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author:("machat, Josef")
1.  Prevalence and Risk Factors of Carotid Vessel Wall Inflammation in Coronary Artery Disease Patients 
JACC. Cardiovascular imaging  2011;4(11):1195-1205.
We investigated the prevalence and clinical risk factors of carotid vessel wall inflammation by means of 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) in a population consisting of coronary artery disease (CAD) patients.
The atherosclerotic disease process is characterized by infiltration and retention of oxidized lipids in the artery wall, triggering a disproportionate inflammatory response. Efforts have been made to use noninvasive imaging to quantify this inflammatory response in the vessel wall. Recently, carotid FDG-PET has been shown to reflect the metabolic rate of glucose, a process known to be enhanced in inflamed tissue.
Carotid inflammation was quantified in 82 CAD patients (age 62 ± 10 years) as the maximum target-to-background ratio (wholevesselTBRmax). Furthermore, we assessed the maximal standardized uptake value values (wholevesselSUVmax), the single hottest segment (SHS), and the percent active segments (PAS) of the FDG uptake in the artery wall, measured by FDG-PET.
Whole-vessel TBRmax > 1.8 was present in 67%, > 2.0 in 39%, > 2.2 in 23%, and > 2.4 in 12% of the population. Multiple linear regression analysis with backward elimination revealed that body mass index (BMI) ≥ 30 kg/m2 (p < 0.0001), age > 65 years (p = 0.01), smoking (p = 0.02), and hypertension (p = 0.01) were associated with wholevesselTBRmax. The number of components of the metabolic syndrome was also associated with wholevesselTBRmax (p = 0.02). In similar analyses, wholevesselSUVmax was associated with BMI ≥30 kg/m2 (p < 0.0001), age > 65 years (p = 0.004), male gender (p = 0.02), and hypertension (p = 0.04); SHS with BMI ≥30 kg/m2 (p < 0.0001), age >65 years (p = 0.02), smoking (p = 0.04), and hypertension (p = 0.05); PAS with BMI ≥30 kg/m2 (p = 0.001), smoking (p = 0.03), and hypertension (p = 0.01).
Carotid inflammation as revealed by FDG-PET is highly prevalent in the CAD population and is associated with obesity, age over 65 years, history of hypertension, smoking, and male gender. Artery wall FDG uptake increased when components of the metabolic syndrome clustered.
PMCID: PMC4120023  PMID: 22093271
atherosclerosis; FDG-PET; inflammation; metabolic syndrome; obesity
2.  PET/CT presentation of primary effusion lymphoma-like lymphoma unrelated to human herpes virus 8, a rare NHL subtype 
We present a 71-year-old female with human herpes virus 8 (HHV8)-unrelated primary effusion lymphoma (PEL)-like lymphoma. Dyspnea and pericardial effusion led to pericardiocentesis, diagnosing diffuse large B-cell lymphoma. She underwent positron emission tomography/computed tomography (PET/CT), which demonstrated hypermetabolic pericardial, pleural, and ascites fluid without lymphadenopathy elsewhere. Malignant fluid in the absence of lymphadenopathy is a hallmark of PEL. PEL is associated with immunodeficiency states such as acquired immunodeficiency syndrome (AIDS) and infectious agents such as HHV8. Our patient had no such history and had not received immunosuppressive chemotherapy. We present the PET/CT findings of this rare case of HHV8-unrelated PEL-like lymphoma.
PMCID: PMC4157198  PMID: 25210290
Human herpes virus 8; malignant pericardial effusion; positron emission tomography/computed tomography; primary effusion lymphoma
3.  Arterial and Fat Tissue Inflammation are Highly Correlated - A Prospective 18F-FDG PET/CT Study 
There is evidence that the link between obesity and cardiovascular disease might relate to inflammation in both fat tissue and the arterial wall. 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) uptake is a surrogate marker of vessel wall inflammation. The aim of the study was to measure FDG uptake in both regions using PET and identify links between adipose and arterial inflammation.
173 cardiovascular patients were prospectively imaged with FDG-PET/CT. Arterial FDG uptake was measured in the carotid arteries and ascending aorta. The same was done in fat tissue in the neck, the pre-sternal region (all subcutaneous) and the pericardium. FDG uptake wasquantified as average maximal target-to-background ratio (meanTBRmax).Multivariate regression analyses were performed to identify significant associations between arterial and adipose tissue FDG uptake and clinical variables as given by the standardized correlation coefficient (β).
FDG uptake values within all fat tissue regions were highly predictive of vascular FDG uptake in both the carotids (neck subcutaneous: β:0.262, p<0.0001) and aorta (chest pericardial: β:0.220, p=0.008 and chest subcutaneous: β:0.193, p=0.019). Obesity was significantly associated with elevated FDG uptake in adipose tissue (neck subcutaneous: β:0.470, p<0.0001; chest subcutaneous: β:0.619, p=0.028; chest pericardial: β:0.978, p=0.035).
FDG uptake in diverse fat tissue regions was significantly associated with arterial FDG uptake, a reasonable surrogate of inflammation. Increasing body weight significantly predicted the level of fatty inflammation. FDG-PET therefore provides imaging evidence for an inflammatory link between fat tissue and the vasculature in patients with cardiovascular disease.
PMCID: PMC4024167  PMID: 24442596
FDG-PET; Inflammation; Atherosclerosis; Fat Tissue; Carotid Arteries; Aorta
4.  Optimizing 18F-FDG PET/CT Imaging of Vessel Wall Inflammation –The Impact of 18F-FDG Circulation Time, Injected Dose, Uptake Parameters, and Fasting Blood Glucose Levels 
18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) is increasingly used for imaging of vessel wall inflammation. However, limited data is available regarding the impact of methodological variables, i. e. patient’s pre-scan fasting glucose, the FDG circulation time, the injected FDG dose, and of different FDG uptake parameters, in vascular FDG-PET imaging.
195 patients underwent vascular FDG-PET/CT of the aorta and the carotids. Arterial standard uptake values (meanSUVmax) as well as target-to-background-ratios (meanTBRmax) and the FDG blood pool activity in the superior vein cava (SVC) and the jugular veins (JV) were quantified. Vascular FDG uptake classified according to tertiles of patient’s pre-scan fasting glucose levels, the FDG circulation time, and the injected FDG dose was compared using ANOVA. Multivariate regression analyses were performed to identify the potential impact of all variables described on the arterial and blood pool FDG uptake.
Tertile analyses revealed FDG circulation times of about 2.5 h and prescan glucose levels of less than 7.0 mmol/l showing favorable relations between the arterial and blood pool FDG uptake. FDG circulation times showed negative associations with the aortic meanSUVmax values as well as SVC- and JV FDG blood pool activity but a positive correlation with the aortic- and carotid meanTBRmax values. Pre-scan glucose was negatively associated with aortic- and carotid meanTBRmax and carotid meanSUVmax values, but correlated positively with the SVC blood pool uptake. Injected FDG dose failed to show any significant association with the vascular FDG uptake.
FDG circulation times and pre-scan blood glucose levels significantly impact FDG uptake within the aortic and carotid wall and may bias the results of image interpretation in patients undergoing vascular FDG-PET/CT. FDG dose injected was less critical. Therefore, circulation times of about 2.5 h and pre-scan glucose levels less than 7.0 mmol/l should be preferred in this setting.
PMCID: PMC4024166  PMID: 24271038
FDG-PET; FDG Dose; FDG Circulation Time; Pre-scan Glucose; Vessel Wall Inflammation
5.  Preclinical evaluation of MR-attenuation correction versus CT-attenuation correction on a sequential whole-body MR/PET scanner 
Investigative radiology  2013;48(5):313-322.
The application of attenuation correction for combined MR/PET systems is still a major challenge for accurate quantitative PET. CT attenuation correction (CTAC) is the current clinical standard for PET/CT scans. MR, unlike CT, has no direct information about photon attenuation but rather proton densities. On combined MR/PET scanners, MR-based attenuation correction (MRAC) consists of assigning empirical attenuation coefficients to MR signal intensities. The objective of the current study was to evaluate the MRAC implemented on the combined MR/PET scanner versus the CTAC with the same PET data in an animal model.
MR/PET acquisition was performed using a clinically approved sequential MR/PET scanner (Philips Ingenuity TF). CT and MR/PET images of 20 NZW rabbits were retrospectively analyzed. Animals were positioned on a customized animal bed to avoid movement between CT and MR/PET scanners. PET images from both methods (MRAC and CTAC) were generated. Voxel-by-voxel and region-of-interest (ROI) analyses were performed to determine differences in standardized uptake values (SUV). ROIs were drawn on the coregistered CT images for aorta, liver, kidney, spine and soft tissue (muscle) and superimposed on the PET images.
Voxel-by-voxel comparison of PET showed excellent correlation between MRAC and CTAC SUV values (R=0.99, p<0.0001). The mean of the difference of SUVs between all respective MRAC and CTAC voxels was −0.94% (−0.06±0.30SD), confirming slight underestimation of MRAC. The ROI-based comparison similarly showed MRAC SUV values were underestimated compared to CTAC. The mean difference between MRAC and CTAC for all ROIs was 10.8% (−0.08±0.06SD, R=0.99, p< 0.0001) and −9.7% (−0.15±0.12SD, R=0.99, p<0.0001) for SUVmean and SUVmax, respectively. The highest differences were found in the spine (SUVmean −26.1% (−0.11)) and areas close to large bones such as the back muscles (SUVmean −16.8% (−0.04)).
In this study, we have compared MRAC and CTAC methods for PET attenuation correction in an animal model. We have confirmed that the MRAC method implemented on a sequential MR/PET scanner underestimates PET values by less than 10% in most regions, except areas containing or close to large bone structures such as the spine or the back muscles. Bone segmentation is therefore suggested to be included in the MR attenuation map in order to minimize the quantification error of MRAC methods compared to the gold standard CTAC. Further clinical studies need to be carried out to validate the clinical use of MRAC.
PMCID: PMC3638002  PMID: 23296082
6.  A consecutive case series experience with [18 F] florbetapir PET imaging in an urban dementia center: impact on quality of life, decision making, and disposition 
Identification and quantification of fibrillar amyloid in brain using positron emission tomography (PET) imaging and Amyvid™ ([18 F] Amyvid, [18 F] florbetapir, 18 F-AV-45) was recently approved by the US Food and Drug Administration as a clinical tool to estimate brain amyloid burden in patients being evaluated for cognitive impairment or dementia. Imaging with [18 F] florbetapir offers in vivo confirmation of the presence of cerebral amyloidosis and may increase the accuracy of the diagnosis and likely cause of cognitive impairment (CI) or dementia. Most importantly, amyloid imaging may improve certainty of etiology in situations where the differential diagnosis cannot be resolved on the basis of standard clinical and laboratory criteria.
A consecutive case series of 30 patients (age 50-89; 16 M/14 F) were clinically evaluated at a cognitive evaluation center of urban dementia center and referred for [18 F] florbetapir PET imaging as part of a comprehensive dementia workup. Evaluation included neurological examination and neuropsychological assessment by dementia experts. [18 F] florbetapir PET scans were read by trained nuclear medicine physicians using the qualitative binary approach. Scans were rated as either positive or negative for the presence of cerebral amyloidosis. In addition to a comprehensive dementia evaluation, post [18 F] florbetapir PET imaging results caused diagnoses to be changed in 10 patients and clarified in 9 patients. Four patients presenting with SCI were negative for amyloidosis. These results show that [18 F] florbetapir PET imaging added diagnostic clarification and discrimination in over half of the patients evaluated.
Amyloid imaging provided novel and essential data that: (1) caused diagnosis to be revised; and/or (2) prevented the initiation of incorrect or suboptimal treatment; and/or (3) avoided inappropriate referral to an anti-amyloid clinical trial.
PMCID: PMC3913628  PMID: 24484858
Amyvid™; Florbetapir; PET; Clinical series; Alzheimer’s disease; Neuroimaging
7.  Impact of Non-Insulin Dependent Type-2 Diabetes on Carotid Wall 18F-FDG-PET Uptake 
Objective & Background
Inflammation is a pivotal process in the progression of atherosclerosis, which can be non-invasively imaged by 18F-fluorodeoxyglucose positron emission tomography (FDG-PET). In this study, the impact of non-insulin dependent type-2 diabetes on carotid wall FDG uptake in patients with documented or suspected cardiovascular disease was evaluated.
Carotid artery wall FDG uptake was quantified in 134 patients (age 60.2±9.7 years; diabetic subjects: n=43). The pre-scan glucose (gluc) level corrected mean of the maximum standardized uptake value (SUV) values (meanSUVgluc), mean of the maximum target-to-background ratio (meanTBRgluc), and Single Hottest Segment (SHSgluc) of FDG uptake in the artery wall were calculated. Associations between FDG uptake, the presence of risk factors for atherosclerosis, and diabetes were then assessed by multiple regression analysis with backward elimination.
We demonstrated a significant association between diabetes and FDG uptake in the arterial wall (diabetes: meanSUVgluc; β=0.324, meanTBRgluc; β=0.317, and SHSgluc; β=0.298; for all: p<0.0001, respectively). In addition, in diabetic patients, both body mass index (BMI) ≥30 kg/m2 (BMI ≥30 kg/m2: meanSUVgluc; β=0.4, meanTBRgluc; β=0.357, and SHSgluc; β=0.388; for all: p<0.015) and smoking (smoking: meanTBRgluc; β=0.312, SHSgluc; β=0.324; for all: p<0.04) were significantly associated with FDG uptake.
Type-2 diabetes was significantly associated with carotid wall FDG uptake in patients with known or suspected cardiovascular disease. In diabetic patients, obesity and smoking add to the risk of increased FDG uptake values. Furthermore, the degree of carotid wall FDG uptake increases with increments of fasting glucose levels in diabetic patients.
PMCID: PMC3392202  PMID: 22651864
FDG-PET; Inflammation; Atherosclerosis; Diabetes; Carotid Arteries
8.  Coronary artery and thoracic aorta calcification is inversely related to coronary flow reserve as measured by 82Rb PET/CT in intermediate risk patients 
Journal of Nuclear Cardiology  2013;20(3):375-384.
The strength and nature of the relationship between myocardial perfusion imaging (MPI), coronary flow reserve (CFR), and coronary artery calcium (CAC) and thoracic aorta calcium (TAC) remain to be clarified.
Dynamic rest-pharmacological stress 82Rb positron emission tomography/computed tomography MPI with CFR, CAC, and TAC was performed in 75 patients (59 ± 13 years; F/M = 38/37) with intermediate risk of coronary artery disease.
A total of 29 (39%) patients had ischemic and 46 (61%) had normal MPI. CAC was correlated with TAC (ρ = 0.7; P < .001), and CFR was inversely related with CAC and TAC (ρ = −0.6 and −0.5; P < .001, respectively). By gender-specific univariate analysis, age (P = .001), CAC (P = .004), and CFR (P = .008) in males, but CFR (P = .0001), age (P = .002), and TAC (P = .01) in females were significant predictors of ischemic MPI. By multiple regression, the most potent predictor was CFR [odds ratio (OR) = 0.17, P = .01), followed by age (OR = 1.07, P = .02), gender (OR = 4.01, P = .03), and CAC (OR = 1.002, P = .9).
Combination of MPI, CFR, CAC, and TAC has complementary roles in intermediate risk patients.
Electronic supplementary material
The online version of this article (doi:10.1007/s12350-013-9675-5) contains supplementary material, which is available to authorized users.
PMCID: PMC3653061  PMID: 23468383
PET/CT; coronary flow reserve; coronary artery calcium; thoracic aorta calcium; coronary artery disease
9.  Detection of Neovessels in Atherosclerotic Plaques of Rabbits using Dynamic Contrast Enhanced MRI and 18F-FDG PET 
The association of inflammatory cells and neovessels in atherosclerosis is considered a histological hallmark of high-risk active lesions. Therefore, the development and validation of noninvasive imaging techniques that allow for the detection of inflammation and neoangiogenesis in atherosclerosis would be of major clinical interest.
Our aim was to test two techniques, black blood dynamic contrast enhanced MRI (DCE-MRI) and 18-fluorine-fluorodeoxyglucose (18F-FDG) PET, to quantify inflammation expressed as plaque neovessels content in a rabbit model of atherosclerosis.
Methods and Results
Atherosclerotic plaques were induced in the aorta of ten rabbits by a combination of two endothelial abrasions and four months hyperlipidemic diet. Six rabbits underwent MRI during the injection of Gd-DTPA, while four rabbits were imaged after injection of 18F-FDG with PET. We found a positive correlation between neovessels count in atherosclerotic plaques and 1) Gd-DTPA uptake parameters evaluated by DCE-MRI (r = 0.89, p = 0.016) and 2) 18F-FDG uptake evaluated by PET (r = 0.5, p =0.103 after clustered robust, Huber-White, standard errors analysis).
DCE-MRI and 18F-FDG PET may allow for the evaluation of inflammation in atherosclerotic plaques of rabbits. These non-invasive imaging modalities could be proposed as clinical tools in the evaluation of lesion prognosis and monitoring of anti–angiogenic therapies.
PMCID: PMC3194007  PMID: 18467641
atherosclerosis; inflammation; neovessels; MRI; PET
10.  The Relationships Between Regional Arterial Inflammation, Calcification, Risk Factors and Biomarkers – A Prospective FDG PET/CT Imaging Study 
Fluorodeoxyglucose positron emission tomography (FDG PET) imaging of atherosclerosis has been used to quantify plaque inflammation and to measure the effect of plaque stabilizing drugs. Here we explore how atherosclerotic plaque inflammation varies across arterial territories and how it relates to arterial calcification. We also test the hypotheses that the degree of local arterial inflammation measured by PET is correlated with the extent of systemic inflammation and presence of risk factors for vascular disease.
Methods and Results
Forty-one subjects underwent vascular PET/CT imaging with FDG. All had either vascular disease or multiple risk factors for it. Forty subjects underwent carotid imaging, twenty-seven underwent aortic, twenty-four iliac and thirteen femoral imaging. Thirty-three subjects had a panel of biomarkers analyzed.
We found strong associations between FDG uptake in neighboring arteries (left vs. right carotid r=0.91, p<0.001, ascending aorta vs. aortic arch r=0.88, p<0.001). Calcification and inflammation rarely overlapped within arteries – carotid artery FDG uptake vs. calcium score r=−0.42, p=0.03). Carotid artery FDG uptake was greater in those with a history of coronary artery disease (target to background ratio (TBR) 1.83 vs. 1.61, p<0.01), and in males vs. females (TBR 1.83 vs. 1.63, p<0.05). Similar findings were also noted in the aorta and iliac arteries. Subjects with the highest levels of FDG uptake also had the greatest concentrations of inflammatory biomarkers: descending aorta TBR vs. matrix metalloproteinase 3 (MMP 3): r=0.53, p=0.01 and carotid TBR vs. MMP 9: r=0.50, p=0.01. Non-significant positive trends were seen between FDG uptake and levels of interleukin 18, fibrinogen and C-reactive protein. Finally, we found that the atheroprotective biomarker adiponectin was negatively correlated with the degree of arterial inflammation in the descending aorta: r=−0.49, p=0.03).
This study shows that FDG PET imaging can increase our knowledge of how atherosclerotic plaque inflammation relates to calcification, serum biomarkers and vascular risk factors. Plaque inflammation and calcification rarely overlap, supporting the theory that calcification represents a late, burnt-out stage of atherosclerosis. Inflammation in one arterial territory is associated with inflammation elsewhere, and the degree of local arterial inflammation is reflected in the blood levels of several circulating biomarkers. We suggest that FDG PET imaging could be used as a surrogate marker of both atherosclerotic disease activity and drug effectiveness. Prospective, event driven studies are now underway to determine the role of this technique in clinical risk prediction.
PMCID: PMC3190196  PMID: 19808576
Atherosclerosis; Imaging; Inflammation; Positron Emission Tomography; Fluorodeoxyglucose; Calcification
11.  Extraperitoneal urine leak after renal transplantation: the role of radionuclide imaging and the value of accompanying SPECT/CT - a case report 
BMC Medical Imaging  2010;10:23.
The differentiation of the nature of a fluid collection as a complication of kidney transplantation is important for management and treatment planning. Early and delayed radionuclide renography can play an important role in the evaluation of a urine leak. However, it is sometimes limited in the evaluation of the exact location and extent of a urine leak.
Case Presentation
A 71-year-old male who had sudden anuria, scrotal swelling and elevated creatinine level after cadaveric renal transplantation performed Tc-99 m MAG3 renography to evaluate the renal function, followed by an ultrasound which was unremarkable. An extensive urine leak was evident on the planar images. However, an exact location of the urine leak was unknown. Accompanying SPECT/CT images confirmed a urine leak extending from the lower aspect of the transplant kidney to the floor of the pelvic cavity, presacral region and the scrotum via right inguinal canal as well as to the right abdominal wall.
Renal scintigraphy is very useful to detect a urine leak after renal transplantation. However, planar imaging is sometimes limited in evaluating the anatomical location and extent of a urine leak accurately. In that case accompanying SPECT/CT images are very helpful and valuable to evaluate the anatomical relationships exactly.
PMCID: PMC2984463  PMID: 20961409
12.  Repeatability of regional myocardial blood flow calculation in 82Rb PET imaging 
We evaluated the repeatability of the calculation of myocardial blood flow (MBF) at rest and pharmacological stress, and calculated the coronary flow reserve (CFR) utilizing 82Rb PET imaging. The aim of the research was to prove high repeatability for global MBF and CFR values and good repeatability for regional MBF and CFR values. The results will have significant impact on cardiac PET imaging in terms of making it more affordable and increasing its use.
12 normal volunteers were imaged at rest and during pharmacological stress, with 2220 MBq of 82Rb each. A GE Advance PET system was used to acquire dynamic 50-frame studies. MBF was calculated with a 2-compartmental model using a modified PMOD program (PMOD; University Hospital Zurich, Zurich, Switzerland). Two differential equations, describing a 2-compartmental model, were solved by numerical integration and using Levenberg-Marquardt's method for fitting data. The PMOD program defines 16 standard segments and calculates myocardial flow for each segment, as well as average septal, anterior, lateral, inferior and global flow. Repeatability was evaluated according to the method of Bland and Altman.
Global rest and stress MBF, as well as global CFR, showed very good repeatability. No significant differences were found between the paired resting global MBF (0.63 ± 0.13 vs. 0.64 ± 0.13 mL/min/g; mean difference, -1.0% ± 2.6%) and the stress global MBF (1.37 ± 0.23 vs. 1.37 ± 0.24; mean difference, 0.1% ± 2.3%). Global CFR was highly reproducible (2.25 ± 0.56 vs. 2.22 ± 0.54, P = not statistically significant; mean difference, 1.3% ± 14.3%). Repeatability coefficients for global rest MBF were 0.033 (5.2%) and stress MBF 0.062 (4.5%) mL/min/g. Regional rest and stress MBF and CFR have shown good reproducibility. The average per sector repeatability coefficients for rest MBF were 0.056 (8.5%) and stress MBF 0.089 (6.3%) mL/min/g, and average repeatability coefficient for CFR was 0.25 (10.6%).
The results of the study show that software calculation of MBF and CFR with 82Rb myocardial PET imaging is highly repeatable for global values and has good repeatability for regional values.
PMCID: PMC2646684  PMID: 19178700
13.  Comparison of 2D, 3D high dose and 3D low dose gated myocardial 82Rb PET imaging 
We compared 2D, 3D high dose (HD) and 3D low dose (LD) gated myocardial Rb-82 PET imaging in 16 normal human studies. The main goal in the paper is to evaluate whether the images obtained by a 3D LD studies are still of comparable clinical quality to the images obtained with the 2D HD or 3D HD studies.
All 2D and 3D HD studies were performed with 2220 MBq of Rb-82. The 3D LD were performed with 740 MBq of Rb-82. A GE Advance PET system was used for acquisition. Polar maps were created and used to calculate noise among (NAS) and within (NWS) the segments in the noise analysis. In addition, the contrast between left ventricular (LV) wall and LV cavity was also analysed. For 13 subjects, ejection fraction (EF) on 2D and 3D studies was calculated using QGS program.
For the H20 reconstruction filter, the mean contrast in mid-ventricular short-axis slice was 0.33 ± 0.06 for 2D studies. The same contrast for the 3D HD studies was 0.38 ± 0.07 and for 3D LD, it was 0.34 ± 0.08. For the 6 volunteers where 3D HD was used, NAS was 3.64*10-4 and NWS was 1.79*10-2 for 2D studies, and NAS was 3.70*10-4 and NWS was 1.85*10-2 for 3D HD studies, respectively. For the other 10 volunteers where 3D LD was used, NAS was 3.85*10-4 and NWS was 1.82*10-2 for the 2D studies, and NAS was 5.58*10-4 and NWS was 1.91*10-2 for the 3D LD studies, respectively. For the sharper H13 filter, the data followed the same pattern, with slightly higher values of contrast and noise. EF values in 2D and 3D were close. The Pearson's correlation coefficient was 0.90. The average difference from 13 subjects was 8.3%.
2D and 3D HD gating Rb-82 PET cardiac studies have similar contrast, ejection fractions and noise levels. 3D LD gating imaging, gave comparable results in terms of contrast, EF and noise to either 2D or 3D HD gating PET imaging. 3D LD PET gated imaging can make Rb-82 PET cardiac imaging more affordable with significantly less radiation exposure to the patients.
PMCID: PMC2140263  PMID: 17953754
14.  Comparison of 18F SPECT with PET in myocardial imaging: A realistic thorax-cardiac phantom study 
Positron emission tomography (PET) imaging with fluorine-18 (18F) Fluorodeoxyglucose (FDG) and flow tracer such as Rubidium-82 (82Rb) is an established method for evaluating an ischemic but viable myocardium. However, the high cost of PET imaging restricts its wider clinical use. Therefore, less expensive 18F FDG single photon emission computed tomography (SPECT) imaging has been considered as an alternative to 18F FDG PET imaging. The purpose of the work is to compare SPECT with PET in myocardial perfusion/viability imaging.
A nonuniform RH-2 thorax-heart phantom was used in the SPECT and PET acquisitions. Three inserts, 3 cm, 2 cm and 1 cm in diameter, were placed in the left ventricular (LV) wall to simulate infarcts. The phantom acquisition was performed sequentially with 7.4 MBq of 18F and 22.2 MBq of Technetium-99m (99mTc) in the SPECT study and with 7.4 MBq of 18F and 370 MBq of 82Rb in the PET study. SPECT and PET data were processed using standard reconstruction software provided by vendors. Circumferential profiles of the short-axis slices, the contrast and viability of the inserts were used to evaluate the SPECT and PET images.
The contrast for 3 cm, 2 cm and 1 cm inserts were for 18F PET data, 1.0 ± 0.01, 0.67 ± 0.02 and 0.25 ± 0.01, respectively. For 82Rb PET data, the corresponding contrast values were 0.61 ± 0.02, 0.37 ± 0.02 and 0.19 ± 0.01, respectively. For 18F SPECT the contrast values were, 0.31 ± 0.03 and 0.20 ± 0.05 for 3 cm and 2 cm inserts, respectively. For 99mTc SPECT the contrast values were, 0.63 ± 0.04 and 0.24 ± 0.05 for 3 cm and 2 cm inserts respectively. In SPECT, the 1 cm insert was not detectable. In the SPECT study, all three inserts were falsely diagnosed as "viable", while in the PET study, only the 1 cm insert was diagnosed falsely "viable".
For smaller defects the 99mTc/18F SPECT imaging cannot entirely replace the more expensive 82Rb/18F PET for myocardial perfusion/viability imaging, due to poorer image spatial resolution and poorer defect contrast.
PMCID: PMC1634842  PMID: 17076890
15.  Non-invasive imaging of atherosclerotic plaque macrophage in a rabbit model with F-18 FDG PET: a histopathological correlation 
Coronary atherosclerosis and its thrombotic complications are the major cause of mortality and morbidity throughout the industrialized world. Thrombosis on disrupted atherosclerotic plaques plays a key role in the onset of acute coronary syndromes. Macrophages density is one of the most critical compositions of plaque in both plaque vulnerability and thrombogenicity upon rupture. It has been shown that macrophages have a high uptake of 18F-FDG (FDG). We studied the correlation of FDG uptake with histopathological macrophage accumulation in atherosclerotic plaques in a rabbit model.
Atherosclerosis was induced in rabbits (n = 6) by a combination of atherogenic diet and balloon denudation of the aorta. PET imaging was performed at baseline and 2 months after atherogenic diet and coregistered with magnetic resonance (MR) imaging. Normal (n = 3) rabbits served as controls. FDG uptake by the thoracic aorta was expressed as concentration (μCi/ml) and the ratio of aortic uptake-to-blood radioactivity. FDG uptake and RAM-11 antibody positive areas were analyzed in descending aorta.
Atherosclerotic aortas showed significantly higher uptake of FDG than normal aortas. The correlation of aortic FDG uptake with macrophage areas assessed by histopathology was statistically significant although it was not high (r = 0.48, p < 0.0001). When uptake was expressed as the ratio of aortic uptake-to-blood activity, it correlated better (r = 0.80, p < 0.0001) with the macrophage areas, due to the correction for residual blood FDG activity.
PET FDG activity correlated with macrophage content within aortic atherosclerosis. This imaging approach might serve as a useful non-invasive imaging technique and potentially permit monitoring of relative changes in inflammation within the atherosclerotic lesion.
PMCID: PMC1479805  PMID: 16725052
16.  Using the intraoperative hand held probe without lymphoscintigraphy or using only dye correlates with higher sensory morbidity following sentinel lymph node biopsy in breast cancer: A review of the literature 
There are no studies that have directly investigated the incremental reduction in sensory morbidity that lymphoscintigraphy images (LS) and triangulated body marking or other skin marking techniques provide during sentinel lymph node biopsy (SLNB) compared to using only the probe without LS and skin marking or using only dye. However, an indirect assessment of this potential for additional sensory morbidity reduction is possible by extracting morbidity data from studies comparing the morbidity of SLNB to that of axillary lymph node dissection.
A literature search yielded 13 articles that had data on sensory morbidity at specific time points on pain, numbness or paresthesia from SLNB that used radiotracer and probe or used only dye as a primary method of finding the sentinel node (SN). Of these, 10 utilized LS, while 3 did not utilize LS. By matching the data in studies not employing LS to the studies that did, comparisons regarding the percentage of patients experiencing pain, numbness/paresthesia after SLNB could be reasonably attempted at a cutoff of 9 months.
In the 7 studies reporting on pain after 9 months (> 9 months) that used LS (1347 patients), 13.8% of patients reported these symptoms, while in the one study that did not use LS (143 patients), 28.7% of patients reported these symptoms at > 9 months (P < 0.0001). In the 6 studies reporting on numbness and/or paresthesia at > 9 months that used LS (601 patients), 12.5% of patients reported these symptoms, while in the 3 studies that did not use LS (229 patients), 23.1% of patients reported these symptoms at > 9 months (P = 0.0002). Similar trends were also noted for all these symptoms at ≤ 9 months.
Because of variations in techniques and time of assessing morbidity, direct comparisons between studies are difficult. Nevertheless at a minimum, a clear trend is present: having the LS images and skin markings to assist during SLNB appears to yield more favorable morbidity outcomes for the patients compared to performing SLNB with only the probe or performing SLNB with dye alone. These results are extremely pertinent, as the main reason for performing SLNB itself in the first place is to achieve reduced morbidity.
PMCID: PMC1262786  PMID: 16194276

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