Matthias Teufel, Presenter: Nothing to Disclose

Sabrina Koeppe MD, Abstract Co-Author: Nothing to Disclose

Dominik Ketelsen MD, Abstract Co-Author: Nothing to Disclose

Stern Martin, Abstract Co-Author: Nothing to Disclose

Claus Detlef Claussen MD, Abstract Co-Author: Nothing to Disclose

Juergen F. Schaefer MD, Abstract Co-Author: Nothing to Disclose

Proton MRI of lung imaging could replace CT as a reference standard in patients with cystic fibrosis by direct visualisation of changes with very low proton density like air trapping, bullae and emphysema. Up to now, it was possible to visualize these changes by MRI merely with polarised gases or perfusion imaging. An improved MRI technique with ultra short echo time opens new possibilities of proton density imaging of the lung. Aim of this study was to compare both modalities, CT and MRI, by using a non modified Helbich-Bhalla-Score.

During a period of two years, pulmonary MRI was obtained in 85 patients with cystic fibrosis (range 8-29 years, median15 years). 19 patients of these were scheduled for low dose CT examination because of clinical indication (e.g. acute exacerbation). MRI was performed in a 1.5 T scanner using a GE sequence with ultrashort echo time (TE = 0.8 ms, voxel size 1.6x1.6x15 mm3) in in- and exspiration. Additionally, 3D GE sequences with breathhold and TSE sequences with respiration- and ECG-triggering were performed. At the same day, 40-slice MSCT was carried out adapted to bodyweight (100 or 120 KV, 30-60 mAs, 1 and 3 mm slice thickness, smooth and sharp kernel reconstructions) with additional incremental slices (3 positions) in exspiration. The Helbich-Bhalla-Scores was analyzed by two experienced radiologists in consensus for both modalities without knowledge of the clinical data. To avoid recall bias the time interval between CT and MRI evaluation was four weeks. Correlation, mean difference and accordance in each category of the score were calculated.

There was a high correlation between both methods (r = 0.87; P < 0,01). The mean score for CT was 12.2 (range 1-18) and for MRI 11.7 (range 2-19) with a mean difference of 0.5 points. Beside a high correlation for findings with long T2* echo time (i.e. infiltrates) we could also state a qualitative accordance of 95-100% in the categories emphysema, bullae and mosaic perfusion (air trapping).

These results suggest that in our patient group scheduled for CT for clinical indications no relevant findings were missed by MR imaging.

Using ultra short echo time pulmonary MRI offers an excellent radiation free alternative to HRCT by visualization of air trapping, bullae and emphysema without any contrast media.

Teufel, M, Koeppe, S, Ketelsen, D, Martin, S, Claussen, C, Schaefer, J, Role of Pulmonary MRI in Patients with Cystic Fibrosis Using Sequences with Ultrashort Echo Time in Comparison to HRCT.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9011697.html