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AJNR - American Journal of Neuroradiology

Published ahead of print on October 8, 2008
doi: 10.3174/ajnr.A1315

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American Journal of Neuroradiology 30:64-70, January 2009
© 2009 American Society of Neuroradiology

HEAD & NECK

MR Imaging of Orbital Inflammatory Syndrome, Orbital Cellulitis, and Orbital Lymphoid Lesions: The Role of Diffusion-Weighted Imaging

R. Kapur^a, A.R. Sepahdari^b, M.F. Mafee^c, A.M. Putterman^a, V. Aakalu^a, L.J.A. Wendel^d and P. Setabutr^a

^a Departments of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Ill
^b Radiology, University of Illinois at Chicago, Chicago, Ill
^c Department of Radiology, University of California, San Diego, Calif
^d Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa

Please address correspondence to Rashmi Kapur, MD, Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, 1855 W Taylor St, M/C 648, Chicago, IL 60612; e-mail: rashmi_kapur{at}yahoo.com

BACKGROUND AND PURPOSE: Orbital inflammatory syndrome (OIS) has clinical features that overlap with orbital lymphoid lesions and orbital cellulitis. Prompt diagnosis is needed in all 3 conditions because the management of each one differs greatly. CT and MR imaging, though useful, do not always distinguish among these conditions. The aim of this study was to identify the role of diffusion-weighted imaging (DWI) in differentiating these 3 diagnoses.

MATERIALS AND METHODS: A retrospective analysis of orbital MR imaging was conducted. T1- and T2-weighted and postcontrast images were analyzed. Region-of-interest analysis was performed by using measurements in areas of abnormality seen on conventional MR imaging sequences and measurements of the ipsilateral thalamus for each patient. The DWI signal intensity of the lesion was expressed as a percentage of average thalamic intensity in each patient. Similarly, lesion apparent diffusion coefficients (ADCs) and lesion-thalamus ADC ratios were calculated. Statistical significance was determined by the Kruskal-Wallis test, and post hoc pairwise comparisons, by the Mann-Whitney U test for DWI-intensity ratio, ADC, and ADC ratio.

RESULTS: A significant difference was noted in DWI intensities, ADC, and ADC ratio between OIS, orbital lymphoid lesions, and orbital cellulitis (P < .05). Lymphoid lesions were significantly brighter than OIS, and OIS lesions were significantly brighter than cellulitis. Lymphoid lesions showed lower ADC than OIS and cellulitis. A trend was seen toward lower ADC in OIS than in cellulitis (P = .17).

CONCLUSIONS: DWI may help differentiate OIS from lymphoid lesions and cellulitis and may allow more rapid management.

This article has been cited by other articles:

				A. R. Sepahdari, V. K. Aakalu, R. Kapur, E. A. Michals, N. Saran, A. French, and M. F. Mafee MRI of Orbital Cellulitis and Orbital Abscess: The Role of Diffusion-Weighted Imaging Am. J. Roentgenol., September 1, 2009; 193(3): W244 - W250. [Abstract] [Full Text] [PDF]