Differing Pulmonary Structural Abnormalities Detected on Pulmonary MR Imaging in Cystic Fibrosis Patients with Varying Pancreatic Function

Abstract

Purpose In cystic fibrosis (CF) the phenotypic expression of complaints varies widely. Genotypes with sufficient pancreatic function (PS) exhibit milder lung disease compared to CF patients with insufficient pancreatic function (PI). The purpose of this study was to evaluate structural lung disease (SLD) in CF patients with differing pancreatic status but similar results on pulmonary function testing using a pulmonary magnetic resonance imaging score (MR-CF score).

Materials and Methods In this retrospective study, 20 patients in our single-center CF database were included: 10 with PS (mean age 12.5 years; six male; BMI 17.4 kg/m²; FeV₁ 102 %) were matched by gender, age and lung function with 10 PI patients. Experienced observers semi-quantitatively assessed SLD for each lung lobe. The established MR-CF score measures the extent and the severity of bronchiectasis and bronchial wall thickening, mucus plugging, centrilobular opacity, consolidation, sacculation, and air trapping. The total score and sub-score values were compared to the pancreatic status.

Results Patients with CF-PS had overall statistically significant lower MR-CF scores (p = 0.024), and therefore milder SLD, compared to CF-PI. The differences were most significant for bronchiectasis (p = 0.0042) and air trapping (p = 0.0304). SLD was more severe in the upper lobes in all patients. However, differences between CF-PS and CF-PI patients were present in both the upper and lower lung areas (p = 0.0247 and p = 0.0196, respectively).

Conclusion Our results demonstrated that CF patients with impaired pancreatic function show more severe lung pathology detected by MRI, especially bronchiectasis and air trapping.

Key points: 

• Pulmonary MRI offers morphological and functional details without using ionizing radiation

• CF patients with pancreatic insufficiency show more severe pulmonary structural impairment

• Bronchiectasis and air trapping are the most common structural lung changes with predominance in the upper lung lobes.

Citation Format

• Kraus MS, Teufel M, Esser M et al. Differing Pulmonary Structural Abnormalities Detected on Pulmonary MR Imaging in Cystic Fibrosis Patients with Varying Pancreatic Function. Fortschr Röntgenstr 2020; 192: 567 – 575

Zusammenfassung

Ziel Die Multisystemerkrankung zystische Fibrose (CF) zeigt phänotypisch eine große Symptomvarianz, wobei Genotypen mit suffizienter Pankreasfunktion (PS) eine mildere Lungenbeeinträchtigung aufzuweisen scheinen im Vergleich zu pankreasinsuffizienten (PI) CF-Patienten. Ziel dieser Studie war die Evaluation von strukturellen Lungengerüstveränderungen (SLD) bei CF-Patienten mit unterschiedlicher Pankreasfunktion mittels pulmonalem MRT-Score (MR-CF-Score).

Material und Methoden 20 CF-Patienten wurden in diese retrospektive monozentrische Studie eingeschlossen: 10 PS-CF-Patienten (mittleres Alter 12,5 Jahre; 6 männlich; BMI 17,4 kg/m²; FeV₁ 102 %) wurden nach Geschlecht, Alter und Lungenfunktion mit 10 PI-Patienten gepaart. Erfahrene Radiologen beurteilten die strukturellen Lungenveränderungen in jedem Lungenlappen mittels semi-quantitativem MR-CF-Score: Dieser beinhaltet Bronchiektasien/peribronchiale Wandverdickung, Mukusverlegung, zentrilobuläre Opazität, Konsolidierung, Sakkulation und Überblähung/Air Trapping. Der Score sowie die kategorischen Werte wurden mit dem Pankreasstatus korreliert.

Ergebnisse CF-PS-Patienten zeigten einen signifikant niedrigeren MR-CF-Gesamtscore (p = 0,024) und damit mildere Lungengerüstveränderungen. Die größten kategorischen Unterschiede waren bezüglich Bronchiektasien (p = 0,0042) und Überblähung (p = 0,0304) zu beobachten. SLD waren insbesondere in den Lungenoberfeldern am deutlichsten, jedoch zeigten sich signifikante Unterschiede in Bezug auf die Pankreasfunktion in sowohl den Lungenober- als auch -unterfeldern (p = 0,0247 und p = 0,0196).

Schlussfolgerung Unsere Ergebnisse zeigen signifikante Unterschiede bezüglich SLD und Pankreasstatus bei CF-Patienten mit identischen Lungenfunktionswerten. Pankreasinsuffiziente Patienten zeigten hierbei deutlich schwerere Lungengerüstveränderungen im MRT, insbesondere Bronchiektasien und Überblähung.

Kernaussagen: 

• Pulmonales MRT ermöglicht eine morphologische und funktionelle Diagnostik ohne Einsatz ionisierender Strahlung.

• CF-Patienten mit insuffizienter Pankreasfunktion zeigen ausgeprägtere strukturelle Lungengerüstveränderungen im Vergleich zu pankreassuffizienten Patienten bei gleicher Lungenfunktion.

• Bronchiektasien und Überblähung sind die häufigsten strukturellen Lungengerüstveränderungen mit Betonung der Lungenoberfelder.

Key words

pancreas - thorax - MR-functional imaging - atelectasis - genetic defects - MR imaging

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