Kalman filter-based EM-optical sensor fusion for needle deflection estimation.

Purpose: In many clinical procedures such as cryoablation that involves needle insertion, accurate placement of the needle's tip at the desired target is the major issue for optimizing the treatment and minimizing damage to the neighboring anatomy. However, due to the interaction force between the needle and tissue, considerable error in intraoperative tracking of the needle tip can be observed as needle deflects.

Methods: In this paper, measurements data from an optical sensor at the needle base and a magnetic resonance (MR) gradient field-driven electromagnetic (EM) sensor placed 10 cm from the needle tip are used within a model-integrated Kalman filter-based sensor fusion scheme.

Real-time probe tracking using EM-optical sensor for MRI-guided cryoablation.

Background: A method of real-time, accurate probe tracking at the entrance of the MRI bore is developed, which, fused with pre-procedural MR images, will enable clinicians to perform cryoablation efficiently in a large workspace with image guidance.

Methods: Electromagnetic (EM) tracking coupled with optical tracking is used to track the probe. EM tracking is achieved with an MRI-safe EM sensor working under the scanner's magnetic field to compensate the line-of-sight issue of optical tracking.

Wall suction-assisted image-guided therapeutic paracentesis: a safe and less expensive alternative to evacuated bottles.

Objective: To assess the safety and cost savings of using wall suction and plastic canisters instead of evacuated bottles, currently in short supply, to drain, and collect large amounts of fluid during image-guided paracentesis procedures.

Materials And Methods: In a hospital-based practice, 551 image-guided paracenteses were performed in 191 consecutive patients over a 10-month period, using wall suction to facilitate drainage. Total volume of fluid removed and complications were recorded.

Magnetic Resonance Imaging-Guided Breast Interventions: Role in Biopsy Targeting and Lumpectomies.

Contrast-enhanced breast MR imaging is increasingly being used to diagnose breast cancer and to perform biopsy procedures. The American Cancer Society has advised women at high risk for breast cancer to have breast MR imaging screening as an adjunct to screening mammography. This article places special emphasis on biopsy and operative planning involving MR imaging and reviews use of breast MR imaging in monitoring response to neoadjuvant chemotherapy.

CT-guided conformal cryoablation for peripheral NSCLC: initial experience.

Purpose: To study the feasibility of CT-guided and monitored percutaneous conformal cryoablation of Non-Small Cell Lung Cancer for patients who are not suitable for surgical resection.

Materials And Method: CT-guided percutaneous conformal cryoablation was performed on 46 patients with peripheral Non-Small Cell Lung Cancer. Patients with tumor sizes less than 3 cm in diameter were treated with double-needle clamping cryoablation, while the patients with 3-5 cm tumor sizes were treated with multiple-needle conformal cryoablation.

Brava and autologous fat transfer is a safe and effective breast augmentation alternative: results of a 6-year, 81-patient, prospective multicenter study.

Background: Breast augmentation by autologous fat transfer is an appealing alternative in need of scientific validation.

Methods: In a prospective multicenter study, 81 women (age range, 17 to 63 years) wore the Brava device, a bra-like vacuum-based external tissue expander, for 4 weeks and then underwent autologous fat injection using 10 to 14 needle puncture sites into each breast in a three-dimensional fanning pattern (average, 277 ml volume injected per breast). Patients resumed Brava wear within 24 hours for 7 or more days.

High-resolution magnetic resonance imaging enhanced with superparamagnetic nanoparticles measures macrophage burden in atherosclerosis.

Background: Macrophages contribute to the progression and acute complications of atherosclerosis. Macrophage imaging may serve as a biomarker to identify subclinical inflamed lesions, to predict future risk, and to aid in the assessment of novel therapies.

Methods And Results: To test the hypothesis that nanoparticle-enhanced, high-resolution magnetic resonance imaging (MRI) can measure plaque macrophage accumulation, we used 3-T MRI with a macrophage-targeted superparamagnetic nanoparticle preparation (monocrystalline iron oxide nanoparticles-47 [MION-47]) in cholesterol-fed New Zealand White rabbits 6 months after balloon injury.

MRI findings in injured articular cartilage of the knee correlated with surgical findings.

Background: There is a strong need for quick noninvasive diagnostic technique that can give a valid estimate of the status of the cartilage reliably, discriminating intact cartilage from various grades of impaired cartilage. The goal of this study was to assess the incidence of knee cartilage injuries and compare the accuracy of two-dimension spin echo (2D SE) and fast spin echo (FSE) (conventional MRI), three-dimensional spoiled gradient echo (3D SPGR), three-dimensional fast imaging employing steady state acquisition (3D FIESTA) MR imaging sequences with surgical examination of the articular cartilage.

Methods: One hundred and thirty-eight knees with history of knee trauma received conventional MRI, 3D SPGR and 3D FIESTA MRI examination before surgery, and surgical examination of articular cartilage was used as reference standard.

Negative pressure fixation device to reduce motion artifacts on contrast-enhanced MRI of the breast: a clinical feasibility study.

Purpose: To investigate the effect of a negative pressure fixation device on misregistration artifacts in contrast-enhanced (CE) MR subtraction images.

Materials And Methods: Nine patients, two of which had been previously diagnosed with breast cancer, were examined with T2-weighted (T2-w) turbo spin-echo (TSE) and three-dimensional (3D) spoiled gradient-recalled echo (SPGR) CE dynamic MRI. Baselines images were subtracted from the dynamic images.

Simultaneous ultrasound and MRI system for breast biopsy: compatibility assessment and demonstration in a dual modality phantom.

Simultaneous capturing of ultrasound (US) and magnetic resonance (MR) images allows fusion of information obtained from both modalities. We propose an MR-compatible US system where MR images are acquired in a known orientation with respect to the US imaging plane and concurrent real-time imaging can be achieved. Compatibility of the two imaging devices is a major issue in the physical setup.

Multi-modal imaging: simultaneous MRI and ultrasound imaging for carotid arteries visualization.

The purpose of this study is to examine the feasibility of simultaneous Magnetic Resonance Imaging (MRI) and Ultrasound (US) imaging in visualizing anatomical structures and functions in human carotid arteries. US has high frame rate in visualizing dynamic changes while high resolution MRI is capable of capturing volumetric structures with the best tissue contrast. Concurrent multi-modal image acquisition allows fusion of US Doppler flow measurement with volumetric MRI.

Breast focused ultrasound surgery with magnetic resonance guidance.

This paper will review the experience and current applications of magnetic resonance-guided focused ultrasound surgery (MRgFUS) for treatment of breast tumors. Because of the efficient screening mammography programs, most of the breast cancers diagnosed today in the United States and European Union are in early stage and are treated with limited surgery. The MRgFUS may offer an alternative treatment option to conventional surgical lumpectomy with the advantage of being a noninvasive procedure and potentially achieving a better cosmetic outcome.

Improved characterization of atherosclerotic plaques by gadolinium contrast during intravascular magnetic resonance imaging of human arteries.

Objectives: To determine whether gadolinium-DTPA (Gd-DTPA) facilitates discrimination of fibrous, lipid or calcified constituents during intravascular magnetic resonance imaging (IVMRI) of human atherosclerotic arteries.

Background: Atherosclerotic plaques that cause fatal thrombosis due to rupture have high content of lipid relative to fibrous tissue. We recently demonstrated that IVMRI identifies lipid, fibrous, and calcified components within atherosclerotic human arteries with favorable sensitivity and specificity.

Intraoperative and interventional MRI: recommendations for a safe environment.

In this paper we report on current experience and review magnetic resonance safety protocols and literature in order to define practices surrounding MRI-guided interventional and surgical procedures. Direct experience, the American College of Radiology White paper on MR Safety, and various other sources are summarized. Additional recommendations for interventional and surgical MRI-guided procedures cover suite location/layout, accessibility, safety policy, personnel training, and MRI compatibility issues.

DuraSeal magnetic resonance and computed tomography imaging: evaluation in a canine craniotomy model.

Objective: Several novel sealing materials have been proposed as an adjunct to sutured dural closure to help insure watertight closure, thus diminishing the risk of pseudomeningocele formation. This evaluation was undertaken to clarify the in vivo magnetic resonance imaging (MRI) and computed tomographic (CT) scan characteristics of one such sealant, which has a high water content, permitting similar imaging characteristics to pseudomeningoceles and inflammatory collections.

Methods: After a craniotomy in two canine subjects, we sprayed a novel, water-soluble, self-polymerizing, absorbable, hydrogel sealant onto the dura and the bone flap was replaced.

Characterization of human atherosclerotic plaques by intravascular magnetic resonance imaging.

Background: Development and validation of novel imaging modalities to assess the composition of human atherosclerotic plaques will improve the understanding of atheroma evolution and could facilitate evaluation of therapeutic strategies for plaque modification. Surface MRI can characterize tissue content of carotid but not deeper arteries. This study evaluated the usefulness of intravascular MRI (IVMRI) to discern the composition of human iliac arteries in vivo.

On the strong field dependence and nonlinear response to gadolinium contrast agent of proton transverse relaxation rates in dairy cream.

Dairy cream, as a suspension of lipid droplets in water, is a potentially useful magnetic resonance imaging (MRI) phantom material and an interesting material for studying fundamental relaxation mechanisms. Here we report a strong increase in the transverse relaxation rates with field strength for both the water and lipid protons in dairy cream. Also, studies at 4.

MR imaging--guided breast ablative therapy.

The integration of imaging and thermal therapy can provide a minimally invasive or even noninvasive alternative to breast surgery for small tumors. Ongoing trials seek to show safety and efficacy for laser, radiofrequency, microwave, cryoablation, and focused ultrasound surgery. To be successful, these therapies must achieve equivalent or even greater efficacy as surgical outcomes and must demonstrate total ablation of the dominant lesion with negative margins, while sparing normal tissue beyond the target tissue.

Superconducting RF coils for clinical MR imaging at low field.

Rationale And Objectives: A number of recent reports in the MRI literature have established that substantial signal-to-noise ratio (SNR) gains can be achieved with small samples or low resonance frequencies, through the use of high-quality factor high-temperature superconducting (HTS) RF receive coils. We show the application of HTS coils to the imaging of human subjects with improved SNR compared with copper coils.

Materials And Methods: HTS coils were constructed from 7.

Late genitourinary and gastrointestinal toxicity after magnetic resonance image-guided prostate brachytherapy with or without neoadjuvant external beam radiation therapy.

Background: This study was designed to estimate the rates of late genitourinary (GU) and rectal toxicity after magnetic resonance image (MRI)-guided prostate brachytherapy exclusively or in conjunction with external beam radiation therapy (EBRT).

Methods: Between November 1997 and April 2002, 201 patients with category T1C prostate carcinoma (according to the 2002 American Joint Committee on Cancer staging criteria), prostate specific antigen levels < 10 ng/mL, and biopsy Gleason score 3 + 4 disease were treated with MRI-guided brachytherapy exclusively or in conjunction with EBRT. The MRI-guided technique was designed to spare the urethra based on delivery of the prescription dose to the peripheral zone exclusively.

Intraoperative magnetic resonance imaging and magnetic resonance imaging-guided therapy for brain tumors.

Since their introduction into surgical practice in the mid 1990s, intraoperative MRI systems have evolved into essential, routinely used tools for the surgical treatment of brain tumors in many centers. Clear delineation of the lesion, "under-the-surface" vision, and the possibility of obtaining real-time feedback on the extent of resection and the position of residual tumor tissue (which may change during surgery due to "brain-shift") are the main strengths of this method. High-performance computing has further extended the capabilities of intraoperative MRI systems, opening the way for using multimodal information and 3D anatomical reconstructions, which can be updated in "near real time.

Feasibility of MR imaging-guided breast lumpectomy for malignant tumors in a 0.5-T open-configuration MR imaging system.

Rationale And Objectives: The authors performed this study to develop the technology for and evaluate the utility of a 0.5-T vertical open-configuration magnetic resonance (MR) imaging system for imaging-guided breast lumpectomy of malignant tumors.

Materials And Methods: Twenty women with breast cancer underwent MR imaging-guided lumpectomy in a 0.