Comparison of manual tracing versus a semiautomatic radial measurement method in temporal lobe MRI volumetry for pharmacoresistant epilepsy

Introduction The aim of this study was to test a modified radial semiautomated volumetry technique (radial divider technique, RDT) versus the manual volumetry technique (MVT) for proportionality of temporal subvolumes in 30 patients with drug-resistant temporal lobe epilepsy. Methods Included in the study were 30 patients (15 female, 15 male; mean age 39.6 years) with pharmacoresistant epilepsy (mean duration 26.6 years). MRI studies were performed preoperatively on a 1.5-T scanner. All image processing steps and volume measurements were performed using ANALYZE software. The volumes of six subregions were measured bilaterally; these included the superior temporal gyrus (STG), middle + inferior temporal gyrus (MITG), fusiform gyrus (FG), parahippocampal gyrus (PHG), amygdala (AM), and hippocampus (HP). Linear regression was used to investigate the relationship between the comparable subvolumes obtained with MVT and RDT. Results Very high correlations (R ² >0.95) between RDT and MVT were observed for the STG + MITG and the STG + MITG + FG, but low correlations for the PHG subvolumes and the combined PHG + HP + AM subvolumes. These observations were independent of the side of the pathology and of hemisphere. Conclusion The two measurement techniques provided highly reliable proportional results. This series in a homogeneous group of TLE patients suggests that the much quicker RDT is suitable for determining the volume of temporolateral and laterobasal temporal lobe compartments, of both the affected and the non-affected side and the right and left hemisphere. C.-A. Mueller and J. Scorzin contributed equally to this work.