Background: Pulmonary embolism (PE) is diagnosed either by ventilation/perfusion (V/Q) scintigraphy or pulmonary CT angiography. One of the imaging methods used in nuclear medicine is hybrid SPECT/CT scintigraphy. Objectives: The aim of this study was to evaluate the utility of SPECT/CT(Q) scintigraphy in the diagnosis of PE and to compare SPECT/CT(Q) with planar(Q) and SPECT(Q) methods. Methods: The study group consisted of 109 consecutive patients suspected of having PE referred for performing lung scintigraphy. The inclusion criteria were: performance of perfusion planar, SPECT and SPECT/CT scans; availability of clinical data covering a 6-month follow-up period, and D-dimer level testing. The number of eligible patients was 84. PE was reported in patients with at least 1 segmental or 2 subsegmental perfusion defects without parenchymal abnormalities on CT scans. PE was excluded when there was a normal perfusion pattern or perfusion defects were caused by lung parenchymal abnormalities or were not arranged in accordance with the pulmonary vasculature. Results: Twenty-six patients (31%) had a final diagnosis of PE. The sensitivity and specificity values of each method were as follows: planar(Q) 73 and 43%, SPECT(Q) 88 and 47% and SPECT/CT(Q) 100 and 83%. SPECT/CT(Q) yielded a significantly higher diagnostic accuracy than planar(Q) (p < 0.001) and SPECT(Q) (p < 0.001) scans. Conclusions: We conclude that hybrid SPECT/CT(Q) imaging has a high diagnostic efficacy in the diagnosis of PE. Lung perfusion scintigraphy performed with a hybrid SPECT/CT device has a significantly higher sensitivity and specificity than scanning performed with the planar or SPECT technique.

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Purpose of the Report The aim of the study was to prospectively compare performance of 18F-fluorocholine (FCH) and 18F-prostate-specific membrane antigen (PSMA)-1007 PET/CT in patients with biochemical relapse (BCR) of prostate cancer and low prostate-specific antigen levels. Methods We prospectively enrolled 40 BCR patients after radical treatment and prostate-specific antigen levels 2.0 ng/mL or less. 18F-FCH and 18F-PSMA-1007 PET/CT imaging was performed within a mean interval of 54 ± 21 days. Scans were done 87 ± 10 and 95 ± 12 minutes after injecting 248 ± 35 and 295 ± 14 MBq of 18F-FCH and 18F-PSMA-1007, respectively. Rates of negative, equivocal, and positive scan results were compared per patient. Per lesion, findings were grouped as equivocal or highly suggestive of malignancy and then compared for their number, localization (local relapse, lymph nodes, bones), and SUVmax values. Results Positive, equivocal, and negative results were reported in 60%, 27.5%, and 12.5% of 18F-PSMA-1007 and in 5%, 37.5%, and 57.5% of 18F-FCH scans, respectively. In 70% of scans, 18F-PSMA-1007 PET/CT upgraded 18F-FCH PET/CT results. 18F-PSMA-1007 scans also showed significantly more lesions (184 vs 63, P = 0.0006). Local relapse, lymph node, and bone lesions accounted, respectively, for 9%, 58%, and 33% of 18F-PSMA-1007 and 5%, 89%, and 6% 18F-FCH of PET/CT findings. Highly suspicious lesions accounted for 74% of 18F-PSMA-1007 and 11% of 18F-FCH PET/CT findings. In 18F-PSMA-1007 PET/CT SUVmax values of highly suggestive lesions were significantly higher than in equivocal lesions (median, 3.6 vs 2.5; P < 0.00001). Conclusions In early BCR patients 18F-PSMA-1007 showed a higher detection rate than 18F-FCH PET/CT. The former also showed more lesions in total, more highly suggestive lesions and less equivocal lesions.

Background The aim of the study was to compare widely used ordered subset expectation maximisation (OSEM) algorithm with a new Bayesian penalised likelihood (BPL) Q.Clear algorithm in 18F-PSMA-1007 PET/CT. Methods We retrospectively assessed 25 18F-PSMA-1007 PET/CT scans with both OSEM and Q.Clear reconstructions available. Each scan was independently reported by two physicians both in OSEM and Q.Clear. SUVmax, SUVmean and tumour-to-background ratio (TBR) of each lesion were measured. Reports were also compared for their final conclusions and the number and localisation of lesions. Results In both reconstructions the same 87 lesions were reported. Mean SUVmax, SUVmean and TBR were higher for Q.Clear than OSEM (7.01 vs 6.53 [p = 0.052], 4.16 vs 3.84 [p = 0.036] and 20.2 vs 16.8 [p < 0.00001], respectively). Small lesions (< 10 mm) had statistically significant higher SUVmax, SUVmean and TBR in Q.Clear than OSEM (5.37 vs 4.79 [p = 0.032], 3.08 vs 2.70 [p = 0.04] and 15.5 vs 12.5 [p = 0.00214], respectively). For lesions ≥ 10 mm, no significant differences were observed. Findings with higher tracer avidity (SUVmax ≥ 5) tended to have higher SUVmax, SUVmean and TBR values in Q.Clear (11.

Purpose: We aimed to find the minimum feasible dose of fluorodeoxyglucose (18F-FDG) in positron emission tomography/computed tomography (PET/CT) of Hodgkin lymphoma patients performed on a camera with bismuth germanate (BGO) crystals.Methods: Ninety-one 18F-FDG PET/CT scans with decreasing time per bed position (2 min, 1.5 min, 1 min, 50 sec, 40 sec, 30 sec and 20 sec) were assessed to evaluate image quality. Mean administered dose was 3.0±0.1 MBq/kg and mean uptake time was 54.0±8.7 min. The series quality was subjectively marked in 1-10 scale and then ranked 1-7 based on the mean mark. Interobserver rank correlation and intraclass correlation within each series were calculated. Phantom studies were also performed to determine if reduced acquisition time can be directly translated into a reduced dose. Results: We show the longer the time of acquisition the higher the mark and rank. The interobserver agreement in ranking was 100% with kappa coefficient of 1.00 (95% CI [0.83-1.0]). The general intraclass correlation coefficient was 0.945 (95% CI [0,936-0,952]). Only the series with 2 min and 1.5 min acquisition time were appropriate for assessment (mean mark ≥7). In phantom studies there was a linear correlation between time per bed, administered activity and number of total prompts detected by a scanner. Hence, reduction of acquisition time of 25% (from 2 min to 1.5 min) could be directly translated into a 25% dose reduction (from 3.0 to 2.25 MBq/kg).Conclusions: In patients with HL, 18F-FDG dose can be reduced by up to 25% when using a BGO crystal camera, without substantial impact on image quality.