Interactive atlas with magnetic resonance on CD-ROM for Macintosh

Computer assisted education in radiology has been increasingly used during the past ten years and now complements traditional learning resources. Magnetic Resonance Imaging (MRI) of musculoskeletal anatomy, and particularly of joints, lends itself naturally to learning modules on computer. This paper describes the design, development and use of an interactive computer assisted teaching module of MR joint anatomy on CD-ROM for Macintosh: to date, we have used this atlas for ankle and elbow anatomy. The atlas is divided into three main sections: MR anatomy, traditional anatomy and a quiz. On each MR image, any anatomical detail can be identified clicking on it with the mouse. Buttons allow to visualize cross-reference points and to go directly on the desired image. If the student wants to look at anatomical drawings of the last identified structure, a button retrieves all the cards in the traditional anatomy section containing that structure. Finally, the student can make his own self-assessment, verifying his learning immediately with the exam mode: the software makes a random selection of 10 MR images where an anatomical structure must be indicated: if the answer is wrong, the software gives the right one and shows the misinterpreted structure. Then, the student is given a total score for his performance. The computer assisted teaching modules present some advantages: the images can be viewed in a given sequence (like traditional learning resources) or in any self-paced, customized way; this possibility, together with the friendly interface of Macintosh computers could make learning more active and pleasant.     

Three-dimensional display of cardiac structures using reconstructed magnetic resonance imaging

It is sometimes difficult to understand the three-dimensional (3D) relationship of cardiac and mediastinal structures despite advances in magnetic resonance (MR) imaging techniques. We present a low-cost system for 3D reconstruction of the major mediastinal structures by processing the MR imaging data on a NeXT workstation. MR images of multisection, multiphase, spin-echo techniques stored in a picture archiving and communication system (PACS) data base were used for the reconstruction. The computer program obtained the contours of the multiple components of the mediastinal structures by the combination of automatic and manual procedure. The bundled software of a 3D kit was used for surface rendering of hidden surface removal, shading of the visible parts of the surfaces, perspective transformation, and motion parallax by rotation of the surfaces. 3D reconstruction was performed in 15 patients with cardiac diseases, and the 3D-reconstructed images were compared with the plain chest x rays of the patients. The 3D presentation clearly showed the complex anatomy of cardiovascular diseases and helped elucidate the misconceptions in the interpretation of the plain chest x rays. Our 3D images are used for education and should be viewed by medical students and beginners in radiology at an individual pace with plain chest radiographs, MR images, and legends. Although applied to the heart and the great vessels in this report, this system is also applicable to other structures.     

The GI Project: a prototype electronic textbook for high school biology

A prototype electronic science textbook for secondary education was developed to help bridge the gap between state-of-the-art medical technology and the basic science classroom. The prototype combines the latest in radiologic imaging techniques with a user-friendly multimedia computer program to teach the anatomy, physiology, and diseases of the gastrointestinal (GI) tract. The program includes original text, illustrations, photographs, animations, images from upper GI studies, plain radiographs, computed tomographic images, and three-dimensional reconstructions. These features are intended to create a stimulus-rich environment in which the high school science student can enjoy a variety of interactive experiences that will facilitate the learning process. The computer-based book is a new educational tool that promises to play a prominent role in the coming years. Current research suggests that computer-based books are valuable as an alternative educational medium. Although it is not yet clear what form textbooks will take in the future, computer-based books are already proving valuable as an alternative educational medium. For beginning students, they reinforce the material found in traditional textbooks and class presentations; for advanced students, they provide motivation to learn outside the traditional classroom.     

Correlative MR-anatomic study of the median nerve

OBJECTIVE: The purpose of our study was to evaluate the effectiveness of MR imaging for showing the intrinsic anatomy of a peripheral nerve. Cadaver wrist specimens that included the median nerve were imaged with MR imaging at 3 T, then sectioned, stained, and inspected grossly and microscopically. The size, shape, and signal intensity of the sheath and axonal structures in the median nerve were identified in MR images by comparison with anatomic sections. CONCLUSION: This study suggests that MR imaging with sufficiently high-resolution techniques shows the internal structure of peripheral nerves. These results suggest that MR imaging may be a means to distinguish neuritis, tumor, degeneration, or fatty proliferation in a peripheral nerve and to evaluate the nerve before microsurgical anastomosis.     

Double oblique MR images of the shoulder: comparison with conventional images

PURPOSE: Because the scapula is not only slanted on transverse sections but also inclines on sagittal section, we now perform shoulder MR imaging using double oblique images (DOI), which are planes perpendicular or parallel to the long axis of the scapula obtained with oblique sagittal scout imaging. The purpose of this study was to evaluate the usefulness of double oblique shoulder MR imaging. MATERIALS AND METHODS: MR images of shoulders with operatively or arthroscopically proven lesions (20 cases) that had been examined on both conventional images (CI) and DOI were retrospectively reviewed. DOI were compared with CI not only in terms of diagnostic performance but also in their ability to identify the details of shoulder anatomy. All MR studies were done with a shoulder coil on a high-field (1.5T) unit. RESULTS: Although the accuracy of DOI in diagnosing shoulder disorders such as rotator cuff tear and labrum injury was not as good as that of CI, DOI were better for identifying or discriminating muscles and tendons of the rotator cuff, labralbicipital junction and anterior band of the inferior gleno-humeral ligament, and for recognizing the correct position of the glenoid labrum. CONCLUSION: MR double oblique imaging of the shoulder provides more detailed information about shoulder anatomy and disorders than conventional imaging.     

Pulmonary embolism; lung scanning interpretation: about words

OBJECTIVE: The purpose of this study was to determine the prevalence and nature of a horizontal cleft in the posterior aspect of Hoffa's infrapatellar fat pad and to show pathologic processes involving this cleft. MATERIALS AND METHODS: Fifty consecutive MR imaging examinations of the knee were evaluated for the presence and appearance of a cleft in the infrapatellar fat pad. Examples of abnormalities involving the cleft were collected from additional MR studies. MR imaging, gross dissection, and histologic examination of a cadaveric knee were also performed to evaluate the anatomy and histology of the cleft. RESULTS: The cleft in the infrapatellar fat pad was revealed on MR imaging in 45 of 50 knees and had a variable shape, either linear (82%), pipe-shaped (7%), or globular-shaped (11%). Joint effusion or anterior cruciate ligament tear did not affect the appearance of the cleft. The cleft was located anterior to the distal insertion of the anterior cruciate ligament on the tibia. At gross dissection of the cadaveric knee, the roof of the cleft was formed by the ligamentum mucosum (infrapatellar plica), and the cleft was lined with synovium. The prospective evaluation of additional MR imaging examinations of the knee revealed pathologic entities of the cleft such as ganglion cysts, loose bodies, nodular synovitis, and amyloid. CONCLUSION: A horizontal cleft located in the posterior aspect of the infrapatellar fat pad is a common and normal MR imaging finding with a prevalence of 90%. The horizontal cleft is lined with synovium and its roof is formed by the ligamentum mucosum (infrapatellar plica). This cleft communicates with the knee joint. A distended cleft can form a prominent recess mimicking pathologic processes; conversely, disorders can arise in the cleft.     

MR pancreatography: a useful tool for evaluating pancreatic disorders

Magnetic resonance (MR) pancreatography is being used with increasing frequency as a noninvasive alternative to diagnostic endoscopic retrograde pancreatography in the evaluation of the pancreatic duct and various pathologic conditions of the pancreas. This recently developed technique allows improved spatial resolution and permits imaging of the entire pancreatico-biliary tract during a single breath hold. MR pancreatography can help identify the course and drainage pattern of the pancreatic duct and is useful in diagnosing congenital anomalies such as pancreas divisum and annular pancreas without the risk of inducing pancreatitis. In some instances, MR pancreatography may demonstrate duct disruption and associated fluid collections resulting from trauma. In recurrent acute pancreatitis, MR pancreatography is useful in suggesting the cause of the disease; in chronic pancreatitis, it is useful in depicting ductal anatomy, detecting strictures or intraductal calculi prior to surgery, and detecting complications such as pseudocysts and fistulas. In addition, MR pancreatography performed in conjunction with abdominal MR imaging is useful in identifying pancreatic malignancies as well as in establishing resectability and preventing unnecessary preoperative stent placement.     

MR imaging of the corpus callosum

The corpus callosum is the major axonal commissure of the brain, connecting the two cerebral hemispheres and providing communication between the cortical and subcortical neurons. With MR imaging in the sagittal plane, the corpus callosum can be depicted in great detail. We review the normal anatomy, development, and process of myelination of the corpus callosum. The MR features of various pathologic conditions involving the corpus callosum are described. Finally, we discuss the evolving role of MR imaging in neuropsychiatric diseases with respect to the corpus callosum.     

Fetal fast MR imaging: reproducibility, technical quality, and conspicuity of anatomy

PURPOSE: To evaluate the normal appearance of fetal anatomy, the conspicuity of fetal organs, the reproducibility of images, and the limitations to image quality with the use of half-Fourier, single-shot rapid acquisition with relaxation enhancement (RARE) magnetic resonance (MR) imaging. MATERIALS AND METHODS: Fifty-four fetuses of 49 pregnancies underwent MR imaging with the half-Fourier, single-shot RARE technique. Two reviewers attempted to identify 47 organs and anatomic regions in each fetus. Organ or region conspicuity, image quality, and the limitations of image quality were graded. RESULTS: Fetal anatomy was well depicted in fetuses over 20 weeks in gestational age. Fetal imaging was limited by gestational age of 20 weeks or less usually owing to the small size of the organ or region being evaluated and, less frequently, by motion. CONCLUSION: Half-Fourier, single-shot RARE MR imaging provided a detailed and reproducible evaluation of normal fetal anatomy, which can be used as a standard of reference in MR imaging of fetal anomalies.     

The normal and pathologic ischiorectal fossa at CT and MR imaging

A wide spectrum of disease processes involve the ischiorectal fossa, including congenital and developmental lesions; inflammatory, traumatic, and hemorrhagic conditions; primary tumors; and pathologic processes outside the ischiorectal fossa with secondary involvement. Both computed tomography (CT) and magnetic resonance (MR) imaging are useful in the definitive diagnosis of these pathologic conditions, with MR imaging being the modality of choice because of its superior contrast resolution and multiplanar capability. In Gartner duct cyst, both CT and MR imaging demonstrate a well-defined, round mass; in tailgut cyst, CT demonstrates a well-defined retrorectal mass with a solid or cystic appearance. MR imaging in particular plays a major role in the assessment of fistula in ano, infection, and hematoma. Lipoma and pelvic plexiform neurofibroma typically have low attenuation and high signal intensity at CT and MR imaging, respectively. Recurrent rectal tumor appears at both modalities as an irregular soft-tissue mass with or without central necrosis in the presacral space, perineum, or pelvic sidewall. Familiarity with the imaging features and differential diagnoses of various ischiorectal pathologic processes will facilitate prompt, accurate diagnosis and treatment.     

Segmentation of multispectral magnetic resonance image using penalized fuzzy competitive learning network

Segmentation (tissue classification) of the medical images obtained from Magnetic resonance (MR) images is a primary step in most applications of computer vision to medical image analysis. This paper describes a penalized fuzzy competitive learning network designed to segment multispectral MR spin echo images. The proposed approach is a new unsupervised and winner-takes-all scheme based on a neural network using the penalized fuzzy clustering technique. Its implementation consists of the combination of a competitive learning network and penalized fuzzy clustering methods in order to make parallel implementation feasible. The penalized fuzzy competitive learning network could provide an acceptable result for medical image segmentation in parallel processing using the hardware implementation. The experimental results show that a promising solution can be obtained using the penalized fuzzy competitive learning neural network based on least squares criteria.     

The use of a computerized brain atlas to support knowledge-based training in radiology

Trainers of radiologists face the particular challenges of teaching normal and abnormal appearance for a variety of imaging modalities, providing access to a large appropriately-indexed case library, and teaching a consistent approach to the reporting of cases. The computer has the potential to address these issues, to supplement conventional teaching of radiology by providing case-based tutoring and diagnostic support based on a large library of images of normal and abnormal anatomy, described in a consistent terminology. The paper presents a new approach to computer-based training in radiology that combines a knowledge-based tutor with an on-line medical atlas. It describes two existing computer systems, the MR Tutor and ATLAS, and discusses the medical, computational, epistemic, and pedagogic issues involved in developing a combined Atlas-Tutor. Integrating an atlas with a training system could significantly improve the teaching and support offered, but practical difficulties include the need to merge knowledge representations and to incorporate techniques for registering atlas plates on images that exhibit abnormalities. The paper addresses these problems, and concludes by indicating how the Atlas-Tutor might be employed in practical radiology training.     

Concentrations, biomagnification and spatial variation of organochlorine compounds in a pelagic food web in the northern part of the Baltic Sea

A computer program, BrainView, is presented which has been developed to reconstruct, visualize, and evaluate three dimensional (3D) biological and medical imaging data, such as images from histological sections, confocal microscopy, or magnetic resonance tomography. The program allows the simultaneous display of three orthogonal sectional planes, i.e. the horizontal, frontal, and sagittal planes, of reconstructed data and to move interactively through the brain to optimally assess the 3D data set. Furthermore, any arbitrary sectioning plane through a data set can be visualized. Implemented warping algorithms allow the geometric normalization of data sets of different animals, modalities or developmental stages as a preprocessing for the comparative evaluation of the data. For a quantitative analysis, data sets can be segmented based on equal grey levels and the corresponding equidensities were calculated. The program works on Apple-Macintosh computers and has a user-friendly graphical interface. The BrainView program is discussed in comparison to related programs.     

Transdermal oestrogen reduces daytime blood pressure in hypertensive women [see comment

A complex system of connective-tissue septa within the orbit has previously been described in serial histologic sections. The present study describes the anatomy of the orbital connective tissue system on high-resolution magnetic resonance (MR) images in vivo. Five volunteers aged 26 to 35 year underwent magnetic resonance imaging of the orbit on a 1 Tesla unit (Impact, Siemens, Germany). T1-weighted coronal images were obtained using a surface coil. Anatomical structures on the MR images were identified by comparison with corresponding histologic sections. On MR images of the anterior orbit, the levator aponeurosis, Lockwood ligament, transverse intermuscular ligament, common sheath, check ligaments, Tenon capsule, intermuscular septa, and palpebral ligaments can be seen. In the mid- and posterior orbit, the intermuscular orbital septa, especially the superolateral septum, the superior ophthalmic vein hammock, and septa of the radial connective tissue system are visualized. High-resolution magnetic resonance imaging is capable of delineating the major septa of the orbital connective tissue system.     

Global phylogeography of the ridley sea turtles (Lepidochelys spp.) as inferred from mitochondrial DNA sequences

BACKGROUND: The cardiovascular applications of magnetic resonance (MR) techniques in coronary artery disease have increased considerably in recent years. Technical advantages of MR imaging are the excellent spatial resolution, the characterization of myocardial tissue, and the potential for three-dimensional imaging. These characteristics allow the accurate assessment of left ventricular mass and volume, the differentiation of infarcted from normal tissue, and the determination of systolic wall thickening and regional wall motion abnormalities. METHODS: In addition to the conventionally used spin-echo and cine-echo techniques, newer techniques such as myocardial tagging, ultrafast MR imaging and MR coronary angiography have been developed. These newer techniques allow a more accurate assessment of ventricular function (tagging), myocardial perfusion (ultrafast imaging), and evaluation of stenosis severity (MR coronary angiography). Particularly early detection and flow assessment of stenosed coronary arteries and bypasses by MR angiography would constitute a major breakthrough in cardiovascular MR imaging. Apart from the MR imaging techniques, cardiac metabolism may be well assessed using MR spectroscopy. This provides unique information on the metabolic behaviour of the myocardium under conditions stress-induced ischemia. However, the definite niche of cardiac MR spectroscopy has still to be settled. CONCLUSION: Currently, MR techniques allow the evaluation of anatomy and function (accepted use), perfusion and viability (development phase), and coronary angiography (experimental phase). A particular strength of MR imaging is that one single MR test may encompass cardiac anatomy, perfusion, function, metabolism and coronary angiography. The replacement of multiple diagnostic tests with one MR test may have major effects on cardiovascular healthcare economics and would outweight the cost inherent to the MR angiography procedure.     

T-cell regeneration: all repertoires are not created equal

BACKGROUND: The most common objective manifestations of pituitary adenoma are visual, including impairment of a visual field and loss of acuity. The characteristic visual field defect caused by pituitary adenomas with suprasellar extension is bitemporal hemianopsia. The present study was undertaken to determine the relationship between a visual field defect and the chiasma compression caused by pituitary adenomas. METHODS: Between January 1994 and December 1996 within the Department of Neurosurgery at the Neurological Institute of Veterans General Hospital-Taipei, 70 patients with pituitary adenoma were selected. Their medical records and radiological films were reviewed. The qualified visual field scores were compared with the chiasma compression levels measured from computed tomography, sagittal and coronal magnetic resonance (MR) imaging. The relationships of pathological diagnosis as well as history of prior operations with visual field defect score were also evaluated. RESULTS: patients with a pathological diagnosis of a non-functional pituitary adenoma or with a history of prior operation for the pituitary adenoma had the more severe visual field defect. The chiasma compression level, no matter measured from computed tomography, sagittal MR or coronal MR imaging, was correlated significantly with the visual field defect. The correlation coefficient was 0.764 from computed tomography, 0.688 from sagittal MR imaging, and 0.717 from coronal MR imaging. The visual field defect was present mostly when the chiasma compression exceeded a certain level when measured from computed tomography, sagittal MR and coronal MR imaging. On the other hand, variation in chiasma type had little effect on the appearance and degree of a visual field defect. CONCLUSIONS: There was a linear correlation between a visual field defect and the chiasma compression no matter whether measured from computed tomography or from MR imaging. The visual field defect occurred mostly when the chiasma compression exceeded a certain level. A more severe visual field defect appeared in patients with nonfunctional pituitary adenoma or those with a prior operation history for the pituitary adenoma.     

Smoking and Parkinson''s disease: a dose-response relationship

BACKGROUND: Previous studies questioned the link between early childhood anemia and detrimental child development. OBJECTIVE: A population-based study was conducted to examine the association between early childhood anemia and mild or moderate metal retardation at 10 y of age. DESIGN: The present study linked early childhood nutrition data collected by the Special Supplemental Program for Women, Infants, and Children (WIC) and school records. Hemoglobin values were used to determine the relation between anemia in early life and children's placement in special education classes for mild or moderate mental retardation. Subjects were all participants in the WIC program. A computer program was used to link data from birth, WIC, and school records. RESULTS: Logistic regression showed an increased likelihood of mild or moderate mental retardation associated with anemia, independent of birth weight, maternal education, sex, race-ethnicity, the mother's age, or the child's age at entry into the WIC program. CONCLUSION: These findings support the proposition that efforts to prevent mild and moderate mental retardation should include providing children with adequate nutrition during early childhood.     

Visualization of the topographical structure of the anesthetized mouse brain by MR microimaging

A nuclear magnetic resonance (NMR) spectrometer equipped with a magnet producing a high and extremely uniform magnetic field (7.05 T) was combined with a strong field gradient coil (3.5 mT/cm) and applied to MR microimaging of the mouse brain to visualize its topographical structure. Since the proton-density-weighted condition (long repetition time (TR) and short echo time (TE); TR/TE = 3,000 ms/10.4 ms) was found to be the most suitable for imaging the mouse brain, mid-sagittal and coronal sections in 1-mm- or 0.3-mm-thick slices were imaged according to the multislice spin echo sequence with 2 or 8 acquisitions, a 2 kHz pulse width and a 256 x 256 data matrix. As expected, the resolution of MR microimaging was comparable to that of the histological sections. The white matter especially, could be distinguished from the gray matter in some regions of the brain. Coronal sections of the brain also showed that the hippocampal CA1-CA3 regions were distinguishable from the other regions. The results suggested that the present MR microimaging technique might be a useful tool for the study of topological anatomy and submicroscopic research using brains of small laboratory animals.     

MR imaging and MR angiography in the diagnosis of dural arteriovenous fistulas

Intracranial DAVFs are most commonly found in the cavernous, transverse, and sigmoid sinuses. MR imaging and MR angiography can be used to screen for these lesions and determine if there is cortical venous drainage. Conventional angiography still has a major role in screening and is mandatory prior to any therapy. Spinal DAVFs are uncommon lesions seen predominantly in older men. The diagnosis can be suspected with MR imaging if a large draining vein is seen in association with swelling and enhancement of the conus and increased signal on T2-weighted images. MR angiography shows some promise in identifying the vascular anatomy of these lesions.     

Magnetic resonance techniques in the evaluation of the newborn brain

MR imaging provides unequaled sensitivity as compared with US or CT scanning for evaluating developmental changes and pathologic processes in the newborn brain. Myelination can be assessed qualitatively and quantitatively using newer 3D-MR imaging methods. MR imaging provides a much clearer delineation of many developmental disorders, including anomalies of migration and organization, as well as a variety of metabolic disorders and congenital infections. Neonatal intracranial hemorrhage is detected in all its locations by MR imaging. The timing of the hemorrhage is a unique feature of MR imaging. Venous thrombosis also can be identified by MR imaging and confirmed with MR angiography. HIE is the major cause of potentially preventable or reversible brain injury that results in considerable long-term neurologic morbidity. Early detection is crucial for interventions aimed at preventing or reversing ongoing injury. DWI can show early changes at the cellular level that are not detectable by any other imaging modality. MR spectroscopy has further opened the possibility of studying the metabolic mechanisms that define the pathophysiologic events taking place in neonatal brain injury. Both 31P-MR spectroscopy, as a marker of the acute changes in energy metabolism, and 1H-MR spectroscopy, with the measurement of lactate and the excitotoxic aminoacids glutamate and glutamine, have enabled us to study the early and late effects of insults to the newborn brain in a noninvasive fashion. Studies performed to determine the predictive value of MR spectroscopy for later neurodevelopmental outcome after HIE have shown promising results but need further evaluation on larger patient samples. The potential use of these methods in the evaluation of early neuroprotective treatment regimens in the newborn remains to be determined.