technetium-tc-99m-bicisate and Encephalitis--Viral

This is a case of herpes simplex encephalitis (HSE) examined with 99mTc-ethyl cysteinate dimer (ECD) and 99mTc-hexamethyl propyleneamine oxime (HMPAO) SPECT. Static images obtained with 99mTc-ECD showed a reduced tracer uptake of the temporal lobe but focal hyperactivity using 99mTc-HMPAO. Dynamic images indicated regional increase of cerebral blood perfusion with both tracers. Technetium-99m-ECD had rapid washout from the inflamed tissue, while 99mTc-HMPAO had avid uptake. Hypofixation of 99mTc-ECD leads to failure to detect the characteristic finding of temporal lobe hyperemia in acute HSE.

Topics: Acute Disease; Aged; Brain; Cysteine; Encephalitis, Viral; Female; Herpes Simplex; Humans; Hyperemia; Organotechnetium Compounds; Radiopharmaceuticals; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Technetium-99m-hexamethyl propyleneamine oxime (HMPAO) and 99mTc-ethyl cysteinate dimer (ECD) accumulate in brain tissue in proportion to regional cerebral blood flow in healthy subjects and in patients with a variety of neurological diseases. We report on four patients with herpes simplex encephalitis and the discordance between these two approved cerebral perfusion imaging radiopharmaceuticals.. SPECT images showed unilateral regional increase of 99mTc-HMPAO uptake and decrease of 99mTc-ECD uptake in the affected temporal lobe.

Topics: Brain; Cysteine; Encephalitis, Viral; Female; Herpes Simplex; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Male; Middle Aged; Organotechnetium Compounds; Radiopharmaceuticals; Technetium Tc 99m Exametazime; Temporal Lobe; Tomography, Emission-Computed, Single-Photon