Pulmonary embolism in pregnancy: comparison of pulmonary CT angiography and lung scintigraphy.
OBJECTIVE
The purpose of this study was to retrospectively compare the diagnostic adequacy of lung scintigraphy with that of pulmonary CT angiography (CTA) in the care of pregnant patients with suspected pulmonary embolism.


METHODS
Patient characteristics, radiology report content, additional imaging performed, final diagnosis, and diagnostic adequacy were recorded for pregnant patients consecutively referred for lung scintigraphy or pulmonary CTA according to physician preference. Measurements of pulmonary arterial enhancement were performed on all pulmonary CTA images of pregnant patients. Lung scintigraphy and pulmonary CTA studies deemed inadequate for diagnosis at the time of image acquisition were further assessed, and the cause of diagnostic inadequacy was determined. The relative contribution of the inferior vena cava to the right side of the heart was measured on nondiagnostic CTA images and compared with that on CTA images of age-matched nonpregnant women, who were the controls.


RESULTS
Twenty-eight pulmonary CTA examinations were performed on 25 pregnant patients, and 25 lung scintigraphic studies were performed on 25 pregnant patients. Lung scintigraphy was more frequently adequate for diagnosis than was pulmonary CTA (4% vs 35.7%) (p = 0.0058). Pulmonary CTA had a higher diagnostic inadequacy rate among pregnant than nonpregnant women (35.7% vs 2.1%) (p < 0.001). Transient interruption of contrast material by unopacified blood from the inferior vena cava was identified in eight of 10 nondiagnostic pulmonary CTA studies.


CONCLUSIONS
We found that lung scintigraphy was more reliable than pulmonary CTA in pregnant patients. Transient interruption of contrast material by unopacified blood from the inferior vena cava is a common finding at pulmonary CTA of pregnant patients.
Department of Radiology, St Vincent's University Hospital, Elm Park, Dublin 4, Ireland. caroleridge@hotmail.com
Carole A
CA
Ridge
Shaunagh
S
McDermott
Bridget J
BJ
Freyne
Donal J
DJ
Brennan
Conor D
CD
Collins
Stephen J
SJ
Skehan
D000293:Adolescent; D000328:Adult; D016009:Chi-Square Distribution; D003287:Contrast Media; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007479:Iopamidol; D008875:Middle Aged; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular / Q000000981:diagnostic imaging*; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D013668:Technetium Tc 99m Aggregated Albumin; D014057:Tomography, X-Ray Computed / Q000379:methods*
D003287:Contrast Media; D019275:Radiopharmaceuticals; D013668:Technetium Tc 99m Aggregated Albumin; D007479:Iopamidol