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Direct Visualization of Tracer Permeation into the Endolymph in Human Patients Using MR Imaging. 利用磁共振成像直接观察示踪剂渗入人体内淋巴的情况
Shinji Naganawa, Rintaro Ito, M. Kawamura, Toshiaki Taoka, Tadao Yoshida, M. Sone
PURPOSEThe endolymph of the inner ear, vital for balance and hearing, has long been considered impermeable to intravenously administered gadolinium-based contrast agents (GBCAs) due to the tight blood-endolymph barrier. However, anecdotal observations suggested potential GBCA entry in delayed heavily T2-weighted 3D-real inversion recovery (IR) MRI scans. This study systematically investigated GBCA distribution in the endolymph using this 3D-real IR sequence.METHODSForty-one patients suspected of endolymphatic hydrops (EHs) underwent pre-contrast, 4-h, and 24-h post-contrast 3D-real IR imaging. Signal intensity in cerebrospinal fluid (CSF), perilymph, and endolymph was measured and analyzed for temporal dynamics of GBCA uptake, correlations between compartments, and the influence of age and presence of EH.RESULTSEndolymph showed a delayed peak GBCA uptake at 24h, contrasting with peaks in perilymph and CSF at 4h. Weak to moderate positive correlations between endolymph and CSF contrast effect were observed at both 4 (r = 0.483) and 24h (r = 0.585), suggesting possible inter-compartmental interactions. Neither the presence of EH nor age significantly influenced endolymph enhancement. However, both perilymph and CSF contrast effects significantly correlated with age at both time points.CONCLUSIONThis study provides the first in vivo systematic confirmation of GBCA entering the endolymph following intravenous administration. Notably, endolymph uptake peaked at 24h, significantly later than perilymph and CSF. The lack of a link between endolymph contrast and both perilymph and age suggests distinct uptake mechanisms. These findings shed light on inner ear fluid dynamics and their potential implications in Ménière's disease and other inner ear disorders.
目的:内耳的内淋巴对平衡和听力至关重要,但由于血液-内淋巴屏障紧密,静脉注射钆基造影剂 (GBCA) 长期以来一直被认为是不可渗透的。然而,轶事观察表明,在延迟重T2加权三维真实反转恢复(IR)磁共振成像扫描中可能会有GBCA进入。方法41 名疑似内淋巴水肿(EHs)的患者分别接受了对比前、对比 4 小时和对比后 24 小时的三维真实红外成像。对脑脊液(CSF)、淋巴结和内淋巴的信号强度进行了测量,并分析了 GBCA 摄取的时间动态、各分区之间的相关性以及年龄和 EH 存在的影响。结果内淋巴在 24 小时后出现 GBCA 摄取延迟峰值,与淋巴结和脑脊液在 4 小时后出现的峰值形成鲜明对比。内淋巴和脑脊液对比效应在 4 小时(r = 0.483)和 24 小时(r = 0.585)时均呈弱至中等正相关,表明可能存在室间相互作用。EH 的存在和年龄对内淋巴增强均无明显影响。结论 本研究首次在体内系统证实了 GBCA 在静脉注射后进入内淋巴。值得注意的是,内淋巴吸收在 24 小时达到峰值,明显晚于淋巴周围和脑脊液。内淋巴对比度与淋巴液和年龄之间缺乏联系,这表明摄取机制各不相同。这些发现揭示了内耳液体动力学及其对梅尼埃病和其他内耳疾病的潜在影响。
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引用次数: 0
Diffusion Tensor Image Analysis ALong the Perivascular Space (DTI-ALPS): Revisiting the Meaning and Significance of the Method. 沿血管周围空间的弥散张量图像分析(DTI-ALPS):重新审视该方法的意义和重要性。
Toshiaki Taoka, Rintaro Ito, Rei Nakamichi, T. Nakane, H. Kawai, Shinji Naganawa
More than 5 years have passed since the Diffusion Tensor Image Analysis ALong the Perivascular Space (DTI-ALPS) method was proposed with the intention of evaluating the glymphatic system. This method is handy due to its noninvasiveness, provision of a simple index in a straightforward formula, and the possibility of retrospective analysis. Therefore, the ALPS method was adopted to evaluate the glymphatic system for many disorders in many studies. The purpose of this review is to look back and discuss the ALPS method at this moment.The ALPS-index was found to be an indicator of a number of conditions related to the glymphatic system. Thus, although this was expected in the original report, the results of the ALPS method are often interpreted as uniquely corresponding to the function of the glymphatic system. However, a number of subsequent studies have pointed out the problems on the data interpretation. As they rightly point out, a higher ALPS-index indicates predominant Brownian motion of water molecules in the radial direction at the lateral ventricular body level, no more and no less. Fortunately, the term "ALPS-index" has become common and is now known as a common term by many researchers. Therefore, the ALPS-index should simply be expressed as high or low, and whether it reflects a glymphatic system is better to be discussed carefully. In other words, when a decreased ALPS-index is observed, it should be expressed as "decreased ALPS-index" and not directly as "glymphatic dysfunction". Recently, various methods have been proposed to evaluate the glymphatic system. It has become clear that these methods also do not seem to reflect the entirety of the extremely complex glymphatic system. This means that it would be desirable to use various methods in combination to evaluate the glymphatic system in a comprehensive manner.
以评估肾脏系统为目的的沿血管周围空间弥散张量图像分析(DTI-ALPS)方法提出至今已有 5 年多的时间。这种方法因其无创、以简单的公式提供简单的指标以及可进行回顾性分析而非常方便。因此,许多研究都采用 ALPS 方法来评估许多疾病的甘回流系统。本综述旨在回顾和讨论 ALPS 方法。因此,尽管这在最初的报告中是意料之中的,但 ALPS 方法的结果往往被解释为与甘泌乳系统的功能唯一对应。然而,随后的一些研究指出了数据解释上的问题。正如他们正确指出的那样,较高的 ALPS 指数表明水分子在侧脑室体水平的径向布朗运动占主导地位,仅此而已。幸运的是,"ALPS 指数 "这一术语已经变得很普遍,现在已被许多研究人员视为常用术语。因此,ALPS-指数应该简单地用高或低来表示,至于它是否反映了甘油系统,最好还是仔细讨论。换句话说,当观察到 ALPS-index 下降时,应表述为 "ALPS-index 下降",而不是直接表述为 "glymphatic dysfunction"。最近,人们提出了各种方法来评估甘液系统。很明显,这些方法似乎也不能反映极其复杂的甘运动系统的全部情况。这意味着,最好能将各种方法结合起来使用,以全面评估甘液系统。
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引用次数: 0
Comparison of Echo-Planar Imaging and Compressed Sensing in the Estimation of Flow Metrics from Aortic 4D Flow MR Imaging: A Healthy Volunteer Study. 主动脉四维血流 MR 成像中回声平面成像与压缩传感在估计血流指标方面的比较:健康志愿者研究
Satoru Aono, Satonori Tsuneta, Noriko Nishioka, Takuya Aoike, Hiroyuki Hirayama, Kinya Ishizaka, Jihun Kwon, Masami Yoneyama, Noriyuki Fujima, Kohsuke Kudo

Purpose: Prolonged scanning of time-resolved 3D phase-contrast MRI (4D flow MRI) limits its routine use in clinical practice. An echo-planar imaging (EPI)-based sequence and compressed sensing can reduce the scan duration. We aimed to determine the impact of EPI for 4D flow MRI on the scan duration, image quality, and quantitative flow metrics.

Methods: This was a prospective study of 15 healthy volunteers (all male, mean age 33 ± 5 years). Conventional sensitivity encoding (SENSE), EPI with SENSE (EPI), and compressed SENSE (CS) (reduction factors: 6 and 12, respectively) were scanned.Scan duration, qualitative indexes of image quality, and quantitative flow parameters of net flow volume, maximum flow velocity, wall shear stress (WSS), and energy loss (EL) in the ascending aorta were assessed. Two-dimensional phase-contrast cine MRI (2D-PC) was considered the gold standard of net flow volume and maximum flow velocity.

Results: Compared to SENSE, EPI and CS12 shortened scan durations by 71% and 73% (EPI, 4 min 39 sec; CS6, 7 min 29 sec; CS12, 4 min 14 sec; and SENSE, 15 min 51 sec). Visual image quality was significantly better for EPI than for SENSE and CS (P < 0.001). The net flow volumes obtained with SENSE, EPI, and CS12 and those obtained with 2D-PC were correlated well (r = 0.950, 0.871, and 0.850, respectively). However, the maximum velocity obtained with EPI was significantly underestimated (P < 0.010). The average WSS was significantly higher with EPI than with SENSE, CS6, and CS12 (P < 0.001, P = 0.040, and P = 0.012, respectively). The EL was significantly lower with EPI than with CS6 and CS12 (P = 0.002 and P = 0.007, respectively).

Conclusion: EPI reduced the scan duration, improved visual image quality, and was associated with more accurate net flow volume than CS. However, the flow velocity, WSS, and EL values obtained with EPI and other sequences may not be directly comparable.

目的:时间分辨三维相位对比磁共振成像(4D 流量磁共振成像)的长时间扫描限制了其在临床实践中的常规应用。基于回声平面成像(EPI)的序列和压缩传感可缩短扫描时间。我们旨在确定 4D 血流 MRI 的 EPI 对扫描时间、图像质量和定量血流指标的影响:这是一项对 15 名健康志愿者(均为男性,平均年龄为 33 ± 5 岁)进行的前瞻性研究。对扫描时间、图像质量的定性指标以及升主动脉的净血流量、最大血流速度、壁剪应力和能量损失等定量血流参数进行了评估。二维相位对比 cine MRI(2D-PC)被认为是净血流量和最大流速的金标准:与 SENSE 相比,EPI 和 CS12 的扫描时间分别缩短了 71% 和 73%(EPI,4 分 39 秒;CS6,7 分 29 秒;CS12,4 分 14 秒;SENSE,15 分 51 秒)。EPI的视觉图像质量明显优于SENSE和CS(P 结论:EPI缩短了扫描时间,改善了视觉图像质量:与 CS 相比,EPI 缩短了扫描时间,提高了视觉图像质量,并能获得更准确的净血流量。然而,EPI 和其他序列获得的血流速度、WSS 和 EL 值可能无法直接比较。
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引用次数: 0
Characteristics of Suspicious Breast Lesions Visible Only on MR Imaging: Is It Possible to Classify into Immediate Biopsy and Careful Observation Groups? 仅在磁共振成像中可见的可疑乳腺病变的特征:是否可以分为立即活检组和仔细观察组?
Ryozo Kai, Mitsuhiro Tozaki, Yuya Koike, Aya Nagata, Kanae Taruno, Yoshimitsu Ohgiya

Purpose: To investigate the characteristics of suspicious MRI-only visible lesions and to explore the validity of subcategorizing these lesions into the following two groups: lesions that would require immediate biopsy (4Bi) and lesions for which careful clinical follow-up could be recommended (4Fo).

Methods: A retrospective review of 108 MRI-only visible lesions in 106 patients who were diagnosed as Breast Imaging Reporting and Data System (BI-RADS) category 4 between June 2018 and June 2022 at our institution was performed by two radiologists. The breast MR images were evaluated according to BI-RADS and additional MRI descriptors (linear ductal, branching, and apparent diffusion coefficient values). The lesions were categorized by previously reported classification systems, and the positive predictive values (PPVs) for the different categories were determined and compared. Subsequently, a new classification system was developed in this study.

Results: The total malignancy rate was 31% (34/108). No significant differences between benign and malignant lesions were identified for focus and mass lesions. For non-mass lesions, linear ductal and heterogeneous internal enhancement suggested a benign lesion (P = 0.0013 and P = 0.023, respectively), and branching internal enhancement suggested malignancy (P = 0.0066). Segmental distribution suggested malignancy (P = 0.0097). However, the PPV of segmental distribution with heterogeneous enhancement was significantly lower than that of category 4 segmental lesions with other enhancement patterns (11% vs. 59%; P = 0.0198).As a new classification, the distribution of focal, linear, and segmental was given a score of 0, 1, or 2, and the internal enhancement of heterogeneous, linear-ductal, clumped, branching, and clustered-ring enhancement was given a score of 0, 1, 2, 3, and 4, respectively. When categorized using a scoring system, a statistically significant difference in PPV was observed between 4Fo (n = 27) and 4Bi (n = 33) (7% vs. 61%, P = 0.000029).

Conclusion: The new classification system was found to be highly capable of subcategorizing BI-RADS category 4 MRI-only visible non-mass lesions into 4Fo and 4Bi.

目的:调查核磁共振纯可见可疑病灶的特征,并探讨将这些病灶细分为以下两类的有效性:需要立即活检的病灶(4Bi)和建议进行仔细临床随访的病灶(4Fo):两位放射科医生对我院2018年6月至2022年6月期间诊断为乳腺影像报告和数据系统(BI-RADS)第4类的106例患者的108个MRI可见病灶进行了回顾性复查。乳腺 MR 图像根据 BI-RADS 和其他 MRI 描述因子(线性导管、分支和表观扩散系数值)进行评估。病变按照之前报道的分类系统进行分类,并确定和比较了不同类别的阳性预测值(PPV)。随后,本研究制定了一套新的分类系统:结果:总恶性率为 31%(34/108)。病灶和肿块病变在良性和恶性病变之间无明显差异。对于非肿块病变,线性导管和异型内部强化提示良性病变(P = 0.0013 和 P = 0.023),而分支内部强化提示恶性病变(P = 0.0066)。分段分布提示恶性(P = 0.0097)。作为一种新的分类方法,局灶性、线状和节段性的分布被赋予 0、1 或 2 分,而异型、线状-传导性、团块状、分支状和团环状增强的内部增强分别被赋予 0、1、2、3 和 4 分。当使用评分系统进行分类时,4Fo(n = 27)和 4Bi(n = 33)之间的 PPV 有显著统计学差异(7% vs. 61%,P = 0.000029):结论:研究发现,新的分类系统能够将 BI-RADS 第 4 类仅 MRI 可见非肿块病变细分为 4Fo 和 4Bi。
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引用次数: 0
Imaging of 17O-labeled Water Using Fast T2 Mapping with T2-preparation: A Phantom Study. 利用快速 T2 映射和 T2 准备对 17O 标记的水进行成像:模型研究
Hiroyuki Kameda, Yumi Nakada, Yuta Urushibata, Hiroyuki Sugimori, Takaaki Fujii, Naoya Kinota, Daisuke Kato, Minghui Tang, Keita Sakamoto, Kohsuke Kudo

17O-labeled water is a T2-shortening contrast agent used in proton MRI and is a promising method for visualizing cerebrospinal fluid (CSF) dynamics because it provides long-term tracking of water molecules. However, various external factors reduce the accuracy of 17O-concentration measurements using conventional signal-intensity-based methods. In addition, T2 mapping, which is expected to provide a stable assessment, is generally limited to temporal-spatial resolution. We developed the T2-prepared based on T2 mapping used in cardiac imaging to adapt to long T2 values and tested whether it could accurately measure 17O-concentration in the CSF using a phantom. The results showed that 17O-concentration in a fluid mimicking CSF could be evaluated with an accuracy comparable to conventional T2-mapping (Carr-Purcell-Meiboom-Gill multi-echo spin-echo method). This method allows 17O-imaging with a high temporal resolution and stability in proton MRI. This imaging technique may be promising for visualizing CSF dynamics using 17O-labeled water.

17O 标记的水是质子磁共振成像中使用的一种 T2 缩短造影剂,由于它能对水分子进行长期追踪,因此是一种很有前景的脑脊液(CSF)动态可视化方法。然而,各种外部因素降低了使用基于信号强度的传统方法测量 17O 浓度的准确性。此外,T2 映射有望提供稳定的评估,但一般仅限于时间空间分辨率。我们在心脏成像中使用的 T2 映射的基础上开发了 T2 准备,以适应长 T2 值,并使用模型测试了它是否能准确测量 CSF 中的 17O 浓度。结果表明,模拟 CSF 的液体中 17O 浓度的评估准确度可与传统 T2 映射(Carr-Purcell-Meiboom-Gill 多回波自旋回波法)媲美。这种方法可在质子磁共振成像中实现高时间分辨率和高稳定性的 17O 成像。这种成像技术在使用 17O 标记的水观察 CSF 动态方面大有可为。
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引用次数: 0
Automated Detection of Cerebral Microbleeds on Two-dimensional Gradient-recalled Echo T2* Weighted Images Using a Morphology Filter Bank and Convolutional Neural Network. 利用形态学滤波器库和卷积神经网络在二维梯度回波 T2* 加权图像上自动检测脑微出血。
Noriko Nishioka, Yukie Shimizu, Toru Shirai, Hisaaki Ochi, Yoshitaka Bito, Kiichi Watanabe, Hiroyuki Kameda, Taisuke Harada, Kohsuke Kudo

Purpose: We present a novel algorithm for the automated detection of cerebral microbleeds (CMBs) on 2D gradient-recalled echo T2* weighted images (T2*WIs). This approach combines a morphology filter bank with a convolutional neural network (CNN) to improve the efficiency of CMB detection. A technical evaluation was performed to ascertain the algorithm's accuracy.

Methods: In this retrospective study, 60 patients with CMBs on T2*WIs were included. The gold standard was set by three neuroradiologists based on the Microbleed Anatomic Rating Scale guidelines. Images with CMBs were extracted from the training dataset comprising 30 cases using a morphology filter bank, and false positives (FPs) were removed based on the threshold of size and signal intensity. The extracted images were used to train the CNN (Vgg16). To determine the effectiveness of the morphology filter bank, the outcomes of the following two methods for detecting CMBs from the 30-case test dataset were compared: (a) employing the morphology filter bank and additional FP removal and (b) comprehensive detection without filters. The trained CNN processed both sets of initial CMB candidates, and the final CMB candidates were compared with the gold standard. The sensitivity and FPs per patient of both methods were compared.

Results: After CNN processing, the morphology-filter-bank-based method had a 95.0% sensitivity with 4.37 FPs per patient. In contrast, the comprehensive method had a 97.5% sensitivity with 25.87 FPs per patient.

Conclusion: Through effective CMB candidate refinement with a morphology filter bank and FP removal with a CNN, we achieved a high CMB detection rate and low FP count. Combining a CNN and morphology filter bank may facilitate the accurate automated detection of CMBs on T2*WIs.

目的:我们提出了一种在二维梯度回波 T2* 加权图像(T2*WI)上自动检测脑微出血(CMB)的新型算法。该方法将形态学滤波器组与卷积神经网络(CNN)相结合,提高了 CMB 检测的效率。为确定算法的准确性,进行了技术评估:在这项回顾性研究中,共纳入了 60 名 T2*WI 上有 CMB 的患者。金标准由三位神经放射学专家根据微出血解剖量表指南设定。使用形态学滤波器库从由 30 个病例组成的训练数据集中提取出带有 CMB 的图像,并根据大小和信号强度阈值去除假阳性(FP)。提取的图像用于训练 CNN(Vgg16)。为了确定形态学滤波器库的有效性,我们比较了以下两种从 30 例测试数据集中检测 CMB 的方法的结果:(a) 使用形态学滤波器库和额外的 FP 去除;(b) 不使用滤波器的综合检测。训练有素的 CNN 对这两组初始候选 CMB 进行处理,并将最终候选 CMB 与金标准进行比较。比较了两种方法的灵敏度和每个患者的 FP:结果:经过 CNN 处理后,基于形态学过滤器库的方法灵敏度为 95.0%,每位患者的 FP 为 4.37。相比之下,综合方法的灵敏度为 97.5%,每名患者的 FP 为 25.87 个:通过使用形态学滤波器组对候选 CMB 进行有效细化,并使用 CNN 去除 FP,我们实现了较高的 CMB 检测率和较低的 FP 数量。将 CNN 与形态学滤波器库相结合,有助于在 T2*WI 上准确自动检测 CMB。
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引用次数: 0
Utility of Diffusion-weighted MR Imaging for Evaluating the Depth of Invasion in Oral Tongue Squamous Cell Carcinoma. 弥散加权磁共振成像在评估口腔舌鳞状细胞癌浸润深度方面的实用性
Hiroki Tanaka, Sho Koyasu, Masahiro Kikuchi, Mami Iima, Koichi Omori, Yuji Nakamoto

Purpose: The 8th edition of the American Joint Committee on Cancer staging system included the depth of invasion (DOI) for the T classification of oral cancer. However, no standardized method has been established to clinically measure the DOI. This study aimed to investigate the accuracy of MRI-based DOI for oral tongue squamous cell carcinoma (OTSCC) in each MRI sequence.

Methods: We enrolled 49 patients with histologically proven OTSCC, treated surgically between April 2017 and February 2021. We divided the DOI into three groups using 5 and 10 mm, the thresholds for determining the T stage, and retrospectively evaluated the agreement between MRI-based DOI and pathological DOI (pDOI) for each MRI sequence, axial T1-weighted imaging (T1WI), T2-weighted imaging with fat suppression (FS-T2WI), contrast-enhanced T1WI with fat suppression (CE-T1WI), diffusion-weighted imaging (DWI), and apparent diffusion coefficient (ADC) maps. We also divided the DOI into two groups using 3 mm, the threshold for considering elective neck dissection, and evaluated the overestimation rate of MRI-based DOI in lesions with pDOI ≤ 3 mm.

Results: With 5-mm and 10-mm divisions, the accuracy of the DOI assessment was highest on DWI (0.82, weighted kappa = 0.85). With a 3-mm division, the accuracy was also highest on DWI (0.87, kappa = 0.73). The overestimation rate of the MRI-based DOI in lesions with pDOI ≤ 3 mm was lowest on DWI (27.8%).

Conclusion: DOI on DWI exhibits a comparatively higher rate of concordance with pDOI. DWI may be more useful than other MRI sequences in evaluating the DOI of OTSCC.

目的:美国癌症联合委员会第八版分期系统将浸润深度(DOI)纳入口腔癌 T 级分类。然而,目前尚未建立临床测量 DOI 的标准化方法。本研究旨在探讨基于 MRI 的 DOI 在每个 MRI 序列中对口腔舌鳞状细胞癌(OTSCC)的准确性:我们招募了 49 名经组织学证实的 OTSCC 患者,他们在 2017 年 4 月至 2021 年 2 月期间接受了手术治疗。我们以 5 毫米和 10 毫米作为确定 T 分期的阈值,将 DOI 分成三组,并回顾性评估了每个 MRI 序列、轴向 T1 加权成像(T1WI)、带脂肪抑制的 T2 加权成像(FS-T2WI)、带脂肪抑制的对比增强 T1WI(CE-T1WI)、弥散加权成像(DWI)和表观弥散系数(ADC)图中基于 MRI 的 DOI 与病理 DOI(pDOI)之间的一致性。我们还使用 3 毫米(考虑选择性颈部解剖的阈值)将 DOI 分成两组,并评估了基于 MRI 的 DOI 在 pDOI ≤ 3 毫米的病变中的高估率:以 5 毫米和 10 毫米为分界,DWI 评估的准确率最高(0.82,加权卡帕 = 0.85)。3 毫米分割时,DWI 的准确率也最高(0.87,kappa = 0.73)。对于 pDOI ≤ 3 毫米的病变,基于 MRI 的 DOI 高估率在 DWI 上最低(27.8%):结论:DWI 的 DOI 与 pDOI 的吻合率相对较高。DWI在评估OTSCC的DOI方面可能比其他磁共振序列更有用。
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引用次数: 0
4D Flow MRI Reflects Physiological Hemodynamics for the Diagnosis and Management of Portosystemic Shunts. 四维血流磁共振成像反映门静脉分流诊断和管理的生理血流动力学。
Atsushi Higaki, Akira Yamamoto, Toshimasa Okada, Tomio Ueno, Yasuyuki Tomiyama, Kosuke Ito, Tsutomu Tamada

A woman in her sixties with portosystemic shunt and hepatic encephalopathy underwent open mesenteric vein ligation, resulting in improved portal flow and blood ammonia. In this case, 4D flow MRI was a valuable diagnostic and follow-up tool, visualizing and quantifying physiological portal hemodynamics with features distinct from those of contrast-enhanced CT and digital subtraction angiography. Our case study highlights the value of 4D flow MRI for managing portosystemic shunts.

一位六十多岁的妇女患有门静脉分流和肝性脑病,她接受了肠系膜静脉开放结扎术,结果门静脉血流和血氨得到改善。在这个病例中,四维血流磁共振成像是一种有价值的诊断和随访工具,它可以观察和量化生理性门静脉血流动力学,其特征与对比增强 CT 和数字减影血管造影不同。我们的病例研究凸显了四维血流 MRI 在管理门静脉分流方面的价值。
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引用次数: 0
Histological Properties of a Chemically Fixed Human Embryo Visualized with Quantitative Susceptibility Mapping. 利用定量易感性图谱观察化学固定人类胚胎的组织学特性
Toru Shirai, Yasuhiko Terada, Katsumi Kose, Shigehito Yamada

A chemically fixed Carnegie stage 23 (approximately 56 days of gestation) human embryo specimen was imaged using 3D spin-echo and gradient-echo sequences in a static magnetic field strength of 4.74T, and a quantitative susceptibility map was calculated using the 3D gradient-echo image. The acquired 3D microscopic images (90 μm cube voxel size) clarified the relationship between R2 (transverse relaxation rate), R2* (apparent transverse relaxation rate), and magnetic susceptibility in the heart, liver, kidney, and spinal cord. The results suggested that the R2* and magnetic susceptibility in each tissue were probably due to paramagnetic iron ions originating from erythrocytes. The large R2* (~130 s-1) and magnetic susceptibility (~0.122 ppm) in the liver were attributed to its hemopoietic function. A large magnetic susceptibility (~0.116 ppm) was also observed in the spinal cord, but we conclude that more detailed future studies are needed.

在 4.74T 的静态磁场强度下,使用三维自旋回波和梯度回波序列对化学固定的卡内基 23 期(约妊娠 56 天)人类胚胎标本进行了成像,并使用三维梯度回波图像计算了定量磁感应强度图。获得的三维显微图像(90 微米立方体体素大小)阐明了心脏、肝脏、肾脏和脊髓的 R2(横向弛豫率)、R2*(表观横向弛豫率)和磁感应强度之间的关系。结果表明,各组织中的 R2* 和磁感应强度可能是由来自红细胞的顺磁性铁离子造成的。肝脏中较大的 R2*(约 130 s-1)和磁感应强度(约 0.122 ppm)归因于其造血功能。在脊髓中也观察到了较大的磁感应强度(约 0.116 ppm),但我们认为今后还需要进行更详细的研究。
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引用次数: 0
Comparison of 3D Magnetization-transfer- and Spectral-presaturation-with-inversion-recovery-based Neuromelanin Imaging. 基于神经黑素成像的三维磁化转移和光谱预饱和与反转复原成像的比较。
Midori Kusama, Yukio Kimura, Masami Yoneyama, Takashi Namiki, Takeshi Tamaru, Kenji Miyagi, Noriko Sato

Purpose: Neuromelanin is visualized by optimizing the conditions of longitudinal relaxation (T1)-weighted imaging (T1WI). Although it was originally developed in 2D imaging, 3D imaging has been also reported, and T1WI sequences with magnetization transfer (MT) pulses are now widely used in 3D gradient echo (GRE) sequences. In this study, we assert that the use of spectral presaturation with inversion recovery (SPIR) may also be useful as an alternative to MT pulses, and we optimize SPIR and compare it with MT.

Methods: Neuromelanin images with MT pulse and SPIR (flip angles [FAs] = 19º, 22º, and 25º) were acquired from 30 healthy volunteers. To achieve the same acquisition time of 5 min, the slab thickness of the MT images was less than 1/3 of those of the SPIR images; the acquisition areas for MT and SPIR were the brainstem and the whole brain, respectively. Visual and quantitative evaluation was performed and compared on the four sequences acquired for the substantia nigra pars compacta (SNc) and the locus coeruleus (LC). For visual assessment, we used the mean score from a 3-point scale by two evaluators. For quantitative evaluation, the contrast ratios of SNc and LC were calculated in comparison with the background tissue signal.

Results: In visual assessments, the mean scores of the SPIR FA19º and FA22º images were better than others in the SNc. Regarding LC, the SPIR FA22º image yielded the best mean score. In quantitative evaluations, the MT image was significantly lower than the other three images in SNc. Regarding LC, there were no significant differences among the four acquired images (MT and SPIR FA19º, FA22º, and FA25º).

Conclusions: Detection of neuromelanin in SNc and LC was improved by the use of SPIR compared to MT pulse in 3D neuromelanin imaging.

目的:通过优化纵向弛豫(T1)加权成像(T1WI)的条件来观察神经黑素。虽然它最初是在二维成像中开发的,但三维成像也有报道,目前带有磁化转移(MT)脉冲的 T1WI 序列已广泛应用于三维梯度回波(GRE)序列中。在本研究中,我们认为使用带反转恢复(SPIR)的频谱预饱和也可替代 MT 脉冲,我们对 SPIR 进行了优化,并将其与 MT 进行了比较:方法:我们从 30 名健康志愿者身上采集了 MT 脉冲和 SPIR(翻转角 [FA] = 19º、22º 和 25º)神经黑素图像。为了实现相同的 5 分钟采集时间,MT 图像的板厚度小于 SPIR 图像的 1/3;MT 和 SPIR 的采集区域分别为脑干和全脑。我们对采集到的四个序列进行了视觉和定量评估,并对黑质(SNc)和小叶区(LC)进行了比较。在视觉评估方面,我们采用了由两名评估员进行 3 点评分的平均值。在定量评估中,我们计算了SNc和LC与背景组织信号的对比度:在视觉评估中,SPIR FA19º和FA22º图像的平均得分在SNc方面优于其他图像。在 LC 方面,SPIR FA22º 图像的平均得分最高。在定量评估中,MT 图像明显低于 SNc 中的其他三种图像。在低密度脂蛋白胆固醇方面,所获得的四张图像(MT 和 SPIR FA19º、FA22º 和 FA25º)之间没有明显差异:结论:在三维神经黑素成像中,使用 SPIR 比 MT 脉冲能更好地检测 SNc 和 LC 中的神经黑素。
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Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine
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