Parveen Sunner MD, Presenter: Nothing to Disclose

Jonathan Thomas Abele MD, Abstract Co-Author: Nothing to Disclose

Based on the high sensitivity, equivalent fetal radiation risk, lower breast radiation dose and reduced risk of anaphylaxis and nephrotoxicity, we proposed that a low-dose perfusion only scan be offered to all pregnant patients with a clinical suspicion for pulmonary embolism (PE) and a normal chest radiograph. Our goal was to establish that perfusion scintigraphy provides a high number of diagnostic studies and can be used to triage patients requiring more specific CT pulmonary angiography (CTPA) assessment.

A retrospective analysis of a multi-site diagnostic imaging protocol used in the assessment of clinically suspected pulmonary embolism in pregnancy (Sep 2009 to Feb 2011) was performed. This protocol incorporated low-dose perfusion scanning as the initial imaging study in patients with a normal chest radiograph (Figure 1). The percentage of patients requiring a low-dose perfusion scan only was compared with those requiring both a low-dose perfusion study and a CT scan for diagnosis.

Data from 83 patients was collected. Nine (9) cases (11%) were excluded from the analysis as they did not follow the recommended imaging algorithm. Seventy-four (74) patients (89%) were evaluated according to the algorithm ranging in gestational age from 11 – 37 weeks. Sixty-one (61) patients (82%) had normal perfusion studies and required no further imaging. Thirteen (13) patients (18%) were further assessed with CTPA. One patient was diagnosed with PE.  Eight (8) patients had a normal CTPA.  Three (3) patients demonstrated alternative causes for abnormal perfusion including bronchiectasis, bronchopneumonia and atelectasis.

PE was excluded in 82% of women with a normal chest radiograph and low-dose perfusion scan. Only a minority (13%) of patients required an additional CTPA for further evaluation. By using a diagnostic imaging algorithm involving an initial low-dose perfusion scan in patients with a normal chest radiograph, only a minority (13%) of patients will be exposed to the increased risks associated with CT including increased breast radiation and risks of IV contrast.

Pulmonary embolism is a major cause of mortality during pregnancy with unique diagnostic considerations and significant treatment implications. An optimal diagnostic imaging workup is desired.

Sunner, P, Abele, J, Assessment of a Multisite Diagnostic Imaging Algorithm Incorporating Low-Dose Perfusion Scanning for Clinically Suspected Pulmonary Embolism in Pregnant Patients.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11004300.html