Effect of Contrast Prewarming on Vascular Enhancement at Cardiac CTA-An Observational Study.

Objective: We hypothesize that contrast warming, which reduces the viscosity of iodinated contrast media, is associated with fewer pressure-limited injections and greater arterial enhancement in the left ventricle, aortic root, left coronary artery, and right coronary artery, which would reflect improved image quality.

Methods: We conducted a retrospective review of cardiac CTA studies performed with iohexol 350 mg/mL solution either prewarmed to body temperature (37 °C, N=591) or at room temperature (24 °C, N=59). χ2 test was used to compare the rate of pressure-limited injections (pressure limit 325 psi) between prewarmed and nonwarmed studies. Hounsfield unit (HU) attenuation was measured from regions of interest in the left ventricle, aortic root, left coronary artery, and right coronary artery. The Mann-Whitney U test was used to compare enhancement between prewarmed and nonwarmed exams. Linear regression was used to further examine the enhancement between contrast groups.

Results: Cardiac CTA studies using prewarmed contrast had a significantly lower rate of pressure-limited injections (22/591 vs. 42/59, χ21=275.1; P<0.001). Prewarmed contrast resulted in significantly greater enhancement on cardiac CTA in the left ventricle (488 vs. 400 HU; P<0.001), aortic root (494 vs. 400 HU; P<0.001), left coronary artery (467 vs. 387 HU; P<0.001), and right coronary artery (449 vs. 377 HU; P<0.001). With linear regression, prewarmed contrast use was associated with greater enhancement in the left ventricle (R2=0.220, F7, 602=24.211, P<0.001), aortic root (R2=0.228, F7, 602=25.467, P<0.001), left coronary artery (R2=0.216, F8, 587=20.274, P<0.001), and right coronary artery (R2=0.221, F8, 571=20.302, P<0.001).

Conclusions: The results support our hypothesis that prewarming of iodinated contrast media to body temperature results in fewer pressure-limited injections and improved vascular enhancement.