The Qualitative Grading of Muscle Fat Infiltration in Whiplash Using Fat/Water Magnetic Resonance Imaging

Publication date: Available online 5 September 2017
Source:The Spine Journal
Author(s): Rebecca Abbott, Anneli Peolsson, Janne West, James M. Elliott, Ulrika Åslund, Anette Karlsson, Olof Dahlqvist Leinhard
Background contextDevelopment of muscle fat infiltration (MFI) in the neck muscles is associated with poor functional recovery following whiplash injury. Custom software and time-consuming manual segmentation of magnetic resonance (MR) images is required for quantitative analysis and presents as a barrier for clinical translation.PurposeThe purpose of this work was to establish a qualitative MR measure for MFI and evaluate its ability to differentiate between individuals with severe whiplash-associated disorder (WAD), mild/moderate WAD, and healthy controls.Study Design/SettingCross-SectionalPatient SampleThirty-one subjects with WAD and 31 age and sex matched controls were recruited from an ongoing randomized controlled trial.Outcome MeasuresThe cervical multifidus was visually identified and segmented into eighths in the axial fat/water images (C4-C7). MFI was assessed on a visual scale: 0 for no or marginal MFI, 1 for light MFI and 2 for distinct MFI. The participants with WAD were divided in two groups: mild/moderate and severe based on neck disability index (NDI) % scores.MethodsThe mean regional MFI was compared between the healthy controls and each of the WAD groups using the Mann-Whitney U-test. ROC-analyses were carried out to evaluate the validity of the qualitative method. The study received funding from the Swedish Research Council and the Medical research council of South-East Sweden (FORSS). AP and UÅ have no conflicts of interests to report. ODL, JW and AK are stockowners in Advanced MR Analytics AB (AMRA). JE reports relevant activities outside the body of work as 35% investment/ownership in a medical consulting start-up, Pain ID, LLC.ResultsTwenty-one (68%) patients had mild/moderate disability and 10 (32%) were considered severe. Inter- and intra- rater reliability was excellent when grading was averaged by level or when frequency of grade 2 was considered. Statistically significant differences (p<0.05) in regional MFI were particularly notable between the severe WAD group and healthy controls. The ROC-curve, based on detection of distinct MFI, showed an area-under-the curve of 0.768 (95% CI 0.59-0.94) for discrimination of WAD participants.ConclusionsThese preliminary results suggest a qualitative MR measure for MFI is reliable and valid, and may prove useful towards the classification of WAD in radiology practice.



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