title: Dexamethasone normalizes brain tumor hemodynamics as indicated by dynamic susceptibility contrast MRI perfusion parameters.
abstract: The purpose of this study is to demonstrate the utility of dynamic susceptibility contrast (DSC) MRI-derived perfusion parameters to characterize the hemodynamic effects of dexamethasone in a 9L gliosarcoma tumor model. Twenty-four rats underwent intracerebral inoculation with 9L tumor cells. Fifteen were treated with a total of 3mg/kg of dexamethasone on days 10-14 post-inoculation, while the remaining 9 rats served as controls. Fourteen days post-inoculation, MRI images, sensitive to total and micro-vascular cerebral blood flow (CBF), mean transit time (MTT), and intravoxel transit time distributions (TTD)s were obtained using a simultaneous gradient-echo(GE)/spin-echo(SE) DSC-MRI method. Dexamethasone-treated animals had a microvascular (SE) tumor CBF that was 45.9% higher (p = 0.0008) and a MTT that was 47.8% lower (p = 0.0005) than untreated animals. With treatment, there was a non-significant 91.3% increase in total (GE) vascular CBF (p = 0.35), and a significant decrease in MTT (49.1%, p = 0.02). The total vascular and microvascular TTDs from the treated tumors were similar to normal brain, unlike the TTDs in the untreated tumors. These findings demonstrate that DSC-MRI perfusion methods can be used to non-invasively detect the morphological and functional changes in tumor vasculature that occur in response to dexamethasone treatment.
authors.affiliation: Department of Biophysics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226-0509, USA.
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Quarles
authors.forename: Hendrikus G J
authors.initials: HG
authors.lastname: Krouwer
authors.forename: Scott D
authors.initials: SD
authors.lastname: Rand
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Schmainda
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use*; D001932:Brain Neoplasms / Q000098:blood supply* / Q000188:drug therapy* / Q000473:pathology; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology; D003287:Contrast Media; D003907:Dexamethasone / Q000627:therapeutic use*; D018316:Gliosarcoma / Q000098:blood supply* / Q000188:drug therapy* / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D010477:Perfusion; D051381:Rats; D017208:Rats, Wistar; D012039:Regional Blood Flow
chemical_list: D000893:Anti-Inflammatory Agents; D003287:Contrast Media; D003907:Dexamethasone