Comparison of bone scintigraphy and68Ga-PSMA PET for skeletal staging in prostate cancer.
OBJECTIVE
The aim of our study was to compare the diagnostic performance of68Ga-PSMA PET and99mTc bone scintigraphy (BS) for the detection of bone metastases in prostate cancer (PC) patients.


METHODS
One hundred twenty-six patients who received planar BS and PSMA PET within three months and without change of therapy were extracted from our database. Bone lesions were categorized into benign, metastatic, or equivocal by two experienced observers. A best valuable comparator (BVC) was defined based on BS, PET, additional imaging, and follow-up data. The cohort was further divided into clinical subgroups (primary staging, biochemical recurrence, and metastatic castration-resistant prostate cancer [mCRPC]). Additionally, subgroups of patients with less than 30 days delay between the two imaging procedures and with additional single-photon emission computed tomography (SPECT) were analyzed.


RESULTS
A total of 75 of 126 patients were diagnosed with bone metastases. Sensitivities and specificities regarding overall bone involvement were 98.7-100 % and 88.2-100 % for PET, and 86.7-89.3 % and 60.8-96.1 % (p < 0.001) for BS, with ranges representing results for 'optimistic' or 'pessimistic' classification of equivocal lesions. Out of 1115 examined bone regions, 410 showed metastases. Region-based analysis revealed a sensitivity and specificity of 98.8-99.0 % and 98.9-100 % for PET, and 82.4-86.6 % and 91.6-97.9 % (p < 0.001) for BS, respectively. PSMA PET also performed better in all subgroups, except patient-based analysis in mCRPC.


CONCLUSIONS
Ga-PSMA PET outperforms planar BS for the detection of affected bone regions as well as determination of overall bone involvement in PC patients. Our results indicate that BS in patients who have received PSMA PET for staging only rarely offers additional information; however, prospective studies, including a standardized integrated x-ray computed tomography (SPECT/CT) protocol, should be performed in order to confirm the presented results.
Department of Nuclear Medicine, Klinikum rechts der Isar der TU München, Ismaninger Str. 22, 81675, Munich, Germany. thomas.pyka@tum.de.
Thomas
http://orcid.org/0000-0002-2686-2851
T
Pyka
Department of Nuclear Medicine, Klinikum rechts der Isar der TU München, Ismaninger Str. 22, 81675, Munich, Germany.|Department of Nuclear Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
Shozo
S
Okamoto
Department of Urology, Klinikum rechts der Isar der TU München, Munich, Germany.
Marielena
M
Dahlbender
Department of Urology, Klinikum rechts der Isar der TU München, Munich, Germany.
Robert
R
Tauber
Department of Urology, Klinikum rechts der Isar der TU München, Munich, Germany.
Margitta
M
Retz
Department of Urology, Klinikum rechts der Isar der TU München, Munich, Germany.
Matthias
M
Heck
Department of Nuclear Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
Nagara
N
Tamaki
Department of Nuclear Medicine, Klinikum rechts der Isar der TU München, Ismaninger Str. 22, 81675, Munich, Germany.
Markus
M
Schwaiger
Department of Urology, Klinikum rechts der Isar der TU München, Munich, Germany.
Tobias
T
Maurer
Department of Nuclear Medicine, Klinikum rechts der Isar der TU München, Ismaninger Str. 22, 81675, Munich, Germany.
Matthias
M
Eiber
D000368:Aged; D000369:Aged, 80 and over; D000954:Antigens, Surface; D001859:Bone Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000556:secondary*; D005710:Gallium Radioisotopes; D043425:Glutamate Carboxypeptidase II; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography / Q000379:methods*; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D000954:Antigens, Surface; D005710:Gallium Radioisotopes; D019275:Radiopharmaceuticals; C473848:FOLH1 protein, human; D043425:Glutamate Carboxypeptidase II
68Ga-PSMA; Bone metastasis; Bone scintigraphy; Prostate cancer