Subtraction coronary computed tomography in patients with severe calcification

Abstract

To investigate the clinical usefulness of subtraction coronary computed tomographic angiography (CCTA) in patients with severe calcification. A 320-row area detector CT system was used in this study. The subjects were 78 patients (47 men and 31 women, 739 years of age) with an Agatston score of >300 who were able to undergo prospective one-beat scanning during a single breath-hold. The CCTA findings were compared against invasive coronary angiography. The diagnostic capabilities of CCTA for the severely calcified segments with and without the additional information provided by subtraction CCTA were compared. Severe calcification was observed in 174 (31.9%) of the 546 segments, and non-assessable regions were observed in 74 (13.6%) of the segments. The addition of subtraction CCTA information improved the diagnostic accuracy for segments with severe calcification from 67.8 to 82.8% on a per-segment basis and from 70.1 to 82.1% on a per-patient basis, with non-assessable segments considered to be stenotic. When non-assessable segments were considered to be an incorrect diagnosis, the diagnostic accuracy was improved from 48.3 to 75.9% on a per-segment basis and from 43.3 to 79.1% on a per-patient basis. In addition, when evaluation was limited to non-assessable segments, subtraction CCTA provided a diagnostic accuracy of 81.1% when non-assessable segments were considered to be stenotic or 66.2% when non-assessable segments were considered to be an incorrect diagnosis. Subtraction CCTA improves the diagnostic capabilities of CCTA in patients with severe calcification.

Diagnostic accuracy of a modified subtraction coronary CT angiography method with short breath-holding time: a feasibility study

“…In subtraction CCTA, to minimize misregistration artefact due to differences in the breath-hold position, the two scans for obtaining the mask image (mask scan) and post-contrast image (post-contrast scan) should ideally be performed in a single breath-holding. 3 A previous study using test injection method reported that breath-holding time is in the range of 20-40 s. 5 Another study using test injection method reported by Kidoh et al 14 demonstrated that they could shorten the breathholding time to approximately 20 s. On the other hand, Amanuma et al 6,7 reported that the breath-holding time was approximately 25 s using bolus-tracking method. They also described that subtraction CCTA could not be performed in some patients despite the administration of supplemental oxygen.…”

“…They also described that subtraction CCTA could not be performed in some patients despite the administration of supplemental oxygen. 6 Recently, modified subtraction CCTA with a short breathholding time using bolus-tracking method was reported. Although this investigation confirmed that this method could shorten the breath-holding time to ,15 s while providing diagnostic images, the diagnostic accuracy of the evaluation of significant stenosis itself was not evaluated.…”

“…1,2 Promising results have been reported applying subtraction CCTA using 320-detector row CT scanner in patients with severe calcifications or stents. [3][4][5][6][7][8] With subtraction CCTA, coronary calcifications and stents are removed by subtracting mask image data (pre-contrast image data) from post-contrast image data. To minimize misregistration artefact due to differences in the breath-hold position, the required scans (mask and post-contrast scans) should be performed in a single breath-hold.…”

“…3 Although this method may minimize misregistration artefacts, a long breath-holding time of approximately 20-40 s is required. [3][4][5][6][7][8] This long breath-holding time represents a major limitation for subtraction CCTA because it may exclude patients who cannot hold their breath for over 20 s.…”

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

“…This effective method allows calcium to be subtracted from coronary computed tomography angiography (CCTA) images, providing improved diagnostic accuracy over conventional CCTA in patients with severe coronary artery calcification and stent (1)(2)(3)(4)(5)(6)(7). SCCTA uses two CCTA datasets collected pre-contrast and after contrast enhancement.…”