Celiac ganglia: can they be misinterpreted on multimodal 68Ga-PSMA-11 PET/MR?

The objective of this study was to investigate the morphologic features and Ga-prostate-specific membrane antigen (PSMA)-11 avidity of celiac ganglia (CG) on multimodal PET/MRI.

Ga-PSMA-11 whole-body PET/MR examinations in 120 patients, referred for staging or follow-up of prostate cancer, were retrospectively reviewed to investigate the radiotracer uptake [maximum standardized uptake value (SUVmax)] and morphologic features (size, shape, location) of CG. Nodular, oval and longitudinal nodular, thick or with oval parts shapes of CG were regarded as mistakable with lymph nodes, whereas linear and longitudinal shapes were considered as not mistakable.

On MR scans, CG were visible in 98% (117/120) on both sides and in two patients only on the left side. Mistakable CG shape was detected in 69% (83/120) of patients on both or at least one side. The left CG were thicker (4±1.4 mm; range: 1.5-7.5 mm) than the right ones (3±1.3 mm; range: 0.5-7 mm). Mean SUVmax was 2.51±1.17 (range: 0.02-5.48) in the left CG and 2.23±1.22 (range: 0.02-5.91) in the right CG. Increased Ga-PSMA-11 uptake, SUVmax at least 2, was detected in 75% (90/120), and both - erroneous shape and elevated Ga-PSMA-ligand uptake - was observed in 55% (66/120) of all patients on both sides or at least one side.

Frequently observed, the nodular, oval and longitudinal (nodular, thick or with oval parts) shape of CG, especially of the thicker left CG, on MR scans may cause mistaking them for lymph nodes, even abnormal or metastatic. On whole-body PET/MRI, evident and sometimes high Ga-PSMA-11 uptake in CG increases the risk of a misinterpretation of them as metastases.