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Objective: This paper describes the methods used to create annotated deformable anatomic templates (DATs) and display them in a patient's axial 2-dimensional and reformatted volume brain images., Methods: A senior neuroradiologist annotated and manually segmented 1185 color-coded structures on axial magnetic resonance images of a normal template brain using domain knowledge from multiple medical specialties. Besides the visible structures, detailed pathways for vision, speech, cognition, and movement were charted. This was done by systematically joining visible anatomic anchor points and selecting the best fit based on comparisons with cadaver dissections and the constraints defined on the companion 2-dimensional images., Results: The DAT is commercially available for use on a picture archiving and communication system or as a standalone workstation., Conclusions: The DAT can quickly embed extensive, clinically useful functional neuroanatomic knowledge into the patient's brain images. Besides labeling visible structures, DAT displays clinically important, previously uncharted subdivisions of the fiber tracts.

Animal studies show that long-lasting stretching training can lead to significant hypertrophy and increases in maximal strength. Accordingly, previous human studies found significant improvements in maximal voluntary contraction (MVC), flexibility, and muscle thickness (MTh) using constant angle long-lasting stretching. It was hypothesized that long-lasting stretching with high intensity will lead to sufficient mechanical tension to induce muscle hypertrophy and maximal strength gains. This study examined muscle cross-sectional area (MCSA) using magnetic resonance imaging (MRI). Therefore, 45 well-trained subjects (f: 17, m: 28, age: 27.7 ± 3.0 years, height: 180.8 ± 4.9 cm, mass: 80.467.2 kg) were assigned to an intervention group (IG) that stretched the plantar flexors 6 x 10 minutes per day for 6 weeks or a control group (CG). Data analysis was performed using 2-way ANOVA. There was a significant Time x Group interaction in MVC (p < 0.001-0.019, η² = 0.158-0.223), flexibility (p < 0.001, η² = 0.338-0.446), MTh (p = 0.002-0.013, η² = 0.125-0.172), and MCSA(p = 0.003-0.014, η² =0.143-0.197). Post hoc analysis showed significant increases inMVC(d = 0.64-0.76), flexibility (d = 0.85-1.12), MTh (d = 0.53-0.6), and MCSA (d = 0.16-0.3) in IG compared with CG, thus confirming previous results in well-trained subjects. Furthermore, this study improved the quality for the morphological examination by investigating both heads of the gastrocnemius with MRI and sonography. Because stretching can be used passively, an application in rehabilitation settings seems plausible, especially if no commonly used alternatives such as strength training are applicable. [ABSTRACT FROM AUTHOR]

This paper gives perspectives on a companion article, the case history of a professional writer who has multiple sclerosis. The patient's first-person account of her illness is combined with clinical summaries about her care. The discussion of this case illustrates the value of combining such subjective and objective reports in evaluating a patient. Furthermore, considering these reports in the context of current research findings on the organization and function of cognitive neural systems can shed light on patients' seemingly contradictory clinical findings. For this patient, a deficit in the ability to select the most important information to achieve her current goals reflected her neuropsychological test results and neuroradiologic findings, and helped to explain her difficulties with her job and her activities of daily living. Because the patient's cognitive impairments have been her primary manifestations of multiple sclerosis, she illustrates the importance of physicians attending to and helping patients manage their cognitive deficits.

Even after 100 years, problems of early evaluation, classification, and treatment of Legg-Calvè-Perthes disease (LCPD) are still under discussion. In the past, most of the studies on the natural history of LCPD proved that majority of the cases heal spontaneously without functional impairment at maturity, but if we consider the late results a considerable number of hips become painful and require prosthesis. Thus, in this review the results of the several important papers published in the last 40 years and the articles about magnetic resonance imaging in LCPD are analyzed to evaluate whether there can be a new way to reach an early best diagnosis to improve the prognostic evaluation.

Purpose of Review: In recent years molecular imaging techniques have made important advances as regards the study of sarcoidosis. This paper reviews new developments in these techniques as well as their present role and limitations in the assessment of patients with sarcoidosis., Recent Findings: PET with (18)F-fluorodeoxyglucose ((18)F-FDG PET) has proved to be more sensitive than (67)gallium ((67)Ga) scan for assessing the inflammatory activity of sarcoidosis. Integrated (18)F-FDG PET/computed tomography (CT) scanners have improved diagnostic accuracy, and an emerging role for (18)F-FDG PET/CT in monitoring therapy has been described. The use of MRI is well established in neurosarcoidosis and musculoskeletal sarcoidosis. MRI is also the test of choice in suspected cardiac sarcoidosis. It provides anatomical information and quantification of ventricular function, and reveals very early changes in the signal of the myocardium in delayed enhancement., Summary: (18)F-FDG PET/CT is useful in the detection of occult granuloma sites and residual activity in patients with fibrotic pulmonary sarcoidosis. It has an emerging role in the therapeutic management of patients with multisystemic sarcoidosis. MRI is indicated when neurosarcoidosis or cardiac or musculoskeletal involvement is suspected. Although most lesions detected are nonspecific in appearance, some patterns may be present in the early stages.

Study Design: Retrospective magnetic resonance imaging (MRI)-based study., Objective: Our goal was to develop Wiltse's paraspinal surgical approach by determining the precise anatomic locations of the intermuscular cleavage planes formed by the multifidus and longissimus muscles. The primary objective was to measure the distances between the midline and the intermuscular planes, bilaterally, on MRI scans at each of the five disc levels between L1 and S1. Secondary objectives included identifying the existence of any correlations between patient demographics and the measured outcomes., Summary of Background Data: In 1968, Wiltse described an approach to the spine using the natural cleavage plane of the multifidus and longissimus muscles as an entry to the posterior spinal elements. The small direct incisions lessened bleeding, tissue violation, and muscle retraction, which popularized Wiltse's approach among surgeons. A detailed description of the locations of the intermuscular cleavage planes at each lumbar disc level, however, is not available., Methods: MRI scans of 200 patients taken during routine care (2007-2009) were retrospectively reviewed to gather measurements of the distances from the intermuscular cleavage planes to the midline, bilaterally, at each disc level from L1 to S1. Age, sex, and BMI (body mass index) were obtained to determine correlations., Results: Mean measurements significantly differed between all disc levels. At L5-S1, the mean distance was 37.8 mm; at L4-L5, 28.4 mm; at L3-L4, 16.2 mm; at L2-L3, 10.4 mm; and at L1-L2, 7.9 mm. The mean female distances were significantly greater than males (2 mm) on both sides of L5-S1 only. No correlation was discovered between BMI, age, height (N = 50), or weight (N = 50) with respect to measured distances., Conclusion: In the absence of any significant clinical correlation between patient demographics and the entry site in Wiltse's approach, the spine surgeon may use distances described in this paper to apply to a broad base of spine patients regardless of BMI, sex, or age.

Background: The purpose of this paper was to compare the use of computed tomography (CT) versus magnetic resonance imaging (MRI) to evaluate hip reduction in patients with dysplasia of the hip., Methods: A retrospective review of postoperative pelvic CT and MRI in patients <13 months of age with hip dysplasia was performed. Scanner time, anesthesia requirement, cost, and radiation dosage were recorded. Hips were classified as dislocated, subluxated, or reduced. Sensitivity and specificity of CT and MRI were calculated. The outcomes of the subluxated hips were followed., Results: Thirty-two CT scans and 33 MRI scans in 39 patients were evaluated. CT scanner time was 2.8 minutes, which was significantly less than the 8.9 minutes required for MRI (P=0.0001). Postoperative anesthesia was only required for 1 CT case. Average cost of CT examination was $788 and $1104 for MRI. Average radiation dose with CT examinations was 1 mSv. Of the postoperative nonsubluxated hips (n=30 for CT and n=37 for MRI), CT demonstrated a sensitivity of 100% and a specificity of 96%, whereas MRI exhibited a sensitivity of 100% and a specificity of 100%. Of the postoperative subluxated hips, 66.7% spontaneously reduced, 22.2% remained subluxated, and 11.1% redislocated., Conclusions: This is the first study to compare these imaging modalities in the evaluation of hip reduction in DDH. This study affirms MRI as an alternative to CT scan. The sensitivity and specificity of both modalities appears excellent. Similar to other studies, a large percentage of subluxated hips in both groups reduce without additional surgical intervention., Level of Evidence: Diagnostic level II.

This is the sixth in a series of articles on the spine. The first 5 reviewed the sectional anatomy of the cervical, thoracic, and lumbosacral spines. This paper will review both the male and female pelves. Procedures performed in the pelvis include electromyography of the anal sphincter, pudendal and sacral nerve stimulator implants, and botulinum toxin type A injections into the prostate, the bladder, the urethra, and the anus. Complications from these procedures are rare. Electromyography in this region is particularly uncomfortable. Botulinum toxin type A denervation may result in local effects such as incontinence or urinary retention or rarely remote effects such as limb weakness. Neurostimulators may get infected or may fail. This article provides anatomically accurate schematics of innervations of the pelvis that can be used to interpret magnetic resonance images of muscles and nerves in the pelvic floor region. Cross-sectional schematics of the male and female pelves were drawn as they appear on imaging projections. The relevant nerves were color coded. The muscles and the skin surfaces were labeled and assigned the color of the appropriate nerves. An organized comprehensive map of the motor innervation of both the male and female pelves allows the physician to increase the accuracy and efficacy of interventional procedures. This anatomic map could also assist the electromyographer in correlating the clinical and electrophysiologic findings on magnetic resonance images.

In recent years, criteria for the diagnosis of multiple sclerosis (MS) have changed, mainly due to the incorporation of new MRI criteria. While the new criteria are a logical step forward, they are complex and-not surprisingly-a good working knowledge of them is not always evident among neurologists and neuroradiologists. In some circumstances, several MRI examinations are needed to achieve an accurate and prompt diagnosis. This provides an incentive for continued efforts to refine the incorporation of MRI-derived information into the diagnostic workup of patients presenting with a clinically isolated syndrome. Within the European multicenter collaborative research network that studies MRI in MS (MAGNIMS), a workshop was held in London in November 2007 to review information that may simplify the existing MS diagnostic criteria, while maintaining a high specificity that is essential to minimize false positive diagnoses. New data that are now published were reviewed and discussed and together with a new proposal are integrated in this position paper.

This review examines the state of the art in vessel wall imaging by magnetic resonance imaging (MRI) with an emphasis on the biomechanical assessment of atherosclerotic plaque. Three areas of advanced techniques are discussed. First, alternative contrast mechanisms, including susceptibility, magnetization transfer, diffusion, and perfusion, are presented as to how they facilitate accurate determination of plaque constituents underlying biomechanics. Second, imaging technologies including hardware and sequences, are reviewed as to how they provide the resolution and signal-to-noise ratio necessary for determining plaque structure. Finally, techniques for combining MRI data into an overall assessment of plaque biomechanical properties, including wall shear stress and internal plaque strain, are presented. The paper closes with a discussion of the extent to which these techniques have been applied to different arteries commonly targeted by vessel wall MRI.

Purpose of Review: To give an overview of recent developments in neuroimaging in psychiatry and on the current discussion about the relationship between theoretical concepts and data from neuroimaging studies., Recent Findings: In psychiatric neuroimaging, broad concepts such as the self, well being, insight, empathy and volition form an integral part of the questions to be answered and cannot be avoided. Although, currently, the intradisciplinary discussion in neuroscience is mainly focused at the methodological and neurobiological level, psychological and philosophical theories are also needed for the interpretation of results. This raises questions regarding the epistemic priority of neuroimaging data and theories., Summary: In the current paper, we present the hypothesis that there is an interdependence of neuroimaging data and theoretical concepts. An approach to 'correlational neuroscience' with an awareness of this issue may help in avoiding misunderstandings and oversimplifications as well as building an interdisciplinary theoretical framework that is able to integrate findings from life sciences, mind sciences and humanities.

Atrial septal defects can occur at various levels of the interatrial septum. Sinus venosus atrial septal defect (SVASD) results from abnormal resorption of the embryologic sinus venosus, and may be of the superior or inferior type. In this paper, we describe a 46-year-old man with inferior-type SVASD who presented with arrhythmias and dyspnea. Cardiac magnetic resonance and cardiac catheterization were useful in evaluating the anatomic/functional characteristics of inferior-type SVASD and distinguishing it from unroofed coronary sinus.

Multislice computed tomography technology has enabled sophisticated insights into the evaluation of collateral venous pathways in the thorax. A small but well-established body of literature has described the multiple venous pathways in patients with central venous obstruction. In unusual circumstances, however, physiologically maladaptive pathways have been described involving systemic to pulmonary venous shunts. This paper describes 21 patients with systemic to pulmonary venous shunts having a wide spectrum of etiologies. Clinical presentations typically include cardiopulmonary symptomatology and paradoxical emboli. Ultrafast magnetic resonance and multislice computed tomography established the diagnosis of this uncommon but important entity.

Continued advances in radiofrequency hardware and tailored software have, in recent times, greatly increased the power and performance of magnetic resonance imaging for noninvasive evaluation of cardiovascular diseases. Magnetic resonance imaging can uniquely be manipulated to trade temporal resolution and spatial resolution against each other, depending on whether detailed structural or functional information is required. However, to date, a number of cardiovascular magnetic resonance applications have been somewhat limited due to signal-to-noise ratio constraints, reflecting the narrow imaging window imposed by physiological cardiac motion. By increasing the operating field strength from 1.5 to 3 T, it is possible (in principle) to double the signal-to-noise ratio, which in turn may be "traded" for improvements in spatial resolution, coverage, or imaging speed. In this context, the development of parallel imaging has set the stage for impressive performance improvements in contrast-enhanced magnetic resonance angiography at 3 T. Indeed, one could argue that without parallel acquisition, the bang for the buck in going from 1.5 to 3 T would be limited. In this paper, we discuss the current status of 3-T magnetic resonance imaging for cardiovascular imaging, considering the relative gains and limitations relative to 1.5 T.

The development of novel imaging agents and techniques is allowing some biological events to be imaged in vivo with magnetic resonance imaging (MRI) at the cellular and subcellular level. In this paper, the use of novel gadolinium chelates and superparamagnetic iron oxide nanoparticles for molecular MRI of the cardiovascular system is extensively reviewed. The physical properties of these imaging agents and the pulse sequences best suited to their visualization are extensively discussed. The application of molecular MRI in diseases of the vasculature and myocardium is then reviewed. The clinical experience to date, as well as the promise and potential impact of molecular MRI, is extensively discussed.

The value of medical imaging in detection, staging, grading, and tissue-specific diagnosis has been substantially increased, especially after the introduction of magnetic resonance imaging, the combined use of cytogenetic and molecular techniques and the refinement of biopsy techniques. In this paper, we will focus on the combination of parameters including clinical information, prevalence, age, location, and findings on medical imaging, yielding the highest diagnostic sensitivity and specificity. An imaging prototype of a malignant soft tissue tumor will be proposed. In a second part, we will present an overview of most common soft tissue tumors, especially focusing on these tumors having more characteristic imaging features that allow to make a more detailed tissue-specific diagnosis. Finally, we will give the radiologist a short list of important things to take home.

This paper will review the lumbosacral spine (L1-S5). Procedures performed in the lumbosacral spine include electromyography, spinal stimulator implants, spinal infusion implants for spasticity or pain medications, sacroiliac spine injections, facet blocks, and steroid injections. Complications from these procedures include iatrogenic paraplegia or paraplegia due to transverse myelitis, intravascular penetration, dural puncture, increased pain at the injection site, increased radicular pain, increased spine pain, lightheadedness, nausea, nonspecific headache, and vomiting. Long-term complications include implant infection, implant or catheter dislodgment/kinking, and device failure. This paper provides anatomically accurate schematics of innervations of the lumbosacral spine (L1-S5) that can be used to interpret magnetic resonance images of the muscles and nerves. Cross-sectional schematics of the lumbosacral spine were drawn as they appear on imaging projections. The relevant nerves were color coded. The muscles and skin surfaces were labeled and assigned the color of the appropriate nerves. An organized comprehensive map of the motor innervation of the lumbosacral spine allows the physician to increase the accuracy and efficacy of interventional procedures. This anatomical map could also assist the electromyographer in correlating the clinical and electrophysiological findings on magnetic resonance images.

This paper will review the experience and current applications of magnetic resonance-guided focused ultrasound surgery (MRgFUS) for treatment of breast tumors. Because of the efficient screening mammography programs, most of the breast cancers diagnosed today in the United States and European Union are in early stage and are treated with limited surgery. The MRgFUS may offer an alternative treatment option to conventional surgical lumpectomy with the advantage of being a noninvasive procedure and potentially achieving a better cosmetic outcome. Selection of appropriate patients is of paramount importance. Additional studies are needed to determine the effectiveness of the MRgFUS tumor ablation and define its role as a replacement for surgical lumpectomy.

Objectives: This paper describes our work in developing techniques and devices for magnetic resonance (MR)-guided high-intensity ultrasound ablation of the prostate and includes review of relevant literature., Methods: Catheter-based high-intensity ultrasound applicators, in interstitial and transurethral configurations, were developed to be used under MR guidance. Magnetic resonance thermometry and the relevant characteristics and artifacts were evaluated during in vivo thermal ablation of the prostate in 10 animals. Contrast-enhanced MR imaging (MRI) and diffusion-weighted MRI were used to assess tissue damage and compared with histology., Results: During evaluation of these applicators, MR thermometry was used to monitor the temperature distributions in the prostate in real time. Magnetic resonance-derived maximum temperature thresholds of 52 degrees C and thermal dose thresholds of 240 minutes were used to control the extent of treatment and qualitatively correlated well with posttreatment imaging studies and histology. The directional transurethral devices are selective in their ability to target well-defined regions of the prostate gland and can be rotated in discrete steps to conform treatment to prescribed boundaries. The curvilinear applicator is the most precise of these directional techniques. Multisectored transurethral applicators, with dynamic angular control of heating and no rotation requirements, offer a fast and less complex means of treatment with less selective contouring., Conclusions: The catheter-based ultrasound devices can produce spatially selective regions of thermal destruction in prostate. The MR thermal imaging and thermal dose maps, obtained in multiple slices through the target volume, are useful for controlling therapy delivery (rotation, power levels, duration). Contrast-enhanced T1-weighted MRI and diffusion-weighted imaging are useful tools for assessing treatment.

Magnetic resonance imaging (MRI)-guided focused ultrasound surgery (FUS) is a full noninvasive approach for localized thermal ablation of deep tissues, coupling the following: (1) a versatile, nonionizing physical agent for therapy and (2) a state-of-the art diagnosis and on-line monitoring tool. A commercially available, Food and Drug Administration-approved device using the MRI-guided FUS exists since 2004 for the ablation of benign tumors (uterine fibroids); however, the ultimate goal of the technological, methodological, and medical research in this field is to provide a clinical-routine tool for fighting localized cancer. When addressing cancer applications, the accurate spatial control of the delivered thermal dose is mandatory. Contiguous destruction of the target volume must be achieved in a minimum time, whereas sparing as much as possible the neighboring healthy tissues and especially when some adjacent regions are critical. This paper reviews some significant developments reported in the literature related to the image-based control of the FUS therapy for kidney, breast, prostate, and brain, including the own experience of the authors on the active feedback control of the temperature during FUS ablation. In addition, preliminary results of an original study of MRI-guided FUS ablation of VX2 carcinoma in kidney, under active temperature control, are described here.

We studied anesthesia times for diagnostic and interventional radiology using anesthesia billing data and paper radiology logbooks. For computerized tomography and magnetic resonance imaging procedures, we tried to predict future anesthesia times by using historical anesthesia times classified by Current Procedural Terminology (CPT) codes. By this method, anesthesia times were estimated even less accurately than operating room cases. Computerized tomography and magnetic resonance imaging had many different CPT codes, most rare, and CPT codes reflected organs imaged, not scanning times. However, when, anesthesia times were estimated by expert judgment, face validity and accuracy were good. Lower and upper prediction bounds were also estimated from the expert estimates. For interventional radiology, predicting anesthesia times was challenging because few CPT codes accounted for most cases. Because interventional radiologists scheduled their elective cases into allocated time, the necessary goal was not to estimate the time to complete each case but rather the time to complete each day's entire series of elective cases including turnover times. We determined the time of day (e.g., 4 pm) up to when interventional radiology could schedule so that on 80% of days the anesthesia team finishes no later than a specified time (e.g., 6 pm). Both diagnostic and interventional radiology results were similarly less accurate when Version 9 of the International Classifications of Diseases' procedure codes was used instead of CPT.

Purpose of Review: This review reports on the use of muscle magnetic resonance imaging as a clinical and research tool in inherited neuromuscular disorders., Recent Findings: Several papers published during the past few years have reported on the value of muscle magnetic resonance imaging in detecting patterns of muscle involvement in various muscular dystrophies and other inherited myopathies. The patterns of muscle involvement observed on muscle magnetic resonance imaging are often specific for distinct genetic entities., Summary: Our review of the literature suggests that muscle magnetic resonance imaging can provide information that is useful in clinical practice and may be used as an additional tool in a diagnostic flow chart to select appropriate genetic and biochemical investigations.

This paper discusses the modern neurosurgeon's use of advanced magnetic resonance imaging in pre-operative and perioperative planning. The effect of advanced imaging on the risk and benefit analysis of surgery is discussed in particular.

Hyperpolarized gases belong to a new class of MR contrast agents that, when inhaled, provide high temporal and spatial resolution images of the lung airspaces. At this time, hyperpolarized gas MRI is only being performed at a limited number of institutions. However, the availability of hyperpolarized gas MRI could increase dramatically in coming years as regulatory hurdles within the U.S. are surmounted. The intent of this paper is to provide an introduction to hyperpolarized gas MRI for the thoracic radiologist. It includes a description of the basic principles of hyperpolarized gas MRI and a review of the results of preliminary clinical investigations with this method.

Pulmonary blood flow is one of the primary determinants of gas exchange. While a number of methods can be used to evaluation pulmonary perfusion, these have substantial limitations. In this paper, we discuss the use of magnetic resonance imaging techniques for the evaluation of pulmonary blood flow. While these methods are not commonly used at present, they have the potential to contribute greatly to the evaluation of suspected pulmonary vascular disease.

Multiple receiver coils produce images with different but complementary views of a patient. This can be used to shorten scans times but there often remain image artifacts caused by patient motion or physiological processes such as flowing blood. This paper reviews how the extra information from the multiple coils can be used to reduce image artifacts. In one method, affected portions of data can be identified and discarded but enough information is still available to reconstruct an improved image. In other methods, the motion itself is determined and the corrupted data is then corrected, leading to an image with reduced artifacts. Results are presented from images corrupted by motion or by flowing blood.

In cardiac imaging, acquisition speed is of primary importance. While improved performance has mainly been achieved through improvements in gradient hardware in the past, further developments along this direction are limited due to physiological constraints such as the risk of peripheral nerve stimulation. With the introduction of parallel imaging, alternative means for increasing acquisition speed have become available. Using information from multiple receiver coils, images can be reconstructed from a sparsely sampled set of data. In practice, parallel imaging allows for 2- to 3-fold acceleration of the imaging process in typical cardiac applications. Further increases in acquisition speed are, however, difficult to achieve for current clinical field strengths and typical field of views. To address the limited gain in acquisition speed achievable with parallel imaging, a new set of methods has been proposed to take into account the similarity of image information at different time points during a dynamic series. Using these methods, 5- to 8-fold acceleration can be achieved in cardiac imaging. It is the purpose of this paper to review cardiac applications of reduced data acquisition methods with focus on parallel imaging and the recently developed k-t BLAST and k-t SENSE techniques.

Pediatric body magnetic resonance imaging can be challenging because of the intrinsic physiologic motions from high respiratory and heart rates. Unlike in adults, in preadolescent children, breath holding is often not an available option. In this paper, the authors describe their clinical experience using the recently available parallel imaging technique, sensitivity encoding (SENSE), to improve on the image quality of pediatric body MR examinations. The three major areas described include rapid imaging using SENSE to achieve time-resolved contrast-enhanced MRA, improvement in single-shot turbo spin echo imaging with SENSE, and decreasing respiratory motion artifact with combination of SENSE and multiple signal averages in various pulse sequences. Some practical suggestions of using SENSE in clinical pediatric body MR examinations are highlighted. The addition of SENSE has allowed for improved image quality and more efficient overall MR examinations for pediatric body imaging.

Intraoperative magnetic resonance imaging (MRI) has been used for years to update neuronavigation and for intraoperative resection control. For this purpose, low-field (0.1-0.2 T) MR scanners have been installed in the operating room, which, in contrast to machines using higher magnetic field strength, allowed the use of standard anesthetic and surgical equipment. However, these low-field MR systems provided only minor image quality and a limited battery of MR sequences, excluding functional MRI, diffusion-weighted MRI, or MR angiography and spectroscopy. Based on these advantages, a concept using high-field MRI (1.5 T) with intraoperative functional neuronavigational guidance has been developed that required adaptation of the anesthetic regimen to working in the close vicinity to the strong magnetic field. In this paper the authors present their experience with the first 80 consecutive patients who received anesthesia in a specially designed radio frequency-shielded operating room equipped with a high-field (1.5 T) MR scanner. We describe the MR-compatible anesthesia equipment used including ventilator, monitoring, and syringe pumps, which allow standard neuroanesthesia in this new and challenging environment. This equipment provides the use of total intravenous anesthesia with propofol and remifentanil allowing rapid extubation and neurologic examination following surgery. In addition, extended intraoperative monitoring including EEG monitoring required for intracranial surgery is possible. Moreover, problems and dangers related to the effects of the strong magnetic field are discussed.

Magnetic resonance diffusion tensor imaging (DTI) is a new technique that can be used to visualize and measure the diffusion of water in brain tissue; it is particularly useful for evaluating white matter abnormalities. In this paper, we review research studies that have applied DTI for the purpose of understanding neuropsychiatric disorders. We begin with a discussion of the principles involved in DTI, followed by a historical overview of magnetic resonance diffusion-weighted imaging and DTI and a brief description of several different methods of image acquisition and quantitative analysis. We then review the application of this technique to clinical populations. We include all studies published in English from January 1996 through March 2002 on this topic, located by searching PubMed and Medline on the key words "diffusion tensor imaging" and "MRI." Finally, we consider potential future uses of DTI, including fiber tracking and surgical planning and follow-up.

Background: Previous studies on unilateral neglect have shown that there are at least two types of neglect-i.e., body-centered and stimulus-centered neglect. These symptoms suggest that the human brain has at least two different reference frames for processing external space. It is unknown, however, whether these two frames are represented independently in the brain and if so, which areas (or networks) of the brain are responsible for each frame of reference., Objective: To determine whether body-centered neglect and stimulus-centered neglect can be dissociated in patients with brain injury., Methods: New figure discriminative cancellation tasks were designed to simultaneously assess body-centered neglect and stimulus-centered neglect. Two neglect patients with lesions located in different anatomic regions were required to circle every complete figure and to cross out every figure with a missing portion on a sheet of white (29.7 x 42 cm) paper., Results: Patient 1 omitted leftward stimuli on the paper, but the stimuli he found were correctly circled or crossed out. On the other hand, Patient 2 marked stimuli across the paper although he mistakenly circled stimuli that were missing a portion of their left side. Neither patient manifested interaction between the two types of neglect., Conclusion: The results of this study clearly showed double dissociation between the two types of neglect. Furthermore, it not only provides evidence that there are two distinct systems of reference frame for external space in the human brain, but also adds new knowledge indicating that these two systems function independently, at least in part.

This paper is the last of three articles that describe the functional anatomy of the upper limb. It extends the series by presenting the axial anatomy of the forearm and hand. In addition, it provides a table that defines the patterns of muscle denervation specific to six representative sites. This set of articles is clinically useful because it can be used to rapidly identify and describe the innervation of the muscles and skin of the upper limb.

This paper reviews the use of neuroimaging in the diagnosis of dementia, especially Alzheimer's disease. Computed tomography is still used to determine reversible causes of dementia; however, without clinical symptoms these causes are hard to find and computed tomography scanning is only cost-effective in a defined group of patients. Using magnetic resonance imaging, atrophy of the medial temporal lobe can be assessed volumetrically and visually, with a high correlation between the two methods. Medial temporal lobe atrophy is highly predictive of Alzheimer's disease, and correlates with neuropsychological performance and postmortem histologically measured volume. Cerebral volume changes over time seem to differentiate Alzheimer's disease and mild cognitive impairment progressing to Alzheimer's disease from controls with high accuracy. Studies of the corpus callosum in dementia indicate a cortico-cortical disconnection caused by atrophy. Of the new techniques, functional magnetic resonance imaging seems the most promising. This technique can possibly play a role in predicting Alzheimer's disease in patients with mild cognitive impairment. The use of single-photon emission computed tomography and positron emission tomography in (early) differential diagnoses seems limited. Lower regional cerebral blood flow is related to the severity of dementia and survival. Iodine-123 iodobenzamide single-photon emission computed tomography in dementia with Lewy bodies seems promising. Current and future positron emission tomography studies concentrate on memory function and receptor imaging. The focus in neuroimaging, especially magnetic resonance imaging, has shifted to early diagnosis and monitoring of the disease course, with a special interest in predicting dementia in patients with mild cognitive impairment.

Subtraction ictal SPET co-registered to MRI (SISCOM) has been shown to aid epileptogenic localization and improve surgical outcome in partial epilepsy patients. This paper reports a method of identifying significant areas of epileptogenic activation in the SISCOM subtraction image, taking into account normal variation between sequential 99Tcm-ethyl cysteinate diethylester SPET scans of single individuals, and attempts to assess the clinical value of statistical mapping in subtraction SPET. Non-linear inter-subject registration is used to combine a group of subtraction images into a common anatomical framework. A map of the pixel intensity standard deviation values in the subtraction images is created, and this map is non-linearly registered to a patient's SISCOM subtraction image. Pixels in the patient subtraction image were then evaluated based upon the statistical characteristics of corresponding pixels in the atlas. SISCOM images created with the voxel variance method were rated higher in quality than the conventional image variance method in 15 patients. No difference in localization rate was observed between the voxel variance mapping and image variance methods. The voxel significance mapping method was shown to improve the quality of clinical SISCOM images.

Magnetization transfer imaging is a technique that was introduced into clinical radiology in the early nineteen nineties and which has gained in popularity ever since, particularly in the field of neuroradiology. This paper presents an overview of the clinical and scientific applications of magnetization transfer imaging in neuroradiology.

New contrast agents for magnetic resonance imaging are continually being developed by pharmaceutical companies in order to better image the liver. These agents can be divided into hepatobiliary agents directed to the hepatocytes and nanoparticulate agents directed to the reticulo-endothelial system. After intravenous injection, all these agents concentrate in the liver and induce profound changes in signal intensity. Particulate agents induce predominantly a darkening of the liver parenchyma, while hepatobiliary agents induce a brightening. In both cases, liver-lesion conspicuity is enhanced, leading to a better visualization of the lesion. After a brief description of the principal characteristics of the agents, this paper will attempt to summarize the utility of these agents for the detection and characterization of focal liver disease.

The last ten years have seen dramatic changes in the therapeutic approach to both primary (i.e., hepatocellular carcinoma: HCC) and secondary (i.e., metastatic lesions) focal liver malignancies. This has been due to the increasing proliferation of new modalities, including percutaneous ablative therapies (ethanol injection: PEI; radiofrequency: RF; laser; microwaves), angiographic therapies (segmental chemoembolization; hypoxic perfusion) and liver transplantation (OLT), in addition to a greater acceptance of pre-existing modalities (resection; systemic chemotherapy). Thus, a main aim of current medical management is to select for each patient the therapeutic modality which will provide the highest success rate, fewest risks and lowest costs for each given situation. However, in order to decide on the appropriate therapeutic choice, the accurate diagnosis of neoplastic lesions by means of one or more imaging modalities (ultrasound: US; computed tomography: CT; magnetic resonance: MR) is mandatory. This imaging work-up can be viewed as having three purposes: lesion detection, lesion characterization, intrahepatic and extrahepatic cancer staging. The present paper is concerned primarily with the imaging approach to liver lesion detection.

Objective: To review studies on the assessment of correlations between magnetization transfer ratio (MTR) histogram analysis and measures of clinical and neuropsychological function., Background: Since its recent introduction, MTR histogram analysis has attracted attention in the field of multiple sclerosis (MS)., Methods: In this paper, studies are discussed that deal with MTR histogram analysis. The principles of MTR, application of MTR methodology as regional and volumetric MTR analysis, clinical and neuropsychological correlates, and potential use of MTR histogram analysis as an estimate of cerebral lesion load in MS are discussed respectively., Results: In several preliminary studies, it has been shown that in MS patients, measures derived from MTR histograms correlate with measures of clinical and particularly neuropsychological function., Conclusion: MTR histogram analysis is a promising method to estimate cerebral lesion load in MS patients. Before it can be routinely used as an outcome measure in clinical trials, a number of questions about this technique have to be addressed.

After several years of research in many disciplines, concern for the safety of silicone gel-filled breast implants continues. Although systemic effects of silicone are debated, there is growing consensus that implant rupture and other local breast complications from implants are very real concerns. This paper reviews the history of breast augmentation with an emphasis on the great variety of implants manufactured during the last generation. A classification scheme consisting of 14 breast implant categories is described, and the MR appearance of many is illustrated. The MR signs of implant rupture and pitfalls associated with those signs are reviewed. Indications and contraindications for MR imaging of implants and soft tissue silicone are presented. The author's breast implant and soft-tissue silicone MR imaging experience with follow-up surgical experience over the last 6 years is summarized and discussed. For 1,626 single lumen silicone gel-filled implants imaged, the sensitivity for rupture was 74% and the specificity was 98%. For those implants, 64.9% showed no evidence rupture on MR, 7.9% were indeterminate, and 27.2% were definitely ruptured. Of those that were ruptured, 26.2% had silicone outside as well as within the fibrous capsule. Of the 442 implants that were shown to be ruptured, 54.8% were in a state of uncollapsed rupture, 12.9% minimally collapsed rupture, 4.1% partially collapsed rupture, and 28.3% fully collapsed rupture.

Computer-aided subtraction of the co-registered and normalized interictal from the ictal single photon emission tomography (SPET) scan, followed by co-registration to the magnetic resonance image, may improve the utility of ictal SPET in the localization of partial epilepsy. This paper describes and technically validates our method. The SPET to SPET co-registration was tested using six sequential 99Tc(m) brain phantom SPET images of different known positions (15 matches). The registration error was determined by multiplying the calculated match transformation matrix by the inverse of the known transformation matrix. The 'worst case' co-registration error was less that one voxel diameter in all cases (median 3.2 mm, range 1.2-4.8 mm). For interictal to ictal SPET registrations in 10 consecutive intractable partial epilepsy patients, a similar root mean square distance (RMSD) between corresponding points on the matched scans was found as for the phantom studies (median 2.2 vs 2.6 mm). The appropriateness of our normalization was studied by comparing the pixel intensity distributions between the matched scans, and by analysing the subtraction pixel intensity distribution. The pixel intensity distribution for both the normalized phantom, and paired normalized patient studies, were closely matched to each other except for the extreme values, which in clinical situations likely represent regions of ictal activation or depression. The subtraction image intensity distributions were symmetrically centred on zero for all values up to at least within the 5th to 95th centile range, confirming good normalization for the 'non-activated' pixels. Also, a linear relationship was demonstrated between the measured pixel intensity on the phantom scans and the true changes in 99Tc(m) activity based on its decay constant. The results of this study demonstrate that our method produces accurate SPET to SPET co-registration, and appropriate SPET normalization, thereby allowing a valid ictal subtraction image to be derived.

Imaging of the Apert syndrome hand is usually done with plain x-rays. This gives only a limited assessment of the grossly abnormal anatomy. Computed tomography (CT) and magnetic resonance imaging (MRI) have the ability to comprehensively demonstrate the spatial arrangement of the bones as well as the anatomy of the soft-tissue structures. This paper demonstrates the use of these two imaging modalities in the complex Apert syndrome hand to improve surgical planning and treatment.

Magnetic resonance (MR) arthrography is possible in any joint in which standard arthrography is performed. The diagnostic potential of this technique is optimized in the assessment of complex anatomical structures and intra-articular abnormalities that are difficult to visualize on conventional MR images. This paper presents the most common applications of MR arthrography in the shoulder, hip, knee, ankle, elbow and wrist, and explores the clinical indications in which MR arthrography adds the greatest benefit compared to standard arthrography and conventional MR imaging. Arthrographic MR images are most valuable in the evaluation of glenoid and acetabular labra, tendons of the rotator cuff, post-operative menisci, osteochondral fractures and loose bodies.

Severe kyphosis is a frequent complication of multiple laminectomies for the treatment of intraspinal tumors in growing children. Early Segmental Spinal Instrumentation (SSI) and posterior spinal fusion can prevent this complication, but because of ferromagnetic properties of conventional stainless steel implants, magnetic resonance imaging (MRI) performed to determine completeness of the resection and later for recurrence of the tumor becomes difficult. To overcome the problems with postoperative imaging, we have resorted to early stabilization of the spine following laminectomy with titanium alloy implants. The decreased ferromagnetic properties of titanium alloy result in less scatter distortion of the image, thus permitting a better follow-up of the tumor. This paper reports five consecutive patients with stabilization of the spine with titanium alloy implants and posterior spinal fusion done at the time of laminectomy. The use of titanium alloy implants in these patients allowed detailed MRI follow-up in all cases, and in two patients offered the surgical team information that altered or affected the patient's care.

Glenohumeral instability refers to subluxation or dislocation of the glenohumeral joint. This painful disorder is particularly common in the athletic population, and the individual with instability may present with a variety of clinical complaints. This paper addresses current theories regarding the pathophysiology of glenohumeral instability and illustrates magnetic resonance findings that can assist in diagnosis and treatment planning.

A mere 5 to 7 years ago, the majority of literature on demyelinating, infectious, metabolic, and congenital diseases of the brain focused on comparison between computed tomography and magnetic resonance imaging (MRI). MRI has become not only the foremost diagnostic tool in imaging of the central nervous system, but also a key research instrument. This is displayed by the recent increase in papers concerning magnetic resonance spectroscopy. It is perhaps no better illustrated than in the study of multiple sclerosis. A review of neuroimaging in infectious diseases places a heavy emphasis on AIDS-related infections. The ongoing development of new scan sequences, contrast agents, and fast scanning techniques are broadening our image of the brain and, indeed, our understanding of pathophysiologic mechanisms of disease states. Excellent examples of this are the metabolic and congenital diseases where, based on the knowledge of metabolic pathways and embryology, MRI has become the modality of choice.

Background and Purpose: Diffusion-weighted magnetic resonance imaging has been shown to be particularly suited to the study of the acute phase of cerebral ischemia in animal models. The studies reported in this paper were undertaken to determine whether this technique is sensitive to the known ischemic thresholds for cerebral tissue energy failure and disturbance of membrane ion gradients., Methods: Diffusion-weighted images of the gerbil brain were acquired under two sets of experimental conditions: as a function of cerebral blood flow after controlled graded occlusion of the common carotid arteries (partial ischemia), as a function of time following complete bilateral carotid artery occlusion (severe global ischemia), and on deocclusion after 60 minutes of ischemia., Results: During partial cerebral ischemia, the diffusion-weighted images remained unchanged until the cerebral blood flow was reduced to 15-20 ml.100 g-1.min-1 and below, when image intensity increased as the cerebral blood flow was lowered further. This is similar to the critical flow threshold for maintenance of tissue high-energy metabolites and ion homeostasis. After the onset of severe global cerebral ischemia, diffusion-weighted image intensity increased gradually after a delay of approximately 2.5 minutes, consistent with complete loss of tissue adenosine triphosphate and with the time course of increase in extracellular potassium. This hyperintensity decreased on deocclusion following 60 minutes of ischemia., Conclusions: The data suggest that diffusion-weighted imaging is sensitive to the disruption of tissue energy metabolism or a consequence of this disruption. This raises the possibility of imaging energy failure noninvasively. In humans, this could have potential in visualizing brain regions where energy metabolism is impaired, particularly during the acute phase following stroke.

In this paper a new technique is presented for measuring the local temporal changes and correlation between them on spatially aligned image sequences. A temporal correlation image is derived from a sequence of static images (frames). The method is illustrated in an application to the dynamic MRI of the rabbit kidney following bolus injection of Gd-DTPA. The similarity maps clearly separate the dynamic response of the cortex to the indicator from that of the medulla and, therefore, segment the kidney into two regions. Regions with different temporal dynamics can be displayed in different colors using a lookup table designed for that purpose.

Failure to reduce an acute posterior dislocation of the shoulder is rare and is usually due to the interposition of a structure into the joint. In this paper we report the MR and CT findings of a failed reduction due to interposition of a dislocated biceps tendon between the humeral head and anterior glenoid fossa. This was associated with an avulsed subscapularis tendon with its attachment to the lesser tuberosity and a nondisplaced fracture of the humeral neck, findings which were only evident on MR.

This paper describes an approach for contrast media research with which high resolution MR images of rats can be studied before, during, and after intravenous contrast media administration. Using a probe designed to hold up to eight rats, the contrast-enhancing properties in normal rat brains of Gd-DTPA, a low molecular weight compound, and polylysine-(Gd-DTPA), a high molecular weight compound, were compared simultaneously in two groups of four rats each. Signal intensity-time graphs, as measured over various anatomical structures of the normal rat head, demonstrated the feasibility of directly comparing enhancement patterns of two pharmacologically different contrast agents and obtaining relevant data in a single experiment.

In many clinical situations neuroradiologists and neurosurgeons are keenly interested in images displaying both brain structures and intracranial vessels in an integrative manner. In this paper an approach to three-dimensional visualization of brain and vascular structures from magnetic resonance (MR) volume data is reported. It has been designed with the aim of providing a robust and reliable image processing tool for routine clinical applications. The method has been made possible by recent developments in MR image acquisition, especially MR angiography and rapid gradient-echo sequences (Turbo-fast low angle shot). On the basis of the ray-tracing principle, integration of brain and vessel anatomy into a single 3D image is achieved. Image data are acquired with flow-compensated gradient-echo pulse sequences. Even slow flow in venous structures may be demonstrated using a two-dimensional sequential-slice scanning method. Finally, if incorporated into an interactive image processing system, this technique may be used as a planning tool allowing a surgical "rehearsal" prior to actual operative exposure and resection of a lesion.