Biomagnetic Imaging Research Articles

Estimation of Electrical Source Localization Using the Temporal Correlation between Magnetic Field Measurements

It is well known that an inverse problem of biomagnetic imaging is generally ill-posed. Recently several attempts using biocoherence have been reported, but the ill-condition is not considered in these previous methods. If the conventional reconstruction formula is under the ill-condition, the reconstruction problem is also ill-posed and the ill-posedness cannot be improved. In this paper, we propose an approach to estimate the location of current sources under the condition that sources of different positions have little or weak correlation. Our method is based on a well-known regularization method, the truncated SVD method. Compared with the conventional method, our technique allows accurate determination of the location of current sources because it improves the ill-posedness of the inverse problem. We carried out computer simulations using the half-space conducting model and confirmed the effectiveness of our method.

Intracranial neurosurgery guided by functional imaging

Neurosurgery on eloquent cortex entails important risks of functional deficits complicating aggressive lesion resection. In this study, advanced biomagnetic functional imaging of somatosensory and motor cortex combined with surface rendered magnetic resonance imaging displays including vascular anatomy were used in conjunction with a new nonintrusive intraoperative guided instrumentation system to resect a tumor in eloquent cortex. Intraoperative verification of the accuracy of pre-operative motor localization demonstrated highly accurate results comparing direct stimulation and noninvasive presurgical mapping. The applicability of surface rendered combined functional and anatomic maps of cortex is directly evident on comparison of preoperative computer images and intraoperative pictures. This combination of new technologies has a significant potential for reduced risk and improved outcome in neurosurgery of eloquent cortex.

A 31-channel squid system for biomagnetic imaging

A modular multichannel SQUID-system, in which every single channel can be optimized or replaced individually, is presented. The DC-SQUIDs based on the materials NbN/MgO are prepared by thin film technology and show noise values below 10μΦ0/√Hz. A simplified way of coupling the modulation and feedback current directly to the coupling coil is realized The complete SQUID module including the superconducting shield was miniaturized down to a diameter of 5mm. The gradiometers are wire wound and an as made balancing better than 10−3 is achieved. The cryogenic system was optimized with respect to low vibrations and low helium boil off rate. Simple conductive paint with precisely adjusted surface resistivity is used for RF-shielding. The complete SQUID-electronic of one channel has been realized on one single board and uses a new bias modulation scheme to completely suppress intrinsic 1/f noise. The noise level of the complete system is below 10fT/√Hz. Biomagnetic measurements of the human heart and brain are presented. Single current dipole reconstructions and current density imaging techniques can be used to find the underlying sources. Using a special coil positioning system an overlay of the functional current images with morphological MR-images can be carried out.

Programme of the international workshop on non pharmacological treatment of cardiac arrhythmias: present and future. A potential application for biomagnetic imaging, Rome (Italy), December 9–11, 1990

Programme of the international workshop on non pharmacological treatment of cardiac arrhythmias: present and future. A potential application for biomagnetic imaging, Rome (Italy), December 9–11, 1990

Tikhonov regularisation approach to dynamic biomagnetic imaging

We describe a method of identifying the distributed sources associated with biomagnetic data sets. The technique is based on Tikhonov regularisation. An algorithm has been implemented in FORTRAN on a PC/AT computer. Its predictions are stable with respect to measurement noise.

Technology 1991: medical electronics

1990 saw major advances in medical technology. A combination of technological advances in magnetic resonance imaging (MRI) is unveiling new horizons for brain surgery, providing real-time feedback in the operating room. Computer-based stereotaxic techniques are being used experimentally in surgery, and experiments with robotic surgery are underway. In other developments, a variation on MRI, magnetic resonance spectroscopy, was shown to diagnose coronary artery disease accurately, ultrasonic imaging of blood flow received renewed attention, interest in biomagnetic imaging continued to grow and research cast further doubt on the efficacy of gallstone lithotripsy.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Biomagnetometry provides a new compass for exploring the brain and heart

AMONG more than 1400 papers presented at 75th Scientific Assembly and Annual Meeting of Radiological Society of North America (RSNA), there was only one on biomagnetic imaging. Nevertheless, in opinion of a number of radiologists there—including Derek Harwood-Nash, MD, who is RSNA's program committee chair— this fledgling field is one of most exciting areas in radiology today, with many potential diagnostic applications in cardiology, neurology, and psychiatry. At next few gatherings of the world's largest medical meeting, he expects to see many more papers on biomagnetic imaging that should provide a clearer view of what this latest round of ultra-high technology (and ultra-high cost) imaging can do for biomedical research and patient care. Detailing Electrical Activity Unlike ultrasound, computed tomography, and magnetic resonance imaging (MRI) scans (which provide anatomic information) and positron emission tomography and single-photon computed tomography scans (which show metabolic information),

Biomagnetometry Provides a New Compass for Exploring the Brain and Heart

AMONG the more than 1400 papers presented at the 75th Scientific Assembly and Annual Meeting of the Radiological Society of North America (RSNA), there was only one on biomagnetic imaging. Nevertheless, in the opinion of a number of radiologists there—including Derek Harwood-Nash, MD, who is the RSNA's program committee chair— this fledgling field is one of the most exciting areas in radiology today, with many potential diagnostic applications in cardiology, neurology, and psychiatry. At the next few gatherings of "the world's largest medical meeting," he expects to see many more papers on biomagnetic imaging that should provide a clearer view of what this latest round of ultra-high technology (and ultra-high cost) imaging can do for biomedical research and patient care. <h3>Detailing Electrical Activity</h3> Unlike ultrasound, computed tomography, and magnetic resonance imaging (MRI) scans (which provide anatomic information) and positron emission tomography and single-photon computed tomography scans (which show metabolic information),

A Non-Magnetic, MR-Compatible Pacing Catheter for Clinical Application in Magnetocardiography

A special bipolar pacing catheter for use in magnetocardiographic investigations has been developed. Several investigations have shown that it is fully compatible to both biomagnetic and MR imaging and thus serves as an ideal reference point for intracardial stimulation in magnetocardiography.