Showing papers on "Perfusion scanning published in 2012"
TL;DR: Tenecteplase was associated with significantly better reperfusion and clinical outcomes than alteplase in patients with stroke who were selected on the basis of CT perfusion imaging.
Abstract: BackgroundIntravenous alteplase is the only approved treatment for acute ischemic stroke. Tenecteplase, a genetically engineered mutant tissue plasminogen activator, is an alternative thrombolytic agent. MethodsIn this phase 2B trial, we randomly assigned 75 patients to receive alteplase (0.9 mg per kilogram of body weight) or tenecteplase (0.1 mg per kilogram or 0.25 mg per kilogram) less than 6 hours after the onset of ischemic stroke. To favor the selection of patients most likely to benefit from thrombolytic therapy, the eligibility criteria were a perfusion lesion at least 20% greater than the infarct core on computed tomographic (CT) perfusion imaging at baseline and an associated vessel occlusion on CT angiography. The coprimary end points were the proportion of the perfusion lesion that was reperfused at 24 hours on perfusion-weighted magnetic resonance imaging and the extent of clinical improvement at 24 hours as assessed on the National Institutes of Health Stroke Scale (NIHSS, a 42-point scale ...
527 citations
TL;DR: SPECT is widely available and most extensively validated; PET achieved the highest diagnostic performance; CMR may provide an alternative without ionizing radiation and a similar diagnostic accuracy as PET.
412 citations
TL;DR: Rb-82 PET is accurate for the detection of obstructive CAD and, despite advances in SPECT technology, remains superior and more widespread use of Rb- 82 PET may be beneficial to improve CAD detection.
289 citations
Book•
12 Feb 2012
TL;DR: E Echo-Planar Magnetic Resonance Imaging of Human Brain Activation and its Applications: Clinical Applications of Neuroimaging Using Echo- planar Imaging and Research Issues using Echo-planar Imaging for Functional Brain Imaging.
Abstract: 1. The Historical Development of Echo-Planar Magnetic Resonance Imaging.- 2. Theory of Echo-Planar Imaging.- 3. Echo-Planar Imaging Hardware.- 4. Echo-Planar Imaging Pulse Sequences.- 5. Echo-Planar Image Reconstruction.- 6. Echo-Planar Imaging Image Artifacts.- 7. Physiological Side Effects of Fast Gradient Switching.- 8. Echo-Planar Imaging Angiography.- 9. Diffusion Imaging with Echo-Planar Imaging.- 10. Echo-Planar Imaging of the Abdomen.- 11. Abdominal Diffusion Imaging Using Echo-Planar Imaging.- 12. Echo-Planar Imaging of the Heart.- 13. Perfusion Imaging with Echo-Planar Imaging.- 14. Clinical Applications of Neuroimaging Using Echo-Planar Imaging.- 15. Echo-Planar Magnetic Resonance Imaging of Human Brain Activation.- 16. Research Issues Using Echo-Planar Imaging for Functional Brain Imaging.- 17. Echo-Planar Imaging on Small-Bore Systems.- 18. Echo-Planar Imaging-Hybrids: Single Shot RARE.- 19. Echo-Planar Imaging-Hybrids: Turbo Spin-Echo Imaging.- 20. Echo-Planar Imaging-Hybrids: Gradient and Spin-Echo (GRASE) Imaging.- 21. Spiral Echo-Planar Imaging.
226 citations
TL;DR: There is good correlation between CMR(CMR) and MPR(PET), and for the detection of significant CAD, M PR(PET) and CMR seem comparable and very accurate; therefore, although quantitative CMR is clinically useful, further refinements are still required.
220 citations
TL;DR: Quantitative CTP mismatch classification using relCBF and Tmax is similar to perfusion-diffusion MRI, and the greater accessibility of CTP may facilitate generalizability of mismatch-based selection in clinical practice and trials.
Abstract: Background and Purpose—Perfusion imaging has the potential to select patients most likely to respond to thrombolysis. We tested the correspondence of computed tomography perfusion (CTP)-derived mismatch with contemporaneous perfusion-diffusion magnetic resonance imaging (MRI). Methods—Acute ischemic stroke patients 3 to 6 hours after onset had CTP and perfusion-diffusion MRI within 1 hour, before thrombolysis. Relative cerebral blood flow (relCBF) and time to peak of the deconvolved tissue residue function (Tmax) were calculated. The diffusion lesion (diffusion-weighted imaging) was registered to the CTP slabs and manually outlined to its maximal visual extent. Volumetric accuracy of CT-relCBF infarct core (compared with diffusion-weighted imaging) was tested. To reduce false-positive low CBF regions, relCBF core was restricted to voxels within a relative time-to-peak (relTTP) >4 seconds for lesion region of interest. The MR-Tmax >6 seconds perfusion lesion was automatically segmented and registered to CT...
190 citations
TL;DR: The frequency and implications for mismatch classification of DLR are investigated using imaging from the EPITHET and DEFUSE studies and the impact of adjusting baseline diffusion lesion volume for DLR volume on perfusion-diffusion mismatch analyzed.
Abstract: Diffusion-weighted imaging (DWI) is commonly used to assess irreversibly infarcted tissue but its accuracy is challenged by reports of diffusion lesion reversal (DLR). We investigated the frequency and implications for mismatch classification of DLR using imaging from the EPITHET (Echoplanar Imaging Thrombolytic Evaluation Trial) and DEFUSE (Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evolution) studies. In 119 patients (83 treated with IV tissue plasminogen activator), follow-up images were coregistered to acute diffusion images and the lesions manually outlined to their maximal visual extent in diffusion space. Diffusion lesion reversal was defined as voxels of acute diffusion lesion that corresponded to normal brain at follow-up (i.e., final infarct, leukoaraiosis, and cerebrospinal fluid (CSF) voxels were excluded from consideration). The appearance of DLR was visually checked for artifacts, the volume calculated, and the impact of adjusting baseline diffusion lesion volume for DLR volume on perfusion-diffusion mismatch analyzed. Median DLR volume reduced from 4.4 to 1.5 mL after excluding CSF/leukoaraiosis. Visual inspection verified 8/119 (6.7%) with true DLR, median volume 2.33 mL. Subtracting DLR from acute diffusion volume altered perfusion-diffusion mismatch (T(max)>6 seconds, ratio>1.2) in 3/119 (2.5%) patients. Diffusion lesion reversal between baseline and 3 to 6 hours DWI was also uncommon (7/65, 11%) and often transient. Clinically relevant DLR is uncommon and rarely alters perfusion-diffusion mismatch. The acute diffusion lesion is generally a reliable signature of the infarct core.
187 citations
TL;DR: Intravoxel Incoherent Motion MR imaging was found to be a valid and promising method to quantify brain perfusion in humans and the IVIM perfusion parameters were reactive to hyperoxygenation-induced vasoconstriction and hypercapnia- induced vasodilatation.
Abstract: The results of this study validate the use of intravoxel incoherent motion MR imaging to measure perfusion in the human brain and demonstrate that perfusion fraction, pseudodiffusion coefficient, and blood flow–related perfusion fraction change gradually under hypercapnia and hyperoxygenation in the full brain and in smaller regions of interest.
173 citations
TL;DR: The findings imply that CBF and blood transit times are compromised in aging, and these changes together with differences between genders should be taken into account when studying brain perfusion.
Abstract: Normal aging is associated with diminished brain perfusion measured as cerebral blood flow (CBF), but previously it is difficult to accurately measure various aspects of perfusion hemodynamics including: bolus arrival times and delays through small arterioles, expressed as arterial-arteriole transit time. To study hemodynamics in greater detail, volumetric arterial spin labeling MRI with variable postlabeling delays was used together with a distributed, dual-compartment tracer model. The main goal was to determine how CBF and other perfusion hemodynamics vary with aging. Twenty cognitive normal female and 15 male subjects (age: 23–84 years old) were studied at 4 T. Arterial spin labeling measurements were performed in the posterior cingulate cortex, precuneus, and whole brain gray matter. CBF declined with advancing age (P < 0.001). Separately from variations in bolus arrival times, arterial-arteriole transit time increased with advancing age (P < 0.01). Finally, women had overall higher CBF values (P < 0.01) and shorter arterial-arteriole transit time (P < 0.01) than men, regardless of age. The findings imply that CBF and blood transit times are compromised in aging, and these changes together with differences between genders should be taken into account when studying brain perfusion. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
160 citations
TL;DR: As a rapid, noninvasive, and quantitative technique, ASL has clinical use in detecting blood flow abnormalities in patients with AIS and provided largely consistent results in delineating hypoperfused brain regions in AIS.
Abstract: Background and Purpose—The purpose of this study was to evaluate the potential clinical value of arterial spin-labeled (ASL) perfusion MRI in acute ischemic stroke (AIS) through comparison with dynamic susceptibility contrast (DSC) enhanced perfusion MRI. Methods—Pseudocontinuous ASL with 3-dimensional background-suppressed gradient and spin echo readout was applied with DSC perfusion MRI on 26 patients with AIS. ASL cerebral blood flow and multiparametric DSC perfusion maps were rated for image quality and lesion severity/conspicuity. Mean ASL cerebral blood flow and DSC perfusion values were obtained in main vascular territories. Kendall coefficient of concordance was calculated to evaluate the reliability of ratings. Spearman correlation coefficients were calculated to compare ratings and quantitative perfusion values between ASL and DSC perfusion maps. Results—ASL cerebral blood flow and DSC perfusion maps provided largely consistent results in delineating hypoperfused brain regions in AIS. Hyperemic ...
153 citations
TL;DR: DECT is able to identify pulmonary perfusion defects with good accuracy and may potentially enhance the diagnostic accuracy in the assessment of PE.
TL;DR: In advanced HCC, CTP is a more sensitive image biomarker for monitoring early antiangiogenic treatment effects as well as in predicting outcome at the end of treatment and progression-free survival as compared with RECIST and tumor density.
Abstract: Purpose:Our aim was to investigate the hypothesis that the CT perfusion (CTP) is a more sensitive image biomarker when compared with tumor burden (Response Evaluation Criteria in Solid Tumors [RECIST]) and tumor density (HU) for monitoring treatment changes and for predicting long-term outcome in ad
TL;DR: Results in normal volunteers demonstrate heterogeneity of transit delay across different brain regions that lead to quantification errors without the transit maps and demonstrate the feasibility of the proposed reduced spatial resolution arterial spin labeling prescan approach to perfusion and transit delay quantification.
Abstract: Arterial spin labeling perfusion MRI can suffer from artifacts and quantification errors when the time delay between labeling and arrival of labeled blood in the tissue is uncertain. This transit delay is particularly uncertain in broad clinical populations, where reduced or collateral flow may occur. Measurement of transit delay by acquisition of the arterial spin labeling signal at many different time delays typically extends the imaging time and degrades the sensitivity of the resulting perfusion images. Acquisition of transit delay maps at the same spatial resolution as perfusion images may not be necessary, however, because transit delay maps tend to contain little high spatial resolution information. Here, we propose the use of a reduced spatial resolution arterial spin labeling prescan for the rapid measurement of transit delay. Approaches to using the derived transit delay information to optimize and quantify higher resolution continuous arterial spin labeling perfusion images are described. Results in normal volunteers demonstrate heterogeneity of transit delay across different brain regions that lead to quantification errors without the transit maps and demonstrate the feasibility of this approach to perfusion and transit delay quantification.
TL;DR: In suspected coronary artery disease, combined coronary CTA + CTP identifies patients with hemodynamically significant stenoses with >90% accuracy compared with FFR.
Abstract: Objectives We sought to determine the accuracy of combined coronary computed tomography angiography (CTA) and computed tomography stress myocardial perfusion imaging (CTP) in the detection of hemodynamically significant stenoses using fractional flow reserve (FFR) as a reference standard in patients with suspected coronary artery disease. Background CTP can be qualitatively assessed by visual interpretation or quantified by the transmural perfusion ratio determined as the ratio of subendocardial to subepicardial contrast attenuation. The incremental value of each technique in addition to coronary CTA to detect hemodynamically significant stenoses is not known. Methods Forty symptomatic patients underwent FFR and 320-detector computed tomography assessment including coronary CTA and CTP. Myocardial perfusion was assessed using the transmural perfusion ratio and visual perfusion assessment. Computed tomography images were assessed by consensus of 2 observers. Transmural perfusion ratio Results Coronary CTA detected FFR-significant stenoses with 95% sensitivity and 78% specificity. The additional use of visual perfusion assessment and the transmural perfusion ratio both increased the specificity to 95%, with sensitivity of 87% and 71%, respectively. The area under the receiver-operating characteristic curve for coronary CTA + visual perfusion assessment was significantly higher than both coronary CTA (0.93 vs. 0.85, p = 0.0003) and coronary CTA + the transmural perfusion ratio (0.93 vs. 0.79, p = 0.0003). Per-vessel and per-patient accuracy for coronary CTA, coronary CTA + the transmural perfusion ratio, and coronary CTA + visual perfusion assessment was 83% and 83%, 87% and 92%, and 92% and 95%, respectively. Conclusions In suspected coronary artery disease, combined coronary CTA + CTP identifies patients with hemodynamically significant stenoses with >90% accuracy compared with FFR. When interpreted with coronary CTA, visual perfusion assessment provided superior incremental value in the detection of FFR-significant stenoses compared with the quantitative transmural perfusion ratio assessment.
TL;DR: Compared to MRI and SPECT both, dynamic real-time perfusion CT and first-pass dual-energy perfusions CT showed good agreement for the detection of myocardial perfusion defects.
TL;DR: Adenosine-stress CT perfusion detects myocardial perfusion defects in good correlation with nuclear MPI and improves the diagnostic accuracy for identifying flow-obstructing stenosis compared with CTA alone.
Abstract: OBJECTIVE. The purpose of this article is to evaluate the feasibility of adenosine-stress dynamic myocardial perfusion imaging (MPI) with 128-MDCT dual-source CT for detecting myocardial ischemia in comparison with conventional catheter coronary angiography and nuclear MPI. SUBJECTS AND METHODS. Thirty patients (21 men and nine women; mean [± SD] age, 59.2 ± 7.6 years) prospectively underwent a combined stress CT perfusion and CT angiography (CTA) examination. Complete time-attenuation curves of the myocardium were acquired with prospectively ECG-triggered axial images at two alternating positions. Myocardial blood flow (MBF) was quantified according to dynamic CT perfusion, and MBF values of normal and abnormal segments were compared. Findings on CT perfusion were compared with those for stress and rest SPECT. Perfusion defects according to CT were correlated to flow-obstructing stenosis detected on CTA and catheter coronary angiography. RESULTS. On stress CT perfusion, 19 patients (63%) and 83 of 504 se...
TL;DR: In this article, the authors evaluated quantification of myocardial blood flow at a pixel level based on contrastenhanced first-pass cardiac magnetic resonance (CMR) imaging in dogs and in patients.
Abstract: Objectives The aim of this study was to evaluate fully quantitative myocardial blood flow (MBF) at a pixel level based on contrast-enhanced first-pass cardiac magnetic resonance (CMR) imaging in dogs and in patients. Background Microspheres can quantify MBF in subgram regions of interest, but CMR perfusion imaging may be able to quantify MBF and differentiate blood flow at a much higher resolution. Methods First-pass CMR perfusion imaging was performed in a dog model with local hyperemia induced by intracoronary adenosine. Fluorescent microspheres were the reference standard for MBF validation. CMR perfusion imaging was also performed on patients with significant coronary artery disease (CAD) by invasive coronary angiography. Myocardial time-signal intensity curves of the images were quantified on a pixel-by-pixel basis using a model-constrained deconvolution analysis. Results Qualitatively, color CMR perfusion pixel maps were comparable to microsphere MBF bull's-eye plots in all animals. Pixel-wise CMR MBF estimates correlated well against subgram (0.49 ± 0.14 g) microsphere measurements (r = 0.87 to 0.90) but showed minor underestimation of MBF. To reduce bias due to misregistration and minimize issues related to repeated measures, 1 hyperemic and 1 remote sector per animal were compared with the microsphere MBF, which improved the correlation (r = 0.97 to 0.98), and the bias was close to zero. Sector-wise and pixel-wise CMR MBF estimates also correlated well (r = 0.97). In patients, color CMR stress perfusion pixel maps showed regional blood flow decreases and transmural perfusion gradients in territories served by stenotic coronary arteries. MBF estimates in endocardial versus epicardial subsectors, and ischemic versus remote sectors, were all significantly different (p Conclusions Myocardial blood flow can be quantified at the pixel level (∼32 μl of myocardium) on CMR perfusion images, and results compared well with microsphere measurements. High-resolution pixel-wise CMR perfusion maps can quantify transmural perfusion gradients in patients with CAD.
TL;DR: 3D whole heart myocardial perfusion CMR accurately detects functionally significant CAD as defined by using FFR and provides an assessment of ischemic burden in agreement with the invasive DJS and holds promise for noninvasive guidance of therapy and risk stratification of patients with CAD.
TL;DR: In this article, the authors retrospectively reviewed all cases in which NIRS measurements were obtained at a single, academic neurointensive care unit from February 2008 to June 2011 in which CT perfusion was performed at the same time as NIRs data was collected.
Abstract: Object Near-infrared spectroscopy (NIRS) offers noninvasive bedside measurement of direct regional cerebral arteriovenous (mixed) brain oxygenation. To validate the accuracy of this monitoring technique, the authors analyzed the statistical correlation of NIRS and CT perfusion with respect to regional cerebral blood flow (CBF) measurements. Methods The authors retrospectively reviewed all cases in which NIRS measurements were obtained at a single, academic neurointensive care unit from February 2008 to June 2011 in which CT perfusion was performed at the same time as NIRS data was collected. Regions of interest were obtained 2.5 cm below the NIRS bifrontal scalp probe on CT perfusion with an average volume between 2 and 4 ml, with mean CBF values used for purposes of analysis. Linear regression analysis was performed for NIRS and CBF values. Results The study included 8 patients (2 men, 6 women), 6 of whom suffered subarachnoid hemorrhage, 1 ischemic stroke, and 1 intracerebral hemorrhage and brain edema....
TL;DR: Findings related to the physiological origins and electrical characteristics of the perfusion impedance change signal are summarized, highlighting properties that are particularly relevant to EIT.
Abstract: Although electrical impedance tomography (EIT) for ventilation monitoring is on the verge of clinical trials, pulmonary perfusion imaging with EIT remains a challenge, especially in spontaneously breathing subjects. In anticipation of more research on this subject, we believe a thorough review is called for. In this paper, findings related to the physiological origins and electrical characteristics of this signal are summarized, highlighting properties that are particularly relevant to EIT. The perfusion impedance change signal is significantly smaller in amplitude compared with the changes due to ventilation. Therefore, the hardware used for this purpose must be more sensitive and more resilient to noise. In previous works, some signal- or image-processing methods have been required to separate these two signals. Three different techniques are reviewed in this paper, including the ECG-gating method, frequency-domain-filtering-based methods and a principal-component-analysis-based method. In addition, we review a number of experimental studies on both human and animal subjects that employed EIT for perfusion imaging, with promising results in the diagnosis of pulmonary embolism (PE) and pulmonary arterial hypertension as well as other potential applications. In our opinion, PE is most likely to become the main focus for perfusion EIT in the future, especially for heavily instrumented patients in the intensive care unit (ICU).
TL;DR: The data imply that PASL may be a valuable instrument for investigating perfusion changes in the transition from normal aging to dementia and indicate that it might become an alternative to nuclear imaging techniques in AD diagnostics.
Abstract: Alzheimer's disease (AD) and mild cognitive impairment (MCI), the transitional clinical stage between cognition in normal aging and dementia, have been linked to abnormalities in brain perfusion. Pulsed arterial spin labeling (PASL) is a magnetic resonance imaging (MRI) technique for evaluating brain perfusion. The present study aimed to determine regional perfusion abnormalities in 19 patients with mild dementia in AD and 24 patients with MCI as compared to 24 cognitively healthy elderly controls using PASL. In line with nuclear imaging methods, lower perfusion in patients with MCI and AD was found mainly in the parietal lobe, but also in angular and middle temporal areas as well as in the left middle occipital lobe and precuneus. Our data imply that PASL may be a valuable instrument for investigating perfusion changes in the transition from normal aging to dementia and indicate that it might become an alternative to nuclear imaging techniques in AD diagnostics.
TL;DR: The findings show that a fast 2½-minute ASL perfusion scan may be adequate for screening patients with acute stroke with contraindications to gadolinium-based contrast agents.
Abstract: Background and Purpose—Perfusion MRI can be used to identify patients with acute ischemic stroke who may benefit from reperfusion therapies. The risk of nephrogenic systemic fibrosis, however, limi...
TL;DR: The goal of this review is to give an overview of the techniques most commonly in use for physiological experiments along with the issues unique to each technique.
Abstract: From the first measurements of the distribution of pulmonary blood flow using radioactive tracers by West and colleagues (J Clin Invest 40: 1–12, 1961) allowing gravitational differences in pulmona...
TL;DR: The results suggest that CT-p can help in non-invasive quantification of tumour blood supply, related to the formation of new arterial structures (neoangiogenesis), which are essential for tumour growth.
Abstract: To determine the value of perfusion computed tomography (CT-p) in the quantitative assessment of tumour-related neoangiogenesis processes in patients with hepatocellular carcinoma (HCC). Fifty-two biopsy proven HCC lesions were examined with dynamic CT investigations during injection of 50 mL of contrast agent (350 mgI/mL). A dedicated perfusion software which generated a quantitative map of arterial and portal perfusion by means of a colour scale was employed. The following parameters related to the blood microcirculation and tissue perfusion were calculated: hepatic perfusion (Perf), tissue blood volume (BV), hepatic perfusion index (HPI), arterial perfusion (AP), portal perfusion (PP), and time to peak (TTP). Perfusion parameters were statistically analysed, comparing neoplastic lesions with cirrhotic parenchyma. Perf, BV, HPI and AP values were higher (P < 0.001), whereas PP and TTP were lower (P < 0.001) in HCC relative to the surrounding liver. No significant correlation was found between perfusion parameters and HCC grade. Values of perfusion parameters in the cirrhotic liver of patients with and without HCC were not significantly different. Our results suggest that CT-p can help in non-invasive quantification of tumour blood supply, related to the formation of new arterial structures (neoangiogenesis), which are essential for tumour growth. • Perfusion computed tomography (CT) enables depiction of tumour vascular physiology
• Perfusion CT is non-invasive and is now quick to perform and analyse
• Quantitative measurements of hepatic perfusion provide important information about hepatocellular carcinoma (HCC)
• Such perfusion CT data may help in the determination of the outcome of HCC.
• Perfusion CT can act as an in-vivo biomarker of tumour-related angiogenesis.
TL;DR: This is the first report describing quantification of foot perfusion before and after lower extremity revascularization for severe limb ischemia and ICGA provides rapid visual and quantitative information about regional foot perfusions.
TL;DR: Mismatch classification based on ASL and PWI agrees frequently but not perfectly; ASL tends to overestimate the PWI time to maximum lesion volume, and improved ASL methodologies and higher field strength are necessary before ASL can be recommended for routine use in acute stroke.
Abstract: Background and Purpose—The perfusion-weighted imaging (PWI)–diffusion-weighted imaging (DWI) mismatch paradigm is widely used in stroke imaging studies. Arterial spin labeling (ASL) is an alternati...
TL;DR: MR INFORM will assess whether an initial strategy of CMR perfusion is non-inferior to invasive angiography supplemented by FFR measurements to guide the management of patients with stable coronary artery disease.
Abstract: In patients with stable coronary artery disease (CAD), decisions regarding revascularisation are primarily driven by the severity and extent of coronary luminal stenoses as determined by invasive coronary angiography. More recently, revascularisation decisions based on invasive fractional flow reserve (FFR) have shown improved event free survival. Cardiovascular magnetic resonance (CMR) perfusion imaging has been shown to be non-inferior to nuclear perfusion imaging in a multi-centre setting and superior in a single centre trial. In addition, it is similar to invasively determined FFR and therefore has the potential to become the non-invasive test of choice to determine need for revascularisation. The MR-INFORM study is a prospective, multi-centre, randomised controlled non-inferiority, outcome trial. The objective is to compare the efficacy of two investigative strategies for the management of patients with suspected CAD. Patients presenting with stable angina are randomised into two groups: 1) The FFR-INFORMED group has subsequent management decisions guided by coronary angiography and fractional flow reserve measurements. 2) The MR-INFORMED group has decisions guided by stress perfusion CMR. The primary end-point will be the occurrence of major adverse cardiac events (death, myocardial infarction and repeat revascularisation) at one year. Clinical trials.gov identifier NCT01236807. MR INFORM will assess whether an initial strategy of CMR perfusion is non-inferior to invasive angiography supplemented by FFR measurements to guide the management of patients with stable coronary artery disease. Non-inferiority of CMR perfusion imaging to the current invasive reference standard (FFR) would establish CMR perfusion imaging as an attractive non-invasive alternative to current diagnostic pathways.
TL;DR: ADMSCs have a therapeutic effect against CCl4-mediated liver fibrosis, evidenced by CT perfusion scan and down-regulation of VEGF, and may benefit the fibrotic liver through alteration of microcirculation.
Abstract: Adipose derived mesenchymal stem cells (ADMSCs), carrying the similar characteristics to bone marrow mesenchymal stem cells, only much more abundant and easier to obtain, may be a promising treatment for liver fibrosis. We aim to investigate the therapeutic potential of ADMSCs transplantation in liver fibrosis caused by carbon tetrachloride (CCl4) in rats as well as its underlying mechanism, and to further explore the appropriate infusion pathway. ADMSCs were isolated, cultured and identified. Placebo and ADMSCs were transplanted via portal vein and tail vein respectively into carbon tetrachloride (CCl4)-induced liver fibrosis rats. Computed tomography (CT) perfusion scan and microvessel counts were performed to measure the alteration of liver microcirculation after therapy. Liver function tests and histological findings were estimated. CT perfusion scan shown significant decrease of hepatic arterial perfusion index, significant increased portal vein perfusion, total liver perfusion in rats receiving ADMSCs from portal vein, and Factor VIII (FVIII) immunohistochemical staining shown significant decrease of microvessels in rats receiving ADMSCs from portal vein, indicating microcirculation improvement in portal vein group. Vascular endothelial growth Factor (VEGF) was significantly up-regulated in fibrosis models, and decreased after ADMSCs intraportal transplantation. A significant improvement of liver functional test and histological findings in portal vein group were observed. No significance was found in rats receiving ADMSCs from tail vein. ADMSCs have a therapeutic effect against CCl4-mediated liver fibrosis. ADMSCs may benefit the fibrotic liver through alteration of microcirculation, evidenced by CT perfusion scan and down-regulation of VEGF. Intraportal transplantation is a better pathway than tail vein transplantation.
TL;DR: Three-dimensional CMR stress perfusion provided high diagnostic accuracy for the detection of functionally significant CAD and myocardial ischaemic burden measurements were highly reproducible and allowed the assessment of CAD severity.
Abstract: Aims Dynamic three-dimensional-cardiac magnetic resonance (3D-CMR) perfusion proved highly diagnostic for the detection of angiographically defined coronary artery disease (CAD) and has been used to assess the efficacy of coronary stenting procedures. The present study aimed to relate significant coronary lesions as assessed by fractional flow reserve (FFR) to the volume of myocardial hypoenhancement on 3D-CMR adenosine stress perfusion imaging and to define the inter-study reproducibility of stress inducible 3D-CMR hypoperfusion.
Methods and results A total of 120 patients with known or suspected CAD were examined in two CMR centres using 1.5 T systems. The protocol included cine imaging, 3D-CMR perfusion during adenosine infusion, and at rest followed by delayed enhancement (DE) imaging. Fractional flow reserve was recorded in epicardial coronary arteries and side branches with ≥2 mm luminal diameter and >40% severity stenosis (pathologic FFR < 0.75). Twenty-five patients underwent an identical repeat CMR examination for the determination of inter-study reproducibility of 3D-CMR perfusion deficits induced by adenosine. Three-dimensional CMR perfusion scans were visually classified as pathologic if one or more segments showed an inducible perfusion deficit in the absence of DE. Myocardial ischaemic burden (MIB) was measured by segmentation of the area of inducible hypoenhancement and normalized to left ventricular myocardial volume (MIB, %). Three-dimensional CMR perfusion resulted in a sensitivity, specificity, and diagnostic accuracy of 90, 82, and 87%, respectively. Substantial concordance was found for inter-study reproducibility [Lin's correlation coefficient: 0.98 (95% confidence interval: 0.96–0.99)].
Conclusion Three-dimensional CMR stress perfusion provided high diagnostic accuracy for the detection of functionally significant CAD. Myocardial ischaemic burden measurements were highly reproducible and allowed the assessment of CAD severity.
TL;DR: Perfusion MRI of rectal cancer can be useful for assessing tumoural Ktrans changes by CRT, and tumours with high pre-CRT Ktrans values tended to respond favourably toCRT, particularly in terms of downstaging criteria.
Abstract: To evaluate the utility of perfusion MRI as a potential biomarker for predicting response to chemoradiotherapy (CRT) in locally advanced rectal cancer. Thirty-nine patients with primary rectal carcinoma who were scheduled for preoperative CRT were prospectively recruited. Perfusion MRI was performed with a 3.0-T MRI system in all patients before therapy, at the end of the 2nd week of therapy, and before surgery. The K
trans (volume transfer constant) and V
e (extracellular extravascular space fraction) were calculated. Before CRT, the mean tumour K
trans in the downstaged group was significantly higher than that in the non-downstaged group (P = 0.0178), but there was no significant difference between tumour regression grade (TRG) responders and TRG non-responders (P = 0.1392). Repeated-measures analysis of variance (ANOVA) showed significant differences for evolution of K
trans values both between downstaged and non-downstaged groups (P = 0.0215) and between TRG responders and TRG non-responders (P = 0.0001). Regarding V
e, no significant differences were observed both between downstaged and non-downstaged groups (P = 0.689) or between TRG responders and TRG non-responders (P = 0.887). Perfusion MRI of rectal cancer can be useful for assessing tumoural K
trans changes by CRT. Tumours with high pre-CRT K
trans values tended to respond favourably to CRT, particularly in terms of downstaging criteria. • Perfusion MRI can now assess therapeutic response of tumours to therapy. • Tumours with high initial
K
trans
values responded favourably to chemoradiotherapy. • Perfusion MRI of rectal cancer may help with decisions about management.