title: Predictive value of multimodality MRI using conventional, perfusion, and spectroscopy MR in anaplastic transformation of low-grade oligodendrogliomas.
abstract: The aim of our study was to evaluate the role of proton magnetic resonance (MR) spectroscopy and MR perfusion in the follow-up of low-grade gliomas, since conventional MR imaging (MRI) is not reliable in detecting the passage from a low- to high-grade tumor. Twenty-one patients with a World Health Organisation (WHO) grade II glioma were followed up using proton MR spectroscopy, perfusion, and conventional MRIs. Follow-up MRIs had been performed at the third month of evolution and then twice a year, with an average of five MR studies per patient. Five out of the 21 patients had an anaplastic transformation. A choline to creatine ratio (choline/creatine ratio) above 2.4 is associated with an 83% risk of a malignant transformation in an average delay of 15.4 months. The choline/creatine ratio at this threshold was more efficient than perfusion MR in detecting the anaplastic transformation, with sensitivity of 80% and specificity of 94%. An increased choline/creatine ratio seemed to occur an average 15 months before the elevation of relative cerebral blood volume (rCBV). The mean annual growth of low-grade glioma was 3.65 mm. A growth rate higher than 3 mm per year was also correlated with greater risk of anaplastic transformation. Proton magnetic resonance spectroscopy should be recommended in the follow-up of low-grade gliomas since the choline/creatine ratio can predict anaplastic transformation before perfusion abnormalities, with high positive predictive value of 83%.
authors.affiliation: Department of Radiology, Hospital Lyon Sud, Université de Lyon, Université Lyon 1, Hospices civils de Lyon, Pierre-Benite, France. chadi.hlaihel@gmail.com
authors.forename: Chadi
authors.initials: C
authors.lastname: Hlaihel
authors.forename: Laurent
authors.initials: L
authors.lastname: Guilloton
authors.forename: Jacques
authors.initials: J
authors.lastname: Guyotat
authors.forename: Nathalie
authors.initials: N
authors.lastname: Streichenberger
authors.forename: Jerome
authors.initials: J
authors.lastname: Honnorat
authors.forename: François
authors.initials: F
authors.lastname: Cotton
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000473:pathology*; D002560:Cerebrovascular Circulation / Q000502:physiology; D002794:Choline / Q000378:metabolism; D003287:Contrast Media; D003401:Creatine / Q000378:metabolism; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009837:Oligodendroglioma / Q000473:pathology*; D011522:Protons; D012372:ROC Curve; D012039:Regional Blood Flow
chemical_list: D003287:Contrast Media; D011522:Protons; D003401:Creatine; D002794:Choline