Virtual Noncalcium Dual-Energy CT: Detection of Lumbar Disk Herniation in Comparison with Standard Gray-scale CT

Abstract

To assess the diagnostic performance of dual-energy CT with reconstruction of virtual noncalcium (VNCa) images for the detection of lumbar disk herniation compared with standard CT image reconstruction. Materials and Methods:For this retrospective study, 41 patients (243 intervertebral disks; overall mean age, 68 years; 24 women [mean age, 68 years] and 17 men [mean age, 68 years]) underwent clinically indicated third-generation, dual-source, dual-energy CT and 3.0-T MRI within 2 weeks between March 2017 and January 2018. Six radiologists, blinded to clinical and MRI information, independently evaluated conventional gray-scale dual-energy CT series for the presence and degree of lumbar disk herniation and spinal nerve root impingement. After 8 weeks, readers reevaluated examinations by using color-coded VNCa reconstructions. MRI evaluated by two separate experienced readers, blinded to clinical and dual-energy CT information, served as the standard of reference. Sensitivity and specificity were the primary metrics of diagnostic performance.Results: A total of 112 herniated lumbar disks were depicted at MRI. VNCa showed higher overall sensitivity (612 of 672 [91%] vs 534 of 672 [80%]) and specificity (723 of 786 [92%] vs 665 of 786 [85%]) for detecting lumbar disk herniation compared with standard CT (all comparisons, P , .001). Interreader agreement was excellent for VNCa and substantial for standard CT (k = 0.82 vs 0.67; P , .001). VNCa achieved superior diagnostic confidence, image quality, and noise scores compared with standard CT (all comparisons, P , .001). Conclusion:Color-coded dual-energy CT virtual noncalcium reconstructions show substantially higher diagnostic performance and confidence for depicting lumbar disk herniation compared with standard CT.

Vertebral disk morphology of the lumbar spine: a retrospective analysis of collagen-sensitive mapping using dual-energy computed tomography

“…A previous study by Booz et al showed higher sensitivity and specificity of DECT compared with standard CT in detecting lumbar disk herniation and spinal nerve root impingement, suggesting that DECT might be as accurate as MRI [ 8 ]. However, Booz et al used a different reconstruction algorithm (virtual non-calcium reconstruction), while we investigated a three-material decomposition algorithm with a collagen-specific gradient.…”

“…In patients who have contraindications to diagnostic MRI or need a timely CT scan for other indications, disk visualization by CT could be helpful as an alternative diagnostic instrument. Previous studies have highlighted the value of DECT in intervertebral disk evaluation and have shown a higher sensitivity and specificity of DECT compared with standard CT in detecting lumbar disk herniation and spinal nerve root impingement [ 8 , 9 ]. However, these studies used different DECT reconstruction algorithms and did not compare results with MRI—the current diagnostic standard in detecting disk pathology.…”

A Review of the Applications of Dual-Energy CT in Acute Neuroimaging

“…In addition to detecting marrow edema, VNCa color map overlay images have been found to have higher overall sensitivity and specificity (91% and 92%, respectively) than standard CT for detecting lumbar disk herniation, using MRI as a reference standard 82 (Figure 6). In patients with vertebral fractures, color overlay collagen maps created using three-material decomposition techniques were found to be both sensitive (0.85) and specific (0.75) for disk injuries, with sensitivity varying from 0.80 to 0.98 depending on severity of disk injury.…”

“…77 Additional studies published after this meta-analysis assessing edema in vertebral compression fractures with VNCa demonstrated very similar sensitivities (between 85% and 98%) and specificities (between 92% and 99%), with an area under the receiver-operating characteristic curve ranging from 0.88 to 0.97. [78][79][80][81] In addition to detecting marrow edema, VNCa color map overlay images have been found to have higher overall sensitivity and specificity (91% and 92%, respectively) than standard CT for detecting lumbar disk herniation, using MRI as a reference standard 82 (Figure 6). In patients with vertebral fractures, color overlay collagen maps created using three-material decomposition techniques were found to be both sensitive (0.85) and specific (0.75) for disk injuries, with sensitivity varying from 0.80 to 0.98 depending on severity of disk injury.…”

Age-dependent microstructural changes of the intervertebral disc: a validation of proteoglycan-sensitive spectral CT

“…Recent studies suggest that DECT is also useful in depicting the morphology and microstructural changes of IVDs [17,18]. Additionally, virtual non-calcium (VnCa) maps have been shown to increase diagnostic performance and confidence for depicting lumbar disc herniation as compared with standard CT [19]. However, a systematic analysis of quantitative and qualitative aspects has yet to be conducted.…”