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In an MRI volumetric study of 10 young male schizophrenics (DSM-III-R 295.9x) a temporal lobe segment, corresponding hippocampal formation and parahippocampal gyrus were found smaller as compared with healthy controls while temporal horn was enlarged. Temporal lobe segment and parahippocampal gyrus were larger on the right in patients and controls, reversed asymmetry was found for the hippocampus.
Neuroimaging techniques have advanced the diagnosis, management, and understanding of the pathophysiology underlying the epilepsies. High-resolution ultrasound is an important and useful technique in the investigation of prematures and neonates with seizures. Computed tomography (CT) scans have a diminishing role in the investigation of patients with epilepsy, but in the absence of magnetic resonance imaging (MRI), CT may detect gross structural pathology. MRI is the technique of choice for investigation of patients with seizure disorders. MRI provides excellent anatomic information and tissue contrast, resulting in high sensitivity. MRI studies should be customized to answer the appropriate clinical question. Functional imaging techniques including single photon emission computed tomography (SPECT), positron emission tomography (PET), magnetic resonance spectroscopy, and functional MRI are becoming increasingly important in the investigation and management of patients with seizures. These techniques permit noninvasive assessment of the epileptic substrate, functional status, ictal activity, blood flow changes, metabolism, and neuroreceptors. Application of these new techniques promises to advance our understanding and treatment of seizures in children.
Two new macrocyclic DOTA-like chelates containing one phosphonate pendant arm were synthesised as potential contrast agents for MRI (magnetic resonance imaging). The chelates bind to the lanthanide(III) in an octadentate manner, via four nitrogen atoms, three carboxylate and one phosphonate oxygen atoms. Solution structures of [Ln(do3ap(OEt2))(H(2)O)] and [Ln(do3ap(OEt))(H(2)O)](-) were studied using (31)P and (1)H NMR spectroscopy and SAP (square-antiprismatic)/TSAP (twisted square-antiprismatic) isomerism was observed. Depending on the nature of the lanthanide(III) ion, the lanthanide(III) complexes of H(4)do3ap(OEt) are present in solution as up to four different diastereoisomers observable with NMR. The TSAP isomer is the most abundant at the beginning of the lanthanide series and, with a decrease of the ionic radius of lanthanide(III) ions, both TSAP and SAP forms were observed. A second interconversion (SAP<-->TSAP') becomes important at the end of the series (TSAP' means the TSAP species without a coordinated water molecule). The remaining axial coordination site is occupied by one water molecule for the Gd(3+)-complex. The calculated fraction of the TSAP isomer in the gadolinium(III) complexes increases in the order [Gd(DOTA)(H(2)O)](-) < [Gd(do3ap(OEt2))(H(2)O)] < [Gd(do3ap(OEt))(H(2)O)](-) < [Gd(do3ap)(H(2)O)](2-). Gadolinium(III) complexes of phosphorus-containing chelates, generally, have the advantage of a relatively fast water exchange rate due to a greater sterical demand of the phosphorus acid moiety and of the presence of the second-sphere water shell, which also contributes to the overall relaxivity. The [Gd(do3ap(OEt2))(H(2)O)] and [Gd(do3ap(OEt))(H(2)O)](-) complexes were studied by variable-temperature (17)O NMR and (1)H NMRD. The experimental data were evaluated simultaneously with commonly used equations based on Solomon-Bloembergen-Morgan approximation, extended by a contribution of the second coordination sphere. The water exchange rates were found to be strongly dependent on the TSAP/SAP isomeric ratio and the overall charge of the complex: the monoanionic [Gd(do3ap(OEt))(H(2)O)](-) complex with TSAP molar fraction equal to 0.36 has the water exchange rate of 20 x 10(6) s(-1) (tau(M) = 50 ns) while neutral [Gd(do3ap(OEt2))(H(2)O)] complex with TSAP molar fraction 0.28 has an exchange rate equal to 4.4 x 10(6) s(-1) (tau(M) = 227 ns).
With an eye toward the development of nitroxides as potential contrast enhancing agents for MRI applications, we have compared the rates of reduction of 24 nitroxides of diverse structures by rat whole liver homogenate, hepatocytes, subcellular fractions, and ascorbate (10 eq excess). Our results indicate that five-membered ring nitroxides and alpha-carboxy alpha-aryl tert-butyl nitroxides are significantly more resistant toward bioreduction than six-membered ring and heterocyclic-substituted nitroxides in all systems. In the case of six-membered ring nitroxides the presence of either negatively charged or positively charged groups increases the susceptibility toward ascorbate reduction. The presence of carboxylate groups tends to enhance the resistance of all the nitroxides toward reduction by liver homogenate, hepatocytes, and subcellular fractions. trans-Azethoxyl nitroxides exhibited the best overall resistance toward bioreduction. The T1 relaxants of selected nitroxides were measured and found to be similar.
PURPOSE: To evaluate the incidence and features of cystic structures adjacent to the frontal horns of neonates using MRI, and to assess the clinical features of the neonates. MATERIALS AND METHODS: Between April 2001 and January 2005, MRI examinations were performed at our hospital in 352 neonates and infants whose postconceptional age was less than 48 weeks. We retrospectively evaluated the MRI findings and the clinical records. RESULTS: Seventeen babies (8 males and 9 females) showed cystic structures adjacent to frontal horns, hemilaterally or bilaterally. The incidence of the cysts was 4.8% in total, and was 1.4% (1/74), 9.2% (6/65), and 4.7% (10/213)in term infants, preterm infants born at 33-36 weeks of gestational age, and at less than 32 weeks, respectively. The cysts ranged from 1 to 8 mm in diameter, and were located in the white matter adjacent to ventricular walls and in the portion cephalad to the frontal horns. The cysts resolved in 5 cases (with follow-up ranging from 3 months to 2 years of age), causing slight dilatation of the frontal horn. Developmental disturbances were not observed in patients without other abnormalities. CONCLUSION: Cystic structures near the frontal horns in neonates are detected by MRI at a rate of 4.8%. They will resolve spontaneously without causing developmental abnormalities.
Mouse lemurs (Microcebus murinus) are prosimian primates described to be convenient models of brain aging. We observed very high correlations between the T2-weighted magnetic resonance imaging (MRI) signal decrease and the natural logarithm of age in the basal ganglia. The correlation coefficient was higher for the pallidum (r = 0.95, P < 0.0001) than for other structures. We suggest that the ratio of the pallidum intensity divided by the amygdala and temporal lobe intensity should be a valuable non-invasive marker of age and of cerebral aging. It should be particularly useful for the non-invasive assessment of interventions and drugs that affect the aging process.
This study used structural magnetic resonance imaging (MRI) to investigate associations between brain structure and saccadic eye movements. Seventeen healthy subjects underwent structural MRI and infra-red oculographic assessment of a reflexive saccade task. Volumes of prefrontal, premotor, and occipitoparietal cortex, caudate, thalamus, and cerebellar vermis were used as predictors in multiple regression with prosaccade gain as a dependent variable, controlling for whole-brain volume. Using voxel-based morphometry (VBM), gain was entered into correlational analysis with grey matter density. Regression analysis indicated that vermis volumes predicted prosaccade gain. VBM replicated this finding: gain was correlated with grey matter in the left cerebellar hemisphere and vermis. These findings agree with previous studies on the role of the cerebellar vermis in saccadic gain and support the validity of structural neuroimaging methods in elucidating the neural correlates of saccadic eye movements.
We determine a statistic called the radially Persistent Angular Structure (PAS) from samples of the Fourier transform of a three-dimensional function. The method has applications in diffusion magnetic resonance imaging (MRI), which samples the Fourier transform of the probability density function of particle displacements. The persistent angular structure is then a representation of the relative mobility of particles in each direction. In combination, PAS-MRI computes the persistent angular structure at each voxel of an image. This technique has biomedical applications, where it reveals the orientations of microstructural fibres, such as white-matter fibres in the brain. We test PAS-MRI on synthetic and human brain data. The data come from a standard acquisition scheme for diffusion-tensor MRI in which the samples in each voxel lie on a sphere in Fourier space.
OBJECTIVE: To use computed tomography (CT) and magnetic resonance imaging (MRI) to provide a detailed description of the nasal cavities and paranasal sinuses in clinically normal mesaticephalic dogs. ANIMALS: 2 clinically normal Belgian Shepherd Dogs that weighed 25 and 35 kg, respectively. PROCEDURE: The first dog was anesthetized and positioned in ventral recumbency for CT and MRI examinations, and transverse slices were obtained from the caudal part of the frontal sinuses to the nares. For MRI, T1-weighted, T2-weighted, and proton-density sequences were obtained. The second dog was anesthetized and positioned in dorsal recumbency with the head perpendicular to the table, and CT and MRI examinations were again conducted. At the completion of the MRI examination, each dog received an i.v. injection of heparin and then was euthanatized. A 4% solution of formaldehyde was perfused i.v. immediately after each dog was euthanatized. The skull was prepared, decalcified, embedded with gelatin, and sectioned into 5-mm-thick sections by use of a stainless-steel knife. Each anatomic section was photographed and compared with the corresponding CT and MRI views. RESULTS: Structures on the CT and MRI views matched structures on the corresponding anatomic sections. The CT scans provided good anatomic detail of the bony tissues, and MRI scans were superior to CT scans for determining soft-tissue structures. CONCLUSIONS AND CLINICAL RELEVANCE: CT and MRI provide a means for consistent evaluation of all structures of the nasal cavities and frontal sinuses. Both techniques could be useful for evaluation of diseases that affect the nasal region.
We examined the relationship between MRI lesions and electro-clinical findings with special attention to the localising value of aura sensations and the sides of interictal epileptiform discharges in 327 patients with symptomatic localisation-related epilepsy. As a result, while autonomic as well as psychic auras were correlated with temporal lesions, simple motor seizures were associated with extra-temporal ones. Within the group of patients with temporal lobe epilepsy, autonomic but not psychic auras concurred significantly more often with medial temporal structural lesions. Furthermore, there was a significant difference between concordance rates between sides of MRI lesions and EEG foci as a function of laterality: while the right-sided MRI lesions constantly showed ipsilateral EEG foci, EEG foci concurring with the left-sided MRI lesions proved to be often falsely lateralising. From these results, we assumed that lateral as well as medial temporal involvement is needed in the genesis of the psychic aura in contrast to the autonomic aura, which could be induced without lateral temporal involvement, and lesions in the left hemisphere are more apt to induce secondarily epileptogenic than those in the right hemisphere.
Falanga is an ancient form of punishment or torture but is still commonly reported by our refugees. The late result of caning the heel and ball of the foot is a chronic painful condition with few clinical signs. The aim of the present study was to assess, by MRI, possible morphologic characteristics of the heel and ball of the foot, related to falanga and pain in correlation to clinical findings. Magnetic resonance imaging of the foot was obtained in 12 victims exposed to falanga torture and 9 healthy volunteers. Sagittal T1-weighted spin-echo images (TR 616-840 ms, TE 20 ms), T2-weighted spin-echo images (TR 1900 ms, TE 90 ms), and short tau inversion recovery (STIR) images (TR 1200 ms, TE 15 ms, TI 100 ms) were performed. The central portion of the plantar aponeurosis was generally significantly thicker in victims exposed to falanga torture as compared with that of controls (P < 0.05). In all except one of the victims, MRI demonstrated two layers of the thickened plantar aponeurosis: a deeper portion with normal homogeneous low signal intensity (SI) appearance, and a superficial layer with characteristic areas of mixed SI on both T1- and T2-weighted images. There were no signs of chronic muscular compartment syndromes, and the thickness of the plantar pad did not differ between the two groups. Magnetic resonance imaging may demonstrate morphologic characteristics of the plantar aponeurosis which may confirm falanga torture. Further imaging with more specific sequences is warranted to demonstrate the supposed injuries in the compartmental fat tissue chambers and the vascularity of the ball pad of the foot.
PURPOSE: To compare magnetic resonance imaging (MRI) findings at different stages of cervix cancer treatment and to define the potential of MRI to delineate the gross tumor volume (GTV), clinical target volume (CTV), pathoanatomic structures, and organs at risk (OAR) in brachytherapy. METHODS AND MATERIALS: Forty-nine patients underwent MRI at diagnosis and at brachytherapy. The ability to discriminate anatomic structures on MRI was assessed (quality factor: 0 = inability to discriminate; 1 = fair discrimination; 2 = good discrimination; 3 = excellent discrimination). The overall ability to visualize (percentage of patients with quality factors greater than 0) and the overall discrimination quality score (mean quality factors of all patients) were estimated for the applicator, GTV at diagnosis (GTV(D)), GTV at brachytherapy (GTV(BT))/"gray zones," cervix rim/uterine corpus, OAR, vaginal wall, and parametria. RESULTS: The overall ability to visualize the applicator on MRI at brachytherapy was 100%; for the GTV(BT)/"gray zones," cervix rim/uterine corpus, OAR, and vaginal wall, visualization was 98% (overall discrimination quality factors: 1.2, 2.9, 2.1, 1.9, 1.7, and 2.6). Three of 4 borders of parametrial space were defined in more than 98% (discrimination quality factors: 2.9, 2.1, and 1.2). CONCLUSION: Magnetic resonance imaging provides appropriate information for definition of the applicator, GTV, CTV, pathoanatomic structures, and OAR that enables precise delineation for cervix cancer brachytherapy.
The blood clearance kinetics of five gadolinium complexes, Gd(L), were determined in rats and the results interpreted in terms of an open two-compartment pharmacokinetic model. The complexes were tested in vitro for stability in serum and in aqueous solutions of ions that they might encounter in vivo and that might be expected to react with the Gd(L) complexes to produce uncomplexed gadolinium. Reaction with serum was observed in two instances. Chemical structural differences among the chelating ligands appear to govern the overall reactivity of their Gd(L) complexes. It may be inferred from the results that a preferred structural feature of the ligand is the presence of a 12-membered 1,4,7,10-tetraaza macrocycle.
OBJECTIVES: Gray and white matter volume deficits have been reported in a number of studies of children with attention-deficit/hyperactivity disorder (ADHD); however, there is a paucity of structural magnetic resonance imaging (MRI) studies of adults with ADHD. This structural MRI study used an a priori region of interest approach. METHODS: Twenty-four adults with DSM-IV ADHD and 18 healthy controls comparable on age, socioeconomic status, sex, handedness, education, IQ, and achievement test performance had an MRI on a 1.5T Siemens scanner. Cortical and sub-cortical gray and white matter were segmented. Image parcellation divided the neocortex into 48 gyral-based units per hemisphere. Based on a priori hypotheses we focused on prefrontal, anterior cingulate cortex (ACC) and overall gray matter volumes. General linear analyses of the volumes of brain regions, adjusting for age, sex, and total cerebral volumes, were used to compare groups. RESULTS: Relative to controls, ADHD adults had significantly smaller overall cortical gray matter, prefrontal and ACC volumes. CONCLUSIONS: Adults with ADHD have volume differences in brain regions in areas involved in attention and executive control. These data, largely consistent with studies of children, support the idea that adults with ADHD have a valid disorder with persistent biological features.
Major depression is a heterogeneous condition, and the search for neural correlates specific to clinically defined subtypes has been inconclusive. Theoretical considerations implicate frontostriatal, particularly subgenual prefrontal cortex (PFC), dysfunction in the pathophysiology of melancholia--a subtype of depression characterized by anhedonia--but no empirical evidence has been found yet for such a link. To test the hypothesis that melancholic, but not nonmelancholic depression, is associated with the subgenual PFC impairment, concurrent measurement of brain electrical (electroencephalogram, EEG) and metabolic (positron emission tomography, PET) activity were obtained in 38 unmedicated subjects with DSM-IV major depressive disorder (20 melancholic, 18 nonmelancholic subjects), and 18 comparison subjects. EEG data were analyzed with a tomographic source localization method that computed the cortical three-dimensional distribution of current density for standard frequency bands, allowing voxelwise correlations between the EEG and PET data. Voxel-based morphometry analyses of structural magnetic resonance imaging (MRI) data were performed to assess potential structural abnormalities in melancholia. Melancholia was associated with reduced activity in the subgenual PFC (Brodmann area 25), manifested by increased inhibitory delta activity (1.5-6.0 Hz) and decreased glucose metabolism, which themselves were inversely correlated. Following antidepressant treatment, depressed subjects with the largest reductions in depression severity showed the lowest post-treatment subgenual PFC delta activity. Analyses of structural MRI revealed no group differences in the subgenual PFC, but in melancholic subjects, a negative correlation between gray matter density and age emerged. Based on preclinical evidence, we suggest that subgenual PFC dysfunction in melancholia may be associated with blunted hedonic response and exaggerated stress responsiveness.
Tuberculosis of the spine usually involves the vertebral body and intervertebral disk. Involvement of the posterior arch is rare. We report a case of tuberculosis involving the posterior elements of the T4 and T5 vertebrae in a 38 year old woman. CT is helpful to assess bony structures whereas MRI is ideal to evaluate the neural structures. Clinical, radiographic, and therapeutic considerations regarding tuberculosis of the spine are reviewed.
Inner ear extension caused by schwannomas, which can cause hearing loss, tinnitus and vertigo, is an extremely rare finding. We report a male patient who presented with progressive hearing loss as well as tinnitus in the right ear. Despite rheologic infusion therapy with glucocorticosteroids at another hospital, the patient showed an explicit hearing loss and vertigo related to the right ear. In the pure tone audiogram, we found complete deafness of the right ear, the equilibriometry with caloric testing showed complete loss of the labyrinth. In the HR-MRI, a structure appeared in ranges of the basal and middle cochlea with enhancement of the contrast medium. From the MRI aspect, this appeared to be a small intracochlear schwannoma. As a differential diagnosis, a chronic granulation is also possible. In agreement with the patient, we decided to control the structure clinically every 6 months using MRI; no further growth of the structure appeared. A precise imaging via HR-MRI is required to detect intracochlear schwannomas. Observation is an appropriate option for patients who have serviceable hearing. Surgical exploration can be recommended in cases of progressive diseases and growth into the inner ear with recurrent vertigo attacks. The option of radiotherapy for the treatment of intrameatal acoustic neurinomas should be considered.
In this paper we present the spatial resolution enhancement and noise reduction level achieved with an optimized inductively coupled surface coil specifically designed for our experiments. The technique of designing and implementing customized coils for magnetic resonance imaging of very small structures is described. We have designed a low cost prototype of an inductively coupled circular surface coil, tuned for 1H magnetic resonance imaging at 200 MHz. The coil is mounted on a customized teflon support. The inductive coupling used in this coil improves the signal-to-noise ratio by reducing various loss mechanisms (specially the dielectric losses). Test images have been acquired to determine the evolution of induced articular lesions in a rabbit animal model, as well as brain tumors in rats. The images show high spatial resolution, excellent B1 field homogeneity and no "hot spots". Comparing these images with those acquired with conventional coils, one finds better spatial resolution and signal-to-noise ratio, as well as larger field of view with less intense illumination artifact. The methodology can be used in any application that requires high quality imaging of small structures.