Effects of the Training Data Condition on Arterial Spin Labeling Parameter Estimation Using a Simulation-Based Supervised Deep Neural Network.

Objective: A simulation-based supervised deep neural network (DNN) can accurately estimate cerebral blood flow (CBF) and arterial transit time (ATT) from multidelay arterial spin labeling signals. However, the performance of deep learning depends on the characteristics of the training data set. We aimed to investigate the effects of the ground truth (GT) ranges of CBF and ATT on the performance of the DNN when training data were prepared using arterial spin labeling signal simulation.

[Usefulness of Breath-hold DWI Focused on the Hepatic Dome in EOB-MRI].

Purpose: Respiratory-triggered-diffusion-weighted imaging (R-DWI) of the liver often results in poor image quality under the diaphragmatic dome on the cephalic side of the liver (hepatic dome) secondary to magnetic field inhomogeneity in liver magnetic resonance imaging (MRI). Hence, the usefulness of additional breath-hold-DWI (B-DWI) focusing on the hepatic dome was investigated.

Methods: A total of 22 patients (14 men and 8 women; mean age 69.

Estimation of Cerebral Blood Flow and Arterial Transit Time From Multi-Delay Arterial Spin Labeling MRI Using a Simulation-Based Supervised Deep Neural Network.

Background: An inherently poor signal-to-noise ratio (SNR) causes inaccuracy and less precision in cerebral blood flow (CBF) and arterial transit time (ATT) when using arterial spin labeling (ASL). Deep neural network (DNN)-based parameter estimation can solve these problems.

Purpose: To reduce the effects of Rician noise on ASL parameter estimation and compute unbiased CBF and ATT using simulation-based supervised DNNs.

The Utility of Arterial Transit Time Measurement for Evaluating the Hemodynamic Perfusion State of Patients with Chronic Cerebrovascular Stenosis or Occlusive Disease: Correlative Study between MR Imaging and O-labeled HO Positron Emission Tomography.

Purpose: To verify whether arterial transit time (ATT) mapping can correct arterial spin labeling-cerebral blood flow (ASL-CBF) values and to verify whether ATT is a parameter that correlates with positron emission tomography (PET)-oxygen extraction fraction (OEF) and PET-mean transit time (MTT).

Methods: Eleven patients with unilateral major cerebral artery stenosis or occlusion underwent MRI and PET in the chronic or asymptomatic phase. ASL-MRI acquisitions were conducted with each of two post-label delay (PLD) settings (0.

Atlas-based relaxometry and subsegment analysis of the substantia nigra pars compacta using quantitative MRI: a healthy volunteer study.

Objective: Parkinson's disease is a neurodegenerative disorder caused by neuronal cell loss in the substantia nigra pars compacta (SNpc). We aimed to perform atlas-based relaxometry using an anatomical SNpc atlas and obtain baseline values of SNpc regions in healthy volunteers.

Methods: Neuromelanin (NM)-sensitive imaging of the midbrain and whole-brain 3D weighted images of 27 healthy volunteers (20 males; aged 36.

Separating spin compartments in arterial spin labeling using delays alternating with nutation for tailored excitation (DANTE) pulse: A validation study using T -relaxometry and application to arterial cerebral blood volume imaging.

Purpose: To clarify the type of spin compartment in arterial spin labeling (ASL) that is eliminated by delays alternating with nutation for tailored excitation (DANTE) pulse using T -relaxometry, and to demonstrate the feasibility of arterial cerebral blood volume (CBV ) imaging using DANTE-ASL in combination with a simplified two-compartment model.

Method: The DANTE and T -preparation modules were combined into a single ASL sequence. T values under the application of DANTE were determined to evaluate changes in T , along with the post-labeling delay (PLD) and the relationship between transit time without DANTE (TT ) and T .

[Evaluation of Long-term Fluctuation of Geometric Distortion in MRI for Radiation Therapy Planning by Using an Automatic Analysis Tool].

High tissue contrast in magnetic resonance imaging (MRI) allows better radiotherapy planning. However, geometric distortion in MRI induces inaccuracies affecting such planning, making it necessary to evaluate the characteristics of such geometric distortion. Although many studies have considered geometric distortion, most of these involved measurements performed only a few times.

Robust arterial transit time and cerebral blood flow estimation using combined acquisition of Hadamard-encoded multi-delay and long-labeled long-delay pseudo-continuous arterial spin labeling: a simulation and in vivo study.

Arterial transit time (ATT) prolongation causes an error of cerebral blood flow (CBF) measurement during arterial spin labeling (ASL). To improve the accuracy of ATT and CBF in patients with prolonged ATT, we propose a robust ATT and CBF estimation method for clinical practice. The proposed method consists of a three-delay Hadamard-encoded pseudo-continuous ASL (H-pCASL) with an additional-encoding and single-delay with long-labeled long-delay (1dLLLD) acquisition.

Evaluation of intraocular gas using magnetic resonance imaging after pars plana vitrectomy with gas tamponade for rhegmatogenous retinal detachment.

We used magnetic resonance imaging (MRI) to assess how a patient's posture affects intraocular gas changes and whether the postoperative prone position is required after pars plana vitrectomy (PPV) with gas tamponade for rhegmatogenous retinal detachments (RRDs). Eight patients with RRDs who underwent PPV combined with cataract surgery with gas tamponade were prospectively included. They underwent MRI examination both in the prone and supine positions.

Intravascular signal suppression and microvascular signal mapping using delays alternating with nutation for tailored excitation (DANTE) pulse for arterial spin labeling perfusion imaging.

Objective: To optimize the delays alternating with nutation for tailored excitation (DANTE) pulse as a vascular crushing gradient to eliminate macro-and micro-vascular signals and to generate a macrovascular space-related map by applying DANTE with multiple conditions.

Materials And Methods: Numerical simulation was performed to estimate the optimal flip angle (FA) of the DANTE. A phantom study was conducted to evaluate the impact of the FA and gradient area (GA) of the DANTE with three flow velocities and various parameters of the DANTE.

The use of combined T-weighted and FLAIR synthetic magnetic resonance images to improve white matter region contrast: a feasibility study.

Synthetic magnetic resonance imaging (MRI) allows the production of images with any contrast from a single scan after quantification. The combined T-weighted image (T2WI) and fluid-attenuated inversion recovery (FLAIR) image is expected to have an improved contrast between the normal-appearing white matter (WM) and WM lesion (WML). The purpose of this study was to determine whether optimal T contrast-weighted images (SyFLAIR) comprising the combined T2WI and FLAIR image generated using synthetic MRI could improve contrast in the WM region.

Evaluation of retained products of conception using pulsed continuous arterial spin-labeling MRI: clinical feasibility and initial results.

Objectives: We evaluated the vascularity of retained products of conception (RPOC) using arterial spin-labeling magnetic resonance imaging (ASL-MRI) to clarify the clinical feasibility of this approach.

Materials And Methods: A pulsed-continuous ASL sequence with echo-planar imaging (EPI) acquisitions was used. Ten consecutive patients with RPOC were enrolled.

Three-dimensional arterial spin labeling imaging with a DANTE preparation pulse.

On arterial spin-labeled (ASL) images, areas of bright intravascular signal will appear when the post labeling delay time is shorter than arterial transit time. Vascular suppression (VS) schemes reduce artefactual bright signal by dephasing intravascular labeled spins. However, existing VS methods, such as Motion-Sensitized Driven-Equilibrium (MSDE), decrease the uniformity of the signal intensity distribution and extend the echo time.

Evaluation of Bleb Fluid After Baerveldt Glaucoma Implantation Using Magnetic Resonance Imaging.

We evaluated bleb fluid images taken after Baerveldt glaucoma implantation. T2-weighted images of bleb fluid were scanned with 3 Tesla magnetic resonance imaging in 52 patients who had undergone tube-shunt surgery using the 350-mm endplate Baerveldt glaucoma implant; three-dimensional images were constructed from these images. Bleb fluid images were classified into either a layer of bleb fluid on either side of the endplate (double bleb layer group; n = 24) or one layer outside the endplate (single bleb layer group; n = 28).

Simultaneous detection of hepatocellular carcinoma and vessel thrombus by using SPIO-enhanced B-TFE with the T preparation pulse technique.

The purpose of this study was to compare between superparamagnetic iron oxide (SPIO)-enhanced three-dimensional balanced turbo field-echo (B-TFE) sequence with T preparation pulse (T prep) and T*-weighted imaging (T*WI) for the simultaneous detection of hepatocellular carcinoma (HCC) and vessel thrombus. For 1.5-T magnetic resonance imaging, SPIO was administered to 23 patients with a portal or venous tumor thrombus, and B-TFE with T prep and T*WI were acquired.

Preliminary study of apparent diffusion coefficient assessment after ion beam therapy for hepatocellular carcinoma.

We evaluated the state of hepatocellular carcinoma (HCC) and the liver after ion beam therapy by analyzing the apparent diffusion coefficient (ADC). In this retrospective study, we evaluated 13 HCC lesions in 10 patients who underwent magnetic resonance imaging before and after therapy. Diffusion-weighted imaging was performed with use of b values of 0, 150, and 800 s/mm(2).

Comparison of long-labeled pseudo-continuous arterial spin labeling (ASL) features between young and elderly adults: special reference to parameter selection.

Background: The signal intensity obtained by arterial spin labeling (ASL) depends not only on perfusion signal, but also on arterial transit time (ATT). Although ATT has a more significant effect on accurate regional cerebral blood flow (CBF) calculations, the multiple post-labeling delay (PLD) approach is difficult to use in routine examinations.

Purpose: To optimize imaging parameters for labeling duration (LD) and PLD and to confirm their validity in long-labeled pseudo-continuous ASL.

[Development of an magnetic resonance imaging safety management system for metallic biomedical products using an magnetic resonance compatibility database and inquiry-based patient records].

Several incidents involving magnetic resonance imaging (MRI) examinations of patients with unchecked MR-unsafe metallic products have been reported. To improve patient safety, we developed a new MRI safety management system for metallic biomedical products and evaluated its efficiency in clinical practice. Our system was integrated into the picture archiving and communication system (PACS) and comprised an MR compatibility database and inquiry-based patient records of internal metallic biomedical products, enabling hospital staff to check MR compatibility by product name.