Impact of tissue sample preparation methods on myelin-sensitive quantitative MR imaging.

Purpose: Validation of quantitative MRI (qMRI) parameters with histology is often done with ex vivo fixed tissue samples. Freezing is another common form of tissue preservation, but the effects of freezing and thawing tissue on myelin-sensitive quantitative MRI parameters and their correlation with histology require further analysis.

Methods: Myelin water imaging, off-resonance RF saturation magnetization transfer (MT), and selective inversion recovery MT MRI experiments were conducted on 14 fresh, thawed, and fixed sheep brain tissue samples to calculate various surrogate measures of myelin content.

Impact of Tissue Sample Preparation Methods on Myelin-Sensitive Quantitative MR Imaging.

Purpose: Validation of quantitative MRI (qMRI) parameters with histology is often done with ex vivo fixed tissue samples. Freezing is another common form of tissue preservation, but the effects of freezing and thawing tissue on myelin-sensitive quantitative MRI parameters and their correlation with histology require further analysis.

Methods: Myelin water imaging, off-resonance RF saturation magnetization transfer (MT), and selective inversion recovery MT MRI experiments were conducted on 14 fresh, thawed, and fixed sheep brain tissue samples to calculate various surrogate measures of myelin content.

Circulating and Magnetic Resonance Imaging Biomarkers of Intestinal Fibrosis in Small Bowel Crohn's Disease.

Background: We previously identified circulating and MRI biomarkers associated with the surgical management of Crohn's disease (CD). Here we tested associations between these biomarkers and ileal resection inflammation and collagen content.

Methods: Fifty CD patients undergoing ileal resection were prospectively enrolled at 4 centers.

MRI and Blood-based Biomarkers Are Associated With Surgery in Children and Adults With Ileal Crohn's Disease.

Background: Despite advances in medical therapy, many children and adults with ileal Crohn's disease (CD) progress to fibrostenosis requiring surgery. We aimed to identify MRI and circulating biomarkers associated with the need for surgical management.

Methods: This prospective, multicenter study included pediatric and adult CD cases undergoing ileal resection and CD controls receiving medical therapy.

Technical note: hydrogel-based mimics of prostate cancer with matched relaxation, diffusion and kurtosis for validating multi-parametric MRI.

Background: Protocol standardization and optimization for clinical translation of emerging quantitative multiparametric (mp)MRI biomarkers of high-risk prostate cancer requires imaging references that mimic realistic tissue value combinations for bias assessment in derived relaxation and diffusion parameters.

Purpose: This work aimed to develop a novel class of hydrogel-based synthetic materials with simultaneously controlled quantitative relaxation, diffusion, and kurtosis parameters that mimic in vivo prostate value combinations in the same spatial compartment and allow stable assemblies of adjacent structures.

Methods: A set of materials with tunable T, diffusion, and kurtosis were assembled to create quantitative biomimetic (mp)MRI references.

The impeded diffusion fraction quantitative imaging assay demonstrated in multi-exponential diffusion phantom and prostate cancer.

Purpose: To demonstrate a method for quantification of impeded diffusion fraction (IDF) using conventional clinical DWI protocols.

Methods: The IDF formalism is introduced to quantify contribution from water coordinated by macromolecules to DWI voxel signal based on fundamentally different diffusion constants in vascular capillary, bulk free, and coordinated water compartments. IDF accuracy was studied as a function of b-value set.

Functionalized nanoparticles with targeted antibody to enhance imaging of breast cancer in vivo.

Background: Targeted contrast nanoparticles for breast tumor imaging facilitates early detection and improves treatment efficacy of breast cancer. This manuscript reports the development of an epidermal growth factor receptor-2 (HER-2) specific, bi-modal, dendrimer conjugate to enhance computed tomography (CT) and magnetic resonance imaging (MRI) of HER-2-positive breast cancer. This material employs generation 5 poly(amidoamine) dendrimers, encapsulated gold nanoparticles, chelated gadolinium, and anti-human HER-2 antibody to produce the nanoparticle contrast agent.

Relayed nuclear Overhauser enhancement sensitivity to membrane Cho phospholipids.

Purpose: Phospholipids are key constituents of cell membranes and serve vital functions in the regulation of cellular processes; thus, a method for in vivo detection and characterization could be valuable for detecting changes in cell membranes that are consequences of either normal or pathological processes. Here, we describe a new method to map the distribution of partially restricted phospholipids in tissues.

Methods: The phospholipids were measured by signal changes caused by relayed nuclear Overhauser enhancement-mediated CEST between the phospholipid Cho headgroup methyl protons and water at around -1.

Multicenter Repeatability Study of a Novel Quantitative Diffusion Kurtosis Imaging Phantom.

Quantitative kurtosis phantoms are sought by multicenter clinical trials to establish accuracy and precision of quantitative imaging biomarkers on the basis of diffusion kurtosis imaging (DKI) parameters. We designed and evaluated precision, reproducibility, and long-term stability of a novel isotropic (i)DKI phantom fabricated using four families of chemicals based on vesicular and lamellar mesophases of liquid crystal materials. The constructed iDKI phantoms included negative control monoexponential diffusion materials to independently characterize noise and model-induced bias in quantitative kurtosis parameters.

Repeatability of Quantitative Diffusion-Weighted Imaging Metrics in Phantoms, Head-and-Neck and Thyroid Cancers: Preliminary Findings.

The aim of this study was to establish the repeatability measures of quantitative Gaussian and non-Gaussian diffusion metrics using diffusion-weighted imaging (DWI) data from phantoms and patients with head-and-neck and papillary thyroid cancers. The Quantitative Imaging Biomarker Alliance (QIBA) DWI phantom and a novel isotropic diffusion kurtosis imaging phantom were scanned at 3 different sites, on 1.5T and 3T magnetic resonance imaging systems, using standardized multiple b-value DWI acquisition protocol.

A unique anisotropic R of collagen degeneration (ARCADE) mapping as an efficient alternative to composite relaxation metric (R -R ) in human knee cartilage study.

Purpose: Anisotropic transverse R (1/T ) relaxation of water proton is sensitive to cartilage degenerative changes. The purpose is to develop an efficient method to extract this relaxation metric in clinical studies.

Methods: Anisotropic R can be measured inefficiently by standard R mapping after removing an isotropic contribution obtained from R mapping.

Ultracompact Nanotheranostic PEG Platform for Cancer Applications.

We present a new targetable nanoconstruct (NC) capable of simultaneously serving as a therapeutic platform for photodynamic therapy (PDT) as well as a magnetic resonance (MR) molecular imaging agent, free of heavy metal atoms. PDT has seen much interest with the introduction of NC-assisted cell-specific targeting of the photosensitizer (PS). The previously reported ultrasmall 8-arm polyethylene glycol amine (8PEGA) NC, with an attached chlorin e6 (Ce6) PS, yielded promising results for PDT of heart arrhythmia, and , on live rat and sheep hearts, respectively, when using targeting peptides for of cardio-myocytes.

Regional cardiac function analysis from tagged MRI images. Comparison of techniques: Harmonic-Phase (HARP) versus Sinusoidal-Modeling (SinMod) analysis.

Cardiac MRI tagging is a valuable technique for evaluating regional heart function. Currently, there are a number of different techniques for analyzing the tagged images. Specifically, k-space-based analysis techniques showed to be much faster than image-based techniques, where harmonic-phase (HARP) and sine-wave modeling (SinMod) stand as two famous techniques of the former group, which are frequently used in clinical studies.

Left ventricular metabolism, function, and sympathetic innervation in men and women with type 1 diabetes.

Background: In type I diabetes (T1DM), alterations in LV function may occur due to changes in innervation, metabolism, and efficiency.

Objectives: We evaluated the association between sympathetic nerve function, oxidative metabolism, resting blood flow, LV efficiency and function in healthy diabetics, and assessed gender differences.

Methods: Cross-sectional study of 45 subjects with T1DM, 60% females, age 34 ± 13 years, and 10 age-matched controls.

Molecular, dynamic, and structural origin of inhomogeneous magnetization transfer in lipid membranes.

Purpose: To elucidate the dynamic, structural, and molecular properties that create inhomogeneous magnetization transfer (ihMT) contrast.

Methods: Amphiphilic lipids, lamellar phospholipids with cholesterol, and bovine spinal cord (BSC) specimens were examined along with nonlipid systems. Magnetization transfer (MT), enhanced MT (eMT, obtained with double-sided radiofrequency saturation), ihMT (MT - eMT), and dipolar relaxation, T , were measured at 2.

Comparison of noncontrast MRI magnetization transfer and T2 -Weighted signal intensity ratios for detection of bowel wall fibrosis in a Crohn's disease animal model.

Purpose: To compare the abilities of magnetization transfer magnetic resonance imaging (MT-MRI) and T2 -weighted signal intensity (T2 WSI) ratios to detect intestinal fibrosis in a Crohn's disease animal model.

Materials And Methods: Ten rats ("Group 1") received one trinitrobenzenesulfonic acid enema to induce acute colonic inflammation, while 10 additional animals ("Group 2") received multiple enemas to induce colonic inflammation and fibrosis. Gradient recalled-echo MT-MRI (5 and 10 kHz off-resonance) and T2 -weighted spin-echo imaging were performed 2 days after the last enema.

Simultaneous fat saturation and magnetization transfer contrast imaging with steady-state incoherent sequences.

Purpose: This work combines an n-dimensional fat sat(uration) radiofrequency (RF) pulse with steady-state incoherent (SSI) pulse sequences, e.g., spoiled gradient-echo sequence, to simultaneously produce B0 insensitive fat suppression and magnetization transfer (MT) contrast.

Acceleration of ultrasound thermal therapy by patterned acoustic droplet vaporization.

One application of acoustic droplet vaporization (ADV), a method of converting biocompatible microdroplets into microbubbles, is to enhance locally high intensity focused ultrasound (HIFU) therapy. Two objectives are pursued here: (1) the controlled creation of a bubble trench prior to HIFU using ADV and (2) use of the trench for increasing ablation volumes, lowering acoustic powers, and decreasing therapy duration. Thermally responsive phantoms were made with perfluorocarbon emulsion.

Magnetization transfer in lamellar liquid crystals.

Purpose: This study examines the relationship between quantitative magnetization transfer (qMT) parameters and the molecular composition of a model lamellar liquid crystal (LLC) system composed of 1-decyl alcohol (decanol), sodium dodecyl sulfate (SDS), and water.

Methods: Samples were made within a stable lamellar mesophase to provide different ratios of total semisolid protons (SDS + decanol) to water protons. Data were collected as a function of radiofrequency power, frequency offset, and temperature.

Tissue-compliant neural implants from microfabricated carbon nanotube multilayer composite.

Current neural prosthetic devices (NPDs) induce chronic inflammation due to complex mechanical and biological reactions related, in part, to staggering discrepancies of mechanical properties with neural tissue. Relatively large size of the implants and traumas to blood-brain barrier contribute to inflammation reactions, as well. Mitigation of these problems and the realization of long-term brain interface require a new generation of NPDs fabricated from flexible materials compliant with the brain tissue.

Anti-tumor necrosis factor α prevents bowel fibrosis assessed by messenger RNA, histology, and magnetization transfer MRI in rats with Crohn's disease.

Objective: Treatment of Crohn's disease (CD) with anti-tumor necrosis factor α (TNFα) decreases intestinal inflammation, but the effect on fibrosis remains unclear. We hypothesized that treatment with rat-specific anti-TNFα will decrease the development of intestinal fibrosis in a rat model of CD. We further hypothesized that magnetization transfer magnetic resonance imaging (MT-MRI) will be sensitive in detecting these differences in collagen content.

Feasibility of LNG-IUS in a baboon model.

Background: The baboon (Papio hamadryas anubis) is an attractive model for intrauterine contraception research due to anatomic similarity to the human. Although non-human primates have previously been used for intrauterine contraception research, it was unknown whether modern intrauterine devices (IUDs) can be placed in an anatomically similar position in the baboon. This study sought to determine whether human-use IUDs could be seated correctly in the uterus of the baboon.

Intermediate-term effects of intracardiac communications created noninvasively by therapeutic ultrasound (histotripsy) in a porcine model.

The authors have demonstrated that histotripsy (pulsed cavitational ultrasound) can create atrial septal defects and ventricular septal defects (VSDs) in an open-chest canine model transcutaneously through the intact chest of neonatal pigs. To assess the potential untoward effects of these applications, the clinical, systemic, and pathologic effects of histotripsy-induced intracardiac communications were analyzed. Six neonatal pigs received noninvasive ultrasound therapy to their ventricular septa, then were allowed to survive 1 month for evaluation of intermediate-term effects.

Acoustic droplet vaporization for enhancement of thermal ablation by high intensity focused ultrasound.

Rationale And Objectives: Acoustic droplet vaporization (ADV) shows promise for spatial control and acceleration of thermal lesion production. The investigators hypothesized that microbubbles generated by ADV could enhance high-intensity focused ultrasound (HIFU) thermal ablation by controlling and increasing local energy absorption.

Materials And Methods: Thermal lesions were produced in tissue-mimicking phantoms using focused ultrasound (1.