Nuclear Medicine Service, Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
Clin Nucl Med. 2012 Aug;37(8):759-62. doi: 10.1097/RLU.0b013e31825ae8e7.
Merkel cell carcinoma (MCC) is a rare cutaneous neuroendocrine neoplasm with propensity for nodal metastases. A few reports have presented imaging results with FDG PET/CT or 111In-pentetreotide (OctreoScan, OCT) indicating a higher sensitivity for FDG than OCT, but no reports have directly compared FDG to OCT in the same patients. We reviewed our experience in a limited number of patients who underwent both procedures.
Patients with MCC who had FDG PET and OCT between 2000 and 2010 in our center were retrospectively reviewed. Patients were included if they had FDG PET/CT and OCT scan within a 2-month interval. For each eligible patient, we compared all abnormal lesions identified on either scan. The findings were verified by pathology or other imaging techniques up to a 4-month follow-up.
A total of 9 patients met the selection criteria with 10 dual scans (1 was scanned twice). Three patients had no documented sites of disease at the time of imaging. One patient had negative findings on both FDG and OCT initially, but 1 year later developed FDG-positive OCT-negative disease. Five patients had metastatic disease at the time of imaging: 2 were negative on OCT and positive on FDG; the other 3 were positive on both scans but had more lesions on FDG.
Our data on a small number of patients are in agreement with prior individual FDG or OCT reports and suggest that, overall, FDG PET/CT detects more MCC lesions and upgrades MCC stage compared with the OCT scan. Importantly, there were no lesions identified by OCT that were missed by PET. Thus, given the added resolution and sensitivity of PET, the use of OCT in MCC in the modern era is of limited value and it remains to be seen whether newer 68Ga-labeled somatostatin analogs will perform better than OCT.
默克尔细胞癌（MCC）是一种罕见的皮肤神经内分泌肿瘤，具有淋巴结转移的倾向。有一些报告介绍了 FDG PET/CT 或 111In-五肽替肽（OctreoScan，OCT）的成像结果，表明 FDG 比 OCT 的敏感性更高，但没有报告直接比较同一患者的 FDG 与 OCT。我们回顾了我们在少数接受这两种检查的患者中的经验。
我们回顾了 2000 年至 2010 年期间在我们中心接受 FDG PET 和 OCT 的 MCC 患者。如果患者在 2 个月的时间内进行了 FDG PET/CT 和 OCT 扫描，则将其纳入研究。对于每个符合条件的患者，我们比较了两种扫描中发现的所有异常病变。结果通过病理学或其他影像学技术在 4 个月的随访中得到验证。
共有 9 名患者符合选择标准，共进行了 10 次双扫描（1 名患者扫描了 2 次）。3 名患者在进行影像学检查时没有记录到疾病部位。1 名患者最初在 FDG 和 OCT 上均无阳性发现，但 1 年后出现 FDG 阳性 OCT 阴性疾病。5 名患者在进行影像学检查时患有转移性疾病：2 名患者 OCT 阴性而 FDG 阳性；另外 3 名患者两种扫描均阳性，但 FDG 上的病变更多。
我们对少数患者的数据与先前的 FDG 或 OCT 报告一致，表明总体而言，与 OCT 扫描相比，FDG PET/CT 检测到更多的 MCC 病变并升级 MCC 分期。重要的是，OCT 未发现任何 PET 漏诊的病变。因此，鉴于 PET 的分辨率和敏感性更高，在现代时代，OCT 在 MCC 中的应用价值有限，并且尚不清楚新型 68Ga 标记的生长抑素类似物是否比 OCT 表现更好。
