CT Angiography in the Emergency Department: Maximizing Contrast Enhancement and Image Quality While Minimizing Radiation Dose and Contrast Material Volume: Vascular/Interventional Radiology

Comparing Peristaltic and Direct-Drive Contrast Injection Systems for Thoracic Computed Tomography (CT): Effects on Dose, Image Quality, and Pathology

Introduction To compare thoracic vasculature opacification between the direct-drive and the peristaltic drive contrast injection systems and the effect on quantitative and qualitative image quality during computed tomography. Method A retrospective chart review of 88 patients who underwent chest computed tomography (CT) following a direct-drive injector before 2016 (Group A) or a peristaltic injector after 2016 (Group B). Both protocols employed 80mL of iodinated contrast media volume. Quantitative measurements of the thoracic vascular opacification, contrast-to-noise ratio (CNR), effective radiation dose, and arterial venous contrast ratio (AVCR) for each vessel were computed and compared. The measured values of vascular opacification, CNR, and dose length product (DLP) were assessed utilizing paired t-test and Pearson's correlation. Receiver operating characteristic (ROC), visual grading characteristics (VGC), and Cohen's kappa methodology were measured. Results There was no significant difference in the mean opacification of the chest vasculature (p > 0.05). The CNR in Group B was significantly lower than in Group A (p < 0.05) except for the brachiocephalic artery, proximal descending aorta, and the right pulmonary artery. Arterial venous contrast ratio at all anatomic levels demonstrated no statistical significance between groups. There were no differences in ROC, VGC, or kappa values between groups. Conclusion When comparing two contrast media injection systems in chest CT, there was no qualitative difference in image quality or pathology detection. However, quantitatively, direct-drive injectors provided higher CNR. Direct-drive contrast injectors also provided a superior quantitative image quality of chest vasculature compared to peristaltic injectors.

Low-dose three-dimensional CT angiography for the evaluation of posterolateral protrusion of the vertebral artery over the posterior arch of the atlas: a quantitative anatomical comparison study of the rotational and neutral positions

AIM

To investigate the changes in relevant anatomical parameters of posterolateral protrusion of the vertebral artery (VA) between head-neck rotational and neutral positions using low-dose three-dimensional computed tomography angiography (3D-CTA).

MATERIALS AND METHODS

Low-dose 3D-CTA images obtained for various craniocervical diseases in 36 non-dominant VA side patients with neutral, left and right head-neck rotational positions were evaluated. The relevant parameters from superior and inferior views, including external diameter (ED), internal diameter (ID), transverse diameter (TD), heights and diameters of posterolateral protrusion of the VA over the posterior arch of the atlas in the neutral and rotational positions, were recorded and compared.

RESULTS

There was no significant differences in the rotational angle (left/right: 31.23 ± 6.60/29.94 ± 6.09°, p>0.05). There were no significant differences in heights and diameters of bilateral VA between rotational and neutral positions (all p>0.05). The contralateral ID, ED, and TD of the rotational positions were significantly shorter than those of the neutral position (all p<0.05), while there were no significant differences in the three ipsilateral diameters (all p>0.05).

CONCLUSIONS

Posterolateral protrusion of the VA is not uncommon in the population, and surgeons should be aware of its presence, especially the increased possibility of injury to the VA caused by head-neck rotation, during the operation; thus, preoperative evaluation by low-dose 3D-CTA should be considered.