RT Journal Article
SR Electronic
T1 PSA-stratified performance of <sup>18</sup>F- and <sup>68</sup>Ga-labeled tracers in PSMA-PET imaging of patients with biochemical recurrence of prostate cancer
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP jnumed.116.185538
DO 10.2967/jnumed.116.185538
A1 Felix Dietlein
A1 Carsten Kobe
A1 Stephan Neubauer
A1 Matthias Schmidt
A1 Simone Stockter
A1 Thomas Fischer
A1 Klaus Schomäcker
A1 Axel Heidenreich
A1 Boris D. Zlatopolskiy
A1 Bernd Neumaier
A1 Alexander Drzezga
A1 Markus Dietlein
YR 2016
UL http://jnm.snmjournals.org/content/early/2016/11/30/jnumed.116.185538.abstract
AB Purpose: Several studies outlined the sensitivity of 68Ga-labeled PET tracers against the prostate-specific membrane antigen (PSMA) for localization of relapsed prostate cancer in patients with renewed increase in the prostate-specific antigen (PSA), commonly referred to as biochemical recurrence. Labeling of PSMA tracers with 18F offers numerous advantages, including improved image resolution, longer half-life and increased production yields. The aim of this study was to assess the PSA-stratified performance of the 18F-labeled PSMA tracer 18F-DCFPyL and the 68Ga-labeled reference 68Ga-PSMA-HBED-CC. Methods: We examined 191 consecutive patients with biochemical recurrence according to standard acquisition protocols with 18F-DCFPyL (N = 62, 269.8 MBq, PET scan at 120 minutes p.i.) or 68Ga-PSMA-HBED-CC (N = 129, 158.9 MBq, 60 minutes p.i.). We determined PSA-stratified sensitivity rates for both tracers and corrected our calculations for Gleason scores using iterative matched-pair analyses. As an orthogonal validation, we directly compared tracer distribution patterns in a separate cohort of 25 patients, sequentially examined with both tracers. Results: After prostatectomy (N = 106), the sensitivity of both tracers was significantly associated with absolute PSA levels (P = 4.3x10-3). Sensitivity increased abruptly, when PSA values exceeded 0.5µg/L (P = 2.4x10-5). For PSA &lt;3.5µg/L, most relapses were diagnosed at a still limited stage (P = 3.4x10-6). For PSA of 0.5-3.5µg/L, PSA-stratified sensitivity was 88% (15/17) for 18F-DCFPyL and 66% (23/35) for 68Ga-PSMA-HBED-CC. This significant difference was preserved in the Gleason-matched-pair analysis. Outside of this range, sensitivity was comparably low (PSA &lt;0.5µg/L) or high (PSA &gt;3.5µg/L). After radiotherapy (N = 85), tracer sensitivity was largely PSA-independent. In the 25 patients examined with both tracers, distribution patterns of 18F-DCFPyL and 68Ga-PSMA-HBED-CC were strongly comparable (P = 2.71x10-8). However, in 36% of the PSMA-positive patients we detected additional lesions on the 18F-DCFPyL scan (P = 3.7x10-2). Conclusion: Our data suggest that 18F-DCFPyL is non-inferior to 68Ga-PSMA-HBED-CC, while offering the advantages of 18F-labeling. Our results indicate that imaging with 18F-DCFPyL may even exhibit improved sensitivity in localizing relapsed tumors after prostatectomy for moderately increased PSA levels. Although the standard acquisition protocols, used for 18F-DCFPyL and 68Ga-PSMA-HBED-CC in this study, stipulate different activity doses and tracer uptake times after injection, our findings provide a promising rationale for validation of 18F-DCFPyL in future prospective trials.