CORTICOSTEROID-INDUCED MAGNETIC-RESONANCE-IMAGING CHANGES IN PATIENTSWITH RECURRENT MALIGNANT GLIOMA

Purpose: We studied corticosteroid-induced magnetic resonance (MR) sca n changes in patients with recurrent malignant glioma to determine if corticosteroid therapy started concurrently with investigational treat ment might yield false-positive responses. Patients and Methods: Ten s ymptomatic patients not on corticosteroids when malignant glioma recur red had a baseline MR scan performed before corticosteroid treatment, followed by serial scans at weekly intervals for 1 month while on dexa methasone (16 mg/d). The maximum cross-sectional areas and volumes of the gadolinium-enhancing regions (tumor) and TS-weighted abnormalities (tumor plus edema) were compared quantitatively and qualitatively for each series of scans. Results: Nine of 10 patients (90%) had a measur able reduction in the size of the gadolinium-enhancing region or TS-we ighted abnormality with corticosteroid treatment. The maximum cross-se ctional area and volume of the gadolinium-enhancing region decreased b y at least 25% in three of 10 patients (30%). The maximum cross-sectio nal area and volume of the T2-weighted abnormality decreased by at lea st 25% in five of 10 patients (50%). Maximum measurable radiologic imp rovement wets evident within 2 weeks in most patients. MR scans were j udged improved by the reporting neuroradiologist in seven of 10 [70%]. These subjective visual improvements were also evident within 2 weeks , but generally described as slight or modest. Conclusion: Corticoster oid-induced MR scan reductions in tumor size may confound the assessme nt of response of recurrent malignant gliomas to investigational agent s. For patients who start corticosteroids for symptom control, investi gational treatment should be delayed until a new baseline MR image is established 2 weeks later. Response is then judged by comparing subseq uent MR scans with the new corticosteroid-influenced baseline image.