bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of region‐of‐interest analysis with three different histogram analysis methods in the determination of perfusion metrics in patients with brain gliomas
Authors: Young Robert , Babb James , Law Meng , Pollack Erica , Johnson Glyn 
Published: September 2007

AbstractPurposeTo compare routine ROI analysis and three different histogram analyses in the grading of glial neoplasms. The hypothesis is that histogram methods can provide a robust and objective technique for quantifying perfusion data in brain gliomas. Current region‐of‐interest (ROI)‐based methods for the analysis of dynamic susceptibility contrast perfusion magnetic resonance imaging (DSC MRI) data are operator‐dependent.Materials and MethodsA total of 92 patients underwent conventional and DSC MRI. Multiple histogram metrics were obtained for cerebral blood flow (CBF), cerebral blood volume (CBV), and relative CBV (rCBV) maps using tumoral (T), peritumoral (P), and total tumoral (TT) analysis. Results were compared to histopathologic grades. Statistical analysis included Mann‐Whitney (MW) tests, Spearman rank correlation coefficients, logistic regression, and McNemar tests.ResultsThe maximum value of rCBV (rCBVmax) showed highly significant correlation with glioma grade (r = 0.734, P < 0.001). The strongest histogram correlations (P < 0.0001) occurred with rCBVT SD (r = 0.718), rCBVP SD25 (r = 0.724) and rCBVTT SD50 (r = 0.685). Multiple rCBVT, rCBVP, and rCBVTT histogram metrics showed significant correlations. CBF and CBV histogram metrics were less strongly correlated with glioma grade than rCBV histogram metrics.ConclusionHistogram analysis of perfusion MR provides prediction of glioma grade, with peritumoral metrics outperforming tumoral and total tumoral metrics. Further refinement may lead to automated methods for perfusion data analysis. J. Magn. Reson. Imaging 2007;26:1053–1063. © 2007 Wiley‐Liss, Inc.
Quantification of physiological and hemodynamic indices using T1 dynamic contrast‐enhanced MRI in intracranial mass lesions
Authors: Singh Anup , Haris Mohammad , Rathore Divya , Purwar Ankur , Sarma Manoj , Bayu Getaneh , Husain Nuzhat , Rathore Ram K. Singh , Gupta Rakesh K. 
Published: September 2007

AbstractPurposeTo estimate precontrast tissue parameter (T10) using fast spin echo (FSE) and to quantify physiological and hemodynamic parameters with leakage correction using T1‐weighted dynamic contrast‐enhanced (DCE) perfusion imaging.Materials and MethodsVoxel‐wise T10 computation was performed followed by the analysis of T1‐weighted DCE perfusion data for the conversion of signal intensity time curve to concentration time curve, estimation of hemodynamic and physiological perfusion indices, and a method for leakage correction. Validations of accuracy of the computations have also been carried out.ResultsThe computed T10 and hemodynamic perfusion indices in normal white and gray matter were in good agreement with the literature values. Physiological perfusion indices in these regions were found negligible, validating computations. Cerebral blood volume (CBV) values change negligibly over the length of concentration time curve in white matter, gray matter, and lesion (CBVcorrected), while CBVuncorrected (lesion) shows linear increase over time.ConclusionT1‐weighted DCE perfusion data along with FSE‐based T1 estimation can be used for an accurate estimation of hemodynamic and physiological perfusion indices. J. Magn. Reson. Imaging 2007;26:871–880. © 2007 Wiley‐Liss, Inc.
Least‐squares chemical shift separation for 13C metabolic imaging
Authors: Reeder Scott B. , Brittain Jean H. , Grist Thomas M. , Yen Yi‐Fen 
Published: September 2007

AbstractPurposeTo describe a new least‐squares chemical shift (LSCSI) method for separation of chemical species with widely spaced peaks in a sparse spectrum. The ability to account for species with multiple peaks is addressed.Materials and MethodsThis method is applied to imaging of 13C‐labeled pyruvate and its metabolites alanine, pyruvate, and lactate. The method relies on a priori knowledge of the resonant frequencies of the different chemical species, as well as the relative signal from the two pyruvate peaks, one of which lies near the alanine peak. With this information a least‐squares method was utilized for separation of signal from the three metabolites, facilitating tremendous reductions in the amount of data required to decompose the different chemical species. Optimization of echo spacing for maximum noise performance of the signal separation is also described.ResultsImaging an enriched 13C phantom at 3.0T, the LSCSI method demonstrates excellent metabolite separation, very similar to echo planar spectroscopic imaging (EPSI), while only using 1/16th as much data.ConclusionThis approach may be advantageous for in vivo hyperpolarized 13C metabolic applications for reduced scan time compared with EPSI. J. Magn. Reson. Imaging 2007;26:1145–1152. © 2007 Wiley‐Liss, Inc.
Three‐dimensional delayed gadolinium‐enhanced MRI of cartilage (dGEMRIC) for in vivo evaluation of reparative cartilage after matrix‐associated autologous chondrocyte transplantation at 3.0T: Preliminary results
Authors: Trattnig Siegfried , Marlovits Stefan , Gebetsroither Simone , Szomolanyi Pavol , Welsch Goetz H. , Salomonowitz Erich , Watanabe Atsuya , Deimling Michael , Mamisch Tallal Charles 
Published: September 2007

AbstractPurposeTo use a 3D gradient‐echo (GRE) sequence with two flip angles for delayed gadolinium‐enhanced MRI of cartilage (dGEMRIC) to evaluate relative glycosaminoglycan content of repair tissue after matrix‐associated autologous chondrocyte transplantation (MACT).Materials and MethodsIn a phantom study, T1‐mapping based on a 3D‐GRE sequence with different flip angle combinations was compared with a standard inversion recovery (IR) sequence at 3.0T. Fifteen patients were examined after MACT in the knee at “3–13 months” (group I) and “19–42 months” (group II). The δ relaxation rate (δR1) calculated for repair tissue and normal hyaline cartilage was measured and mean values were compared in different postoperative intervals using analysis of variance.ResultsThe flip angle combination 35/10° provided the best agreement with IR sequence for short and long T1 values. The mean δR1 for repair tissue was 2.49 versus 1.04 at the intact control site in group I and 1.90 compared with 0.81 in group II. Differences from repair tissue to control sites showed statistically significance for both groups; no significant difference was found between groups.ConclusionThe 3D dual flip angle dGEMRIC technique optimized for cartilage imaging is comparable to standard T1 IR technique for T1 mapping. Furthermore, the preliminary in vivo study demonstrates the feasibility of the technique in the evaluation of MACT patients. J. Magn. Reson. Imaging 2007;26:974–982. © 2007 Wiley‐Liss, Inc.
Absolute quantification of cerebral blood flow in normal volunteers: Correlation between Xe‐133 SPECT and dynamic susceptibility contrast MRI
Authors: Knutsson Linda , Börjesson Siv , Larsson Elna‐Marie , Risberg Jarl , Gustafson Lars , Passant Ulla , Ståhlberg Freddy , Wirestam Ronnie 
Published: September 2007

AbstractPurposeTo compare absolute cerebral blood flow (CBF) estimates obtained by dynamic susceptibility contrast MRI (DSC‐MRI) and Xe‐133 SPECT.Materials and MethodsCBF was measured in 20 healthy volunteers using DSC‐MRI at 3T and Xe‐133 SPECT. DSC‐MRI was accomplished by gradient‐echo EPI and CBF was calculated using a time‐shift‐insensitive deconvolution algorithm and regional arterial input functions (AIFs). To improve the reproducibility of AIF registration the time integral was rescaled by use of a venous output function. In the Xe‐133 SPECT experiment, Xe‐133 gas was inhaled over 8 minutes and CBF was calculated using a biexponential analysis.ResultsThe average whole‐brain CBF estimates obtained by DSC‐MRI and Xe‐133 SPECT were 85 ± 23 mL/(min 100 g) and 40 ± 8 mL/(min 100 g), respectively (mean ± SD, n = 20). The linear CBF relationship between the two modalities showed a correlation coefficient of r = 0.76 and was described by the equation CBF(MRI) = 2.4 · CBF(Xe)−7.9 (CBF in units of mL/(min 100 g)).ConclusionA reasonable positive linear correlation between MRI‐based and SPECT‐based CBF estimates was observed after AIF time‐integral correction. The use of DSC‐MRI typically results in overestimated absolute perfusion estimates and the present study indicates that this trend is further enhanced by the use of high magnetic field strength (3T). J. Magn. Reson. Imaging 2007;26:913–920. © 2007 Wiley‐Liss, Inc.
Measurement of cerebral blood volume in humans using hyperoxic MRI contrast
Authors: Bulte Daniel , Chiarelli Peter , Wise Richard , Jezzard Peter 
Published: September 2007

AbstractPurposeTo develop a new method of measuring quantitative regional cerebral blood volume (CBV) using epochs of hyperoxia as an intravenous contrast agent with T2*‐weighted MRI.Materials and MethodsImages were acquired from six subjects (four male, two female, mean age 29 ± 3.7 years) using a sequence combining pulsed arterial spin labeling interleaved with a gradient echo echo‐planar imaging (EPI) blood oxygenation level‐dependent (BOLD) sequence at 3T. The hyperoxia paradigm lasted 28 minutes consisting of 4 minutes of normoxia, two 6‐minute blocks of hyperoxia separated by 6 minutes of normoxia. During the hyperoxic blocks the subjects were delivered a fractional oxygen concentration of 0.5.ResultsThe mean CBV was calculated to be 3.77 ± 1.05 mL/100 g globally, 3.93 ± 0.90 mL/100 g in gray matter (GM), and 2.52 ± 0.78 mL/100 g in white matter (WM). The mean GM/WM ratio was thus found to be 1.56. These values are comparable to those obtained in other studies.ConclusionThe hyperoxia technique for measuring CBV may be particularly useful for patient groups where an injected bolus of contrast agent is contraindicated. As more functional studies are employing epochs of inspired gases for calibration purposes, this method is easily incorporated into existing paradigms to produce a noninvasive, repeatable, easily tolerated, and quantitative measurement of regional CBV. J. Magn. Reson. Imaging 2007;26:894–899. © 2007 Wiley‐Liss, Inc.
Intracranial time‐of‐flight MR angiography at 7T with comparison to 3T
Authors: von Morze Cornelius , Xu Duan , Purcell Derk D. , Hess Christopher P. , Mukherjee Pratik , Saloner David , Kelley Douglas A.C. , Vigneron Daniel B. 
Published: September 2007

AbstractPurposeTo establish the feasibility of intracranial time‐of‐flight (TOF) MR angiography (MRA) at 7T using phased array coils and to compare its performance to 3T.Materials and MethodsIn an initial study, five normal volunteers were scanned at 7T and 3T using eight‐channel coils and standard acquisition parameters from a clinical TOF protocol. In a second study three additional studies were performed at 7T and 3T using empirically optimized 7T parameters. Contrast‐to‐noise (CNR) values were measured for major vessel segments.ResultsAll measurements documented CNR increases at 7T, with a mean increase of 83% in the initial study and 88% in the second study. The CNR values achieved using the latter protocol were similar to the values obtained in the initial study, despite the 42% reduction expected due to the higher spatial resolution. CNR in the smaller peripheral vessels was increased dramatically, resulting in excellent visualization at high resolution.ConclusionTOF MRA at 7T demonstrated improved visualization of the intracranial vasculature, particularly the smaller peripheral vessels, and may benefit studies of small aneurysms, atherosclerosis, vasospasm, and vasculitis. J. Magn. Reson. Imaging 2007;26:900–904. © 2007 Wiley‐Liss, Inc.
Bleomycin‐induced lung injury assessed noninvasively and in spontaneously breathing rats by proton MRI
Authors: Karmouty‐Quintana Harry , Cannet Catherine , Zurbruegg Stefan , Blé François‐Xavier , Fozard John R. , Page Clive P. , Beckmann Nicolau 
Published: September 2007

AbstractPurposeTo apply proton magnetic resonance imaging (MRI) techniques to assess noninvasively and in spontaneously breathing rats, structural changes following a single intratracheal administration of bleomycin (BLM).Materials and MethodsRats were scanned by MRI prior to BLM or vehicle administration and at six hours, 24 hours, week 1, and at weeks 2, 3, 6, and 8 after treatment. Bronchoalveolar lavage (BAL) fluid and histological analyses were performed at 24 hours, and at weeks 1 and 8 (histology only).ResultsProminent MRI fluid signals were detected in the lungs of BLM‐treated rats one week after challenge. These signals correlated with increased inflammatory parameters in BAL fluid and with marked perivascular and parenchymal infiltration with inflammatory cells in histological slices. At week 2 the MRI signals due to edema resolved, but nevertheless an increase in MRI signal intensity from the lung parenchyma was apparent. In some areas of the right lung the MRI signal intensity in the parenchyma decreased between weeks 2 and 8. These observations were in line with histology demonstrating collagen deposition and atelectasis (hallmarks of fibrosis) at week 1 and a partial recovery of the lung parenchyma at week 8.ConclusionThe data demonstrate the ability of proton MRI to detect BLM‐induced lung fibrosis as well as the acute inflammatory response caused by the agent. J. Magn. Reson. Imaging 2007;26:941–949. © 2007 Wiley‐Liss, Inc.
Accuracy and reliability of MRI vs. laboratory measurements in an ex vivo porcine model of arthritic cartilage loss
Authors: Jaremko Jacob L. , Maciejewski Conrad M. , Cheng Rita W.T. , Ronsky Janet L. , Thompson Richard B. , Lambert Robert G.W. , Dhillon Sukhvinder S. 
Published: September 2007

AbstractPurposeTo quantify the accuracy of magnetic resonance imaging (MRI) measurement of change in cartilage volume due to thin linear excisions, simulating arthritic cartilage losses, by comparison with laboratory volume measurements in an ex vivo porcine model.Materials and MethodsWe scanned 15 porcine patellae by T1‐weighted spoiled gradient echo (SPGR) MRI at baseline and after excision of up to three thin layers of articular cartilage. Excised fragment volume was determined from density and weight. Postexcision scans were “fused” to the baseline scan by three‐dimensional (3D) registration. This allowed automated recalculation of the remaining cartilage volume within a baseline region of interest (ROI) following each excision. We compared MRI estimates of change in cartilage volume to direct laboratory measurement of fragment volume.ResultsOur 38 excised fragments averaged 0.16 mL, or ∼7% of cartilage volume. MRI and laboratory estimates of total cartilage volume loss differed by 1.6% ± 13.2% (mean, coefficient of variation [CV]). Accuracy was ±0.1 mL for 95% of scans.ConclusionMRI estimates of small changes in porcine patellar cartilage volume were unbiased, reliable, and accurate to 0.1 mL. Despite a proportionately high error in the very thin fragments tested, achievement of similar accuracy in vivo would be adequate to detect approximately two years of osteoarthritic cartilage loss. J. Magn. Reson. Imaging 2007;26:992–1000. © 2007 Wiley‐Liss, Inc.
Assessment of microvascular density, extracellular volume fraction, and radiobiological hypoxia in human melanoma xenografts by dynamic contrast‐enhanced MRI
Authors: Vestvik Ida K. , Egeland Tormod A.M. , Gaustad Jon‐Vidar , Mathiesen Berit , Rofstad Einar K. 
Published: September 2007

AbstractPurposeTo investigate whether gadopentetate dimeglumine (Gd‐DTPA)‐based dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI) may be a useful method for assessing fraction of radiobiologically hypoxic cells in tumors.Materials and MethodsA‐07 and R‐18 human melanoma xenografts were used as preclinical tumor models. DCE‐MRI was performed at a voxel size of 0.23 × 0.47 × 2.0 mm3. Tumor images of E · F (E is the initial extraction fraction of Gd‐DTPA and F is blood perfusion) and λ (the partition coefficient of Gd‐DTPA) were produced by subjecting DCE‐MRI series to Kety analysis. Microvascular density and extracellular volume fraction (ECVF) were determined by analysis of histological preparations. The fraction of radiobiologically hypoxic cells was measured by the paired survival curve method.ResultsE · F correlated with microvascular density, and λ correlated with ECVF. The fraction of hypoxic cells was ∼6.5‐fold higher in R‐18 tumors than in A‐07 tumors, consistent with the observation that A‐07 tumors showed higher values for E · F and microvascular density and lower cell density (i.e., higher values for λ and ECVF) than R‐18 tumors.ConclusionE · F and λ images obtained by Kety analysis of DCE‐MRI series contain information that may be utilized to estimate the extent of radiobiological hypoxia in tumors. J. Magn. Reson. Imaging 2007;26:1033–1042. © 2007 Wiley‐Liss, Inc.
Multisite fMRI reproducibility of a motor task using identical MR systems
Authors: Costafreda Sergi G. , Brammer Michael J. , Vêncio Ricardo Z.N. , Mourão Maria L. , Portela Luiz A.P. , de Castro Claudio Campi , Giampietro Vincent P. , Amaro Edson 
Published: September 2007

AbstractPurposeTo estimate between‐scanner functional MRI (fMRI) reproducibility in a multisite study.Materials and MethodsA total of five identical 1.5T MR systems were used to repeatedly scan five subjects while performing a finger tapping task. A two‐way (scanners, subjects) random effects analysis of variance (ANOVA) was used to estimate between‐scanner and between‐subject variability on two outcome variables: task‐related mean blood oxygenation level dependent (BOLD) signal change and volume of activation within a motor region‐of‐interest (ROI).ResultsBetween‐scanner variability of fMRI data accounted for a small proportion of the total variation in the BOLD signal change (8.34%, P = 0.114) and volume of activation (5.46%, P = 0.203). Between‐subject variation accounted for more than half of the total variation for both measurements (57.17% and 54.46%, respectively, P < 0.01).ConclusionThese results support the feasibility of multisite studies using identical scanner systems. J. Magn. Reson. Imaging 2007;26:1122–1126. © 2007 Wiley‐Liss, Inc.
MR‐guided radiofrequency ablation in a 0.2‐T open MR system: Technical success and technique effectiveness in 100 liver tumors
Authors: Clasen Stephan , Boss Andreas , Schmidt Diethard , Schraml Christina , Fritz Jan , Schick Fritz , Claussen Claus D. , Pereira Philippe L. 
Published: September 2007

AbstractPurposeTo evaluate the feasibility and technique effectiveness of magnetic resonance (MR)‐guided radiofrequency (RF) ablation of hepatic malignancies.Materials and MethodsIn 64 patients, 100 primary (N = 19) or secondary (N = 81) liver tumors (mean diameter = 24.7 mm; range = 4–60 mm) were treated with 87 sessions of MR‐guided RF ablation. The entire ablation procedure was carried out at an 0.2‐T open MR system by using MR‐compatible internally cooled electrodes. T2‐weighted turbo spin echo sequences (TR/TE = 3500 msec/110 msec) were used to monitor thermally induced coagulation. Technique effectiveness was assessed four months after the last RF ablation by dynamic MR imaging at 1.5‐T.ResultsMR‐guided RF ablation procedures were technical successful in 85 of 87 (97.7%) assessed at the end of each session. Complete coagulation was intended in 99 of 100 tumors. Technique effectiveness was observed in 92 of 99 (92.9%) of these tumors. To achieve complete coagulation 82 of 92 (89.1%) tumors required a single session. T2‐weighted sequences were accurate to monitor the extent of coagulation and were supportive to guide overlapping ablation. There were two of 87 (2.3%) major and seven of 87 (8.0%) minor complications.ConclusionMR‐guided RF ablation is a safe and effective therapy in the treatment of hepatic malignancies. MR imaging offers an accurate monitoring of thermally‐induced coagulation, thus enabling complete tumor coagulation in a single session. J. Magn. Reson. Imaging 2007;26:1043–1052. © 2007 Wiley‐Liss, Inc.
Parallel imaging of knee cartilage at 3 Tesla
Authors: Zuo Jin , Li Xiaojuan , Banerjee Suchandrima , Han Eric , Majumdar Sharmila 
Published: September 2007

AbstractPurposeTo evaluate the feasibility and reproducibility of quantitative cartilage imaging with parallel imaging at 3T and to determine the impact of the acceleration factor (AF) on morphological and relaxation measurements.Materials and MethodsAn eight‐channel phased‐array knee coil was employed for conventional and parallel imaging on a 3T scanner. The imaging protocol consisted of a T2‐weighted fast spin echo (FSE), a 3D‐spoiled gradient echo (SPGR), a custom 3D‐SPGR T1rho, and a 3D‐SPGR T2 sequence. Parallel imaging was performed with an array spatial sensitivity technique (ASSET). The left knees of six healthy volunteers were scanned with both conventional and parallel imaging (AF = 2).ResultsMorphological parameters and relaxation maps from parallel imaging methods (AF = 2) showed comparable results with conventional method. The intraclass correlation coefficient (ICC) of the two methods for cartilage volume, mean cartilage thickness, T1rho, and T2 were 0.999, 0.977, 0.964, and 0.969, respectively, while demonstrating excellent reproducibility. No significant measurement differences were found when AF reached 3 despite the low signal‐to‐noise ratio (SNR).ConclusionThe study demonstrated that parallel imaging can be applied to current knee cartilage quantification at AF = 2 without degrading measurement accuracy with good reproducibility while effectively reducing scan time. Shorter imaging times can be achieved with higher AF at the cost of SNR. J. Magn. Reson. Imaging 2007;26:1001–1009. © 2007 Wiley‐Liss, Inc.
Cancer yield of probably benign breast MR examinations
Authors: Eby Peter R. , DeMartini Wendy B. , Peacock Sue , Rosen Eric L. , Lauro Bridget , Lehman Constance D. 
Published: September 2007

AbstractPurposeTo evaluate the cancer yield, frequency of use, and follow‐up compliance of breast MR examinations assessed as “probably benign.”Materials and MethodsWe retrospectively reviewed our MR database of 809 consecutive examinations between January 2003 and June 2004. We identified all examinations that ultimately received an MR breast imaging reporting and data system (BI‐RADS) 3 assessment and recommendation for a short‐interval follow‐up MR with or without an antecedent targeted ultrasound. The clinical indication for breast MR, date of the follow‐up examination, follow‐up assessment, and any pathology findings through June 2005 were collected from clinical records and radiology and pathology reports. Frequency of BI‐RADS 3 use, follow‐up compliance, and cancer yield were calculated.ResultsA total of 160 out of 809 (20%) examinations comprise the study population. A total of 100 out of 160 (63%) women returned for the recommended follow‐up MR, in which three out of 100 (3%) were upgraded to BI‐RADS 4 with biopsy recommended. One patient underwent biopsy and the result was benign. A total of seven out of 160 (4%) underwent mastectomy in lieu of MR for known cancer elsewhere in the breast. One out of seven mastectomy specimens contained malignancy that corresponded to the probably benign finding, resulting in a cancer yield of one out of 160 (0.6%).ConclusionOur data suggest that follow‐up MR is a valid alternative to biopsy for MR BI‐RADS 3 lesions. J. Magn. Reson. Imaging 2007;26:950–955. © 2007 Wiley‐Liss, Inc.