Prevalence of motion artifact simulating aortic dissection on spiral CT using a 180 ° linear interpolation algorithm for reconstruction of the images

Abstract

Appearance of a curvilinear interface in the ascending aorta which simulates an aortic dissection has been reported when using short-scan-time acquisitions (1 s) and not when using ultrafast CT (50 ms scan time) [1][2][3][4][5][6]. The artifact has been observed on both conventional and spiral scans. This artifact is thought to be related to the motion of the aortic wall in the interval time from end diastole to end systole [1, 5, 6]. Recently, it has been suggested that segmented images from data which have been collected during 0.6 s of a full 1-s scan of a conventional axial image can be retrospectively reconstructed to eliminate this artifact [1]. Spiral CT, which has gained widespread acceptance, requires interpolation to synthesize transaxial images from the volume data set [7]. The simplest approach is linear interpolation between spiral projection data sets from adjacent turns (i. e. 360°apart). However, using this interpolation volume, averaging artifacts due to the broadening of the section sensitivity profile have been noted [8, 9]. Consequently, all current spiral CT scanners reorder the projection data and perform interpolation from views separated by 180°(180°linear interpolation) [9]. In our previous personal experience (unpublished data), we often observed motion artifacts in the proximal part of the ascending aorta which simulate aortic dissection, using a 360°linear interpolation algorithm, as well as other series [3,4]. In several cases these artifacts disappeared when a 180°linear interpolation algorithm was used (Fig. 1).The goal of this study was to evaluate the prevalence of the pseudo-aortic dissection using a 180°linear interpolation algorithm. To our knowledge, the prevalence of the pseudo-aortic dissection using a 180°linear interpolation algorithm, in a large series, has not been reported. Materials and methodsA total of 100 consecutive dynamic contrast-enhanced spiral chest CT examinations, taken during a 1-month interval, performed on a Somatom Plus S CT scanner (Siemens Medical Systems, Erlangen, Germany) for a variety of non-selected indications, excluding clinical suspicion of aortic dissection (i. e. lymphoma followup, lung-cancer staging, mediastinal lymph nodes), were obtained for assessment of the thoracic aorta. The patients included 41 women and 59 men, 19-85 years old (mean age 57 years). Spiral chest CT examinations were performed during a single breath-hold using 10 mm/s table motion, 10 mm collimation, and 10 mm contiguous reconstructions from the lung apex to the diaphragm. The contrast enhancement was provided by a monophasic bolus IV infusion of 120-150 ml of contrast material injected at a rate of 2 ml/s via an antecubital vein. Scanning began 30 s after the initialization of the bolus. Contiguous reconstruction were obtained with a 180°linear interpolation algorithm.The CT examinations were independently and retrospectively reviewed by two experienced radiologists in vascular radiology (P. L. and F. G.). Studies were interpreted as positive if at least one image sho...

Helical and Single-Slice Conventional CT Versus Electron Beam CT for the Quantification of Coronary Artery Calcification

“…Research shows that in helical CT reconstruction, the 180° linear interpolation algorithm is superior to the 360° linear interpolation algorithm for reducing motion artifacts in the ascending aorta [20]. The 180° linear interpolation algorithm, widely available in helical CT scanners, involves a data range of 2 × (180° + Φ ), with a fan beam angle Φ of 52°.…”

ECG-correlated imaging of the heart with subsecond multislice spiral CT

“…Although similar ideas have been proposed for single slice CT, a few years ago [2], [3], their generalization to multislice CT turned out to be very effective and to overcome the known problems of cardiac imaging from single slice CT [4], [5]. Unlike other manual approaches that retrospectively select the best images for diagnosis [6], [7] or retrospectively determine the optimal "timing shift" about which to center a partial scan reconstruction [8], the algorithms developed by our group are dedi-cated cardiac reconstruction algorithms that automatically allow us to reconstruct complete volumes at any cardiac phase. They require the simultaneously recorded electrocardiogram (ECG) of the patient for synchronization purposes.…”

ECG‐correlated image reconstruction from subsecond multi‐slice spiral CT scans of the heart

“…2 Since spiral CT offers many features such as excellent volume scanning capability, high rotation speed ͑subsecond scanning͒, quantitative imaging, high resolution, and broad availability 3,4 there have been many attempts to use standard spiral scanning for cardiac imaging. [5][6][7] The only methods known to us that used dedicated cardiac reconstruction algorithms for heart imaging are the ones presented in a previous article: Electrocardiogram ͑ECG͒ data, recorded during the scan, may be used to divide projection data into ranges that are allowed or forbidden to be utilized for reconstruction. 8 The results are promising, although further work has to be done to improve image quality and to establish means for quantification of coronary calcium.…”