Abstract
PurposeTo assess image quality of CT pulmonary angiography (CTPA) at reduced radiation exposure (RD-CTPA) and contrast medium (CM) volume using two different iterative reconstruction (IR) algorithms (iDose4 and iterative model reconstruction (IMR)) in comparison to filtered back projection (FBP).Materials and Methods52 patients (body weight < 100 kg, mean BMI: 23.9) with suspected pulmonary embolism (PE) underwent RD-CTPA (tube voltage: 80 kV; mean CTDIvol: 1.9 mGy) using 40 ml CM. Data were reconstructed using FBP and two different IR algorithms (iDose4 and IMR). Subjective and objective image quality and conspicuity of PE were assessed in central, segmental, and subsegmental arteries.ResultsNoise reduction of 55% was achieved with iDose4 and of 85% with IMR compared to FBP. Contrast-to-noise ratio significantly increased with iDose4 and IMR compared to FBP (p<0.05). Subjective image quality was rated significantly higher at IMR reconstructions in comparison to iDose4 and FBP. Conspicuity of central and segmental PE significantly improved with the use of IMR. In subsegmental arteries, iDose4 was superior to IMR.ConclusionsCTPA at reduced radiation exposure and contrast medium volume is feasible with the use of IMR, which provides improved image quality and conspicuity of pulmonary embolism in central and segmental arteries.
Highlights
With advances in CT technology offering high temporal and spatial resolution, the diagnostic accuracy of CT pulmonary angiography (CTPA) has increased with reported sensitivities and specificities of 83–100% and 89–97%, respectively [1,2,3]
Noise reduction of 55% was achieved with iDose4 and of 85% with iterative model reconstruction (IMR) compared to filtered back projection (FBP)
Contrast-to-noise ratio significantly increased with iDose4 and IMR compared to FBP (p
Summary
With advances in CT technology offering high temporal and spatial resolution, the diagnostic accuracy of CT pulmonary angiography (CTPA) has increased with reported sensitivities and specificities of 83–100% and 89–97%, respectively [1,2,3]. An optimized CTPA protocol with a combination of both reduced radiation dose and reduced CM volume would be desirable. Low tube voltage CTPA protocols have shown the ability to reduce radiation dose and, by shifting the average x-ray photon energy closer to the k-absorption edge of iodine, to reduce CM volume in non-obese patients [9,10,11,12]. Previous studies have shown the feasibility of low KV CTPA examinations combined with IR, facilitating good image quality [14]. A combination of both, low kilo voltage CTPA protocol and IR may facilitate the reduction of both, radiation dose and CM volume, while maintaining image quality. The aim of this study was to assess image quality of CTPA at reduced radiation exposure (RD-CTPA) and CM volume using the two different IR algorithms iDose and IMR in comparison to filtered back projection (FBP)
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