bluuebunny/crossref_metadata_2025_split huggingface dataset:
MRI Findings of recurrent hepatocellular carcinoma after liver transplantation: Preliminary results
Authors: Lee Chang Hee , Brubaker Lauren M. , Gerber David A. , Ku Young Mi , Kim Young Hoon , Shin Sang Soo , Semelka Richard C. 
Published: May 2011

AbstractPurposeTo describe the patterns of recurrence and serial magnetic resonance imaging (MRI) features of hepatocellular carcinoma (HCC) after liver transplantation.Materials and MethodsAll cases of recurrent HCC after transplantation between September 2002 and August 2009 that underwent MRI including precontrast T1, T2‐weighted images, and postgadolinium dynamic images were reviewed. On MRI we evaluated the characteristics and patterns of recurrent HCC after transplantation.ResultsA total 7 of 76 transplanted patients (four men, three women, age range, 45–63, mean 52.7 years) were included in this study. Four patients (57.1%) were identified to have a pattern of persistent local disease (PLD) near the transplanted liver, hepatorenal space, or suture site within 2.75 years (range, 2–4 years). Two patients showed recurrent HCC in the allograft alone within 5 years. One patient showed an intraperitoneal seeding (IPS) pattern which demonstrated diffuse peritoneal infiltration and thickening within 9 months. The diffuse metastatic disease (DMD) pattern was observed as a late manifestation of PLD and IPS. The most prominent volume of recurrent tumor burden was found in an extrahepatic (5 of 7 patients) compared to an intrahepatic (2 of 7 patients) location. The signal intensities and enhancement patterns did not exhibit change with disease progression.ConclusionWe describe four patterns of recurrence of HCC following transplant. The most prominent tumor burden was located in an extrahepatic compared to an intrahepatic location. J. Magn. Reson. Imaging 2011;33:1399–1405. © 2011 Wiley‐Liss, Inc.
Morphological manifestations of nonpuerperal mastitis on magnetic resonance imaging
Authors: Liu Haiquan , Peng Weijun 
Published: May 2011

AbstractPurpose:To investigate the morphological features of nonpuerperal mastitis on magnetic resonance imaging (MRI).Materials and Methods:MRI results of 27 patients diagnosed with nonpuerperal mastitis were retrospectively analyzed according to the Breast Imaging Reporting and Data System (BI‐RADS).Results:According to the enhanced MRI results, 22 cases presented as nonmass‐like enhancements and five cases presented as masses. For the 22 nonmass‐like enhancement lesions, one case showed as a homogeneous enhancement and 21 cases showed as heterogeneous enhancements. In the 21 heterogeneous enhancement cases, 13 contained lesions of rim‐like enhancement. With regard to the number of lesions with rim‐like enhancement, 11 presented as multiple and two as single. In the five mass lesions, three presented as rim enhancements. Indications of rim or rim‐like enhancement accounted for 59% (16/27) of all cases. For the 16 cases that presented with signs of rim or rim‐like enhancement, the central hypointensity area surrounded by enhanced rim or rim‐like entity showed as hyperintensity in 14 cases and hypointensity or heterointensity in two cases on T2‐weighted imaging.Conclusion:On contrast‐enhanced MRI, most nonpuerperal mastitis presented as nonmass‐like lesion with heterogeneous signal intensity. The observation of signs of rim or rim‐like enhancement on contrast‐enhanced MRI with central hypointensity areas showing as hyperintensity on T2‐weighted imaging is suggestive of the possibility of nonpuerperal mastitis. J. Magn. Reson. Imaging 2011;33:1369–1374. © 2011 Wiley‐Liss, Inc.
Fast Lipid And Water Levels by Extraction with Spatial Smoothing (FLAWLESS): Three‐dimensional volume fat/water separation at 7 Tesla
Authors: Narayan Sreenath , Huang Fangping , Johnson David , Gargesha Madhusudhana , Flask Chris A. , Zhang Guo‐Qiang , Wilson David L. 
Published: May 2011

AbstractPurpose:To quickly and robustly separate fat/water components of 7T MR images in the presence of field inhomogeneity for the study of metabolic disorders in small animals.Materials and Methods:Starting with a Markov random field (MRF) based formulation for the 3‐point Dixon separation problem, we incorporated new implementation strategies, including stability tracking, multiresolution image pyramid, and improved initial value generation. We term the new method FLAWLESS (Fast Lipid And Water Levels by Extraction with Spatial Smoothing).Results:Compared with non‐MRF techniques, FLAWLESS decreased the fat–water swapping mistakes in all of the three‐dimensional (3D) animal volumes that we tested. FLAWLESS converged in approximately 1/60th of the computation time of other MRF approaches. The initial value generation of FLAWLESS further improved robustness to field inhomogeneity in 3D volume data.Conclusion:We have developed a novel 3‐point Dixon technique found to be useful for high field small animal imaging. It is being used to assess lipid depots and metabolic disorders as a function of genes, diet, age, and therapy. J. Magn. Reson. Imaging 2011;33:1464–1473. © 2011 Wiley‐Liss, Inc.
Breast diffusion‐weighted MRI: Comparison of tetrahedral versus orthogonal diffusion sensitization for detection and localization of mass lesions
Authors: Ueguchi Takashi , Yamada Sachiko , Mihara Naoki , Koyama Yoshihiro , Sumikawa Hiromitsu , Tomiyama Noriyuki 
Published: May 2011

AbstractPurpose:To evaluate the potential of tetrahedral diffusion‐weighted imaging (DWI) compared to orthogonal DWI for detection and localization of early enhanced breast mass lesions at 1.5T.Materials and Methods:Sixty‐seven consecutive patients (mean age 51.7 years, range 14–84 years) with 68 solitary early enhanced breast lesions suspicious for cancer on dynamic contrast‐enhanced magnetic resonance imaging (MRI) were enrolled in this retrospective study. Two radiologists independently observed maximum intensity projection images of orthogonal and tetrahedral DWI and the diagnostic accuracy and background tissue visibility between two DWI techniques were compared. Contrast‐enhanced MRI was used as the reference standard. Background tissue visibility was assessed based on whether the “breast quadrant” and “skin line” were determined. A phantom validation study for apparent diffusion coefficient (ADC) values was also conducted.Results:Sensitivity (93%) and specificity (96%) on tetrahedral DWI were equivalent to those on orthogonal DWI (sensitivity, 88%; specificity, 95%). Background tissue was more easily determined with tetrahedral DWI (breast quadrant, 90%; skin lines, 95%) than with orthogonal DWI (breast quadrant, 61%; skin lines, 16%). ADC values of tetrahedral DWI were highly correlated with those of orthogonal DWI.Conclusion:Tetrahedral DWI provided equivalent detectability of mass lesions with improved visibility of surrounding anatomical structure. J. Magn. Reson. Imaging 2011;33:1375–1381. © 2011 Wiley‐Liss, Inc.
Noncontrast MR angiography for comprehensive assessment of abdominopelvic arteries using quadruple inversion‐recovery preconditioning and 3D balanced steady‐state free precession imaging
Authors: Atanasova Iliyana P. , Kim Daniel , Lim Ruth P. , Storey Pippa , Kim Sooah , Guo Hua , Lee Vivian S. 
Published: May 2011

AbstractPurpose:To develop a noncontrast magnetic resonance angiography (MRA) method for comprehensive evaluation of abdominopelvic arteries in a single 3D acquisition.Materials and Methods:A noncontrast MRA (NC MRA) pulse sequence was developed using four inversion‐recovery (IR) pulses and 3D balanced steady‐state free precession (b‐SSFP) readout to provide arterial imaging from renal to external iliac arteries. Respiratory triggered, high spatial resolution (1.3 × 1.3 × 1.7 mm3) noncontrast angiograms were obtained in seven volunteers and ten patients referred for gadolinium‐enhanced MRA (CE MRA). Images were assessed for diagnostic quality by two radiologists. Quantitative measurements of arterial signal contrast were also performed.Results:NC MRA imaging was successfully completed in all subjects in 7.0 ± 2.3 minutes. In controls, image quality of NC MRA averaged 2.79 ± 0.39 on a scale of 0–3, where 3 is maximum. Image quality of NC MRA (2.65 ± 0.41) was comparable to that of CE MRA (2.9 ± 0.32) in all patients. Contrast ratio measurements in patients demonstrated that NC MRA provides arterial contrast comparable to source CE MRA images with adequate venous and excellent background tissue suppression.Conclusion:The proposed noncontrast MRA pulse sequence provides high‐quality visualization of abdominopelvic arteries within clinically feasible scan times. J. Magn. Reson. Imaging 2011;33:1430–1439. © 2011 Wiley‐Liss, Inc.
Dual‐temporal resolution dynamic contrast‐enhanced MRI protocol for blood–brain barrier permeability measurement in enhancing multiple sclerosis lesions
Authors: Jelescu I.O. , Leppert I.R. , Narayanan S. , Araújo D. , Arnold D.L. , Pike G.B. 
Published: May 2011

AbstractPurpose:To design a more accurate and reproducible technique for the measurement of blood–brain barrier (BBB) permeability in gadolinium‐enhancing multiple sclerosis (MS) lesions.Materials and Methods:Four MS patients were scanned using a new dynamic contrast‐enhanced (DCE)‐magnetic resonance imaging (MRI) protocol based on an uninterrupted two‐part acquisition consisting of an initial part at high temporal and low spatial resolutions and a second part at low temporal and high spatial resolutions. The method preserves both the high spatial resolution needed for the often small size of lesions and the high temporal resolution required during the first minute after injection to sufficiently sample the first‐pass bolus. Simulations compared the performance of this new protocol with the conventional one at low temporal and high spatial resolutions throughout.Results:The BBB permeability estimates changed by up to 33% between the two protocols. The new protocol led to simulated error on Ktrans of 7%–10%, versus 7%–30% with the conventional protocol, and was more robust with respect to offsets between acquisition and injection start times, differences in shape of the first‐pass peak, and permeability values.Conclusion:The dual‐temporal resolution protocol produces improved BBB permeability estimates and provides a more complete view of active inflammatory MS lesion pathology. J. Magn. Reson. Imaging 2011;33:1291–1300. © 2011 Wiley‐Liss, Inc.
Measurement of aortic arch pulse wave velocity in cardiovascular MR: Comparison of transit time estimators and description of a new approach
Authors: Dogui Anas , Redheuil Alban , Lefort Muriel , DeCesare Alain , Kachenoura Nadjia , Herment Alain , Mousseaux Elie 
Published: May 2011

AbstractPurpose:To investigate the efficiency of a new method (TT‐Upslope) for transit time (Δt) estimation from cardiovascular MR (CMR) velocity curves.Materials and Methods:Fifty healthy volunteers (40 ± 15 years) underwent applanation tonometry to estimate carotid–femoral pulse wave velocity (cf‐PWV) and carotid pressure measurements, and CMR to estimate aortic arch‐PWV and ascending aorta distensibility (AAD). The Δt was calculated with TT‐Upslope by minimizing the area delimited by two sigmoid curves fitted to the systolic upslope of the ascending (AAC) and descending (DAC) aorta velocity curves, and compared with previously described methods: TT‐Point using the half maximum of AAC and DAC, TT‐Foot using AAC and DAC feet, and TT‐Wave by minimizing the area between AAC and DAC curves using cross correlation.Results:All the Δt methods provided a high reproducibility of arch‐PWV. However, TT‐Upslope and TT‐Wave resulted in better correlations with aging (r = 0.83/r = 0.83 versus r = 0.47/r = 0.72), cf‐PWV (r = 0.69/r = 0.70 versus r = 0.34/r = 0.59), and AAD (r = 0.81/r = 0.71 versus r = 0.61/r = 0.60). Furthermore, TT‐Upslope resulted in stronger relationship between arch‐PWV and AAD according to a theoretical model and provided better characterization of older subjects compared with TT‐Wave.Conclusion:Arch‐PWV estimated with CMR using the TT‐Upslope method was found to be reproducible and accurate, providing strong correlations with age and aortic stiffness indices. J. Magn. Reson. Imaging 2011;33:1321–1329. © 2011 Wiley‐Liss, Inc.
Cardiovascular MR dobutamine stress in adult tetralogy of fallot: Disparity between CMR volumetry and flow for cardiovascular function
Authors: Valverde Israel , Parish Victoria , Tzifa Aphrodite , Head Catherine , Sarikouch Samir , Greil Gerald , Schaeffter Tobias , Razavi Reza , Beerbaum Philipp 
Published: May 2011

AbstractPurpose:To evaluate the MR agreement of cardiac function parameters between volumetric (cine SSFP) and phase contrast flow (PC‐flow) assessment in patients with repaired tetralogy of Fallot (r‐TOF) and chronic pulmonary regurgitation (PR) at rest and under dobutamine stress (DS‐MR).Materials and Methods:We studied 18 patients with r‐TOF and severe chronic PR (34 ± 12.7 years, PR fraction[flow] 44 ± 15%) by cardiac MR at rest, 10 and 20 μg/kg/min of dobutamine. We compared analogous functional parameters by volumetry and PC‐flow: (i) Systemic output [left ventricle stroke volume (LVSV) versus aortic forward flow (AOFF)], (ii) Pulmonary output [right ventricle stroke volume (RVSV) versus pulmonary forward flow (PAFF)], (iii) PR volume [(RVSV‐LVSV) versus pulmonary backward flow (PABF)], (iv) PR fraction [(RVSV‐LVSV/RVSV) versus (PABF/PAFF)].Results:We found excellent Bland‐Altman agreement (mean difference ± limits of agreement, mL/beat/m2) at rest for both the systemic (−0.8 ± 5.7) and pulmonary strokes volumes (−0.1 ± 7.6), which slightly deteriorates during DS‐MR. The PR volume showed acceptable agreement at rest (−3.6 ± 15.1), but also further deteriorated during stress (5.4 ± 24). In contrast, the PR fraction showed poor agreement equally at rest (−5.6 ± 22.8) and DS‐MR (3.2 ± 19.2).Conclusion:In r‐TOF with chronic PR, analogous functional parameters should not be used interchangeably between volumetric and PC‐flow assessment during DS‐MR evaluation. J. Magn. Reson. Imaging 2011;33:1341–1350. © 2011 Wiley‐Liss, Inc.
Quantitative assessment of the cervical spinal cord damage in neuromyelitis optica using diffusion tensor imaging at 3 Tesla
Authors: Qian Wenshu , Chan Queenie , Mak Henry , Zhang Zhongping , Anthony Marina‐Portia , Yau Kelvin Kai‐Wing , Khong Pek‐Lan , Chan Koon Ho , Kim Mina 
Published: May 2011

AbstractPurpose:To investigate whether quantitative MRI measures of cervical spinal cord white matter (WM) using diffusion tensor imaging (DTI) in neuromyelitis optica (NMO) differed from controls and correlated with clinical disability.Materials and Methods:Ten referred patients and 12 healthy volunteers were imaged on a 3 Tesla scanner and patients were clinically assessed on the Expanded Disability Status Scale (EDSS). Two raters quantified DTI‐derived indices from all participants, including fractional anisotropy (FA), mean diffusivity (MD), parallel diffusivity (lambda[parallel]) and perpendicular diffusivity (lambda[perpendicular]) at C1–C6 for lateral and dorsal columns. After the inter‐rater reliability test, univariate correlations between DTI measures and disability were assessed using the Spearman's rho correlation coefficient. Multiple regression analysis was performed to investigate which DTI measures independently correlated with the clinical score.Results:Statistical test results indicated high reliability of all DTI measurements between two raters. NMO patients showed reduced FA, increased MD and lambda[perpendicular] compared with controls while lambda[parallel] did not show any significant difference. The former three DTI metrics also showed significant correlations with disability scores, and especially FA was found to be sensitive to mild NMO (EDSS ≤ 3)Conclusion:FA is a potentially useful quantitative biomarker of otherwise normal appearing WM damage in NMO. Such damage is associated with clinical disability. J. Magn. Reson. Imaging 2011;33:1312–1320. © 2011 Wiley‐Liss, Inc.
Early onset of retrograde flow in the main pulmonary artery is a characteristic of pulmonary arterial hypertension
Authors: Helderman Frank , Mauritz Gert‐Jan , Andringa Kirsten E. , Vonk‐Noordegraaf Anton , Marcus J. Tim 
Published: May 2011

AbstractPurpose:To evaluate if early onset of retrograde flow in the main pulmonary artery is a characteristic of pulmonary arterial hypertension (PAH).Materials and Methods:Fifty‐five patients with suspected pulmonary hypertension (PH) underwent right‐sided heart catheterization and retrospectively ECG‐gated MR phase‐contrast velocity quantification in the main pulmonary artery. Pulmonary hypertension was defined by a mean pulmonary artery pressure being larger than 25 mmHg. The onset time of the retrograde flow relative to the cardiac cycle duration (Relative Onset Time = ROT) was compared with mean pulmonary artery pressure.Results:By the catheterization, 38 patients were identified as having PAH. The ROT for these PAH patients was significantly different from those found in the 17 non‐PH subjects (0.14 ± 0.06 versus 0.37 ± 0.06, P < 0.001). The mean pulmonary artery pressure was related to the ROT (r2 = 0.62, P < 0.001) and could be estimated from the ROT with a standard deviation of 11.7 mmHg. With a cutoff value of 0.25, the ROT distinguished PAH patients from non‐PH subjects.Conclusion:Early onset of retrograde flow in the main pulmonary artery is a characteristic of pulmonary arterial hypertension and is visible by standard MR phase‐contrast velocity quantification. J. Magn. Reson. Imaging 2011;33:1362–1368. © 2011 Wiley‐Liss, Inc.
Hepatic fat quantification using chemical shift MR imaging and MR spectroscopy in the presence of hepatic iron deposition: Validation in phantoms and in patients with chronic liver disease
Authors: Lee Seung Soo , Lee Youngjoo , Kim Namkug , Kim Seong Who , Byun Jae Ho , Park Seong Ho , Lee Moon‐Gyu , Ha Hyun Kwon 
Published: May 2011

AbstractPurpose:To compare the accuracy of four chemical shift magnetic resonance imaging (MRI) (CS‐MRI) analysis methods and MR spectroscopy (MRS) with and without T2‐correction in fat quantification in the presence of excess iron.Materials and Methods:CS‐MRI with six opposed‐ and in‐phase acquisitions and MRS with five‐echo acquisitions (TEs of 20, 30, 40, 50, 60 msec) were performed at 1.5 T on phantoms containing various fat fractions (FFs), on phantoms containing various iron concentrations, and in 18 patients with chronic liver disease. For CS‐MRI, FFs were estimated with the dual‐echo method, with two T2*‐correction methods (triple‐ and multiecho), and with multiinterference methods that corrected for both T2* and spectral interference effects. For MRS, FF was estimated without T2‐correction (single‐echo MRS) and with T2‐correction (multiecho MRS).Results:In the phantoms, T2*‐ or T2‐correction methods for CS‐MRI and MRS provided unbiased estimations of FFs (mean bias, −1.1% to 0.5%) regardless of iron concentration, whereas the dual‐echo method (−5.5% to −8.4%) and single‐echo MRS (12.1% to 37.3%) resulted in large biases in FFs. In patients, the FFs estimated with triple‐echo (R = 0.98), multiecho (R = 0.99), and multiinterference (R = 0.99) methods had stronger correlations with multiecho MRS FFs than with the dual‐echo method (R = 0.86; P ≤ 0.011). The FFs estimated with multiinterference method showed the closest agreement with multiecho MRS FFs (the 95% limit‐of‐agreement, −0.2 ± 1.1).Conclusion:T2*‐ or T2‐correction methods are effective in correcting the confounding effects of iron, enabling an accurate fat quantification throughout a wide range of iron concentrations. Spectral modeling of fat may further improve the accuracy of CS‐MRI in fat quantification. J. Magn. Reson. Imaging 2011;33:1390–1398. © 2011 Wiley‐Liss, Inc.
Future changes in intense precipitation over Canada assessed from multi‐model NARCCAP ensemble simulations
Authors: Mailhot Alain , Beauregard Ian , Talbot Guillaume , Caya Daniel , Biner Sébastien 
Published: May 2011

AbstractAnnual maxima (AM) series of precipitation from 15 simulations of the North American Regional Climate Change Assessment Program (NARCCAP) have been analysed for gridpoints covering Canada and the northern part of United States. The NARCCAP Regional Climate Models' simulations have been classified into the following three groups based on the driving data used at the RCMs boundaries: (1) NCEP (6 simulations); (2) GCM‐historical (5 simulations); and (3) GCM‐future (4 simulations). Historical simulations are representative of the 1968‐2000 period while future simulations cover the 2041‐2070 period. A reference common grid has been defined to ease the comparison. Multi‐model average intensities of AM precipitation of 6‐, 12‐, 24‐, 72‐, and 120‐h for 2‐, 5‐, 10‐, and 20‐year return periods have been estimated for each simulation group. Comparison of results from NCEP and GCM‐historical groups shows good overall agreement in terms of spatial distribution of AM intensities. Comparison of GCM‐future and GCM‐historical groups clearly shows widespread increases with median relative changes across all gridpoints ranging from 12 to 18% depending on durations and return periods. Fourteen Canadian climatic regions have been used to define regional projections and average regional changes in intense precipitation have been estimated for each duration and return period. Uncertainties on these regional values, resulting from inter‐model variability, were also estimated. Results suggest that inland regions (e.g. Ontario and more specifically Southern Ontario, the Prairies, Southern Quebec) will experience the largest relative increases in AM intensities while coastal regions (e.g. Atlantic Provinces and the West Coast) will experience the smallest ones. These projections are most valuable inputs for the assessment of future impact of climate change on water infrastructures and the development of more efficient adaptation strategies. Copyright © 2011 Royal Meteorological Society
A statistical model for the urban heat island and its application to a climate change scenario
Authors: Hoffmann Peter , Krueger Oliver , Schlünzen K. Heinke 
Published: May 2011

AbstractA linear statistical model relating the nocturnal urban heat island (UHI) intensity of Hamburg with meteorological conditions is constructed from observations taken by the German Meteorological Service (DWD). To find the appropriate predictors the relationship between different meteorological variables and the UHI of Hamburg is analyzed. Results and physical plausibility suggest that cloud cover, wind speed and relative humidity are the relevant variables and can be used to construct a statistical model. The parameters for the statistical model are determined with the generalized least square method. With the help of the statistical model up to 42% of the UHI variance can be explained. The statistical model is then used to statistically downscale results from climate runs of the regional climate models (RCM) REMO and CLM. Both RCMs were driven with the A1B SRES emission scenario runs of the global climate model ECHAM5/MPI‐OM. The resulting values for the future UHI are analyzed with respect to monthly averages and the frequency distribution. Results show that changes in the UHI are different for the different months. Significant change (decrease of UHI) in the results of both RCMs and for both realizations of the A1B scenario can be found for April in at the middle and the end of the century and in December at the end of the century. For the summer months which are most relevant to the development of adaption strategies the results differ between the RCMs. REMO results show no significant changes for the summer, while analyses of CLM suggest significant increase in July and August. The frequency distribution of the summer UHI shows no significant changes for REMO and only in one realization of CLM a significant increase in moderate and strong UHI days can be found for the end of the century. Copyright © 2011 Royal Meteorological Society