Momoko Okasaki

Long fasting is effective in inhibiting physiological myocardial 18F-FDG uptake and for evaluating active lesions of cardiac sarcoidosis

BackgroundF-fluorodeoxyglucose (FDG) positron emission tomography (PET) is a promising modality for detecting active lesions of cardiac sarcoidosis (CS). However, determining whether 18F-FDG uptake in the myocardium is physiological is challenging due to metabolic shift in myocardial cells. Although methods for inhibiting physiological myocardial 18F-FDG uptake have been proposed, no standard methods exist. This study therefore aimed to compare the effect of an 18-h fast (long fasting (LF)) with heparin loading plus a 12-h fast (HEP) before 18F-FDG PET scan.MethodsWe analyzed the effects of LF and HEP on the inhibition of physiological myocardial 18F-FDG uptake in healthy subjects (18 in HEP and 19 in LF) and in patients with known or suspected CS (96 in HEP and 69 in LF). In CS, the lower uptake of 18F-FDG in the myocardium was evaluated. A visual four-point scale was used to assess myocardial 18F-FDG uptake in comparison with hepatic uptake (1 lower, 2 similar, 3 somewhat higher, 4 noticeably higher).ResultsMyocardial 18F-FDG uptake was 1.68 ± 1.06 in LF and 3.17 ± 1.16 in HEP in healthy subjects (p < 0.0001), whereas it was 1.48 ± 0.99 in LF and 2.48 ± 1.33 in HEP in CS patients (p < 0.0001). Logistic regression and regression trees revealed the LF was the most effective in inhibiting myocardial 18F-FDG uptake. In addition, serum free fatty acid levels on intravenous 18F-FDG injection were a possible biomarker.ConclusionsLF is effective in inhibiting myocardial 18F-FDG uptake, and consequently, it could be useful for evaluating active lesions of CS in 18F-FDG PET images.

Evaluation of Wegener’s granulomatosis using 18F-fluorodeoxyglucose positron emission tomography/computed tomography

ObjectiveWegener’s granulomatosis (WG) is a relatively rare disease characterized by granulomatous necrotizing vasculitis that primarily involves small- and medium-sized vessels. Systemic findings observed on 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) have not been well reported. The purpose of this study was to evaluate the FDG PET/CT imaging in the diagnosis and follow-up of patients with WG.Materials and methodsThirteen FDG PET/CT images obtained for 8 patients (2 men and 6 women) with WG were retrospectively analyzed. Of these, 6 were performed for diagnosis, 2 for restaging and follow-up, and 5 for assessment of treatment efficacy. Maximum standardized uptake values (max SUVs) and visual analyses were used to interpret the FDG PET/CT images. In addition, nonenhanced CT findings obtained during FDG PET/CT were described.ResultsWG lesions of the upper respiratory tract and lung were more clearly detected by FDG PET/CT fusion imaging than by nonenhanced CT alone, and all of the active lesions showed decreased FDG uptake after treatment. In addition, FDG PET/CT can provide complementary information to indicate biopsy site based on FDG uptakes.ConclusionsFDG PET/CT is a feasible modality for evaluating lesion activities, therapeutic monitoring, and follow-up of WG. Furthermore, biopsy sites of WG lesions may be determined by FDG PET/CT.

Utility of fluorodeoxyglucose positron emission tomography/computed tomography for early diagnosis and evaluation of disease activity of relapsing polychondritis: a case series and literature review

OBJECTIVE Relapsing polychondritis (RPC) is relatively rare and early diagnosis is difficult. We investigated the utility of fluorodeoxyglucose (FDG)-PET/CT for the diagnosis of RPC and evaluation of disease activity. METHODS Five RPC patients undergoing FDG-PET/CT in our hospital between 2006 and 2012 were studied. Eight RPC cases examined by PET reported in the literature were also assessed. Data from a total of 13 patients were analysed. RESULTS Typical FDG accumulation was noted in the tracheobronchial trees of nine patients, the costal cartilage of five, joints of five, larynx of four, nasal cavity/paranasal sinuses of three, auricles of three, lymph nodes of three and the aorta of one. One patient showed nasal chondritis on a PET scan despite the absence of nasal changes on physical examination. Of five patients with costochondritis, four remained asymptomatic. Of nine patients with airway FDG accumulation, eight developed respiratory symptoms and all had CT abnormalities. In the other patient, airway FDG accumulation was evident despite the absence of airway symptoms and a lack of abnormalities in the respiratory function test and CT. PET also revealed bronchial chondritis in asymptomatic patients. The mean maximum standardized uptake values (SUVmax) of the upper and lower airways was 5.79 (s.d. 2.87) and 6.47 (s.d. 4.08), respectively. In five patients with a PET after treatment, FDG accumulation had diminished with symptomatic and inflammatory improvement. CONCLUSION FDG-PET/CT is a potentially powerful tool for the early diagnosis of RPC, especially in patients without easily biopsied organ involvement. This modality also facilitates evaluation of disease extent and disease activity during treatment.

4′-[Methyl-11C]-Thiothymidine PET/CT for Proliferation Imaging in Non–Small Cell Lung Cancer

A new tracer, 4′-[methyl-11C]-thiothymidine (11C-4DST), has been developed as an in vivo cell proliferation marker based on the DNA incorporation method. This study evaluated the potential of 11C-4DST PET/CT for imaging proliferation in non–small cell lung cancer (NSCLC), compared with 18F-FDG PET/CT. Methods: Eighteen patients with lung lesions were examined by PET/CT using 11C-4DST and 18F-FDG. We constructed decay-corrected time–activity curves of 9 major regions as the mean standardized uptake value. We then compared the maximum standardized uptake value (SUVmax) of lung tumors on both 11C-4DST and 18F-FDG PET/CT with the Ki-67 index of cellular proliferation and with CD31-positive vessels as a marker of angiogenesis in surgical pathology. Results: NSCLC was pathologically confirmed in 19 lesions of 18 patients. Physiologic accumulation of 11C-4DST was high in liver, kidney, and bone marrow and low in aorta, brain, lung, and myocardium. Biodistribution of 11C-4DST was almost stable by 20 min after injection of 11C-4DST. Mean 11C-4DST SUVmax for lung cancer was 2.9 ± 1.0 (range, 1.5–4.7), significantly different from mean 18F-FDG SUVmax, which was 6.2 ± 4.5 (range, 0.9–17.3; P < 0.001). The correlation coefficient between SUVmax and Ki-67 index was higher with 11C-4DST (r = 0.82) than with 18F-FDG (r = 0.71). The correlation coefficient between SUVmax and CD31 was low with both 11C-4DST (r = 0.21) and 18F-FDG (r = 0.21), showing no significant difference between the tracers. Conclusion: A higher correlation with proliferation of lung tumors was seen for 11C-4DST than for 18F-FDG. 11C-4DST PET/CT may allow noninvasive imaging of DNA synthesis in NSCLC.

Differences in fluorodeoxyglucose positron emission tomography/computed tomography findings between elderly onset rheumatoid arthritis and polymyalgia rheumatica

Abstract Objectives. To compare the fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) findings in patients with elderly-onset rheumatoid arthritis (EORA) with those in patients with polymyalgia rheumatica (PMR), two conditions with similar clinical presentations. Methods. We retrospectively analyzed the FDG-PET/CT findings in 10 patients with EORA and 27 patients with PMR admitted to our department between 2006 and 2012. Results: No significant difference was observed in the median patient ages at the time of FDG-PET/CT scans in the EORA and PMR groups (73.5 vs. 78.0 years, respectively). Significant differences in both FDG uptake scores and standardized uptake values were observed between the two groups in the ischial tuberosities, spinous processes, and wrists. No significant differences were detected in the shoulders and hips. However, specific uptake patterns were observed in each group: circular and linear uptake patterns were observed around the humeral head in the EORA group, whereas focal and non-linear uptake patterns were observed in the PMR group. Moreover, focal uptake in front of the hip joint, indicating iliopectineal bursitis, tended to be limited to the PMR group. High sensitivity (92.6%) and specificity (90%) were observed for PMR diagnoses when at least three of the following five items were satisfied: characteristic findings of shoulder and iliopectineal bursitis, FDG uptake in ischial tuberosities and spinal spinous processes, and lack of FDG uptake in the wrists. Conclusion. The differences in the degree of uptake at each lesion and in uptake patterns at the shoulders and hips are potentially useful for obtaining a definitive diagnosis.

Imaging spectrum and pitfalls of 18F-fluorodeoxyglucose positron emission tomography/computed tomography in patients with tuberculosis

Mycobacterium tuberculosis (TB) is one of the most prominant diseases frequently causing false positive lesions in oncologic surveys using 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT), since TB granulomas are composed of activated macrophages and lymphocytes with high affinity for glucose. These pitfalls of 18F-FDG PET/CT are important for radiologists. Being familiar with 18F-FDG images of TB could assist in preventing unfavorable clinical results based on misdiagnoses. In addition, 18F-FDG PET/CT has the advantage of being able to screen the whole body, and can clearly detect harboring TB lesions as high uptake foci. This article details the spectrum and pitfalls of 18F-FDG PET/CT imaging in TB.

Prognostic value of post-treatment (18)F-FDG PET/CT for advanced head and neck cancer after combined intra-arterial chemotherapy and radiotherapy.

OBJECTIVE To clarify the prognostic value of post-treatment (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) in patients with advanced head and neck squamous cell carcinoma (HNSCC) after combined intra-arterial chemotherapy and radiotherapy (IACR). METHODS Thirty-six patients with HNSCC who underwent IACR were recruited. The period from the end of IACR to the last post-treatment (18)F-FDG PET/CT examination was 8-12 weeks. Both patient-based and lesion-based analyses were used to evaluate the PET/CT images. For lesion-based analysis, 36 regions (12 lesions of recurrences and 24 scars at primary sites) were selected. The Kaplan-Meier method was used to assess the overall survival (OS) stratified by (18)F-FDG uptake or visual interpretation results. RESULTS Twelve patients with recurrence were identified by six months after IACR. The sensitivity and specificity in the patient-based analysis were 67% (8/12) and 88% (21/24), respectively. The mean OS was estimated to be 12.1 months (95% CI, 6.3-18.0 months) for the higher maximum standardized uptake value (SUVmax) group (n=7) and 44.6 months (95% CI, 39.9-49.3 months) for the lower SUVmax group (n=29). OS in the higher SUVmax group (cut-off point, 6.1) or positive visual interpretation group was significantly shorter than that in the lower SUVmax or negative visual interpretation group (P<0.001 and P<0.05, respectively). CONCLUSIONS The SUVmax and visual interpretation of HNSCC on post-IACR (18)F-FDG PET/CT can provide prognostic survival estimates.

Evaluation of a new motion correction algorithm in PET/CT: combining the entire acquired PET data to create a single three-dimensional motion-corrected PET/CT image.

PurposeThis study evaluated the potential of Q.Freeze algorithm for reducing motion artifacts, in comparison with ungated imaging (UG) and respiratory-gated imaging (RG). Patients and methodsTwenty-nine patients with 53 lesions who had undergone RG 18F-FDG PET/CT were included in this study. Using PET list mode data, five series of PET images [UG, RG, and QF images with an acquisition duration of 3 min (QF3), 5 min (QF5), and 10 min (QF10)] were reconstructed retrospectively. The image quality was evaluated first. Next, quantitative metrics [maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean), SD, metabolic tumor volume, signal to noise ratio, or lesion to background ratio] were calculated for the liver, background, and each lesion, and the results were compared across the series. ResultsQF10 and QF5 showed better image quality compared with all other images. SUVmax in the liver, background, and lesions was lower with QF10 and QF5 than with the others, but there were no statistically significant differences in SUVmean and the lesion to background ratios. The SD with UG and RG was significantly higher than that with QF5 and QF10. The metabolic tumor volume in QF3 and QF5 was significantly lower than that in UG. ConclusionThe Q.Freeze algorithm can improve the quality of PET imaging compared with RG and UG.

18f-fdg and 11c-methionine Pet/ct Findings in a Case With Anti-nmda (nr2b) Receptor Encephalitis

A 70-year-old man was brought to the emergency room in an unconscious state. A cerebrospinal fluid analysis demonstrated strongly positive autoantibody glutamate receptor epsilon 2 (GluRe2) titer, corresponding to anti-N-methyl-D-aspartate receptor (anti-NMDAR) NR2B autoantibody titers. The patient was diagnosed with limbic encephalitis. Brain MRI showed a high intensity in the left anterior-temporal lobe on T2WI/fluid attenuated inversion recovery (FLAIR) images, without enhancement. In this area, 18F-FDG PET showed a relatively decreased uptake, but 11C-methionine PET showed mildly increased uptake. Despite the patients near-full functional recovery, similar PET findings were confirmed 6 months later. The mechanism of regional cerebral increased 11C-methionine uptake in anti-NMDAR (NR2B) receptor encephalitis is unknown.

Amyloid imaging mismatch.

An 82-year-old man with suspected systemic amyloidosis and complete atrioventricular block underwent vascular biopsy during his pacemaker implantation with pathology showing amyloid deposits. 99mTc-aprotinin SPECT revealed increased radiotracer uptake along the left ventricular wall, consistent with cardiac amyloidosis. 11C-PiB PET/CT performed for the evaluation of amyloid deposits in the brain showed findings suggestive of Alzheimer disease without abnormal radiotracer concentration in the myocardium to match the 99mTc-aprotinin SPECT findings. Dynamic PET images showed increased 11C-PiB concentration in the left ventricular myocardium at 2 minutes after injection, with subsequent tracer clearance by approximately 5 minutes, consistent with normal 11C-PiB biodistribution.