Internal Structural Changes in the Hippocampus Observed on 3-Tesla MRI in Patients with Mesial Temporal Lobe Epilepsy

Mitsueda-Ono, Takahiro; Ikeda, Akio; Sawamoto, Nobukatsu; Hanakawa, Takashi; Kinoshita, Masako; Matsumoto, Riki; Mikuni, Nobuhiro; Amano, Shigeru; Fukuyama, Hidenao; Takahashi, Ryōsuke

doi:10.2169/internalmedicine.52.8852

Cited by 13 publications

(10 citation statements)

References 26 publications

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“…Therefore, it is reasonable to consider that an AR 6% or more indicates pathologic hippocampal atrophy . In some dogs in this study, the difference in the unilateral volume of the hippocampus was visible during a visual radiological evaluation of the MRI scans, which is also described in human patients with mTLE . A volumetric analysis of chosen intracranial structures is used to support the radiological evaluation of subtle changes in brain tissue in MRI images .…”

Section: Discussionmentioning

confidence: 65%

Comparison of electroencephalographic findings with hippocampal magnetic resonance imaging volumetry in dogs with idiopathic epilepsy

Czerwik

Płonek

Podgórski

et al. 2018

Veterinary Internal Medicne

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Background: In humans, temporal lobe epilepsy (TLE), is a type of focal epilepsy occurring mainly in the mesial TLE (mTLE), commonly associated with hippocampal sclerosis (HS). Objectives: According to recent studies, TLE might also occur in dogs and could be associated with hippocampal atrophy (HA)/HS. To date, hippocampal lesions have not been correlated with electroencephalographic (EEG) findings in epileptic dogs. Animals: An EEG examination, brain magnetic resonance imaging, and volumetric assessment of the hippocampus were performed in 16 nonepileptic and 41 epileptic dogs. Methods: In this retrospective study, the presence and localization of EEG‐defined epileptiform discharges (EDs) was blindly evaluated. The hippocampus was measured and assessed for unilateral atrophy. The results of EEG and volumetric findings were correlated to determine whether the functional epileptic focus is equivalent to structural changes. Results: The median hippocampal asymmetric ratio (AR) in epileptic dogs was significantly greater than in the control group (P < .001). Using a cut‐off threshold AR of >6%, 56% (23/41) of the dogs were characterized with unilateral HA. Of those animals, 35% (8/23) had EDs in the temporal leads and 26% (6/23) had no EDs. In 88% (7/8) of dogs with EDs in the temporal leads that had unilateral HA, the EDs correlated with the side of the decreased hippocampal volume. Conclusions and Clinical Importance: The results indicate an association between the presence of EDs detectable on EEG and a decrease in the unilateral hippocampal volume in some cases of canine idiopathic epilepsy that might reflect features of human mTLE.

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Section: Discussionmentioning

confidence: 65%

Comparison of electroencephalographic findings with hippocampal magnetic resonance imaging volumetry in dogs with idiopathic epilepsy

Czerwik

Płonek

Podgórski

et al. 2018

Veterinary Internal Medicne

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“…Although this explanation is not conclusive, as no correlation has been established between T 2 HP changes and cell loss, the expression of aquaporin 4, and T 2 relaxation time are increased in the hippocampal region after pilocarpine-induced status (17) and in sclerotic hippocampus in human TLE (48). Other factors, as astrogliosis may contribute to T 2 HP changes and should be addressed in future studies, as recently reported in patients with mesial temporal epilepsy (49). …”

Section: Discussionmentioning

confidence: 77%

Changes in Hippocampal Volume are Correlated with Cell Loss but Not with Seizure Frequency in Two Chronic Models of Temporal Lobe Epilepsy

et al. 2014

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Kainic acid (KA) or pilocarpine (PILO) have been used in rats to model human temporal lobe epilepsy (TLE) but the distribution and severity of structural lesions between these two models may differ. Magnetic resonance imaging (MRI) studies have used quantitative measurements of hippocampal T2 (T2HP) relaxation time and volume, but simultaneous comparative results have not been reported yet. The aim of this study was to compare the MRI T2HP and volume with histological data and frequency of seizures in both models. KA- and PILO-treated rats were imaged with a 2 T MRI scanner. T2HP and volume values were correlated with the number of cells, mossy fiber sprouting, and spontaneous recurrent seizures (SRS) frequency over the 9 months following status epilepticus (SE). Compared to controls, KA-treated rats had unaltered T2HP, pronounced reduction in hippocampal volume and concomitant cell reduction in granule cell layer, CA1 and CA3 at 3 months post SE. In contrast, hippocampal volume was unchanged in PILO-treated animals despite detectable increased T2HP and cell loss in granule cell layer, CA1 and CA3. In the following 6 months, MRI hippocampal volume remained stable with increase of T2HP signal in the KA-treated group. The number of CA1 and CA3 cells was smaller than age-matched CTL group. In contrast, PILO group had MRI volumetric reduction accompanied by reduction in the number of CA1 and CA3 cells. In this group, T2HP signal was unaltered at 6 or 9 months after status. Reductions in the number of cells were not progressive in both models. Notably, the SRS frequency was higher in PILO than in the KA model. The volumetry data correlated well with tissue damage in the epileptic brain, suggesting that MRI may be useful for tracking longitudinal hippocampal changes, allowing the assessment of individual variability and disease progression. Our results indicate that the temporal changes in hippocampal morphology are distinct for both models of TLE and that these are not significantly correlated to the frequency of SRS.

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“…In the last decade, MRI technical improvements, including high-resolution imaging and high-field MRI, have yielded increased sensitivity in detecting subtle abnormalities. [25][26][27][28][29] However, a relatively long acquisition time is required for high-resolution images, which can be uncomfortable or inconvenient for patients and result in blurred images caused by patient motion. To reduce motion artifacts associated with a long acquisition time, the most effective solution is shortening the image acquisition time.…”

Section: Discussionmentioning

confidence: 99%

Deep Learning Based Noise Reduction for Brain MR Imaging: Tests on Phantoms and Healthy Volunteers

Kidoh

Shinoda

Kitajima

et al. 2020

MRMS

168

119

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Purpose:To test whether our proposed denoising approach with deep learning-based reconstruction (dDLR) can effectively denoise brain MR images. Methods:In an initial experimental study, we obtained brain images from five volunteers and added different artificial noise levels. Denoising was applied to the modified images using a denoising convolutional neural network (DnCNN), a shrinkage convolutional neural network (SCNN), and dDLR. Using these brain MR images, we compared the structural similarity (SSIM) index and peak signal-to-noise ratio (PSNR) between the three denoising methods. Two neuroradiologists assessed the image quality of the three types of images. In the clinical study, we evaluated the denoising effect of dDLR in brain images with different levels of actual noise such as thermal noise. Specifically, we obtained 2D-T 2 -weighted image, 2D-fluid-attenuated inversion recovery (FLAIR) and 3D-magnetization-prepared rapid acquisition with gradient echo (MPRAGE) from 15 healthy volunteers at two different settings for the number of image acquisitions (NAQ): NAQ2 and NAQ5. We reconstructed dDLR-processed NAQ2 from NAQ2, then compared with SSIM and PSNR. Two neuroradiologists separately assessed the image quality of NAQ5, NAQ2 and dDLR-NAQ2. Statistical analysis was performed in the experimental and clinical study. In the clinical study, the inter-observer agreement was also assessed. Results:In the experimental study, PSNR and SSIM for dDLR were statistically higher than those of DnCNN and SCNN (P < 0.001). The image quality of dDLR was also superior to DnCNN and SCNN. In the clinical study, dDLR-NAQ2 was significantly better than NAQ2 images for SSIM and PSNR in all three sequences (P < 0.05), except for PSNR in FLAIR. For all qualitative items, dDLR-NAQ2 had equivalent or better image quality than NAQ5, and superior quality to that of NAQ2 (P < 0.05), for all criteria except artifact. The inter-observer agreement ranged from substantial to near perfect.Conclusion: dDLR reduces image noise while preserving image quality on brain MR images.

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Internal Structural Changes in the Hippocampus Observed on 3-Tesla MRI in Patients with Mesial Temporal Lobe Epilepsy

Cited by 13 publications

References 26 publications

Comparison of electroencephalographic findings with hippocampal magnetic resonance imaging volumetry in dogs with idiopathic epilepsy

Comparison of electroencephalographic findings with hippocampal magnetic resonance imaging volumetry in dogs with idiopathic epilepsy

Changes in Hippocampal Volume are Correlated with Cell Loss but Not with Seizure Frequency in Two Chronic Models of Temporal Lobe Epilepsy

Deep Learning Based Noise Reduction for Brain MR Imaging: Tests on Phantoms and Healthy Volunteers

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