Matthew S. Parsons

Temporal association of annular tears and nuclear degeneration: lessons from the pediatric population.

BACKGROUND AND PURPOSE: Studies done mainly in adults have shown an association between annular tears and nuclear degeneration. We wanted to study this association in the pediatric population to better understand the natural history of disk degeneration in its early stages. We hypothesized that this association is discernible even at a young age and that annular tears precede nuclear degeneration. MATERIALS AND METHODS: Twenty-six children with back pain and known disk pathology were identified from our radiology report data base. Two neuroradiologists independently evaluated T12 through S1 intervertebral disks in these images. One reader evaluated the disks for the presence and type of annular tears. The other reader graded the signal intensity of the disks on an ordinal scale and the extent of disk degeneration on the Pfirrmann scale. Mean degeneration and signal-intensity grades were compared for disks with radial tears, disks with nonradial tears, and disks without annular tears. RESULTS: Fifty-six disks had radial tears. These demonstrated significantly higher nuclear degeneration grades and greater signal-intensity loss than disks with nonradial tears or disks with no annular tears. About one third (30.3%) of the disks with radial tears had a normal nuclear signal intensity. Only 3% of disks with a signal-intensity grade of ≥3 had an intact annulus. CONCLUSIONS: Nuclear degeneration in children is associated with radial annular tears and rarely occurs in the absence of annular tears.

Temporal interactions of degenerative changes in individual components of the lumbar intervertebral discs: a sequential magnetic resonance imaging study in patients less than 40 years of age.

Study Design. A retrospective longitudinal observational study using baseline and follow-up magnetic resonance imaging (MRI). Objective. To study the natural history of disc degeneration, focusing on the significance of changes affecting the individual components of the intervertebral disc. Summary of Background Data. The natural history of the degenerative disc disease is poorly understood. Focusing on the relative prevalence, temporal evolution, and interactions of pathology in the anulus fibrosus, nucleus pulposus, and the end plates can help in better understanding of this process. Methods. MRIs of the lumbar spine in 63 patients, obtained at a mean interval of 30 months, were evaluated independently by two neuroradiologists to assess the temporal evolution of degeneration changes in 378 discs between T12 through S1 segments. In addition, a direct side-by-side comparison of two studies was also performed. Statistical analysis was performed to assess the association between the degeneration of individual disc components and to find the predictors of future degeneration. Results. Radial anular tears and end plate defects were associated with worse nuclear degeneration at the time of the initial study. Both end plate defects and nuclear degeneration were rare in the absence of radial tears. Multiple nominal logistic regression analysis showed that radial tears and herniation at the time of the initial study, along with the duration between the two imaging studies were the significant predictors of worsening nuclear degeneration. Age, sex, and the segmental disc level did not show any significant association with temporal progression of nuclear degeneration. Conclusion. Radial tears and herniation are significant predictors of progressive nuclear degeneration, which was not seen in the absence of radial tears. End plate defects also frequently occur before nuclear degeneration but rarely in the absence of anular tears.

A Two-Tiered Approach to MRI for Hearing Loss: Incremental Cost of a Comprehensive MRI Over High-Resolution T2-Weighted Imaging

OBJECTIVE The objective of our study was to compare the cost-effectiveness of two approaches to using MRI for the evaluation of patients with hearing loss. MATERIALS AND METHODS We developed a decision tree to compare the cost-effectiveness of conventional MRI with that of a proposed two-tiered model in which an initial 3D T2-weighted imaging examination was used to determine the need for comprehensive MR scanning. Three radiologists independently and blindly reviewed the 3D T2-weighted images acquired as part of the comprehensive MR examinations of 256 patients with hearing loss to assess the diagnostic efficacy of the two-tiered approach. Costs were defined in terms of both the scanner utilization time for the imaging facility and the dollar amount for payers. Effectiveness was defined in terms of the ability to correctly detect the presence or absence of disease. RESULTS The conventional approach was less cost-effective, with a baseline incremental cost-effectiveness ratio (ICER) of 27,299 minutes of scanner utilization per unit increase in effectiveness. Assuming a 50% reduction in the reimbursement of the technical component from the current level by the Centers for Medicare & Medicaid Services, this result reflected an ICER of

Two-Tiered Approach to MRI for Headache: A Cost-Effective Way to Use an Expensive Technology

258,664 per unit increase in effectiveness. The results of a sensitivity analysis showed the robustness of the cost-effectiveness of the two-tiered imaging approach in a variety of scenarios that reflect differences in scanning practices and possible differences in recall rates. The conventional imaging approach was absolutely dominated by the two-tiered approach in the scenarios created to reflect the expected range of prevalence of disease. CONCLUSION A two-tiered approach to MRI provides a more cost-effective alternative to the current approach of using a comprehensive MRI examination without and with contrast material to evaluate patients with hearing loss.

Effect of Spatial Resolution of T2-Weighted Imaging on Diagnostic Efficacy of MRI in Detection of Papilledema

OBJECTIVE The purpose of this study was to compare the diagnostic efficacy and cost implications of a proposed two-tiered approach to MRI in patients with headache. MATERIALS AND METHODS We identified 245 consecutive patients with headache using MRI studies performed at a tertiary care facility between October 2009 and July 2011. Three radiologists prospectively used FLAIR sequences from these MR studies to diagnose underlying abnormality or to identify the need for a comprehensive MRI study. We compared the diagnostic efficacy and the cost implications of such a two-tiered approach with those of conventional MRI from the perspectives of the payer, the patient, and the imaging facility. RESULTS The sensitivity and specificity for two-tiered (83.3% and 100%, respectively) and conventional (91% and 97.8%, respectively) MRI approaches were not significantly different. Assuming a 50% reduction in the payment for the initial limited MRI performed as a first step of the two-tiered approach, this approach would have resulted in 44.8% savings to the payer. A substantial reduction in the scanner utilization time from 4168 minutes to 1249 minutes for the two-tiered approach would have enabled increased throughput at the imaging facility. Although 27 (11%) patients would have been recalled for a comprehensive MRI study in the two-tiered approach, the average time spent in the scanner by each patient would have been less for the two-tiered approach (5.1 minutes vs 17.0 minutes). CONCLUSION A two-tiered approach to MRI can serve as a viable cost-effective alternative to the conventional approach.

Using Correlative Properties of Neighboring Pixels to Improve Gray-White Differentiation in Pediatric Head CT Images

OBJECTIVE. Morphologic changes associated with papilledema may be masked by partial volume averaging effects in images obtained at a slice thickness greater than normal optic nerve thickness. We aimed to compare the diagnostic accuracy of high-resolution 3D T2-weighted imaging performed at submillimeter slice thickness with conventional T2-weighted imaging performed at 5-mm slice thickness for detection of papilledema. MATERIALS AND METHODS. Two blinded neuroradiologists evaluated conventional and high-resolution axial T2-weighted imaging across orbits from 25 patients with clinically proven papilledema and 66 control participants without papilledema. They graded optic nerve sheath distention and optic nerve head configuration, also making a binary determination for presence or absence of papilledema for each set of images. The diagnostic accuracy of each technique was assessed in terms of sensitivity, specificity, positive likelihood ratio, and interobserver agreement. These parameters were compared using the homogeneity of odds ratio and McNemar tests. RESULTS. High-resolution T2-weighted imaging was associated with higher sensitivity (83.3% vs 56.2%, p = 0.0072 for reader 1; 87.5% vs 54.2% for reader 2, p = 0.0001) but unchanged specificity. High-resolution T2-weighted imaging was significantly better than conventional T2-weighted imaging in detecting optic nerve head deformity in patients with papilledema, but there was no difference between two techniques in detection of optic nerve sheath distention. High-resolution imaging also enabled greater interobserver agreement (κ = 0.82) compared with conventional T2-weighted image (κ = 0.62). CONCLUSION. Improved visualization of the optic nerve head afforded by high-resolution T2-weighted imaging translates into better diagnostic performance of MRI in detection of papilledema, with higher sensitivity and interobserver reliability.

Enhancing contrast to noise ratio of hippocampi affected with mesial temporal sclerosis: A case-control study in children undergoing epilepsy surgeries

BACKGROUND AND PURPOSE: A lower radiation dose can have a detrimental effect on the quality of head CT images. The aim of this study performed in a pediatric population was to test whether an image-processing algorithm (Correlative Image Enhancement) based on the correlation among intensities of neighboring pixels can improve gray-white differentiation in head CTs. MATERIALS AND METHODS: Sixty baseline head CT images with normal findings obtained from scans of 30 children were processed using Correlative Image Enhancement to produce corresponding enhanced images. Gray-white differentiation in baseline and enhanced images was assessed quantitatively by calculating the contrast-to-noise ratio and conspicuity in equivalent ROIs in gray and white matter. Two masked readers rated the images for visibility of gray-white differentiation on a 5-point Likert scale. Differences in both quantitative and qualitative measures of gray-white differentiation between baseline and enhanced images were tested for statistical significance. P values < .05 were considered significant. RESULTS: Image processing resulted in improvement in the contrast-to-noise ratio (from 1.86 ± 0.94 to 2.26 ± 1.00, P = .02) as well as conspicuity (from 37.28 ± 11.56 to 46.4 ± 11.5, P < .001). This was accompanied by improved subjective visibility of gray-white differentiation as reported by both readers (P < .01). CONCLUSIONS: Image processing using Correlative Image Enhancement had a beneficial effect on quantitative measures of gray-white differentiation. This translated into improved perception of gray-white differentiation by readers. Further studies are needed to assess the effect of such image processing on the detection of disease processes using head CTs.

Using Correlative Properties of Neighboring Pixels to Enhance Contrast-to-Noise Ratio of Abnormal Hippocampus in Patients With Intractable Epilepsy and Mesial Temporal Sclerosis

OBJECTIVE Detection of mesial temporal sclerosis (MTS) in children with epilepsy is important. We assessed whether an image-processing algorithm (Correlative Image Enhancement, CIE) could facilitate recognition of hippocampal signal abnormality in the presence of MTS by increasing contrast to noise ratio between affected hippocampus and normal gray matter. PATIENTS AND METHODS Baseline coronal FLAIR images from brain MRIs of 27 children with epilepsy who underwent hippocampal resection were processed using CIE. These included 19 hippocampi with biopsy proven MTS and 8 biopsy proven normal hippocampi resected in conjunction with hemispherotomy. We assessed the effect of processing on contrast to noise ratio (CNR) between hippocampus and normal insular gray matter, and on assessment of hippocampal signal abnormality by two masked neuroradiologists. RESULTS Processing resulted in a significant increase in mean CNR (from 3.9 ± 5.3 to 25.3 ± 25.8; P < 0.01) for hippocampi with MTS, with a substantial (>100%) increase from baseline seen in 15/19 (78.9%) cases. Baseline CNR of 1.7 ± 5.3 for normal hippocampi did not change significantly after processing (1.8 ± 5.3; P = 1.00). For one reader, baseline sensitivity (14/19; 73.6%) was unaffected but the specificity improved from 62.5% (5/8) to 100%. An increase in both sensitivity (from 73.6% to 78.9%) and specificity (from 62.5% to 75%) was seen for the second reader. CONCLUSION By enhancing CNR for diseased hippocampi while leaving normal hippocampi relatively unaffected, CIE may improve the diagnostic accuracies of radiologists in detecting MTS-related signal alteration within the affected hippocampus.

Location of Core Diagnostic Information Across Various Sequences in Brain MRI and Implications for Efficiency of MRI Scanner Utilization

RATIONALE AND OBJECTIVES To test whether an image-processing algorithm can aid in visualization of mesial temporal sclerosis on magnetic resonance imaging by selectively increasing contrast-to-noise ratio (CNR) between abnormal hippocampus and normal brain. MATERIALS AND METHODS In this Institutional Review Board-approved and Health Insurance Portability and Accountability Act-compliant study, baseline coronal fluid-attenuated inversion recovery images of 18 adults (10 females, eight males; mean age 41.2 years) with proven mesial temporal sclerosis were processed using a custom algorithm to produce corresponding enhanced images. Average (Hmean) and maximum (Hmax) CNR for abnormal hippocampus were calculated relative to normal ipsilateral white matter. CNR values for normal gray matter (GM) were similarly calculated using ipsilateral cingulate gyrus as the internal control. To evaluate effect of image processing on visual conspicuity of hippocampal signal alteration, a neuroradiologist masked to the side of hippocampal abnormality rated signal intensity (SI) of hippocampi on baseline and enhanced images using a five-point scale (definitely abnormal to definitely normal). Differences in Hmean, Hmax, GM, and SI ratings for abnormal hippocampi on baseline and enhanced images were assessed for statistical significance. RESULTS Both Hmean and Hmax were significantly higher in enhanced images as compared to baseline images (p < 0.0001 for both). There was no significant difference in the GM between baseline and enhanced images (p = 0.9375). SI ratings showed a more confident identification of abnormality on enhanced images (p = 0.0001). CONCLUSION Image-processing resulted in increased CNR of abnormal hippocampus without affecting the CNR of normal gray matter. This selective increase in conspicuity of abnormal hippocampus was associated with more confident identification of hippocampal signal alteration.

Balanced steady-state free-precession MR imaging for measuring pulsatile motion of cerebellar tonsils during the cardiac cycle: a reliability study

OBJECTIVE Targeting redundancy within MRI can improve its cost-effective utilization. We sought to quantify potential redundancy in our brain MRI protocols. MATERIALS AND METHODS In this retrospective review, we aggregated 207 consecutive adults who underwent brain MRI and reviewed their medical records to document clinical indication, core diagnostic information provided by MRI, and its clinical impact. Contributory imaging abnormalities constituted positive core diagnostic information whereas absence of imaging abnormalities constituted negative core diagnostic information. The senior author selected core sequences deemed sufficient for extraction of core diagnostic information. For validating core sequences selection, four readers assessed the relative ease of extracting core diagnostic information from the core sequences. Potential redundancy was calculated by comparing the average number of core sequences to the average number of sequences obtained. RESULTS Scanning had been performed using 9.4±2.8 sequences over 37.3±12.3 minutes. Core diagnostic information was deemed extractable from 2.1±1.1 core sequences, with an assumed scanning time of 8.6±4.8 minutes, reflecting a potential redundancy of 74.5%±19.1%. Potential redundancy was least in scans obtained for treatment planning (14.9%±25.7%) and highest in scans obtained for follow-up of benign diseases (81.4%±12.6%). In 97.4% of cases, all four readers considered core diagnostic information to be either easily extractable from core sequences or the ease to be equivalent to that from the entire study. With only one MRI lacking clinical impact (0.48%), overutilization did not seem to contribute to potential redundancy. CONCLUSION High potential redundancy that can be targeted for more efficient scanner utilization exists in brain MRI protocols.