Feasibility of spectral shaping for detection and quantification of coronary calcifications in ultra-low dose CT

Marleen Vonder,Gert Jan Pelgrim,Rozemarijn Vliegenthart,Matthijs Oudkerk,Thomas Henzler,Thomas G Flohr,Sèvrin E M Huijsse,Marcel J W Greuter,Mathias Meyer

doi:10.1007/s00330-016-4507-z

Abstract

ObjectivesTo evaluate detectability and quantification of coronary calcifications for CT with a tin filter for spectral shaping.MethodsPhantom inserts with 100 small and 9 large calcifications, and a moving artificial artery with 3 calcifications (speed 0–30 mm/s) were placed in a thorax phantom simulating different patient sizes. The phantom was scanned in high-pitch spiral mode at 100 kVp with tin filter (Sn100 kVp), and at a reference of 120 kVp, with electrocardiographic (ECG) gating. Detectability and quantification of calcifications were analyzed for standard (130 HU) and adapted thresholds.ResultsSn100 kVp yielded lower detectability of calcifications (9 % versus 12 %, p = 0.027) and lower Agatston scores (p < 0.008), irrespective of calcification, patient size and speed. Volume scores of the moving calcifications for Sn100 kVp at speed 10–30 mm/s were lower (p < 0.001), while mass scores were similar (p = 0.131). For Sn100 kVp with adapted threshold of 117 HU, detectability (p = 1.000) and Agatston score (p > 0.206) were similar to 120 kVp. Spectral shaping resulted in median dose reduction of 62.3 % (range 59.0–73.4 %).ConclusionsCoronary calcium scanning with spectral shaping yields lower detectability of calcifications and lower Agatston scores compared to 120 kVp scanning, for which a HU threshold correction should be developed.Key points• Sn100kVp yields lower detectability and lower Agatston scores compared to 120kVp• Adapted HU threshold for Sn100kVp provides Agatston scores comparable to 120kVp• Sn100 kVp considerably reduces dose in calcium scoring versus 120 kVp

Highlights

Since the publication of the considerable lung cancer mortality reduction due to computed tomography (CT) screening in theEur Radiol (2017) 27:2047–2054National Lung Screening Trial [1], lung cancer screening has become recommended by US and European healthcare organizations [2,3,4]
We found that the Sn100 kVp scan protocol with standard Hounsfield Unit (HU) threshold, resulted in lower detectability of calcifications and lower calcium scores regardless of coronary movement
Adaptation of the HU threshold for calcium scoring at Sn100 kVp resulted in similar detectability and Agatston score for small and medium patient size

Summary

Introduction

Since the publication of the considerable lung cancer mortality reduction due to computed tomography (CT) screening in theEur Radiol (2017) 27:2047–2054National Lung Screening Trial [1], lung cancer screening has become recommended by US and European healthcare organizations [2,3,4]. Since the publication of the considerable lung cancer mortality reduction due to computed tomography (CT) screening in the. The advent of low-dose CT lung cancer screening may offer the opportunity to screen for coronary calcifications. It is well known that smoking, the main risk factor for lung cancer, is a major risk factor for cardiovascular disease. Screening for cardiovascular disease combined with early detection of lung cancer, may improve the cost-effectiveness of chest CT screening. The potential for radiation dose reduction in lung cancer screening with this ultra-low dose chest CT was recently shown [5, 6]. A dose reduction up to 90 % was achieved with spectral shaping and advanced iterative reconstruction, while maintaining a high sensitivity of pulmonary nodule detection [5]

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