{"entity":{"id":"tc-99m-psma-imaging","kind":"drug","name":"Technetium Tc-99m PSMA agents (PSMA-I&S)","aka":["99mTc-PSMA-I&S","Tc-99m PSMA imaging and surgery"],"tldr":"A version of the PSMA prostate cancer scan that uses the same cheap, widely available radioactive tag as a standard bone scan instead of the PET tracers. Surgeons can also carry a small radiation detector into the operating room to help find and remove cancerous lymph nodes. It has not been through formal drug approval; it is used as an academic, in-house preparation.","summary":"99mTc-PSMA-I&S ([99mTc]Tc-mas3-y-nal-k(Sub-KuE)) was developed at the Technical University of Munich as a cost-effective, kit-based alternative to 111In-PSMA-I&T for PSMA-targeted radioguided surgery, first reported in the Journal of Nuclear Medicine in 2017. In that first-in-human report, preoperative SPECT/CT at 12 hours after injection showed high uptake in all lesions previously identified by 68Ga-PSMA-11 PET/MR, and a handheld gamma probe successfully guided intraoperative resection of metastatic lymph nodes down to 3 mm.\n\nBeyond radioguided surgery, retrospective single-centre series have used PSMA-I&S SPECT/CT as a stand-alone diagnostic tool: one series reported patient-based sensitivity, specificity and accuracy of 86%, 100% and 92% for detecting primary prostate cancer, and for restaging in biochemical recurrence, sensitivity of 67% with specificity of 100%, generally trailing PSMA-PET's reported sensitivity in the low-PSA setting but offering same-day, low-cost imaging with equipment most nuclear medicine departments already own. Because it is produced from an academic cold-kit under local institutional protocols rather than an FDA- or EMA-reviewed marketing application, it has no formal regulatory approval or labelled dose; reported clinical activities have ranged from roughly 500-700 MBq for combined SPECT-and-surgery protocols.","status":"emerging","asOf":"2026-09-22","links":[{"label":"Robu et al., J Nucl Med 2017: preclinical evaluation and first patient application of 99mTc-PSMA-I&S for SPECT imaging and radioguided surgery in prostate cancer","url":"https://jnm.snmjournals.org/content/58/2/235.full.pdf"},{"label":"Diagnostic value of 99mTc-PSMA-I&S SPECT/CT for prostate cancer detection and staging (2024)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC10798073/"}],"tags":["PSMA","SPECT","radioguided surgery","academic cold kit"],"related":["cu-64-sar-bispsma","in-111-pentetreotide","ga-68","tc-99m","in-111"],"indications":["prostate","prostate-bcr"],"sections":[],"technologies":["spect","spect-ct"],"targets":["psma"],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"modality":"SPECT tracer","mechanism":"PSMA-I&S (\"imaging and surgery\") is a urea-based small-molecule PSMA inhibitor labelled with technetium-99m via a MAS3 chelator. It binds prostate-specific membrane antigen on prostate cancer cells; because technetium-99m is a gamma emitter available from any hospital's own generator (unlike gallium-68 or fluorine-18, which need a generator or cyclotron dedicated to PET production), it can be used both for pre-operative SPECT/CT localisation and, with a handheld gamma probe, for intraoperative radioguided surgery.","approvals":[],"mechanismSteps":[],"toxicity":[],"access":[],"regulatoryEvents":[]},"route":"/drugs/tc-99m-psma-imaging/","neighbours":{"drug":[{"id":"cu-64-sar-bispsma","kind":"drug","name":"Copper-64 SAR-bisPSMA","route":"/drugs/cu-64-sar-bispsma/"},{"id":"in-111-pentetreotide","kind":"drug","name":"Indium-111 pentetreotide","route":"/drugs/in-111-pentetreotide/"}],"isotope":[{"id":"ga-68","kind":"isotope","name":"Gallium-68","route":"/isotopes/ga-68/"},{"id":"in-111","kind":"isotope","name":"Indium-111","route":"/isotopes/in-111/"},{"id":"tc-99m","kind":"isotope","name":"Technetium-99m","route":"/isotopes/tc-99m/"}],"indication":[{"id":"prostate-bcr","kind":"indication","name":"Biochemical recurrence of prostate cancer","route":"/indications/prostate-bcr/"},{"id":"prostate","kind":"indication","name":"Prostate cancer","route":"/indications/prostate/"}],"technology":[{"id":"spect","kind":"technology","name":"SPECT & bone scan","route":"/technologies/spect/"},{"id":"spect-ct","kind":"technology","name":"SPECT/CT","route":"/technologies/spect-ct/"}],"target":[{"id":"psma","kind":"target","name":"PSMA","route":"/targets/psma/"}]}}