A recent study published in Chest evaluated the sequence of clinical scoring, D-dimer testing, compression ultrasonography, V/Q scanning and CT (MDCT) in that order for the diagnosis and rule-out of PE. CT was only needed in 11% of the patients:
Results: Detection of DVT by ultrasonography established the diagnosis of PE in 43 (13%). Lung scan associated with clinical probability was diagnostic in 243 (76%) of the remaining patients. MDCT scan was required in only 35 (11%) of the patients. The 3-month thromboembolic risk in patients not given anticoagulants, based on the results of the diagnostic protocol, was 0.53% (95% CI, 0.09-2.94).
Conclusions: A diagnostic strategy combining clinical assessment, d-dimer, ultrasonography, and lung scan gave a noninvasive diagnosis in the majority of outpatients with suspected PE and appeared to be safe.
A related editorial was titled Retro Is the Rage!: Ventilation-Perfusion Scanning Is Alive and Well in the Diagnosis of Pulmonary Embolism.
Well, I'm going to savor this moment for a little self aggrandizement. I told you so. I've been hammering this point for the last six years on this blog. The evidence has never favored CT over V/Q for PE. Minimizing the use of CT in the evaluation of patients for PE will save costs, radiation risk and kidneys.