Abstracts 15^Th International Conference On Radiopharmaceutical Therapy (ICRT2020) December 5-6, 2020

Theragnostics

^99mTc-Prostate-Specific Membrane Antigen Single-Photon Emission Computed Tomography/Computed Tomography, an Evaluation of the Method Including Comparison with Methylene Diphosphonate Single-Photon Emission Computed Tomography/Computed Tomography

Marcel Baehr, Bernd Kuhn, Knut Liepe

Department of Nuclear Medicine, GH Klinikum Frankfurt (Oder), Frankfurt, Germany

Background: When PSMA-PET/CT and whole-body MRI are not available, current guidelines recommend CT imaging plus bone scan for prostate cancer staging of nodal and distant metastasis. Although ^99mTc-PSMA SPECT/CT (PSMA-SPECT/CT) is thought to be a valuable alternative, its method is not standardized, yet. Methods: In 67 patients PSMA SPECT/CT using 512 to 757 MBq ^99mTc-PSMA-API and MDP-SPECT/CT using 502 to 566 MBq of ^99mTc-MDP were performed. Routinely PSMA SPECT/CT includes whole-body scan after 1 hour and SPECT/CT after 4 to 6 hours. In three patients, repetitive SPECT/CTs were performed between 1 and 6 hours. Results: In PSMA SPECT/CT, variation of administered activity showed no significantly different changes in SUVlbm (SUV). Target-tobackground ratio (T/B) was higher in lymph nodes than bone lesions. T/B increased over time from 1 to 6 hours. PSMA SPECT/CT detected more lesions than whole-body scan, especially in body trunk. In extremities, no lesions were missed. PSMA SPECT/CT showed significantly higher T/B than MDP SPECT/CT. Mean effective doses were 7,8 mSv for PSMA SPECT/CT, 5,1 mSv for MDP SPECT/CT and usually 15 mSv for diagnostic CT. Conclusion: In PSMA SPECT/CT contrast was high and steadily increased within six hours after administration. With respect to patient comfort, imaging after 3 to 5 hours is optimal. Whole-body scan with SPECT/CT of body trunk facilitates detection of smallest lesions in body trunk without missing metastasis in extremities. PSMA SPECT/CT is favored against bone scan plus CT concerning radiation exposure, patient comfort and contrast in bone and lymph node metastases.

Publication History

Article published online:
19 April 2022

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