Atsuro Masuda

The effects of 18-h fasting with low-carbohydrate diet preparation on suppressed physiological myocardial 18F-fluorodeoxyglucose (FDG) uptake and possible minimal effects of unfractionated heparin use in patients with suspected cardiac involvement sarcoidosis

AbstractBackground18F-fluorodeoxyglucose (FDG) PET plays an important role in the detection of cardiac involvement sarcoidosis (CS). However, diffuse left ventricle (LV) wall uptake sometimes makes it difficult to distinguish between positive uptake and physiological uptake. The aims of this study were to evaluate the effects of 18-h fasting with low-carbohydrate diet (LCD) vs a minimum of 6-h fasting preparations on diffuse LV FDG uptake and free fatty acid (FFA) levels in patients with suspected CS.MethodsEighty-two patients with suspected CS were divided into 2 preparation protocols: one with a minimum 6-h fast without LCD preparation (group A, nxa0=xa058) and the other with a minimum 18-h fast with LCD preparation (group B, nxa0=xa024). All patients also received intravenous unfractionated heparin (UFH; 50xa0IU/kg) before the injection of nFDG.ResultsGroup A showed a higher percentage of diffuse LV uptake than did group B (27.6 vs 0.0%, Pxa0=xa0.0041). Group B showed higher FFA levels (1159.1u2009xa0±xa0u2009393.0, 650.5u2009xa0±xa0u2009310.9 μEq/L, Pxa0<xa0.0001) than did group A. Patients with diffuse LV uptake (nxa0=xa016) showed lower FFA levels than did other patients (nxa0=xa066) (432.1u2009xa0±xa0u2009296.1, 888.4u2009xa0±xa0u2009381.4 μEq/L, Pxa0<xa0.0001). UFH administration significantly increased FFAs in both groups, even in the patients with diffuse LV FDG uptake.ConclusionsThe 18-h fast with LCD preparation significantly reduced diffuse LV uptake and increased FFA levels. In particular, the FFA level was significantly lower in patients with LV diffuse uptake than in patients without LV diffuse uptake. Acutely increasing plasma FFA through the use of UFH may not have a significant role in reducing physiological LV FDG uptake.

Simultaneous cardiac imaging to detect inflammation and scar tissue with (18)F-fluorodeoxyglucose PET/MRI in cardiac sarcoidosis.

A 50-year-old female was referred to our hospital for complete right bundle branch block, which was detected by annual health check-up. Although she had no symptoms, echocardiography demonstrated left ventricular wall thinning and aneurysm at basal inter-ventricular septum and apex of the left ventricle (Figure 1, arrows). Thus, we suspected cardiac sarcoidosis and performed F-fluorodeoxyglucose (FDG) PET/MRI. After low carbohydrate diet for 24 hour before imaging and fasting for more than 18 hour, the patient was administered heparin 50 IU/kg intravenously to suppress physiological FDG uptake on the myocardium. Image acquisition was initiated 60 minutes after FDG administration.Maximum intensity projection revealed FDG uptake on bilateral hilar lymph nodes and mediastinal lymph nodes (Figure 2, arrows). Intense FDG uptake and late gadolinium enhancement (LGE) were observed in the left ventricle and in the right ventricle (Figure 3). T2-weighted images (T2WI) also showed high signal intensity indicating myocardial edema (Figure 3, arrows). Fusion images showed concordance of myocardial FDG uptake and LGE in most regions, but it should be noted that there was a discrepancy among the areas of FDG uptake, LGE, and high-intensity region on T2WI. This discrepancy revealed by simultaneous PET/MRI reminds us differential aspects of myocardial FDG uptake (active inflammation), LGE (fibrotic scar), and high-intensity region on T2WI (myocardial edema). PET/MRI is a useful imaging technology to provide helpful diagnostic information and guide a therapeutic strategy of cardiac sarcoidosis.

Right ventricular 18 F-FDG uptake is an important indicator for cardiac involvement in patients with suspected cardiac sarcoidosis

PurposeCardiac sarcoidosis is most commonly found in the left ventricular (LV) free wall. Presence in the right ventricle (RV) is less common but might be useful for detecting cardiac involvement of sarcoidosis. 18F-fluorodeoxyglucose (18F-FDG) PET has been used to detect LV regions with cardiac sarcoidosis. However, the same has not been done for RV involvement. The aims of the current study were to evaluate RV 18F-FDG uptake and its relationship to the distribution of LV wall 18F-FDG-positive segments in the LV, and to evaluate whether patients with positive RV 18F-FDG uptake met the 1993 diagnostic criteria of the Japanese Ministry of Health and Welfare (JMHW) guidelines regarding sarcoidosis with suspected cardiac involvement.MethodFifty-nine biopsy-proven extra-cardiac sarcoidosis patients (age 56.1xa0±xa014.7xa0years) with suspected cardiac involvement based on abnormal electrocardiography or echocardiography findings underwent fasting 18F-FDG PET or PET/CT. The LV wall was divided into 17 segments and RV uptake was also evaluated.ResultAmong 59 patients, 35 (59.3xa0%) showed some abnormal 18F-FDG uptake in the RV and/or LV wall. With respect to the RV wall, 13 (22.0xa0%) showed abnormal 18F-FDG uptake. The number of LV-involved segments was 4.8xa0±xa02.4 in the patients with RV 18F-FDG uptake, which was significantly higher than in the patients without RV uptake, 1.8xa0±xa02.2 (Pxa0<xa00.0001). Patients with RV uptake more frequently met the diagnostic criteria of the 1993 JMHW guidelines (nxa0=xa027), than did those without RV uptake (84.6 vs. 34.8xa0%, Pxa0=xa00.0033).Conclusion18F-FDG PET identified RV involvement less frequently than LV involvement in this study population. However, patients who had RV uptake showed a greater number of LV-involved segments and met the JMHW diagnostic criteria more frequently. Although RV uptake is less frequent, 18F-FDG RV uptake may be useful in diagnosing cardiac involvement in sarcoidosis.Clinical trial registrationUMIN000006533.

Administration of unfractionated heparin with prolonged fasting could reduce physiological 18F-fluorodeoxyglucose uptake in the heart.

Background The physiological uptake of 18F-fluorodeoxyglucose (FDG) in the heart often interferes with the accurate diagnosis of inflammatory cardiac diseases (CDs). Unfractionated heparin (UFH) administration may suppress its uptake through the alteration of myocardial metabolism. Purpose To clarify the effectiveness of UFH administration to suppress the physiological FDG uptake in the heart. Material and Methods The physiological FDG uptake in the heart was compared among 178 patients who fasted less than 18u2009h, 37 patients who fasted more than 18u2009h, and 64 patients who fasted more than 18u2009h and were administered UFH (UFH-CD group) prior to FDG PET/CT. Free fatty acid (FFA), triglyceride, insulin, and blood glucose levels were measured after UFH administration. Myocardial FDG uptake was evaluated by visual assessment and on the basis of maximum standardized uptake value (SUVmax). Results In the UFH-CD group, the FFA level increased 15u2009min after UFH administration (Pu2009<u20090.01). Blood glucose and insulin levels remained unchanged (Pu2009=u2009NS). FDG physiological uptake was observed in 69% of the patients who fasted less than 18u2009h, 38% of the patients fasted more than 18u2009h, and 22% of the UFH-CD group (Pu2009<u20090.01 for trend). SUVmax decreased in the UFH-CD group compared with the patients who fasted less than 18u2009h (Pu2009<u20090.01) and the patients who fasted more than 18u2009h (Pu2009=u20090.029). Conclusion UFH administration and fasting more than 18u2009h could effectively suppress FDG physiological uptake in the heart and can be a useful method of detecting inflammatory CDs and tumors.

Cardiac fibroma with high 18F-FDG uptake mimicking malignant tumor.

We here present a case of cardiac fibroma mimicking a malignant tumor due to the Ffluorodeoxyglucose (FDG) high accumulation. A 23year-old woman was found asymptomatic bradycardia by a health checkup. Echocardiography detected the wall thickening in the basal septal portion of the left ventricle (LV) (supplementary movies). As cardiac tumor was suspected, further evaluations including FDG positron emission tomography (PET)/computed tomography (CT) and enhanced magnetic resonance imaging (MRI) were performed. To suppress physiological myocardial uptake, this patient fasted for 18 h with unfractionated heparin (50 IU kg) i.v. injected 15 minutes prior to FDG administration. FDG PET/CT showed focal tracer accumulation in the entire mass (Figure 1A, B). Cardiac MRI showed iso-intense on T1weighed image (T1WI) (Figure 1C), hypo-intense on T2-weighed image (T2WI) (Figure 1D), and hyper-intense on late gadolinium enhancement (LGE) (Figure 1E) in the mass. Endo-myocardial biopsy pathologically revealed a benign intracardiac fibroma (Figure 2). Cardiac fibroma is a benign connective tissue tumor derived from fibroblasts. It occurs predominantly in infants and young children, typically found as a large tumor, more frequently in the anterior or septal LV wall. The MRI findings could clarify the tissue characteristics of a wellcircumscribed tumor with low iso-intense on T1WI, low intense on T2WI because of their dense, fibrous nature, and hyper-intense on LGE that reflects the characterization of a great extracellular space, which was consisted of fibroblasts interspersed among large amounts of collagen, for gadolinium accumulation. It remained unclear why the fibroma indicated high FDG accumulation in this case. However, there was a case report of nonossifying fibroma that showed high FDG accumulation similarly to our study. FDG PET/CT is a powerful tool to differentiate the malignant cardiac lesion from benign ones. However, this case suggests that even the focal increased FDG uptake was detected in the mass, the specific MRI findings could lead to the correct diagnosis of the cardiac fibroma. Electronic supplementary material The online version of this article (doi:10.1007/s12350-015-0362-6) contains supplementary material, which is available to authorized users. Reprint requests: Osamu Manabe, MD, PhD, Department of Nuclear Medicine, Hokkaido University Graduate School of Medicine, Kita 15 Nishi 7, Kita-Ku, Sapporo 060-8638, Japan; osamumanabe817@ med.hokudai.ac.jp J Nucl Cardiol 2017:24;323–4. 1071-3581/

Volume-based glucose metabolic analysis of FDG PET/CT: The optimum threshold and conditions to suppress physiological myocardial uptake

34.00 Copyright 2015 American Society of Nuclear Cardiology.

Cardiac imaging with 18F-fluorodeoxyglucose PET/MRI in hypertrophic cardiomyopathy

ObjectiveFDG PET/CT plays a significant role in the diagnosis of inflammatory heart diseases and cardiac tumors. We attempted to determine the optimal FDG uptake threshold for volume-based analyses and to evaluate the relationship between the myocardial physiological uptake volume in FDG PET and several clinical factors.MethodsA total of 190 patients were retrospectively analyzed. The cardiac metabolic volume (CMV) was defined as a volume within the boundary determined by a threshold (SUVmean of blood poolxa0×xa01.5).ResultsThe SUVmean of the blood pool measured in the descending aorta (DA) (rxa0=xa00.86, intraclass correlation coefficient [ICC]xa0=xa00.93, Pxa0<xa00.0001) and that in the left ventricle (LV) cavity (rxa0=xa00.87, ICCxa0=xa00.90, Pxa0<xa00.0001) showed high inter-operator reproducibility. However, the SUVmean in the LV cavity showed a significant correlation with the CMV (Pxa0=xa00.0002, rxa0=xa00.26). The CMV in the patients who fasted <xa018xa0hours were significantly higher (49.7xa0u2009±u2009xa073.2 vs. 18.0xa0u2009±xa0u200953.8xa0mL, Pxa0=xa00.0013) compared to the patients with >xa018-hour fasting. The multivariate analysis demonstrated that only the fasting period >xa018xa0hours was independently associated with CMVxa0=xa00.ConclusionOur findings revealed that the DA is suitable to decide the threshold for the volume-based analysis. The fasting time was significantly associated with the cardiac FDG uptake.

Vulnerable plaque on the common iliac artery detected by 18F-FDG PET/MRI

A 57-year-old female was referred to our hospital for severe left ventricular hypertrophy (LVH). Although she had no symptoms and no history of hypertension, echocardiography demonstrated severe LVH in the mid LV to the apex with no asymmetric septal hypertrophy. Thus, we suspected apical type of HCM and performed FDG-PET/MRI. After fasting for more than 18 hours, the patient was administered unfractionated heparin 50 IU/kg intravenously 15 minutes before FDG administration to suppress physiological FDG uptake on the myocardium. Image acquisition was initiated 60 min after FDG administration. Cine MRI images (Videos 1 and 2 in supplementary material) showed severe hypertrophy in the middle region of the LV with no LV outflow obstruction. However, myocardial thinning and reduced wall motion were observed in the apex. Intense FDG uptake was observed in the LV, suggesting a metabolic substrate switching from fatty acids to glucose, and FDG uptake was relatively low, and late gadolinium enhancement was evident in the apex (Figures 1, 2). Fusion images clearly showed FDG uptake on the hypertrophied myocardium. It should be noted that, although we used prolonged fasting and intravenous heparin, distinguishing physiological uptake of FDG from pathological uptake related to metabolic switching might be sometimes challenging. Simultaneous PET/MRI was able to reconstruct accurate fusion images and provided anatomic and metabolic characterizations of the hypertrophied heart. Myocardial biopsy revealed cardiomyocyte hypertrophy with mere disarray, slight fibrosis, and no inflammatory cell infiltration, consistent with pathological findings of HCM. There were no signs suggestive of secondary cardiomyopathy, which represents cardiac hypertrophy. The PET/MRI is

Assessment of myocardial viability of a patient with old myocardial infarction by 18 F-fluorodeoxyglucose PET/MRI

A 69-year-old man with suspected peripheral arterial disease underwent F-FDG PET/MRI to evaluate arterial stenosis and the characteristics of plaques in the arteries. After fasting for more than 6 h, 185 MBq of F-FDG was administered 60 min before image acquisition. MR angiography without contrast enhancement showed stenosis of the common iliac arteries bilaterally (a). The left common iliac artery showed marked FDG uptake (b, d, red arrows) that corresponded to a stenosis with high signal intensity on T1-weighted images (c, red arrow) that suggested that the lesion was a vulnerable plaque [1, 2]. No FDG uptake was observed in the right common iliac artery, although there was a significant stenosis. Arterial angiography and intravascular ultrasonography revealed a hypoechoic but ruptured plaque in the left common iliac artery and a hypoechoic plaque in the right common iliac artery (e, red arrowheads). Increased uptake of F-FDG in an atherosclerotic plaque is associated with plaque vulnerability [1, 3]. MRI has also been used to characterize the tissue of atherosclerotic plaques [2]. Combined PET/MRI plays an important role in evaluating vulnerable plaque from the point of view of functional and structural information. Furthermore, combined PET/MRI is able to acquire images simultaneously and provides precise fusion images. We report here the first case of the effective evaluation of a vulnerable plaque in the common iliac artery by F-FDG PET/MRI.

Whole body assessment by 18F-FDG PET in a patient with infective endocarditis

Hybrid PET/MRI has been used for the evaluation of several cardiac diseases. PET/MRI provides profound insights about the pathophysiology of cardiac diseases. However, a clinical application of the cardiac PET/MRI has not been fully investigated. This case emphasizes the value of F-fluorodeoxyglucose (FDG) PET/MRI for the evaluation of myocardial viability. This novel modality provides useful information including myocardial function, metabolism, anatomy, and myocardial viability by a one-stop examination.