bluuebunny/crossref_metadata_2025_split huggingface dataset:
Orthogonal measurement of thoracic aorta luminal diameter using ECG‐gated high‐resolution contrast‐enhanced MR angiography
Authors: Bireley William R. , Diniz Lincoln O. , Groves Elliott M. , Dill Karin , Carroll Timothy J. , Carr James C. 
Published: October 2007

AbstractPurposeTo compare orthogonal measurements of the thoracic aortic luminal diameter to standard axial measurements within the same patient population using ECG‐gated high‐resolution contrast‐enhanced MR angiography (CE‐MRA).Materials and MethodsIn all, 45 consecutive patients who had undergone CE‐MRA for suspected disease of the thoracic aorta were evaluated retrospectively. Two diameter measurement techniques were performed for each patient's thoracic aorta: standard axial and orthogonal to the aorta. Seven anatomic locations along the thoracic aorta were used for measurement. The data obtained were compared using a paired, two‐tailed t‐test.ResultsWe found that the aorta diameter measurements acquired from axial MRA images were significantly greater (P < 0.05) than those acquired from images orthogonal to the course of the aorta at six of seven anatomic sites. Overall, standard axial measurements were found to overestimate luminal diameter of the thoracic aorta by 0.24 cm (95% confidence interval [CI]: 0.14, 0.33) compared to orthogonal measurements. 13.3% of the patients were placed into a greater aorta size classification based on the axial versus the orthogonal measurements.ConclusionStandard axial measurements can overestimate vessel size of the thoracic aorta. ECG‐gated high‐resolution CE‐MRA can be used to measure orthogonal diameters of the thoracic aorta. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Mechanical dyssynchrony or myocardial shortening as MRI predictor of response to biventricular pacing?
Authors: Rüssel Iris K. , Zwanenburg Jaco J.M. , Germans Tjeerd , Marcus J. Tim , Allaart Cornelis P. , de Cock Carel C. , Götte Marco J.W. , van Rossum Albert C. 
Published: October 2007

AbstractPurposeTo investigate whether mechanical dyssynchrony (regional timing differences) or heterogeneity (regional strain differences) in myocardial function should be used to predict the response to cardiac resynchronization therapy (CRT).Materials and MethodsBaseline mechanical function was studied with MRI in 29 patients with chronic heart failure. Using myocardial tagging, two mechanical dyssynchrony parameters were defined: the standard deviation (SD) in onset time (Tonset) and in time to first peak (Tpeak,first) of circumferential shortening. Electrical dyssynchrony was described by QRS width. Further, two heterogeneity parameters were defined: the coefficient of variation (CV) in end‐systolic strain and the difference between peak septal and lateral strain (DiffSLpeakCS). The relative increase in maximum rate of left ventricle pressure rise (dP/dtmax) quantified the acute response to CRT.ResultsThe heterogeneity parameters correlated better with acute response (CV: r = 0.58, DiffSLpeakCS: r = 0.63, P < 0.005) than the mechanical dyssynchrony parameters (SD(Tonset): r = 0.36, SD(Tpeak,first) r = 0.47, P = 0.01, but similar to electrical dyssynchrony (r = 0.62, P < 0.001). When a heterogeneity parameter was combined with electrical dyssynchrony, the correlation increased (r > 0.70, Pincr < 0.05).ConclusionRegional heterogeneity in myocardial shortening correlates better with response to CRT than mechanical dyssynchrony, but should be combined with electrical dyssynchrony to improve prediction of response beyond the prediction from electrical dyssynchrony only. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
In vivo proton magnetic resonance spectroscopy in patients with mood disorders: A technically oriented review
Authors: Capizzano Aristides A. , Jorge Ricardo E. , Acion Laura C. , Robinson Robert G. 
Published: October 2007

AbstractProton MR spectroscopy (1HMRS) has been extensively used among mood disorders patients. A review of the published literature in 1HMRS studies of mood disorders was carried out for the period 1991 to July 2006. Of 71 1HMRS studies, 77.5% were done at 1.5T and 66.2% used single voxel sequences (SVS), implying limitations of spectral resolution and anatomic coverage, respectively. In all, 47.9% of studies relied on creatine (Cr) as internal signal standard, although Cr changes were reported in major depression (MD). Most reported metabolic alterations related to mood state affected the left frontal lobe. Depressed adult and pediatric MD patients had reduced glutamate (Glu) in frontal lobe regions, which reversed with successful treatment. A consistent reduction of N‐acetyl‐aspartate (NAA) was reported in the hippocampal formation among bipolar disorder (BD) patients, along with an increment in frontal Glu. The differences in results of 1HMRS studies in mood disorders reflect heterogeneity of technical factors and subject selection. Future studies should benefit from higher spectral resolution and more extensive anatomic coverage as well as standardized data‐processing protocols and subject selection criteria. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Exposure of workers to pulsed gradients in MRI
Authors: Crozier Stuart , Wang Hua , Trakic Adnan , Liu Feng 
Published: October 2007

AbstractPurposeTo numerically evaluate the electric field/current density magnitudes and spatial distributions in healthcare workers when they are standing close to the gradient coil windings near the magnetic resonance imaging (MRI) scanner ends.Materials and MethodsAnatomically realistic, whole‐body male and female voxel phantoms are engaged to model the workers at various positions near the ends of three cylindrical gradient coils (x‐, y‐, and z‐axis gradients). The numerical calculations of induced fields are based on an efficient, quasistatic finite‐difference method.ResultsThe simulations show that it is possible to induce electric fields/current densities above levels recommended by the International Commission for Non‐ionizing Radiation Protection (ICNIRP) and the Institute of Electrical and Electronics Engineers (IEEE) standards when the workers are standing close to the gradient coils and when two or three gradients are switched simultaneously, as is often the case.ConclusionThe longitudinal gradient tends to induce more fields in workers than the transverse coils. The strongest levels of field exposure are observed when all three gradients are operated simultaneously and can be above regulations when the healthcare worker is close to the gradient coils. Other postures such as bending into the magnet shall be investigated in further studies. J. Magn. Reson. Imaging 2007;26:1236–1254. © 2007 Wiley‐Liss, Inc.
Chronic postinfarction pseudo‐pseudoaneurysm diagnosed by cardiac MRI
Authors: Faludi Réka , Tóth Levente , Komócsi András , Varga‐Szemes Ákos , Papp Lajos , Simor Tamás 
Published: October 2007

AbstractLeft ventricular pseudo‐pseudoaneurysm is an extremely rare complication of myocardial infarction. In this condition the postinfarction rupture of the myocardium is not transmural, but remains circumscribed within the ventricular muscle itself as a cavity joining to the left ventricle through a narrow neck. The differentiation between postinfarction pseudoaneurysms and pseudo‐pseudoaneurysms may be very difficult using conventional imaging techniques, such as transthoracic, or transesophageal echocardiography and left ventricular angiography. Cardiac MRI (CMR), however, is capable of distinguishing among anatomical structures such as pericardium, thrombus, and myocardium. In our report a chronic postinfarction pseudo‐pseudoaneurysm is described by CMR in a patient with an old myocardial infarction. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Detecting groups of coherent voxels in functional MRI data using spectral analysis and replicator dynamics
Authors: Müller Karsten , Neumann Jane , Grigutsch Maren , von Cramon D. Yves , Lohmann Gabriele 
Published: October 2007

AbstractPurposeTo investigate the relationship between functional MRI (fMRI) time series in the human brain, combining fMRI spectral analysis and replicator dynamics.Materials and MethodsSimulated and real fMRI time courses were investigated using the bivariate spectral coherence. Coherence values were placed in coherence matrices encoding the relationship between the time courses. Groups of maximally coherent voxels were detected using replicator dynamics. Results were compared to a former approach called number of coherent voxels (NCV).ResultsNCV critically depends on a threshold that has to be chosen in advance. The lower this threshold, the larger the detected group. Using higher NCV thresholds in our simulations, the method did not detect all voxels that were constructed to have a high coherence among each other. In contrast, the replicator process found the whole group in all simulations.ConclusionThe application of replicator dynamics to spectral matrices is a reliable method for detecting groups of maximally coherent voxels. A replicator process is able to determine groups of voxels with the property that each voxel in the group exhibits a high coherence with every other group member. In contrast to the NCV approach, this method is parameter‐free and does not require the a priori selection of a reference voxel. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
MR imaging of the female pelvis at 3 Tesla: Evaluation of image homogeneity using different dielectric pads
Authors: Kataoka Masako , Isoda Hiroyoshi , Maetani Yoji , Nakamoto Yuji , Koyama Takashi , Umeoka Shigeaki , Tamai Ken , Kido Aki , Morisawa Nobuko , Saga Tsuneo , Togashi Kaori 
Published: October 2007

AbstractPurposeTo evaluate improvements in image homogeneity in pelvic MR imaging at 3 Tesla (T) using two different dielectric pads.Materials and MethodsA total of eight healthy females were scanned using a 3T MR scanner equipped with a body‐array coil. Axial and sagittal fast spin‐echo T2‐weighted images (T2WI) (TR/TE = 3200 msec/94 msec), axial fast spin‐echo T1‐weighted images (T1WI) (TR/TE = 700 msec/11 msec), and sagittal half‐Fourier acquisition single‐shot turbo spin‐echo (HASTE) images (TR/TE = 3000 msec/100 msec) were performed for pelvic imaging. Sequences were repeated with dielectric pads (consisting of either ultrasound [US] gel or water), and without pads. Three or four regions of interest (ROIs) were placed on fatty tissues and the ratio of minimum to maximum signal intensity (RSI) was calculated as a marker of image homogeneity.ResultsRSI was significantly higher on T2WI and T1WI when using dielectric pads than when no pad was used. A similar tendency was observed in RSI on HASTE. No significant difference was found between images with US gel pads and those with water pads.ConclusionDielectric pads consisting of either US gel or water are effective in improving image homogeneity of the pelvis on 3T MRI. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Laser Doppler velocimetry (LDV) and 3D phase‐contrast magnetic resonance angiography (PC‐MRA) velocity measurements: Validation in an anatomically accurate cerebral artery aneurysm model with steady flow
Authors: Hollnagel Dorothea I. , Summers Paul E. , Kollias Spyros S. , Poulikakos Dimos 
Published: October 2007

AbstractPurposeTo verify the accuracy of velocity mapping with three‐dimensional (3D) phase‐contrast magnetic resonance angiography (PC‐MRA) for steady flow in a realistic model of a cerebral artery aneurysm at a 3T scanner.Materials and MethodsSteady flow through an original geometry model of a cerebral aneurysm was mapped at characteristic positions by state‐of‐the‐art laser Doppler velocimetry (LDV) as well as 3D PC‐MRA at 3T. The spatial distributions and local values of two velocity components obtained with these two measurement methods were compared.ResultsThe 3D PC‐MRA velocity field distribution and mean velocity values exhibited only minor differences to compare to the LDV measurements in straight artery regions for both main and secondary velocities. The differences increased in regions with disturbed flow and in cases where the measurement plane was not perpendicular to the main flow direction.Conclusion3D PC‐MRA can provide reliable measurements of velocity components of steady flow in small arteries. The accuracy of such measurements depends on the artery size and the measurement plane positioning. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Opposed phase imaging in lumbar disc disease: An option providing faster image acquisition times
Authors: Yagmurlu Banu , Erden Ilhan , Tanju Sumru , Genc Yasemin 
Published: October 2007

AbstractPurposeTo investigate the utility of opposed phase imaging (OPI) (in‐phase and out‐of‐phase) in lumbar disc disease.Materials and MethodsA total of 127 patients suspected of disc disease were examined with both traditional lumbar spine protocol (fast spin‐echo [FSE] T1‐weighted, T2‐weighted sagittal, and T2‐weighted axial) and OPI. Images were evaluated to detect the disc disease and to assess the anatomical clarity of certain spinal structures by two different radiologists using a four‐point scale (1 = inadequate, 2 = adequate, 3 = good, and 4 = optimal). Results of two methods in terms of pathologic conditions and anatomical structures were compared. Comparison of the methods and the interpretations of two radiologists were performed by using kappa statistics. The difference among two methods in terms of anatomic clarity was assessed by using Wilcoxon analysis.ResultsDisc disease detected by each technique demonstrated concurrence (agreement was 82.4% and 93.1% for two radiologists; P < 0.05). OPI received similar scores with conventional sequences for disc disease (P > 0.05). OPI was optimal in displaying disc, marrow, osteophytes, and hemangiomas, where other structures got higher scores on conventional images (P > 0.05 and P > 0.001). But these structures had equal scores at least in one of the opposed‐phase images. Acquisition time for OPI and conventional images were 4.46 and 9.01 minutes, respectively.ConclusionOPI can be a faster backup technique in evaluating the lumbar disc disease. It has a shorter image acquisition time with adequate diagnostic quality. It can be a “time saver” option for busy MR centers or may be used for patients who cannot tolerate longer acquisition times. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Planimetric and continuity equation assessment of aortic valve area: Head to head comparison between cardiac magnetic resonance and echocardiography
Authors: Pouleur Anne‐Catherine , le Polain de Waroux Jean‐Benoît , Pasquet Agnès , Vancraeynest David , Vanoverschelde Jean‐Louis J. , Gerber Bernhard L. 
Published: October 2007

AbstractPurposeTo compare the accuracy of planimetric and continuity equation measurements of aortic valve area (AVA) by cardiac MR (cMR) to each other and against transthoracic (TTE) and transesophageal (TEE) echocardiography.Materials and MethodsA total of 31 patients (21 men, mean age = 67 ± 13 years) with aortic stenosis (AS) and 16 controls (12 men, mean age = 57 ± 14 years) underwent measurement of AVA by planimetric and continuity equation cMR. Measurements were compared to TEE planimetry and continuity equation TTE.ResultsAVA by continuity equation cMR correlated highly to continuity equation TTE (r = 0.98) and was not significantly different (1.8 ± 1.3 cm2 vs. 1.8 ± 1.4 cm2, P = 0.62). Similarly, AVA by cMR planimetry was not statistically different from TEE planimetry (2.1 ± 1.7 cm2 vs. 2.1 ± 1.6 cm2, P = 0.34) and correlated highly (r = 0.98). Yet planimetric measurements of AVA by cMR and TEE were significantly higher than AVA by continuity equation cMR (P < 0.001 and P < 0.001, respectively) and TTE (P < 0.001 and P < 0.001, respectively).ConclusionBoth planimetry and continuity equation–based measurements of AVA by cMR are equally accurate. However, similar to TEE, cMR AVA is larger by planimetry than by continuity equation. This is consistent with the contention that the anatomical maximum opening of a stenotic aortic valve is larger than the size of the functional vena contracta. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Correlation of lung parenchymal MR signal intensity with pulmonary function tests and quantitative computed tomography (CT) evaluation: A pilot study
Authors: Iwasawa Tae , Takahashi Hiroshi , Ogura Takashi , Asakura Akira , Gotoh Toshiyuki , Kagei Seiichiro , Nishimura Jun‐ichi , Obara Makoto , Inoue Tomio 
Published: October 2007

AbstractPurposeTo evaluate the effect of ventilatory impairment on MR signal intensity of the lung parenchyma.Materials and MethodsSubjects were five normal volunteers (age = 30 ± 7.9 years, mean ± SD) and 19 male patients with chronic obstructive lung disease (COPD) (mean age = 70.4 ± 6.5 years). Coronal MR images were obtained over entire lung fields at full inspiration and full expiration with cardiac triggering on a 1.5T system. Changes in the mean lung intensity between the two respiratory states were normalized by each intercept of the linear regression lines of the signal changes, and the slope of the relationship was calculated. Computed tomography (CT) images were also obtained in COPD patients at full inspiration using a multidetector row CT scanner. Attenuation values less than −950 Hounsfield units (HU) (RA‐950) represented the percentage of relative lung area on the CT.ResultsThe mean slope of COPD patients (0.365 ± 0.074) was less steep than that of the normal subjects (0.570 ± 0.124, P < 0.001). In COPD patients, the slope correlated significantly with forced expiratory volume in one second (FEV1, r = 0.508, P = 0.026), but not with RA‐950.ConclusionIn COPD patients, lung signal change measured by MRI correlates with airflow obstruction, but not with volume of the emphysema measured by lung CT. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Line scan diffusion spectrum of the denervated rat skeletal muscle
Authors: Yamabe Eiko , Nakamura Toshiyasu , Oshio Koichi , Kikuchi Yoshito , Toyama Yoshiaki , Ikegami Hiroyasu 
Published: October 2007

AbstractPurposeTo detect the earlier changes of the skeletal muscle of rats after peripheral nerve injury by measuring the apparent diffusion coefficient (ADC) on diffusion MR spectroscopy.Materials and MethodsThe posterior tibial nerve was transected in six rats (nerve transection group) and was only dissected in six rats (control group). At one, three, five, seven, 14, and 28 days after the surgery, both the T2 value and the ADC of gastrocnemius muscle were measured using a line‐scan diffusion spectrum on a 1.5T clinical MR imager on both groups.ResultsIn the nerve transection group, the T2 ratio compared to the contralateral side increased gradually over four weeks after the transection, while the ADC ratio increased right after the surgery and began to decrease at five days. Four weeks after the transection, the ADC ratio returned to normal while the T2 ratio stayed at a high value. The control group indicated an almost constant T2 and ADC ratio during the experimental periods.ConclusionThe ADC of the skeletal muscle increased quickly after the transection of the dominant peripheral nerve and was detectable one day after the surgery. Diffusion MRI can be a useful tool for early detection of peripheral nerve injury instead of T2‐weighted MRI or electromyography (EMG). J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
MRI appearance of perianal carcinoma in Crohn's disease
Authors: Lad Shilpa V. , Haider Masoom A. , Brown Carl J. , Mcleod Robin S. 
Published: October 2007

AbstractDetection of carcinoma in perianal Crohn's disease can be difficult. The purpose of this study was to describe the MRI appearance of anorectal cancer in patients with perianal Crohn's disease. A total of six patients with anorectal carcinoma (four mucinous adenocarcinoma, two squamous) in Crohn's disease were retrospectively reviewed. Axial T2 and dynamic postcontrast fat‐suppressed T1‐weighted gradient echo sequences were performed, and findings were compared with 18 noncancer patients with perianal fistulae in Crohn's disease. MRI characteristics of carcinoma were irregular inner wall contours and delayed mild enhancement of internal tissue. The combined features of an irregular internal wall and delayed enhancing tissue were seen exclusively in cancer patients. The four cases of mucinous adenocarcinoma all displayed a pattern of lobulated fluid‐filled cavities with delayed internal tissue enhancement. This pattern was not seen in any of the control cases. The presence of a double‐layered enhancement pattern was seen in both cases of squamous carcinoma and in only one of four cases of mucinous adenocarcinoma and one of 18 noncancer cases. The pattern of contrast enhancement is valuable in the MRI diagnosis of carcinoma in perianal Crohn's disease. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Diagnostic performance of MRI relative to CT for metastatic nodes of head and neck squamous cell carcinomas
Authors: Sumi Misa , Kimura Yasuo , Sumi Tadateru , Nakamura Takashi 
Published: October 2007

AbstractPurposeTo compare the diagnostic abilities of magnetic resonance imaging (MRI) and computed tomography (CT) based on the architectural changes in the nodal parenchyma.Materials and MethodsWe retrospectively studied histologically proven 70 metastatic and 52 reactive nodes in the necks of 38 patients with head and neck squamous cell carcinomas who had undergone both CT and MRI. We assessed the detectability of the architectural changes in the nodal parenchyma that were suggestive of cancer focus (cancer nest, necrosis, and keratinization). The diagnostic abilities of CT and MRI were assessed by three observers separately for the small (<10 mm in minimum axis diameter) and large (≥10 mm) nodes.ResultsMRI was significantly more effective than CT in diagnosing small metastatic nodes, yielding 83% sensitivity, 88% specificity, and 86% accuracy. However, the diagnostic abilities of MRI and CT were similar for large metastatic nodes; MRI yielded 100% sensitivity, 98% specificity, and 99% accuracy. receiver operating characteristic analysis also indicated that the Az values were significantly higher for MRI than for CT (0.927 vs. 0.822, P = 0.00054) for the detection of small nodes.ConclusionMRI is superior to CT in the diagnosis of metastatic nodes from head and neck squamous cell carcinomas. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Alteration of blood oxygenation level‐dependent signaling by local circulatory condition
Authors: Kamba Masayuki , Sung Yul‐Wan , Ogawa Seiji 
Published: October 2007

AbstractPurposeTo determine regional differences in the relationship between neuronal activation and blood oxygenation level‐dependent (BOLD) signal changes.Materials and MethodsWe performed BOLD and perfusion‐based studies on healthy adult volunteers (40 for BOLD and 20 for perfusion‐based studies) with visual stimulation of varied extent in the visual field of subjects.ResultsRegions with a significant negative correlation between the extent of visual stimuli and BOLD and perfusion responses were found bilaterally on the lateral surface of the occipital lobe just anterior to the occipital pole. These regions were located in the border zone between the territories of the middle and posterior cerebral arteries.ConclusionInsufficient perfusion pressure in these regions may have led to attenuation of BOLD and perfusion responses to stimulation of a large portion of the visual field, or a condition in which a large extent of the visual areas was activated in the proximal regions of the territories perfused by the middle and posterior cerebral arteries. This finding supports the hypothesis that regional differences in circulatory condition can result in alterations of the relationship between neuronal activation and BOLD signal changes in the normal human brain. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.