Ziel/Aim:
To compare the detection rate of Tc-99 m-PSMA I&S SPECT/CT and Ga-68-PSMA PET/CT for pelvic lymph node metastases in patients with biochemically recurrent prostate cancer planned for radioguided surgery.
Methodik/Methods:
We included 31 patients (age 63 ± 7 years, range 52 – 76) planned for radioguided surgery with pelvic lymph node metastases in our retrospective study. All patients underwent planar whole-body Tc-99 m-PSMA-I&S scan with additional SPECT/CT of the pelvic region 17 ± 3h p.i. An average dose of 725 ± 72 MBq Tc-99 m-PSMA I&S was applied. All patients underwent a prior Ga-68-PSMA PET/CT, which identified 55 PET-positive lymph nodes and served as the standard of reference. Lymph nodes in SPECT/CT were categorized as positive when maximum uptake exceeded blood pool activity, SPECT-positive lesions were compared with the reference PET.
Ergebnisse/Results:
80% (44/55) of the PET-positive lesions were detected in Tc-99 m-PSMA-I&S SPECT/CT. All false-negative lesions on SPECT/CT (11/55) were attributed to patients with very low lesion SUVmax and SUVmean values in PET/CT or intensified antiandrogen therapy in-between resulting in PSA decrease and size reduction of lymph node in CT. All PET-positive lymph nodes were found metastatic in histology.
Schlussfolgerungen/Conclusions:
Tc-99 m-PSMA I&S SPECT/CT showed a comparable detection rate to PSMA-PET/CT for pelvic lymph node metastases in patients with biochemically recurrent prostate cancer planned for radioguided surgery.
