A new automated method for analysis of rCBF-SPECT images based on the active-shape algorithm: normal values

Capillary transit time heterogeneity inhibits cerebral oxygen metabolism in patients with reduced cerebrovascular reserve capacity from steno-occlusive disease

The healthy cerebral perfusion demonstrates a homogenous distribution of capillary transit times. A disruption of this homogeneity may inhibit the extraction of oxygen. A high degree of capillary transit time heterogeneity (CTH) describes that some capillaries have very low blood flows, while others have excessively high blood flows and consequently short transit times. Very short transit times could hinder the oxygen extraction due to insufficient time for diffusion of oxygen into the tissue. CTH could be a consequence of cerebral vessel disease. We examined whether patients with cerebral steno-occlusive vessel disease demonstrate high CTH and if elevation of cerebral blood flow (CBF) by administration of acetazolamide (ACZ) increases the cerebral metabolic rate of oxygen (CMRO₂), or if some patients demonstrate reduced CMRO₂ related to detrimental CTH. Thirty-four patients and thirty-one healthy controls participated. Global CBF and CMRO₂ were acquired using phase-contrast MRI. Regional brain maps of CTH were acquired using dynamic contrast-enhanced MRI. Patients with impaired cerebrovascular reserve capacity demonstrated elevated CTH and a significant reduction of CMRO₂ after administration of ACZ, which could be related to high CTH. Impaired oxygen extraction from CTH could be a contributing part of the declining brain health observed in patients with cerebral vessel disease.

A quantitative evaluation of brain dysfunction and body-burden of toxic metals

Background

Toxic metal exposure (e.g. Hg, Pb, As) exposure is known to induce significant adverse effects on human brain function. The aim this study was to assess toxic metal body-burden in relation to potential brain dysfunction in patients diagnosed with neurological disorders (NDs).

Material/Methods

The Liberty Institutional Review Board (Deland, FL) approved the present study. Quantitative, fractionated, random urinary porphyrin testing (μg/L) from the Clinical Laboratory Improvement Act/Amendment (CLIA)-approved Laboratory Corporation of America (LabCorp) and cortical perfusion index (CPi) values from single-photon-emission-computed-tomography (SPECT) brain scans were employed to evaluate a prospective cohort of qualifying patients with diagnosed NDs (n=52) presenting for medical care at an endocrinology practice in the Cincinnati, OH area.

Results

Patients with more severe in comparison to mild brain dysfunction had significant increases in the mean urinary concentration of uroporphyrins (uP), coproporphyrins I (cP I), and total cP (cP I + III), as well as a trend towards significantly increased mean urinary concentration of pentacarboxyporphyins (5cxP) and cP III. A significant positive correlation between Hg body-burden associated porphyrins (5cxP + cP I + cP III) and increased brain dysfunction was observed.

Conclusions

The present study associated brain dysfunction with Hg body-burden in a cohort of patients diagnosed with NDs, but the contributions of other heavy metals or genetic factors cannot be ruled-out. Additional studies should be conducted to evaluate the consistency of the present findings with examinations of other populations.