title: Follow-up gliomas after radiotherapy: 1H MR spectroscopic imaging for increasing diagnostic accuracy.
abstract: We evaluated the value of magnetic resonance imaging (MRI) and the additional benefit of proton MR spectroscopic imaging (1H SI) in patients with a new suspicious lesion after fractionated stereotactic radiotherapy (FSRT) of a glioma. Thirty-four patients with histologically proven astrocytoma WHO II-IV after treatment by FSRT and a new suspect lesion in the follow-up were included in this study. Data were analysed by three independent radiologists with different experience in 1H SI: Data were verified by clinical follow-up (PT, progressive tumour; nPT, non-progressive tumour) and a kappa analysis was performed. Sensitivity and specificity of T1 weighted (w) and T2w MRI was compared (imaging at radiotherapy and follow-up) using further follow-up controls as gold standard and the additional benefit of 1H SI (imaging at follow-up) was calculated. Mean interval between last irradiation and detection of a suspicious lesion was 37 +/- 32 months. Time to clinical evaluation was 13 +/- 8 months. Interobserver agreement was significantly high in all analyses (kappa always >0.8, P < 0.05). T2w imaging proved to be superior to contrast enhanced T1w imaging in sensitivity (87.5 vs 81.25%) and specificity (85.7 vs 57.1%). Solitary 1H SI had similar results as T2w (sensitivity 87.5%, specificity 71.4%). Taking all techniques into account, all PT were correctly diagnosed. Radiologists' experience had no significant influence on correct interpretation of a suspicious lesion. We conclude that 1H SI is helpful in characterising new suspicious lesions in irradiated gliomas, particularly if pre-MRI is not available for evaluating follow-up.
authors.affiliation: Department of Radiology, German Cancer Research Center, Heidelberg, Germany. matthias.lichy@med.uni-tuebingen.de
authors.forename: Matthias Philipp
authors.initials: MP
authors.lastname: Lichy
authors.forename: Christian
authors.initials: C
authors.lastname: Plathow
authors.forename: Daniela
authors.initials: D
authors.lastname: Schulz-Ertner
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Kauczor
authors.forename: Heinz-Peter
authors.initials: HP
authors.lastname: Schlemmer
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016477:Artifacts; D001254:Astrocytoma / Q000473:pathology* / Q000532:radiotherapy; D001932:Brain Neoplasms / Q000473:pathology* / Q000532:radiotherapy; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D012680:Sensitivity and Specificity; D016896:Treatment Outcome