Infertility profile at King Edward VIII Hospital, Durban, South Africa

Interventional MRI is one of the most recent developments of clinical MR imaging. Because of the development of open MR systems and very compact high-field systems, a number of interventional procedures are already possible today under MR control and will be tested in experimental and clinical investigations. The currently commercially available systems differ with respect to their static magnetic field strength, their gradient systems and patient access. In addition, there are differences concerning their space requirements and costs. All systems have components facilitating interventional procedures. In this article we discuss the advantages and shortcomings of these commercially available systems and look at future developments in interventional MR equipment.     

Neuroimaging in multiple sclerosis

Neuroimaging in multiple sclerosis is now dominated by MR imaging. This article will focus primarily on conventional MR imaging studies in multiple sclerosis, but will also discuss briefly some of the more recent advances related to MR imaging. Fast spin-echo imaging, fluid attenuated inversion recovery MR studies, three-dimensional volumetric studies, magnetization transfer, and magnetic resonance spectroscopy as it applies to multiple sclerosis are examined.     

New and future developments in cerebrovascular ultrasound, magnetic resonance angiography, and related techniques

Four-dimensional (4D) analysis of atherosclerotic plaque and wall motion, the application of 4D ultrasound to the study of atherogenesis, and the incorporation of ultrasound data into flow models for simulation of cerebrovascular hemodynamics are new frontiers in diagnostic ultrasound that use computer vision and optical flow techniques to exploit the full potential of real-time imaging and Doppler studies. New approaches to improve blood vessel delineation with ultrasound include application of contrast agents, harmonic imaging, and red blood cell density imaging. An assessment of the potential clinical utility of these new developments in cerebrovascular ultrasound requires an analysis of comparable trends in magnetic resonance (MR) technology, eg, rapid advances in the fields of MR angiography, dynamic contrast-enhanced MR, and MR diffusion imaging. Likewise, the value of ultrasound techniques for the measurement of blood flow to evaluate cerebrovascular hemodynamics must be compared to related methods in magnetic resonance, such as dynamic MR inflow tracking. This article addresses several new and future developments in cerebrovascular ultrasound and discusses their relative merits in terms of ongoing research in the field of magnetic resonance angiography, imaging, and related techniques.     

Rapid identification of up to three Candida species in a single reaction tube by a 5'' exonuclease assay using fluorescent DNA probes

OBJECTIVE: The objective of our investigation was to determine whether an MR imaging system designed to obtain images of the extremities affects the safety and functionality of pacemakers or that of implantable cardioverter defibrillators (ICDs). MATERIALS AND METHODS: Ex vivo experiments were conducted in which seven pacemakers and seven ICDs were exposed to a 0.2-T extremity MR imaging system. Magnetic field attraction was assessed at three positions relative to the MR imaging system. In addition, the devices were placed into a test apparatus that was oriented parallel and perpendicular relative to the MR imaging system while imaging was performed on a phantom using T1-weighted spin-echo and gradient-echo sequences. Various functional aspects of the pacemakers and ICDs were evaluated before, during (pacemakers only), and after MR imaging. RESULTS: Magnetic field attraction was relatively minor for all devices. The quality of the MR images was unaffected by the devices. Operation of this MR system did not alter any of the functional aspects of the pacemakers or ICDs evaluated in this study. CONCLUSION: According to these data and in consideration of how patients are positioned during examinations--that is, positioned so that the thorax (where the pacemaker or ICD and the corresponding leads are located) does not enter the magnet bore--the results suggest that it should be safe to perform MR imaging in patients with the pacemakers and ICDs evaluated in this study.     

Relative body weight and self-esteem among African Americans in four nationally representative samples

Since the emergence of magnetic resonance (MR) imaging, its clinical applications have seen a logarithmic growth. The advantage of MR imaging is that it offers a vast amount of important clinical information with minimal risk to the patient, and promises to reduce the need for angiographic studies with their attendant morbidity and mortality. We review the applications and recent advances of MR imaging to include coronary imaging of native, bypassed and stented vessels, carotid arteries, peripheral arteries, and the aorta. In addition, we discuss issues of patient preferences and the future directions of MR imaging. We predict that the clinical utility of MR angiography will grow with refinements that will improve speed, resolution, and even the use of spectroscopy to characterize plaque.     

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.     

Common bile ductal carcinoma, hilar cholangiocarcinoma: evaluation with MR cholangiography

Recently, imaging of bile ductal carcinoma has been improved by new techniques such as MR cholangiography. Cancer invasion along the bile duct has been demonstrated by MR cholangiography. MR cholangiography will be useful for obtaining more detailed information in the diagnosis and staging of common bile ductal carcinoma, hilar cholangiocarcinoma.     

Recurrence risk of a serious, noninherited chromosomal abnormality

The elbow has proven the most technically challenging of all of the major joints in MR imaging, particularly with regard to radiofrequency design. It is possible to obtain high-quality diagnostic studies on most clinical MR imaging systems that are made today using available coils and pulse sequences. This article evaluates techniques for MR imaging of the elbow.     

MR imaging and cervical fixation devices: evaluation of ferromagnetism, heating, and artifacts at 1.5 Tesla

The purpose of this study was to assess ferromagnetism, heating, and artifacts for cervical fixation devices exposed to a 1.5 T MR system. Cervical fixation devices (three halos, one tong and two halo vests) were evaluated for compatibility with MR procedures. Ferromagnetism was determined using a previously described technique. Heating was evaluated by measuring temperatures at various positions on the cervical fixation devices while applied to a volunteer subject before and during the use of various pulse sequences, including an magnetization transfer contrast (MTC) sequence. Artifacts associated with routine clinical MR imaging of the cervical spine were qualitatively evaluated with the cervical fixation devices applied to a volunteer subject. None of the devices displayed attraction to the magnetic field. The temperature changes were +/-1.5 degrees C in each instance. The MTC pulse sequence produced a sensation of "heating" the skull pins that may have been caused by vibration of the cervical fixation device. The MR images of the cervical spine were obtained without apparent artifacts using each routine, clinical pulse sequence. The lack of ferromagnetism, negligible heating, and capability of obtaining diagnostically acceptable studies of the cervical spine indicate that MR imaging performed at 1.5 T or less may be conducted safely in patients with each of the cervical fixation devices tested using conventional pulse sequences.     

Advances in abdominal MR imaging

Major technical advances in MR imaging have led to its wider use in the evaluation of abdominal disease. The principle new pulse sequence is the RARE sequence for T2-weighted imaging. Multishot and breath-hold single-shot RARE techniques are now widely used, and both have performed as well as conventional spin-echo imaging with far shorter acquisition times. The most notable improvements have been in the detection and characterization of hepatic lesions. Two liver-specific contrast agents received FDA approval during 1997: SPIO particles or ferumoxide and mangafodipir trisodium, a hepatocyte-specific agent. Both of these agents provide considerable benefit in the detection and characterization of hepatic lesions. Manganese enhancement has also proved useful in MR imaging of the pancreas, although fat-suppressed T1-weighted imaging with dynamic gadolinium enhancement has also yielded results comparable with those of contrast-enhanced CT. MR hydrography, a generic term for static fluid imaging, is another derivative of RARE fast T2-weighted imaging. MRCP, the best known example of MR hydrography, has been rapidly and widely employed as a primary method for imaging the biliary and pancreatic ducts and has become competitive with ERCP. MR vascular imaging, especially portal venography, has been used for noninvasive imaging of portal venous disease in Budd Chiari disease, before placement of transjugular intrahepatic portosystemic shunts, and for pancreatic cancer staging. Finally, the development of conventional phased-array body coils and endorectal coils has enabled high-quality MR imaging of perirectal disease (including Crohn disease, fistula in ano, and postpartum sphincter dysfunction). Future abdominal applications of MR imaging will involve second-generation MR interventional techniques, including use of open systems, functional or diffusion-weighted imaging exploiting the molecular activity of tissues, and virtual MR endoscopy. Although CT continues to evolve as the premier technique for survey screening of the abdomen, the technical advances in MR imaging have enabled this modality to assume some special nitch roles (in which it adds unique value) in the evaluation of the abdomen. Radiologists can safely assume that there will undoubtedly be much more to come.     

Three novel integrin beta3 subunit missense mutations (H280P, C560F, and G579S) in thrombasthenia, including one (H280P) prevalent in Japanese patients

OBJECTIVE: The purpose of this article is to describe the findings on MR imaging and MR arthrography in posterior capsular tear and teres minor muscle injury after posterior dislocation. We also correlate MR imaging with the arthroscopic findings and present treatment options for these patients. CONCLUSION: MR imaging is helpful in diagnosing abnormalities caused by posterior dislocation injuries and in directing therapy. Teres minor muscle and capsular injuries may occur without the typical reverse Bankart lesion. Isolated teres minor muscle tears seen on MR imaging after posterior dislocation injury may cause pain. However, no consensus exists as to whether the lesions seen on MR images in these patients should be treated surgically or conservatively.     

Only visual impressions are almost always present in long-term memories, and reported completeness, accuracy, and verbalizability of recollections increase with age

PURPOSE: To stage advanced cervical carcinoma with conventional or pharmacokinetic magnetic resonance (MR) imaging by correlating imaging findings with whole-mount specimens and histopathologic findings. MATERIALS AND METHODS: Twenty-six adult patients with primary cervical cancer (stages IIB-IVA) underwent T2-weighted turbo spin-echo (SE) MR imaging; gadolinium-enhanced, T1-weighted SE MR imaging; and gadolinium-enhanced, saturation-recovery, turbo fast low-angle shot MR imaging. All imaging findings were correlated with the whole-mount specimens and histopathologic findings. Signal intensity changes versus time were analyzed by using a pharmacokinetic model and parameter values displayed as a color-coded overlay. RESULTS: Histopathologic stages were IIB (n = 9), IIIB (n = 1), and IVA (n = 16). The overall accuracy for tumor staging was 73% for T2-weighted, 81% for T1-weighted, and 92% for pharmacokinetic MR imaging. Pharmacokinetic MR imaging was accurate (90%) in the diagnosis of tumor extension into the bladder and/or rectal wall but inaccurate (69%) in that of parametrial invasion. T2-weighted images were most accurate (86%) in the assessment of parametrial tumor extension but less accurate (69%) in that of bladder or rectal invasion. CONCLUSION: T2-weighted turbo SE images are still superior to contract medium-enhanced T1-weighted SE or pharmacokinetic MR images in the diagnosis of parametrial infiltration by uterine cervical carcinoma. However, pharmacokinetic MR imaging is a promising method for demonstrating and staging IVA disease.     

Magnetic resonance imaging based digitally reconstructed radiographs, virtual simulation, and three-dimensional treatment planning for brain neoplasms

Currently, patients with brain neoplasms must undergo both computed tomography (CT) and magnetic resonance (MR) imaging to take advantage of CT's density information and MR's soft tissue imaging capabilities. A method has been developed that allows virtual simulation, digitally reconstructed radiographs (DRRs), and 3-D treatment planning of patients with brain neoplasms to be generated using only one T1-weighted MR data set. DRRs of an anthropomorphic RANDO head phantom were generated using MR and CT imaging. The MR based DRRs provided structural information equivalent to CT based DRRs. The spatial linearity of CT and MR image sets was evaluated by measuring the percent distortion and spatial error. There was no statistical difference in spatial linearity or accuracy between the CT and MR image sets. MR and CT based treatment planning were compared using a variety of different treatment accessories, field sizes, photon energies, and gantry positions. Doses at various points throughout the head phantom were used as comparison points between CT based heterogeneous, CT based homogenous, and MR based homogenous treatment planning of the head phantom. Lithium fluoride thermoluminescent dosimeters were used to verify the dosimetric accuracy of MR based treatment planning by taking measurements at these points. For treatment plans with fields that pass through large air cavities, such as the maxillary sinus, homogenous treatment planning produces unacceptable dosimetric error (2%-4%). For treatment plans with fields that pass through the skull, MR homogenous treatment planning can be used with a dosimetric accuracy of +/- 2%.     

Chondroblastoma: classic and confusing appearance at MR imaging

PURPOSE: To define the characteristics of chondroblastoma at magnetic resonance (MR) imaging and the combination of findings that are diagnostic for chondroblastoma. MATERIALS AND METHODS: From January 1987 through December 1992, 22 patients with histologically confirmed chondroblastoma and prior MR imaging examinations were seen. Patients included 16 men and six women, aged 10-58 years (median, 17 years). Retrospective analysis of findings at MR imaging, plain radiography, computed tomography, and bone scanning was performed. RESULTS: Low to intermediate heterogeneous signal intensity, lobular internal architecture, and fine lobular margins were well defined with high-resolution T2-weighted (repetition time > or = 1,500 msec, echo time > or = 70 msec) MR imaging. Adjacent bone-marrow and soft-tissue edema and periosteal reactions were more dramatically demonstrated on MR images than on radiographs. Bone marrow edema was prominent in all but five cases. Obvious periosteal reaction and adjacent soft-tissue edema were visible in 17 cases. CONCLUSION: Knowledge of the MR imaging findings of chondroblastoma will allow accurate diagnosis and help avoid confusion with infection and aggressive neoplasms.     

In vitro and in vivo MR imaging of hyaline cartilage: zonal anatomy, imaging pitfalls, and pathologic conditions

Hyaline cartilage plays an essential role in the maintenance of normal synovial joint function by reducing friction and distributing loads. Histologic analysis of hyaline cartilage reveals zonal variation in cellular morphology, proteoglycan concentration, and collagen fiber size and orientation. High-resolution magnetic resonance (MR) imaging reveals an analogous laminar anatomy that is often visible on clinical images obtained with proper attention to technique. In vitro and in vivo pulse sequences show three distinct laminae: a hypointense superficial lamina, a hyperintense intermediate lamina, and a heterogeneous deep lamina that consists of alternating hyperintense and hypointense bands perpendicular to the subchondral bone. Imaging pitfalls include magic angle effects, truncation artifact, partial volume effect, regional anatomic variation, chemical shift, and magnetic susceptibility effects. Pathologic conditions that affect articular cartilage include chondromalacia patellae, osteoarthritis, and localized traumatic lesions. Although detection of early cartilage disease remains elusive, MR imaging can demonstrate intermediate and advanced lesions.     

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.     

Multifunctional magnetic resonance imaging of cerebrovascular disease

Over the last few years magnetic resonance imaging (MRI) has developed into a multipurpose imaging technique. In addition to anatomical information, data can be obtained on perfusion, metabolism and imaging of the vascular anatomy. Especially in the field of neuroradiology the possibilities for obtaining multifunctional information from combined MR examinations are promising. In particular, stroke or stroke-related research benefits from these developments. This article reviews the current status and the potential of newly developed MR techniques with regard to the intracranial hemodynamic changes in patients with severe stenosis or occlusion of the internal carotid artery. The combination of MR angiography, perfusion-weighted MRI and MR spectroscopic imaging seems especially useful in the management of the individual patient.     

Clinical assessment of MR of the brain in nonsurgical inpatients

PURPOSE: To evaluate the effect of MR imaging of the brain on four domains of patient care: diagnosis, diagnostic workup, therapy, and prognosis. METHODS: Pre- and post-MR written questionnaires and oral interviews were administered to the referring clinicians of 103 medical and neurologic inpatients at a tertiary care institution. Additional information was obtained from radiologic reports and records. RESULTS: The study population had a diverse array of signs and symptoms and of presumptive clinical diagnoses, reflecting the breadth of disease seen at our institution. The vast majority of physicians (89%) reported that MR imaging added significant diagnostic information, playing an important role in guiding diagnostic workup (24%), planning treatment (34%), and estimating prognosis (47%). MR imaging was significantly more likely to decrease than to increase confidence in the presumptive clinical diagnosis. Thus, MR imaging may be most useful in the setting of diagnostic uncertainty. CONCLUSION: Our results show that MR imaging of the brain has important effects on each of the four domains of care for medical inpatients.     

Developmental pattern of expression of NPDC-1 and its interaction with E2F-1 suggest a role in the control of proliferation and differentiation of neural cells

It is now possible to perform contrast arteriography safely and rapidly by taking advantage of gadolinium contrast agents and three-dimensional MR imaging. Although the development of this approach to arteriography is in its infancy, the image quality already rivals conventional arteriography. As we continue to develop this technique by taking advantage of more pulse sequence tricks, improving hardware, and improving contrast agents, the field of vascular imaging will undoubtedly be transformed. This article discusses the fundamental concepts underlying this approach to angiography.     

Diagnosing breast implant rupture with MR imaging, US, and mammography

A total of 135 symptomatic women with 262 breast implants were examined with magnetic resonance (MR) imaging performed with a body coil, ultrasound (US), or both to determine imaging features of implant rupture. Surgical proof was available for 33 women with 62 implants; 24 were ruptured and 38 were intact. Complicated internal structure was the most reliable predictor of implant rupture: Diffuse low-level echoes were seen on sonograms in 56% of ruptured implants; internal membranes (which correspond to the collapsed implant shell) were seen on MR images in 58% of ruptured implants. Fluid droplets were seen within the silicone in 26% of ruptured implants on MR images. Irregular implant contour can be a sign of rupture but is unreliable. Fluid collections around silicone implants are not a sign of rupture. At present, neither US nor conventional MR imaging with a body coil is sufficiently reliable to advocate routine screening of asymptomatic women with breast implants. Evaluation with MR imaging performed with a surface coil is more reliable.