Medial meniscus posterior root tear causes swelling of the medial meniscus and expansion of the extruded meniscus: a com
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Medial meniscus posterior root tear causes swelling of the medial meniscus and expansion of the extruded meniscus: a comparative analysis between 2D and 3D MRI Yoshiki Okazaki1 · Takayuki Furumatsu1 · Takuya Yamaguchi2 · Yuya Kodama3 · Yusuke Kamatsuki1 · Shin Masuda1 · Yuki Okazaki1 · Takaaki Hiranaka1 · Ximing Zhang1 · Toshifumi Ozaki1 Received: 1 December 2018 / Accepted: 18 June 2019 © European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA) 2019
Abstract Purpose This study aimed to clarify the advantages of three-dimensional (3D) magnetic resonance imaging (MRI) over two-dimensional (2D) MRI in measuring the size of the medial meniscus (MM) and to analyse the volumes of MM and the extruded meniscus in patients with MM posterior root tear (MMPRT), at 10° and 90° knee flexion. Methods This study included 17 patients with MMPRTs and 15 volunteers with uninjured knees. The MMs were manually segmented for 3D reconstruction; thereafter, the extruded part separated from the tibial edge was determined. The length, width, height, and extrusion of MM were measured by the 2D and 3D methods, and compared. The MM volume, extruded meniscus volume, and their ratio were also calculated using 3D analysis software in the two groups. Results The estimated length and posterior height of MM were larger with 3D MRI than with 2D MRI measurements. The MM volume was significantly greater in MMPRT knees than in normal knees, with increasing MM height. In MMPRT knees, the mean volume of the extruded meniscus and its ratio significantly increased by 304 mm3 (p = 0.02) and 9.1% (p 10 weeks, using the intra-class correlation coefficient (ICC), with the 95% confidence interval (CI).
Volume analysis of MM and the extruded meniscus Volume measurement of the meniscus was performed via voxel counting, which was calculated by the summation of all voxel volumes lying within the boundaries; this has been reported as a valid and accurate method of volume analysis [35]. All 3D images in the present study had a reconstructed matrix size of 512 × 512, pixel size of 0.352 mm2, and slice thickness of 1 mm. The volume of each voxel was 0.124 mm3, according to the following formula: 1 × 0.352 × 0.352. After visual confirmation of the exact segmentation of MM, the SYNAPSE VINCENT® software accomplished the MMV measurements automatically. MMEV was defined as the volume of the extruded meniscus beyond the inner articular part of MM (Figs. 1d, 2d). The MMEV ratio was calculated as MMEV divided by MMV to adjust for individual differences. In addition, the negative MMV in the inner articular part was determined as the MM remaining volume (MMRV). The MMRV ratio (MMRV/ MMV × 100) was also calculated. The 3D parameters (MML, MMBW, MMPH, MMME, and MMPE) and these volume measurements were compared between MMPRT knees and normal knees at 10° and 90° of knee flexion.
Reliability evaluation of the 3D segmentation A radiologic technologist and two orthopaedic surgeons (YoO and TF) retrospectively segmented MM and defined the MME area ma
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