We prospectively investigated the ideal imaging time to measure vascular uptake after injection of 18F-FDG. Methods: A total of 17 patients with atherosclerotic abdominal aortic aneurysm underwent dynamic abdominal PET/CT using 2-min frames between 45 and 53, 57 and 65, 115 and 123, and 175 and 183 min after injection of 18F-FDG. For each period of dynamic imaging, vessel wall and lumen uptake were measured using the maximum standardized uptake value (SUVmax) and target-to-background ratio (TBR). Results: No significant difference in TBR across all time points (repeated measures ANOVA, P = 0.206) was observed, despite a significant difference in aortic wall and lumen uptake with time (repeated measures ANOVA, P = 0.02 and P < 0.001, respectively). There was no significant difference between aortic wall uptake at 60 min (SUVmax, 2.15 ± 0.11 SE) and 180 min (SUVmax, 1.99 ± 0.18 SE) (paired t test, P = 0.367). There was a significant difference in lumen uptake at 60 min (SUVmax, 2.4 ± 0.11 SE) and 180 min (SUVmax, 1.7 ± 0.1 SE) (paired t test, P = 0.001). There was no significant difference in TBR between 60 min (0.91 ± 0.03) and 180 min (1.01 ± 0.06 SE) (paired t test, P = 0.131). With increasing delayed imaging, there was increasing variability (SE) in the SUVmax for the aortic wall and TBRs. Conclusion: There was no significant advantage in imaging at 3 h over 1 h after 18F-FDG injection.
There is a lack of prognostic biomarkers in idiopathic pulmonary fibrosis (IPF) patients. The objective of this study is to investigate the potential of 18F-FDG-PET/ CT to predict mortality in IPF.A total of 113 IPF patients (93 males, 20 females, mean age ± SD: 70 ± 9 years) were prospectively recruited for 18F-FDG-PET/CT. The overall maximum pulmonary uptake of 18F-FDG (SUVmax), the minimum pulmonary uptake or background lung activity (SUVmin), and target-to-background (SUVmax/ SUVmin) ratio (TBR) were quantified using routine region-of-interest analysis. Kaplan-Meier analysis was used to identify associations of PET measurements with mortality. We also compared PET associations with IPF mortality with the established GAP (gender age and physiology) scoring system. Cox analysis assessed the independence of the significant PET measurement(s) from GAP score. We investigated synergisms between pulmonary 18F-FDG-PET measurements and GAP score for risk stratification in IPF patients.During a mean follow-up of 29 months, there were 54 deaths. The mean TBR ± SD was 5.6 ± 2.7. Mortality was associated with high pulmonary TBR (p = 0.009), low forced vital capacity (FVC; p = 0.001), low transfer factor (TLCO; p < 0.001), high GAP index (p = 0.003), and high GAP stage (p = 0.003). Stepwise forward-Wald-Cox analysis revealed that the pulmonary TBR was independent of GAP classification (p = 0.010). The median survival in IPF patients with a TBR < 4.9 was 71 months, whilst in those with TBR > 4.9 was 24 months. Combining PET data with GAP data ("PET modified GAP score") refined the ability to predict mortality.A high pulmonary TBR is independently associated with increased risk of mortality in IPF patients.
BackgroundSmall benign insulinomas are hard to localise, leading to difficulties in planning of surgical interventions. We aimed to prospectively assess the insulinoma detection rate of single-photon emission CT in combination with CT (SPECT/CT) with a glucagon-like peptide-1 receptor avid radiotracer, and compare detection rates with conventional CT/MRI techniques.MethodsIn our prospective imaging study, we enrolled adults aged 25–81 years at centres in Germany, Switzerland, and the UK. Eligible patients had proven clinical and biochemical endogenous hyperinsulinaemic hypoglycaemia and no evidence for metastatic disease on conventional imaging. CT/MRI imaging was done at referring centres according to standard protocols. At three tertiary nuclear medicine centres, we used whole body planar images and SPECT/CT of the abdomen up to 168 h after injection of 111In-[Lys40(Ahx-DTPA-111In)NH2]-exendin-4 (111In-DTPA-exendin-4) to identify insulinomas. Consenting patients underwent surgery and imaging findings were confirmed histologically.FindingsBetween Oct 1, 2008, and Dec 31, 2011, we recruited 30 patients. All patients underwent 111In-DTPA-exendin-4 imaging, 25 patients underwent surgery (with histological analysis), and 27 patients were assessed with CT/MRI. 111In-DTPA-exendin-4 SPECT/CT correctly detected 19 insulinomas and four additional positive lesions (two islet-cell hyperplasia and two uncharacterised lesions) resulting in a positive predictive value of 83% (95% CI 62–94). One true negative (islet-cell hyperplasia) and one false negative (malignant insulinoma) result was identified in separate patients by 111In-DTPA-exendin-4 SPECT/CT. Seven patients (23%) were referred to surgery on the basis of 111In-DTPA-exendin-4 imaging alone. For 23 assessable patients, 111In-DTPA-exendin-4 SPECT/CT had a higher sensitivity (95% [95% CI 74–100]) than did CT/MRI (47% [27–68]; p=0·011).Interpretation111In-DTPA-exendin-4 SPECT/CT could provide a good second-line imaging strategy for patients with negative results on initial imaging with CT/MRI.FundingOncosuisse, the Swiss National Science Foundation, and UK Department of Health.
To test the hypothesis that sequential (18)F-fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) is a correlative marker in metastatic clear cell renal cancer (mRCC), patients were treated with sunitinib. Three sequential scans were conducted to determine whether the timing of the investigation was relevant.Forty-four untreated mRCC patients were enrolled into this prospective phase II study. (18)F-FDG-PET/CT scans were conducted before (n = 44) and after 4 weeks (n = 43) and 16 weeks (n = 40) of sunitinib given at standard doses. The primary endpoint was to correlate FDG-PET/CT response (20% reduction in SUV(max)) at 4 and 16 weeks with overall survival (OS).Forty-three (98%) patients had FDG-PET/CT avid lesions at diagnosis (median SUV(max) = 6.8, range: <2.5-18.4). In multivariate analysis, a high SUV(max) and an increased number of PET-positive lesions correlated with shorter OS [HR: 3.30 (95% CI: 1.36-8.45) and 3.67 (95% CI: 1.43-9.39), respectively]. After 4 weeks of sunitinib, a metabolic response occurred in 24 (57%) patients, but this did not correlate with progression-free survival (HR for responders = 0.87; 95% CI: 0.40-1.99) or OS (HR for responders = 0.80; 95% CI: 0.34-1.85). After 16 weeks of treatment, disease progression on FDG-PET/CT occurred in 28% (n = 12) patients which correlated with a decreased OS and PFS [HR = 5.96 (95% CI: 2.43-19.02) and HR = 12.13 (95% CI: 3.72-46.45), respectively].Baseline FDG-PET/CT yields prognostic significant data. FDG-PET/CT responses occur in the majority of patients after 4 weeks of therapy; however, it is not until 16 weeks when the results become prognostically significant.
As bone marrow is richer in blood supply than bone, it seems likely that the initial spread of metastatic disease is to marrow rather than bone. In order to explore this possibility and, hopefully, the rate at which the cortex becomes affected, 20 patients have undergone bone marrow imaging as well as conventional bone studies. The bone and marrow images were compared for each patient and the number and sizes of the lesions noted. Results suggest that marrow lesions are often larger or more numerous than corresponding bone lesions, indicating that bone involvement may well follow marrow. Accurate positioning and experienced interpretation of the images are vital as it is difficult to detect “cold” lesions in areas of poor count rate, and obscuring liver and spleen uptake. The immediate benefit to patients has been to confirm the diagnosis of secondary disease in equivocal bone images.
There is no consensus on the optimum mode of imaging in patients with painful shoulder lesions. There is a particular paucity of scintigraphic data. As a result, the strengths and weaknesses of scintigraphy cannot be adequately compared to other imaging techniques used in shoulder imaging. This study evaluated whether specific patterns of scintigraphic abnormality could be detected in patients with painful shoulders seen in rheumatological practice using 99mTc-methylene diphosphonate (MDP).Scintigraphic abnormalities were recorded in consecutive patients presenting to a rheumatology clinic with unilateral shoulder pain. Patients were subdivided according to patterns of clinical abnormality consistent with a working diagnosis of a lesion located in the subacromial region, adhesive capsulitis (frozen shoulder) or a lesion likely to be located in the glenohumeral joint. Patterns of radiopharmaceutical distribution in different regions of the shoulder were evaluated in the light of clinical data and the results of shoulder radiographs.Technetium-99m-MDP scans were abnormal in 19 of 24 (79%) patients, and radiographs were abnormal in 8 of 24 (33%) patients. Distinct patterns of 99mTc-MDP image abnormality were identified: an increase in 99mTc-MDP uptake in the coracoid, acromion and medial humeral head on anterior planar images, together with an absence of posterior planar image abnormality, frequently occurred in association with a working diagnosis of a lesion located in the subacromial region. Posterior planar 99mTc-MDP image abnormalities always occurred in patients with clinical features consistent with a diagnosis of adhesive capsulitis. There was an 85% agreement between two observers' scores when 99mTc-MDP distribution in specific shoulder regions was graded.Distinct patterns of 99mTc-MDP distribution may be associated with clinically-distinct patterns of abnormality in patients with painful shoulder lesions. Further studies to elucidate a role for 99mTc-MDP scintigraphy in this patient group are warranted.
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