bluuebunny/crossref_metadata_2025_split huggingface dataset:
Localized 2D J‐resolved H MR spectroscopy of human brain tumors in vivo
Authors: Thomas M. Albert , Ryner Lawrence N. , Mehta Minesh P. , Turski Patrick A. , Sorenson James A. 
Published: March 2007

AbstractApplication of two‐dimensional (2D) J‐resolved MR spectroscopy, fully localized in three dimensions to monitor the metabolites in human brain tumors in vivo on a whole body MR scanner is presented. A modified PRESS sequence with [90° – 180° – t1/2 – 180° – t1/2‐acquisition] was used for voxel localization (2D J point‐resolved spectroscopy [PRESS]); chemical shift selective (CHESS) sequence was used for suppression of water. The incremental delay (t1/2) added to the intervals before and after the last slice‐selective 180° RF pulse allowed the monitoring of the J‐evolution in a localized 2D NMR spectrum. The addition of the second frequency dimension in 2D J‐resolved spectroscopy to encode the indirect spin‐spin coupling allowed the visualization of lactate peaks not observed in the 1D MR spectrum because of severe overlap with lipid peaks. 2D spectra of a two‐layer phantom with 100 mM alanine and corn oil and also from three patients with tumors are presented here. The 2D spectra show that the J‐coupled lactate peaks could be separated even when the lipids peaks severely overlap.
MR perfusion imaging of the kidney pre‐ and post‐dipyridamole stress
Authors: Tello Richard , Hartnell George G. , Hill Thomas , Volpe Joanne , Finn J. Paul , Cohen Mylan 
Published: March 2007

AbstractAnimal studies have demonstrated that renal MR contrast enhancement depends on the timing of image acquisition. Limited human studies have demonstrated effects of dipyidamole (DP) on total renal perfusion. This study assessed the effect of DP on total and regional renal perfusion using gated perfusion MRI for patients undergoing DP stress. Five subjects with no evidence of renal ischemia were examined at rest and after DP stress. Rest MRI images in the left kidney were acquired using electrocardiogram (ECG)‐gated MR: turbo fast low‐angle shot (FLASH); echo time (TE) = 12, repetition time (TR) = 6. flip angle = 12, inversion time (TI) = (100) 10 to 45 seconds after injection of gadopentetate dimeglumine. Stress was induced in the MRI scanner (DP, .56 mg/kg over 4 minutes) followed by stress MRI after a second bolus of gadopentetate dimeglumine in the same position and identical time intervals. MR signal in the whole left kidney and renal medulla and cortex pre‐ and post‐DP demonstrated a 70% depression of total renal perfusion with relative preservation of cortical perfusion at the expense of medullary perfusion. Post‐DP MR images demonstrated a decrease in cortical perfusion with an additional 29% depression of medullary perfusion (P < .001) with respect to cortical perfusion. Turbo FLASH MRI can provide adequate time and spatial resolution to demonstrate changes in renal perfusion. Depression of renal medullary perfusion after DP appears to be caused by the intrarenal effect of DP and may have clinical impact.
Contrast enhancement with GD‐EOB‐DTPA in MR imaging of hepatocellular carcinoma in mice: A comparison with superparamagnetic iron oxide
Authors: Fujita Makoto , Yamamoto Reiko , Fritz‐Zieroth Bernhard , Yamanaka Tsuyoshi , Takahashi Masaya , Miyazawa Tomoaki , Tatsuta Masaharu , Terada Nobuyuki , Hosomi Naohiro , Inoue Etsuo , Kuroda Chikazumi 
Published: March 2007

AbstractThe purpose of this study was to evaluate the ability of the new liver‐specific magnetic resonance contrast agent gadolinium‐ethoxybenzyl‐diethylenetriamine penta‐acetic acid (Gd‐EOB‐DTPA) to detect hepatocellular carcinoma (HCC). Seventeen mice with 66 chemically induced HCCs underwent magnetic resonance imaging with both Gd‐EOB‐DTPA (30 μmol/kg) and superparamagnetic iron oxide (SPIO; 10 μmol/kg). After enhancement, lesion‐to‐liver contrast‐to‐noise ratios (CNRs) of 47 detected HCCs increased negatively from 3.7 ± 10.7 (mean ± SD) to –55.1 ± 25.8 with Gd‐EOB‐DTPA (P < .001) and increased positively from 10.4 ± 10.4 to 26.1 ± 16.3 with SPIO (P < .001). The improvement of CNR after administration of SPIO was less in smaller lesions (< 4 mm), whereas that after administration of Gd‐EOB‐DTPA was independent of lesion size. However, Gd‐EOB‐DTPA positively enhanced four HCCs (8.5%), both highly differentiated (grade 1) and moderately differentiated (grade 2). Gd‐EOB‐DTPA allows the conspicuous detection of small HCCs; however, moderately differentiated HCCs occasionally may be positively enhanced.
Magnetic resonance imaging evaluation of the ascending aorta after graft‐inclusion surgery: Comparison between an ultrafast contrast‐enhanced MR sequence and conventional cine‐MRI
Authors: Loubeyre Pierre , Delignette Alexandra , Bonefoy Laurence , Douek Philippe , Amiel Michel , Revel Didier 
Published: March 2007

AbstractThe aim of this study was to compare the value of two magnitude‐based MR sequences, a contrast‐enhanced ultrafast MR sequence and a cine MR sequence, for the detection of flow around the graft in the postoperative ascending thoracic aorta. Thirteen patients who underwent ascending aortic surgery for dissection (n = 11) and aneurysm (n = 2) were enrolled. They were referred to MRI for mediastinum enlargement on the chest x‐ray or mediastinal symptoms. All patients had replacement of the diseased ascending aorta using a graft‐inclusion technique (with wrapping of the native aorta over the graft). Delays between surgery and MRI ranged from 15 days to 8 years (mean: 10 months). All patients were examined using a T1‐weighted spin‐echo sequence, a magnitude‐based cine gradient‐echo sequence, and an ultrafast contrast‐enhanced MR sequence. MR images of the cine and the contrast‐enhanced sequences were retrospectively and independently analyzed by two qualified radiologists for evidence of flow or thrombus around the graft, including perigraft structure and aneurysmal formations. Evidence of flow was detected by both methods in all aneurysmal formations of the ascending aorta located at suture level (n = 6). Evidence of flow in the perigraft structure was found in seven cases by contrast‐enhanced MR sequence and in only four cases by cine MR sequence. Contrast‐enhanced ultrafast MR sequence could be proposed as a minimally invasive and fast modality for assessing the perigraft structure, in graft‐in‐clusion surgical procedures of the ascending aorta, when noncontrast enhanced MR sequences do not exclude the possibility of flowing blood in this structure.
Papillary projections in ovarian neoplasms: Appearance on MRI
Authors: Outwater Eric K. , Huang Abbott B. , Dunton Charles J. , Talerman Alexander , Capuzzi David M. 
Published: March 2007

AbstractPapillary projections are distinctive pathologic features of epithelial ovarian neoplasms. We sought to determine whether these structures have recognizable features on MRI. A search of a database of 125 patients on whom MRI was performed with pelvic phased‐array coil and abdominal surgical exploration was performed for suspected gynecologic disease identified 15 patients who had either MRI reports or pathology reports mentioning papillary projections in an adnexal mass. The MR images were reviewed to characterize the size, structure, and signal intensity of papillary projections. Pathologic correlation was performed on these and on four surgical specimens imaged with high resolution technique. Pathologic correlation showed that larger papillary projections had a distinctive structure of a fibrous stalk supporting clumps of edematous papillae with signal intensity similar to that of fluid on T2‐weighted images. Smaller papillae showed nondescript intracystic projections of intermediate signal intensity on T2‐weighted images. All papillary projections in vivo enhanced after injection of gadopentetate dimeglumine. Papillary projections have an appearance on MRI that reflects their histologic structure.
Pharmacokinetic Analysis of Gd‐DTPA Enhancement in dynamic three‐dimensional MRI of breast lesions
Authors: Den Boer Jacques A. , Hoenderop Ruud K. K. M. , Smink Jouke , Dornseiffen Gerard , Koch Paul W. A. A. , Mulder Jan H. , Slump Cornelis H. , Volker Edo D. P. , De Vos Rob A. I. 
Published: March 2007

AbstractThe purpose of this study was to demonstrate that dynamic MRI covering both breasts can provide sensitivity for tumor detection as well as specificity and sensitivity for differentiation of tumor malignancy. Three‐dimensional gradient echo scans were used covering both breasts. Before Gd‐DTPA bolus injection, two scans were obtained with different flip angles, and after injection, a dynamic series followed. Thirty‐two patients were scanned according to this protocol. From these scans, in addition to enhancement, the value of T1 before injection was obtained. This was used to estimate the concentration of Gd‐DTPA as well as the pharmacokinetic parameters governing its time course. Signal enhancement in three‐dimensional dynamic scanning was shown to be a sensitive basis for detection of tumors. In our series, all but two mam‐mographically suspicious lesions did enhance, and in three cases, additional enhancing lesions were found, two of which were in the contralateral breast. The parameter most suited for classification of breast lesions into benign or malignant was shown to be the pharmacokinetically defined permeability k31, which, for that test, gave a sensitivity of 92% and a specificity of 70%. Our three‐dimensional dynamic MRI data are sensitive for detection of mammographically occult breast tumors and specific for classification of these as benign or malignant.
Limitations of the keyhole technique for quantitative dynamic contrast‐enhanced breast MRI
Authors: Bishop Jonathan E. , Santyr Giles E. , Kelcz Frederick , Plewes Donald B. 
Published: March 2007

AbstractThe effect of keyhole data acquisition on quantitative analysis of dynamic MRI was examined. Experiments were performed retrospectively on raw data obtained from clinical dynamic contrast‐enhanced breast imaging procedures. The effects of keyhole phase‐encoding acquisition and type of reconstruction algorithm on the accuracy of derived quantitative parameters was assessed. Results indicate that the minimum keyhole size used should be restricted by the approximate minimum size of the expected lesions. Furthermore, reconstruction algorithms that offer improved image resolution do not circumvent this restriction.
Improved solvent suppression and increased spatial excitation bandwidths for three‐dimensional press CSI using phase‐compensating spectral/spatial spin‐echo pulses
Authors: Star‐Lack Josh , Vigneron Daniel B. , Pauly John , Kurhanewicz John , Nelson Sarah J. 
Published: March 2007

AbstractDual phase‐compensating spectral/spatial echo‐planar (EP) spin‐echo (SE) pulses were incorporated into the point resolved spectroscopy (PRESS) excitation sequence to improve water and lipid suppression for 1H chemical shift imaging (CSI) and to decrease the dependence of the PRESS box location upon chemical shift. The asymmetric EPSE pulses (either minimum or maximum phase in the chemical shift domain) were substituted for the two PRESS SE pulses to yield zero phase spectra. Three different pulses were designed and tested at 1.5 T. Pulse 1, targeted for brain CSI (TE > 85 msec), passed choline to lipid resonances, suppressed water, and rephased the methyl lactate doublet independently of TE. Pulse 2, targeted for general purpose shorter TE PRESS, possessed both high chemical shift and spatial domain bandwidths. Pulse 3, designed for prostate CSI, passed choline to citrate resonances while suppressing lipids and water. The three pulses possessed spatial bandwidths ranging between 3.3 and 5.0 kHz, more than three times higher than that offered by one‐dimensional SE pulses of equivalent maximum B1 amplitude. Phantom and in vivo experimental results demonstrated that, for EPSE pulses 1 and 2, suppression factors higher than 104 were achieved. The increased spatial bandwidths resulted in less contamination by signals from outside the designated PRESS excited region and a significant improvement in the uniformity of metabolite intensities for voxels located near edges of the PRESS box.
Massive edema of the ovary: High resolution MR findings using a phased‐array pelvic coil
Authors: Kramer Larry A. , Lalani Tasneem , Kawashima Akira 
Published: March 2007

AbstractWe report a rare premenarchal case of massive ovarian edema in which high resolution MRI findings more accurately reflected characteristic pathologic changes of this condition compared with CT and ultrasound. A potential role of MR in preoperative diagnosis of massive ovarian edema is suggested.
Xenon effects on regional cerebral blood flow assessed by 15O‐H2O positron emission tomography: Implications for hyperpolarized xenon MRI
Authors: Liotti Mario , Martin Charles C. , Gao Jia‐Hong , Roby John W. , Mayberg Helen S. , Zamarripa Frank , Jerabek Paul A. , Fox Peter T. 
Published: March 2007

AbstractSubjective and physiologic effects of 33% inhaled Xe were measured with 15O‐water positron emission tomography (PET) in 3 subjects at rest and during visual stimulation. The procedure was well tolerated. Robust functional activations of the visual cortex were obtained after xenon (Xe) inhalation as well as air breathing. However, Xe inhalation was followed by smaller size, but significant decreases of regional cerebral blood flow (rCBF) in visual cortex relative to the air‐breathing baseline, both during visual stimulation and at rest. No such decreases were found in other sensory or motor regions.
Use of an intravascular T1 contrast agent to improve MR cine myocardial‐blood pool definition in man
Authors: Stillman Arthur E. , Wilke Norbert , Jerosch‐Herold Michael 
Published: March 2007

AbstractThe feasibility of improving myocardial/blood pool contrast in MR cine images through use of an intravascular contrast agent (Ferumoxtran, Advanced Magnetics, Inc., Cambridge, MA) was tested in four subjects. The contrast‐to‐noise ratio (CNR) demonstrated a trend toward improvement in the short axis and improved significantly in the long axis cine by an average of 128% (P < .05). Image intensity gradients at the myocardial/blood pool interface increased significantly in both the short and long axis (P < .01). It is expected that larger image intensity gradients at the endocardial border should improve the capabilities of automated segmentation algorithms, reducing the uncertainty and need for manual editing.
Imaging of nodal metastases in the head and neck
Authors: Anzai Yoshimi , Brunberg James A. , Lufkin Robert B. 
Published: March 2007

AbstractTherapeutic outcome of head and neck cancer is influenced strongly by the presence of nodal metastases. Sensitivity and specificity of the physical examination for the diagnosis of nodal metastasis is unsatisfactory, resulting in both false negatives and false positives of 25 to 40%. Preoperative detection of nodal metastases therefore becomes one of the important goals of imaging studies of patients with head and neck cancer. Despite several advanced techniques and the wide clinical use of MR, MR has surprisingly added little to the diagnostic accuracy of contrast‐enhanced CT. Although CT and MR allow detection of abnormally enlarged nodes or necrotic nodes, neither borderline‐sized nodes without necrosis nor extracapsular spread are reliably differentiated from reactive or normal nodes in patients with head and neck cancer. Lack of definitive diagnostic methods of metastatic lymph nodes is a serious shortcoming in the preoperative workup for patients with head and neck cancer. To avoid missing small metastatic nodes, a large number of patients clinically staged as NO have undergone elective neck dissection to exclude metastases. With development of more tissue‐specific imaging techniques, patients can be better characterized according to the status of nodal disease so that an appropriate therapeutic protocol can be designed for an individual case.
Blood flow patterns in the thoracic aorta studied with three‐directional MR velocity mapping: The effects of age and coronary artery disease
Authors: Bogren Hugo G. , Mohiaddin Raad H. , Kilner Philip J. , Jimenez‐Borreguero Luis J. , Yang Guang Z. , Firmin David N. 
Published: March 2007

AbstractThe objective was to investigate how the blood flows in the thoracic aorta, with special emphasis on flow reversal and flow into the coronary arteries. Three‐directional MR velocity mapping was used to map multidirectional flow velocities in the aorta in 14 normal subjects and 14 patients with coronary artery disease. Dynamic flow vector maps and through‐plane velocity maps were used. The flow reversed in all subjects in the upper ascending aorta and usually also in the distal aortic arch. Retrograde flow became antegrade again at various levels in the ascending aorta and in the coronary sinuses. Seven flow characteristics were investigated that, lumped together, were significantly different (P = .0005) in normal subjects compared with patients and in normal subjects 70 years of age and older compared with those younger than 70 years of age.
Comparison of inversion recovery asymmetrical spin‐echo EPI and gradient‐echo EPI for brain motor activation study
Authors: Zheng Jie , Ehrhardt James C. , Cizadlo Ted , Yuh William T. C. 
Published: March 2007

AbstractAn inversion recovery asymmetric spin‐echo (IR‐ASE) echo‐planar imaging (EPI) sequence has been developed for functional studies of the brain. This technique uses an 180° inversion pulse with a long inversion time (TI) to suppress the pulsatile cerebrospinal fluid and an asymmetric spin‐echo readout to obtain activation signals from brain capillaries. Because gradient‐echo sequences are most sensitive to large vessels, motor cortex activation studies using a gradient‐echo technique also were conducted for comparison with the IR‐ASE method. The results suggest that the IR‐ASE pulse sequence may be a useful complement to the gradient‐echo technique for the study of neuronal activity of the human brain.
The pharmacokinetics of hyperpolarized xenon: Implications for cerebral MRI
Authors: Martin Charles C. , Williams Robert F. , Gao Jia‐Hong , Nickerson Lisa D. H. , Xiong Jinhu , Fox Peter T. 
Published: March 2007

AbstractIn this work, a compartmental model to predict the concentration of hyperpolarized xenon (Xe) in the brain is developed based on the well established kinetics of Xe and estimated T1 values for the compartments. For the gaseous compartments, T1 was set to 12 seconds. For the tissue compartments, T1 was set to 6 seconds. Three gas delivery techniques were modeled: hyperventilation followed by breath‐hold, continual breathing, and hyperventilation followed by continual breathing. Based on Xe CT, it is estimated that the maximum concentration of Xe that could be breathed is 80%. Based on this value and the estimated maximum polarization of 50%, the peak gray matter concentration of hyperpolarized Xe is calculated to be .036 mM. This leads to an estimated signal‐to‐noise ratio (SNR), at 2 T, for hyperpolarized Xe that is a factor of 50 lower than the SNR for proton MRI. The peak concentration of hyperpolarized Xe was also calculated over a wide range of gas and tissue T1 values. This model also predicts that the arterial blood will have a concentration of hyperpolarized Xe that is 10 times greater than the concentration in gray matter. An interactive version of the model can be found on the World Wide Web at http://ric.uthscsa.edu/staff/charlesmartinphd.html.
T1ρ dispersion imaging of head and neck tumors: A comparison to spin lock and magnetization transfer techniques
Authors: Markkola Antti T. , Aronen Hannu J. , Paavonen Timo , Hopsu Erkki , Sipilä Leena M. , Tanttu Jukka I. , Sepponen Raimo E. 
Published: March 2007

AbstractThe potential of T1ρ dispersion, spin lock (SL), and magnetization transfer (MT) techniques to differentiate benign and malignant head and neck tumors was evaluated. Twenty‐four patients with pathologically verified head and neck tumors were studied with a .1‐T MR imager. T1ρ dispersion effect was defined as 1 — (intensity with lower locking field amplitude/intensity with higher locking field amplitude). T1ρ dispersion effects were higher for malignant than benign tumors (P = .001). With T1ρ dispersion effect .14 as the threshold, sensitivity for detecting a malignant tumor was 91%, specificity was 77%, and accuracy was 83%. A strong correlation between T1ρ dispersion effects and SL effects and between T1ρ dispersion effects and MT effects in the head and neck tumors was found (r = .87, P < .001 and r = .90, P < .001, respectively). High T1ρ dispersion effects are not specific indicators of malignancy, because chronic infections, some benign tumors, and malignancies may overlap. Low T1ρ dispersion effect values are characteristic of a benign tumor.
MRI analysis of lumbar intervertebral disc height in young and older populations
Authors: Roberts Neil , Gratin Christophe , Whitehouse Graham H. 
Published: March 2007

AbstractMeasurements of length and section area on MR images are made conventionally by the manipulation of a tracker ball to move a cursor to define end points or delineate boundaries. This operator‐dependent method lacks the objectivity that computer‐based image analysis techniques, such as edge‐detection algorithms, can give. We describe an image analysis routine, based on earlier work by Vincent and Soille using algorithms of mathematical morphology, for automatically extracting the boundary of lumbar intervertebral discs on MR images. This is applied to the automatic measurement of the maximum disc space height and section area of non‐degenerate intervertebral discs on MR images obtained for healthy male subjects of two distinct age ranges, ie, twenty 20‐ to 30‐year‐olds and twenty 50‐ to 60‐year‐olds. Throughout the levels L1 to L4, intervertebral disc height is found to be significantly greater (P = .0003 to .0161) in the older than in the younger age group. The data support a model of the spine in which the disc adopts a more concave form as a result of microfracturing of the end plates during adult life.
Gradient‐echo perfusion imaging of musculoskeletal abnormalities with contrast‐enhanced two‐dimensional fat‐saturation FLASH
Authors: Konez Orhan , Bis Kostaki G. , Shirkhoda Ali , Shetty Anil N. , Gürgün Mehmet , Wilcox Richard , Irwin Ronald 
Published: March 2007

AbstractThe objective of this study was to evaluate the utility of MR perfusion imaging of various musculoskeletal lesions with a contrast‐enhanced two‐dimensional fat saturation fast low angle shot (FLASH) sequence and to assess the potential of this technique for distinguishing malignant from benign conditions. Thirty‐six musculoskeletal lesions were studied at 1.5 T. The signal intensity of the lesions, adjacent artery, muscle, bone marrow, and fat were plotted against time. The time to peak enhancement, time to maximum signal intensity, percent enhancement, rate of peak enhancement, and rate of enhancement parameters were calculated. Because of a significant overlap between malignant and benign conditions, accuracy rates were lower than reported previously. The best parameter based on these values was the rate of peak enhancement (sensitivity, 84.6%; specificity, 65.2–66.6%; positive predictive value, 57.8–68.7%). Fat saturation gradient‐echo MR perfusion imaging allows for a rapid assessment of the vascularity of musculoskeletal pathology; however, a significant overlap persists between malignant neoplasms and several benign conditions.
Prototype system for an MR simulation of intracavitary brachytherapy for cervical cancer: Preliminary results in six cases
Authors: Ebe Kazuyu , Matsunaga Naofumi 
Published: March 2007

AbstractWe report a newly developed MR simulation system for intracavitary brachytherapy for cervical cancer and subsequent treatment results. MR simulation was performed on six patients. The spatial relationship of the tumor to the bladder, rectum, bowel, applicators, etc. was depicted well. Doses to the tumor and surrounding normal tissues were read from isodose curves superimposed on the T2‐weighted sagittal image. This system promises to be useful in customizing the dose distribution.