title: Repeatability of derived parameters from histograms following non-Gaussian diffusion modelling of diffusion-weighted imaging in a paediatric oncological cohort.
abstract: OBJECTIVE
  To examine repeatability of parameters derived from non-Gaussian diffusion models in data acquired in children with solid tumours.
  
  
  METHODS
  Paediatric patients (<16 years, n = 17) were scanned twice, 24 h apart, using DWI (6 b-values, 0-1000 mm-2s) at 1.5 T in a prospective study. Tumour ROIs were drawn (3 slices) and all data fitted using IVIM, stretched exponential, and kurtosis models; percentage coefficients of variation (CV) calculated for each parameter at all ROI histogram centiles, including the medians.
  
  
  RESULTS
  The values for ADC, D, DDCα, α, and DDCKgave CV < 10 % down to the 5th centile, with sharp CV increases below 5th and above 95th centile. K, f, and D* showed increased CV (>30 %) over the histogram. ADC, D, DDCα, and DDCKwere strongly correlated (ρ > 0.9), DDCαand α were not correlated (ρ = 0.083).
  
  
  CONCLUSIONS
  Perfusion- and kurtosis-related parameters displayed larger, more variable CV across the histogram, indicating observed clinical changes outside of D/DDC in these models should be interpreted with caution. Centiles below 5th for all parameters show high CV and are unreliable as diffusion metrics. The stretched exponential model behaved well for both DDCαand α, making it a strong candidate for modelling multiple-b-value diffusion imaging data.
  
  
  CONCLUSIONS
  • ADC has good repeatability as low 5th centile of the histogram distribution. • High CV was observed for all parameters at extremes of histogram. • Parameters from the stretched exponential model showed low coefficients of variation. • The median ADC, D, DDCα, and DDCKare highly correlated and repeatable. • Perfusion/kurtosis parameters showed high CV variations across their histogram distributions.
authors.affiliation: Division of Radiotherapy & Imaging, The Institute of Cancer Research, Cancer Research UK Cancer Imaging Centre, 123 Old Brompton Road, London, SW7 3RP, UK.
authors.forename: Neil P
authors.initials: NP
authors.lastname: Jerome
authors.affiliation: Division of Radiotherapy & Imaging, The Institute of Cancer Research, Cancer Research UK Cancer Imaging Centre, 123 Old Brompton Road, London, SW7 3RP, UK.
authors.forename: Keiko
authors.initials: K
authors.lastname: Miyazaki
authors.affiliation: Division of Radiotherapy & Imaging, The Institute of Cancer Research, Cancer Research UK Cancer Imaging Centre, 123 Old Brompton Road, London, SW7 3RP, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Collins
authors.affiliation: Division of Radiotherapy & Imaging, The Institute of Cancer Research, Cancer Research UK Cancer Imaging Centre, 123 Old Brompton Road, London, SW7 3RP, UK.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Orton
authors.affiliation: Division of Radiotherapy & Imaging, The Institute of Cancer Research, Cancer Research UK Cancer Imaging Centre, 123 Old Brompton Road, London, SW7 3RP, UK.
authors.forename: James A
authors.initials: JA
authors.lastname: d'Arcy
authors.affiliation: Department of Radiology, Royal Marsden NHS Foundation Trust, Sutton, Surrey, SM2 5PT, UK.
authors.forename: Toni
authors.initials: T
authors.lastname: Wallace
authors.affiliation: Paediatric Drug Development Team, Division of Cancer Therapeutics and Clinical Studies, The Institute of Cancer Research, 123 Old Brompton Road, London, SW7 3RP, UK.|Hospital Niño Jesus, Av Menendez Pelayo 65, Madrid, Spain.|Paediatric Drug Development Unit, Children and Young People's Unit, Royal Marsden NHS Foundation Trust, Sutton, Surrey, SM2 5PT, UK.
authors.forename: Lucas
authors.initials: L
authors.lastname: Moreno
authors.affiliation: Paediatric Drug Development Team, Division of Cancer Therapeutics and Clinical Studies, The Institute of Cancer Research, 123 Old Brompton Road, London, SW7 3RP, UK.|Paediatric Drug Development Unit, Children and Young People's Unit, Royal Marsden NHS Foundation Trust, Sutton, Surrey, SM2 5PT, UK.
authors.forename: Andrew D J
authors.initials: AD
authors.lastname: Pearson
authors.affiliation: Paediatric Drug Development Team, Division of Cancer Therapeutics and Clinical Studies, The Institute of Cancer Research, 123 Old Brompton Road, London, SW7 3RP, UK.|Paediatric Drug Development Unit, Children and Young People's Unit, Royal Marsden NHS Foundation Trust, Sutton, Surrey, SM2 5PT, UK.
authors.forename: Lynley V
authors.initials: LV
authors.lastname: Marshall
authors.affiliation: Paediatric Drug Development Team, Division of Cancer Therapeutics and Clinical Studies, The Institute of Cancer Research, 123 Old Brompton Road, London, SW7 3RP, UK.|Paediatric Drug Development Unit, Children and Young People's Unit, Royal Marsden NHS Foundation Trust, Sutton, Surrey, SM2 5PT, UK.
authors.forename: Fernando
authors.initials: F
authors.lastname: Carceller
authors.affiliation: Division of Radiotherapy & Imaging, The Institute of Cancer Research, Cancer Research UK Cancer Imaging Centre, 123 Old Brompton Road, London, SW7 3RP, UK. martin.leach@icr.ac.uk.
authors.forename: Martin O
authors.initials: MO
authors.lastname: Leach
authors.affiliation: Paediatric Drug Development Team, Division of Cancer Therapeutics and Clinical Studies, The Institute of Cancer Research, 123 Old Brompton Road, London, SW7 3RP, UK.|Paediatric Drug Development Unit, Children and Young People's Unit, Royal Marsden NHS Foundation Trust, Sutton, Surrey, SM2 5PT, UK.
authors.forename: Stergios
authors.initials: S
authors.lastname: Zacharoulis
authors.affiliation: Department of Radiology, Royal Marsden NHS Foundation Trust, Sutton, Surrey, SM2 5PT, UK.
authors.forename: Dow-Mu
authors.initials: DM
authors.lastname: Koh
mesh_terms: D000293:Adolescent; D002648:Child; D015331:Cohort Studies; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008962:Models, Theoretical; D009369:Neoplasms / Q000000981:diagnostic imaging*; D011446:Prospective Studies; D015203:Reproducibility of Results
keywords: Diffusion magnetic resonance imaging; Functional magnetic resonance imaging; Medical oncology; Paediatrics; Reproducibility of results