Assessment of radiation and chemotherapy efficacy for brain cancer patients is traditionally accomplished by measuring changes in tumor size several months after therapy has been administered. The ability to use noninvasive imaging during the early stages of fractionated therapy to determine whether a particular treatment will be effective would provide an opportunity to optimize individual patient management and avoid unnecessary systemic toxicity, expense, and treatment delays. We investigated whether changes in the Brownian motion of water within tumor tissue as quantified by using diffusion MRI could be used as a biomarker for early prediction of treatment response in brain cancer patients. Twenty brain tumor patients were examined by standard and diffusion MRI before initiation of treatment. Additional images were acquired 3 weeks after initiation of chemo-and͞or radiotherapy. Images were coregistered to pretreatment scans, and changes in tumor water diffusion values were calculated and displayed as a functional diffusion map (fDM) for correlation with clinical response. Of the 20 patients imaged during the course of therapy, 6 were classified as having a partial response, 6 as stable disease, and 8 as progressive disease. The fDMs were found to predict patient response at 3 weeks from the start of treatment, revealing that early changes in tumor diffusion values could be used as a prognostic indicator of subsequent volumetric tumor response. Overall, fDM analysis provided an early biomarker for predicting treatment response in brain tumor patients. diffusion MRI ͉ therapeutic response

Patients with chronic hypercortisolemia due to Cushing's syndrome (CS) exhibit cognitive dysfunction. Because glucocorticoid excess is associated with hippocampal damage in animals, and the hippocampus participates in learning and memory, we explored the relationships between hippocampal formation (HF) volume, memory dysfunction, and cortisol levels in 12 patients with CS. After magnetic resonance imaging, HF volume was determined using digital sum of track ball traces of dentate gyrus, hippocampus proper and subiculum, correcting for total intracranial volume. For 27% of the patients, HF volume fell outside the 95% confidence intervals for normal subject volume given in the literature. In addition, there were significant and specific correlations between HF volume and scores for verbal paired associate learning, verbal recall, and verbal recall corrected for full-scale IQ (r = 0.57 to 0.70, p < 0.05). HF volume was negatively correlated with plasma cortisol levels (r = -0.73, p < 0.05). These studies suggest an association between reduced HF volume, memory dysfunction, and elevated cortisol in patients with CS.

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Diffuse malignant gliomas, the most common type of brain tumor, carry a dire prognosis and are poorly responsive to initial treatment. The response to treatment is typically evaluated by measurements obtained from radiographic images several months after the start of treatment; therefore, an early biomarker of tumor response would be useful for making early treatment decisions and for prognostic information. Thirty-four patients with malignant glioma were examined by diffusion MRI before treatment and 3 weeks later. These images were coregistered, and differences in tumor-water diffusion values were calculated as functional diffusion maps (fDM), which were correlated with the radiographic response, time-to-progression (TTP), and overall survival (OS). Changes in fDM at 3 weeks were closely associated with the radiographic response at 10 weeks. The percentage of the tumor undergoing a significant change in the diffusion of water (V T ) was different between patients with progressive disease (PD) vs. stable disease (SD) (P < 0.001). Patients classified as PD by fDM analysis at 3 weeks were found to have a shorter TTP compared with SD (median TTP, 4.3 vs. 7.3 months; P < 0.04). By using fDM, early patient stratification also was correlated with shorter OS in the PD group compared with SD patients (median survival, 8.0 vs. 18.2 months; P < 0.01). On the basis of fDM, tumor assessment provided an early biomarker for response, TTP, and OS in patients with malignant glioma. Further evaluation of this technique is warranted to determine whether it may be useful in the individualization of treatment or evaluation of the response in clinical protocols.diffusion MRI ͉ human glioma ͉ treatment assessment ͉ surrogate marker

Despite dose escalation to 90 Gy, the predominant failure pattern in high-grade gliomas remains local. This suggests that close margins used in highly conformal treatments do not increase the risk of marginal or distant recurrences. Our results indicate that intensification of local radiotherapy with dose escalation is feasible and deserves further evaluation for high-grade gliomas.