Accuracy of Cardiac Innervation Scintigraphy for Mild Cognitive Impairment With Lewy Bodies.

OBJECTIVE: To provide evidence that cardiac I-123-metaiodobenzylguanidine sympathetic innervation imaging (MIBG) scintigraphy differentiates probable mild cognitive impairment with Lewy bodies (MCI-LB) from mild cognitive impairment due to Alzheimer disease (MCI-AD), we scanned patients with MCI and obtained consensus clinical diagnoses of their MCI subtype. We also performed baseline FP-CIT scans to compare the accuracy of MIBG and FP-CIT. METHODS: We conducted a prospective cohort study into the accuracy of cardiac MIBG scintigraphy in the diagnosis of MCI-LB. Follow-up clinical assessment was used to diagnose MCI-AD (no core features of MCI-LB and normal FP-CIT), probable MCI-LB (2 or more core features, or 1 core feature with abnormal FP-CIT), or possible MCI-LB (1 core feature or abnormal FP-CIT). For the comparison between MIBG and FP-CIT, only core clinical features were used for diagnosis. RESULTS: We recruited 95 people with mild cognitive impairment. Cardiac MIBG was abnormal in 22/37 probable and 2/15 possible MCI-LB cases and normal in 38/43 MCI-AD cases. The sensitivity in probable MCI-LB was 59% (95% confidence interval [CI], 42%-75%), specificity 88% (75%-96%), and accuracy 75% (64%-84%). The positive likelihood ratio was 5.1 and negative likelihood ratio 0.46. With symptom-only diagnoses, the accuracies were 79% for MIBG (95% CI, 68%-87%) and 76% for FP-CIT (95% CI, 65%-85%). CONCLUSIONS: Cardiac MIBG appears useful in early disease, with an abnormal scan highly suggestive of MCI-LB. Validation in a multicenter setting is justified. CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that cardiac MIBG distinguishes MCI-LB from MCI-AD.

Site qualification and clinical interpretation standards for 99mTc-SPECT perfusion imaging in a multi-center study of MITNEC (Medical Imaging Trials Network of Canada).

BACKGROUND: Qualification and interpretation standards are essential for establishing 99mTc-SPECT MPI accuracy vs. alternative modalities. METHODS: Rest-stress 99mTc-SPECT phantom scans were acquired on 35 cameras. LV defects were quantified with summed stress (SSS) and difference scores (SDS) at 2 core labs. SDS ≥ 2 in the right coronary artery (RCA) was the qualifying standard. Twenty rest (R)-stress (S) patient images were acquired on qualified cameras and interpreted by core labs. Global scoring differences > 3 between labs or discordant clinical interpretations underwent review. Scoring, interpretation, image quality, and diagnostic parameter agreement were assessed. RESULTS: Phantom scans: visual scoring confirmed RCA-ischemia on all cameras. Regional SSS, SDS agreement was moderate to very good: ICC-r = 0.57, 0.84. Patient scans: 90% of global SSS, 85% of SDS differences were ≤ 3. Regional SSS, SDS agreement: ICC-r = 0.87, 0.86, and global abnormal (SSS ≥ 4) and ischemic (SDS ≥ 2) interpretation: ICC-r = 0.90 were excellent. Clinical interpretation agreement was 100% following review. Image quality agreement was 70%. Automated metrics also agreed: ischemic total perfusion deficit ICC-r = 0.75, reversible perfusion defect, transient ischemic dilation, and S-R LV ejection fraction ICC-r ≥ 0.90. CONCLUSION: Quantitative scoring and interpretation of scans were highly repeatable with site qualification and clinical interpretation standardization, indicating that dual-core lab interpretation is appropriate to determine 99mTc-SPECT MPI accuracy.

Inter-reader variability of SPECT MPI readings in low- and middle-income countries: Results from the IAEA-MPI Audit Project (I-MAP).

BACKGROUND: Consistency of results between different readers is an important issue in medical imaging, as it affects portability of results between institutions and may affect patient care. The International Atomic Energy Agency (IAEA) in pursuing its mission of fostering peaceful applications of nuclear technologies has supported several training activities in the field of nuclear cardiology (NC) and SPECT myocardial perfusion imaging (MPI) in particular. The aim of this study was to verify the outcome of those activities through an international clinical audit on MPI where participants were requested to report on studies distributed from a core lab. METHODS: The study was run in two phases: in phase 1, SPECT MPI studies were distributed as raw data and full processing was requested as per local practice. In phase 2, images from studies pre-processed at the core lab were distributed. Data to be reported included summed stress score (SSS); summed rest score (SRS); summed difference score (SDS); left ventricular (LV) ejection fraction (EF) and end- diastolic volume (EDV). Qualitative appraisals included the assessment of perfusion and presence of ischemia, scar or mixed patterns, presence of transient ischemic dilation (TID), and risk for cardiac events (CE). Twenty-four previous trainees from low- and middle-income countries participated (core participants group) and their results were assessed for inter-observer variability in each of the two phases, and for changes between phases. The same evaluations were performed for a group of eleven international experts (experts group). Results were also compared between the groups. RESULTS: Expert readers showed an excellent level of agreement for all parameters in both phase 1 and 2. For core participants, the concordance of all parameters in phase 1 was rated as good to excellent. Two parameters which were re-evaluated in phase 2, namely SSS and SRS, showed an increased level of concordance, up to excellent in both cases. Reporting of categorical variables by expert readers remained almost unchanged between the two phases, while core participants showed an increase in phase 2. Finally, pooled LVEF values did not show a significant difference between core participants and experts. However, significant differences were found between LVEF values obtained using different software packages for cardiac analysis. CONCLUSIONS: In this study, inter-observer agreement was moderate-to-good for core group readers and good-to-excellent for expert readers. The quality of reporting is affected by the quality of processing. These results confirm the important role of the IAEA training activities in improving imaging in low- and middle-income countries.

Diagnostic performance of non-invasive imaging for stable coronary artery disease: A meta-analysis.

BACKGROUND: To determine diagnostic performance of non-invasive tests using invasive fractional flow reserve (FFR) as reference standard for coronary artery disease (CAD). METHODS: Medline, Embase, and citations of articles, guidelines, and reviews for studies were used to compare non-invasive tests with invasive FFR for suspected CAD published through March 2017. RESULTS: Seventy-seven studies met inclusion criteria. The diagnostic test with the highest sensitivity to detect a functionally significant coronary lesion was coronary computed tomography (CT) angiography [88%(85%-90%)], followed by FFR derived from coronary CT angiography (FFRCT) [85%(81%-88%)], positron emission tomography (PET) [85%(82%-88%)], stress cardiac magnetic resonance (stress CMR) [81%(79%-84%)], stress myocardial CT perfusion combined with coronary CT angiography [79%(74%-83%)], stress myocardial CT perfusion [77%(73%-80%)], stress echocardiography (Echo) [72%(64%-78%)] and stress single-photon emission computed tomography (SPECT) [64%(60%-68%)]. Specificity to rule out CAD was highest for stress myocardial CT perfusion added to coronary CT angiography [91%(88%-93%)], stress CMR [91%(90%-93%)], and PET [87%(86%-89%)]. CONCLUSION: A negative coronary CT angiography has a higher test performance than other index tests to exclude clinically-important CAD. A positive stress myocardial CT perfusion added to coronary CT angiography, stress cardiac MR, and PET have a higher test performance to identify patients requiring invasive coronary artery evaluation.

Competency-Based Medical Education: Do the Cardiac Imaging Training Guidelines Have it Right?

OBJECTIVES: This study sought to: 1) determine if the current training volume guidelines are reasonable for attaining competence for interpreting myocardial perfusion imaging (MPI); and if not, 2) identify potential thresholds for training volumes and competence. BACKGROUND: There is a growing desire to adopt competency-based medical education (CBME). As such, the implementation of CBME will require new and novel methods of defining, measuring, and assessing clinical competence. The potential use of CBME in cardiac imaging has not been well studied. METHODS: Consecutive MPI studies were interpreted independently by trainees, and expert readers reviewed the same studies. Studies were quantified using summed scores and % left ventricular (LV) ischemia and the kappa agreement between trainee and expert were measured every 50 cases. Agreement for all MPI and abnormal MPI cases was calculated. RESULTS: A total of 24 trainees interpreted 9,668 MPI studies over 37 months. Agreement between trainees and expert readers increased with MPI case volumes but at different rates. The threshold for competence was set at 2 SDs below expert interobserver agreement. The average trainee surpassed this threshold for both summed stress score and %LV ischemia after 800 studies and after 400 abnormal MPI studies. Trainees learned at different rates and surpassed the competence threshold after different case volumes. CONCLUSIONS: The use of CBME within nuclear cardiology appears to be feasible. Our results suggest that current guidelines may be insufficient to ensure competence and would support the need to increase the MPI case volumes. The use of CBME principles would suggest that trainees may achieve competence at different rates and our results suggest a shift in focus from volume-based learning toward target agreement thresholds.

I-131 Postablation SPECT/CT Predicts Relapse of Papillary Thyroid Carcinoma more Accurately than Whole Body Scan.

BACKGROUND/AIM: The aim of the study was to prospectively compare I-131 postablation Whole Body scan (WBS) and Single Photon Emission Computerized Tomography/Computerized Tomography (SPECT/CT) scan on thyroid cancer patients. PATIENTS AND METHODS: Overall, 58 patients with papillary thyroid carcinoma were submitted to total thyroidectomy and I-131 remnant ablation. Post-ablation WBS and SPECT/CT scans performed on the same day were compared. Results of SPECT/CT were confirmed by neck and upper mediastinum ultrasound scan and on specific cases by a fully diagnostic CT scan, other tests and definitive histology acting as the gold standard. A total of 36/58 patients were followed-up for 5 years to detect relapse. RESULTS: Mac Nemar Chi square and Fisher's exact tests disclosed statistically significant differences between WBS and SPECT/CT scan, concerning cervical lymphadenopathy detection (p=0.031) and relapse prediction by NM stage (p=0.033), respectively; SPECT/CT was more accurate in both comparisons. CONCLUSION: In papillary thyroid carcinoma I-131 post-ablation SPECT/CT scan detects cervical lymphadenopathy and predicts relapse by NM stage more accurately than WBS.

[Impact of Misregistration between the Myocardial Perfusion Images and CT Attenuation Correction Map on the %up Take with 17 Segments Polar Map].

PURPOSE: Computed tomography (CT) attenuation correction of myocardial perfusion in single-photon emission computed tomography (SPECT) /CT systems is possibility of misregistration between emission and transmission scans. This study aimed to evaluate the influence of misregistration using a polar map of 17 segments model. METHODS: Using the fusion software, we assessed the magnitude and direction of misregistration in 200 consecutive myocardial perfusion SPECT images with 99mTechnetium (99mTc) tetrofosmin. After registration, CT data was shifted by ±1, ±2, and ±3 pixels along the cephalad/caudal, dorsal/ventral, and left/right axes, respectively. The registered image was compared with the shifted image. RESULTS: Misregistration between the SPECT and CT images occurred by 1-2 pixels in 127 cases (63.5%) and by 2 or more pixels in four cases (2%); the maximum misregistration was 1.2±0.4 pixels on average. The polar map scoring was most significantly affected by 3 pixel ventral shift. A ventral shift of 1 pixel affected the scores for the anterolateral and inferolateral segments, whereas a caudal shift of 1 pixel affected the scores for the anterior segment. CONCLUSION: Since the 17 segments model can evaluate the position more precisely than the five segments model, it is possible to evaluate up to 1 pixel misregistration.

Are there normal values of phase analysis parameters for left ventricular dyssynchrony in patients with no structural cardiomyopathy?: a systematic review.

BACKGROUND: ECG-gated single photon emission computed tomography (SPECT) myocardial perfusion scintigraphy combined with phase analysis allows for the assessment of left ventricular dyssynchrony. However, there are several software programs available thereby introducing variability in outcome and normal values. The aim of this systematic review was to evaluate the variability between different programs as currently available in literature with a focus on normal values. METHODS: A systematic review was performed using the Embase, LILACS and Medline databases looking for articles reporting on normal values of the most used phase analysis parameters. The search resulted in 110 articles from Medline, 349 from Embase and one from LILACS. After exclusion of duplicate articles, 370 documents remained. Of these only 13 were deemed eligible for the systematic review. RESULTS: Phase SD and bandwidth are the main parameters used in dyssynchrony analysis. Most articles reviewed here used the Emory Cardiac ToolBox (ECTb) to determine the phase analysis parameters values, which varied greatly among the four software tested. The bandwidth and phase SD calculated by the Quantitative Gated SPECT (QGS) tends to be smaller than that calculated by the ECTb. In relation to the bandwidth, ECTb and cardioREPO (cREPO) have higher values than the other software programs. The value of entropy obtained from 4DM is lower than those obtained from QGS and cREPO. CONCLUSION: We found that normal values of phase analysis can vary among software programs and can be different even when the same software is used.

Current pediatric administered activity guidelines for 99m Tc-DMSA SPECT based on patient weight do not provide the same task-based image quality.

PURPOSE: In the current clinical practice, administered activity (AA) for pediatric molecular imaging is often based on the North American expert consensus guidelines or the European Association of Nuclear Medicine dosage card, both of which were developed based on the best clinical practice. These guidelines were not formulated using a rigorous evaluation of diagnostic image quality (IQ) relative to AA. In the guidelines, AA is determined by a weight-based scaling of the adult AA, along with minimum and maximum AA constraints. In this study, we use task-based IQ assessment methods to rigorously evaluate the efficacy of weight-based scaling in equalizing IQ using a population of pediatric patients of different ages and body weights. METHODS: A previously developed projection image database was used. We measured task-based IQ, with respect to the detection of a renal functional defect at six different AA levels (AA relative to the AA obtained from the guidelines). IQ was assessed using an anthropomorphic model observer. Receiver-operating characteristics (ROC) analysis was applied; the area under the ROC curve (AUC) served as a figure-of-merit for task performance. In addition, we investigated patient girth (circumference) as a potential improved predictor of the IQ. RESULTS: The data demonstrate a monotonic and modestly saturating increase in AUC with increasing AA, indicating that defect detectability was limited by quantum noise and the effects of object variability were modest over the range of AA levels studied. The AA for a given value of the AUC increased with increasing age. The AUC vs AA plots for all the patient ages indicate that, for the current guidelines, the newborn and 10- and 15-yr phantoms had similar IQ for the same AA suggested by the North American expert consensus guidelines, but the 5- and 1-yr phantoms had lower IQ. The results also showed that girth has a stronger correlation with the needed AA to provide a constant AUC for 99m Tc-DMSA renal SPECT. CONCLUSIONS: The results suggest that (a) weight-based scaling is not sufficient to equalize task-based IQ for patients of different weights in pediatric 99m Tc-DMSA renal SPECT; and (b) patient girth should be considered instead of weight in developing new administration guidelines for pediatric patients.

Prospective diagnostic performance of semiconductor SPECT myocardial perfusion imaging: wall thickening analysis reduces the need for an additional prone acquisition.

PURPOSE: To determine whether the assessment of regional wall thickening (WT) in addition to myocardial perfusion from stress supine acquisitions could compensate for the lack of prone acquisition and the corresponding decrease in the diagnostic performance of SPECT myocardial perfusion imaging (MPI) in patients with known or suspected coronary artery disease (CAD). METHODS: The study group comprised 41 patients (123 vessels) with known or suspected CAD prospectively recruited for systematic prone and supine 201Tl stress SPECT MPI. The diagnostic performance of SPECT MPI was determined for various image sets including nongated supine images (supine NG), nongated combined prone and supine images (prone and supine NG) and gated supine images, allowing WT evaluation from NG images in addition to perfusion (supine NG + WT) using invasive coronary angiography and fractional flow reserve as the gold standards. RESULTS: The rate of false positives was significantly higher among the supine NG images (20.8%) than among either the prone and supine NG or the supine NG + WT images (3.3% and 2.7%, respectively, P < 0.05 vs. supine NG). Consequently, specificity was higher for the prone and supine NG images than for the supine NG images (96.1% vs. 76.1%, P < 0.01) and was highest for the supine NG + WT images (96.8%, P not significant vs. prone and supine NG), without significant differences in sensitivity (80.0%, 86.6% and 73.3%, respectively, P not significant for all comparisons). CONCLUSION: The diagnostic performance of supine stress SPECT MPI is improved when WT assessment of ischaemic segments is used as an additional diagnostic criterion to values not significantly different from those with combined prone and supine acquisitions.

The Qualification of an Enrichment Biomarker for Clinical Trials Targeting Early Stages of Parkinson's Disease.

As therapeutic trials target early stages of Parkinson's disease (PD), appropriate patient selection based purely on clinical criteria poses significant challenges. Members of the Critical Path for Parkinson's Consortium formally submitted documentation to the European Medicines Agency (EMA) supporting the use of Dopamine Transporter (DAT) neuroimaging in early PD. Regulatory documents included a comprehensive literature review, a proposed analysis plan of both observational and clinical trial data, and an assessment of biomarker reproducibility and reliability. The research plan included longitudinal analysis of the Parkinson Research Examination of CEP-1347 Trial (PRECEPT) and the Parkinson's Progression Markers Initiative (PPMI) study to estimate the degree of enrichment achieved and impact on future trials in subjects with early motor PD. The presence of reduced striatal DAT binding based on visual reads of single photon emission tomography (SPECT) scans in early motor PD subjects was an independent predictor of faster decline in UPDRS Parts II and III as compared to subjects with scans without evidence of dopaminergic deficit (SWEDD) over 24 months. The EMA issued in 2018 a full Qualification Opinion for the use of DAT as an enrichment biomarker in PD trials targeting subjects with early motor symptoms. Exclusion of SWEDD subjects in future clinical trials targeting early motor PD subjects aims to enrich clinical trial populations with idiopathic PD patients, improve statistical power, and exclude subjects who are unlikely to progress clinically from being exposed to novel test therapeutics.

Comparison of acquisition protocols for ventilation/perfusion SPECT-a Monte Carlo study.

One of the most commonly used imaging techniques for diagnosing pulmonary embolism (PE) is ventilation/perfusion (V/P) scintigraphy. The aim of this study was to evaluate the performance of the currently used imaging protocols for V/P single photon emission computed tomography (V/P SPECT) at two nuclear medicine department sites and to investigate the effect of altering important protocol parameters. The Monte Carlo technique was used to simulate 4D digital phantoms with perfusion defects. Six imaging protocols were included in the study and a total of 72 digital patients were simulated. Six dually trained radiologists/nuclear medicine physicians reviewed the images and reported all perfusion mismatch findings. The radiologists also visually graded the image quality. No statistically significant differences in diagnostic performance were found between the studied protocols, but visual grading analysis pointed out one protocol as significantly superior to four of the other protocols. Considering the study results, we have decided to harmonize our clinical protocols for imaging patients with suspected PE. The administered Technegas and macro aggregated albumin activities have been altered, a low energy all purpose collimator is used instead of a low energy high resolution collimator and the acquisition times have been lowered.

Use of cardiac magnetic resonance imaging and single photon emission computed tomography for the diagnosis of stable coronary artery disease in Switzerland.

BACKGROUND: Direct invasive testing in the diagnosis of stable coronary artery disease (CAD) involves high costs and relevant risks. By comparison, single-photon emission computed tomography (SPECT) and cardiac magnetic resonance imaging (CMR) are noninvasive diagnostic tests. SPECT is currently the most widely used diagnostic technique, but new medical and economic evidence favours CMR. Guidelines do not recommend one technique in preference to the other, and their use in Switzerland is poorly documented, as a scoping study by the Swiss Medical Board reported. We aimed at a quantitative and qualitative analysis of the use of these diagnostic techniques in Swiss hospitals. METHODS: We contacted nine Swiss hospitals to obtain the number of SPECT/CMR investigations used to diagnose stable CAD in 2014–2016 and submitted a questionnaire to investigate the advantages and limitations of the two imaging techniques. In addition, two experts in SPECT and CMR, respectively, at two university hospitals were interviewed, using open questions. RESULTS: Data were obtained from 8 hospitals, and 22 questionnaires were returned. In Switzerland, both techniques have been implemented very differently in different hospitals, but the overall number of diagnostic procedures has increased. The questionnaires reported lower scores for CMR regarding the availability of the scans, contraindications and the suitability of the technique for the diagnosis of CAD. The experts described potential conflicts of interest in some institutions, depending on how the cardiology and radiology departments collaborated, and highlighted the debated results of studies comparing CMR with SPECT for the diagnosis of CAD. The main conclusion drawn from the interviews was the recommendation of a patient-centred evaluation. CONCLUSION: The use of SPECT versus CMR in Switzerland for the diagnosis of stable CAD is heterogeneous, but reflects the guidelines, which do not distinguish between the two diagnostic techniques. Expert opinions underlined that discussion should not be so much about the choice of the diagnostic modality but about how a clinical question in a patient can best be answered.

Efficacy and Limitations of rCBF-SPECT in the Diagnosis of Alzheimer's Disease With Amyloid-PET.

This study aimed to assess efficacy and limitations of regional cerebral blood flow imaging using single-photon emission computed tomography (rCBF-SPECT) in the diagnosis of Alzheimer's disease (AD) with amyloid-positron emission tomography (amyloid-PET). Thirteen patients, who underwent both rCBF-SPECT and amyloid-PET after clinical diagnosis of AD or mild cognitive impairment, were retrospectively identified. The rCBF-SPECTs were classified into 4 grades, from typical AD pattern to no AD pattern of hypoperfusion; amyloid-beta (Aß) positivity was assessed by amyloid-PET. Four patients were categorized into a typical AD pattern on rCBF-SPECT, and all were Aß+. The other 9 patients did not exhibit a typical AD pattern; however, 4 were Aß+. The Mini-Mental State Examination score and Clinical Dementia Rating scale were not significantly different between Aß+ and Aß- patients. A typical AD pattern on rCBF-SPECT can reflect Aß+; however, if not, rCBF-SPECT has a limitation to predict amyloid pathology.

Reduced Scan Time in 123I-FP-CIT SPECT Imaging Using a Large-Field Cadmium-Zinc-Telluride Camera.

We evaluated the reproducibility of I-ioflupane (I-FP-CIT) SPECT with shorter scan times using a CZT camera. One hundred ninety-nine I-FP-CIT SPECT scans obtained with standard scan time (30 minutes) were truncated to provide 24-, 18-, and 15-minute study simulations. Striatal binding ratios were automatically calculated and remained stable for all series. At 15 minutes, only 10 of 398 striata (2.5%) showed statistically significant different striatal binding ratios compared with reference series. These series were reviewed by 2 operators, and a perfect agreement was found for each patient. Therefore, CZT camera allows a 2-fold scan time reduction in I-FP-CIT SPECT.

Correlation of 99mTc-TRODAT-1 SPECT Imaging Findings and Clinical Staging of Parkinson Disease.

PURPOSE: The aims of this study were to evaluate Tc-TRODAT-1 SPECT imaging patterns and to assess their correlation with disease severity in clinically diagnosed patients of Parkinson disease (PD). METHODS: The study included 241 patients with clinically diagnosed idiopathic Parkinson disease who underwent Tc-TRODAT-1 SPECT/CT scan. Binding ratios were calculated for each striatum, caudate, and putamen individually, by drawing region of interest. Occipital cortex region of interest was taken for background correction. Correlation of binding ratio with increasing clinical stage was derived, as described by modified Hoehn and Yahr scale. RESULTS: Median binding ratio was least in the contralateral putamen for all stages of modified Hoehn and Yahr. A statistically significant negative correlation was found between increasing disease severity and binding ratio in all subregions of striatum. Patients were clinically categorized into postural instability and gait disorder group and tremor-dominant PD group. No significant asymmetry was found between the left and right striatum in patients belonging to postural instability and gait disorder group and in those with bilateral tremors without lateralization. CONCLUSIONS: Tc-TRODAT-1 SPECT is useful in early detection and in assessing disease severity of PD. A significant asymmetry with the contralateral side being affected more than the ipsilateral side can be attributed to tremor-dominant patients. The binding ratio of the ipsilateral striatum may serve useful as a marker of remaining functional dopaminergic neuronal reserve in the striatum.

Standardization of the specific binding ratio in [123I]FP-CIT SPECT: study by striatum phantom.

OBJECTIVE: The quantitative values of the specific binding ratio (SBR) in [I]FP-CIT have been reported to change because of differences in apparatus, collection conditions, and image reconstruction. The aim of this study was to clarify the distribution of calculated SBR values by performing [I]FP-CIT single-photon emission computed tomography in a multicenter collaborative study using a phantom. A simple correction method was also devised that enables direct comparison of the SBR value calculated at one facility with those calculated at other facilities. MATERIALS AND METHODS: Data were acquired at 14 facilities using the phantom adjusted to right striatum : left striatum : cerebral parenchyma (back ground)=8 : 4 : 1, and the SBR values were calculated.We devised a method to correct the SBR using the results of experiments with a known ratio phantom. RESULTS: The SBR values considerably differed between facilities. The average SBR with a theoretical value of 7 and with a theoretical value of 3 in all facilities was 6.48±0.89 and 2.58±0.51, respectively. The range of SBRs with a theoretical value of 7 and a theoretical value of 3 was 3.18 and 1.59, respectively. We devised a simple method for calibrating the SBR value at the clinical examination of each facility to a directly comparable value. CONCLUSION: Direct comparison of the SBR with those of other facilities and sharing other facilities normal values is clinically difficult. We devised countermeasures that do not affect the diagnosis and developed a simple tool to calculate the standardized SBR.

PET/CT Evaluation of Cardiac Sarcoidosis.

The increasing implementation of advanced cardiovascular imaging in the form of cardiac PET/CT has had a significant impact on the management of cardiac sarcoidosis, which continues to evolve. This review summarizes the role of PET/CT imaging in sarcoidosis with a specific focus on (1) indications, (2) patient preparation, (3) test performance, (4) study interpretation, (5) clinical relevance of findings, (6) comparison to alternative imaging modalities, and finally (7) introduction of areas of anticipated development and research.

Semi-quantification of the minimum detectable difference of imaging quality of gamma camera SPET for four radionuclides via an innovative PMMA phantom with a V-shaped slit: interpretation of a feasibility study.

OBJECTIVE: An indigenous polymethyl metacrylate (PMMA) phantom with a V-shaped slit and a correlated technique for semi-quantifying the minimum detectable difference (MDD) of single photon emission tomography (SPET) via gamma camera scanning are proposed and validated using four radionuclides. MATERIALS AND METHODS: Radio-actinide solutions of gallium-67 (67Ga), technetium-99m (99mTc), iodine-131 (131I) and thallium-201 (201Tl) were diluted to 11c.c. and thoroughly injected into the continuous zig zag slit of the PMMA phantom. Either depth or edge of the slit between two lines of the V-shape was customized from deep or wide to change into shallow or narrow gradually. Thus, the quantified MDD could be easily evaluated, according to the revised Student's t-test evaluation. The revised Student's t-test was calculated by both full width at half maximum (FWHM) and edge width between two adjacent peaks that were acquired from the original data matrix of SPET. The derived MDD was indicated as for radionuclide, depth, width in mm: For 67Ga, 2.9, 2.13, for 99mTc, 2.5, 0.66, for 131I, 4.7, 2.38 and for 201Tl, 3.3, 2.00, respectively. RESULTS: Technetium-99m had the highest and 131I had the lowest MDD among the four radionuclides. Furthermore, two adjacent peaks of 67Ga could be easily identified with fewer counts than for 201Tl (depth, 2.9 vs. 3.3mm), but its MDD was poorer (width: 2.13 vs.2.00mm). The revised Student's t-test analysis proved to be an acceptable technique for the MDD identification. CONCLUSION: The proposed new combination of PMMA phantom with a V-slit and the revised Student's t-test proved to be instrumental in the MDD of SPET optimization analysis.

A Monte Carlo Simulation Study of Optimization for Collimator in a Pixelated SPECT Camera.

OBJECTIVE: To investigate the influence of collimator hole shape, size, and material on the performance of the high-resolution SPECT camera to find the optimal collimator design using the GEANT4 application for the tomographic emission Monte Carlo platform. METHODS AND MATERIALS: The geometry of the dual head camera equipped with a pixelated CsI(Na) crystal, lead hexagonal-hole collimator, and two flat-panel H8500 position-sensitive photomultipliers were accurately described in the GEANT4 application for the tomographic emission. The basic features of the scanner were calculated by using 2 mCi 99mTc sources. RESULTS: The simulated average spatial resolutions of lead hexagonal-, square-, and round-hole collimators were 2.68, 2.96, and 3.06 mm at 2.5 cm from the collimator surface, respectively. The sensitivity of the lead hexagonal-hole collimator was 10.86% and 18.84%, greater than that of the square and round holes, respectively, on the collimator surface. The measured averages of spatial resolution using gold were 16.14%, 11.39%, and 5.1% better than those of lead, tantalum, and tungsten hexagonal-hole collimators, respectively, at 2.5 cm from the collimator. The sensitivities of the tungsten, gold, tantalum, depleted uranium, and lead hexagonal-hole collimators were 0.74, 0.48, 1.127, 0.32, and 1.38 cps/µCi on the collimator surface, respectively. CONCLUSIONS: The hexagonal-hole collimator was preferred over the square- and round-hole collimators because of the optimum sensitivity and spatial resolution offered by its regular arrangement of apertures. Also, the lower-absorption and stopping-power materials such as lead revealed relatively better characteristics at specific sensitivity, whereas higher-absorption materials such as gold showed the best spatial resolution. The collimator with finer hole size had the superior spatial resolution and less sensitivity than larger holes.