Cholesteatoma imaging using modified echo-planar diffusion-weighted magnetic resonance imaging.

INTRODUCTION: Imaging of cholesteatomas can be useful especially in cases of recurrent disease. Computed tomography scans have been recommended before primary surgery, but cholesteatoma tissue looks similar to inflammatory tissue. Diffusion-weighted magnetic resonance imaging is both sensitive and specific in detecting cholesteatoma, which appears as a bright signal on a dark background. Non-echo-planar diffusion-weighted magnetic resonance imaging is superior to routine echo-planar diffusion-weighted magnetic resonance imaging as it minimises susceptibility artefacts; however, the addition of this facility involves expensive magnetic resonance scanner upgrading. METHOD: To avoid the cost of such upgrading, we modified our echo-planar diffusion-weighted magnetic resonance imaging parameters and then scanned 15 consecutive cases of suspected cholesteatoma or suspected recurrent cholesteatoma. RESULTS: Imaging results correlated well with clinical and/or operative findings. CONCLUSION: These results indicate that software adjustments can enable echo-planar diffusion-weighted magnetic resonance imaging to detect cholesteatomas reliably, and as effectively as non-echo-planar diffusion-weighted magnetic resonance imaging. This discovery has the potential to facilitate reliable delayed post-operative screening of canal wall up mastoidectomies, avoiding the need for a 'second look' procedure.

Cranial MRI of small rodents using a clinical MR scanner.

Increasing numbers of small animal models are in use in the field of neuroscience research. Magnetic resonance imaging (MRI) provides an excellent method for non-invasive imaging of the brain. Using three-dimensional (3D) MR sequences allows lesion volumetry, e.g. for the quantification of tumor size. Specialized small-bore animal MRI scanners are available for high-resolution MRI of small rodents' brain, but major drawbacks of this dedicated equipment are its high costs and thus its limited availability. Therefore, more and more research groups use clinical MR scanners for imaging small animal models. But to achieve a reasonable spatial resolution at an acceptable signal-to-noise ratio with these scanners, some requirements concerning sequence parameters have to be matched. Thus, the aim of this paper was to present in detail a method how to perform MRI of small rodents brain using a standard clinical 1.5 T scanner and clinically available radio frequency coils to keep material costs low and to circumvent the development of custom-made coils.

Asymmetric sensorineural hearing loss evaluation with T2 FSE-MRI in a public hospital.

CONCLUSIONS: T2-weighted fast-spin echo magnetic resonance imaging (MRI) can be an economically beneficial protocol for screening patients with asymmetric sensorineural hearing loss without other neurologic findings in a public hospital population. OBJECTIVE: The goal of this study was to determine if fast spin echo T2 MRI is similar to gadolinium-enhanced MRI in evaluating asymmetric sensorineural hearing loss in a county hospital population. PATIENTS AND METHODS: This was a retrospective chart review of all outpatients seen at a public hospital, comprising patients with no other cranial nerve findings who underwent gadolinium-enhanced MRI of the internal auditory canal and brain between January 2002 and September 2003. Patients with >15 dB difference in hearing at one frequency or 10 dB hearing difference at two frequencies underwent gadolinium-enhanced MRI scan with FSE T2 sequence as part of the examination protocol. RESULTS: A total of 146 patients were identified who met all the inclusion criteria for the study. Of the 146 MRI scans performed, abnormalities were seen on 71 of them, the majority of which were inconsequential. No acoustic neuromas were identified in our study population. Cost savings of over 100,000 dollars would have been realized if only T2 FSE protocols had been used.

Dynamic magnetic resonance guided treatment of developmental dysplasia of the hip.

This study demonstrates the feasibility and advantages of near real-time, multiplanar, dynamic magnetic resonance image-assisted treatment of patients with developmental dysplasia of the hip. Pathoanatomy and dynamic blocks to reduction are visualized with anatomic clarity not otherwise possible. Continuous imaging allows accurate assessment and maintenance of optimum positioning throughout the casting procedure. Patient charges for this new technique are less than standard methods of treatment, and the child receives no ionizing radiation.

Future cost-effective MRI will be at high field.

The most cost effective MR imaging system is the one that provides the highest quality images (allowing the earliest possible diagnosis), the largest number of applications (allowing bundling of services and one-stop shopping for consumers), and the highest throughput (should it become necessary to scan a large number of patients in a capitated world). When all other parameters are normalized (eg, the skill and training of the radiologist and technologist as well as the RF, computer, and gradient subsystems), high field provides faster, higher resolution, thinner slice, and higher contrast MR images than low field. For these reasons, high field MRI will remain more cost effective than its lower field counterparts in the future.