Faculty Bibliography

PURPOSE/OBJECTIVE:To evaluate existing methods of standardization by exploiting the well-known tissue characterizing property of magnetization transfer ratio (MTR) values obtained from MT imaging, and compare the tissue characterizability of standardized T2, proton density (PD), and T1 images against the MTR images. MATERIALS AND METHODS/METHODS:Image intensity standardization is a postprocessing method that was designed to correct for acquisition-to-acquisition signal intensity variations (nonstandardness) inherent in magnetic resonance (MR) images. The main idea of this technique is to deform the volume image histogram of each study to match a standard histogram, and to utilize the resulting transformations to map the image intensities into a standard scale. The method has been shown to produce a significant gain in similarity of resulting images and to achieve numeric tissue characterization. In this work we compared PD-, T2-, and T1-weighted images before and after standardization with the corresponding MT images for 10 patient MRI studies of the brain, in terms of the normalized median values on the corresponding image histograms. RESULTS:No statistically significant difference was observed between the standardized PD-, T2-, and T1-weighted images and the corresponding MTR images. However, a statistically significant difference was found between the pre- and poststandardized PD-, T2-, and T1-weighted images, and between the prestandardized PD-, T2-, and T1-weighted images and the corresponding MTR images. CONCLUSION/CONCLUSIONS:These results suggest that standardized T2, PD, and T1 images and their tissue-specific intensity signatures may be useful for characterizing disease.

The institutional review board approved the described HIPAA-compliant study, which was performed to prospectively evaluate observer performance in the detection of artificial multiple sclerosis (MS) lesions that were randomly distributed supra- and infratentorially on simulated fluid-attenuated inversion-recovery (FLAIR) magnetic resonance (MR) images obtained at different echo times (TEs). MR parametric maps were derived from mixed multi-echo inversion-recovery images obtained in a 40-year-old healthy male volunteer and in a patient with MS, both of whom gave informed consent. Pseudo-randomly distributed artificial MS lesions of varying size, number, and location were equally represented on the FLAIR images (11 000/100-200/2600 [repetition time msec/TE msec/inversion time msec]). Twelve images obtained in both regions at each of 11 TEs spaced 10 msec apart were rated by seven neuroradiologists by using a four-point scale. Observer performance in the detection of MS lesions on the FLAIR images, as estimated by using areas under the alternative free-response receiver operating characteristic curve, was highest and most consistent at the 100-msec TE, both supratentorially (93.0% +/- 8.6 [standard error of the mean]) and infratentorially (87.4% +/- 10.0).

OBJECTIVES: Head trauma is a common cause of anosmia, but diagnosis is typically late, owing to more life-threatening sequelae of the injury. Herein, we describe our workup for a case of traumatic anosmia and the magnetic resonance imaging (MRI) findings both at the time of injury and at the 18-month follow-up. METHODS: We present a case report and a review of the literature. RESULTS: A 33-year-old woman presented to our institution with a chief complaint of loss of smell and taste following an occipital blow to her head that occurred when she was hit by a car while riding a bicycle. We present the findings of MRI performed at the time of the injury and at the 18-month follow-up. We describe the clinical progression of her disease, from symptoms of parosmic and phantosmic episodes accompanied by dysgeusia to total anosmia at the 18-month follow-up. CONCLUSIONS: We advocate the use of MRI, coupled with otolaryngology consultation and formal olfactory testing, in the diagnosis, management, and counseling of patients with anosmia sustained from head injury

OBJECTIVES/OBJECTIVE:This study was conducted to evaluate magnetic resonance imaging (MRI) as an objective measure of survival of micronized acellular human dermal graft (Cymetra, LifeCell Corporation) injected into the thyroarytenoid muscle for augmentation of unilateral vocal fold paralysis. METHODS:We performed a retrospective review of MRI scans obtained in 6 patients in whom Cymetra was injected into the thyroarytenoid muscle. Gadolinium-enhanced MRI of the larynx was performed 3 days, 1 month, 8 months, 11 months, 15 months, and 21 months after injection. The survival of injected Cymetra was assessed according to information obtained from the MRI scan. Images were also obtained for 1 cm3 of reconstituted Cymetra paste. RESULTS:The identification of Cymetra in the larynx is based on its proteinaceous content. T1-weighted images of the injected material in the true vocal fold showed hyperintense foci corresponding to injected Cymetra. Hyperintense signal was also present on the T2-weighted images. Persistence of the injected Cymetra was readily detectable by MRI for as long as 11 months. CONCLUSIONS:Cymetra is a viable treatment option for vocal fold augmentation. The duration of survival of Cymetra (as long as 11 months) makes it a good option in cases in which longer survival of the injectable material is needed.

BACKGROUND: Capillary hemangiomas are benign vascular lesions that commonly present at birth or in early infancy on the face, scalp, back, or chest. The authors present an exceedingly rare case of an intracranial capillary hemangioma arising in an adult. Only 4 biopsy-proven cases have been reported in the pediatric population previous to this case report. CASE DESCRIPTION: A 31-year-old pregnant woman presented at 38 weeks of gestation with severe headaches, nausea, and vomiting. Imaging revealed an extra-axial mass lesion arising from the tentorium with both supra- and infratentorial components. The patient underwent a resection of her tumor, which was diagnosed as a capillary hemangioma by histopathologic examination. The patient required 2 further resections after the lesion exhibited a rapid regrowth from residual tumor in the left transverse sinus. The patient has remained free of disease 41 months out from her third surgery. CONCLUSIONS: Intracranial capillary hemangiomas are exceedingly rare entities, with a capability for rapid growth. When gross total resection cannot be achieved, these patients should be observed closely, and the use of adjuvant radiotherapy should be considered

BACKGROUND AND PURPOSE: The petrous and cavernous segments of the extradural internal carotid artery take a complex course through the skull base before entering the subarachnoid space distal to the cavernous sinus. Despite the protection from trauma afforded by the anatomy, the petrous and carotid internal carotid artery (ICA) segments of the vessel remains subject to disease, the most important of which are aneurysms. Aneurysms affecting the petrous portion of the vessel are extremely uncommon, and presentation with otologic symptoms is unusual. These symptoms include hearing loss, tinnitus, and life threatening hemorrhage. This article emphasizes the need for a high level of suspicion for aneurysm as a potential cause for otologic symptoms. We report and discuss three cases of petrous carotid aneurysms with otologic manifestations to increase the awareness and aid in the diagnosis and treatment of this uncommon disorder. METHODS: The medical records and imaging studies of three patients presenting to our institution with aneurysms involving the petrous internal carotid artery were reviewed. One presented with progressive bilateral sensorineural hearing loss. The next patient presented with pulsatile tinnitus. The last patient presented to the emergency room unresponsive with severe epistaxis. RESULTS: All three patients had imaging studies revealing petrous carotid aneurysms. Each patient had symptoms related to the aneurysms ranging from hearing loss, tinnitus, and life-threatening hemorrhage. CONCLUSION: Petrous carotid aneurysms are rare, and presentation with otologic symptoms is unusual. Awareness of these lesions as a cause of otologic symptoms, however, is highly important. These cases also illustrate the usefulness of endovascular treatments for aneurysms of the petrous portion of the internal carotid artery, which are extremely difficult to treat by using an open surgical approach.

This paper presents a method for the precise, accurate and efficient quantification of brain tumor (glioblastomas) via MRI that can be used routinely in the clinic. Tumor volume is considered useful in evaluating disease progression and response to therapy, and in assessing the need for changes in treatment plans. We use multiple MRI protocols including FLAIR, T1, and T1 with Gd enhancement to gather information about different aspects of the tumor and its vicinity. These include enhancing tissue, nonenhancing tumor, edema, and combinations of edema and tumor. We have adapted the fuzzy connectedness framework for tumor segmentation in this work and the method requires only limited user interaction in routine clinical use. The system has been tested for its precision, accuracy, and efficiency, utilizing 10 patient studies. The percent coefficient of variation (% CV) in volume due to operator subjectivity in specifying seeds for fuzzy connectedness segmentation is less than 1%. The mean operator and computer time required per study for estimating the volumes of both edema and enhancing tumor is about 16 min. The software package is designed to run under operator supervision. Delineation has been found to agree with the operators' visual inspection most of the time except in some cases when the tumor is close to the boundary of the brain. In the latter case, the scalp, surgical scar, or orbital contents are included in the delineation, and an operator has to exclude this manually. The methodology is rapid, robust, consistent, yielding highly reproducible measurements, and is likely to become part of the routine evaluation of brain tumor patients in our health system.

In this work, the feasibility of using T2rho weighting as an MR contrast mechanism is evaluated. Axial images of a human brain were acquired using a single-slice spin-lock T2rho-weighted pulse sequence and compared to analogous T2-weighted images of the same slice. The contrast between white matter and gray matter in T2rho-weighted images was approximately 40% greater than that from T2-weighted data. These preliminary data suggest that the novel contrast mechanism of T2rho can be used to yield high-contrast T2-like images.

Lhermitte-Duclos disease is a rare benign lesion of uncertain pathogenesis characterized by distortion of the normal cerebellar laminar cytoarchitecture. There is a characteristic MR imaging appearance of a nonenhancing mass in the cerebellar hemisphere with a striated pattern. We report two cases of Lhermitte-Duclos disease and describe findings on diffusion-weighted MR imaging.

STUDY DESIGN: A case of intradural venous varix producing a mass-like lesion in the lumbar spine is reported. OBJECTIVE: To present a rare cause of an intradural mass lesion along the cauda equina. To present radiologic findings of this entity and to offer a hypothesis for its formation. SUMMARY OF BACKGROUND DATA: Epidural venous varices have been described previously in the literature. To the authors' knowledge, no cases of intradural venous varix presenting as an intradural mass have been reported previously. MATERIALS AND METHODS: An elongated, serpentine intradural mass was discovered on routine lumbar MRI performed for investigation of the patient's radiculopathy. The patient underwent laminectomy and intradural exploration. RESULT: On surgical exploration, a serpentine, massively dilated vein was identified, which distorted the normal nerve roots. CONCLUSION: A venous varix should be considered in the differential diagnosis of an intradural lesion in the lumbar spine in the appropriate clinical setting.