CT Pulmonary Angiography at Reduced Radiation Exposure and Contrast Material Volume Using Iterative Model Reconstruction and iDose4 Technique in Comparison to FBP

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.

Association of Radiation Doses and Cancer Risks from CT Pulmonary Angiography Examinations in Relation to Body Effective Diameter

“…As such, it is crucial to calculate an accurate organ-equivalent dose before obtaining an estimation of cancer risk. At the moment there is no research has been found that evaluated the organ dose and cancer risk meticulously in CTPA examination elsewhere (Laqmani et al, 2016(Laqmani et al, , 2014Sabel et al, 2016;Sauter et al, 2018). This study aims to evaluate the dose exposure and to estimate cancer risk attributes from CTPA examinations based on the size and habitus of the patients.…”

Radiation Doses and Cancer Risk from CT Pulmonary Angiography Examinations

“…Most of the CT-system is used 32 cm body phantom calculation for determining the CTDIvol contribute for this finding. For CTPA, several studies that focused on CT dose and its optimization techniques [2,[7][8][9]. Surprisingly, there is no known comprehensively studied describing SSDE in different size of the patient in CTPA examination.…”

“…Most studies reported that detrimental effects of radiation exposure are higher in susceptible patient populations, especially young women and children [11] As such, it is crucial to calculate an accurate organequivalent dose before obtaining an estimation of cancer risk. So far, no research has been found that evaluated the organ dose and cancer risk in CTPA examination based on previous study elsewhere [2,8,9,12]. This study aims to investigate the usefulness and effect of SSDE and patient size in evaluating radiation dose in CTPA examination and to estimate the cancer risk for each scan and organ.…”

Double-Low Dose Protocol of Computed Tomography Pulmonary Angiography (CTPA) in the Diagnosis of Pulmonary Embolism: A Feasible Approach for Reduction of Both Contrast Medium and Radiation Doses

“…The CT attenuation measured in main pulmonary trunk and left lower segmental pulmonary artery was found to be significantly higher in Group A than that in Group B (414.3±149.4 HU and 416.4±139.3 vs. 259.6±69.7 and 256.0±75.0 HU, p<0.0001) with no significant difference in signal-to-noise ratio (SNR) and contrast-to-noise-ratio (CNR) between the two groups (p>0.05). Most of the studies tested lowering kVp value with 80 or 100 kVp on CTPA examinations while achieving diagnostic images with low radiation dose, [35][36][37][38][39][40] while Boos and colleagues in their study further lowered the kVp to 70 without affecting image quality. It is well known that lowering tube voltage is associated with increased image noise, but this can be compensated by iterative reconstruction, which is confirmed by Boos study.…”

“…Of these reported double lowdose CTPA studies, most of them were performed in patients with normal BMI (mean value <25 kg/m 2 ). 30,35 In contrast, Boos and colleagues presented diagnostic quality images in large patients as well, although they did not include extremely obese patients. The limitations of previous studies including only normal sized patients or with missing data on BMI 43 have been overcome by Boos' study, with findings offering additional value to the current literature.…”