Tran Kathryn, Khan Sairah, Taghizadehasl Mina, Palazzo Fausto, Frilling Andrea, Todd Jeannie F, Al-Nahhas Adil
Department of Nuclear Medicine, Hammersmith Hospital, Imperial College NHS Trust, Du Cane Road, London W12 0HS, United Kingdom.
Hell J Nucl Med. 2015 Jan-Apr;18(1):19-24. doi: 10.1967/s002449910163. Epub 2015 Feb 13.
Medullary carcinoma of the thyroid (MTC) is a rare neuroendocrine tumour (NET) that expresses somatostatin receptors on the cell membrane and secretes calcitonin. Surgery is the primary curative modality but is achieved only when the diagnosis is timely so there is a high rate of persistent and recurrent disease indicated by a rise in the serum calcitonin levels. Successful management of recurrent disease requires accurate localisation with cross sectional and functional imaging. The introduction of gallium-68-Dotatate ((68)Ga-Dotatate) peptides positron emission tomography/computerized tomography (PET/CT) has significantly improved the detection of NET and has been reported as a valuable adjunct in MTC localisation. We retrospectively reviewed our cases of MTC to correlate the detectability of (68)Ga-Dotatate in relation to calcitonin levels and assess suitability of inoperable patients for peptide receptor radionuclide therapy (PRRT).
Seven patients (age range 31-66 years, M:F 3:4) with raised calcitonin (mean=7,143pg/mL) were referred for (68)Ga-Dotatate PET/CT scan for localisation of persisting recurrent MTC. Six patients were known to have MTC treated with thyroidectomy and one patient was presenting for the first time. All patients had multiple imaging including ultrasound (US), CT, magnetic resonance imaging (MRI), fluorine-18-fluorodeoxyglucose ((18)F-FDG) PET/CT and iodine-123-metaiodobenzylguanidine ((123)I-MIBG). Positive findings were defined as areas of increased uptake other than the organs of normal distribution and were correlated with results of biopsies, other imaging, long term monitoring of calcitonin and clinical follow up.
In 6/7 patients with very high serum calcitonin (range= 672-37,180, mean=8,320pg/mL) (68)Ga-Dotatate PET/CT confirmed the presence of active disease seen on other modalities or detected hitherto unsuspected lesions. In at least 3 cases, (68)Ga-Dotatate PET/CT showed many more lesions compared to other imaging combined. In 1/7 patient (68)Ga-Dotatate PET/CT was negative in line with a relatively low calcitonin level (80pg/mL) and negative disease on fine needle aspiration.
(68)Ga-Dotatate PET/CT is an effective tool for localising metastatic spread of MTC. It appears to be most effective in the presence of higher levels of serum calcitonin, probably in excess of 500pg/mL. The results of our small cohort had an impact on staging and management with the introduction of peptide receptor radionuclide therapy for inoperable disease.
甲状腺髓样癌（MTC）是一种罕见的神经内分泌肿瘤（NET），其细胞膜上表达生长抑素受体并分泌降钙素。手术是主要的治愈方式，但只有在诊断及时时才能实现，因此血清降钙素水平升高表明疾病持续和复发率很高。复发性疾病的成功管理需要通过横断面和功能成像进行准确的定位。镓-68-奥曲肽（（68）Ga-Dotatate）肽正电子发射断层扫描/计算机断层扫描（PET/CT）的引入显著提高了NET的检测率，并已被报道为MTC定位中有价值的辅助手段。我们回顾性分析了我们的MTC病例，以关联（68）Ga-Dotatate的可检测性与降钙素水平，并评估不可手术患者接受肽受体放射性核素治疗（PRRT）的适用性。
7例降钙素升高（平均=7,143pg/mL）的患者（年龄范围31 - 66岁，男:女为3:4）因持续性复发性MTC的定位被转诊进行（68）Ga-Dotatate PET/CT扫描。6例患者已知患有MTC并接受了甲状腺切除术，1例患者为首次就诊。所有患者均进行了多种影像学检查，包括超声（US）、CT、磁共振成像（MRI）、氟-18-氟脱氧葡萄糖（（18）F-FDG）PET/CT和碘-123-间碘苄胍（（123）I-MIBG）。阳性结果定义为正常分布器官以外摄取增加的区域，并与活检结果、其他影像学检查、降钙素的长期监测和临床随访相关。
在7例血清降钙素水平非常高（范围=672 - 37,180，平均=8,320pg/mL）的患者中，6例患者的（68）Ga-Dotatate PET/CT证实了其他检查方式所见的活动性疾病的存在或检测到了此前未怀疑的病变。至少3例患者中，与其他影像学检查联合相比，（68）Ga-Dotatate PET/CT显示出更多的病变。1例患者（68）Ga-Dotatate PET/CT结果为阴性，其降钙素水平相对较低（80pg/mL）且细针穿刺结果为阴性。
（68）Ga-Dotatate PET/CT是定位MTC转移扩散的有效工具。在血清降钙素水平较高（可能超过500pg/mL）时，它似乎最有效。我们小队列的结果对分期和管理产生了影响，为不可手术的疾病引入了肽受体放射性核素治疗。
