Bone marrow edema around the hip in non-traumatic pain: dual-energy CT vs MRI.

Objectives: To evaluate the diagnostic accuracy of dual-energy computed tomography (DECT) in identifying bone marrow edema (BME) around the hip joint in non-traumatic patients.
Methods: This prospective IRB-approved study was conducted between January 2019 and October 2019 and included 59 consecutive patients (18 males, 41 females; mean age 61.5 years, range 32-82) who were assessed by DECT and magnetic resonance imaging (MRI) within a 5-day period. Diagnostic accuracy values for diagnosing BME on a per-patient and on a per-partition-basis analysis were calculated for DECT images by two readers (R1 and R2, with 15 and 10 years of experience, respectively), using MRI as reference for diagnosis. Inter-observer agreements were calculated with k-statistics. A p value of < 0.05 was considered as statistically significant.
Results: MRI depicted BME in 44/59 patients (74.58%), with the involvement of 83/708 (11.72%) partitions. The sensitivity, specificity, and accuracy of R1 and R2 were 95.45% (42/44), 86.67% (13/15), and 93.22% (55/59) for R1, and 86.36% (38/44), 80.00% (12/15), and 84.75% (50/59) for R2. For both readers, the BME detection rate was higher in patients with severe edema (100%) in comparison to patients with mild edema (91.30% and 73.91%). In the partition-basis analysis, sensitivity, specificity, and accuracy ranges were 33.3 to 100%, 91.84 to 100%, and 88.14 to 100%, respectively. The inter-observer agreement for patients' analysis was substantial (k = 0.7065), whereas for partition analysis ranged from fair (k = 0.2976) to near-perfect (k = 1.000).
Conclusion: DECT can accurately identify BME around the hip joint, in comparison to MRI.
Key Points: • DECT can accurately identify bone marrow edema around the hip joint in a cohort of non-traumatic patients. • The detection of bone marrow edema by means of DECT may help the radiologist to identify associated findings, including avascular necrosis of the femoral head and insufficiency or stress fractures. • In cases of patients suffering from groin pain with bone marrow edema identified by DECT, the concurrent reading of high-resolution conventional CT images may increase the confidence of diagnosis and/or reduce the reading time.