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Purpose: 18 F-fluorodeoxyglocose positron emission tomography (FDG PET) plays a significant role in the diagnosis of cardiac sarcoidosis (CS). Texture analysis is a group of computational methods for evaluating the inhomogeneity among adjacent pixels or voxels. We investigated whether texture analysis applied to myocardial FDG uptake has diagnostic value in patients with CS., Methods: Thirty-seven CS patients (CS group), and 52 patients who underwent FDG PET/CT to detect malignant tumors with any FDG cardiac uptake (non-CS group) were studied. A total of 36 texture features from the histogram, gray-level co-occurrence matrix (GLCM), gray-level run length matrix (GLRLM), gray-level zone size matrix (GLZSM) and neighborhood gray-level difference matrix (NGLDM), were computed using polar map images. First, the inter-operator and inter-scan reproducibility of the texture features of the CS group were evaluated. Then, texture features of the patients with CS were compared to those without CS lesions., Results: Twenty-eight of the 36 texture features showed high inter-operator reproducibility with intraclass correlation coefficients (ICCs) over 0.80. In addition, 17 of the 36 showed high inter-scan reproducibility with ICCs over 0.80. The SUVmax showed no difference between the CS and non-CS group [7.36 ± 2.77 vs. 8.78 ± 4.65, p = 0.45, area under the curve (AUC) = 0.60]. By contrast, 16 of the 36 texture features could distinguish CS from non-CS grsoup with AUC > 0.80. Multivariate logistic regression analysis after hierarchical clustering concluded that long-run emphasis (LRE; P = 0.0004) and short-run low gray-level emphasis (SRLGE; P = 0.016) were significant independent factors that could distinguish between the CS and non-CS groups. Specifically, LRE was significantly higher in CS than in non-CS (30.1 ± 25.4 vs. 11.4 ± 4.6, P < 0.0001), with high diagnostic ability (AUC = 0.91), and had high inter-operator reproducibility (ICC = 0.98)., Conclusions: The texture analysis had high inter-operator and high inter-scan reproducibility. Some of texture features showed higher diagnostic value than SUVmax for CS diagnosis. Therefore, texture analysis may have a role in semi-automated systems for diagnosing CS.

Background: (18)F-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., Methods: Eighty-two patients with suspected CS were divided into 2 preparation protocols: one with a minimum 6-h fast without LCD preparation (group A, n = 58) and the other with a minimum 18-h fast with LCD preparation (group B, n = 24). All patients also received intravenous unfractionated heparin (UFH; 50 IU/kg) before the injection of FDG., Results: Group A showed a higher percentage of diffuse LV uptake than did group B (27.6 vs 0.0%, P = .0041). Group B showed higher FFA levels (1159.1  ±  393.0, 650.5  ±  310.9 μEq/L, P < .0001) than did group A. Patients with diffuse LV uptake (n = 16) showed lower FFA levels than did other patients (n = 66) (432.1  ±  296.1, 888.4  ±  381.4 μEq/L, P < .0001). UFH administration significantly increased FFAs in both groups, even in the patients with diffuse LV FDG uptake., Conclusions: The 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.

Purpose: Cardiac 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. (18)F-fluorodeoxyglucose ((18)F-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 (18)F-FDG uptake and its relationship to the distribution of LV wall (18)F-FDG-positive segments in the LV, and to evaluate whether patients with positive RV (18)F-FDG uptake met the 1993 diagnostic criteria of the Japanese Ministry of Health and Welfare (JMHW) guidelines regarding sarcoidosis with suspected cardiac involvement., Method: Fifty-nine biopsy-proven extra-cardiac sarcoidosis patients (age 56.1 ± 14.7 years) with suspected cardiac involvement based on abnormal electrocardiography or echocardiography findings underwent fasting (18)F-FDG PET or PET/CT. The LV wall was divided into 17 segments and RV uptake was also evaluated., Result: Among 59 patients, 35 (59.3%) showed some abnormal (18)F-FDG uptake in the RV and/or LV wall. With respect to the RV wall, 13 (22.0%) showed abnormal (18)F-FDG uptake. The number of LV-involved segments was 4.8 ± 2.4 in the patients with RV (18)F-FDG uptake, which was significantly higher than in the patients without RV uptake, 1.8 ± 2.2 (P < 0.0001). Patients with RV uptake more frequently met the diagnostic criteria of the 1993 JMHW guidelines (n = 27), than did those without RV uptake (84.6 vs. 34.8%, P = 0.0033)., Conclusion: (18)F-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, (18)F-FDG RV uptake may be useful in diagnosing cardiac involvement in sarcoidosis., Clinical Trial Registration: UMIN000006533.

Purpose: Cardiac involvement in sarcoidosis is one of the leading causes of death associated with abnormalities of the conduction system. (18)F-FDG PET is useful for detecting inflammatory lesions in cardiac sarcoidosis. However, the relationship between ECG abnormalities and focal (18)F-FDG uptake has not been studied. The aim of this study was to evaluate the relationship between electrocardiogram (ECG) abnormalities and the location of elevated myocardial (18)F-FDG uptake in patients with sarcoidosis., Methods: Included in the study were 50 patients (56.3 ± 14.9 years old) with histologically proven sarcoidosis with suspected cardiac involvement based on ECG or echocardiography. All patients had fasted for at least 6 h and were given unfractionated heparin (50 IU/kg) intravenously to reduce the physiological (18)F-FDG uptake in the myocardium. The left ventricle (LV) wall was divided into 17 segments by visual analysis. Obvious accumulation in each segment was defined as positive., Results: Of the 50 patients, 33 showed some ECG abnormalities, including atrioventricular (AV) block in 13. Patients with abnormal ECG findings had a higher number of regions with (18)F-FDG uptake than patients without ECG abnormality (3.48 ± 2.73 vs. 1.41 ± 2.09 regions, p = 0.0051). Among ECG abnormalities, the predictor for interventricular septum wall (18)F-FDG involvement was AV block (p = 0.0025)., Conclusion: Patients with ECG abnormalities showed a higher number of abnormal (18)F-FDG myocardial uptake regions than patients without ECG abnormalities. In particular, focal (18)F-FDG uptake in the interventricular septum in cardiac sarcoidosis was associated with AV block. Therefore, determination of regional (18)F-FDG distribution might contribute to patient management in cardiac sarcoidosis.

Cardiac sarcoidosis (CS) is a rare and potentially life-threatening disease that causes conduction disturbance, systolic dysfunction, and most notably sudden cardiac death. Accurate diagnosis of CS is thus mandatory; however, a reliable approach that enables diagnosis of CS with high sensitivity and specificity has yet to be established. Recent studies have demonstrated the promising potential of (18)F-fluoro-2-deoxyglucose positron emission tomography ((18)F-FDG PET) in the diagnosis and assessment of CS. Indeed, (18)F-FDG PET provides a wide variety of advantages over previous imaging modalities; however, there are pitfalls and limitations that should be recognized. In this review article, (1) the rationale for (18)F-FDG PET application in CS, (2) suitable pretest preparations, and (3) evaluation protocols for the (18)F-FDG PET images obtained will be addressed. In particular, sufficient suppression of physiological (18)F-FDG uptake in the heart is essential for accurate assessment of CS. Also, (4) recent studies addressing the diagnostic role of (18)F-FDG PET and (5) the clinically important differences between (18)F-FDG PET and other imaging technologies will be reviewed. For example, active sarcoid lesions and their response to steroid treatment will be better detected by (18)F-FDG PET, whereas fibrotic lesions might be shown more clearly by magnetic resonance imaging or other nuclear myocardial perfusion imaging. In the last decade, (18)F-FDG PET has substantially enhanced detection of CS; however, CS would be better evaluated by a combination of multiple modalities. In the future, advances in (18)F-FDG PET and other emerging imaging modalities are expected to enable better management of patients with sarcoidosis.

In April 2005, a 72-year-old woman with pulmonary sarcoidosis exhibited focal (18)F-fluoro-2-deoxyglucose ((18)F-FDG) uptake in her heart on (18)F-FDG positron emission tomography (PET). Although Japanese guidelines for diagnosing cardiac sarcoidosis were not met at this point, electrocardiography, echocardiography, and magnetic resonance imaging became diagnostic for cardiac sarcoidosis 1 year later. In the present case report, the potential of (18)F-FDG PET in the early recognition of cardiac sarcoidosis in comparison with other imaging modalities is discussed.

Purpose: Despite accumulating reports on the clinical value of (18)F-fluoro-2-deoxyglucose positron emission tomography (18F-FDG PET) and magnetic resonance imaging (MRI) in the assessment of cardiac sarcoidosis, no studies have systematically compared the images of these modalities., Methods: Twenty-one consecutive patients with suspected cardiac sarcoidosis underwent cardiac examinations that included 18F-FDG PET and MRI. The association of 18F-FDG PET and MRI findings with blood sampling data such as serum angiotensin converting enzyme levels was also evaluated., Results: Eight of 21 patients were diagnosed as having cardiac sarcoidosis according to the Japanese Ministry of Health and Welfare Guidelines for Diagnosing Cardiac Sarcoidosis. Sensitivity and specificity for diagnosing cardiac sarcoidosis were 87.5 and 38.5%, respectively, for 18F-FDG PET, and 75 and 76.9%, respectively, for MRI. When the 18F-FDG PET and MRI images were compared, 16 of 21 patients showed positive findings in one (n = 8) or both (n = 8) of the two modalities. In eight patients with positive findings on both images, the distribution of the findings differed among all eight cases. The presence of positive findings on 18F-FDG PET was associated with elevated serum angiotensin-converting enzyme levels; this association was not demonstrated on MRI., Conclusions: Both 18F-FDG PET and MRI provided high sensitivity for diagnosing cardiac sarcoidosis in patients with suspected cardiac involvement, but the specificity of (18)F-FDG PET was not as high as previously reported. The different distributions of the findings in the two modalities suggest the potential of 18F-FDG PET and MRI in detecting different pathological processes in the heart.

Aims: To evaluate the value of (18)F-fluoro-2-deoxyglucose positron emission tomography ((18)F-FDG PET) in detecting cardiac sarcoidosis., Methods and Results: Thirty-two patients with sarcoidosis and thirty controls were recruited. All subjects underwent cardiac (18)F-FDG PET after a 6 h fasting period, and subjects with sarcoidosis underwent blood testing, ECG, echocardiography, and (67)Ga and (99m)Tc-sestamibi (MIBI) scintigraphy. We classified (18)F-FDG PET images into four patterns ('none', 'diffuse', 'focal', and 'focal on diffuse') and found that all the control subjects exhibited either none (n=16) or diffuse (n=14) pattern. In contrast, fifteen subjects with sarcoidosis exhibited none, seven exhibited diffuse, eight exhibited focal, and two exhibited focal on diffuse patterns, with the prevalence of the focal and focal on diffuse patterns being significantly higher in the sarcoidosis group when compared with the control group (P<0.001). None of the 32 subjects with sarcoidosis exhibited abnormal findings on (67)Ga scintigraphy, and 4 exhibited abnormal findings on (99m)Tc-MIBI scintigraphy., Conclusion: Focal uptake of the heart on (18)F-FDG PET images is a characteristic feature of patients with sarcoidosis. Furthermore, (18)F-FDG PET has the potential to detect cardiac sarcoidosis that cannot be diagnosed by (67)Ga or (99m)Tc-MIBI scintigraphy.