CaLS system reproducible, improves cartilage lesion detection rates

The Cartilage Lesion Score (CaLS) system, a reproducible scoring system for cartilage lesions, has been found to improve the detection rate for disease progression monitoring, according to a study published online Jan. 16 by Radiology.

Osteoarthritis (OA) demands specific and sensitive imaging tools for early diagnosis and treatment as well as effective disease progression monitoring. Three MRI-based semiquantitative scoring systems are currently available for whole organ assessment of the OA joint: the Whole-Organ Magnetic Resonance Imaging Score (WORMS), Boston-Leeds Osteoarthritis Knee Score (BLOKS), and MR Osteoarthritis Knee Score (MOAKS). However, each system has both strengths and weaknesses associated with assessment of the joint with OA’s features.

Because cartilage degradation is a signature characteristic of OA, cartilage lesions are ideal for monitoring disease progression. Lead author Hamza Alizai, MD, of the University of California-San Francisco, and colleagues created a study to determine the reproducibility of CaLS, identify the association between CaLS-detected longitudinal change in cartilage lesions with known risk factors for OA progression, and compare detection of cartilage progression of CaLS with that of the semiquantitative systems WORMS and BLOKS.

The study was comprised of 52 participants who had two or more risk factors for OA but no symptoms or radiographic evidence of the disease. A healthy cohort of 25 additional participants with no risk factors and no radiographic evidence of OA was also included in the study. All participants had to be between 45 and 60 years old and have a body mass index between 19 and 27 kg/m2. The researchers conducted 3-T MRI on the right knee of all participants at baseline and at the 24 month follow-up. The images gathered were analyzed with WORMS, BLOKS, and CaLS systems and the progression of cartilage lesions from each system was compared with linear regression models.

Intraclass coefficient values for the inter- and intraobserver reliability of the CaLS system were 0.86 and 0.91. The CaLS system had a significantly higher detection of the three systems. When analyzed with CaLS, 51.8 percent of the lesions progressed. In comparison, 17.6 percent of the lesions progressed with WORMS and 13 percent did so with BLOKS. The difference between the measurement of progression between BLOKS and WORMS was not significant. With an odds ratio of 2.78, participants with OA risk factors had significantly higher odds of progression than those without risk factors under the CaLS system.

Though the study was limited by relatively small sample sizes and a lack of comparison between CaLS and the MOAKS system, “The quantitative measurement of cartilage lesions and the better detection of change in lesions over time that are enabled by the new CaLS system may help clinicians in the follow-up and management-related decision-making process for eventual treatment of cartilage degeneration,” wrote the authors.