In Vivo Reactive Astrocyte Imaging in Patients With Schizophrenia Using Fluorine 18-Labeled THK5351.

Importance: In vivo imaging studies of reactive astrocytes are crucial for understanding the pathophysiology of schizophrenia because astrocytes play a critical role in glutamate imbalance and neuroinflammation.

Objective: To investigate in vivo reactive astrocytes in patients with schizophrenia associated with positive symptoms using monoamine oxidase B (MAO-B)-binding fluorine 18 ([18F])-labeled THK5351 positron emission tomography (PET).

Design, Setting, And Participants: In this case-control study, data were collected from October 1, 2021, to January 31, 2023, from the internet advertisement for the healthy control group and from the outpatient clinics of Seoul National University Hospital in Seoul, South Korea, for the schizophrenia group.

Endolymphatic hydrops asymmetry distinguishes patients with Meniere's disease from normal controls with high sensitivity and specificity.

Background: Many endolymphatic hydrops (EH) MRI studies in the literature do not include a normal control group. Consequently, it remains unclear which outcome measure in EH MRI can most effectively distinguish between MD patients and normal controls.

Methods: Gadolinium-enhanced EH imaging was performed to quantitatively evaluate the extents of hydrops in MD patients and age-/sex-matched normal controls.

Three-Dimensional Volumetric Measurement of Endolymphatic Hydrops in Meniere's Disease.

We used volumetric three-dimensional (3D) analysis to quantitatively evaluate the extent of endolymphatic hydrops (EH) in the entire inner ear. We tested for correlations between the planimetric and volumetric measurements, to identify their advantages and disadvantages. HYDROPS2-Mi2 EH images were acquired for 32 ears (16 patients): 16 ipsilateral ears of MD patients (MD-ears) and 16 contralateral ears.

Simultaneous Multiparametric PET/MRI with Silicon Photomultiplier PET and Ultra-High-Field MRI for Small-Animal Imaging.

Unlabelled: Visualization of biologic processes at molecular and cellular levels has revolutionized the understanding and treatment of human diseases. However, no single biomedical imaging modality provides complete information, resulting in the emergence of multimodal approaches. Combining state-of-the-art PET and MRI technologies without loss of system performance and overall image quality can provide opportunities for new scientific and clinical innovations.

MRI-Based Attenuation Correction for PET/MRI Using Multiphase Level-Set Method.

Unlabelled: Inaccuracy in MR image-based attenuation correction (MR-AC) leads to errors in quantification and the misinterpretation of lesions in brain PET/MRI studies. To resolve this problem, we proposed an improved ultrashort echo time MR-AC method that was based on a multiphase level-set algorithm with main magnetic field (B0) inhomogeneity correction. We also assessed the feasibility of this level-set-based MR-AC method (MR-AC(level)), compared with CT-AC and MR-AC provided by the manufacturer of the PET/MRI scanner (MR-AC(mMR)).

Early prediction of response to neoadjuvant chemotherapy in breast cancer patients: comparison of single-voxel (1)H-magnetic resonance spectroscopy and (18)F-fluorodeoxyglucose positron emission tomography.

Objectives: To prospectively compare performances of single-voxel proton magnetic resonance spectroscopy ((1)H-MRS) and (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) in predicting pathologic response to neoadjuvant chemotherapy (NAC) in breast cancer patients.

Methods: Thirty-five breast cancer patients who received NAC and subsequent surgery were prospectively enrolled. MRS and FDG-PET were performed before and after the 1st NAC cycle.

Whole-brain diffusion-tensor changes in parkinsonian patients with impulse control disorders.

Background And Purpose: The aim of this study was to determine the changes in diffusion-tensor images associated with medication-related impulse control disorder (ICD) in Parkinson's disease (PD) patients undergoing chronic dopamine-replacement therapy.

Methods: Nineteen PD patients, comprising 10 with ICD (PD-ICD) and 9 without ICD (PD-nonICD), and 18 age-matched healthy controls (HCs) with no cognitive or other psychiatric disorders were analyzed. All subjects underwent 3-T magnetic resonance diffusion-tensor imaging.

Functional dysconnectivity of corticostriatal circuitry and differential response to methylphenidate in youth with attention-deficit/hyperactivity disorder.

Background: Brain frontostriatal circuits have been implicated in the pathophysiology of attention-deficit/hyperactivity disorder (ADHD). However, effects of methylphenidate on circuit-level functional connectivity are as yet unclear. The aim of the present study was to comprehensively investigate the functional connectivity of major striatal subregions in children with ADHD, including subanalyses directed at mapping cognitive and treatment response characteristics.

Intratumoral heterogeneity of breast cancer xenograft models: texture analysis of diffusion-weighted MR imaging.

Objective: To investigate whether there is a relationship between texture analysis parameters of apparent diffusion coefficient (ADC) maps and histopathologic features of MCF-7 and MDA-MB-231 xenograft models.

Materials And Methods: MCF-7 estradiol (+), MCF-7 estradiol (-), and MDA-MB-231 xenograft models were made with approval of the animal care committee. Twelve tumors of MCF-7 estradiol (+), 9 tumors of MCF-7 estradiol (-), and 6 tumors in MDA-MB-231 were included.

COMT genotype affects brain white matter pathways in attention-deficit/hyperactivity disorder.

Increased dopamine availability may be associated with impaired structural maturation of brain white matter connectivity. This study aimed to derive a comprehensive, whole-brain characterization of large-scale axonal connectivity differences in attention-deficit/hyperactivity disorder (ADHD) associated with catechol-O-methyltransferase gene (COMT) Val158Met polymorphism. Using diffusion tensor imaging, whole-brain tractography, and an imaging connectomics approach, we characterized altered white matter connectivity in youth with ADHD who were COMT Val-homozygous (N = 29) compared with those who were Met-carriers (N = 29).

Diffusion tensor tractography analysis of the corpus callosum fibers in amyotrophic lateral sclerosis.

Background And Purpose: Involvement of the corpus callosum (CC) is reported to be a consistent feature of amyotrophic lateral sclerosis (ALS). We examined the CC pathology using diffusion tensor tractography analysis to identify precisely which fiber bundles are involved in ALS.

Methods: Diffusion tensor imaging was performed in 14 sporadic ALS patients and 16 age-matched healthy controls.

Connectomic disturbances in attention-deficit/hyperactivity disorder: a whole-brain tractography analysis.

Background: Few studies have sought to identify, in a regionally unbiased way, the precise cortical and subcortical regions that are affected by white matter abnormalities in attention-deficit/hyperactivity disorder (ADHD). This study aimed to derive a comprehensive, whole-brain characterization of connectomic disturbances in ADHD.

Methods: Using diffusion tensor imaging, whole-brain tractography, and an imaging connectomics approach, we characterized altered white matter connectivity in 71 children and adolescents with ADHD compared with 26 healthy control subjects.

Extrastriatal dopaminergic changes in Parkinson's disease patients with impulse control disorders.

Objective: To investigate the extrastriatal dopaminergic neural changes in relation to the medication-related impulse control disorders (ICD) in Parkinson's disease (PD).

Method: A total of 31 subjects (11 and 11 drug-treated PD patients with and without medication-related ICDs and 9 healthy controls) having no other co-morbid psychiatric disorders participated in this study. Each subject underwent dynamic N-(3-[(18)F]fluoropropyl)-2-carbomethoxy-3-(4-iodophenyl) nortropane (FP-CIT) positron emission tomography scans.

Effect of delayed transit time on arterial spin labeling: correlation with dynamic susceptibility contrast perfusion magnetic resonance in moyamoya disease.

Objectives: Because arterial spin labeling (ASL) is completely noninvasive and provides absolute cerebral blood flow (CBF) information within a brief period, the technique has been increasingly used for patients with acute or chronic cerebrovascular disease. However, the effect of delayed transit time on ASL can generate errors in the quantitative estimation of CBF using ASL. Furthermore, in the clinical setting, in which transit time is uncertain, the variability of the transit time in patients reduces the validity of CBF on ASL images.

Serial MR analysis of early permanent and transient ischemia in rats: diffusion tensor imaging and high b value diffusion weighted imaging.

Objective: To evaluate the temporal evolution and diagnostic values of the diffusion tensor imaging (DTI) and the high b value diffusion weighted imaging (DWI) in the early permanent and transient cerebral ischemia.

Materials And Methods: For permanent or 30-minute transient-ischemia induced 30 rats, DTI and DWIs at both high b (b = 3000 s/mm(2)) and standard b value (b = 1000 s/mm(2)) were obtained at the following conditions: at 15, 30, 45, 60 minutes after the occlusion of what for hyperacute permanent ischemia; at 1, 3, 5, 7, 9 hours after the occlusion for acute permanent ischemia; and at 15 minutes before reperfusion, 0.5, 2.

Comparison of segmentation-based attenuation correction methods for PET/MRI: evaluation of bone and liver standardized uptake value with oncologic PET/CT data.

Unlabelled: For attenuation correction (AC) in PET/MRI systems, segmentation-based methods are most often used. However, the standardized uptake value (SUV) of lesions in the bone and liver, which have higher attenuation coefficients than other organs, can be underestimated, potentially leading to misinterpretation of clinical cases. Errors in SUV estimation are also dependent on the segmentation schemes used in the segmentation-based AC.

SiPM-PET with a short optical fiber bundle for simultaneous PET-MR imaging.

For positron emission tomography (PET) inserts to magnetic resonance imaging (MRI) applications, optical fibers have been used for some time to transfer scintillation photons to photomultiplier tubes positioned outside the fringe magnetic field. We previously proposed a novel utilization of an optical fiber for good radio frequency (RF) transmission from body coils to an imaging object. Optical fiber bundles between silicon photomultipliers (SiPM) and scintillation crystals provide an increased spacing between RF-shielded electronics boxes, facilitating RF passage from the body RF coils to imaging objects.

Hydrotropic magnetic micelles for combined magnetic resonance imaging and cancer therapy.

Polymeric nanoparticles, capable of encapsulating imaging agents and therapeutic drugs, have significant advantages for simultaneous diagnosis and therapy. Nonetheless, improvements in the loading contents of the active agents are needed to achieve enhanced imaging and effective therapeutic outcomes. Aiming to make these improvements, a hydrotropic micelle (HM) was explored to encapsulate superparamagnetic iron oxide nanoparticles (SPIONs) as the magnetic resonance (MR) imaging agent and paclitaxel (PTX) as the hydrophobic anticancer drug.

Initial results of simultaneous PET/MRI experiments with an MRI-compatible silicon photomultiplier PET scanner.

Unlabelled: The most investigated semiconductor photosensor for MRI-compatible PET detectors is the avalanche photodiode (APD). However, the silicon photomultiplier (SiPM), also called the Geiger-mode APD, is gaining attention in the development of the next generation of PET/MRI systems because the SiPM has much better performance than the APD. We have developed an MRI-compatible PET system based on multichannel SiPM arrays to allow simultaneous PET/MRI.

Correlation of perfusion parameters on dynamic contrast-enhanced MRI with prognostic factors and subtypes of breast cancers.

Purpose: To investigate whether a correlation exists between perfusion parameters obtained from dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) and prognostic factors or immunohistochemical subtypes of breast cancers.

Materials And Methods: Quantitative parameters (K(trans) , k(ep) , and v(e) ) of 70 invasive ductal carcinomas were obtained using DCE-MRI as a postprocessing procedure. Correlations between parameters and prognostic factors, including tumor size, axillary nodal status, histologic grade, nuclear grade, expression of estrogen receptor (ER), progesterone receptor (PR), Ki-67, p53, bcl-2, and human epidermal growth factor receptor 2 (HER2) and subtypes categorized as luminal (ER or PR-positive), triple negative (ER or PR-negative, HER2-negative), and HER2 (ER and PR-negative, HER2 overexpression) were analyzed.

Development of small-animal PET prototype using silicon photomultiplier (SiPM): initial results of phantom and animal imaging studies.

Unlabelled: Silicon photomultiplier (SiPM; also called a Geiger-mode avalanche photodiode) is a promising semiconductor photosensor in PET and PET/MRI because it is intrinsically MRI-compatible and has internal gain and timing properties comparable to those of a photomultiplier tube. In this study, we have developed a small-animal PET system using SiPMs and lutetium gadolinium oxyorthosilicate (LGSO) crystals and performed physical evaluation and animal imaging studies to show the feasibility of this system.

Methods: The SiPM PET system consists of 8 detectors, each of which comprises 2 × 6 SiPMs and 4 × 13 LGSO crystals.

Diffusion-weighted MR imaging: pretreatment prediction of response to neoadjuvant chemotherapy in patients with breast cancer.

Purpose: To evaluate the potential of diffusion-weighted (DW) magnetic resonance (MR) imaging with an apparent diffusion coefficient (ADC) map in the prediction of response to neoadjuvant chemotherapy in patients with breast cancer.

Materials And Methods: This retrospective study was approved by the institutional review board, which waived the informed consent requirement. Fifty-three consecutive women (mean age, 43.

Tumor targeting chitosan nanoparticles for dual-modality optical/MR cancer imaging.

We report tumor targeting nanoparticles for optical/MR dual imaging based on self-assembled glycol chitosan to be a potential multimodal imaging probe. To develop an optical/MR dual imaging probe, biocompatible and water-soluble glycol chitosan (M(w) = 50 kDa) were chemically modified with 5beta-cholanic acid (CA), resulting in amphiphilic glycol chitosan-5beta-cholanic acid conjugates (GC-CA). For optical imaging near-infrared fluorescence (NIRF) dye, Cy5.