磁気共鳴デジタル差分血管造影法(MRDSA)の研究

学位の種別: 論文博士審査委員会委員 : (主査)東京大学准教授 國松 聡, 東京大学教授 宮川 清, 東京大学准教授 桐生 茂, 東京大学講師 山本 知孝, 東京大学講師 武笠 晃丈University of Tokyo(東京大学

Synthetic data generation method for hybrid image-tabular data using two generative adversarial networks

The generation of synthetic medical records using generative adversarial networks (GANs) has become increasingly important for addressing privacy concerns and promoting data sharing in the medical field. In this paper, we propose a novel method for generating synthetic hybrid medical records consisting of chest X-ray images (CXRs) and structured tabular data (including anthropometric data and laboratory tests) using an auto-encoding GAN ({\alpha}GAN) and a conditional tabular GAN (CTGAN). Our approach involves training a {\alpha}GAN model on a large public database (pDB) to reduce the dimensionality of CXRs. We then applied the trained encoder of the GAN model to the images in original database (oDB) to obtain the latent vectors. These latent vectors were combined with tabular data in oDB, and these joint data were used to train the CTGAN model. We successfully generated diverse synthetic records of hybrid CXR and tabular data, maintaining correspondence between them. We evaluated this synthetic database (sDB) through visual assessment, distribution of interrecord distances, and classification tasks. Our evaluation results showed that the sDB captured the features of the oDB while maintaining the correspondence between the images and tabular data. Although our approach relies on the availability of a large-scale pDB containing a substantial number of images with the same modality and imaging region as those in the oDB, this method has the potential for the public release of synthetic datasets without compromising the secondary use of data.Comment: 14 page

Radiation Myelopathy Caused by Palliative Radiotherapy and Intrathecal Methotrexate

Radiation myelopathy is a rare, late-stage adverse event that develops following irradiation at or above 50 Gy. Here, we report a case of irreversible paraplegia caused by palliative radiation (20 Gy in 5 fractions) to the spinal cord combined with intrathecal methotrexate (IT-MTX). A 69-year-old man presented with back pain, prompting a diagnosis of acute myeloid leukemia. At the first visit, he complained of muscle weakness and hypoesthesia in both legs; spinal magnetic resonance imaging (MRI) revealed an epidural mass compressing the spinal cord at the fifth to seventh level of the thoracic vertebrae. This was considered to be an extramedullary lesion of leukemia, and he received remission induction therapy including IT-MTX; palliative radiation (20 Gy in 5 fractions) of the epidural mass was initiated the following day. Then, during the course of consolidation therapy, a second IT-MTX was performed after 1 month and a third after 3 months. While the consolidation therapy was complete, yielding remission, he developed sudden paraplegia, as well as bladder and bowel dysfunction (BBD), 10 months later. Spinal MRI showed extensive intramedullary high signal intensity on T2-weighted image, including the irradiation field. It was thought myelopathy was due to irradiation of the spinal cord combined with IT-MTX. He immediately received steroid pulse therapy; however, the paraplegia and BBD did not improve. It is extremely rare for irreversible radiation myelopathy to occur with IT-MTX and palliative radiation to the spinal cord. We believe that even with low-dose palliative radiation, caution is required for combined use with IT-MTX

3 Tesla MRI detects accelerated hippocampal volume reduction in postmenopausal women

Purpose To clarify age-related structural changes specific to hippocampal volume by hierarchizing according to age, gender, and menopausal status. Many studies report the neuroprotective effects of estrogen and age-related brain volume changes; however, there are no studies regarding age-related change specific to hippocampal volume in terms of age, gender, and menopausal status. Materials and Methods T1-weighted MR images were obtained in 412 healthy adults divided into eight groups according to age and gender, to analyze brain volume change focusing on hippocampal volume. Results Voxel-based morphometry (VBM) revealed significantly smaller gray matter volume in the hippocampus bilaterally in females aged in their fifties (51 of 59 females were at menopause) compared with females in their forties (3 of 46 females were at menopause). No significant difference was found, however, between female groups in their fifties versus sixties, or sixties versus seventies; or between male groups in their forties versus fifties, fifties versus sixties, or sixties versus seventies. In addition, VBM revealed significant hippocampal volume reduction bilaterally in all postmenopausal women compared with all premenopausal women. Conclusion The results of the current study suggest that the menopause may be associated with hippocampal volume reduction. © 2010 Wiley-Liss, Inc.Thesis of Goto,Masami / 後藤 政実 博士学位論文(金沢大学 / 大学院医薬保健学総合研究科

Case Report: Tuberous sclerosis complex-associated hemihypertrophy successfully treated with mTOR inhibitor sirolimus

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by a mutation in either of the two tumor suppressor genes, TSC1 and TSC2. Due to dysregulated activity of the mammalian target of rapamycin (mTOR) pathway, hamartomas or benign tumors frequently occur in many organs and are often treated with mTOR inhibitors. Hemihypertrophy is a rare complication of TSC. Although not being a tumor, progressive overgrowth of the affected limb may cause cosmetic and functional problems, for which the efficacy of mTOR inhibitors has not been reported previously. We herein report a case of TSC-associated hemihypertrophy. In this case, genetic studies revealed TSC1 loss of heterozygosity as the cause of hemihypertrophy. Clinically, pharmacological treatment with an mTOR inhibitor sirolimus successfully ameliorated cosmetic and functional problems with no intolerable adverse effects