title: Tumor volumetric measurements in surgically inaccessible pediatric low-grade glioma.
abstract: Tumor measurement is important in unresectable pediatric low-grade gliomas (pLGGs) to determine either the need for treatment or assess response. Standard methods measure the product of the largest 2 lengths from transverse, anterior-posterior, and cranio-caudal dimensions (SM, cm). This single-institution study evaluated tumor volume measurements (VM, cm) in such pLGGs. Of 50 patients treated with chemotherapy for surgically inaccessible pLGG, 8 met the inclusion criteria of having 2 or more sequential MRI studies of T1-weighted Fast-Spoiled Gradient Recalled acquisition. SM and VM were performed by 2 independent neuroradiologists. Associations of measurement methods with defined therapeutic response criteria and patient clinical status were assessed. The mean tumor size at the first MRI scan was 20 cm and 398 cm according to SM and VM, respectively. VM results did not differ significantly from SM-derived spherical volume calculations (Pearson correlation, P<0.0001) with a high interrater reliability. Both methods were concordant in defining the tumor response according to the current criteria, although radiologic progressive disease was not associated with clinical status (SM: P=0.491, VM: P=0.208). In this limited experience, volumetric analysis of unresectable pLGGs did not seem superior to the standard linear measurements for defining tumor response.
authors.affiliation: Divisions of *Haematology/Oncology †Neuro-Radiology ‡Neuroscience and Mental Health, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.
authors.forename: John-Paul
authors.initials: JP
authors.lastname: Kilday
authors.forename: Helen
authors.initials: H
authors.lastname: Branson
authors.forename: Conrad
authors.initials: C
authors.lastname: Rockel
authors.forename: Suzanne
authors.initials: S
authors.lastname: Laughlin
authors.forename: Donald
authors.initials: D
authors.lastname: Mabbott
authors.forename: Eric
authors.initials: E
authors.lastname: Bouffet
authors.forename: Ute
authors.initials: U
authors.lastname: Bartels
mesh_terms: D000293:Adolescent; D001932:Brain Neoplasms / Q000473:pathology* / Q000601:surgery; D002648:Child; D002675:Child, Preschool; D005260:Female; D005910:Glioma / Q000473:pathology* / Q000601:surgery; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D060787:Neoplasm Grading; D047368:Tumor Burden