RT Journal Article
SR Electronic
T1 PSA-Stratified Performance of <sup>18</sup>F- and <sup>68</sup>Ga-PSMA PET in Patients with Biochemical Recurrence of Prostate Cancer
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 947
OP 952
DO 10.2967/jnumed.116.185538
VO 58
IS 6
A1 Dietlein, Felix
A1 Kobe, Carsten
A1 Neubauer, Stephan
A1 Schmidt, Matthias
A1 Stockter, Simone
A1 Fischer, Thomas
A1 Schomäcker, Klaus
A1 Heidenreich, Axel
A1 Zlatopolskiy, Boris D.
A1 Neumaier, Bernd
A1 Drzezga, Alexander
A1 Dietlein, Markus
YR 2017
UL http://jnm.snmjournals.org/content/58/6/947.abstract
AB 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 using 18F-DCFPyL (n = 62, 269.8 MBq, PET scan at 120 min after injection) or 68Ga-PSMA-HBED-CC (n = 129, 158.9 MBq, 60 min after injection). 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 = 4.3 × 10−3). Sensitivity increased abruptly, when PSA values exceeded 0.5 μg/L (P = 2.4 × 10−5). For a PSA less than 3.5 μg/L, most relapses were diagnosed at a still limited stage (P = 3.4 × 10−6). For a PSA of 0.5–3.5 μg/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; 0.5 μg/L) or high (PSA &gt; 3.5 μg/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 = 2.71 × 10−8). However, in 36% of the PSMA-positive patients we detected additional lesions on the 18F-DCFPyL scan (P = 3.7 × 10−2). Conclusion: Our data suggest that 18F-DCFPyL is noninferior 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.