Kyongtae Tyler Bae MD, PhD, Abstract Co-Author: Nothing to Disclose

Cheng Tao, Presenter: Nothing to Disclose

Cheng Hong MD, PhD, Abstract Co-Author: Nothing to Disclose

Fang Zhu MD, PhD, Abstract Co-Author: Nothing to Disclose

Margherita Milite, Abstract Co-Author: Nothing to Disclose

Charles Floyd Hildebolt DDS, PhD, Abstract Co-Author: Nothing to Disclose

A patient’s body weight and the amount of contrast medium are closely related to the degree of contrast enhancement. Unlike in the liver and aorta, however, this relationship has been rarely studied in pulmonary CT angiography (CTA), in part because this application is relatively new with multi-detector row CT (MDCT). The purpose of this study is to evaluate the amounts of contrast medium required for pulmonary CTA to achieve different degrees of contrast enhancement for a given patient body weight.

We retrospectively studied fifty-four consecutive patients (mean age, 59 years; 27 men) who underwent standard pulmonary embolism chest CT examinations with 16- and 64-MDCT. Contrast medium (350 mgI/mL) was injected at a rate of 4 mL/sec. The volume of injected contrast medium equals the product of the injection rate and the sum of scan delay and scan duration, up to the maximum volume of 125 mL. The scan delay was determined with a bolus tracking method in which a region of interest was placed on the main pulmonary artery and the diagnostic CT scan was triggered at the contrast enhancement threshold of 100 HU for 16-MDCT and 150 HU for 64-MDCT. Scan delays and durations were recorded. Contrast enhancement attenuation was measured craniocaudally every second in the main pulmonary artery and the right ventricle. For each patient, injected contrast volume per body weight index (CVBWI, mL/kg) was calculated. Regression analysis was performed between CVBWI and time-averaged contrast enhancement.

A wide range of body weights (46.4-153 kg) and contrast volumes (58-125 mL) were observed. Moderate correlation (r=0.39, P=0.004) was observed between CVBWI and time-averaged contrast enhancement in the pulmonary artery/right ventricle. The regression model [206 HU + (93 x CVBWI) HU] indicates that 1.0, 1.5, and 2.0 mL/kg of 350 mgI/mL contrast medium is required to achieve 299, 345, and 392 HU of attenuation in the pulmonary artery, respectively.

To achieve a consistent contrast enhancement on pulmonary CTA, the amount of required contrast medium volume should be adjusted to the patient’s body-weight: approximately 1.0 mL/kg contrast medium to yield 300 HU attenuation.

M.M.: Margherita Milite is an employee of Siemens Medical System

Bae, K, Tao, C, Hong, C, Zhu, F, Milite, M, Hildebolt, C, Degree of Contrast Enhancement in Pulmonary CTA with MDCT: Association with Body Weight and Volume of Contrast Medium.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4411443.html