Detection of occult, undisplaced hip fractures with a dual-energy CT algorithm targeted to detection of bone marrow edema

Emerg Radiol. 2015 Feb;22(1):25-9. doi: 10.1007/s10140-014-1249-6. Epub 2014 Jul 2.

Abstract

The purpose of this study is to describe our initial clinical experience with dual-energy computed tomography (DECT) virtual non-calcium (VNC) images for the detection of bone marrow (BM) edema in patients with suspected hip fracture following trauma. Twenty-five patients presented to the emergency department at a level 1 trauma center between January 1, 2011 and January 1, 2013 with clinical suspicion of hip fracture and normal radiographs were included. All CT scans were performed on a dual-source, dual-energy CT system. VNC images were generated using prototype software and were compared to regular bone reconstructions by two musculoskeletal radiologists in consensus. Radiological and/or clinical diagnosis of fracture at 30-day follow-up was used as the reference standard. Twenty-one patients were found to have DECT-VNC signs of bone marrow edema. Eighteen of these 21 patients were true positive and three were false positive. A concordant fracture was clearly seen on bone reconstruction images in 15 of the 18 true positive cases. In three cases, DECT-VNC was positive for bone marrow edema where bone reconstruction CT images were negative. Four patients demonstrated no DECT-VNC signs of bone marrow edema: two cases were true negative, two cases were false negative. When compared with the gold standard of hip fracture determined at retrospective follow-up, the sensitivity of DECT-VNC images of the hip was 90 %, specificity was 40 %, positive predictive value was 86 %, and negative predictive value was 50 %. Our initial experience would suggest that DECT-VNC is highly sensitive but poorly specific in the diagnosis of hip fractures in patients with normal radiographs. The value of DECT-VNC primarily lies in its ability to help detect fractures which may be subtle or undetectable on bone reconstruction CT images.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Algorithms*
  • Bone Marrow / diagnostic imaging*
  • Diagnosis, Differential
  • Edema / diagnostic imaging*
  • Emergency Service, Hospital
  • False Negative Reactions
  • False Positive Reactions
  • Female
  • Hip Fractures / diagnostic imaging*
  • Humans
  • Male
  • Middle Aged
  • Radiographic Image Interpretation, Computer-Assisted
  • Sensitivity and Specificity
  • Tomography, X-Ray Computed / methods*