Everaldo Gregio-Junior, Abstract Co-Author: Nothing to Disclose

Marcello Henrique Nogueira-Barbosa MD, PhD, Abstract Co-Author: Nothing to Disclose

Mario M Lorenzato, Abstract Co-Author: Nothing to Disclose

Frank W. Roemer MD, Abstract Co-Author: Vice-President, Boston Imaging Core Lab LLC Shareholder, Boston Imaging Core Lab LLC Research Consultant, Merck KGaA

Ali Guermazi MD, PhD, Abstract Co-Author: President, Boston Imaging Core Lab, LLC Research Consultant, Merck KGaA Research Consultant, Novartis AG Research Consultant, sanofi-aventis Group Research Consultant, Stryker Corporation Research Consultant, AstraZeneca PLC

Michel D. Crema MD, Presenter: Shareholder, Boston Imaging Core Lab, LLC

MRI is commonly used and widely accepted for semiquantitative and quantitative assessments of meniscal extrusion (ME). Ultrasound (US) is widely available and can be applied for the assessment of ME. The aim of this study was to validate the semiquantitative and quantitative assessments of medial ME in US, using MRI measurements as the reference standard.

80 consecutive patients referred for knee MRI were also evaluated by US on the same day. US, using a 12-5 MHz linear probe, and 1.5T routine MRI were performed with patients in a supine position. US was performed at the medial aspect of the knee in the longitudinal axis. Two skin markers were placed in the medial aspect of the knee where ME was assessed. On MRI, the coronal T2w sequence was used to evaluate medial ME, using the slice displaying both skin markers placed during US. For both methods, the edge of the medial tibial plateau was used as the reference for ME measurement. ME was assessed separately by 2 radiologists, and semiquantitatively graded as: 0 (< 2mm), 1 (≥2mm and <4mm), and 2 (≥ 4mm). The agreement comparing ME measurements between US and MRI was assessed using weighted kappa (κ) statistics. Also, intraclass correlation coefficients (ICC) were used to assess agreement using absolute values of measurements (quantitative assessment). Inter-reader reliability for US and MRI ME grades was assessed using κ statistics. The diagnostic performance of US in the detection of ME was evaluated using MRI data as the reference.

When comparing ME grades between US and MRI, the agreement was moderate for reader 1 (κ =0.57) and substantial for reader 2 (κ=0.64). When comparing ME absolute values between US and MRI, a substantial agreement was found for both readers (ICC of 0.73 and 0.70 respectively). Inter-reader agreement was substantial for MRI measurements (κ=0.7) and almost perfect for US measurements (κ=0.98). For both readers, US showed excellent sensitivity (95% and 96%) and good specificity (82% and 70%) in the detection of medial ME.

US is a reliable technique in both semiquantitative and quantitative assessments of ME, showing excellent diagnostic performance in the detection of ME when compared to MRI.

US is a powerful tool in the assessment of ME, as it may allow for dynamic evaluation from supine to weight-bearing positions, which would help the understanding of causes and consequences of ME.

Gregio-Junior, E, Nogueira-Barbosa, M, Lorenzato, M, Roemer, F, Guermazi, A, Crema, M, Ultrasonographic Assessment of Medial Meniscal Extrusion: A Comparative Study Using Magnetic Resonance Imaging (MRI) as the Reference Standard.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12027085.html