RT Journal Article
SR Electronic
T1 Radiation dosimetry of Tc99m-PSMA I&S: a single-center prospective study
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP jnumed.120.253476
DO 10.2967/jnumed.120.253476
A1 Urbán, Szabolcs
A1 Meyer, Catherine
A1 Dahlbom, Magnus
A1 Farkas, István
A1 Sipka, Gábor
A1 Besenyi, Zsuzsanna
A1 Czernin, Johannes
A1 Calais, Jeremie
A1 Pávics, László
YR 2020
UL http://jnm.snmjournals.org/content/early/2020/12/04/jnumed.120.253476.abstract
AB Introduction: Tc-99m-labeled Mas3-y-nal-k(Sub-KuE) (Tc-99m-PSMA I&S) is a prostate specific membrane antigen (PSMA) tracer that can be used for planar and SPECT/CT gamma imaging and radio-guided surgery (RGS). The primary aim of this study was to estimate the dosimetry of Tc-99m-PSMA I&S using a hybrid method (sequential gamma planar imaging and one single SPECT/CT) in healthy volunteers. The secondary aim was to depict the tracer biodistribution and tumor-to-background ratios (TBR) in patients with prostate cancer (PCa). Methods: Dosimetry of Tc-99m-PSMA I&S was investigated in four healthy volunteers. Whole-body planar imaging was acquired at 1, 2, 3, 6 and 24 hours, and SPECT/CT at 6h after tracer injection. Contours of organs were drawn on all acquisitions to determine organ activity at each timepoint. Absorbed dose was estimated using two Methods: 1) independent curve-fitting manual method (Levenberg-Marquardt-based algorithm using dose factors from Radiation Dose Assessment Resource (RADAR) web site) and 2) OLINDA/EXM® v 2.0 software (HERMES Medical Solutions). Biodistribution of Tc-99m-PSMA I&S was assessed in ten patients with PCa on SPECT/CT images at 6 h. Tumor uptake (SUVmax), and TBR (tumor SUVmax/ background organ SUVmean) using muscle (T/M), bladder (T/B) and intestine (T/I) as background organs were determined. Results: The mean injected activity of Tc-99m-PSMA I&S was 717 MBq (range: 562-828). No adverse events related to the injection of Tc-99m-PSMA-I&S were reported. The average radiation effective dose was 0.0055 mSv/MBq with the RADAR manual method and 0.0052 mSv/MBq with OLINDA/EXM®. Total body effective dose ranged between 3.33-4.42 and 3.11-4.23 mSv, respectively. All PCa patients showed high tracer uptake in primary and metastatic lesions with T/M, T/B, T/I ranging from 5.29 - 110, 0.11 – 7.02 and 0.96 – 16.30, respectively. Conclusion: Effective doses of Tc-99m-PSMA I&S were comparable to those known for most of the Tc-99m tracers and was lower than 68Ga-labelled and 18F-labelled agents. Tc-99m-PSMA I&S SPECT/CT showed high TBR in PCa patients. This study can provide required data for translation and approval of Tc-99m-PSMA I&S by regulatory agencies.