Decreasing the radiation dose for contrast-enhanced abdominal spectral CT with a half contrast dose: a matched-pair comparison with a 120 kVp protocol

Abstract

Objectives: To compare the estimated radiation dose of 50% reduced iodine contrast medium (halfCM) for virtual monochromatic images (VMIs) with that of standard CM (stdCM) with a 120 kVp imaging protocol for contrast-enhanced CT (CECT). Methods: We enrolled 30 adults with renal dysfunction who underwent abdominal CT with halfCM for spectral CT. As controls, 30 matched patients without renal dysfunction using stdCM were also enrolled. CT images were reconstructed with the VMIs at 55 keV with halfCM and 120 kVp images with stdCM and halfCM. The Monte Carlo simulation tool was used to simulate the radiation dose. The organ doses were normalized to CTDIvol for the liver, pancreas, spleen, and kidneys and measured between halfCM and stdCM protocols. Results: For the arterial phase, the mean organ doses normalized to CTDIvol for stdCM and halfCM were 1.22 and 1.29 for the liver, 1.50 and 1.35 for the spleen, 1.75 and 1.51 for the pancreas, and 1.89 and 1.53 for the kidneys. As compared with non-enhanced CT, the average increase in the organ dose was significantly lower for halfCM (13.8% ± 14.3 and 26.7% ± 16.7) than for stdCM (31.0% ± 14.3 and 38.5% ± 14.8) during the hepatic arterial and portal venous phases (p < 0.01). Conclusion: As compared with stdCM with the 120 kVp imaging protocol, a 50% reduction in CM with VMIs with the 55 keV protocol allowed for a substantial reduction of the average organ dose of iodine CM while maintaining the iodine CT number for CECT. Advances in knowledge: This study provides that the half iodine contrast medium protocol for abdominal CT with a dual-layer-dual energy CT can significantly reduce the increase in the average organ dose for non-enhanced CT as compared with the standard contrast medium protocol.

Individualized Scan Protocols in Abdominal Computed Tomography

“…By decreasing tube voltage, a substantial reduction in CM could be achieved without negatively influencing either objective or subjective image quality. 25,26 Reducing both parameters at the same time will decrease CNR and may lead to insufficient image quality. 13 However, in the current study, CNR was comparable between groups by adapting both radiation and CM dose, as intended in the study design.…”

“…Earlier studies focused on CM reduction in patients with reduced kidney function. By decreasing tube voltage, a substantial reduction in CM could be achieved without negatively influencing either objective or subjective image quality 25,26 . Reducing both parameters at the same time will decrease CNR and may lead to insufficient image quality 13 .…”

Early detection of hypervascularization in hepatocellular carcinoma (≤2 cm) on hepatic arterial phase with virtual monochromatic imaging: Comparison with low-tube voltage CT

“…[13] Recently, virtual monochromatic imaging (VMI) with dual-energy CE-CT imaging (DE-CT) has been introduced, and VMI at low keV is reported to show a similar contrast enhancement CT numbers of the abdominal organs as with SE-CT imaging with a dramatically reduced iodine dose. [14][15][16] However, no studies have investigated the use of VMI in the detection of hypervascularization of early HCC.…”