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Perfusion MRI (perfusion + mri)
Kinds of Perfusion MRI Selected AbstractsDynamic observation of pulmonary perfusion using continuous arterial spin-labeling in a pig modelJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2001David A. Roberts MD Abstract The continuous arterial spin-labeling (CASL) method of perfusion MRI is used to observe pulmonary perfusion dynamically in an animal model. Specifically, a respiratory-triggered implementation of the CASL method is used with approximate spatial resolution of 0.9 × 1.8 × 5.0 mm (0.008 cc) and 2-minute temporal resolution. Perfusion MRI is performed dynamically during repeated balloon occlusion of a segmental pulmonary artery, as well as during pharmacological stimulation. A total of three Yorkshire pigs were studied. The results demonstrate the ability of the endogenous spin-labeling method to characterize the dynamic changes in pulmonary perfusion that occur during important physiological alterations. J. Magn. Reson. Imaging 2001;14:175,180. © 2001 Wiley-Liss, Inc. [source] Harmonic Imaging in Acute Stroke: Detection of a Cerebral Perfusion Deficit With Ultrasound and Perfusion MRIJOURNAL OF NEUROIMAGING, Issue 2 2003Karsten Meyer MD ABSTRACT Perfusion harmonic imaging of the brain is a new ultrasound technique for assessing cerebral perfusion. In a patient with acute middle cerebral artery infarction, this method detected a cerebral perfusion deficit corresponding to the area of delayed perfusion as displayed by perfusion magnetic resonance imaging. [source] Susceptibility Contrast and Arterial Spin Labeled Perfusion MRI in Cerebrovascular DiseaseJOURNAL OF NEUROIMAGING, Issue 1 2003Ronald L. Wolf MD ABSTRACT Purpose. To directly compare dynamic susceptibility contrast (DSC) and continuous arterial spin labeled (CASL) magnetic resonance (MR) perfusion techniques in patients with known cerebrovascular disease, with the goals of identifying possible pitfalls in interpretation and determining potential for a complementary role in this setting. Methods. DSC and CASL MR perfusion studies were performed and compared in 11 patients with acute and/or chronic cerebrovascular disease. Using an automated segmentation technique, Pearson correlation coefficients were generated for CASL perfusion measurements compared to DSC perfusion maps (time-to-peak [TTP], relative cerebral blood volume [rCBV], cerebral blood flow [rCBF], and mean transit time [MTT]) by hemisphere and vascular territory. Results. TTP maps obtained using DSC perfusion MR correlated best both subjectively and objectively with CASL perfusion MRmeasurements when all patients studied were considered. If patients with a major transit delay were excluded, DSC rCBF correlated best with CASL CBF measurements. Conclusion. There may be a complementary role for CASL and DSC perfusion MR methods in cerebrovascular disease, especially in the setting of a marked transit delay. [source] Perfusion MRI with radial acquisition for arterial input function assessment,MAGNETIC RESONANCE IN MEDICINE, Issue 5 2007Eugene G. Kholmovski Abstract Quantification of myocardial perfusion critically depends on accurate arterial input function (AIF) and tissue enhancement curves (TECs). Except at low doses, the AIF is inaccurate because of the long saturation recovery time (SRT) of the pulse sequence. The choice of dose and SRT involves a trade-off between the accuracy of the AIF and the signal-to-noise ratio (SNR) of the TEC. Recent methods to resolve this trade-off are based on the acquisition of two data sets: one to accurately estimate the AIF, and one to find the high-SNR TEC. With radial k -space sampling, a set of images with varied SRTs can be reconstructed from the same data set, allowing an accurate assessment of the AIF and TECs, and their conversion to contrast agent (CA) concentration. This study demonstrates the feasibility of using a radial acquisition for quantitative myocardial perfusion imaging. Magn Reson Med 57:821,827, 2007. © 2007 Wiley-Liss, Inc. [source] Perfusion MRI: a brief overviewACTA NEUROPSYCHIATRICA, Issue 6 2009Inge Rasmussen Jr No abstract is available for this article. [source] Perfusion MR imaging with pulsed arterial spin-labeling: Basic principles and applications in functional brain imagingCONCEPTS IN MAGNETIC RESONANCE, Issue 5 2002Yihong Yang Abstract Basic principles of the arterial spin-labeling perfusion MRI are described, with focus on a brain perfusion model with pulsed labeling. A multislice perfusion imaging sequence with adiabatic inversion and spiral scanning is illustrated as an example. The mechanism of the perfusion measurement, the quantification of cerebral blood flow, and the suppression of potential artifacts are discussed. Applications of the perfusion imaging in brain activation studies, including simultaneous detection of blood flow and blood oxygenation, are demonstrated. Important issues associated with the applications such as sensitivity, quantification, and temporal resolution are discussed. © 2002 Wiley Periodicals, Inc. Concepts Magn Reson 14: 347,357, 2002 [source] Magnetic resonance imaging for ischemic heart diseaseJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 1 2007Hajime Sakuma MD Abstract Cardiac MRI has long been recognized as an accurate and reliable means of evaluating cardiac anatomy and ventricular function. Considerable progress has been made in the field of cardiac MRI, and cardiac MRI can provide accurate evaluation of myocardial ischemia and infarction (MI). Late gadolinium (Gd)-enhanced MRI can clearly delineate subendocardial infarction, and the assessment of transmural extent of infarction on late enhanced MRI has been shown to be useful in predicting functional recovery of dysfunctional myocardium in patients after MI. Stress first-pass contrast-enhanced (CE) myocardial perfusion MRI can be used to detect subendocardial ischemia, and recent studies have demonstrated the high diagnostic accuracy of stress myocardial perfusion MRI for detecting significant coronary artery disease (CAD). Free-breathing, whole-heart coronary MR angiography (MRA) was recently introduced as a method that can provide visualization of all three major coronary arteries within a single three-dimensional (3D) acquisition. With further improvements in MRI techniques and the establishment of a standardized study protocol, cardiac MRI will play a pivotal role in managing patients with ischemic heart disease. J. Magn. Reson. Imaging 2007;26:3,13. © 2007 Wiley-Liss, Inc. [source] High cerebral blood volume in human gliomas predicts deletion of chromosome 1p: Preliminary results of molecular studies in gliomas with elevated perfusionJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 6 2007Meng Law MD Abstract Purpose To determine if increased perfusion using dynamic susceptibility contrast perfusion MRI (DSC MRI) in gliomas may be predictive of 1p19q deletions. Loss of heterozygosity of chromosomes 1p and 19q confers responsiveness to chemotherapy improving survival in gliomas. Materials and Methods We retrospectively reviewed 16 patients who had DSC MRI and molecular studies of their excised gliomas for 1p19q deletions. Allelic status was assessed by loss of heterozygosity using polymerase chain reaction (PCR). DNA was extracted from paraffin curls of brain tumor sections and nail clippings. Relative cerebral blood volume (rCBV) measurements were then statistically compared with the presence of 1p and 19q deletions. Results Patients with 1p19q deletions (N = 7) demonstrated rCBV values of 10.54 ± 2.93. Patients without 1p deletions (N = 9) had rCBV values of 4.84 ± 2.4 (P = 0.012). Logistic regression demonstrated that rCBV was able to predict the presence of a 1p deletion to significance levels of 0.038 and 0.044, adjusted and not adjusted for age and sex, respectively. The kappa coefficient for the agreement between predicted deletion status using rCBV and the truedeletion status was 0.746 (P = 0.0028). Deletions of 19q alone, or together with 1p deletions, were not associated with high rCBV. Conclusion Histopathologic, molecular, and imaging evidence supports increased neovascularity in gliomas with 1p deletions in this preliminary study. We propose a diagnostic algorithm to obtain molecular studies in gliomas demonstrating high rCBV. J. Magn. Reson. Imaging 2007;25:1113,1119. © 2007 Wiley-Liss, Inc. [source] Blood oxygenation level-dependent MRI of cerebral gliomas during breath holdingJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2004Yuan-Yu Hsu MD Abstract Purpose To assess the cerebrovascular responses to short breath holding of cerebral gliomas using blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI). Materials and Methods Six patients with a low-grade glioma and one patient with a high-grade glioma were studied using T2*-weighted echo planar imaging (EPI) during repeated periods of 15-second or 20-second breath-holding. Tumor vascularity was evaluated using dynamic susceptibility contrast perfusion MRI. Results Increases in BOLD signal intensity during repeated breath-holding were consistently identified in patients' normal appearing gray matter, comparable with those in healthy adults. Absence of significant BOLD signal enhancement was noted both in low-grade and high-grade gliomas, which is either due to overwhelming hypoxia in a tumor, inadequacy or absence of hypercapnia-induced vasodilatation of tumor vessels, or both. Breath-hold regulated decreases in BOLD signals occurred only in the high-grade glioma, which is most likely due to the hypercapnia-induced steal effect that redistributes blood flow from tumor regions with unresponsive neovasculature to surrounding normal tissue. Conclusion BOLD MRI during short breath holding can disclose differential cerebrovascular response between normal tissue and cerebral glioma. J. Magn. Reson. Imaging 2004;19:160,167. © 2004 Wiley-Liss, Inc. [source] Dynamic observation of pulmonary perfusion using continuous arterial spin-labeling in a pig modelJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2001David A. Roberts MD Abstract The continuous arterial spin-labeling (CASL) method of perfusion MRI is used to observe pulmonary perfusion dynamically in an animal model. Specifically, a respiratory-triggered implementation of the CASL method is used with approximate spatial resolution of 0.9 × 1.8 × 5.0 mm (0.008 cc) and 2-minute temporal resolution. Perfusion MRI is performed dynamically during repeated balloon occlusion of a segmental pulmonary artery, as well as during pharmacological stimulation. A total of three Yorkshire pigs were studied. The results demonstrate the ability of the endogenous spin-labeling method to characterize the dynamic changes in pulmonary perfusion that occur during important physiological alterations. J. Magn. Reson. Imaging 2001;14:175,180. © 2001 Wiley-Liss, Inc. [source] Systolic 3D first-pass myocardial perfusion MRI: Comparison with diastolic imaging in healthy subjectsMAGNETIC RESONANCE IN MEDICINE, Issue 4 2010Taehoon Shin Abstract Three-dimensional (3D) first-pass myocardial perfusion imaging (MPI) is a promising alternative to conventional two-dimensional multislice MPI due to its contiguous spatial coverage that is beneficial for estimating the size of perfusion defects. Data acquisition at mid-diastole is a typical choice for 3D MPI yet is sensitive to arrhythmia and variations in R-R interval that are common in cardiac patients. End systole is the second longest quiescent cardiac phase and is known to be less sensitive to the R-R variability. Therefore, 3D MPI with systolic acquisition may be advantageous in patients with severe arrhythmia once it is proven to be comparable to diastolic MPI in subjects with negligible R-R variation. In this work, we demonstrate the feasibility of 3D MPI with systolic data acquisition in five healthy subjects. We performed 3D MPI experiments in which 3D perfusion data were acquired at both end-systole and mid-diastole of every R-R interval and analyzed the similarity between resulting time intensity curves (TIC) from the two data sets. The correlation between systolic and diastolic TICs was extremely high (mean = 0.9841; standard deviation = 0.0166), and there was a significant linear correlation between the two time intensity curve upslopes and peak enhancements (P < 0.001). Magn Reson Med 63:858,864, 2010. © 2010 Wiley-Liss, Inc. [source] Myocardial perfusion MRI with sliding-window conjugate-gradient HYPRMAGNETIC RESONANCE IN MEDICINE, Issue 4 2009Lan Ge Abstract First-pass perfusion MRI is a promising technique for detecting ischemic heart disease. However, the diagnostic value of the method is limited by the low spatial coverage, resolution, signal-to-noise ratio (SNR), and cardiac motion-related image artifacts. In this study we investigated the feasibility of using a method that combines sliding window and CG-HYPR methods (SW-CG-HYPR) to reduce the acquisition window for each slice while maintaining the temporal resolution of one frame per heartbeat in myocardial perfusion MRI. This method allows an increased number of slices, reduced motion artifacts, and preserves the relatively high SNR and spatial resolution of the "composite images." Results from eight volunteers demonstrate the feasibility of SW-CG-HYPR for accelerated myocardial perfusion imaging with accurate signal intensity changes of left ventricle blood pool and myocardium. Using this method the acquisition time per cardiac cycle was reduced by a factor of 4 and the number of slices was increased from 3 to 8 as compared to the conventional technique. The SNR of the myocardium at peak enhancement with SW-CG-HYPR (13.83 ± 2.60) was significantly higher (P < 0.05) than the conventional turbo-FLASH protocol (8.40 ± 1.62). Also, the spatial resolution of the myocardial perfection images was significantly improved. SW-CG-HYPR is a promising technique for myocardial perfusion MRI. Magn Reson Med, 2009. © 2009 Wiley-Liss, Inc. [source] Quantitative analysis of first-pass contrast-enhanced myocardial perfusion MRI using a patlak plot method and blood saturation correctionMAGNETIC RESONANCE IN MEDICINE, Issue 2 2009Takashi Ichihara Abstract The objectives of this study were to develop a method for quantifying myocardial K1 and blood flow (MBF) with minimal operator interaction by using a Patlak plot method and to compare the MBF obtained by perfusion MRI with that from coronary sinus blood flow in the resting state. A method that can correct for the nonlinearity of the blood time,signal intensity curve on perfusion MR images was developed. Myocardial perfusion MR images were acquired with a saturation-recovery balanced turbo field-echo sequence in 10 patients. Coronary sinus blood flow was determined by phase-contrast cine MRI, and the average MBF was calculated as coronary sinus blood flow divided by left ventricular (LV) mass obtained by cine MRI. Patlak plot analysis was performed using the saturation-corrected blood time,signal intensity curve as an input function and the regional myocardial time,signal intensity curve as an output function. The mean MBF obtained by perfusion MRI was 86 ± 25 ml/min/100 g, showing good agreement with MBF calculated from coronary sinus blood flow (89 ± 30 ml/min/100 g, r = 0.74). The mean coefficient of variation for measuring regional MBF in 16 LV myocardial segments was 0.11. The current method using Patlak plot permits quantification of MBF with operator interaction limited to tracing the LV wall contours, registration, and time delays. Magn Reson Med, 2009. © 2009 Wiley-Liss, Inc. [source] Evaluation of an AIF correction algorithm for dynamic susceptibility contrast-enhanced perfusion MRIMAGNETIC RESONANCE IN MEDICINE, Issue 1 2008Peter Brunecker Abstract For longitudinal studies in patients suffering from cerebrovascular diseases the poor reproducibility of perfusion measurements via dynamic susceptibility-weighted contrast-enhanced MRI (DSC-MRI) is a relevant concern. We evaluate a novel algorithm capable of overcoming limitations in DSC-MRI caused by partial volume and saturation issues in the arterial input function (AIF) by a blood flow stimulation-study. In 21 subjects, perfusion parameters before and after administration of blood flow stimulating L -arginine were calculated utilizing a block-circulant singular value decomposition (cSVD). A total of two different raters and three different rater conditions were employed to select AIFs: Besides 1) an AIF selection by an experienced rater, a beginner rater applied a steady state-oriented strategy, returning; 2) raw; and 3) corrected AIFs. Highly significant changes in regional cerebral blood flow (rCBF) by 9.0% (P < 0.01) could only be found when the AIF correction was performed. To further test for improved reproducibility, in a subgroup of seven subjects the baseline measurement was repeated 6 weeks after the first examination. In this group as well, using the correction algorithm decreased the SD of the difference between the two baseline measurements by 42%. Magn Reson Med 60:102,110, 2008. © 2008 Wiley-Liss, Inc. [source] Early magnetic resonance imaging findings in patients receiving tissue plasminogen activator predict outcome: Insights into the pathophysiology of acute stroke in the thrombolysis era,ANNALS OF NEUROLOGY, Issue 1 2004Julio A. Chalela MD We measured ischemic brain changes with diffusion and perfusion MRI in 42 ischemic stroke patients before and 2 hours (range approximately 1.5 to 4.5 hours) after standard intravenous tissue plasminogen activator (tPA) therapy. The median time from stroke onset to tPA was 131 minutes. Clinical and MRI variables (change in perfusion and/or diffusion weighted lesion volume) were compared between those with excellent outcome defined as 3-month modified Rankin score (mRS) of 0 to 1 and those with incomplete recovery (mRS >1). In multivariate logististic regression analysis, the most powerful independent predictor for excellent outcome was improved brain perfusion: hypoperfusion volume on mean transit time (MTT) map decrease >30% from baseline to 2-hour post tPA scan (p=0.009; odds ratio [95% confidence interval], 20.7 [2.1-203.9]). Except for age < 70 years, no other baseline clinical or imaging variable was an independent predictor of outcome. We propose MTT lesion volume decrease more than 30% 2 hours after tPA as an early marker of long-term clinical benefit of thrombolytic therapy. [source] | ||||||||||||||||||||||