Jie Luo MS, Presenter: Nothing to Disclose

Anne Cross MD, Abstract Co-Author: Nothing to Disclose

Pascal Sati Dipl Eng, PhD, Abstract Co-Author: Nothing to Disclose

Dmitriy A. Yablonskiy PhD, Abstract Co-Author: Nothing to Disclose

Failing to quantitatively assess the tissue damage in Multiple Sclerosis (MS) could be one of the reasons why correlation between conventional MRI, based on T1w and T2w images, and clinical findings remains weak. Herein, we applied a novel MRI technique, Gradient Echo Plural Contrast Imaging (GEPCI), which allows quantitative evaluation of degree of tissue damage in MS lesions (Sati, et al, Neuroimage 2010), for monitoring MS progression in humans.

Six Relapsing Remitting MS (RRMS) subjects under treatment were scanned using Siemens 1.5T Magnetom Sonata twice (6 months apart). Standard clinical 2D T1w, T2w and FLAIR images and 3D GEPCI images were obtained with a resolution of 1×1×3mm3. GEPCI technique produces quantitative T2* maps, and T1w images. Then, histograms of R2* (=1/T2*) values are generated for the whole White Matter volume. The histograms are comprised of a peak (approximating a Gaussian shape) and a tail of small R2* values, the latter corresponding to MS lesions. We define for each voxel a tissue damage score TDS = (R2*-R2c*)/R2c*, which scales the tissue damage from 0 (corresponding to normal tissue at the peak center, R2*=R2c*), to 1 (total demyelination and axonal loss). The tissue damage load (TDL) is the sum of TDS of all abnormal voxels, which incorporates both lesion load and severity.

We found that in all cases GEPCI scores were elevated compared to normal subjects, however the trend of their changes varied between subjects, reflecting different disease progression. A notable example from one patient showed an increase in the lesion load (total volume of abnormal voxels), but a decrease in the TDL over 6 months. These findings indicate an increase in the volume of lesions but improvement in their average pathology. These types of changes are not detectable by standard MR imaging.

In this study, we demonstrated that GEPCI technique provides an efficient method for monitoring progression of MS. This method not only depicts MS lesions similar to conventional T1w and FLAIR images, but also allows quantitative evaluation of disease progression in the target organ, based on tissue R2* relaxation rate constants.

The new MRI technique (GEPCI) provides information on MS disease pathology beyond conventional T1w and FLAIR images, allowing sufficient sensitivity for longitudinal studies of disease progression.

Luo, J, Cross, A, Sati, P, Yablonskiy, D, Quantitative Monitoring of the Multiple Sclerosis Progression Using Gradient Echo Plural Contrast Imaging Technique.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9011150.html