The use of ECG and respiratory triggering to improve the sensitivity of oxygen-enhanced proton MRI of lung ventilation.
Changes in lung signal between normal breathing and breathing pure oxygen is the basis for oxygen-enhanced ventilation MRI. An optimal technique guarantees a significant response to pure oxygen in well-ventilated lung tissue. To improve the sensitivity, we investigated the effect of ECG and respiratory triggering. Centric reordered single-shot rapid acquisition relaxation enhancement sequences (TE 4.2 ms, echo spacing 4.2 ms, bandwidth 650 Hz/pixel), with an inversion recovery preparation pulse (TI 700 ms), were used. Series of 20 measurements were performed with and without ECG and respiratory triggering in five young volunteers. Subsequently, series of 100 images were acquired during breathing normal air and pure oxygen (as "stimulus"). Ventilation maps showed by means of the z-score how far the response deviates from the signal intensities during the normal air condition. The standard deviation of the lung signal intensities was lowest for the cardiac-triggered series. In the ventilation maps, on the other hand, signal changes were statistically more significant in the respiratory than in the cardiac-triggered series. The average z-scores in the right (left) cranial part of the lung were 12.4 (13.0) and 9.2 (9.7) for respiratory and ECG-triggered acquisitions. We propose to use respiratory triggering as a means to improve the sensitivity of MR ventilation studies.
Vaninbroukx
Johan
J
Department of Radiology, University Hospitals, KU Leuven, Herestraat 49, 3000 Leuven, Belgium.
Bosmans
Hilde
H
Sunaert
Stefan
S
Demedts
Maurits
M
Delcroix
Marion
M
Marchal
Guy
G
Verschakelen
Johny
J
D000328:Adult; D004562:Electrocardiography; D006801:Humans; D008168:Lung / Q000033:anatomy & histology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D010100:Oxygen; D012123:Pulmonary Ventilation; D012119:Respiration; D012680:Sensitivity and Specificity
D010100:Oxygen