Clinical impact of “true whole-body” Ga-68-PSMA I&T PET/CT: lesion frequency and added benefit in lower extremities

Ziel/Aim:

To determine the additional clinical impact of lower extremity scan in Ga-68-PSMA I&T PET/CT on prostate cancer treatment.

Methodik/Methods:

We performed a retrospective analysis in 100 patients (age 67 years; range 46 – 81) with a documented diagnosis of prostate cancer between 01/2015 and 01/2017. The Ga-68- PSMA-PET/CT was indicated in 27 patients for primary staging and in 73 patients for recurrent or metastatic prostate cancer. Mean PSA prior Ga-68-PSMA I&T PET/CT was 3.1 ng/ml (range 0.01 – 1510 ng/ml). Mean Gleason score was 7. All patients underwent whole-body Ga-68-PSMA I&T PET/CT with an average dose of 157 ± 29 MBq (range 80 – 291 MBq) and an uptake period of 78 ± 28 min. (range 29 – 152 min.). PET acquisition time was 90 seconds per bed position for the head, thorax and abdomen, and 60 seconds for the lower extremity, resulting in a scan time of about 40 min. Findings were reported according to miTNM guidelines (1).

Ergebnisse/Results:

In 79/100 patients (79%) at least one Ga-68-PSMA I&T positive lesion was detected. Only 3/100 patients (3%) harbored PSMA positive findings in the lower extremities. None of the patients had critical CT findings of the lower extremities. None of the detected lesions in lower extremities altered clinical patient management. All detected lesions in lower extremities were additional bone metastases in patients with disseminated osseous metastases or diffuse marrow infiltration.

Schlussfolgerungen/Conclusions:

Additional lesions detected in “true” whole-body Ga-68-PSMA I&T PET/CT in lower extremities are rare and did not alter patient management. Thus, in our opinion, a scan of the lower extremities can be omitted. Saved scan time could be invested in additional time for critical regions or enable higher patient throughput.

Literatur/References:

[1] Eiber M et al. Prostate Cancer Molecular Imaging Standardized Evaluation (PROMISE): Proposed miTNM Classification for the Interpretation of PSMA-Ligand PET/CT. Journal of Nuclear Medicine. 2017;59(3):469 – 478.