We evaluated the relationship between image degradation due to the reflux of contrast agent into the major neck veins and use of a left-arm injection site during computed tomographic (CT) angiography of the carotid arteries.
A total of 364 patients underwent 4-section carotid CT angiography performed with an injection into the right (n = 183) or left (n = 181) arm. We calculated the volume of refluxed contrast medium and measured the retrosternal distance measured as the shortest distance between the sternum and the arch or its branches. Nine patients underwent follow-up CT angiography weeks later by using the side of injection not used before for comparison.
The amount of refluxed contrast medium was greater with left-arm injection than with right-arm injection (P < 0.001). With left-arm injection, the volume was significantly correlated with the retrosternal distance (r = −0.514, P < 0.001), even after we adjusted for age and sex in the linear regression model (P < 0.001). Five of the 9 patients who received injections in both arms had no reflux of contrast medium, whereas 4 patients had obvious reflux after left-arm but not right-arm injection.
Normal compression of the left brachiocephalic vein due to a developmental decreased retrosternal space may degrade carotid CT angiograms because of reflux of contrast material into the cervical veins. This degradation can be avoided if right-arm injection is used.
From the *Department of Radiology, E-Da Hospital, I-Shou University, Kaohsiung County; and †Department of Neurology, Chang Gung Memorial Hospital, Taipei, Taiwan, ROC.
Received for publication July 15, 2006; accepted August 8, 2006.
Reprints: Chi-Jen Chen, MD, Department of Radiology, E-Da Hospital, I-Shou University, 1, E-Da Road, Jiau-Shu Tsuen, Yan-Chau Shiang, Kaohsiung County 824, Taiwan, ROC (e-mail: firstname.lastname@example.org).
Supported by research grants NSC 93-2314-B214-007, NSC 93-2314-B214-008, and NSC 94-2314-B-214-001 from the National Science Council, Taiwan.