The proposed clinical trial will be a sequential Phase I/II, diagnostic imaging, controlled, open label, single site study in a broad cross-section of patients with known or suspected somatostatin receptor positive tumours. All participants will be imaged with [68]Ga-HA-DOTATATE PET/CT or PET/MRI for uptake by somatostatin receptor positive tumours. Up to seven [68]Ga-HA-DOTATATE scans may be performed per participant, as clinically indicated. A safety evaluation will be conducted on the first 10 consecutively enrolled participants (safety sub-group), consisting of vital signs, haematology and serum biochemistry profile (pre-injection and post-imaging), and an adverse event (AE) assessment (up to 24 hours) after [68]Ga-HA-DOTATATE imaging. The safety evaluation for subsequent [68]Ga-HA-DOTATATE scan visits for participants in the safety sub-group and for the remaining participants will consist of an AE assessment while in the Nuclear Medicine department. The efficacy evaluation will include [68]Ga-HA-DOTATATE scan clinical accuracy compared to standard of care CT.