Lack of interaction between magnetic resonance imaging and the copper-T380A IUD.

To determine if the CuT380A (ParaGard) IUD is affected by magnetic resonance imaging (MRI), in vitro studies utilizing a CuT380A IUD (ParaGard), a copper-bearing IUD, and a Signa 1.5T HR system were used to evaluate whether the dynamic magnetic forces generated by the MRI resulted in movement, torque, or heat when the IUD was exposed to the magnetic field generated by the MRI. There was no deflection, turning motion (torque), or temperature change when the IUD was exposed to a magnetic field. There appears to be no reason to exclude women with IUDs of the type examined from an MRI system or its environs.

Frameless 3D volume registration of MR data sets for stereotactic pallidotomy.

Frameless 3D volume registration of Magnetic Resonance (MR) and computed (CT) data sets has been described by Kummar et al. [11]. Its use in 3D volume registration for stereotactic planning in patients undergoing pallidotomy is presented. Pre-operative examinations with the stereotactic frame and postoperative examinations without the stereotactic frame can be co-registered and reviewed for accuracy of planned and lesional coordinates.

Greater residual vision in monkeys after striate cortex damage in infancy.

1. Monkeys with large unilateral surgical ablations of striate cortex, sustained either in adulthood or at 5-6 wk of age, were trained on an oculomotor detection and localization task and tested with visual stimuli in the hemifields ipsilateral and contralateral to the lesion 2-5 yr after surgery. 2. Monkeys with lesions sustained in adulthood were largely unable to detect stimuli in the hemifield contralateral to the lesion, with only one monkey showing recovery toward the end of testing. Monkeys with lesions of striate cortex made in infancy, however, each showed residual detection capacity at the beginning of testing and improved to near normal by the end of testing. 3. Each of the monkeys showing a residual ability to detect within the contralateral hemifield was also able to localize visual targets with eye movements. 4. These findings demonstrate that the vision surviving striate cortex damage in primates is more robust after early damage as has been shown to be the case for primary somatosensory, motor, and association cortex.

Intracranial route of a cervical neuroblastoma through skull base foramina.

A case of primary cervical neuroblastoma gaining access to the cerebellopontine angle via direct perineural spread is described. MRI effectively delineated soft tissues, while CT demonstrated tumor calcifications and the integrity of adjacent bones. Both imaging modalities were beneficial in predicting the unique histology and pattern of disease confirmed at surgery.

Radiology on the information superhighway.

PURPOSE: To explore the potential for the information superhighway to provide radiologists with new opportunities. MATERIALS AND METHODS: The Internet was used as the communication and distribution medium. MOSAIC, a graphical interface, provided access for clients, and a computer was used to serve text, images, sound, and cine onto the Internet. RESULTS: The system can be used to send reports and images to referring physicians or consulting radiologists; to provide a large database that is constantly available; to provide an increasing collection of teaching files; and to distribute interactive, multimedia teaching tools that can be used on any computer system. The use of the MOSAIC interface facilitates interaction, which allows users with limited computer experience to access the system. CONCLUSION: The Internet can dramatically expand the ways radiologists interact with their colleagues. These preliminary results indicate that there will be great challenges and opportunities for improving care and teaching in the future.

Knowledge-based medical image analysis and representation for integrating content definition with the radiological report.

Technology breakthroughs in high-speed, high-capacity, and high performance desk-top computers and workstations make the possibility of integrating multimedia medical data to better support clinical decision making, computer-aided education, and research not only attractive, but feasible. To systematically evaluate results from increasingly automated image segmentation it is necessary to correlate them with the expert judgments of radiologists and other clinical specialists interpreting the images. These are contained in increasingly computerized radiological reports and other related clinical records. But to make automated comparison feasible it is necessary to first ensure compatibility of the knowledge content of images with the descriptions contained in these records. Enough common vocabulary, language, and knowledge representation components must be represented on the computer, followed by automated extraction of image-content descriptions from the text, which can then be matched to the results of automated image segmentation. A knowledge-based approach to image segmentation is essential to obtain the structured image descriptions needed for matching against the expert's descriptions. We have developed a new approach to medical image analysis which helps generate such descriptions: a knowledge-based object-centered hierarchical planning method for automatically composing the image analysis processes. The problem-solving steps of specialists are represented at the knowledge level in terms of goals, tasks, and domain objects and concepts separately from the implementation level for specific representations of different image types, and generic analysis methods. This system can serve as a major functional component in incrementally building and updating a structured and integrated hybrid information system of patient data.(ABSTRACT TRUNCATED AT 250 WORDS)

Convex third ventricle: a possible sign for dementia using MRI.

The shape and thickness of the third ventricles were studied with magnetic resonance imaging in 46 patients under evaluation for memory impairment. We compared this population with 23 subjects imaged for other reasons. The study group consisted of patients with diagnoses of probable dementia of the Alzheimer's type (DAT; 35.6%), multi-infarct dementia (MID; 22.2%), depression (8.9%), alcoholic dementia (6.7%), other dementias (OD; 13.2%) and no dementia (6.7%). Within the study group, there were no significant differences across diagnostic categories for duration of symptoms or level of education. Patients with DAT were, however, more impaired than others (Mini-Mental State Examination scores: DAT 14.6 [+/- 8.2] versus MID 17.4 [+/- 6.2] versus OD 21.2 [+/- 6.4]). Demented subjects were more likely than nondemented individuals to have a convex third ventricle and greater wall separation. The results suggest that the shape of the third ventricle may correlate with dementia. Possibly, the dorsal medial nucleus of the thalamus is involved in the dementia.

In-vitro assessment of the behavior of magnetic resonance angiography in the presence of constrictions.

RATIONALE AND OBJECTIVES: Time-of-flight magnetic resonance angiography (TOF/MRA) is increasingly used to assess the nature and severity of stenotic blood vessels. Flow artifacts associated with high flows and/or narrow constrictions may confuse the interpretation of these studies. Accurate TOF/MRA evaluations demand an understanding of the nature of these flow effects. METHODS: A two-dimensional TOF pulse sequence was used to acquire images of five smoothly constricted phantoms at various flows. Analysis included assessment of phantom appearance and quantification of apparent constriction diameter and signal variations. RESULTS: Most notable flow phenomena were a cone-shaped region of high signal, a region of signal void, and signal preservation along the wall. When visible, constriction diameter was accurately measured. CONCLUSIONS: The behavior observed in TOF/MRA images can be understood by considering the contributing mechanisms of phase dispersion, turbulence, poststenotic flow eddies, flow reversal, and flow separation.

Magnetic resonance imaging of the rabbit knee: detection of cartilage proteoglycan degradation.

Intra-articular (i.a.) injection of papain causes a reversible loss of proteoglycan in intact rabbit knees. Twelve rabbits were scanned with magnetic resonance imaging (MRI) at 0, 24, 48 and 72 hours after 5 units of papain i.a. in a 1.5 Tesla Signa with a three inch surface coil using spin echo sequence. Total cartilage thickness in proton density images was 1.08 +/- 0.09 mm prior to papain injection. The magnetic resonance images showed a reduction in articular cartilage thickness in papain-treated rabbit femurs at 24 hours to 0.69 +/- 0.18 mm and partial restoration by 72 hours to 0.77 +/- 0.21 mm.

The use of magnetic resonance imaging in the study of edema.

A method of studying edema using magnetic resonance imaging (MRI) is presented. Three patients with lower extremity edema due to congestive heart failure were imaged with a 0.6 tesla system before and after diuresis. Edge detection algorithms were utilized to precisely outline regions of interest for quantification. Water and nonwater elements were separated within the region of interest to quantify water content. The results show that: (1) Edema can be quantified by use of MRI. (2) Subcutaneous edema is distributed along defined planes (ie, nonuniformly). (3) Increased water content is present not only in the subcutaneous tissue but also in deeper lying muscle.

Magnetic resonance imaging reflects cartilage proteoglycan degradation in the rabbit knee.

Cartilage degeneration in osteoarthritis is initiated by a loss of proteoglycan. Intra-articular injection of papain causes a reversible loss of proteoglycan in rabbit knees. Rabbits were scanned with magnetic resonance imaging (MRI), using a 1.5T Signa superconducting magnet with 3 inch surface coil. Spin echo sequences were performed in the coronal and sagittal planes at 0, 24, 48, and 72 h after intra-articular injection of papain to obtain T1, proton density, and T2-weighted images. Cartilage proteoglycan content was measured biochemically and histochemically. Reduced articular cartilage thickness in the MR images of papain-treated knees corresponded to changes in cartilage proteoglycan content.

Automatic generation of plans for biomedical image interpretation.

This paper presents a new object-centered, goal-driven planning approach to biomedical image interpretation. We describe here a prototype system which takes advantage of spatial and detectability constraints from an expert-derived model of expected anatomical structures to automatically generate plans for the interpretation of multimodality images.

MRI evaluation of left ventricular hypertrophy in a canine model of aortic stenosis.

The progression of ventricular myocardial mass in nine puppies with experimental left ventricular hypertrophy and three controls was observed over a period of 7 months using magnetic resonance imaging (MRI). Left ventricular hypertrophy was created by surgically induced aortic stenosis when the puppies were 1 month old. Quantification of the progression of the left ventricular mass due to aortic stenosis as compared to the controls of similar age was then performed during the subsequent 7 months. Cardiac gated spin-echo technique was used for the imaging of the heart. Novel edge detection techniques were applied for automated identification of the border of the myocardium for measurement. Methods for correction of partial volume effect were applied in the analysis of the data. Clear-cut differences in myocardial mass (P less than .001) and in radius-to-wall thickness ratio (r/h, P less than .02) between puppies with aortic stenosis and controls were observed. The differences in end-diastolic volume between the two groups, however, were significant during the initial phase of hypertrophic compensation (P less than .001) and insignificant (P greater than .05) during the long-term phase of hypertrophic compensation. The results demonstrated that MRI is applicable in serial assessment of myocardial hypertrophy.

Image processing on Macintosh II: a practical boundary finding algorithm for biomedical measurement.

With increasing research interest in displaying and analyzing biomedical images, a practical personal computer based off-line image processing software would be useful. This paper describes the implementation of an image processing work station on a Macintosh II which features a novel edge detection capability useful for biomedical measurement. The boundary finding algorithm is coded in Turbo Pascal, and operates at a speed comfortable for interactive operation. Depending on the complexity of the problem, it usually takes less than a minute for the measurement of an image. The edge detection algorithm has an built-in edge detector with decision-making capability, and can be efficiently controlled by a mouse. In this way, the local accuracy of an automatic edge detection operator, and the global accuracy of the human eye (through manual control of a mouse) are combined.

Clinical and research applications of magnetic resonance imaging.

In medicine, as in science and engineering, magnetic resonance imaging has become an invaluable tool; in certain applications it has already become the preferred diagnostic technique. The author briefly reviews the principles of magnetic resonance as they apply to diagnostic imaging, describes several of the more important clinical applications of the technology, and discusses some areas of investigation that may lead to future medical imaging uses.

Strip scan: a method for faster MR imaging.

In certain limited applications, one can reduce MR imaging time without loss of essential diagnostic information by limiting the field of view.

New technique for ultrasound imaging.

A new system of ultrasonic imaging has been developed which utilizes optical interferometry. This system has a broad frequency range, wide angular response, and good resolution. Operation of the system and the results of experimental imaging are described. Application of this technique to the evaluation of in vitro tissue specimens demonstrates its capability for characterization of ultrasonic tissue properties.