Indirect CT Venography at 80 kVp with Sinogram-Affirmed Iterative Reconstruction Compared to 120 kVp with Filtered Back Projection: Assessment of Image Quality and Radiation Dose.

Inyoung Song,Jeong Geun Yi,Sung Min Ko,Jeong Hee Park,Chin-Tu Chen

doi:10.1371/journal.pone.0163416

Inyoung Song, Jeong Geun Yi + Show 3 more

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https://doi.org/10.1371/journal.pone.0163416

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Journal: PloS one	Publication Date: Sep 23, 2016
Citations: 5	License type: CC BY 4.0

Affiliation: Konkuk University Medical Center

Abstract

ObjectiveTo evaluate the image quality and radiation dose of indirect computed tomographic venography (CTV) using 80 kVp with sinogram-affirmed iterative reconstruction (SAFIRE) and 120 kVp with filtered back projection (FBP).Materials and MethodsThis retrospective study was approved by our institution and informed consent was waived. Sixty-one consecutive patients (M: F = 27: 34, mean age 60 ± 16, mean BMI 23.6 ± 3.6 kg/m2) underwent pelvic and lower extremity CTVs [group A (n = 31, 120 kVp, reconstructed with FBP) vs. group B (n = 30, 80 kVp, reconstructed with SAFIRE)]. The vascular enhancement, image noise, contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR) were compared. Subjective image analysis for image quality and noise was performed by two radiologists. Radiation dose was compared between the two groups.ResultsCompared with group A, higher mean vascular enhancement was observed in the group B (group A vs. B, 118.8 ± 15.7 HU vs. 178.6 ± 39.6 HU, p < 0.001), as well as image noise (12.0 ± 3.8 HU vs. 17.9 ± 6.1 HU, p < 0.001) and CNR (5.1 ± 1.9 vs. 7.6 ± 3.0, p < 0.001). The SNRs were not significantly different in both groups (11.2 ± 4.8 vs. 10.8 ± 3.7, p = 0.617). There was no significant difference in subjective image quality between the two groups (all p > 0.05). The subjective image noise was higher in the group B (p = 0.036 in reader 1, p = 0.005 in reader 2). The inter-observer reliability for assessing subjective image quality was good (ICC 0.746~0.784, p < 0.001). The mean CT dose index volume (CTDIvol) and mean dose length product (DLP) were significantly lower in group B than group A [CTDIvol, 6.4 ± 1.3 vs. 2.2 ± 2.2 mGy (p < 0.001); DLP, 499.1 ± 116.0 vs. 133.1 ± 45.7 mGy × cm (p < 0.001)].ConclusionsCTV using 80 kVp combined with SAFIRE provides lower radiation dose and improved CNR compared to CTV using 120 kVp with FBP.

Highlights

Deep vein thrombosis (DVT) and acute pulmonary embolism (PE) are manifestations of venous thromboembolism (VTE)
Compared with group A, higher mean vascular enhancement was observed in the group B, as well as image noise (12.0 ± 3.8 Hounsfield unit (HU) vs. 17.9 ± 6.1 HU, p < 0.001) and contrast-to-noise ratio (CNR) (5.1 ± 1.9 vs. 7.6 ± 3.0, p < 0.001)
There was no significant difference in subjective image quality between the two groups

Summary

Introduction

Deep vein thrombosis (DVT) and acute pulmonary embolism (PE) are manifestations of venous thromboembolism (VTE). Since the combined indirect computed tomographic venography (CTV) of lower extremity and pulmonary CT angiography (CTPA) was described in 1998, this CT technique is increasingly being used and recommend for patients with suspected VTE because it can accurately depict PE to the level of segmental pulmonary arteries and concurrently demonstrate lower extremity DVT in a single examination [4,5,6] It uses only the contrast media already intravenously injected to enhance pulmonary artery and requires only additional 3 minutes to complete the overall examination [4,7,8]. In conjunction with low tube voltage, an iterative reconstruction (IR) algorithm which uses a correction loop in the reconstruction of an image from the raw image data to control noise on CT images has been received considerable attention in terms of maintaining image quality [16,17]

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