CT Pulmonary Angiogram Quality Comparison Between Early and Later Pregnancy

Purpose: Pregnancy increases the risk for thromboembolic disease. CT pulmonary angiogram (CTPA) is widely used for the diagnosis of pulmonary embolus (PE); however, a significant number of scans are suboptimal or non-diagnostic in pregnant patients. This phenomenon is attributed to physiology during the gravid state. The aim of this study is to examine whether all stages of pregnancy are similarly at risk for suboptimal scans.

Methods: Pregnant patients who had CTPA scans between February 2008 and November 2014 were included. The attenuation in the major pulmonary arteries was compared among patients and controls. An attenuation of 200 Hounsfield units (HU) was used as a cutoff between adequate and suboptimal studies. Statistical analysis compared attenuation means and number of arteries with adequate versus suboptimal attenuation.

Results: Forty patients were included in the study. Nine were at or below 13 weeks of pregnancy and 31 between week 14 and term. A control group of 14 non-pregnant women of similar age were also included. All arteries showed a significantly higher attenuation in early pregnancy and in the control group compared to later in pregnancy, p < 0.05. Fewer suboptimal opacified arteries were found in early pregnancy (11.1%) and controls (5.7%) compared to later in pregnancy (33.3%), p < 0.01.

Conclusion: Patients in early pregnancy are more likely to have a technically successful CTPA scan compared to later in pregnancy and show similar opacification to non-pregnant women. This suggests a possible paradigm shift from the current approach to suspected PE in pregnant patients.