Determination of lowest possible contrast volume in computed tomography pulmonary angiography by using pulmonary transit time.

Purpose: The aim of this study was to assess the effectiveness of the modified test-bolus (mTB) method in computed tomography pulmonary angiography (CTPA).

Materials And Methods: The Institutional Review Board approved this retrospective study. We reviewed 24 patients (nine men, 15 women; age range, 21-88 years) in whom CTPA was performed either by Bolus-Tracking (BT) (n = 12) or mTB (n = 12) methods. Pulmonary transit time (PTT) was used to determine scan delay time and contrast volume in the mTB group. The contrast volume, radiation dose, quantitative measures, and qualitative scores of enhancement were compared. The chi-squared test, Mann-Whitney U test, and κ statistics were used. The significance level was 0.05.

Results: The effective dose (P = 0.028) and contrast volume (P < 0.001) was significantly lower in the mTB group than those in the BT group. The difference in the quantitative measures and qualitative scores of enhancement between groups was statistically insignificant (P = 0.729, P = 0.635, respectively). Significantly fewer artefacts were observed in the mTB group (P = 0.024).

Conclusion: By taking into account PTT, mTB appears to be a promising method for tailoring CTPA to the patient with the use of less contrast material and resulting in fewer artifacts.