[A new method for imaging ventilation-distribution with 3Helium in magnetic resonance tomography].
BACKGROUND
Conventional 1H-MRI of the lung is restricted by susceptibility effects and low proton density: Recently, imaging of lung ventilation in MRI has become feasible using hyperpolarised inert gases with a spin of I = 1/2, such as 3He and 129Xe, as inhalative "contrast agents". New technical developments, preclinical and clinical application of this method are described.


METHODS
With optical laser pumping high polarisation rates can be achieved, resulting in a high signal-to-noise ratio (S/N). A dedicated application system allows accurate administration of 3He boli at different time points during inspiration. Thus, dynamic ventilation imaging becomes possible. Prerequisites for this method include a dedicated coil as well as a spectroscopy option at the MRI system. Fast sequences and low flip angles are employed to comply with the relaxation of hyperpolarise 3He in vivo.


RESULTS
Overall homogeneous signal intensity (SI) represents physiological conditions. Obstructive lung disease is associated with generalised or localised signal inhomogeneity. Different time constants of specific lung regions are probably responsible for this kind of inhomogeneous inspiratory distribution of ventilation. Tumours show a clear ventilation deficit, correlating with non-ventilated lung areas.


CONCLUSIONS
3He MRI is a promising new modality for the evaluation of ventilation distribution under different pathological conditions. This may include obstructive lung disease and assessment of ventilation distribution before and after thoracic surgery. Furthermore, evaluation of patients with acute lung failure and validation of ventilator settings in anaesthesia may be performed.
Markstaller
K
K
Klinik für Radiologie, Johannes Gutenberg-Universität, Mainz.
Kauczor
H U
HU
Weiler
N
N
Eberle
B
B
Surkau
R
R
Kienast
K
K
Otten
E W
EW
Thelen
M
M
D003287:Contrast Media; D006371:Helium; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation; D007554:Isotopes; D008171:Lung Diseases / Q000175:diagnosis / Q000503:physiopathology; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D014692:Ventilation-Perfusion Ratio / Q000502:physiology*
D003287:Contrast Media; D007554:Isotopes; D006371:Helium
Neue Methode zur Darstellung der Verteilung der Ventilation mittels polarisiertem 3Helium in der Magnetresonanztomographie (MRT).