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Objective: To assess the benefits of coronary collateral circulation on myocardial perfusion, viability and function in patients with total occlusion of a single coronary artery using the 99m Tc-sestamibi SPECT and 18 F-fluorodeoxyglucose PET., Methods: 164 Consecutive patients were included who underwent coronary angiography results exhibited total occlusion of a single coronary artery and received 99m Tc-MIBI SPECT and 18 F-FDG PET within 90 days of angiography. Myocardial perfusion and viability in patients with collateral circulation and those without it were compared. Long-term follow-up was performed through a review of patient clinical records., Results: Collateral circulation was present in 56 patients (34%) and absent in 108 patients (66%). The total perfusion defect size in patients with collateral circulation decreased when compared to those without (30% ± 13% to 35% ± 14%, P < .05). The myocardial viability was 22% ± 12% in patients with collateral circulation, and 12% ± 9% in those without (P < .001). The left ventricular ejection fraction was higher, and the end-diastolic and end-systolic left ventricular volumes were lower in patients with collateral circulation (39% ± 11%, 138 ± 66, 89 ± 57) compared to patients without collateral circulation (31% ± 9%, 177 ± 55, 125 ± 48, all P < .001, respectively). Multi-factor logistic regression identified that concerning the variables of sex, age, viable myocardium, collateral circulation, treatment type and others, only treatment type was significantly associated with therapeutic effects (OR 3.872, 95% CI 1.915-7.830, P < .001)., Conclusion: Collateral circulation can preserve resting myocardial blood perfusion and myocardial viability, and help maintain the function of the left ventricular myocardium. The appropriate treatment strategy will have a substantial impact on the therapeutic outcome., (© 2020. American Society of Nuclear Cardiology.)

First introduced in 1976, 18 F-fluorodeoxyglucose ( 18 F-FDG) positron emission tomography (PET) has become an indispensable tool for diagnosis and prognostic evaluation of tumors, heart disease, as well as other conditions, including inflammation and infection. Because 18 F-FDG can accurately reflect the glucose metabolism level of organs and tissues, it is known as a "century molecule" and is currently the main agent for PET imaging. The degree of 18 F-FDG uptake by cells is related to both the rate of glucose metabolism and glucose transporter expression. These, in turn, are strongly influenced by hypoxia, in which cells meet their energy needs through glycolysis, and 18 F-FDG uptake increased due to hypoxia. 18 F-FDG uptake is a complex process, and hypoxia may be one of the fundamental driving forces. The correct interpretation of 18 F-FDG uptake in PET imaging can help clinics make treatment decisions more accurately and effectively. In this article, we review the application of 18 F-FDG PET in tumors, myocardium, and inflammation. We discuss the relationship between 18 F-FDG uptake and hypoxia, the possible mechanism of 18 F-FDG uptake caused by hypoxia, and the associated clinical implications.

Purpose: 18F-FDG PET myocardial metabolic imaging is used to estimate myocardial viability. However, poor image quality can affect the accurate quantification of viable myocardium. We assessed the feasibility of a rescue protocol that reinjected low-dose 18F-FDG with simultaneous 1 to 2 U of insulin injection and oral administration of 10 g of glucose to improve the image quality of 18F-FDG PET myocardial metabolic imaging., Patients and Methods: Fifty-one consecutive patients with poor quality to uninterpretable 18F-FDG PET/CT myocardial metabolic images received the rescue protocol immediately after the initial image acquisition. The postrescue image acquisition was performed 1 hour later. The rescue image quality was compared with the initial image. The qualitative visual estimation of the images was graded as follows: grade 0, homogeneous, minimal uptake; grade 1, predominantly minimal or mild uptake; grade 2, moderate uptake; and grade 3, good uptake. The myocardium-to-blood pool activity ratio (M/B) was measured to assess the image quality quantitatively., Results: The grades of 0 to 3 were observed in 24 (47%), 27 (53%), 0 (0%), and 0 (0%) patients, respectively, for the initial imaging, and in 0 (0%), 3 (5.9%), 4 (7.8%), and 44 (86.3%) patients for the rescue imaging (P < 0.001). The rescue M/B was significantly higher than the initial M/B (3.4 ± 1.4 vs 1.6 ± 0.6, respectively; P < 0.001)., Conclusions: The rescue protocol successfully and rapidly improved the quality of myocardial 18F-FDG metabolic imaging., Competing Interests: Conflicts of interest and sources of funding: none declared., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Background: This study aimed to compare the accuracy of gated-SPECT (GSPECT) and gated-PET (GPET) in the assessment of left ventricular (LV) end-diastolic volumes (EDVs), end-systolic volumes (ESVs) and LV ejection fractions (LVEFs) among patients with prior myocardial infarction (MI)., Methods: One hundred and sixty-eight consecutive patients with MI who underwent GSPECT and GPET were included. Of them, 76 patients underwent CMR in addition to the two imaging modalities. The measurements of LV volumes and LVEF were performed using Quantitative Gated SPECT (QGS), Emory Cardiac Toolbox (ECTB), and 4D-MSPECT (4DM)., Results: The correlation between GPET, GSPECT, and CMR were excellent for LV EDV (r = 0.855 to 0.914), ESV (r = 0.852 to 0.949), and LVEF (r = 0.618 to 0.820), as calculated from QGS, ECTB, and 4DM. In addition, subgroup analysis revealed that EDV, ESV, and LVEF measured by GPET were accurate in patients with different extents of total perfusion defect (TPD), viable myocardium, and perfusion/metabolic mismatch. Furthermore, multivariate regression analysis identified that mismatch score was associated with the difference in EDV (P < 0.05) measurements between GPET and CMR., Conclusions: In patients with MI, LV volumes and LVEF scores measured by both GSPECT and GPET imaging were comparable to those determined by CMR, but should not be interchangeable in individual patients.

Background: Myocardial 18 F-deoxyglucose ( 18 F-FDG) uptake has been observed to be enhanced in patients with coronary artery disease (CAD) under fasting conditions. However, whether the increased 18 F-FDG is induced by myocardial ischemia and how to discriminate ischemic from physiological 18 F-FDG uptake have rarely been investigated., Methods: Under fasting conditions, 18 F-FDG PET imaging was performed in 52 patients with suspected CAD. Two 18 F-FDG imaging sessions were conducted within two hours after a single administration of 18 F-FDG (dual-time-point imaging), and with an intervention of an exercise test after the first imaging. Abnormal 18 F-FDG uptake was determined by the classification of the 18 F-FDG distribution pattern, and the changes of the 18 F-FDG distribution between the two PET imaging sessions were analyzed. 99m Tc-sestamibi was injected at peak exercise and myocardial perfusion imaging (MPI) was conducted after 18 F-FDG imaging. Coronary angiography was considered the reference for diagnosing CAD., Results: Overall, 54.8% (17/31) of CAD patients and 36.2% (21/58) of stenotic coronaries showed exercise-induced abnormal uptake of 18 F-FDG. Based on the classification of the 18 F-FDG distribution pattern, the sensitivity and specificity of exercise 18 F-FDG imaging to diagnose CAD was 80.6% and 95.2% by patient analysis, 56.9% and 98.0% by vascular analysis, respectively. Compared with MPI, 18 F-FDG imaging had a tendency to have higher sensitivity (80.6% vs 64.5%, P = 0.06) on the patient level., Conclusion: Myocardial ischemia can induce 18 F-FDG uptake. With the classification of the 18 F-FDG distribution pattern, dual-time-point 18 F-FDG imaging under fasting conditions is efficient in diagnosing CAD.

Objective: Increased myocardial glucose metabolism occurs with the onset of myocardial ischemia and may persist even after the restoration of blood flow, termed as 'ischemic memory'. Previous studies have demonstrated that 18F-fluorodeoxyglucose (18F-FDG) is a sensitive marker of myocardial ischemia and may have potential utility in diagnosing unstable angina (UA). This study aimed to explore the value of F-FDG PET/CT in diagnosing UA., Patients and Methods: Thirty-four patients (17 male patients; mean age, 59 ± 6 years) with suspected UA were prospectively recruited. Resting myocardial F-FDG PET/CT imaging was performed 21 ± 9 h (2-46 h) after the latest onset of angina pectoris. Resting or exercise myocardial perfusion imaging (MPI) and coronary angiography were performed. 'Focal' or 'focal on diffuse' myocardial F-FDG uptake was defined as abnormal, whereas other patterns of myocardial uptake, including 'focal' uptake on the basal segments, were considered as normal. The final diagnosis of UA was based on a comprehensive analysis of ECG, MPI, and coronary angiography., Results: Of the 21 patients with a final diagnosis of UA, 18 had increased 18F-FDG uptake (sensitivity 85.7%), whereas, of the 13 patients without UA, only one had abnormal 18F-FDG uptake (specificity 92.3%). The sensitivity of resting 18F-FDG imaging was higher than that of resting MPI (85.7 vs. 52.4%, P=0.016). Moreover, six UA patients with only exercise-induced ischemia showed abnormal F-FDG uptake at rest., Conclusion: This pilot study demonstrated that resting 18F-FDG PET/CT imaging is an accurate and sensitive technique for the identification of UA.

Myocardial perfusion imaging is the mainstay of nuclear cardiovascular imaging. It has been in extensive clinical use for well over 35 years for diagnosing, risk-stratification, and long-term follow-up of patients with suspected or known coronary artery disease. A unique strength of nuclear imaging is its ability to provide a repertoire of tools for imaging metabolic and biochemical processes, receptor and transporter function, inflammation, and gene expression at molecular and cellular levels in intact organisms, under a wide variety of physiological conditions. With this approach, only selective myocardium with targeted abnormality can be visualized (hot spot imaging). This provides an opportunity for imaging complex biochemical, metabolic, and inflammatory processes of the cardiovascular system. (18)F-labeled (18)FDG, a radiolabeled glucose analogue, tracks cellular uptake and metabolism of glucose in the tissue and organs. Profound changes in regional glucose metabolism accompany several cardiovascular disease processes, which can be imaged using (18)FDG. However, caution is required while performing and interpreting these images. Because myocardial glucose uptake can vary widely under different metabolic and physiological states and this variation can overlap with the changes in myocardial glucose uptake under pathologic conditions, a strict and careful regulation of metabolic milieu is required while performing (18)FDG imaging. Cardiac (18)FDG imaging can be used for imaging myocardial ischemia, viability, and sarcoidosis. These techniques can overcome many of the limitations of current imaging techniques. In this article, we describe recent studies using (18)FDG for imaging myocardial ischemia and cardiac sarcoidosis., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Background: The prevalence of myocardial perfusion and glucose metabolic abnormalities and their significance in patients with isolated left ventricular non-compaction (ILVNC) have not been well investigated., Methods: Seventeen ILVNC patients who underwent cardiac magnetic resonance (CMR) and (99m)Tc-sestamibi SPECT/fluorine-18 deoxyglucose ((18)F-FDG) PET imaging were included. Left ventricular non-compaction, regional wall motion abnormalities, left ventricular ejection fraction (LVEF), and delayed enhancement (DE) were estimated using CMR. Myocardial perfusion and metabolism were evaluated with SPECT/PET., Results: Ninety-five (32.9%) segments were considered non-compacted. DE was present in 52 (18.0%) segments and 10 (58.8%) patients. The rate of occurrence of DE was significantly higher in compacted segments than in non-compacted segments (22.7% vs 8.4%, P = .003). Myocardial perfusion abnormalities were present in 92 (31.8%) segments, of which 66 were perfusion/metabolism match and 26 were perfusion/metabolism mismatch. The rate of occurrence of perfusion abnormality was similar between compacted and non-compacted segments (32.0% vs 31.6%, P = .948), but it was significantly higher in segments with DE than in those without DE (51.9% vs 27.4%, P = .001). None of the imaging features alone (non-compaction, DE, perfusion abnormalities, match or mismatch) showed significant correlations with LVEF (all P > .05)., Conclusion: In the current study, myocardial perfusion/metabolism mismatch and match were observed in both non-compacted and compacted myocardium in ILVNC patients. Further research is warranted to determine their pathologic and clinical significance.

Purpose: Ventricular function is a powerful predictor of survival in patients with heart failure (HF). However, studies characterizing gated F-18 FDG PET for the assessment of the cardiac function are rare. The aim of this study was to prospectively compare gated F-18 FDG PET and cardiac MRI for the assessment of ventricular volume and ejection fraction (EF) in patients with HF., Methods: Eighty-nine patients with diagnosed HF who underwent both gated F-18 FDG PET/CT and cardiac MRI within 3 days were included in the analysis. Left ventricular (LV) end-diastolic volume (EDV), end-systolic volume (ESV), and EF were obtained from gated F-18 FDG PET/CT using the Quantitative Gated SPECT (QGS) and 4D-MSPECT software., Results: LV EDV and LV ESV measured by QGS were significantly lower than those measured by cardiac MRI (both P<0.0001). In contrast, the corresponding values for LV EDV for 4D-MSPECT were comparable, and LV ESV was underestimated with borderline significance compared with cardiac MRI (P = 0.047). LV EF measured by QGS and cardiac MRI showed no significant differences, whereas the corresponding values for 4D-MSPECT were lower than for cardiac MRI (P<0.0001). The correlations of LV EDV, LV ESV, and LV EF between gated F-18 FDG PET/CT and cardiac MRI were excellent for both QGS (r = 0.92, 0.92, and 0.76, respectively) and 4D-MSPECT (r = 0.93, 0.94, and 0.75, respectively). However, Bland-Altman analysis revealed a significant systemic error, where LV EDV (-27.9±37.0 mL) and ESV (-18.6±33.8 mL) were underestimated by QGS., Conclusion: Despite the observation that gated F-18 FDG PET/CT were well correlated with cardiac MRI for assessing LV function, variation was observed between the two imaging modalities, and so these imaging techniques should not be used interchangeably.

Myocardial perfusion imaging (MPI) has been in clinical use for over 30 years, providing an effective, reliable, and relatively simple tool for diagnosis, risk stratification, and follow-up of patients with suspected or know coronary artery disease (CAD). The unique strength of nuclear imaging is its ability to provide tools for imaging biochemical and metabolic processes, and receptor and transporter functions at molecular and cellular levels in intact organisms under various physiologic conditions. Metabolic imaging using radiolabeled glucose analogues ((18)F-fluorodeoxyglucose [(18)FDG]) provides a unique ability to image myocardial ischemia directly ("hot spot" imaging) in patients with known or suspected CAD. Exercise (18)FDG imaging can potentially overcome some of the limitations of currently used stress-rest MPI. In this article, we describe recent studies using exercise (18)FDG for imaging myocardial ischemia and its potential use in routine clinical practice.

Unlabelled: We have recently demonstrated the potential of (18)F-FDG as an imaging marker of myocardial ischemia if injected at peak exercise. However, how long increased (18)F-FDG uptake can be observed after an episode of exercise-induced myocardial ischemia is not known. We performed the current study to determine whether increased regional myocardial (18)F-FDG uptake at exercise in patients with coronary artery disease (CAD) persists on rest imaging (24 h later), after an episode of exercise-induced myocardial ischemia., Methods: Twenty-four patients with suspected CAD underwent exercise (99m)Tc-sestamibi and (18)F-FDG imaging. Repeated (18)F-FDG imaging was performed 24 h after exercise imaging, after an injection of a second dose of (18)F-FDG at rest in 20 patients. Perfusion imaging with (99m)Tc-sestamibi was simultaneously performed with (18)F-FDG imaging. All patients underwent coronary angiography., Results: Eighteen patients had greater than or equal to 70% luminal narrowing of 1 or more coronary vessels. Fifteen patients (83%) showed increased regional (18)F-FDG uptake on exercise imaging, but only 11 patients (61%) had perfusion abnormalities. Of these 15 patients with increased regional (18)F-FDG uptake on exercise imaging, 8 (53%) had no discernible (18)F-FDG uptake, 5 (33%) had decreased (18)F-FDG uptake, and only 2 (13%) had persistent (18)F-FDG uptake on rest (18)F-FDG images. The summed (18)F-FDG uptake score significantly decreased, from 14.4 +/- 10.3 at exercise to 6.7 +/- 9.2 at rest (P = 0.01). Patients with persistent (18)F-FDG uptake at rest had more (18)F-FDG uptake and lower peak rate-pressure product at exercise, compared with patients with no residual (18)F-FDG uptake at rest., Conclusion: Exercise-induced regional myocardial (18)F-FDG uptake is highly specific and sensitive for exercise-induced myocardial ischemia. Regional myocardial (18)F-FDG uptake may persist 24 h after an episode of exercise-induced myocardial ischemia in some patients.

Unlabelled: The prognostic value of myocardial viability assessment on left ventricular (LV) aneurysms remains undetermined. We aimed, first, to evaluate the long-term survival benefit of assessing the viability of the aneurysmal myocardium in patients with ischemic cardiomyopathy and, second, in the revascularization subgroup, to compare the short-term effects on LV function and clinical symptoms in patients treated by revascularization alone or by revascularization plus aneurysmectomy., Methods: Seventy consecutive patients with an LV aneurysm who underwent 99mTc-sestamibi SPECT and 18F-FDG PET were followed up for a median of 6.8 y (range, 0.1-8.8 y). Only cardiac death during follow-up served as the endpoint. Patients were classified into 4 groups by aneurysmal viability and by treatment strategy (medical or surgical). Further, the effects of aneurysmectomy on LV function at 3 mo were evaluated by an analysis of revascularized patients grouped by aneurysmal viability and by aneurysmectomy., Results: Twenty-four patients were assigned to medical therapy, and 46 patients were assigned to surgery (18 revascularization alone and 28 revascularization plus aneurysmectomy). The annual cardiac mortality rate in patients with a viable aneurysm treated medically (n = 10) was significantly higher than that in patients with a viable aneurysm treated surgically (n = 23) (11.6% vs. 1.5%, chi2 = 12.87, P < 0.0001) and was also significant higher than that in patients with a nonviable aneurysm treated medically (n = 14) (chi2 = 4.13, P < 0.05) or surgically (n = 23) (chi2 = 10.46, P = 0.001). Multivariate analysis showed that the aneurysmal mismatch score (P = 0.003) and surgical therapy (P = 0.001) were independent predictors of cardiac death. Improvement of LV function and symptoms after revascularization (P < 0.05) was observed in patients with revascularization plus aneurysmectomy and in patients with a viable aneurysm and revascularization only., Conclusion: Viability in LV aneurysm in patients with ischemic cardiomyopathy was a negative independent predictor of survival. Compared with medical therapy, coronary revascularization was associated with improved long-term survival, symptoms, and LV function in patients with a viable aneurysm. These findings warrant further prospective investigations.

Coronary arteries may be involved in some patients with Takayasu arteritis. Evaluation of myocardial involvement due to coronary lesions may provide important information in the clinical management of these patients. We report Tc-99m sestamibi and F-18 FDG myocardial single photon emission computed tomography in 3 cases of such patients.

Background: Scintigraphic myocardial perfusion imaging is the most widely used noninvasive modality for the detection of coronary artery disease (CAD). A technique for direct imaging of exercise-induced myocardial ischemia is highly desirable and preferable over perfusion imaging but is presently unavailable. We evaluated the feasibility and diagnostic accuracy of direct imaging of exercise-induced myocardial ischemia with fluorine-18-2-deoxyglucose (18FDG)., Methods and Results: Twenty-six patients with known or suspected CAD and no prior myocardial infarction underwent simultaneous myocardial perfusion and ischemia imaging after the intravenous injection of Tc-99m-sestamibi (99mTc-sestamibi) and 18FDG at peak exercise. Rest perfusion imaging was carried out separately. All patients underwent coronary angiography. Exercise 18FDG myocardial images were compared with exercise-rest 99mTc-sestamibi images and coronary angiography. Of 22 patients with > or =50% narrowing of > or =1 coronary arteries, 18 had perfusion abnormalities (sensitivity 82%) whereas 20 had abnormal myocardial 18FDG uptake (sensitivity 91%, P=NS). Perfusion abnormalities were seen in myocardial segments corresponding to 25 vascular territories of a total of 51 vessels with > or =50% luminal narrowing in 22 patients (sensitivity 49%), whereas increased 18FDG uptake was seen in 34 vascular territories (sensitivity 67%, P=0.008). 18FDG images were of high quality and easy to interpret but required simultaneous perfusion images for localizing abnormal myocardial 18FDG uptake., Conclusions: Exercise-induced myocardial ischemia can be imaged directly with 18FDG. Combined exercise 18FDG-99mTc-sestamibi imaging provides a better assessment of exercise-induced myocardial ischemia compared with exercise-rest perfusion imaging. Direct ischemia imaging eliminates some of the limitations of presently used myocardial perfusion imaging. Large-scale clinical studies are warranted.