Background: F-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. Methods: We 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). Results: Myocardial 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. Conclusions: LF 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.

Objective Wegener’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 methods Thirteen 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. Results WG 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. Conclusions FDG 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.

Objectives To investigate fluorodeoxyglucose (FDG) accumulation in large joints, bursas, and large vessels in patients with polymyalgia rheumatica (PMR) using 18-FDG positron emission tomography/computed tomography (PET/CT) and to differentiate PMR from similar diseases. Methods Fourteen untreated patients with active PMR and 17 control patients with rheumatoid arthritis (n = 11) or other active rheumatic diseases (n = 6) underwent 18-FDG PET/CT. FDG uptake in large joints, bursas and vertebral spinous processes was evaluated by calculating maximum standardised uptake values and by visual scoring (scale 0–4). PET scan images were scored in seven vascular regions, and total vascular scores (range 0–21) were calculated. Results Polymyalgia rheumatica patients showed increased FDG uptake in ischial tuberosities, greater trochanters, and lumbar spinous processes. Positive results at two or more of these sites showed high sensitivity (85.7%) and specificity (88.2%) for the diagnosis of PMR, and shoulder or hip-joint involvement showed low disease specificity. High FDG accumulations were found in the aortas and subclavian arteries of two PMR patients who were asymptomatic for temporal arteritis and scanty synovium and perisynovium, based on FDG uptake. PET/CT images of the 12 PMR patients without apparent vascular involvement showed synovitis and/or perisynovitis. Conclusions Fluorodeoxyglucose-PET/CT may be useful for the detection of PMR lesions, which are difficult to identify using other methods.

Ito K, et al. Korean J Radiol. 2016 May-Jun;17(3):424-434. http://dx.doi.org/10.3348/kjr.2016.17.3.424

The aim of this study was to evaluate the impact of (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) on the management of patients with infectious spondylitis. Twenty-nine patients with infectious spondylitis (9 with tuberculous spondylitis and 20 with pyogenic spondylitis) who had undergone an (18)F-FDG PET/CT examination were retrospectively evaluated; 42 lesions were detected. A useful impact on the clinical management of infection therapy (start or longer duration of antibiotic therapy, or surgical intervention, etc) was defined as a strong impact, whereas gaining new information not affecting the clinical management of infection therapy from (18)F-FDG PET/CT was defined as a weak impact. No impact was defined as not obtaining any new information influencing infection therapy. (18)F-FDG PET/CT had a strong impact on the clinical management of 52% (15 of 29) of the patients. (18)F-FDG PET/CT detected 10 cases of spondylitis and one artificial graft infection that the clinician had not recognized, and the therapeutic period was extended in these patients. In five patients with tuberculous spondylitis, the (18)F-FDG PET/CT images were used to decide the biopsy sites in three patients and to determine which lesions required surgery in two patients. (18)F-FDG PET/CT is useful for detecting infectious spondylitis.