SPECT radioactive pharmaceuticals and their clinical uses

TracersHalf-lifeTargetMOAClinical useReferences
123I-IMP13.3 hrCBFLipophilic tracer crosses BBB, binds to brain tissue in proportion to perfusionDiagnosis of dementia, including AD[139, 140]
99mTc-HMPAO6.7 hrCBFLipophilic tracer crosses the BBB, gets trapped in neurons, and reflects cerebral perfusionDiagnosis and evaluation of AD, monitoring disease progression, and treatment response[141]
99mTc-ECD6 hrCBFBind to brain tissue, reflecting rCBFEvaluating cerebral perfusion, distinguishing AD from other dementias[142144]
123I-AV-45110 minAβ plaquesBinds to Aβ aggregates in the brainUsed to assess the presence of Aβ in AD[68]
123I-PiB13.3 hAβ plaques, tau proteinAmyloid-binding, PET-SPECT hybridDiagnosis of AD, differentiating AD from other dementias[125, 145]
Benzathine (99mTc-Tc-BZ)6.3 hAβ plaques, BBB disruptionBBB disruption, SPECT-imaging of brain function and perfusionDiagnosis of AD, monitoring disease progression, and treatment response[146]

123I-IMP: iodine-123 labeled 2-iodo-3-(N,N-dimethylamino) propylamine; 99mTc-HMPAO: technetium-99m hexamethylpropyleneamine oxime; 99mTc-ECD: technetium-99m ethyl cysteinate dimer; 123I-AV-45: iodine-123 amyvid (florbetapir); 123I-PiB: iodine-123 pittsburgh compound B; rCBF: regional cerebral blood flow; Aβ: amyloid beta; BBB: blood brain barrier; SPECT: single photon emission computed tomography; PET: positron emission tomography; AD: Alzheimer’s disease; MOA: mechanism of action