Voxelwise computed diffusion-weighted imaging for the detection of cytotoxic oedema in brain imaging: a pilot study.

Abstract

Aim To evaluate voxelwise computed diffusion-weighted imaging (vcDWI) for the detection of cytotoxic oedema in brain imaging and to quantify the benefit of lesion contrast in comparison to standard b = 1000 s/mm2 by the example of acute ischaemic stroke. Materials and methods A retrospective evaluation of 66 patients (63 ± 15.9 years) suspected for acute ischaemic stroke who received diffusion-weighted magnetic resonance imaging and fluid-attenuated inversion recovery sequence. A neuroradiologist evaluated all examinations for acute ischaemic stroke based on diffusion-weighted imaging, the apparent diffusion coefficient and fluid-attenuated inversion recovery (reference standard) and 6 weeks later the vcDWI in a randomised manner. Time of analysis was noted. Signal intensities were acquired in lesions, in healthy tissue as well as in the cerebrospinal fluid. Contrast ratios and coefficients of variation were computed. Results A total of 218 lesions was found in 46/66 patients. vcDWI identified all patients and lesions correctly. The median evaluation time was 36 seconds (4-126 s) for the vcDWI and 44 seconds (9-186 s; P < 0.001) for the diffusion-weighted imaging/apparent diffusion coefficient reading. The contrast ratio in vcDWI (mean value 2.57, range 1.73-4.11) was higher than in b = 1000 s/mm2 (2.33, 0.83-3.85, P = 0.03) and the apparent diffusion coefficient map (1.83, 1.00-3.00, P < 0.001), respectively. Coefficients of variation in lesions and tissue did not differ significantly between vcDWI and b = 1000 s/mm2 ( P = 0.81/ P = 0.26). The signal intensity of cerebrospinal fluid was lower in vcDWI than in b = 1000 mm2/s (0.08 and 34.8, P < 0.001). Conclusion It could be shown that vcDWI has the potential to accelerate the detection of diffusion-restricted lesions in neuroimaging by improving the contrast ratios and reducing the T2 shine-through effect in comparison to standard diffusion-weighted imaging in brain imaging.