[Reduction of Motion Artifacts in Liver MRI Using Deep Learning with High-pass Filtering].

Purpose: To investigate whether deep learning with high-pass filtering can be used to effectively reduce motion artifacts in magnetic resonance (MR) images of the liver.

Methods: The subjects were 69 patients who underwent liver MR examination at our hospital. Simulated motion artifact images (SMAIs) were created from non-artifact images (NAIs) and used for deep learning.

Quantitative evaluation of functional liver reserve using the liver-to-spleen ΔR ratio based on gadoxetic acid-enhanced MRI: corrected for the effect of gadoxetic acid dose.

Background: The liver T reduction rate can be used to assess liver function. However, higher doses of gadoxetic acid may shorten the liver T value in the hepatobiliary phase and increase the T reduction rate in patients with severe liver dysfunction, potentially overestimating liver function.

Purpose: To verify the relationship between the gadoxetic acid dose and the liver T reduction rate and ΔR of the liver and spleen, and to clarify whether the ΔR of hepatocytes, corrected for the effect of gadoxetic acid dose, could be used as an index of functional liver reserve.

[Feasibility of Cerebrovascular Reserve Assessment Using Stretched Exponential Model in Major Cerebral Artery Steno-occlusive Disease: Comparison with SPECT].

Purpose: To clarify whether diffusion-weighted imaging using stretched exponential model can assess cerebrovascular reserve (CVR) in patients with major cerebral artery steno-occlusive disease, we compared stretched exponential parameters and single-photon emission computed tomography (SPECT).

Methods: Twenty-nine patients with unilateral major cerebral artery steno-occlusive disease (25 men and 4 women; age, 69±11 years) were analyzed in this study. The patients were divided into three groups: normal CVR (CVR≥30%), moderate CVR (10%≤CVR<30%), and severe CVR (CVR<10%).

[Effects of Changing the Source-to-image Receptor Distance Parameter of Scattered X-ray Correction after Exposure on Image Quality in Portable Chest Radiography].

Purpose: To validate the effects of changing the source-to-image receptor distance (SID) parameter of scattered X-ray correction after exposure on the image quality in portable chest radiography.

Methods: The actual SID and tube current-time product (mAs) were varied such that the direct X-ray dose to a flat panel detector (FPD) remained constant. We created two groups as follows: Group A (with the SID parameter unchanged) and Group B (with the SID parameter changed to the actual SID after a phantom chest exposure).

Improvement in the contrast-to-noise ratio and quantitative measurement of T and T* values for carotid atherosclerotic plaque using multi-echo phase-sensitive inversion recovery.

Quantitative magnetic resonance imaging is required to accurately evaluate carotid plaque vulnerability. We prospectively evaluated the potential for fast quantitative black-blood carotid vessel wall imaging using a three-dimensional (3D) multi-echo phase-sensitive inversion recovery (mPSIR) sequence. Forty-nine patients with carotid atherosclerotic plaques were examined.

Quantitative evaluation of focal liver lesions with T1 mapping using a phase-sensitive inversion recovery sequence on gadoxetic acid-enhanced MRI.

Purpose: To determine the usefulness of T1 values measured using a phase-sensitive inversion recovery (PSIR) sequence for the diagnosis of focal liver lesions.

Method: The study enrolled 87 patients who underwent gadoxetic acid-enhanced magnetic resonance imaging (MRI) for assessment of 38 hepatocellular carcinomas, 33 hepatic hemangiomas, 30 metastatic liver tumors, and 14 hepatic cysts. PSIR was performed before and 15 min after contrast agent administration, and then the respective T1 values were measured and the T1 reduction rate was calculated.

[Comparison of Arterial Spin-labeling Perfusion Images at Different Spatial Normalization Methods Based on Voxel-based Statistical Analysis].

Purpose: Spatial normalization is a significant image pre-processing operation in statistical parametric mapping (SPM) analysis. The purpose of this study was to clarify the optimal method of spatial normalization for improving diagnostic accuracy in SPM analysis of arterial spin-labeling (ASL) perfusion images.

Methods: We evaluated the SPM results of five spatial normalization methods obtained by comparing patients with Alzheimer's disease or normal pressure hydrocephalus complicated with dementia and cognitively healthy subjects.