Article Magnetische Resonanztomographie bei Patienten mit metallischen Implantaten was published on January 1, 1988 in the journal Biomedical Engineering / Biomedizinische Technik (volume 33, issue s2).

The magnetic fields caused by electrical activity of the human heart can be coherently measured with a highly sensitive, multichannel, superconducting quantum interference-device system and can enable noninvasive localization of the underlying electrical activity. The magnetocardiograms (MCGs) of 10 patients with spontaneous premature ventricular complexes (PVCs), three patients with ventricular tachycardia (VT), and four healthy subjects with induced paced beats were recorded for 2-15 minutes. After correction for superimposed repolarization activity, the site of origin of the arrhythmias was localized from the magnetic field distribution at the onset of the ectopic beats. The localization results of paced beats showed an error of a few millimeters in relation to the position of the catheter tip. The results of spontaneous PVC and VT were confirmed with endocardial mapping or associated with ischemic lesions. The authors conclude that multichannel magnetocardiographic studies enable the completely noninvasive localization of ventricular arrhythmias.

This study presents the results of in-vitro and clinical experiences with metallic implants during MRT investigations. In-vitro temperature measurements of various implants showed little temperature rise depending on the shape and the orientation in the static magnetic field (max. 0.3-degrees-C). Ferromagnetic forces could not be detected with these implants. In contrast, severe temperature increase (9.4-degrees-C) was observed with an intratracheal spiral tube. Tubes of this type should not be used in MR imaging to avoid the risk of burning. 105 MR examinations were performed in patients with metallic implants (CNS shunts, aortocoronary bypass grafts, aortic-, mitral-prosthesis, orthopedic implants, skin staples, shrapnels). Patients with vascular clips were accepted for MR imaging when the clips were nonferromagnetic only. No adverse effects were observed in these patients.

Concerning the path genetic mechanism of idiopathic long QT syndrome (LQTS), the hypothesis of a specific sympathetic imbalance has gained general acceptance, but its validity has never been proven. To test this hypothesis I‐123‐MIBG, an analogue of norepinephrine and guanethi‐dine, was used to provide scinfigraphic display of the efferent cardiac sympathetic innervation. Twelve members of four LQTS families fmean age 38.2 ± 17.2 years, eight males) and eight healthy volunteers (mean age 48.2 ± 13.3 years, five males) were studied by means of M23‐MTBG single photon emission computed tomography (SPECT). A quantitative analysis of all scans was performed. All scans of the healthy volunteers show a uniform tracer uptake with sometimes slightly decreased activity in the apex. (1) All patients with QT c > 440 msec (n = 5); (2) all, who had suffered from at least one episode of torsade de pointes, ventricular fibrillation (VF) or syncope (n = 5); and (3) all symptomatic patients with QTc prolongation (n = 4) have reduced or abolished (P < 0.02) MIBG uptakes in the inferior and inferior septal parts of the left ventricle (congenital myocardial sympathetic disintegration [CMSD]). Additionally, one female without symptoms or QT C prolongation (LQT) shows an abnormal MIBG SPECT similar to the one of her daughter, who has LQT and symptoms. One male without LQT, who had suffered from VF shows CMSD similar to his father, who has LQT, but no symptoms. All members of the families with normal MIBG SPECTs have neither LQT nor symptoms. In all families CMSD fulfills the criteria of autonomic‐dominant inheritance. Normal QT c ‐interval predicted only in 57% normal cardiac sympathetic enervation in the present LQTS families. Therefore, quantitative I‐123‐MIBG SPECT enables to identify myocardial sympathetic disintegration as structural defect in LQTS. CMSD is associated with and without LQT and presents a pattern of autosomal‐dominant inheritance. LQT at rest or during exercise was specific (100%). but less sensitive (63%) in the assessment of CMSD than I‐123‐MIBG SPECT.

In this work, the technique of P-31-NMR-spectroscopy is applied for the first time to diagnose coronary heart disease in patients, using a suitable measuring technique.In 13 healthy volunteers we applied a method comfortable and tolerable for patients, which enabled us to examine the myocardium inside the reception area of a surface coil. Concerning myocardium-specific selectivity and sensitivity the localization techniques FROGS (Fast-ROtating-Gradient-Spectroscopy), 1-D-ISIS (1-Dimensional-Image-Selected-In-vivo-Spectroscopy) and 3-D-ISIS were compared. By a combination of the 3-D-ISIS-technique with magnetic resonance imaging, we obtained a monitored position of the volume of interest (VOI) within the myocardium, thus gaining a selective measurement. The cube-shaped VOI with a lateral length of 50 mm was placed into the apical-septal area of the myocardium.On the basis of the obtained results, we examined seven patients suffering from coronary heart disease, which was symptomatic and verified by coronary angiography.The P-31-NMR-spectra of the two examined groups were computed into numbers representing the relative content of the myocardial high-energy-phosphates. In addition, the quotients PCr/ATP and P(i)/ATP were calculated and compared.With this small number of cases the evaluation of the PCr/ATP-ratios already showed a significant difference of 0.34 (p < 0.01) between patients with coronary heart disease (0.49 +/- 0.19) and healthy volunteers (0.83 +/- 0.27).The findings suggest the conclusion that P-31-NMR-spectroscopy is able to be instrumental in the diagnostic detection assessment of the metabolic state in coronary heart disease.Being non-invasive and free of x-rays, the method represents only little physical and psychical stress for the patient and, in this respect, is an ideal supplement to coronary angiography, myocardium perfused nuclear scanning, and similar investigation techniques.

Magnetocardiography is a non-invasive biomagnetic technique for measuring magnetic fields produced at the surface of the body when the heart is stimulated to beat. The measurement is contact-free and is independent of tissue resistance. For the first time, magnetocardiography employing multi-channel systems permits the accurate, non-invasive localization of accessory conduction pathways and ectopic ventricular activity.

This study presents the results of in-vitro and clinical experiences with metallic implants during MRT investigations. In-vitro temperature measurements of various implants showed little temperature rise depending on the shape and the orientation in the static magnetic field (max. 0.3 degrees C). Ferromagnetic forces could not be detected with these implants. In contrast, severe temperature increase (9.4 degrees C) was observed with an intratracheal spiral tube. Tubes of this type should not be used in MR imaging to avoid the risk of burning. 105 MR examinations were performed in patients with metallic implants (CNS shunts, aortocoronary bypass grafts, aortic-, mitral-prosthesis, orthopedic implants, skin staples, shrapnels). Patients with vascular clips were accepted for MR imaging when the clips were non-ferromagnetic only. No adverse effects were observed in these patients.

In this work, the technique of 31P-NMR-spectroscopy is applied for the first time to diagnose coronary heart disease in patients, using a suitable measuring technique. In 13 healthy volunteers we applied a method comfortable and tolerable for patients, which enabled us to examine the myocardium inside the reception area of a surface coil. Concerning myocardium-specific selectivity and sensitivity the localization techniques FROGS (Fast-ROtating-Gradient-Spectroscopy), 1-D-ISIS (1-Dimensional-Image-Selected-In-vivo-Spectroscopy) and 3-D-ISIS were compared. By a combination of the 3-D-ISIS-technique with magnetic resonance imaging, we obtained a monitored position of the volume of interest (VOI) within the myocardium, thus gaining a selective measurement. The cube-shaped VOI with a lateral length of 50 mm was placed into the apical-septal area of the myocardium. On the basis of the obtained results, we examined seven patients suffering from coronary heart disease, which was symptomatic and verified by coronary angiography. The 31P-NMR-spectra of the two examined groups were computed into numbers representing the relative content of the myocardial high-energy-phosphates. In addition, the quotients PCr/ATP and Pi/ATP were calculated and compared. With this small number of cases the evaluation of the PCr/ATP-ratios already showed a significant difference of 0.34 (p less than 0.01) between patients with coronary heart disease (0.49 +/- 0.19) and healthy volunteers (0.83 +/- 0.27). The findings suggest the conclusion that 31P-NMR-spectroscopy is able to be instrumental in the diagnostic detection assessment of the metabolic state in coronary heart disease.(ABSTRACT TRUNCATED AT 250 WORDS)

A method has been developed to eliminate disturbing magnetic signals in the biomagnetic localization of arrhythmogenic sources in the heart. The procedure consists of two steps: Superimposed background activity of the heart is eliminated by subtraction of a template of pure background activity. Systematic and electronic offset is subsequently eliminated by baseline-correction during periods of zero activity. The method was applied to several kinds of arrhythmias. It was demonstrated that elimination of background activity is the prerequesite for exact localization and that the proposed procedure yields correct results.

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.

The authors designed a multichannel system for noninvasive measurement of the extremely weak magnetic fields generated by the brain and the heart. It uses a flat array of 37 superconducting magnetic field-sensing coils connected to sophisticated superconducting quantum interference devices. To prevent interference from external electromagnetic fields, the system is operated inside a shielded room. Complete sets of coherent data, even from spontaneous events, can be recorded. System performance was evaluated with phantom measurements and evoked-response studies. A spatial resolution of a few millimeters and a temporal resolution of a millisecond were obtained. First results in patients with partial epilepsy and investigations of the cardiac conductive pathway indicate that biomagnetism is now ready for a systematic clinical evaluation. Interpretation of measurements was facilitated by highlighting biomagnetically localized electrical activity in three-dimensional digital magnetic resonance images.

Article Magnetokardiographie (MKG): Technischer Fortschritt durch ein Vielkanal-SQUID-System. Klinische Anwendung bei Linkshypertrophie und WPW-Syndrom. was published on January 1, 1989 in the journal Biomedical Engineering / Biomedizinische Technik (volume 34, issue s1).

ECG-alterations under the influence of static magnetic fields were investigated in phantoms (1.5 Tesla), animals and volunteers (4.0 Tesla), as well as in 12 patients (0.5, 1.0, and 1.5 Tesla). Under the influence of static magnetic fields high- and low-frequency voltages are superimposed on the ECG. Motions of the electrical leads induce high-frequency waves, which can alter the ECG to the extent that only the QRS-complex can be recognized. Electrolytes moved by the blood stream in static magnetic fields also induce voltages (Hall-effect) which, according to the patient's position, result in ST-segment- and partial T-wave-elevations or depressions. All ECG-alterations are reversible after exposition to the static magnetic field. Rhythm disturbances do not occur. The results indicate that static magnetic fields up to 4.0 Tesla do not have permanent adverse effects on the human ECG.

Wie jedes neue Verfahren in der Medizin wurde auch die Kernspintomographie auf mögliche Risiken und Nebenwirkungen geprüft [1–7]. Obwohl die technische Realisierung des Meßprinzipes komplex ist, sind die Grundkräfte, die auf den Menschen einwirken, einfach und in ihren Dimensionen genau definiert. Mögliche Schädigungen können durch das statische Magnetfeld die wechselnden Gradientenfelder und die Hochfrequenzfelder bedingt sein. Besonderer Beachtung bedürfen bewegte elektrische Ladungen innerhalb eines statischen Magnetfeldes. In den großen Arterien werden dabei Potentialdifferenzen von 16 mV pro Tesla induziert [1, 3]. Bereits bei Feldstärken von 0,3 Tesla sind Veränderungen des Elektrokardiogramms erkennbar [2]. Ziel dieser Untersuchung ist es, elektrokardiographische Veränderungen bei Einwirken einer Magnetfeldstärke von 0,5 bis 4,0 Tesla aufzuzeigen.