Sanjeev Bhalla MD, Presenter: Nothing to Disclose

Christine O. Menias MD, Abstract Co-Author: Nothing to Disclose

Alison Cahill MD, Abstract Co-Author: Nothing to Disclose

V/Q provides a lower maternal radiation dose for embolic imaging and does not require iodinated contrast which can cross the placenta, yet many fear that a majority will be nondiagnostic. Our purpose was to determine the performance characteristics of V/Q scans versus multidetector CT in the evaluation of pulmonary embolism in the pregnant patient.

After IRB approval, the Radiology information system was searched for all pregnant patients in whom either a V/Q or helical CT for pulmonary embolism was performed (from 2000-2007). All reports were reviewed by a thoracic radiologist, who also reviewed the studies to verify the initial interpretation. Presenting chest radiographs were also reviewed. Clinical followup was also performed.

166 patients were identified: 142 V/Q scans and 35 PE protocol MDCTs. 9 patients had both V/Q scans and CT examinations. In the V/Q group 60 studies (42%) were normal, 68 (48%)were low-likelihood, 9 (6%)were intermediate and 5 (4%)were high-likelihood. Of the 9 intermediate studies, 8 went on to CT of which only 1 was positive. Of these 9 intermediate studies, 5 had initial abnormal chest radiographs. In the CT group, 4 were read as positive (only 2 were positive in review), and 31 were negative (33 in review). In the negative group, 10 (29%)had other explanations for the clinical symptoms of shortness of breath (edema, pneumonia)and 11 (31%)had caveats to the interpretation (limited [2]; moderately limited [9]).

In pregnant patients, a minority of V/Q scans will be intermediate whereby a significant number of CTs will be limited. This is likely funstion of the altered hemodynamics in the setting of normal perfusion and ventilation.

The V/Q scan is diagnostic in many pregnant patients. The chest radiograph can be used as a triage tool in embolism imaging: normal radiographs should prompt V/Q while abnormal ones should lead to CT.

Bhalla, S, Menias, C, Cahill, A, Imaging of PE in the Pregnant Patient: Is V/Q More Robust than CT?.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5011381.html