Patient anesthesia and monitoring at a 1.5-T MRI installation

Wireless video transmission into the MRI magnet room: implementation and evaluation at 1.5T, 3T and 7T

Purpose To analyze the interference between a wireless high definition multimedia interface (WHDMI) and magnetic resonance imaging (MRI) image quality at 1.5T, 3T and 7T. Materials and methods A wireless video transmission system (WVTS) consisting of a WHDMI and a projector was used to transmit and display a video stream into the magnet room. MR image quality was analyzed at 1.5T, 3T and 7T. Signal-to-noise-ratio (SNR¯) $(\overline {{\rm{SNR}}} )$ and radio frequency (RF)-noise spectrum were measured at three transmitter positions (A: inside the cabin, B: in front of the waveguide and C: in the control room). WVTS system functionality tests included measurements of reliability, delay and image quality. Results With the WVTS mean SNR¯ $\overline {{\rm{SNR}}} $ values significantly decreased in comparison to the reference for all positions and fieldstrenghts, while the spectra's baseline is elevated at 1.5T and 3T. Peaks related to continuous wave interferences are apparent at all field strenghts. For WHDMI alone mean SNR¯ $\overline {{\rm{SNR}}} $ values were stable without significant differences to the reference. No elevation of the spectra's baseline could be observed. Functionality measurements confirmed high connection reliability with stable image quality and no delays for all field strengths. Conclusion We conclude that wireless transmission of video streams into the MRI magnet room is feasible at all field strengths without hampering image quality.

Complications during intrahospital transport of critically ill patients: Focus on risk identification and prevention

Intrahospital transportation of critically ill patients is associated with significant complications. In order to reduce overall risk to the patient, such transports should well organized, efficient, and accompanied by the proper monitoring, equipment, and personnel. Protocols and guidelines for patient transfers should be utilized universally across all healthcare facilities. Care delivered during transport and at the site of diagnostic testing or procedure should be equivalent to the level of care provided in the originating environment. Here we review the most common problems encountered during transport in the hospital setting, including various associated adverse outcomes. Our objective is to make medical practitioners, nurses, and ancillary health care personnel more aware of the potential for various complications that may occur during patient movement from the intensive care unit to other locations within a healthcare facility, focusing on risk reduction and preventive strategies.

Neuroinformatics challenges to the structural, connectomic, functional and electrophysiological multimodal imaging of human traumatic brain injury

Throughout the past few decades, the ability to treat and rehabilitate traumatic brain injury (TBI) patients has become critically reliant upon the use of neuroimaging to acquire adequate knowledge of injury-related effects upon brain function and recovery. As a result, the need for TBI neuroimaging analysis methods has increased in recent years due to the recognition that spatiotemporal computational analyses of TBI evolution are useful for capturing the effects of TBI dynamics. At the same time, however, the advent of such methods has brought about the need to analyze, manage, and integrate TBI neuroimaging data using informatically inspired approaches which can take full advantage of their large dimensionality and informational complexity. Given this perspective, we here discuss the neuroinformatics challenges for TBI neuroimaging analysis in the context of structural, connectivity, and functional paradigms. Within each of these, the availability of a wide range of neuroimaging modalities can be leveraged to fully understand the heterogeneity of TBI pathology; consequently, large-scale computer hardware resources and next-generation processing software are often required for efficient data storage, management, and analysis of TBI neuroimaging data. However, each of these paradigms poses challenges in the context of informatics such that the ability to address them is critical for augmenting current capabilities to perform neuroimaging analysis of TBI and to improve therapeutic efficacy.

Intraoperative magnetic resonance imaging in neurosurgery: the Brigham concept

The resection of brain tumors is limited by the surgeon's ability to precisely define margins. To overcome this problem, various neuronavigational tools have been used. The development of image-guided navigation systems represents a substantial improvement in the microsurgical treatment of various intracranial lesions. However, a major drawback of this technology is that they use images acquired preoperatively, on which the surgical planning and intraoperative performance is based. As the intracranial anatomy dynamically changes during a neurosurgical procedure, only intraoperatively acquired images can provide the neurosurgeon with the information needed to perform real-time, image-guided surgery. Because magnetic resonance imaging best delineates the soft-tissue extent of most tumors, it currently remains the superior method for intraoperative image guidance. In this review, we outline the development as well as current and possible future applications of the intraoperative MRI (iMRI) unit at the Brigham and Women's Hospital, Boston, MA.

Magnetic resonance imaging of soft-tissue tumors in children

Magnetic resonance imaging (MRI) has become an important diagnostic tool in the detection and characterization and local anatomic staging of soft-tissue tumors in children. This article outlines some of the procedural issues unique to the pediatric population.

A new frontier: magnetic resonance imaging-operating room

Developments in technology have led to the merger of two distinct environments, that of magnetic resonance imaging and that of the operating room. The major advantage of this merger for neurosurgical procedures is the ability to perform real-time imaging to help guide surgery. This review discusses the role of the anesthesiologist in the planning and administration of safe anesthesia in this new and challenging environment.

Intraoperative MR imaging guidance for intracranial neurosurgery: experience with the first 200 cases

PURPOSE

To review preliminary experience with an open-bore magnetic resonance (MR) imaging system for guidance in intracranial surgical procedures.

MATERIALS AND METHODS

A vertically oriented, open-configuration 0.5-T MR imager was housed in a sterile procedure room. Receive and transmit surface coils were wrapped around the patient's head, and images were displayed on monitors mounted in the gap of the magnet and visible to surgeons. During 2 years, 200 intracranial procedures were performed.

RESULTS

There were 111 craniotomies, 68 biopsies, 12 intracranial cyst evaluations, four subdural drainages, and five transsphenoidal pituitary resections performed with the intraoperative MR unit. In each case, the intraoperative MR system yielded satisfactory results by allowing the radiologist to guide surgeons toward lesions and to assist in treatment. In two patients, hyperacute hemorrhage was noted and removed. The duration of the procedure and the complication rate were similar to those of conventional surgery.

CONCLUSION

Intraoperative MR imaging was successfully implemented for a variety of intracranial procedures and provided continuous visual feedback, which can be helpful in all stages of neurosurgical intervention without affecting the duration of the procedure or the incidence of complications. This system has potential advantages over conventional frame-based and frameless stereotactic procedures with respect to the safety and effectiveness of neurosurgical interventions.

A simple MR-compatible infusion pump

A simple, mechanical infusion pump that employs a constant force, nonferromagnetic spring to squeeze a syringe is described. The contrast infusion rate is determined by the spring force, gadolinium solution viscosity, and the resistance of either a user-selected needle or a precision oriffice according to Poiseuille's Law or the Bernoulli effect. Its use in dynamic, gadolinium-enhanced 3D MR angiography is described.

Sedation, anesthesia, and physiologic monitoring during MR imaging: evaluation of procedures and equipment

The authors developed safe standard sedation and general anesthesia procedures for adults and children, including adequate physiologic monitoring, during magnetic resonance (MR) imaging. Six-year results are reported from one institution; 75% of the 600 patients per year who require sedation or anesthesia are children who require sedation only. Testing was done to determine MR compatibility of various types of equipment essential for monitoring and supporting sedated or anesthetized patients in 1.0- and 1.5-T MR imagers. Use of sedation procedures that include oral chloral hydrate after sleep deprivation resulted in a failure rate of 3.8% in sedating outpatient children. Every physiologic parameter that can be monitored under normal circumstances in the critical care unit or operating room can be monitored during MR imaging. Our experience indicates that with careful consideration of the unique MR environment and with rigorous testing of monitoring equipment, MR imaging can be performed safely in sedated or anesthetized patients.

Magnetic resonance for the anaesthetist. Part II: Anaesthesia and monitoring in MR units

Anaesthetists are increasingly involved in patient care during magnetic resonance imaging and spectroscopy. This paper describes a system which has been developed for the management of critically ill patients and the conduct of anaesthesia in a magnetic resonance unit with a 1.6 tesla whole body magnet. Difficulties which arise from working in a confined space in a high magnetic field are highlighted. Different approaches to anaesthesia, sedation and the modification of equipment for use in this environment are reviewed. The problems associated with patient monitoring within a magnetic field are discussed and some solutions are suggested. A transport system for critically ill patients is described and a protocol for management is outlined.

Policies, guidelines, and recommendations for MR imaging safety and patient management. SMRI Safety Committee

The following are policies, guidelines, and recommendations from the Safety Committee of the Society for Magnetic Resonance Imaging (SMRI) concerning various issues related to magnetic resonance (MR) imaging safety and patient management. These policies, guidelines, and recommendations were developed to provide standardized and consistent information for use by health practitioners involved in clinical MR imaging.

Magnetic resonance for the anaesthetist. Part I: Physical principles, applications, safety aspects

Anaesthetists are being increasingly involved in magnetic resonance (MR) procedures, both in patient care and as a research tool. This paper outlines the physical basis of nuclear magnetic resonance and describes its application in magnetic resonance imaging and spectroscopy. Principles of magnet design and safety relevant to anaesthetic practice in a magnetic resonance environment are discussed and guidelines for anaesthetic practice suggested. Some recent clinical magnetic resonance studies of anaesthetic interest are reviewed.

Nuclear magnetic resonance in clinical pharmacology and measurement of therapeutic response

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