Combined proton MR spectroscopy and dynamic contrast enhanced MR imaging of human intracranial tumours in vivo

A study was undertaken to determine if the vascular characteristics measured by dynamic contrast-enhanced magnetic resonance imaging (primarily permeability surface area product and extracellular-extravascular tissue volume fraction) would be beneficial in explaining the inter-lesion metabolic heterogeneity displayed by human intracranial tumours. Magnetic resonance spectroscopy was carried out using a single-voxel STEAM sequence and dynamic imaging was carried out using a combination of pre-contrast proton density-weighted FSPGR images (to remove the influence of native tissue T1), bolus injection of Gd-DTPA and subsequent T1-weighted FSPGR dynamic imaging. A two-compartment pharmacokinetic model was employed to determine vascular characteristics. Results obtained from 12 meningiomas suggest a possible correlation between the level of lipids/macromolecules and permeability surface area product, although the confounding issue of extra-voxel contamination arising from lipids in the scalp and skull marrow cannot be ruled out in the more superficial lesions. Results obtained from 11 gliomas (four low and seven high grade) demonstrate that permeability surface area product is not specific for the range of vascular characteristics and metabolite profiles observed in gliomas and is therefore unable to explain metabolic heterogeneity in these lesions.

Pharmacokinetic study of the interaction between rifampicin and ketoconazole

This study assessed the potential pharmacokinetic interaction between rifampicin and ketoconazole, two drugs used to treat the increasingly common combination of Mycobacterium tuberculosis and Candida albicans infection in AIDS patients. The peak plasma rifampicin concentrations in six healthy male subjects were not altered when taken in conjunction with ketoconazole. However, the peak plasma ketoconazole levels were significantly diminished when taken in conjunction with rifampicin, compared to when taken alone (P less than 0.015). The mean area under the curve (AUC) for ketoconazole was significantly diminished when taken with oral or intravenous rifampicin (P less than 0.001).