Diagnosis of Pulmonary
Embolism with Magnetic Resonance Angiography
Jonathan Segal
8/15/97
Key Clinical Points
- MRA of the pulmonary arteries, as compared to
conventional pulmonary angiography, had a high
sensitivity ( 100%) and specificity (95%) for diagnosis
of pulmonary embolism.
- With a +LR of 22 and a -LR of 0, MRA may prove to offer a
non-invasive method for diagnosing PE without exposing
patients toiodinated contrast, but a randomized
controlled trial is needed.
- MRA is limited by the need for patients to hold their
breath for 27 seconds to avoid motion artifact.
Evidence
- 30 patients with suspected PE undergoing both angiography
& MRA
| |
Patients |
Vascular Segments |
| |
PE+ |
PE- |
PE+ |
PE- |
| MRA+ |
8 |
1 |
2 |
4 |
| MRA- |
0 |
21 |
1 |
665 |
| Totals |
8 |
22 |
22 |
669 |
| MRA |
Sensitivity |
Specificity |
PPV |
NPV |
+LR |
-LR |
| Patients |
100 |
95 |
87 |
100 |
22 |
0 |
| Vasc.Seg. |
95 |
99 |
84 |
99 |
160 |
.04 |
Comments
- The power of the study is limited by the small sample
size.
- The characteristics of the patient population are not
well described in terms of the clinical suspicion for PE
- 10% (3 of 30) of patients had multiple vascular segments
that were unable to be visualized secondary to motion
artifact.
- Interobserver correlation was good and 2 of 3
interpreters had only one year of experience with MRA of
the pulmonary vasculature.
Reference:
Meaney JFM, Weg JG, Chenevert TL, et al. Diagnosis of pulmonary
embolism with magnetic resonance angiography. NEJM.1997
May 15; 336:1422-7.