Quantitative and Qualitative Assessment of Pulmonary Emphysema with T2-Weighted PROPELLER MRI in a High-Risk Population Compared to Low-Dose CT

Abstract

Purpose To determine the suitability of T2-weighted PROPELLER MRI for the assessment of pulmonary emphysema.

Materials and Methods 60 participants in a lung cancer screening program (30 subjects with pulmonary emphysema, and 30 control subjects without emphysema) were included for this retrospective study. All subjects were examined with low-dose CT (LDCT) and MRI within the screening program. The use of a T2-weighted PROPELLER sequence for the assessment of emphysema was analyzed and correlated with the results of LDCT. The presence and the extent of pulmonary emphysema were first assessed qualitatively using a three-point score, and then quantitatively with a semi-automated software program to obtain emphysema indices.

Results All 30 cases with pulmonary emphysema were accurately detected by MRI. There were 3 cases with emphysema according to MRI without emphysematous changes on LDCT (false-positive results). The qualitative scores as well as the emphysema indices were significantly higher in the emphysema group compared to the control group for MRI and LDCT (p < 0.001). Both the scores and the indices correlated significantly between MRI and LDCT (qualitative score of severity: r = 0.912/p < 0.001 in the emphysema group and r = 0.668/p < 0.001 in the control group; emphysema index: r = 0.960/p < 0.001 in the emphysema group and r = 0.746/p < 0.001 in the control group).

Conclusion The presence and the extent of pulmonary emphysema may be assessed qualitatively and quantitatively by T2-weighted PROPELLER MRI with very good correlation to LDCT.

Key Points: 

• T2-weighted PROPELLER MRI may be suitable for the assessment of pulmonary emphysema.

• There was significant correlation between MRI and LDCT regarding qualitative scores and quantitative emphysema indices in our study with correlation coefficients for different subgroups ranging from r = 0.668 to r = 0.960.

• T2-weighted PROPELLER MRI may have the potential to be used for follow-up examinations in patients with severe emphysema to avoid radiation exposure of repeated CTs.

Citation Format

• Meier-Schroers M, Sprinkart AM, Becker M et al. Quantitative and Qualitative Assessment of Pulmonary Emphysema with T2-Weighted PROPELLER MRI in a High-Risk Population Compared to Low-Dose CT. Fortschr Röntgenstr 2018; 190: 733 – 739

Zusammenfassung

Ziel Evaluation der Eignung der T2-gewichteten PROPELLER-MRT für die Bewertung von Lungenemphysemen.

Material und Methoden Es wurden 60 Teilnehmer eines Lungenkrebsscreenings (30 mit und 30 ohne Lungenemphysem) in diese retrospektive Studie eingeschlossen. Im Rahmen des Screenings wurden alle Studienpatienten mittels Niedrigdosis-CT (NDCT) und MRT untersucht. Für diese Studie wurde analysiert, ob eine T2-gewichtete PROPELLER-Sequenz für die Bewertung von Lungenemphysemen eingesetzt werden kann. Die Ergebnisse der MRT wurden mit denen der NDCT verglichen. Das Vorliegen und die Ausprägung eines Lungenemphysems wurden zunächst qualitativ mit einem 3-Punkte-Score bewertet. Danach wurden Emphysem-Indices mit Hilfe einer halbautomatischen Software quantitativ bestimmt.

Ergebnisse Das Vorliegen eines Lungenemphysems wurde in allen 30 Fällen korrekt von der MRT erkannt. Es gab 3 Fälle mit einem Emphysem laut MRT, die keine emphysematösen Veränderungen in der NDCT aufwiesen (falsch-positive Ergebnisse). Die Emphysem-Scores und die Emphysem-Indices waren sowohl in der NDCT als auch in der MRT signifikant höher in der Emphysemgruppe als in der Kontrollgruppe (p < 0,001). Es gab eine signifikante Korrelation der Scores und der Indices zwischen der MRT und der NDCT (Scores der Emphysemausprägung: r = 0,912/p < 0,001 in der Emphysemgruppe und r = 0,668/p < 0,001 in der Kontrollgruppe; Emphysemindices: r = 0,960/p < 0,001 in der Emphysemgruppe und r = 0,746/p < 0,001 in der Kontrollgruppe).

Schlussfolgerung Es ist denkbar, dass das Vorliegen und die Ausprägung von Lungenemphysemen qualitativ und quantitativ mittels T2-gewichteter PROPELLER-MRT bewertet werden können, mit sehr guten Korrelationen zur NDCT.

Kernaussagen: 

• Die T2-gewichtete PROPELLER-MRT könnte sich für die Bewertung von Lungenemphysemen eignen.

• Es zeigten sich signifikante Korrelationen zwischen der MRT und der NDCT bezüglich der qualitativen Scores und bezüglich der quantitativen Emphysem-Indices in unserer Studie mit Korrelationskoeffizienten von r = 0,668 bis r = 0,960 bei verschiedenen Subgruppen.

• Die T2-gewichtete PROPELLER-MRT könnte sich für Verlaufskontrollen bei Patienten mit schwerwiegendem Emphysem eignen, um die Strahlenbelastung durch wiederholte CTs zu vermeiden.

Key words

CT - thorax - MR imaging

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