Jagtap Rajlaxmi, Asopa Ramesh V, Basu Sandip
Radiation Medicine Centre, Bhabha Atomic Research Centre, Tata Memorial Hospital Annexe, Parel, Maharashtra, India.
Homi Bhabha National Institute, Mumbai, Maharashtra, India.
World J Nucl Med. 2019 Jan-Mar;18(1):30-35. doi: 10.4103/wjnm.WJNM_16_18.
The aim of this prospective study was to explore the feasibility of F-fluoromisonidazole (F-FMISO) cardiac positron emission tomography/computed tomography (PET/CT) in the detection of cardiac hypoxia in patients of ischemic heart disease (IHD) and to compare the uptake pattern with that of Tc-MIBI and F-fluorodeoxyglucose (F-FDG). Twenty-six patients suffering from IHD were evaluated in this study. The patients initially underwent Tc-MIBI rest/stress myocardial perfusion imaging and F-FDG cardiac PET/CT as a part of their routine cardiac imaging. Patients with hibernating myocardium on these scans further underwent F-FMISO Cardiac PET/CT. Controls were also considered in the form of patients with scarred and normal myocardium. On visual assessment, increased F-FMISO uptake was noted in the hibernating myocardium compared to scarred or normal myocardium. On semiquantification analysis, there was overlap in the uptake values with a range of maximum standardized uptake value (SUV) in hibernating, scarred, and normal myocardium being 0.8-2.2 g/dl, 0.7-1.8 g/dl, and 0.7-1.6 g/dl, respectively. On individual patient-specific comparison in subjects harboring both hibernating and scarred myocardium, it was observed that SUV of F-FMISO in hibernating myocardium was highest, followed by scarred myocardium and normal myocardium, respectively. The ratio of F-FMISO SUV of hibernating to the normal myocardium in these subjects was always more than 1, and never less than the ratio of SUV of scarred to normal myocardium. Thus, in this mixed population study, it was observed that on an individual patient basis, hypoxic myocardium consistently showed higher F-FMISO uptake than surrounding scarred and normal myocardium. The ratio of F-FMISO SUV of hibernating to normal myocardium was higher than the ratio of scarred to the normal myocardium in all patients. On overall basis, however, there was considerable overlap in the SUV values among hibernating, scarred, and normal myocardium resulting in difficulty in differentiation of these entities with FMISO cardiac PET. F-FDG cardiac PET/CT remains the standard and superior method to determine hibernating myocardium in patients of IHD due to its superior contrast. The limitation of FMISO is poor signal to noise ratio because of high background uptake from the blood pool. Cardiac PET/CT with superior hypoxia tracers needs to be further examined for imaging cardiac hypoxia.
这项前瞻性研究的目的是探讨F-氟米索硝唑（F-FMISO）心肌正电子发射断层扫描/计算机断层扫描（PET/CT）在检测缺血性心脏病（IHD）患者心肌缺氧方面的可行性，并将其摄取模式与锝-甲氧基异丁基异腈（Tc-MIBI）和F-氟脱氧葡萄糖（F-FDG）的摄取模式进行比较。本研究评估了26例IHD患者。这些患者最初接受了Tc-MIBI静息/负荷心肌灌注成像和F-FDG心肌PET/CT检查，作为其常规心脏成像的一部分。在这些扫描中显示有冬眠心肌的患者进一步接受了F-FMISO心肌PET/CT检查。还纳入了有瘢痕心肌和正常心肌的患者作为对照。在视觉评估中，与瘢痕心肌或正常心肌相比，冬眠心肌中F-FMISO摄取增加。在半定量分析中，摄取值存在重叠，冬眠心肌、瘢痕心肌和正常心肌的最大标准化摄取值（SUV）范围分别为0.8-2.2g/dl、0.7-1.8g/dl和0.7-1.6g/dl。在同时存在冬眠心肌和瘢痕心肌的个体患者特异性比较中，观察到冬眠心肌中F-FMISO的SUV最高，其次分别是瘢痕心肌和正常心肌。在这些受试者中，冬眠心肌与正常心肌的F-FMISO SUV比值始终大于1，且从不低于瘢痕心肌与正常心肌的SUV比值。因此，在这项混合人群研究中，观察到在个体患者层面，缺氧心肌始终显示出比周围瘢痕心肌和正常心肌更高的F-FMISO摄取。在所有患者中，冬眠心肌与正常心肌的F-FMISO SUV比值高于瘢痕心肌与正常心肌的比值。然而，总体而言，冬眠心肌、瘢痕心肌和正常心肌的SUV值存在相当大的重叠，导致用FMISO心肌PET区分这些心肌组织存在困难。由于其对比度更高，F-FDG心肌PET/CT仍然是确定IHD患者冬眠心肌的标准且更优的方法。FMISO的局限性在于血池本底摄取高，导致信噪比差。需要进一步研究使用更优的缺氧示踪剂的心肌PET/CT用于心肌缺氧成像。
