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 toolin cartilage evaluation. This observational and analytical study was designed to answer the question of whether there is arelationship between MRI and ultrasound in measuring cartilage thickness in the medial femoral condyle. The current study wasconducted at the Radiology Department of Rasole-Akram Hospital, Tehran, Iran, between March and May 2020. The samplesize was 18 people. The mean cartilage thickness of the left medial femoral cartilage was measured by T1 weighted MRI andultrasound from transverse, anterior, middle, and posterior medial femoral regions in nine healthy females with a mean ± stddeviation 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 alsoincluded. Pearson and Bland–Altman plots were used for correlations and agreements. Anterior longitudinal ultrasoundthickness measures were significantly positively correlated with MRI anterior (r = 0.93, p = 0.00001), transverse ultrasoundwith MRI anterior (r = 0.87 p = 0.0369), middle longitudinal ultrasound with MRI anterior (r = 0.87 p = 0.00002), and transverseultrasound 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 a goodabsolute agreement between corresponding measurements done by ultrasound and MRI. The results suggest that ultrasound maybe a good clinical tool for assessing relative cartilage thickness in medial femoral regions.