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At least 1,603 records · Page 89Linked to original sources
PubMed2004

Comparison of ultrasound and magnetic resonance imaging in 100 singleton pregnancies with suspected brain abnormalities.

OBJECTIVE: To compare the diagnostic accuracy of the current reference standard-ultrasound with in utero magnetic resonance imaging, in a selected group of patients. DESIGN: Prospective study. SETTING: Five fetal maternal tertiary referral centres and an academic radiology unit. SAMPLE: One hundred cases of fetuses with central nervous system abnormalities where there has been diagnostic difficulties on ultrasound. In 48 cases the women were less than 24 weeks of gestation and in 52 cases later in pregnancy. METHODS: All women were imaged on a 1.5 T clinical system using a single shot fast spin echo technique. The results of antenatal ultrasound and in utero magnetic resonance were compared. MAIN OUTCOME MEASURES: The definitive diagnosis was made either at autopsy or by postmortem magnetic resonance imaging, in cases that went to termination of pregnancy, or a combination of postnatal imaging and clinical follow up in the others. RESULTS: In 52 of cases, ultrasound and magnetic resonance gave identical results and in a further 12, magnetic resonance provided extra information that was judged not to have had direct effects on management. In 35 of cases, magnetic resonance either changed the diagnosis (29) or gave extra information that could have altered management (6). In 11 of the 30 cases where magnetic resonance changed the diagnosis, the brain was described as normal on magnetic resonance. CONCLUSIONS: In utero magnetic resonance imaging is a powerful tool in investigating fetal brain abnormalities. Our results suggest that in selected cases of brain abnormalities, detected by ultrasound, antenatal magnetic resonance may provide additional, clinically useful information that may alter management.

Brain↗
PubMed2006

Comparison of radiography and magnetic resonance imaging for evaluating the extent of nasal neoplasia in dogs.

OBJECTIVES: Magnetic resonance imaging (MRI) is increasingly used in veterinary practice and, in some centres, is part of the diagnostic work-up of small animals with nasal disease. However, there are no published studies which critically evaluate the use of magnetic resonance imaging for this purpose. The purpose of this work was to assess the changes seen using magnetic resonance imaging and to compare them with radiography. METHODS: The study included 12 dogs that had undergone both radiography and magnetic resonance imaging of the nasal cavity and had a histopathological diagnosis of malignant nasal neoplasia. Two pairs of board-certified radiologists scored the radiographs and the MRI scans, evaluating 10 signs of abnormality using a simple scoring system. Magnetic resonance imaging features were described in detail, and radiographic and magnetic resonance imaging scores for each sign as well as total scores were compared. RESULTS: Magnetic resonance imaging often showed that the tumour was more extensive than it had appeared on radiography but occasionally showed that radiographs had overestimated its size. Although radiography was reliable for assessment of the presence and size of a mass and for the extent of turbinate destruction, it usually failed to show occlusion of the major airway passages that were evident on magnetic resonance imaging. Extension of the tumour into the opposite nasal cavity, frontal sinus, orbit and cranial cavity was shown much better on magnetic resonance imaging. CLINICAL SIGNIFICANCE: Minor but significant extension beyond the nasal cavity, which is important for treatment planning and prognosis, requires magnetic resonance imaging for demonstration, although radiography shows major changes reliably.

Animals↗
PubMed2004

Electron beam therapy with coil-generated magnetic fields.

This paper presents an initial study on the issues involved in the practical implementation of the use of transverse magnetic fields in electron beam therapy. By using such magnetic fields the dose delivered to the tumor region can increase significantly relative to that deposited to the healthy tissue. Initially we calculated the magnetic fields produced by the Helmholtz coil and modified Helmholtz coil configurations. These configurations, which can readily be used to generate high intensity magnetic fields, approximate the idealized magnetic fields studied in our previous publications. It was therefore of interest to perform a detailed study of the fields produced by these configurations. Electron beam dose distributions for 15 MeV electrons were calculated using the ACCEPTM code for a 3T transverse magnetic field produced by the modified Helmholtz configuration. The dose distribution was compared to those obtained with no magnetic field. The results were similar to those obtained in our previous work, where an idealized step function magnetic field was used and a 3T field was shown to be the optimal field strength. A simpler configuration was also studied in which a single external coil was used to generate the field. Electron dose distributions are also presented for a given geometry and given magnetic field strength using this configuration. The results indicate that this method is more difficult to apply to radiotherapy due to its lack of symmetry and its irregularity. For the various configurations dealt with here, a major problem is the need to shield the magnetic field in the beam propagation volume, a topic that must be studied in detail.

Biophysical Phenomena↗
PubMed2006

Influence of static magnetic fields on pain perception and sympathetic nerve activity in humans.

Static and pulsed magnetic fields have been reported to have a variety of physiological effects. However, the effect of static magnetic fields on pain perception and sympathetic function is equivocal. To address this question, we measured pain perception during reproducible noxious stimuli during acute exposure to static magnets. Pain perception, muscle sympathetic nerve activity, mean arterial pressure, heart rate, and forearm blood velocity were measured during rest, isometric handgrip, postexercise muscle ischemia, and cold pressor test during magnet and placebo exposure in 15 subjects (25 +/- 1 yr; 8 men and 7 women) following 1 h of exposure. During magnet exposure, subjects were placed on a mattress with 95 evenly spaced 0.06-T magnets imbedded in it. During placebo exposure, subjects were placed on an identical mattress without magnets. The order of the two exposure conditions was randomized. At rest, no significant differences were noted in muscle sympathetic nerve activity (8 +/- 1 and 7 +/- 1 bursts/min for magnet and placebo, respectively), mean arterial pressure (91 +/- 3 and 93 +/- 3 mmHg), heart rate (63 +/- 2 and 62 +/- 2 beats/min), and forearm blood velocity (3.0 +/- 0.3 and 2.6 +/- 0.3 cm/s). Magnets did not alter pain perception during the three stimuli. During all interventions, no significant differences between exposure conditions were found in muscle sympathetic nerve activity and hemodynamic measurements. These results indicate that acute exposure to static magnetic fields does not alter pain perception, sympathetic function, and hemodynamics at rest or during noxious stimuli.

Adult↗
PubMed2000

Cranial vault expansion: a comparison of magnetic coupled distraction to traditional surgical repositioning.

We compared the effectiveness of transcutaneously activated magnetic distraction of an osteotomized cranial bone flap to surgical repositioning of the flap with immediate, rigid internal fixation. Thirty immature rabbits were studied. All 30 rabbits underwent complete circumferential osteotomies of both parietal bones and postoperatively all were fitted with head frames. The rabbits were divided into 4 groups. The experimental magnetic distraction group consisted of 10 animals (group 1). In these rabbits magnets were secured to both parietal bones and magnets of opposite polarity were placed in the headframes. Each morning, the magnets in the head-frames were moved 0.25 mm farther away from the skull; this continued for 20 days for a total setback of 5 mm. Five animals served as the magnetic distraction controls; in these animals magnets were placed on the parietal bones but none were attached to the headframes (group 2). The experimental surgical repositioning group consisted of 10 rabbits (group 3). In each the parietal bones were elevated and fixed 5 mm above the rest of the skull using vitallium mesh and screws. Five rabbits made up the surgical respositioning control group (group 4). In these animals, parietal osteotomies were performed but the bones were secured to the skull in their original positions using hardware identical to that used in the experimental group. Six weeks later all of the animals were sacrificed. Two significant differences were identified between the experimental groups: (1) the cranial contours of the animals in the magnetic distraction group were rounded while those of the surgically repositioned group were acutely angled; (2) the osteotomies in rabbits in the magnetic distraction group were essentially completely ossified while in rabbits in the surgically repositioned group there were obvious gaps at the osteotomy sites that were filled with fibrous tissue. These conclusions support the potential utility of magnetically activated distraction as an alternative to current methods of cranial vault remodeling.

Animals↗
PubMed1996

Comparison of cervical magnetic and transcutaneous phrenic nerve stimulation before and after threshold loading.

Brief supramaximal stimulation of the phrenic nerves (twitch) is considered a promising technique to detect diaphragmatic fatigue in humans. However, the most commonly employed methodology (transcutaneous stimulation) is technically difficult. Cervical magnetic stimulation is a recently described technique that is potentially simpler and may obviate some of the problems inherent with transcutaneous stimulation. The purpose of this study was to determine the ability of cervical magnetic stimulation to evaluate diaphragmatic function. Accordingly, we measured transdiaphragmatic pressure (Pdi) during transcutaneous and cervical magnetic stimulation of the phrenic nerves before and after a potentially fatiguing task; inspiratory threshold loading to task failure. During threshold loading, subjects generated approximately 60% of their maximal esophageal pressure with each breath until they could no longer reach the target pressure. At least 10 twitches were obtained during both transcutaneous and magnetic stimulation before and 10, 30, 60, and 120 min after threshold loading. Control twitch Pdi was significantly larger during magnetic stimulation compared with transcutaneous stimulation: 39.3 +/- 3.0 (mean +/- SE) versus 27.4 +/- 2.3 cm H2O, p < 0.0005. This increase in twitch Pdi was solely due to the esophageal component. Following threshold loading, a significant reduction in transcutaneous twitch Pdi was seen in only three of the 10 subjects. Mean transcutaneous twitch Pdi fell only slightly from 27.4 +/- 2.3 during control to 25.1 +/- 2.2 cm H2O at 10 min after loading (p < 0.004). In contrast, magnetic twitch Pdi was significantly reduced in nine of the 10 subjects following threshold loading. Mean magnetic twitch Pdi fell from 39.3 +/- 3.0 during control to 31.1 +/- 3.0 cm H2O at 10 min after loading (p < 0.0001). The average fall in twitch Pdi post-loading (expressed as a percentage of the control value) was significantly greater for magnetic stimulation compared with transcutaneous stimulation: 21.0 +/- 3.1 versus 7.8 +/- 2.9%, p < 0.0001. In summary: (1) in the fresh state, twitch Pdi is larger with magnetic stimulation compared with transcutaneous stimulation, and (2) transcutaneous and cervical magnetic twitch Pdi are affected differently by threshold loading to task failure.

Adult↗
PubMed2006

A comparison between clinical assessment and magnetic resonance imaging of acute hamstring injuries.

BACKGROUND: Physicians evaluating hamstring strains in professional football players are increasingly turning to magnetic resonance imaging to support the clinical diagnosis and management of the injury. However, little information is available to assess how magnetic resonance imaging compares with the clinical evaluation in establishing the duration of rehabilitation required. HYPOTHESIS: Magnetic resonance imaging of hamstring strains can be useful in determining duration of rehabilitation. STUDY DESIGN: Cohort study (Diagnosis); Level of evidence, 1. METHODS: Fifty-eight professional football players with a diagnosis of hamstring injury made by the team physician were enrolled in the study. All players underwent magnetic resonance imaging and a clinical evaluation by an independent physical therapist within 3 days of the injury. Presence, type, and location of injury were recorded in each examination. The physical therapist estimated the time required until return to competition, and the radiologist used the length of the injury (coronal view) to establish rehabilitation duration. Both clinicians were blinded to the other modality. RESULTS: Clinical and magnetic resonance imaging assessments were in agreement in 38 of 58 cases (65.5%). In 18 cases (31.0%), a clinically positive diagnosis was made, but no abnormalities were evident on magnetic resonance imaging. In 2 cases (3.4%), magnetic resonance imaging detected an injury, whereas the clinical examination had negative or equivocal findings. Both clinical examination and magnetic resonance imaging findings were strongly correlated with the actual time required to return to competition (r = .69, P < .001 and r = .58, P < .001, respectively). The correlation coefficient between clinical predictions and magnetic resonance imaging findings was moderate (r = .36, P = .006). CONCLUSION: This study shows that magnetic resonance imaging is not required for estimating the duration of rehabilitation of an acute minor or moderate hamstring injury in professional football players.

Adult↗
PubMedDate not supplied

Magnetic resonance imaging of knee disorders. Clinical value and cost-effectiveness in a sports medicine practice.

To prospectively evaluate the clinical value of magnetic resonance imaging of the knee in a referral sports medicine practice, we performed a three-part study. First, we asked 72 consecutive patients a series of clinically relevant questions regarding the ordering of their magnetic resonance imaging scans. Second, we asked the treating physicians at our center if the magnetic resonance imaging findings changed the diagnosis or treatment. Third, we compared the clinical evaluation with the findings on magnetic resonance imaging scans for 37 patients who had arthroscopic confirmation. From the physician's perspective, in only three cases would the results of the scan have changed the diagnosis. Information from the scans was judged to contribute to patient treatment in only 14 of 72 patients. Finally, comparison of clinical evaluation and magnetic resonance imaging findings with findings during arthroscopic procedures showed that clinical evaluation had a sensitivity and specificity of 100% for diagnosis of anterior cruciate ligament injuries, whereas magnetic resonance imaging was 95% sensitive and 88% specific. For isolated meniscal lesions, the clinical assessment had a sensitivity and specificity of 91% compared with 82% and 87%, respectively, for magnetic resonance imaging. For evaluation of articular surface damage, the predictive value of a positive test was 100% for clinical assessment and 33% for the magnetic resonance imaging. We conclude that magnetic resonance imaging is overused in the evaluation of knee disorders and not a cost-effective method for evaluating injuries when compared with a skilled examiner. Clinical assessment equals or surpasses the magnetic resonance imaging in accuracy.

Adolescent↗
PubMed2001

Subjective reactions of children to single-pulse transcranial magnetic stimulation.

Single-pulse transcranial magnetic stimulation is a useful tool to investigate cortical function in childhood neuropsychiatric disorders. Magnetic stimulation is associated with a shock-like sensation that is considered painless in adults. Little is known about how children perceive the procedure. We used a self-report questionnaire to assess children's subjective experience with transcranial magnetic stimulation. Normal children and children with attention-deficit hyperactivity disorder (ADHD) underwent transcranial magnetic stimulation in a study of cortical function in ADHD. Subjects were asked to rate transcranial magnetic stimulation on a 1 to 10 scale (most disagreeable = 1, most enjoyable = 10) and to rank it among common childhood events. Thirty-eight subjects completed transcranial magnetic stimulation; 34 said that they would repeat it. The overall rating for transcranial magnetic stimulation was 6.13, and transcranial magnetic stimulation was ranked fourth highest among the common childhood events. These results suggest that although a few children find transcranial magnetic stimulation uncomfortable, most consider transcranial magnetic stimulation painless. Further studies are necessary to confirm these findings.

Adolescent↗
PubMed1997

The utility of high-resolution magnetic resonance imaging in the evaluation of the triangular fibrocartilage complex of the wrist.

We performed a prospective study in order to assess the utility of high-resolution magnetic resonance imaging in the detection and specific localization of tears of the triangular fibrocartilage complex. Seventy-seven patients who had pain in the wrist were studied with use of a dedicated surface coil and three-dimensional gradient-recalled techniques with a field of view of eight centimeters and a slice thickness of one millimeter. The patients had pain on the ulnar side of the wrist, ligamentous instability, occult ganglia, or a combination of these. Magnetic resonance images were assessed for radial or ulnar avulsion, or both; central defects; degenerative intrasubstance changes; and complex tears of the triangular fibrocartilage complex. Partial tears were differentiated from complete tears. The findings on the magnetic resonance images were then compared with the arthroscopic findings. Fifty-seven of the fifty-nine tears that were suspected on magnetic resonance images were confirmed with arthroscopy; the two suspected tears that were not confirmed had been interpreted as small partial tears on the magnetic resonance images. With use of arthroscopy as the standard, magnetic resonance imaging had a sensitivity of 100 per cent (fifty-seven of fifty-seven), a specificity of 90 per cent (eighteen of twenty), and an accuracy of 97 per cent (seventy-five of seventy-seven) for the detection of a tear (kappa = 0.93, p < 0.00001). Fifty-three of the fifty-seven tears were localized correctly with use of magnetic resonance imaging. With regard to the location of the tear, magnetic resonance imaging had a sensitivity of 100 per cent (fifty-three of fifty-three), a specificity of 75 per cent (eighteen of twenty-four), and an accuracy of 92 per cent (seventy-one of seventy-seven) (kappa = 0.9, p < 0.0001). We concluded that high-resolution magnetic resonance imaging permits accurate depiction and localization of tears of the triangular fibrocartilage complex. When the appropriate pulse sequence is used, magnetic resonance imaging is an accurate and effective method for the non-invasive evaluation of pain in the wrist.

Adolescent↗
PubMed1988

Application of 31P magnetic resonance spectroscopy to the study of athletic performance.

Magnetic resonance spectroscopy is a non-invasive and repeatable method of studying muscle metabolism. Magnetic resonance spectroscopy uses specific radiofrequency pulses in a strong magnetic field to determine the relative concentrations of chemical compounds in the sample. 31P Magnetic resonance spectroscopy provides indirect measures of phosphate compounds such as adenosine triphosphate (ATP), phosphocreatine and inorganic phosphate. Muscle intracellular pH can also be determined. Exercise tests can be performed in the magnet such that the metabolic response to steady-state exercise can be measured. The ratio of inorganic phosphate to phosphocreatine reflects the relative metabolic rate of mitochondrial respiration (V) and the extrapolated maximum capacity of oxidative metabolism (Vm). Normal humans vary considerably in their metabolic response to exercise. These differences are reflected in their Vms and the degree of acidosis during exercise. Active muscles in endurance trained athletes have higher Vms and faster recovery rates than normal controls. Preliminary studies have been done to assess muscle glycolytic capacity by measuring the degree of acidosis during ischaemic exercise. Exercise-induced muscle injury can be detected as an increased inorganic phosphate to phosphocreatine ratio in resting muscle. The increase in the inorganic phosphate to phosphocreatine ratio with injury reaches a peak 1 to 2 days after the injury and lasts for up to a week. Similar increases in the inorganic phosphate to phosphocreatine ratio occur in patients with destructive neuromuscular diseases. Thus changes in the resting inorganic phosphate to phosphocreatine ratio may be used to detect the degree of muscle injury following exercise. Levels of H2PO4- in muscle are thought to be important in causing muscle fatigue during exercise. As 31P magnetic resonance spectroscopy can measure H2PO4-, magnetic resonance spectroscopy has become a useful technique in the study of the metabolic causes of muscle fatigue. It may also be possible to identify the relative populations of fast twitch and slow twitch fibres in a skeletal muscle using pH changes measured with 31P magnetic resonance spectroscopy. Magnetic resonance spectroscopy using other nuclei, such as 1H, 13C and 23Na, have the potential to provide information on other metabolic changes which occur with exercise. Magnetic resonance spectroscopy has shown promise as a technique to monitor the effects of training, including overtraining, in specific muscle groups in athletes.

Energy Metabolism↗
PubMed1999

[Hepatocellular carcinoma in cirrhosis: semeiology and performance of magnetic resonance imaging and lipiodol computed tomography].

OBJECTIVES: a) Describe hepatocellular semiology in magnetic resonance imaging and lipiodol computerized tomography in patients with cirrhosis, who are candidates for surgery; b) Clarify the respective roles of magnetic resonance imaging and lipiodol computerized tomography in hepatocellular detection. METHODS: Twenty four patients with suspected hepatocellular carcinoma underwent successive magnetic resonance imaging and lipiodol computerized tomography. Thirty-four of the 67 lesions seen by lipiodol computerized tomography and 28 of 52 lesions seen by magnetic resonance imaging were confirmed histologically. RESULTS: In lipiodol computerized tomography, 44% of hepatocellular carcinomas had a dense and homogeneous pattern; 24% had a homogeneous but slightly dense pattern. Sixteen distinct deposits were described: 4 were confirmed as hepatocellular carcinoma and 12 were not controlled histologically. In magnetic resonance imaging 57% of hepatocellular carcinomas have a high intensity on T1 and T2 weighted spin echo images, 38% were hyperintense on T2 and hypo or isointense on T1 weighted images. Eighty-six percent of hyperintense T1 and T2 weighted images were hepatocellular carcinoma. When the gold standard was histology, lipiodol computerized tomography sensitivity (81%) was higher than magnetic resonance imaging (68%). When the gold standard was lipiodol computerized tomography, the sensitivity of magnetic resonance imaging was 47 +/- 12%. CONCLUSIONS: a) The sensitivity of lipiodol computerized tomography was better than resonance magnetic imaging; b) the homogeneous and slightly dense pattern corresponded to a hepatocellular carcinoma in 50% of cases; c) on magnetic resonance imaging any lesions with high intensity on T1 and T2 spin echo images strongly suggests hepatocellular carcinoma; d) if surgical resection after ultrasonography is being considered, the second step should be an magnetic resonance imaging.

Aged↗
PubMedDate not supplied

Low-amplitude, extremely low frequency magnetic fields for the treatment of osteoarthritic knees: a double-blind clinical study.

CONTEXT: Noninvasive magnetotherapeutic approaches to bone healing have been successful in past clinical studies. OBJECTIVE: To determine the effectiveness of low-amplitude, extremely low frequency magnetic fields on patients with knee pain due to osteoarthritis. DESIGN: Placebo-controlled, randomized, double-blind clinical study. SETTING: 4 outpatient clinics. PARTICIPANTS: 176 patients were randomly assigned to 1 of 2 groups, the placebo group (magnet off) or the active group (magnet on). INTERVENTION: 6-minute exposure to each magnetic field signal using 8 exposure sessions for each treatment session, the number of treatment sessions totaling 8 during a 2-week period, yielded patients being exposed to uniform magnetic fields for 48 minutes per treatment session 8 times in 2 weeks. The magnetic fields used in this study were generated by a Jacobson Resonator, which consists of two 18-inch diameter (46-cm diameter) coils connected in series, in turn connected to a function generator via an attenuator to obtain the specific amplitude and frequency. The range of magnetic field amplitudes used was from 2.74 x 10(-7) to 3.4 x 10(-8) G, with corresponding frequencies of 7.7 to 0.976 Hz. OUTCOME MEASURES: Each subject rated his or her pain level from 1 (minimal) to 10 (maximal) before and after each treatment and 2 weeks after treatment. Subjects also recorded their pain intensity in a diary while outside the treatment environment for 2 weeks after the last treatment session (session 8) twice daily: upon awakening (within 15 minutes) and upon retiring (just before going to bed at night). RESULTS: Reduction in pain after a treatment session was significantly (P < .001) greater in the magnet-on group (46%) compared to the magnet-off group (8%). CONCLUSION: Low-amplitude, extremely low frequency magnetic fields are safe and effective for treating patients with chronic knee pain due to osteoarthritis.

Adult↗
PubMed2002

The effect of flexible magnets on hand muscle strength: a randomized, double-blind study.

The purpose of this study was to determine the effect of a flexible magnet on hand grip and thumb-forefinger pinch strength. Flexible magnet use has become popular in sports medicine and rehabilitation for a number of reasons, including augmenting muscle force output. Thirty-five university students (18 men and 17 women) volunteered for this study. Each subject was tested for grip strength (grip dynamometer) and thumb-forefinger pinch strength (pinch gauge) under 3 different treatment conditions: baseline (no magnet), sham magnet (placebo), and flexible magnet (700-G intensity). The order of treatments was randomly assigned, and all data collection followed a double-blind format. For grip strength measurements, magnet placement was over the bellies of the flexor digitorum profundus and flexor digitorum superficialis, and for pinch strength measurements, it was over the bellies of the flexor pollicis brevis and opponens pollicis. Three trials for each strength measurement for each of the 3 conditions were performed. Magnets (700 G or sham) were placed on the appropriate areas of the skin 3 minutes before the first test trial, with each subsequent test trial separated by 1 minute. Comparison among the 3 treatment conditions was analyzed using a 1-way analysis of variance (ANOVA) with repeated measures. ANOVA revealed no statistically significant (p > 0.05) mean differences for strength among any of the 3 treatments (baseline, 700-G magnet, or sham magnet) for either hand grip or thumb-forefinger pinch within each sex subgroup or for the combined group. The findings indicate that flexible magnets with a field strength of 700 G do not increase muscle strength.

Adult↗
PubMedDate not supplied

Magnetic resonance cholangiopancreatography in patients with upper abdominal pain: a prospective study.

BACKGROUND/AIMS: To determine the role of magnetic resonance cholangiopancreatogram with conventional abdominal magnetic resonance examination in patients presenting clinically with upper abdominal pain and abnormal liver function tests and to compare the findings with endoscopic retrograde cholangiopancreatogram results. METHODOLOGY: Magnetic resonance cholangiopancreatogram and endoscopic retrograde cholangiopancreatogram were done in 77 patients. Conventional magnetic resonance examination of the liver and upper abdomen was done first followed by magnetic resonance cholangiopancreatogram using a half fourrier single shot turbo spin echo sequence. Conventional endoscopic retrograde cholangiopancreatogram was done by direct intraductal injection of radiographic contrast material through a duodenoscope under fluoroscopy control. RESULTS: Endoscopic retrograde cholangiopancreatogram failed in 7 patients (9%) and Magnetic resonance cholangiopancreatogram images were inadequate in 3 patients (4%). The findings of adequate magnetic resonance exams in 74 patients were: choledocholithiasis in 24 patients (32%), bile duct stricture in 19 patients (26%), normal biliary ducts in 29 patients (39%) and dilated biliary ducts with no definite cause in 2 patients (3%). The findings of successful endoscopic retrograde cholangiopancreatograms in 67 patients after exclusion of inadequate magnetic resonance cholangiopancreatograms were: choledocholithiasis in 25 patients (37%), bile duct stricture in 18 patients (27%), normal biliary ducts in 21 patients (31%) and dilated biliary ducts with no evident cause in 2 patients (3%) and hemobilia in 1 patient (2%). CONCLUSIONS: Magnetic resonance cholangiopancreatogram is a non-invasive technique, its accuracy is increased if it is combined with conventional abdominal magnetic resonance exam and it can replace the endoscopic retrograde cholangiopancreatogram.

Abdominal Pain↗
PubMed2004

Target distribution of magnetic albumin nanoparticles containing adriamycin in transplanted rat liver cancer model.

BACKGROUND: Liver cancer is one of the most common diseases around the world. The aim of this study was to verify the effect of magnetic field application on target distribution of nanoparticles in transplanted rat liver cancer model and to find out a new method for the treatment of malignant liver tumor. METHODS: Seven days after the establishment of the model, the abdomen of the rat was exposed through a midline abdominal incision. A cannula was inserted into the gastro-duodenal artery. In the experimental group (12 rats), the tumor tissue was exposed to the magnetic field for 30 minutes. Magnetic albumin nanoparticles containing adriamycin or at an equal dose of free adriamycin (0.5 mg/kg) were injected into the hepatic artery. After the magnetic field was removed, the rat was immediately sacrificed. An equal dose of nanoparticles in absence of the magnetic field served as control (12 rats). Tissues of tumor, nontargeted sites of the liver, heart, kidney, lung, spleen, stomach and small intestine were analyzed for gamma-counts and examined histologically. RESULTS: In the experimental group, the radioactivity of tumor tissue was 8.7 times that of liver tissue. In the control group, the radioactivity of tumor tissue was 2.8 times that of normal liver tissue. The radioactivity of the lung was reduced more significantly in the experimental group than in the control group. No significant difference in the kidney, heart, spleen, small intestine and stomach was observed between the experimental group and control group. And over 80% of the injected nanoparticles distributed in the liver. CONCLUSIONS: In the presence of magnetic field, magnetic albumin nanoparticles may accumulate in tumor tissues, of which the radioactivity can increase to 8.7 times that of normal liver. Even if the magnetic field is not applied, magnetic albumin nanoparticles in tumor tissues still increase to 2.8 times that of normal liver tissues. These findings indicate that normal organs in the presence of magnetic field are less exposed to chemotherapeutic drugs.

Albumins↗
PubMed1991

Magnetic studies on mechanical activity of the heart.

Magnetic measurement offers a new noninvasive technique for monitoring cardiac mechanical activity and for evaluation of important hemodynamic parameters, e.g., heart volume changes and cardiac output. The magnetic signal is observed with a sensitive magnetometer when an external magnetic field is applied to the thorax. The magnitude of the signal is usually in the order of a few picoteslas when an applied magnetic field of about 250 A/m is used. This signal is due to the differences in magnetic susceptibilities of intracardiac blood, heart muscle, and surrounding lung tissues. In the present paper, the origin of the magnetic susceptibility signal is theoretically analyzed and various measurement techniques are reviewed. The measurement results reported by different authors are compared and discussed. The spatial variation of the magnetic signal is analyzed in terms of mathematical models and its temporal behavior is compared with the results obtained from other measurement techniques. Three independent experimental methods are proposed in order to separate the magnetic plethysmogram from the other components in the total magnetic susceptibility signal recorded above the heart. The results suggest that usually about 65 to 80% of the signal originates directly from cardiac volume changes, and that the cardiac plethysmogram can be separated easily by surrounding the thorax with the medium whose magnetic susceptibility is about -5.10(-6), or by preventing motion of the chest wall of the subject.

Biomechanical Phenomena↗
PubMed1996

Clinical experiences with magnetic drug targeting: a phase I study with 4'-epidoxorubicin in 14 patients with advanced solid tumors.

Anticancer drugs reversibly bound to magnetic fluids (ferrofluids) could be concentrated in locally advanced tumors by magnetic fields that are arranged at the tumor surface outside of the organism. If certain requirements are met, systemic toxicity might be minimized, and local tumor efficacy might be increased. We have conducted a Phase I clinical trial using this approach in patients with advanced and unsuccessfully pretreated cancers or sarcomas. Nine such patients received two treatment courses, 3 patients received one course, and 2 patients received three courses of magnetic drug targeting consisting of the infusion of epirubicin in increasing doses (from 5 to 100 mg/m2) that had been chemically bound to a magnetic fluid and the application of magnetic fields to the tumors for 60-120 min. In 2 of 14 patients, the same dose of epirubicin not bound to a magnetic fluid was administered systemically 3 weeks after drug targeting for intraindividual comparisons. Magnetic drug targeting with epirubicin was well tolerated. In one case, a planned second treatment was withdrawn, because of an episode of chills 130 min after infusion of the magnetic drug. Two patients received a third treatment because of good responses after the first two therapies. Based on magnetic resonance tomographic techniques, pharmacokinetics, and the histological detection of magnetites, it was shown that the ferrofluid could be successfully directed to the tumors in about one-half of the patients. Organ toxicity did not increase with the treatment, but epirubicin-associated toxicity appeared at doses greater than 50 mg/m2. Although treatment with magnetic drug targeting seems safe, improvements are necessary to make it more effective and independent of patient- or disease-related problems. A study design to compare conventional treatments with the new treatment form within one patient seems crucial to eliminate interindividual differences.

Adolescent↗