Contrast-enhanced fluid-attenuated inversion recovery imaging for leptomeningeal disease in children

Abstract

Background and purpose: To develop an MR imaging method that improves detection of leptomeningeal disease when compared with the current reference standard, contrast-enhanced T1-weighted imaging.

Methods: We investigated the cases of 10 children who were at high risk of intracranial leptomeningeal disease (Sturge-Weber syndrome and medulloblastoma). The cases of Sturge-Weber syndrome were investigated by using one MR imaging examination, and the cases of medulloblastoma were investigated by using four MR imaging examinations performed over 18 months. In all cases, contrast-enhanced fluid-attenuated inversion recovery (FLAIR) images were acquired in addition to the routine sequences. The parameters of the FLAIR sequence were chosen to maximize the T1 component of the signal intensity, to maximize detection of leptomeningeal enhancement. We made subjective and objective assessments of the presence and extent of leptomeningeal disease as shown on contrast-enhanced T1-weighted images and contrast-enhanced FLAIR images.

Results: In three of the four cases of Sturge-Weber syndrome, the T1 and FLAIR sequences showed comparable extent of leptomeningeal enhancement. For one child, FLAIR images showed unexpected bilateral disease and more extensive leptomeningeal enhancement on the clinically suspected side. In four of six cases of medulloblastoma, no leptomeningeal enhancement was shown on any examinations during the 18-month period. In two cases, FLAIR images showed more extensive leptomeningeal enhancement when compared with T1-weighted images.

Conclusion: Contrast-enhanced FLAIR imaging seems to improve detection of leptomeningeal disease when compared with routine contrast-enhanced T1-weighted imaging. This seems to be partly because of suppression of signal intensity from normal vascular structures on the surface of the brain by FLAIR, which allows easier visualization of abnormal leptomeninges. We think that these findings can be extrapolated to the investigation of leptomeningeal disease of all causes and at all ages.

Fig 1.

Images from the case of a 9-year-old child with suspected left-sided Sturge-Weber syndrome. A, Axial view contrast-enhanced T1-weighted image obtained at the level of the Monro foramina. Note the prominent but normal enhancement of vascular structures in the right hemisphere. B, Axial view contrast-enhanced FLAIR image obtained at the level of the Monro foramina shows the improved visualization of leptomeningeal disease in the left temporal lobe. Note that enhancement of normal vascular structures in the right hemisphere is suppressed. C, Axial view contrast-enhanced T1-weighted image obtained toward the vertex. D, Axial view contrast-enhanced FLAIR image obtained toward the vertex shows considerably more enhancement in the left frontal lobe as compared with the T1-weighted image. More importantly, abnormal leptomeningeal enhancement is shown over the right frontal lobe, indicating bilateral disease. The presence of bilateral disease precluded surgical intervention.

Fig 2.

Images from the case of a 3-year-old patient who presented with early morning headache and vomiting headache. A mass in the fourth ventricle was shown to be a medulloblastoma. A, Axial view contrast-enhanced T1-weighted image obtained at presentation showed extensive leptomeningeal spread. B, Significant response to treatment was achieved by 6 months, with no residual disease evident on the T1-weighted image. C, Contrast-enhanced FLAIR image did show leptomeningeal enhancement in the right frontal lobe (arrows) that could be seen in retrospect on the T1-weighted image. D, Contrast-enhanced T1-weighted image obtained at 12 months showed progressive disease in the right frontal lobe. E, Contrast-enhanced T1-weighted image obtained at 18 months also showed progressive disease in the right frontal lobe.

Fig 3.

Images from the case of a 2-year-old patient who presented with symptoms and signs suggestive of a posterior fossa mass. A, Coronal view contrast-enhanced T1-weighted image shows a large mass centered in the right cerebellar hemisphere that was confirmed to be medulloblastoma. No evidence of intracranial metastases was observed at presentation. B, Contrast-enhanced FLAIR image obtained at 6 months shows definite abnormality in the meninges overlying the left parietal lobe (arrow). C, In retrospect, this region is viewed as abnormal on the contrast-enhanced T1-weighted image, although it was reported as normal. D, Contrast-enhanced T1-weighted image obtained at 12 months shows definite progression. E, Contrast-enhanced T1-weighted image obtained at 18 months also shows definite progression.