Assessment of pulmonary perfusion with breath-hold and free-breathing dynamic contrast-enhanced magnetic resonance imaging: quantification and reproducibility

Abstract Objectives: The purpose of this study was to investigate whether quantification of pulmonary perfusion from dynamic contrast-enhanced (DCE) MRI yields more reproducible results with data acquired during free breathing than with data from conventional breath-hold measurements. Material and Methods: 10 healthy male volunteers underwent two imaging sessions at a clinical 1.5T-MRI system, separated by a week ± one day. Each of these sessions comprised two DCE MRI acquisitions, one performed during breath-hold, and one during free, shallow breathing; both acquisitions were separated by at least 20 minutes. For all DCE MRI measurements, a standard dose of Gadobutrol was used. Breath hold measurements lasted 53 seconds; free-breathing acquisitions were performed in a total acquisition time of 146 seconds. Lung tissue was segmented automatically to minimize user influence and pulmonary plasma flow (PPF) and volume (PPV) were quantified on a perpixel basis with a one-compartment model. Freebreathing measurements were analyzed twice, (a) including data from the entire acquisition duration and (b) after truncation to the duration of the breath-hold measurements. For further statistical analysis, median values of the resulting parameter maps were determined. To assess intra-individual reproducibility, intra-class correlation coefficients and coefficients of variation between first and second measurements were calculated for breathhold, truncated and full free-breathing measurements, respectively. Differences in the coefficients of variation were assessed with a non-parametric two-sided paired Wilcoxon signed-rank test. Results: All 40 measurements were completed successfully. Maps of PPF and PPV could be calculated from both measurement techniques; PPF and PPV in the breath-hold measurements were significantly lower (p<0.001) than in truncated and full free-breathing measurements. Both evaluations of the free-breathing measurements yielded higher intra-class correlation coefficients and lower coefficients of variation between first and second measurements than in the breath-hold measurements. Conclusions: Besides offering substantially higher patient comfort, free-breathing DCE MRI acquisitions allow for pixel-wise quantification of pulmonary perfusion and hence generation of parameter maps. Moreover, quantitative perfusion estimates derived from free-breathing DCE MRI measurements have better reproducibility than estimates from the conventionally used breath-hold measurements