Three-dimensional magnetic resonance imaging ultrashort echo-time cones for assessing lung density in pediatric patients

Konstantinos G Zeimpekis,Julia Geiger,Christian J Kellenberger,Florian Wiesinger,Gaspar Delso

doi:10.1007/s00247-020-04791-1

Konstantinos G Zeimpekis, Julia Geiger + Show 3 more

Open Access

https://doi.org/10.1007/s00247-020-04791-1

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Abstract

BackgroundMRI of lung parenchyma is challenging because of the rapid decay of signal by susceptibility effects of aerated lung on routine fast spin-echo sequences.ObjectiveTo assess lung signal intensity in children on ultrashort echo-time sequences in comparison to a fast spin-echo technique.Materials and methodsWe conducted a retrospective study of lung MRI obtained in 30 patients (median age 5 years, range 2 months to 18 years) including 15 with normal lungs and 15 with cystic fibrosis. On a fast spin-echo sequence with radial readout and an ultrashort echo-time sequence, both lungs were segmented and signal intensities were extracted. We compared lung-to-background signal ratios and histogram analysis between the two patient cohorts using non-parametric tests and correlation analysis.ResultsOn ultrashort echo-time the lung-to-background ratio was age-dependent, ranging from 3.15 to 1.33 with high negative correlation (Rs = −0.86). Signal in posterior dependent portions of the lung was 18% and 11% higher than that of the anterior lung for age groups 0–2 and 2–18 years, respectively. The fast spin-echo sequence showed no variation of signal ratios by age or location, with a median of 0.99 (0.98–1.02). Histograms of ultrashort echo-time slices between controls and children with aggravated cystic fibrosis with mucus plugging and wall thickening exhibited significant discrepancies that differentiated between normal and pathological lungs.ConclusionSignal intensity of lung on ultrashort echo-time is higher than that on fast spin-echo sequences, is age-dependent and shows a gravity-dependent anterior to posterior gradient. This signal variation appears similar to lung density described on CT.

Highlights

Computed tomography (CT) is considered the reference standard for imaging the lung parenchyma
The big advantage of MRI for lung imaging in children would be that it does not involve ionizing radiation — which poses a substantial risk, especially in young children, who are the most sensitive [11] — MRI could be used as radiation-free alternative to follow-up CT scans in pediatric patients [12]
Patients were split into two groups: 15 patients (10 females, 5 males, median age 6 years, range 0–18 years) with morphologically normal lungs were used as a control group and 15 patients (4 females, 11 males, median age 4 years, range 1–17 years) were diagnosed with cystic fibrosis

Summary

Introduction

Computed tomography (CT) is considered the reference standard for imaging the lung parenchyma. MRI is being used increasingly for assessing the lung and airways in children [1,2,3,4]. The big advantage of MRI for lung imaging in children would be that it does not involve ionizing radiation — which poses a substantial risk, especially in young children, who are the most sensitive [11] — MRI could be used as radiation-free alternative to follow-up CT scans in pediatric patients [12]. This study involved children and adolescents with cystic fibrosis, with the goal of validating the diagnostic value of our ultrashort echo-time sequence. MRI of lung parenchyma is challenging because of the rapid decay of signal by susceptibility effects of aerated lung on routine fast spin-echo sequences

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