bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rectal barium in pelvic MR imaging: Initial results
Authors: Panaccione John L. , Ros Pablo R. , Torres Gladys M. , Burton Sharon S. 
Published: March 2007

AbstractPelvic magnetic resonance (MR) imaging is limited by lack of an effective bowel contrast agent. This study was performed to evaluate the efficacy of rectally administered barium sulfate as a contrast agent in pelvic MR imaging. Thirty‐two patients were studied retrospectively to evaluate anatomic definition of the rectosigmoid colon. A commercially available barium sulfate suspension was administered rectally in 19 patients. Thirteen patients were imaged without barium. In the latter patients, anatomic definition of the rectum and sigmoid colon was poor to fair with all pulse sequences. Delineation of the rectum and sigmoid colon improved in patients who received rectal barium, owing to distention and marking of the bowel by the predominately low‐signal‐intensity barium. Barium is a safe, inexpensive negative contrast agent for bowel that may improve pelvic MR imaging.
OMR, a positive bowel contrast agent for abdominal and pelvic MR imaging: Safety and imaging characteristics
Authors: Patten Randall M. , Moss Albert A. , Fenton Theresa A. , Elliott Sharon 
Published: March 2007

AbstractTo determine the safety and imaging characteristics of OMR — an effervescent solution of ferric ammonium citrate — as a bowel contrast agent, magnetic resonance (MR) imaging at 1.5 T was performed in 29 volunteers. T1‐ and T2‐weighted images of the upper abdomen and pelvis were obtained before and after oral administration of OMR at doses of 100–400 mg of iron in 300–600 mL of water. Respiratory‐ordered phase encoding and presaturation pulses were used routinely for artifact suppression. All dose levels of OMR provided marking of the bowel by increasing intraluminal signal intensity; however, the degree and percentage of small bowel opacification appeared more prominent at higher dose levels of iron. Semisolid or watery bowel movements were noted in 31% of subjects, but no clinically important laboratory abnormalities were seen. OMR improved delineation of the head of the pancreas on T1‐weighted images in 72% of subjects but was less useful in defining the body and tail. OMR is a safe and effective bowel contrast agent for MR imaging. Because artifacts due to movement of hyperintense bowel may degrade the images, OMR may be most useful on short TR/TE or fast imaging pulse sequences or when combined with antiperistaltic agents.
MR imaging characteristics of noncancerous lesions of the prostate
Authors: Lovett Karen , Rifkin Matthew D. , McCue Peter A. , Choi Hong 
Published: March 2007

AbstractRadical prostatectomy specimens from 53 men with clinical stage A or B prostate cancer were retrospectively reviewed and compared with correlative axial T2‐weighted magnetic resonance (MR) images obtained just before surgery. Non‐cancerous lesions were evaluated for signal intensity and location. Focal high‐signal‐intensity areas (n = 72) were present in 81% of patients. The 26% of lesions seen in the central gland all correlated with cystic atrophy. Of the 53 lesions seen in the peripheral prostate, 47 (89%) were cystic atrophy without associated cancer, four (7.5%) cystic atrophy with cancer, and two (3.8%) focal inflammation. Focal low‐signal‐intensity areas (n = 42) were present in 60% of patients. Of the 31% of lesions in the central prostate, one‐fifth correlated with benign prostatic hyperplasia (BPH) and four‐fifths with fibrous tissue. Of the 69% of peripheral lesions, 83% corresponded to fibrous tissue, 10% to BPH, and 7% to normal tissue. Mixed lesions (n = 42) were present in 64% of patients; 86% of these were located centrally and 14% peripherally. All mixed central lesions were BPH; the peripheral lesions were areas of combined cystic atrophy and fibrosis. BPH of low or mixed signal intensity can extend into the peripheral prostate and mimic cancer. High‐intensity cystic atrophy associated with cancer can mimic normal tissue.
Fast, interactive algorithm for segmentation of a series of related images: Application to volumetric analysis of MR images of the heart
Authors: Wang Jin Zhao , Turner David A. , Chutuape Mariano D. 
Published: March 2007

AbstractMagnetic resonance (MR) cine images of the beating heart have excellent spatial and temporal resolution. Extracting the boundaries of the heart from MR images for volumetric measurements is of considerable interest; however, since the number of images involved is large, tracing the boundaries by hand is tedious and prohibitively time consuming. The authors have developed an interactive method of boundary detection that uses the correlation between the cardiac boundaries on temporally or spatially adjacent images to increase the speed of the process and reproducibility of the measurement. A simulated cine MR study of a phantom (total of 155 images) and cardiac cine studies of two patients (192 images each) were analyzed by two independent observers. Analysis of the phantom data was completed in 5.6 minutes (2.16 seconds per image) by observer 1 and 6.3 minutes (2.4 seconds per image) by observer 2. The percent measurement errors for 31 phantom volumes (30‐120 mL) were 0.96% and 0.83% for observers 1 and 2, respectively. The observers analyzed the patient studies in 14‐23 minutes (4.4‐7.2 seconds per image), with interobserver variabilities of 5.8% and 3.7% for the two patients, respectively. The authors conclude that their flexible, semiautomatic, interactive algorithm allows rapid and reproducible detection of structural boundaries.
MR imagin—histopathologic correlation of thermal injuries induced with interstitial Nd:YAG laser irradiation in the chronic model
Authors: Anzai Yoshimi , Lufkin Robert B. , Farahani Keyvan , Hirschowitz Sharon , Castro Dan J. 
Published: March 2007

AbstractMagnetic resonance (MR) imaging–histopathologic correlation of thermal injuries induced with interstitial laser irradiation was performed in a chronic model up to 12 weeks after laser exposure. T2‐weighted MR images showed irreversible coagulative necrosis as a low‐signal‐intensity area. A higher‐intensity surrounding area, corresponding to edema, was also present in acute lesions on T2‐weighted images. Serial studies of the chronic model showed that a substantial portion of the interstitial edema zone progressed to coagulative necrosis up to 7 days after laser irradiation. This necrotic zone decreased in size beyond 2 weeks, presumably through biologic healing. MR imaging and pathologic findings correlated well in the chronic model. MR imaging has the potential to depict acute, irreversible thermal damage even before morphologic change is seen at the standard pathologic examination. Recognizing the dynamics of tissue response to interstitial laser irradiation on MR images is valuable for estimation of true lesion volume.
Effect of Gd‐DTPA‐BMA on magnetization transfer: Application to rapid imaging of cardiac ischemia
Authors: Jones Richard A. , Haraldseth Olav , Schjott Jan , Brurok Heidi , Jynge Per , Oksendal Audun N. , Rinck Peter A. 
Published: March 2007

AbstractThe addition of a paramagnetic contrast agent reduces the magnetization transfer effect between the free and restricted proton pools in both agar phantoms and cardiac muscle tissue. This reduction is due to the reduction in the intrinsic T1 of the free proton pool and increases the signal observed after a given magnetization transfer sequence. Images of ex vivo piglet hearts were obtained with a segmented snapshot FLASH (fast low‐angle shot) sequence with a 128 × 128 matrix, four segments, and two signals averaged, resulting in an imaging time of 7 seconds. Magnetization transfer was induced by applying a DANTE (delays alternating with nutations for tailored excitations) pulse sequence in the intersegment interval. This was an efficient method of inducing magnetization transfer because it excites the restricted proton pool across the full frequency spectrum. Ischemia due to occlusion of the left anterior descending branch of the coronary artery could be visualized after infusion of gadolinium di‐ethylenetriaininepentaacetic acid‐bis(methylamide) (DTPA‐BMA). Although the ischemia could be seen with the basic sequence, the contrast between isch‐emic and non‐ischemic tissue improved when the magnetization transfer sequence was included. The most marked improvements in magnetization transfer were achieved with low doses of Gd‐DTPA‐BMA.
Liquid oral magnetic particles as a gastrointestinal contrast agent for MR imaging: Efficacy in vivo
Authors: Rubin Daniel L , Muller Holde H. , Sidhu Manrita K. , Young Stuart W. , Hunke William A. , Gorman William G. 
Published: March 2007

AbstractRecent in vitro studies suggested there is an optimal range of concentration and viscosity for a liquid formulation of oral magnetic particles (WIN 39996) for magnetic resonance (MR) imaging of the gastrointestinal (GI) tract. To determine whether this formulation is also effective in vivo and whether differing viscosity and administration regimen affect GI distribution of the contrast agent, a range of concentrations of iron (75, 150,and 200 μg/mL) and viscosities (1, 150, and 600 cp) were imaged in dogs at 1.5 T with conventional spin‐echo and fat‐saturation pulse sequences. The effects of dose regimen (single vs divided dose) and subject position (supine vs right lateral decubitus) were also studied. The 75 and 200 μg/mL concentrations were unacceptable for MR imaging, while 150 μ.g/mL was effective. The GI distribution of the contrast agent was affected jointly by viscosity, subject position, and dose regimen. The 150 μg/mL formulation produced excellent GI contrast enhancement in vivo for both 150‐ and 600‐cp viscosities. The choice of optimal viscosity may depend on the preferred administration regimen.
Contrast‐enhanced MR angiography
Authors: Runge Val M. , Kirsch John E. , Lee Charles 
Published: March 2007

AbstractMagnetic resonance (MR) angiography, although still in its infancy, is recognized as a valuable diagnostic tool. Investigation of the utility of contrast media as applied to MR angiography is, to no surprise, preliminary. In restricted instances, with present techniques, contrast media‐enhanced MR angiography can provide additional valuable diagnostic information. Inspection of two‐dimensional images (as opposed to three‐dimensional projections) and comparison of MR images before and after administration of contrast agent are particularly important. Improved visualization of intracranial aneurysms, arteriovenous malformations, venous anomalies, and arterial occlusions has been demonstrated on three‐dimensional time‐of‐flight MR angiograms after intravenous administration of a gadolinium chelate, relative to studies performed before administration of the contrast agent.
Aortoiliac disease: Two‐dimensional inflow MR angiography with lipid suppression
Authors: Mulligan Susan A. , Doyle Mark , Matsuda Tetsuya , Koslin D. Bradley , Kenney Philip J. , Barton Robert E. , Pohost Gerald M. 
Published: March 2007

AbstractA magnetic resonance (MR) imaging strategy, SLIP (spatially separated lipid presaturation), which can be incorporated into existing MR imaging and MR angiographic techniques, has been developed to suppress lipid signal. The authors report the clinical application of this technique, with a triple comparison of two‐dimensional inflow MR angiography, with and without SLIP, and x‐ray angiography in patients with aortoiliac disease. SLIP improved visualization of arterial segments, with 50 of 63 (79%) arterial segments visualized versus 41 of 63 (65%) for non‐SLIP MR angiography. The SLIP strategy aids in the depiction of slow or turbulent flow, because the lipid signal is suppressed while the intravascular signal is left undisturbed. Image quality improves because of the combination of decreased background lipid signal intensity and use of the maximum‐intensity‐projection algorithm. Compared with x‐ray arteriography, non‐SLIP MR angiography had a sensitivity and specificity of 60% and 56%, respectively, for detection of lesions with 50%–100% diameter reduction, while SLIP MR angiography had a sensitivity and specificity, respectively, of 53% and 67%.
Two‐point interference method for suppression of ghost artifacts due to motion
Authors: Xiang Qing‐San , Bronskill Michael J. , Henkelman R. Mark 
Published: March 2007

AbstractA two‐point interference method is introduced for suppression of ghosting due to motion in magnetic resonance imaging. The method requires only two time‐interleaved data acquisitions, without any monitoring of the motion. A postprocessing technique is used to produce a weighted sum of the two acquired images, in which ghosts are suppressed by interference through an automatic regional tuning procedure. The appropriate complex weighting factors are regionally chosen by minimizing the “gradient energy”, which is defined as the sum of squared pixel values in the partial‐derivative maps. The method was tested in both phantoms and volunteers with a variety of imaging protocols. The level of ghost suppression with the two‐point method was found to be comparable to that of the three‐point method described previously by the authors.
Dynamic MR mammography: A technique for potentially reducing the biopsy rate for benign breast disease
Authors: Turkat Terry J. , Klein Barry D. , Polan Ruth L. , Richman Roselyn H. 
Published: March 2007

AbstractThirty‐five women with a total of 39 breast lesions detected at mammography and/or physical examination and who were scheduled for surgical biopsy were studied with dynamic magnetic resonance (MR) mammography. Fat‐suppressed, spoiled GRASS (gradient‐recalled acquisition in the steady state) sequences were performed before and after administration of gadopentetate dimeglumine. T1‐weighted spin‐echo and fat‐suppressed T2‐weighted fast spin‐echo images were also obtained. By measuring percentage signal intensity change in lesions on the spoiled GRASS images after contrast agent injection, the authors achieved a sensitivity of 100% and a specificity of 83.3% in differentiating benign from malignant lesions (24 benign, 15 malignant), with biopsy results as the standard. This dynamic MR mammography technique deserves further evaluation.
Frequency response of prospectively gated phase‐contrast MR velocity measurements
Authors: Frayne Richard , Rutt Brian K. 
Published: March 2007

AbstractThe authors developed and experimentally verified expressions that describe the frequency response of prospectively gated phase‐contrast magnetic resonance velocity measurements. Both interleaved and noninterleaved phase‐contrast techniques were evaluated. The primary determinants of the frequency response were (a) the number of interleaved acquisitions (N), (b) the time between acquisitions (ΔT), and (c) the degree of balance between the first moments of the velocity‐encoding gradients. To quantify the last factor, an imbalance parameter (U) was defined. Depending on the chosen implementation and U, deviations from the ideal frequency responses were predicted and observed. The expressions also revealed an advantage of interleaved acquisitions that use a one‐sided gradient configuration: no changes in the frequency response. The effects of concurrently encoding orthogonal velocity components with a Hadamard four‐point scheme were examined.
Errors in quantitative dynamic three‐dimensional keyhole MR imaging of the breast
Authors: Plewes Donald B. , Bishop Jonathan , Soutar Ian , Cohen Eve 
Published: March 2007

AbstractThree‐dimensional (3D) keyhole magnetic resonance (MR) imaging has been proposed as a means of providing dynamic monitoring of contrast agent uptake by breast lesions, with complete breast coverage and high spatial and temporal resolution. The 3D keyhole technique dynamically samples the central regions of k‐space in both phase‐encoding directions and provides high‐frequency data from a precon‐trast acquisition. Errors due to data truncation with two‐dimensional and 3D region‐of‐lnterest measurements are estimated from a numerical simulation of various implementations of the 3D keyhole technique. Errors were found to increase with increasing temporal resolution and reduced object size. Errors of 75% are possible for objects with a diameter approaching 1 pixel when a 3D keyhole implementation that samples 50% of phase‐encoding data in each direction is used. Preliminary clinical Images with this approach illustrate artifacts consistent with inadequate k‐space sampling.
Transient increased segmental hepatic enhancement distal to portal vein obstruction on dynamic gadolinium‐enhanced gradient echo MR images
Authors: Schlund James F. , Semelka Richard C. , Kettritz Ute , Eisenberg Lara B. , Lee Joseph K. T. 
Published: March 2007

AbstractThe purpose of the present study was to demonstrate the frequency of occurrence of transient increased segmental hepatic enhancement distal to portal veto obstruction in patients with a lobar (main branch) portal vein obstruction. MR images of all patients with main and lobar branch portal vein obstruction examined by dynamic gadolinium enhanced gradient echo MR images between December 1990 and July 1994 were reviewed retrospectively. All studies included T2‐weighted imaging, Tl‐weighted spoiled gradient echo‘fast low angle shot ([FLASH])’ and postgadolinium enhanced PLASH imaging at 1, 45, and 90 sec and 10 min. Fourteen patients were identified with portal vein obstruction which Included: six with main portal and right and left branch occlusion, six with right lobar, and two with left lobar. In the six patients with main portal vein obstruction, enhancement on 1‐sec postgadolinium FLASH images was homogenous (three patients), diffusely heterogeneous (two patients), or peripherally hyperintense (one patient). In eight of eight patients with isolated obstruction of the right or left lobar portal vein, transient‐increased segmental enhancement distal to portal vein occlusion was observed on immediate postcontrast images. Relatively high signal intensity of the involved segments was present on 1‐sec images and liver parenchymal enhancement became more homogeneous by 45 to 90 sec in all cases. In conclusion, transient‐increased segmental enhancement occurred in eight of eight patients with isolated right or left portal vein occlusion. We postulate that this effect occurs due to increased hepatic arterial blood flow in the presence of portal vein obstruction.
MR‐guided biopsy of the breast after lumpectomy and radiation therapy using two methods of immobilization in the lateral decubitus position
Authors: Desouza Nandita M. , Kormos Donald W. , Krausz T. , Coutts Glyn A. , Hall Alasdair S. , Burl Michael , Schwieso Jane E. , Puni Rakesh , Vernon Claire 
Published: March 2007

AbstractWe describe two methods of breast immobilization using the lateral decubitus position to increase patient comfort and access to the axillary tail for MR‐guided biopsy in the postsurgical or irradiated breast. The First method uses a compression device with good immobilization but poor patient tolerance. The second approach uses a thermoplastic mesh material to form a rigid exoskeleton around the breast: immobilization is adequate and patient acceptability is good. The latter method is prderred and requires formal evaluation in larger scale trials.
Dynamic Evaluation of Exercising Leg Muscle in Healthy Subjects with Echo Planar MR Imaging: Work Rate and Total Work Determine Rate of T2 Change
Authors: Disler David G. , Cohen Mark S. , Krebs David E. , Roy Serge H. , Rosenthal Daniel I. 
Published: March 2007

AbstractEcho planar MR imaging of the leg was performed in nine healthy volunteers to better understand the dynamic relationship between exercise and changes in muscle T2. Imaging and T2 calculation was performed before, during, and after ankle dorsiflexion exercises using a TR of 9 seconds and a TE of 60 msec. Performing 9‐second duty cycles, six of the subjects exercised for sets of 12 duty cycles, three with a graded series of weights and pulleys and three with an isometric orthotic device graded in varying percentages of maximum voluntary contraction. The other three volunteers performed duty cycles to fatigue. Gastrocnemius and soleus muscle T2 relaxation times were unchanged before, during, and after exercise. The tibialis anterior muscle showed an initial brief 1.7–6.2% decrease in T2 values after starting exercise, followed by a linear increase. Maximum T2 values and percent changes were higher for higher work rates (P <.05), and the rate of T2 change increased in a linear fashion with increasing work rates. By using rapid serial MR imaging, we show that the rate of muscle T2 change bears a simple linear relationship to muscle work. This technique may be exploited in both diagnostic and rehabilitation procedures.
1995 SMR young investigators' award finalist: MR measurement of time‐dependent blood pressure variations
Authors: Urchuk Stephen N. , Plewes Donald B. 
Published: March 2007

AbstractAn MR imaging method for measuring intravascular pressure variations is introduced. The technique is based on estimates of vascular compliance and vessel distension, which are obtained from a correlation of spatial and temporal velocity derivatives and measurements of the velocity gradient in the direction of flow, respectively. The accuracy of the technique was determined in vitro through a comparison of MR and transducer pressure measurements obtained in distensible vessel phantoms undergoing pulsatile flow. Results indicated that a root‐mean‐square error of 4–12% can be expected in phantoms covering a physiological range of compliance. In vivo feasibility was demonstrated by thoracic aorta pressure measurements, which produced pressure waveforms with an expected shape and magnitude.
Fast spin‐echo characteristics of visual stimulation‐induced signal changes in the human brain
Authors: Gao Jia‐Hong , Xiong Jinhu , Li Jinqi , Schiff Joseph , Roby John , Lancaster Jack L. , Fox Peter T. 
Published: March 2007

AbstractA fast spin‐echo (FSE) technique used in a conventional MR imaging scanner has been successfully developed for obtaining functional MR images with high spatial resolution and multiple slices. Our preliminary visual stimulation studies using the FSE technique show that the nuclear MR signal increases by 2.6% during activation in the primary visual cortex. These results provide evidence that the diffusion of tissue water molecules plays a key role in determining functional MR signal amplitude. Because the FSE functional MR imaging signal is extremely sensitive to microvascular (brain capillaries) hemodynamics, the FSE technique can be a powerful tool for studying the neuronal activity of the human brain.
Studies of the central nervous system‐derived CAD cell line, a suitable model for intraneuronal transport studies?
Authors: Li Yongling , Hou Linda Xiu‐E , Aktiv Annika , Dahlström Annica 
Published: March 2007

AbstractThe CAD cell line is a variant of a CNS‐derived Cath.a cell line established by targeted oncogenesis in transgenic mice. Cell differentiation of the cell line can be induced by “starvation,” i.e., removal of serum from the culture medium (protein‐free medium). The differentiated CAD cells extend long processes, which ultrastructurally contain abundant microtubules, intermediate filaments, and various synaptic vesicles/organelles in the varicose enlargements, thus resembling neurites. Histochemical studies demonstrated that the differentiated cells express a number of synaptic vesicle proteins, cytoskeletons, different neurotransmitter enzymes, neuropeptides, and glia proteins. The data suggest that the differentiated CAD cells may be a suitable model for studies of intraneuronal transport, recycling of receptors, and pharmacological investigations. © 2007 Wiley‐Liss, Inc.