Susceptibility-Weighted Imaging in Neurodegeneration in Langerhans Cell Histiocytosis

A 15-year-old boy with confirmed Langerhans cell histiocytosis (LCH) was referred for magnetic resonance imaging (MRI). Conventional MRI, using T1- and T2-weighted sequences, detected bilateral T2-hyperintense and T1-hypointense, non-contrast-enhancing signal alterations within the pons, dentate nuclei, and adjacent cerebellar white matter (Figure 1). In addition, discrete T1-hyperintense calcifications were noted in the globus pallidus. These lesions represent the classical pattern of neurodegeneration in LCH (ND-LCH).1

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Figure 1 T2-hyperintense lesions in the brainstem and dentate nuclei.

Susceptibility-weighted imaging (SWI) is a newly developed MRI sequence that is highly sensitive for intraparenchymal calcifications and hemorrhages because of its pulse design.2 The calcifications in the globus pallidus identified on T1-weighted sequences were more conspicuous on SWI. SWI also revealed additional calicifications affecting the substantia nigra that were not prospectively recognized on either conventional T1- or T2-weighted sequences (Figure 2).

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Figure 2 Bilateral SWI-hypointense calcifications in the substantia nigra and globus pallidus.

SWI should be added to conventional MRI in patients with ND-LCH. SWI may reveal areas of tissue injury that go undetected on conventional MRI. SWI's ability to more precisely identify the complete extent of ND-LCH and the apparent selective injury of certain gray matter structures, like the substantia nigra, may provide increased insight into neurologic symptoms, mechanisms of injury, and disease progression.