Latest Advances in Musculoskeletal Dual Energy Computed Tomography (DECT)

Added value of color-coded virtual non-calcium dual-energy CT in the detection of acute knee fractures in non-radiology inexpert readers

PURPOSE

To evaluated the added value of dual-energy CT (DECT) virtual non-calcium (VNCa) protocol on conventional CT in the detection of acute knee fractures in non-radiology inexpert readers.

METHOD

One hundred fifty-six patients (mean age, 51.97 years; age range, 17-86 years) with knee trauma, who underwent DECT and MRI within 3 days between April 2017 and October 2018, were retrospectively analyzed. Three readers (intern, 1st-year general surgery resident, 1st-year emergency medicine resident) independently analyzed CT alone and then with the additional color-coded DECT VNCa for fractures. A board-certified radiologist, analyzed CT and MRI series to define the reference standard. Sensitivity, specificity, and AUC were compared between the two reading sessions.

RESULTS

Fifty-seven patients had acute fractures and 99 had no fractures. Thirteen of 57 fractures were nondisplaced. The additional use of VNCa images significantly increased the mean AUC (reader 1: 0.813 vs. 0.919; reader 2: 0.842 vs. 0.930; reader 3: 0.837 vs. 0.921; P < 0.05). When only nondisplaced fractures included, the mean AUC was more increased in the combined analysis of CT and DECT VNCa (reader 1: 0.521 vs. 0.916; reader 2: 0.542 vs. 0.926; reader 3: 0.575 vs. 0.926; P <  .01). Sensitivity increased by 15 %-20 % in total fracture group and by 69 %-77 % in nondisplaced fracture group over that with CT alone when both CT and DECT VNCa were used. Specificity did not differ significantly.

CONCLUSIONS

The additional use of color-coded DECT VNCa protocol to conventional CT improved diagnostic performance in detecting acute knee fractures for inexperienced non-radiology readers.

The effect of tube voltage combination on image artefact and radiation dose in dual-source dual-energy CT: comparison between conventional 80/140 kV and 80/150 kV plus tin filter for gout protocol

OBJECTIVES

In dual-source CT, dual-energy (DE) performance is affected by various X-ray tube voltage combinations with and without tin filter (Sn). The purpose of this study was to assess the utility of the 80/150 Sn kV voltage combination in terms of image artefact and radiation dose for DECT gout protocol, compared with the conventional 80/140 kV.

METHODS

Seventy-four patients with suspected gout who underwent dual-source DECT examinations scanned at 80/140 kV (n = 37) and at 80/150 Sn kV (n = 37) were included. Patients' age, sex, and serum uric acid levels were matched between the two groups. The types and incidence of image artefacts and radiation dose were evaluated.

RESULTS

The 80/150 Sn kV group had significantly fewer patients with artefacts, compared to the 80/140 kV group [11 (30 %) of 37 vs 35 (94.6 %) of 37, p < 0.001]. Except for the motion artefact, the rest of the artefacts-skin, nail bed, submillimetre, motion, vascular, beam-hardening, clumpy artefact along tendon-were significantly less observed in the 80/150 Sn kV acquisitions. The dose-length product (DLP) and effective dose were significantly lower for the 80/150 Sn kV acquisitions compared with the 8s0/140 kV scans (DLP: 104.46 ± 10.66 mGy·cm vs 344.70 ± 56.39 mGy·cm, p < 0.001; effective dose: 1.04 ± 0.11 mSv vs 3.45 ± 0.56 mSv, p < 0.001).

CONCLUSIONS

The 80/150 Sn kV voltage combination in dual-source DECT system could be used as one of the artefact reduction methods while reducing radiation dose for gout protocol when compared to the conventional 80/140 kV.

KEY POINTS

• DECT has emerged as the leading modality for non-invasive diagnosis of gout. • Various X-ray tube voltage combinations are now feasible in dual-source DECT. • The 80/150 Sn kV acquisition could facilitate artefact reduction in gout protocol.

The Utility of Dual Energy Computed Tomography in Musculoskeletal Imaging

The objective of this article is to review the mechanisms, advantages and disadvantages of dual energy computed tomography (DECT) over conventional tomography (CT) in musculoskeletal imaging as DECT provides additional information about tissue composition and artifact reduction. This provides clinical utility in detection of urate crystals, bone marrow edema, reduction of beam hardening metallic artifact, and ligament and tendon analysis.