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PubMed1995

In vitro cytotoxicity testing of neodymium-iron-boron magnets.

Neodymium-iron-boron magnets are being increasingly used in orthodontic and orthopedic appliances. The purpose of this study was to investigate the in vitro cytotoxicity of these new "super" magnets. A modified agar overlay technique was performed using both L929 mouse fibroblasts and adult human oral mucosal fibroblasts. The neodyium-iron-boron magnets were tested in the following forms: uncoated magnetized, uncoated demagnetized, parylene coated demagnetized, and parylene coated magnetized. Results revealed that uncoated magnetized, uncoated demagnetized, and parylene coated magnetized were cytotoxic to both L929 mouse fibroblasts and human oral mucosal fibroblasts. However the parylene coated demagnetized neodymium magnets were only cytotoxic to the human mucosal fibroblasts. This study supports the hypothesis that these are cytotoxic effects of possibly corrosion products and of magnetism. The specific toxic effects of parylene were not examined in this present study. Statistical analysis (Mann-Whitney U-test, p = 0.014) suggested that, in this experiment, the human oral mucosal fibroblasts were more sensitive to the effects of these rare earth magnets. With the evidence of a biological effect, the use of implanted magnets must at present be limited until the safety can be assured.

Animals↗
PubMed2005

Efficiency of magnetic liposomal transforming growth factor-beta 1 in the repair of articular cartilage defects in a rabbit model.

We evaluated the efficacy of a magnetic liposomal delivery system of transforming growth factor (TGF)-beta(1) in the treatment of articular cartilage defects in a rabbit model. Articular cartilage defects were created in the patellar groove of rabbits, and a permanent magnet or a nonmagnetic alloy was implanted in the defect site. Magnetic liposomal drugs, prepared by the conventional film method and sonication, were injected into the defect site 1 week after surgery. First, the efficacy of the magnetic liposomal delivery system was evaluated by using a model compound fluorescence-labeled dextran 40,000 (FD-40). Then, the therapeutic efficiency of magnetic liposomal TGF-beta(1) was evaluated by cartilage histological scoring at 4, 8, and 12 weeks after surgery. The injected magnetic liposomal FD-40 accumulated at the target site where a permanent magnet had been implanted. The histological score showed that the injection of magnetic liposomal TGF-beta(1) under magnetic force was significantly effective in the repair of the defect site over 12 weeks after surgery. Injection of TGF-beta(1) into the cartilage defect was effective as a magnetic liposomal preparation under magnetic force, resulting in acceleration of the cartilage repair, probably because of the desirable accumulation of TGF-beta(1) at the target site.

Animals↗
PubMed1986

Magnetic compass orientation in the Eastern red-spotted newt (Notophthalmus viridescens).

Laboratory tests were carried out to examine the orientation behavior of adult Eastern red-spotted newts (Notophthalmus viridescens) to earth-strength magnetic fields. Groups of 30 to 40 newts were housed in water-filled, all-glass aquaria with an artificial shoreline at one end. The aquaria were located in a greenhouse or outdoors adjacent to the laboratory building, and aligned on either the magnetic north-south or east-west axis. Tests were carried out in an enclosed indoor arena. Newts were tested in four horizontal alignments of the magnetic field: the ambient magnetic field (magnetic north at North) and three altered fields (magnetic north rotated to East, South or West). Data were analyzed after pooling the magnetic bearings from all four conditions in such a way as to retain the component of the newts' orientation that was a consistent response to the magnetic field. Elevation of training tank water temperature was used to increase the newts' motivation to orient in the direction of shore. Newts exposed to a training tank water temperature of 33-34 degrees C just prior to testing exhibited consistent unimodal magnetic compass orientation. The direction of orientation was altered predictably by changing training tank alignment and location relative to the laboratory building. The results provide the first evidence of a strong, replicable magnetic compass response in a terrestrial vertebrate under controlled laboratory conditions. Further, the present study demonstrates that the Eastern newt is able to learn a directional response relative to the earth's magnetic field.

Animals↗
PubMed2005

Accuracy of magnetic resonance imaging in rectal cancer depends on location of the tumor.

PURPOSE: This study was designed to evaluate prospectively magnetic resonance imaging for the prediction of the circumferential resection margin in rectal cancer to identify in which patient magnetic resonance imaging could accurately assess the circumferential resection margin before surgery and in which patients it could not. METHODS: During a 17-month period, a preoperative magnetic resonance imaging for the assessment of circumferential resection margin was obtained prospectively in 38 patients with mid or low rectal cancer. The agreement of magnetic resonance imaging and pathologic examination for assessment of circumferential resection margin was analyzed. RESULTS: Overall, magnetic resonance imaging agreed with histologic examination of the circumferential resection margin assessment in 28 patients (73 percent; kappa = 0.47). In all cases of disagreement between magnetic resonance imaging and pathology, magnetic resonance imaging overestimated the circumferential resection margin involvement. For the 11 patients with mid rectal cancer, circumferential resection margin was well predicted by magnetic resonance imaging in all cases (kappa = 1). For 27 patients with low rectal tumor, overall agreement between magnetic resonance imaging and histologic assessment was 63 percent (kappa = 0.35). Agreement was 22 percent (kappa = 0.03) for the 9 patients with low anterior and 83 percent (kappa = 0.67) for the 18 patients with low posterior rectal tumor. Univariate analysis revealed that only low and anterior rectal tumor was risk factor of overestimation of the circumferential resection margin by magnetic resonance imaging. CONCLUSIONS: Although magnetic resonance imaging remains the best imaging tool for the preoperative assessment of the circumferential resection margin in patients with rectal cancer, it can overestimate the circumferential resection margin involvement in low and anterior tumor with the risk of overtreating the patients.

Adult↗
PubMed1993

Experimental evidence for 60 Hz magnetic fields operating through the signal transduction cascade. Effects on calcium influx and c-MYC mRNA induction.

We tested the hypothesis that early alterations in calcium influx induced by an imposed 60 Hz magnetic field are propagated down the signal transduction (ST) cascade to alter c-MYC mRNa induction. To test this we measured both ST parameters in the same cells following 60 Hz magnetic field exposures in a specialized annular ring device (220 G (22 mT), 1.7 mV/cm maximal E(induced), 37 degrees C, 60 min). Ca2+ influx is a very early ST marker that precedes the specific induction of mRNA transcripts for the proto-oncogene c-MYC, an immediate early response gene. In three experiments influx of 45Ca2+ in the absence of mitogen was similar to that in cells treated with suboptimal levels of Con-A (1 micrograms/ml). However, calcium influx was elevated 1.5-fold when lymphocytes were exposed to Con-A plus magnetic fields; this co-stimulatory effect is consistent with previous reports from our laboratory [FEBS Lett. 301 (1992) 53-59; FEBS Lett. 271 (1990) 157-160; Ann. N.Y. Acad. Sci. 649 (1992) 74-95]. The level of c-MYC mRNA transcript copies in non-activated cells and in suboptimally-activated cells was also similar, which is consistent with the above calcium influx findings. Significantly, lymphocytes exposed to the combination of magnetic fields plus suboptimal Con-A responded with an approximate 3.0-fold increase in band intensity of c-MYC mRNA transcripts. Importantly, transcripts for the housekeeping gene GAPDH were not influenced by mitogen or magnetic fields. We also observed that lymphocytes that failed to exhibit increased calcium influx in response to magnetic fields plus Con-A, also failed to exhibit an increase in total copies of c-MYC mRNA. Thus, calcium influx and c-MYC mRNA expression, which are sequentially linked via the signal transduction cascade in contrast to GAPDH, were both increased by magnetic fields. These findings support the above ST hypothesis and provide experimental evidence for a general biological framework for understanding magnetic field interactions with the cell through signal transduction. In addition, these findings indicate that magnetic fields can act as a co-stimulus at suboptimal levels of mitogen; pronounced physiological changes in lymphocytes such as calcium influx and c-MYC mRNA induction were not triggered by a weak mitogenic signal unless accompanied by a magnetic field. Magnetic fields, thus, have the ability to potentiate or amplify cell signaling.

Animals↗
PubMedDate not supplied

Effects of static magnetic fields at the cellular level.

There have been few studies on the effects of static magnetic fields at the cellular level, compared to those of extremely low frequency magnetic fields. Past studies have shown that a static magnetic field alone does not have a lethal effect on the basic properties of cell growth and survival under normal culture conditions, regardless of the magnetic density. Most but not all studies have also suggested that a static magnetic field has no effect on changes in cell growth rate. It has also been shown that cell cycle distribution is not influenced by extremely strong static magnetic fields (up to a maximum of 10 T). A further area of interest is whether static magnetic fields cause DNA damage, which can be evaluated by determination of the frequency of micronucleus formation. The presence or absence of such micronuclei can confirm whether a particular treatment damages cellular DNA. This method has been used to confirm that a static magnetic field alone has no such effect. However, the frequency of micronucleus formation increases significantly when certain treatments (e.g., X-irradiation) are given prior to exposure to a 10 T static magnetic field. It has also been reported that treatment with trace amounts of ferrous ions in the cell culture medium and exposure to a static magnetic field increases DNA damage, which is detected using the comet assay. In addition, many studies have found a strong magnetic field that can induce orientation phenomena in cell culture.

Animals↗
PubMed2001

Magnetic properties and heavy-metal contents of contaminated seabed sediments of Penny's Bay, Hong Kong.

Magnetic properties and heavy-metal concentrations of vibrocore samples were found to be potential indicators of shipping contamination in seabed sediments in Hong Kong Harbour. Geochemical results of 74 vibrocores located off Penny's Bay on Lantau Island revealed an enrichment of heavy metals in the upper 1-2 m of the cores within the eastern part of the study site. Whole-core magnetic susceptibility measurements also showed a greater concentration of magnetic particles in the surficial layer of these cores. A significant correlation exists between the magnetic susceptibility and the concentrations of Pb, Zn and Cu, as well as the Tomlinson pollution load index (PLI). The proximity of these cores to a major navigation fairway and an anchorage site suggests probable contamination of the surficial seabed sediments by shipping-related wastes. A study of the magnetic properties of one of the cores, VT60, revealed a difference in the magnetic properties between the contaminated and the uncontaminated sediments. Samples from the contaminated zone exhibited relatively stronger magnetic remanence and susceptibility. The two groups of samples also formed distinct trends on the hysteresis ratios plot. A level of unusually high magnetic susceptibility within the contaminated zone was attributable to the presence of strongly magnetized granules, which were probably refuse from shipping-related activities. Geochemical and magnetic results were also conducted on samples of different size-fractions from this core. The < 63 microns fraction was found to contain a relatively higher magnetic susceptibility and greater heavy-metal content.

Environmental Monitoring↗
PubMed1983

Magnetic bones in human sinuses.

Studies on the interaction of magnetic fields and biological organisms have centred on the influence of applied magnetic fields on the physiology and behaviour of organisms, including humans, and a search for magnetic sources within the organisms themselves. Evidence continues to accumulate that a wide range of organisms, from bacteria to vertebrates, can detect and orient to ambient magnetic fields (for examples see refs 2-4). Since the discovery that magnetic orientation by bacteria was due to the presence within the organism of magnetic particles of the ferric/ferrous oxide, magnetite, the search has begun for other biogenic deposits of inorganic magnetic material and ways in which the possession of such material might confer on the organism the ability to orient to ambient magnetic fields. Such magnetic material, often identified as magnetite, has been discovered in bees, homing pigeons, dolphins and various other organisms, including man. A variety of hypotheses for the use of magnetite in magnetic field detection have been proposed. We report here that bones from the region of the sphenoid/ethmoid sinus complex of humans are magnetic and contain deposits of ferric iron. The possible derivations and functions of these deposits are discussed.

Bone and Bones↗
PubMed2003

Response of fistulating Crohn's disease to infliximab treatment assessed by magnetic resonance imaging.

AIMS: To assess fistula track healing after infliximab treatment using magnetic resonance imaging. METHODS: Magnetic resonance imaging and clinical evaluation were performed before and after three infliximab infusions given over a 6-week period. Magnetic resonance images were evaluated for abscesses and fistula tracks. Paired magnetic resonance image examinations were rated 'better', 'unchanged' or 'worse'. Magnetic resonance imaging and clinical outcomes were then compared. RESULTS: Of the 12 referred patients, pre-treatment magnetic resonance imaging detected abscesses in three (two not treated). Of the 10 treated patients, seven had peri-anal fistulas, two of whom also had recto-vaginal fistulas, and three had abdominal wall entero-cutaneous fistulas. After infliximab, four were in remission, one had a response and five were non-responders. One developed a peri-anal abscess. Magnetic resonance imaging improved in six, was unchanged in two and was worse in two. In four of the six with improvement in magnetic resonance imaging, the fistula track resolved, but two of these had clinically persistent entero-cutaneous fistulas. The clinical outcome and magnetic resonance imaging correlated in seven of the 10 patients; in three (two entero-cutaneous and one peri-anal), there was discordance. CONCLUSIONS: Magnetic resonance imaging identifies clinically silent sepsis. Fistulas may persist despite clinical remission. Clinical response to infliximab and clinical correlation with magnetic resonance imaging were poor in patients with abdominal entero-cutaneous fistulas.

Abscess↗
PubMed1998

Performance of a continuous flow ventricular assist device: magnetic bearing design, construction, and testing.

A new centrifugal continuous flow ventricular assist device, the CFVAD III, which is fully magnetic bearing suspended, has been developed. It has only one moving part (the impeller), has no contact (magnetic suspension), is compact, and has minimal heating. A centrifugal impeller of 2 inch outer diameter is driven by a permanent magnet brushless DC motor. This paper discusses the design, construction, testing, and performance of the magnetic bearings in the unit. The magnetic suspension consists of an inlet side magnetic bearing and an outlet side magnetic bearing, each divided into 8 pole segments to control axial and radial displacements as well as angular displacements. The magnetic actuators are composed of several different materials to minimize size and weight while having sufficient load capacity to support the forces on the impeller. Flux levels in the range of 0.1 T are employed in the magnetic bearings. Self sensing electronic circuits (without physical sensors) are employed to determine the impellar position and provide the feedback control signal needed for the magnetic bearing control loops. The sensors provide position sensitivity of approximately 0.025 mm. A decentralized 5 axis controller has been developed using modal control techniques. Proportional integral derivative controls are used for each axis to levitate the magnetically supported impeller.

Algorithms↗
PubMed2004

[High field MR imaging: magnetic field interactions of aneurysm clips, coronary artery stents and iliac artery stents with a 3.0 Tesla MR system].

PURPOSE: To evaluate magnetic field interactions of commonly used biomedical implants at 3.0 Tesla. MATERIALS AND METHODS: Fourteen aneurysm clips designed for permanent placement in intracranial aneurysms, 19 coronary artery stents and 20 iliac artery stents were evaluated in an actively shielded compact 3.0 T MR system (Intera, Philips Medical Systems, Best, The Netherlands, length of magnet 1.57 m). The magnetic deflection forces (translational movement) were evaluated as follows: The implants were suspended by a fine string and placed in the magnet bore at the location of the maximum magnetic field gradient. The translational forces F (z) were calculated from the measured angle of deflection from the vertical axis. The magnetic field-induced torque (rotational forces) was evaluated as follows: Each implant was placed in the center of the magnetic bore parallel to the static magnetic field B0 (position 0 degrees ). Any possible displacement of the implant was noted on a millimeter scale and any torque qualitatively evaluated using a 5 point grading scale (0: no torque; + 4: very strong torque). The implant was turned in steps of 45 degrees, and the procedure was repeated to encompass a full 360 degrees rotation. RESULTS: In 52 of the 53 devices tested, the deflection force (deflection angle: range 0-21 degrees, translational force: range 0-3.8 mN) was less than the gravitational force (i.e., the implant's weight). These devices (n = 52/53) did not show any alignment to or rotation in the magnetic field at any of the various 45 degrees -increment positions corresponding to a qualitative torque evaluation of grade 0/4. One device (n = 1/53), an iliac artery stent made of stainless steel (Zenith, Cook, Mönchengladbach, BRD), was found to have deflection forces (deflection angle 88 degrees translational force 299 mN) greatly exceeding the gravitational force as well as a pronounced torque (grade 4/4). CONCLUSION: Out of 53 biomedical implants evaluated for magnetic field interactions at 3.0 T, one iliac artery stent made of stainless steel was found to be potentially unsafe based on ASTM criteria. MR imaging at 3.0 Tesla may be performed safely in patients with any of the other 52 different implants evaluated in this study with respect to magnetic field translational attraction and torque.

Alloys↗
PubMed1991

Limitations of magnetic resonance imaging and ultrasound-directed (duplex) scanning in the diagnosis of subclavian vein thrombosis.

To investigate the potential role of magnetic resonance imaging and duplex scanning in the diagnosis of catheter-induced subclavian vein thrombosis, we correlated the results of 43 arm phlebograms with duplex scans; 28 of these phlebograms were also correlated with magnetic resonance imaging scans of the thoracic veins. Eighteen of the 43 phlebograms were normal, and all had normal magnetic resonance imaging and duplex studies. Eleven subclavian veins were totally occluded on phlebography; all had duplex scans, and five were also scanned with magnetic resonance imaging. Duplex scans detected 6 of 11 occlusions, whereas magnetic resonance imaging detected 4 of the 5 occlusions scanned. The five occlusions that were not detected by either magnetic resonance imaging or duplex scans were short segmental occlusions of the medial one third of the left subclavian vein. Of 14 nonocclusive thrombi seen on phlebography, duplex scans correctly identified 8. Magnetic resonance imaging was done on eight nonocclusive thrombi but identified only two. All abnormal findings on duplex scanning and magnetic resonance imaging were confirmed by phlebography. Short occlusions of the proximal portion of the left subclavian vein were often undetected by duplex scanning but occasionally seen with magnetic resonance imaging. Neither modality was sensitive to the presence of nonocclusive mural thrombi. Magnetic resonance imaging is highly reliable in ruling out the presence of a thrombotic process in the subclavian vein, but it may on occasion fail to detect the presence of subclavian thrombi. For this reason, in cases with suspected subclavian vein thrombosis magnetic resonance imaging cannot be used as the only diagnostic modality.(ABSTRACT TRUNCATED AT 250 WORDS)

Catheterization, Central Venous↗
PubMed1997

Clinical application of magnets in orthodontics and biological implications: a review.

Over the last decade magnets have been used in orthodontic and dentofacial orthopaedics and attempts have been made to evaluate the biological implications of magnets and magnetic fields during clinical application. This review aims to indicate the advantages and disadvantages of magnets in orthodontics and dentofacial orthopaedics over traditional techniques, and update related clinical experiences. The treatment of impacted teeth and Class II malocclusions by means of magnetic force is favoured and the correction of Class III and open bite malocclusions involving the use of magnets also appears promising. The advantages of magnets over traditional force delivery systems are: frictionless mechanics, when the magnets are in attractive configuration; predictable force levels, no force decay over time and less patient co-operation. However, the size of the magnets can increase the bulk of the appliance and three-dimensional control is limited when the magnets are in a repulsive configuration. In addition magnets used in vivo require a coating to prevent corrosion and the possible side effects of corrosive products.

Animals↗
PubMed1999

The physical characteristics of neodymium iron boron magnets for tooth extrusion.

Impaction and non-eruption of teeth is a common problem encountered in orthodontics and many techniques have been proposed for the management of this condition. It has been advocated that a system utilizing magnets would supply a continuous, directionally sensitive, extrusive force, through closed mucosa and thus provide not only a physiological sound basis for successful treatment, but also reduce the need for patient compliance and appliance adjustment. This ex vivo investigation examined in detail the physical characteristics of neodymium iron boron magnets employed in attraction in order to assess their usefulness in the clinical situation. Attractive force and magnetic flux density measurements were recorded for nine sets of magnet pairs with differing morphologies. The effect of spatial relationship on force was assessed by varying vertical, transverse and horizontal positions of the magnets relative to each other, and by altering the pole face angles. The data obtained suggest that magnets with larger pole face areas and longer magnetic axes provide the best performance with respect to clinical usefulness. It was possible to formulate a specific relationship between force and flux density for each magnet pair. This relationship can be used in the clinical management of unerupted teeth to predict the force between the magnets by measuring the magnetic flux density present at mucosal level. The results indicate that magnetic systems may, indeed, have a place in the treatment of unerupted teeth.

Biomechanical Phenomena↗
PubMed1997

Efficacy of magnetic resonance angiography in the evaluation of vascular malformations of the hand.

Conventional arteriography has been the accepted standard technique for demonstrating the anatomic details in vascular malformations of the hand. The technique of magnetic resonance angiography provides detailed anatomy for vascular anomalies of the hand without the use of an invasive technique or contrast enhancement. When magnetic resonance angiography is combined with magnetic resonance imaging, the extent of the lesion with respect to the surrounding tissues and the flow characteristics of the lesion can be determined noninvasively. In our institution, magnetic resonance angiography has replaced conventional arteriography as the technique of choice for the evaluation of these lesions. This report evaluates the efficacy of magnetic resonance imaging/ magnetic resonance angiography in the management of vascular malformations of the hand. Ten consecutive patients over 30 months (median age 37 years) underwent magnetic resonance imaging/magnetic resonance angiography evaluation after the clinical diagnosis of a vascular malformation of the hand was made. Four patients in the group had conventional arteriography performed before referral. Magnetic resonance imaging/magnetic resonance angiography clearly defined the anatomic extent of the lesion, its relationship to surrounding tissues, and the flow characteristics in each patient. In the four patients in whom conventional arteriography had been performed, the magnetic resonance angiography findings matched the arteriographic findings. On the basis of the magnetic resonance imaging/magnetic resonance angiography findings, six patients were treated nonoperatively with compressive garments and four patients had operative treatment (resection of lesion n = 2, digital ray resection n = 2). In this series, magnetic resonance imaging/magnetic resonance angiography was efficacious in the management of vascular malformations of the hand. This technique provides detailed images of both the arterial and venous components of the lesions without the requirements of contrast enhancement, ionizing radiation, or an invasive procedure. Furthermore, the resectability can be determined based on the extent of involvement and the flow characteristics.

Adolescent↗
PubMed1995

Can we distinguish between benign versus malignant compression fractures of the spine by magnetic resonance imaging?

STUDY DESIGN: The authors investigate the usefulness of magnetic resonance imaging in differentiating benign versus malignant compression fractures by reviewing patients and a fracture model in a canine model. OBJECTIVES: To determine the sensitivity and specificity of magnetic resonance imaging in differentiating benign versus malignant compression fractures of the spine and to obtain distinguishing features in magnetic resonance imaging. SUMMARY OF BACKGROUND DATA: The differentiation between benign and abnormal compression fractures of the thoracolumbar spine has important implications regarding patient treatment and prognosis. Plain radiographs, bone scans, and computed tomography are not accurate imaging modalities for this purpose. METHODS: Magnetic resonance imaging scans of 22 patients with confirmed lesions of the thoracolumbar spine were studied. There were 11 malignant and 11 benign lesions. Two experienced neuroradiologists blindly reviewed the magnetic resonance imaging scans and determined benign or malignant lesions. A canine study was performed to simulate a compression fracture model with a vertebral osteotomy in two dogs, and serial contrast-enhanced magnetic resonance imaging scans were performed 15, 30, 60 and 90 days after surgery. RESULTS: The correct interpretation between two neuroradiologists was 77% and 95%. The combined sensitivity rate was 88.5%, and the specificity rate was 89.5%. Magnetic resonance imaging reliably distinguished benign versus malignant lesions based on the anatomic distribution and intensity of signal changes of bone and adjacent tissues, contrast enhancement characteristics, and changes over time. Only one malignant lesion was misinterpreted by both neuroradiologists as benign, whereas there was one additional missed malignant lesion and three misinterpreted benign lesions by one radiologist. In the canine study, signal changes and enhancement were found 60 days after surgery, but no signal changes or enhancement were noted on the scan 90 days after surgery. CONCLUSIONS: Magnetic resonance imaging scans can detect malignant vertebral lesions early, but acute healing compression fractures may mimic the findings of metastatic lesions. The use of contrast-enhanced magnetic resonance imaging scans and serial magnetic resonance imagings are helpful for additional differentiation between benign and malignant compression fractures. In addition to magnetic resonance imaging scans, other diagnostic tests and clinical findings should be correlated before biopsy or surgery of the suspected lesion.

Adult↗
PubMed1997

The clinical use of magnetic resonance imaging in pyogenic vertebral osteomyelitis.

STUDY DESIGN: Retrospective chart review of 103 cases. OBJECTIVES: To describe the clinical use of magnetic resonance imaging in a pyogenic vertebral osteomyelitis. SUMMARY OF BACKGROUND DATA: Long delays in diagnosing pyogenic vertebral osteomyelitis of the spine have been shown in many reports. Magnetic resonance imaging has been advocated as the imaging method of choice in suspected spinal infections. The use, accuracy, and timing of magnetic resonance imaging in pyogenic vertebral osteomyelitis have not been reported in a large series. METHODS: In 103 patients with pyogenic vertebral osteomyelitis who underwent magnetic resonance imaging at or before the time of diagnosis, the author reviewed the clinical findings and results of the magnetic resonance imaging, timing with respect to symptom duration and diagnosis, and accuracy of readings in detecting spinal infection. Follow-up magnetic resonance imaging reports also were reviewed. RESULTS: Magnetic resonance imaging appeared to give the correct diagnosis or suggest pyogenic vertebral osteomyelitis as a possible diagnosis in 55% and 36% of cases, respectively, with less than 2 weeks of symptoms. After 2 weeks, the percentages of correct and possible diagnoses of pyogenic vertebral osteomyelitis increased to 76% and 20%, respectively. Magnetic resonance imaging was obtained within 1 month of the start of symptoms in 73% of cases. The diagnosis was made within 1 month in the most cases as well, compared with a 2- to 6-month delay in most series. Follow-up magnetic resonance images often gave impressions of progressive disease, where the clinical picture appeared to improve. CONCLUSIONS: Magnetic resonance imaging is valuable in suggesting the diagnosis even very early in the clinical course of pyogenic vertebral osteomyelitis. Its use may eliminate significant delays in diagnosis. The use of magnetic resonance imaging in following the therapeutic response remains to be defined.

Bacterial Infections↗
PubMed2005

Evaluation of rotator cuff tears with magnetic resonance arthrography.

The size and morphologic features of rotator cuff tears may influence treatment selection and affect final outcomes. Magnetic resonance arthrography allows observation of these features and other intraarticular structures. To assess the utility of magnetic resonance imaging in assessing size and morphologic features, we retrospectively reviewed observations on 41 shoulders in 37 consecutive surgically treated patients (mean age, 63.2 years) who had magnetic resonance imaging followed by magnetic resonance arthrography. The maximum rotator cuff defect size in the anteroposterior direction defined transverse size, and the maximum rotator cuff defect size in the mediolateral direction defined longitudinal size. Sensitivities for detecting full-thickness rotator cuff tears by magnetic resonance imaging and magnetic resonance arthrography were 90.2% and 100%, respectively. Maximum longitudinal and transverse dimensions of the tear as shown by magnetic resonance arthrography correlated better with intraoperative measurements (r2 = 0.85 transversely, 0.92 longitudinally) than magnetic resonance imaging measurements (r2 = 0.47 transversely, 0.26 longitudinally). The reproducibility of the two methods is similar. Magnetic resonance arthrography also allowed morphologic classification of the torn tendon as blunt end, tapering end, indistinct end, horizontal tear, and global tear. There was good agreement in classifying torn edges; the imaging findings agreed with findings at surgery. Magnetic resonance arthrography was more accurate in evaluating rotator cuff tear size and morphologic features than conventional magnetic resonance imaging.

Adult↗