bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationship between sodium intensity and perfusion deficits in acute ischemic stroke
Authors: Tsang Adrian , Stobbe Robert W. , Asdaghi Negar , Hussain Muhammad S. , Bhagat Yusuf A. , Beaulieu Christian , Emery Derek , Butcher Ken S.
Published: December 2010

Purpose

To assess the relationship between sodium signal intensity changes and oligemia, measured with perfusion‐weighted imaging (PWI), in ischemic stroke patients.

Materials and Methods

Nine ischemic stroke patients (55 ± 13 years), four with follow‐up scans, underwent sodium and proton imaging 4–32 hours after symptom onset. Relative sodium intensity was calculated as the ratio of signal intensities in core (identified as hypertintense lesions on diffusion‐weighted imaging [DWI]) or putative penumbra (PWI‐DWI mismatch) to contralateral homologous regions.

Results

Sodium intensity increases in the core were not correlated with the severity of hypoperfusion, measured with either cerebral blood flow (rho = 0.157; P = 0.61) or cerebral blood volume (rho = −0.234; P = 0.44). In contrast, relative sodium intensity was not elevated (4–7 hours 0.96 ± 0.07; 17–32 hours 1.00 ± 0.07) in PWI‐DWI mismatch regions.

Conclusion

Sodium signal intensity cannot be predicted by the degree of hypoperfusion acutely. Sodium intensity also remains unchanged in PWI‐DWI mismatch tissue, indicating preservation of ionic homeostasis. Sodium magnetic resonance imaging (MRI), in conjunction with PWI and DWI, may permit identification of patients with viable tissue, despite an unknown symptom onset time. J. Magn. Reson. Imaging 2011;33:41–47. © 2010 Wiley‐Liss, Inc.
Glenohumeral joint instability
Authors: Omoumi Patrick , Teixeira Pedro , Lecouvet Frédéric , Chung Christine B.
Published: December 2010

Due to the configuration of its bony elements, the glenohumeral joint is the most mobile joint of the body, but also an inherently unstable articulation. Stabilization of the joint is linked to a complex balance between static and dynamic soft tissue stabilizers. Because of complex biomechanics, and the existence of numerous classifications and acronyms to describe shoulder instability lesions, this remains a daunting topic for most radiologists. In this article we provide a brief review of the anatomy of the glenohumeral joint, as well as the classifications and the pathogenesis of shoulder instability. Technical aspects related to the available imaging techniques (including computed tomography [CT] arthrography, magnetic resonance imaging [MRI], and MR arthrography) are reviewed. We then describe the imaging findings related to shoulder instability, focusing on those elements that are important to the clinician. J. Magn. Reson. Imaging 2011;33:2–16. © 2010 Wiley‐Liss, Inc.
Effects of postprandial state and mesenteric blood flow on the repeatability of MR elastography in asymptomatic subjects
Authors: Hines Catherine D.G. , Lindstrom Mary J. , Varma Adarsh K. , Reeder Scott B.
Published: December 2010

Purpose

To determine the repeatability of stiffness measurements in the liver using MR elastography (MRE) during the fasted and fed states. MRE has gained increased recognition as a noninvasive method to quantify fibrotic changes in the liver. It is well known that eating increases splanchnic blood flow, and fasting status of patients has been recognized as a factor that may affect hepatic stiffness measured with MRE.

Materials and Methods

Hepatic MRE stiffness and flow through the superior mesenteric vein (SMV) were measured in 12 healthy subjects in fasted and fed states, and measurements were repeated 5 weeks later. A linear mixed effects model was used to estimate the sources of variability in the data, which included day (exams on different days) and subject. Sources were combined to calculate the overall standard deviation of a single MRE measurement.

Results

The total within‐subject standard deviation of an MRE exam is 8.5% (standard error [SE] = 1.7%) or 9.0% (SE = 1.8%) for fasted and fed states, respectively. No significant differences between fasted/fed state stiffness and no correlation between hepatic stiffness and SMV flow were observed.

Conclusion

As seen in this smaller population, healthy subjects scanned in a known fasted or fed state provide repeatable stiffness estimates with no relationship to SMV flow. J. Magn. Reson. Imaging 2011;33:239–244. © 2010 Wiley‐Liss, Inc.
Mapping developmental precentral and postcentral gyral changes in children on magnetic resonance images
Authors: Yang Faguo , Shan Zuyao Y.
Published: December 2010

Purpose

To study the shape changes in precentral gyrus (PRG) and postcentral gyrus (PCG) during healthy brain development in childhood.

Materials and Methods

Magnetic resonance (MR) images from 20 healthy children scanned twice at 6.3 ± 0.8 and 8.1 ± 0.9 years old were analyzed in this study. The analysis steps included: 1) The PRG and PCG were manually segmented from the MR images of each subject; 2) 3D mesh representing the PRG and PCG were built from the manually segmented images; 3) a series of shape description features were extracted and statistically analyzed by a permutation test method.

Results

This study showed the following statistically significant findings (P < 0.05): left PCG and PRG are located more posteriorly and superiorly than their right compartments; the hemispheric asymmetry of the PRG in the inferior–superior direction decreased after 2 years; the superior part of the PCG and PRG shifted and rotated to the posterior side of the brain.

Conclusion

During normal pediatric brain development hemispheric asymmetry and shape of PCG and PRG are changed. These findings, together with previous reports in the literature, illustrate a region‐specific brain structure maturation pattern in children and may be related to changing neurocognitive functions. J. Magn. Reson. Imaging 2011;33:62–70. © 2010 Wiley‐Liss, Inc.
Reliability of two techniques for assessing cerebral iron deposits with structural magnetic resonance imaging
Authors: Valdés Hernández Maria C. , Jeong Tina H. , Murray Catherine , Bastin Mark E. , Chappell Francesca M. , Deary Ian J. , Wardlaw Joanna M.
Published: December 2010

Purpose

To test the reliability of two computational methods for segmenting cerebral iron deposits (IDs) in the aging brain, given that its measurement in magnetic resonance imaging (MRI) is challenging due to the similar effect produced by other minerals, especially calcium, on T2*‐weighted sequences.

Materials and Methods

T1‐, T2*‐weighted, and fluid‐attenuated inversion recovery (FLAIR) MR brain images obtained at 1.5T from 70 subjects in their early 70s who displayed a wide range of brain IDs were analyzed. The first segmentation method used a multispectral approach based on the fusion of two or more structural sequences registered and mapped in the red/green color space followed by Minimum Variance Quantization. The second method employed a combined thresholding, size and shape analysis using T2*‐weighted images augmented with visual information from T1‐weighted data.

Results

Both segmentation techniques had high intra‐ and interobserver agreement (95% confidence interval [CI] = ± 57 voxels in a range from 0 to 1800), which decreased in subjects with significant microbleeds and/or IDs. However, the thresholding method was more observer dependent in identifying microbleeds and IDs boundaries than the multispectral approach.

Conclusion

Both techniques proved to be in agreement and have good intra‐ and interobserver reliability. However, they have limitations, specifically with regard to automation and observer independence, so further work is required to develop fully user‐independent methods of identifying cerebral IDs. J. Magn. Reson. Imaging 2011;33:54–61. © 2010 Wiley‐Liss, Inc.
Cardiac MRI to investigate myocardial scar and coronary venous anatomy using a slow infusion of dimeglumine gadobenate in patients undergoing assessment for cardiac resynchronization therapy
Authors: Duckett Simon G. , Chiribiri Amedeo , Ginks Matthew R. , Sinclair Stephen , Knowles Benjamin R. , Botnar Rene , Carr‐White Gerry S. , Rinaldi Christopher A. , Nagel Eike , Razavi Reza , Schaeffter Tobias
Published: December 2010

Purpose

To evaluate a cardiac MR (CMR) examination with slow infusion of a high‐relaxivity contrast agent to visualize coronary venous anatomy (CVA) and myocardial scar in heart failure patients awaiting cardiac resynchronization therapy (CRT).

Materials and Methods

Fourteen patients awaiting CRT (seven ischemic cardiomyopathy (ICM) and seven non‐ICM) and two with normal LV function underwent CMR on a 1.5 Tesla (T) MR scanner. Dimeglumine‐gadobenate was slowly infused. Bolus arrival in the LV was measured by a dynamic electrocardiogram (ECG) ‐triggered inversion recovery (IR) scan subsequent to starting an ECG‐triggered respiratory‐navigated three‐dimensional (3D) SSFP MR scan with IR preparation to acquire systolic whole‐heart anatomy for vein visualization. Delayed contrast‐enhanced MR scan was performed to assess myocardial scar. CVA obtained by CMR was compared with X‐ray venography in 11 patients. CVA and scar were segmented and registered for visual inspection.

Results

For all subjects, there was excellent visualization of the CVA. All ICM and one non‐ICM patient showed scar. There was excellent correlation between veins seen by CMR and venography.

Conclusion

We have demonstrated that slow infusion protocol of dimeglumine‐gadobenate can be used to assess both CVA and myocardial scar in a single MR examination. Furthermore, an image overlay technique has been used to show the relationship of scar to the CVA. J. Magn. Reson. Imaging 2011;33:87–95. © 2010 Wiley‐Liss, Inc.
Dynamic contrast‐enhanced magnetic resonance imaging and invasive breast cancer: Primary lesion kinetics correlated with axillary lymph node extracapsular extension
Authors: Loiselle Christopher R. , Eby Peter R. , Peacock Sue , Kim Janice N. , Lehman Constance D.
Published: December 2010

Purpose

To determine if dynamic contrast‐enhanced (DCE) magnetic resonance imaging (MRI) peak enhancement (PE) of primary breast cancer can predict the presence of lymph node extracapsular extension (LNECE) in patients with axillary metastatic disease.

Materials and Methods

In all, 167 patients treated with radiotherapy for invasive breast cancer from January 1, 2006 to November 1, 2007 were retrospectively identified. Patients with DCE‐MRI and surgical axillary staging were included in this study. PE of primary tumors was compared according to axillary nodal status: negative, positive without LNECE, or positive with LNECE. A receiver operator characteristic curve (ROC) was plotted to determine accuracy of PE to predict LNECE.

Results

Forty‐six patients met the study criteria. Thirty‐two (70%) were node‐negative, 9 (19%) were node‐positive without LNECE, and 5 (11%) were node‐positive with LNECE. PE was greater for patients with LNECE (mean 365%) compared to node‐positive patients without LNECE (mean 183%) P = 0.05 and node‐negative patients (mean 144%) P = 0.0012. Area under the ROC curve was 0.93.

Conclusion

DCE‐MRI PE may be a surrogate marker for LNECE. If validated, DCE‐MRI may provide noninvasive kinetic information informing axillary nodal status for patients who receive chemotherapy prior to surgical axillary staging or forego axillary dissection after a positive sentinel node biopsy. J. Magn. Reson. Imaging 2011;33:96–101. © 2010 Wiley‐Liss, Inc.
Liver methylene fraction by dual‐ and triple‐echo gradient‐echo imaging at 3.0T: Correlation with proton MR spectroscopy and estimation of robustness after SPIO administration
Authors: Guiu Boris , Petit Jean‐Michel , Loffroy Romaric , Aho Serge , Ben Salem Douraied , Masson David , Robin Isabelle , Vergès Bruno , Hillon Patrick , Cercueil Jean‐Pierre , Krausé Denis
Published: December 2010

Purpose

To assess the systematic errors in liver methylene fraction (LMF) resulting from fat–fat interference effects with dual‐ and triple‐echo gradient‐recalled‐echo Dual/Triple GRE) sequences and to test the robustness of these sequences after iron overloading.

Materials and Methods

Forty type‐2 diabetic patients underwent LMF measurement by 3.0T 1H magnetic resonance spectroscopy (corrected for T1 and T2 decays) as the reference standard and liver fat fraction (%Fat) measurement by four Dual/Triple GRE sequences with 20° and 60° flip angle (α), corrected for T1 recovery. The same four sequences were repeated in eight patients after ferumoxide injection. Corrections for systematic errors were determined from the linear regressions (spectroscopy LMF values over Dual/Triple GRE %Fat values). Robustness was tested using Wilcoxon's signed‐rank test.

Results

Fat–fat interference effects produced a ∼10% relative systematic error and T2* decay produced a 1.9%–4.2% absolute systematic error in LMF. When comparing before and after ferumoxide, dual‐echo imaging with α = 20° and α = 60°, even when corrected, showed absolute differences of 7.23% [2.81%–10.25%] (P = 0.0117) and 5.65% [1.89%–8.216.8%] (P = 0.0117), respectively; compared to only 1.17% [0.08%–2.83%] (P = 0.0251) and 1.15% [0.37%–2.73%] (P = 0.2626) with triple‐echo imaging and α = 20° and α = 60°, respectively.

Conclusion

Triple‐echo imaging with α = 60° corrected for both T1 recovery and fat–fat interference effects is robust after superparamagnetic iron oxide (SPIO) administration and can reliably quantify LMF. J. Magn. Reson. Imaging 2011;33:119–127. © 2010 Wiley‐Liss, Inc.
Increased gray matter volume of left pars opercularis in male orchestral musicians correlate positively with years of musical performance
Authors: Abdul‐Kareem Ihssan A. , Stancak Andrej , Parkes Laura M. , Sluming Vanessa
Published: December 2010

Purpose

To compare manual volumetry of gray matter (GM) / white matter (WM) of Broca's area subparts: pars opercularis (POP) and pars triangularis (PTR) in both hemispheres between musicians and nonmusician, as it has been shown that these regions are crucial for musical abilities. A previous voxel‐based morphometric (VBM) study conducted in our laboratory reported increased GM density in Broca's area of left hemisphere in male orchestral musicians. Functional segregation of POP/PTR justified separate volumetric analysis of these parts.

Materials and Methods

We used the same cohort for the VBM study. Manual morphometry (stereology) was used to compare volumes between 26/26 right‐handed orchestral musicians/nonmusicians.

Results

As expected, musicians showed significantly increased GM volume in the Broca's area, specifically in the left POP. No significant results were detected in right POP, left/right PTR GM volumes, and WM volumes for all regions. Results were positively correlated with years of musical performance (r = 0.7, P = 0.0001).

Conclusion

This result corroborates the VBM study and is in line with the hypothesis of critical involvement of POP in hearing‐action integration being an integral component of frontoparietotemporal mirror neuron network. We hypothesize that increased size of musicians' left POP represent use‐dependent structural adaptation in response to intensive audiomotor skill acquisition. J. Magn. Reson. Imaging 2011;33:24–32. © 2010 Wiley‐Liss, Inc.
Divergent neural processes specific to the acute and sustained phases of verum and SHAM acupuncture
Authors: Liu Jixin , Qin Wei , Guo Qian , Sun Jinbo , Yuan Kai , Dong Minghao , Liu Peng , Zhang Yi , von Deneen Karen M. , Liu Yijun , Tian Jie
Published: December 2010

Purpose

To discuss which brain region potentially functioned and switched between the immediate and delayed response of acupuncture.

Materials and Methods

A nonrepeated event‐related functional MRI (fMRI) design was used to investigate the spatial and temporal patterns of acupuncture effects induced by needling an acupoint ST36 (ACU) and a nonmeridian point (SHAM). The standard general linear model was used to detect the immediate neural responses of acupuncture. Graph theory analysis was used to characterize the functional integrated network of the acupuncture delayed effect.

Results

Acupuncture induced significant signal changes in the limbic/paralimbic areas, neocortical regions, brainstem, and cerebellum for immediate effect both in ACU and SHAM. Some of these brain regions showed strong functional connectivity for a delayed effect in ACU. Conjunction analysis showed that the insula played a critical role during the overall process of ACU. No overlapping brain regions were found in SHAM.

Conclusion

The findings of this study suggested that the delayed effects may reflect a more significant characteristic underlying acupuncture. Given that the insula as a relay station switched between the immediate and delayed response, it suggested that divergent functional connectivity patterns may mediate the acupuncture‐related effects for ACU and SHAM. J. Magn. Reson. Imaging 2011;33:33–40. © 2010 Wiley‐Liss, Inc.
Diffusion‐weighted imaging of the abdomen at 3.0 Tesla: Image quality and apparent diffusion coefficient reproducibility compared with 1.5 Tesla
Authors: Rosenkrantz Andrew B. , Oei Marcel , Babb James S. , Niver Benjamin E. , Taouli Bachir
Published: December 2010

Purpose

To compare single‐shot echo‐planar imaging (SS EPI) diffusion‐weighted MRI (DWI) of abdominal organs between 1.5 Tesla (T) and 3.0T in healthy volunteers in terms of image quality, apparent diffusion coefficient (ADC) values, and ADC reproducibility.

Materials and Methods

Eight healthy volunteers were prospectively imaged in this HIPAA‐compliant IRB‐approved study. Each subject underwent two consecutive scans at both 1.5 and 3.0T, which included breathhold and free‐breathing DWI using a wide range of b‐values (0 to 800 s/mm2). A blinded observer rated subjective image quality (maximum score= 8), and a separate observer placed regions of interest within the liver, renal cortices, pancreas, and spleen to measure ADC at each field strength. Paired Wilcoxon tests were used to compare abdominal DWI between 1.5T and 3.0T for specific combinations of organs, b‐values, and acquisition techniques.

Results

Subjective image quality was significantly lower at 3.0T for all comparisons (P = 0.0078– 0.0156). ADC values were similar at 1.5T and 3.0T for all assessed organs, except for lower liver ADC at 3.0T using b0‐500‐600 and breathhold technique. ADC reproducibility was moderate at both 1.5T and 3.0T, with no significant difference in coefficient of variation of ADC between field strengths.

Conclusion

Compared with 1.5T, SS EPI at 3.0T provided generally similar ADC values, however, with worse image quality. Further optimization of abdominal DWI at 3.0T is needed. J. Magn. Reson. Imaging 2011;33:128–135. © 2010 Wiley‐Liss, Inc.
Low‐dose 3D time‐resolved magnetic resonance angiography (MRA) of the supraaortic arteries: Correlation with high spatial resolution 3D contrast‐enhanced MRA
Authors: Lee Youn‐Joo , Laub Gerhard , Jung So‐Lyung , Yoo Won‐Jong , Kim Young‐Joo , Ahn Kook‐Jin , Kim Bum‐soo
Published: December 2010

Purpose

To evaluate the feasibility of low‐dose, 3D time‐resolved contrast‐enhanced magnetic resonance angiography (TR‐CEMRA) in the assessment of the supraaortic vessel, and to compare the results with high‐resolution contrast‐enhanced MRA (HR‐CEMRA).

Materials and Methods

This was an Institutional Review Board‐approved retrospective study. Forty‐five consecutive patients underwent contrast‐enhanced 3D TR‐CEMRA and 3D HR‐CEMRA for evaluation of neurovascular disease at 3.0 T. Gadobutrol was administered at a constant dose of 1 mL for TR‐CEMRA (independent of patient weight), and 0.1 mmol/kg for HR‐CEMRA. Two readers evaluated image quality using a four‐point scale (from 0 = excellent to 3 = nondiagnostic), and subsequently graded each stenosis into clinically relevant categories: normal (0%), mild stenosis (<50%), moderate to severe (>50%), and occlusion.

Results

The overall image quality for low‐dose TR‐CEMRA was in the diagnostic range (median 0, range 0–3). On the grading of stenosis, TR‐CEMRA using the TWIST sequence correlated with HR‐CEMRA (r = 0.668, P < 0.001). In terms of the comparison of TR‐CEMRA with HR‐CEMRA, of the 675 supraaortic arterial segments evaluated for stenosis or occlusion, agreement occurred in 611 of 675 (90.5%), overestimation in 41 of 675 (6.1%), and underestimation 23 of 675 (3.4%).

Conclusion

TR‐CEMRA achieved by administration of a small contrast dose (1 cc) yields rapid and important functional and anatomical information in the evaluation of supraaortic arteries. Due to limited spatial resolution, TR‐CEMRA at the current parameters has a tendency to overestimate the stenosis of smaller intracranial arteries compared to HR‐CEMRA. J. Magn. Reson. Imaging 2011;33:71–76. © 2010 Wiley‐Liss, Inc.
Preliminary evidence of altered gray and white matter microstructural development in the frontal lobe of adolescents with attention‐deficit hyperactivity disorder: A diffusional kurtosis imaging study
Authors: Helpern Joseph A. , Adisetiyo Vitria , Falangola Maria F. , Hu Caixia , Di Martino Adriana , Williams Kathleen , Castellanos Francisco X. , Jensen Jens H.
Published: December 2010

Purpose

To investigate non‐Gaussian water diffusion using diffusional kurtosis imaging (DKI) to assess age effects on gray matter (GM) and white matter (WM) microstructural changes in the prefrontal cortex (PFC) of adolescents with attention‐deficit hyperactivity disorder (ADHD) compared to typically developing controls (TDC).

Materials and Methods

In this preliminary cross‐sectional study, T1‐weighted magnetization‐prepared rapid gradient echo (MPRAGE) and DKI images were acquired at 3T from TDC (n = 13) and adolescents with ADHD (n = 12). Regression analysis of the PFC region of interest (ROI) was conducted.

Results

TDC show a significant kurtosis increase of WM microstructural complexity from 12 to 18 years of age, particularly in the radial direction, whereas WM microstructure in ADHD is stagnant in both the axial and radial directions. In ADHD, GM microstructure also lacked a significant age‐related increase in complexity as seen in TDC; only kurtosis measures were able to detect this difference.

Conclusion

These findings support the prevailing theory that ADHD is a disorder affecting frontostriatal WM. Our study is the first to directly quantify an aberrant age‐related trajectory in ADHD within GM microstructure, suggesting that the assessment of non‐Gaussian directional diffusion using DKI provides more sensitive and complementary information about tissue microstructural changes than conventional diffusion imaging methods. J. Magn. Reson. Imaging 2011;33:17–23. © 2010 Wiley‐Liss, Inc.
High‐resolution 3D coronary vessel wall imaging with near 100% respiratory efficiency using epicardial fat tracking: Reproducibility and comparison with standard methods
Authors: Scott Andrew D. , Keegan Jennifer , Firmin David N.
Published: December 2010

Purpose

To quantitatively assess the performance and reproducibility of 3D spiral coronary artery wall imaging with beat‐to‐beat respiratory‐motion‐correction (B2B‐RMC) compared to navigator gated 2D spiral and turbo‐spin‐echo (TSE) acquisitions.

Materials and Methods

High‐resolution (0.7 × 0.7 mm) cross‐sectional right coronary wall acquisitions were performed in 10 subjects using four techniques (B2B‐RMC 3D spiral with alternate (2RR) and single (1RR) R‐wave gating, navigator‐gated 2D spiral (2RR) and navigator‐gated 2D TSE (2RR)) on two occasions. Wall thickness measurements were compared with repeated measures analysis of variance (ANOVA). Reproducibility was assessed with the intraclass correlation coefficient (ICC).

Results

In all, 91% (73/80) of acquisitions were successful (failures: four TSE, two 3D spiral (1RR) and one 3D spiral (2RR)). Respiratory efficiency of the B2B‐RMC was less variable and substantially higher than for navigator gating (99.6 ± 1.2% vs. 39.0 ± 7.5%, P < 0.0001). Coronary wall thicknesses (± standard deviation [SD]) were not significantly different: 1.10 ± 0.14 mm (3D spiral (2RR)), 1.20 ± 0.16 mm (3D spiral (1RR)), 1.14 ± 0.15 mm (2D spiral), and 1.21 ± 0.17 mm (TSE). Wall thickness reproducibility ranged from good (ICC = 0.65, 3D spiral (1RR)) to excellent (ICC = 0.87, 3D spiral (2RR)).

Conclusion

High‐resolution 3D spiral imaging with B2B‐RMC permits coronary vessel wall assessment over multiple thin contiguous slices in a clinically feasible duration. Excellent reproducibility of the technique potentially enables studies of disease progression/regression. J. Magn. Reson. Imaging 2011;33:77–86. © 2010 Wiley‐Liss, Inc.
Automatic segmentation propagation of the aorta in real‐time phase contrast MRI using nonrigid registration
Authors: Odille Freddy , Steeden Jennifer A. , Muthurangu Vivek , Atkinson David
Published: December 2010

Purpose

To assess the use of a nonrigid registration technique for semi‐automatic segmentation of the aorta from real‐time velocity mapping MRI.

Materials and Methods

Real‐time phase contrast images were acquired to measure flow and stroke volumes in 10 subjects, during free breathing, at rest, and during exercise. A nonrigid registration algorithm was developed to propagate a manually drawn region of interest in the aorta from one frame to all other frames of the real‐time sequence (148 images). Thus the technique provided a semi‐automatic segmentation over the whole sequence of images. The accuracy was assessed by comparison with manual segmentations in terms of Dice overlap measures and stroke volumes (SV).

Results

Semi‐automatic segmentations were comparable to manual ones (Dice score of 0.89 ± 0.04). Inter‐observer reproducibility was similar for manual and semi‐automatic segmentations (Dice score of 0.90 ± 0.04 in both cases, the difference was not significant). SV measurements also showed good agreement between manual and semi‐automatic segmentations (correlation coefficient r > 0.94), and the differences were not statistically significant.

Conclusion

Although real‐time phase contrast images have compromised image quality, a fast and robust segmentation of the aorta was possible using the registration‐based technique. J. Magn. Reson. Imaging 2011;33:232–238. © 2010 Wiley‐Liss, Inc.
Usefulness of diffusion‐weighted imaging for differentiating between desmoid tumors and malignant soft tissue tumors
Authors: Oka Kiyoshi , Yakushiji Toshitake , Sato Hiro , Fujimoto Toru , Hirai Toshinori , Yamashita Yasuyuki , Mizuta Hiroshi
Published: December 2010

Purpose

To evaluate the usefulness of diffusion‐weighted imaging (DWI) for differentiating between desmoid tumors and malignant soft tissue tumors.

Materials and Methods

Conventional MRI and DWI were performed for 8 desmoid tumors and 74 malignant soft tissue tumors. DWI was obtained with a single‐shot echo‐planar imaging sequence using a 1.5 Tesla (T) MR imager. DW images were acquired with motion‐probing gradient pulses applied along three directions (x, y, and z axes) with three b‐factors (0, 500, and 1000 s/mm2). Two observers blinded to clinical information measured three regions of interest within the solid tumor and selected a minimum apparent diffusion coefficient () in each lesion. The mean ADC of desmoid tumors was calculated and compared with that of malignant soft tissue tumors using the Mann‐Whitney U test.

Results

The mean ADC of desmoid tumors and malignant soft tissue tumors was 1.36 ± 0.48 × 10−3 mm2/s and 0.88 ± 0.20 × 10−3 mm2/s (mean ± SD), respectively. The mean ADC of the desmoid tumors was significantly higher than that of malignant soft tissue tumors (P < 0.01).

Conclusion

DWI is considered to be useful for differentiating between desmoid tumors and malignant soft tissue tumors. In the future, further investigation in a large series is necessary. J. Magn. Reson. Imaging 2011;33:189–193. © 2010 Wiley‐Liss, Inc.
Evaluation of respiratory liver and kidney movements for MRI navigator gating
Authors: Song Ruitian , Tipirneni Aaryani , Johnson Perry , Loeffler Ralf B. , Hillenbrand Claudia M.
Published: December 2010

Purpose

To determine the tracking factor by studying the relationship between kidney and diaphragm motions and to compare the efficiency of the gating‐and‐following and gating‐only algorithms in reducing motion artifacts in navigator‐gated scans.

Materials and Methods

Diaphragm and kidney motions were measured by using real‐time TrueFISP sequences from 10 healthy human volunteers to determine tracking factors at different acceptance windows. Mean tracking factors were used to calculate mean residual errors and improvement factors for the gating‐and‐following and gating‐only algorithms.

Results

Mean tracking factors for ±4, ±6, ±8 mm and full acceptance windows ranged from 0.6 to 0.7, with large interindividual variations. Acceptance rates increased as the size of the acceptance window increased (acceptance rate for a 4 mm window ∼50%). There was a greater reduction of motion errors by gating‐and‐following (maximum of 1.86 mm) than gating‐only (maximum of 7.05 mm).

Conclusion

Mean tracking factors obtained in this study can be used as a guideline for using the gating‐and‐following algorithm in navigator‐gated kidney scans. The gating‐and‐following and gating‐only algorithms were quantitatively compared, and it was found that the former is more effective in reducing motion errors. J. Magn. Reson. Imaging 2011;33:143–148. © 2010 Wiley‐Liss, Inc.
High‐resolution interleaved water‐fat MR imaging of finger joints with chemical‐shift elimination
Authors: Kwok Wingchi E. , You Zhigang , Seo Gwysuk , Lerner Amy , Totterman Saara , Ritchlin Christopher , Monu Johnny
Published: December 2010

Purpose

To study the use of an interleaved water‐fat (IWF) sequence with a custom‐made radiofrequency (RF) coil for high‐resolution imaging of arthritic finger joints.

Materials and Methods

High‐resolution finger magnetic resonance imaging (MRI) was performed using a custom‐made dedicated RF receiver coil and an IWF sequence. A phantom, a cadaver finger specimen, and the fingers of two normal controls and six arthritic subjects were imaged with a resolution of 156 × 156 × 600 μm. The appearance of anatomic structures on the IWF images were compared with images acquired with a regular sequence. The images were reviewed by two musculoskeletal radiologists for the depiction of anatomical structures and for the presence of abnormalities.

Results

The high‐resolution images revealed detailed structures of the finger joints not detectable using typical clinical resolution. The IWF sequence gave more realistic depiction of subchondral bone thickness, and avoided false bone erosions displayed in the regular sequence. It also allowed better visualization of ligaments and tendons.

Conclusion

This pilot study shows the feasibility and the potential usefulness of high‐resolution IWF imaging for finger joint evaluation. This technique may be useful for the diagnosis and treatment assessment of arthritis, and for the study of joint disease pathogenesis. J. Magn. Reson. Imaging 2011;33:245–251. © 2010 Wiley‐Liss, Inc.
Quantification of fat infiltration in oculopharyngeal muscular dystrophy: Comparison of three MR imaging methods
Authors: Gloor Monika , Fasler Susanne , Fischmann Arne , Haas Tanja , Bieri Oliver , Heinimann Karl , Wetzel Stephan G. , Scheffler Klaus , Fischer Dirk
Published: December 2010

Purpose

To analyze and compare three quantitative MRI methods to determine the degree of muscle involvement in oculopharyngeal muscular dystrophy (OPMD).

Materials and Methods

Muscle fat content (MFC) was determined based on water–fat quantification using a 2‐point Dixon (2PD) method and on a histogram analysis of the free induction decay (FID) signal of a gradient‐spoiled steady‐state free precession (SSFP) sequence. In addition, transverse relaxation times (T2) of muscle tissue were calculated using a monoexponential decay model.

Results

We observed an increased mean MFC in OPMD patients as compared to healthy controls with the adductor magnus and soleus muscles being the most involved muscles in the thigh and calf, respectively. Furthermore, strong correlations (0.78 < R2 < 0.94) between different quantitative MR methods were observed. Fewer outliers, however, were obtained by the 2PD method and T2 measurements, suggesting these methods being superior to the SSFP‐FID method.

Conclusion

Quantitative MR techniques, such as fast multiecho Dixon methods and T2 imaging, can reliably differentiate between healthy and dystrophic muscles in OPMD, even if muscles are only marginally affected. Quantitative methods thus represent a promising tool that may be able to monitor more objectively the individual disease progression and treatment response in future clinical trials in muscular dystrophies. J. Magn. Reson. Imaging 2011;33:203–210. © 2010 Wiley‐Liss, Inc.
Structural variability of endotoxins from R‐type isogenic mutants of Shigella sonnei
Authors: Kilár Anikó , Dörnyei Ágnes , Bui Annamária , Szabó Zoltán , Kocsis Béla , Kilár Ferenc
Published: December 2010

The structural variations in the rough‐type endotoxins [lipopolysaccharides (LPSs)] of Shigella sonnei mutant strains (S. sonnei phase II—4303, R41, 562H and 4350) were investigated by Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF‐MS) and tandem MS. A series of S. sonnei mutants had previously been the subject of analytical studies on the biosynthesis of heptose components in the core oligosaccharide region of LPSs. This study gives a complete overview on the structures of the full core and lipid A of S. sonnei mutant strains by MS. We found that the LPSs of the isogenic rough mutants were formed in a step‐like manner containing 0:1:2:3 heptose in the deep core region of 4350, 562H, R41 and 4303, respectively, and the longest LPS from the mutant S. sonnei 4303 contained also five hexoses. The structural variations in the lipid A moiety and in the oligosaccharide part of the intact LPS were followed by MALDI‐TOF‐MS/MS. For the dissolution and the ionization of the samples, 2,5‐dihydroxybenzoic acid in citric acid solution was applied as matrix. The detailed evaluation of the mass spectra indicates heterogeneity in the lipid part due to the differences in the phosphate and fatty acid composition. Copyright © 2010 John Wiley & Sons, Ltd.
Compositional studies of human RPE lipofuscin: mechanisms of molecular modifications
Authors: Murdaugh L. S. , Mandal S. , Dill A. E. , Dillon J. , Simon J. D. , Gaillard E. R.
Published: December 2010

The accumulation of lipofuscin has previously been implicated in several retinal diseases including Best's macular dystrophy, Stargardt's disease and age‐related macular degeneration (AMD). Previously one of the major fluorophores of lipofuscin was identified as a bis‐retinoid pyridinium salt called A2E, which is known to photochemically cause damage. In addition to A2E, there are numerous components in RPE lipofuscin that are unidentified. These compounds were determined to be structurally related to A2E by their fragmentation pattern with losses of 106, 190, 174 and/or 150 amu from the parent ion and the formation of fragments of ca 592 amu. The vast majority consists of relatively hydrophobic components corresponding to derivatized A2E with molecular weights in discrete groups of 800–900, 970–1080 and > 1200 m/z regions. In order to determine the mechanism of these modifications, A2E was chemically modified by; (1) the formation of specific esters, (2) reaction with specific aldehydes and (3) spontaneous auto‐oxidation. The contribution of ester formation to the naturally occurring components of lipofuscin was discounted since their fragmentation patterns were different to those found in vivo. Alternatively, reactions with specific aldehydes result in nearly identical products as those found in vivo. Artificial aging of RPE lipofuscin gives a complex mixture of structurally related components. This results from the auto‐ and/or photooxidation of A2E to form aldehydes, which then back react with A2E giving a series of higher molecular weight products. The majority of these modifications result in compounds that are much more hydrophobic than A2E. These higher molecular weight materials have increased values of log P compared to A2E. This increase in hydrophobicity most likely aids in the sequestering of A2E into granules with the concomitant diminution of its reactivity. Therefore, these processes may serve as protective mechanisms for the RPE. Copyright © 2010 John Wiley & Sons, Ltd.
Multiple unknown degradants generated from the insect repellent DEET by photoinduced processes on TiO2
Authors: Medana Claudio , Calza Paola , Dal Bello Federica , Raso Elena , Minero Claudio , Baiocchi Claudio
Published: December 2010

This paper deals with the photocatalytic transformation of N,N‐diethyl‐m‐toluamide (DEET), one of the most widespread and efficient mosquito repellents, under simulated solar irradiation using titanium dioxide as the photocatalytic source of oxidizing species. The investigation involved monitoring of the DEET decomposition, the identification of intermediate compounds and the assessment of mineralization. High‐resolution mass spectrometry was employed to assess the evolution of the photocatalyzed process over time. Fifty‐one main species were identified after DEET transformation. Several isomeric species were formed and were characterized by analyzing MS and MSn spectra in full, and by comparison with parent molecule fragmentation pathways. In the DEET molecule, the initial transformation involved mono‐ and polyhydroxylation followed by oxidation of the alcohol groups, cleavage of the alkyl chains or ring opening. All these intermediates are easily degraded and DEET is completely mineralized after 4 h of irradiation. Microtox bioassay (Vibrio fischeri) was employed to evaluate the ecotoxicity of solutions treated by photocatalysis. Copyright © 2010 John Wiley & Sons, Ltd.
A fully validated method for the determination of vardenafil in blood using gas chromatography/mass spectrometry
Authors: Papoutsis Ioannis , Nikolaou Panagiota , Athanaselis Sotirios , Pistos Constantinos , Maravelias Constantinos , Spiliopoulou Chara
Published: December 2010

Vardenafil (VDN) is one of the three commercially available phosphodiesterase type 5 inhibitors and it is mainly used in the treatment of erectile dysfunction. A sensitive and specific gas chromatography/mass spectrometry (GC/MS) method for the determination of VDN in blood has been developed and validated. Sample preparation included solid‐phase extraction and derivatization with N‐methyl‐N‐tert‐butyldimethylsilyl‐trifluoroacetamide (MTBSTFA) and 1% tert‐butyldimethylsilylchloride (TBDMSCl). Protriptyline was used as the internal standard for this assay. Limits of detection and quantification for VDN were 0.70 and 2.00 µg/l, respectively. The calibration curves were linear within the dynamic range 2.00–200.0 µg/l with a correlation coefficient higher than 0.991. Absolute recovery ranged from 88.6% to 95.7% for the analyte of interest at three quality control levels. Intra‐ and inter‐day accuracy was found to be between − 6.1% to 10.8% and − 9.3% to 11.6%, respectively, whereas intra‐ and inter‐day precision was < 7.8% and 9.7%, correspondingly. The proposed method is the first fully validated GC/MS method for the determination of VDN in blood samples and it can be used in routine every day analysis by clinical and forensic laboratories for pharmacokinetic studies, for therapeutic drug level monitoring or for the investigation of related forensic cases. A few blood samples analyzed using the developed method is reported herein to demonstrate the suitability of the method. Copyright © 2010 John Wiley & Sons, Ltd.
Tautomerization in gas‐phase ion chemistry of isomeric C‐8 deoxyguanosine adducts from phenol‐induced DNA damage
Authors: Sagoo Sandeep , Beach Daniel G. , Manderville Richard A. , Gabryelski Wojciech
Published: December 2010

Collision‐induced dissociation (CID) of 8‐(4″‐hydroxyphenyl)‐2′‐deoxyguanosine and 8‐(2″‐hydroxyphenyl)‐2′‐deoxyguanosine was investigated using sequential tandem mass spectrometry. These adducts represent biomarkers of DNA damage linked to phenolic radicals and were investigated to gain insight into the effects of chemical structure of a C‐8 modification on fragmentation pathways of modified 2′‐deoxyguanosine (dG). CID in MS2 of the deprotonated molecules of both the isomers generated the same product ion having the same m/z values. CID in MS3 of the product ion at m/z 242 and CID in MS4 experiments carried out on the selected product ions at m/z 225 and m/z 218 afford distinct fragmentation patterns. The conformational properties of isomeric product ions from CID showed that the ortho‐isomers possess the unique ability to tautomerize through an intramolecular proton transfer between the phenolic OH group and the imine nitrogen (N7). Tautomerization of ortho‐isomers to their keto‐tautomers led to differences in their system of conjugated double bonds compared with either their enol‐tautomer or the para‐isomer. The charge redistribution through the N‐7 site on the imidazole ring is a critical step in guanosine adduct fragmentation which is disrupted by the formation of the keto‐tautomer. For this reason, different reaction pathways are observed for 8‐(4″‐hydroxyphenyl)‐2′‐deoxyguanosine and 8‐(2″‐hydroxyphenyl)‐2′‐deoxyguanosine. We present herein the dissociation and the gas‐phase ion‐molecule reactions for highly conjugated ions involved in the CID ion chemistry of the investigated adducts. These will be useful for those using tandem mass spectrometry for structural elucidation of C‐8 modified dG adducts. This study demonstrates that the modification at the C‐8 site of dG has the potential to significantly alter the reactivity of adducts. We also show the ability of tandem mass spectrometry to completely differentiate between the isomeric dG adducts investigated. Copyright © 2010 John Wiley & Sons, Ltd.
Observations of different core water cluster ions Y−(H2O)n (Y = O2, HOx, NOx, COx) and magic number in atmospheric pressure negative corona discharge mass spectrometry
Authors: Sekimoto Kanako , Takayama Mitsuo
Published: December 2010

Reliable mass spectrometry data from large water clusters Y−(H2O)n with various negative core ions Y− such as O2−, HO−, HO2−, NO2−, NO3−, NO3−(HNO3)2, CO3− and HCO4− have been obtained using atmospheric pressure negative corona discharge mass spectrometry. All the core Y− ions observed were ionic species that play a central role in tropospheric ion chemistry. These mass spectra exhibited discontinuities in ion peak intensity at certain size clusters Y−(H2O)m indicating specific thermochemical stability. Thus, Y−(H2O)m may correspond to the magic number or first hydrated shell in the cluster series Y−(H2O)n. The high intensity discontinuity at HO−(H2O)3 observed was the first mass spectrometric evidence for the specific stability of HO−(H2O)3 as the first hydrated shell which Eigen postulated in 1964. The negative ion water clusters Y−(H2O)n observed in the mass spectra are most likely to be formed via core ion formation in the ambient discharge area (760 torr) and the growth of water clusters by adiabatic expansion in the vacuum region of the mass spectrometers (≈1 torr). The detailed mechanism of the formation of the different core water cluster ions Y−(H2O)n is described. Copyright © 2010 John Wiley & Sons, Ltd.
Investigating the effects of anterior tibial translation on anterior knee force in the porcine model: Is the porcine knee ACL dependent?
Authors: Boguszewski Daniel V. , Shearn Jason T. , Wagner Christopher T. , Butler David L.
Published: December 2010

This study sought to determine anterior force in the porcine knee during simulated 6‐degree‐of‐freedom (DOF) motion to establish the role of the anterior cruciate ligament (ACL). Using a 6‐DOF robot, a simulated ovine motion was applied to porcine hind limbs while recording the corresponding forces. Since the porcine knee is more lax than the ovine knee, anterior tibial translations were superimposed on the simulated motion in 2 mm increments from 0 mm to 10 mm to find a condition that would load the ACL. Increments through 8 mm increased anterior knee force, while the 10 mm increment decreased the force. Beyond 4 mm, anterior force increases were non‐linear and less than the increases at 2 and 4 mm, which may indicate early structural damage. At 4 mm, the average anterior force was 76.9 ± 10.6 N (mean ± SEM; p < 0.025). The ACL was the primary restraint, accounting for 80–125% of anterior force throughout the range of motion. These results demonstrate the ACL dependence of the porcine knee for the simulated motion, suggesting this model as a candidate for studying ACL function. With reproducible testing conditions that challenge the ACL, this model could be used in developing and screening possible reconstruction strategies. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:641–646, 2011
Experimental blunt chest trauma impairs fracture healing in rats
Authors: Recknagel Stefan , Bindl Ronny , Kurz Julian , Wehner Tim , Ehrnthaller Christian , Knöferl Markus Werner , Gebhard Florian , Huber‐Lang Markus , Claes Lutz , Ignatius Anita
Published: December 2010

In poly‐traumatic patients a blunt chest trauma is an important trigger of the posttraumatic systemic inflammatory response. There is clinical evidence that fracture healing is delayed in such patients, however, experimental data are lacking. Therefore, we investigated the influence of a thoracic trauma on fracture healing in a rat model. Male Wistar rats received either a blunt chest trauma combined with a femur osteotomy or an isolated osteotomy. A more rigid or a more flexible external fixator was used for fracture stabilization to analyze whether the thoracic trauma influences regular healing and mechanically induced delayed bone healing differently. The blunt chest trauma induced a significant increase of IL‐6 serum levels after 6 and 24 h, suggesting the induction of a systemic inflammation, whereas the isolated fracture had no effect. Under a more rigid fixation the thoracic trauma considerably impaired fracture healing after 35 days, reflected by a significantly reduced flexural rigidity (three‐point‐bending test), as well as a significantly diminished callus volume, moment of inertia, and relative bone surface (µCT analysis). In confirming the clinical evidence, this study reports for the first time that a blunt chest trauma considerably impaired bone healing, possibly via the interaction of the induced systemic inflammation with local inflammatory processes. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:734–739, 2011