Investigating image criteria indicative of a post-diuretic scan in patients undergoing a Gallium-68 prostate-specific membrane antigen (PSMA) exam

Abstract

Purpose: When used in the management of prostate carcinoma, image interpretation of Gallium-68 (Ga-68) prostate-specific membrane antigen (PSMA) Positron Emission Tomography/Computed Tomography (PET/CT) examinations may be impaired by urinary activity. Past research has provided evidence of several protocols incorporating the use of diuretics into these examinations. However, literature has demonstrated poor consistency on the use of diuretics during Ga-68 PSMA imaging. This study is being carried out with the purpose of using the Delphi process to achieve expert consensus on the optimum use of diuretics during Ga-68 PSMA scans, within the local scenario. Objectives: The objectives of the study involved providing recommendations on how to improve and standardise local guidelines with regards to the use of diuretics during Ga-68 PSMA PET/CT examinations through the use of an international questionnaire and a local Delphi study. The international questionnaire investigated trends on the use of diuretics during Ga-68 PSMA examinations, image criteria indicative of diuretic administration and participant demographics. The local Delphi study aimed to achieve expert consensus on the use of diuretics and the image criteria indicative of diuretic administration during these scans. Methodology: The study was divided into two distinct phases which consisted of an international questionnaire in phase 1, and a Delphi study in phase 2. Both phases used a prospective, non-experimental, and cross-sectional design with a concurrent embedded mixed-methods approach. Results: The results showed that local experts agreed on having a diuretic protocol for Ga-68 PSMA scans. Experts were also in favour of nuclear medicine physicians or experienced radiographers selectively choosing which cases required diuretic administration, only after routine whole-body imaging had been performed. Experts also identified foci of activity in the abdomen or pelvis, which could not be confidently identified as urinary activity or metastatic lymph nodes, as the only image criteria seen on routine imaging which would justify the use of diuretics during Ga-68 PSMA examinations. Conclusions: This study provided a list of suggestions that may be applied to a departmental protocol for the optimum use of diuretics during Ga-68 PSMA examinations