bluuebunny/crossref_metadata_2025 huggingface dataset:
Imaging the New Madrid Seismic Zone using double‐difference tomography
Authors: Dunn Meredith , DeShon Heather R. , Powell Christine A.
Published: October 2013

Three‐dimensional P and S wave velocity (VP and VS) models and high‐resolution earthquake relocations are determined for the New Madrid Seismic Zone using double‐difference local earthquake tomography. The data set consists of arrival times and differential times recorded by the Cooperative New Madrid Seismic Network (CNMSN) from 2000 to 2007 and the 1989–1992 Portable Array Network and Data Acquisition deployment. Waveform cross correlation–derived differential times for the CNMSN data are also incorporated. The velocity solutions are compatible with previous solutions centered on the active arms of seismicity and cover a broader area, including mafic intrusions along the margin of the Reelfoot rift. Major features include elevated VP and VS associated with the mafic plutons and reduced VP and VS along and southeast of the Axial fault (AF), a major arm of seismicity trending along the rift axis. Low VP extends to a depth of at least 20 km along the portion of the AF that extends south of the Missouri bootheel. A locally high VP/VS anomaly imaged along the central portion of the Reelfoot fault is spatially correlated with a significant change in fault trend and is interpreted as a region containing high pore pressure and/or water‐filled microcracks.
High‐resolution MODIS aerosol retrieval during wildfire events in California for use in exposure assessment
Authors: Raffuse Sean M. , McCarthy Michael C. , Craig Kenneth J. , DeWinter Jennifer L. , Jumbam Loayeh K. , Fruin Scott , James Gauderman W. , Lurmann Frederick W.
Published: October 2013

Retrieval of aerosol optical depth (AOD) from the Moderate Resolution Imaging Spectroradiometer (MODIS) using the Collection 5 (C005) algorithm provides large‐scale (10 × 10 km) estimates that can be used to predict surface layer concentrations of particulate matter with aerodynamic diameter smaller than 2.5 µm (PM2.5). However, these large‐scale estimates are not suitable for identifying intraurban variability of surface PM2.5 concentrations during wildfire events when individual plumes impact populated areas. We demonstrate a method for providing high‐resolution (2.5 km) kernel‐smoothed estimates of AOD over California during the 2008 northern California fires. The method uses high‐resolution surface reflectance ratios of the 0.66 and 2.12 µm channels, a locally derived aerosol optical model characteristic of fresh wildfire plumes, and a relaxed cloud filter. Results show that the AOD derived for the 2008 northern California fires outperformed the standard product in matching observed aerosol optical thickness at three coastal Aerosol Robotic Network sites and routinely explained more than 50% of the variance in hourly surface PM2.5 concentrations observed during the wildfires.
Planetary‐scale wave activity as a source of varying tropospheric response to stratospheric sudden warming events: A case study
Authors: Martineau Patrick , Son Seok‐Woo
Published: October 2013

Stratospheric Sudden Warming (SSW) events are typically, but not always, accompanied by negative Northern Annular Mode anomalies in the troposphere. However, large uncertainties remain as to which dynamical processes are responsible for those anomalies. In order to highlight sources of variability in stratosphere‐troposphere coupling among SSW events, we present a case study of three selected events and show detailed Transformed Eulerian Mean diagnostics for momentum changes in the stratosphere and troposphere in the course of those events. Our results suggest that planetary‐scale waves, especially the zonal wave number 2 component, may play an important role not only for the onset of tropospheric anomalies in response to SSW events but also for introducing variability in the vertical coupling, i.e., whether the tropospheric circulation anomalies lag, lead, or occur simultaneous to the weakening of the vortex. Particularly, the meridional propagation of those waves in the upper troposphere could be an important factor that determines whether SSW events lag or lead tropospheric anomalies.
Nonlinear coupling between quasi 2 day wave and tides based on meteor radar observations at Maui
Authors: Huang Kai Ming , Liu Alan Z. , Lu Xian , Li Zhenhua , Gan Quan , Gong Yun , Huang Chun Ming , Yi Fan , Zhang Shao Dong
Published: October 2013

An observational study of nonlinear interaction between the quasi 2 day wave (QTDW) and the diurnal and semidiurnal tides from meteor radar measurements at Maui is reported. The diurnal and semidiurnal tides show a short‐term variation with the QTDW activity. The variation of amplitude of the semidiurnal tide is opposite to that of the QTDW. The minimum amplitudes of the diurnal tide appear several days later than the maximum amplitudes of the QTDW, and the diurnal tide obviously strengthens when the QTDW drops to small amplitudes. The bispectrum analysis shows significant nonlinear interactions among the QDTW and the tidal components. The two quasi 16 h modes with periods of 16.2 h and 15.8 h generated in the interactions of the QTDW with the diurnal and semidiurnal tides can clearly be distinguished because of the slight deviation of the QTDW period from 48 h. The bicoherence spectrum demonstrates that the QTDW and the semidiurnal tide have quite strong levels of coherence, indicating that the nonlinear interaction is a mechanism responsible for the variability of the semidiurnal tide. Although there is also some interaction between the QTDW and the diurnal tide, their coherence level is low. When the QTDW drops to very weak amplitudes, the background wind decreases and reverses. During this time, the diurnal tide holds large amplitudes. These results support the notion that the variability of the diurnal tide is mainly attributable to the strong QTDW‐induced changes in the background atmosphere, which was shown in the modeling study by Chang et al. (2011). Hence, both the nonlinear interaction and the background flow changes are responsible for the observed variation of the diurnal tide.
Changes in precipitation intensity over East Asia during the 20th and 21st centuries simulated by a global atmospheric model with a 60 km grid size
Authors: Kusunoki Shoji , Mizuta Ryo
Published: October 2013

We conducted three‐member ensemble simulations using a global atmospheric model with a high horizontal resolution of a 60 km grid size for the period 1872–2099 (228 years). Between 1872 and 2005, the model was forced with observed historical sea surface temperatures (SST), while between 2006 and 2099, the boundary SST data were estimated using the multimodel ensemble of the Coupled Model Intercomparison Project Phase 3 models and assuming A1B emission scenario. Annual mean precipitation (PAVE), the Simple Daily Precipitation Intensity Index (SDII), and the maximum 5 day precipitation total (R5d) averaged over East Asia increase almost monotonically through the 21st century. The statistically significant area of precipitation intensity increase is larger for 2080–2099 than for 2046–2065. In particular, intense rainfall will increase over northern and southern China during 2080–2099. The conversion rate from water vapor to precipitation per 1°C rise in surface air temperature for SDII and R5D is much larger than that for PAVE during the 21st century. This suggests that extreme rainfall events will occur more frequently than moderate rainfall events even if the amount of temperature rise is same. Future changes in the horizontal transport of water vapor also lead to more intense precipitation over East Asia. In particular, the increase in clockwise water vapor transport due to intensification of the subtropical high contributes to increased intense precipitation over southern China.
Thermodynamic and mass balance constraints on iron‐bearing phyllosilicate formation and alteration pathways on early Mars
Authors: Catalano Jeffrey G.
Published: October 2013

Widespread occurrences of phyllosilicates, predominantly nontronite and Mg saponite, in the Noachian‐aged crust of Mars place constraints on water availability and surface conditions. However, the Noachian atmosphere likely lacked oxidants capable of forming nontronite from the basaltic crust and its origins are thus uncertain. In this study, scenarios for the formation of iron‐bearing phyllosilicates from the weathering and hydrothermal alteration of Martian basalt were investigated using geochemical modeling to establish plausible pathways of nontronite generation and the effect of redox conditions on associated secondary phases. Hydrothermal alteration produced FeII and Mg saponite, serpentine, and zeolites at 100°C and chlorite, prehnite, and talc at 250°C, consistent with phases observed in crater deposits on Mars. Anoxic weathering produced primarily FeII and Mg saponite. High water‐rock ratios produced Al‐clays and amorphous silica and high pCO2 conditions inhibited smectite formation because of carbonate precipitation. Oxic weathering produced primarily nontronite and Mg saponite. Later oxidation of anoxic weathering products also formed nontronite‐Mg saponite assemblages; oxidation products of hydrothermal assemblages included nontronite, Mg saponite, and either Al smectites or residual zeolites or prehnite. These calculations demonstrate that there are multiple plausible routes to form Fe/Mg smectites on early Mars and that an oxidizing atmosphere need not have existed in the Noachian. Decoupling iron oxidation from initial clay formation raises the possibilities that Mars transitioned to conditions favoring widespread iron oxidation after phyllosilicate formation ceased and that residual, unoxidized ferrous iron phyllosilicates still exist today in the Martian subsurface.
A comparison of rayed craters on the Moon and Mercury
Authors: Neish C. D. , Blewett D. T. , Harmon J. K. , Coman E. I. , Cahill J. T. S. , Ernst C. M.
Published: October 2013

Observations of rayed craters at optical and radar wavelengths provide insight into the processes that lead to ray formation and degradation on terrestrial planets. We have compared optical and S‐Band radar data for several large (> 20 km diameter), young craters on the Moon and Mercury and find evidence that secondary cratering plays a significant role in the formation of crater rays. Regions where rays appear bright to optical and radar sensors correspond to dense concentrations of secondary craters, and the observed radar enhancement appears to be a result of the deposition of blocky, immature ejecta from the secondary craters and/or the rocky, immature interior walls of the secondary craters. We define a new optical maturity index for Mercury and find that rays in radar and optical images correspond closely, indicating that the rays are rich in centimeter‐ to decimeter‐sized clasts. Rays on the Moon are less prominent at radar wavelengths, suggesting that they are currently composed of smaller clasts, centimeter sized or less. This difference suggests that secondary craters are larger on Mercury and capable of excavating more decimeter‐sized clasts. Furthermore, observations of rayed craters provide an opportunity to assign relative ages to the youngest craters on the Moon and Mercury. Although rayed craters on Mercury appear most similar to the youngest craters on the Moon, the apparent ages are more likely influenced by inherent differences in impact velocity, surface gravitational acceleration, and target properties that result in the formation of larger secondary craters on Mercury.
Impact of mountain pine beetle outbreaks on forest albedo and radiative forcing, as derived from Moderate Resolution Imaging Spectroradiometer, Rocky Mountains, USA
Authors: Vanderhoof M. , Williams C. A. , Ghimire B. , Rogan J.
Published: October 2013

Mountain pine beetle (Dendroctonus ponderosae) outbreaks in North America are widespread and have potentially large‐scale impacts on albedo and associated radiative forcing. Mountain pine beetle outbreaks in Colorado and southern Wyoming have resulted in persistent and significant increases in both winter albedo (change peaked 10 years post outbreak at 0.06 ± 0.01 and 0.05 ± 0.01, in lodgepole pine (Pinus contorta) and ponderosa pine (Pinus ponderosa) stands, respectively) and spring albedo (change peaked 10 years post outbreak at 0.06 ± 0.01 and 0.04 ± 0.01, in lodgepole pine and ponderosa pine stands, respectively). Instantaneous top‐of‐atmosphere radiative forcing peaked for both lodgepole pine and ponderosa pine stands in winter at 10 years post outbreak at −1.7 ± 0.2 W m−2 and −1.4 ± 0.2 W m−2, respectively. The persistent increase in albedo with time since mountain pine beetle disturbance combined with the continued progression of the attack across the landscape from 1994–2011 resulted in an exponential increase in winter and annual radiative cooling (MW) over time. In 2011 the rate of radiative forcing within the study area reached −982.7 ± 139.0 MW, −269.8 ± 38.2 MW, −31.1 ± 4.4 MW, and −147.8 ± 20.9 MW in winter, spring, summer, and fall, respectively. An increase in radiative cooling has the potential to decrease sensible and/or latent heat flux by reducing available energy. Such changes could affect current mountain pine beetle outbreaks which are influenced by climatic conditions.
Laparoscopic robot‐assisted major hepatectomy
Authors: Boggi Ugo , Caniglia Fabio , Amorese Gabriella
Published: October 2013

Background

We herein present a systematic review of English literature on robot‐assisted major hepatectomy (MH).

Methods

Major hepatectomy was defined as resection of three or more liver segments. A literature search was performed using the Pubmed database. Articles containing more than five robotic MH were selected. In case of multiple publications from the same institution, only the most recent article was considered in order to avoid double counting of patients between series.

Results

Five articles were included in this review. A total of 68 robotic MH were analyzed, including 38 right hepatectomies and 30 left hepatectomies. There were no deaths. Two right hepatectomies (5.2%) and one left hepatectomy (3.3%) were converted to open surgery. Weighted average of operative time and intraoperative blood loss were 418.6 min and 411.4 ml, respectively. Four patients received blood transfusions (6.3%) and 17 developed postoperative complications (26.9%). Information on tumor type were available for 57 patients of whom 42 were diagnosed with malignant tumors (73.6%) and 15 with benign diseases (26.3%). No port site metastasis, peritoneal carcinomastosis, or intrahepatic recurrence were reported. Three patients had microscopic margin positivity.

Conclusions

Major hepatectomy can be performed under robotic assistance. Further experience is needed before final conclusions can be drawn.
Reactions of 2‐(1,3‐Dithiolan‐2‐ylidene)malononitrile with Amino‐ and Hydrazinophosphorus Compounds: A Facile Route to Functionalized Phosphorus Heterocycles
Authors: Ali Tarik E.
Published: October 2013

A facile and efficient route to functionalized phosphorus heterocycles was achieved by treatment of 2‐(1,3‐dithiolan‐2‐ylidene)malononitrile with amino‐ and hydrazinophosphorus compounds in the presence of a strong base via fragmentation of 1,3‐dithiolane ring.
Simple Synthesis of Quinoxalin‐2(1H)‐one N‐Oxides from N‐Aryl‐2‐nitrosoanilines and Alkylated Cyanoacetic Esters
Authors: Królikiewicz Magdalena , Wróbel Zbigniew
Published: October 2013

N‐Aryl‐2‐nitrosoanilines, available from the reaction of N‐arylamines with nitroarenes, condense under alkaline conditions with alkylated derivatives of cyanoacetic esters furnishing quinoxalin‐2(1H)‐one N‐oxides in good to excellent yields. The reaction involves the condensation of the carbanion with the nitroso group leading to the nitrone intermediate, followed by intramolecular acylation of the amine function.
Efficient and Expeditious Synthesis of Pyrano‐pyrimidines, Multi‐substituted γ‐Pyrans, and Their Antioxidant Activity
Authors: El‐Bayouki Khairy A. M. , Basyouni Wahid M. , Khatab Tamer K. , El‐Basyoni Fakhry A. , Hamed Ahmed R. , Mostafa Eslam A.
Published: October 2013

An efficient, expeditious catalytic route for the synthesis of ethyl 6‐amino‐5‐cyano‐2‐methyl‐4‐aryl‐4H‐pyran‐3‐carboxylates 2 was achieved via a three‐component, one‐pot reaction of malononitrile, ethyl acetoacetate, and various aromatic aldehydes in water as a solvent at room temperature. The key advantages are excellent yield, reaction time, and inexpensive catalyst. Also, cyclization of 4H‐pyrans 2 to the corresponding 4H‐pyrano[2,3‐d]pyrimidines 3 using silica sulfuric acid in the presence of acetic anhydride was described. Some synthesized compounds exhibited promising antioxidant activities.
Cyclization of Cyanoethylated Ketones as a Route to 6‐Substituted Indole Derivatives
Authors: Bergman Jan , Stensland Birgitta
Published: October 2013

δ‐Cyanoketones are quickly cyclized with KOtBu to 3‐aminocyclohex‐2‐enone derivatives, which in turn will give substituted indoles when treated with oxalyl chloride. Thus, 3‐amino‐6,6‐dimethylcyclohex‐2‐enone gave 3‐chloro‐6,6‐dimethyl‐2,5,6,7‐tetrahydroindole‐2,5‐dione, whose structure was corroborated by X‐ray crystallography, whereas the corresponding molecule without the blocking gem‐dimethyl groups, 3‐aminocyclohex‐2‐enone, gave via hydrogen shifts 6‐chloro‐3‐hydroxyoxindole.
The patient care circle: A descriptive framework for understanding care transitions
Authors: Lee Jennifer I. , Cutugno Christine , Pickering Sean P. , Press Matthew J. , Richardson Joshua E. , Unterbrink Michelle , Kelser Mary Elizabeth , Evans Arthur T.
Published: October 2013

BACKGROUND

Reducing hospital readmissions depends on ensuring safe care transitions, which requires a better understanding of the challenges experienced by key stakeholders.

OBJECTIVE

Develop a descriptive framework illustrating the interconnected roles of patients, providers, and caregivers in relation to readmissions.

DESIGN

Multimethod qualitative study with 4 focus groups and 43 semistructured interviews. Multiple perspectives were included to increase the trustworthiness (internal validity) and transferability (external validity) of the results. Data were analyzed using grounded theory to generate themes associated with readmission.

SETTING/PATIENTS

General medicine patients with same‐site 30‐day readmissions, their family members, and multiple care providers at a large urban academic medical center.

RESULTS

A keynote generated from the multiperspective responses was that care transitions were optimized by a well‐coordinated multidiscipline support system, described as the Patient Care Circle. In addition, issues pertaining to readmissions were identified and classified into 5 main themes emphasizing the necessity of a coordinated support network: (1) teamwork, (2) health systems navigation and management, (3) illness severity and health needs, (4) psychosocial stability, and (5) medications.

CONCLUSION

A well‐coordinated collaborative Patient Care Circle is fundamental to ensuring safe care transitions. Journal of Hospital Medicine 2013;8:619–626. © 2013 Society of Hospital Medicine
Evidence review: Periprocedural use of blood products
Authors: Hogshire Lauren C. , Patel Manish S. , Rivera Edward , Carson Jeffrey L.
Published: October 2013

Blood product transfusion has not been subject to rigorous clinical study, and great practice variations exist. Of particular concern to hospitalists is the use of red blood cells, plasma, and platelets prior to invasive procedures to correct anemia or perceived bleeding risk. We summarize the known risks associated with periprocedural anemia, prolonged international normalized ratio (INR), and thrombocytopenia, as well as the effects of blood product administration on clinical outcomes. Clinical trial evidence argues for a restrictive red blood cell transfusion threshold (a hemoglobin level of 7–8 g/dL or symptomatic anemia) for most perioperative patients. There are no high‐quality data to guide plasma and platelet transfusions around the time of procedures. Available data do not support the use of prothrombin time/INR to guide prophylactic administration of plasma, and there are scarce data to guide platelet use around the time of an invasive procedure. Therefore, we rely on current consensus expert opinion, which recommends administration of plasma in moderate‐ to high‐risk procedures when INR is >1.5. We recommend platelet transfusion in low‐risk procedures when platelet count is <20,000/μL, for average‐risk procedures when platelet count is <50,000/μL, and for procedures involving the central nervous system when the platelet count is <100,000/μL. Journal of Hospital Medicine 2013;8:647–652. © 2013 Society of Hospital Medicine
Pediatric to adult‐care transitions in childhood‐onset chronic disease: Hospitalist perspectives
Authors: Hunt Susan , Sharma Niraj
Published: October 2013

OBJECTIVE

Survey of adult‐centered hospitalist perspectives on caring for adults with chronic diseases of childhood onset (CDoCO) to investigate comfort level and identify targets of future educational and policy intervention.

METHODS

We developed an on‐line survey for adult‐centered hospitalists based on a prior outpatient survey and introduced it to the Society of Hospital Medicine membership via e‐mail. Consent was implied by completing the survey.

RESULTS

Of all respondents, 60% saw 5 or more adults with CDoCO over a 6‐month period. Among internal medicine respondents, 40% did not feel comfortable caring for this population, with lack of familiarity with the literature, lack of training in CDoCO, coordinating with multiple specialists, and lack of training in adolescent development and behavior ranked as the most significant barriers to care.

CONCLUSION

The steadily growing population of adults with CDoCO and their high inpatient utilization have lead to increased care by adult‐centered hospitalists, many of whom do not feel comfortable caring for them. Educational initiatives aimed at increasing medical knowledge base for common issues, training in adolescent development, increased care coordination, and access to address psychosocial issues would improve hospitalist comfort and patient care for this vulnerable population. Journal of Hospital Medicine 2013;8:627–630. © 2013 Society of Hospital Medicine
AUDIO RECORDING OF HOUSEHOLD INTERVIEWS TO ENSURE DATA QUALITY
Authors: Berazneva Julia
Published: October 2013

The use of audio recording technology in the collection of quantitative household survey data in developing countries offers many benefits at a low cost. The benefits include ensuring that interviews take place, training and supervision of enumerators, assuring data quality, secure data storage, and easy data sharing, among others. This paper describes the use of audio recording by a research project that collected household level data in rural western Kenya in 2011–2012. I discuss the benefits of audio recording, both anticipated and encountered, as well as the costs and the applicability of this method in other research settings. Copyright © 2013 John Wiley & Sons, Ltd.
Police Overestimation of Criminal Career Homogeneity
Authors: Roach Jason , Pease Ken
Published: October 2013

Police presumptions about criminal career trajectories have been little studied. The exploratory study reported here involved 42 police staff of varying rank and experience. Participants were asked to complete a questionnaire that asked them to predict the type of offence that an individual with a specified prior record would most probably commit next. Participating police personnel substantially overstated the homogeneity of criminal careers, that is, the nature of prior offences determined their prediction of their next offence more than available official data would deem reasonable. An incidental finding was that officers who rated the probability of further offending highest were also those who thought criminal careers most specialised. The implications for operational police decision‐making were discussed and held to be profound. Copyright © 2013 John Wiley & Sons, Ltd.
Quantitative 23Na MRI of human knee cartilage using dual‐tuned 1H/23Na transceiver array radiofrequency coil at 7 tesla
Authors: Moon Chan Hong , Kim Jung‐Hwan , Zhao Tiejun , Bae Kyongtae Ty
Published: October 2013

Purpose

To develop quantitative dual‐tuned (DT) 1H/23Na MRI of human knee cartilage in vivo at 7 Tesla (T).

Materials and Methods

A sensitive 23Na transceiver array RF coil was developed at 7T. B1 fields generated by the transceiver array coil were characterized and corrected in the 23Na images. Point spread function (PSF) of the 23Na images was measured, and the signal decrease due to partial‐volume‐effect was compensated in [23Na] quantification of knee cartilage. SNR and [23Na] in anterior femoral cartilage were measured from seven healthy subjects.

Results

SNR of 23Na image with the transceiver array coil was higher than that of birdcage coil. SNR in the cartilage at 2‐mm isotropic resolution was 26.80 ± 3.69 (n = 7). B1 transmission and reception fields produced by the DT coil at 7T were similar to each other. Effective full‐width‐half‐maximum of 23Na image was ∼5 mm at 2‐mm resolution. Mean [23Na] was 288.13 ± 29.50 mM (n = 7) in the anterior femoral cartilage of normal subjects.

Conclusion

We developed a new high‐sensitivity 23Na RF coil for knee MRI at 7T. Our 1H/23Na MRI allowed quantitative measurement of [23Na] in knee cartilage by measuring PSF and cartilage thickness from 23Na and 1H image, respectively. J. Magn. Reson. Imaging 2013;38:1063–1072. © 2013 Wiley Periodicals, Inc.
MRI in differentiating ovarian borderline from benign mucinous cystadenoma: Pathological correlation
Authors: Zhao Shu Hui , Qiang Jin Wei , Zhang Guo Fu , Wang Shi Jia , Qiu Hai Ying , Wang Li
Published: October 2013

Purpose

To investigate MRI in differentiating borderline mucinous cystadenoma (MC) from benign MC of the ovary.

Materials and Methods

We studied MR images of 26 benign MCs and 24 borderline MCs of the ovary. The following MRI features of tumors were evaluated and compared between two groups: laterality, shape, size, loculation, signal intensity of the fluid, thickness of the septation and the wall, and vegetations. The results of the MRI were then compared with the pathological findings.

Results

Honeycomb loculi, high signal intensity on T1WI, and low signal intensity on T2WI of the intracystic content, thickened septation or wall (≥5 mm), and vegetations (≥5 mm) were significantly more common in borderline MC than in benign MC with the sensitivity and specificity of identifying borderline MC of 50.0% and 80.8%, 41.7% and 96.2%, 45.8% and 96.2%, and 62.5% and 96.2%, respectively. The presence of any one of the following features—honeycomb loculi with a low signal intensity on T2WI, thickened septation or wall (≥5 mm), and vegetations (≥5 mm)—yielded the sensitivity, specificity, and accuracy of identifying borderline MC of 91.7%, 92.3%, and 92.0%, respectively.

Conclusion

MRI has the ability to accurately demonstrate the morphological characteristics of ovarian MC and reliably differentiate borderline MC from benign MC. J. Magn. Reson. Imaging 2014;39:162–166. © 2013 Wiley Periodicals, Inc.
Revisiting the central gland anatomy via MRI: Does the central gland extend below the level of verumontanum?
Authors: Hansford Barry Glenn , Peng Yahui , Jiang Yulei , Al‐Ahmadie Hikmat , Eggener Scott , Yousuf Ambereen , Oto Aytekin
Published: October 2013

Purpose

To determine whether the central gland of the prostate, composed of both central and transition zones, extends below the verumontanum in patients over age 43 based on prostate magnetic resonance imaging (MRI).

Materials and Methods

In all, 82 patients who underwent preoperative, multiparametric endorectal MRI (1.5T and 3T) at our institution were included. The central gland was defined as a combination of the central zone and transition zone. Two radiologists measured central gland extension below verumontanum using axial, coronal, and sagittal T2‐weighted images and coregistration picture archiving and communication system software.

Results

The final cohort consisted of 63 patients with a mean age of 60.2 years (standard deviation: 7.1, range: 43–76). The central gland extended below the verumontanum in 60/63 (95%) patients. Mean central gland extension below the verumontanum was 6.5 mm (standard deviation = 3.7, range: 0, 18). Weak (r = 0.35), but significant (P = 0.005) positive correlation was found between age and the amount of central gland extension below the verumontanum.

Conclusion

Contrary to McNeal's classical prostatic anatomy teaching, the central gland extends below the verumontanum in 95% of men over 43, likely due to deformation of the gland by benign prostatic hyperplasia. It is important for pathologists to be aware of this observation for accurate characterization of the zonal origin of prostate cancer below the level of the verumontanum. J. Magn. Reson. Imaging 2014;39:167–171. © 2013 Wiley Periodiacls, Inc.
Dose response of the intravascular contrast agent gadofosveset trisodium in MR perfusion imaging of the myocardium using semiquantitative evaluation
Authors: Niedermayer Sebastian , Prompona Maria , Cyran Clemens C. , Reiser Maximilian , Huber Armin
Published: October 2013

Purpose

To evaluate appropriate injection protocols for gadofosveset at 1.5 and 3 T magnetic resonance imaging (MRI) for semiquantitative myocardial perfusion analysis.

Materials and Methods

Eighteen young healthy volunteers were subjected to first‐pass perfusion cardiac scans at 1.5 and 3 T MRI using three different injection protocols for gadofosveset (0.00375, 0.0075, and 0.0150 mmol/kg bodyweight) and two perfusions. At both field strengths a T1‐weighted saturation recovery turboFLASH sequence with parallel imaging was employed. Peak signal‐to‐noise ratio (SNR), maximum contrast enhancement ratio (CER), peak‐baseline difference, and upslope values were assessed. Moreover, sectors with dark banding artifacts were evaluated.

Results

Significant differences of the upslope values for first compared to second perfusion could be observed for the medium‐ and high‐dose groups at 1.5 T (P < 0.01), but not at 3 T. Sectors with dark banding artifacts during first perfusion occurred significantly more often at the highest dose of gadofosveset compared to the lowest dose at 1.5 T (P = 0.04) and 3 T (P < 0.01).

Conclusion

The best injection protocol for semiquantitative perfusion analysis at 1.5 T is 0.00375 mmol/kg, as higher doses lead to lower upslope values during the second perfusion. At 3 T 0.0075 mmol/kg should be used to avoid dark banding artifacts. J. Magn. Reson. Imaging 2014;39:203–210. © 2013 Wiley Periodicals, Inc.
Usefulness of MR elastography for predicting esophageal varices in cirrhotic patients
Authors: Sun Hye Young , Lee Jeong Min , Han Joon Koo , Choi Byung Ihn
Published: October 2013

Purpose

To evaluate the usefulness of magnetic resonance elastography (MRE) as a noninvasive tool for predicting esophageal varices and identifying high‐risk varices.

Materials and Methods

In all, 126 patients with liver cirrhosis, and who underwent both MRI including MRE of the liver as well as upper gastrointestinal endoscopy for variceal screening within 1 month before or after the MRI, were included in this study. The relationship between the liver stiffness values measured by MRE and the degree of esophageal varices was assessed using Spearman's correlation analysis. In addition, the diagnostic performance of MRE for predicting the presence of varices or high‐risk varices (grade ≥II) was evaluated using the receiver‐operating characteristics (ROC) curves.

Results

The mean stiffness values of liver parenchyma measured on MRE were well correlated with the grade of esophageal varices (r = 0.63). In addition, the MRE‐based liver stiffness values were significantly lower in the lower‐risk group than in the higher‐risk group (P < 0.0001). The area under the ROC curve values of MRE for predicting the presence of varices or high‐risk varices (grade ≥II) were 0.859 and 0.810, respectively. Using a liver stiffness cutoff value of 5.803 kPa, the sensitivity, specificity, positive predictive value, and negative predictive value for predicting high‐grade (≥II) esophageal varices were 96%, 60%, 36%, and 98%, respectively.

Conclusion

The MRE‐based liver stiffness value may be useful for noninvasively predicting esophageal varices and identifying high‐risk varices in cirrhotic patients. J. Magn. Reson. Imaging 2014;39:559–566. © 2013 Wiley Periodicals, Inc.
Robust estimation of pulse wave transit time using group delay
Authors: Meloni Antonella , Zymeski Heather , Pepe Alessia , Lombardi Massimo , Wood John C.
Published: October 2013

Purpose

To evaluate the efficiency of a novel transit time (Δt) estimation method from cardiovascular magnetic resonance flow curves.

Materials and Methods

Flow curves were estimated from phase contrast images of 30 patients. Our method (TT‐GD: transit time group delay) operates in the frequency domain and models the ascending aortic waveform as an input passing through a discrete‐component “filter,” producing the observed descending aortic waveform. The GD of the filter represents the average time delay (Δt) across individual frequency bands of the input. This method was compared with two previously described time‐domain methods: TT‐point using the half‐maximum of the curves and TT‐wave using cross‐correlation. High temporal resolution flow images were studied at multiple downsampling rates to study the impact of differences in temporal resolution.

Results

Mean Δts obtained with the three methods were comparable. The TT‐GD method was the most robust to reduced temporal resolution. While the TT‐GD and the TT‐wave produced comparable results for velocity and flow waveforms, the TT‐point resulted in significant shorter Δts when calculated from velocity waveforms (difference: 1.8 ± 2.7 msec; coefficient of variability: 8.7%). The TT‐GD method was the most reproducible, with an intraobserver variability of 3.4% and an interobserver variability of 3.7%.

Conclusion

Compared to the traditional TT‐point and TT‐wave methods, the TT‐GD approach was more robust to the choice of temporal resolution, waveform type, and observer. J. Magn. Reson. Imaging 2014;39:550–558. © 2013 Wiley Periodicals, Inc.
Repetitive exposure of mice to strong static magnetic fields in utero does not impair fertility in adulthood but may affect placental weight of offspring
Authors: Zaun Gregor , Zahedi Yasmin , Maderwald Stefan , Orzada Stephan , Pütter Carolin , Scherag André , Winterhager Elke , Ladd Mark E. , Grümmer Ruth
Published: October 2013

Purpose

To investigate the effect of daily exposure in utero to static magnetic fields during prenatal development on germ cell development and fertility of exposed offspring in adulthood.

Materials and Methods

Mice were exposed daily in utero to different static magnetic field strengths at the bore entrance or in the isocenter of 1.5 T and 7 T MRI systems during the entire course of prenatal development.

Results

In utero‐exposed male mice revealed no effect of magnetic field strength on weight of testes and epididymis or on sperm count, sperm morphology, or fertility. Exposed pregnant female mice showed no reduced fertility in terms of pregnancy rates and litter size, pointing to a normal ovarian function. However, a reduced placental weight of offspring of intrauterine exposed female mice was observed that correlated with a decrease in embryonic weight in those animals exposed at the strongest magnetic field. This effect seemed to be parent‐dependent, since it was not observed in those embryos fathered by in utero‐exposed male mice.

Conclusion

Repetitive in utero exposure to strong static magnetic fields does not impair fertility but may have a parental‐dependent effect on fetal programming with regard to placental development and fetal growth. J. Magn. Reson. Imaging 2014;39:683–690. © 2013 Wiley Periodicals, Inc.
Registration of dynamic contrast‐enhanced MRI of the common carotid artery using a fixed‐frame template‐based squared‐difference method
Authors: Ramachandran Sarayu , Calcagno Claudia , Mani Venkatesh , Robson Philip M. , Fayad Zahi A.
Published: October 2013

Purpose

This study examines template‐based squared‐difference registration for motion correction in dynamic contrast‐enhanced (DCE) MRI studies of the carotid artery wall and compares the results of fixed‐frame template‐based registration with a previously proposed consecutive‐frame registration method.

Materials and Methods

Ten T1‐weighted black‐blood, turbo spin‐echo DCE‐MRI studies of the carotid artery wall were used to test template‐based squared‐difference registration. An intermediate image from each series was selected as the fixed‐frame template for registration. Squared‐difference minimization was used to align each image and template. Time‐intensity curves generated from data aligned with template‐based squared‐difference registration were compared with gold standard curves created by drawing regions of interest on each image in the series. The results were also compared with unregistered data and data after consecutive‐frame squared‐difference registration.

Results

An analysis of variance test of root mean‐square error values between gold standard curve and curves from unregistered data and data registered with consecutive‐frame and fixed‐frame template‐based methods was significant (P < 0.005) with template‐based squared‐difference registration producing curves that most closely matched the gold standard.

Conclusion

A fixed‐frame template‐based squared‐difference registration method was proposed and validated for alignment of DCE‐MRI of carotid arteries. J. Magn. Reson. Imaging 2014;39:1017–1017. © 2013 Wiley Periodicals, Inc.
Renal cell carcinoma in patients with acquired cystic disease of the kidney: Assessment using a combination of T2‐weighted, diffusion‐weighted, and chemical‐shift MRI without the use of contrast material
Authors: Akita Hirotaka , Jinzaki Masahiro , Akita Ayano , Mikami Shuji , Oya Mototsugu , Kuribayashi Sachio
Published: October 2013

Purpose

To evaluate the MRI findings of renal cell carcinoma (RCC), including findings on diffusion‐weighted images (DWIs) and chemical shift images (CSIs), in patients with acquired cystic disease of the kidney (ACDK) in relation to the histopathologic findings.

Materials and Methods

Two radiologists retrospectively reviewed the MRI findings of 10 RCCs in seven consecutive patients with ACDK. They evaluated the signal intensities (SIs) and signal homogeneity of the lesions on T2‐weighted images, DWIs, and T1‐weighted images. Thereafter, they evaluated the cytoplasmic fat in the lesions by CSIs. After image analyses, the MRI findings were correlated with the histopathologic findings.

Results

The RCCs tended to show heterogeneous high SIs on T2‐weighted images and DWIs. The high SIs on DWIs were mainly attributable to the viable parts, and the heterogeneity was due to the various SIs arising from the intratumoral degenerative components. Unlike the reported findings for hemorrhagic cysts, the RCCs did not show homogeneous high SIs or fluid‐iron levels on T1‐weighted images. The four lesions, in which the presence of cytoplasmic fat was suggested on CSIs, were clear cell RCCs.

Conclusion

The MRI findings, including findings on DWIs and CSIs, well reflected the histopathologic findings of RCC in patients with ACDK. J. Magn. Reson. Imaging 2014;39:924–930. © 2013 Wiley Periodicals, Inc.
Pulmonary 3 T MRI with ultrashort TEs: Influence of ultrashort echo time interval on pulmonary functional and clinical stage assessments of smokers
Authors: Ohno Yoshiharu , Nishio Mizuho , Koyama Hisanobu , Yoshikawa Takeshi , Matsumoto Sumiaki , Seki Shinichiro , Obara Makoto , van Cauteren Marc , Takahashi Masaya , Sugimura Kazuro
Published: October 2013

Purpose

To assess the influence of ultrashort TE (UTE) intervals on pulmonary magnetic resonance imaging (MRI) with UTEs (UTE‐MRI) for pulmonary functional loss assessment and clinical stage classification of smokers.

Materials and Methods

A total 60 consecutive smokers (43 men and 17 women; mean age 70 years) with and without COPD underwent thin‐section multidetector row computed tomography (MDCT), UTE‐MRI, and pulmonary functional measurements. For each smoker, UTE‐MRI was performed with three different UTE intervals (UTE‐MRI A: 0.5 msec, UTE‐MRI B: 1.0 msec, UTE‐MRI C: 1.5 msec). By using the GOLD guidelines, the subjects were classified as: “smokers without COPD,” “mild COPD,” “moderate COPD,” and “severe or very severe COPD.” Then the mean T2* value from each UTE‐MRI and CT‐based functional lung volume (FLV) were correlated with pulmonary function test. Finally, Fisher's PLSD test was used to evaluate differences in each index among the four clinical stages.

Results

Each index correlated significantly with pulmonary function test results (P < 0.05). CT‐based FLV and mean T2* values obtained from UTE‐MRI A and B showed significant differences among all groups except between “smokers without COPD” and “mild COPD” groups (P < 0.05).

Conclusion

UTE‐MRI has a potential for management of smokers and the UTE interval is suggested as an important parameter in this setting. J. Magn. Reson. Imaging 2014;39:988–997. © 2013 Wiley Periodicals, Inc.
T1 mapping in the rat myocardium at 7 tesla using a modified CINE inversion recovery sequence
Authors: Smit Henk , Guridi Ruben Pellicer , Guenoun Jamal , Poot Dirk H. J. , Doeswijk Gabriela N. , Milanesi Matteo , Bernsen Monique R. , Krestin Gabriel P. , Klein Stefan , Kotek Gyula
Published: October 2013

Purpose

To evaluate the reproducibility and sensitivity of the modified CINE inversion recovery (mCINE‐IR) acquisition on rats for measuring the myocardial T1 at 7 Tesla.

Materials and Methods

The recently published mCINE‐IR acquisition on humans was applied on rats for the first time, enabling the possibility of translational studies with an identical sequence. Simulations were used to study signal evolution and heart rate dependency. Gadolinium phantoms, a heart specimen and a healthy rat were used to study reproducibility. Two cryo‐infarcted rats were scanned to measure late gadolinium enhancement (LGE).

Results

In the phantom reproducibility studies the T1 measurements had a maximum coefficient of variation (COV) of 1.3%. For the in vivo reproducibility the COV was below 5% in the anterior cardiac segments. In simulations with phantoms and specimens, a heart rate dependency of approximately 0.5 ms/bpm was present. The T1 maps of the cryo‐infarcted rats showed a clear lowering of T1 in de LGE region.

Conclusion

The results show that mCINE‐IR is highly reproducible and that the sensitivity allows detecting T1 changes in the rat myocardium. J. Magn. Reson. Imaging 2014;39:901–910. © 2013 Wiley Periodicals, Inc.
Functional evaluation of transplanted kidneys using arterial spin labeling MRI
Authors: Heusch Philipp , Wittsack Hans‐Jörg , Blondin Dirk , Ljimani Alexandra , Nguyen‐Quang Michael , Martirosian Petros , Zenginli Hakan , Bilk Philip , Kröpil Patric , Heusner Till A. , Antoch Gerald , Lanzman Rotem S.
Published: October 2013

Purpose

To investigate non–contrast‐enhanced arterial spin labeling (ASL) MRI for functional assessment of transplanted kidneys at 1.5 Tesla (T) and 3T.

Materials and Methods

This study was approved by the local ethics committee, and written informed consent was obtained from all participants. Ninety eight renal allograft recipients (mean age, 51.5 ± 14.6 years) were prospectively included in this study. ASL MRI was performed at 1.5T (n = 65) and 3T (n = 33) using a single‐slice flow‐sensitive alternating inversion recovery true–fast imaging with steady‐state precession (FAIR True‐FISP) sequence in the paracoronal plane. ASL perfusion was regional analyzed for the renal cortex on parameter maps. ASL was compared between patients with good or moderate allograft function (Group a; estimated glomerular filtration rate [eGFR] > 30 mL/min/1.73 m2) and patients with heavily impaired allograft function (Group b; eGFR ≤ 30 mL/min/1.73 m2) and correlated to renal function as determined by eGFR.

Results

ASL perfusion and eGFR were comparable at 1.5T (246.9 ± 66.8 mL/100 g/min and 41.9 ± 22.7 mL/min/1.73 m2) and 3T (236.5 ± 102.3 mL/100 g/min and 35.9 ± 22.9 mL/min/1.73 m2). ASL perfusion was significantly higher in group a (282.7 ± 60.8 mL/100 g/min) as compared to group b (178.2 ± 63.3 mL/100 g/min) (P < 0.0001). ASL perfusion values exhibited a significant correlation with renal function as determined by eGFR (r = 0.59; P < 0.0001).

Conclusion

Cortical ASL perfusion values differ between patients with good or moderate allograft function and poor allograft function and correlate significantly with allograft function. Our results highlight the potential of ASL MRI for functional evaluation of renal allografts. J. Magn. Reson. Imaging 2014;40:84–89. © 2013 Wiley Periodicals, Inc.
Cerebral arterial and venous blood flow in adolescent multiple sclerosis patients and age‐matched controls using phase contrast MRI
Authors: Macgowan Christopher K. , Chan Katherine Y. , Laughlin Suzanne , Marrie Ruth Ann , Banwell Brenda
Published: October 2013

Purpose

Altered cerebrovascular blood flow has been proposed as a mechanism for multiple sclerosis (MS). The primary objective of this study was to measure arterial and venous blood flow in adolescent MS patients and healthy controls (HC), in whom confounding factors such as age and lifestyle are less influential.

Materials and Methods

Phase‐contrast magnetic resonance imaging (MRI) was used to measure flow in 26 MS patients and 26 controls aged 17.7 ± 1.8 and 17.8 ± 2.1 years, respectively. Flow was measured in the left and right internal carotid arteries (ICA), vertebral arteries (VA), internal jugular veins (IJV), and epidural veins (EV). Eighteen MS patients returned for a second MRI examination after 6 months. In all participants, ultrasound criteria for chronic cerebrospinal venous insufficiency (CCSVI) were also evaluated.

Results

Flows (mL/min) in the MS group versus HC group were as follows: right ICA = 262 ± 57 vs. 263 ± 32, left ICA = 260 ± 67 vs. 270 ± 36, right VA = 96 ± 50 vs. 103 ± 30, left VA = 104 ± 37 vs. 118 ± 41, right IJV = 342 ± 180 vs. 345 ± 195, left IJV = 190 ± 131 vs. 250 ± 148, right EV = 33 ± 29 vs. 48 ± 43, and left EV = 36 ± 35 vs. 44 ± 28 (P > 0.17 for all comparisons). In MS participants, a nonsignificant trend to lower flow in the left IJV was observed, and the flow pulsatility index in the epidural veins was higher. Two MS participants met ultrasound criteria for CCSVI, but no significant difference in flow was detected.

Conclusion

No population difference in flow rate was detected in adolescent MS participants relative to age‐matched controls. J. Magn. Reson. Imaging 2014;40:341–347. © 2013 Wiley Periodicals, Inc.