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Castleman disease is an uncommon benign disorder mainly affecting mediastinal lymph nodes and rarely visceral organs. The most typical structural finding is hypervascularity which can be well demonstrated both by CT and MRI. We report MR findings of an unusual case of solitary parenchymal lung involvement.
BACKGROUND: The macro-social and environmental conditions in which people live, such as the level of a country's development or inequality, are associated with brain-related disorders. However, the relationship between these systemic environmental factors and the brain remains unclear. We aimed to determine the association between the level of development and inequality of a country and the brain structure of healthy adults. METHODS: We conducted a cross-sectional study pooling brain imaging (T1-based) data from 145 magnetic resonance imaging (MRI) studies in 7,962 healthy adults (4,110 women) in 29 different countries. We used a meta-regression approach to relate the brain structure to the country's level of development and inequality. RESULTS: Higher human development was consistently associated with larger hippocampi and more expanded global cortical surface area, particularly in frontal areas. Increased inequality was most consistently associated with smaller hippocampal volume and thinner cortical thickness across the brain. CONCLUSIONS: Our results suggest that the macro-economic conditions of a country are reflected in its inhabitants' brains and may explain the different incidence of brain disorders across the world. The observed variability of brain structure in health across countries should be considered when developing tools in the field of personalized or precision medicine that are intended to be used across the world.
OBJECTIVE: 22q11.2 deletion syndrome is the most common genetic cause of velopharyngeal dysfunction (VPD). Magnetic resonance imaging (MRI) is a promising method for noninvasive, three-dimensional (3D) assessment of velopharyngeal (VP) anatomy. The purpose of this study was to assess VP structure in patients with 22q11.2 deletion syndrome by using 3D MRI analysis. DESIGN: This was a retrospective analysis of magnetic resonance images obtained in patients with VPD associated with a 22q11.2 deletion compared with a normal control group. SETTING: This study was conducted at The Children's Hospital of Philadelphia, a pediatric tertiary care center. PATIENTS, PARTICIPANTS: The study group consisted of 5 children between the ages of 2.9 and 7.9 years, with 22q11.2 deletion syndrome confirmed by fluorescence in situ hybridization analysis. All had VPD confirmed by nasendoscopy or videofluoroscopy. The control population consisted of 123 unaffected patients who underwent MRI for reasons other than VP assessment. INTERVENTIONS: Axial and sagittal T1- and T2-weighted magnetic resonance images with 3-mm slice thickness were obtained from the orbit to the larynx in all patients by using a 1.5T Siemens Visions system. OUTCOME MEASURES: Linear, angular, and volumetric measurements of VP structures were obtained from the magnetic resonance images with VIDA image-processing software. RESULTS: The study group demonstrated greater anterior and posterior cranial base and atlanto-dental angles. They also demonstrated greater pharyngeal cavity volume and width and lesser tonsillar and adenoid volumes. CONCLUSION: Patients with a 22q11.2 deletion demonstrate significant alterations in VP anatomy that may contribute to VPD.
Despite neuropathological and electrophysiological evidence for the involvement of parahippocampal structures in temporal lobe epilepsy (TLE), little attention has been paid to morphometric changes in these structures, and the relation of these changes to TLE. We performed high-resolution MRI volumetric analysis to examine in vivo the morphology of the parahippocampal region in 20 healthy subjects and 6 TLE patients with MRI evidence of unilateral hippocampal atrophy. In normal controls the standardized volume of the left entorhinal cortex (EC) was 1305 +/- 138 mm3 and that of the right EC was 1376 +/- 170 mm3; the left perirhinal cortex (PC) was 2900 +/- 554 mm3 and the right PC was 2771 +/- 486 mm3; the left posterior parahippocampal cortex (PPC) was 2499 +/- 583 mm3 and the right PPC was 2234 +/- 404 mm3. Using a 2 standard deviation cutoff from the mean of normal controls, we found ipsilateral to the seizure focus: (i) a reduction in the volume of the EC in all patients; (ii) a reduction of the PC in 2/6 (33%) patients; (iii) no reduction in the volume of the PPC in any patient. In 3/6 (50%) of patients, the EC was also abnormally small contralateral to the seizure focus. In patients with unilateral TLE, the EC is the most affected structure within the parahippocampal region. Whether this is due to a primary role of the EC in the genesis of TLE or is the consequence of its pivotal position in the reciprocal flow of information between the hippocampus and the neo- and limbic cortices remains to be explored.
The recent development of 3 Tesla MRI (3T MRI) has been fueled by promise of increased signal-to-noise ratio(SNR). Many are excited about the opportunity to not only use the increased SNR for clearer images, but also the chance to exchange it for better resolution or faster scans. These possibilities have caused a rapid increase in the market for 3T MRI, where the faster scanning tips an already advantageous economic outlook in favor of the user. As a result, the global market for 3T has grown from a research only market just a few years ago to an ever-increasing clinically oriented customer base. There are, however, significant obstacles to 3T MRI presented by the physics at higher field strengths. For example, the T1 relaxation times are prolonged with increasing magnet field strength. Further, the increased RF-energy deposition (SAR), the larger the chemical shift and the stronger susceptibility effect have to be considered as challenges. It is critical that one looks at both the advantages and disadvantages of using 3T. While there are many issues to address aand a number of different methods for doing so, to properly tackle each of these concerns will take time and effort on the part od researchers and clinicians. The optimization of 3T MRI scanning will have to be a combined effort, though much of the work to date has been in neuroimaging. Multiple applications have been explored in addition to clinical anatomical imaging, where resolution is improved showing structure in the brain never seen before in human MRI. Body and cardiac imaging provide a great challenge but are also achievable at 3T. As an example, the full range of clinical applications currently achieved on today's state-of-the-art 1.5T cardiac MR scanners has also been demonstrated at 3T. In the body, the full range of contrast is available over large fields of view allowing whole liver studies in the clinic or, as needed, one may choose a smaller field of view for high-resolution imaging of the pancreas. The ability to increase resolution for musculoskeletal imaging has provided previously unseen detail. Bone structure, cartilage, and tendons and ligaments can be clearly visualized and pathology more easily detected due to an increased image quality. As the increase in field strength continues, a push to look at 7T has begun. The design philosophy is to keep the system as similar as possible, while changing only the frequency-dependent components. To date, both animal and human imaging have been performed on a whole body 7T scanner. Results show promise for both detailed imaging and functional MRI, but the road ahead is too long to be able to predict where it will end. The move toward higher field strengths is an exciting adventure in which 3T plays the role of trailblazer.
Imaging cerebral GABAA receptor density (GRD) with single-photon emission tomography (SPET) and iodine-123 iomazenil is highly accurate in lateralizing epileptogenic foci in patients with complex partial seizures of temporal origin. Limited knowledge exists on how iomazenil SPET compares with magnetic resonance imaging (MRI) in this regard. We present a patient with complex partial seizures in whom MRI had identified an arachnoid cyst anterior to the tip of the left temporal lobe. Contralaterally to this structural abnormality, interictal electroencephalography (EEG) performed after sleep deprivation disclosed an intermittent frontotemporal dysrhythmic focus with slow and sharp waves. On iomazenil SPET images GRD was significantly reduced in the right temporal lobe and thus contralaterally to the MRI abnormality, but ipsilaterally to the pathological EEG findings. These data suggest that iomazenil SPET may significantly contribute to the presurgical evaluation of epileptic patients even when MRI identifies potentially epileptogenic structural lesions.
We investigated 429 consecutive patients, aged 5 to 18 (mean: 11.0 +/- 3.1) years, diagnosed with migraine or tension-type headache. The patients underwent either MRI or exclusively clinical follow-up examinations. Magnetic resonance imaging revealed normal findings in 82.3% and structural changes in 17.7%. However, the vast majority of these changes had minimal or no pathological relevance, and a causal relationship to the patient's headache could not be proven in any case. In the non-MRI group, clinical follow-up examinations confirmed the initial diagnosis in all patients and MRI was not required in any of these subjects. In conclusion, our study shows a poor relation between recurrent headache fulfilling the criteria of migraine and tension-type headache and structural changes incidentally detected by MRI. In addition, it suggests that clinical follow-up examinations are reliable. Accordingly, MRI is not required for routine examination of recurrent headache in children and adolescents, but it should be performed in patients with abnormal neurological findings, atypical headache pattern, or significant change of preexisting headache.
BACKGROUND: Back problems are reported more by occupational drivers than by any other occupational group. One explanation is that whole-body vibration caused by the vehicle leads to accelerated disc degeneration, herniation, and associated symptoms. We aimed to investigate the effects of lifetime driving exposure on lumbar disc degeneration in monozygotic twins with very different histories of occupational driving during their life. METHODS: We assessed 45 male monozygotic twin pairs from the population-based Finnish Twin Cohort who had greatly different patterns of occupational driving during their life. Data were obtained for driving exposures and potential confounding factors through an extensive, structured interview. We assessed disc degeneration with lumbar MRI. FINDINGS: Disc degeneration did not differ between occupational drivers and their twin brothers. We also did not identify any overall tendency for greater degeneration or pathology in occupational drivers than their twin brothers. INTERPRETATIONS: Although driving may exacerbate symptoms of back problems, it does not damage the disc. Our inability to identify structural damage should be encouraging to those employed in occupations involving motorised vehicles and operation of heavy equipment.
Silica aerogels represent a new class of open-pore materials with pore dimensions on a scale of tens of nanometers, and are thus classified as mesoporous materials. In this work, we show that the combination of NMR spectroscopy and chemical-shift selective magnetic resonance imaging (MRI) can resolve some of the important aspects of the structure of silica aerogels. The use of xenon as a gaseous probe in combination with spatially resolved NMR techniques is demonstrated to be a powerful, new approach for characterizing the average pore structure and steady-state spatial distributions of xenon atoms in different physicochemical environments. Furthermore, dynamic NMR magnetization transfer experiments and pulsed-field gradient (PFG) measurements have been used to characterize exchange processes and diffusive motion of xenon in samples at equilibrium. In particular, this new NMR approach offers unique information and insights into the nanoscopic pore structure and microscopic morphology of aerogels and the dynamical behavior of occluded adsorbates. MRI provides spatially resolved information on the nature of the flaw regions found in these materials. Pseudo-first-order rate constants for magnetization transfer among the bulk and occluded xenon phases indicate xenon-exchange rate constants on the order of 1 s-1 for specimens having volumes of 0.03 cm3. PFG diffusion measurements show evidence of anisotropic diffusion for xenon occluded within aerogels, with nominal self-diffusivity coefficients on the order of D = 10(-3) cm2/s. Copyright 1998 Academic Press.
Recently, kinematic magnetic resonance imaging (MRI) techniques have been developed to provide diagnostic information related to the functional aspects of the joints. The kinematic MRI evaluation of the joint is used to assess the various interactions of the soft tissues and bony anatomic structures that comprise the joint, and to evaluate the relative alignment of these structures through a specific range of motion. The use of kinematic MRI techniques for examination of the joints provides the radiologist and the clinician with augmented data of anatomic and movement-related information.
Twenty-nine soft tissue masses were studied with magnetic resonance imaging (MRI) which proved to be useful in the preoperative evaluation of these lesions. Other imaging modalities employed had significant limitations. Plain films were of little value because of the intrinsically low contrast of soft tissues. Angiography was not necessary unless MRI suggested a vascular lesion or proximity to major blood vessels. Computed tomography (CT) and MRI both readily identified fatty lesions and their relationship to adjacent structures. Some soft tissue tumors could not be delineated from normal muscle with CT, but were easily seen with MRI. MRI is ideally suited for the study of suspected soft tissue tumors because of its excellent soft tissue contrast and its ability to image directly in any plane. Optimum evaluation required imaging in at least two planes with spin echo sequences chosen to bring out both T1 and T2 features.
OBJECTIVES: Developmental cerebral dysplasias are frequent causes of epilepsy. The early stage of gestation, mainly the period of neural crest separation and neuroblast migration (disturbance of midline structures, heterotopias, cortical dysplasias and disturbance of the ventricular and vascular formation), may be considered as a cause of serious cerebral dysplasia. The aim of the study was focused on frequent simultaneous occurrences of epileptic seizures and the defect or abnormality of the ventricular system - cavum septi pellucidi (CSP). MATERIAL AND METHOD: In our study the clinical symptoms, EEG and somatosensory evoked potentials (SEP's) following median nerve stimulation and MRI pictures in the group of patients with CSP (n= 35), were analyzed. In the SEP analysis, a control group of normal, healthy volunteers (n = 40) and a group of age matched patients with epileptic seizures of different origin, without structural lesions evident on MRI (n=21), were used. RESULTS: Analysis of the patient population with CSP (CSP was confirmed by MRI) showed that approximately in 2/3 cases, different types of cranio-cerebral dysplasias were evident on MRI. More than 2/3 of the patients with CSP showed epilepsy and an abnormal EEG record, however, focal EEG changes were seen more frequently in the group of patients with epilepsy without CSP, than in patients with CSP. The SEP's in patients with CSP showed a statistically significant prolongation of latency of thalamic P15 waves, however these changes were not present in the group of patients with epilepsy of a different origin. CONCLUSIONS: In a group of patients with CSP, dysplastic MRI changes, together with the prolongation of thalamic wave latencies according SEP, were examined. These clinical symptoms may be considered the result of disturbances of early gestation and of lesions of midline structures. CSP became an interesting model opportunity for us, and allowed for the clinical, MRI and electrophysiological examination of developmental cerebral dysplasias. We believe that there is an important role for septal and diencephalic midline structures in cerebral electrogenesis, and possibly in the origin of epileptic seizures too.
Smith-Lemli-Opitz syndrome (SLOS) is an autosomal recessive disorder of cholesterol biosynthesis. It is caused by mutations in the gene encoding the enzyme 7-dehydrocholesterol Delta7-reductase (DHCR7), which catalyzes the final step in cholesterol biosynthesis, usually resulting in cholesterol deficiency. We report a 3.5-year-old girl who has cognition in the low average range and normal behavior, but in whom molecular studies identified two missense mutations in DHCR7: V326L and F284L. She was born at term following an uncomplicated pregnancy and delivery, and presented at 12 days of age with poor feeding, abdominal distention, and jaundice. Colonic biopsy was consistent with Hirschsprung disease. On physical examination she had mild ptosis, a long philtrum, mild micrognathia, a short, upturned nose, and subtle 2,3 syndactyly. Her 7-dehydrocholesterol (7-DHC) level was markedly elevated at 8.7 mg/dl (normal 0.10 +/- 0.05), and her cholesterol level was normal at 61 mg/dl (normal for newborn period 50-80 mg/dl). Karyotype analysis was normal, 46,XX. Breast milk feeding was initiated and continued for 18 months. Cholesterol supplementation was implemented at 100 mg/kg/day at 3 months, which resulted in increased cholesterol levels and reduced dehydrocholesterol levels. Neuropsychological testing has shown functioning in the low average range, between the 14th and 18th centiles when compared to peers. This is markedly higher than most children with SLOS. She has no behavioral problems. MRI and MRS testing of the brain revealed no structural abnormalities. This is in contrast to a recently reported case by Prasad et al. [2002: Am J Med Genet 108:64-68] with a mild phenotype, behavioral problems, and abnormal MRI, who is compound heterozygote for both a null and missense mutation. Our case suggests that patients with severe feeding disorders with or without Hirschprung disease and postnatal onset microcephaly may warrant screening for SLOS.
Quantitative magnetic resonance imaging (MRI) was used to investigate volumes of different brain structures in 19 patients with late-onset major depression (DSM-III-R), 27 patients with Alzheimer's disease (NINCDS-ADRDA criteria) and 13 age matched controls. 3-D MRI sequences were acquired using a Siemens 1.5 T scanner. Whole brain volume, CSF volume, volume of the frontal and temporal lobes and the volume of the amygdala-hippocampus complex were assessed using the software NMR Win. Compared to the controls, depressed patients showed a significantly lower whole brain volume and a significantly higher CSF volume, whereas volumes of the frontal and temporal lobes as well as the amygdala-hippocampus complex volumes were not significantly decreased. In addition, depressed patients exhibited a higher ventricle-brain ratio suggesting a higher degree of central atrophy compared to healthy individuals. In contrast, Alzheimer patients showed significantly lower volumes than depressed patients and controls with respect to all volumetric parameters. Although the findings indicate the presence of brain atrophy in patients with late-onset depression, the pattern of volumetric changes in these patients differs markedly from that observed in patients with primary degenerative dementia.
PURPOSE: To evaluate the feasibility of high-resolution magnetic resonance imaging (MRI) of trabecular bone of the wrist at 3 Tesla (3T) in vivo and to assess the potential benefit of the increased resolution for clinical assessment of structural changes in spongy bone. MATERIAL AND METHODS: High-resolution MRI of the wrist was performed with a whole-body 3T MR scanner using a dedicated circularly polarized transmit-receive wrist-coil. Two 3D-FISP sequences with a spatial resolution of 300 x 300 x 300 microm3 in a measuring time of TA = 7:51 min, and 200 x 200 x 200 microm3 in TA = 9:33 min were applied. Seven young healthy volunteers and three elderly subjects with suspected osteoporosis were examined. The signal-to-noise ratio (SNR) in the optimized setup at 3T was compared to measurements at 1.5T. RESULTS: The images at 3T allow microscopic analysis of the bone structure at an isotropic spatial resolution of 200 microm in examination times of <10 min. Differences in the structure of the spongy bone between normal and markedly osteoporotic subjects are well depicted. The SNR at 3T was found up to 16 times higher than at 1.5T applying unchanged imaging parameters. CONCLUSION: The proposed high-resolution MRI technique offers high potential in the diagnosis and follow-up of diseases with impaired bone structure of hand and/or wrist in clinical applications.
The aim of this study was to determine a current density threshold for exciting the motor cortex area of the brain. The current density threshold for excitation of nerve fibres (20 microm in diameter) found in the literature is approximately 1 A/m(2) at frequencies lower than 1 kHz. In consideration of a safety factor of 100, the International Commission on Non-Ionizing Radiation Protection (ICNIRP) recommends to restrict the exposure to 0.01 A/m(2). The electromagnetic stimulation of neurons in the motor cortex is used in the clinical diagnosis of nerve lesions and neuropathy by means of magnetic or electrical transcranial stimulation. Combining medical data from clinical studies and technical specifications of the Magstim Model 200 stimulator, we were able to compute the current density threshold for the excitation of the human motor cortex by means of the finite element method (FEM). A 3D-CAD head model was built on the basis of magnetic resonance imaging (MRI) slices and segmented into four anatomical structures (scalp, skull, brain, and ventricular system) with different conductivities. A current density threshold for the stimulation of the motor cortex area of the upper limbs of 6 and 2.5 A/m(2) at 2.44 kHz and 50 Hz, respectively, was calculated. As these values lie above the recommended ICNIRP values by two orders of magnitude there is no need for lower safety standards with regard to stimulation of the brain.
Magnetic resonance imaging (MRI) has become a staple of diagnostic radiology. Despite its diagnostic utility the resolving power of typical clinical MRI instruments is only on the order of 1 mm. This has led to the development of magnetic resonance microscopy (MRM), which employs the same physical imaging principals used in MRI, but with instrumentation designed to resolve structural details down to the level of 10-100 microns in samples ranging from less than 1mm to several centimeters in size. Until recently, major advancements in MRM have focused on hardware and software developments allowing the detection of radio-frequency signals originating from very small volume elements within the sample. Such high-resolution images have facilitated the early detection of diseased tissue by focusing on sub-millimeter structural changes induced in the tissue. To sensitize the MRM technique to pathologic tissue changes, investigators have developed techniques, such as chemical shift imaging to detect pre-cancerous changes in tissue metabolism and MR relaxometry to detect changes in tissue composition during the earliest stages of degeneration for diseases such as osteoarthritis or multiple sclerosis. However, such non-specific measurements can only serve as surrogate measures of disease progression and potential measures of treatment efficacy. As disease diagnosis moves from the anatomic to the molecular stage, scientists will require imaging techniques that can detect molecular events deep inside the human body. To meet this goal, MR scientists are working to improve imaging resolutions in vivo and they are developing molecular probes that can dramatically amplify the MR signal in response to specific and highly localized molecular events. This article will identify current trends in the MRM field aimed at meeting the challenges imposed by molecular imaging and areas for future development in this highly promising imaging field.
From 1987 to 1992, invasive EEG studies using subdural strips, grids or depth electrodes were performed in a total of 160 patients with medically intractable epilepsy, in whom scalp EEG was insufficient to localize the epileptogenic focus. Dependent on the individual requirements, these different electrode types were used alone or in combination. Multiple strip electrodes with 4 to 16 contacts were implanted in 157 cases through burrholes, grids with up to 64 contacts in 15 cases via boneflaps, and intrahippocampal depth electrodes in 36 cases using stereotactic procedures. In every case, localization of the electrodes with respect to brain structures was controlled by CT scan and MRI. Visual and computerized analysis of extra-operative recordings allowed the localization of a resectable epileptogenic focus in 143 patients (89%), who subsequently were referred for surgery, whereas surgery had to be denied to 17 patients (11%). We did not encounter any permanent morbidity or mortality in our series. In our experience, EEG-monitoring with chronically implanted electrodes is a feasible technique which contributes essentially to the exact localization of the epileptogenic focus, since it allows nearly artefact-free recording of the ictal and interictal activity. Moreover, grid electrodes can be used for extra-operative functional topographic mapping of eloquent brain areas.