Texture-Based Analysis of 100 MR Examinations of Head and Neck Tumors - Is It Possible to Discriminate Between Benign and Malignant Masses in a Multicenter Trial?

AIM: To evaluate whether texture-based analysis of standard MRI sequences can help in the discrimination between benign and malignant head and neck tumors. MATERIALS AND METHODS: The MR images of 100 patients with a histologically clarified head or neck mass, from two different institutions, were analyzed. Texture-based analysis was performed using texture analysis software, with region of interest measurements for 2 D and 3 D evaluation independently for all axial sequences. COC, RUN, GRA, ARM, and WAV features were calculated for all ROIs. 10 texture feature subsets were used for a linear discriminant analysis, in combination with k-nearest-neighbor classification. Benign and malignant tumors were compared with regard to texture-based values. RESULTS: There were differences in the images from different field-strength scanners, as well as from different vendors. For the differentiation of benign and malignant tumors, we found differences on STIR and T2-weighted images for 2 D, and on contrast-enhanced T1-TSE with fat saturation for 3 D evaluation. In a separate analysis of the subgroups 1.5 and 3 Tesla, more discriminating features were found. CONCLUSION: Texture-based analysis is a useful tool in the discrimination of benign and malignant tumors when performed on one scanner with the same protocol. We cannot recommend this technique for the use of multicenter studies with clinical data. KEY POINTS: 2 D/3 D texture-based analysis can be performed in head and neck tumors. Texture-based analysis can differentiate between benign and malignant masses. Analyzed MR images should originate from one scanner with an identical protocol.

Intratympanic Contrast in the Evaluation of Menière Disease: Understanding the Limits.

BACKGROUND AND PURPOSE: Studies describing endolymphatic hydrops in Menière disease after off-label intratympanic gadolinium-based contrast have been limited by long acquisition times. We aimed to demonstrate the feasibility of post-intratympanic imaging on a 3T MR imaging system within a clinically tolerable acquisition time and to address potential pitfalls in acquisition or interpretation. MATERIALS AND METHODS: FDA Investigational New Drug 115,342 and institutional review board approval were obtained for intratympanic injection of 8-fold diluted Gd-DTPA into the more symptomatic ear of 6 adults with Menière disease. 3T MR imaging was performed using a 3-inch surface coil before and up to 28 hours after injection using FLAIR to define the nonenhancing endolymphatic space within the enhancing perilymph. Variable FLAIR TI images were used to determine the impact of fluid-suppression on interpretation. Image quality was assessed for perilymphatic and extralabyrinthine contrast enhancement, definition of endolymphatic anatomy, and other anatomic variants or pathologic findings. RESULTS: The surface coil afforded 0.375 × 0.375 mm in-plane FLAIR resolution in <4 minutes 30 seconds, sufficient to perceive the nonenhancing spiral lamina, interscalar septa, and endolymphatic structures. Coronal views highlighted a potential interpretation pitfall of vestibular endolymphatic distention overestimation due to partial volume averaging. Varying FLAIR TI resulted in visible changes in the perception of the cochlear endolymphatic space. CSF enhancement was detectable at the internal auditory canal fundus on the injected side in half of the patients, which may confound interpretation. CONCLUSIONS: Using a surface coil preserves high resolution within a clinically acceptable acquisition time. Pitfalls remain regarding the interpretation of these images and optimizing protocols across platforms in the absence of a clear internal reference for standardization.

Diffusion-weighted imaging of malignant ocular masses: initial results and directions for further study.

BACKGROUND AND PURPOSE: Ocular masses represent a spectrum of malignant tumors and benign lesions that are sometimes difficult to detect and differentiate by conventional imaging techniques. The aim of this study was to characterize a group of malignant ocular masses with DWI, with the goals of establishing reference data and identifying potential clinical applications for improved noninvasive characterization. MATERIALS AND METHODS: With institutional review board approval, 26 malignant ocular masses in 22 patients were retrospectively analyzed. Five masses were excluded from further analysis due to nonvisualization. Fifteen retinoblastomas, 5 melanomas, and 1 highly undifferentiated carcinoma were studied. Region-of-interest analysis was performed, and the ADC of each mass was measured and also compared with a normal-appearing thalamus. Lesion thickness was measured, the amount of susceptibility artifact was qualitatively assessed and graded, and the correlation between these factors and retinoblastoma ADC was determined. RESULTS: Retinoblastomas had an ADC of 0.93 ± 0.3 × 10(-3) mm(2)/s (mean). Melanoma had an ADC of 1.18 ± 0.16 × 10(-3) mm(2)/s. The ADC of retinoblastoma was strongly inversely correlated with lesion thickness, likely representing the effect of partial volume averaging. ADC was not correlated with the amount of subjectively determined susceptibility artifact. CONCLUSIONS: Malignant ocular tumors were consistently characterized with DWI, though with limitations due to artifact and partial volume averaging. Additional description of DWI of ocular masses and further technical improvements may lead to a clinical role for DWI.

Anterior-segment retinoblastoma mimicking pseudoinflammatory angle-closure glaucoma: review of the literature and the important role of imaging.

A 7-year-old boy presented with angle-closure glaucoma, initially presumed to be idiopathic. A ciliary body mass was later detected on MR imaging, suggestive of medulloepithelioma but pathologically proved to be diffuse infiltrating retinoblastoma. We discuss the patient management and review the literature, with emphasis on the role of CT and MR imaging in evaluating pediatric angle-closure glaucoma and in influencing the management of patients with retinoblastoma and medulloepithelioma.

MR imaging of orbital inflammatory syndrome, orbital cellulitis, and orbital lymphoid lesions: the role of diffusion-weighted imaging.

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.

Acute optic nerve infarction demonstrated by diffusion-weighted imaging in a case of rhinocerebral mucormycosis.

SUMMARY: A 60-year-old woman developed right-eye vision loss secondary to rhinocerebral mucormycosis. Routine MR imaging sequences including enhanced MR imaging showed normal optic nerves, but a diffusion-weighted sequence and apparent diffusion coefficient maps revealed markedly restricted diffusion in the right optic nerve. This MR imaging abnormality of optic nerve infarction due to mucormycosis has not been reported previously.

Analysis of magnetic resonance imaging-based blood and cerebrospinal fluid flow measurements in patients with Chiari I malformation: a system approach.

OBJECT: A pilot study was performed to assess noninvasively the change in intracranial compliance (ICC) and intracranial pressure (ICP) in patients with Chiari I malformation who undergo foramen magnum decompression. The working hypothesis was that the main effect of the decompressive surgery is a change in ICP. Noninvasive cine phasecontrast magnetic resonance (MR) imaging is a motion-sensitive dynamic MR imaging technique that allows for visualization and quantitation of tissue motion and flow. The authors' group has used dynamic phase-contrast MR imaging to visualize and quantify pulsatile blood and cerebrospinal fluid (CSF) flow in the craniospinal system. METHODS: A system approach has been used to characterize the hemodynamic-hydrodynamic coupling in the craniospinal system and to derive measures for ICC and ICP. Magnetic resonance imaging-based ICC and ICP values are derived from the ratio of the volume and pressure changes that occur naturally during each cardiac cycle. The authors conducted a prospective study of four patients, three of whom were studied before and after decompressive surgery; significant change in MR imaging-derived ICC and ICP values was documented in only one of the three surgically treated patients. A significant change in the dynamics of the intracranial volume change (ICVC) during the cardiac cycle, however, was observed in all three patients. In healthy individuals the ICVC waveform usually consists of the following sequence: monotonic increase in intracranial volume (ICV) during the systolic phase due to increased blood inflow, monotonic decrease in ICV caused by the onset of CSF outflow into the spinal canal, and increase in the venous outflow. A nonmonotonic decline in the ICVC waveform has been observed in all patients with headaches, and a relatively normal waveform was found in those without headaches or whose headaches were resolved or alleviated by the surgery. A "partial-valve" mechanism is proposed as an explanation for the abnormal ICVC dynamics. The monotonic decline in ICVC is interrupted by a "premature" reduction in the CSF outflow. This may be caused by a displacement of the hindbrain into the cervical spinal canal during the systolic phase. This obstructs the CSF flow at the later part of the systolic phase such that the ICV does not continue its gradual decline. Postsurgery, the ICVC waveforms presented a more normal-appearing ICVC dynamics profile. CONCLUSIONS: Magnetic resonance imaging measurement of transcranial CSF and blood flow may lead to a better understanding of the pathophysiology of Chiari malformations and may prove to be an important diagnostic tool for guiding for the treatment of patients with Chiari I malformation.

Pneumosinus dilatans of the sphenoid sinus presenting with visual loss.

OBJECTIVE: To report 3 cases of pneumosinus dilatans of the sphenoid sinus associated with visual loss. MATERIALS AND METHODS: Retrospective case series describing history of visual loss, visual examination, visual field deficits, and radiologic imaging. RESULTS: Three patients developed visual loss associated with pneumosinus dilatans of the sphenoid sinus. CONCLUSIONS: Pneumosinus dilatans of the sphenoid sinus is a rare disorder that should be considered in patients presenting with unexplained visual loss.

Glomus faciale, glomus jugulare, glomus tympanicum, glomus vagale, carotid body tumors, and simulating lesions. Role of MR imaging.

In summary, MR imaging characteristics of a case of paraganglioma of the facial nerve are reported. The relationship of paragangliomas and the chromaffin system have been discussed. There are many reports of cases of synchronous paragangliomas and pheochromocytomas. These reports, along with simultaneous involvement in familial MEN syndromes, and the common embrylogic origin (neural crest) and similar histopathologic relationships between paragangliomas and pheochromocytoma, all support the fact that they are part of the chromaffin system.

Effect of interference of metallic objects on interpretation of T1-weighted magnetic resonance images in the maxillofacial region.

PURPOSE: Metallic objects produce artifacts on magnetic resonance (MR) images. However, studies on typical dental materials in this area are scant. This study was conducted to describe and measure the magnitude of such artifacts. MATERIALS AND METHODS: Samples of various dental materials (dental gold, amalgam, stainless steel, titanium, silver-palladium, and vitallium) were embedded in bovine muscle and then subjected to T1-weighted MR imaging. The materials were of the typical morphology and composition encountered in routine maxillofacial practice. The MR artifacts were measured and compared with the original specimen measurements. RESULTS: All metallic objects were found to produce artifacts and to interfere with the interpretation of MR images. Artifacts were most pronounced in the central plane of the object. Gold produced the greatest artifact, and amalgam produced the least. CONCLUSION: Because metals commonly used in the maxillofacial region all produce artifacts on MR images, avoidance measures should be used to minimize the effect of these artifacts.

Otogenic intracranial inflammations: role of magnetic resonance imaging.

The clinical course of acute otitis media is usually short, and the process terminates because of the host's immune system, the infection-resistant properties of the mucosal linings, and the susceptibility of the major organisms (beta-hemolytic streptococcus or pneumococcus) to penicillin. However, a small proportion (1% to 5%) of untreated or inadequately treated patients may experience complications. Prior to the development of an intracranial complication of otomastoiditis, warning symptoms or signs may be evident; these include severe earache, severe headache, vertigo, chills and fever, and meningeal symptoms and signs. Increasing headache, particularly temporoparietal headache near the affected ear, often indicates an impending intracranial complication. This symptom, often the only indication of an epidural abscess, demands prompt investigation and medical and surgical intervention. In our experience, computed tomography (CT) permits accurate diagnosis of acute coalescent or latent (masked) mastoiditis and its associated complications. However, magnetic resonance imaging (MRI) remains the study of choice to evaluate otogenic intracranial complications. This article demonstrates the important role of MRI in diagnosing various stages of acute otomastoiditis and its associated complications.

Role of magnetic resonance imaging and diagnostic and interventional angiography in vascular and neoplastic diseases of the skull base associated with vestibulocochlear symptoms.

There are many vascular and neoplastic diseases as well as normal variants that produce the vestibulocochlear symptoms of pulsatile tinnitus, hearing loss, dizziness, and ataxia. Magnetic resonance imaging may be diagnostic, and magnetic resonance angiography/magnetic resonance venography have added to the ability of magnetic resonance to image vascular abnormalities. The extent of neoplasms is accurately assessed and complication of vascular lesions are clearly seen. However, detailed vascular anatomy requires high-quality selective angiography. This enables optimal treatment planning. Endovascular therapeutic intervention has a major role to play in conjunction with surgery of skull base lesions and may be curative in certain conditions, avoiding major surgical procedures. The interventionalist, however, must have an excellent knowledge of the external carotid circulation and all of its potential communications with the internal circulation to avoid serious embolic complications.

Congenital sensorineural hearing loss and enlarged endolymphatic sac and duct: role of magnetic resonance imaging and computed tomography.

During the past 20 years, there have been significant advances in cochlear implants as the treatment of choice for profoundly hearing-impaired children. The increasing application of cochlear implant has brought with it an increase in the investigational use of computed tomography and magnetic resonance imaging. In this article, the author reviews (a) the anatomy and embryology of the inner ear, (b) the pathological changes associated with congenital sensorineural hearing loss (SNHL), and (c) the spectrum of imaging findings in patients with SNHL.

Magnetic resonance imaging of the normal temporal bone.

Recent advances in magnetic resonance imaging (MRI) technology has allowed the development of imaging sequences tailored to the assessment of exquisite anatomic detail of the temporal bone structures. This article describes MRI of the normal temporal bone anatomy, with emphasis on common anatomic variants and clinically relevant structures.

Magnetic resonance imaging for evaluation of otic labyrinth pathology.

The auditory (cochlear) labyrinth, the cochlea, holds the hearing sensory receptors. The vestibular labyrinth contains the sensory receptors for balance, which lie in the three semicircular canals and in the otolithic organs (the saccule and utricle). Pure tone audiometry and brain stem evoked audiometry can help to differentiate a peripheral cochlear disorder from central lesion. The type of nystagmus, severity of postural instability, and neurological evaluation can help to differentiate a peripheral vestibular disorder from a central vestibular lesion. The decision whether to perform an appropriate imaging such as brain imaging versus labyrinthine imaging depends on the clinical and paraclinical information provided to the radiologist by the neurotologist, neurologist, or other clinicians. The magnetic resonance imaging characteristics of peripheral cochlear and vestibular lesions are the main focus of this article.

Value of imaging in disorders of the facial nerve.

Imaging of the facial nerve has proved its usefulness to physicians in the evaluation of pathological conditions of this nerve. Magnetic resonance imaging (MRI) of the facial nerve should always be obtained selectively and should include the parotid gland in case of peripheral facial nerve palsy. Gadolinium-DTPA contrast pulse sequence is the most informative MRI study for evaluation of facial nerve pathology. This article reviews the imaging anatomy of the facial nerve and describes the clinical features and MR characteristics of common disorders of the facial nerve.

Bilateral orbital emphysema from compressed air injury.

PURPOSE: To describe a patient who developed bilateral subconjunctival and orbital emphysema after an automobile tire explosion. METHOD: Case report. RESULTS: A 60-year-old man sustained bilateral ocular injury after a tire explosion. Ophthalmic examination disclosed bilateral subconjunctival air, with no visible conjunctival laceration. Computed tomography showed orbital emphysema, with no evidence of orbital fracture. Follow-up examination 2 weeks after the injury disclosed resolution of the subconjunctival air. Best-corrected visual acuity in the right eye was decreased after the explosion but improved to the baseline level of 20/40 2 weeks after the injury. CONCLUSION: Subconjunctival and orbital emphysema can occur from high-pressure air injury in the absence of an obvious entry site.

Optic nerve sheath meningiomas. Role of MR imaging.

Optic nerve meningiomas usually are seen in middle-aged and elderly women, and present as a slowly progressing axial proptosis and loss of vision. CT and MR imaging are the most valuable diagnostic tools to evaluate these tumors. This article reviews the MR imaging and CT characteristics of optic nerve sheath meningiomas and discusses features that may distinguish optic nerve sheath meningiomas from simulating lesions.

Sarcoidosis of the eye, orbit, and central nervous system. Role of MR imaging.

Sarcoidosis, a systemic disease of unknown cause, frequently involves the eye, orbit, and central nervous system. The MR imaging findings of orbital and optic pathway sarcoidosis may closely resemble several other orbital and intracranial diseases. This article reviews MR imaging findings of sarcoidosis when it involves the eye, orbit, and visual pathways. Careful review of MR findings and other neuroimaging findings and clinical characteristics will reduce the incidence of mistaking optic nerve and chiasmal sarcoidosis for meningioma or glioma.