Myocardial somatostatin PET uptake is observed not only in most patients with acute myocarditis (AM) but also in some oncology patients referred for routine somatostatin PET. This raises concerns about the specificity of somatostatin PET for detecting myocarditis. The current study aims to identify factors associated with the detection of myocardial uptake on somatostatin PET scans recorded for oncology indications and differential PET criteria that characterize myocardial uptake in AM patients. Methods: We analyzed factors associated with the detection of myocardial [⁶⁸Ga]Ga-DOTATOC uptake in 508 [⁶⁸Ga]Ga-DOTATOC PET scans from 178 patients, performed for confirmed or suspected oncologic disease (Onc-PET) and PET criteria that could differentiate myocardial [⁶⁸Ga]Ga-DOTATOC uptake in 31 patients with MRI-ascertained AM (AM-PET) from that in the Onc-PET group. Results: Significant myocardial uptake was detected in 137 (26.9%) Onc-PET scans and was independently associated with somatostatin analog treatment (exp(β), 0.805; 95% CI, 0.728–0.890; P < 0.001) and age (exp(β), 1.005; 95% CI, 1.001–1.009; P = 0.012). A comparable model was selected for predicting the myocardial-to-blood SUV_max ratio using somatostatin analog treatment (P < 0.001) and history of coronary artery disease (P = 0.022). Myocardial uptake was detected in 12.9% (25/193) of Onc-PET scans from patients treated with somatostatin analogs but in 43.4% (59/136) of untreated patients over the median age of 64 y. Myocardial uptake was apparent in all 31 AM-PET scans, with volume and intensity of uptake dramatically higher than in the 137 Onc-PET scans showing myocardial uptake. A myocardial-to-blood SUV_max ratio threshold of 2.20 provided a sensitivity of 87% (27/31) and a specificity of 88% (44/50) for differentiating myocardial uptake between the AM-PET group and an Onc-PET group restricted to patients with clinical characteristics comparable to those of patients in the AM-PET group (≤64 y of age, no coronary artery disease history, and no somatostatin agonists). A myocardial uptake volume threshold of 18 cm³ provided comparable diagnostic accuracy (sensitivity, 84% [26/31]; specificity, 94% [47/50]). Conclusion: Myocardial uptake was detected in 26.9% of somatostatin PET scans recorded for oncology indications. This rate was decreased by somatostatin analog treatments and increased in older individuals. However, somatostatin PET scans, analyzed with the quantitative criterion of uptake intensity or volume, are able to identify AM and to differentiate it from myocardial uptake of other origins.

心肌生长抑素 PET 摄取不仅在大多数急性心肌炎 (AM) 患者中观察到，而且在一些转诊常规生长抑素 PET 治疗的肿瘤患者中也观察到。这引发了人们对生长抑素 PET 检测心肌炎的特异性的担忧。目前的研究旨在确定与肿瘤学适应症记录的生长抑素 PET 扫描中检测心肌摄取相关的因素以及表征 AM 患者心肌摄取的差异 PET 标准。方法：我们分析了 178 名患者的 508 次 [ ⁶⁸ Ga]Ga-DOTATOC PET 扫描中与心肌 [ ⁶⁸ Ga]Ga-DOTATOC 摄取检测相关的因素，这些扫描针对确诊或疑似肿瘤疾病 (Onc-PET) 进行，并且 PET 标准可以区分 31 名 MRI 确定的 AM (AM-PET) 患者和 Onc-PET 组患者的心肌 [ ⁶⁸ Ga]Ga-DOTATOC 摄取情况。结果：在 137 例 (26.9%) Onc-PET 扫描中检测到显着的心肌摄取，并且与生长抑素类似物治疗 (exp(β), 0.805; 95% CI, 0.728–0.890; P < 0.001) 和年龄 (exp( β），1.005；95% CI，1.001-1.009； P = 0.012）。选择一个可比较的模型来预测使用生长抑素类似物治疗的心肌与血液 SUV_最大比率 ( P < 0.001) 和冠状动脉疾病史 ( P = 0.022)。在接受生长抑素类似物治疗的患者中，Onc-PET 扫描中检测到心肌摄取的比例为 12.9% (25/193)，但在中位年龄超过 64 岁的未接受治疗的患者中，这一比例为 43.4% (59/136)。 在所有 31 次 AM-PET 扫描中，心肌摄取都很明显，摄取的体积和强度明显高于显示心肌摄取的 137 次 Onc-PET 扫描。心肌与血液 SUV_最大比值阈值为 2.20，区分 AM-PET 组和 Onc-PET 组之间的心肌摄取的敏感性为 87% (27/31)，特异性为 88% (44/50)仅限于临床特征与 AM-PET 组患者相当的患者（年龄≤64 岁，无冠状动脉疾病史，且未使用生长抑素激动剂）。 18 cm ³的心肌摄取体积阈值提供了相当的诊断准确性（敏感性，84% [26/31]；特异性，94% [47/50]）。结论：在记录肿瘤学指征的生长抑素 PET 扫描中，26.9% 检测到心肌摄取。生长抑素类似物治疗可降低该比率，而老年人中该比率会增加。然而，生长抑素 PET 扫描，通过摄取强度或体积的定量标准进行分析，能够识别 AM 并将其与其他来源的心肌摄取区分开来。