Limited Value of Ga-68-DOTATOC-PET-CT in Routine Screening of Patients with Multiple Endocrine Neoplasia Type 1

Routine screening is recommended for patients with multiple endocrine neoplasia type 1 (MEN1) to enable early detection and treatment of associated neuroendocrine neoplasms (NEN). Gallium⁶⁸-DOTATOC-Positron emission tomography combined with computed tomography (Ga-68-DOTATOC-PET-CT) is a very sensitive and specific imaging technique for the detection of sporadic neuroendocrine tumors. The present study evaluated the value of Ga-68-DOTATOC-PET-CT in routine screening of patients with MEN1.

Between January 2014 and March 2016, all MEN1 patients underwent Ga-68-DOTATOC-PET-CT in addition to conventional imaging (computed tomography of the thorax, magnetic resonance imaging of the abdomen and pituitary, endoscopic ultrasonography). The diagnostic yield of conventional imaging and Ga-68-DOTATOC-PET-CT was prospectively documented and compared, and treatment changes caused by the addition of Ga-68-DOTATOC-PET-CT were recorded.

Conventional imaging detected 145 NENs, mainly pancreaticoduodenal NENs (n = 117, 81%), in 31 of 33 MEN1 patients. Ga-68-DOTATOC-PET-CT detected 55 NENs in 23 of the 33 patients (p = 0.0001). Ninety (62%) NENs detected by conventional imaging were missed by DOTATOC-PET-CT. The majority of missed lesions were pNEN (n = 68; 74%). The sensitivity of Ga-68-DOTATOC-PET-CT for NENs <5, 5-9, 10-19 and ≥20 mm was 0, 29, 81 and 100%, respectively. However, Ga-68-DOTATOC-PET-CT detected more liver and lymph node metastases in patients with known metastatic disease, which did not lead to a change of patients' management. In one patient (3%), Ga-68-DOTATOC-PET-CT was the only imaging modality that detected a small intestine NEN and led to potentially curative surgery.

Ga-68-DOTATOC-PET-CT cannot be recommended for routine screening of MEN1 patients. It might provide important additional information in patients with suspected or known metastatic disease.