title: Hemodynamic response imaging: a potential tool for the assessment of angiogenesis in brain tumors.
abstract: Blood oxygenation level dependence (BOLD) imaging under either hypercapnia or hyperoxia has been used to study neuronal activation and for assessment of various brain pathologies. We evaluated the benefit of a combined protocol of BOLD imaging during both hyperoxic and hypercapnic challenges (termed hemodynamic response imaging (HRI)). Nineteen healthy controls and seven patients with primary brain tumors were included: six with glioblastoma (two newly diagnosed and four with recurrent tumors) and one with atypical-meningioma. Maps of percent signal intensity changes (ΔS) during hyperoxia (carbogen; 95%O2+5%CO2) and hypercapnia (95%air+5%CO2) challenges and vascular reactivity mismatch maps (VRM; voxels that responded to carbogen with reduced/absent response to CO2) were calculated. VRM values were measured in white matter (WM) and gray matter (GM) areas of healthy subjects and used as threshold values in patients. Significantly higher response to carbogen was detected in healthy subjects, compared to hypercapnia, with a GM/WM ratio of 3.8 during both challenges. In patients with newly diagnosed/treatment-naive tumors (n = 3), increased response to carbogen was detected with substantially increased VRM response (compared to threshold values) within and around the tumors. In patients with recurrent tumors, reduced/absent response during both challenges was demonstrated. An additional finding in 2 of 4 patients with recurrent glioblastoma was a negative response during carbogen, distant from tumor location, which may indicate steal effect. In conclusion, the HRI method enables the assessment of blood vessel functionality and reactivity. Reference values from healthy subjects are presented and preliminary results demonstrate the potential of this method to complement perfusion imaging for the detection and follow up of angiogenesis in patients with brain tumors.
authors.affiliation: Functional Brain Center, The Wohl Institute for Advanced Imaging, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel. dafnab@tlvmc.gov.il
authors.forename: Dafna
authors.initials: D
authors.lastname: Ben Bashat
authors.forename: Moran
authors.initials: M
authors.lastname: Artzi
authors.forename: Haim
authors.initials: H
authors.lastname: Ben Ami
authors.forename: Orna
authors.initials: O
authors.lastname: Aizenstein
authors.forename: Deborah T
authors.initials: DT
authors.lastname: Blumenthal
authors.forename: Felix
authors.initials: F
authors.lastname: Bokstein
authors.forename: Benjamin W
authors.initials: BW
authors.lastname: Corn
authors.forename: Zvi
authors.initials: Z
authors.lastname: Ram
authors.forename: Avraham A
authors.initials: AA
authors.lastname: Kanner
authors.forename: Biatris
authors.initials: B
authors.lastname: Lifschitz-Mercer
authors.forename: Irit
authors.initials: I
authors.lastname: Solar
authors.forename: Tsafrir
authors.initials: T
authors.lastname: Kolatt
authors.forename: Mika
authors.initials: M
authors.lastname: Palmon
authors.forename: Yifat
authors.initials: Y
authors.lastname: Edrei
authors.forename: Rinat
authors.initials: R
authors.lastname: Abramovitch
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain / Q000378:metabolism / Q000473:pathology; D001932:Brain Neoplasms / Q000098:blood supply* / Q000175:diagnosis*; D016022:Case-Control Studies; D003287:Contrast Media; D003952:Diagnostic Imaging; D005260:Female; D006439:Hemodynamics; D006454:Hemoglobins; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009389:Neovascularization, Pathologic / Q000175:diagnosis*; D010101:Oxygen Consumption; D012008:Recurrence
chemical_list: D003287:Contrast Media; D006454:Hemoglobins; C100003:deoxyhemoglobin