Gallium-68 DOTATATE PET
A highly sensitive PET imaging technique using gallium-68 labelled DOTATATE (a somatostatin analogue) to detect somatostatin receptor-positive tumours. Ga-68 DOTATATE PET has largely replaced older somatostatin receptor scintigraphy and is used to select patients for lutetium Lu-177 dotatate therapy.
Technical Context
Ga-68 DOTATATE (NETSPOT, Detectnet): Ga-68 chelated to DOTA-Tyr3-octreotate, binding SSTR2 with high affinity. PET/CT protocol: IV injection of approximately 2 MBq/kg → 60-minute uptake period → whole-body PET/CT acquisition. Image interpretation: physiological uptake in pituitary, adrenals, spleen, liver, kidneys, and head of pancreas (SSTR-expressing normal tissues); pathological uptake in tumour lesions quantified by SUVmax. Clinical applications: initial NET staging, restaging after treatment, detection of unknown primary, and selection for Lu-177 PRRT (patients with adequate tumour uptake — typically SUVmax greater than hepatic background — are candidates for PRRT). The Krenning score (visual comparison of tumour uptake to reference organs) was developed for OctreoScan but adapted for DOTATATE PET. Ga-68 DOTATATE PET has changed NET management by detecting lesions missed by conventional imaging in approximately 30-40% of patients, altering treatment decisions in approximately 30% of cases.