共查询到20条相似文献,搜索用时 46 毫秒
1.
S. Sivaram Kaushik Zackary I. Cleveland Gary P. Cofer Gregory Metz Denise Beaver John Nouls Monica Kraft William Auffermann Jan Wolber H. Page McAdams Bastiaan Driehuys 《Magnetic resonance in medicine》2011,65(4):1154-1165
Given its greater availability and lower cost, 129Xe apparent diffusion coefficient (ADC) MRI offers an alternative to 3He ADC MRI. To demonstrate the feasibility of hyperpolarized 129Xe ADC MRI, we present results from healthy volunteers (HV), chronic obstructive pulmonary disease (COPD) subjects, and age‐matched healthy controls (AMC). The mean parenchymal ADC was 0.036 ± 0.003 cm2 sec?1 for HV, 0.043 ± 0.006 cm2 sec?1 for AMC, and 0.056 ± 0.008 cm2 sec?1 for COPD subjects with emphysema. In healthy individuals, but not the COPD group, ADC decreased significantly in the anterior–posterior direction by ~22% (P = 0.006, AMC; 0.0059, HV), likely because of gravity‐induced tissue compression. The COPD group exhibited a significantly larger superior–inferior ADC reduction (~28%) than the healthy groups (~24%) (P = 0.00018, HV; P = 3.45 × 10?5, AMC), consistent with smoking‐related tissue destruction in the superior lung. Superior–inferior gradients in healthy subjects may result from regional differences in xenon concentration. ADC was significantly correlated with pulmonary function tests (forced expiratory volume in 1 sec, r = ?0.77, P = 0.0002; forced expiratory volume in 1 sec/forced vital capacity, r = ?0.77, P = 0.0002; diffusing capacity of carbon monoxide in the lung/alveolar volume (VA), r = ?0.77, P = 0.0002). In healthy groups, ADC increased with age by 0.0002 cm2 sec?1 year?1 (r = 0.56, P = 0.02). This study shows that 129Xe ADC MRI is clinically feasible, sufficiently sensitive to distinguish HV from subjects with emphysema, and detects age‐ and posture‐dependent changes. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc. 相似文献
2.
Hemanthkumar Athiraman Quan Jiang Guang Liang Ding Li Zhang Zheng Gang Zhang Lei Wang Ali S. Arbab Qingjiang Li Swayam Panda Karen Ledbetter Ali M. Rad Michael Chopp 《Magnetic resonance in medicine》2009,61(3):587-594
MRI has been used to evaluate labeled cell migration and distribution. However, quantitative determination of labeled cell concentration using MRI has not been systematically investigated. In the current study, we investigated the relationships between labeled cell concentration and MRI parameters of transverse relaxation rate, R2, and apparent diffusion coefficient (ADC), in vitro in phantoms and in vivo in rats after stroke. Significant correlations were detected between iron concentration or labeled cell concentration and MRI measurements of R2, ADC, and ADC×R2 in vitro. In contrast, in vivo labeled cell concentration did not significantly correlate with R2, ADC, and ADC×R2. A major factor for the absence of a significant correlation between labeled cell concentration and MRI measurements in vivo may be attributed to background effects of ischemic tissue. By correcting the background effects caused by ischemic damage, ΔR2 (difference in R2 values in the ischemic tissue with and without labeled cells) exhibited a significant correlation to labeled cell concentration. Our study suggests that MRI parameters have the potential to quantitatively determine labeled cell concentration in vivo. Magn Reson Med, 2009. © 2008 Wiley‐Liss, Inc. 相似文献
3.
Dingxin Wang Sumeet Virmani Richard Tang Barbara Szolc‐Kowalska Gayle Woloschak Reed A. Omary Andrew C. Larson 《Magnetic resonance in medicine》2008,60(4):970-975
Transcatheter intraarterial perfusion (TRIP)‐MRI is an intraprocedural technique to iteratively monitor liver tumor perfusion changes during transcatheter arterial embolization (TAE) and chemoembolization (TACE). However, previous TRIP‐MRI approaches using two‐dimensional (2D) T1‐weighted saturation‐recovery gradient‐recalled echo (GRE) sequences provided only limited spatial coverage and limited capacity for accurate perfusion quantification. In this preclinical study, a quantitative 4D TRIP‐MRI technique (serial iterative 3D volumetric perfusion imaging) with rigorous radiofrequency (RF) B1 field calibration and dynamic tissue longitudinal relaxation rate R1 measurement is presented for monitoring intraprocedural liver tumor perfusion during TAE. 4D TRIP‐MRI and TAE were performed in five rabbits with eight VX2 liver tumors (N = 8). After B1 calibrated baseline and dynamic R1 quantification, subsequent tissue contrast agent concentration time curves were derived. A single‐input flow‐limited pharmacokinetic model and peak gradient method were applied for perfusion analysis. The perfusion Fρ reduced significantly from pre‐TAE 0.477 (95% confidence interval [CI]: 0.384–0.570) to post‐TAE 0.131 (95% CI: 0.080–0.183 ml/min/ml, P < 0.001). Magn Reson Med 60:970–975, 2008. © 2008 Wiley‐Liss, Inc. 相似文献
4.
Benjamin Lemasson Samuel Valable Régine Farion Alexandre Krainik Chantal Rémy Emmanuel L. Barbier 《Magnetic resonance in medicine》2013,69(1):18-26
The aim of this study was to compare magnetic resonance imaging (MRI) and histological estimates of the mean vessel diameter (mVD), the vessel density (Density), and the vessel size index (VSI) obtained in the same tumor‐bearing animals. Twenty‐seven rats bearing intracranial glioma (C6 or RG2) were imaged by MRI. Changes in transverse relaxations (ΔR and R2) were induced by the injection of an iron‐based contrast agent and were mapped using a multi gradient‐echo spin‐echo sequence. Then, brain vascular network was studied ex vivo by histology. Three regions of interest were drawn in apparently normal tissue (neocortex and striatum) and in the tumor. In vivo mVDMRI, DensityMRI, and VSIMRI were measured; ex vivo, mVDhisto, Densityhisto, and VSIhisto were quantified on the same animals. MRI and histology measurements differed by ?15 to 26%. A positive correlation was found between MRI and histology for mVD, Density, and VSI counterparts (R2 = 0.62, 0.50, 0.73, respectively; P < 0.001 in all cases). This study indicates that MRI and histology yields well correlated the estimates of mVD, Density, and VSI. VSI is the closest MRI estimate to histology. As Density and mVD or VSI provide complementary information, it is worth computing them to characterize angiogenesis beyond blood volume fraction. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc. 相似文献
5.
Fluorine‐19 [19F] MRI oximetry and 1H blood oxygen level–dependent (BOLD) MRI were used to investigate tumor oxygenation in rat breast 13762NF carcinomas, and correlations between the techniques were examined. A range of tissue oxygen partial pressure (pO2) values was found in the nine tumors while the anesthetized rats breathed air, with individual tumor pO2 ranging from a mean of 1 to 36 torr and hypoxic fraction (HF10) (<10 torr) ranging from 0% to 75%, indicating a large intra‐ and intertumor heterogeneity. Breathing oxygen produced significant increase in tumor pO2 (mean ΔpO2 = 50 torr) and decrease in HF10 (P < 0.01). 1H BOLD MRI observed using a spin echo‐planar imaging (EPI) sequence revealed a heterogeneous response and significant increase in mean tumor signal intensity (SI) (ΔSI = 7%, P < 0.01). R measured by multigradient‐echo (MGRE) MRI decreased significantly in response to oxygen (mean ΔR = ?4 s?1; P < 0.05). A significant correlation was found between changes in mean tumor pO2 and mean EPI BOLD ΔSI accompanying oxygen breathing (r2 > 0.7, P < 0.001). Our results suggest that BOLD MRI provides information about tumor oxygenation and may be useful to predict pO2 changes accompanying interventions. Significantly, the magnitude of the BOLD response appears to be predictive for residual tumor HFs. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc. 相似文献
6.
Combined acquisition of gradient‐echo and spin‐echo signals in MRI time series reveals additional information for perfusion‐weighted imaging and functional MRI because of differences in the sensitivity of gradient‐echo and spin‐echo measurements to the properties of the underlying vascular architecture. The acquisition of multiple echo trains within one time frame facilitates the simultaneous estimation of the transversal relaxation parameters R2 and R. However, the simultaneous estimation of these parameters tends to be incorrect in the presence of slice profile mismatches between signal excitation and subsequent refocusing pulses. It is shown here that improvements in pulse design reduced R2 and R estimation errors. Further improvements were achieved by augmented parameter estimation through the introduction of an additional parameter δ to correct for discordances in slice profiles to facilitate more quantitative measurements. Moreover, the analysis of time‐resolved acquisitions revealed that the temporal stability of R2 estimates could be increased with improved pulse design, counteracting low contrast‐to‐noise ratios in spin‐echo‐based perfusion and functional MRI. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc. 相似文献
7.
Yuenan Wang Carmen J. Booth Hyeonjin Kim Maolin Qiu R. Todd Constable 《Magnetic resonance in medicine》2009,61(5):1185-1192
MRI has the potential of providing a noninvasive assessment of liver pathology. This work introduces a portal pressure gradient (PPG) model derived from fluid mechanics, where the PPG is proportional to the average velocity and inversely proportional to the vessel area in the upper part of portal vein. Using a phase‐contrast spoiled gradient echo sequence, the PPG model was verified in a phantom study and was tested in an animal study using 35 rats with various degrees of hepatic fibrosis induced by carbon tetrachloride (CCl4). Histological examination was conducted to determine the severity of hepatic fibrosis. The fibrosis score monotonically increased with the duration of CCl4 treatment. The PPG was highly correlated with nonzero fibrosis scores (r2 = 0.90, P < 0.05). There was a significant difference between control and cirrhosis groups (P < 0.0006, α < 0.0018). The difference between control and fibrosis (noncirrhosis) groups (P < 0.002, α < 0.006) was also significant. Without the administration of any contrast agent, the MRI‐PPG approach shows promise as a noninvasive means of evaluating liver fibrosis. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc. 相似文献
8.
Jensen LR Garzon B Heldahl MG Bathen TF Lundgren S Gribbestad IS 《Journal of magnetic resonance imaging : JMRI》2011,34(5):1099-1109
Purpose:
To use dynamic contrast‐enhanced (DCE) and diffusion‐weighted (DW) MRI at 3 Tesla (T) for early evaluation of treatment effects in breast cancer patients undergoing neoadjuvant chemotherapy (NAC), and assess the reliability of DW‐MRI.Materials and Methods:
DW‐ and DCE‐MRI acquisitions of 15 breast cancer patients were performed before and after one cycle of NAC. MRI tumor diameter and volume, apparent diffusion coefficient (ADC) and kinetic parameters (Ktrans, ve) were derived. The reliability of ADC before NAC was assessed. Changes in MRI parameters after NAC were analyzed, and logistic regression analysis was used to find the best predictors for pathologic response.Results:
The reliability for ADC values was high, with intraclass correlation coefficient of 0.84 (P = 0.001). After one cycle of NAC, MRI tumor diameter (8%, P = 0.005) and tumor volume (30%, P = 0.008) was reduced for all patients, while ADC mean values increased (0.12 mm2/s, P = 0.008). The best predictor for treatment response was a change in MRI tumor diameter with mean error rate of 0.167 (13% for responders, 5% for nonresponders, P = 0.291).Conclusion:
Changes in MRI derived tumor diameter and ADC after only one cycle of NAC could provide a valuable tool for early evaluation of treatment effects in breast cancer patients. J. Magn. Reson. Imaging 2011;. © 2011 Wiley Periodicals, Inc. 相似文献9.
Anderson SW Jara H Ozonoff A O'Brien M Hamilton JA Soto JA 《Journal of magnetic resonance imaging : JMRI》2012,35(1):140-146
Purpose:
To evaluate the effects of hepatic fibrosis on ADC and T2 values of ex vivo murine liver specimens imaged using 11.7 Tesla (T) MRI.Materials and Methods:
This animal study was IACUC approved. Seventeen male, C57BL/6 mice were divided into control (n = 2) and experimental groups (n = 15), the latter fed a 3, 5‐dicarbethoxy‐1, 4‐dihydrocollidine (DDC) supplemented diet, inducing hepatic fibrosis. Ex vivo liver specimens were imaged using an 11.7T MRI scanner. Spin‐echo pulsed field gradient and multi‐echo spin‐echo acquisitions were used to generate parametric ADC and T2 maps, respectively. Degrees of fibrosis were determined by the evaluation of a pathologist as well as digital image analysis. Scatterplot graphs comparing ADC and T2 to degrees of fibrosis were generated and correlation coefficients were calculated.Results:
Strong correlation was found between degrees of hepatic fibrosis and ADC with higher degrees of fibrosis associated with lower hepatic ADC values. Moderate correlation between hepatic fibrosis and T2 values was seen with higher degrees of fibrosis associated with lower T2 values.Conclusion:
Inverse relationships between degrees of fibrosis and both ADC and T2 are seen, highlighting the utility of these parameters in the ongoing development of an MRI methodology to quantify hepatic fibrosis. J. Magn. Reson. Imaging 2012;35:140‐146. © 2011 Wiley Periodicals, Inc. 相似文献10.
Julien Vautier Melanie Heilmann Christine Walczak Joël Mispelter Andreas Volk 《Magnetic resonance in medicine》2010,64(1):313-318
Dynamic contrast‐enhanced MRI is extensively studied to define and evaluate biomarkers for early assessment of vasculature‐targeting therapies. In this study, two‐dimensional and three‐dimensional radial multi‐gradient‐echo techniques for dynamic R*2‐corrected R1 mapping based on the spoiled gradient recalled signal equation were implemented and validated at 4.7 T. The techniques were evaluated on phantoms and on a respiratory motion animated tumor model. R1 measurements were validated with respect to a standard inversion‐recovery spin‐echo sequence in a four‐compartment phantom covering a range of relaxation rates typically found in tumor tissue. In the range of [0.4, 3] sec?1, R1 differences were less than 10% for both two‐dimensional and three‐dimensional experiments. A dynamic contrast‐enhanced MRI pilot study was performed on a colorectal tumor model subcutaneously implanted in mice at the abdominal level. Low motion sensitivity of radial acquisition allowed image recording without respiratory triggering. Three‐dimensional Ktrans maps and significantly different mean Ktrans values were obtained for two contrast agents with different molecular weights. The radial multi‐gradient‐echo approach should be most useful for preclinical experimental conditions where the tissue of interest experiences physiologic motion, like spontaneous extracerebral tumors developed by transgenic mice, and where dynamic contrast‐enhanced MRI is performed with high‐relaxivity contrast agents. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc. 相似文献
11.
Nicholas P. Blockley Ian D. Driver Susan T. Francis Joseph A. Fisher Penny A. Gowland 《Magnetic resonance in medicine》2011,65(5):1278-1286
This study aims to improve the method used to produce cerebrovascular reactivity (CVR) maps by MRI. Previous methods have used a standard boxcar presentation of carbon dioxide (CO2). Here this is replaced with a sinusoidally modulated CO2 stimulus. This allowed the use of Fourier analysis techniques to measure both the amplitude and phase delay of the BOLD CVR response, and hence characterize the arrival sequence of blood to different regions of the brain. This characterization revealed statistically significant relative delays between regions of the brain (ANOVA < 0.0001). In addition, post hoc comparison showed that the frontal (P < 0.001) and parietal (P = 0.004) lobes reacted earlier than the occipital lobe. Magn Reson Med, 2011. © 2010 Wiley‐Liss, Inc. 相似文献
12.
Yuji Shen Ida M. Pu Trevor Ahearn Matthew Clemence Christian Schwarzbauer 《Magnetic resonance in medicine》2013,69(6):1541-1552
Hypercapnia and hyperoxia give rise to vasodilation and vasoconstriction, respectively. This study investigates the influence of hypercapnia and hyperoxia on venous vessel size in the human brain. Venous vessel radii were measured in response to hypercapnia and hyperoxia. The venous vessel radii were determined by calculation of the changes in R2* and R2 that are induced by breathing 6% CO2 or pure oxygen. The experimental paradigm consisted of two 3‐min intervals of inhaling 6% CO2 or 100% O2 interleaved with three 2‐min intervals of breathing air. Hypercapnic and hyperoxic experiments were performed on eight subjects on a 3T scanner. Parametric maps of mean venous vessel radius were calculated from the changes in R2* and R2, which were measured by simultaneous acquisition of gradient‐echo and spin‐echo signals. The mean venous vessel radii in hypercapnia were 7.3 ± 0.3 μm in gray matter and 6.6 ± 0.5 μm in white matter. The corresponding vessel radii in hyperoxia were 5.6 ± 0.2 μm in gray matter and 5.4 ± 0.2 μm in white matter. These results show that the venous vessel radius was larger in hypercapnia than that in hyperoxia in both gray matter and white matter (P < 0.005), which agrees with the hypothesis that hypercapnia causes vasodilation and hyperoxia induces vasoconstriction. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc. 相似文献
13.
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.14.
Warren D. Foltz PhD Andy Wu BSc Peter Chung MD Charles Catton MD Andrew Bayley MD Michael Milosevic MD Robert Bristow MD Padraig Warde MD Anna Simeonov MSc David A. Jaffray PhD Masoom A. Haider MD Cynthia Ménard MD 《Journal of magnetic resonance imaging : JMRI》2013,37(4):909-916
Purpose:
To evaluate regional and temporal changes in apparent diffusion coefficient (ADC) and T2 relaxation during radiation therapy (RT) in patients with low and intermediate risk localized prostate cancer.Materials and Methods:
Seventeen patients enrolled on a prospective clinical trial where MRI was acquired every 2 weeks throughout eight weeks of image‐guided prostate IMRT (78 Gy/39 fractions). ADC and T2 quantification used entire prostate, central gland, benign peripheral zone, and tumor‐dense regions‐of‐interest, and mean values were evaluated for common response trends.Results:
Overall, the RT responses were greater than volunteer measurement repeatability, and week 6 appeared to be an optimum time‐point for early detection. RT effects on the entire prostate were best detected using ADC (5–7% by week 2, P < 0.0125), effects on peripheral zone were best detected using T2 (19% reduction at week 6; P = 0.004) and effects on tumors were best detected using ADC (14% elevation at week 6; P = 0.004).Conclusion:
ADC and T2 may be candidate biomarkers of early response to RT warranting further investigation against clinical outcomes. J. Magn. Reson. Imaging 2013;37:909–916. © 2012 Wiley Periodicals, Inc. 相似文献15.
Daniel Kim Jens H. Jensen Ed X. Wu Sujit S. Sheth Gary M. Brittenham 《Magnetic resonance in medicine》2009,62(2):300-306
Measurement of proton transverse relaxation rates (R2) is a generally useful means for quantitative characterization of pathological changes in tissue with a variety of clinical applications. The most widely used R2 measurement method is the Carr‐Purcell‐Meiboom‐Gill (CPMG) pulse sequence but its relatively long scan time requires respiratory gating for chest or body MRI, rendering this approach impractical for comprehensive assessment within a clinically‐acceptable examination time. The purpose of our study was to develop a breathhold multiecho fast spin‐echo (FSE) sequence for accurate measurement of R2 in the liver and heart. Phantom experiments and studies of subjects in vivo were performed to compare the FSE data with the corresponding even‐echo CPMG data. For pooled data, the R2 measurements were strongly correlated (Pearson correlation coefficient = 0.99) and in excellent agreement (mean difference [CPMG – FSE] = 0.10 s–1; 95% limits of agreement were 1.98 and –1.78 s–1) between the two pulse sequences. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc. 相似文献
16.
Ning Jin Zhuoli Zhang Longjiang Zhang Guangming Lu Andrew C. Larson 《Magnetic resonance in medicine》2011,66(1):207-212
Abdominal effective transverse relaxation rate (R2*) mapping is critical for a wide range of applications. However, respiratory motion can lead to significant image quality deterioration and R2* overestimation. For this work, we explored the feasibility of combining respiratory self‐gating techniques with a multiple gradient‐recalled echo sequence for free‐breathing abdominal R2* measurements. In a series of eight normal volunteers, respiratory self‐gated–multiple gradient‐recalled echo methods effectively avoided motion artifacts to produce quantitative R2* measurements in liver, spleen, and kidneys that were comparable to R2* measurements produced while breath‐holding. Respiratory self‐gated–multiple gradient‐recalled echo methods demonstrated the potential to avoid the need for breath‐holding during abdominal R2* mapping. For clinical application, respiratory self‐gated–multiple gradient‐recalled echo approaches could be particularly useful for R2* measurements in those patients unable or unwilling to sustain sufficiently long breath‐holds to avoid motion artifacts. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc. 相似文献
17.
Chao Xu Valerij G. Kiselev Harald E. Möller Jochen B. Fiebach 《Magnetic resonance in medicine》2013,69(4):981-991
Perfusion measurements using dynamic susceptibility contrast imaging provide additional information about the mean vessel size of microvasculature when supplemented with a dual gradient echo (GE) – spin echo (SE) contrast. Dynamic increase in the corresponding transverse relaxation rate constant changes, ΔR2GE and ΔR2SE, forms a loop on the (Δ, ΔR2GE) plane, rather than a reversible line. The shape of the loop and the direction of its passage differentiate between healthy brain and pathological tissue, such as tumour and ischemic tissue. By considering a tree model of microvasculature, the direction of the loop is found to be influenced mainly by the relative arterial and venous blood volume, as well as the tracer bolus dispersion. A parameter Λ is proposed to characterize the direction and shape of the loop, which might be considered as a novel imaging marker for describing the pathology of cerebrovascular network. Magn Reson Med 69:981–991, 2013. © 2012 Wiley Periodicals, Inc. 相似文献
18.
Kim HJ Kim TW Ryu SY Yang PS Kwon MJ Kim JC Lee YS Lee HJ Yang JH Kim JK Chung YA Oh EY Lee SB 《Clinical imaging》2011,35(6):413-420
Objectives
Acetazolamide-challenged perfusion magnetic resonance imaging (MRI) has been shown as a method for assessment of cerebrovascular reserve (CVR) capacity in patients with atherosclerotic steno-occlusive disease of internal carotid artery. We have assessed the feasibility of the acetazolamide-challenged perfusion MRI for evaluating CVR in symptomatic patients with severe middle cerebral artery (MCA) stenosis (≥70%) by comparison with the acetazolamide-challenged technetium-99m-hexamethylpropyleneamine oxime (HMPAO) single-photon emission computed tomography (SPECT).Methods
Seventeen prospectively enrolled patients with symptomatic unilateral MCA stenosis underwent technetium-99m-hexamethylpropyleneamine oxime SPECT and perfusion MRI without and with acetazolamide challenge, respectively. Acetazolamide-challenged SPECT and perfusion MRI were compared quantitatively by Region of interest (ROI) analysis.Results
At all ROIs, there were no significant differences in percent change between SPECT and perfusion MRI. Patients with impaired CVR showed significant decreases in the percent changes of respective cerebral blood flow (P=.016) and respective cerebral blood volume (P=.029).Conclusion
Acetazolamide-challenged perfusion MRI is feasible for evaluating CVR in symptomatic patients with severe MCA stenosis quantitatively. 相似文献19.
Bisdas S Nemitz O Berding G Weissenborn K Ahl B Becker H Donnerstag F 《European radiology》2006,16(10):2220-2228
Twelve patients with ICA stenosis underwent dynamic perfusion computed tomography (CT) and positron emission tomography (PET) studies at rest and after acetazolamide challenge. Cerebral blood flow (CBF) maps on perfusion CT resulted from a deconvolution of parenchymal time-concentration curves by an arterial input function (AIF) in the anterior cerebral artery as well as in both anterior choroidal arteries. CBF was measured by [15O]H2O PET using multilinear least-squares minimization procedure based on the one-compartment model. In corresponding transaxial PET scans, CBF values were extracted using standardized ROIs. The baseline perfusion CT-CBF values were lower in perfusion CT than in PET (P>0.05). CBF values obtained by perfusion CT were significantly correlated with those measured by PET before (P<0.05) and after (P<0.01) acetazolamide challenge. Nevertheless, the cerebrovascular reserve capacity was overestimated (P=0.05) using perfusion CT measurements. The AIF selection relative to the side of carotid stenosis did not significantly affect calculated perfusion CT-CBF values. In conclusion, the perfusion CT-CBF measurements correlate significantly with the PET-CBF measurements in chronic carotid stenotic disease and contribute useful information to the evaluation of the altered cerebral hemodynamics. 相似文献
20.
Damien Mandry MD Françoise Lapicque PhD Freddy Odille PhD Wassila Djaballah MD Andrei Codreanu MD Jean‐Marie Escanyé PhD Jacques Felblinger PhD Gilles Karcher MD Michel Claudon MD Pierre‐Yves Marie MD 《Journal of magnetic resonance imaging : JMRI》2009,29(1):78-85