Progress in SPECT and PET Reconstruction for Theranostics: From Diagnosis to Therapy.

The theranostic paradigm enables personalization of treatment by selecting patients with a diagnostic radiopharmaceutical and monitoring therapy using a matched therapeutic isotope. This strategy relies on accurate image reconstruction of both pretherapy and post-therapy images for patient selection and monitoring treatment. However, traditional reconstruction methods are hindered by challenges such as crosstalk in multi-isotope imaging and extremely low-count measurements data when imaging of alpha-emitting isotopes. Additionally, to fully realize the benefits of new imaging systems being developed for theranostic applications, advanced reconstruction techniques are needed. This review highlights recent progress and discusses critical challenges and unmet needs in theranostic image reconstruction.