A pilot study to assess the feasibility of measurement of adrenal gland volume by magnetic resonance imaging

Abstract

Background: Repeated computed tomography (CT) assessment of the adrenal glands is associated with a significant radiation burden. The increasing capabilities of magnetic resonance (MR) volumetric analysis of the adrenals make this a potentially alternative technique in man.

Purpose: To determine whether MR imaging could be used to measure adrenal volume, and to determine the intra- and interobserver variation and repeatability of MR volume imaging of adrenals in healthy human subjects.

Material and Methods: This was a single-cohort, sequential design, three-part study involving four MRI examinations per subject following ethical approval and informed consent. Information was collected on four healthy subjects (three male and one female). Two different investigators estimated the area of the adrenal gland for each of the 3-mm contiguous slices (and consequently adrenal volume). In order to estimate inter- and intrareader variability, a repeated-measures mixed model was fitted with adrenal volume as the dependent variable. In order to estimate any bias between readers, Bland-Altman methodology was applied.

Results: Intraobserver variation for adrenal gland volume is approximately 5% of a 3-cm³ adrenal gland. Interobserver variation is approximately 9% of a 3-cm³ adrenal gland. Potential variation in measurement for adrenal volume from all sources equates to approximately 14% of a 3-cm³ adrenal gland. Verification of image reading by a second investigator (consensus reading) reduces variability.

Conclusion: Analysis of adrenal gland volume using MRI is a potentially reliable technique that could be used to assess a pathological change in adrenal size.

Key words::

• Adrenal
• magnetic resonance
• measurement
• volume

Acknowledgements

Thanks to Leisa Smith, Shirley Blaney, Gillian Finch (GlaxoSmithKline R&D, Clinical Unit, Cambridge), Claire Sims (MRIS Unit, Addenbrooke's Hospital, Cambridge), Ruth Dixon, and Jonathan Appleby (GSK R&D Neurosciences Discovery Medicine, Harlow, Essex) for their assistance in this work.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

This work was supported by GlaxoSmithKline.