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Introduction: Assessment of myocardial uptake of Tc-99m-pyrophosphate (Tc-99m PYP) is pivotal in distinguishing transthyretin-associated cardiac amyloidosis (ATTR) from light chain amyloid (AL). It is often difficult to differentiate myocardial uptake from blood pool radioactivity with planar imaging or SPECT. We studied whether simultaneous dual-isotope Tc-99m PYP/Tl-201 SPECT improves assessment of Tc-99m PYP uptake compared to single-isotope SPECT., Methods: Simultaneous Tc-99m PYP/Tl-201 dual-isotope SPECT was acquired in 112 patients studied for possible cardiac amyloidosis. Visual interpretation was performed by two observers on single-isotope followed by dual-isotope SPECT. Heart-to-contralateral lung ratio (H/CL) of myocardial counts quantified by single-isotope and dual-isotope SPECT was compared between ATTR, AL, and no amyloidosis groups., Results: In 112 patients (39 ATTR and 26 AL patients, and 47 no amyloidosis), a lower proportion of no amyloidosis and AL patients were classified visually as equivocal with dual-isotope SPECT compared to single-isotope SPECT (2% vs 19%, P = 0.02 and 8% vs 35%, P = 0.04, respectively). H/CL measurements with single-isotope and dual-isotope were lower in AL and no amyloidosis patients vs ATTR patients (P < 0.05). Interobserver agreement of visual assessment was improved with dual-isotope SPECT (P = 0.03). AUCs for detection of ATTR by visual assessment and H/CL quantification were higher with dual-isotope (0.94 and 0.95, respectively) compared to single-isotope SPECT (0.84, P = 0.001 and 0.92, P = 0.02)., Conclusion: Tc-99m PYP/Tl-201 SPECT improves visual differentiation of ATTR and AL amyloidosis compared to single-isotope SPECT. Visual assessment and H/CL quantitation with dual-isotope SPECT provide similar discrimination between patients with ATTR and AL amyloidosis.

Sarcoidosis is a significant disease affecting the heart. 18 F-fluorodeoxyglucose (FDG) positron emission tomography (PET) is a well-validated method for identifying significant focal inflammatory sarcoid lesions. The recent progress in image interpretation in nuclear medicine improves the diagnosis and the risk stratification in patients with cardiac sarcoidosis. Especially, metabolic activity, texture analysis, phase analysis, right ventricle assessment, and digital PET/CT are promising methods to assess cardiac sarcoidosis. This review focuses on the latest data analyses and image interpretation used in nuclear medicine to assess cardiac sarcoidosis., Competing Interests: None., (© The Japanese Society of Nuclear Cardiology 2020.)

Aims: Myocardial perfusion imaging without and with quantitative myocardial blood flow (MBF) and myocardial flow reserve (MFR) plays an important role in the diagnosis and risk stratification of patients with stable coronary artery disease (CAD). We aimed to quantify the effects of coronary revascularization on regional stress MBF and MFR and to determine whether the presence of subendocardial infarction was associated with these changes., Methods and Results: Forty-seven patients with stable CAD were prospectively enrolled. They underwent 15O-water positron emission tomography at baseline and 6 months after optimal medical therapy alone (n = 16), percutaneous coronary intervention (PCI) (n = 18), or coronary artery bypass grafting (CABG) (n = 13). Stenosis of ≥50% diameter was detected in 98/141 vessels (70%). The regional MFR was significantly increased from baseline to follow-up [1.84 (interquartile range, IQR 1.28-2.17) vs. 2.12 (IQR 1.69-2.63), P < 0.001] in vessel territories following PCI or CABG due to an increase in the stress MBF [1.33 (IQR 0.97-1.67) mL/g/min vs. 1.64 (IQR 1.38-2.17) mL/g/min, P < 0.001], whereas there was no significant change in the regional stress MBF or MFR in vessel territories without revascularization. A multilevel mixed-effects models adjusted for baseline characteristics, subendocardial infarction assessed by cardiovascular magnetic resonance imaging, and intra-patient correlation showed that the degree of angiographic improvement after coronary revascularization was significantly associated with increased regional stress MBF and MFR (P < 0.05 for all)., Conclusion: Coronary revascularization improved the regional stress MBF and MFR in patients with stable CAD. The magnitude of these changes was associated with the extent of revascularization independent of subendocardial infarction., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2019. For permissions, please email: journals.permissions@oup.com.)

Purpose: To improve the evaluation of low-attenuation plaque (LAP) by using semiautomated software and to assess whether the use of a proposed automated function (LAP editor) that excludes voxels adjacent to the outer vessel wall improves the relationship between LAP and the presence and size of the lipid-rich component (LRC) verified at intravascular US. At coronary CT angiography, quantification of LAP can improve risk stratification. Plaque, defined as the area between the vessel and the lumen wall, is prone to partial volume effects from the surrounding pericoronary adipose tissue., Materials and Methods: The percentage of LAP (%LAP), defined as the percentage of noncalcified plaque with an attenuation value lower than 30 HU (LAP/total plaque volume) at greater than or equal to 0 mm (%LAP 0 ), greater than or equal to 0.1 mm (%LAP 0.1 ), greater than or equal to 0.3 mm (%LAP 0.3 ), greater than or equal to 0.5 mm (%LAP 0.5 ), and greater than or equal to 0.7 mm (%LAP 0.7 ) inward from the vessel wall boundaries, were quantified in 155 plaques in 90 patients who underwent coronary CT angiography before intravascular US. At intravascular US, the LRC was identified by using echo attenuation, and its size was measured by using the attenuation score (summed score/analysis length) based on the attenuation arc (1 = < 90°, 2 = 90° to < 180°, 3 = 180° to < 270°, 4 = 270°-360°) for every 1 mm., Results: Use of LAP editing improved the ability for discriminating LRC (areas under receiver operating characteristic curve: 0.667 with %LAP 0 , 0.713 with %LAP 0.1 [ P < .001 for comparison with %LAP 0 ]), 0.778 with %LAP 0.3 [ P < .001], 0.825 with %LAP 0.5 [ P < .001], 0.802 with %LAP 0.7 [ P = .002]). %LAP 0.5 had the strongest correlation ( r = 0.612, P < .001) with LRC size, whereas %LAP 0 resulted in the weakest correlation ( r = 0.307; P < .001)., Conclusion: Evaluation of LAP at coronary CT angiography can be significantly improved by excluding voxels that are adjacent to the vessel wall boundaries by 0.5 mm. Supplemental material is available for this article. © RSNA, 2019., (2019 by the Radiological Society of North America, Inc.)

Background: We investigated the prognostic predictive value of the combination of fluorodeoxyglucose (FDG)- and fluoromisonidazole (FMISO)-PET in patients with non-small cell lung carcinoma (NSCLC) treated with stereotactic body radiation therapy (SBRT)., Patients and Methods: We prospectively examined patients with pathologically proven NSCLC; all underwent FDG and FMISO PET/CT scans before SBRT. PET images were acquired using a whole-body time-of-flight PET-CT scanner with respiratory gating. We classified them into recurrent and non-recurrent groups based on their clinical follow-ups and compared the groups' tumor diameters and PET parameters (i.e., maximum of the standardized uptake value (SUVmax), metabolic tumor volume, tumor-to-muscle ratio, and tumor-to-blood ratio). We performed univariate analysis to evaluate the impact of the PET variables on the patients' progression-free survival (PFS). We divided the patients by thresholds of FDG SUVmax and FMISO SUVmax obtained from receiver operating characteristic analysis for assessment of recurrence rate and PFS., Results: Thirty-two NSCLC patients (19 male and 13 females; median age, 83 years) were enrolled. All received SBRT. At the study endpoint, 23 patients (71.9%) were non-recurrent and nine patients (28.1%) had recurrent disease. Significant between-group differences were observed in tumor diameter and all the PET parameters, demonstrating that those were significant predictors of the recurrence in all patients. In the 22 patients with tumors > 2 cm, tumor diameter and FDG SUVmax were not significant predictors. Thirty-two patients were divided into three patterns from the thresholds of FDG SUVmax (6.81) and FMISO SUVmax (1.89); A, low FDG and low FMISO (n = 14); B, high FDG and low FMISO (n = 8); C, high FDG and high FMISO (n = 10). No pattern A patient experienced tumor recurrence, whereas two pattern B patients (25%) and seven pattern C patients (70%) exhibited recurrence. A Kaplan-Meier analysis of all patients revealed a significant difference in PFS between patterns A and B (p = 0.013) and between patterns A and C (p < 0.001). In the tumors > 2 cm patients, significant differences in PFS were demonstrated between pattern A and C patients (p = 0.002)., Conclusion: The combination of FDG- and FMISO-PET can identify patients with a baseline risk of recurrence and indicate whether additional therapy might be performed to improve survival.

Takotsubo cardiomyopathy (TC) is a syndrome of transient left ventricular (LV) dysfunction mimicking acute coronary syndrome. Although the mechanisms underlying the occurrence of TC are unknown, several imaging techniques contribute to its diagnosis. Here we review the current knowledge about TC, in particular, the pathophysiology and the role of imaging including nuclear cardiovascular medicine.

Rationale: Adaptive servo-ventilation (ASV), a novel respiratory support therapy for sleep disorders, may improve cardiac function in heart failure (HF). However, the reasons that ASV improves cardiac function have not been fully studied especially in sympathetic nervous function (SNF). The purpose of the present study was to investigate the effects of ASV therapy on cardiac SNF in patients with HF., Methods: We evaluated ASV therapeutic effects before and 6 months after ASV therapy in 9 HF patients [57.3 ± 17.3 years old, left ventricular ejection fraction (LVEF) 36.1 ± 16.7%]. We performed echocardiography, polysomnography, biomarkers, 11 C-hydroxyephedrine (HED) PET as a presynaptic function marker and planar 123 I-metaiodobenzylguanidine (MIBG) to evaluate washout rate., Results: ASV therapy reduced apnea-hypopnea index (AHI) and improved plasma brain natriuretic peptide (BNP) concentration. In 123 I-MIBG imaging, the early heart/mediastinum (H/M) ratio increased after ASV therapy (2.19 ± 0.58 to 2.40 ± 0.67; P = 0.045). Washout rate did not change (23.8 ± 7.3% to 23.8 ± 8.8%; P = 0.122). Global 11 C-HED retention index (RI) improved from 0.068 ± 0.033/s to 0.075 ± 0.034/s (P = 0.029)., Conclusions: ASV reduced AHI and improved BNP. ASV might initially improve presynaptic cardiac sympathetic nervous function in HF patients after 6 months of treatment.

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.

Objective: FDG 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., Methods: A 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 pool × 1.5)., Results: The SUVmean of the blood pool measured in the descending aorta (DA) (r = 0.86, intraclass correlation coefficient [ICC] = 0.93, P < 0.0001) and that in the left ventricle (LV) cavity (r = 0.87, ICC = 0.90, P < 0.0001) showed high inter-operator reproducibility. However, the SUVmean in the LV cavity showed a significant correlation with the CMV (P = 0.0002, r = 0.26). The CMV in the patients who fasted < 18 hours were significantly higher (49.7  ±  73.2 vs. 18.0  ±  53.8 mL, P = 0.0013) compared to the patients with > 18-hour fasting. The multivariate analysis demonstrated that only the fasting period > 18 hours was independently associated with CMV = 0., Conclusion: Our 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.

Patient misidentification in imaging examinations has become a serious problem in clinical settings. Such misidentification could be prevented if patient characteristics such as sex, age, and body weight could be predicted based on an image of the patient, with an alert issued when a mismatch between the predicted and actual patient characteristic is detected. Here, we tested a simple convolutional neural network (CNN)-based system that predicts patient sex from FDG PET-CT images. This retrospective study included 6,462 consecutive patients who underwent whole-body FDG PET-CT at our institute. The CNN system was used for classifying these patients by sex. Seventy percent of the randomly selected images were used to train and validate the system; the remaining 30% were used for testing. The training process was repeated five times to calculate the system's accuracy. When images for the testing were given to the learned CNN model, the sex of 99% of the patients was correctly categorized. We then performed an image-masking simulation to investigate the body parts that are significant for patient classification. The image-masking simulation indicated the pelvic region as the most important feature for classification. Finally, we showed that the system was also able to predict age and body weight. Our findings demonstrate that a CNN-based system would be effective to predict the sex of patients, with or without age and body weight prediction, and thereby prevent patient misidentification in clinical settings.

Purpose: The aim of this study was to verify coronary flow velocity reserve (CFVR) on the left main trunk (LMT) in comparison with myocardial flow reserve (MFR) by 15 O-labeled water positron emission tomography (PET) (MFR-PET) in both the healthy adults and the patients with coronary artery disease (CAD), and to evaluate the feasibility of CFVR to detect CAD., Methods: Eighteen healthy adults and 13 patients with CAD were evaluated. CFVR in LMT was estimated by 3T magnetic resonance imaging (MRI) with phase contrast technique. MFR-PET in the LMT territory including anterior descending artery and circumflex artery was calculated as the ratio of myocardial blood flow (MBF)-PET at stress to MBF-PET at rest., Results: There was a significant positive relationship between CFVR and MFR-PET (R = 0.45, P < 0.0001). Inter-observer calculations of CFVR showed good correlation (R 2 = 0.93, P < 0.0001). The CFVR in patients with CAD was significantly lower than that in healthy adults (1.90 ± 0.61 vs. 2.77 ± 1.03, respectively, P = 0.01), which were similar to the results of MFR-PET (2.23 ± 0.84 vs. 3.96 ± 1.04, respectively, P < 0.0001). For the detection of patients with CAD, the area under the curve was 0.78 (P = 0.01). The sensitivity was 0.77 and specificity was 0.72 when a cut-off of 2.15 was used., Conclusion: CFVR by 3T was validated with MFR-PET. CFVR could detect the patients with CAD. This method is a simple and reliable index without radiation or contrast material.

A 34-year-old Japanese woman presented with widespread scaly erythema that had enlarged over 2 years. A skin biopsy revealed the diagnosis of mycosis fungoides (patch stage, T1b N0 M0 B0), a most frequent cutaneous T-cell lymphoma. F-FDG PET/CT scan unexpectedly showed intense uptake on the left sole, which suggested a tumorous mycosis fungoides lesion (SUVmax = 6.2). Careful examination revealed the mass to be a typical plantar wart of 2 cm in diameter that the patient had not recognized. With repeated cryotherapy, the wart disappeared in 6 months, and follow-up F-FDG PET/CT showed no abnormal uptake on the left sole.

Aims: The aim of this study was to determine whether deep convolutional neural network (DCNN)-based features can represent the difference between cardiac sarcoidosis (CS) and non-CS using polar maps., Methods: A total of 85 patients (33 CS patients and 52 non-CS patients) were analyzed as our study subjects. One radiologist reviewed PET/CT images and defined the left ventricle region for the construction of polar maps. We extracted high-level features from the polar maps through the Inception-v3 network and evaluated their effectiveness by applying them to a CS classification task. Then we introduced the ReliefF algorithm in our method. The standardized uptake value (SUV)-based classification method and the coefficient of variance (CoV)-based classification method were used as comparative methods., Results: Sensitivity, specificity and the harmonic mean of sensitivity and specificity of our method with the ReliefF algorithm were 0.839, 0.870 and 0.854, respectively. Those of the SUVmax-based classification method were 0.468, 0.710 and 0.564, respectively, and those of the CoV-based classification method were 0.655, 0.750 and 0.699, respectively., Conclusion: The DCNN-based high-level features may be more effective than low-level features used in conventional quantitative analysis methods for CS classification., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Aims: Coronary flow reserve (CFR) is an integrated measure of the entire coronary vasculature, and is a powerful prognostic marker in coronary artery disease (CAD). The extent to which coronary revascularization can improve CFR is unclear. This study aimed to evaluate the impact of percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG) on CFR in patients with stable CAD., Methods and Results: In a prospective, multicentre observational study, CFR was measured by 15O-water positron emission tomography as the ratio of stress to rest myocardial blood flow at baseline and 6 months after optimal medical therapy (OMT) alone, PCI, or CABG. Changes in the SYNTAX and Leaman scores were angiographically evaluated as indicators of completeness of revascularization. Follow-up was completed by 75 (25 OMT alone, 28 PCI, and 22 CABG) out of 82 patients. The median SYNTAX and Leaman scores, and baseline CFR were 14.5 [interquartile range (IQR): 8-24.5], 5.5 (IQR: 2.5-12.5), and 1.94 (IQR: 1.67-2.66), respectively. Baseline CFR was negatively correlated with the SYNTAX (ρ = -0.40, P < 0.001) and Leaman scores (ρ = -0.33, P = 0.004). Overall, only CABG was associated with a significant increase in CFR [1.67 (IQR: 1.14-1.96) vs. 1.98 (IQR: 1.60-2.39), P < 0.001]. Among patients with CFR <2.0 (n = 41), CFR significantly increased in the PCI [1.70 (IQR: 1.42-1.79) vs. 2.21 (IQR: 1.78-2.49), P = 0.002, P < 0.001 for interaction between time and CFR] and CABG groups [1.28 (IQR: 1.13-1.80) vs. 1.86 (IQR: 1.57-2.22), P < 0.001]. The reduction in SYNTAX or Leaman scores after PCI or CABG was independently associated with the percent increase in CFR after adjusting for baseline characteristics (P = 0.012 and P = 0.011, respectively)., Conclusion: Coronary revascularization ameliorated reduced CFR in patients with obstructive CAD. The degree of improvement in angiographic CAD burden by revascularization was correlated with magnitude of improvement in CFR.

Radionuclide imaging has an advantage for quantitative analyses of the tracer concentration and its temporal changes. Myocardial perfusion and function have been adapted for synchrony analyses. Extracted parameters have been demonstrated to measure ventricular synchrony and even to predict CRT outcomes. ERNA has the advantages of higher temporal resolution, greater reproducibility, and the volumetric analysis of both ventricles that can be applied for analyses of intraventricular synchrony and interventricular synchrony. Several software packages such as Quantitative Gated SPECT, the Emory Cardiac Toolbox, cardioREPO, and Heart Function View are available to assess the LV dyssynchrony parameters from GSPECT. A count-based method is applied to extract the amplitude and phase from each of the reconstructed GSPECT short-axis datasets throughout the cardiac cycle and then subjected to a Fourier analysis, the results of which are displayed on a polar map and histogram. Some of the parameters such as the bandwidth (expressed as the 95% width of the phase histogram) and the standard deviation of the phase are obtained by the phase histogram to assess the intraventricular synchrony. This review paper focuses on the application of the LV dyssynchrony parameters estimated by cardiac SPECT in patients with a heart disease.

Immunoglobulin G4 (IgG4)-related disease can affect the cardiovascular system, including the coronary arteries and pericardium and especially the walls of large and medium-sized vessels. The presence of coronary involvement is critical, as this condition can cause myocardial ischemia or sudden cardiac death. Although histopathologic examination remains the reference standard for detecting organ involvement and diagnosing IgG4-related disease, obtaining biopsy or surgical specimens from the vessel wall is still challenging. Because patients may be only mildly symptomatic, noninvasive imaging evaluation of IgG4-related cardiovascular disease (CVD) has an essential role in not only the diagnosis but also the management of this condition. Multidetector CT is a useful noninvasive examination for establishing the primary diagnosis and defining anatomic landmarks and their relationships. The spectrum of vessel involvement is vast, with varied manifestations. Radiologists should be familiar with inflammatory vasculitis, aneurysmal change, and pseudotumor formation in all vessels and the distribution of these conditions throughout the body. Electrocardiographically gated CT enables accurate, fast, and noninvasive characterization of coronary pathologic conditions and thus has an important advantage over catheter angiography. Combined PET/CT can depict inflammatory processes and help distinguish IgG4-related CVD from atherosclerosis. Familiarity with the PET/CT and CT findings of inflammatory processes involved in IgG4-related CVD is important for accurate diagnosis and evaluation of therapeutic response during follow-up. The multidetector CT and PET/CT characteristics of IgG4-related CVD, such as aortitis, periaortitis, arteritis, and periarteritis and including coronary artery involvement and pericarditis, are reviewed. In addition, the inflammatory process, quantification of active inflammation, and therapeutic response during follow-up associated with IgG4-related CVD are described. Online DICOM image stacks are available for this article. © RSNA, 2018.

Background: Cardiac sarcoidosis (CS) is a rare but potentially life-threatening disease that causes conduction disturbance, systolic dysfunction, and, most notably, sudden cardiac death. 18 F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) plays important roles not only in diagnosing CS but also in evaluating the effects of anti-inflammatory therapy. A volume-based analysis of parameters measured by FDG PET, so-called cardiac metabolic volume (CMV), has emerged as a new assessment tool. CMV is measured as the volume within the boundary determined by a reference tissue such as the liver and the blood pool uptake. However, there is a possibility that oral steroid therapy could lead to variations of the liver and the blood pool uptake. Here, we attempted to evaluate the steroid effects on the liver and the blood pool uptake. A total of 38 CS patients who underwent FDG PET/CT before and during steroid therapy were retrospectively enrolled. Volumes of interest (VOIs) were placed in the right lobe of the liver and descending aorta (DA). The maximum standardized uptake value (SUVmax), SUVmean, and SUVpeak of the liver and DA were compared between time points before and during steroid therapy., Results: The SUVmax, SUVmean, and SUVpeak of the liver during steroid therapy significantly increased from the time point before the therapy (SUVmax 3.5 ± 0.4 vs. 3.8 ± 0.6, p = 0.014; SUVmean 2.7 ± 0.3 vs. 3.0 ± 0.5, p = 0.0065; SUVpeak 3.0 ± 0.4 vs. 3.4 ± 0.6, p = 0.006). However, the SUVmax, SUVmean, and SUVpeak in the DA did not significantly change (SUVmax 2.2 ± 0.3 vs. 2.2 ± 0.4, p = 0.46; SUVmean 1.9 ± 0.3 vs. 2.0 ± 0.4, p = 0.56; SUVpeak 2.0 ± 0.3 vs. 2.0 ± 0.3, p = 0.70)., Conclusions: We measured FDG uptake in the liver and blood pool before and during steroid therapy. Steroid therapy increased the liver uptake but not the blood pool uptake. Our findings suggested that the DA uptake is a more suitable threshold than liver uptake to evaluate therapeutic effects using volume-based analysis of cardiac FDG PET.

Cardiovascular disease (CVD) is the leading cause of death and disease burden worldwide. Nuclear myocardial perfusion imaging with either single-photon emission computed tomography or positron emission tomography has been used extensively to perform diagnosis, monitor therapies, and predict cardiovascular events. Several radiopharmaceutical tracers have recently been developed to evaluate CVD by targeting myocardial perfusion, metabolism, innervation, and inflammation. This article reviews old and newer used in nuclear cardiac imaging.

We have developed the method for dynamic 320-row multidetector computed tomography (MDCT)-derived quantitative coronary flow reserve (CFRCT) and hyperemic myocardial blood flow (MBFCT). We evaluated diagnostic value of CFRCT and hyperemic MBFCT for detecting obstructive coronary artery disease (CAD) in per-patient and per-vessel analysis, and their relations with the severity of CAD burden.Adenosine stressed and rest dynamic myocardial perfusion MDCT were prospectively performed in patients with known or suspected CAD. Per-patient and per-vessel MBFCT were estimated from dynamic perfusion images in rest and hyperemic phases, and per-patient and per-vessel CFRCT were calculated from the ratio of rest and hyperemic MBFCT. Degree of stenosis was evaluated by coronary CT angiography (CTA) and invasive coronary angiography (ICA). Obstructive stenosis was defined as ≥70% stenosis in ICA. CAD burden with MDCT was calculated by logarithm transformed coronary artery calcium (CAC) score and the CTA-adapted Leaman risk score (CT-LeSc). A logistic regression analysis was used to measure the receiver-operating characteristic curve and corresponding area under the curve (AUC) for the detection of obstructive CAD.Twenty-seven patients and 81 vessels were eligible for this study. Sixteen patients had obstructive CAD, and 31 vessels had obstructive stenosis. Using an optimal cutoff, the CFRCT and hyperemic MBFCT had the moderate diagnostic values in per-patient (AUC = 0.89 and 0.86, respectively) and per-vessel (AUC = 0.79 and 0.76, respectively). Per-patient CFRCT and hyperemic MBFCT exhibited a moderate inverse correlation with CAC score and the CT-LeSc.Per-patient and per-vessel CFRCT as well as hyperemic MBFCT had moderate diagnostic value for detecting obstructive CAD. These per-patient values exhibited a moderate inverse correlation with CAD burden. CFRCT and hyperemic MBFCT might add quantitative functional information for evaluating patients with CAD.

We herein report a rare case of mucinous tubular and spindle cell carcinoma (MTSCC) in an 80-year-old woman. A well circumscribed tumor located on the right kidney was discovered incidentally as a result of screening non-contrast CT. Fluorodeoxyglucose positron emission tomography (FDG PET)/CT showed the increased tracer accumulation in the tumor. The histological diagnosis was MTSCC, which is a rare and only recently established subtype of the malignant renal cell carcinoma (RCC). The present case suggests the clinical benefit of a high uptake of FDG combined with enhanced contrast CT in the differentiation of MTSCCs and other RCCs.

With the increasing availability of positron emission tomography (PET) myocardial perfusion imaging, the absolute quantification of myocardial blood flow (MBF) has become popular in clinical settings. Quantitative MBF provides an important additional diagnostic or prognostic information over conventional visual assessment. The success of MBF quantification using PET/computed tomography (CT) has increased the demand for this quantitative diagnostic approach to be more accessible. In this regard, MBF quantification approaches have been developed using several other diagnostic imaging modalities including single-photon emission computed tomography, CT, and cardiac magnetic resonance. This review will address the clinical aspects of PET MBF quantification and the new approaches to MBF quantification.

Purpose: To evaluate heterogeneity of myocardial contraction in relation to extensive late gadolinium enhancement (LGE) in hypertrophic cardiomyopathy (HCM) patients with preserved left ventricular ejection fraction, using fast strain-encoded magnetic resonance imaging., Materials and Methods: Twenty-two HCM patients and 24 age-matched control subjects were included in this retrospective study. The regional and global peak values of longitudinal and circumferential strain (LS regional , LS global , CS regional , CS global ), and their regional heterogeneities were evaluated using coefficients of variation (LS CoV , CS CoV ) in relation to LGE. Receiver operating characteristic curve analysis was performed to identify patients with a total left ventricular myocardial LGE ≥ 15%., Results: LS global in HCM patients was significantly decreased compared to that in controls (- 14.4 ± 2.4% vs - 17.2 ± 2.0%; p = 0.0004), while CS global was not (p = 1.0). Negative LGE segments demonstrated decreased LS regional in HCM patients compared to in controls (p < 0.0001), while CS regional was not decreased. CS CoV demonstrated the largest area under the curve (AUC) (0.91), with high sensitivity (83%) and specificity (94%) for detection of HCM patients with extensive LGE, while the AUC of LS CoV was low (0.49)., Conclusion: The heterogeneity in CS regional has a high diagnostic value for detection of HCM patients with extensive LGE.

Background: The quantification of myocardial blood flow (MBF) and coronary flow reserve (CFR) are useful approaches for evaluating the functional severity of coronary artery disease (CAD). 15 O-water positron emission tomography (PET) is considered the gold standard method for MBF quantification. However, MBF measurements in 15 O-water PET with three-dimensional (3D) data acquisition, attenuation correction using computed tomography (CT), and time of flight have not been investigated in detail or validated. We conducted this study to evaluate the diagnostic potential of MBF measurements using PET/CT for a comparison of a control group and patients suspected of having CAD., Results: Twenty-four patients with known or suspected CAD and eight age-matched healthy volunteers underwent rest and pharmacological stress perfusion studies with 15 O-water PET/CT. The whole and three regional (left anterior descending (LAD), left circumflex (LCX), and right coronary artery (RCA) territory) MBF values were estimated. The CFR was computed as the ratio of the MBF during adenosine triphosphate-induced stress to the MBF at rest. The inter-observer variability was assessed by two independent observers. PET/CT using a 15 O-water dose of 500 MBq and 3D data acquisition showed good image quality. A strong inter-observer correlation was detected in both the whole MBF analysis and the regional analysis with high intra-class correlation coefficients (r > 0.90, p < 0.001). Regional MBF at rest (LAD, 0.82 ± 0.15 ml/min/g; LCX, 0.83 ± 0.17 ml/min/g; RCA, 0.71 ± 0.20 ml/min/g; p = 0.74), MBF at stress (LAD, 3.77 ± 1.00 ml/min/g; LCX, 3.56 ± 1.01 ml/min/g; RCA, 3.27 ± 1.04 ml/min/g; p = 0.62), and CFR (LAD, 4.64 ± 0.90; LCX, 4.30 ± 0.64; RCA, 4.64 ± 0.96; p = 0.66) of the healthy volunteers showed no significant difference among the three regions. The global CFR of the patients was significantly lower than that of the volunteers (2.75 ± 0.81 vs. 4.54 ± 0.66, p = 0.0002). The regional analysis of the patients demonstrated that the CFR tended to be lower in the stenotic region compared to the non-stenotic region (2.43 ± 0.81 vs. 2.95 ± 0.92, p = 0.052)., Conclusions: 15 O-water PET/CT with 3D data acquisition can be reliably used for the quantification of functional MBF and CFR in CAD patients.

Background: We aimed to assess the positivity, distribution, quantitative degree of vessel inflammation, and clinical characteristics of IgG4-related aortitis/periarteritis and periarteritis (IgG4-aortitis), and to examine the difference in these characteristics between cases with and without IgG4-aortitis, using fluorodeoxyglucose positron-emission tomography/computed tomography (FDG-PET/CT) co-registered with contrast-enhanced CT (CECT). We retrospectively evaluated 37 patients with IgG4-related disease (IgG4-RD) who underwent both FDG-PET/CT and CECT. The arterial SUVmax and its value normalized to the background venous blood pool (BP)-the target-to-background ratio (TBR) in the entire aorta and the major first branches-were measured. Active vascular inflammation was considered in cases with a higher FDG uptake than BP and a thickened arterial wall (>2 mm)., Results: Fifteen (41%) patients exhibited IgG4-aortitis. Most patients (80%) showed multiple region involvement. The entire aorta, including the major first branches, were involved, typically showing a thickened wall and high FDG uptakes. The most common site was the iliac arteries (35%), followed by the infrarenal abdominal aorta (33%), thoracic aorta (8%), first branches of the thoracic aorta (8%), suprarenal abdominal aorta (6%), and the first branches of the abdominal aorta (5%). The IgG4-aortitis-positive vessel regions were thickened, with an average maximal wall thickness of 6.3 ± 2.9 mm. The SUVmax and TBR values were significantly higher in the IgG4-aortitis-positive regions (median 3.7 [1.6-5.5] and 2.1 [1.4-3.7], respectively) than in the IgG4-aortitis-negative regions (median 2.1 [1.2-3.7] and 1.3 [0.9-2.3], respectively; p < 0.0001). The IgG4-aortitis-positive group patients were older (69.5 ± 6.0 vs. 63.3 ± 12.6 years, respectively) and had a higher male predominance (80 vs. 55%, respectively) than the negative group, although the differences were not significant (p = 0.17 and p = 0.06, respectively)., Conclusions: We investigated the image characteristics of IgG4-aortitis. The entire aorta and major branches can be involved with more than 2-fold higher FDG uptake than the venous background pool, and with wall thickening. The most common involved site is the iliac arteries, followed by the infrarenal abdominal aorta.

Objectives: To evaluate the diagnostic value of delayed contrast-enhanced computed tomography (DE-CT) for cardiac sarcoidosis (CS) in patients with or without implantable devices, including a quantitative comparison with late gadolinium enhancement cardiac magnetic resonance (LGE-CMR)., Methods: Twenty-four patients (mean age, 64 ± 9 years; 17 women) with known or suspected CS underwent retrospective electrocardiogram-gated DE-CT at 80 kV with knowledge-based iterative model reconstruction. Fourteen patients without implantable devices also underwent LGE-CMR, while ten with pacemakers or implantable cardioverter-defibrillators did not. The presence of hyperenhanced myocardium was assessed visually and quantitatively using a 5-standard deviation threshold above the mean of remote myocardium., Results: Inter-observer agreement for visual detection of hyperenhanced segments on DE-CT was excellent in patients with implantable devices and in those without (κ = 0.91 and κ = 0.94, respectively). Comparisons of the percent area of hyperenhanced myocardium between DE-CT and LGE-CMR on both per-patient and per-segment analyses showed good correlations (r = 0.96 and r = 0.83, respectively; p < 0.001). The sensitivity and specificity of DE-CT for the diagnosis of CS were 94% and 33%., Conclusions: The extent of hyperenhanced lesion with DE-CT showed good agreement with LGE-CMR results. DE-CT showed high sensitivity for detecting CS and may be useful particularly in patients with contraindications to CMR., Key Points: • Delayed contrast-enhanced CT (DE-CT) can be applied to patients with implantable devices. • DE-CT can detect cardiac sarcoidosis (CS) lesions similarly to cardiac MRI. • DE-CT shows high sensitivity for detecting CS. • DE-CT may be useful particularly in patients with contraindications to cardiac MRI.

Purpose: This investigation aimed to identify significant predictors of regional sympathetic denervation quantified by 11 C-hydroxyephedrine (HED) positron emission tomography (PET) in patients with heart failure with preserved left ventricular ejection fraction (HFpEF)., Methods: Included in the study were 34 patients (age 63 ± 15 years, 23 men) with HFpEF (left ventricular ejection fraction ≥40%) and 11 age-matched volunteers without heart failure. Cardiac magnetic resonance imaging was performed to measure left ventricular size and function, and the extent of myocardial late gadolinium enhancement (LGE). 11 C-HED PET was performed to quantify myocardial sympathetic innervation that was expressed as a 11 C-HED retention index (RI, %/min). To identify predictors of regional 11 C-HED RI in HFpEF patients, we propose a multivariate mixed-effects model for repeated measures over segments with an unstructured covariance matrix., Results: Global 11 C-HED RI was significantly lower and more heterogeneous in HFpEF patients than in volunteers (P < 0.01 for all). Regional 11 C-HED RI was correlated positively with systolic wall thickening (r = 0.42, P < 0.001) and negatively with the extent of LGE (r = -0.43, P < 0.001). Segments in HFpEF patients with a large extent of LGE had the lowest regional 11 C-HED RI among all segments (P < 0.001 in post hoc tests). Multivariate analysis demonstrated that systolic wall thickening and the extent of LGE were significant predictors of regional 11 C-HED RI in HFpEF patients (both P ≤ 0.001)., Conclusion: Regional sympathetic denervation was associated with contractile dysfunction and fibrotic burden in HFpEF patients, suggesting that regional sympathetic denervation may provide an integrated measure of myocardial damage in HFpEF.

Myocardial perfusion imaging using positron emission tomography (PET) allows both qualitative and quantitative measurement. The quantitative myocardial blood flow and coronary flow reserve (CFR) are reliable indices for evaluating functional severity, influenced by both epicardial stenosis and microvascular disease. Fractional flow reserve (FFR) also reflects physiological stenosis, which measures the pressure differences across a coronary artery stenosis during maximum hyperemia. Discordance between CFR and FFR has been noticed in estimating the functional significance of coronary stenosis. In this review, we summarize the feasibility of PET for the management of coronary artery disease compared to FFR., (Copyright © 2017. Published by Elsevier Ltd.)

Diastolic dysfunction is important in the pathophysiology of heart failure with preserved ejection fraction (HFpEF). Sympathetic nervous hyperactivity may contribute to the development of diastolic dysfunction. The aim of this study was to determine the relationship between myocardial sympathetic innervation quantified by 11 C-hydroxyephedrine PET and diastolic dysfunction in HFpEF patients. Methods: Forty-one HFpEF patients having an echocardiographic left ventricular ejection fraction of 40% or greater and 12 age-matched volunteers without heart failure underwent the echocardiographic examination and 11 C-hydroxyephedrine PET. Diastolic dysfunction was classified into grades 0-3 by Doppler echocardiography. Myocardial sympathetic innervation was quantified using the 11 C-hydroxyephedrine retention index (RI). The coefficient of variation of 17-segment RIs was derived as a measure of heterogeneity in myocardial 11 C-hydroxyephedrine uptake. Results: Grade 2-3 diastolic dysfunction (DD 2-3 ) was found in 19 HFpEF patients (46%). They had a significantly lower global RI (0.075 ± 0.018 min -1 ) than volunteers (0.123 ± 0.028 min -1 , P < 0.001) and HFpEF patients with grade 0-1 diastolic dysfunction (DD 0-1 ) (0.092 ± 0.024 min -1 , P = 0.046). HFpEF patients with DD 2-3 had the largest coefficient of variation of 17-segment RIs of the 3 groups (18.4% ± 7.7% vs. 14.1% ± 4.7% in HFpEF patients with DD 0-1 , P = 0.042 for post hoc tests). In multivariate logistic regression analysis, a lower global RI (odds ratio, 0.66 per 0.01 min -1 ; 95% confidence interval, 0.38-0.99; P = 0.044) was independently associated with the presence of DD 2-3 in HFpEF patients. Conclusion: Myocardial sympathetic innervation was impaired in HFpEF patients and was associated with the presence of advanced diastolic dysfunction in HFpEF., (© 2017 by the Society of Nuclear Medicine and Molecular Imaging.)

Purpose: Metabolic activity and hypoxia are both important factors characterizing tumor aggressiveness. Here, we used F-18 fluoromisonidazole (FMISO) and F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) to define metabolically active hypoxic volume, and investigate its clinical significance in relation to progression free survival (PFS) and overall survival (OS) in glioblastoma patients., Experimental Design: Glioblastoma patients (n = 32) underwent FMISO PET, FDG PET, and magnetic resonance imaging (MRI) before surgical intervention. FDG and FMISO PET images were coregistered with gadolinium-enhanced T1-weighted MR images. Volume of interest (VOI) of gross tumor volume (GTV) was manually created to enclose the entire gadolinium-positive areas. The FMISO tumor-to-normal region ratio (TNR) and FDG TNR were calculated in a voxel-by-voxel manner. For calculating TNR, standardized uptake value (SUV) was divided by averaged SUV of normal references. Contralateral frontal and parietal cortices were used as the reference region for FDG, whereas the cerebellar cortex was used as the reference region for FMISO. FDG-positive was defined as the FDG TNR ≥1.0, and FMISO-positive was defined as FMISO TNR ≥1.3. Hypoxia volume (HV) was defined as the volume of FMISO-positive and metabolic tumor volume in hypoxia (hMTV) was the volume of FMISO/FDG double-positive. The total lesion glycolysis in hypoxia (hTLG) was hMTV × FDG SUVmean. The extent of resection (EOR) involving cytoreduction surgery was volumetric change based on planimetry methods using MRI. These factors were tested for correlation with patient prognosis., Results: All tumor lesions were FMISO-positive and FDG-positive. Univariate analysis indicated that hMTV, hTLG, and EOR were significantly correlated with PFS (p = 0.007, p = 0.04, and p = 0.01, respectively) and that hMTV, hTLG, and EOR were also significantly correlated with OS (p = 0.0028, p = 0.037, and p = 0.014, respectively). In contrast, none of FDG TNR, FMISO TNR, GTV, HV, patients' age, or Karnofsky performance scale (KPS) was significantly correlated with PSF or OS. The hMTV and hTLG were found to be independent factors affecting PFS and OS on multivariate analysis., Conclusions: We introduced hMTV and hTLG using FDG and FMISO PET to define metabolically active hypoxic volume. Univariate and multivariate analyses demonstrated that both hMTV and hTLG are significant predictors for PFS and OS in glioblastoma patients.

Cartilaginous tumors of the larynx are uncommon neoplasms that sometimes mimic laryngeal cancers. There has been no report of F-FDG PET/CT for the evaluation of laryngeal cartilaginous tumors. We reported 3 cases of laryngeal cartilaginous tumors with the image findings, including CT, FDG PET/CT, and MRI and reviewed literatures. We concluded that the combination of a very high-signal mass on T2-weighted magnetic resonance images and lower FDG uptake might be diagnostic image characteristics for distinguishing laryngeal cartilaginous tumor from laryngeal cancer.

18 F-fluoromisonidazole (FMISO) is a positron emission tomography (PET) tracer that accumulates in hypoxic tissues. We here present a case of suspected cardiac sarcoidosis which was detected with increased FMISO uptake.

Background: Accelerated clearance of (99m)technetium-sestamibi (MIBI) has been observed after reperfusion therapy in patients with acute coronary syndrome (ACS), but the mechanisms have not been fully investigated. MIBI retention may depend on mitochondrial function. The clearance rate of (11)carbon-acetate reflects such mitochondrial functions as oxidative metabolism. The purpose of this study was to examine the mechanisms of accelerated MIBI clearance in ACS. We therefore compared it to oxidative metabolism estimated using (11)C-acetate positron emission tomography (PET)., Methods: Eighteen patients [mean age 69.2 ± 8.7 years, 10 males (56 %)] with reperfused ACS underwent MIBI single-photon emission computed tomography (SPECT), echocardiography, and (11)C-acetate PET within 3 weeks of the onset of ACS. MIBI images were obtained 30 min and 3 h after MIBI administration. Regional left ventricular (LV) function was evaluated by echocardiography. The measurement of oxidative metabolism was obtained through the mono-exponential fitting of the (11)C-acetate time-activity curve (k mono)., Results: Among 95 segments of reperfused myocardium, MIBI SPECT showed 64 normal segments (group N), 14 segments with accelerated MIBI clearance (group AC), and 17 segments with fixed defect (group F). Group AC showed lower k mono than group N (0.041 ± 0.009 vs 0.049 ± 0.010, p = 0.02). Group F showed lower k mono than group N (0.039 ± 0.012 vs 0.049 ± 0.010, p = 0.01). However, k mono was similar in group AC and group F (p = 0.99)., Conclusions: Segments with accelerated MIBI clearance showed reduced oxidative metabolism in ACS. Loss of MIBI retention may be associated with mitochondrial dysfunction.

Background: Comprehensive evaluation of endothelium-dependent and endothelium-independent vascular functions in peripheral arteries and coronary arteries in smokers has never been performed previously. Through the use of brachial artery ultrasound and oxygen-15-labeled water positron emission tomography (PET), we sought to investigate peripheral and coronary vascular dysfunctions in smokers., Methods and Results: Eight smokers and 10 healthy individuals underwent brachial artery ultrasound at rest, during reactive hyperemia [250mmHg cuff occlusion (flow-mediated dilatation (FMD)], and following sublingual nitroglycerin (NTG) administration. Myocardial blood flow (MBF) was assessed through O-15-labeled water PET at rest, during adenosine triphosphate (ATP) administration, and during a cold pressor test (CPT). Through ultrasound, smokers were shown to have significantly reduced %FMD compared to controls (6.62±2.28% vs. 11.29±2.75%, p=0.0014). As assessed by O-15-labeled water PET, smokers were shown to have a significantly lower CPT response than were controls (21.1±9.5% vs. 50.9±16.9%, p=0.0004). There was no relationship between %FMD and CPT response (r=0.40, p=0.097). Endothelium-independent vascular dilatation was similar for both groups in terms of coronary flow reserve with PET (p=0.19). Smokers tended to have lower %NTG in the brachial artery (p=0.055)., Conclusions: Smokers exhibited impaired coronary endothelial function as well as peripheral brachial artery endothelial function. In addition, there was no correlation between PET and ultrasound measurements, possibly implying that while smokers may have systemic vascular endothelial dysfunction, the characteristics of that dysfunction may be different in peripheral arteries and coronary arteries., (Copyright © 2016. Published by Elsevier Ltd.)

Background: Methotrexate-associated lymphoproliferative disorder (MTX-LPD) is a benign lymphoid proliferation or malignant lymphoma in patients who have been treated with MTX. MTX withdrawal and observation for a short period should be considered in the initial management of patients who develop LPD while on MTX therapy. Here we evaluated the diagnostic accuracy and predictive value of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) for MTX-LPD., Methods: We retrospectively investigated the cases of 15 patients clinically suspected of having MTX-LPD. A total of 324 anatomic regions (207 nodal and 117 extranodal regions) were assessed by (18)F-FDG PET/CT and by multi-detector row CT (MDCT). Each anatomic region was classified as either malignant or benign. The uptake of (18)F-FDG was assessed semi-quantitatively with the standardized uptake value maximum (SUVmax), the whole-body metabolic tumor volume (WBMTV), and the whole-body total lesion glycolysis (WBTLG) in order to investigate predictive factors of spontaneous regression after the withdrawal of MTX., Results: MTX-LPD lesions were observed in 92/324 (28.4 %) regions. (18)F-FDG PET/CT showed 90.2 % sensitivity, 97.4 % specificity, and 95.4 % accuracy, values which were significantly higher than those of MDCT (59.8, 94.8, and 84.9 %, respectively. p < 0.002). After the withdrawal of MTX, 9/15 patients (60.0 %) achieved complete response (CR). The SUVmax, WBMTV and WBTLG values of the CR patients were 9.2 (range 2.8-47.1), 44.3 (range 0-362.6) ml, 181.8 (range 0-2180.9) ml, respectively, which were not significantly different from those of the non-CR patients: 10.6 (range 0-24.9), 15.7 (range 0-250.1) ml, and 97.4 (range 0-1052.1) ml., Conclusions: Although (18)F-FDG PET/CT was a useful tool to detect MTX-LPD lesions, none of the (18)F-FDG PET parameters before the withdrawal of MTX could be used to predict CR after the withdrawal of MTX.

Purpose: Tumor necrosis is one of the indicators of tumor aggressiveness. (18)F-fluoromisonidazole (FMISO) is the most widely used positron emission tomography (PET) tracer to evaluate severe hypoxia in vivo. Because severe hypoxia causes necrosis, we hypothesized that intratumoral necrosis can be detected by FMISO PET in brain tumors regardless of their histopathology. We applied FMISO PET to various types of brain tumors before tumor resection and evaluated the correlation between histopathological necrosis and FMISO uptake., Methods: This study included 59 brain tumor patients who underwent FMISO PET/computed tomography before any treatments. According to the pathological diagnosis, the brain tumors were divided into three groups: astrocytomas (group 1), neuroepithelial tumors except for astrocytomas (group 2), and others (group 3). Two experienced neuropathologists evaluated the presence of necrosis in consensus. FMISO uptake in the tumor was evaluated visually and semi-quantitatively using the tumor-to-normal cerebellum ratio (TNR)., Results: In visual analyses, 26/27 cases in the FMISO-positive group presented with necrosis, whereas 28/32 cases in the FMISO-negative group did not show necrosis. Mean TNRs with and without necrosis were 3.49 ± 0.97 and 1.43 ± 0.42 (p < 0.00001) in group 1, 2.91 ± 0.83 and 1.44 ± 0.20 (p < 0.005) in group 2, and 2.63 ± 1.16 and 1.35 ± 0.23 (p < 0.05) in group 3, respectively. Using a cut-off value of TNR = 1.67, which was calculated by normal reference regions of interest, we could predict necrosis with sensitivity, specificity, and accuracy of 96.7, 93.1, and 94.9 %, respectively., Conclusions: FMISO uptake within the lesion indicated the presence of histological micro-necrosis. When we used a TNR of 1.67 as the cut-off value, intratumoral micro-necrosis was sufficiently predictable. Because the presence of necrosis implies a poor prognosis, our results suggest that FMISO PET could provide important information for treatment decisions or surgical strategies of any type of brain tumor.

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 18 h, 37 patients who fasted more than 18 h, and 64 patients who fasted more than 18 h 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 15 min after UFH administration (P < 0.01). Blood glucose and insulin levels remained unchanged (P = NS). FDG physiological uptake was observed in 69% of the patients who fasted less than 18 h, 38% of the patients fasted more than 18 h, and 22% of the UFH-CD group (P < 0.01 for trend). SUVmax decreased in the UFH-CD group compared with the patients who fasted less than 18 h (P < 0.01) and the patients who fasted more than 18 h (P = 0.029)., Conclusion: UFH administration and fasting more than 18 h could effectively suppress FDG physiological uptake in the heart and can be a useful method of detecting inflammatory CDs and tumors., (© The Foundation Acta Radiologica 2015.)

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 (CS) is a cause of conduction system disease (CSD). (18)F-Fluorodeoxyglucose-positron emission tomography (FDG PET) and cardiac magnetic resonance (CMR) are used for detection of CS. The relative diagnostic value of these has not been well studied. The aim was to compare these imaging modalities in this population., Methods: We recruited steroid-naive patients with newly diagnosed CSD due to CS. All CS patients underwent both imaging studies within 12 weeks of each other. Patients were classified into two groups: group A with chronic mild CSD (right bundle branch block and/or axis deviation), and group B with new-onset atrioventricular block (AVB, Mobitz type II or third-degree AVB)., Results: Thirty patients were included. Positive findings on both imaging studies were seen in 72 % of patients (13/18) in group A and in 58 % of patients (7/12) in group B. The remainder (28 %) of the patients in group A were positive only on CMR. Of the patients in group B, 8 % were positive only on CMR and 33 % were positive only on FDG PET. Patients in group A were more likely to be positive only on CMR, and patients in group B were more likely to be positive only on FDG PET (p = 0.02). Patients in group B positive only on FDG PET underwent CMR earlier relative to their symptomatology than patients positive only on CMR (median 7.0, IQR 1.5 - 34.3, vs. 72.0, IQR 25.0 - 79.5 days; p = 0.03)., Conclusion: The number of positive FDG PET and CMR studies was different in patients with CSD depending on their clinical presentation. This study demonstrated that CMR can adequately detect cardiac involvement associated with chronic mild CSD. In patients presenting with new-onset AVB and a negative CMR study, FDG PET may be useful for detecting cardiac involvement due to CS.

Background: To develop and validate a method for quantifying myocardial blood flow (MBF) using dynamic perfusion magnetic resonance imaging (MBFMRI ) at 3.0 Tesla (T) and compare the findings with those of (15) O-water positron emission tomography (MBFPET )., Methods: Twenty healthy male volunteers underwent magnetic resonance imaging (MRI) and (15) O-water positron emission tomography (PET) at rest and during adenosine triphosphate infusion. The single-tissue compartment model was used to estimate the inflow rate constant (K1). We estimated the extraction fraction of Gd-DTPA using K1 and MBF values obtained from (15) O-water PET for the first 10 subjects. For validation, we calculated MBFMRI values for the remaining 10 subjects and compared them with the MBFPET values. In addition, we compared MBFMRI values of 10 patients with coronary artery disease with those of healthy subjects., Results: The mean resting and stress MBFMRI values were 0.76 ± 0.10 and 3.04 ± 0.82 mL/min/g, respectively, and showed excellent correlation with the mean MBFPET values (r = 0.96, P < 0.01). The mean stress MBFMRI value was significantly lower for the patients (1.92 ± 0.37) than for the healthy subjects (P < 0.001)., Conclusion: The use of dynamic perfusion MRI at 3T is useful for estimating MBF and can be applied for patients with coronary artery disease., (© 2014 Wiley Periodicals, Inc.)

Unlabelled: The red nucleus (RN) is a pair of small gray matter structures located in the midbrain and involved in muscle movement and cognitive functions. This retrospective study aimed to investigate the metabolism of human RN and its correlation to other brain regions., Methods: We developed a high-resolution semiconductor PET system to image small brain structures. Twenty patients without neurologic disorders underwent whole-brain scanning after injection of 400 MBq of (18)F-FDG. The individual brain (18)F-FDG PET images were spatially normalized to generate a surface projection map using a 3-dimensional stereotactic surface projection technique. The correlation between the RN and each voxel on the cerebral and cerebellar cortices was estimated with Pearson product-moment correlation analysis., Results: Both right and left RNs were visualized with higher uptake than that in the background midbrain. The maximum standardized uptake values of RN were 7.64 ± 1.92; these were higher than the values for the dentate nucleus but lower than those for the caudate nucleus, putamen, and thalamus. The voxel-by-voxel analysis demonstrated that the right RN was correlated more with ipsilateral association cortices than contralateral cortices, whereas the left RN was equally correlated with ipsilateral and contralateral cortices. The left RN showed a stronger correlation with the motor cortices and cerebellum than the right RN did., Conclusion: Although nonspecific background activity around RNs might have influenced the correlation patterns, these metabolic relationships suggested that RN cooperates with association cortices and limbic areas to conduct higher brain functions., (© 2015 by the Society of Nuclear Medicine and Molecular Imaging, Inc.)

Purpose: (11)C-methionine (MET) PET is an established diagnostic tool for glioma. Studies have suggested that MET uptake intensity in the tumor is a useful index for predicting patient outcome. Because MET uptake is known to reflect tumor expansion more accurately than MRI, we aimed to elucidate the association between volume-based tumor measurements and patient prognosis., Methods: The study population comprised 52 patients with newly diagnosed glioma who underwent PET scanning 20 min after injection of 370 MBq MET. The tumor was contoured using a threshold of 1.3 times the activity of the contralateral normal cortex. Metabolic tumor volume (MTV) was defined as the total volume within the boundary. Total lesion methionine uptake (TLMU) was defined as MTV times the mean standardized uptake value (SUVmean) within the boundary. The tumor-to-normal ratio (TNR), calculated as the maximum standardized uptake value (SUVmax) divided by the contralateral reference value, was also recorded. All patients underwent surgery (biopsy or tumor resection) targeting the tissue with high MET uptake. The Kaplan-Meier method was used to estimate the predictive value of each measurement., Results: Grade II tumor was diagnosed in 12 patients (3 diffuse astrocytoma, 2 oligodendroglioma, and 7 oligoastrocytoma), grade III in 18 patients (8 anaplastic astrocytoma, 6 anaplastic oligodendroglioma, and 4 anaplastic oligoastrocytoma), and grade IV in 22 patients (all glioblastoma). TNR, MTV and TLMU were 3.1 ± 1.2, 51.6 ± 49.9 ml and 147.7 ± 153.3 ml, respectively. None of the three measurements was able to categorize the glioma patients in terms of survival when all patients were analyzed. However, when only patients with astrocytic tumor (N = 33) were analyzed (i.e., when those with oligodendroglial components were excluded), MTV and TLMU successfully predicted patient outcome with higher values associated with a poorer prognosis (P < 0.05 and P < 0.01, respectively), while the predictive ability of TNR did not reach statistical significance (P = NS)., Conclusion: MTV and TLMU may be useful for predicting outcome in patients with astrocytic tumor.

Purpose: The predictive value of FDG PET at thyroid remnant ablation was evaluated in comparison to radioiodine uptake in high-risk patients with differentiated thyroid cancer., Patients and Methods: One hundred forty-one patients who underwent radioiodine therapy (RIT) after total thyroidectomy and received at least 1 further RIT due to suspected metastases were retrospectively analyzed. Patients had not received RIT previously. FDG PET was performed before thyroid remnant ablation. Thyroid-stimulating hormone-stimulated serum thyroglobulin (Tg) was measured for biochemical response assessment (change of Tg between the first and second RIT, ΔTg)., Results: Biochemical response could be evaluated in 80 patients; survival data could be obtained for 88 patients (maximum, 124 months). Biochemical response was significantly better in patients with radioiodine-positive metastases compared with patients with radioiodine-negative metastases (median ΔTg I+, 55.8% vs I-, 112.6%; P < 0.01). Regarding survival, deaths occurred later in patients with radioiodine-positive metastases compared with radioiodine-negative patients; however, there was no significant difference regarding overall survival (I+, 61.3% vs I-, 58.2%; P > 0.05). Patients with FDG-positive metastases at thyroid remnant ablation showed a poorer biochemical response compared with patients with FDG-negative metastases (median ΔTg FDG+, 77.5% vs FDG-, 53.2%; P < 0.05), and these groups also differed significantly regarding survival (overall survival FDG+, 48.5% vs FDG-, 100%, P < 0.05)., Conclusions: At thyroid remnant ablation, FDG PET is more predictive for long-term survival, whereas radioiodine uptake is more important for short-term response. FDG PET performed at thyroid remnant ablation might represent a useful tool for management of high-risk patients with differentiated thyroid cancer.