OPTIMIZATION OF THORACIC SPIRAL CT - EFFECTS OF IODINATED CONTRAST-MEDIUM CONCENTRATION

PURPOSE: To determine the effect of varying iodine concentration on ar terial enhancement and perivenous artifact during thoracic spiral comp uted tomographic (CT) scanning. MATERIALS AND METHODS: One hundred thi rty-eight outpatients received 15.0 g (n = 76) or 22.5 g (n = 62) of i odine (300 mg/mL iodine) while undergoing thoracic spiral CT. Patients received either undiluted contrast medium, 1:1 normal saline dilution , or 3:1 normal saline dilution. Contrast medium was injected at a flo w rate determined to deliver the entire iodine dose within 40 seconds. Attenuation was measured within arteries and veins. Three blinded tho racic radiologists independently graded perivenous artifact and arteri al enhancement. RESULTS: Perivenous artifacts were statistically signi ficantly reduced with successive iodine dilution (P < .002). Arterial enhancement was statistically significantly better with 15.0 g of iodi ne diluted 1:1 when compared with the same iodine dose undiluted or di luted 3:1 (P < .01). Arterial enhancement achieved with 15.0 g of iodi ne diluted 1:1 was not statistically significantly lower than that ach ieved with 22.5 g of iodine diluted 1:1 (P > .31); however, venous art ifact was greater with 22.5 g of iodine (P < .004). CONCLUSION: Reduce d iodine concentration appears to diminish perivenous artifact and to result in improved arterial enhancement during thoracic spiral CT.