title: A Radiation-Induced Hippocampal Vascular Injury Surrogate Marker Predicts Late Neurocognitive Dysfunction.
abstract: OBJECTIVE
  We aimed to develop a hippocampal vascular injury surrogate marker for early prediction of late neurocognitive dysfunction in patients receiving brain radiation therapy (RT).
  
  
  METHODS
  Twenty-seven patients (17 males and 10 females, 31-80 years of age) were enrolled in an institutional review board-approved prospective longitudinal study. Patients received diagnoses of low-grade glioma or benign tumor and were treated by (3D) conformal or intensity-modulated RT with a median dose of 54 Gy (50.4-59.4 Gy in 1.8-Gy fractions). Six dynamic-contrast enhanced MRI scans were performed from pre-RT to 18-month post-RT, and quantified for vascular parameters related to blood-brain barrier permeability, K(trans), and the fraction of blood plasma volume, Vp. The temporal changes in the means of hippocampal transfer constant K(trans) and Vp after starting RT were modeled by integrating the dose effects with age, sex, hippocampal laterality, and presence of tumor or edema near a hippocampus. Finally, the early vascular dose response in hippocampi was correlated with neurocognitive dysfunction at 6 and 18 months post-RT.
  
  
  RESULTS
  The mean K(trans) Increased significantly from pre-RT to 1-month post-RT (P<.0004), which significantly depended on sex (P<.0007) and age (P<.00004), with the dose response more pronounced in older females. Also, the vascular dose response in the left hippocampus of females correlated significantly with changes in memory function at 6 (r=-0.95, P<.0006) and 18-months (r=-0.88, P<.02) post-RT.
  
  
  CONCLUSIONS
  The early hippocampal vascular dose response could be a predictor of late neurocognitive dysfunction. A personalized hippocampus sparing strategy may be considered in the future.
authors.affiliation: Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York.
authors.forename: Reza
authors.initials: R
authors.lastname: Farjam
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan.
authors.forename: Priyanka
authors.initials: P
authors.lastname: Pramanik
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan.
authors.forename: Madhava P
authors.initials: MP
authors.lastname: Aryal
authors.affiliation: Department of Radiology, University of Michigan, Ann Arbor, Michigan.
authors.forename: Ashok
authors.initials: A
authors.lastname: Srinivasan
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan.
authors.forename: Christopher H
authors.initials: CH
authors.lastname: Chapman
authors.affiliation: Department of Radiation Oncology, Washington University in St. Louis, St. Louis, Missouri.
authors.forename: Christina I
authors.initials: CI
authors.lastname: Tsien
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan.
authors.forename: Theodore S
authors.initials: TS
authors.lastname: Lawrence
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan; Department of Radiology, University of Michigan, Ann Arbor, Michigan; Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan. Electronic address: yuecao@umich.edu.
authors.forename: Yue
authors.initials: Y
authors.lastname: Cao
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001812:Blood-Brain Barrier / Q000528:radiation effects; D001932:Brain Neoplasms / Q000532:radiotherapy; D003072:Cognition Disorders / Q000209:etiology*; D016371:Cranial Irradiation / Q000009:adverse effects* / Q000379:methods; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005910:Glioma / Q000532:radiotherapy; D006624:Hippocampus / Q000098:blood supply* / Q000528:radiation effects; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000209:etiology; D008875:Middle Aged; D010911:Pituitary Neoplasms / Q000532:radiotherapy; D011446:Prospective Studies; D011829:Radiation Dosage; D011832:Radiation Injuries / Q000150:complications*; D020266:Radiotherapy, Conformal / Q000009:adverse effects / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods; D012044:Regression Analysis; D012737:Sex Factors; D013997:Time Factors; D057772:Vascular System Injuries / Q000209:etiology*