The Relationship Between MRI Classification Of Discoid Meniscus And Tear Pattern

Purpose To approach the relationship between MRI classification and tear pattern, to discuss the image characteristic of the classification.Materials?and?Methods 70 patients with arthroscope verified and 64 normal meniscus to contrast were examined with conventional MRI by Siemens Espree 1.5T and GE Signa Excite 1.5T HD TWINSPEED on sagittal and coronal slice. T1WI,T2WI,T2WI+FS,T2*GRE sequences were performed. The patients were divided into impuberal group(n=30) and adult group(n=40).The discoid meniscus were classified as slab type(n=33),wedge type(n=19),hyperthophied-horn type(n=18).Following quantitative parameters were measured. The meniscal width and tibial plateau width on the coronal slice showing the intterconcdyloid spine(a),calculated the ratio of them(b);the width of the anterior and posterior horns of the meniscus on the sagittal slice showing the maximum meniscal diameter, calculated the sum of the width of the anterior and posterior horns of the meniscus(c) and the ratio of the sum and the width of the maximum meniscal diameter(d); the maximum width showing"butterfly"change on the sagittal slice(e) ;the number of the spine showing"butterfly"change when the layer thickness was 4mm(f), analyzed the sensitivity and specificity of the diagnosis value of different parameter for discoid meniscus by ROC curve, the difference of a and b in different discoid meniscus type in MRI and the relationship between the classification and tear pattern.Results⑴No significant difference in the incidence of each type existed between impuberal group and adult group(P>0.05);⑵b> or =0.20 is the most reliable criterion the diagnose discoid meniscus (P<0.01),the sensitivity and specificity of a were 99%,96%, the sensitivity and specificity of d> or =0.70 to diagnose discoid meniscus were 96%,90%;⑶A significant difference in a and c existed between discoid and normal meniscus (P<0.01);⑷No significant difference in e existed between slab type and hyperthophied-horn type(P>0.05),meniscus of wedge type had wider width on the sagittal slice showing"butterfly"change(P<0.05);⑸A complex tear is a main type of tear pattern in each type of discoid meniscus, the occurrence of complex tear, horizontal tear and longitudinal tear are more common in slab and hyperthophied-horn type cases than wedge type cases, the occurrence of radial tear is more common in wedge type than the others. Conclusion?Comparing different quantitative parameters to diagnose discoid meniscus, b and d had more reliable sensitivity and specificity, a> or =20mm, c> or =22mm viewed as aid index to diagnose discoid meniscus . MRI could show tear pattern of discoid meniscus overall and provide more information and guidance for the choice of clinical method.