Improved uniformity of aortic enhancement with customized contrast medium injection protocols at CT angiography

PURPOSE: To compare the uniformity of aortoiliac opacification obtained fro m uniphasic contrast medium injections versus individualized biphasic injec tions at computed tomographic (CT) angiography. MATERIALS AND METHODS: Thirty-two patients with an abdominal aortic aneurys m underwent CT angiography. In 16 patients (group 1), 120 mi of contrast ma terial was administered at a flow rate of 4 mL/sec. In the other 16 patient s (group 2) biphasic injection protocols were computed by using mathematic deconvolution of each patient's time-attenuation response to a standardized test injection. Attenuation uniformity was quantified as the "plateau devi ation" of enhancement values, which were calculated as the SD of the time-c ontiguous attenuation values -:observed during the 30-second scanning perio d. RESULTS: Group 2 patients received between 77 and 165 mt (mean, 115 mL) of contrast medium. Initial flow rates ranged from 4.1 to 10.0 mL/sec (mean, 6 .8 mL/sec) for the first 4-6 seconds; continuing flow rates ranged from 2.0 to 4.8 mL/sec, (mean, 3.1 mL/sec) for the remaining 24-26 seconds. The pla teau deviation was significantly mailer in group 2 patients (19 HU) versus group 1 patients (38 HU, P < .001). CONCLUSION: At CT angiography, tailored biphasic injections led to more uni form aortoiliac enhancement, compared with standard uniphasic injections of contrast medium.