Increased contrast in magnetic resonance imaging (MRI) is accomplished using polymeric micelles loaded with superparamagnetic iron oxide (SPIO) nanoparticles encapsulated biocompatible, biodegradable poly(ϵ-caprolactone)-b-poly(ethylene glycol) (PCL-b-PEG) copolymers (see Figure). The show significantly improved T2 relaxivities and remarkable MRI detection sensitivity. Supporting information for this article available on the WWW under http://www.wiley-vch.de/contents/jc_2089/2005/c1904_s.pdf...

Abstract This clinical trial was performed to evaluate the safety and feasibility of interactive MR‐guided radiofrequency (RF) interstitial thermal ablation (ITA) entirely within MR imager. RF‐ITA on 11 intra‐abdominal metastatic tumors during 13 sessions. The RF electrode placed under guidance a .2‐T system using rapid fast imaging with steady state precession (FISP) true FISP images. A custom 17‐gauge used modified in four sessions allow circulation iced saline for cooling ablation. Tissue...

The purpose of this investigation was to evaluate the accuracy MR Imaging for needle depiction at 0.2 and 1.5 T with multiple pulse sequences orientations. goal provide a framework biopsy approach imaging technique parameter selection that will ensure safety MR-guided procedures.Eight titanium stainless steel alloy MR-compatible devices were immersed in fluid phantoms placed into 1.5- 0.2-T systems used clinical imaging. Spin-echo, turbo spin-echo, gradient-echo images obtained shafts...

Abstract Clinical requirements for interventional MRI (I‐MRI) monitoring of needle placement or thermal ablation demand rapid (near‐real‐time) image acquisition rates, high spatial resolution, and T2 weighting. Experimental analysis performed earlier (see ref. 8) suggests that many sequences used either scanning weighting at fields fail to meet both the speed (conventional spin echo [SE], turbo SE) contrast (ie, fast low‐angle shot [FLASH], imaging with steady state precession [FISP]) when...

A technique has been developed that significantly improves the image resolution and reduces motion artifacts in conventional two-dimensional Fourier transform three-dimensional magnetic resonance imaging sequences. Modifications on gradient waveforms completely refocus transverse magnetization at echo time, regardless of occurring between time 90° radiofrequency excitation (within-view). This accomplishes suppression regains signal from flowing blood CSF. Images head, abdomen, chest, spine...

PURPOSE: To perform a phase II clinical trial to evaluate efficacy and safety of interactive magnetic resonance (MR) imaging–guided radiofrequency (RF) interstitial thermal ablation (ITA) primary renal tumors. MATERIALS AND METHODS: Ten male patients (age range, 25–83 years) with peripheral cell carcinoma contraindications surgery were treated percutaneous RF ITA entirely guided monitored 0.2-T MR imaging unit. By using 200-W system custom-fabricated imaging–compatible cool-tip electrodes,...

Our goal was to determine whether functional MRI on a standard 1.5 T system can localize activation during visual vigilance sustained attention task and this corresponds results described in PET investigation of similar task.Sixteen volunteers were studied using gradient echo technique. A single axial section oriented within stereotaxic coordinate space, 40 mm superior the anterior-posterior commissure line. Images with eyes closed followed by images subject concentration small dim spot....

Interactive MR imaging-guided biopsy and aspiration with a modified clinical C-arm system.J S Lewin, C A Petersilge, F Hatem, J L Duerk, G Lenz, M E Clampitt, Williams, K R Kaczynski, Lanzieri, Wise HaagaAudio Available | Share

Purpose: To evaluate an augmented reality (AR) system in combination with a 1.5-T closed-bore magnetic resonance (MR) imager as navigation tool for needle biopsies. Materials and Methods: The experimental protocol had institutional animal care use committee approval. Seventy biopsies were performed phantoms by using 20 tube targets, each diameter of 6 mm, 50 virtual targets. position the tip AR MR space was compared multiple imaging planes, real localization errors calculated. Ten AR-guided...

To generate real-time, nongated, free-breathing cardiac images, the undersampled radial trajectory combined with parallel imaging in form of GRAPPA has shown promise. However, this method starts to fail at high undersampling factors due assumptions that must be made for purposes calibrating weight sets. In manuscript, a novel through-time calibration scheme is proposed which greatly improves image quality acceleration required real-time imaging. This offers better than standard GRAPPA, but...

The authors evaluated semiautomatic, voxel-based registration methods for a new application, the assessment and optimization of interventional magnetic resonance imaging (I-MRI) guided thermal ablation liver cancer. abdominal images acquired on low-field-strength, open I-MRI system contain noise, motion artifacts, tissue deformation. Dissimilar can be obtained as result different MRI acquisition techniques and/or changes induced by treatments. These features challenge algorithm. one manual...

Abstract This investigation explores the feasibility of a catheter‐based receiver probe for NMR study arterial walls. Simulations and phantom experiments demonstrate spatial response several “inside‐out” coil designs, including loop, “birdcage,” “multipole,” “center return,” opposed solenoids. For target defined by an annulus in plane perpendicular to B 0 , solenoid design provides substantially superior homogeneity other designs considered. Canine iliofemoral artery images were acquired...

This study examined the contribution and interdependence of multiple imaging parameters in clinical sequences to aid practicing radiologists minimizing artifacts during MR spine after implantation titanium pedicle screws.A lumbar specimen with screws implanted was imaged a 1.5-T scanner. Sequence type, voxel volume, TE, bandwidth varied. Different volumes were achieved by altering section thickness, field view (FOV), matrix size. Artifact size measured on sagittal axial images at midpedicle...

Bone marrow reconversion in adults who are smokers: MR Imaging findings.T B Poulton, W D Murphy, J L Duerk, C Chapek and H FeiglinAudio Available | Share

In this study, we registered live-time interventional magnetic resonance imaging (iMRI) slices with a previously obtained high-resolution MRI volume that in turn can be variety of functional images, e.g., PET, SPECT, for tumor targeting. We created and evaluated slice-to-volume (SV) registration algorithm special features its potential use iMRI-guided radio-frequency (RF) thermal ablation prostate cancer. The included multiresolution approach, two similarity measures, automatic restarting to...

Abstract A novel two‐element, catheter‐based phased array coil was designed and built for both active MR device tracking high‐resolution vessel wall imaging. The consists of two independent solenoid coils that are wound in opposite directions, connected to separate receive channels, mounted collinearly on an angiographic catheter. elements were used independently or together imaging applications, respectively. array's dual functionality tested a clinical 1.5 T MRI scanner vitro, vivo, situ....

Abstract Multislice parallel imaging involves the simultaneous sampling of multiple slices which are subsequently separated using reconstruction. The CAIPIRINHA technique improves this reconstruction by manipulating phase RF excitation pulses to shift aliasing pattern such that there is less energy be reconstructed. In work, it shown combining manipulation used in with a non‐Cartesian (radial) scheme further decreases for algorithm reconstruct, thereby increasing degree multi‐channel...

A three-dimensional (3D) mutual information registration method was created and used to register MRI volumes of the pelvis prostate. It had special features improve robustness. First, it a multi-resolution approach performed from low high resolution. Second, two similarity measures, correlation coefficient at lower resolutions full resolution, because their particular advantages. Third, we avoid local minima by restarting with randomly perturbed parameters. The criterion for below an...

Abstract The purpose of this study was to determine the suitability MRI accurately detect radiofrequency (RF) thermoablative lesions created under MR guidance. In vivo RF were in livers six New Zealand White rabbits using a 2‐mm‐diameter titanium alloy electrode with 20‐mm exposed tip and 50‐W generator. This performed 0.2T clinical C‐arm imager for guidance monitoring. Each animal sacrificed gross evaluation performed. Histologic correlation on first two animals. MR‐compatible easily...

Abstract Radiofrequency (RF) energy has many advantages in thermal tumor ablation protocols. With the recent development of open MRI systems, interventional procedures, including ablation, have become focus great research interest. However, significant interference between RF generators and MR imagers prevented simultaneous imaging and, until now, limited role RF‐based therapy MRI. Here, a simple switching circuit designed with consideration patient safety provides compatibility systems...

PURPOSE: To test the hypotheses that (a) magnetic resonance (MR) imaging–guided radio-frequency (RF) thermal ablation of vertebrae is feasible in porcine models, (b) procedure safety depends on location within vertebra, and (c) MR imaging allows accurate monitoring induced lesion size shape. MATERIALS AND METHODS: Ten percutaneous RF ablations were randomized over various lumbar vertebral levels locations seven pigs. Animals followed up for 2, 7, or 14 days before sacrifice. Thermal shape as...

Abstract Previous work has shown that the use of radial GRAPPA for reconstruction undersampled real‐time free‐breathing cardiac data allows frame rates up to 30 images/s. It is well known spiral trajectory offers a higher scan efficiency compared trajectories. For this reason, we have developed novel through‐time method and demonstrate its application imaging. By moving from trajectory, temporal resolution can be further improved at lower acceleration factors GRAPPA. In addition, image...

Abstract Functional MR (fMR) has been useful in providing insight into the localization and detection of neural cortical activity. However, patient head motion is inevitable over course most fMR experiments. Although methods to align control activation images may correct for some this motional error, they will be incomplete correcting those that depend on spatial orientation. signal amplitude structures lie along air‐tissue interfaces, example, are sensitive susceptibility errors introduced...

A new optical method of detuning parallel resonant circuits is described. This involves the integration a photoresistor in with inductor and capacitor circuit, this case magnetic resonance imaging (MRI) receiver coil. fiberoptic cable extending length interventional device used conjunction an external light source to deliver photoresistor. Exposing changes its bulk resistance greatly lowers Q effectively it. By combining scheme inductive coupling device-mounted microcoils standard MRI coil,...