Several studies of other anatomical regions have shown the utility of DECT VNCa in traumatic bone lesions. The technique is relatively novel. In 2010, Pache et al. demonstrated posttraumatic bone bruise of the knee with DECT VNCa images [
5]. Their study included 21 patients and used MRI as the reference standard; the results for two readers were a sensitivity of 86.4% and specificity of 94.4%–95.5%. In a study of 14 patients with MRI and DECT-VNCa imaging, Ai et al. showed bone bruise persisting for up to 10 weeks after knee trauma [
9]. Guggenberger et al. studied the diagnostic performance of DECT VNCa images for detecting traumatic bone marrow lesions of the ankle in 30 patients [
10]. MRI was the reference standard, and they reported a high sensitivity of 90%, but a moderate specificity of 81.6%. Reddy et al. studied 25 patients with DECT VNCa for detection of occult, non-displaced hip fracture [
11]. The reference standard was clinical follow-up at 30 days. The study showed a high sensitivity of 90%, but poor specificity of 40%. Five patients had no fracture, but three of them had positive findings in the VNCa images. Kellock et al. recently performed a retrospective study of 118 patients with suspected nondisplaced hip fracture. Three readers used VNCa images in addition to the standard CT bone reconstructions. They reported an up to 5% increase in sensitivity from 95% to 100% compared to standard CT alone, while specificity of 100% remained unchanged as it was already high with standard CT [
6]. Reddy et al. attributed a low specificity in their study to degenerative changes of bone marrow in the femoral head or acetabulum, while Kellock et al. discussed whether this could be due to few patients without fracture. The technique has also been studied in vertebral compression fractures. Wang et al. studied 63 patients with 112 compression fractures using MRI as reference standard [
7]. They found overall sensitivity of 63% and specificity of 98.5%. In a similar study of 23 patients with 72 vertebral fractures by Karaca et al., a sensitivity of 89.3% and specificity of 98.7% were reported [
12]. Petritsch et al. recently studied 22 patients with 37 vertebral compression fractures [
13]. They reported improved sensitivity from 64% to 92% when quantitative analysis of VNCa images by measuring CT numbers was used in addition to visual analysis. However, specificity with this quantitative method was 82.6% compared to 99.3% with qualitative visual assessment. In summary, the results for the anatomical regions studied so far are showing VNCa imaging to be a promising technique for the demonstration of bone marrow edema in skeletal trauma.
Choice of imaging method for the suspected scaphoid fracture depends on resource availability, local expertise, financial cost and how fast the diagnosis should be established, for instance, in athletes and workers who cannot tolerate occupational absence. Financial cost estimates should take into account not only the cost of imaging, but also the number of lost workdays and re-consultation.
Traditional practice with initial immobilization and clinical control with x-ray within 7–10 days means that three of four patients are immobilized unnecessarily, cf. 25% are radiographically occult. Current recommendations for a prompt diagnosis consider MRI to be the preferred imaging method [
2]. A cost-analysis study has shown that an adapted protocol of MRI for scaphoid fracture is nearly equal to immobilization and repeat consultation [
8].
The value of DECT-VNCa imaging primarily lies in its ability to help detect fractures, which may be subtle or undetectable on bone reconstruction CT images. Further studies are warranted to provide knowledge of the accuracy of CT combined with VNCa images for the diagnosis of acute scaphoid fracture. This can lead to progression toward more efficient patient care as well as less unnecessary loss of function and work absence after wrist trauma.