Optimization and validation of a rapid high-resolution T1-w 3D FLASH waterexcitation MRI sequence for the quantitative assessment of articular cartilage volume and thickness

In view of follow up. survey and development of therapeutic strategies for osteoarthritis where cartilage deterioration plays an important role, a non invasive, reliable and quantitative assessment of the articular cartilage is desirable. The currently available high resolution T-1-weighted (T1-w) 3 D FLASH pulse sequences with frequency selective fat suppression are very t ime consuming. We have I)optimized a high resolution T1-w 3D FLASH water ex citation (WE) sequence for short acquisition time and cartilage visualizati on, and 2) validated this sequence for cartilage volume and thickness quant ification. The spectral fat presaturation was replaced by selective water e xcitation. The flip angle of the WE sequence was optimized for the contrast to noise (C/N-cart) ratio of cartilage. Sagittal datasets (voxel size: 0.3 1 x 0.31 x 2 mm(3)) of the knees of nine healthy volunteers were acquired b oth, with the 3D FLASH WE (17.2/6.6/30 degrees) sequence (WE) and a previou sly validated 3D FLASH fat saturated (42/11/30 degrees) sequence (FS). For validation of the WE sequence, cartilage volume, mean and maximal cartilage thickness of the two sequences were compared. Reproducibility was assessed by calculating the coefficient of variation (COV %) of 4 consecutive WE da ta sets in the volunteers. The acquisition rime was reduced from 16 ' 30 " (FS) down to 7 ' 14 " for the WE sequence. Image contrast and visualization of the cartilage was very similar, but delineation of the basal layer of t he cartilage was slightly improved with the WE sequence. A flip angle of 30 degrees provided the best C/N-cart ratios (WE). Reproducibility (COV) was between 1.9 and 5.9%. Cartilage volume and thickness agreed within 4% betwe en FS and WE sequence. The WE sequence allows for rapid, valid and reproduc ible quantification of articular cartilage volume and thickness, prerequisi tes for follow-up examinations. The reduced acquisition time (50% of FS) en ables routine clinical application and thus may contribute to a broader ass essment of osteoarthritis. (C) 2001 Elsevier Science Inc. All rights reserv ed.