Rz. Stodilka et al., Scatter and attenuation correction for brain SPECT using attenuation distributions inferred from a head atlas, J NUCL MED, 41(9), 2000, pp. 1569-1578
Citations number
40
Categorie Soggetti
Radiology ,Nuclear Medicine & Imaging","Medical Research Diagnosis & Treatment
Sequential transmission scanning (TS)/SPECT is impractical for neurological
ly impaired patients who are unable to keep their heads motionless for the
extended duration of the combined scans. To provide an alternative to TS, w
e have developed a method of inferring-attenuation distributions (IADs), fr
om SPECT data, using a head atlas and a registration program. The validity
of replacing TS with IAD was tested in 10 patients with mild dementia. Meth
ods: TS was conducted with each patient using a collimated Tc-99m line sour
ce and fanbeam collimator; this was followed by hexamethyl propyleneamine o
xime-SPECT. IAD was derived by deformably registering the brain component o
f a digital head atlas to a preliminary SPECT reconstruction and then apply
ing the resulting spatial transformation to the full head atlas. SPECT data
were reconstructed with scatter and attenuation correction. Relative regio
nal cerebral blood flow was quantified in 12 threshold-guided anatomic regi
ons of interest, with cerebellar normalization. SPECT reconstructions using
IAD were compared with those using TS (which is the "gold standard") in te
rms of these regions of interest. Results: When we compared all regions or
interest across the population, the correlation between IAD-guided and TS-g
uided SPECT scans was 0.92 (P < 0.0001), whereas the mean absolute differen
ce between the scans was 7.5%. On average, IAD resulted in slight underesti
mation of relative regional cerebral blood flow; however, this underestimat
ion was statistically significant for only the left frontal and left centra
l sulcus regions (P = 0.001 and 0.002, respectively). Error analysis indica
ted that approximately 10.0% of the total error was caused by IAD scatter c
orrection, 36.6% was caused by IAD attenuation correction, 27.0% was caused
by discrepancies in region-of-interest demarcation from quantitative error
s in IAD-guided reconstructions, and 26.5% was caused by patient motion thr
oughout the imaging procedure. Conclusion: SPECT reconstructions guided by
IAD are sufficiently accurate to identify regional cerebral blood flow defi
cits of 10%, which are typical in moderate and advanced dementia.