Neuroimaging features of neurodegeneration with brain iron accumulation

Abstract

NBIA characterizes a class of neurodegenerative diseases that feature a prominent extrapyramidal movement disorder, intellectual deterioration, and a characteristic deposition of iron in the basal ganglia. The diagnosis of NBIA is made on the basis of the combination of representative clinical features along with MR imaging evidence of iron accumulation. In many cases, confirmatory molecular genetic testing is now available as well. A number of new subtypes of NBIA have recently been described, with distinct neuroradiologic and clinical features. This article outlines the known subtypes of NBIA, delineates their clinical and radiographic features, and suggests an algorithm for evaluation.

Fig 1.

T2-weighted MR imaging appearance of a healthy 60-year-old woman (A), a 66-year-old woman with idiopathic Parkinson disease (B), and a 16-year-old female patient with idiopathic NBIA (C) obtained on a 1.5T scanner by using standard clinical TEs and TRs.

Fig 2.

A clinical- and neuroimaging-based algorithm for evaluating patients with suspected NBIA. BG indicates basal ganglia; WM, white matter; FFF, facial-faucial-finger.

Fig 3.

PKAN. A and B, The eye-of-the-tiger sign begins with T2 hyperintensity within the globus pallidus. C and D, Iron subsequently accumulates with time. Cerebral and/or cerebellar atrophy and white matter hyperintensity are not typical features.

Fig 4.

NFT. A, Patchy hypointensity is typically seen within multiple deep gray nuclei, including the caudate, putamen, globus pallidus, and thalamus in symptomatic cases. B, Concurrent T2 hyperintensities (cavitation) may be seen within regions of hypointensity. Images courtesy of P.F. Chinnery.

Fig 5.

NAD. Iron deposition may be seen in the globus pallidus (A) and the substantia nigra (B) on T2* and T2 images. C, Confluent white matter hyperintensities may be seen on fluid-attenuated inversion recovery sequences as well. D, Global cerebellar atrophy is a frequent feature.

Fig 6.

ACP. A and B, More homogeneous iron deposition is seen within the basal ganglia, with juxtaposed confluent white matter hyperintensities on T2-weighted sequences. Images courtesy of H. Miyajima.

Fig 7.

FAHN. Evidence of iron deposition in the globus pallidus (A) and, to a lesser extent, the substantia nigra (B) may be seen on T2-weighted images. C, Confluent white matter abnormalities may be apparent on T2/fluid-attenuated inversion recovery sequences. D, Mild cerebral atrophy may occur, along with significant pontocerebellar atrophy and thinning of the corpus callosum (A).

Fig 8.

KRS. Globus pallidus, caudate, and putamen hypointensity may be seen on T2-weighted images (A and B), in addition to generalized cerebral and cerebellar atrophy (A and C).

Fig 9.

WSS. Extensive confluent white matter T2 hyperintensity is typical of the disorder (A and C), while hypointensity of the globus pallidus on T2 sequences is an inconsistent feature (B). Images courtesy of S. Bohlega.

Fig 10.

SENDA. Hypointensity of the globus pallidus (A) is overshadowed by that of the substantia nigra and cerebral peduncles (B) on T2-weighted imaging. C, T1 sequences demonstrate hyperintensity of the substantia nigra and cerebral peduncles with central linear hypointensity. D, Global cerebral atrophy is also a feature.