Emergency: Abdomen and Vessels

Benefits or pitfalls of dual-energy CT

Key images Findings

51-year-old female with impaired renal function (creatinine: 1.65 mg/dl, GFR: 36 ml/min) due to lupus nephritis underwent right renal biopsy that was complicated by perirenal hematoma. Drop of hemoglobin level was noted. The patient was referred to dual-energy CT to exclude active bleeding. Due to impaired renal function, CT was performed with reduced contrast volume (40 ml).

Boosting of contrast enhancement at lower keV virtual monoenergetic images allows the use of low contrast volume for 3D volume rendering images.

Axial images, 3D volume rendered images

Conventional axial CT with low contrast volume (40 ml) was performed and interruption of right posterior renal capsule and perirenal hematoma was demonstrated without active bleeding. Renal defect was better demarcated on virtual monoenergetic images at 40 keV. Conventional 3D volume rendered images were of poor quality. 3D volume rendered images at 40 keV provided significantly improved image quality.

Discussion

Virtual monoenergetic images at 40 keV improve visualization of vessels at dual-energy CT angiography. Diagnostic images could be provided with low-contrast volume in patients with poor renal function by dual-energy CT angiography that enables boosting of contrast enhancement at lower keV.

Conventional CT with contrast axial image, arterial phase: interruption of right posterior renal capsule (white arrow) and perirenal hematoma (blue arrows), no active bleeding was demonstrated.

Conventional 3D volume rendered image: poor quality with low (40 ml) contrast volume.

3D volume rendered image at 40 keV: good quality image generated with boosted contrast.