title: Pretreatment prediction of brain tumors' response to radiation therapy using high b-value diffusion-weighted MRI.
abstract: Diffusion-weighted magnetic resonance imaging (DWMRI) is sensitive to tissues' biophysical characteristics, including apparent diffusion coefficients (ADCs) and volume fractions of water in different populations. In this work, we evaluate the clinical efficacy of DWMRI and high diffusion-weighted magnetic resonance imaging (HDWMRI), acquired up to b = 4000 sec/mm(2) to amplify sensitivity to water diffusion properties, in pretreatment prediction of brain tumors' response to radiotherapy. Twelve patients with 20 brain lesions were studied. Six ring-enhancing lesions were excluded due to their distinct diffusion characteristics. Conventional and DWMRI were acquired on a 0.5-T MRI. Response to therapy was determined from relative changes in tumor volumes calculated from contrast-enhanced T1-weighted MRI, acquired before and a mean of 46 days after beginning therapy. ADCs and a diffusion index, R(D), reflecting tissue viability based on water diffusion were calculated from DWMRIs. Pretreatment values of ADC and R(D) were found to correlate significantly with later tumor response/nonresponse (r = 0.76, P <.002 and r = 0.77, P <.001). This correlation implies that tumors with low pretreatment diffusion values, indicating high viability, will respond better to radiotherapy than tumors with high diffusion values, indicating necrosis. These results demonstrate the feasibility of using DWMRI for pretreatment prediction of response to therapy in patients with brain tumors undergoing radiotherapy.
authors.affiliation: Advanced Technology Center, Sheba Medical Center, Tel-Hashomer, Ramat-Gan 52621, Israel. yael@tauphy.tau.ac.il
authors.forename: Yael
authors.initials: Y
authors.lastname: Mardor
authors.forename: Yiftach
authors.initials: Y
authors.lastname: Roth
authors.forename: Aharon
authors.initials: A
authors.lastname: Ochershvilli
authors.forename: Roberto
authors.initials: R
authors.lastname: Spiegelmann
authors.forename: Thomas
authors.initials: T
authors.lastname: Tichler
authors.forename: Dianne
authors.initials: D
authors.lastname: Daniels
authors.forename: Stephan E
authors.initials: SE
authors.lastname: Maier
authors.forename: Ouzi
authors.initials: O
authors.lastname: Nissim
authors.forename: Zvi
authors.initials: Z
authors.lastname: Ram
authors.forename: Jacob
authors.initials: J
authors.lastname: Baram
authors.forename: Arie
authors.initials: A
authors.lastname: Orenstein
authors.forename: Raphael
authors.initials: R
authors.lastname: Pfeffer
mesh_terms: D001921:Brain / Q000473:pathology*; D001932:Brain Neoplasms / Q000175:diagnosis* / Q000532:radiotherapy* / Q000556:secondary; D001943:Breast Neoplasms / Q000175:diagnosis; D005240:Feasibility Studies; D005260:Female; D005910:Glioma / Q000175:diagnosis / Q000532:radiotherapy / Q000556:secondary; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D011237:Predictive Value of Tests; D011471:Prostatic Neoplasms / Q000175:diagnosis; D013997:Time Factors; D016896:Treatment Outcome