bluuebunny/crossref_metadata_2025_split huggingface dataset:
MR imaging of head and neck vascular malformations
Authors: Gelbert François , Riche Marie Claire , Reizine Daniel , Guichard Jean‐Pierre , Assouline Eva , Hodes Jonathan E. , Merland Jean Jacques 
Published: March 2007

AbstractBetween 1980 and 1990, 150 patients with cervicofacial vascular malformations were studied at the authors' institution with computed tomography, plain radiography, and angiography. Since 1989, 34 of these patients have also undergone magnetic resonance (MR) imaging. Capillary‐venous hemangiomas seem to be the best indication for the adjunctive use of MR imaging. The venous pouches, characteristic of this type of lesion, cause elevated signal intensity, well seen on the T2‐weighted images. Excellent fat and muscle differentiation with MR imaging allows appreciation of the depth of extension of these lesions and their delimitation from normal tissue. Arteriovenous malformations (AVMs) are characterized by serpentine signal voids, indicative of the high flow rate of these lesions. Delimitation of the AVM nidus in the midst of the afferent and efferent dilated vessels is often difficult. Study of immature angiomas with MR imaging should be restricted to lesions in specific locations (eg, orbital, laryngeal). Lymphatic malformations showed either tissular or cystic signal intensity changes. MR imaging does not replace other studies but represents an important complementary study for the delineation and diagnosis of deep extensions of vascular malformations, allowing better planning of therapy.
Bowel disease: Prospective comparison of CT and 1.5‐T pre‐ and postcontrast MR imaging with T1‐weighted fat‐suppressed and breath‐hold FLASH sequences
Authors: Semelka Richard C. , Shoenut J. Patrick , Silverman Richard , Kroeker Mervyn A. , Yaffe Clifford S. , Micflikier Allan B. 
Published: March 2007

AbstractThe potential of new high‐field‐strength magnetic resonance (MR) imaging sequences to evaluate bowel disease was investigated and compared with computed tomographic (CT) studies. Thirty‐two patients were studied, 14 with known or suspected gastrointestinal tumors and 18 with known or suspected bowel inflammatory conditions. T1‐weighted fat‐suppressed spinecho and breath‐hold FLASH (fast low‐angle shot) images were obtained before and after intravenous injection of 0.1 mmol/kg gadopentetate dimeglumine. Pathologic confirmation was obtained by biopsy (n = 18), surgical excision (n = 8), or endoscopy (n = 6). CT and MR images were analyzed separately in a prospective fashion and reviewed by consensus. Information from CT and MR images was comparable in cases of confirmed bowel neoplasia. CT scans had better spatial resolution, while fat‐suppressed gadolinium‐enhanced MR images had better contrast resolution. In the 18 cases of bowel inflammation, CT scans showed concentric wall thickening in 16, while MR images showed concentric wall thickening in 14 and increased contrast enhancement in 17. Contrast enhancement was better appreciated on fat‐suppressed images than on FLASH images. The results suggest that MR imaging may play a role in the evaluation of bowel disease.
Experimental hyaline cartilage lesions: Two‐dimensional spin‐echo versus three‐dimensional gradient‐echo MR imaging
Authors: Adam Gerhard , Nolte‐Ernsting Claus , Prescher Andreas , Bühne Markus , Bruchmüller Kira , Küpper Werner , Günther Rolf W. 
Published: March 2007

AbstractThe value of magnetic resonance (MR) imaging, with two‐dimensional (2D) spin‐echo and FISP (fast imaging with steady‐state precession) and FLASH (fast low‐angle shot) three‐dimensional (3D) gradient‐echo sequences, for the detection of hyaline cartilage defects of the femoral condyle and the tibial plateau, was investigated in an animal model. In eight dogs, the anterior cruciate ligament was transected in one knee joint, resulting in rapid development of osteoar‐thritis with degeneration of the hyaline cartilage. At autopsy, 24 cartilage lesions were found, which were classified into four grades. The overall detection of cartilage lesions with MR imaging was poor. Only five of the 24 lesions were visible on 2D spin‐echo images, while 11 of 24 were visible on 3D FISP images and 15 of 24 were seen on 3D FLASH images. The best results were obtained in advanced stages of cartilage degeneration, involving ulceration and complete abrasion of the cartilage layer. Signal loss or signal intensity increase in the cartilage layer was seen inconsistently in grades 3 and 4 degeneration. In this animal model, 2D spin‐echo imaging was inadequate for the diagnosis of hyaline cartilage lesions, while 3D gradient‐echo imaging permitted satisfactory diagnosis in only grade 4 cartilage disease.
MR imaging of microcirculation in rat brain: Correlation with carbon dioxide‐induced changes in blood flow
Authors: Maki Jeffrey H. , Benveniste Helene , Macfall James R. , Piantadosi Claude A. , Johnson G. Allan 
Published: March 2007

AbstractConsiderable interest has been shown in developing a magnetic resonance (MR) imaging technique with quantitative capability in the evaluation of tissue microcirculation (“perfusion”). In the present study, the flow‐dephased/flow‐compensated (FD/FC) technique is evaluated for measuring rat cerebral blood flow (CBF) under nearly optimal laboratory conditions. Imaging was performed on a 2.O‐T system equipped with shielded gradient coils. Rat CBF was varied by manipulating arterial carbon dioxide pressure (Paco2). In parallel experiments, optimized MR imaging studies (seven rats) were compared with laser Doppler flowmetry (LDF) studies (nine rats). LDF values showed a high degree of correlation between CBF and Paco2, agreeing with results in the literature. MR imaging values, while correlating with Paco2, showed considerable scatter. The most likely explanation is unavoidable rat motion during the requisite long imaging times. Because of this motion sensitivity, the FD/FC technique cannot provide a quantitative measure of CBF. It can, however, provide a qualitative picture.
Clearance of liposomal gadolinium: In vivo decomplexation
Authors: Unger Evan C. , Fritz Thomas A. , Tilcock Colin , New Terri E. 
Published: March 2007

AbstractThe contrast agents gadolinium‐DTPA (diethylenetriaminepentaacetic acid), Gd‐DOTA (tetraazacyclododecanetetraacetic acid), and Gd‐HP‐DO3A (1,4,7‐tris[carboxymethyl]‐10‐[2′hydroxypropyl]‐1,4,7,10‐tetraazacyclododecane) are used in humans as extracellular contrast agents. Although free Gd+ ion is toxic, the intact Gd3+ complexes are rapidly excreted and are relatively nontoxic. Decomplexation with release of free gadolinium is a relevant clinical concern in patients with altered renal clearance. Blood pool contrast agents currently under development may have longer clearance half‐lives and be more prone to decomplexation. The present study was designed to evaluate the clearance of liposomally encapsulated Gd3+ complexes (DTPA, DOTA, and HP‐DO3A). The macrocyclic compounds had more rapid and complete clearance than DTPA (P <.05). Parallel studies with carbon‐14 and Gd‐153‐labeled complexes showed significant differences (P <.05) in the amount of these isotopes retained in the heart, kidney, lungs, and spleen, providing strong supportive evidence for in vivo decomplexation.
High‐dose gadoteridol in MR imaging of intracranial neoplasms
Authors: Runge Val M. , Kirsch John E. , Burke Vickie J. , Price Ann C. , Nelson Kevin L. , Thomas Greg S. , Dean Bruce L. , Lee Charles 
Published: March 2007

AbstractTwelve patients with a high suspicion of brain metastases by previous clinical or radiologic examinations were studied in a phase III investigation with magnetic resonance (MR) imaging at 1.5 T after a bolus intravenous injection of 0.1 mmol/kg gadoteridol followed at 30 minutes by a second bolus injection of 0.2 mmol/kg gadoteridol. All lesions were best demonstrated (showed greatest enhancement) at the 0.3‐mmol/kg (cumulative) dose, with image analysis confirming signal intensity enhancement in the majority of cases after the second gadoteridol injection. More lesions were detected with the 0.3‐mmol/kg dose than with the 0.1‐mmol/kg dose, and more lesions were detected with the 0.1‐mmol/kg dose than on precontrast images. In this limited clinical trial, high‐dose gadoteridol injection (0.3‐mmol/kg cumulative dose) provided improved lesion detection on MR images specifically in intracranial metastatic disease.
Reblurred deconvolution method for chemical shift removal in F‐19 (PFOB) MR imaging
Authors: Lee H. K. , Nalcioglu Orhan 
Published: March 2007

AbstractPerfluorocarbons such as perfluoroctylbromide (PFOB) can be used as contrast agents in the vascular system for fluorine‐19 magnetic resonance imaging or as synthetic oxygen carriers. F‐19 imaging has been proposed for studying the vascular system, capillary flow, tissue perfusion, and tumor oxygenation. A major difficulty is that F‐19 compounds often have complex multipeak spectra. These peaks result in chemical shift artifacts, lower signal‐to‐noise ratios, and blurred images. Each peak also excites a different section when a section‐select gradient is applied. Direct inverse filtering is the simplest deconvo‐lution method for correcting such artifacts; however, two major difficulties present themselves: functional singularity and noise amplification at high frequencies. The use of a new reblurred de‐convolution (RED) method appears to overcome these problems. Although this method is based on iterative deconvolution in the spatial domain, the computational overhead is negligible. Since the point spread function and object data are already available in the time domain as FID data, RED appears to be useful for eliminating chemical shift artifacts and suppressing noise amplification while restoring the original image without loss of resolution.
Calculation of three‐dimensional left ventricular strains from biplanar tagged MR images
Authors: Moore Christopher C. , O'Dell Walter G. , McVeigh Elliot R. , Zerhouni Elias A. 
Published: March 2007

AbstractThe noninvasive measurement of time‐resolved three‐dimensional (3D) strains throughout the myocardium could greatly improve the clinical evaluation of cardiac disease and the ability to mathematically model the heart. On the basis of orthogonal arrays of tagged magnetic resonance (MR) images taken at several times during systole, such strains can be determined, but only after heart motion through the image planes is taken into account. An iterative material pointtracking algorithm is presented to solve this problem. It is tested by means of mathematical models of the heart with cylindric and spherical geometries that undergo deformations and bulk motions. Errors introduced by point‐tracking interpolation were found to be negligible compared with those due to marker identification on the images. In a human heart studied with this technique, the corrected radial strains at the left ventricular base were approximately 2.5 times the two‐dimensional estimates derived from the fixed image planes. The authors conclude that material point tracking allows accurate, timeresolved 3D strains to be calculated from tagged MR images, and that prior correction for motion of the heart through image planes is necessary.
MR imaging detection of calcified intracranial lesions and differentiation from iron‐laden lesions
Authors: Gronemeyer Suzanne A. , Langston James W. , Hanna Soheil L. , Langston James W. 
Published: March 2007

AbstractMagnetic susceptibility variation caused by calcium permits limited detection of intracranial calcificatios and/or their distinction from iron‐laden lesions with spin‐echo or gradient‐echo magnetic resonance (MR) techniques. The magnetic susceptibility sensitivity of phase imaging has been used to detect iron‐laden lesions. A new approach that combines the magnetic susceptibility sensitivity of both gradient‐echo and phase imaging to yield greater imaging sensitivity to calcium is presented. Two‐dimensional fast low‐angle shot (FLASH) gradient‐echo imaging with phase image reconstruction (gradient‐echo phase [GEP]) was used at 1.0 and 1.5 T. Twelve patients with computed tomography‐proved calcified intracranial lesions (≥200 HU) and seven patients with iron‐laden intracranial lesions having a characteristic appearance on T1‐and T2‐weighted and FLASH MR images were studied. The GEP imaging technique helped detect calcified intracranial lesions (≥200 HU) and helped distinguish them from iron‐laden lesions.
Detection of acute and treated lesions of hepatosplenic candidiasis: Conparison of dynamic contrast‐enhanced CT and MR Imaging
Authors: Semelka Richard C. , Patrick Shoenut J. , Greenberg Howard M. , Bow Eric J. 
Published: March 2007

AbstractDynamic contrast‐enhanced computed tomography (CT) was compared with 1.5‐T magnetic resonance (MR) imaging with FLASH (fast low‐angle shot), gadolinium‐enhanced FLASH (Gd‐FLASH), and T2‐weighted fat‐suppression (T2FS) sequences in 11 patients with hematologic malignancies, five with biopsy‐confirmed hepatosplenic candidiasis treated with antifungal chemotherapy and six with a clinical history suggestive of acute hepatosplenic candidiasis. CT and MR images were separately interpreted in a prospective fashion. MR imaging showed lesions compatible with candidiasis in the liver in six patients, the spleen in five, and the kidneys in one. CT showed candidiasis‐compatible lesions in the liver in three patients and the spleen in one; no renal lesions were shown. Differences between acute and treated candidal lesions were observed. Gd‐FLASH images showed the most liver lesions (n = 106), followed by FLASH (n = 85), T2FS (n = 20), and CT (n = 18). MR imaging performed better than CT in distinguishing candidal hepatic lesions from recurrent lymphoblastic lymphoma in one patient and from hepatic infarcts in another. The results suggest that MR imaging may be superior to CT in detecting lesions of hepatosplenic candidiasis.
Cardiovascular MR imaging: Current level of clinical activity
Authors: White Richard D. , Ehrnan Richard L. , Weinreb Jeffrey C. 
Published: March 2007

AbstractRelative to other clinical magnetic resonance [MR] imaging activities, cardiovascular [CV] MR imaging has been slow to demonstrate a clinical presence. To better understand the present situation in clinical CV MR imaging, a survey of Society for Magnetic Resonance Imaging (SMRI) members was conducted. A large majority (78%) of the 90 sites responding to the survey reported clinical activity in CV MR imaging. Of these 70 sites, 46% restricted such activity to routine clinical work, while 3% restricted it to clinical research. The remaining 51% conducted both. At all clinical sites. The overall frequency of performance of clinical CV MR imaging was variable (mean, 4.2 and 13.8 cases per month at routine‐only and combined routine‐research sites, respectively]. In clinical CV studies, gated static, multilevel spin‐echo and dynamic gradient‐echo [cine] techniques were most common. At the 68 sites involved in routine clinical CV MR imaging. Primarily anatomic studies composed a much higher proportion of the total [mean, 86%) than primarily functional studies. The evaluation of acquired thoracic aortic disease, congenital cardiac malformation, and para‐or intracardiac mass were the most prevalent anatomic indications overall. Approximately half of the same sites assessed functional aspects of CV disease. The assessment of ventricular dysfunction and valvular dysfunction were the most common functional objectives. The survey indicated that the level of clinical activities in CV MR imaging was low and that most responding sites were involved in clinical CV MR imaging primarily for detection and delineation of anatomic abnormalities.
High‐speed black blood imaging of vessel stenosis in the presence of pulsatile flow
Authors: Chien Daisy , Goldmann Alexander , Edelman Robert R. 
Published: March 2007

AbstractStenosis phantoms were created to study the ability of “black blood” methods to image a vessel stenosis in the presence of pulsatile flow. Black blood images were acquired with a modified TurboFLASH (fast low‐angle shot) method that eliminates flow signal by applying a set of prepulses before segmented data acquisition. With this high‐speed approach, imaging can be completed within 16 seconds. This technique was compared with conventional spin‐echo black blood, gradient‐echo black blood, and gradient‐echo bright blood methods. Loss of flow signal, which extended beyond the site of the stenosis, was seen on the gradient‐echo bright blood images. The pattern of signal loss varied with the type of stenosis. Flow voids were achieved with spin‐echo black blood imaging: however, substantial ghosting artifacts were seen. With gradient‐echo black blood imaging, it was difficult to eliminate all flow signal, particularly for in‐plane flow. The modified TurboFLASH method produced high‐quality black blood images in a fraction of the time needed for spin‐echo imaging. It showed no ghosting artifacts even in the presence of pulsatile flow.
Effect of hypothyroidism on phosphorus metabolism in muscle and liver: In vivo P‐31 MR spectroscopy study
Authors: Hagspiel Klaus D. , Von Weymarn Constantin , McKinnon Graeme , Haldemann Regina , Marincek Borut , von Schulthess Gustav K. 
Published: March 2007

AbstractHypothyroidism is known to affect nearly every organ and organ system of the human body. The goal of the present study was to gain insight into the phosphorus metabolism and bioenergetic function of striated (calf) muscle and liver in patients with hypothyroidism before and after thyroid hormone treatment. With an ISIS (image‐selected in vivo spectroscopy) magnetic resonance (MR) technique for volume selection, phosphorus‐31 metabolism of the calf muscle in 10 patients and of the liver in seven patients with severe hypothyroidism was studied before and after treatment. In addition, spectra from the calf muscle and liver were obtained in 10 healthy volunteers. Relative to those from the healthy subjects, the P‐31 MR spectra from patients with hypothyroidism showed a significantly diminished phosphocreatine/inorganic phosphate ratio (P < .01). After thyroid hormone substitution therapy, this ratio returned to normal values within several weeks. No statistically significant changes in the spectra of liver tissue could be detected. The results support the theory that hypothyroidism induces a hormone‐dependent, fully reversible impairment of the energy metabolism of striated muscle. Changes in liver metabolism observed with biochemical methods are apparently not detectable with state‐of‐the‐art P‐31 MR spectroscopy.
Reduced‐bandwidth method for F‐19 imaging of perflubron
Authors: Lee H. K. , Nalcioglu Orhan 
Published: March 2007

AbstractA reduced‐bandwidth imaging method has been developed to eliminate the chemical shift artifacts in magnetic resonance (MR) imaging of the blood substitute perflubron (PFB) and simultaneously enhance the signal‐to‐noise ratio (SNR). The two strongest spectral peaks, which have relatively long T2 values (247 and 471 msec), were used. When the receiver bandwidth is reduced substantially by increasing the data acquisition time Ts, the bandwidth across the object becomes less than the chemical shift frequency. The reduced bandwidth eliminates misregistration by displaying the images corresponding to multiple spectral peaks on the same image plane simultaneously. An additional gain due to the reduced bandwidth is the reduced thermal Gaussian noise. Unfortunately, the increased Ts results in an increased TE, which causes the signal to be attenuated by T2 relaxation. The optimum measured Ts (and TE) values for successful image separation and maximum SNR were 120 and 144 msec for the two spectral peaks, respectively. The long TE also suppresses the rest of the downfield spectral peak cluster of PFB. The degree of magnetic field inhomogeneity and tissue susceptibility across the object may cause some limitations in the application of this technique; however, a composite radio‐frequency pulse that will allow use of additional spectral lines and/or localized volume imaging techniques may be incorporated to overcome these limitations.
Rapid fat/water assessment in knee bone marrow with inner‐volume rare spectroscopic imaging
Authors: Oshio Koichi , Mulkern Robert V. 
Published: March 2007

AbstractAn inner‐volume modification of a spectroscopic imaging technique based on RARE (rapid acquisition with relaxation enhancement) sequences is shown to provide, in less than 1 minute, spectra suitable for fat/ water peak‐area integration from selected imaging columns containing more than 1,000 5 × 5 × 1‐mm voxels. A limitation is the unavoidable T2 weighting of the spectral peaks, which influences estimations of true fat/ water composition from the spectra. Studies obtained in the knees of healthy volunteers demonstrate the ability of the technique to enable characterization of the two major proton peaks in bone marrow. Data collected at two or more effective TEs are suitable for extrapolation of fat/water estimates to zero TE.
Routine quantitative analysis of brain and cerebrospinal fluid spaces with MR imaging
Authors: Kikinis Ron , Shenton Martha E. , Gerig Guido , Martin John , Anderson Mark , Metcalf David , Guttmann Charles R. G. , McCarley Robert W. , Jolesz Ferenc A. , Lorensen William , Cline Harvey 
Published: March 2007

AbstractA computerized system for processing spin‐echo magnetic resonance (MR) imaging data was implemented to estimate whole brain (gray and white matter) and cerebrospinal fluid volumes and to display three‐dimensional surface reconstructions of specified tissue classes. The techniques were evaluated by assessing the radiometric variability of MR volume data and by comparing automated and manual procedures for measuring tissue volumes. Results showed (a) the homogeneity of the MR data and (b) that automated techniques were consistently superior to manual techniques. Both techniques, however, were affected by the complexity of the structure, with simpler structures (eg, the intracranial cavity) showing less variability and better spatial correlation of segmentation results between raters. Moreover, the automated techniques were completed for whole brain in a fraction of the time required to complete the equivalent segmentation manually. Additional evaluations included interrater reliability and an evaluation that included longitudinal measurement, in which one subject was imaged sequentially 24 times, with reliability computed from data collected by three raters over 1 year. Results showed good reliability for the automated segmentation procedures.
MR angiography with a cardiac‐phase–specific acquisition window
Authors: Selby Katherine , Saloner David , Anderson Charles M. , Chien Daisy , Lee Ralph E. 
Published: March 2007

AbstractA method for cardiac‐phase–specific magnetic resonance (MR) angiography is presented. An electronics module permits incrementing of phase‐encoding gradients and storage of incoming data only during a chosen portion of the cardiac cycle. Suppression of stationary material is maintained by delivering radio‐frequency pulses at constant TR throughout the cycle. Imaging of a pulsatile flow phantom demonstrates that acquiring data only during systole substantially increases the signal intensity of flowing material. In addition, phase‐encoding ghost artifacts are eliminated from the neighborhood of the vessel. Image acquisition time is minimized by acquiring only the low‐frequency phase‐encoding lines in the cardiac‐phase–specific mode. In healthy volunteers, greatly improved MR angiograms of the lower extremities are obtained. Fat saturation and magnetization transfer further enhance vessel/background contrast. Acquiring data only during systole ensures rapid inflow for all phase‐encoding lines, permitting a near‐longitudinal section orientation without in‐plane saturation. This substantially reduces total acquisition time relative to axial acquisition.