GE Signa Horizon Research Articles

Cognitive disconnective syndrome by single strategic strokes in vascular dementia

Strategic regions correspond to associative, limbic and paralimbic structures and related circuits, that underpin cognitive/behavioral functions. Strokes in these eloquent sites produce pictures of vascular dementia with syndromic features due to specific site lesion and/or interruption of their interconnections. This study aims at analysing subcortical strategic strokes that express similar cognitive/behavioral elements, by sharing common pathways. Patients (n=6) who attended in specialized ambulatory, were submitted to neuropsychological and neuroimaging assessments through MRI (GE Signa Horizon 1.5T) and brain SPECT (Millennium MG, ECD [TC-99m]). Stroke locations and respective main symptoms were: 1. anteromedian thalamus [L]: anterograde and retrograde amnesia (ARA), expression aphasia (EA), executive dysfunction (ED), apathy, and depression; 2. anterior thalamus [R]: ARA, inattention, apathy, and aggressiveness; 3. dorsomedian thalamus [L]: inattention, ED, anosognosia, and aggressiveness; 4. central paramedian thalamus [R]: EA, visual perception deficits (VPD), ED, infantility, and personality disorder; 5. caudate nucleus (ventral-head) [L]: VPD, ED, delirium, visual hallucinations, and personality disorder; and 6. anterior capsule [L]: VPD, ED, apathy, and depression. Vascular strategic syndromes connote the predominantly impaired cognitive/behavioral symptom of each site. Temporal and frontal disconnection symptoms were produced by disrupted MTT/hippocampal and IML/amygdala circuits expressing amnesic syndrome associated with heterogeneous dysexecutive syndrome, in all the cases, by disrupting frontal–basal ganglia–thalamus–cortical net, in three different levels of their pathway.

Cerebrocerebellar system and Arnold's bundle - A tractographic study: preliminary results.

The cerebellum, traditionally considered a structure involved in balance and movement control, was more recently recognized as important in cognitive, emotional and behavioral functions. These functions appear to be related to the more recent parts of the cerebellum that belong to the cerebrocerebellar system. One of the key segments of this system is the (pre)fronto-[penduncule]-pontine projection that represents the Arnold’s bundle. Diffusion tensor imaging and tractography (DTI-TR) has permitted in vivo virtual dissection of white matter tracts, including those of the cerebellar.ObjectiveTo study the fronto-[peduncule]-pontine projection (Arnold’s bundle), with DTI-TR.MethodsTen normal subjects were included (mean age 30 years). Standard acquisitions in three planes were obtained with a 1.5T GE Signa Horizon scanner, complemented with DTI acquisitions. Post-processing and analysis was performed using an ADW 4.3 workstation running Functool 4.5.3(GE Medical Systems). A single ROI was placed on the medial third of the cerebral peduncle base, considered the site of convergence of the fibers of Arnold’s bundle, bilaterally.ResultsTwenty tractograms were obtained. All were constituted by a significant number of fibers in correspondence to the frontal lobe, and part of them anterior to the coronal plane at the anterior commissure, which characterizes them as associated to the prefrontal region.ConclusionsFor the first time, frontal lobe related projections were systematically revealed with DTI-TR seeded from cerebral peduncle base ROIs. They showed anatomic coherence with Arnold’s bundle, which includes the prefrontopontine segment of the cortico-ponto-cerebellar path, one of the components of the cerebrocerebellar system, acknowledged as fundamental for non-motor functions such as cognition, emotion and behavior.

The brain subcortical white matter and aging: A quantitative fractional anisotropy analysis.

To study the integrity of hemispheric subcortical white matter by comparing normal young and elderly subjects using quantitative fractional anisotropy (DTI-FA).MethodsSubjects of two different age groups (young=12, elderly=12) were included. MR - GE Signa Horizon - 1.5T scans were performed. Cases with Fazekas scores =3 were assessed on FLAIR sequence. Standard parameters for DTI-FA were used. ROIs were placed at various sites of the subcortical white matter, and the genu and splenium of the midline corpus callosum. Analysis was performed using Functool. Statistics for anterior and posterior white matter, as well as the genu and splenium were compared between the groups. The study was approved by the Ethics Committee of IPUB-UFRJ and informed consent obtained.ResultsDTI-FA showed lower anisotropy values in the anterior region (subcortical white matter and genu), but not in the posterior region (subcortical white matter and splenium), in elderly normal subjects compared to young subjects.ConclusionThe results may represent loss of integrity of anterior (frontal) white matter fibers in the elderly subjects. These fibers constitute important intra- and inter-hemispheric tracts, components of neural networks that provide cognitive, behavioral, motor and sensory integration. The loss of integrity of the anterior segments of the studied fiber systems with ageing, represents a disconnection process that may underlie clinical manifestations found in elderly subjects such as executive dysfunction.

Development of Korean Male Body Model for Computational Dosimetry

The dimensions of the human body vary by age, sex, and race. The internal structure and outer dimensions of a body exposed to an electromagnetic field is important for accurate dosimetry. The average physical size of Korean adult males between the ages 18 to 24 was investigated, and a male volunteer was selected whose physical condition is within the physical standards, ± 5%. Magnetic resonance images and partially computerized tomography images of the volunteer were acquired. The intervals between the transverse images were 1 mm for the head and 3 mm for the rest of the body. About 30 different tissues were manually classified by an anatomist on the raw images, and the segmented images were implemented in the form of a text file appropriate for numerical formulation. model is needed to consider accurate dosimetry in a Korean human body for electromagnetic field exposures. In this letter, the development process of a voxel-based human body model and its results are described. A volunteer was selected based on the average physique of Korean males, and his body was imaged from the crown of the head to the tip of his toes using magnetic resonance (MR) imaging and computerized tomography (CT) scans. For these two types of images, an MR machine (GE Signa Horizon 1.5 Tesla MRI System) and CT machine (GE High Speed Advantage) were used. The CT scans were performed only in a partial head region for better identification of bone, fibrous tissue, and interior air. Based on these images, a three-dimensional anatomical data set suitable for numerical analysis in a rectangular grid, such as the FDTD technique, was implemented.

Cerebral Activation Associated with Visually Evoked Sexual Arousal in the Limbic System: Functional MR Imaging

Purpose: To identify the brain centers associated with visually evoked sexual arousal in the human brain, and to investigate the neural mechanism for sexual arousal using functional MRI (fMRI). Materials and Methods: A total of 20 sexually potent volunteers consisting of 10 males (mean age: 24) and 10 females (mean age: 23) underwent fMRI on a 1.5T MR scanner (GE Signa Horizon). The fMRI data were obtained from 7 slices (10 mm slice thickness) parallel to the AC-PC (anterior commissure and posterior commissure) line, giving a total of 511 MR images. The sexual stimulation consisted of a 1-minute rest with black screen, followed by a 4-minute stimulation by an erotic video film, and concluded with a 2-minute rest. The brain activation maps and their quantification were analyzed by the statistical parametric mapping (SPM 99) program. Results: The brain activation regions associated with visual sexual arousal in the limbic system are the posterior cingulate gyrus, parahippocampal gyrus, hypothalamus, medial cingulate gyrus, thalamus, amygdala, anterior cingulate gyrus, insula, hippocampus, caudate nucleus, globus pallidus and putamen. Especially, the parahippocampal gyrus, cingulate gyrus, thalamus and hypothalamus were highly activated in comparison with other areas. The overall activities of the limbic lobe, diencephalon, and basal ganglia were 11.8%, 10.5%, and 3.4%, respectively. In the correlation test between brain activity and sexual arousal, the hypothalamus and thalamus showed positive correlation, but the other brain areas showed no correlation. Conclusion: The fMRI is useful to quantitatively evaluate the cerebral activation associated with visually evoked, sexual arousal in the human brain. This result may be helpful by providing clinically valuable information on sexual disorder in humans as well as by increasing the understanding of the neuroanatomical correlates of sexual arousal.

Functional neuroanatomy in depressed patients with sexual dysfunction: blood oxygenation level dependent functional MR imaging.

ObjectiveTo demonstrate the functional neuroanatomy associated with sexual arousal visually evoked in depressed males who have underlying sexual dysfunction using Blood Oxygenation Level Dependent-based fMRI.Materials and MethodsTen healthy volunteers (age range 21-55: mean 32.5 years), and 10 depressed subjects (age range 23-51: mean 34.4 years, mean Beck Depression Inventory score of 39.6±5.9, mean Hamilton Rating Scale Depression (HAMD)-17 score of 33.5±6.0) with sexual arousal dysfunction viewed erotic and neutral video films during functional magnetic resonance imaging (fMRI) with 1.5 T MR scanner (GE Signa Horizon). The fMRI data were obtained from 7 oblique planes using gradient-echo EPI (flip angle/TR/TE=90°/6000 ms/50 ms). The visual stimulation paradigm began with 60 sec of black screen, 150 sec of neutral stimulation with a documentary video film, 30 sec of black screen, 150 sec of sexual stimulation with an erotic video film followed by 30 sec of black screen. The brain activation maps and their quantification were analyzed by SPM99 program.ResultsThere was a significant difference of brain activation between two groups during visual sexual stimulation. In depressed subjects, the level of activation during the visually evoked sexual arousal was significantly less than that of healthy volunteers, especially in the cerebrocortical areas of the hypothalamus, thalamus, caudate nucleus, and inferior and superior temporal gyri. On the other hand, the cerebral activation patterns during the neutral condition in both groups showed no significant differences (p < 0.01).ConclusionThis study is the first demonstration of the functional neuroanatomy of the brain associated with sexual dysfunction in depressed patients using fMRI. In order to validate our physiological neuroscience results, further studies that would include patients with other disorders and sexual dysfunction, and depressed patients without sexual dysfunction and their treatment response are needed.

Report on the ECR2003 (European Congress of Radiology): comparison of apparent diffusion coefficient (ADC) between different MRI scanners

To analyze reproducibility of ADC measurements on different MRI scanners. Diffusion-weighted imaging (DWI) of a home-made phantom (gelatine of different concentration was enclosed in case of circle pillar shape) was performed with the following protocol; spin-echo type echo planar imaging; TR=7000 msec, TE=minimal, matrix=128 x 128, FOV=220 mm, slice thickness=5mm, NEX=1, b-factor=0, 500, and 1000 sec/mm(2) on four different 1.5T MR scanners [GE Signa Horizon (two of them), GE Signa Horizon Lx, and Siemens Magnetom Symphony]. Image analysis were performed on a workstation (GE Medical Systems) or on an operators console of Symphony (for data of Symphony). We used two-point method. Regions of interest (ROIs) were set on every part of ADC map of home-made phantom and ADCs were measured. A linear approximation graphs were also made with every MRI scanner and b-factor. A linear approximation was performed, formulas were y=-0.08x+2.32, r(2)=0.84(Lx), y=-0.09x+2.58, r(2)=0.89(Horizon-1) y=-0.11x+2.67, r(2)=0.95(Horizon-2), y=-0.08x+2.42, r(2)=0.97(Symphony) at b-factor of 500sec/mm(2). y=-0.08x+2.33, r(2)=0.91(Lx), y=-0.09x+2.43, r(2)=0.93(Horizon-1), y=-0.08x +2.48, r(2)=0.92(Horizon-2), y=-0.07x+2.39, r(2)=0.96(Symphony) at b-factor of 1000 sec/mm(2). ADC values measured at two MRI scanners (same model and older than the other scanners) are higher than other scanners on b-factor=500 sec/mm(2), but at b-factor=1000 sec/mm(2), a good relationship between every scanners was obtained. This result seems to depend on generation of the MRI scanners; newly scanners have good relations b-factor 500 and 1000 sec/mm(2). Pulse sequence design may be improved and optimized in newly scanners. When ADCs were used as quantitative value, a proper b-factor must be used.

Neovascular Perfusion in Lung Cancer: Qualitative and Quantitative Study using MR Perfusion Imaging

AbstractThe value of phase‐tracking subtraction MR pulmonary perfusion technique in the evaluation of the neovascular perfusion of lung cancer was investigated in 25 patients with lung cancer. All patients were examined with a GE Signa Horizon LX 1.5 T MR system with 2D fast spoiled gradient‐recalled‐echo and first‐pass images after bolus injection of contrast agents were obtained. The first‐pass images of pulmonary artery (PA), pulmonary parenchyma (PP) and pulmonary vein (PV)/ aorta phases and their time‐signal intensity curves (TSC) were calculated, subtracted and analyzed on a GE Advantage workstation with Functool software. The signal intensity changes of tumors occurred simultaneous to, or slightly later than the signal intensity changes of the descending aorta, whereas the signal intensity changes of corresponding regions of normal lung were simultaneous with those of the PA. Thus the TSCs of tumors matched those of the descending aorta, whereas the TSCs of corresponding regions of normal lung matched those of the PA. These findings indicate that the blood supply of these lung cancers comes from the aorta. On the other hand, the maximum slope of the TSC of the tumors was larger than that of normal lung, indicating that the blood supply to the tumor was larger in quantity and that the tumor probably had a higher density of vessels compared to normal lung tissue. It is concluded that MR perfusion imaging of differential phase subtraction of the pulmonary circulation can help to evaluate the angiogenesis of lung cancer by showing the source of the blood supply, its quantity and its hemodynamics.

The findings of proton MR spectroscopy in chronic focal pancreatitis and pancreatic cancer

Background/Aims: The differential diagnosis between chronic focal pencrentitis (CFP) and pancreatic carcinoma (PC) is important for their difference in prognosis and method of management. Unfortunately, it is often difficult and even impossible to discriminate between them, because of their similarity of presenting clinical or radiologic features. The presence of a focal pancreatic mass is generally indicative of a neoplasm, hut chronic pancreatitls may cause a focal pancreatic mass, usually in the head. This study aimed to know the differences of in rive proton MR spectroscopic features between CFP and PC, and to evaluate the possibility to discriminate CFP from PC by analysis of in rive 'H-MR spectra. Methods: We evaluated the in vivo ~H-MR spectra from 33 human pancreases. Our series included 15 cases of CFP and 18 cases of PC. All cases of CFP and PC were confirmed by histopathotogy after surgical resection. Proton MR spectroscopy (~H-MRS) was performed at 1.5T GE Signa Horizon (GE Medical System, Milwaukee, USA) system using localized proton STEAM sequence and body coil in all cases with subjects were located in supine position. No respiratory interruption was required during the spectroscopic signal acquisition. Parameters using in MRS were: TR = over 3000 ms, TE = 30 ms, number of scans = 128, voxel size = 8 (2x2x2) cm 3, and one NEX. The ratio of peak area of all peaks at 1.6-4.1ppm to lipid (O.9-1.6ppm) [P(1.64.1ppm)/P(O.9-1.6ppm)] was calculated in CFP and PC group, and compared the results between these groups. We also evaluated the sensitivity and specificity for discriminating CFP from PC by analysis of in rive 1H-MR spectra. Results:/n rive 1H-MR spectra of CFP showed significantly diminished amount of lipids as compared with that of PC. The ratio of P(1.64.1ppm)/P(O.9-1.Sppm) in CFP was much higher than that in PC with a statistical significance (p<O.05) due to decreased peak area of lipids. Mean _+ standard deviation of P(1.6-4.1ppm)/ P(O.9-1.6ppm) in CFP and PC group were 2.78 +_ 1.67 and 0.35 _+ 0.09, respectively. W'~ a cut-off value of 0.6 for discriminating CFP from PC, both the s e n s ~ and specificity were 100%. Conclusion: CFP and PC can be distinguished from each other by analysis of in rive ~H-MR spectra, and in vivo ~H-MRS can he a useful method for making differential diagnosis between CFP and PC.

The diagnostic utility of pericholecystic high signal by magnetic resonance cholangiography in the patient with acute cholecystitis

AIMS: Pericholecystic high signal demonstrated by Magnetic Resonance Cholangiography (MRC) is suspected of acute cholecystitis. However, comparison between pathological findings of acute cholecystitis and pedcholecystic high signal has not been fully evaluated yet. The aim of this study was to evaluate the relationship between pathological findings of surgical resected gallbladder and pericholecysUc high signal by MRC. METHODS: From 1998 to 2000, MRC was examined in 775 patients with biliopancraatic disease using GE Signa Horizon LX 1.0 T. Early cholecystectomy was performed in 45 patients on 19 (* : median) (4-30) days after MRC. Of these, the presence and amount of pedcholecystic high signal and the pathological findings including thickness of cholecystic wall and acute inflammatory index (length of wall with either severe inflammatory cell infilt~tion, hemorrhage or necrosis / total longitudinal length of gallbladder) was studied. RESULTS: Pedcholecystic high signal was demonstrated in 15 patients and was not in 30 patients. Thickness of cholecystic wall was significantly different between the patients with (4.9* (3.1-6.9) mm) and without (2.2* (0.9-4.6) mm) pericholecystic high signal (P<O.O01). Acute inflammatory index was also significantly different between the patients with (52* (0-97) %) and without (0 (0-37) %) pericholecystic high signal (P<O.O01). Among the 15 patients with pericholecystic high signal, 2 were suffered from abscess type and 8 were hemorrhagic, necrotizing type of acute cholecystitis. On the other hand, according to the 30 patients without pericholecystic high signal, only 3 were suffered from hemorrhagic, necrotizing type of acute cholecystitis. Of the patients with acute inflammatory index below 6 %, pericholacystic high signal was only demonstrated in the body of gallbladder and dilatation of Rokitansky-Aschoff sinus was seen. Concerning patients with acute inflammatory index over 6 %, pericholecystic high signal was circumfersntially demonstrated at least in the body and fundus of gallbladder. CONCLUSIONS: We proved that pericholecystic high signal by MRC was.the imaging of acute cholecystitis from the viewpoint of pathology. MRC was useful in diagnosing acute cholecystitis based on the findings of pericholecystic high signal.

Ictal brain hemodynamics in the epileptic focus caused by a brain tumor using functional magnetic resonance imaging (fMRI)

Using functional magnetic resonance imaging (fMRI) we were able to observe, in detail, ictal brain hemodynamics during epileptic seizure caused by a brain tumor. A 53-year-old man was experencing partial motor seizures of the left side of his face and neck. In a brain MR image a mass lesion was found in the subcortical area of the right frontal lobe. We found focal spikes in his right hemisphere, though dominantly in C4 and T4 regions. fMRI investigations were carried out at 1.5 T (GE Signa Horizon) using gradient-echo echo-planar neuroimaging. We were able to perform the ictal examination twice. The activated regions were focalized and clearly found only on the lateral side of the tumor base. The region was in agreement with the epileptic focus examined using an electrocorticogram (ECOG). The signal intensity in the seizure focus rapidly increased 30 seconds before the convulsion was observed. After the end of the convulsion it also took 30 seconds to restore the signal intensity to the baseline value. fMRI is a very useful tool for various studies such as the identification of the epileptic focus, the mechanism of epileptic seizure, and so on.

Magnetic Resonance Cholangiopancreatography in Cystic Lesions of the Pancreas

There are few reports about magnetic resonance cholangiopancreatography (MRCP) in cystic lesions of the pancreas (KLP). For this reason, we have undertaken a prospective study evaluating the diagnostic efficiency of MRCP as compared with ultrasonography. Twenty-four patients with KLP were examined with magnetic resonance imaging (MRI), and standard and cholangiopancreatography. There were seven cases of cysts associated with acute pancreatitis, 11 patients with KLP and chronic calcifying pancreatitis, five cases of cystic neoplasms of the pancreas, and one polycystic disease of the gland. All cases were first submitted to ultrasonography, which failed to diagnose only a case of cyst associated with chronic pancreatitis depicted by MRCP. We used a GE Signa Horizon 1.5-T system (20 examinations) and a Siemens Magneton Plus 1.5-T machine (four examinations). Eleven patients were operated on. In all cases, it was possible to identify the cysts, the main pancreatic duct and the biliary tree, and verify the relationship of the cyst with neighboring organs. Communication of the cyst with the main pancreatic duct was described in five instances, but we cannot be sure that MRCP would have depicted all cyst-duct communications. The MRI and MRCP images were confirmed by surgery in the 11 operated-on cases. The diagnosis of duct alterations and small pancreatic stones in initial cases of chronic calcifying pancreatitis may be problematic. Clinical findings are very important data to be considered in the differential diagnosis of KLP. Together with the clinical data, MRCP is a very important technique in the diagnostic and therapeutic decision making of KLP. Standard magnetic resonance is advisable as part of the examination in all cases. MRCP is not invasive, is reliable if one knows its limitations, and the patient can return at once to his activities. It allows the analysis of many variables in one examination, contributing to better therapy.

Proton MR Spectroscopic Features of Liver Cirrhosis: Comparing with Normal Liver

Purpose : The purpose of this study was to determine the proton MR spectroscopic features of liver cirrhosis and the different proton MR spectroscopic features between liver cirrhosis and the normal human liver by comparing the two different conditions. Materials and Methods : The investigation involved 30 cases of in-vivo proton MR spectra obtained from 15 patients with liver cirrhosis demonstrated on the basis of radiologic and clinical findings, and from 15 normal volunteers without a past or current history of liver disease. MR spectroscopy involved the use of a 1.5T GE Signa Horizon system (GE Medical Systems, Milwaukee, U.S.A.) with body coil. STEAM (STimulated Echo-Aquisition Mode) with 3000/30 msec of TR/TE was used for signal acquisition; patients were in the prone position and respiration was not interrupted. Cases were assigned to either the cirrhosis or normal group, and using the proton MR spectra of cases of in each group, peak changes occurring in lipids (at 1.3ppm), glutamate and glutamine (at 2.4 -2 .5ppm), phosphomonoesters (at 3.0 -3 .1ppm), and glycogen and glucose (at 3.4 -3 .9ppm) were evaluated. Mean and standard deviation of the ratio of glutamate + glutamine/lipids, phospho-monoesters/lipids, glycogen + glucose/lipids were calculated from the area of their peaks. The ratio of various metabolites to lipid content was compared between the normal and cirrhosis group. Results : The main characteristic change in proton MR spectra in cases of liver cirrhosis compared with normal liver was decreased relative intensity of lipid peak. Mean and standard deviation of ratio of glutamate + g-lutamine/ lipids, phosphomonoesters/lipids, glycogen + glucose/lipids calculated from the area of their peaks of normal and cirrhotic liver were 0.0204 0.0067 and 0.0693 0.0371 (p0.0090 and 0.0881 0.0276 (p0.0267 and 0.2325 0.1071 (p0 . 0 3 5 5 . Conclusion : Proton MR spectra of liver cirrhosis revealed decreased intensity of lipid with statistical signifi-cance compared with that of normal liver, and peak at 3.9 -4.1 ppm with unknown nature. In conclusion, liver cirrhosis can be diagnosed non-invasively by the analysis of observed proton MR spectroscopic features.

Functional MR Imaging in the Patients with Complex Partial Seizures

Purpose: To evaluate the clinical usefulness of functional MR imaging (fMRI) for localization of the cerebral motor and sensory cortices and the language center in patients with complex partial seizure. Materials and Methods: A total of 47 fMRIs were obtained in 14 patients (M:F=9:5; age 15 -50 years; 13 right handed and 1 ambidextrous) with complex partial seizure (6 temporal lobe epilepsy, 6 frontal lobe epilepsy, 1 occipitotemporal lobe epilepsy, 1 hemispheric epilepsy). Conventional MR imaging revealed no abnormality in four patients, localized cerebral atrophy in one, hippocampal sclerosis in four, and benign neoplasm in the remaining five. fMRI was performed on a 1.5 T MR scanner (GE Signa Horizon) using gradient-echo single-shot EPI. Nineteen fMRIs were obtained in eight patients who performed the language task, 16 fMRIs in ten who performed the motor task and 12 fMRIs in ten who performed the somatosensory task. The activation task consisted of three language tasks (silent picture naming, word generation from a character, categorical word generation), motor tasks (opposition of thumb and index finger for hand/dorsiflexion or extension for foot), and sensory tasks (passive tactile stimulation of hand or foot using a toothbrush). The data were analyzed using z-score (p