Performance of Helical Computed Tomography in Unselected Outpatients with Suspected Pulmonary Embolism

Abstract

Helical CT should not be used alone for suspected pulmonary embolism but could replace angiography in combined strategies that include ultrasonography and lung scanning.

Impact of reliance on CT pulmonary angiography on diagnosis of pulmonary embolism: A Bayesian analysis

“…24 Thus, many emboli found in patients with low pretest probability actually may have been subsegmental PE that would not have been diagnosed by another radiologist. As CTPA is more accurate for diagnosing central PE, 25 clinicians should consider reviewing "positive" scans with the interpreting radiologist, especially when the pretest probability was low and the filling defects identified are in distal vessels.…”

Faut-il traiter les embolies pulmonaires sous-segmentaires ?

“…Pourtant, la sensibilité du scanner monobarrette est imparfaite, avec jusqu'à 21 % de faux négatifs rapportés [17]. La sensibilité est particulièrement faible pour la détection d'embolies au niveau des artères segmentaires et sous-segmentaires [18,19].…”

Pulmonary embolism: an unsuspected killer

“…Interpreting the study without factoring in the pretest probability would lead to overdiagnosis and underdiagnosis of PE: Of patients who have a high-probability V/Q scan but a low pretest probability, 44% would have angiograms negative for PE, whereas in patients with a low-probability scan but a high pretest probability, 40% would be found to have PE on angiogram (see Table 3) [13,96]. Because of these interpretive factors and because patients with preexisting lung disease often have abnormal studies, V/Q scan provides a definitive answer regarding whether or not a patient should be started on anticoagulation therapy in only 25% to 40% of cases [12].…”

“…Many investigators have questioned whether the sensitivity of CT is sufficient to rule out definitively the possibility of PE [97]. Perrier et al [12] found the sensitivity and specificity to be only 70% and 91%, whereas others have reported sensitivities of 88% to 100% with negative predictive values of 89% to 95% [98][99][100].…”

“…Prior autopsy studies consistently have shown the rate to be even higher, at approximately 70% [7][8][9][10][11]. Conversely, in patients in whom the diagnosis is considered, the prevalence of PE is only 25% to 35% [12,13]. Therefore, clinicians generally miss PE when it is present and suspect it when it is not.…”