These images are from an 36 year old HIV positive man,
with a history of cognitive impairments. Functional images are from two time
points, before and after therapy with AZT.
These images show typical findings in AIDS dementia:
patchy hypoperfusion with a multifocal distribution which tends to be seen
prominently in the frontal lobes.
Compare with normal as follows. Defects in cerebral perfusion have
been previously reported in HIV positive individuals by single photon emission
computed tomography(SPECT).
The anatomic and clinical significance of these findings,
however, has remained uncertain. Because previous studies have shown that AIDS
dementia complex(ADC) is associated with both functional defects and structural
evidence of brain volume loss, we spatially matched(registered) the functional
and structural data to assess the extent to which observed perfusion defects
were "real", that is, represented low tracer uptake from structurally
normal brain.
The image datasets shown here are sampled along the same
plane of view, to permit the direct comparison of SPECT and MR images in ADC.
This type of analysis shows that there are functional defects(ie perfusion
defects) in areas that appear non-atrophic.
These are perhaps sites of early damage in which the
structural images are still relatively normal.
