Dosimetry estimation and preliminary clinical application of [99mTc]Tc-HYNIC-PSMA-XL-2 in prostate cancer

Abstract

Objective: Molecular imaging of prostate-specific membrane antigen (PSMA) inhibitors has become a favorite for prostate cancer (PCa). This study aimed to estimate the dosimetry and the preliminary clinical application of the [^99mTc]Tc-HYNIC-PSMA-XL-2, which is a novel imaging tracer invented by our team that can specifically targets PSMA for PCa and its metastases.

Methods: The single-photon emission computed tomography (SPECT) whole-body (WB) planar images were collected on 6 patients at 0.5, 1.0, 2.0, 4.0 and 8.0 h after ^99mTc-PSMA-XL-2 injection, respectively. The SPECT/computed tomography (CT) scan was carried out immediately following the WB planar image scan performed after 2.0 h. The volumes of interest (VOIs) of the bladder, heart wall, intestines, kidneys, liver, lungs, and spleen were segmented in the SPECT/CT images. VOIs of the salivary glands and the whole body were drawn in SPECT planar images. The dosimetry toolkit was used to process the data and project the SPECT/CT images onto planar images. The dosimetry analysis was performed using the IDAC-Dose dosimetry software. Furthermore, other PCa patients were enrolled to study the preliminary clinical application of [^99mTc]Tc-HYNIC-PSMA-XL-2.

Results: The clearance of [^99mTc]Tc-HYNIC-PSMA-XL-2 is primarily by the hepatobiliary and intestinal system, due to its lipophilic characteristic. The effective half-life of [99mTc]Tc-HYNIC-PSMA-XL-2 is about 3.90 h. High absorbed doses were observed in the salivary glands (1.93E-02 ± 3.88E-03 mSv/MBq), kidneys (1.63E-02 ± 7.32E-03 mSv/MBq) and spleen (1.21E-02 ± 2.64E-03 mSv/MBq). The total body effective dose was 4.84E-03 ± 9.30E-05 mSv/MBq. The preliminary clinical case indicated that [^99mTc]Tc-HYNIC-PSMA-XL-2 SPECT/CT could detect the primary prostate lesion, lymph node and bone metastases comprehensively.

Conclusion: [^99mTc]Tc-HYNIC-PSMA-XL-2 is a safe SPECT/CT tracer, which can detect prostate malignant lesions without interference from the bladder. In addition, the malignant lesions of the lymph node and bone of PCa patients also can be detected efficiently.

Keywords: Dosimetry; PSMA; Prostate cancer; SPECT/CT.