Abstract
PurposeTo compare the image quality of prospectively ECG-gated low voltage coronary computed tomography angiography (CTA) with an administration of low concentration contrast medium.Method and MaterialsA total of 101 patients, each with a heart rate below 65 beats per minute (BPM), underwent a prospectively ECG-gated axial scan in CT coronary angiography on a 64-slice CT scanner. All patients were allocated in three groups (group A: n=31, 80kVp, 300 mgI/ml; group B: n=34, 100kVp, 300 mgI/ml; group C: n=36, 120kVp, 370 mgI/ml). The CT attenuation values of aortic root (AR), left main coronary artery (LMA), right main coronary artery (RMA) and chest subcutaneous fat tissue were measured. The contrast-to-noise ratio (CNR) of AR, LMA and RMA were calculated according to the formulas below. The values of computed tomography dose index (CTDI) and dose-length product (DLP) were recorded. Image quality was assessed on a 5-point scale. The results were compared using the one-way ANOVA and rank sum tests.ResultsThe values of CNR and SNR for vessels in group A and group B were not significantly different from group C (each p > 0.05). The effective radiation dose in group A (1.51±0.70 mSv) and group B (2.59±1.24 mSv) were both lower than group C (4.92±2.82 mSv) (each p < 0.05). There was no significant difference among the image quality scores of group A (4.10±0.41), group B (3.90±0.48) and group C (4.04±0.36) (each P > 0.05).ConclusionLow tube voltage coronary CT angiography using low concentration contrast medium does not affect the imaging quality for assessing the coronary arteries compared with high voltage coronary CT angiography using high concentration contrast medium. Meanwhile low concentration contrast medium allowed 47-69% of radiation dose reduction.
Highlights
Multi-detector-row computed tomography (MDCT) has been considered as the method of choice for the diagnosis, treatment planning and follow-up of many diseases, such as coronary heart disease (CHD), myocardial infarction (MI) and pulmonary embolism (PE)
Low tube voltage coronary CT angiography using low concentration contrast medium does not affect the imaging quality for assessing the coronary arteries compared with high voltage coronary CT angiography using high concentration contrast medium
It is reported that it produces 11–15 mSv to 21 mSv at 64-silice MDCT to CT coronary angiography [5,6,7] On the other hand, the concentration of the contrast agent plays an important role in image quality, which may affect the diagnosis of vascular disease, including CHD
Summary
Multi-detector-row computed tomography (MDCT) has been considered as the method of choice for the diagnosis, treatment planning and follow-up of many diseases, such as coronary heart disease (CHD), myocardial infarction (MI) and pulmonary embolism (PE). CT angiography (CTA) uses MDCT for rapid continuous scanning and, through multiple-planar and three-dimensional CT restructuring, is able to obtain a set of vascular images. Technical advances, such as the addition of detector rows, have significantly improved the spatial resolution and scanning speed of MDCT, which makes MDCT improve the diagnostic accuracy for coronary artery stenosis [1,2,3]. Despite those advantages compared to conventional diagnostic workup, radiation exposure is still a major concern [4]. Many reports have compared contrast media with different iodine concentrations during the enhancement of multiple organs and vessels on CT scans [14,15,16,17]
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