Imperial College London


Faculty of EngineeringDepartment of Mechanical Engineering

Research Associate



k.chappell Website




Lab 122 / Office 774City and Guilds BuildingSouth Kensington Campus





Publication Type

12 results found

Mills L, Chappell KE, Emsley R, Alavi A, Andrzejewska I, Santhakumaran S, Nicholl R, Chang J, Uthaya S, Modi Net al., 2024, Preterm Formula, Fortified or Unfortified Human Milk for Very Preterm Infants, the PREMFOOD Study: A Parallel Randomised Feasibility Trial., Neonatology, Vol: 121, Pages: 222-232

OBJECTIVE: Uncertainty exists regarding optimal supplemental diet for very preterm infants if the mother's own milk (MM) is insufficient. We evaluated feasibility for a randomised controlled trial (RCT) powered to detect important differences in health outcomes. METHODS: In this open, parallel, feasibility trial, we randomised infants 25+0-31+6 weeks of gestation by opt-out consent to one of three diets: unfortified human milk (UHM) (unfortified MM and/or unfortified pasteurised human donor milk (DM) supplement), fortified human milk (FHM) (fortified MM and/or fortified DM supplement), and unfortified MM and/or preterm formula (PTF) supplement from birth to 35+0 weeks post menstrual age. Feasibility outcomes included opt-outs, adherence rates, and slow growth safety criteria. We also obtained anthropometry, and magnetic resonance imaging body composition data at term and term plus 6 weeks (opt-in consent). RESULTS: Of 35 infants randomised to UHM, 34 to FHM, and 34 to PTF groups, 21, 19, and 24 infants completed imaging at term, respectively. Study entry opt-out rate was 38%; 6% of parents subsequently withdrew from feeding intervention. Two infants met predefined slow weight gain thresholds. There were no significant between-group differences in term total adipose tissue volume (mean [SD]: UHM: 0.870 L [0.35 L]; FHM: 0.889 L [0.31 L]; PTF: 0.809 L [0.25 L], p = 0.66), nor in any other body composition measure or anthropometry at either timepoint. CONCLUSIONS: Randomisation to UHM, FHM, and PTF diets by opt-out consent was acceptable to parents and clinical teams, associated with safe growth profiles and no significant differences in body composition. Our data provide justification to proceed to a larger RCT.

Journal article

Lanz H, Ristic M, Chappell K, McGinley Jet al., 2023, Minimum number of scans for collagen fibre direction estimation using Magic Angle Directional Imaging (MADI) with a priori information, Array, Vol: 17, Pages: 1-10, ISSN: 2590-0056

Tissues such as tendons, ligaments, articular cartilage, and menisci contain significant amounts of organised collagen which gives rise to the Magic Angle effect during magnetic resonance imaging (MRI). The MR intensity response of these tissues is dependent on the angle between the main field, B0, and the direction of the collagen fibres. Our previous work showed that by acquiring scans at as few as 7–9 different field orientations, depending on signal to noise ratio (SNR), the tissue microstructure can be deduced from the intensity variations across the set of scans. Previously our Magic Angle Directional Imaging (MADI) technique used rigid registration and manual final alignment, and did not assume any knowledge of the target anatomy being scanned. In the present work, fully automatic soft registration is incorporated into the MADI workflow and a priori knowledge of the target anatomy is used to reduce the required number of scans. Simulation studies were performed to assess how many scans are theoretically necessary. These findings were then applied to MRI data from a caprine knee specimen. Simulations suggested that using 3 scans might be sufficient, but in practice 4 scans were necessary to achieve high accuracy. 5 scans only offered marginal gains over 4 scans. A 15 scan dataset was used as a gold standard for quantitative voxel-to-voxel comparison of computed fibre directions, qualitative comparison of collagen tractography plots are also presented. The results are also encouraging at low SNR values, showing robustness of the method and applicability at low field.

Journal article

Chappell KE, Williams AA, Chu CR, 2021, Quantitative Magnetic Resonance Imaging of Articular Cartilage Structure and Biology, Cartilage Injury of the Knee: State-of-the-Art Treatment and Controversies, Pages: 37-50, ISBN: 9783030780500

Articular cartilage is a complex avascular and aneural tissue. Once its surface is disrupted, it is difficult to repair. Cartilage consists of an anisotropic extracellular collagen matrix containing water, proteoglycans, and chondrocytes. State-of-the-art quantitative morphologic and compositional magnetic resonance imaging (MRI) can visualize and measure changes to cartilage structure in injury or disease earlier and with more specificity than is achievable with radiography. Morphologic MRI permits assessment of cartilage surface disruption, subsurface lesions, and cartilage thickness loss. Compositional MRI techniques such as T2 and UTE-T2* mapping, dGEMRIC, and T1ρ relaxometry can probe subsurface changes to cartilage biochemical integrity including disruption of the collagen matrix and loss of proteoglycans. These techniques show potential to assist with monitoring subclinical signs of cartilage degeneration, as well as the efficacy of cartilage repair procedures and therapeutic interventions.

Book chapter

Brujic D, Chappell KE, Ristic M, 2020, Accuracy of collagen fibre estimation under noise using directional MR imaging, Computerized Medical Imaging and Graphics, Vol: 86, Pages: 1-9, ISSN: 0895-6111

In tissues containing significant amounts of organised collagen, such as tendons, ligaments, menisci and articular cartilage, MR imaging exhibits a strong signal intensity variation caused by the angle between the collagen fibres and the magnetic field. By obtaining scans at different field orientations it is possible to determine the unknown fibre orientations and to deduce the underlying tissue microstructure. Our previous work demonstrated how this method can detect ligament injuries and maturity-related changes in collagen fibre structures. Practical application in human diagnostics will demand minimisation of scanning time and likely use of open low-field scanners that can allow re-orienting of the main field. This paper analyses the performance of collage fibre estimation for various image SNR values, and in relation to key parameters including number of scanning directions and parameters of the reconstruction algorithm. The analysis involved Monte Carlo simulation studies which provided benchmark performance measures, and studies using MR images of caprine knee samples with increasing levels of synthetic added noise. Tractography plots in the form of streamlines were performed, and an Alignment Index (AI) was employed as a measure of the detected orientation distribution. The results are highly encouraging, showing high accuracy and robustness even for low image SNR values.

Journal article

Chappell K, Brujic D, Van Der Straeten C, Meeson R, Gedroyc W, McRobbie D, Ristic Met al., 2019, Detection of maturity and ligament injury using magic angle directional imaging, Magnetic Resonance in Medicine, Vol: 82, Pages: 1041-1054, ISSN: 0740-3194

Purpose: To investigate whether magnetic field–related anisotropies of collagen may be correlated with postmortem findings in animal models.Methods: Optimized scan planning and new MRI data‐processing methods were proposed and analyzed using Monte Carlo simulations. Six caprine and 10 canine knees were scanned at various orientations to the main magnetic field. Image intensities in segmented voxels were used to compute the orientation vectors of the collagen fibers. Vector field and tractography plots were computed. The Alignment Index was defined as a measure of orientation distribution. The knees were subsequently assessed by a specialist orthopedic veterinarian, who gave a pathological diagnosis after having dissected and photographed the joints.Results: Using 50% less scans than reported previously can lead to robust calculation of fiber orientations in the presence of noise, with much higher accuracy. The 6 caprine knees were found to range from very immature (< 3 months) to very mature (> 3 years). Mature specimens exhibited significantly more aligned collagen fibers in their patella tendons compared with the immature ones. In 2 of the 10 canine knees scanned, partial cranial caudal ligament tears were identified from MRI and subsequently confirmed with encouragingly high consistency of tractography, Alignment Index, and dissection results.Conclusion: This method can be used to detect injury such as partial ligament tears, and to visualize maturity‐related changes in the collagen structure of tendons. It can provide the basis for new, noninvasive diagnostic tools in combination with new scanner configurations that allow less‐restricted field orientations.

Journal article

Logan K, Emsley RJ, Jeffries S, Andrzejewska I, Hyde MJ, Gale C, Chappell K, Mandalia S, Santhakumaran S, Parkinson JRC, Mills L, Modi Net al., 2016, Development of Early Adiposity in Infants of Mothers With Gestational Diabetes Mellitus, Diabetes Care, Vol: 39, Pages: 1045-1051, ISSN: 0149-5992

OBJECTIVEInfants born to mothers with gestational diabetes mellitus (GDM) are at greaterrisk of later adverse metabolic health. We examined plausible candidate mediators;adipose tissue (AT) quantity and distribution, and intrahepatocellular lipid(IHCL) content, comparing infants of mothers with GDM and without GDM (controlgroup) over the first 3 postnatal months.RESEARCH DESIGN AND METHODSWe conducted a prospective longitudinal study using MRI and spectroscopy toquantify whole-body and regional AT volumes, and IHCL content, within 2 weeksand 8–12 weeks after birth. We adjusted for infant size and sex, and maternalprepregnancy BMI. Values are reported as the mean difference (95% CI).RESULTSWe recruited 86 infants (GDM group 42 infants; control group 44 infants). Motherswith GDM had good pregnancy glycemic control. Infants were predominantlybreast fed up to the time of the second assessment (GDM group 71%; controlgroup 74%). Total AT volumes were similar in the GDM group compared with thecontrol group at a median age of 11 days (228 cm3 [95% CI 2121, 65], P = 0.55), butwere greater in the GDM group at a median age of 10 weeks (247 cm3 [56, 439], P =0.01). After adjustment for size, the GDM group had significantly greater total ATvolume at 10 weeks than control group infants (16.0% [6.0, 27.1], P = 0.002). ATdistribution and IHCL content were not significantly different at either time point.CONCLUSIONSAdiposity in GDM infants is amplified in early infancy, despite good maternalglycemic control and predominant breast-feeding, suggesting a potential causalpathway to later adverse metabolic health. Reduction in postnatal adiposity maybe a therapeutic target to reduce later health risks.

Journal article

Gale C, Jeffries S, Logan KM, Chappell KE, Uthaya SN, Modi Net al., 2013, Avoiding sedation in research MRI and spectroscopy in infants: our approach, success rate and prevalence of incidental findings, ARCHIVES OF DISEASE IN CHILDHOOD-FETAL AND NEONATAL EDITION, Vol: 98, Pages: F267-F268, ISSN: 1359-2998

Journal article

Yiannakas MC, Wheeler-Kingshott CAM, Berry AM, Chappell K, Henderson A, Kolappan M, Miller DH, Tozer DJet al., 2010, A Method for Measuring the Cross Sectional Area of the Anterior Portion of the Optic Nerve In Vivo Using a Fast 3D MRI Sequence, JOURNAL OF MAGNETIC RESONANCE IMAGING, Vol: 31, Pages: 1486-1491, ISSN: 1053-1807

Journal article

Reichert ILH, Robson MD, Gatehouse PD, He TG, Chappell KE, Holmes J, Girgis S, Bydder GMet al., 2005, Magnetic resonance imaging of cortical bone with ultrashort TE pulse sequences, MAGNETIC RESONANCE IMAGING, Vol: 23, Pages: 611-618, ISSN: 0730-725X

Journal article

Chappell KE, Robson MD, Stonebridge-Foster A, Glover A, Allsop JM, Williams AD, Herlihy AH, Moss J, Gishen P, Bydder GMet al., 2004, Magic angle effects in MR neurography, AMERICAN JOURNAL OF NEURORADIOLOGY, Vol: 25, Pages: 431-440, ISSN: 0195-6108

Journal article

Reichert ILH, Benjamin M, Gatehouse PD, Chappell KE, Holmes J, He TG, Bydder GMet al., 2004, Magnetic resonance imaging of periosteum with ultrashort TE pulse sequences, JOURNAL OF MAGNETIC RESONANCE IMAGING, Vol: 19, Pages: 99-107, ISSN: 1053-1807

Journal article

Chappell KE, Patel N, Gatehouse PD, Main J, Puri BK, Taylor-Robinson SD, Bydder GMet al., 2003, Magnetic resonance imaging of the liver with ultrashort TE (UTE) pulse sequences, JOURNAL OF MAGNETIC RESONANCE IMAGING, Vol: 18, Pages: 709-713, ISSN: 1053-1807

Journal article

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