MEASURING HIP DEVELOPMENT USING MRI – A PRELIMINARY REPORT

Abstract

Background: Information on embryological hip development has been obtained from post mortem examination

1. . There is less information on normal foetal hip

2. . Magnetic resonance imaging (MRI) allows development to be followed in the healthy baby.

AIM: To assess the value of MRI of the foetus and neonate to provide information on normal and abnormal hip development.

To establish normal patterns of hip development.

To obtain charts that could be used to detect abnormality earlier.

There are three aspects to this study:

1. Validation – analysing MRI scans of babies hips prior to post mortem (the gold standard) would verify MRI as a valid tool for such studies.

2. Measurements will be gained for foetus in utero

3. Similarly for pre and term babies.

PATIENT SELECTION: 30 patients for each aspect of this pilot study, 90 in total (3).

For the initial validation process, parents who had consented to post mortem were asked to consider additionally an MR scan of their neonate’s hips, a total of 30 cases.

Method: MR images in axial and coronal planes were obtained using a high resolution T2 weighted sequences (4).

Measurements were made, by two independent observers, of the width and depth of the acetabulum and the radius & diameter of the femoral head, volume and area were calculated. Inter-observer variation was assessed.

Results: The babies ranged in gestation from 17 – 42 weeks

With the exception of the acetabular width each dimension showed little development until week 20 when the line of growth rose exponentially. The acetabular width showed only a slow rate of growth despite the changes seen in the femoral head. Levels of observer agreement were high (ICCs = 0.98) for all but depth (ICCs = 0.86). The measurements for all dimensions were in line with previous post mortem studies.

CONCLUSION: MRI is a valid and acceptable alternative to post mortem in the assessment of hip development eventually allowing early detection of abnormal hip development.