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Echo planar

Ping Lu, Guohong Tian, Xilan Liu, Feng Wang, Zhongshuai Zhang, Yan Sha
PURPOSE: In clinical practice, acute optic neuritis (ON) associated with the development of neuromyelitis optica (NMO) after the first attack is often indistinguishable from that associated with multiple sclerosis (MS). We aimed to determine the optimal combination of features derived from conventional magnetic resonance imaging (MRI) and diffusion-weighted imaging using readout-segmented echo-planar imaging (RESOLVE-DWI) for the differentiation of these conditions. MATERIALS AND METHODS: Orbital conventional MRI and RESOLVE-DWI were performed using a 3...
May 21, 2018: Journal of Computer Assisted Tomography
Yasuo Mori, Jun Miyata, Masanori Isobe, Shuraku Son, Yujiro Yoshihara, Toshihiko Aso, Takanori Kouchiyama, Toshiya Murai, Hidehiko Takahashi
AIM: Echo-planar imaging is a common technique used in functional magnetic resonance imaging (fMRI), however it suffers from image distortion and signal loss because of large susceptibility effects that are related to the phase-encoding direction of the scan. Despite this relationship, the majority of neuroimaging studies have not considered the influence of phase-encoding direction. Here, we aimed to clarify how phase-encoding direction can affect the outcome of an fMRI connectivity study of schizophrenia...
May 17, 2018: Psychiatry and Clinical Neurosciences
Nicholas J Freeman, Henrik Odéen, Dennis L Parker
PURPOSE: Evaluate a numerical inverse Green's function method of deriving specific absorption rates (SARs) from high intensity focused ultrasound (HIFU) sonications given tissue parameters (thermal conductivity, specific heat capacity, and mass density) and 3-D magnetic resonance imaging (MRI) temperature measurements. METHODS: SAR estimates were evaluated using simulations and MR temperature measurements from HIFU sonications. For simulations, a "true" SAR was calculated using the hybrid angular spectrum method for ultrasound simulations...
May 17, 2018: Medical Physics
Zijing Dong, Erpeng Dai, Fuyixue Wang, Zhe Zhang, Xiaodong Ma, Chun Yuan, Hua Guo
PURPOSE: Multishot interleaved echo-planar imaging (iEPI) can achieve higher image resolution than single-shot EPI for diffusion-tensor imaging (DTI), but its application is limited by the prolonged acquisition time. To reduce the acquisition time, a novel model-based reconstruction for simultaneous multislice (SMS) and parallel imaging (PI) accelerated iEPI DTI is proposed. MATERIALS AND METHODS: DTI datasets acquired by iEPI with SMS and PI acceleration can be regarded as 3D k-space data, which is undersampled along both the slice and phase encoding directions...
May 14, 2018: Medical Physics
Adarsh Ghosh, Tulika Singh, Veenu Singla, Rashmi Bagga, Radhika Srinivasan, Niranjan Khandelwal
OBJECTIVE: Susceptibility artefacts from bones and bowel, geometric distortion make diffusion imaging of the pelvis difficult. We discuss the difficulties of single-shot-echoplanar[ss-ep ]DWI and evaluate a new diffusion-weighted imaging technique - readout segmented echo planar[ rs-ep]DWI in endometrial carcinoma and discuss the imaging physics. METHODS: IRB approval was obtained and five consecutive patients underwent both rs-ep and ss-ep-DWI of the female pelvis and two radiologists compared the images...
May 11, 2018: British Journal of Radiology
Kenichiro Hirata, Takeshi Nakaura, Tomoyuki Okuaki, Masafumi Kidoh, Seitaro Oda, Daisuke Utsunomiya, Tomohiro Namimoto, Mika Kitajima, Hideki Nakayama, Yasuyuki Yamashita
The purpose of this study was to compare the image quality of turbo spin echo (TSE) diffusion-weighted imaging (DWI) and echo-planar imaging (EPI) of the oral cavity region.This retrospective study included 26 patients who had undergone both TSE- and EPI-DWI. Misregistration of DWI with T2-TSE images was assessed in the oral cavity. We also compared geometric distortion, the signal-to-noise ratio (SNR), contrast, and the apparent diffusion coefficient (ADC) for the tongue parotid gland, and spinal cord. On a 5-point scale, 2 radiologists scored the TSE- and EPI-DWI of each patient for ghost artifacts, image contrast, and overall image quality...
May 2018: Medicine (Baltimore)
Kenneth Wengler, Takeshi Fukuda, Dharmesh Tank, Mingqian Huang, Elaine S Gould, Mark E Schweitzer, Xiang He
BACKGROUND: Limited microcirculation has been implicated in Achilles tendinopathy and may affect healing and disease progression. Existing invasive and noninvasive approaches to evaluate tendon microcirculation lack sensitivity and spatial coverage. PURPOSE: To develop a novel Achilles tendon intravoxel incoherent motion (IVIM) MRI protocol to overcome the limitations from low tendon T2 /T2 * value and low intratendinous blood volume and blood velocity to evaluate tendon microcirculation...
May 9, 2018: Journal of Magnetic Resonance Imaging: JMRI
Lin Yin Yao, Yi Chen Guo, Xiao Jun Zhan, Zhi Fu Sun, Ying Li, Yong Xiang Wei
OBJECTIVES: To investigate the cerebral white matter micro-structure in patients with idiopathic olfactory loss using diffusion tensor imaging (DTI). METHODS: Sixteen patients with idiopathic olfactory loss and sixteen normal subjects matched by age and sex were recruited in this study. Sniffin'Stick olfactory test was performed to evaluate the olfactory function of all subjects. We acquired diffusion tensor images with an echo planar imaging (EPI) sequence from all subject on a 3T scanner...
March 2018: Journal of Clinical Otorhinolaryngology, Head, and Neck Surgery
Heidi Kuang, Angela Duong, Hyunjin Jeong, Kassandra Zachos, Ana C Andreazza
Bipolar disorder (BD) is a debilitating mood disorder with no specific biological marker. No novel treatment has been developed specifically for BD in the last several decades. Although the pathophysiology of BD remains unclear, there is strong evidence in the literature supporting the role of mitochondrial dysfunction in BD. In this systematic review, we identified and investigated twelve studies that measure lactate, which is a direct marker for mitochondrial dysfunction, in BD patients and healthy controls...
May 4, 2018: Psychiatry and Clinical Neurosciences
Maiko Kozumi, Hideki Ota, Takaya Yamamoto, Rei Umezawa, Haruo Matsushita, Yojiro Ishikawa, Noriyoshi Takahashi, Tomonori Matsuura, Kei Takase, Keiichi Jingu
OBJECTIVES: To evaluate correlations between tumour response to definitive chemoradiotherapy (CRT) in oesophageal squamous cell carcinoma (SCC) and histogram-derived apparent diffusion coefficient (ADC) parameters on diffusion-weighted MR images. METHODS: Forty patients with clinical T3-4 oesophageal SCC underwent concurrent CRT. MR examination at 3 T was performed 1-3 days prior to CRT. Readout-segmented echo-planar diffusion imaging was used to acquire ADC maps...
May 3, 2018: European Radiology
Hyunjo Jeong, Sungjong Cho, Shuzeng Zhang, Xiongbing Li
This paper describes the acoustic nonlinearity parameter (β) determination for fluids using a pulse-echo method with the stress-free boundary. A newly derived β formula requires the measurement of the fundamental and second harmonic displacements with appropriate corrections for attenuation, diffraction, and boundary reflection. Measurements are composed of two steps: receiver calibration and harmonic generation. The β values calculated for water at several distances between the planar transducer and the water-air interface are in good agreement with literature, providing a validation for the method...
April 2018: Journal of the Acoustical Society of America
Gao Ma, Xiao-Quan Xu, Hao Hu, Guo-Yi Su, Jie Shen, Hai-Bin Shi, Fei-Yun Wu
Objective: To compare the diagnostic performance of readout-segmented echo-planar imaging (RS-EPI)-based diffusion kurtosis imaging (DKI) and that of diffusion-weighted imaging (DWI) for differentiating malignant from benign masses in head and neck region. Materials and Methods: Between December 2014 and April 2016, we retrospectively enrolled 72 consecutive patients with head and neck masses who had undergone RS-EPI-based DKI scan (b value of 0, 500, 1000, and 1500 s/mm2 ) for pretreatment evaluation...
May 2018: Korean Journal of Radiology: Official Journal of the Korean Radiological Society
Bijaya Thapa, Nabraj Sapkota, YouJung Lee, Kyle Jeong, John Rose, Lubdha M Shah, Erica Bisson, Eun-Kee Jeong
BACKGROUND: Injury in the cervical spinal cord (CSC) can lead to varying degrees of neurologic deficit and persistent disability. Diffusion tensor imaging (DTI) is a promising method to evaluate white matter integrity and pathology. However, the conventional DTI results are limited with respect to the specific details of neuropathology and microstructural architecture. In this study we used ultrahigh-b radial-DWI (UHb-rDWI) with b-values ranging from 0 to ∼7500 s/mm2 and calculated decay constant (DH ) at the high b-values, which gives much deeper insight about the microscopic environment of CSC white matter...
April 29, 2018: Journal of Magnetic Resonance Imaging: JMRI
Marek Dostál, Miloš Keřkovský, Eva Korit Áková, Eva Němcová, Jakub Stulík, Monika Staňková, Vladan Bernard
BACKGROUND: Segmentation of the gray and white matter (GM, WM) of the human spinal cord in MRI images as well as the analysis of spinal cord diffusivity are challenging. When appropriately segmented, diffusion tensor imaging (DTI) of the spinal cord might be beneficial in the diagnosis and prognosis of several diseases. PURPOSE: To evaluate the applicability of a semiautomatic algorithm provided by ITK-SNAP in classification mode (CLASS) for segmenting cervical spinal cord GM, WM in MRI images and analyzing DTI parameters...
April 29, 2018: Journal of Magnetic Resonance Imaging: JMRI
Ichiro Yamada, Norio Yoshino, Keigo Hikishima, Junichiro Sakamoto, Misaki Yokokawa, Yu Oikawa, Hiroyuki Harada, Tohru Kurabayashi, Yukihisa Saida, Ukihide Tateishi, Akane Yukimori, Toshiyuki Izumo, Shun Asahina
PURPOSE: In this study, we aimed to determine the usefulness of diffusion kurtosis imaging (DKI) as a noninvasive method for evaluation of the histologic grade and lymph node metastasis in patients with oral carcinoma. MATERIALS AND METHODS: Twenty-seven patients with oral carcinoma were examined with a 3-T MR system and 16-channel coil. DKI data were obtained by a single-shot echo-planar imaging sequence with repetition time, 10,000 ms; echo time, 94 ms; field of view, 250 × 204...
April 25, 2018: Magnetic Resonance Imaging
Benedikt Rieger, Mehmet Akçakaya, José C Pariente, Sara Llufriu, Eloy Martinez-Heras, Sebastian Weingärtner, Lothar R Schad
Magnetic resonance fingerprinting (MRF) is a promising method for fast simultaneous quantification of multiple tissue parameters. The objective of this study is to improve the coverage of MRF based on echo-planar imaging (MRF-EPI) by using a slice-interleaved acquisition scheme. For this, the MRF-EPI is modified to acquire several slices in a randomized interleaved manner, increasing the effective repetition time of the spoiled gradient echo readout acquisition in each slice. Per-slice matching of the signal-trace to a precomputed dictionary allows the generation of T1 and T2 * maps with integrated B1 + correction...
April 27, 2018: Scientific Reports
Olli Nykänen, Lassi Rieppo, Juha Töyräs, Ville Kolehmainen, Simo Saarakkala, Karin Shmueli, Mikko J Nissi
PURPOSE: We investigated the feasibility of quantitative susceptibility mapping (QSM) for assessing degradation of articular cartilage by measuring ex vivo bovine cartilage samples subjected to different degradative treatments. Specimens were scanned at several orientations to study if degradation affects the susceptibility anisotropy. T2*-mapping, histological stainings, and polarized light microscopy were used as reference methods. Additionally, simulations of susceptibility in layered geometry were performed...
April 24, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Congbo Cai, Chao Wang, Yiqing Zeng, Shuhui Cai, Dong Liang, Yawen Wu, Zhong Chen, Xinghao Ding, Jianhui Zhong
PURPOSE: An end-to-end deep convolutional neural network (CNN) based on deep residual network (ResNet) was proposed to efficiently reconstruct reliable T2 mapping from single-shot overlapping-echo detachment (OLED) planar imaging. METHODS: The training dataset was obtained from simulations that were carried out on SPROM (Simulation with PRoduct Operator Matrix) software developed by our group. The relationship between the original OLED image containing two echo signals and the corresponding T2 mapping was learned by ResNet training...
April 24, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Sarah Keller, Avneesh Chhabra, Shaheen Ahmed, Anne C Kim, Jonathan M Chia, Jin Yamamura, Zhiyue J Wang
OBJECTIVE: Quantitative diffusion tensor imaging (DTI) of skeletal muscles is challenging due to the bias in DTI metrics, such as fractional anisotropy (FA) and mean diffusivity (MD), related to insufficient signal-to-noise ratio (SNR). This study compares the bias of DTI metrics in skeletal muscles via pixel-based and region-of-interest (ROI)-based analysis. METHODS: DTI of the thigh muscles was conducted on a 3.0-T system in N = 11 volunteers using a fat-suppressed single-shot spin-echo echo planar imaging (SS SE-EPI) sequence with eight repetitions (number of signal averages (NSA) = 4 or 8 for each repeat)...
May 2018: European Journal of Radiology
Marcin Czarniecki, Iztok Caglic, James T Grist, Andrew B Gill, Kamil Lorenc, Rhys A Slough, Andrew N Priest, Tristan Barrett
OBJECTIVE: To compare image quality, artefact, and distortion in standard echo-planar imaging (EPI) with periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) for prostate magnetic resonance imaging (MRI) diffusion-weighted imaging (DWI) in patients with previous total hip replacement (THR). METHODS: 21 male subjects with a clinical suspicion for, or known prostate cancer and previous THR were scanned at 1.5 T using a phased-array body coil...
May 2018: European Journal of Radiology
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