Klinikum rechts der Isar
Technische Universität München
Staging of biochemical recurrent PCa after radical prostatectomy using
68Gallium-labelled ligand of PSMA-PET/CT and PET/MRI
EMUC
Tobias Maurer1, Veronika Beck1, Ambros J. Beer2, Michael Souvatzoglou2, Konstantin Holzapfel3, Hubert Kübler1, Jürgen E. Gschwend1,
Hans-Jürgen Wester4, Bernhard Haller5, Markus Schwaiger2, Matthias Eiber2
1Department of Urology, 2Department of Nuclear Medicine, 3Department of Radiology,
4Department of Pharmaceutical Radiochemistry, 5Institute of Medical Statistics and Epidemiology
P063
Klinikum rechts der Isar der TU München, Germany
Introduction & Objective.
Staging of recurrent prostate cancer after curative intended radical prostatectomy (RPE) remains challenging especially at
low PSA values. Recently, Glu-NH-CO-NH-Lys-(Ahx)-[(68)Ga(HBED-CC)] as a novel 68Gallium-labelled ligand of the
prostate-specific membrane antigen (68Ga-HBED-PSMA) has been developed. PSMA shows a selective and marked
expression on the cell surface of prostate cancer cells. Thus, the aim of this study was to investigate the detection rate of
68Ga-HBED-PSMA PET/CT and PET/MR-imaging in patients with biochemical recurrence of prostate cancer after RPE. .
Methods.
This retrospective analysis included 332 patients with a median PSA-level of 1.7 ng/ml (range 0.2-63 ng/ml). After injection
of 122±17 MBq 68Ga-HBED-PSMA contrast-enhanced PET/CT or fully-diagnostic PET/MR including multiparametric
prostate MR was performed in 256 patients and 76 patients, respectively. Images were reviewed by one nuclear medicine
physician and one radiologist in consensus. Findings were rated as suspicious or highly suggestive for recurrent prostate
cancer.
Results.
For PET/CT and PET/MR detection rates for PSA-values ≥2 ng/ml, were 96.1% (122/127) and 95.5% (21/22), for PSAvalues 1 - 2 ng/ml 94.4% (67/71) and 81.3% (13/16), for PSA-values 0.5 - 1 ng/ml 71.4% (25/35) and 75.0% (9/12) and for
PSA-value 0.2 – 0.5 ng/ml 56.5% (13/23) and 50.0% (13/26), respectively. Especially in cases with low PSA-values the
diagnostic certainty was substantially higher in PET/MR compared to PET/CT: for PSA-values 0.2 – 0.5 ng/ml 38.5% vs.
69.2% of positive findings on PET/CT vs. PET/MR were rated as highly suggestive for prostate cancer recurrence.
68Ga-PSMA
10/23
25/35
PET/CT
67/71
122/127
Patient with biochemical recurrency (PSA 1.1ng/ml) after RPX ´00 (pT3b pN1 cM0 R0 GS5), androgen-withdrawal
´00-´05 and salvage RTX of prostatic bed ´11 (PSA 0.2ng/ml). 68Ga-PSMA-PET/CT shows a pathological signal
uptake in a single obturator LN, not described as suspicious on CT. A salvage PLA on the right side was performed
revealing a single LN metastasis in 1/9 LN (GS5). Subsequently, a complete PSA-drop <0.01ng/ml was observed.
68Ga-PSMA
13/26
9/12
PET/MRI
13/16
21/22
68Ga-PSMA
PET/MR in a patient nine months after RPX (pT3a pN0 cM0 G0 GS7a, iPSA 6.47ng/ml) presenting with
a rising PSA (0.4ng/ml; PSA nadir 0.17ng/ml). Axial 68Ga-PSMA PET and fused PET/MR demonstrate a high focal
uptake projecting on a 6mm pararectal LN in the T2-weighted MRI sequence. On MRI-based anatomical evaluation
alone the LN was not described as suspicious due to its small size and atypical location. The patient received targeted
radiation therapy of the prostate bed and boost on the suspicious LN with subsequent PSA-drop.
Conclusion.
68Ga-HBED-PSMA PET-imaging shows higher detection rates for patients with recurrent prostate cancer than reported for
other tracers especially at low PSA-values and most likely will replace other tracers like 18F-FDG or choline derivatives in
clinical practice. As salvage therapy is most effective at low PSA-levels, early detection of cancerous foci by 68Ga-HBEDPSMA PET-imaging might improve oncological results. PET/MR might be advantageous in patients with PSA <1 ng/ml as
multiparametric MR provides additional information, thus increasing the diagnostic certainty.