Increased differentiation of intracranial white matter lesions by multispectral 3D-tissue segmentation: preliminary results

MRI is a very sensitive imaging modality. however with relatively low speci ficity. The aim of this work was to determine the potential of image post-p rocessing using 3D-tissue segmentation technique for identification and qua ntitative characterization of intracranial lesions primarily in the white m atter. Forty subjects participated in this study: 28 patients with brain mu ltiple sclerosis (MS). 6 patients with subcortical ischemic vascular dement ia (SIVD), and 6 patients with lacunar white matter infarcts (LI). In routi ne MR imaging these pathologies may be almost indistinguishable. The 3D-tis sue segmentation technique used in this study was based on three input MR i mages (T-1, T-2-weighted, and proton density). A modified k-Nearest-Neighbo r (k-NN) algorithm optimized For maximum computation speed and high quality segmentation was utilized. In MS lesions, two very distinct subsets were c lassified using this procedure. Based on the results of segmentation one su bset probably represent gliosis, and the other edema and demyelination. In SIVD, the segmented images demonstrated homogeneity, which differentiates S IVD from the heterogeneity observed in MS. This homogeneity was in agreemen t with the general histological findings. The LI changes pathophysiological ly from subacute to chronic. The segmented images closely correlated with t hese changes, showing a central area of necrosis with cyst formation surrou nded by an area that appears like reactive gliosis. In the chronic state, t he cyst intensity was similar to that of CSF, while in the subacute stage, the peripheral rim was more prominent. Regional brain lesion load were also obtained on one MS patient to demonstrate the potential use of this techni que for lesion load measurements. The majority of lesions were identified i n the parietal and occipital robes. The follow-up study showed qualitativel y and quantitatively that the calculated MS load increase was associated wi th brain atrophy represented by an increase in CSF volume as well as decrea se in "normal" brain tissue volumes. Importantly, these results were consis tent with the patient's clinical evolution of the disease after a six-month period. In conclusion, these results show there is a potential application for a 3D tissue segmentation technique to characterize white matter lesion s with similar intensities on T-2-weighted MR images. The proposed methodol ogy warrants further clinical investigation and evaluation in a large patie nt population. (C) 2001 Elsevier Science Inc. All rights reserved.