic adenocarcinoma and surrounding parenchyma: correlations between enhancement patterns at triphasic MDCT and histologic features 
BMC Gastroenterology  2014;14:16.
Background
The aim is to assess the time-density curves (TDCs) and correlate the histologic results for small (≤ 2 cm) PDA and surrounding parenchyma at triphasic Multidetector-row CT (MDCT).
Methods
Triphasic MDCT scans of 38 consecutive patients who underwent surgery for a small PDA were retrospectively reviewed. The TDCs were analyzed and compared with histologic examination of the PDA and pancreas upstream/downstream in all cases. Three enhancement patterns were identified: 1) enhancement peak during pancreatic parenchymal phase (PPP) followed by a rapid decline on portal venous phase (PVP) and delayed phase (DP) at 5 minutes (type 1 pattern: normal pancreas); 2) maximum enhancement in PVP that gradually decreases in DP (type 2 pattern: mild chronic pancreatitis or PDA with mild fibrous stroma); 3) progressive enhancement with maximum peak in DP (type 3 pattern: severe chronic pancreatitis or PDA with severe fibrous stroma). A p value less than 0.05 was considered statistically significant. Sensitivity was calculated for PDA detection and an attenuation difference with the surrounding tissue of at least 10 HU was considered.
Results
PDA showed type 2 pattern in 5/38 cases (13.2%) and type 3 pattern in 33/38 cases (86,8%). Pancreas upstream to the tumor had type 2 pattern in 20/38 cases (52,6%) and type 3 pattern in 18/38 cases (47,4%). Pancreas downstream to the tumor had type 1 pattern in 19/25 cases (76%) and type 2 pattern in 6/25 cases (24%). Attenuation difference between tumor and parenchyma upstream was higher of 10 UH on PPP in 31/38 patients (sensitivity = 81.6%), on PVP in 29/38 (sensitivity = 76.3%) and on DP in 17/38 (sensitivity = 44.7%). Attenuation difference between tumor and parenchyma downstream was higher of 10 UH on PPP in 25/25 patients (sensitivity = 100%), on PVP in 22/25 (sensitivity = 88%) and on DP in 20/25 (sensitivity = 80%). Small PDAs were isodense to the pancreas upstream to the tumor, and therefore unrecognizable, in 8 cases (8/38; 21%) at qualitative analysis and in 4 cases (4/38; 10,5%) at quantitative analysis.
Conclusions
The quantitative analysis increases the sensitivity for detection of small PDA at triphasic MDCT.
doi:10.1186/1471-230X-14-16
PMCID: PMC3903041  PMID: 24447719
Pancreas; Pancreas; Neoplasms; Helical Computed Tomography (CT); Triphasic Helical CT; Quantitative analysis
4.  MRI versus 64-row MDCT for diagnosis of hepatocellular carcinoma 
AIM: To compare the diagnostic capability of multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) for the detection of hepatocellular carcinoma (HCC) tumour nodules and their effect on patient management.
METHODS: A total of 28 patients (25 male, 3 female, mean age 67 ± 10.8 years) with biopsy-proven HCC were investigated with 64-row MDCT (slice 3 mm native, arterial and portal-venous phase, 120 mL Iomeprol, 4 mL/s, delay by bolus trigger) and MRI (T1fs fl2d TE/TR 2.72/129 ms, T2tse TE/TR 102/4000 ms, 5-phase dynamic contrast-enhanced T1fs fl3d TE/TR 1.56/4.6, Gadolinium-DTPA, slice 4 mm). Consensus reading of both modalities was used as reference. Tumour nodules were analyzed with respect to number, size, and location.
RESULTS: In total, 162 tumour nodules were detected by consensus reading. MRI detected significantly more tumour nodules (159 vs 123, P < 0.001) compared to MDCT, with the best sensitivity for early arterial phase MRI. False-negative CT findings included nodules ≤ 5 mm ( n = 5), ≤ 10 mm ( n = 17), ≤ 15 mm ( n = 12 ), ≤ 20 mm ( n = 4 ), and 1 nodule > 20 mm. MRI missed 2 nodules ≤ 10 mm and 1 nodule ≤ 15 mm. On MRI, nodule diameters were greater than on CT (29.2 ± 25.1 mm, range 5-140 mm vs 24.1 ± 22.7 mm, range 4-129 mm, P < 0.005). In 2 patients, MDCT showed only unilobar tumour spread, whereas MRI revealed additional nodules in the contralateral lobe. Detection of these nodules could have changed the therapeutic strategy.
CONCLUSION: Contrast-enhanced MRI is superior to 64-row MDCT for the detection of HCC nodules. Patients should be allocated to interventional or operative treatment according to a dedicated MRI-protocol.
doi:10.3748/wjg.15.6044
PMCID: PMC2797660  PMID: 20027676
American Association for the Study of Liver Diseases; European Association for the Study of the Liver; Hepatocellular carcinoma; Multidetector computed tomography; Magnetic resonance imaging
5.  Multi-Detector Computed Tomography Angiography for Coronary Artery Disease 
Executive Summary
Purpose
Computed tomography (CT) scanning continues to be an important modality for the diagnosis of injury and disease, most notably for indications of the head and abdomen. (1) According to a recent report published by the Canadian Institutes of Health Information, (1) there were about 10.3 scanners per million people in Canada as of January 2004. Ontario had the fewest number of CT scanners per million compared to the other provinces (8 CT scanners per million). The wait time for CT in Ontario of 5 weeks approaches the Canadian median of 6 weeks.
This health technology and policy appraisal systematically reviews the published literature on multidetector CT (MDCT) angiography as a diagnostic tool for the newest indication for CT, coronary artery disease (CAD), and will apply the results of the review to current health care practices in Ontario. This review does not evaluate MDCT to detect coronary calcification without contrast medium for CAD screening purposes.
The Technology
Compared with conventional CT scanning, MDCT can provide smaller pieces of information and can cover a larger area faster. (2) Advancing MDCT technology (8, 16, 32, 64 slice systems) is capable of producing more images in less time. For general CT scanning, this faster capability can reduce the time that patients must stay still during the procedure, thereby reducing potential movement artefact. However, the additional clinical utility of images obtained from faster scanners compared to the images obtained from conventional CT scanners for current CT indications (i.e., non-moving body parts) is not known.
There are suggestions that the new fast scanners can reduce wait times for general CT. MDCT angiography that utilizes a contrast medium, has been proposed as a minimally invasive replacement to coronary angiography to detect coronary artery disease. MDCT may take between 15 to 45 minutes; coronary angiography may take up to 1 hour.
Although 16-slice and 32-slice CT scanners have been available for a few years, 64-slice CT scanners were released only at the end of 2004.
Review Strategy
There are many proven, evidence-based indications for conventional CT. It is not clear how MDCT will add to the clinical utility and management of patients for established CT indications. Therefore, because cardiac imaging, specifically MDCT angiography, is a new indication for CT, this literature review focused on the safety, effectiveness, and cost-effectiveness of MDCT angiography compared with coronary angiography in the diagnosis and management of people with CAD.
This review asked the following questions:
Is the most recent MDCT angiography effective in the imaging of the coronary arteries compared with conventional angiography to correctly diagnose of significant (> 50% lumen reduction) CAD?
What is the utility of MDCT angiography in the management and treatment of patients with CAD?
How does MDCT angiography in the management and treatment of patients with CAD affect longterm outcomes?
The published literature from January 2003 to January 31, 2005 was searched for articles that focused on the detection of coronary artery disease using 16-slice CT or faster, compared with coronary angiography. The search yielded 138 articles; however, 125 were excluded because they did not meet the inclusion criteria (comparison with coronary angiography, diagnostic accuracy measures calculated, and a sample size of 20 or more). As screening for CAD is not advised, studies that utilized MDCT for this purpose or studies that utilized MDCT without contrast media were also excluded. Overall, 13 studies were included in this review.
Summary of Findings
The published literature focused on 16-slice CT angiography for the detection of CAD. Two abstracts that were presented at the 2005 European Congress of Radiology meeting in Vienna compared 64-slice CT angiography with coronary angiography.
The 13 studies focussing on 16-slice CT angiography were stratified into 2 groups: Group 1 included 9 studies that focused on the detection of CAD in symptomatic patients, and Group 2 included 4 studies that examined the use of 16-slice CT angiography to detect disease progression after cardiac interventions. The 2 abstracts on 64-slice CT angiography were presented separately, but were not critically appraised due to the lack of information provided in the abstracts.
16-Slice Computed Tomography Angiography
The STARD initiative to evaluate the reporting quality of studies that focus on diagnostic tests was used. Overall the studies were relatively small (fewer than 100 people), and only about one-half recruited consecutive patients. Most studies reported inclusion criteria, but 5 did not report exclusion criteria. In these 5, the patients were highly selected; therefore, how representative they are of the general population of people with suspicion if CAD or those with disease progression after cardiac intervention is questionable. In most studies, patients were either already taking, or were given, β-blockers to reduce their heart rates to improve image quality sufficiently. Only 6 of the 13 studies reported interobserver reliability quantitatively. The studies typically assessed the quality of the images obtained from 16-slice CT angiography, excluded those of poor quality, and compared the rest with the gold standard, coronary angiography. This practice necessarily inflated the diagnostic accuracy measures. Only 3 studies reported confidence intervals around their measures.
Evaluation of the studies in Group 1 reported variable sensitivity, from just over 60% to 96%, but a more stable specificity, at more than 95%. The false positive rate ranged from 5% to 8%, but the false negative rate was at best under 10% and at worst about 30%. This means that up to one-third of patients who have disease may be missed. These patients may therefore progress to a more severe level of disease and require more invasive procedures. The calculated positive and negative likelihood ratios across the studies suggested that 16-slice CT angiography may be useful to detect disease, but it is not useful to rule out disease. The prevalence of disease, measured by conventional coronoary angiography, was from 50% to 80% across the studies in this review. Overall, 16-slice CT angiography may be useful, but there is no conclusive evidence to suggest that it is equivalent to or better than coronary angiography to detect CAD in symptomatic patients.
In the 4 studies in Group 2, sensitivity and specificity were both reported at more than 95% (except for 1 that reported sensitivity of about 80%). The positive and negative likelihood ratios suggested that the test might be useful to detect disease progression in patients who had cardiac interventions. However, 2 of the 4 studies recruited patients who had been asymptomatic since their intervention. As many of the patients studied were not symptomatic, the relevance of performing MDCT angiography in the patient population may be in question.
64-Slice Computed Tomography Angiography
An analysis from the interim results based on 2 abstracts revealed that 64-slice CT angiography was insufficient compared to coronary angiography and may not be better than 16-slice CT angiography to detect CAD.
Conclusions
Cardiac imaging is a relatively new indication for CT. A systematic review of the literature was performed from 2003 to January 2005 to determine the effectiveness of MDCT angiography (16-slice and 64-slice) compared to coronary angiography to detect CAD. At the time of this report, there was no published literature on 64-slice CT for any indications.
Based on this review, the Medical Advisory Secretariat concluded that there is insufficient evidence to suggest that 16-slice or 64-slice CT angiography is equal to or better than coronary angiography to diagnose CAD in people with symptoms or to detect disease progression in patients who had previous cardiac interventions. An analysis of the evidence suggested that in investigating suspicion of CAD, a substantial number of patients would be missed. This means that these people would not be appropriately treated. These patients might progress to more severe disease and possibly more adverse events. Overall, the clinical utility of MDCT in patient management and long-term outcomes is unknown.
Based on the current evidence, it is unlikely that CT angiography will replace coronary angiography completely, but will probably be used adjunctively with other cardiac diagnostic tests until more definitive evidence is published.
If multi-slice CT scanners are used for coronary angiography in Ontario, access to the current compliment of CT scanners will necessarily increase wait times for general CT scanning. It is unlikely that these newer-generation scanners will improve patient throughput, despite the claim that they are faster.
Screening for CAD in asymptomatic patients and who have no history of ischemic heart disease using any modality is not advised, based on the World Health Organization criteria for screening. Therefore, this review did not examine the use of multi-slice CT for this purpose.
PMCID: PMC3382628  PMID: 23074474
6.  Hepatocellular carcinoma in cirrhotic patients at multidetector CT: hepatic venous phase versus delayed phase for the detection of tumour washout 
The British Journal of Radiology  2011;84(1001):403-412.
Objectives
Our aim was to compare retrospectively hepatic venous and delayed phase images for the detection of tumour washout during multiphasic multidetector row CT (MDCT) of the liver in patients with hepatocellular carcinoma (HCC).
Methods
30 cirrhotic patients underwent multiphasic MDCT in the 90 days before liver transplantation. MDCT was performed before contrast medium administration and during hepatic arterial hepatic venous and delayed phases, images were obtained at 12, 55 and 120 s after trigger threshold. Two radiologists qualitatively evaluated images for lesion attenuation. Tumour washout was evaluated subjectively and objectively. Tumour-to-liver contrast (TLC) was measured for all pathologically proven HCCs.
Results
48 HCCs were detected at MDCT. 46 of the 48 tumours (96%) appeared as either hyper- or isoattenuating during the hepatic arterial phase subjective washout was present in 15 HCCs (33%) during the hepatic venous phase and in 35 (76%) during the delayed phase (p<0.001, McNemar’s test). Objective washout was present in 30 of the 46 HCCs (65%) during the hepatic venous phase and in 42 of the HCCs (91%) during the delayed phase (p=0.001). The delayed phase yielded significantly higher mean TLC absolute values compared with the hepatic venous phase (−16.1±10.8 HU vs −10.5±10.2 HU; p<0.001).
Conclusions
The delayed phase is superior to the hepatic venous phase for detection of tumour washout of pathologically proven HCC in cirrhotic patients.
doi:10.1259/bjr/18329080
PMCID: PMC3473662  PMID: 21081569
7.  Detection of hypervascular hepatocellular carcinoma: Comparison of multi-detector CT with digital subtraction angiography and Lipiodol CT 
AIM: The purpose of this study was to compare the diagnostic accuracy of biphasic multi-detector row helical computed tomography (MDCT), digital subtraction angiography (DSA) and Lipiodol computed tomography (CT) in detection of hypervascular hepatocellular carcinoma (HCC).
METHODS: Twenty-eight patients with nodular HCC underwent biphasic MDCT examination: hepatic arterial phase (HAP) 25 s and portal venous phase (PVP) 70 s after injection of the contrast medium (1.5 mL/kg). They also underwent hepatic angiography and intra-arterial infusion of iodized oil. Lipiodol CT was performed 3-4 wk after infusion. MDCT images were compared with DSA and Lipiodol CT images for detection of hepatic nodules.
RESULTS: The three imaging techniques had the same sensitivity in detecting nodules >20 mm in diameter. There was no significant difference in the sensitivity among HAP-MDCT, Lipiodol CT and DSA for nodules of 10-20 mm in diameter. For the nodules <10 mm in diameter, HAP-MDCT identified 47, Lipiodol CT detected 27 (χ2 = 11.3, P = 0.005<0.01, HAP-MDCT vs Lipiodol CT) and DSA detected 16 (χ2 = 9.09, P = 0.005<0.01 vs Lipiodol CT and χ2 = 29.03, P = 0.005<0.01vs HAP-MDCT). However, six nodules <10 mm in diameter were detected only by Lipiodol CT.
CONCLUSION: MDCT and Lipiodol CT are two complementary modalities. At present, MDCT does not obviate the need for DSA and subsequent Lipiodol CT as a preoperative examination for HCC.
doi:10.3748/wjg.v11.i2.200
PMCID: PMC4205401  PMID: 15633215
Hypervascular hepatocellular carcinoma; Multi-detector CT; Digital subtraction angiography; Lipiodol CT
8.  Imaging of early pancreatic cancer on multidetector row helical computed tomography 
The British Journal of Radiology  2010;83(994):823-830.
Early pancreatic cancer is small and limited to the pancreas. In contrast, small pancreatic cancer may include peripancreatic vasculature or metastasis involvement. This study evaluates images of early pancreatic cancer on multidetector CT (MDCT) using contrast-enhanced multiphasic imaging, and post-processed pancreatic duct images. CT findings and pathological features were analysed in eight patients with early pancreatic cancer. Pathological evaluation included location, size and histological grading of the tumour. MDCT evaluation covered the maximum diameter of the main pancreatic duct (MPD), stenosis or obstruction of the MPD, loss of normal lobar texture and associated pancreatitis. Attenuation differences between normal pancreatic parenchyma and the tumour (AD–PT) were also measured. Focal stenosis or obstruction of the MPD with dilatation of the distal MPD was demonstrated in all patients. Associated pancreatitis occurred in six patients with tumours measuring 12 mm or greater. Loss of normal lobar texture was recognised in four cases with the tumour measuring 14 mm or greater. Statistically, low-attenuated lesions and high-attenuated lesions differed with respect to the tumour size (p<0.01), and a positive relationship was demonstrated between the tumour size and AD–PT (r = 0.84). In seven cases, AD–PT is higher during the arterial phase than the pancreatic phase. Early pancreatic cancer appears as low attenuation on early phase, and as high- to iso-attenuation during the pancreatic and delayed phases in respect to the tumour size. Focal stenosis or obstruction of the MPD with dilatation of the distal MPD observed on curved reformation imaging seems important in the diagnosis of early pancreatic cancer.
doi:10.1259/bjr/80905803
PMCID: PMC3473757  PMID: 20442278
9.  Capability of multidetector CT to diagnose hepatocellular carcinoma-associated arterioportal shunt 
AIM: To investigate the capability of multidetector CT (MDCT) to diagnose HCC-associated arterioportal shunt (APS).
METHODS: Two hundred and eighty-two patients with HCC received both thin-slice and enhancement MDCT scanning at early hepatic arterial phase, late hepatic arterial phase and portal venous phase, and digital subtract angiography (DSA) examination. Images were analyzed jointly by two experienced radiologists blinded to the opposite examination results, including the existence or not of APS, shunt locations, types and degrees of APS, with or without thrombosis.
RESULTS: There were 56 APS associated with HCC, including 48 central, seven peripheral and one mixed, or 42 severe, seven moderate, seven mild APS. Forty-one severe, seven moderate and central APS were all revealed with MDCT and DSA. Seven mild and peripheral APS were all displayed with MDCT; only five of them displayed DSA, two faint shunt APS associated with massive HCC were missed. One mixed APS was demonstrated as severe combined with mild shunt with both MDCT and DSA.
CONCLUSION: MDCT could diagnose not only DSA revealed APS, but also missed mild and peripheral APS with DSA due to faint shunt associated with massive HCC, is a simple, effective and noninvasive new technique for diagnosis of HCC-associated APS.
doi:10.3748/wjg.v11.i17.2666
PMCID: PMC4305763  PMID: 15849831
Hepatocelluar carcinoma; Arterioportal shunt; CT
10.  Enhancement patterns of hepatocellular carcinomas on multiphasic multidetector row CT: comparison with pathological differentiation 
The British Journal of Radiology  2012;85(1017):e573-e583.
Objective
The objective of this study was to determine the incidence of typical and atypical enhancement patterns of hepatocellular carcinomas (HCCs) on multiphasic multidetector row CT (MDCT) and to correlate the enhancement patterns and morphological image findings of HCC with the degree of tumour differentiation.
Methods
MDCT images of 217 patients with 243 surgically proven HCCs were evaluated through consensus reading by two radiologists. Our MDCT protocol was composed of precontrast, arterial, portal and delayed phases. The reviewers analysed the CT images for degree of attenuation; relative timing of washout; presence of dysmorphic intratumoral vessels, aneurysms and necrosis; tumour size; tumour margin; presence of pseudocapsule; intratumoral heterogeneity; and determined enhancement pattern. The imaging features were correlated with tumour differentiation using Fisher's exact test or the χ2 test.
Results
Among 243 HCCs, 137 (56.4%) showed the typical enhancement pattern of HCC, which is arterial enhancement and washout on portal or equilibrium phase images. In the arterial phase, 190 of 243 (78.2%) HCCs showed hypervascularity, with approximately three quarters of poorly differentiated (PD) (34 of 45, 75.6%) and moderately differentiated (MD) HCCs (92 of 123, 74.8%) showing washout during the portal or delayed phases, vs only 50% of well-differentiated (WD) HCCs (11 of 22; p<0.048). The presence of intratumoral vessels and aneurysms, tumour necrosis, attenuation of precontrast, the relative timing of washout, intratumoral attenuation heterogeneity, tumour margin and tumour size were correlated with the pathological differentiation of HCCs (p<0.05).
Conclusion
A typical enhancement of HCCs on MDCT was not unusual (43.6%) and WD and PD HCCs account for most of the atypical enhancement patterns. Early washout favoured MD and PD HCCs rather than WD HCCs, whereas in our study the presence of intratumoral aneurysm was a highly specific finding for PD HCC.
doi:10.1259/bjr/86767895
PMCID: PMC3487070  PMID: 22919011
11.  Characteristics of paraesophageal varices: A study with 64-row multidetector computed tomography portal venography 
AIM: To identify the characteristics of morphology, location and collateral circulation involved in paraesophageal varices (para-EV) of portal hypertension patients with 64-row multidetector computed tomography (MDCT).
METHODS: Fifty-two of 501 patients with portal hypertensive cirrhosis accompanied with esophageal varices were selected for 64-row MDCT examination after the observation of para-EV. The CT protocol included unenhanced, arterial and portal phases with a slice thickness of 0.625 mm and a scanning field of 2 cm above the bifurcation to the lower edge of kidney. The CT portal venography (CTPV) was reformatted on AW4.3 workstation. The characteristics of origination, location, morphology and collateral circulation in para-EV were observed.
RESULTS: Among the 52 cases of para-EV, 50 showed the originations from the posterior branch of left gastric vein, while the others from the anterior branch. Fifty cases demonstrated their locations close to the esophageal-gastric junction, and the other two cases were extended to the inferior bifurcation of the trachea. The circuitous pattern was observed in 16 cases, while reticulated pattern was seen in 36 cases. Collateral circulation identified 4 cases of single periesophageal varices (peri-EV) communication, 3 cases of single hemiazygous vein, one case of single inferior vena cava, 41 cases of mixed type (collateral communications of at least 2 of above mentioned types) and 3 cases of undetermined communications. Among all the cases, 43 patients showed the communications between para-EV and peri-EV, while hemiazygous vein (43 cases) and inferior vena cava (5 cases) were also involved.
CONCLUSION: Sixty-four-row multidetector computed tomography portal venography could display the location, morphology, origin, and collateral types of para-EV, which provides important and referable information for clinical management and disease prognosis.
doi:10.3748/wjg.14.5331
PMCID: PMC2744066  PMID: 18785288
Computer tomography; Portal venography; Paraesophageal varices; Hepatic cirrhosis; Portal hypertension
12.  Evaluating the effect of two different anesthetic protocols on 64-MDCT coronary angiography in dogs 
Heart rate is a major factor influencing diagnostic image quality in computed tomographic coronary artery angiography (MDCT-CA) with an ideal heart rate of 60–65 beats/minute in humans. Using standardized contrast bolus volume, two different clinically applicable anesthetic protocols were compared for effect on cardiovascular parameters and 64-MDCT-CA quality in ten healthy dogs. The protocol using midazolam/fentanyl (A) was hypothesized to result in adequate reduction of heart rate achieving adequate image quality for MDCT-CA studies and having low impact on blood pressure, where as the protocol utilizing dexmedetomidine (B) was expected to result in reduction of heart rate to the target heart range resulting in excellent image quality while possibly showing undesirable effect on the blood pressure values measured.
Heart rate was 80.6 ± 7.5bpm with protocol A and 79.2 ± 14.2bpm with protocol B during image acquisition (P=1). R-R intervals allowing for the best depiction of the individual coronary artery segments were found in the end diastolic period and varied between the 70–95% interval. Diagnostic quality was rated excellent, good and moderate in the majority of the segments evaluated, with higher scores given for more proximal segments and lower for more distal segments respectively. Blur was the most commonly observed artifact and most affected the distal segments. There was no significant difference for the optimal reconstruction interval, diagnostic quality and measured length individual segments or proximal diameter of the coronary arteries between both protocols (P=1). Both anesthetic protocols and the standardized bolus volume allow for diagnostic quality coronary 64-MDCT-CA exams.
doi:10.1111/vru.12185
PMCID: PMC4297233  PMID: 25065815
Heart; computed tomography; dexmedetomidine; midazolam; fentanyl
13.  Early and Delayed Myocardial Enhancement in Myocardial Infarction Using Two-Phase Contrast-Enhanced Multidetector-Row CT 
Korean Journal of Radiology  2007;8(2):94-102.
Objective
The purpose of this study was to describe the myocardial enhancement patterns in patients with myocardial infarction using two-phase contrast-enhanced multidetector-row computed tomography (MDCT).
Materials and Methods
Twenty-three patients with clinically proven myocardial infarction (17 acute myocardial infarction [AMI] and 6 chronic myocardial infarction [CMI]) were examined with two-phase contrast-enhanced ECG-gated MDCT. The presence, location, and patterns of myocardial enhancement on two-phase MDCT images were compared with infarcted myocardial territories determined by using electrocardiogram, echocardiography, thallium-201 single photon emission computed tomography, catheter and MDCT coronary angiography.
Results
After clinical assessment, the presence of myocardial infarctions were found in 27 territories (19 AMI and 8 CMI) of 23 patients. Early perfusion defects were observed in 30 territories of all 23 patients. Three territories not corresponding to a myocardial infarction were detected in three patients with AMI and were associated with artifacts. Fourteen of perfusion defects were in the left anterior descending artery territory, four in the left circumflex artery territory, and nine in the right coronary artery territory. Delayed enhancement was observed in 25 territories (17 AMI and 8 CMI) of 21 patients. Delayed enhancement patterns were variable. Transmural early perfusion defects (n =12) were closely associated with transmural late enhancement (n = 5) and subendocardial residual defect with subepicardial late enhancement (n = 5).
Conclusion
Myocardial infarction showed early perfusion defects and variable delayed enhancement patterns on two-phase contrast-enhanced MDCT. Delayed enhancement technique of MDCT could provide additional information of the location and extent of infarcted myocardium, and could be useful to plan appropriate therapeutic strategies in patients with AMI.
doi:10.3348/kjr.2007.8.2.94
PMCID: PMC2626780  PMID: 17420626
Computed tomography (CT), multidetector-row; Ischemic heart disease; Myocardium, Infarction; Myocardium, CT; Heart, CT
14.  Accuracy of routine multidetector computed tomography to identify arterial variants in patients scheduled for pancreaticoduodenectomy 
AIM: To assess the efficacy of cross-sectional multidetector computed tomography (MDCT) imaging without arterial reconstruction to identify aberrant right hepatic artery (RHA) and celiac artery stenosis (CAS) in patients scheduled for pancreaticoduodenectomy.
METHODS: Patients with peri-ampullary and pancreatic head tumors who underwent routine preoperative MDCT and subsequent computed tomography (CT) angiography (CTA), conventional angiography or pancreaticoduodenectomy between September 2007 and August 2013 were identified. Retrospective analysis of imaging data was undertaken using CTA, conventional angiographic and surgical findings as the reference standards. The accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of MDCT in evaluation of aberrant RHA and CAS were calculated.
RESULTS: A group of 458 patients met the inclusion criteria of this study to detect aberrant RHA, and 181 cases were included to identify CAS. Fifty-four (11.8%) patients were confirmed to have aberrant RHA, while 12 (6.6%) patients with CAS were demonstrated. MDCT yielded an accuracy of 98.5%, sensitivity of 96.3% and specificity of 98.8% in the detection of aberrant RHA. The sensitivity, specificity, PPV and NPV of MDCT for detecting CAS were 58.3%, 98.2%, 70% and 97.1%, respectively.
CONCLUSION: Routine MDCT is recommended such that surgeons and radiologists be alerted to the importance of arterial variants on preoperative CT scans in patients scheduled for pancreaticoduodenectomy.
doi:10.3748/wjg.v21.i3.969
PMCID: PMC4299351  PMID: 25624732
Pancreaticoduodenectomy; Aberrant hepatic artery; Celiac artery stenosis; Multidetector computed tomography; Angiography
15.  Predictive value of multi-detector computed tomography for accurate diagnosis of serous cystadenoma: Radiologic-pathologic correlation 
AIM: To identify multi-detector computed tomography (MDCT) features most predictive of serous cystadenomas (SCAs), correlating with histopathology, and to study the impact of cyst size and MDCT technique on reader performance.
METHODS: The MDCT scans of 164 patients with surgically verified pancreatic cystic lesions were reviewed by two readers to study the predictive value of various morphological features for establishing a diagnosis of SCAs. Accuracy in lesion characterization and reader confidence were correlated with lesion size (≤ 3 cm or ≥ 3 cm) and scanning protocols (dedicated vs routine).
RESULTS: 28/164 cysts (mean size, 39 mm; range, 8-92 mm) were diagnosed as SCA on pathology. The MDCT features predictive of diagnosis of SCA were microcystic appearance (22/28, 78.6%), surface lobulations (25/28, 89.3%) and central scar (9/28, 32.4%). Stepwise logistic regression analysis showed that only microcystic appearance was significant for CT diagnosis of SCA (P = 0.0001). The sensitivity, specificity and PPV of central scar and of combined microcystic appearance and lobulations were 32.4%/100%/100% and 68%/100%/100%, respectively. The reader confidence was higher for lesions > 3 cm (P = 0.02) and for MDCT scans performed using thin collimation (1.25-2.5 mm) compared to routine 5 mm collimation exams (P > 0.05).
CONCLUSION: Central scar on MDCT is diagnostic of SCA but is seen in only one third of SCAs. Microcystic morphology is the most significant CT feature in diagnosis of SCA. A combination of microcystic appearance and surface lobulations offers accuracy comparable to central scar with higher sensitivity.
doi:10.3748/wjg.15.2739
PMCID: PMC2695889  PMID: 19522024
Pancreas; Serous cystadenoma; Multi-detector computed tomography; Central scar; Lobulations; Microcystic
16.  Imaging features of solid pseudopapillary tumor of the pancreas on multi-detector row computed tomography 
AIM: To retrospectively analyze the imaging features of solid-pseudopapillary tumors (SPTs) of the pancreas on multi-detector row computed tomography (MDCT) and define the imaging findings suggestive of malignant potential.
METHODS: A total of 24 consecutive cases with surgically and pathologically confirmed SPTs of the pancreas underwent preoperative abdominal MDCT studies in our hospital. All axial CT images, CT angiographic images, and coronally and sagittally reformed images were obtained. The images were retrospectively reviewed at interactive picture archiving and communication system workstations.
RESULTS: Of the 24 cases of SPTs, 11 cases (45.8%) occurred in the pancreatic head and seven (29.1%) in the tail. Eighteen were pathologically diagnosed as benign and six as malignant. MDCT diagnosis of SPTs was well correlated with the surgical and pathological results (Kappa = 0.6, P < 0.05). The size of SPTs ranged from 3 to 15 cm (mean, 5.8 cm). When the size of the tumor was greater than 6 cm (including 6 cm), the possibilities of vascular (8 vs 1) and capsular invasion (9 vs 0) increased significantly (P < 0.05). Two pathologically benign cases with vascular invasion and disrupted capsule on MDCT presented with local recurrence and hepatic metastases during follow-up about 1 year after the resection of the primary tumors.
CONCLUSION: Vascular and capsular invasion with superimposed spread into the adjacent pancreatic parenchyma and nearby structures in SPTs of the pancreas can be accurately revealed by MDCT preoperatively. These imaging findings are predictive of the malignant potential associated with the aggressive behavior of the tumor, even in the pathologically benign cases.
doi:10.3748/wjg.15.829
PMCID: PMC2653382  PMID: 19230043
Solid pseudopapillary tumor; Pancreas; Multi-detector row computed tomography; Malignant potential; Aggressive behaviors
17.  Effect of Thin Overlapping Reconstruction on the Attenuation of Small (≤ 3 cm) Renal Cysts in the Nephrographic Phase of MDCT: a Phantom Study 
Korean Journal of Radiology  2006;7(4):275-280.
Objective
To evaluate the effect of thin overlapping reconstruction on the attenuation of small (≤ 3 cm) renal cysts in the nephrographic phase of multidetector CT (MDCT).
Materials and Methods
We scanned a phantom kidney containing spheres of various sizes (10, 20, and 30 mm) using both 4- and 16-channel MDCT scanners, and reconstructed images with various slice thickness (T, mm) and intervals (I, mm). The attenuation increase (AI) was measured for each sphere in 240-HU diluted solution of contrast material and compared with the attenuation in 35-HU solution.
Results
On the 4-channel MDCT, thin overlapping reconstruction (T/I = 3/1, compared with 5/5) lowered the AI as much as 17 HU in the 10 mm-sphere and 6 HU in the 20 mm-sphere (p < 0.05). Thin slicing alone was also effective; however overlapping alone was not. On the 16-channel MDCT, AI in the 10 mm-sphere was significantly lower than on the 4-channel MDCT with T/I = 5/5 (p < 0.05), however thinner slicing or overlapping did not affect the attenuation significantly in all of the spheres.
Conclusion
The effect of thin overlapping reconstruction on minimizing falsely elevated attenuation in the nephrographic phase was significant only in cysts ≤ 20 mm on the 4-channel MDCT.
doi:10.3348/kjr.2006.7.4.275
PMCID: PMC2667614  PMID: 17143031
Kidney; Cyst; Computed tomography (CT); Pseudoenhancement
18.  Comparison of pancreatic acinar cell carcinoma and adenocarcinoma using multidetector-row computed tomography 
AIM: To distinguish acinar cell carcinoma (ACC) from pancreatic adenocarcinoma (AC) by comparing their computed tomography findings.
METHODS: Patients with ACC and AC were identified on the basis of results obtained using surgically resected pancreatectomy specimens. The preoperative computer tomographic images of 6 acinar cell carcinoma patients and 67 pancreatic adenocarcinoma patients in 4 phases (non-contrast, arterial, portal venous, and delayed phase) were compared. The scan delay times were 40, 70, and 120 s for each contrast-enhanced phase. The visual pattern, tomographic attenuation value, and time attenuation curve were assessed and compared between AC and ACC cases using the χ2 test, Wilcoxon signed-rank test, and Mann Whitney U test.
RESULTS: The adenocarcinomas tended to be hypodense in all 4 phases. The acinar cell carcinomas also tended to be hypodense in the 3 contrast-enhanced phases, although their computed tomographic attenuation values were higher. Further, 5 of the 6 acinar cell carcinomas (83%) were isodense in the non-contrast phase. The time attenuation curve of the adenocarcinomas showed a gradual increase through the 4 phases, and all adenocarcinomas showed peak enhancement during the delayed phase. The time attenuation curve of the acinar cell carcinomas showed peak enhancement during the portal venous phase in 4 cases and during the arterial phase in 2 cases. None of the 6 acinar cell carcinomas showed peak enhancement during the delayed phase.
CONCLUSION: The tumor density in the non-contrast phase and time attenuation curve pattern clearly differ between acinar cell carcinomas and adenocarcinomas, and multidetector-row computed tomography can thus distinguish these tumors.
doi:10.3748/wjg.v19.i34.5713
PMCID: PMC3769910  PMID: 24039366
Pancreatic acinar cell carcinoma; Pancreatic adenocarcinoma; Multidetector-row computed tomography; Visual pattern; Time attenuation curve
19.  Prevalence of Unsuspected Pancreatic Cysts on MDCT 
OBJECTIVE
Current generation MDCT technology facilitates identification of small, nonenhancing lesions in the pancreas. The objective of this study was to determine the prevalence of findings of unsuspected pancreatic cysts on 16-MDCT in a population of adult out-patients imaged for disease unrelated to the pancreas.
MATERIALS AND METHODS
Contrast-enhanced MDCT scans of the abdomen were reviewed from 2,832 consecutive examinations to identify pancreatic cysts. Patients with a history of pancreatic lesions or predisposing factors for pancreatic disease or who were referred for pancreatic CT were excluded.
RESULTS
A total of 73 patients had pancreatic cysts, representing a prevalence of 2.6 per 100 patients (95% CI, 2.0–3.2). Cysts ranged in size from 2 to 38 mm (mean, 8.9 mm) and were solitary in 85% of cases. Analysis of demographic information showed a strong correlation between pancreatic cysts and age, with no cysts identified among patients under 40 years and a prevalence of 8.7 per 100 (95% CI, 4.6–12.9) in individuals from 80 to 89 years. After controlling for age, cysts were more common in individuals of the Asian race than all other race categories, with an odds ratio of 3.57 (95% CI, 1.05–12.13). There was no difference by sex in the prevalence of cysts (p = 0.527); however, cysts were on average 3.6 mm larger (p = 0.014) in men than women.
CONCLUSION
In this outpatient population, the prevalence of unsuspected pancreatic cysts identified on 16-MDCT was 2.6%. Cyst presence strongly correlated with increasing age and the Asian race.
doi:10.2214/AJR.07.3340
PMCID: PMC2692243  PMID: 18716113
CT; incidence; MDCT; pancreatic cyst; prevalence
20.  80-kVp CT Using Iterative Reconstruction in Image Space Algorithm for the Detection of Hypervascular Hepatocellular Carcinoma: Phantom and Initial Clinical Experience 
Korean Journal of Radiology  2012;13(2):152-164.
Objective
To investigate whether the low-tube-voltage (80-kVp), intermediate-tube-current (340-mAs) MDCT using the Iterative Reconstruction in Image Space (IRIS) algorithm improves lesion-to-liver contrast at reduced radiation dosage while maintaining acceptable image noise in the detection of hepatocellular carcinomas (HCC) in thin (mean body mass index, 24 ± 0.4 kg/m2) adults.
Subjects and Methods
A phantom simulating the liver with HCC was scanned at 50-400 mAs for 80, 100, 120 and 140-kVp. In addition, fifty patients with HCC who underwent multiphasic liver CT using dual-energy (80-kVp and 140-kVp) arterial scans were enrolled. Virtual 120-kVP scans (protocol A) and 80-kVp scans (protocol B) of the late arterial phase were reconstructed with filtered back-projection (FBP), while corresponding 80-kVp scans were reconstructed with IRIS (protocol C). Contrast-to-noise ratio (CNR) of HCCs and abdominal organs were assessed quantitatively, whereas lesion conspicuity, image noise, and overall image quality were assessed qualitatively.
Results
IRIS effectively reduced image noise, and yielded 29% higher CNR than the FBP at equivalent tube voltage and current in the phantom study. In the quantitative patient study, protocol C helped improve CNR by 51% and 172% than protocols A and B (p < 0.001), respectively, at equivalent radiation dosage. In the qualitative study, protocol C acquired the highest score for lesion conspicuity albeit with an inferior score to protocol A for overall image quality (p < 0.001). Mean effective dose was 2.63-mSv with protocol A and 1.12-mSv with protocols B and C.
Conclusion
CT using the low-tube-voltage, intermediate-tube-current and IRIS help improve lesion-to-liver CNR of HCC in thin adults during the arterial phase at a lower radiation dose when compared with the standard technique using 120-kVp and FBP.
doi:10.3348/kjr.2012.13.2.152
PMCID: PMC3303898  PMID: 22438682
Hepatocellular carcinoma; Low tube voltage; Iterative reconstruction; 80-kVp; Computed tomography; Image quality
21.  Multidetector Computed Tomography for Coronary Artery Disease Screening in Asymptomatic Populations 
Executive Summary
Objective
This evidence-based health technology assessment systematically reviewed the published literature on multidetector computed tomography (MDCT) angiography (with contrast) as a diagnostic tool for coronary artery disease (CAD), and applied the results of the assessment to health care practices in Ontario.
Clinical Need
Coronary artery disease is the leading cause of death in the western world. Occlusion of coronary arteries reduces coronary blood flow and oxygen delivery to the myocardium (heart muscle). The rupture of an unstable atherosclerotic plaque may result in myocardial infarction. If left untreated, CAD can result in heart failure and, subsequently, death. According to the Heart and Stroke Foundation of Canada, 54% of all cardiovascular deaths are due to CAD. Patient characteristics (e.g., age, sex, and genetics), underlying clinical conditions that predispose to cardiac conditions (e.g., diabetes, hypertension, and elevated cholesterol), lifestyle characteristics, (e.g., obesity, smoking, and physical inactivity), and, more recently, determinants of health (e.g., socioeconomic status) may predict the risk of getting CAD.
In 2004/2005, The Ontario government funded approximately 15,400 percutaneous (through the skin) coronary interventions and 7,840 coronary bypass procedures for the treatment of CAD. These numbers are expected to reach 22,355 for percutaneous coronary interventions and 12,323 for coronary bypass procedures in 2006/2007. It was noted that more than one-half of all first coronary events occur in people without symptoms of CAD. In Ontario in 2000/2001, $457.9 million (Cdn) was spent on invasive ($237.4 million) and noninvasive ($220.5 million) cardiac services. The use of noninvasive cardiac tests, in particular, is rising rapidly.
The Technology
Computed tomography (CT) is a medical imaging method employing tomography where digital geometry processing is used to generate a 3-dimensional image of the internals of an object from a large series of 2-dimensional X-ray images taken around a single axis of rotation. Multidetector computed tomography is performed for noninvasive imaging of the coronary arteries. Computer software quantifies the amount of calcium within the coronary arteries and calculates a coronary artery calcium score.
Compared with conventional CT scanning, MDCT can provide smaller pieces of information and cover a larger area faster. Advanced MDCT technology (that is, 8-, 16-, 32-, and 64-slice systems) can produce more images in less time. For general CT scanning, this faster capability can reduce the length of time people are required to be still during the procedure and thereby reduce potential movement artifact. However, the additional clinical utility of images obtained from faster scanners compared with the images obtained from conventional CT scanners for current CT indications (i.e., nonmoving body parts) is unknown.
Review Strategy
The Medical Advisory Secretariat completed a computer-aided search limited to English-language studies in humans from 1998 to 2007 in multiple medical literature databases, including MEDLINE, EMBASE, The Cochrane Library, and INAHTA/CRD. Case reports, letters, editorials, nonsystematic reviews, and comments were excluded. Additional studies that met the inclusion and exclusion criteria were obtained from reference lists of included studies. Inclusion and exclusion criteria were applied to the results according to the criteria listed below.
The Grading of Recommendations Assessment, Development and Evaluation (GRADE) system was used to evaluate the overall quality of the body of evidence (defined as 1 or more studies) supporting the research questions explored in this systematic review.
Summary of Findings and Conclusions
Screening the asymptomatic population for CAD using MDCT does not meet World Health Organization criteria for screening; hence, it is not justifiable. Coronary artery calcification measured by MDCT is a good predictor of future cardiovascular events. However, MDCT exhibits only moderately high sensitivity and specificity for detection of CAD in an asymptomatic population. If population-based screening were implemented, a high rate of false positives would result in increased downstream costs and interventions. Additionally, some cases of CAD would be missed, as they may not be developed, or not yet have progressed to detectable levels. There is no evidence for the impact of screening on patient management. Cardiovascular risk factors are positively associated with the presence of coronary artery calcification and cardiovascular events; however, risk factor stratification to identify high-risk asymptomatic individuals is unclear given the current evidence-base.
Safety of MDCT screening is also an issue because of the introduction of increased radiation doses for the initial screening scan and possible follow-up interventions.
No large randomized controlled trials of MDCT screening have been published, which indicates an important area of future research.
Lastly, the policy implications for MDCT screening for CAD in the asymptomatic population are significant. There is no evidence on the long-term implications of screening, and the potential impact on the resources of the health care system is considerable.
PMCID: PMC3377586  PMID: 23074503
22.  Evaluation of Reperfused Myocardial Infarction by Low-Dose Multidetector Computed Tomography Using Prospective Electrocardiography (ECG)-Triggering: Comparison with Magnetic Resonance Imaging 
Yonsei Medical Journal  2010;51(5):683-691.
Purpose
To evaluate the potential of prospective electrocardiography (ECG)-gated 64-slice multidetector computed tomography (MDCT) for evaluation of myocardial enhancement, infarct size, and stent patency after percutaneous coronary intervention (PCI) with stenting in patients with myocardial infarction.
Materials and Methods
Seventeen patients who were admitted with acute myocardial infarction were examined with prospective ECG-gated 64-slice cardiac MDCT and magnetic resonance (MR) imaging after reperfusion using PCI with stenting. Cardiac MDCT was performed with two different phases: arterial and delayed phases. We evaluated the stent patency on the arterial phase, and nonviable myocardium on the delayed phase of computed tomography (CT) image, and they were compared with the results from the delayed MR images.
Results
Total mean radiation dose was 7.7 ± 0.5 mSv on the two phases of CT images. All patients except one showed good patency of the stent at the culprit lesion on the arterial phase CT images. All patients had hyperenhanced area on the delayed phase CT images, which correlated well with those on the delayed phase MR images, with a mean difference of 1.6% (20 ± 10% vs. 22 ± 10%, r = 0.935, p = 0.10). Delayed MR images had a better contrast-to-noise ratio (CNR) than delayed CT images (27.1 ± 17.8% vs. 4.3 ± 2.1%, p < 0.001).
Conclusion
Prospective ECG-gated 64-slice MDCT provides the potential to evaluate myocardial viability on delayed phase as well as for stent patency on arterial phase with an acceptable radiation dose after PCI with stenting in patients with myocardial infarction.
doi:10.3349/ymj.2010.51.5.683
PMCID: PMC2908876  PMID: 20635442
Prospective ECG-gated MDCT; magnetic resonance imaging; myocardial infarction; delayed enhancement imaging
23.  Validation of Multi-Detector Computed Tomography as a Non-Invasive Method for Measuring Ovarian Volume in Macaques (Macaca fascicularis) 
American journal of primatology  2010;72(6):530-538.
The purpose of this study was to validate low radiation dose, contrast-enhanced, multi-detector computed tomography (MDCT) as a non-invasive method for measuring ovarian volume in macaques. Computed tomography scans of four known-volume phantoms and nine mature female cynomolgus macaques were acquired using a previously described, low radiation dose scanning protocol, intravenous contrast enhancement, and a 32-slice MDCT scanner. Immediately following MDCT, ovaries were surgically removed and the ovarian weights were measured. The ovarian volumes were determined using water displacement. A veterinary radiologist who was unaware of actual volumes measured ovarian CT volumes three times, using a laptop computer, pen display tablet, hand-traced regions of interest, and free image analysis software. A statistician selected and performed all tests comparing the actual and CT data. Ovaries were successfully located in all MDCT scans. The iliac arteries and veins, uterus, fallopian tubes, cervix, ureters, urinary bladder, rectum, and colon were also consistently visualized. Large antral follicles were detected in six ovaries. Phantom mean CT volume was 0.702±SD 0.504 cc and the mean actual volume was 0.743±SD 0.526 cc. Ovary mean CT volume was 0.258±SD 0.159 cc and mean water displacement volume was 0.257±SD 0.145 cc. For phantoms, the mean coefficient of variation for CT volumes was 2.5%. For ovaries, the least squares mean coefficient of variation for CT volumes was 5.4%. The ovarian CT volume was significantly associated with actual ovarian volume (ICC coefficient 0.79, regression coefficient 0.5, P = 0.0006) and the actual ovarian weight (ICC coefficient 0.62, regression coefficient 0.6, P = 0.015). There was no association between the CT volume accuracy and mean ovarian CT density (degree of intravenous contrast enhancement), and there was no proportional or fixed bias in the CT volume measurements. Findings from this study indicate that MDCT is a valid non-invasive technique for measuring the ovarian volume in macaques.
doi:10.1002/ajp.20807
PMCID: PMC3741054  PMID: 20131358
macaque; menopause; ovary volume; computed tomography; MDCT
24.  Discordance between anatomical and functional coronary stenosis severity 
Netherlands Heart Journal  2007;15(1):5-11.
Background.
New developments have made 16-slice multidetector computed tomography (MDCT) a promising technique for detecting significant coronary stenoses. At present, there is a paucity of data on the relation between fractional flow reserve (FFR) measurement and MDCT stenosis detection.
Objective.
The aim of this study was to investigate the relation between the anatomical severity of coronary artery disease detected by MDCT and functional severity measured by fractional flow reserve (FFR).
Methods.
We studied 53 patients (39 men and 14 women, age 62.5±8.1 years) with single-vessel disease scheduled for percutaneous coronary intervention (PCI). All patients underwent MDCT scanning one day prior to PCI and FFR was measured before PCI in the target vessel.
Results.
MDCT analysis could be performed in 52 of 53 patients (98.1%) and all patients had adequate FFR and quantitative coronary angiography (QCA) measurements. The mean stenosis diameters calculated by MDCT and QCA were 67.0±11.6% and 60.8±11.6% respectively. No significant relation was found between MDCT and QCA (r=0.22, p=0.12) The mean FFR in all patients was 0.67±0.18. A relation of r=-0.46 (p=0.0006) between QCA and FFR was found. In contrast, no relation between MDCT and FFR could be demonstrated (r=–0.09, p=0.50). Furthermore, a high incidence of false-positive and false-negative findings was present in both diagnostic modalities.
Conclusion.
There is no clear relation between the anatomical and functional severity of coronary artery disease as defined by MDCT and FFR. Therefore, functional assessment of coronary artery disease remains mandatory for clinical decisionmaking. (Neth Heart J 2007;15:5-11.)
PMCID: PMC1847721  PMID: 17612701
coronary arteriosclerosis; coronary artery disease; tomography (computed); fractional flow reserve
25.  Optimising the scan delay for arterial phase imaging of the liver using the bolus tracking technique 
Objective:
To optimize the delay time before the initiation of arterial phase scan in the detection of focal liver lesions in contrast enhanced 5 phase liver CT using the bolus tracking technique.
Patients and Methods:
Delay - the interval between threshold enhancement of 100 hounsfield unit (HU) in the abdominal aorta and commencement of the first arterial phase scan. Using a 16 slice CT scanner, a plain CT of the liver was done followed by an intravenous bolus of 120 ml nonionic iodinated contrast media (370 mg I/ml) at the rate of 4 mL/s. The second phase scan started immediately after the first phase scan. The portal venous and delay phases were obtained at a fixed delay of 60 s and 90 s from the beginning of contrast injection. Contrast enhancement index (CEI) and subjective visual conspicuity scores for each lesion were compared among the three groups.
Results:
84 lesions (11 hepatocellular carcinomas, 17 hemangiomas, 39 other hypervascular lesions and 45 cysts) were evaluated. CEI for hepatocellular carcinomas appears to be higher during the first arterial phase in the 6 seconds delay group. No significant difference in CEI and mean conspicuity scores among the three groups for hemangioma, other hypervascular lesions and cysts.
Conclusion:
The conspicuity of hepatocellular carcinomas appeared better during the early arterial phase using a bolus tracking technique with a scan delay of 6 seconds from the 100 HU threshold in the abdominal aorta.
doi:10.2349/biij.7.2.e12
PMCID: PMC3265150  PMID: 22287986
Arterial phase imaging of the liver; bolus tracking technique

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