Diagnosis and management of subsegmental pulmonary embolism.
BACKGROUND
Although the advent of multi-detector row computed tomography (CT) has enabled better visualization of subsegmental pulmonary (SSP) arteries, SSP embolism is of uncertain clinical significance. We aimed at answering the following questions: Is spiral CT an accurate method to detect SSP embolism? How are subsegmental perfusion defects managed in outcome studies including spiral CT? What are the main characteristics and outcomes of patients in whom CT detects isolated subsegmental defects?


METHODS
We performed a Medline search on July 1, 2004, using the keywords 'pulmonary embolism' and 'computed tomography'. We limited our search to English language prospective studies comparing CT to pulmonary angiography, and to prospective outcome studies including CT in a diagnostic strategy, with at least a 3-month follow-up.


RESULTS
Fourteen studies comparing CT to pulmonary angiography, and five prospective management studies using CT were retrieved. The sensitivity of single-detector CT for detecting subsegmental defects compared with pulmonary angiography was low (25%). The proportion of isolated SSP images was significantly higher in management studies using multi-detector CT (17 of 770 scans, 2.2%) compared with those using single-detector CT (22 of 2232, 1.0%; P = 0.01). No straightforward attitude regarding anticoagulation therapy for isolated subsegmental defects emerged from the available literature. Finally, important clinical differences were found between patients having subsegmental and segmental or more proximal defects.


CONCLUSIONS
These findings underline the uncertainty regarding the clinical significance of SSP embolism, and the management of patients with such findings.
Le Gal
G
G
Department of Internal Medicine and Chest Diseases, EA 3878 (Groupe d'Etude de la Thrombose de Bretagne Occidentale), Brest University Hospital, Brest, France. gregoire.legal@chu.brest.fr
Righini
M
M
Parent
F
F
van Strijen
M
M
Couturaud
F
F
D000792:Angiography; D000925:Anticoagulants / Q000494:pharmacology; D006801:Humans; D016239:MEDLINE; D011446:Prospective Studies; D011655:Pulmonary Embolism / Q000175:diagnosis* / Q000628:therapy*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013997:Time Factors; D036542:Tomography, Spiral Computed / Q000379:methods; D016896:Treatment Outcome
D000925:Anticoagulants