PTPS-18APPARENT DIFFUSION COEFFICIENT MEASUREMENT IN PATIENTS WITH DIFFUSE INTRINSIC PONTINE GLIIOMA (DIPG): WORK-IN-PROGRESS

Abstract

BACKGROUND: Pediatric diffuse intrinsic pontine gliomas (DIPG) are pediatric brain tumors with an extremely poor prognosis. Diagnosis has historically been based on magnetic resonance (MR) imaging appearance of the lesion, which demonstrates an expansile pontine lesion; T1 hypo-/T2 hyperintense and without significant contrast enhancement. These imaging findings change during the course of treatment. Efforts have focused on identifying prognostically significant, quantifiable MR characteristics. PURPOSE: Measure the apparent diffusion coefficient (ADC) on serial MR examinations in patients with DIPG. SUBJECTS/METHODS: Medical records of 7 subjects, (2.11 -54.6 years), with the diagnosis of pontine glioma and diffusion imaging were reviewed. MR studies were retrieved from the online Agfa archives. After reviewing the MRIs, images with the most significant enhancing tumor/disease were identified from each patient's most recent/last imaging series. Regions of interest (ROIs) were drawn on the corresponding slices on the ADC maps. Similar ROIs were drawn on the same slices from prior examinations for each patient. Control ROI was obtained from measurements on normal appearing cerebellar white matter bilaterally. ADC values were recorded. Right and left values were combined for the pontine and cerebellar ROIs. Adjusted values were calculated for time points by dividing the pontine by the cerebellar value compensating for differences in the diffusion B-Value and scanner to scanner imaging parameter variability. Adjusted ADC values were plotted against the patient's age at the time of each MRI. A graph with ADC value vs. the number days remaining before patient's death (or last imaging study) was generated, reflecting patient's survival. RESULTS: We identified different patterns of change in the ADC over time for each patient. ADC values were higher than normal in all patients though interpatient variability was noted. Clinical significance of these differences is unclear at present. Correlation with clinical parameters, treatments and survival time is a work-in-progress.