Incidental pulmonary embolism is often missed on multislice CT, but patients may not fare any worse for the oversight, a German researcher said during a session Monday at the ECR.

Patients with incidental and therefore untreated PE actually have a more favorable short-term clinical outcome than those who receive treatment, according to a retrospective study conducted at the University of Munich. The research calls into question the value of detecting minor pulmonary embolism on MSCT of the chest.

Researchers examined 2535 consecutive chest MSCT scans in 1966 patients and examined clinical outcomes in the short term (after 30 days) and long term (after one year). They recorded coexisting morbidity, treatment with anticoagulant therapy (ACT), and complications. Results were presented by Dr. Christophe Engelke, a consultant radiologist at the university.

Through independent review of images by radiologists, researchers also identified true positives and false negatives on the original CT scan. Patient notes were reviewed for unsuspected PE. Three radiologist reviewers were required to reach consensus on the image findings.

Out of the study group, 117 (6.6%) were identified as PE positive and file review was completed in 96 of these cases. Of these 96 cases, 63 had active malignancy (77%) and 58 (68%) had unsuspected PE.

PE severity differed significantly between patients who were true positive and those who had a false negative on the CT report, said Engelke. The most severe cases were detected while the minor cases were more likely to be missed.

Of the patients determined to have PE, 49% received anticoagulant therapy. Therapy was not administered in some of the other cases due to contraindications.

Bleeding complications related to the anticoagulant therapy affected seven patients, and included two fatal cases and five major nonfatal hemorrhage cases.

Patients with unsuspected PE and a false negative CT actually had a better survival rate after 30 days than those who were appropriately treated, Engelke said. This was due to bleeding complications and severity of PE, which was an important predictor of survival. Patients with massive PE had a worse outcome in the short term.

Long-term survival was affected mainly by the presence of comorbidity, rather than PE, Engelke said.