Magnetic resonance imaging in the prone position and the diagnosis of tethered spinal cord.

OBJECTIVE Tethered cord syndrome (TCS) is a neurosurgical disorder with varied clinical manifestations believed to result from vascular compromise due to stretch forces on the spinal cord. Conventional supine MRI findings may include a low-lying conus medullaris, thickened or fat-infiltrated filum terminale, or lipoma; however, imaging sensitivity and specificity for tethered cord can be low. The purpose of this study was to evaluate the utility of prone MRI in the diagnosis of tethered and retethered spinal cord. METHODS Medical records were reviewed in 41 patients who underwent surgical release of tethered cord and in whom preoperative prone MRI sequences were available. Patients were divided into Group 1 (new TCS diagnosis) and Group 2 (recurrent TCS after previous untethering). Absolute conus ventral motion and motion as a percentage of canal width between supine and prone positions was measured in these 2 groups via sagittal T2-weighted sequences; these groups were compared with 30 consecutive patients (Group 3) who were classified as the normal control group. RESULTS The mean ventral motion was as follows: Group 1 (absolute: 0.5 ± 0.5 mm [range 0-2.4 mm]; canal percentage: 3.7% ± 3.9% [range 0%-16.3%]); Group 2 (absolute: 0.4 ± 0.7 mm [range 0-2.6 mm]; canal percentage: 2.2% ± 3.7% [range 0%-14.0%]); and Group 3 (absolute: 3.4 ± 1.3 mm [range 1.4-5.6 mm]; canal percentage: 22.0% ± 7.2% [range 10.5%-36.1%]). Whereas 38/41 surgically treated patients with TCS had diminished (< 10% canal width) ventral motion on preoperative MRI, 30/30 controls had > 10% canal width motion. Sensitivity and specificity were thereby calculated as 92.7% and 100%, respectively. CONCLUSIONS In the present series, prone imaging is found to be a sensitive and specific tool, and the authors believe it may have a role as supportive evidence in the diagnosis of tethered and retethered spinal cord.

Improving Clinical Information on Head CT Requisitions From the Emergency Department to Aid Interpretation and Billing Efficiency.

OBJECTIVE: The accuracy of radiologic interpretations is higher when appropriate clinical information is provided, as is the likelihood of reimbursement for the studies. The purpose of this project was to evaluate and improve the quality of clinical information provided on head CT requisitions from an urban emergency department (ED). SUBJECTS AND METHODS: In a prospective study conducted from July 2015 to May 2016, attending neuroradiologists evaluated 1100 randomly selected ED requisitions for unenhanced head CT, grading them for clinical and billing adequacy on a scale of 0-2. After acquisition of baseline data (400 studies), an intervention was performed that consisted of education of ED staff on the importance of clinical information in requisitions. A reminder slide was placed on a large screen in the ED staff working area with examples of appropriate history. Postintervention data (700 studies) were subsequently obtained. Mean scores and payment lag time before versus after the intervention were compared by Wilcoxon rank sum test. RESULTS: Statistically significant improvement was found in mean scores after the intervention for both clinical (1.32 to 1.43, p = 0.003) and billing (1.64 to 1.74, p = 0.02) adequacy categories. The percentage of studies with a score of 2 increased in both categories, and the percentages of 0 and 1 scores declined. There was a 21.1-day decrease in payment lag time (from 75.8 to 54.7 days, p < 0.0001). CONCLUSION: The quality of clinical information provided on imaging requisitions by ED faculty and residents improved after a fairly simple intervention. Billing efficiency improved, and payment lag time decreased substantially.

Building a Culture of Continuous Quality Improvement in an Academic Radiology Department.

As we enter a new era of health care in the United States, radiologists must be adequately prepared to prove, and continually improve, our value to our customers. This goal can be achieved in large part by providing high-quality services. Although quality efforts on the national and international levels provide a framework for improving radiologic quality, some of the greatest opportunities for quality improvement can be found at the departmental level, through the implementation of total quality management programs. Establishing such a program requires not only strong leadership and employee engagement, but also a firm understanding of the multiple total quality management tools and continuous quality improvement strategies available. In this article, we discuss key tools and strategies required to build a culture of continuous quality improvement in an academic department, based on our experience.

Neoplastic cauda equina syndrome: a neuroimaging-based review.

Cauda equina syndrome refers to dysfunction of the cauda equina, the collection of ventral and dorsal lumbar, sacral and coccygeal nerve roots that surround the filum terminale. This most commonly occurs as a result of compression by a herniated lumbosacral disc. However, the syndrome may also complicate metastatic cancer or a primary neoplasm within or infiltrating the spinal canal. An accurate and timely diagnosis is critical to avoid irreversible loss of neurological function. The clinician and radiologist must therefore be aware of the many possible causes to guide timely management. Here we review the diverse neoplastic causes affecting the cauda equina nerve roots from a neuroimaging-based perspective. We divide them by location into intramedullary neoplasms at the conus (such as astrocytoma), intradural-extramedullary neoplasms (such as schwannoma and leptomeningeal metastases) and extradural neoplasms (such as spinal metastases from systemic neoplasms). We also discuss the clinical features associated with cauda equina tumours, with special focus on cauda equina syndrome.

MRI Findings After Surgery for Chiari Malformation Type I.

OBJECTIVE: Surgery plays an important role in the management of Chiari I malformation. The purpose of this article is to review expected and unexpected MRI findings after the various types of surgery performed during the treatment of Chiari I malformation and associated abnormalities. CONCLUSION: Familiarity with optimal MRI techniques and findings is important when evaluating postoperative changes after treatment of Chiari I malformation.

Acute spinal cord compression: CQI framework increases resource efficiency while promoting delivery of high-quality care.

PURPOSE: Literature reports indicate that advanced imaging is overutilized, especially in the emergency setting. At our institution, stat spinal MRI for suspected acute spinal cord compression (ASCC) was perceived to be excessively utilized. A continuous quality improvement process was employed to investigate this trend and improve the efficiency of this diagnosis. METHODS: Spine imaging in patients with suspected ASCC was retrospectively evaluated for appropriateness of indications and quality of imaging. Based on the results, a new institutional policy for ordering MR for suspected ASCC was implemented, concurrent with development of a new screening spine MRI protocol. Subsequently, indications, efficacy, and imaging utilization of the new strategy were analyzed for improved operational effectiveness. RESULTS: The initial retrospective study demonstrated only a 1.4% positive rate of ASCC as well as image-quality degradation due to patient motion resulting from prolonged scan times. Based on these results, a new institutional policy for ordering stat ASCC spine MRI was instituted with an updated screening MRI protocol. This policy resulted in a positive rate of ASCC of 4.4%, and decreased scan time by 50%-70%, while preserving diagnostic image quality and decreasing resource utilization. CONCLUSIONS: As suspected, stat spinal MRI for ASCC was excessively utilized at our institution. The study demonstrated that systemic improvements regarding this issue can be achieved by using a multidisciplinary approach and following a continuous quality improvement methodology. A new MRI protocol for identification of ASCC was found to preserve image quality and diagnostic confidence, while simultaneously decreasing scan time and use of valuable health care resources.

High-resolution time-resolved contrast-enhanced 3D MRA by combining SENSE with keyhole and SLAM strategies.

Sensitivity encoding (SENSE) was combined with keyhole and selective line acquisition mode (SLAM) techniques to acquire a time series of images during contrast passage. The acquisition speed of the dynamic time frames was improved by a factor of 8 in total. The high spatial frequencies were sampled during the steady state and combined with the dynamic time frames to construct a series of high-resolution time-resolved contrast-enhanced 3D images. Filtered temporal correlation analysis was used to separate the arteries and veins.

Diagnostic fidelity of the Z-buffer segmentation algorithm: preliminary assessment based on intracranial aneurysm detection.

We have developed an algorithm known as the Z-buffer segmentation (ZBS) algorithm for segmenting vascular structures from 3D MRA images. Previously we evaluated the accuracy of the ZBS algorithm on a voxel level in terms of inclusion and exclusion of vascular and background voxels. In this paper we evaluate the diagnostic fidelity of the ZBS algorithm. By diagnostic fidelity we mean that the data preserves the structural information necessary for diagnostic evaluation. This evaluation is necessary to establish the potential usefulness of the segmentation for improved image display, or whether the segmented data could form the basis of a computerized analysis tool. We assessed diagnostic fidelity by measuring how well human observers could detect aneurysms in the segmented data sets. ZBS segmentation of 30 MRA cases containing 29 aneurysms was performed. Image display used densitometric reprojections with shaded surface highlighting that were generated from the segmented data. Three neuroradiologists independently reviewed the generated ZBS images for aneurysms. The observers had 80% sensitivity (90% for aneurysms larger than 2mm) with 0.13 false positives per image. Good agreement with the gold standard for describing aneurysm size and orientation was shown. These preliminary results suggest that the segmentation has diagnostic fidelity with the original data and may be useful for improved visualization or automated analysis of the vasculature.

A methodology and implementation for annotating digital images for context-appropriate use in an academic health care environment.

Use of digital medical images has become common over the last several years, coincident with the release of inexpensive, mega-pixel quality digital cameras and the transition to digital radiology operation by hospitals. One problem that clinicians, medical educators, and basic scientists encounter when handling images is the difficulty of using business and graphic arts commercial-off-the-shelf (COTS) software in multicontext authoring and interactive teaching environments. The authors investigated and developed software-supported methodologies to help clinicians, medical educators, and basic scientists become more efficient and effective in their digital imaging environments. The software that the authors developed provides the ability to annotate images based on a multispecialty methodology for annotation and visual knowledge representation. This annotation methodology is designed by consensus, with contributions from the authors and physicians, medical educators, and basic scientists in the Departments of Radiology, Neurobiology and Anatomy, Dermatology, and Ophthalmology at the University of Utah. The annotation methodology functions as a foundation for creating, using, reusing, and extending dynamic annotations in a context-appropriate, interactive digital environment. The annotation methodology supports the authoring process as well as output and presentation mechanisms. The annotation methodology is the foundation for a Windows implementation that allows annotated elements to be represented as structured eXtensible Markup Language and stored separate from the image(s).

The need for phase-encoding flow compensation in high-resolution intracranial magnetic resonance angiography.

PURPOSE: To demonstrate that the time delay between phase and frequency encoding and the presence of pulsatile blood flow in high-resolution time-of-flight (TOF) imaging of the intracranial arteries (especially near the circle of Willis) can distort the appearance of blood vessels and result in a cross-hatch-appearing artifact in surrounding tissue. MATERIALS AND METHODS: Two techniques to reduce the artifact, tri-directional flow compensation (3DFC) and elliptical-centric (EC) phase-encoding order, are investigated in five volunteer studies. RESULTS: 3DFC eliminates the pulsation-related artifacts and the vessel distortion. A residual amplitude variation artifact is observed. EC phase encoding nearly eliminates the pulsatile motion-related artifact, but it does not eliminate vessel distortion. CONCLUSION: The combination of 3DFC and EC phase encoding appears to provide the greatest artifact reduction in the five volunteer studies performed.

CD/DVD technology.

For storage of large amounts of data, there are many options to consider, including both CD and DVD methods. Given that these are now becoming very cheap alternatives, and that we work in a specialty which generates large volumes of digital data, it is now obvious why CD and DVD burning is of interest to radiologists. These technologies can most assuredly be of great benefit to both our professional and personal lives.

Magnetoencephalographically directed review of high-spatial-resolution surface-coil MR images improves lesion detection in patients with extratemporal epilepsy.

PURPOSE: To determine whether (a) interictal magnetoencephalographic (MEG) epileptiform activity corresponds to anatomic abnormalities at magnetic resonance (MR) imaging, (b) high-spatial-resolution MR imaging depicts lesions in regions without MEG spike activity, (c) MEG-directed review of high-spatial-resolution MR images enables detection of abnormalities not apparent on conventional MR images, and (d) MEG information results in a greater number of diagnosed lesions at re-review of conventional MR images. MATERIALS AND METHODS: Twenty patients with neocortical epilepsy were evaluated with MEG, conventional brain MR imaging with a head coil, and high-spatial-resolution MR imaging with either a surface coil (n = 17) or a high-spatial-resolution birdcage coil (n = 3). Abnormal MEG foci were compared with corresponding anatomic areas on conventional and high-spatial-resolution MR images to determine the presence (concordance) or absence (discordance) of anatomic lesions corresponding to foci of abnormal MEG activity. RESULTS: Forty-four epileptiform MEG foci were identified. Twelve foci (27%) were concordant with an anatomic abnormality at high-spatial-resolution MR imaging, and 32 foci (73%) were discordant. Results of high-spatial-resolution MR imaging were normal in eight patients, and 23 lesions were detected in the remaining 12 patients. Twelve lesions (52%) were concordant with abnormal MEG epileptiform activity, and 11 (48%) were discordant (ie, there was normal MEG activity in the region of the anatomic abnormality). At retrospective reevaluation of conventional MR images with MEG guidance, four occult gray matter migration lesions that had initially been missed were observed. An additional patient with MEG-concordant postoperative gliosis was readily identified with high-spatial-resolution MR images but not with conventional MR images. CONCLUSION: Review of MEG-localized epileptiform areas on high-spatial-resolution MR images enables detection of epileptogenic neocortical lesions, some of which are occult on conventional MR images.

Improved efficiency in double-inversion fast spin-echo imaging.

Double-inversion fast spin-echo (FSE) pulse sequences can be designed to provide excellent suppression of blood signal in black-blood MRI. However, because a nonselective inversion is used, these sequences typically have been highly inefficient. In this work it is demonstrated that the efficiency of double-inversion sequences can be greatly improved by a form of interleaving in which all of the slices to be imaged in a single pass are reinverted each time a signal is obtained from any single slice. To date, several studies have demonstrated a high level of blood suppression with these more efficient techniques.