Longitudinal Assessment Of Enhancing Foci Of Abnormal Signal Intensity In Neurofibromatosis Type 1

BACKGROUND AND PURPOSE:Patients with neurofibromatosis 1 are at increased risk of developing brain tumors, and differentiation from contrast-enhancing foci of abnormal signal intensity can be challenging. We aimed to longitudinally characterize rare, enhancing foci of abnormal signal intensity based on location and demographics.MATERIALS AND METHODS:A total of 109 MR imaging datasets from 19 consecutive patients (7 male; mean age, 8.6?years; range, 2.3?16.8 years) with neurofibromatosis 1 and a total of 23 contrast-enhancing parenchymal lesions initially classified as foci of abnormal signal intensity were included. The mean follow-up period was 6.5?years (range, 1?13.8 years). Enhancing foci of abnormal signal intensity were followed up with respect to presence, location, and volume. Linear regression analysis was performed.RESULTS:Location, mean peak volume, and decrease in enhancing volume over time of the 23 lesions were as follows: 10 splenium of the corpus callosum (295?mm(3), 5 decreasing, 3 completely resolving, 2 surgical intervention for change in imaging appearance later confirmed to be gangliocytoma and astrocytoma WHO II), 1 body of the corpus callosum (44?mm(3), decreasing), 2 frontal lobe white matter (32?mm(3), 1 completely resolving), 3 globus pallidus (50?mm(3), all completely resolving), 6 cerebellum (206?mm(3), 3 decreasing, 1 completely resolving), and 1 midbrain (34?mm(3)). On average, splenium lesions began to decrease in size at 12.2?years, posterior fossa lesions at 17.1?years, and other locations at 9.4?years of age.CONCLUSIONS:Albeit very rare, contrast-enhancing lesions in patients with neurofibromatosis 1 may regress over time. Follow-up MR imaging aids in ascertaining regression. The development of atypical features should prompt further evaluation for underlying tumors.