Value of 68Ga-PSMA HBED-CC PET for the Assessment of Lymph Node Metastases in Prostate Cancer Patients with Biochemical Recurrence: Comparison with Histopathology After Salvage Lymphadenectomy.
The purpose of this study was to evaluate the accuracy of Glu-NH-CO-NH-Lys-(Ahx)-[68Ga(HBED-CC)] PET compared with morphologic imaging for the assessment of lymph node metastases (LNM) in patients with recurrent prostate cancer.


METHODS
Forty-eight patients (median age, 71 y; interquartile range, 66-74 y) with biochemical recurrence (median prostate-specific antigen level, 1.31 ng/mL; interquartile range, 0.75-2.55 ng/mL) who underwent68Ga-prostate-specific membrane antigen (PSMA) HBED-CC PET/CT or PET/MR and salvage lymphadenectomy were retrospectively included. Institutional review board approval and written informed consent were obtained from all patients for the purpose of anonymized evaluation and publication of their data. Standardized predefined lymph node (LN) template fields (n = 10) were evaluated in68Ga-PSMA HBED-CC PET and morphologic imaging for the presence of LNM using a 5-point-scale. Additionally, SUVmean/maxand size of suspicious lesions were determined. Specificity of68Ga-PSMA HBED-CC PET imaging for PET-positive LNs was defined by comparison to histopathology. The diagnostic accuracy of68Ga-PSMA HBED-CC PET compared with morphologic imaging alone was assessed, and areas under the receiver-operating-characteristic curves are presented.


RESULTS
LNM were found histologically in 68 of 179 resected anatomic LN fields (38.0%). The specificity of68Ga-PSMA HBED-CC PET and morphologic imaging was 97.3% and 99.1%, respectively. However,68Ga-PSMA HBED-CC PET detected LNM in 53 of 68 histopathologically proven metastatic LN fields (77.9%) whereas morphologic imaging was positive in only 18 of 67 (26.9%).68Ga-PSMA HBED-CC PET imaging performed significantly superior to morphologic imaging for detection of LNM (difference in the areas under the receiver-operating-characteristic curves, 0.139; 95% confidence interval, 0.063-0.214; P < 0.001). In68Ga-PSMA HBED-CC PET, the mean size of PET-positive LN measured by CT or MRI was 8.3 ± 4.3 mm (range, 4-25 mm), and LNs, which were suspicious only in CT or MRI, presented with a mean size of 13.0 ± 4.9 mm (range, 8-25 mm).


CONCLUSIONS
68Ga-PSMA HBED-CC PET imaging is a promising method for early detection of LNM in patients with biochemical recurrent prostate cancer. It is more accurate than morphologic imaging and thus might represent a valuable tool for guiding salvage lymphadenectomy.
Department of Nuclear Medicine, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany isabel.rauscher@tum.de.
Isabel
I
Rauscher
Department of Urology, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany.
Tobias
T
Maurer
Department of Nuclear Medicine, University Hospital Ulm, Ulm, Germany.
Ambros J
AJ
Beer
Department of Nuclear Medicine, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany.
Frank-Philipp
FP
Graner
Institute of Medical Statistics and Epidemiology, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany.
Bernhard
B
Haller
Department of Pathology, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany; and.
Gregor
G
Weirich
Queen Elizabeth Hospital, University Hospitals Birmingham NHS Foundation Trust, Edgbaston, Birmingham, United Kingdom.
Alan
A
Doherty
Department of Urology, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany.
Jürgen E
JE
Gschwend
Department of Nuclear Medicine, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany.
Markus
M
Schwaiger
Department of Nuclear Medicine, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany.
Matthias
M
Eiber
D000328:Adult; D000368:Aged; D001706:Biopsy; D004492:Edetic Acid / Q000031:analogs & derivatives; D005709:Gallium Isotopes; D005710:Gallium Radioisotopes; D006801:Humans; D008197:Lymph Node Excision / Q000379:methods; D008198:Lymph Nodes / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis* / Q000517:prevention & control; D009842:Oligopeptides; D009942:Organometallic Compounds; D049268:Positron-Emission Tomography / Q000379:methods*; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012189:Retrospective Studies; D016879:Salvage Therapy / Q000379:methods; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
D005709:Gallium Isotopes; D005710:Gallium Radioisotopes; D009842:Oligopeptides; D009942:Organometallic Compounds; D019275:Radiopharmaceuticals; C000718244:gallium 68 PSMA-11; D004492:Edetic Acid
68Ga-PSMA HBED-CC; computed tomography; hybrid imaging; magnetic resonance imaging; positron emission tomography; prostate cancer; salvage lymphadenectomy