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. 2023 Jul 21;5(4):e220157. doi: 10.1148/rycan.220157

Figure 6:

Posttherapy monitoring of index lesions with SPECT/CT imaging. Fused SPECT/CT sagittal images in a 56-year-old man with prostate-specific membrane antigen (PSMA)–avid metastatic prostate cancer undergoing lutetium 177 (177Lu) PSMA-617 therapy. (A) Baseline fluorine 18 (18F) carboxy-fluoro-pyridine-carbonyl-amino-pentyl-ureido-pentanedioic acid (DCFPyL) PET/CT image demonstrates intense PSMA uptake in nodal, osseous, and hepatic metastases (arrows). (B–E) Posttherapy SPECT/CT image with 177Lu-PSMA-617 was performed approximately 24 hours after infusion of the therapeutic radiotracer after each of four cycles administered 6 weeks apart, demonstrating localization of the therapeutic radiopharmaceutical to the metastases. Index lesions in lymph node, bone, and liver (arrows) demonstrate decreased intensity of uptake with each cycle of therapy. (C) After cycle 2, the hepatic and nodal metastases were no longer conspicuous, and (E) after cycle 4, the spine metastasis was no longer conspicuous. Imaging the therapeutic radionuclide enables confirmation of effective delivery to the sites of cancer and detection of treatment response over the course of therapy, demonstrated by the changes in the imaged index lesions over time.

Posttherapy monitoring of index lesions with SPECT/CT imaging. Fused SPECT/CT sagittal images in a 56-year-old man with prostate-specific membrane antigen (PSMA)–avid metastatic prostate cancer undergoing lutetium 177 (177Lu) PSMA-617 therapy. (A) Baseline fluorine 18 (18F) carboxy-fluoro-pyridine-carbonyl-amino-pentyl-ureido-pentanedioic acid (DCFPyL) PET/CT image demonstrates intense PSMA uptake in nodal, osseous, and hepatic metastases (arrows). (B–E) Posttherapy SPECT/CT image with 177Lu-PSMA-617 was performed approximately 24 hours after infusion of the therapeutic radiotracer after each of four cycles administered 6 weeks apart, demonstrating localization of the therapeutic radiopharmaceutical to the metastases. Index lesions in lymph node, bone, and liver (arrows) demonstrate decreased intensity of uptake with each cycle of therapy. (C) After cycle 2, the hepatic and nodal metastases were no longer conspicuous, and (E) after cycle 4, the spine metastasis was no longer conspicuous. Imaging the therapeutic radionuclide enables confirmation of effective delivery to the sites of cancer and detection of treatment response over the course of therapy, demonstrated by the changes in the imaged index lesions over time.