Comparison of quantitative methods for brain single photon emission computed tomography analysis in head trauma and...

In this study, three semi-automated (SA) methods for brain single photon emission computed tomography (SPECT) analysis were evaluated and compared with a quantitative manual (QM) method that allowed precise demarcation of telencephalic and cerebellar regions of interest.

Twenty patients with traumatic brain injury or stroke were imaged by SPECT after injection of 30 mCi (1110 MBq) of Tc-99m HMPAO: The SA methods included: 1) SA left-to-right ratio method, which generated uptake ratios in 4 pairs of symmetric brain sectors in each slice; 2) adjusted scale method, which displayed each slice according to a linear 10-color scale; and 3) SA brain-to-cerebellum ratio method, which exhibited a color scale indicating 5% change in the ratio.

The concordance with QM method was 85% for the adjusted scale method and 80% for the SA left-to-right ratio method. A combination of the Adjusted Scale Method and SA left-to-right ratio method yielded concordant results with the QM method in 95% of patients. Brain-to-cerebellum ratio method gave inconsistent findings because of variable cerebellar activity.

Semi-automated methods reliably evaluated relative brain perfusion in most patients. Whereas the adjusted scale method had the best correlation with the QM method, a combination of the adjusted scale method and SA left-to-right ratio method ws the most useful for routine analysis of brain perfusion. Semi-automated brain-to-cerebellum ratio method was found to be the least useful because of variability of cerebellum uptake, particularly when the brain uptake was higher than the cerebellum. The QM method allowed precise and most accurate delineation of regions of interest for quantitation of relative brain perfusion but required considerable operator input and knowledge of brain anatomy.