{"entity":{"id":"tc-99m-pyrophosphate","kind":"drug","name":"Technetium Tc-99m pyrophosphate","aka":["Tc-99m PYP","PYP"],"tldr":"A bone-scanning radioactive tracer that also sticks to stray protein deposits that build up in a stiffened heart in transthyretin amyloidosis. Comparing how brightly the heart lights up against the ribs on the same scan tells doctors whether this specific, now-treatable type of heart disease is present, usually without needing a heart biopsy.","summary":"Technetium Tc-99m pyrophosphate (Technescan PYP, and generic/branded equivalents such as Phosphotec) is an old bone- and cardiac-imaging kit, FDA-approved for skeletal imaging of altered osteogenesis and, since the 1970s, as an adjunct in diagnosing acute myocardial infarction by direct uptake into necrotic tissue. Its label indications remain that dual scope (plus gated blood pool and gastrointestinal bleeding imaging via in vivo red blood cell labelling); it does not carry an FDA-labelled cardiac amyloidosis indication, and its use for that purpose is guideline-driven, off-label with respect to the original label wording, and now the dominant reason it is ordered in nuclear cardiology.\n\nThe evidence base for amyloid imaging is Gillmore et al. (2016, JAMA Cardiology, n=1,217: 857 with confirmed cardiac amyloidosis, 360 controls), which found 99% sensitivity and 86% specificity for ATTR cardiac amyloidosis using grade 2-3 myocardial uptake on planar/SPECT imaging, rising to 100% specificity and positive predictive value when combined with the absence of a monoclonal light-chain clone on serum/urine testing. ASNC/AHA/ASE/EANM/HFSA/ISA/SCMR/SNMMI multisociety expert consensus recommendations (with a 2021 addendum) formalised the protocol: SPECT or SPECT/CT confirmation of myocardial uptake is required (planar imaging alone is not diagnostic), typically read at both 1 hour and 3 hours after injection, with a visual grade of 2 or 3 classed as strongly suggestive of ATTR-CM, grade 1 as equivocal, and grade 0 as not suggestive.\n\nFDA labelled dosing for cardiac imaging is 370-555 MBq (10-15 mCi) intravenously, with imaging historically recommended 60-90 minutes post-injection for acute infarct detection; amyloid imaging protocols from the nuclear cardiology societies use similar activities with imaging windows out to 3 hours to reduce blood-pool interference.","asOf":"2026-09-22","links":[{"label":"FDA label: Technescan PYP (Tc-99m pyrophosphate), 2025 revision","url":"https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/017538s023,018321s026lbl.pdf"},{"label":"Gillmore et al. 2016, JAMA Cardiology: multicentre study of Tc-99m PYP for ATTR cardiac amyloidosis","url":"https://jamanetwork.com/journals/jamacardiology/fullarticle/2546034"},{"label":"ASNC practice points: 99mTc-pyrophosphate imaging for cardiac amyloidosis","url":"https://www.asnc.org/wp-content/uploads/2024/05/ASNC-Practice-Point-99mTechnetium-Pyrophosphate.2016.pdf"}],"tags":["SPECT","cardiac amyloidosis","bone-avid tracer"],"related":["tl-201-chloride","tc-99m-sestamibi","tc-99m"],"indications":["cardiac-amyloidosis-attr"],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"brand":"Technescan PYP","modality":"SPECT tracer","mechanism":"Tc-99m pyrophosphate has a specific affinity for areas of altered osteogenesis (bone turnover) and, at lower concentration, for acutely infarcted myocardium and, incidentally, for transthyretin amyloid deposits in the heart, apparently via co-deposition of calcium/microcalcification within the amyloid fibrils. In cardiac amyloidosis imaging, myocardial retention is graded visually against rib (bone) uptake on a 0-3 scale on SPECT (or SPECT/CT) images obtained roughly 1-3 hours after injection; grade 2 (equal to rib) or grade 3 (greater than rib) uptake is considered positive.","approvals":[{"region":"US","year":1976,"indication":"Skeletal imaging to demonstrate areas of altered osteogenesis"},{"region":"US","year":1976,"indication":"Cardiac imaging as an adjunct in the diagnosis of acute myocardial infarction"}],"mechanismSteps":[],"dosing":{"route":"Intravenous injection","schedule":"Cardiac imaging (per FDA label): 370-555 MBq (10-15 mCi); cardiac amyloidosis SPECT protocols (per ASNC/multisociety guidance, off-label with respect to the original infarct indication) use similar activity with imaging at 1 and/or 3 hours","source":"https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/017538s023,018321s026lbl.pdf"},"toxicity":[],"access":[],"regulatoryEvents":[]},"route":"/drugs/tc-99m-pyrophosphate/","neighbours":{"drug":[{"id":"tc-99m-sestamibi","kind":"drug","name":"Technetium Tc-99m sestamibi","route":"/drugs/tc-99m-sestamibi/"},{"id":"tl-201-chloride","kind":"drug","name":"Thallous chloride Tl-201","route":"/drugs/tl-201-chloride/"}],"isotope":[{"id":"tc-99m","kind":"isotope","name":"Technetium-99m","route":"/isotopes/tc-99m/"}],"indication":[{"id":"cardiac-amyloidosis-attr","kind":"indication","name":"Cardiac amyloidosis (transthyretin, ATTR-CM)","route":"/indications/cardiac-amyloidosis-attr/"}]}}