2256. Incremental Value of Diffusion-Weighted Imaging Over Conventional Magnetic Resonance Imaging For the Diagnosis of Extremity Osteomyelitis
Authors * Denotes Presenting Author
  1. Mina Guirguis; University of Texas Southwestern Medical Center
  2. Oganes Ashikyan; University of Texas Southwestern Medical Center
  3. Parham Pezeshk; University of Texas Southwestern Medical Center
  4. Yin Xi; University of Texas Southwestern Medical Center
  5. Avneesh Chhabra *; University of Texas Southwestern Medical Center
To determine incremental value of diffusion-weighted imaging (DWI) over conventional MRI for the diagnosis of extremity osteomyelitis (OM).

Materials and Methods:
This cross-sectional study included a consecutive series of histologically proven extremity osteomyelitis and control cases. Musculoskeletal radiologists were asked to evaluate presence and absence of OM and abscess in two rounds – first blinded to the DWI using conventional MRI and radiographs, then again 4-weeks later with all above imaging and DWI images on a PACS system. The reader recorded a binary result as to whether OM and abscess was present or absent as well as their confidence in their diagnosis on a 1-5 scale (5 being most confident). This was compared with pathology-proven diagnosis to determine accuracy.

A total of 202 MRI and DWI scans of suspected OM were included in this study, with 66 being negative for both OM and abscess, 30 with OM, 68 with soft tissue abscess, and 38 diagnosed with both soft tissue abscess and OM. Reader accuracy in diagnosing osteomyelitis when blinded to DWI was 85%. When DWI was included, reader accuracy improved to 88%. The specificity of the reader‘s diagnosis with conventional MR was 81% and sensitivity was 80%, compared with a specificity of 91% and sensitivity of 89% with the addition of DWI. Furthermore, reader confidence also improved with the addition of DWI, from 4.59 to 4.82. A higher mean and minimum ADC value was associated with osteomyelitis (p value=<0.001). For diagnosis of soft tissue abscess, accuracy of conventional MR was 81%, and the addition of DWI raised it to 89%. Sensitivity and specificity with conventional MR were 87% and 77%, respectively, and with the addition of DWI, they became 88% and 90%, respectively. Reader confidence in soft tissue abscess rose from a mean of 4.32 to 4.76 when DWI was used. A lower mean and minimum ADC value was also associated with soft tissue abscess (p value = <0.001).

Diffusion weighted imaging improves diagnostic accuracy and reader confidence in diagnosis of extremity osteomyelitis and abscess.