Table 2.

^99mTc‐based radiopharmaceuticals used for ancillary investigation in the determination of death by neurologic criteria

	Lipophobic radiopharmaceutical	Lipophilic radiopharmaceutical
Radiopharmaceutical examples (original imaging purpose)	99mTc‐DTPA (renal) 99mTc‐GHA (renal) 99mTc‐pertechnetate (thyroid)	99mTc‐HMPAO (functional brain) 99mTc‐ECD (functional brain)
Flow (angiographic) phase#	Primary diagnostic role	Confirmatory, nonmandatory, diagnostic role
Immediate (blood pool) phase#	Minimally contributory role*	Noncontributory
Parenchymal (delayed uptake) phase~	Not applicable	Primary diagnostic role
Criteria necessary to support DNC	Nonvisualization of intracranial flow	Absent parenchymal uptake in brain and brainstem and absent intracranial flow (if performed)
Conceptual and diagnostic limitations	Posterior fossa/brainstem not well‐visualized on anterior flow images 1‐ or 2‐second images are low count and statistically noisy, obscuring signal Specificity for DNC not adequately characterized	Brainstem not well‐visualized, especially on planar imaging. Use in premature and young infants limited Specificity for DNC not adequately characterized

^#By planar imaging only

^*Nonvisualization of venous sinuses supports diagnosis of DNC while visualization of venous sinuses is nonspecific

^~By planar or tomographic (SPECT) imaging

DNC = determination of death by neurologic criteria; DTPA = diethylenetriaminepentaacetic acid (pentetate); ECD = ethyl cysteinate dimer; GHA = glucoheptonate; HMPAO = hexamethylpropyleneamine oxime; SPECT = single photon emission computed tomography