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Selected AbstractsErratum: J. Basic Microbiol.JOURNAL OF BASIC MICROBIOLOGY, Issue 4 20094/200 As came to our knowledge, the evidence for a new spiroketal produced by Aspergillus niger isolated from an opuntia by Wu et al. (Journal of Basic Microbiology 2008, 48 (2008), 140,142; DOI 10.1002/jobm.200700363) does not preclude identity with a previously published compound from Aspergillus niger, terrineol (Macedo Jr., F.C. et al., Tetrahedron Lett., 45 (2004), 53, and Macedo Jr., F.C. et al., Magn. Reson. Chem., 43 (2005), 251). The authors failed to discuss this possibility (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Role of neuroimaging in promoting long-term recovery from ischemic strokeJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2010Rüdiger J. Seitz MD Abstract Human ischemic stroke is an acute disorder followed by a recovery period which may be of varying duration and mechanism. Imaging has created a means to explore the stroke process in vivo, particularly its underlying pathophysiology and recovery mechanisms. Evidence from multicenter studies has shown that, in the acute phase, arterial recanalization and reperfusion of ischemic brain tissue are the most important determinants of recovery. This is followed by functional and structural changes in the perilesional tissue and in large-scale bihemispheric networks that continue with different dynamics for weeks to months. Proof-of-principle studies have revealed that the behavioral gains induced by rehabilitation are paralleled by changes in functional representations. This is supported by data from neuroimaging and electrophysiological studies early after stroke which have shown that dedicated training can induce changes in cerebral functional representations. Accordingly, there is clear evidence that neuroimaging has a significant potential for monitoring the hemodynamic, functional, and structural factors determining recovery from stroke. New imaging methods may provide relevant biomarkers for treatment decisions and therapeutic monitoring. By combining neuroimaging with electrophysiological measures, opportunities exist to develop neuroscience-based strategies in rehabilitation. J. Magn. Reson. Imaging 2010;32:756,772. © 2010 Wiley-Liss, Inc. [source] Magnetic resonance imaging near metal implantsJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2010K.M. Koch PhD Abstract The desire to apply magnetic resonance imaging (MRI) techniques in the vicinity of embedded metallic hardware is increasing. The soft-tissue contrast available with MR techniques is advantageous in diagnosing complications near an increasing variety of MR-safe metallic hardware. Near such hardware, the spatial encoding mechanisms utilized in conventional MRI methods are often severely compromised. Mitigating these encoding difficulties has been the focus of numerous research investigations over the past two decades. Such approaches include view-angle tilting, short echo-time projection reconstruction acquisitions, single-point imaging, prepolarized MRI, and postprocessing image correction. Various technical advances have also enabled the recent development of two alternative approaches that have shown promising clinical potential. Here, the physical principals and proposed solutions to the problem of MRI near embedded metal are discussed. J. Magn. Reson. Imaging 2010;32:773,787. © 2010 Wiley-Liss, Inc. [source] Percent infarct mapping for delayed contrast enhancement magnetic resonance imaging to quantify myocardial viability by Gd(DTPA)JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2010Tamás Simor MD Abstract Purpose To demonstrate the advantages of signal intensity percent-infarct-mapping (SI-PIM) using the standard delayed enhancement (DE) acquisition in assessing viability following myocardial infarction (MI). SI-PIM quantifies MI density with a voxel-by-voxel resolution in clinically used DE images. Materials and Methods In canines (n= 6), 96 hours after reperfused MI and administration of 0.2 mmol/kg Gd(DTPA), ex vivo DE images were acquired and SI-PIMs calculated. SI-PIM data were compared with data from DE images analyzed with several thresholding levels using SIremote+2SD, SIremote+6SD, SI full width half maximum (SIFWHM), and with triphenyl-tetrazolium-chloride (TTC) staining. SI-PIM was also compared to R1 percent infarct mapping (R1-PIM). Results Left ventricular infarct volumes (IV) in DE images, IVSIremote+2SD and IVSIremote+6SD, overestimated (P < 0.05) TTC by medians of 13.21 mL [10.2; 15.2] and 6.2 mL [3.79; 8.23], respectively. SIFWHM, SI-PIM, and R1-PIM, however, only nonsignificantly underestimated TTC, by medians of ,0.10 mL [,0.12, ,0.06], ,0.86 mL [,1.04; 1.54], and ,1.30 mL [,4.99; ,0.29], respectively. The infarct-involved voxel volume (IIVV) of SI-PIM, 32.4 mL [21.2, 46.3] is higher (P < 0.01) than IIVVs of SIFWHM 8.3 mL [3.79, 19.0]. SI-PIMFWHM, however, underestimates TTC (,5.74 mL [,11.89; ,2.52] (P < 0.01)). Thus, SI-PIM outperforms SIFWHM because larger IIVVs are obtained, and thus PIs both in the rim and the core of the infarcted tissue are characterized, in contradistinction from DE-SIFWHM, which shows mainly the infarct core. Conclusion We have shown here, ex vivo, that SI-PIM has the same advantages as R1-PIM, but it is based on the scanning sequences of DE imaging, and thus it is obtainable within the same short scanning time as DE. This makes it a practical method for clinical studies. J. Magn. Reson. Imaging 2010;32:859,868. © 2010 Wiley-Liss, Inc. [source] Comparison of segmentation methods for MRI measurement of cardiac function in ratsJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2010Johannes Riegler MSc Abstract Purpose To establish the accuracy, intra- and inter-observer variabilities of four different segmentation methods for measuring cardiac functional parameters in healthy and infarcted rat hearts. Materials and Methods Six Wistar rats were imaged before and after myocardial infarction using an electrocardiogram and respiratory-gated spoiled gradient echo sequence. Blinded and randomized datasets were analyzed by various semi-automatic and manual segmentation methods to compare their measurement bias and variability. In addition, the accuracy of these methods was assessed by comparison with reference measurements acquired from high-resolution three-dimensional (3D) datasets of a heart phantom. Results Relative inter- and intra-observer variability were found to be similar for all four methods. Semi-automatic segmentation methods reduced analysis time by up to 70%, while yielding similar measurement bias and variability compared with manual segmentation. Semi-automatic methods were found to underestimate the ejection fraction for healthy hearts compared with manual segmentation while overestimating them in infarcted hearts. However, semi-automatic segmentation of short axis slices agreed better with 3D reference scans of a heart phantom compared with manual segmentation. Conclusion Semi-automatic segmentation methods are faster than manual segmentation, while offering a similar intra- and inter-observer variability. However, a potential bias has been observed between healthy and infarcted hearts for different methods, which should also be considered when selecting the most appropriate analysis technique. J. Magn. Reson. Imaging 2010;32:869,877. © 2010 Wiley-Liss, Inc. [source] Fat-water separation in dynamic objects using an UNFOLD-like temporal processingJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2010Riad Ababneh PhD Abstract Purpose To separate fat and water signals in dynamic imaging. Because important features may be embedded in fat, and because fat may take part in disease processes, separating fat and water signals may be of great importance in a number of clinical applications. This work aims to achieve such separation at nearly no loss in temporal resolution compared to usual, nonseparated acquisitions. In contrast, the well-known 3-point Dixon method may cause as much as a 3-fold reduction in temporal resolution. Materials and Methods The proposed approach involves modulating the echo time TE from frame to frame, to force fat signals to behave in a conspicuous manner through time, so they can be readily identified and separated from water signals. The strategy is inspired from the "unaliasing by Fourier encoding the overlaps in the temporal direction" (UNFOLD) method, although UNFOLD involves changes in the sampling function rather than TE, and aims at suppressing aliased material rather than fat. Results The method was implemented at 1.5 T and 3 T, on cardiac cine and multiframe steady-state free precession sequences. In addition to phantom results, in vivo results from volunteers are presented. Conclusion Good separation of fat and water signals was achieved in all cases. J. Magn. Reson. Imaging 2010;32:962,970. © 2010 Wiley-Liss, Inc. [source] 3 Tesla and 7 Tesla MRI of multiple sclerosis cortical lesionsJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2010Emma C. Tallantyre BM Abstract Cortical lesions are prevalent in multiple sclerosis but are poorly detected using MRI. The double inversion recovery (DIR) sequence is increasingly used to explore the clinical relevance of cortical demyelination. Here we evaluate the agreement between imaging sequences at 3 Tesla (T) and 7T for the presence and appearance of individual multiple sclerosis cortical lesions. Eleven patients with demyelinating disease and eight healthy volunteers underwent MR imaging at 3T (fluid attenuated inversion recovery [FLAIR], DIR, and T1 -weighted magnetization prepared rapid acquisition gradient echo [MP-RAGE] sequences) and 7T (T1 -weighted MP-RAGE). There was good agreement between images for the presence of mixed cortical lesions (involving both gray and white matter). However, agreement between imaging sequences was less good for purely intracortical lesions. Even after retrospective analysis, 25% of cortical lesions could only be visualized on a single MRI sequence. Several DIR hyperintensities thought to represent cortical lesions were found to correspond to signal arising from extracortical blood vessels. High-resolution 7T imaging appeared useful for confidently classifying the location of lesions in relation to the cortical/subcortical boundary. We conclude that DIR, FLAIR, and MP-RAGE imaging sequences appear to provide complementary information during the detection of multiple sclerosis cortical lesions. High resolution 7T imaging may facilitate anatomical localization of lesions in relation to the cortical boundary. J. Magn. Reson. Imaging 2010;32:971,977. © 2010 Wiley-Liss, Inc. [source] Imaging biomarkers of cardiovascular diseaseJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 3 2010Jinnan Wang PhD Abstract Cardiovascular disease (CVD) is a leading cause of morbidity and mortality worldwide. Current clinical techniques that rely on stenosis measurement alone appear to be insufficient for risk prediction in atherosclerosis patients. Many novel imaging methods have been developed to study atherosclerosis progression and to identify new features that can predict future clinical risk. MRI of atherosclerotic vessel walls is one such method. It has the ability to noninvasively evaluate multiple biomarkers of the disease such as luminal stenosis, plaque burden, tissue composition and plaque activity. In addition, the accuracy of in vivo MRI has been validated against histology with high reproducibility, thus paving the way for application to epidemiological studies of disease pathogenesis and, by serial MRI, in monitoring the efficacy of therapeutic intervention. In this review, we describe the various MR techniques used to evaluate aspects of plaque progression, discuss imaging-based measurements (imaging biomarkers), and also detail their validation. The application of plaque MRI in clinical trials as well as emerging imaging techniques used to evaluate plaque compositional features and biological activities are also discussed. J. Magn. Reson. Imaging 2010;32:502,515. © 2010 Wiley-Liss, Inc. [source] Negative predictive value of normal adenosine-stress cardiac MRI in the assessment of coronary artery disease and correlation with semiquantitative perfusion analysisJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 3 2010Guenter Pilz MD Abstract Purpose: To prospectively determine the negative predictive value of normal adenosine stress cardiac MR (CMR) in routine patients referred for evaluation of coronary artery disease (CAD), predominantly with intermediate to high pretest risk. Materials and Methods: Consecutive patients referred for coronary angiography were examined in a 1.5 Tesla whole-body scanner before catheterization. A total of 158 patients with normal CMR on qualitative assessment were included, and semiquantitative perfusion analysis was performed. Significant CAD was regarded as luminal narrowing of ,70% in coronary angiography. Results: In the 158 study patients, negative predictive value of normal adenosine-stress CMR for significant CAD was 96.2% (for stenosis ,90%: 98.1%). True-negative and false-negative patients were comparable regarding clinical presentation, risk factors, and CMR findings. Semiquantitative perfusion analysis gave significantly prolonged arrival time index and peak time index in the false-negative group. Using cutoff values >1.8 for arrival time index or >1.2 for peak time index, the CMR negative predictive value increased to 98.7% (for stenosis ,90%: to 100%). Conclusion: The very high negative predictive value for CAD supports CMR-based decision making for the indication to coronary angiography. Semiquantitative perfusion analysis seems promising to identify the small group of CAD patients not detectable by qualitative CMR assessment. J. Magn. Reson. Imaging 2010;32:615,621. © 2010 Wiley-Liss, Inc. [source] Multiple-bolus dynamic contrast-enhanced MRI in the pancreas during a glucose challengeJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 3 2010J.H. Naish PhD Abstract Purpose: To assess the feasibility of multiple-bolus dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) in the pancreas; to optimize the analysis; and to investigate application of the method to a glucose challenge in type 2 diabetes. Materials and Methods: A 4-bolus DCE-MRI protocol was performed on five patients with type 2 diabetes and 11 healthy volunteers during free-breathing. Motion during the dynamic time series was corrected for using a model-driven nonlinear registration. A glucose challenge was administered intravenously between the first and second DCE-MRI acquisition in all patients and in seven of the healthy controls. Results: Image registration improved the reproducibility of the DCE-MRI model parameters across the repeated bolus-acquisitions in the healthy controls with no glucose challenge (eg, coefficient of variation for Ktrans improved from 38% to 28%). Native tissue T1 was significantly lower in patients (374 ± 68 msec) compared with volunteers (519 ± 41 msec) but there was no significant difference in any of the baseline DCE-MRI parameters. No effect of glucose challenge was observed in either the patients or healthy volunteers. Conclusion: Multiple bolus DCE-MRI is feasible in the pancreas and is improved by nonlinear image registration but is not sensitive to the effects of an intravenous glucose challenge. J. Magn. Reson. Imaging 2010;32:622,628. © 2010 Wiley-Liss, Inc. [source] Sealed-off spontaneous perforation of a pyometra diagnosed preoperatively by magnetic resonance imaging: A case reportJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 3 2010Jonghyun Kim MD Abstract : Spontaneous perforation is a very rare complication of pyometra. The clinical findings of perforated pyometra usually mimic perforation of the gastrointestinal tract. In most cases a correct diagnosis can be made only by laparotomy. In our case, the patient's pyometra was sealed and she complained only of mild abdominal pain and showed no signs of peritonitis. Ultrasonography and computed tomography (CT) findings were not suggestive of uterine rupture. However, T2-weighted magnetic resonance imaging (MRI) demonstrated a full thickness defect of the myometrium. We discuss the CT and MRI findings that confirmed a correct diagnosis of perforated pyometra. J. Magn. Reson. Imaging 2010;32:697,699. © 2010 Wiley-Liss, Inc. [source] Use of time resolved magnetic resonance imaging in the diagnosis of pelvic congestion syndromeJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 3 2010Tarun Pandey MD Abstract We describe the efficacy of time-resolved MR angiography in diagnosing a case of pelvic congestion syndrome (PCS). MR angiography, using four-dimensional (4D) TRAK (Time-Resolved Angiography using Keyhole) technique was used in an 81-year-old woman presenting with low backache, pelvic pain, and left pelvic fullness. Dynamic images were obtained in multiple vascular phases including arterial, arteriovenous, and venous phases. The high temporal resolution of 4D TRAK could demonstrate early retrograde left ovarian vein filling as well as multiple dilated pelvic varices, allowing the prospective diagnosis of PCS to be made. Although uncommon in this age group, the diagnosis was subsequently confirmed on conventional catheter venography with symptomatic relief after successful embolization of the incompetent left ovarian vein. The MRA and correlative catheter venography images are presented in this case report. J. Magn. Reson. Imaging 2010;32:700,704. © 2010 Wiley-Liss, Inc. [source] Ultrafast imaging: Principles, pitfalls, solutions, and applicationsJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2010Jeffrey Tsao PhD Abstract Ultrafast MRI refers to efficient scan techniques that use a high percentage of the scan time for data acquisition. Often, they are used to achieve short scan duration ranging from sub-second to several seconds. Alternatively, they may form basic components of longer scans that may be more robust or have higher image quality. Several important applications use ultrafast imaging, including real-time dynamic imaging, myocardial perfusion imaging, high-resolution coronary imaging, functional neuroimaging, diffusion imaging, and whole-body scanning. Over the years, echo-planar imaging (EPI) and spiral imaging have been the main ultrafast techniques, and they will be the focus of the review. In practice, there are important challenges with these techniques, as it is easy to push imaging speed too far, resulting in images of a nondiagnostic quality. Thus, it is important to understand and balance the trade-off between speed and image quality. The purpose of this review is to describe how ultrafast imaging works, the potential pitfalls, current solutions to overcome the challenges, and the key applications. J. Magn. Reson. Imaging 2010;32:252,266. © 2010 Wiley-Liss, Inc. [source] Can MR fluoroscopic triggering technique and slow rate injection provide appropriate arterial phase images with reducing artifacts on gadoxetic acid-DTPA (Gd-EOB-DTPA)-enhanced hepatic MR imaging?JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2010Hiroki Haradome MD Abstract Purpose: To evaluate whether using MR fluoroscopic triggering technique and slow rate injection improves the quality of arterial phase images in gadoxetic acid-DTPA-enhanced (Gd-EOB-DTPA) MR imaging because of proper acquisition timing and reduction of artifacts. Materials and Methods: Two hundred sixteen patients undergoing examination for liver diseases were retrospectively reviewed. All MR images were obtained with two Gd-EOB-DTPA injection protocols: (i) a combination protocol, in which the MR fluoroscopic triggering technique and slow rate injection (1 mL/s) were used; and for comparison, (ii) a conventional protocol, in which adjusted fixed scan delay and ordinary rate injection (2 mL/s) were adopted. Signal-to-noise ratio (SNR) of aorta, portal vein, and liver parenchyma on arterial phase images were calculated. Two blinded readers independently evaluated the obtained arterial phase images in terms of acquisition timing and degree of artifacts. Results: The SNRs of aorta and portal vein on arterial phase images were significantly higher in the combination protocol group (aorta/portal: 221.9 ± 91.9/197.1 ± 89.8) than that in the conventional protocol group (aorta/portal: 169.8 ± 97.4/92.7 ± 48.5) (P < 0.05). The acquisition timing for arterial phase images with the combination protocol was significantly better than that with the conventional protocol (P < 0.01). The image quality of the combination protocol was significantly higher than that of the conventional protocol (P < 0.01). The occurrence rate of moderate or severe degree of artifacts in the conventional protocol (38.0%) was more prominent than that in the combination protocol (18.5%). Conclusion: The combination of the MR fluoroscopic triggering technique and slow rate injection provides proper arterial phase images and reduces the artifacts in Gd-EOB-DTPA MR imaging. J. Magn. Reson. Imaging 2010;32:334,340. © 2010 Wiley-Liss, Inc. [source] Focal nodular hyperplasia: Central scar enhancement pattern using gadoxetate disodiumJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2010Adib R. Karam MD Abstract Purpose: To illustrate the unusual enhancement pattern of the focal nodular hyperplasia central scar using Gadoxetate Disodium. Materials and Methods: Over a 10-month period, six patients, with a total of seven focal nodular hyperplasia lesions with typical central scar, had MRI of the liver using Gadoxetate Disodium (Eovist, Bayer HealthCare Pharmaceuticals Inc., Wayne, NJ). Four of the six patients had a prior Gadobenate Dimeglumine (Multihance, Bracco Diagnostics Inc., Princeton, NJ) -enhanced MRI of the liver performed within the previous year. The dynamic enhancement pattern of the central scar on the 10 liver MRIs was independently analyzed by two abdominal imaging radiologists who were blinded to the contrast agent used. Results: On the Gadoxetate Disodium-enhanced MRIs and during the arterial phase, 1-min, 2-min, and 3-min delay, none of the central scars demonstrated enhancement. However, all four of the lesions that were previously scanned using Gadobenate Dimeglumine demonstrated typical enhancement after a 3-min delay. Conclusion: On Gadoxetate Disodium-enhanced MRIs of the liver, the central scar of focal nodular hyperplasia lesions does not typically demonstrate delayed enhancement. J. Magn. Reson. Imaging 2010;32:341,344. © 2010 Wiley-Liss, Inc. [source] 3D flow-independent peripheral vessel wall imaging using T2 -prepared phase-sensitive inversion-recovery steady-state free precessionJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2010Jingsi Xie BS Abstract Purpose: To develop a 3D flow-independent peripheral vessel wall imaging method using T2 -prepared phase-sensitive inversion-recovery (T2PSIR) steady-state free precession (SSFP). Materials and Methods: A 3D T2 -prepared and nonselective inversion-recovery SSFP sequence was designed to achieve flow-independent blood suppression for vessel wall imaging based on T1 and T2 properties of the vessel wall and blood. To maximize image contrast and reduce its dependence on the inversion time (TI), phase-sensitive reconstruction was used to restore the true signal difference between vessel wall and blood. The feasibility of this technique for peripheral artery wall imaging was tested in 13 healthy subjects. Image signal-to-noise ratio (SNR), wall/lumen contrast-to-noise ratio (CNR), and scan efficiency were compared between this technique and conventional 2D double inversion recovery , turbo spin echo (DIR-TSE) in eight subjects. Results: 3D T2PSIR SSFP provided more efficient data acquisition (32 slices and 64 mm in 4 minutes, 7.5 seconds per slice) than 2D DIR-TSE (2,3 minutes per slice). SNR of the vessel wall and CNR between vessel wall and lumen were significantly increased as compared to those of DIR-TSE (P < 0.001). Vessel wall and lumen areas of the two techniques are strongly correlated (intraclass correlation coefficients: 0.975 and 0.937, respectively; P < 0.001 for both). The lumen area of T2PSIR SSFP is slightly larger than that of DIR-TSE (P = 0.008). The difference in vessel wall area between the two techniques is not statistically significant. Conclusion: T2PSIR SSFP is a promising technique for peripheral vessel wall imaging. It provides excellent blood signal suppression and vessel wall/lumen contrast. It can cover a 3D volume efficiently and is flow- and TI-independent. J. Magn. Reson. Imaging 2010;32:399,408. © 2010 Wiley-Liss, Inc. [source] Diffusion-weighted MRI for monitoring tumor response to photodynamic therapyJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2010Hesheng Wang MS Abstract Purpose: To examine diffusion-weighted MRI (DW-MRI) for assessing the early tumor response to photodynamic therapy (PDT). Materials and Methods: Subcutaneous tumor xenografts of human prostate cancer cells (CWR22) were initiated in athymic nude mice. A second-generation photosensitizer, Pc 4, was delivered to each animal by a tail vein injection 48 h before laser illumination. A dedicated high-field (9.4 Tesla) small animal MR scanner was used to acquire diffusion-weighted MR images pre-PDT and 24 h after the treatment. DW-MRI and apparent diffusion coefficients (ADC) were analyzed for 24 treated and 5 control mice with photosensitizer only or laser light only. Tumor size, prostate specific antigen (PSA) level, and tumor histology were obtained at different time points to examine the treatment effect. Results: Treated mice showed significant tumor size shrinkage and decrease of PSA level within 7 days after the treatment. The average ADC of the 24 treated tumors increased 24 h after PDT (P < 0.001) comparing with pre-PDT. The average ADC was 0.511 ± 0.119 × 10,3 mm2/s pre-PDT and 0.754 ± 0.181 × 10,3 mm2/s 24 h after the PDT. There is no significant difference in ADC values pre-PDT and 24 h after PDT in the control tumors (P = 0.20). Conclusion: The change of tumor ADC values measured by DW-MRI may provide a noninvasive imaging marker for monitoring tumor response to Pc 4-PDT as early as 24 h. J. Magn. Reson. Imaging 2010;32:409,417. © 2010 Wiley-Liss, Inc. [source] Two- and three-dimensional multinuclear stray-field imaging of rotating samples with magic-angle spinning (STRAFI-MAS): From bio to inorganic materialsJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2010Alan Wong PhD Abstract Purpose: To revisit and illustrate the potential of a simple and effective multidimensional stray-field imaging technique with magic-angle spinning, known as STRAFI-MAS. Materials and Methods: STRAFI-MAS images are acquired with a standard NMR magnet and a traditional magic-angle sample spinning (MAS) probe. The stray-field gradients are achieved by placing the MAS probe, along the z -direction, at a distance from the center of the magnet. No pulsed-field gradients are applied. The multidimensional spatial encoding is carried out by synchronizing the radiofrequency pulses with the sample MAS rotation. Results: Two-dimensional (2D) and 3D multinuclear images of various phantoms, including a tibia bone and silicon carbide, are recorded. Images of inorganic solids containing quadrupolar nuclei, 23Na and 27Al, are also explored for the first time by STRAFI-MAS. Conclusion: We have demonstrated that STRAFI-MAS is a simple and user-friendly technique for multidimensional imaging without the need of imaging equipment. With the current advancements in NMR and MRI methodologies, STRAFI-MAS is expected to be further developed and improved. We anticipate that STRAFI-MAS can spark a wide spectrum of interest, from material to bio science, where can benefit from high-resolution images. J. Magn. Reson. Imaging 2010;32:418,423. © 2010 Wiley-Liss, Inc. [source] MR-based visualization and quantification of three-dimensional flow characteristics in the portal venous systemJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2010Zoran Stankovic MD Abstract Purpose: To evaluate the feasibility of time-resolved flow-sensitive MRI for the three-dimensional (3D) visualization and quantification of normal and pathological portal venous (PV) hemodynamics. Materials and Methods: Portal venous hemodynamics were evaluated in 18 healthy volunteers and 5 patients with liver cirrhosis. ECG- and adaptive respiratory navigator gated flow-sensitive 4D MRI (time-resolved 3D MRI with three-directional velocity encoding) was performed on a 3 Tesla MR system (TRIO, Siemens, Germany). Qualitative flow analysis was achieved using 3D streamlines and time-resolved particle traces originating from seven emitter planes precisely placed at anatomical landmarks in the PV system. Quantitative analysis included retrospective extraction of regional peak and mean velocities and vessel area. Results were compared with standard 2D flow-sensitive MRI and to the reference standard Doppler ultrasound. Results: Qualitative flow analysis was successfully used in the entire PV system. Venous hemodynamics in all major branches in 17 of 18 volunteers and 3 of 5 patients were reliably depicted with good interobserver agreement (kappa = 0.62). Quantitative analysis revealed no significant differences and moderate agreement for peak velocities between 3D MR and 2D MRI (r = 0.46) and Doppler ultrasound (US) (r = 0.35) and for mean velocities between 3D and 2D MRI (r = 0.41). The PV area was significantly (P < 0.01) higher in 3D and 2D MRI compared with US. Conclusion: We successfully applied 3D MR velocity mapping in the PV system, providing a detailed qualitative and quantitative analysis of normal and pathological hemodynamics. J. Magn. Reson. Imaging 2010;32:466,475. © 2010 Wiley-Liss, Inc. [source] Improved homogeneity of the transmit field by simultaneous transmission with phased array and volume coilJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2010Nikolai I. Avdievich PhD Abstract Purpose: To improve the homogeneity of transmit volume coils at high magnetic fields (,4 T). Due to radiofrequency (RF) field/tissue interactions at high fields, 4 T to 8 T, the transmit profile from head-sized volume coils shows a distinctive pattern with relatively strong RF magnetic field B1 in the center of the brain. Materials and Methods: In contrast to conventional volume coils at high field strengths, surface coil phased arrays can provide increased RF field strength peripherally. In theory, simultaneous transmission from these two devices could produce a more homogeneous transmission field. To minimize interactions between the phased array and the volume coil, counter rotating current (CRC) surface coils consisting of two parallel rings carrying opposite currents were used for the phased array. Results: Numerical simulations and experimental data demonstrate that substantial improvements in transmit field homogeneity can be obtained. Conclusion: We have demonstrated the feasibility of using simultaneous transmission with human head-sized volume coils and CRC phased arrays to improve homogeneity of the transmit RF B1 field for high-field MRI systems. J. Magn. Reson. Imaging 2010;32:476,481. © 2010 Wiley-Liss, Inc. [source] Ground truth hardware phantoms for validation of diffusion-weighted MRI applicationsJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2010Pim Pullens MSc Abstract Purpose: To quantitatively validate diffusion-weighted MRI (DW-MRI) applications, a hardware phantom containing crossing fibers at a sub-voxel level is presented. It is suitable for validation of a large spectrum of DW-MRI applications from acquisition to fiber tracking, which is an important recurrent issue in the field. Materials and Methods: Phantom properties were optimized to resemble properties of human white matter in terms of anisotropy, fractional anisotropy, and T2. Sub-voxel crossings were constructed at angles of 30, 50, and 65 degrees, by wrapping polyester fibers, with a diameter close to axon diameter, into heat shrink tubes. We show our phantoms are suitable for the acquisition of DW-MRI data using a clinical protocol. Results: The phantoms can be used to succesfully estimate both the diffusion tensor and non-Gaussian diffusion models, and perform streamline fiber tracking. DOT (Diffusion Orientation Transform) and q-ball reconstruction of the diffusion profiles acquired at b = 3000 s/mm2 and 132 diffusion directions reveal multimodal diffusion profiles in voxels containing crossing yarn strands. Conclusion: The highly purpose adaptable phantoms provide a DW-MRI validation platform: applications include optimisation of acquisition schemes, validation of non-Gaussian diffusion models, comparison and validation of fiber tracking algorithms, and quality control in multi-center DWI studies. J. Magn. Reson. Imaging 2010;32:482,488. © 2010 Wiley-Liss, Inc. [source] Predicting and monitoring cancer treatment response with diffusion-weighted MRIJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 1 2010Harriet C. Thoeny MD Abstract An imaging biomarker that would provide for an early quantitative metric of clinical treatment response in cancer patients would provide for a paradigm shift in cancer care. Currently, nonimage based clinical outcome metrics include morphology, clinical, and laboratory parameters, however, these are obtained relatively late following treatment. Diffusion-weighted MRI (DW-MRI) holds promise for use as a cancer treatment response biomarker as it is sensitive to macromolecular and microstructural changes which can occur at the cellular level earlier than anatomical changes during therapy. Studies have shown that successful treatment of many tumor types can be detected using DW-MRI as an early increase in the apparent diffusion coefficient (ADC) values. Additionally, low pretreatment ADC values of various tumors are often predictive of better outcome. These capabilities, once validated, could provide for an important opportunity to individualize therapy thereby minimizing unnecessary systemic toxicity associated with ineffective therapies with the additional advantage of improving overall patient health care and associated costs. In this report, we provide a brief technical overview of DW-MRI acquisition protocols, quantitative image analysis approaches and review studies which have implemented DW-MRI for the purpose of early prediction of cancer treatment response. J. Magn. Reson. Imaging 2010. © 2010 Wiley-Liss, Inc. [source] Comparison of dual to single contrast bolus magnetic resonance myocardial perfusion imaging for detection of significant coronary artery diseaseJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 1 2010Jan G.J. Groothuis MD Abstract Purpose: To investigate the incremental diagnostic value of dual-bolus over single-contrast-bolus first pass magnetic resonance myocardial perfusion imaging (MR-MPI) for detection of significant coronary artery disease (CAD). Materials and Methods: Patients (n = 49) with suspected CAD underwent first pass adenosine stress and rest MR-MPI and invasive coronary angiography (CA). Gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) was injected with a prebolus (1 mL) and a large bolus (0.1 mmol/kg). For the single-bolus technique, the arterial input function (AIF) was obtained from the large-contrast bolus. For the dual-bolus technique, the AIF was reconstructed from the prebolus. Absolute myocardial perfusion was calculated by Fermi-model constrained deconvolution. Receiver operating characteristic (ROC) analysis was used to investigate diagnostic accuracy of MR myocardial perfusion imaging for detection of significant CAD on CA at vessel-based analysis. Results: The area under the curve (AUC) of the minimal stress perfusion value for the detection of significant CAD using the single-bolus and dual-bolus technique was 0.85 ± 0.04 (95% confidence interval [CI], 0.77,0.93) and 0.77 ± 0.05 (95% CI, 0.67,0.86), respectively. Conclusion: In this study the dual-bolus technique had no incremental diagnostic value over single-bolus technique for detection of significant CAD with the used contrast concentrations. J. Magn. Reson. Imaging 2010;32:88,93. © 2010 Wiley-Liss, Inc. [source] Morphological features and clinical feasibility of thoracic duct: Detection with nonenhanced magnetic resonance imaging at 3.0 TJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 1 2010Yu De-xin MD Abstract Purpose: To evaluate the detection of the thoracic duct using nonenhanced magnetic resonance imaging (MRI) and to determine the influence of some related disorders on the lymphatic duct. Materials and Methods: Highly fluid-sensitive sequence and fat-suppressed T2-weighted imaging (FS-T2WI) were performed in a total of 139 cases. The axial and coronal images were used to locate the thoracic duct and the measurement and evaluation of its dimensions were performed using a 3D maximum intensity projection (MIP) reconstruction image. The differences in the dimensions among control, portal hypertension, and common bile duct obstruction groups were compared using one-way analysis of variance. Results: The cisterna chyli was shown in 91% of cases on FS-T2WI, while the thoracic duct appeared in 70% of the MIP images. The common configuration of the cisterna chyli was tubular or saccular in 73%. Eighty thoracic ducts had a slight turn declining to the left at the level of T8,10. There was a significant difference in the transverse diameter of the thoracic duct between the portal hypertension group and other groups (F = 5.638, P = 0.005). Conclusion: Nonenhanced MRI is feasible for locating and depicting the morphological features of the thoracic duct. Portal hypertension may influence the dimension of the thoracic duct. J. Magn. Reson. Imaging 2010;32:94,100. © 2010 Wiley-Liss, Inc. [source] In vivo vascular hallmarks of diffuse leukoaraiosisJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 1 2010Jinsoo Uh PhD Abstract Purpose: To characterize multiple patterns of vascular changes in leukoaraiosis using in vivo magnetic resonance imaging (MRI) techniques. Materials and Methods: We measured cerebral blood flow (CBF), cerebrovascular reactivity (CVR), and blood,brain-barrier (BBB) leakage in a group of 33 elderly subjects (age: 72.3 ± 6.8 years, 17 males, 16 females). Leukoaraiosis brain regions were identified in each subject using fluid-attenuated inversion-recovery (FLAIR) MRI. Vascular parameters in the leukoaraiosis regions were compared to those in the normal-appearing white matter (NAWM) regions. Vascular changes in leukoaraiosis were also compared to structural damage as assessed by diffusion tensor imaging. Results: CBF and CVR in leukoaraiosis regions were found to be 39.7 ± 5.2% (P < 0.001) and 52.5 ± 11.6% (P = 0.005), respectively, of those in NAWM. In subjects who did not have significant leukoaraiosis, CBF and CVR in regions with high risk for leukoaraiosis showed a slight reduction compared to the other white matter regions. Significant BBB leakage was also detected (P = 0.003) in leukoaraiosis and the extent of BBB leakage was positively correlated with mean diffusivity. In addition, CVR in NAWM was lower than that in white matter of subjects without significant leukoaraiosis. Conclusion: Leukoaraiosis was characterized by reduced CBF, CVR, and a leakage in the BBB. J. Magn. Reson. Imaging 2010;32:184,190. © 2010 Wiley-Liss, Inc. [source] Reproducibility of black blood dynamic contrast-enhanced magnetic resonance imaging in aortic plaques of atherosclerotic rabbitsJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 1 2010Claudia Calcagno MD Abstract Purpose: To investigate the short-term reproducibility of black-blood dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) in atherosclerotic rabbits to evaluate the potential of this technique to be a reliable readout of plaque progression and/or regression upon therapeutic intervention. Materials and Methods: Atherosclerotic rabbits were imaged at baseline and 24 hours later with DCE-MRI on a 1.5T MRI system. DCE-MRI images were analyzed by calculating the area under the signal intensity versus time curve (AUC). Intraclass correlation coefficients (ICCs) were used to evaluate interscan, intraobserver, and interobserver reproducibility. In addition, the test,retest coefficient of variation (CoV) was evaluated. Results: Statistical analyses showed excellent interscan, intraobserver, and interobserver agreement. All ICCs were greater than 0.75, P < 0.01 indicating excellent agreement between measurements. Conclusion: Experimental results show good interscan and excellent intra- and interobserver reproducibility, suggesting that DCE-MRI could be used in preclinical settings as a read-out for novel therapeutic interventions for atherosclerosis. This preliminary work encourages investigating the reproducibility of DCE-MRI also in clinical settings, where it could be used for monitoring high-risk patients and in longitudinal clinical drug trials. J. Magn. Reson. Imaging 2010;32:191,198. © 2010 Wiley-Liss, Inc. [source] Pain related to rotator cuff abnormalities: MRI findings without clinical significanceJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 6 2010Jenny T. Bencardino MD Abstract MRI has become an important diagnostic tool in the evaluation of rotator cuff pathology and the technology continues to evolve. Direct MR arthrography, diagnosis-specific sequencing such as fat suppression, special positioning such as abducted externally rotated (ABER) views and ultra high field magnets allow for an unprecedented level of detail in imaging. In this article, we review MRI findings in patients with rotator cuff abnormalities that are anatomic variants or incidental findings. Although MRI findings may be diagnostic in some cases, we find that clinical correlation with history and physical examination is critical to differentiate between anatomic variants, incidental findings, and true pathology. We conclude that good communication between the orthopedic surgeon and the radiologist is necessary to optimize diagnostic yield. J. Magn. Reson. Imaging 2010;31:1286,1299. © 2010 Wiley-Liss, Inc. [source] Pharmacokinetic mapping for lesion classification in dynamic breast MRIJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 6 2010Matthias C. Schabel PhD Abstract Purpose: To prospectively investigate whether a rapid dynamic MRI protocol, in conjunction with pharmacokinetic modeling, could provide diagnostically useful information for discriminating biopsy-proven benign lesions from malignancies. Materials and Methods: Patients referred to breast biopsy based on suspicious screening findings were eligible. After anatomic imaging, patients were scanned using a dynamic protocol with complete bilateral breast coverage. Maps of pharmacokinetic parameters representing transfer constant (Ktrans), efflux rate constant (kep), blood plasma volume fraction (vp), and extracellular extravascular volume fraction (ve) were averaged over lesions and used, with biopsy results, to generate receiver operating characteristic curves for linear classifiers using one, two, or three parameters. Results: Biopsy and imaging results were obtained from 93 lesions in 74 of 78 study patients. Classification based on Ktrans and kep gave the greatest accuracy, with an area under the receiver operating characteristic curve of 0.915, sensitivity of 91%, and specificity of 85%, compared with values of 88% and 68%, respectively, obtained in a recent study of clinical breast MRI in a similar patient population. Conclusion: Pharmacokinetic classification of breast lesions is practical on modern MRI hardware and provides significant accuracy for identification of malignancies. Sensitivity of a two-parameter linear classifier is comparable to that reported in a recent multicenter study of clinical breast MRI, while specificity is significantly higher. J. Magn. Reson. Imaging 2010;31:1371,1378. © 2010 Wiley-Liss, Inc. [source] Quantification of superparamagnetic iron oxide-mediated signal intensity change in patients with liver cirrhosis using T2 and T2* mapping: A preliminary reportJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 6 2010Yong Eun Chung MD Abstract Purpose: To quantify the accumulation of superparamagnetic iron oxide (SPIO) in patients with and without liver cirrhosis using T2 and T2* mapping. Materials and Methods: We enrolled 10 patients without liver cirrhosis and 30 patients with liver cirrhosis (Child-Pugh class A, n = 18; and B/C, n = 12). T2 and T2* mapping were performed before and after SPIO administration. The reductions in T2 (,T2) and T2* (,T2*) after SPIO administration were compared between the control and liver cirrhosis groups and the control, Child-Pugh A, and Child Pugh B/C groups. Results: There were significant differences in ,T2 (22.2 ± 4.4 and 15.1 ± 7.0) and ,T2* values (24.3 ± 3.3 and 16.8 ± 8.1) (P = 0.005 and P < 0.001) between the control and the liver cirrhosis groups. There was a significant difference in the ,T2* between the Child-Pugh A and Child-Pugh B/C groups (P < 0.001) and in the ,T2 and ,T2* between the control and Child-Pugh B/C groups (P = 0.018 and P < 0.001). Conclusion: ,T2 and ,T2* are significantly larger in patients without liver cirrhosis than those with liver cirrhosis. ,T2* is also significantly larger in Child-Pugh class A patients than those in Child-Pugh B/C. J. Magn. Reson. Imaging 2010;31:1379,1386. © 2010 Wiley-Liss, Inc. [source] Eccentric target sign in cerebral toxoplasmosis: Neuropathological correlate to the imaging feature,JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 6 2010G.G. Sharath Kumar MD Abstract Cerebral toxoplasmosis remains one of the most common focal brain lesions in patients with acquired immune deficiency syndrome (AIDS). Diagnosis is a challenge because on cranial imaging it closely mimics central nervous system lymphoma, primary and metastatic central nervous system (CNS) tumors, or other intracranial infections like tuberculoma or abscesses. A magnetic resonance imaging (MRI) feature on postcontrast T1-weighted sequences considered pathognomonic of toxoplasmosis is the "eccentric target sign." The pathological correlate of this imaging sign has been speculative. Herein we correlate the underlying histopathology to the MR feature of eccentric target sign in a patient with autopsy-proven HIV/AIDS-related cerebral toxoplasmosis. The central enhancing core of the target seen on MRI was produced by a leash of inflamed vessels extending down the length of the sulcus that was surrounded by concentric zones of necrosis and a wall composed of histiocytes and proliferating blood vessels, with impaired permeability producing the peripheral enhancing rim. J. Magn. Reson. Imaging 2010;31:1469,1472. © 2010 Wiley-Liss, Inc. [source] | |||||||||||||