Knee-joint articular cartilage demonstrated by magnetic resonance tomography. MR chondrovolumetry using a fat-suppressed FLASH-3D sequence

A fat-suppressed FLASH-3D sequence was optimized on healthy volunteers. A fresh cardaveric knee joint was removed from a 82-year-old man and immediately imaged without being frozen or fixed. MRT was carried out at 1.5 T and 25 mT/m (Vision, Siemens, Erlangen, Germany) with a conventional CP knee coil. Sagittal and transverse sections were acquired perpendicular to the articular surfaces, and then, parallel to these imaging planes, anatomical sections were obtained with a diamond band saw. The volumes of the patellar, tibial and femoral cartilages were determined from both the images and the sections, using an image analysing system. Signal intensities and contrast-to-noise ratios depend on the parameters used. The highest contrast between the cartilage and the periarticular tissues was obtained at a flip angel of 30 (TR=60 ms, TE=11 ms). However, a flip angle of 60 was judged to provide optimal subjective image quality. Using these parameters, the deviations between the radiological and the anatomical cartilage volumes were -4.7% in the patella, -3.1% in the tibial plateau and -4.2% in the femur. The volumes of the knee-joint cartilages may be accurately determined with MRT if an appropriate pulse sequence is chosen. (orig./VHE)