Coronary artery calcium quantification from contrast enhanced CT using gemstone spectral imaging and material decomposition

• DOI: 10.1007/s10554-014-0474-0
• Publication Date: 2014-07-03T09:29:00Z
• Authors: Tobias A. Fuchs; Julia Stehli; Svetlana Dougoud; Bert-Ram Sah; Sacha Bull; Olivier F. Clerc; Mathias Possner; Ronny R. Buechel; Oliver Gaemperli; Philipp A. Kaufmann
• Keywords: Male; Cardiac-Gated Imaging Techniques; Contrast Media; 610 Medicine & health; Pilot Projects; Coronary Artery Disease; Coronary Angiography; Radiation Dosage; Severity of Illness Index; 2705 Cardiology and Cardiovascular Medicine; Electrocardiography; 03 medical and health sciences; 0302 clinical medicine; Predictive Value of Tests; 2741 Radiology, Nuclear Medicine and Imaging; Humans; Aged; Retrospective Studies; 10181 Clinic for Nuclear Medicine; Middle Aged; Coronary Vessels; Linear Models; Feasibility Studies; Radiographic Image Interpretation, Computer-Assisted; Female; Tomography, X-Ray Computed

To explore the feasibility of coronary artery calcium (CAC) measurement from low-dose contrast enhanced coronary CT angiography (CCTA) as this may obviate the need for an unenhanced CT scan. 52 patients underwent unenhanced cardiac CT and prospectively ECG triggered contrast enhanced CCTA (Discovery HD 750, GE Healthcare, Milwaukee, WI, USA). The latter was acquired in single-source dual-energy mode [gemstone spectral imaging (GSI)]. Virtual unenhanced images were generated from GSI CCTA by monochromatic image reconstruction of 70 keV allowing selective iodine material suppression. CAC scores from virtual unenhanced CT were compared to standard unenhanced CT including a linear regression model. After iodine subtraction from the contrast enhanced CCTA the attenuation in the ascending aorta decreased significantly from 359 ± 61 to 54 ± 8 HU (P < 0.001), the latter comparing well to the value of 64 ± 55 HU found in the standard unenhanced CT (P = ns) confirming successful iodine subtraction. After introducing linear regression formula the mean values for Agatston, Volume and Mass scores of virtual unenhanced CT were 187 ± 321, 72 ± 114 mm(3), and 27 ± 46 mg/cm(3), comparing well to the values from standard unenhanced CT (187 ± 309, 72 ± 110 mm(3), and 27 ± 45 mg/cm(3)) yielding an excellent correlation (r = 0.96, r = 0.96, r = 0.92; P < 0.001). Mean estimated radiation dose revealed 0.83 ± 0.02 mSv from the unenhanced CT and 1.70 ± 0.53 mSv from the contrast enhanced CCTA. Single-source dual-energy scanning with GSI allows CAC quantification from low dose contrast enhanced CCTA by virtual iodine contrast subtraction.