bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mitral valve flow measured with cine MR velocity mapping in patients with ischemic heart disease: comparison with doppler echocardiography
Authors: Karwatowski Stefan P. , Brecker Stephen J. D. , Yang Guang Z. , Firmin David N. , Sutton Martin St John , Underwood S. Richard 
Published: March 2007

AbstractDiastolic function is an important element of overall left ventricular function. The pattern of flow across the mitral valve is commonly used as a measure of diastolic ventricular function. Magnetic resonance (MR) velocity mapping of blood flow across the mitral valve was compared with Doppler echocardiography. Nineteen patients with known coronary artery disease (mean age. 62 years: 11 with previous myocardial infarction) were studied. The mean value of peak early filling velocity (± standard deviation) was 60.1 cm/sec ± 14.3 with the MR method and 59.4 cm/sec ± 13.7 with echocardiography (P = 0.732). The mean difference between the two measurements (95% confidence interval) was −0.8 cm/sec (−5.2 cm/sec. +2.2 cm/sec). The mean value of early deceleration was 4.3 mlsec2 ± 1.5 with the MR method and 4.0 m/sec2 ± 1.5 with echocardiography (P = 0.073). The mean Werence was −0.4 cm/sec2 (−0.92 cm/eec2. +0.05 cm/sec2). The mean value of peak atriosystolic velocity was 51 cm/sec ± 14.6 with the MR method and 62 cm/sec ± 17.2 with echocardiography (P = 0.002). The mean difference was −11 cm/sec (−18.1 cm/sec, −3.45 cm /sec). Peak atrial filling was consistently lower with the MR method than with echocardiography. Time‐averaged measurements of ventricular fflling with MR velocity mapping are an accurate measure of early diastolic filling but underestimate the velocity of atriosystolic fflling.
Contrast‐enhanced MR imaging of intrahepatic cholangiocarcinoma: Pathologic correlation study
Authors: Murakami Takamichi , Nakamura Hironobu , Tsuda Kyo , Ishida Takeshi , Tomoda Kaname , Hori Shinichi , Monden Morito , Kanai Toshio , Wakasa Kenichi , Sakurai Masami , Kozuka Takahiro 
Published: March 2007

AbstractThe authors describe the enhanced magnetic resonance (MR) imaging appearance of intrahepatic Cholangiocarcinoma. The MR Images of eight patients with intrahepatlc Cholangiocarcinoma who underwent MR examination within 3 weeks before partial hepatectomy were retrospectively studied. The MR images, including a dynamic study, were compared directly with pathologic and histologic findings. The peripheral region of the medullary subtype of Cholangiocarcinoma, with many tumor cells, showed greater enhancement relative to liver parenchyma in the early phase. The peripheral region of the scirrhous subtype, with fewer tumor cells showed less enhancement in the early phase. In one patient, the thin rim of the medullary tumor showed less enhancement in the late phase, and this rim corresponded to the peripheral region of the medullary tumor with many tumor cells. The central region of tumors with a large amount of fibrous tissue showed prolonged enhancement in the late and delayed phases. The thin rim of liver parenchyma around the tumor showed less enhancement in the early phase and greater enhancement in the late phase; this rim corresponded to congestive liver parenchyma with dilated sinusoids. Intrahepatic Cholangiocarcinoma shows various enhancement patterns, which depend on both the histologic subtype and the degree and distribution of flbrosis within the tumor.
Adrenocortical carcinoma: MR imaging appearance with current techniques
Authors: Schlund James F. , Kenney Philip J. , Brown Elizabeth D. , Ascher Susan M. , Brown Jeffrey J. , Semelka Richard C. 
Published: March 2007

AbstractThe purpose of the study was to define the magnetic resonance (MR) imaging appearance of adrenocortical carcinoma (ACC) with current MR techniques. Eight patients with ACC underwent high‐field‐strength MR imaging with the following sequences: axial T1‐weighted gradient echo, fat‐suppressed T1‐weighted spin echo, fat‐suppressed T2‐weighted spin echo, and gadolinium‐enhanced T1‐weighted gradient echo and fat‐suppressed T1‐weighted spin echo. Postcontrast images were also acquired in the sagittal (six patients) and coronal (three patients) planes. Out‐of‐phase gradient‐echo images were obtained in two patients. Lesion morphology, signal intensity features, and presence of metastatic disease were retrospectively evaluated. MR imaging features of ACC included internal hemorrhage (seven of eight patients), central necrosis (seven of eight), and peripheral enhancing nodules (seven of eight). Out‐of‐phase images in two of two patients demonstrated signal loss compared with in‐phase images, which may be a common feature of these tumors. Liver metastases were present in four patients. Consistent MR features of ACC are Identified.
Understanding acceleration‐induced displacement artifacts in phase‐contrast MR velocity measurements
Authors: Frayne Richard , Rutt Brian K. 
Published: March 2007

AbstractA theoretical framework for understanding acceleration‐induced errors in phase‐contrast magnetic resonance velocity measurements has been developed. An important result of this framework is the interpretation of acceleration‐induced velocity errors as displacement artifacts due to the delay between velocity and spatial encoding. A rotating‐disk phantom was used to confirm the theoretically predicted displacement times (the difference between theory and experiment was 8.2%). Errors were also observed in velocity profiles measured in regions of fluid acceleration downstream from a step stenosis. The magnitude of these errors could be predicted and corrected by using the analytic framework.
Selection of K‐space samples in localized MR spectroscopy of arbitrary volumes of interest
Authors: Reeves Stanley J. 
Published: March 2007

AbstractA number of Image modeling techniques have been proposed to represent magnetic resonance spectro‐scopic images. The goal of these techniques is to reduce the amount of data and thus the time required to reconstruct the image. However, little attention has been given to the choice of k‐space samples. The combination of samples acquired has a great effect on the quality of the reconstructed image. A new method for optimizing the choice of k‐space samples—in which samples from a candidate set are sequentially eliminated in a computationally efficient manner until the desired number remain—is presented and demonstrated by means of simulations.
Fast spin‐echo imaging of the temporomandibular joint
Authors: Rao Vijay M. , Vinitski Simon , Liem Marina , Rapoport Robert 
Published: March 2007

AbstractThe applicability of a fast spin‐echo (PSE) technique for magnetic resonance imaging of the tem‐poromandibular joint (TMJ) was studied, and the technique compared with a conventional spin‐echo (CSE) technique. Sagittal Tl‐weighted CSE and dual‐echo FSE images of 50 TMJs in 25 patients with symptoms of internal TMJ derangement were compared. CSE and FSE images were diagnostically comparable in 22 TMJs (44%). The FSE technique was rated better than CSE imaging for delineation of the disk in 26 joints (52%), whereas the CSE technique was rated better in only two joints (4%). The FSE technique was preferred overall in 54% of the joints. Mild to moderate joint effusion was detected in 17 joints because additional T2‐weighted data were provided with the dual‐echo FSE technique. The study showed that FSE imaging is an effective technique for evaluation of the TMJ. It is faster and diagnostically comparable to or better than CSE imaging, with the added advantage of providing T2‐weighted data.
Segmentation of small structures in MR images: Semiautomated tissue hydration measurement
Authors: Koechner Donna , Petropoulos Helen , Eaton R. Philip , Hart Blaine L. , Brooks William M. 
Published: March 2007

AbstractSegmentation of small anatomic structures In noisy magnetic resonance (MR) images is inherently challenging because the edge Information is contained in the same high‐frequency image component as the noise. The authors overcame this obstacle in the analysis of the sural nerve in the ankle by processing images to reduce noise and extracting edges with an edge detection algorithm less sensitive to noise. Anatomic accuracy of the segmentation was confirmed by a neuroradiologist. A nerve hydration coefficient was determined from the signal intensity of the nerve in these segmented images. These semiautomated measurements of hydration agreed closely with those obtained with a previously described manual method (n=44, P=.76). Each image in the study was analyzed identically, with no modification of the computer algorithm parameters. The data suggest that this robust method may be useful in a multicenter evaluation of diabetes treatment protocols.
Mr cholangiopancreatography: Comparison between two‐dimensional fast spin‐echo and three‐dimensional gradient‐echo pulse sequences
Authors: Reinhold Caroline , Guibaud Laurent , Genin Gilles , Bret Patrice M. 
Published: March 2007

AbstractThe purpose of our study was to perform a prospective comparative analysis of three‐dimensional (3D) steady‐state free precession (SSFP) and two‐dimensional (2D) fast spin‐echo (FSB) imaging in the evaluation of 26 patients with suspected bile duct obstruction. SSFP and highly T2‐weighted FSB sequences were obtained for each patient in multiple planes. Both sequences were reviewed independently and results were compared with findings from direct cholangiography (n = 17) or from a combination of sonography and CT (n = 9). The extrahepatic bile duct (EHBD) and intrahepatic bile duct (IHBD) were dilated In 32% and 54% of patients, respectively. The EHBDs were visualized in 44% of patients with SSFP. versus in 96% with FSE. One or more IHBD segments were seen In 42% of the SSFP sequences and in 100% of the FSB sequences. A portion of, or the entire, pancreatic duct was seen in 23% of the SSFP sequences and in 65% of the FSE sequences. Our findings lead us to conclude that T2‐weighted FSE sequences are superior to SSFP sequences In visualizing the biliary tree and pancreatic duct and that they should replace gradient‐echo sequences in MR Cholangiopancreatography.
A segmented k‐space velocity mapping protocol for quantification of renal artery blood plow during breath‐holding
Authors: Thomsen C. , Cortsen M. , Söndergaard L. , Henriksen O. , Ståhlberg F. 
Published: March 2007

AbstractTwo Important prerequisites for MR velocity mapping of pulsatile motion are synchronization of the sequence execution to the time course of the flow pattern and robustness toward loss of signal in complex flow fields. Synchronization is normally accomplished by using either prospective ECG triggering or so‐called retrospective gating. However, if the studied vessel moves periodically in space as a result of respiratory motion, as in the case of renal arteries, a second synchronization with respect to the vessel motion in space may be necessary. One method to overcome this problem is to use the segmented k‐space technique, in which the entire data acquisition can be made within a breath‐hold by the sampling of several phase‐encoding lines within a small time window during each heart cycle. The aim of this study was to investigate the performance of a segmented k‐space velocity mapping protocol for renal artery flow determination. The protocol uses 16 phase‐encoding lines per heart beat during 16 heart cycles and gives a temporal velocity resolution of 160 msec. Comparison with a conventional ECG‐triggered velocity mapping protocol was made in phantoms as well as in volunteers. In our study, both methods showed sufficient robustness toward complex flow in a phantom model. In comparison with the ECG technique, the segmentation technique reduced vessel blurring and pulsatility artifacts caused by respiratory motion, and average flow values obtained in vivo in the left renal artery agreed between the two methods studied. Although presently hampered by a relatively low temporal resolution, velocity mapping with k‐space segmentation In combination with breath‐holding will benefit from future increased gradient quality, and we assume that in the future the method will become an attractive choice for noninvasive renal artery flow determination.
Influence of bolus volume and dose of gadolinium chelate for first‐pass myocardial perfusion MR imaging studies
Authors: Canet Emmanuelle , Douek Philippe , Bendid Karim , Revel Didier , Amaya Juventino , Millet Philippe , Janier Marc 
Published: March 2007

AbstractFirst‐pass MR myocardial perfusion measurements require a well‐defined left ventricular (LV) blood pool input function. We used a peripheral intravenous (IV) injection of a gadolinium (Gd) chelate to obtain a well‐characterized LV time‐intensity curve. Using a strongly T1‐weighted subsecond MR sequence, we performed cardiac MR imaging after administering an IV bolus injection of one of three different doses of the Gd chelate: a standard dose (0.1 mmol/kg, group I, n = 8); a low dose with two bolus volumes (0.01 mmol/kg, l/10e bolus volume, group n, n = 7, and 0.01 mmol/kg diluted in saline, same bolus volume as group I, group III, n = 3); and an intermediate dose (0.05 mmol/kg, group IV, n = 5). Unlike in group I (high dose), in groups n and m (low dose), the LV curve had a well‐defined first peak, followed by a downslope and a recirculation peak. With the intermediate dose (group IV), a saturation effect still remained on the LV curve. The signal intensity (SI) enhancement of the myocardium was respectively 580 ± 77% at 0.1 mmol/kg, 362 ± 95% at 0.05 mmol/kg, and at 0.01 mmol/kg, it was 184 ± 33% in group II and 272 ± 8% in group m. In conclusion, with subsecond T1‐weighted MR imaging and a low dose of Gd chelate (i.e., 0.01 mmol/kg). the LV input function is a well‐defined first step for MR perfusion modeling.
Correlation between high‐field t2‐ weighted MR imaging and histology of ischemic lesions in gerbil brain
Authors: Hockings Paui D. , Rose Stephen E. , Crozier Stuart , Roffman Wolfgang , Doddrell David M. , Middleton David A. , Reid David G. , Patel Sara , Samson Nicole A. , Rothaul Alan L. , Hunter Jackie A. 
Published: March 2007

AbstractGlobal forebrain ischemia in the Mongolian gerbil is a common animal model for use in stroke research. We produced lesions of graded severity in gerbil brains (after prescreening by MR imaging) by performing 6 minute bilateral carotid artery occlusions while monitoring pericranial temperature with a temporalis muscle thermocouple probe and maintaining the temperature at 32°C 36°C. or 40°C. Lesion severity was scored 4 days after occlusion from findings on spin‐echo images acquired at 7 T and from histologic scores. Statistically signiflcant correlation was observed between the MR imaging score and brain temperature and between the MR imaging score and the area of the CA region of the hippocampus measured by histology. In addition, because prescreening with MR imaging revealed abnormalities in the hippocampus of some of the animals, and these animals were rejected from the study. the statistical significance of the result could be strengthened.
Flow patterns in the dilated ischemic left ventricle studied by MR imaging with velocity vector mapping
Authors: Mohiaddin Raad H. 
Published: March 2007

AbstractMagnetic reaonance velocity vector mapping was used to study flow patterns in dilated and healthy left ventricles. Eleven patients (age mean ± SD, 67 ± 12 yeare) with dilated left ventricle resulting from coronary artery diclease and 10 healthy volunteers (age 50 ± 9) were studied. Cine gradient echo images were acquired in the left ventricle vertical and horizontal long axes. Vertical and horizontal velocity components in the horizontal long axis plane of the left ventricle were encoded simultaneously. Maps of velocity components were then processed into multiple computer generated streaks whose orientation and length corresponded to velocity vectors. The following parameters (mean ± SD) differed significantly between the two groups: The heart rate (patients 70 211 beat/min. controls 57 ± 8, P <.001). end‐diastolic volume (patients 264 ± 83 ml. controls 143 ± 26 ml. P <.001). ejection fraction (patients 31% ± 7, controls 61% ± 6, P < .MI), diameter of the Mow stream (patients 1.7 ± 0.6 cm. controls 3.2 2 0.3 cm. P <.001). In normal subjects the predominant direction of diastouc now through the mitd valve was toward the apex with short‐lived vortices curling back behind each mitral ldet. The vortex beneath the anterior leaflet tended to be larger and more dominant. In patients with dilated left ventricle, the inflow was directed toward the free wall, giving rise to a well developed circular flow pattern turning back toward the septum and outflow tract and persisting through diastole. Magnetic resonance velocity vector mapping is an excellent method for studying left ventricular flow patterns. We have studied flow patterns in healthy volunteers and demonstrated abnormalities in patients with dilated left ventriclea resulting from coronary artery disease.
Gadolinium zeolite as an oral contrast agent for magnetic resonance imaging
Authors: Young Stuart W. , Qing Fan , Rubin Daniel , Balkus Kenneth J. , Engel Julie S. , Lang Johanna , Dow William C. , Mutch James D. , Miller Richard A. 
Published: March 2007

AbstractThe purpose of thls study was to evaluate efficacy and safety of a gadolinium (Gd) zeolite suspension aa an oral MRI contrast agent. Serial dilution of GADO‐ LITE@ orpl Suspdon 1.2500 pg of GdO/mL) were prepared. MRI (T1 and T2 welghted) of standards and dogs (precontrast and postcontraat) were performed. Toxicity and Gd absorption were also asmaued. Subsequently, 30 nod male adult volunteers were divided into six group of five subjects each. Gd zeolite po suspension waa adminlstered before and after MRI in volumes and concentrations ranging from 250 to 1600 mL; 6 to 80 pg of Gd+3/mL. The images were rated (efficacy score) by a bllnded reader. Vital signs, blood chemistries and urlnalysia were recorded. Gadollte Oral Suspension produced excellent enhancement of the dog gastrointestinal (GI) tract. No todclty or absorption of Gd wan obsenred in dogs receiving doses up to 4 times the anticipated human dose My for 14 consecutive days. In clinical tri.lr. Gd zeollte slgnlficantly lmproved the efficacy scores for all groups and all pulrina sequences (all P values <.05). Efflcacy scores and slgnal intendtics generally increased with concentration and volume. No Gd waa detected in blood or urine specimens. No signiftcant adverse events were reported. Gd zeolite 1s a promlsing contrast medium for enhancement of the GI tract in MRI.
Temporal phase unwrapping for cine velocity imaging
Authors: Xiang Qing‐San 
Published: March 2007

AbstractA simple algorithm named temporal phase unwrapping (TPU) is introduced to address the phase aliasing problem in time‐dependent pa contrast (CINE‐PC) velocity imaging. The method exploits the temporal continuity of velocity field and unwraps the phmc along time. TPU only involver a one‐dimensional (1D) temporal integration: therefore. many complications in 2D or 3D spatial phpee unwrapping are avoided. Differential velocity map (DVM) between adjacent movie framer arc first calculated from the complex MR imager. The DVM. have no phase aliasing no the differential velocities arc much smaller than the absolute velocities. ‐–free velocity maps are obtained by integrating the DVMs along the time direction provided M aliasing‐free reference velocity map (RVM) is found as a starting point of the integration. typically, much RVMs are always available within the cardiac cycle, especially in diastole where the blood flow is the lowest. In vivo rceults from fully automated processing and detailed discussion on noise behavior are presented.
A monoclonal antibody to α4‐integrin reverses the MR‐detectable signs of experimental allergic encephalomyelitis in the Guinea pig
Authors: Kent Sharon J. , Karlik Stephen J. , Rice George P. A. , Horner Heidi C. 
Published: March 2007

AbstractExperimental allergic encephalomyelitis (EAE) is a T cell‐mediated autoimmune disease of the CNS characterized by blood‐brain barrier breakdown. cerebral edema formation, lymphocyte infiltration, and demy‐elination, and is used as an animal model of multiple sclerosis (MS). MR imaging is important for the diagnosis of MS and for the evaluation of potential new therapier. In this study, T2‐weighted and T1‐weighted contrast‐enhanced MR imaging was used to evaluate the effectiveness of an antiadhesion therapy in EAE. Leukocyte‐endothelial adhesion at the blood‐brain barrier is considered an essential step in the mediation of CNS leukocyte infiltration in EAE.AN100226m. a monoclonal antibody to α4 integrin has been previously shown to reverse the clinical and histologic signs of EAE by blocking this interaction. In the present study, AN100226m treatment in acute EAE significantly decreased contrast enhancement of the CNS parenchyma indicating closure of the blood‐brain barrier. The percentage of pixele due to leakage of contrast material in T1‐weighted images decreased to <4% in AN100226m‐treated animals whereas it was increased to 15% in control animal (P <.05. Mann‐Whitney rank sum test). A decrease in CNS abnormalities associated with cerebral edema and inflammation was also obsaved on T2‐weighted images (P < ‐05, Mann‐Whitney rank sum test). Thus, an antibody to α4 integrin reversed the blood‐brain barrier permeability changes characteristic of acute EAE. In addition, the further accumulation of innammatory edema was prevented and preexisting edema was resolved.
Appearance of the Normal Pericardium on Coronary MR Angiograms
Authors: Bogaert Jan , Duerinckx André J. 
Published: March 2007

AbstractWe evaluated the appearance of the normal pericardium on breath‐hold MR images used to visualize coronary arteries. A coronary MR angiogram was obtained in 23 subjects (17 healthy volunteers and six patients with no known pericardia! disease) using a breath‐hold K‐space segmented gradient‐recalled echo sequence with fat suppression. Each coronary MR angiographic study included imaging planes equivalent to the following echocardiographic planes: four‐chamber view, vertical two‐chamber view, and two short‐axis views (at base and mid ventricular level). The average pericardial thickness was 1.7 mm (range, 1.5–2.0 mm), and an average length of 60 mm (range, 20–110 mm) of pericardium was visualized. A significantly longer portion of the pericardium was seen in the vertical two‐chamber view and the basal short‐axis view than in the two other views (P <.001). Normal anatomic variations and overlapping structures and image artifacts can alter the appearance of the pericardium. Breath‐hold MR imaging techniques used for coronary MR angiography allow routine, time‐efficient evaluation of large portions of the pericardium.
Feasibility of MR Diffusion Studies in the Kidney
Authors: Siegel Cary Lynn , Aisen Alex M. , Ellis James H. , Londy Frank , Chenevert Thomas L. 
Published: March 2007

AbstractRenal apparent diffusion coefficients (ADCs) were anisotropic within and significantly different between cortex and medulla using a relatively motion‐insensitive one‐dimensional technique in 20 volunteers. ADC values ranged from 1.79 ±.39 to 2.95 ±.58(× 10‐3mm2/sec), relatively high but similar to other reports. Further investigation may help clarify this data, and determine whether the findings result from diffusion properties (and/or radially oriented parenchymal architecture), or artifacts due to factors such as bulk motion.