3D MRI VOLUME SIZING OF KNEE MENISCUS CARTILAGE

Meniscal replacement by allograft and meniscal regeneration through co llagen meniscal scaffolds have been recently reported. To evaluate the effectiveness of a replaced or regrown meniscal cartilage, a method f or measuring the size and function of the regenerated tissue in vivo i s required. To solve this problem, we developed and evaluated a magnet ic resonance imaging (MRI) technique to measure the volume of meniscal tissues. Twenty-one intact fresh cadaver knees were evaluated and sca nned with MRI for meniscal volume sizing. The sizing sequence was repe ated six times for each of 21 lateral and 12 medial menisci. The menis ci were then excised and measured by water volume displacement. Each v olume displacement measurement was repeated six times. The MRI techniq ue employed to measure the volume of the menisci was shown to correspo nd to that of the standard measure of volume and was just as precise. However, the MRI technique consistently underestimated the actual volu me. The average of the coefficient of variation for lateral volumes wa s 0.04 and 0.05 for the water and the MRI measurements, respectively. For medial measurements it was 0.04 and 0.06. The correlation for the lateral menisci was r = 0.45 (p = 0.04) and for the medial menisci it was r = 0.57 (p = 0.05). We conclude that 3D MRT is precise and repeat able but not accurate when used to measure meniscal volume in vivo and therefore may only be useful for evaluating changes in meniscal allog rafts and meniscal regeneration templates over time.