Klaus Kurt Gast MD, Presenter: Nothing to Disclose

Christa Gast, Abstract Co-Author: Nothing to Disclose

Andreas Morbach MS, Abstract Co-Author: Nothing to Disclose

Anja Dahmen, Abstract Co-Author: Nothing to Disclose

Hans-Ulrich Kauczor MD, Abstract Co-Author: Nothing to Disclose

Trine Stavngaard, Abstract Co-Author: Nothing to Disclose

Joerg Schmiedeskamp, Abstract Co-Author: Nothing to Disclose

Alexander Biedermann MD, Abstract Co-Author: Nothing to Disclose

Christoph Dueber MD, Abstract Co-Author: Nothing to Disclose

Wolfgang Guenther Schreiber PhD, Abstract Co-Author: Nothing to Disclose

Edwin J. R. Van Beek MD, PhD, Abstract Co-Author: Nothing to Disclose

Claus Peter Heussel MD, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

HRCT and ³He-MRI both provide high spatial resolution. A direct local comparison is of interest because of the inhomogeneity of pulmonary diseases. A region-of interest-based (ROI) correlation of regional mean lung density (MLDR) in HRCT and the regional apparent diffusion coefficient (ADCR) in ³He-MRI was performed for better understanding of the diagnostic and prognostic possibilities of diffusion weighted ³He-MRI.

A retrospective analysis of 68 subjects enrolled in the multicenter study “Polarized Helium to Image the Lung” included 23 healthy subjects, 38 patients suffering from chronic obstructive pulmonary disease (COPD) and 7 patients with pulmonary emphysema due to alpha-1-antitrypsin deficiency (a1AD). The gas was polarized to approximately 55% at the Institute of Physics at the central institution. HRCT and ³He-MRI were compared using 18 ROIs in 3 transverse levels (carina, 3cm above and 5cm below) in anatomically matching regions. At ³He-MRI, ROIs with a SNR in the of less than 2,1 were excluded. Subsequently, ADCR and MLDR and Pearson correlation coefficients were calculated.

MLDR was -902 HU (min/max, -962/-728 HU) in the healthy group, -911 HU (-983/-599 HU) in COPD patients and -933 HU (-969/-812 HU) in patients with a1AD. Mean ADCR measured in patients was higher in COPD (0,28 cm²/s, min/max 0,13/0,73 cm²/s) and a1AD (0,33 cm²/s, 0,15/0,73cm²/s) than in the healthy population (0,18 cm²/s, 0,11/0,37cm²/s). The individual regional results showed a low linear correlation between HRCT and ³He-MRI: r=0.23 in the whole study population; r=0.48 in healthy participants; R=0,24 in COPD; R=0,71 in patients with a1AD.

Regional evaluation of ADCR and MLDR in anatomically matched ROIs shows a clear difference between two groups of patients with emphysema and healthy subjects. The individual correlation of these parameters is low for the COPD-patients and the healthy group and moderate for a1AD-patients.

CT and diffusion weighted ³He-MRI obviously measure different phenomena of disease, suggesting that MRI assesses functional changes whereas HRCT evaluates lung morphology.

Gast, K, Gast, C, Morbach, A, Dahmen, A, Kauczor, H, Stavngaard, T, Schmiedeskamp, J, Biedermann, A, Dueber, C, Schreiber, W, Van Beek, E, Heussel, C, et al, , Diffusion-weighted ³He-MR in Pulmonary Emphysema: A Regional Comparison with HRCT.  Radiological Society of North America 2006 Scientific Assembly and Annual Meeting, November 26 - December 1, 2006 ,Chicago IL. http://archive.rsna.org/2006/4428645.html