Cerebral perfusion and cerebrovascular reactivity are reduced in white matter hyperintensities

BACKGROUND AND PURPOSE

There is growing evidence that white matter hyperintensities (WMH) should not be considered as benign age-dependent changes on MR images but indicate pathological changes with clinical consequences. Previous studies comparing subjects with WMH to normal controls have reported global reductions in cerebral blood flow (CBF) and cerebral vascular reactivity. In this study, we examined localized hemodynamic status to compare WMH to normal appearing white matter (NAWM).

METHODS

A group of 21 normal 85-year-old subjects were studied using dynamic contrast-enhanced MRI together with administration of acetazolamide. From a combination of anatomic images with different signal weighting, regions of interest were generated corresponding to gray and white matter and WMH. Localized measurements of CBF and cerebral blood volume (CBV) and mean transit time were obtained directly within WMH and NAWM.

RESULTS

When comparing WMH to NAWM, measurements showed significantly lower CBF (P=0.004) and longer mean transit time (P< 0.001) in WMH but no significant difference in CBV (P=0.846). The increases in CBF and CBV induced by acetazolamide were significantly smaller in WMH than in NAWM (P=0.026, P<0.001).

CONCLUSION

These results show that a change in the hemodynamic status is present within the WMH, making these areas more likely to be exposed to transient ischemia inducing myelin rarefaction. In the future, MRI may be used to examine the effect of therapeutic strategies designed to prevent or normalize vascular changes.

Managed care purchasing under SCHIP: a nationwide analysis of freestanding SCHIP contracts

This Policy Brief is the third in a series that examines the State Children's Health Insurance Program (SCHIP), in particular, those state programs that operate directly under the authority of Title XXI of the Social Security Act rather than as an expansion of Medicaid (or a Medicaid demonstration initiative). This series is designed to examine how states structure and administer insurance programs for low-income children when they elect to administer separate SCHIP plans that exist outside of the requirements and constraints of Medicaid. Understanding how states use their flexibility under "separate SCHIP programs" (as they are termed) has become an increasingly important policy question, in the face of heightened interest on the part of Governors, the Bush Administration, and others in comprehensive Medicaid reform. The first two policy briefs in this series analyzed the entitlement status of separately administered SCHIP programs, as well as issues related to coverage design and the definition of medical necessity. This Policy Brief provides the first nationwide overview of how separate SCHIP programs structure "freestanding" SCHIP managed care contracts, i.e., contracts that exist independently of a state's Medicaid managed care agreements. Fifteen such "freestanding" contracts existed as of Calendar Year 2000, and we report here on their general terms of coverage, access, and care coordination. A forthcoming related study will examine behavioral health care in freestanding SCHIP agreements. Following a brief background and discussion of research methods, we present our principal findings and discuss their implications.

Cerebral hemodynamic changes measured by gradient-echo or spin-echo bolus tracking and its correlation to changes in ICA blood flow measured by phase-mapping MRI

Changes in cerebral blood flow (CBF) induced by Acetazolamide (ACZ) were measured using dynamic susceptibility contrast MRI (DSC-MRI) with both spin echo (SE) EPI and gradient echo (GE) EPI, and related to changes in internal carotid artery (ICA) flow measured by phase-mapping. Also examined was the effect of repeated bolus injections. CBF, cerebral blood volume (CBV), and mean transit time (MTT) were calculated by singular value decomposition (SVD) and by deconvolution using an exponential function as kernel. The results showed no dependency on calculation method. GE-EPI measured a significant increase in CBF and CBV in response to ACZ, while SE-EPI measured a significant increase in CBV and MTT. CBV and MTT change measured by SE-EPI was sensitive to previous bolus injections. There was a significant linear relation between change in CBF measured by GE-EPI and change in ICA flow. In conclusion, GE-EPI under the present condition was superior to SE-EPI in monitoring cerebral vascular changes.

Allowing small businesses and the self-employed to buy health care coverage through public programs

The large number of uninsured working Americans and the extent of public support enjoyed by employment-based health insurance argues for a coverage initiative that fosters access to affordable benefits through employment. This proposal, which reflects models in both Massachusetts and Michigan, entails the development of publicly organized and subsidized group health insurance for small firms with low-wage workers. States would provide overall administration and subsidies to both employers and employees. Employers would enroll workers, select insurers, pay premiums, and report data on employment status. The program would be a legislative extension of the State Children's Health Insurance Program (SCHIP), with federal financing to participating states at each respective SCHIP rate. Anti-crowd-out provisions would be included. This program is both administratively and politically feasible. It is also consistent with current thinking regarding public/private partnerships and the desirability of preserving a voluntary employer-sponsored health insurance system.

Quantification of the effect of water exchange in dynamic contrast MRI perfusion measurements in the brain and heart

Measurement of myocardial and brain perfusion when using exogenous contrast agents (CAs) such as gadolinium-DTPA (Gd-DTPA) and MRI is affected by the diffusion of water between compartments. This water exchange may have an impact on signal enhancement, or, equivalently, on the longitudinal relaxation rate, and could therefore cause a systematic error in the calculation of perfusion (F) or the perfusion-related parameter, the unidirectional influx constant over the capillary membranes (K(i)). The aim of this study was to quantify the effect of water exchange on estimated perfusion (F or K(i)) by using a realistic simulation. These results were verified by in vivo studies of the heart and brain in humans. The conclusion is that water exchange between the vascular and extravascular extracellular space has no effect on K(i) estimation in the myocardium when a normal dose of Gd-DTPA is used. Water exchange can have a significant effect on perfusion estimation (F) in the brain when using Gd-DTPA, where it acts as an intravascular contrast agent.

State benefit design choices under SCHIP - implications for pediatric health care

This policy brief is the second in a series of reports focusing on the design of state SCHIP programs as they near full implementation. It examines the extent to which state agencies adopt conventional insurance norms or adhere to special principles of Medicaid coverage design for children in designing separately administered (or freestanding) SCHIP programs. The issue of coverage design is particularly relevant for children with low uses standardized coverage norms to limit coverage and treatment. These standardized norms take the form of across-the-board treatments and exclusions, limited definitions of medical necessity, and the use of irrebuttable, standardized treatment guidelines in determining when covered treatments will be available. All of these practices are impermissible under Medicaid, which uses exceptionally broad preventive standards to determine coverage of children; such standards favor coverage of children with low prevalence problems.

Care coordination and physical and behavioral service integration in managed care contracts: analysis and sample purchasing specifications

This double Issue Brief on the issue of managed care contracts and care coordination has been prepared for the Substance Abuse and Mental Health Services Administration as part of a series that examines legal issues in managed care for persons with mental illness and addiction disorders. This Issue Brief is presented in two parts. Part 1 presents an analysis, based on managed care contract data bases developed by CHSRP, of the extent to which public and private group purchasers maintain agreements that specify care coordination as part of the standard of care for persons with co-occurring physical and/or behavioral illnesses and conditions. Part 2 sets forth sample purchasing specifications that are designed to establish care coordination as part of the standard of care.

Behavioral health benefits for public employees: effect of mental health parity legislation

With the passage of the Mental Health Parity Act of 1996 (MHPA), Congress took an important first step toward equalizing treatment under medical plans between physical and mental illnesses by requiring parity in annual and lifetime dollar limits between physical and mental illness. But the Act was limited in scope: it did not mandate mental health benefits nor prohibit other common types of differentials between physical and mental illnesses, such as higher cost-sharing or lower limits on outpatient visits or inpatient treatments. Before Congress' action in 1996, a few of the states had adopted some type of parity requirement. Since 1996, state parity activity has accelerated.Recently, the Center for Health Services Research and Policy through a grant from the Substance Abuse and Mental Health Services Administration of the U.S. Department of Health and Human Services, examined contracts providing for mental health benefits for state employees in eight states to assess whether legislative attempts to require parity between physical and mental illnesses resulted in noticeable differences in behavioral health benefits for state employees. We concluded that, except in states that have mandated full parity for some or all types of mental illnesses, behavioral health benefits for state employees have not changed significantly as a result of the state parity laws, since they still remain subject to traditional restrictions, such as higher cost-sharing and greater limitations on outpatient visits and inpatient treatment days, than those imposed on physical illnesses. Thus the considerable state activity surrounding mental health parity may have little effect on state employees' access to mental health services, since although state laws required parity in dollar limitations, they generally permitted the continuation of other plan design features that are more restrictive for mental health coverage. However, many of the contracts we examined were multi-year contract and may not have fully reflected recent state activity. Moreover, if Congress renews the Mental Health Parity Act when it expires in September, 2001, and expands the scope of the Act to cover some of these other plan design features, states with more limited parity laws are likely to follow. In that case, perhaps state employees with mental illnesses may see significant change in the future.

State SCHIP design and the right to coverage

This Policy Brief is the first in a series of reports examining the design of state SCHIP programs as they near full implementation status. It explores, whether states in their enabling legislation establishing separate SCHIP programs confer upon eligible children an individual legal right to health insurance benefits (i.e., an individual entitlement) under state law, similar to the entitlement that Medicaid eligible children enjoy under federal law. The question of whether states guarantee necessary health coverage for low-income children through the creation of an individual entitlement is fundamental to the study of state policy making under SCHIP.

U.S. civil rights policy and access to health care by minority Americans: implications for a changing health care system

The history of health care discrimination as well as ongoing, extensive evidence of racial disparities argue for continued vigilance in the area of health care and civil rights. Under Title VI of the Civil Rights Act of 1964, individuals have challenged de facto discriminatory policies adopted by health entities receiving federal financial assistance. Title VI health litigation is difficult because of complex issues of proof as well as confounding problems of poverty and lack of health insurance that affect both claims and remedies. An analysis of cases brought under the law suggests that discrimination claims within a particular market fare better than those challenging decisions to relocate or alter the market served. This has important implications for claims involving discrimination by managed care organizations. Because the same potential for discrimination exists in the new health system of managed care, although in altered form, data collection and evaluation are warranted.

An evaluation of agreements between managed care organizations and community-based mental illness and addiction disorder treatment and prevention providers

This Issue Brief, prepared for the Substance Abuse and Mental Health Services Administration (SAMHSA), examines contracts between managed care organizations (MCOs) and community-based providers of mental illness and addiction disorder treatment and prevention services (MI/AD providers). Building upon initial research published in 1997, this brief explores in depth one of the most hidden aspects of managed care: the relationship between the managed care organizations and health care providers.