Analysis of clinical brain SPECT data based on anatomic standardization and reference to normal data: an ROC-based comparison of visual, semiquantitative, and voxel-based methods.
The technique of anatomic standardization and comparison with normal templates is increasingly used in clinical brain SPECT practice and allows automated, operator-independent volume-of-interest (VOI) or voxel-based analysis of whole-brain data. In 2 distinct clinical populations with severe traumatic brain injury and cognitive impairment, this study compared 3 widely available approaches that use normal templates to evaluate SPECT brain perfusion deficits.


METHODS
In total, 74 subjects were studied. These included 14 patients with severe, traumatic brain injury (group 1; 10 males, 4 females; mean age +/- SD, 27.6 +/- 8.2 y) and 15 patients with cognitive impairment (group 2; 7 males, 8 females; mean age, 75.8 +/- 8.6 y). These data were compared with those from, respectively, 25 and 20 age- and sex-adjusted healthy volunteers. All data were analyzed in 4 ways. Three semiquantitative statistical algorithms were used: statistical parametric mapping (SPM) using SPM99, brain registration and analysis of SPECT studies (BRASS) using a voxelwise region-growing technique, and a predefined VOI approach. These results were compared with visual analysis based on consensus reading by 3 experienced nuclear medicine physicians. Receiver operating characteristic (ROC) analysis was performed at various statistical cutoffs. Moreover, as a measure of regional agreement, relative regional agreement between methods was assessed.


RESULTS
In both study groups, BRASS voxel-based analysis was most accurate, as defined by the area under the ROC curve (0.97 for group 1 and 0.96 for group 2). VOI assessment was slightly more accurate than visual consensus analysis, whereas SPM showed, overall, a lower area under the ROC curve. SPM analysis was also significantly less sensitive at thresholds corresponding to low false-positive fractions. Regional analysis showed 83%-92% agreement between all methods.


CONCLUSIONS
Under clinical conditions, classification of brain SPECT studies can greatly be aided by anatomic standardization techniques and reference to normal data. Under the investigated circumstances, SPM was found to have a lower sensitivity than VOI or voxelwise region-growing techniques, especially at low false-positive fractions.
Van Laere
Koenraad J
KJ
Division of Nuclear Medicine, P7, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium. koen.vanlaere@rug.ac.be
Warwick
James
J
Versijpt
Jan
J
Goethals
Ingeborg
I
Audenaert
Kurt
K
Van Heerden
Ben
B
Dierckx
Rudi
R
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000000981:diagnostic imaging* / Q000473:pathology; D001930:Brain Injuries / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D002560:Cerebrovascular Circulation; D003072:Cognition Disorders / Q000000981:diagnostic imaging / Q000503:physiopathology; D003704:Dementia / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012015:Reference Standards; D012680:Sensitivity and Specificity; D015899:Tomography, Emission-Computed, Single-Photon