MRI DIAGNOSIS OF ANTERIOR CRUCIATE LIGAME NT LESIONS - COMPARISON OF 1.0 T AND 0.2 T - EARLY RESULTS

The purpose of our study was to compare the diagnostic performance of a 0.2-T MRI unit and a 1.0-T MRI unit in the evaluation of the anterio r cruciate ligament in patients with clinically suspected lesions of t his ligament. Twenty four patients with clinically suspected lesions o f the anterior cruciate ligament underwent MRI of the knee on both 0.2 -T and 1.0-T MRI units. Three independent observers evaluated the exam inations for primary and secondary signs of a tear of the anterior cru ciate ligament. Frequency of these signs was determined for both modal ities, and observer agreement was assessed using the kappa statistic. Sixteen of 24 patients had signs of tears of the anterior cruciate lig ament on the 1.0-T unit; the 0.2-T unit detected primary signs in 15/1 6 (93 %) patients and secondary signs in 7/12 (43 %) patients. In 8 pa tients the 1.0 T unit showed neither primary nor secondary signs for t ears of the anterior cruciate ligament; in these patients the 0.2-T un it detected primary signs in 1/8 cases (12 %), and secondary signs in 3/8 cases (37 %). Observer agreement was very good for the 1.0-T unit and fair for the 0.2-T unit. There is no substantial difference betwee n 1.0-T units and 0.2-T MRI units in the visualisation of primary sign s of tears of the anterior cruciate ligament. In the visualisation of secondary signs, 1.0-T units are superior to 0.2-T units, and there is a surprisingly high rate of false-positive results with the 0.2-T uni t. As to the reproducibility of the results, the 1.0-T unit is far sup erior to the 0.2-T unit.