Prostate cancer (PCa) is currently the most common cancer in men in Finland (www.cancerregistry.fi). Although prognosis is very good in majority of men, it is noteworthy that still up to 20% of PCa cases are metastatic at the time of initial diagnosis and yearly 900 men die because of prostate cancer. Robust primary staging is, therefore, one of the most important prognostic factors, and it is crucial for treatment decision. Despite their low sensitivity to detect metastasis, bone scintigraphy (BS) and contrast enhanced whole body computed tomography (ce-wbCT) are recommended by current guidelines for primary staging in men at risk of metastasis. MIP-1404 is a small-molecule PSMA inhibitor that can be used in SPECT systems (99mTc-MIP- 1404 SPECT/CT). 99mTc-MIP-1404 SPECT/CT is performed by a single IV bolus of 99mTc-MIP-1404, which binds with high affinity to extracellular domain of PSMA molecule. As of March 2020, a total of 629 subjects have received 99mTc-MIP-1404 injection averaging 740 ±111 MBq (20 ± 3 mCi) per administration in prospective clinical trials. 99mTc MIP-1404 has been well tolerated following a single IV dose at 740 ± 111 MBq in both healthy volunteers and patients with confirmed metastatic prostate adenocarcinoma. In prospective and retrospective studies, it has shown high potential to detect prostate cancer lesions in primary staging. In fact, Goffin et al. reported a sensitivity of 50% and specificity of 87% detecting local lymph node metastasis in radically operated patients when histopathology was used as a reference. This corresponds closely to the sensitivity of PSMA-PET. PROSTAMIP is a randomized prospective single-institutional study to demonstrate superiority of 99mTc-MIP-1404 SPECT/CT compared to traditional imaging modalities (99mTc-HMDP planar BS plus ce-wbCT).