O223	Is T1-weighted high field MRI sufficient to detect early atherosclerotic lesions? -Results from an ex-vivo study.
1T.Dietrich, 1U.Köhler, 1K.Preetz, 1Ph.Stawowy, 1M.Gräfe, 1S.Kelle, 2B.Schnackenburg, 1E.Fleck, 1E.Nagel, 1K.Graf
1Gernab Heard Institute Berlin/ Department of Internal Medicune / Cardiology, Berlin, DE; 2Philips Medical Systems, Hamburg, DE.

Abstract Objective: The non-invasive characterisation of the vessel wall requires imaging techniques capable of near microscopic resolution. High field MRI provides sufficient signal for the acquisition of high-resolution datasets. The aim of this study was the detailed analysis of the internal structure of the human vascular wall ex vivo with MRI and a comparison to histology. Methods: Tissue samples with low-grade atherosclerotic lesions (Stary 0-3; n=36) from iliac and femoral arteries were scanned at 7 Tesla (Pharmascan Bruker) using 3D slabs resulting in a resolution of 79x79x109 µm using spin echo sequences T1-weighted (T1), proton density weighted (PD) and T2-weighted (T2). Corresponding crossections of each sample obtained by MRI and histology were analyzed for areas of intima, media and adventitia, as well as the presence and extent of plaque. Results: Early lesions were present in 30 of 36 locations. Data sets from histology and MRI using linear regression analysis and Pearrson correlation revealed highly significant correlations preferentially using T2 and PD weighted images. Borderline significance was observed for the adventitial area. Detection and quantification of early lesions was limited wit T1-weighting (r=0.46) but excellent with T2 and PD (r= 0,802; r= 0,716 ; p<0.01). Furthermore, image data revealed a differentiated information on early lesion composition, which corresponded to the histology. Conclusion: T2 and PD-weighted images show a close correlation to histology for the spatial structure of the vessel wall and detection of early lesions. T1-weighted sequences do not provide sufficient information for the detection of early lesions.

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