title: Detection of occult, undisplaced hip fractures with a dual-energy CT algorithm targeted to detection of bone marrow edema.
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.
authors.affiliation: Department of Radiology, Vancouver General Hospital, 899 West 12th Avenue, Vancouver, BC, Canada, V5Z 1M9.
authors.forename: T
authors.initials: T
authors.lastname: Reddy
authors.forename: P D
authors.initials: PD
authors.lastname: McLaughlin
authors.forename: P I
authors.initials: PI
authors.lastname: Mallinson
authors.forename: A C
authors.initials: AC
authors.lastname: Reagan
authors.forename: P L
authors.initials: PL
authors.lastname: Munk
authors.forename: S
authors.initials: S
authors.lastname: Nicolaou
authors.forename: H A
authors.initials: HA
authors.lastname: Ouellette
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001853:Bone Marrow / Q000000981:diagnostic imaging*; D003937:Diagnosis, Differential; D004487:Edema / Q000000981:diagnostic imaging*; D004636:Emergency Service, Hospital; D005188:False Negative Reactions; D005189:False Positive Reactions; D005260:Female; D006620:Hip Fractures / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011857:Radiographic Image Interpretation, Computer-Assisted; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*