Pulmonary MR angiography at 1.0 T: early results with k-space segmented and post-contrast TurboFLASH two-dimensional time-of-flight sequences.

PURPOSE

To evaluate the combined performance of two time-of-flight methods in imaging the pulmonary arteries.

MATERIALS AND METHODS

This study was prospectively conducted in 28 patients suspected for pulmonary embolism (PE). Sixteen patients were free of pulmonary vascular disease, and 12 had pulmonary vascular disease as demonstrated by pulmonary angiography. To reduce artifacts caused by cardiac and respiratory motion, MR images were acquired in all subjects using bi-dimensional (2D), gradient-recalled echo (GRE), breath-hold techniques. Sagittal thin (6-mm) sections obtained with ECG gating, k-space segmentation and incremented flip-angles (TONE), and coronal thick (15-mm) sections obtained after a unique injection of Gadolinium chelate were used.

RESULTS

High quality images were obtained in all 16 (100%) subjects free of pulmonary disease with both techniques, and in 10 and 12 (87% and 100%) patients suspected for pulmonary artery disease with sagittal and coronal Gd-enhanced MRA, respectively. In patients free of pulmonary disease, TONE images exhibited distal pulmonary arteries with 2.1 subsegmental divisions on average, whereas Gd-enhanced TurboFLASH images were the most accurate to identify proximal pulmonary arteries within the mediastinum, even if only 0.8 subsegmental divisions were seen on average. A correct diagnosis of pulmonary embolism was obtained in all cases but one, with use of both MRA techniques, with an overall accuracy of 86%.

CONCLUSION

The association of segmented sagittal GRE images and coronal first-pass Gd-enhanced GRE images can provide information upon normal and diseased pulmonary arteries within the mediastinum until subsegmental pulmonary branches, even in patients with short-breathing. Further studies of patients with various pulmonary artery diseases will confirm whether this technique makes pulmonary MRA feasible in clinical routine situations.