Using thoracic helical CT to assess iodine concentration in a small volume of nonionic contrast medium during vascular opacification: a prospective study.

OBJECTIVE. The goal of the study was to assess whether, using thoracic helical CT, diagnostic mediastinal and hilar vascular enhancement can be obtained with a small amount of nonionic contrast material (80 ml) injected at a relatively slow rate (2 ml/sec).SUBJECTS AND METHODS. One hundred twenty patients (60 in their fourth decade malignancies of life and 60 in their seventh decade of life) referred for contrast-enhanced thoracic CT for malignancies or infections prospectively entered the study. They were randomly assigned to be given one of three iodine concentrations of a nonionic contrast material: 250 mg/ml (I250), 300 mg/ml (I300), and 350 mg/ml (I350). Two radiologists independently graded perivenous artifacts and arterial enhancement of mediastinal and hilar vessels on a 4-point scale: 1, poor; 2, fair; 3, good; and 4, excellent. Measurements of arterial attenuation values (quantitative assessment) were obtained on the aorta and pulmonary artery.RESULTS. Mean scores were equal to or greater than 3...