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1.
Ueli Studler MD Lawrence M. White MD Gustav Andreisek MD Sheena Luu BSc Hai‐Ling Margaret Cheng PhD Marshall S. Sussman PhD 《Journal of magnetic resonance imaging : JMRI》2010,32(2):394-398
Purpose:
To evaluate the impact of motion on T1 values acquired by using either inversion‐recovery fast spin echo (IR‐FSE) or three‐dimensional (3D) spoiled gradient recalled‐echo (SPGR) sequences for delayed gadolinium‐enhanced magnetic resonance imaging of cartilage (dGEMRIC) in volunteers.Materials and Methods:
Single‐slice IR‐FSE and 3D SPGR sequences were applied to perform dGEMRIC in five healthy volunteers. A mutual information‐based approach was used to correct for image misregistration. Displacements were expressed as averaged Euclidean distances and angles. Averages of differences in goodness of fit (Δχ2) tests and averages of relative differences in T1 values (ΔT1) before and after motion correction were computed.Results:
Maximum Euclidean distance was 3.5 mm and 1.2 mm for IR‐FSE and SPGR respectively. Mean ± SD of Δχ2 were 10.18 ± 8.4 for IR‐FSE and ?1.37 ± 5.5 for SPGR. Mean ± SD of ΔT1 were 0.008 ± 0.0048 for IR‐FSE and ?0.002 ± 0.019 for FSPGR. Pairwise comparison of Δχ2 values showed a significant difference for IR‐FSE, but not for 3D‐SPGR. Significantly greater variability in T1 values was also noted for IR‐FSE than for 3D‐SPGR.Conclusion:
Involuntary motion has a significant influence on T1 values acquired with IR‐FSE, but not with 3D‐SPGR in healthy volunteers. J. Magn. Reson. Imaging 2010;32:394–398. © 2010 Wiley‐Liss, Inc.2.
Stephan E. Domayer Siegfried Trattnig MD David Stelzeneder MD Clemens Hirschfeld Sebastian Quirbach MD Ronald Dorotka MD Stefan Nehrer MD Katja Pinker MD Jenny Chan BS Tallal Charles Mamisch MD Martin Dominkus MD Götz H. Welsch MD 《Journal of magnetic resonance imaging : JMRI》2010,31(3):732-739
Purpose:
To demonstrate the feasibility of delayed gadolinium‐enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC) in the ankle at 3 T and to obtain preliminary data on matrix associated autologous chondrocyte (MACI) repair tissue.Materials and Methods:
A 3D dual flip angle sequence was used with an eight‐channel multipurpose coil at 3 T to obtain T1 maps both pre‐ and postintravenous contrast agent (Magnevist, 0.2 mM/kg). Postcontrast T1 over time was evaluated in three volunteers; a modified dGEMRIC protocol was then used to assess 10 cases after MACI in the ankle.Results:
Forty‐five minutes were found sufficient for maximum T1 decrease. MACI cases had a precontrast mean T1 of 1050 ± 148.4 msec in reference cartilage (RC) and 1080 ± 165.6 msec in repair tissue (RT). Postcontrast T1 decreased to 590 ± 134.0 msec in RC and 554 ± 133.0 msec in RT. There was no significant difference between the delta relaxation rates in RT (9.44 × 10?4 s?1) and RC (8.04 × 10?4 s?1, P = 0.487). The mean relative delta relaxation rate was 1.34 ± 0.83.Conclusion:
It is feasible to assess the thin cartilage layers of the ankle with dGEMRIC at 3 T; MACI can yield RT with properties similar to articular cartilage. J. Magn. Reson. Imaging 2010;31:732–739. © 2010 Wiley‐Liss, Inc.3.
Philipp Heusch MD Hans‐Jörg Wittsack PhD Patric Kröpil MD Dirk Blondin MD Michael Quentin MD Janina Klasen MD Gael Pentang MSc Gerald Antoch MD Rotem S. Lanzman MD 《Journal of magnetic resonance imaging : JMRI》2013,37(1):233-236
Purpose:
To evaluate the impact of renal blood flow on apparent diffusion coefficients (ADC) and fractional anisotropy (FA) using time‐resolved electrocardiogram (ECG)‐triggered diffusion‐tensor imaging (DTI) of the human kidneys.Materials and Methods:
DTI was performed in eight healthy volunteers (mean age 29.1 ± 3.2) using a single slice coronal echoplanar imaging (EPI) sequence (3 b‐values: 0, 50, and 300 s/mm2) at the timepoint of minimum (20 msec after R wave) and maximum renal blood flow (200 msec after R wave) at 3T. Following 2D motion correction, region of interest (ROI)‐based analysis of cortical and medullary ADC‐ and FA‐values was performed.Results:
ADC‐values of the renal cortex at maximum blood flow (2.6 ± 0.19 × 10?3 mm2/s) were significantly higher than at minimum blood flow (2.2 ± 0.11 × 10?3 mm2/s) (P < 0.001), while medullary ADC‐values did not differ significantly (maximum blood flow: 2.2 ± 0.18 × 10?3 mm2/s; minimum blood flow: 2.15 ± 0.14 × 10?3 mm2/s). FA‐values of the renal medulla were significantly greater at maximal blood (0.53 ± 0.05) than at minimal blood flow (0.47 ± 0.05) (P < 0.01). In contrast, cortical FA‐values were comparable at different timepoints of the cardiac cycle.Conclusion:
ADC‐values in the renal cortex as well as FA‐values in the renal medulla are influenced by renal blood flow. This impact has to be considered when interpreting renal ADC‐ and FA‐values. J. Magn. Reson. Imaging 2013;37:233–236. © 2012 Wiley Periodicals, Inc.4.
Susan M. Noworolski PhD Galen D. Reed BS John Kurhanewicz PhD Daniel B. Vigneron PhD 《Journal of magnetic resonance imaging : JMRI》2010,32(3):654-662
Purpose:
To develop and validate a post‐processing correction algorithm to remove the effect of the inhomogeneous reception profile of the endorectal coil on MR spectroscopic imaging (MRSI) data.Materials and Methods:
A post‐processing algorithm to correct for the endorectal coil reception effects on MRSI data was developed based upon theoretical modeling of the endorectal coil reception profile and of the spatial saturation pulse profiles. This algorithm was evaluated on three‐dimensional (3D) MRSI data acquired at 3T from a uniform phantom and from 18 patients with known or suspected prostate cancer.Results:
For the phantom data, the coefficient of variation of metabolite peak areas decreased 16% to 46% and the peak area distributions became more Gaussian with correction, as demonstrated by higher Q‐Q plot linear correlations (R2 = 0.98 ± 0.007 vs. R2 = 0.89 ± 0.066). Across the 18 patients, the mean coefficient of variation for suppressed water decreased significantly, from 0.95 ± 0.18, to 0.66 ± 0.11, (P < 10?6, paired t‐test) and the linear correlations of the Q‐Q plots for the suppressed water increased from R2 = 0.91 to R2 = 0.95 (P = 0.0083, paired t‐test) with correction.Conclusion:
An algorithm for reducing the effect of the inhomogeneous reception profile in endorectal coil acquired 3D MRSI prostate data was demonstrated, illustrating increased homogeneity and more Gaussian peak area distributions. J. Magn. Reson. Imaging 2010;32:654–662. © 2010 Wiley‐Liss, Inc.5.
Lee SS Lee Y Kim N Kim SW Byun JH Park SH Lee MG Ha HK 《Journal of magnetic resonance imaging : JMRI》2011,33(6):1390-1398
Purpose:
To compare the accuracy of four chemical shift magnetic resonance imaging (MRI) (CS‐MRI) analysis methods and MR spectroscopy (MRS) with and without T2‐correction in fat quantification in the presence of excess iron.Materials and Methods:
CS‐MRI with six opposed‐ and in‐phase acquisitions and MRS with five‐echo acquisitions (TEs of 20, 30, 40, 50, 60 msec) were performed at 1.5 T on phantoms containing various fat fractions (FFs), on phantoms containing various iron concentrations, and in 18 patients with chronic liver disease. For CS‐MRI, FFs were estimated with the dual‐echo method, with two T2*‐correction methods (triple‐ and multiecho), and with multiinterference methods that corrected for both T2* and spectral interference effects. For MRS, FF was estimated without T2‐correction (single‐echo MRS) and with T2‐correction (multiecho MRS).Results:
In the phantoms, T2*‐ or T2‐correction methods for CS‐MRI and MRS provided unbiased estimations of FFs (mean bias, ?1.1% to 0.5%) regardless of iron concentration, whereas the dual‐echo method (?5.5% to ?8.4%) and single‐echo MRS (12.1% to 37.3%) resulted in large biases in FFs. In patients, the FFs estimated with triple‐echo (R = 0.98), multiecho (R = 0.99), and multiinterference (R = 0.99) methods had stronger correlations with multiecho MRS FFs than with the dual‐echo method (R = 0.86; P ≤ 0.011). The FFs estimated with multiinterference method showed the closest agreement with multiecho MRS FFs (the 95% limit‐of‐agreement, ?0.2 ± 1.1).Conclusion:
T2*‐ or T2‐correction methods are effective in correcting the confounding effects of iron, enabling an accurate fat quantification throughout a wide range of iron concentrations. Spectral modeling of fat may further improve the accuracy of CS‐MRI in fat quantification. J. Magn. Reson. Imaging 2011;33:1390–1398. © 2011 Wiley‐Liss, Inc.6.
Amir Eissa MSc R. Marc Lebel MSc Jeff R. Korzan MD Anna E. Zavodni MD Kenneth G. Warren MD Ingrid Catz MSc Derek J. Emery MD Alan H. Wilman PhD 《Journal of magnetic resonance imaging : JMRI》2009,30(4):737-742
Purpose
To demonstrate 4.7 Tesla (T) imaging methods for visualizing lesions in multiple sclerosis in the human brain using phase susceptibility‐weighting and T2 weighting.Materials and Methods
Seven patients with relapsing‐remitting multiple sclerosis were imaged at 4.7T using three‐dimensional (3D) susceptibility‐weighted imaging (SWI) with 0.90 mm3 voxel volumes, and with 2D T2‐weighted fast spin echo (T2WFSE) with 0.34 mm3 voxels and 1.84 mm3 voxels. The visibility of MS lesions at 4.7T with phase SWI and T2WFSE was assessed by independent lesion counts made by an experienced neuroradiologist, and by quantitative measures.Results
High resolution T2WFSE at 4.7T provided excellent depiction of hyperintense lesions. When combined with phase SWI, 124 total lesions were identified of which 18% were only visible on phase SWI and not on T2WFSE. The phase lesions had a mean phase shift relative to local background of ?11.15 ± 5.97 parts per billion.Conclusion
Imaging at 4.7T can provide both high quality, high resolution T2WFSE and SWI for visualization of lesions in multiple sclerosis. Phase susceptibility‐weighting can identify additional lesions that are not visible with high resolution T2WFSE. J. Magn. Reson. Imaging 2009;30:737–742. © 2009 Wiley‐Liss, Inc.7.
Hae‐Yeoun Lee Noel Codella Matthew Cham Martin Prince Jonathan Weinsaft Yi Wang 《Journal of magnetic resonance imaging : JMRI》2008,28(6):1393-1401
Purpose
To develop and evaluate an automated left ventricle (LV) segmentation algorithm using Graph searching based on Intensity and Gradient information and A priori knowledge (lvGIGA).Materials and Methods
The lvGIGA algorithm was implemented with coil sensitivity correction and polar coordinate transformation. Graph searching and expansion were applied for extracting myocardial endocardial and epicardial borders. LV blood and myocardium intensities were estimated for accurate partial volume calculation of blood volume and myocardial mass. Cardiac cine SSFP images were acquired from 38 patients. The lvGIGA algorithm was used to measure blood volume, myocardial mass, and ejection fraction, and compared with clinical manual tracing and the commercial MASS software.Results
The success rate for segmenting both endocardial and epicardial borders was 95.6% slices for lvGIGA and 37.8% for MASS (excluding basal slices that required manual enclosure of ventricle blood). The lvGIGA segmentation result agreed well with manual tracing, within ?2.9 ± 4.4 mL, 2.1 ± 2.2%, and ?9.6 ± 13.0 g, for blood volume, ejection fraction, and myocardial mass, respectively.Conclusion
The lvGIGA algorithm substantially improves the robustness of LV segmentation automation over the commercial MASS software, agrees well with clinical manual tracing, and may be a useful tool for clinical practice. J. Magn. Reson. Imaging 2008;28:1393–1401. © 2008 Wiley‐Liss, Inc.8.
Satoru Morita Naoko Saito Kazufumi Suzuki Norio Mitsuhashi 《Journal of magnetic resonance imaging : JMRI》2009,29(3):601-606
Purpose
To compare volume‐rendering (VR) and maximum‐intensity‐projection (MIP) of three‐dimensional T2‐weighted turbo spin‐echo magnetic resonance cholangiopancreatography using a free‐breathing navigator‐triggered prospective acquisition correction (3D‐TSE‐PACE‐MRCP) to define biliary anatomies.Materials and Methods
VR and MIP images of 3D‐TSE‐PACE‐MRCP for 102 patients were retrospectively evaluated. Interpretation of cystic duct variation and biliary branching patterns of each image were recorded independently by two radiologists in a blinded fashion. Interpretation confidence on a five‐point scale was compared using the Wilcoxon signed‐rank test. The McNemar test was used to compare the accuracies of each reformation with the reference standard obtained by consensus interpretation of both the images and source images.Results
The reference standard identified all biliary bifurcations and 95 of 102 cystic duct confluences (93.1%). VR findings agreed with the reference standard findings more often than MIP with regard to cystic duct variation (94 [92.2%] vs. 76 [74.5%], P < 0.01) while there was no significant difference for biliary branching patterns (99 [97.1%] vs. 92 [90.2%], P = 0.092). The mean confidence score was significantly higher with VR than MIP with regard to both cystic duct variation and biliary branching patterns (3.7 vs. 2.4; P < 0.01; 4.1 vs. 3.3; P < 0.01).Conclusion
VR reformation of 3D‐TSE‐PACE‐MRCP defines biliary anatomies more accurately than MIP. J. Magn. Reson. Imaging 2009;29:601–606. © 2009 Wiley‐Liss, Inc.9.
Arian Mashhood BS Radha Railkar PhD Takeshi Yokoo MD PhD Yakir Levin MD PhD Lisa Clark MPH PhD Sabrina Fox‐Bosetti BA Michael S. Middleton MD PhD Jonathan Riek PhD Eunkyung Kauh MD PhD Bernard J. Dardzinski PhD Donald Williams PhD Claude Sirlin MD Norah J. Shire PhD MPH 《Journal of magnetic resonance imaging : JMRI》2013,37(6):1359-1370
Purpose:
To evaluate the reproducibility of magnetic resonance imaging (MRI)‐determined hepatic fat fraction (%) across imaging sites with different magnet types and field strength. Reproducibility among MRI platforms is unclear, even though evaluating hepatic fat fractions (FFs) using MRI‐based methods is accurate against MR spectroscopy.Materials and Methods:
Overweight subjects were recruited to undergo eight MRI examinations at five imaging centers with a range of magnet manufacturers and field strengths (1.5 and 3 T). FFs were estimated in liver and in fat‐emulsion phantoms using three methods: 1) dual‐echo images without correction (nominally out‐of‐phase [OP] and in‐phase [IP]); 2) dual‐dual‐echo images (two sequences) with T2* correction (nominally OP/IP and IP/IP); and 3) six‐echo images with spectral model and T2* correction, at sequential alternating OP and IP echo times (Methods 1, 2, and 3, respectively).Results:
Ten subjects were recruited. For Methods 1, 2, and 3, respectively, hepatic FF ranged from ?2.5 to 27.0, 1.9 to 29.6, and 1.3 to 34.4%. Intraclass correlation coefficients were 0.85, 0.89, and 0.91 for each method, and within‐subject coefficients of variation were 18.5, 9.9, and 10.3%, respectively. Mean phantom FFs derived by Methods 2 and 3 were comparable to the known FF for each phantom. Method 1 underestimated phantom FF.Conclusion:
Methods 2 and 3 accurately assess FF. Strong reproducibility across magnet type and strength render them suitable for use in multicenter trials and longitudinal assessments. J. Magn. Reson. Imaging 2013;37:1359–1370. © 2012 Wiley Periodicals, Inc.10.
Purpose
To create diffusion tensor atlases from echo planar imaging (EPI) images acquired at 3 T in 10 normal subjects.Materials and Methods
Data from 10 right‐handed healthy adult volunteers (mean age of 31 ± 3 years; eight males) were acquired using a 3.0‐T scanner. Geometric distortion artifacts correction was accomplished by combining parallel acquisition to reduce the distortion as well as postprocessing by registration to a geometrically accurate T2‐weighted fast‐spin‐echo image. This reduced distortions to within a voxel for most of the internal structures of the brain. The apparent diffusion coefficient (ADC) and fractional anisotropy (FA) atlases were created by warping images using an iterative optical‐flow–based local deformation algorithm that used two channels of data: ADC and FA.Results
A three‐dimensional distance measure was used to evaluate the accuracy of the registration algorithm with contours defined on two structures: the corpus callosum and cerebellum. The average three‐dimensional distance value for the nine subjects (with the 10th as the reference) was 0.2 mm for the corpus callosum and 1.2 mm for the cerebellum.Conclusion
A high‐resolution, diffusion MR atlas with full brain coverage was developed. Additionally, maps of the SD of the diffusion indices were also generated to provide an estimate of the variance within a normal population. Active shape and texture models were also generated for the corpus callosum as an alternate method of representing the variance in morphology and diffusion indices. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.11.
Andrews-Shigaki BC Armstrong BS Zaitsev M Ernst T 《Journal of magnetic resonance imaging : JMRI》2011,33(2):498-504
Purpose:
To introduce and evaluate a method of prospective motion correction for localized proton magnetic resonance spectroscopy (1H‐MRS) using a single‐camera optical tracking system.Materials and Methods:
Five healthy participants were scanned at 3T using a point‐resolved spectroscopic sequence (PRESS) with a motion‐tracking module and phase navigator. Head motion in six degrees was tracked with a Retro‐Grate Reflector (RGR) tracking system and target via a mirror mounted inside the bore. Participants performed a series of three predetermined motion patterns during scanning.Results:
Left–right rotation (Rz) (average 12°) resulted in an increase in the total choline to total creatine ratio (Cho/Cr) of +14.6 ± 1.5% (P = 0.0009) for scans without correction, but no change for scans with correction (+1.1 ± 1.5%; P = 0.76). Spectra with uncorrected Z‐translations showed large lipid peaks (skull) with changes in Cho/Cr of ?13.2 ± 1.6% (P = 0.02, no motion correction) and ?2.2 ± 2.4% (P = 0.51) with correction enabled. There were no significant changes in the ratios of N‐acetylaspartate, glutamate+glutamine, or myo‐inositol to creatine compared to baseline scans for all experiments.Conclusion:
Prospective motion correction for 1H‐MRS, using single‐camera RGR tracking, can reduce spectral artifacts and quantitation errors in Cho/Cr ratios due to head motion and promises improved spectral quality and reproducibility. J. Magn. Reson. Imaging 2011. © 2011 Wiley‐Liss, Inc.12.
Seong‐Eun Kim PhD Eun‐Kee Jeong PhD Xian‐Feng Shi MS Glen Morrell MD PhD Gerald S. Treiman MD Dennis L. Parker PhD 《Journal of magnetic resonance imaging : JMRI》2009,30(5):1068-1077
Purpose:
To determine if 2D single‐shot interleaved multislice inner volume diffusion‐weighted echo planar imaging (ss‐IMIV‐DWEPI) can be used to obtain quantitative diffusion measurements that can assist in the identification of plaque components in the cervical carotid artery.Materials and Methods:
The 2D ss‐DWEPI sequence was combined with interleaved multislice inner volume region localization to obtain diffusion weighted images with 1 mm in‐plane resolution and 2 mm slice thickness. Eleven subjects, six of whom have carotid plaque, were studied with this technique. The apparent diffusion coefficient (ADC) images were calculated using DW images with b = 10 s/mm2 and b = 300 s/mm2.Results:
The mean ADC measurement in normal vessel wall of the 11 subjects was 1.28 ± 0.09 × 10?3 mm2/s. Six of the 11 subjects had carotid plaque and ADC measurements in plaque ranged from 0.29 to 0.87 × 10?3 mm2/s. Of the 11 common carotid artery walls studied (33 images), at least partial visualization of the wall was obtained in all ADC images, more than 50% visualization in 82% (27/33 images), and full visualization in 18% (6/33 images).Conclusion:
2D ss‐IMIV‐DWEPI can perform diffusion‐weighted carotid magnetic resonance imaging (MRI) in vivo with reasonably high spatial resolution (1 × 1 × 2 mm3). ADC values of the carotid wall and plaque are consistent with similar values obtained from ex vivo endarterectomy specimens. The spread in ADC values obtained from plaque indicate that this technique could form a basis for plaque component identification in conjunction with other MRI/MRA techniques. J. Magn. Reson. Imaging 2009;30:1068–1077. © 2009 Wiley‐Liss, Inc.13.
Goergen CJ Barr KN Huynh DT Eastham-Anderson JR Choi G Hedehus M Dalman RL Connolly AJ Taylor CA Tsao PS Greve JM 《Journal of magnetic resonance imaging : JMRI》2010,32(4):847-858
Purpose
To develop methods to quantify cyclic strain, motion, and curvature of the murine abdominal aorta in vivo.Materials and Methods
C57BL/6J and apoE?/? mice underwent three‐dimensional (3D) time‐of‐flight MR angiography to position cardiac‐gated 2D slices at four locations along the abdominal aorta where circumferential cyclic strain and lumen centroid motion were calculated. From the 3D data, a centerline through the aorta was created to quantify geometric curvature at 0.1‐mm intervals. Medial elastin content was quantified with histology postmortem. The location and shape of abdominal aortic aneurysms (AAAs), created from angiotensin II infusion, were evaluated qualitatively.Results
Strain waveforms were similar at all locations and between groups. Centroid motion was significantly larger and more leftward above the renal vessels than below (P < 0.05). Maximum geometric curvature occurred slightly proximal to the right renal artery. Elastin content was similar around the circumference of the vessel. AAAs developed in the same location as the maximum curvature and grew in the same direction as vessel curvature and motion.Conclusion
The methods presented provide temporally and spatially resolved data quantifying murine aortic motion and curvature in vivo. This noninvasive methodology will allow serial quantification of how these parameters influence the location and direction of AAA growth. J. Magn. Reson. Imaging 2010;32:847–858. © 2010 Wiley‐Liss, Inc.14.
Karla Hopp MSc Bogdan F.Gh. Popescu MD PhD Richard P.E. McCrea BSc Sheri L. Harder MD Christopher A. Robinson MD Mark E. Haacke PhD Ali H. Rajput MBBS Alex Rajput MD Helen Nichol PhD 《Journal of magnetic resonance imaging : JMRI》2010,31(6):1346-1354
Purpose:
To test the ability of susceptibility weighted images (SWI) and high pass filtered phase images to localize and quantify brain iron.Materials and Methods:
Magnetic resonance (MR) images of human cadaver brain hemispheres were collected using a gradient echo based SWI sequence at 1.5T. For X‐ray fluorescence (XRF) mapping, each brain was cut to obtain slices that reasonably matched the MR images and iron was mapped at the iron K‐edge at 50 or 100 μm resolution. Iron was quantified using XRF calibration foils. Phase and iron XRF were averaged within anatomic regions of one slice, chosen for its range of iron concentrations and nearly perfect anatomic correspondence. X‐ray absorption spectroscopy (XAS) was used to determine if the chemical form of iron was different in regions with poorer correspondence between iron and phase.Results:
Iron XRF maps, SWI, and high pass filtered phase data in nine brain slices from five subjects were visually very similar, particularly in high iron regions. The chemical form of iron could not explain poor matches. The correlation between the concentration of iron and phase in the cadaver brain was estimated as cFe [μg/g tissue] = 850Δ? + 110.Conclusion:
The phase shift Δ? was found to vary linearly with iron concentration with the best correspondence found in regions with high iron content. J. Magn. Reson. Imaging 2010;31:1346–1354. © 2010 Wiley‐Liss, Inc.15.
Jing Liu PhD Oliver Wieben PhD Youngkyoo Jung PhD Alexey A. Samsonov PhD Scott B. Reeder MD PhD Walter F. Block PhD 《Journal of magnetic resonance imaging : JMRI》2010,32(2):434-440
Purpose:
To achieve single breathhold whole heart cardiac CINE imaging with improved spatial resolution and temporal resolution by using a multi‐echo three‐dimensional (3D) hybrid radial SSFP acquisition.Materials and Methods:
Multi‐echo 3D hybrid radial SSFP acquisitions were used to acquire cardiac CINE imaging within a single breathhold. An optimized interleaving scheme was developed for view ordering throughout the cardiac cycle.Results:
Whole heart short axis views were acquired with a spatial resolution of 1.3 × 1.3 × 8.0 mm3 and temporal resolution of 45 ms, within a single 17 s breathhold. The technique was validated on eight healthy volunteers by measuring the left ventricular volume throughout the cardiac cycle and comparing with the conventional 2D multiple breathhold technique. The left ventricle functional measurement bias of our proposed 3D technique from the conventional 2D technique: end diastolic volume ?3.3 mL ± 13.7 mL, end systolic volume 1.4 mL ± 6.1 mL, and ejection fraction ?1.7% ± 4.3%, with high correlations 0.94, 0.97, and 0.91, accordingly.Conclusion:
A multi‐echo 3D hybrid radial SSFP acquisition was developed to allow for a whole heart cardiac CINE exam in a single breathhold. Cardiac function measurements in volunteers compared favorably with the standard multiple breathhold exams. J. Magn. Reson. Imaging 2010;32:434–440. © 2010 Wiley‐Liss, Inc.16.
Kazuhiro Saito MD Joseph Ledsam BSc Steven Sourbron PhD Jun Otaka MD Yoichi Araki RT Soichi Akata MD Koichi Tokuuye MD 《Journal of magnetic resonance imaging : JMRI》2013,37(5):1109-1114
Purpose:
To evaluate liver function obtained by tracer‐kinetic modeling of dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI) data acquired with a routine gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd‐EOB‐DTPA)‐enhanced protocol.Materials and Methods:
Data were acquired from 25 cases of nonchronic liver disease and 94 cases of cirrhosis. DCE‐MRI was performed with a dose of 0.025 mmol/kg Gd‐EOB‐DTPA injected at 2 mL/sec. A 3D breath‐hold sequence acquired 5 volumes of 72 slices each: precontrast, double arterial phase, portal phase, and 4‐minute postcontrast. Regions of interest (ROIs) were selected semiautomatically in the aorta, portal vein, and whole liver on a middle slice. A constrained dual‐inlet two‐compartment uptake model was fitted to the ROI curves, producing three parameters: intracellular uptake rate (UR), extracellular volume (Ve), and arterial flow fraction (AFF).Results:
Median UR dropped from 4.46 10?2 min?1 in the noncirrhosis to 3.20 in Child–Pugh A (P = 0.001), and again to 1.92 in Child–Pugh B (P < 0.0001). Median Ve dropped from 6.64 mL 100 mL?1 in the noncirrhosis to 5.80 in Child–Pugh A (P = 0.01). Other combinations of Ve and AFF changes were not significant for any group.Conclusion:
UR obtained from tracer kinetic analysis of a routine DCE‐MRI has the potential to become a novel index of liver function. J. Magn. Reson. Imaging 2013;37:1109–1114. © 2012 Wiley Periodicals, Inc.17.
Kartik S. Sundareswaran MS David H. Frakes PhD Mark A. Fogel MD Dennis D. Soerensen MS John N. Oshinski PhD Ajit P. Yoganathan PhD 《Journal of magnetic resonance imaging : JMRI》2009,29(1):155-165
Purpose
To develop and validate a multidimensional segmentation and filtering methodology for accurate blood flow velocity field reconstruction from phase‐contrast magnetic resonance imaging (PC MRI).Materials and Methods
The proposed technique consists of two steps: (1) the boundary of the vessel is automatically segmented using the active contour approach; and (2) the noise embedded within the segmented vector field is selectively removed using a novel fuzzy adaptive vector median filtering (FAVMF) technique. This two‐step segmentation process was tested and validated on 111 synthetically generated PC MRI slices and on 10 patients with congenital heart disease.Results
The active contour technique was effective for segmenting blood vessels having a sensitivity and specificity of 93.1% and 92.1% using manual segmentation as a reference standard. FAVMF was the superior technique in filtering out noise vectors, when compared with other commonly used filters in PC MRI (P < 0.05). The peak wall shear rate calculated from the PC MRI data (248 ± 39 sec?1), was significantly decreased to (146 ± 26 sec?1) after the filtering process.Conclusion
The proposed two‐step segmentation and filtering methodology is more accurate compared to a single‐step segmentation process for post‐processing of PC MRI data. J. Magn. Reson. Imaging 2009;29:155–165. © 2008 Wiley‐Liss, Inc.18.
Francesca Schiavone MSc Rebecca Ann Charlton PhD Thomas Richard Barrick PhD Robin Guy Morris PhD Hugh Stephen Markus DM FRCP 《Journal of magnetic resonance imaging : JMRI》2009,29(1):23-30
Purpose
To determine which MR technique was the most sensitive to age‐related white matter damage. We compared both diffusion tensor imaging (DTI) and magnetization transfer (MT) maps to determine which technique correlated most strongly with cognitive function in a middle‐aged and elderly community population.Materials and Methods
In all, 64 healthy subjects (aged 50–90) underwent MRI and neuropsychology. Histograms were generated for white matter mean diffusivity (MD), fractional anisotropy (FA), and MT ratio (MTR). White matter hyperintensity volume (WMH) and brain volume were also determined. Composite neuropsychological scores were derived for 4 cognitive domains (executive function, working memory, episodic memory, and information processing speed).Results
All MRI parameters correlated with age (FA r = 0.726, P < 0.001; MD r = ?0.619 P < 0.001, MTR r = ?0.566, P < 0.001, WMH r = 0.511, P < 0.001). All MRI parameters correlated with cognition, but DTI, and particularly FA, correlated most strongly. Adding DTI parameters explained more variance in cognition than WMH alone; the increase was greatest with FA, which alone explained 45%, 33%, and 25% of the variance in cognition for information processing speed, episodic memory, and executive function, respectively.Conclusion
DTI appears the most sensitive imaging parameter to determine age‐related white matter damage. The stronger relationship with FA suggests that axonal damage is important in age‐related cognitive decline. J. Magn. Reson. Imaging 2009;29:23–30. © 2008 Wiley‐Liss, Inc.19.
Wei Feng Xiong MD Shi Jun Qiu PhD Hong Zhuo Wang MD Xiao Fei Lv MD 《Journal of magnetic resonance imaging : JMRI》2013,37(1):101-108
Purpose:
To detect radiation‐induced changes of temporal lobe normal‐appearing white mater (NAWM) following radiation therapy (RT) for nasopharyngeal carcinoma (NPC).Materials and Methods:
Seventy‐five H1‐MR spectroscopy and diffusion‐tensor imaging (DTI) examinations were performed in 55 patients before and after receiving fractionated radiation therapy (total dose; 66–75GY). We divided the dataset into six groups, a pre‐RT control group and five other groups based on time after completion of RT. N‐acetylaspartic acid (NAA)/choline (Cho), NAA/creatine (Cr), Cho/Cr, mean diffusibility (MD), functional anisotropy (FA), radial diffusibility (λ?), and axial diffusibility (λ||) were calculated.Results:
NAA/Cho and NAA/Cr decreased and λ? increased significantly within 1 year after RT compared with pre‐RT. After 1 year, NAA/Cho, NAA/Cr, and λ? were not significantly different from pre‐RT. In all post‐RT groups, FA decreased significantly. λ|| decreased within 9 months after RT compared with pre‐RT, but was not significantly different from pre‐RT more than 9 months after RT.Conclusion:
DTI and H1‐MR spectroscopy can be used to detect early radiation‐induced changes of temporal lobe NAWM following radiation therapy for NPC. Metabolic alterations and water diffusion characteristics of temporal lobe NAWM in patients with NPC after RT were dynamic and transient. J. Magn. Reson. Imaging 2013;37:101–108. © 2012 Wiley Periodicals, Inc.20.
Thrippleton MJ Bastin ME Munro KI Williams AR Oniscu A Jansen MA Merrifield GD McKillop G Newby DE Semple SI Marshall I Critchley HO 《Journal of magnetic resonance imaging : JMRI》2011,34(6):1445-1451