Magnetic resonance imaging of uveitis.

INTRODUCTION: Uveitis is a term used to describe inflammation of the choroid, iris, or ciliary body, which make up the uveal tract. It can be idiopathic or associated with a systemic disease which may be infectious or noninfectious. With the exception of B-scan ultrasonography, current imaging methods for diagnosing and monitoring uveitis are predominately non-radiologic. Although MRI has been anecdotally shown to detect various inflammatory conditions of the globe, such as posterior scleritis, endophthalmitis, and posterior uveitis secondary to Vogt-Koyanagi-Harada disease, a more comprehensive review of the MRI findings in uveitis of various etiologies is presented here. METHODS: The MRI and CT studies of seven patients with uveitis and the clinical history of three of them (not available in four patients) were reviewed. Etiologies included ankylosing spondylitis, relapsing polychondritis, Vogt-Koyanagi-Harada disease, sarcoidosis, and tuberculosis. RESULTS: Increased gadolinium enhancement of the uveal tract, which is visualized as the enhancing layer immediately deep to the low-signal sclera, was seen on all six MRI studies. Diffusion-weighted imaging of a case with posterior uveitis and subretinal effusions revealed restriction within the uvea and effusions. Two patients had inflammatory nodules adherent to the uvea, two patients had vitreous humor abnormalities, and one patient exhibited proximal perineural and perimuscular spread of enhancement. Uveoscleral thickening and enhancement with a posterior calcification were observed in the patient with chronic uveitis imaged with CT. CONCLUSIONS: Increased uveal tract enhancement is a common finding in patients with uveitis, regardless of anatomic distribution and etiology. MRI can also further evaluate complications of uveitis and help differentiate it from masquerade syndromes.

Comparative case series of exostoses and osteomas of the internal auditory canal.

Exostoses and osteomas are benign bony lesions of the auditory canal. Although common in the external auditory canal, they are rare and difficult to distinguish in the internal auditory canal (IAC). In this literature review and case presentation, we define radiologic and histologic criteria to differentiate exostoses from osteomas of the IAC. Two patients with exostoses and 1 patient with an osteoma of the IAC are described here. Patient 1 presented with disabling vertigo and was found to have bilateral exostoses with nerve impingement on the right. After removal of the right-sided exostoses via retrosigmoid craniotomy, the patient had complete resolution of her symptoms over 1 year. Patient 2 presented with bilateral pulsatile tinnitus and vertigo and was found to have bilateral IAC exostoses. Patient 3 presented with hearing loss and tinnitus, and a unilateral IAC osteoma was ultimately discovered. Because of the mild nature of their symptoms, patients 2 and 3 were managed without surgery. We show that IAC osteomas can be differentiated from exostoses by radiographic evidence of bone marrow in high-resolution computed tomography scans, or by the presence of fibrovascular channels on histologic analysis. Management of these rare entities is customized on the basis of patient symptoms.

Indeterminate orbital masses: restricted diffusion at MR imaging with echo-planar diffusion-weighted imaging predicts malignancy.

PURPOSE: To determine whether magnetic resonance (MR) imaging with diffusion-weighted (DW) imaging can help discriminate between radiologically indeterminate benign and malignant orbital masses and to identify optimal apparent diffusion coefficient (ADC) thresholds for such discrimination. MATERIALS AND METHODS: Informed consent was waived for this HIPAA-compliant institutional review board-approved retrospective study. Forty-seven orbital masses imaged with echo-planar DW imaging were identified in 47 patients (25 female patients, 22 male patients; average age, 35 years). A fellowship-trained orbital surgeon determined reference-standard diagnoses on the basis of chart review, and a neuroradiology fellow and senior neuroradiologist who were blinded to the diagnoses selected a region of interest for each lesion by consensus. ADC was calculated from signal intensity on DW images obtained with b = 1000 and b = 0 sec/mm(2). Lesion ADC was also compared with that of normal-appearing white matter (ADC ratio). The Student t test was used to compare groups. Receiver operating characteristic analysis was performed. Intraobserver agreement was assessed with a repeat data collection. RESULTS: Malignant lesions had lower ADCs than benign lesions, irrespective of patient age (P < .02) and in adults specifically (P < .05). Lymphomas had lower ADCs than pseudotumors (P < .001). An ADC of less than 1.0 x 10(-3) mm(2)/sec and an ADC ratio of less than 1.2 were optimal for predicting malignancy (sensitivity, 63% for both; specificity, 84% and 90%, respectively; and accuracy, 77% and 81%, respectively). Lymphoma was differentiated from pseudotumor with 100% accuracy (in 16 of 16 cases) by using these values. Infiltrative lesions that were hypointense on T2-weighted images were better characterized with DW imaging than lesions that were hyperintense or well defined. CONCLUSION: Echo-planar DW MR imaging can help characterize indeterminate orbital masses.

MRI of orbital cellulitis and orbital abscess: the role of diffusion-weighted imaging.

OBJECTIVE: Our aims were to describe the role of diffusion-weighted imaging (DWI) in detecting abscess as a complication of orbital cellulitis and to assess whether abscess can be diagnosed with a combination of conventional unenhanced sequences and whole-brain DWI with parallel acquisition. Nine cases of orbital cellulitis imaged with MRI were retrospectively reviewed, including six cases with pyogenic abscess. CONCLUSION: In this preliminary study, DWI improved diagnostic confidence in nearly all cases of orbital abscess when used in conjunction with contrast-enhanced imaging. DWI also confirmed abscess in a majority of cases without contrast-enhanced imaging, which may be of particular use when contrast material is contraindicated.

Magnetic resonance imaging: dynamic contrast enhancement and diffusion-weighted imaging to identify malignant cervical lymph nodes.

OBJECTIVE: To examine the potential of two magnetic resonance imaging (MRI) techniques-dynamic contrast enhancement (DCE) and diffusion-weighted imaging (DWI)-for the detection of malignant cervical lymph nodes. MATERIALS AND METHODS: Using DCE and DWI, we evaluated 33 cervical lymph nodes. For the DCE technique, the maximum relative enhancement, relative enhancement, time to peak enhancement, wash-in rate, wash-out rate, brevity of enhancement, and area under the curve were calculated from a semi-quantitative analysis. For the DWI technique, apparent diffusion coefficients (ADCs) were acquired in the region of interest of each lymph node. Cystic or necrotic parts were excluded. All patients underwent neck dissection or node biopsy. Imaging results were correlated with the histopathological findings. None of the patients underwent neoadjuvant treatment before neck dissection. RESULTS: Relative enhancement, maximum relative enhancement, and the wash-in rate were significantly higher in malignant lymph nodes than in benign lymph nodes (p < 0.009; p < 0.05; and p < 0.03, respectively). The time to peak enhancement was significantly shorter in the malignant lymph nodes (p < 0.02). In the multivariate analysis, the variables identified as being the most capable of distinguishing between benign and malignant lymph nodes were time to peak enhancement (sensitivity, 73.7%; specificity, 69.2%) and relative enhancement (sensitivity, 89.2%; specificity, 69.2%). CONCLUSION: Although DCE was able to differentiate between benign and malignant lymph nodes, there is still no consensus regarding the use of a semi-quantitative analysis, which is difficult to apply in a clinical setting. Low ADCs can predict metastatic disease, although inflammatory processes might lead to false-positive results.

OBJETIVO: Examinar o potencial das imagens de contraste dinâmico (DCE-MRI) e difusão (DW-MRI) em ressonância magnética na detecção de linfonodos cervicais malignos. MATERIAIS E MÉTODOS: Foram realizadas DCE-MRI e DW-MRI em 33 linfonodos cervicais. Os valores de realce relativo máximo, realce relativo, tempo de pico, taxa de realce e lavagem, brevidade do realce e área sob a curva foram avaliados pela análise semiquantitativa (DCE-MRI). Os coeficientes de difusão aparente na DW-MRI foram obtidos na área de interesse. Foram excluídas partes císticas ou necróticas dos nódulos. Todos os pacientes foram submetidos a dissecção cervical ou a biópsia. Os resultados de imagem foram correlacionados com os achados patológicos. Nenhum paciente foi submetido a tratamento neoadjuvante antes da dissecção do pescoço. RESULTADOS: Realce relativo, realce relativo máximo e taxa de realce aumentaram nos nódulos malignos (p < 0,009, p < 0,05 e p < 0,03, respectivamente). O tempo de pico foi reduzido nos nódulos malignos (p < 0,02). A análise multivariada identificou tempo de pico (sensibilidade, 73,7%; especificidade, 69,2%) e realce relativo (sensibilidade, 89,2%; especificidade, 69,2%) como variáveis capazes de distinguir os nódulos benignos e malignos. CONCLUSÃO: Embora o DCE-MRI possa diferenciar os nódulos benignos e malignos, ainda não há consenso sobre a técnica de análise semiquantitativa, em razão de dificuldade de aplicação clínica. Valores baixos do coeficiente de difusão aparente podem predizer nódulo metastático, mas devem-se considerar também resultados falso-positivos, provavelmente secundários ao processo inflamatório.

Otolaryngology in Critical Care.

Diseases affecting the ear, nose, and throat are prevalent in intensive care settings and often require combined medical and surgical management. Upper airway occlusion can occur as a result of malignant tumor growth, allergic reactions, and bleeding events and may require close monitoring and interventions by intensivists, sometimes necessitating surgical management. With the increased prevalence of immunocompromised patients, aggressive infections of the head and neck likewise require prompt recognition and treatment. In addition, procedure-specific complications of major otolaryngologic procedures can be highly morbid, necessitating vigilant postoperative monitoring. For optimal outcomes, intensivists need a broad understanding of the pathophysiology and management of life-threatening otolaryngologic disease.

A study of middle cranial fossa anatomy and anatomic variations.

We conducted a study to establish standardized measurements of the common anatomic landmarks used during surgery via the middle cranial fossa approach. Results were based on high-resolution computed tomography (CT) images of 98 temporal bones in 54 consecutively presenting patients. Measurements were obtained with the assistance of the standard PACS (picture archiving and communication system) software. We found that the superior semicircular canal (SSC) dome was not the highest point on the temporal bone (i.e., the arcuate eminence) in 78 of the temporal bone images (79.6%). Pneumatization above the SSC and above the internal auditory canal (IAC) was found in 27 (27.6%) and 39 (39.8%) temporal bone images, respectively. The anterior wall of the external auditory canal was always anterior to the anterior wall of the IAC. The mean angles between the SSC and the posterior and anterior walls of the IAC were 42.3 degrees and 60.8 degrees, respectively. We also measured other distances, and we compared our findings with those published by others. We hope that the results of our study will help surgeons safely and rapidly locate anatomic landmarks when performing surgery via the middle cranial fossa approach.

Imaging of rhinosinusitis and its complications: plain film, CT, and MRI.

Conventional plain-film radiography may be used as a screening method for various pathological conditions of the sinonasal cavities. However, CT scanning remains the study of choice for the imaging evaluation of acute and chronic inflammatory diseases of sinonasal cavities. MRI is superior to CT in differentiating inflammatory conditions from neoplastic processes. The most common complications of rhinosinusitis in children occur in the orbit. The information obtained from the CT scan and MRI, together with clinical findings, may be the best guidelines for clinical management and the mode of treatment. Although intracranial complications of sinusitis are relatively rare, prompt recognition of these disease states is important to prevent permanent neurological deficit or fatality. It is prudent to obtain MRI of the sinuses, orbits, and brain whenever extensive or multiple complications of sinusitis are suspected, in addition to CT scanning. Chronic rhinosinusitis is a clinical diagnosis, confirmed and staged with the CT scan of sinonasal cavities. Chronic inflammatory disease is often associated with mucosal thickening and sclerosis of the bone, particularly within the sinuses. Chronic extramucosal fungal sinusitis develops as a saprophytic growth in retained secretions in a sinus cavity. The imaging manifestations of chronic mycotic rhinosinusitis may be nonspecific or highly suggestive of the presence of fungal infection. The presence of diffuse increased attenuation within the paranasal sinuses and nasal cavity should be considered as chronic allergic hypersensitivity aspergillosis (chronic noninvasive aspergillosis) or chronic hyperplastic sinusitis and polyposis associated with desiccated, retained mucosal secretions. The MRI characteristics of fungal sinusitis depend on the stage of the disease.

Anatomy and pathology of the eye: role of MR imaging and CT.

Since the development of CT and MR imaging, significant progress has been made in ophthalmic imaging. As the technology advanced and MR imaging units improved their ability in term of spatial resolution, the role of MR imaging in ophthalmic imaging has increased accordingly. This article considers the role of MR and CT imaging in the diagnosis of selected pathologies of the eye.

Rhinosinusitis: Developing guidance for clinical trials.

The Rhinosinusitis Initiative was developed by 5 national societies. The current guidance document is an expansion of the 2004 publication, "Rhinosinusitis: Establishing definitions for clinical research and patient care" and provides templates for clinical trials in antimicrobial, anti-inflammatory, and symptom-relieving therapies for the following: (1) acute presumed bacterial rhinosinusitis, (2) chronic rhinosinusitis (CRS) without nasal polyps, (3) CRS with nasal polyps, and (4) classic allergic fungal rhinosinusitis. In addition to the templates for clinical trials and proposed study designs, the Rhinosinusitis Initiative has developed 6 appendices, which address (1) health outcomes, (2) nasal endoscopy and staging of CRS, (3) radiologic imaging, (4) microbiology, (5) laboratory measures, and (6) biostatistical methods.

Orbital rhabdomyosarcoma and simulating lesions.

The appropriate diagnosis and treatment of orbital rhabdomyosarcoma requires close cooperation and communication between the radiologist, the ophthalmologist, and the medical and radiation oncologists. The clinical presentation, imaging characteristics, and staging of orbital rhabdomyosarcoma are discussed. A discussion of several important simulating lesions and their distinguishing characteristics follows.

Orbital cavernous hemangioma: role of imaging.

CT and MR imaging are particularly important in the diagnostic investigation of patients with vascular disorders of the orbit. The improved image quality of CT and MR imaging, along with dynamic CT angiography, MR angiography, MR venography, and multiphase dynamic contrast CT/MR imaging, has proven useful to delineate as well as differentiate various orbital vascular lesions. This article presents the current classification of orbital vascular disorders and describes the CT/MR imaging characteristics of orbital cavernous hemangiomas and simulating lesions.

Orbital schwannoma and neurofibroma: role of imaging.

Schwannomas are well-circumscribed ovoid masses that most commonly present in the superior orbit. Although it may be difficult to differentiate these benign masses from other orbital tumors on radiologic imaging, the CT and, in particular, the MR imaging characteristics can sometimes point to the diagnosis of a nerve sheath tumor. A definitive diagnosis can be made through correlation with histopathologic findings, however. In most cases, schwannomas have low malignant potential, and with total excision, recurrence is rare.

Orbital and ocular imaging using 3- and 1.5-T MR imaging systems.

The goal of this article is to familiarize general radiologists and clinicians (particularly ophthalmologists, neuro-ophthalmologists, neurologists, and neurosurgeons) with the recent introduction of clinical MR imaging scanners operating at a magnetic field strength of 3-T and to compare them with the more common standard scanners operating at 1.5-T. In this study, MR imaging at 3-T was found to offer superior depiction of orbital and intracranial anatomy and pathologic findings. Spin echo, high spatial resolution, T2-weighted, thin-section MR imaging sequences are especially useful and sensitive at 3-T for the evaluation of orbital, ocular, and intracranial anatomy and pathologic findings. The authors din that time-of-flight (TOF) MR angiography at 3-T surpasses the best MR angiography at 1.5-T and that two-dimensional TOF venography and three-dimensional contrast MR venography at 3-T offer superior visualization of intracranial and facial veins as compared with MR venography at 1.5-T. We believe that with further quality image production and efficient coil design, 3-T MR imaging should hold the promise of playing an important role in the diagnostic imaging evaluation of ocular, orbital, and optic pathway pathologic findings.

Anatomy and pathology of the eye: role of MR imaging and CT.

Since the development of CT and MR imaging, significant progress in ophthalmic imaging has been made. As the technology advanced and MR imaging units improved their ability in terms of spatial resolution, the role of MR imaging in ophthalmic imaging has increased accordingly. This article considers the role of MR and CT imaging in the diagnosis of selected pathologies of the eye.

Retinoblastoma and simulating lesions: role of imaging.

Although the diagnosis of retinoblastoma (Rb) is made primarily by means of clinical examination, CT and MR imaging are helpful to confirm the diagnosis, determine the extent of the intraocular tumor, and exclude extraocular or intracranial involvement. They are also valuable in differentiating Rb from lesions that simulate Rb.

Medulloepithelioma of the ciliary body and optic nerve: clinicopathologic, CT, and MR imaging features.

The definitive diagnosis of medulloepitheliomas of the ciliary body and optic nerve is made by histopathologic examination. Familiarity with rare tumors aids clinicians in accurately diagnosing this rare neoplasm. CT and MR imaging findings can be helpful, especially if the mass is confined in an area of the ciliary body without involvement of the retina. The characteristic findings of cystic changes and possible calcification are suggestive of medulloepithelioma rather than melanoma. The more common and ominous retinoblastoma shares some radiologic features with medulloepithelioma, however, and is thus often a consideration. Clinical diagnosis of medulloepitheliomas of the optic nerve and central nervous system (CNS) is more challenging. The diagnosis is often made by histopathologic examination. Lastly, coexisting CNS tumors and anomalies have been reported in association with intraocular medulloepitheliomas and should be recognized.

Imaging of Optic Neuropathy and Chiasmal Syndromes.

Optic neuropathy involves loss of visual acuity, color vision, and visual field defect with a swollen, pale, anomalous, or normal optic disc seen on fundoscopy. Chiasmal disorders classically present with gradual onset of vision loss, bitemporal hemianopsia, and occasionally, endocrinopathy if the pituitary gland and/or hypothalamus are the causes or are involved. Advance in neuroimaging, especially magnetic resonance (MR) imaging, can reveal pathologic conditions previously detected only clinically. Some entities have imaging characteristics, leading to appropriate treatment without requiring tissue biopsies. Imaging also provides disease surveillance and posttreatment assessment, with computed tomography and MR imaging being complementary to each other.