Publications by authors named "Hitoshi Matsuzawa"

33 Publications

Deep learning-based diagnosis of temporal lobe epilepsy associated with hippocampal sclerosis: An MRI study.

Epilepsy Res 2021 Dec 21;178:106815. Epub 2021 Nov 21.

Department of Neurosurgery, Brain Research Institute, Niigata University, Japan.

Purpose: The currently available indicators-sensitivity and specificity of expert radiological evaluation of MRIs-to identify mesial temporal lobe epilepsy (MTLE) associated with hippocampal sclerosis (HS) are deficient, as they cannot be easily assessed. We developed and investigated the use of a novel convolutional neural network trained on preoperative MRIs to aid diagnosis of these conditions.

Subjects And Methods: We enrolled 141 individuals: 85 with clinically diagnosed mesial temporal lobe epilepsy (MTLE) and hippocampal sclerosis International League Against Epilepsy (HS ILAE) type 1 who had undergone anterior temporal lobe hippocampectomy were assigned to the MTLE-HS group, and 56 epilepsy clinic outpatients diagnosed as nonepileptic were assigned to the normal group. We fine-tuned a modified CNN (mCNN) to classify the fully connected layers of ImageNet-pretrained VGG16 network models into the MTLE-HS and control groups. MTLE-HS was diagnosed using MRI both by the fine-tuned mCNN and epilepsy specialists. Their performances were compared.

Results: The fine-tuned mCNN achieved excellent diagnostic performance, including 91.1% [85%, 96%] mean sensitivity and 83.5% [75%, 91%] mean specificity. The area under the resulting receiver operating characteristic curve was 0.94 [0.90, 0.98] (DeLong's method). Expert interpretation of the same image data achieved a mean sensitivity of 73.1% [65%, 82%] and specificity of 66.3% [50%, 82%]. These confidence intervals were located entirely under the receiver operating characteristic curve of the fine-tuned mCNN.

Conclusions: Deep learning-based diagnosis of MTLE-HS from preoperative MR images using our fine-tuned mCNN achieved a performance superior to the visual interpretation by epilepsy specialists. Our model could serve as a useful preoperative diagnostic tool for ascertaining hippocampal atrophy in patients with MTLE.
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http://dx.doi.org/10.1016/j.eplepsyres.2021.106815DOI Listing
December 2021

Detecting intertrochanteric hip fractures with orthopedist-level accuracy using a deep convolutional neural network.

Skeletal Radiol 2019 Feb 28;48(2):239-244. Epub 2018 Jun 28.

Division of Orthopedic Surgery, Department of Regenerative and Transplant Medicine, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-Dori, Niigata, 951-8510, Japan.

Objective: To compare performances in diagnosing intertrochanteric hip fractures from proximal femoral radiographs between a convolutional neural network and orthopedic surgeons.

Materials And Methods: In total, 1773 patients were enrolled in this study. Hip plain radiographs from these patients were cropped to display only proximal fractured and non-fractured femurs. Images showing pseudarthrosis after femoral neck fracture and those showing artificial objects were excluded. This yielded a total of 3346 hip images (1773 fractured and 1573 non-fractured hip images) that were used to compare performances between the convolutional neural network and five orthopedic surgeons.

Results: The convolutional neural network and orthopedic surgeons had accuracies of 95.5% (95% CI = 93.1-97.6) and 92.2% (95% CI = 89.2-94.9), sensitivities of 93.9% (95% CI = 90.1-97.1) and 88.3% (95% CI = 83.3-92.8), and specificities of 97.4% (95% CI = 94.5-99.4) and 96.8% (95% CI = 95.1-98.4), respectively.

Conclusions: The performance of the convolutional neural network exceeded that of orthopedic surgeons in detecting intertrochanteric hip fractures from proximal femoral radiographs under limited conditions. The convolutional neural network has a significant potential to be a useful tool for screening for fractures on plain radiographs, especially in the emergency room, where orthopedic surgeons are not readily available.
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http://dx.doi.org/10.1007/s00256-018-3016-3DOI Listing
February 2019

Inferior colliculus syndrome: Clinical magnetic resonance microscopy anatomic analysis on a 7 T system.

SAGE Open Med Case Rep 2017 5;5:2050313X17745209. Epub 2017 Dec 5.

Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata, Japan.

We performed detailed structural analysis of a case of a unilateral lesion of the inferior colliculus using magnetic resonance microscopy on a 7 T system. A 36-year-old right-handed man had an intracerebral hemorrhage circumscribed to the right inferior colliculus. Following recovery from the acute phase, he had only residual left ear tinnitus and left trochlear palsy and no hearing loss. Microscopic imaging analysis on a 7 T magnetic resonance imaging system demonstrated a chronic lesion confined primarily to the right central nucleus of the inferior colliculus. Sound localization was significantly impaired in the contralateral hemispace. The case confirms prior clinical reports of unilateral inferior colliculus dysfunction, the specific anatomic characterization of which was demonstrated in this case by magnetic resonance microscopy. It furthermore supports the notion that central nucleus of the inferior colliculus dysfunction can produce tinnitus and sound localization deficits, without hearing loss.
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http://dx.doi.org/10.1177/2050313X17745209DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5721957PMC
December 2017

High-contrast high-resolution imaging of posttraumatic mandibular nerve by 3DAC-PROPELLER magnetic resonance imaging: correlation with the severity of sensory disturbance.

Oral Surg Oral Med Oral Pathol Oral Radiol 2017 Jul 14;124(1):85-94. Epub 2017 Mar 14.

Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata, Japan.

Objective: Magnetic resonance neurography reveals abnormal morphologies of regenerated nerves and overgrown connective tissue in injured trigeminal nerves, suggesting neuroma formation. We hypothesized that such deformities and scar formation contribute to pain symptoms.

Study Design: High-contrast high-resolution magnetic resonance imaging was utilized to evaluate the inferior alveolar nerve and lingual nerve following traumatic injury in 19 patients. The relationship between the morphologic classification and severity of the sensory disorder was assessed.

Results: In all cases, 3-dimensional anisotropy contrast periodically rotated overlapping parallel lines with enhanced reconstruction (3DAC-PROPELLER) successfully revealed the inner structures within the lesion. The isolated type represented the normal course of the nerve isolated from scar-like tissue (8 cases), whereas the deformity type included the deformed nerve either within scar-like tissue or by itself, unassociated with surrounding scar-like tissue (9 cases). In the remaining 2 cases, the nerve tissue and scar-like tissue were incorporated. Patients with the deformity type exhibited significantly more severe pain symptoms compared with patients with the isolated type.

Conclusions: Overgrown connective tissue does not necessarily block regenerating nerves and itself may not cause pain. The morphologic findings on the 3DAC-PROPELLER were relevant to the severity of pain symptoms.
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http://dx.doi.org/10.1016/j.oooo.2017.02.017DOI Listing
July 2017

[Brain Function and the Fiber Tract:Visualization of the Neural Tract].

No Shinkei Geka 2015 Sep;43(9):787-801

Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata.

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http://dx.doi.org/10.11477/mf.1436203124DOI Listing
September 2015

[Application of brain diffusion-weighted imaging performed using readout segmentation of long variable echo trains].

No Shinkei Geka 2015 Jan;43(1):31-40

Shinjinkai, Kitanihon Noshinkeigeka Hospital.

We report the preliminary use of the readout segmentation of long variable echo trains(RESOLVE)sequence, a novel magnetic resonance(MR)scanning technique based on a readout segmented echo planar imaging(EPI)strategy. RESOLVE enables high-resolution diffusion-weighted imaging(DWI)by minimizing susceptibility distortions and T2* blurring. The software for this sequence was provided by Siemens AG, Germany. Previously, we determined appropriate sequence parameters to obtain sufficiently high-resolution images through phantom studies. Then, we applied the sequence to some clinical cases with neurological disorders and analyzed the RESOLVE-DWI data with diffusion tensor imaging(DTI)techniques. In this article, we report clinical application of the RESOLVE sequence in two cases, one with cerebellar infarction and one with an intracranial epidermoid cyst. In both cases, RESOLVE-DWI clearly exposed structures that were obscured or severely distorted by artifacts on usual single-shot EPI-DWI. DTI analyses for RESOLVE-DWI data provided detailed information about fiber tracts and cranial nerves.
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http://dx.doi.org/10.11477/mf.1436202942DOI Listing
January 2015

Expansion of sensorimotor cortical activation for unilateral hand motion during contralateral hand deafferentation.

Neuroreport 2014 Apr;25(6):435-9

aDepartment of Neurosurgery bCenter for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata, Japan.

Acute deprivation of unilateral sensory input rapidly enhances contralateral hand motor function, but the underlying mechanisms remain poorly understood. We herein used functional MRI to evaluate, in 14 healthy individuals, motor cortical activation for right finger motion before, during, and after sensory deprivation of left forearm induced by reversible, noninvasive ischemic nerve block (INB). Before INB, the motor task activated the left primary sensorimotor cortex (SM1) as expected. During INB, the volume of the left SM1 activation significantly increased, and, after INB, it returned to the pre-INB, baseline level. The effectiveness of the INB of the left forearm was ensured by confirming disappearance of the activation in right primary sensory cortex that is normally caused by tactile stimulation of the left index finger. These findings demonstrate that acute deafferentation of unilateral forearm causes rapid and reversible changes in the neural substrates for contralateral finger motion, mediated possibly by attenuation of transcallosal interhemispheric inhibition.
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http://dx.doi.org/10.1097/WNR.0000000000000138DOI Listing
April 2014

Detectability of neural tracts and nuclei in the brainstem utilizing 3DAC-PROPELLER.

J Neuroimaging 2014 May-Jun;24(3):238-44. Epub 2013 Apr 22.

From the Department of Neurosurgery, Brain Research Institute, University of Niigata, Niigata, Japan.

Despite clinical importance of identifying exact anatomical location of neural tracts and nuclei in the brainstem, no neuroimaging studies have validated the detectability of these structures. The aim of this study was to assess the detectability of the structures using three-dimensional anisotropy contrast-periodically rotated overlapping parallel lines with enhanced reconstruction (3DAC-PROPELLER) imaging. Forty healthy volunteers (21 males, 19 females; 19-53 years, average 23.4 years) participated in this study. 3DAC-PROPELLER axial images were obtained with a 3T-MR system at four levels of the brainstem: the lower midbrain, upper and lower pons, and medulla oblongata. Three experts independently judged whether five tracts (corticospinal tract, medial lemniscus, medial longitudinal fasciculus, central tegmental and spinothalamic tracts) and 10 nuclei (oculomotor and trochlear nuclei, spinal trigeminal, abducens, facial, vestibular, hypoglossal, prepositus, and solitary nuclei, locus ceruleus, superior and inferior olives) on each side could be identified. In total, 240 assessments were made. The five tracts and eight nuclei were identified in all the corresponding assessments, whereas the locus ceruleus and superior olive could not be identified in 3 (1.3%) and 16 (6.7%) assessments, respectively. 3DAC-PROPELLER seems extremely valuable imaging method for mapping out surgical strategies for brainstem lesions.
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http://dx.doi.org/10.1111/jon.12027DOI Listing
April 2015

Protracted delay in taste sensation recovery after surgical lingual nerve repair: a case report.

J Med Case Rep 2013 Mar 18;7:77. Epub 2013 Mar 18.

Division of Dental Anesthesiology, Department of Tissue Regeneration and Reconstruction, Niigata University Graduate School of Medical and Dental Sciences, Course for Oral Sciences, 2-5274 Gakkocho-dori, Chuo-ku, Niigata, 951-8514, Japan.

Introduction: Lingual nerve injury is sometimes caused by dental treatment. Many kinds of treatment have been reported, but many have exhibited poor recovery. Here the authors report changes in somatosensory and chemosensory impairments during a long-term observation after lingual nerve repair.

Case Presentation: A 30-year-old Japanese woman claimed dysesthesia and difficulty eating. Quantitative sensory test results indicated complete loss of sensation in the right side of her tongue. She underwent a repair surgery involving complete resection of her lingual nerve using a polyglycolic acid tube containing collagen 9 months after the injury. A year after the operation, her mechanical touch threshold recovered, but no other sensations recovered. Long-term observation of her somatosensory and chemosensory function after the nerve repair suggested that recovery of taste sensation was greatly delayed compared with that of somatosensory function.

Conclusion: This case shows characteristic changes in somatosensory and chemosensory recoveries during 7 postoperative years and suggests that taste and thermal sensations require a very long time to recover after repair surgery.
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http://dx.doi.org/10.1186/1752-1947-7-77DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3607987PMC
March 2013

Preoperative evaluation of spatial relationship between inferior alveolar nerve and fibro-osseous lesion by high resolution magnetic resonance neurography on 3.0-T system: a case report.

J Oral Maxillofac Surg 2012 Feb;70(2):e119-23

Department of Tissue Regeneration and Reconstruction, Division of Dental Anesthesiology, Graduate School of Medical and Dental Sciences, Course for Oral Life Sciences, Niigata University, Chuo-ku, Niigata, Japan.

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http://dx.doi.org/10.1016/j.joms.2011.10.004DOI Listing
February 2012

Analysis of ascending spinal tract degeneration in cervical spondylotic myelopathy using 3D anisotropy contrast single-shot echo planar imaging on a 3.0-T system.

J Neurosurg Spine 2011 Dec 9;15(6):648-53. Epub 2011 Sep 9.

Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Japan.

Object: The authors assessed the role of 3D anisotropy contrast (3DAC) in evaluating specific ascending tract degeneration in patients with cervical spondylotic myelopathy (CSM).

Methods: The authors studied 10 patients (2 women, 8 men; mean age 59.8 ± 14.6 years) with CSM and spinal cord compression below the C2-3 disc level, as well as 10 healthy control individuals (3 women, 7 men; mean age 42.0 ± 24.1 years). Images of the cervical cord at the C2-3 level were obtained using a 3.0-T MR imaging system.

Results: Three-dimensional anisotropy contrast imaging clearly made possible tract-by-tract analysis of the fasciculus cuneatus, fasciculus gracilis, and spinocerebellar tract. Tract degeneration identified using 3DAC showed good correlation with a decline in fractional anisotropy. Degeneration of the fasciculus gracilis detected by "vector contrast" demonstrated a good correlation with Nurick grades.

Conclusions: The study unambiguously demonstrated that 3DAC imaging is capable of assessing ascending tract degeneration in patients with CSM. Degeneration of an individual tract can be easily identified as a vector contrast change on the 3DAC image, a reflection of quantitative changes in anisotropism, similar to fractional anisotropy. Excellent correlation between Nurick grades and fasciculus gracilis degeneration suggests potential application of 3DAC imaging for tract-by-tract clinical correlation.
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http://dx.doi.org/10.3171/2011.7.SPINE10843DOI Listing
December 2011

Expansion of corticomedullary junction high-susceptibility region (CMJ-HSR) with aging: a clue in the pathogenesis of Alzheimer's disease?

J Neuroimaging 2012 Oct 23;22(4):379-83. Epub 2011 Jun 23.

Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata, Japan.

Background: Susceptibility-weighted imaging (SWI) microscopy on a 7.0T system demonstrated the corticomedullary junction (CMJ) to be a high-susceptibility region (HSR) in young normal subjects, suggesting that functional alteration of cortical microcirculation could be assessed with this imaging method.

Methods: Focused microscopic studies were performed on the parietal association cortex in 74 normal volunteers (ages 20-79 years; 35 female, 39 male) using a SWI algorithm on a system constructed based on General Electric Signa LX (Waukesha, WI, USA), equipped with a 900-mm clear bore superconducting magnet operating at 7.0T.

Results: There was a clear-cut reduction in the thickness of the normal-appearing cortex (cortex, R2 = .5290, P < .001) and expansion of CMJ-HSR (R(2) = .6919, P < .001). The sum of cortex thickness and CMJ-HSR thickness was essentially constant, suggesting that the observed expansion of CMR-HSR with aging likely occurred within the cortical mantle.

Conclusion: CMJ-HSR expands significantly as a function of aging. Since CMJ-HSR represents a functionally distinct area with relatively slow venous flow, the observed expansion is believed to reflect alteration in cerebral microcirculation with increased age, providing another clue for pathogenesis of Alzheimer's disease.
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http://dx.doi.org/10.1111/j.1552-6569.2011.00607.xDOI Listing
October 2012

Functional asymmetry in primary auditory cortex for processing musical sounds: temporal pattern analysis of fMRI time series.

Neuroreport 2011 Jul;22(10):470-3

Center for Integrated Human Brain Science, Brain Research Institute, Sensory and Integrative Medicine, Graduate School of Medical and Dental Sciences, University of Niigata, Japan.

Hemispheric differences in the temporal processing of musical sounds within the primary auditory cortex were investigated using functional magnetic resonance imaging (fMRI) time series analysis on a 3.0 T system in right-handed individuals who had no formal training in music. The two hemispheres exhibited a clear-cut asymmetry in the time pattern of fMRI signals. A large transient signal component was observed in the left primary auditory cortex immediately after the onset of musical sounds, while only sustained activation, without an initial transient component, was seen in the right primary auditory cortex. The observed difference was believed to reflect differential segmentation in primary auditory cortical sound processing. Although the left primary auditory cortex processed the entire 30-s musical sound stimulus as a single event, the right primary auditory cortex had low-level processing of sounds with multiple segmentations of shorter time scales. The study indicated that musical sounds are processed as 'sounds with contents', similar to how language is processed in the left primary auditory cortex.
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http://dx.doi.org/10.1097/WNR.0b013e3283475828DOI Listing
July 2011

Morphologic evaluation of the inferior alveolar nerve in patients with sensory disorders by high-resolution 3D volume rendering magnetic resonance neurography on a 3.0-T system.

Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2011 Jan;111(1):95-102

Center for Integrated Human Brain Science, Division of Dental Anesthesiology, Department of Tissue Regeneration and Reconstruction, Graduate School of Medical and Dental Sciences, University of Niigata, Chuoh-ku, Niigata, Japan.

Objective: The objective of this study was to evaluate the inferior alveolar nerve (IAN) morphologically in patients with symptomatic posttraumatic sensory disorders using magnetic resonance imaging (MRI) on a high-field system.

Study Design: Sixteen patients who complained of persistent sensory disturbance attributed to unilateral IAN injury participated in the investigation. High-resolution 3-dimensional volume rendering magnetic resonance neurography was performed on a 3.0-T MRI system.

Results: In 15 (94%) of 16 patients, high-resolution 3-dimensional volume rendering magnetic resonance neurography demonstrated morphologic abnormalities of the IAN as well as connective tissue overgrowth. These findings were confirmed intraoperatively (6 patients) and histopathologically (5 patients). The duration of sensory disturbance correlated significantly with the pattern of morphologic deformity and connective tissue overgrowth.

Conclusions: The current study clearly demonstrated that appropriate application of clinical MRI techniques can significantly improve the diagnosis and potential treatment of patients with orofacial peripheral nerve disorders.
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http://dx.doi.org/10.1016/j.tripleo.2010.09.002DOI Listing
January 2011

[Neuroscientific application of ultra high-field (7 tesla) MRI].

No Shinkei Geka 2010 Feb;38(2):107-16

Department of Neurosurgery, Brain Research Institute, University of Niigata, 1-757 Asahimachidori, Chuo-ku, Niigata 951-8585, Japan.

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February 2010

Insidious extension of pituitary prolactinoma: two can't-miss findings depicted on a 3.0-T MR system.

J Neuroimaging 2010 Jul 27;20(3):267-71. Epub 2009 Apr 27.

Brain Research Institute, University of Niigata, Department of Neurosurgery, Chuo-ku, Niigata, Japan.

Background: In this article, we present two can't-miss findings on preoperative magnetic resonance imaging (MRI) using a 3.0-T MR system resulting in a better surgical option in prolactinoma treatment after emergent of dopamine agonists.

Methods: We reviewed six cases of pituitary prolactinoma; each had vague or occult bulk of adenoma on 1.5-T MR imaging, which were finally confirmed by surgery. Four cases were preoperatively examined with a 3.0-T MR imaging system. With the 3.0-T MR system, 3-dimension-anisotropy-contrast (3DAC) MR imaging and 3-dimension fast spoiled gradient recalled acquisition in the steady state (3D-FSPGR) imaging were used for depiction of the adenoma.

Results: 3DAC imaging revealed cavernous sinus (CS) pathology in three cases, and multiplanar reconstruction of 3D-FSPGR imaging revealed normal pituitary gland and invasive adenoma into the CS in three cases and creeping extension up to the contralateral side of the CS invasion in four cases.

Conclusions: Two can't-miss findings: (1) intrasellar creeping extension up to the opposite side of the adenoma main body and (2) intracavernous-localized adenoma with indistinct intrasellar mass should be carefully considered when neurosurgeons perform adenomectomy for patients with prolactinoma, even in cases of microprolactinoma.
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http://dx.doi.org/10.1111/j.1552-6569.2009.00364.xDOI Listing
July 2010

Tract-by-tract morphometric and diffusivity analyses in vivo of spinocerebellar degeneration.

J Neuroimaging 2009 Jul 24;19(3):220-6. Epub 2008 Oct 24.

Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata, Japan.

Background And Purpose: Three-dimensional anisotropy contrast (3DAC) based on a periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) sequence on a 3.0 T system is a new magnetic resonance imaging technique capable of providing images with significantly high anatomical resolution. The purpose of this study was to confirm whether this technique can characterize the degenerative processes in the brainstem of patients with spinocerebellar degeneration (SCD).

Methods: 3DAC images of 13 patients with multiple system atrophy with predominant cerebellar symptoms (MSA-C) and seven International Cooperative Ataxia Rating Scale (ICARS) score-matched patients with Machado-Joseph disease (MJD) were created using a diffusion-weighted PROPELLER sequence on a 3.0T system. The section of the middle pons was chosen for morphometric and diffusivity analyses.

Results: The above analyses showed that atrophy and increased diffusivity of the ventral portion of the pons indicated MSA-C, whereas atrophy and increased diffusivity of the pontine tegmentum indicated MJD. Furthermore, ICARS scores significantly correlated with both the severities of the pontine atrophy and the mean diffusivity values of the ventral pontocerebellar tracts.

Conclusions: This study demonstrated that 3DAC PROPELLER on a 3.0T system enables in vivo "tract by tract" quantitative analysis of pontine degeneration in SCD.
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http://dx.doi.org/10.1111/j.1552-6569.2008.00273.xDOI Listing
July 2009

In vivo visualization of senile-plaque-like pathology in Alzheimer's disease patients by MR microscopy on a 7T system.

J Neuroimaging 2008 Apr 22;18(2):125-9. Epub 2007 Oct 22.

Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata, Japan.

Background: Microscopic application of magnetic resonance imaging (MRI) has entered the era of clinical application. One of the most important targets is the visualization of pathological findings such as senile plaques (SP), in vivo, in patients with Alzheimer's disease (AD). Such an application provides not only the most accurate diagnostic tool for clinicians but also a solid basis for scientists for developing effective treatment and preventive strategies for AD.

Methods: Focused microscopic studies were performed on parietal association cortex at the level of the centrum semiovale identified on conventional axial slices using a system constructed based on General Electric Signa LX (Waukesha, WI) equipped with a 900-mm clear bore superconducting magnet operating at 7.0 T in 10 patients (67-83-year old, five males, five females) who fulfilled the NINCD and the SADRDA criteria for probable AD, 10 age-matched controls (71-85-year old, five males, five females), and 20 young adults (22-35-year old, 10 males, 10 females) using a susceptibility weighted imaging (SWI) algorithm.

Results: SWI microscopy consistently provided images with SP-like pathology extending within the entire parietal cortex in all cases of AD and 2 out of 10 age-matched volunteers.

Conclusions: Although the precise mechanisms leading to the higher susceptibility rendering SP-like pathology observable within the cortical mantle are not totally understood, the study unambiguously demonstrated that MR microscopy is capable of directly visualizing cortical pathology in AD patients in vivo.
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http://dx.doi.org/10.1111/j.1552-6569.2007.00179.xDOI Listing
April 2008

High-resolution imaging with high and ultra high-field magnetic resonance imaging systems.

Neuroreport 2008 Jan;19(1):7-13

Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Asahimachi, Niigata, Japan.

The development of noninvasive methods capable of affording ever higher resolution images is an ongoing major objective of scientific investigation for the benefit of both clinical medicine and neuroscience. Since its development in the early 1970s, magnetic resonance imaging (MRI) has remained a technology of choice for medical imaging development because of the wide range of potential clinical applications. Although conventional systems with field strengths of 1.0-1.5 T rapidly popularized MRI in general clinical practice in the 1980s, research investigations have focused on imaging yielding much higher anatomical resolution using high (3.0-4.0 T) and ultra high-field (7.0-9.0 T) systems. The substantial clinical experience with high and ultra high-field systems has made evident that there is a definite limit to which higher spatial resolution in and of itself will improve information for clinical judgment, rather, it is essential to develop the entire study as a whole, which would allow for the selection of an optimal combination of all the study elements, especially the appropriate contrast mechanism. This process is analogous to the development of suitable stains for a given pathologic process in histological techniques. In MRI, the natural physico-chemical MR contrast properties of tissues can be taken advantage of to achieve this goal, thereby obviating the need for administering contrast material to individuals.
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http://dx.doi.org/10.1097/WNR.0b013e3282f2e00bDOI Listing
January 2008

Preoperative depiction of cavernous sinus invasion by pituitary macroadenoma using three-dimensional anisotropy contrast periodically rotated overlapping parallel lines with enhanced reconstruction imaging on a 3-tesla system.

J Neurosurg 2008 Jan;108(1):37-41

Department of Neurosurgery, Graduate School of Medical and Dental Sciences, University of Niigata, Japan.

Objectives: Three-dimensional anisotropy contrast (3DAC) magnetic resonance (MR) imaging provides clear depiction of neuronal fibers. The aim of this study was to identify intracavernous cranial nerves in patients with pituitary macro-adenoma and in healthy volunteers by using 3DAC MR imaging on a 3-tesla system and to preoperatively predict cavernous sinus invasion by pituitary macroadenoma.

Methods: Thirty-three patients (cavernous sinuses in 66 sides) with pituitary macroadenomas and 25 healthy volunteers (50 sides) participated in this study. Coronal 3DAC MR images constructed from diffusion weighted images, acquired with periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) sequences, and T2-weighted reverse images were obtained at the same anatomical locations using a 3-tesla MR imaging system. Attempts were made to identify the cranial nerves.

Results: The oculomotor and ophthalmic/maxillary nerves were preoperatively identified in all sides (66 sides in patients and 50 sides in healthy volunteers) on 3DAC MR images. In the 33 patients, cavernous sinus invasion was revealed in 10 (12 [18.2%] of 66 sides) by intraoperative endoscopic observation. Coronal 3DAC MR images revealed that the oculomotor nerves were half surrounded with adenoma in all 12 of these sides, and the ophthalmic/maxillary nerves were half encapsulated with tumor (sensitivity/specificity: 100%/100% and 83%/100%, respectively).

Conclusions: Preoperative evaluation of pituitary macroadenomas using 3DAC PROPELLER MR imaging on a 3-tesla system is likely to be a powerful noninvasive method of detecting cavernous sinus invasion, which can potentially dominate the therapeutic strategy for these lesions.
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http://dx.doi.org/10.3171/JNS/2008/108/01/0037DOI Listing
January 2008

Serial assessments of delayed encephalopathy after carbon monoxide poisoning using magnetic resonance spectroscopy and diffusion tensor imaging on 3.0T system.

Eur Neurol 2008 4;59(1-2):55-61. Epub 2007 Oct 4.

Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata, Japan.

To elucidate the still unclear mechanism of delayed encephalopathy after carbon monoxide (CO) poisoning, we serially performed single-voxel proton magnetic resonance spectroscopy ((1)H-MRS) and diffusion tensor imaging (DTI) on a 3.0T system and intelligence tests in 2 patients, while they were undergoing hyperbaric oxygenation therapy. The chronological changes in (1)H-MRS- and DTI-derived parameters indicated the following: (1) White matter demyelination, aerobic metabolism inhibition, and cytotoxic edema persisted for at least 3 months even after starting the hyperbaric oxygenation therapy; (2) the axonal function and structural integrity of the white matter were initially severely impaired and then gradually and partially improved for 5 months, showing changes similar to those in the scores of the intelligence tests. The results demonstrated that brain damage after CO poisoning may persist longer than expected, and that the (1)H-MRS- and DTI-derived parameters are good indicators of the clinical progress of a patient. The combination of (1)H-MRS and DTI on a 3.0T system is useful for monitoring the changes in brain damage and the clinical symptoms of patients with delayed encephalopathy after CO poisoning.
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http://dx.doi.org/10.1159/000109262DOI Listing
February 2008

Cell-oriented analysis in vivo using diffusion tensor imaging for normal-appearing brain tissue in multiple sclerosis.

Neuroimage 2007 Oct 6;37(4):1278-85. Epub 2007 Aug 6.

Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata, Japan.

There have been several methods proposed so far using diffusion tensor imaging (DTI) for the assessment of normal-appearing brain tissue (NABT) injury in multiple sclerosis (MS). However, for these methods, the analyses of the NABT injury at the cellular level, wherein histological examinations can be used, still present challenging problems. We developed a method of segregating NABT into the following anatomical structures using lambda chart analysis associated with a two-dimensional Gaussian deconvolution of diffusion characteristic functions: 1) structures primarily composed of small neurons and glia; 2) structures primarily composed of large neurons; 3) structures primarily composed of short axons; and 4) structures primarily composed of long axons. Each segregated structure that had a distinctive diffusion characteristic was subjected to the statistical inference of DTI-derived parameters for 14 patients with conventional relapsing-remitting MS (RRMS) and 20 age-matched healthy volunteers. In all of the structures, the trace values were significantly higher and the fractional anisotropy values were significantly lower in the RRMS patients than in the healthy volunteers. Furthermore, the volume fractions of the structures primarily composed of short axons markedly decreased, whereas those of the structures primarily composed of small neurons and glia markedly increased. These results suggest that axonal loss and glial proliferation predominantly occurred in the subcortical white matter and adjacent deep cortical layer, namely, the juxtacortical region. This cell-oriented analysis of NABT injury using DTI confirmed in vivo the histological observation that the juxtacortical region is the most vulnerable site in MS.
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http://dx.doi.org/10.1016/j.neuroimage.2007.06.026DOI Listing
October 2007

Assessment of axonal degeneration along the human visual pathway using diffusion trace analysis.

Am J Ophthalmol 2006 Oct;142(4):591-6

Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata, Japan.

Purpose: The effectiveness of diffusion trace value analysis for non-invasive assessment of retinal ganglion cell (RGC) axonal degeneration at multiple anatomic levels along the human visual pathway under clinical setting was evaluated.

Design: Imaging study.

Methods: Ten patients with unilateral chronic optic neuropathy of varying cause and 16 age-matched normal subjects were studied. Trace, a tensor invariant that is considered to be a sensitive index for pathologic changes in axons, was analyzed at nine anatomic sites in each subject, namely, bilaterally at the level of the optic nerves, uncrossed chiasmal fibers, optic tracts and optic radiations, and crossed chiasmal fibers, using a 3.0 Tesla magnetic resonance imaging system.

Results: Trace values of the optic nerve and uncrossed chiasmal fibers ipsilateral to the affected eye, the crossed chiasmal fibers, and optic tracts bilaterally were significantly higher than those of the corresponding anatomic sites in normal subjects. The optic nerve and uncrossed chiasmal fibers ipsilateral to the unaffected side and optic radiations, bilaterally, had trace values which were not significantly different from the values of the corresponding anatomic levels in normal subjects. The increase in trace value in the optic nerve and uncrossed chiasmal fibers ipsilateral to the affected side was greater than those of the crossed chiasmal fibers and optic tracts.

Conclusions: Findings are highly consistent with a degenerative process of RGC axons and trace values are quantitatively well correlated to predicted pathology at the given anatomical sites. Trace value measurement at multiple sites along fiber pathways appears to be a powerful addition to clinical assessment of the functionality of components of the visual pathways during various stages of a pathologic process.
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http://dx.doi.org/10.1016/j.ajo.2006.05.042DOI Listing
October 2006

Brain developmental abnormalities in Prader-Willi syndrome detected by diffusion tensor imaging.

Pediatrics 2006 Aug;118(2):e442-8

Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Asahimachi 1-757, Niigata, 951-8585, Japan.

Objective: The purpose of this work was to detect brain developmental abnormalities in Prader-Willi syndrome by using diffusion tensor imaging based on a high-field MRI system.

Methods: Eight patients with Prader-Willi syndrome and 8 age- and gender-matched normal control subjects were examined using a high-field (3.0 T) MRI system. Trace value and fractional anisotropy were assessed simultaneously in multiple representative brain regions: the deep gray matter (putamen, caudate head, and dorsomedial thalamus) and the white matter structures (frontal and parietal white matter, posterior limb of internal capsule, and corpus callosum).

Results: In Prader-Willi syndrome patients, trace value was found to be significantly higher in the left frontal white matter and the left dorsomedial thalamus, whereas fractional anisotropy was significantly reduced in the posterior limb of the internal capsule bilaterally, the right frontal white matter, and the splenium of the corpus callosum. The observed diffusivity characteristics indicate developmental abnormalities in these areas, which are highly consistent with the clinical features of Prader-Willi syndrome.

Conclusions: The study provides the first objective evidence that Prader-Willi syndrome patients indeed have developmental abnormalities in specific areas of the brain, providing a new window toward understanding the pathophysiology of Prader-Willi syndrome.
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http://dx.doi.org/10.1542/peds.2006-0637DOI Listing
August 2006

Three-dimensional anisotropy contrast periodically rotated overlapping parallel lines with enhanced reconstruction (3DAC PROPELLER) on a 3.0T system: a new modality for routine clinical neuroimaging.

J Neuroimaging 2006 Jul;16(3):206-11

Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, 1 Asahimachi, Niigata 951-8585, Japan.

Background: Clinical magnetic resonance imaging (MRI) has recently entered the "high-field" era, and systems equipped with 3.0-4.0T superconductive magnets are becoming the gold standard for diagnostic imaging. While higher signal-to-noise ratio (S/N) is a definite advantage of higher field systems, higher susceptibility effect remains to be a significant trade-off. To take advantage of a higher field system in performing routine clinical images of higher anatomical resolution, we implemented a vector contrast image technique to 3.0T imaging, three-dimensional anisotropy contrast (3DAC), with a PROPELLER (Periodically Rotated Overlapping Parallel Lines with Enhanced Reconstruction) sequence, a method capable of effectively eliminating undesired artifacts on rapid diffusion imaging sequences.

Methods: One hundred subjects (20 normal volunteers and 80 volunteers with various central nervous system diseases) participated in the study. Anisotropic diffusion-weighted PROPELLER images were obtained on a General Electric (Waukesha, WI, USA) Signa 3.0T for each axis, with b-value of 1100 sec/mm(2). Subsequently, 3DAC images were constructed using in-house software written on MATLAB (MathWorks, Natick, MA, USA).

Results: The vector contrast allows for providing exquisite anatomical detail illustrated by clear identification of all major tracts through the entire brain. 3DAC images provide better anatomical resolution for brainstem glioma than higher-resolution T2 reversed images. Degenerative processes of disease-specific tracts were clearly identified as illustrated in cases of multiple system atrophy and Joseph-Machado disease.

Conclusion: Anatomical images of significantly higher resolution than the best current standard, T2 reversed images, were successfully obtained. As a technique readily applicable under routine clinical setting, 3DAC PROPELLER on a 3.0T system will be a powerful addition to diagnostic imaging.
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http://dx.doi.org/10.1111/j.1552-6569.2006.00049.xDOI Listing
July 2006

The passage to human MR microscopy: a progress report from Niigata on April 2005.

Magn Reson Med Sci 2005 ;4(2):83-7

Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Asahimachi, Niigata 951-8585, Japan.

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http://dx.doi.org/10.2463/mrms.4.83DOI Listing
February 2006

All-phase MR angiography using independent component analysis of dynamic contrast enhanced MRI time series: phi-MRA.

Magn Reson Med Sci 2003 Apr;2(1):23-7

Center for Integrated Brain Science, Brain Research Institute, University of Niigata, Japan.

Dynamic contrast enhanced magnetic resonance imaging (dynamic MRI) represents a MRI version of non-diffusible tracer methods, the main clinical use of which is the physiological construction of what is conventionally referred to as perfusion images. The raw data utilized for constructing MRI perfusion images are time series of pixel signal alterations associated with the passage of a gadolinium containing contrast agent. Such time series are highly compatible with independent component analysis (ICA), a novel statistical signal processing technique capable of effectively separating a single mixture of multiple signals into their original independent source signals (blind separation). Accordingly, we applied ICA to dynamic MRI time series. The technique was found to be powerful, allowing for hitherto unobtainable assessment of regional cerebral hemodynamics in vivo.
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http://dx.doi.org/10.2463/mrms.2.23DOI Listing
April 2003

Evaluation of efficacy of an automated single-voxel proton MRS algorithm on a 3T system.

Magn Reson Med Sci 2002 Jul;1(2):121-4

Department of Radiological Technology, School of Health Sciences, Faculty of Medicine, University of Niigata, 2-746 Asahimachi-dohri, Niigata-shi, Niigata 951-8518, Japan.

Purpose: To evaluate the efficacy of a fully automatic, single-voxel, proton MR spectroscopy algorithm on a 3.0T MR system.

Methods: The PROBE/SVQ algorithm (GE Medical Systems) was evaluated on a General Electric (GE) Signa LX-3T system. Ten normal volunteers (female, 21.1+/-2.0 years old) participated in the study. Nine representative regions of interest were examined, namely, right and left frontal white matter; right and left parietal white matter; right and left basal ganglia; right and left dentate nucleus; and pons.

Results: The mean coefficients of variation in all regions for the N-acetyl-aspartate to creatine ratio (NAA/Cr), choline to creatine ratio (Cho/Cr), and choline to N-acetyl-aspartate ratio (Cho/NAA) were 10.2+/-2.4%, 11.4+/-3.2% and 12.6+/-1.4%, respectively.

Conclusion: A fully automated spectroscopic examination under clinical setting utilizing the PROBE/SVQ algorithm appears to be a reliable method, extending the window of routine clinical assessment of brain metabolism.
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http://dx.doi.org/10.2463/mrms.1.121DOI Listing
July 2002

Isotropic component trace analysis.

J Neuroimaging 2005 Jul;15(3):233-9

Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Asahimachi, Niigata, Japan.

A new method for analyzing diffusion tensor imaging (DTI) of the brain, based on a recently introduced algorithm, lambda chart analysis (LCA), is presented. Pre-treatment of a given DTI data set with LCA, which effectively segregates isotropic and anisotropic components, allows for total removal of the anisotropic component from the DTI data set. The remaining pure isotropic component can therefore be subjected to further analysis similar to that applied in the trace histogram method. Deconvolution of the trace function yielded 3 Gaussian elements. Remapping of these 3 deconvoluted isotropic elements back onto the 2-dimensional image plane provided anatomical correlates of each element. The algorithm, referred to here as isotropic component trace analysis, can be used as a pictorial analytic tool, as well as a numerical analytical tool, for the noninvasive assessment of isotropic parenchymal components. The presented method provides quantitative indices of certain parenchymal parameters with better clarity than currently available methods. A ready-to-use program, EZ-LCA, for this powerful method is provided (available at http://coe.bri.niigata-u.ac.jp).
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http://dx.doi.org/10.1177/1051228405277404DOI Listing
July 2005

Diffusion tensor analysis of peritumoral edema using lambda chart analysis indicative of the heterogeneity of the microstructure within edema.

J Neurosurg 2005 Feb;102(2):336-41

Center for Integrated Human Brain Science, Department of Neurosurgery, Brain Research Institute, University of Niigata, Japan.

Object: Histopathological studies indicate that cerebral edema associated with tumors (peritumoral edema) does not represent a single pathophysiological or clinical entity. In this study the authors investigated peritumoral edema by performing lambda chart analysis (LCA), a noninvasive technique that can be used to make visible and analyze apparent water diffusivity in tissues in vivo, and assessed the utility of LCA in differentiating high-grade gliomas from nonglial tumors.

Methods: The water diffusivity characteristics of peritumoral edema associated with four tumor groups-12 high-grade gliomas, five low-grade gliomas, 11 metastatic tumors, and 15 meningiomas-were assessed in 43 patients by performing magnetic resonance imaging with the aid of a 3-tesla magnetic resonance imaging system. In all tumor groups, peritumoral edema exhibited greater trace values and reduced anisotropy compared with normal white matter. Edema associated with high-grade gliomas had significantly higher trace values than edema associated with the other three tumor groups, although the anisotropic angles of those groups were comparable.

Conclusions: Lambda chart analysis identified two distinct types of peritumoral edema: edema associated with high-grade gliomas and edema associated with low-grade gliomas or nonglial tumors. The apparent water diffusivity was significantly greater in high-grade gliomas, whereas the anisotropy in these lesions was comparable to that of edema in other tumors. These findings indicated that water movement in areas of edema, predominantly in the extracellular spaces, was less restricted in high-grade gliomas, a phenomenon that likely reflected the destruction of the extracellular matrix ultrastructure by malignant cell infiltration and consequently greater water diffusion. Although preliminary, this study indicates that LCA could be used as a clinical tool for differentiating high-grade gliomas and for evaluating the extent of cellular infiltration.
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http://dx.doi.org/10.3171/jns.2005.102.2.0336DOI Listing
February 2005
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