Diffusion-weighted magnetic resonance imaging for assessment of lung lesions: repeatability of the apparent diffusion coefficient measurement

L Bernardin, N H M Douglas, D J Collins, S L Giles, E A M O'Flynn, M Orton, N M deSouza

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31 Citations (Scopus)

Abstract

PURPOSE: To establish repeatability of apparent diffusion coefficients (ADCs) acquired from free-breathing diffusion-weighted magnetic resonance imaging (DW-MRI) in malignant lung lesions and investigate effects of lesion size, location and respiratory motion.

METHODS: Thirty-six malignant lung lesions (eight patients) were examined twice (1- to 5-h interval) using T1-weighted, T2-weighted and axial single-shot echo-planar DW-MRI (b = 100, 500, 800 s/mm(2)) during free-breathing. Regions of interest around target lesions on computed b = 800 s/mm(2) images by two independent observers yielded ADC values from maps (pixel-by-pixel fitting using all b values and a mono-exponential decay model). Intra- and inter-observer repeatability was assessed per lesion, per patient and by lesion size (> or <2 cm) or location.

RESULTS: ADCs were similar between observers (mean ± SD, 1.15 ± 0.28 × 10(-3) mm(2)/s, observer 1; 1.15 ± 0.29 × 10(-3) mm(2)/s, observer 2). Intra-observer coefficients of variation of the mean [median] ADC per lesion and per patient were 11% [11.4%], 5.7% [5.7%] for observer 1 and 9.2% [9.5%], 3.9% [4.7%] for observer 2 respectively; inter-observer values were 8.9% [9.3%] (per lesion) and 3.0% [3.7%] (per patient). Inter-observer coefficient of variation (CoV) was greater for lesions <2 cm (n = 20) compared with >2 cm (n = 16) (10.8% vs 6.5% ADCmean, 11.3% vs 6.7% ADCmedian) and for mid (n = 14) vs apical (n = 9) or lower zone (n = 13) lesions (13.9%, 2.7%, 3.8% respectively ADCmean; 14.2%, 2.8%, 4.7% respectively ADCmedian).

CONCLUSION: Free-breathing DW-MRI of whole lung achieves good intra- and inter-observer repeatability of ADC measurements in malignant lung tumours.

KEY POINTS: • Diffusion-weighted MRI of the lung can be satisfactorily acquired during free-breathing • DW-MRI demonstrates high contrast between primary and metastatic lesions and normal lung • Apparent diffusion coefficient (ADC) measurements in lung tumours are repeatable and reliable • ADC offers potential in assessing response in lung metastases in clinical trials.

Original languageEnglish
Pages (from-to)502-11
Number of pages10
JournalEuropean Radiology
Volume24
Issue number2
DOIs
Publication statusPublished - Feb 2014

Keywords

  • Adult
  • Aged
  • Diagnosis, Differential
  • Diffusion Magnetic Resonance Imaging/methods
  • Female
  • Follow-Up Studies
  • Humans
  • Image Enhancement
  • Lung Neoplasms/diagnosis
  • Male
  • Middle Aged
  • Neoplasm Staging
  • Prospective Studies
  • ROC Curve
  • Reproducibility of Results
  • Respiration

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