Correlation between the Clinical Course of CRMO Lesions and the Imaging Characteristics on Follow-up MRIs

Objective: To evaluate the correlation between the clinical course of chronic recurrent multifocal osteomyelitis (CRMO) lesions and their imaging characteristics on follow-up MRIs. Material and Methods: Two musculoskeletal fellowship-trained radiologists retrospectively reviewed the initial and follow-up MRI images of 9 CRMO patients who were treated in our institution from 2008 to 2018. Evaluation of clinical course was based on symptomatology, lab results and physical examination and was compared to MRI findings, on follow-up MRIs. Results: Thirty-five CRMO lesions in 9 patients were identified. Patient’s ages ranged from 4 to 15 years with a mean age of 10 years (S.D.±3.22). Six of the 9 patients were female. Only 21 of 35 lesions had been longitudinally followed by MRI. Of the 39 follow-up MRI exams, there was clinical improvement 15 times, and 24 times there was no clinical improvement confirmed by the clinician. Three MRI features: 1) bone marrow edema (BME) size, 2) BME signal intensity and 3) periosteal edema, significantly correlated with the clinical course (p-value<0.001). When there was the improvement of all these three findings, the correlation with clinical improvement was high with 80% sensitivity and 100% specificity. The area under the receiver operator characteristic curve was 0.90 (95% confidence interval 0.795-1.005). Fourteen silent clinical lesions were also identified. Conclusion: Bone marrow edema and periosteal edema correlated best with the clinical course of CRMO patients on follow-up MRIs.