Measuring of knee cartilage thickness: A comparison between ultrasound and magnetic resonance imaging methods

Cartilage diameter evaluation is critical for cartilage assessment. Magnetic resonance imaging (MRI) is the gold standard tool in cartilage evaluation. This observational and analytical study was designed to answer the question of whether there is a relationship between MRI and ultrasound in measuring cartilage thickness in the medial femoral condyle. The current study was conducted at the Radiology Department of Rasole-Akram Hospital, Tehran, Iran, between March and May 2020. The sample size was 18 people. The mean cartilage thickness of the left medial femoral cartilage was measured by T1 weighted MRI and ultrasound from transverse, anterior, middle, and posterior medial femoral regions in nine healthy females with a mean ± std deviation as indicated below:thickness = 1.6 ± 0.04 m, weight = 55.3 ± 4.3 kg, age = 21.7 ± 0.8 years. Additionally, nine healthy males with thickness = 1.80 ± 0.02 m, weight = 78.6 ± 11.1 kg, age = 22.4 ± 0.7 years were also included. Pearson and Bland–Altman plots were used for correlations and agreements. Anterior longitudinal ultrasound thickness measures were significantly positively correlated with MRI anterior (r = 0.93, p = 0.00001), transverse ultrasound with MRI anterior (r = 0.87 p = 0.0369), middle longitudinal ultrasound with MRI anterior (r = 0.87 p = 0.00002), and transverse ultrasound and MRI middle (r = 0.87 p = 0.00001). Agreement in all aspects was good except between the anterior longitudinal ultrasound and MRI posterior. There was good absolute agreement between corresponding measurements done by ultrasound and MRI. The results suggest that ultrasound may be a good clinical tool for assessing relative cartilage thickness in medial femoral regions.