Magnetic Resonance Imaging in Sinonasal Disease Aaron M. Betts, MD*† and Rebecca Cornelius, MD* Abstract: Computed tomography (CT) is often the primary imaging modality for the evaluation of sinonasal disease. For some indications, magnetic resonance imaging (MRI) may provide additional information. There are established indications for using MRI in complicated sinonasal inflammatory disease, invasive fungal sinus disease, and sinonasal mass lesions. When MRI is used in the evaluation of sinonasal disease, it is usually used as a complementary modality in addition to CT. Magnetic resonance imaging in sinonasal disease can be used to further characterize the primary sinonasal disease process and to evaluate the extent of complications such as orbital or intracranial involvement. When MRI is used in sinonasal disease, it should be evaluated in the context of the clinical situation and CT imaging features. This will help radiologists provide a meaningful differential diagnosis to assist in clinical management. Key Words: rhinosinusitis, fungal sinus disease, sinonasal polyposis, sinonasal neoplasm (Top Magn Reson Imaging 2015;24: 15–22)
maging is commonly used in the clinical evaluation and monitoring of sinonasal disease. For the majority of indications, computed tomography (CT) is the primary imaging modality and usually provides a detailed evaluation to guide diagnosis and management when sinonasal imaging is required. Magnetic resonance (MR) imaging is an important imaging modality in some sinonasal disease processes. There are established indications for MR imaging (MRI) as a complementary modality in evaluating complicated rhinosinusitis, invasive sinonasal infection, or when CT or clinical examinations reveals a sinonasal mass lesion.
UNCOMPLICATED RHINOSINUSITIS Adult rhinosinusitis was defined in 1997 by the Task Force for Rhinosinusitis as “a condition manifested by an inflammatory response involving the following: the mucous membranes… of the nasal cavity and the paranasal sinuses, fluids within these cavities, and/or underlying bone.” The Task Force defined major and minor criteria to establish a clinical diagnosis of adult rhinosinusitis and defined 5 classifications based upon these criteria and the duration of the disease process. These 5 classifications of adult rhinosinusitis include acute (12 weeks), and acute exacerbation of chronic rhinosinusitis (sudden worsening of chronic sinusitis with return to baseline after treatment).1 In 2003, the Task Force for Defining Adult Chronic Rhinosinusitis simplified the definition of rhinosinusitis as “a group of disorders characterized by inflammation of the mucosa of the nose and paranasal sinuses.” The 1997 Task Force definitions were based largely upon symptoms, and imaging was not required for the diagnosis. This Task Force
From the *Department of Radiology, University of Cincinnati Medical Center; and †Cincinnati Children's Hospital Medical Center, Cincinnati, OH. Reprints: Rebecca Cornelius, MD, Department of Radiology, University of Cincinnati Medical Center, 234 Goodman St, Cincinnati, OH 45219 (e‐mail: [email protected]
). The authors declare no conflict of interest. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
recommended CT imaging for recurrent or recalcitrant rhinosinusitis but did not discuss the use of MRI. The 2003 Task Force also recommended CT imaging as a means of identifying mucosal abnormalities and recommended against the use of MRI as a primary modality.2 The current American College of Radiology Appropriateness Criteria (ACR-AC) on sinonasal disease also recommend CT as the primary imaging modality for acute, subacute, recurrent, and chronic rhinosinusitis. The ACR-AC indicates that the use of MRI in uncomplicated sinusitis is usually not indicated. However, the ACR-AC mentions that there may be utility of MRI of the head in the general evaluation of headache.3 A 2009 study of patients followed by MRI for pituitary disease compared the grading of sinonasal disease by both MR and CT using the Lund-Mackay scoring system, an image-based system used to grade severity of sinonasal inflammatory disease. This study demonstrated a high correlation of Lund-Mackay scores between CT and MR.4 However, it is important to note that this study did not account for sinonasal symptoms or indications for sinonasal imaging. Similar definitions for rhinosinusitis have been established for pediatric patients. A 2013 Clinical Practice Guideline by the American Academy of Pediatrics (AAP) defines acute bacterial sinusitis in children as persistent nasal discharge for longer than 10 days; a worsening course of nasal discharge, cough, or fever after initial improvement; or concurrent fever and purulent nasal discharge for at least 3 consecutive days.5 The 2001 Clinical Practice Guideline by the AAP defines the temporal classifications of sinusitis in children: acute bacterial sinusitis (