3D Texture Analysis Reveals Imperceptible MRI Textural Alterations in the Thalamus and Putamen in Progressive Myoclonic Epilepsy Type 1, EPM1

Sanna Suoranta,Eini Niskanen,Mervi Könönen,Marja Äikiä,Ritva Vanninen,Hannu Eskola,Reetta Kälviäinen,Päivi Koskenkorva,Kirsi Holli-Helenius,Hemachandra Reddy

doi:10.1371/journal.pone.0069905

Abstract

Progressive myoclonic epilepsy type 1 (EPM1) is an autosomal recessively inherited neurodegenerative disorder characterized by young onset age, myoclonus and tonic-clonic epileptic seizures. At the time of diagnosis, the visual assessment of the brain MRI is usually normal, with no major changes found later. Therefore, we utilized texture analysis (TA) to characterize and classify the underlying properties of the affected brain tissue by means of 3D texture features. Sixteen genetically verified patients with EPM1 and 16 healthy controls were included in the study. TA was performed upon 3D volumes of interest that were placed bilaterally in the thalamus, amygdala, hippocampus, caudate nucleus and putamen. Compared to the healthy controls, EPM1 patients had significant textural differences especially in the thalamus and right putamen. The most significantly differing texture features included parameters that measure the complexity and heterogeneity of the tissue, such as the co-occurrence matrix-based entropy and angular second moment, and also the run-length matrix-based parameters of gray-level non-uniformity, short run emphasis and long run emphasis. This study demonstrates the usability of 3D TA for extracting additional information from MR images. Textural alterations which suggest complex, coarse and heterogeneous appearance were found bilaterally in the thalamus, supporting the previous literature on thalamic pathology in EPM1. The observed putamenal involvement is a novel finding. Our results encourage further studies on the clinical applications, feasibility, reproducibility and reliability of 3D TA.

Highlights

Progressive myoclonic epilepsy type 1 or Unverricht-Lundborg disease (EPM1, ULD, OMIM 254800) is the most common type of progressive myoclonic epilepsy [1]
The present study shows that MRI-based texture analysis reveals imperceptible alterations in EPM1 patients, especially in the thalamus
Three dimensional texture analysis (TA) is a novel method for the analysis of MR images of the brain, and according to our results, 3D TA is able to provide subtle information of the structures of deep gray matter in EPM1 patients that could not be detected by direct visual inspection of the images

Summary

Introduction

Progressive myoclonic epilepsy type 1 or Unverricht-Lundborg disease (EPM1, ULD, OMIM 254800) is the most common type of progressive myoclonic epilepsy [1]. It is an autosomal recessively inherited neurodegenerative disorder caused by mutations in the cystatin B gene (CSTB) [2,3,4]. Sporadic cases of EPM1 have been reported worldwide [6]. The first symptoms of EPM1 are commonly stimulus-sensitive myoclonic jerks and generalized tonic-clonic epileptic seizures. [6] Mild cognitive impairment and slow decline in intellectual level over time have been reported [6,7,8,9] The clinical symptoms can be so mild that there is a delay in the diagnosis and patients may manage well. [6] Mild cognitive impairment and slow decline in intellectual level over time have been reported [6,7,8,9]

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