Effectiveness of MR angiography for the primary diagnosis of acute pulmonary embolism: clinical outcomes at 3 months and 1 year

Abstract

Purpose: To determine the effectiveness of MR angiography for pulmonary embolism (MRA-PE) in symptomatic patients.

Materials and methods: We retrospectively reviewed all patients whom were evaluated for possible pulmonary embolism (PE) using MRA-PE. A 3-month and 1-year from MRA-PE electronic medical record (EMR) review was performed. Evidence for venous thromboembolism (VTE) (or death from PE) within the year of follow-up was the outcome surrogate for this study.

Results: There were 190 MRA-PE exams performed with 97.4% (185/190) of diagnostic quality. There were 148 patients (120 F: 28 M) that had both a diagnostic MRA-PE exam and 1 complete year of EMR follow-up. There were 167 patients (137 F: 30 M) with 3 months or greater follow-up. We found 83% (139/167) and 81% (120/148) MRA-PE exams negative for PE at 3 months and 1 year, respectively. Positive exams for PE were seen in 14% (23/167). During the 1-year follow-up period, five patients (false negative) were diagnosed with DVT (5/148 = 3.4 %), and one of these patients also experienced a non-life-threatening PE. The negative predictive value (NPV) for MRA-PE was 97% (92-99; 95% CI) at 3 months and 96% (90-98; 95% CI) with 1 year of follow-up.

Conclusion: The NPV of MRA-PE, when used for the primary diagnosis of pulmonary embolism in symptomatic patients, were found to be similar to the published values for CTA-PE. In addition, the technical success rate and safety of MRA-PE were excellent.

Keywords: effectiveness, outcomes analysis; magnetic resonance angiography; negative predictive value; pulmonary embolism.

Figure 1

The spectrum of Pulmonary Embolism found at MRA. a: Coronal MRA of Right Interlobar artery (arrow) with peripheral perfusion abnormality (yellow arrows). b: Left lower lobe segmental embolus (white arrow) with small left pleural effusion (lightning bolt).

Figure 2

A 30-year-old female very dyspniec patient imaged with bilateral PE (white arrows): (a) First injection thick slab axial MIP reformation seen showed breathing artifact and the images are not diagnostic. (b) A repeat injection, performed while the same patient was still on the table, with second full MRA-PE (axial thick slab MIP).