A New Contrast Enhancement Protocol for Subtraction Coronary Computed Tomography Requiring a Short Breath-Holding Time

Abstract

Rationale and Objectives:We have developed a new contrast enhancement protocol for subtraction coronary computed tomography (SCCTA) requiring a short breath-holding time. In the protocol, test and main boluses were sequentially and automatically injected, and correct timings for pre-contrast and contrast-enhanced scans for main bolus were automatically determined only by the test bolus tracking. Combined with a fixed short main bolus injection for 7 seconds, the breath-holding time was shortened as possible. The purpose of this study was to evaluate whether use of this new protocol produced adequate quality images, taking into account calcified lesions and in-stent lumens.Materials and Methods: Patients (n = 127) with calcium scores of >400 Agatston units or a history of stent placement were enrolled. Breath-holding times were recorded, and image quality was visually evaluated by two observers.Results: The mean ± standard deviation breath-holding time was 13.2 ± 0.6 seconds. The mean ± SD computed tomography (CT) number of coronary arteries for the pre-contrast scan was sufficiently low [99.2 ± 32.2 Hounsfield units (HU)] and, simultaneously, that for SCCTA was 367.0 ± 77.2 HU. The rate of segments evaluated as unreadable was sufficiently low (3.8%).Conclusions: Use of the SCCTA protocol was efficient and allowed for a shorter breath-holding time and adequate diagnostic accuracy of SCCTA images, including images of calcified and stent implantation segments.

The usefulness of subtraction coronary computed tomography angiography for in-stent restenosis assessment of patients with CoCr stent using 320-row area detector CT

“…The main bolus injection for 7 seconds was automatically started, followed by injection of a saline solution for 7 seconds. [ 12 , 13 ] The iodine contrast medium (370 mgI/mL, iopamidol 370, Bayer AG, Germany) was injected via antecubital vein at a rate of body weight (kg) × 0.07, the total amount of main bolus injection injected was weight (kg) × 0.49–0.7 mL. After the injection of contrast medium, 40 mL of normal saline solution was immediately flushed at the same rate.…”

Clinical Applications of Wide-Detector CT Scanners for Cardiothoracic Imaging: An Update

“…The feasibility of subtraction CCTA has been verified by several studies, and subtraction CCTA allows for a significant improvement in diagnostic accuracy owing to its higher specificity and positive predictive value for the assessment of coronary artery stenosis than those of conventional CCTA alone (103)(104)(105)(106)(107)(108)(109). However, the proportion of segments excluded because of misregistration is still high even in the most recently published study, which reported misregistration in approximately half (53%) of all target segments (109).…”

“…Manual correction can be considered in case of significant lesions, but it is highly time-consuming. Moreover, although the breath-holding times of this single breath-hold method have been shortened to approximately 15–18 seconds, this breath-holding time remains problematic in some patients (107108). In highly selected patients for whom CCTA can be challenging because of an extensive calcium load or inability to tolerate breath-holding, with successful registration, subtraction CCTA may be helpful in the current technique.…”

“…Since Yoshioka and Tanaka (103) reported the initial experiences with subtraction CCTA using a 320-detector-row CT scanner in 2011, many researchers have attempted to develop better acquisition methods or subtraction algorithms. The most important factors for successful achievement of subtraction CCTA should be accurate registration of the two datasets; therefore, most current studies are based on the single breath-hold method to decrease the likelihood of misregistration between the two datasets (104)(105)(106)(107)(108).…”

Successful depiction of systemic collateral supply to pulmonary artery in CTEPH using time‐resolved 4D CT angiography: a case report

“…The examination was performed using a 256-row detector CT system (Revolution CT; GE Healthcare, Milwaukee, WI, USA) using the test bolus tracking method. 1 First, the test bolus was injected for 2 s, followed by a 0.9% saline solution for another 4 s. Then, after waiting for 20 s, the main bolus injection for 18 s was automatically started, followed by the injection of a saline solution for 4 s. The CT operator then manually pressed the acquisition trigger button at the beginning of the enhancement of the right ventricle in the test bolus (the trigger point), visually assessing the monitor images along with the enhancement curve measured in the region of interest (ROI) placed on the right ventricle. After the subsequent scan delay of 23 s from the trigger point, an intermittent image acquisition was automatically started.…”