Showing papers on "Perfusion scanning published in 2009"
TL;DR: The basics of T2* relaxation, T1*-weighted sequences, and their clinical applications are presented, followed by the principles, techniques, and clinical uses of four T2*,-based applications, including SW imaging, perfusion MR imaging, functional MR Imaging, and iron overload imaging.
Abstract: T2* relaxation refers to decay of transverse magnetization caused by a combination of spin-spin relaxation and magnetic fi eld inhomogeneity. T2* relaxation is seen only with gradient-echo (GRE) imaging because transverse relaxation caused by magnetic fi eld inhomogeneities is eliminated by the 180° pulse at spin-echo imaging. T2* relaxation is one of the main determinants of image contrast with GRE sequences and forms the basis for many magnetic resonance (MR) applications, such as susceptibility-weighted (SW) imaging, perfusion MR imaging, and functional MR imaging. GRE sequences can be made predominantly T2* weighted by using a low fl ip angle, long echo time, and long repetition time. GRE sequences with T2*-based contrast are used to depict hemorrhage, calcifi cation, and iron deposition in various tissues and lesions. SW imaging uses phase information in addition to T2*-based contrast to exploit the magnetic susceptibility differences of the blood and of iron and calcifi cation in various tissues. Perfusion MR imaging exploits the signal intensity decrease that occurs with the passage of a high concentration of gadopentetate dimeglumine through the microvasculature. Change in oxygen saturation during specifi c tasks changes the local T2*, which leads to the blood oxygen level–dependent effect seen at functional MR imaging. The basics of T2* relaxation, T2*-weighted sequences, and their clinical applications are presented, followed by the principles, techniques, and clinical uses of four T2*-based applications, including SW imaging, perfusion MR imaging, functional MR imaging, and iron overload imaging.
588 citations
TL;DR: In patients with proximal vessel occlusion, perfusion computed tomography mismatch is a prerequisite for a favourable clinical response, but good collateral status appears a critical determinant of ultimate outcome, particularly if major reperfusion occurs.
Abstract: It is unknown whether collateral vessel status, as seen on computed tomography angiography, can predict the fate of penumbral tissue identified on perfusion computed tomography and thereby influence clinical outcome. We tested this hypothesis in consecutive patients who underwent perfusion computed tomography/computed tomography angiography within 6 h of anterior circulation stroke, who also had repeat perfusion/infarct volume imaging at 24 h, and modified Rankin Scale at 3 months. Collateral status was graded as good or reduced depending on the extent of contrast visualized distal to the occlusion on computed tomography angiography. 'Perfusion computed tomography mismatch' ratio was calculated from the ratio of the mean transit time lesion/cerebral blood volume lesion. Of 92 patients with proximal intracranial vessel occlusion, good collateral status (51/92) was significantly associated with reduced infarct expansion and more favourable functional outcomes (modified Rankin Scale 0-2). Significant univariate predictors of favourable outcome were good collateral status, major reperfusion at 24 h, presence of perfusion computed tomography mismatch (for a range of ratios: > or = 1.2, > or = 2, > or = 3, > or = 3.5) and baseline National Institutes of Health Stroke Scale score. Notably, none of the 37 patients with a perfusion computed tomography mismatch ratio < 3.0 had a favourable outcome. In patients with perfusion computed tomography mismatch, significant independent predictors of favourable outcome were good collateral status, major reperfusion and baseline National Institutes of Health Stroke Scale score. There was also a strong interaction between major reperfusion and good collateral status in the regression models. In patients with proximal vessel occlusion, perfusion computed tomography mismatch is a prerequisite for a favourable clinical response, but good collateral status appears a critical determinant of ultimate outcome, particularly if major reperfusion occurs.
411 citations
TL;DR: Adenosine stress CT can identify stress-induced myocardial perfusion defects with diagnostic accuracy comparable to SPECT, with similar radiation dose and with the advantage of providing information on coronary stenosis.
369 citations
TL;DR: Findings suggest that DSC perfusion MR imaging may be used to differentiate recurrent GBM from EBRT-induced radiation necrosis.
Abstract: In this study, we showed that quantitative measurement of hemodynamic values derived from T2*-weighted dynamic susceptibility-weighted contrast material–enhanced MR imaging results can be used to distinguish recurrent glioblastoma multiforme from external beam radiation therapy–induced necrosis.
343 citations
TL;DR: Image-guided neuronavigation during surgical resection of MR imaging lesions to correlate directly specimen histopathology with localized dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging measurements and to establish accurate rCBV threshold values, which differentiate PTRE from tumor recurrence are established.
Abstract: BACKGROUND AND PURPOSE: Differentiating tumor growth from posttreatment radiation effect (PTRE) remains a common problem in neuro-oncology practice. To our knowledge, useful threshold relative cerebral blood volume (rCBV) values that accurately distinguish the 2 entities do not exist. Our prospective study uses image-guided neuronavigation during surgical resection of MR imaging lesions to correlate directly specimen histopathology with localized dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging (DSC) measurements and to establish accurate rCBV threshold values, which differentiate PTRE from tumor recurrence. MATERIALS AND METHODS: Preoperative 3T gradient-echo DSC and contrast-enhanced stereotactic T1-weighted images were obtained in patients with high-grade glioma (HGG) previously treated with multimodality therapy. Intraoperative neuronavigation documented the stereotactic location of multiple tissue specimens taken randomly from the periphery of enhancing MR imaging lesions. Coregistration of DSC and stereotactic images enabled calculation of localized rCBV within the previously recorded specimen locations. All tissue specimens were histopathologically categorized as tumor or PTRE and were correlated with corresponding rCBV values. All rCBV values were T1-weighted leakage-corrected with preload contrast-bolus administration and T2/T2*-weighted leakage-corrected with baseline subtraction integration. RESULTS: Forty tissue specimens were collected from 13 subjects. The PTRE group (n = 16) rCBV values ranged from 0.21 to 0.71, tumor (n = 24) values ranged from 0.55 to 4.64, and 8.3% of tumor rCBV values fell within the PTRE group range. A threshold value of 0.71 optimized differentiation of the histopathologic groups with a sensitivity of 91.7% and a specificity of 100%. CONCLUSIONS: rCBV measurements obtained by using DSC and the protocol we have described can differentiate HGG recurrence from PTRE with a high degree of accuracy.
340 citations
TL;DR: The combination of CTA and CTP can detect atherosclerosis causing perfusion abnormalities when compared with the combination of quantitative coronary angiography and SPECT.
Abstract: Background— Multidetector computed tomography coronary angiography (CTA) is a robust method for the noninvasive diagnosis of coronary artery disease. However, in its current form, CTA is limited in its prediction of myocardial ischemia. The purpose of this study was to test whether adenosine stress computed tomography myocardial perfusion imaging (CTP), when added to CTA, can predict perfusion abnormalities caused by obstructive atherosclerosis.
Methods and Results— Forty patients with a history of abnormal single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI) underwent adenosine stress 64-row (n=24) or 256-row (n=16) detector CTP and CTA. A subset of 27 patients had invasive angiography available for quantitative coronary angiography. CTA and quantitative coronary angiography were evaluated for stenoses ≥50%, and SPECT-MPI was evaluated for fixed and reversible perfusion deficits using a 17-segment model. CTP images were analyzed for the transmural differences in perfusion using the transmural perfusion ratio (subendocardial attenuation density/subepicardial attenuation density). The sensitivity, specificity, positive predictive value, and negative predictive value for the combination of CTA and CTP to detect obstructive atherosclerosis causing perfusion abnormalities using the combination of quantitative coronary angiography and SPECT as the gold standard was 86%, 92%, 92%, and 85% in the per-patient analysis and 79%, 91%, 75%, and 92% in the per vessel/territory analysis, respectively.
Conclusions— The combination of CTA and CTP can detect atherosclerosis causing perfusion abnormalities when compared with the combination of quantitative coronary angiography and SPECT.
Received August 13, 2008; accepted March 17, 2009.
298 citations
TL;DR: A new method of non‐contrast‐enhanced functional lung MRI (not dependent on intravenous or inhalative contrast agents) is proposed and was applied in preliminary studies on volunteers and patients showing clinical relevance to obtain non-contrast-enhanced perfusion and ventilation data.
Abstract: Assessment of regional lung perfusion and ventilation has significant clinical value for the diagnosis and follow-up of pulmonary diseases In this work a new method of non-contrast-enhanced functional lung MRI (not dependent on intravenous or inhalative contrast agents) is proposed A two-dimensional (2D) true fast imaging with steady precession (TrueFISP) pulse sequence (TR/TE = 19 ms/08 ms, acquisition time [TA] = 112 ms/image) was implemented on a 15T whole-body MR scanner The imaging protocol comprised sets of 198 lung images acquired with an imaging rate of 333 images/s in coronal and sagittal view No electrocardiogram (ECG) or respiratory triggering was used A nonrigid image registration algorithm was applied to compensate for respiratory motion Rapid data acquisition allowed observing intensity changes in corresponding lung areas with respect to the cardiac and respiratory frequencies After a Fourier analysis along the time domain, two spectral lines corresponding to both frequencies were used to calculate the perfusion- and ventilation-weighted images The described method was applied in preliminary studies on volunteers and patients showing clinical relevance to obtain non-contrast-enhanced perfusion and ventilation data
282 citations
TL;DR: CT perfusion is a functional imaging technique that provides important information about capillary-level hemodynamics of the brain parenchyma and is a natural complement to the strengths of unenhanced CT and CT angiography in the evaluation of acute stroke, vasospasm, and other neurovascular disorders.
Abstract: CT perfusion (CTP) is a functional imaging technique that provides important information about capillary-level hemodynamics of the brain parenchyma and is a natural complement to the strengths of unenhanced CT and CT angiography in the evaluation of acute stroke, vasospasm, and other neurovascular disorders. CTP is critical in determining the extent of irreversibly infarcted brain tissue (infarct "core") and the severely ischemic but potentially salvageable tissue ("penumbra"). This is achieved by generating parametric maps of cerebral blood flow, cerebral blood volume, and mean transit time.
275 citations
TL;DR: These efforts address the main limitations of MPS by combining several approaches such as changing the detector geometry and optimizing tomographic sampling of the field of view for myocardial imaging, improving the detector material and collimator design, and optimizing the image reconstruction algorithms.
234 citations
TL;DR: Vasospasm decreases cerebral perfusion, but corresponds with the least perfused region in only two thirds of patients, and almost half of patients with severe vasospasm do not have DCI.
Abstract: Introduction
Vasospasm after aneurysmal subarachnoid hemorrhage (SAH) is thought to cause ischemia. To evaluate the contribution of vasospasm to delayed cerebral ischemia (DCI), we investigated the effect of vasospasm on cerebral perfusion and the relationship of vasospasm with DCI.
223 citations
TL;DR: A procedure is presented that allows concurrent estimation of cerebral perfusion, blood volume, and blood‐brain permeability from dynamic T1‐weighted imaging of a bolus of a paramagnetic contrast agent passing through the brain.
Abstract: Assessment of vascular properties is essential to diagnosis and follow-up and basic understanding of pathogenesis in brain tumors. In this study, a procedure is presented that allows concurrent estimation of cerebral perfusion, blood volume, and blood-brain permeability from dynamic T1-weighted imaging of a bolus of a paramagnetic contrast agent passing through the brain. The methods are applied in patients with brain tumors and in healthy subjects. Perfusion was estimated by model-free deconvolution using Tikhonov's method (gray matter/white matter/tumor: 72 ± 16/30 ± 8/56 ± 45 mL/100 g/min); blood volume (6 ± 2/4 ± 1/7 ± 6 mL/100 g) and permeability (0.9 ± 0.4/0.8 ± 0.3/3 ± 5 mL/100 g/min) were estimated by using Patlak's method and a two-compartment model. A corroboration of these results was achieved by using model simulation. In addition, it was possible to generate maps on a pixel-by-pixel basis of cerebral perfusion, cerebral blood volume, and blood-brain barrier permeability. Magn Reson Med, 2009. © 2009 Wiley-Liss, Inc.
TL;DR: ASL perfusion MRI provides a versatile biomarker of regional brain function that can be acquired as part of a multimodal MRI examination and should be useful for multisite or longitudinal studies.
Abstract: Purpose of reviewArterial spin labeling (ASL) provides an endogenous and completely noninvasive tracer for the quantification of regional cerebral blood flow (CBF) with magnetic resonance imaging (MRI) Although the measurement of CBF has obvious utility in cerebrovascular disorders, because CBF is
TL;DR: It is concluded that V/Q SPECT in combination with low-dose CT without contrast enhancement has an excellent diagnostic performance and should therefore probably be considered first-line imaging in the work-up of PE in most cases.
Abstract: The diagnosis of pulmonary embolism (PE) is usually established by a combination of clinical assessment, D-dimer testing, and imaging with either pulmonary ventilation–perfusion (V/Q) scintigraphy or pulmonary multidetector CT (MDCT) angiography. Both V/Q SPECT and MDCT angiography seem to have high diagnostic accuracy. However, only limited data directly comparing these 2 modalities are available. Hybrid γ-camera/MDCT systems have been introduced and allow simultaneous 3-dimensional lung V/Q SPECT and MDCT angiography, suitable for diagnosing PE. The aim of our study was to compare, in a prospective design, the diagnostic ability of V/Q SPECT, V/Q SPECT combined with low-dose CT, and pulmonary MDCT angiography obtained simultaneously using a combined SPECT/MDCT scanner in patients suspected of having PE. Methods: Consecutive patients from June 2006 to February 2008 suspected of having acute PE were referred to the Department of Nuclear Medicine at Rigshospitalet or Frederiksberg Hospital, Denmark, for V/Q SPECT as a first-line imaging procedure. The number of eligible patients was 196. Patients with positive D-dimer results (>0.5 mmol/mL) or a clinical assessment with a Wells score greater than 2 were included and underwent V/Q SPECT, low-dose CT, and pulmonary MDCT angiography in a single session. Patient follow-up was 6 mo. Results: A total of 81 simultaneous studies were available for analysis, of which 38% were from patients with PE. V/Q SPECT had a sensitivity of 97% and a specificity of 88%. When low-dose CT was added, the sensitivity was still 97% and the specificity increased to 100%. Perfusion SPECT with low-dose CT had a sensitivity of 93% and a specificity of 51%. MDCT angiography alone had a sensitivity of 68% and a specificity of 100%. Conclusion: We conclude that V/Q SPECT in combination with low-dose CT without contrast enhancement has an excellent diagnostic performance and should therefore probably be considered first-line imaging in the work-up of PE in most cases.
TL;DR: CT perfusion is a functional imaging technique that provides important information about capillary-level hemodynamics of the brain parenchyma and is a natural complement to the strengths of unenhanced CT and CT angiography in the evaluation of acute stroke, vasospasm, and other neurovascular disorders.
Abstract: CT perfusion (CTP) is a functional imaging technique that provides important information about capillary-level hemodynamics of the brain parenchyma and is a natural complement to the strengths of unenhanced CT and CT angiography in the evaluation of acute stroke, vasospasm, and other neurovascular disorders. CTP is critical in determining the extent of irreversibly infarcted brain tissue (infarct "core") and the severely ischemic but potentially salvageable tissue ("penumbra"). This is achieved by generating parametric maps of cerebral blood flow, cerebral blood volume, and mean transit time.
TL;DR: Because perfusion is an early change in the ischemic cascade, stress modalities that assess coronary perfusion reserve have a higher sensitivity in detecting flow-limiting stenoses than analysis of stress-induced wall motion abnormalities or ECG changes alone.
Abstract: Noninvasive assessment of myocardial perfusion is important in the diagnosis and risk stratification of patients with known or suspected coronary artery disease (CAD). Although single-photon emission computed tomography (SPECT) is most commonly used, multiple modalities including myocardial contrast echocardiography (MCE), positron emission tomography (PET), cardiac MRI (CMR), and cardiac computed tomography (CT) have emerged as promising techniques. This article will critically evaluate the strengths and weakness of these modalities for evaluating myocardial perfusion.
Myocardial perfusion is a highly regulated process that includes epicardial vessels, resistance vessels, and the endothelium. Endothelial dysfunction is an early manifestation of vascular disease and plays a role in the development of CAD.1 In normal coronaries, sympathetic stimulation causes a flow-mediated endothelium-dependent release of nitric oxide resulting in epicardial and arteriolar vasodilation. With endothelial dysfunction, vasoconstriction from acetylcholine predominates, resulting an attenuation or absence of the normal flow-mediated vasodilation.2 When coronary arteries are narrowed by atherosclerotic disease, coronary autoregulation attempts to normalize myocardial blood flow by reducing the resistance of distal perfusion beds to preserve adequate myocardial oxygen supply.3 A stenosis must exceed 85% to 90% of luminal diameter before significant reductions in resting blood flow occur.4 However, under vasodilator stimulus, maximal coronary flow has been shown to decrease with stenosis of >45% (Figure 1).4 This has been demonstrated clinically using quantitative PET myocardial perfusion imaging (MPI).5,6 Because perfusion is an early change in the ischemic cascade,7 stress modalities that assess coronary perfusion reserve have a higher sensitivity in detecting flow-limiting stenoses than analysis of stress-induced wall motion abnormalities or ECG changes alone.8 Abnormal coronary flow reserve with vasodilator stress in the absence of a significant coronary stenosis occurs and has been attributed to microvascular and/or endothelial dysfunction.9
Figure 1. Relationship between percent diameter stenosis and …
TL;DR: Measurement of myocardial blood flow gives unique diagnostic information regarding the function of the coronary microcirculation and provides a quantitative surrogate endpoint against which the efficacy of treatments can be established.
Abstract: PET provides robust and reproducible measurements of regional myocardial blood flow in milliliters per minute per gram of tissue, providing unique pathophysiologic and diagnostic information on the function of the coronary macro- and microcirculation. There is compelling evidence to suggest that in many instances abnormalities of global myocardial perfusion are demonstrated in individuals with either coronary risk factors for coronary artery disease or different myocardial diseases in the absence of angiographically demonstrable stenosis of the epicardial coronary arteries. In this context, measurement of myocardial blood flow gives unique diagnostic information regarding the function of the coronary microcirculation and provides a quantitative surrogate endpoint against which the efficacy of treatments can be established.
TL;DR: The imaging features of intracranial and spinal ependymoma are reviewed with an emphasis on conventional magnetic resonance imaging, perfusion MRI and proton magnetic resonance spectroscopy, and computed tomography.
Abstract: The imaging features of intracranial and spinal ependymoma are reviewed with an emphasis on conventional magnetic resonance imaging (MRI), perfusion MRI and proton magnetic resonance spectroscopy, and computed tomography. Imaging manifestations of leptomeningeal dissemination of disease are described. Finally, salient imaging features obtained in the postoperative period to evaluate completeness of surgical resection, and thereafter for long-term surveillance for disease recurrence, are reviewed.
TL;DR: The authors review the current knowledge of CBF in this group of patients and the role each main quantitative method has played in evaluating them, both in the disease state and after surgical intervention.
Abstract: Moyamoya disease is characterized by a chronic stenoocclusive vasculopathy affecting the terminal internal carotid arteries. The clinical presentation and outcome of moyamoya disease remain varied based on angiographic studies alone, and much work has been done to study cerebral hemodynamics in this group of patients. The ability to measure cerebral blood flow (CBF) accurately continues to improve with time, and with it a better understanding of the pathophysiological mechanisms in patients with moyamoya disease. The main imaging techniques used to evaluate cerebral hemodynamics include PET, SPECT, xenon-enhanced CT, dynamic perfusion CT, MR imaging with dynamic susceptibility contrast and with arterial spin labeling, and Doppler ultrasonography. More invasive techniques include intraoperative ultrasonography. The authors review the current knowledge of CBF in this group of patients and the role each main quantitative method has played in evaluating them, both in the disease state and after surgical intervention.
TL;DR: The LDLS system proves to be suited to measurement of perfusion in deeper vessels, while FLPI and TiVi showed sensitivity to more superficial nutritional supply and LDLS and FLPI are insensitive to the action of the vasoconstrictor, while TiVi shows the clear boundaries of the reaction.
Abstract: The use of laser Doppler perfusion imaging LDPI and laser speckle perfusion imaging LSPI is well known in the noninvasive investigation of microcirculatory blood flow. This work compares the two techniques with the recently developed tissue viability TiVi im- aging system, which is proposed as a useful tool to quantify red blood cell concentration in microcirculation. Three systems are evaluated with common skin tests such as the use of vasodilating and vasocon- stricting drugs methlynicotinate and clobetasol, respectively and a reactive hyperaemia maneuver using a sphygmomanometer. The de- vices investigated are the laser Doppler line scanner LDLS, the laser speckle perfusion imager FLPI—both from Moor Instruments Axminster, United Kingdom—and the TiVi imaging system Wheels- Bridge AB, Linkoping, Sweden. Both imaging and point scanning by the devices are used to quantify the provoked reactions. Perfusion images of vasodilatation and vasoconstriction are acquired with both LDLS and FLPI, while TiVi images are acquired with the TiVi imager. Time acquisitions of an averaged region of interest are acquired for temporal studies such as the reactive hyperaemia. In contrast to the change in perfusion over time with pressure, the TiVi imager shows a different response due its measurement of blood concentration rather than perfusion. The responses can be explained by physiological un- derstanding. Although the three devices sample different compart- ments of tissue, and output essentially different variables, comparisons can be seen between the three systems. The LDLS system proves to be suited to measurement of perfusion in deeper vessels, while FLPI and TiVi showed sensitivity to more superficial nutritional supply. LDLS and FLPI are insensitive to the action of the vasoconstrictor, while TiVi shows the clear boundaries of the reaction. Assessment of the reso- lution, penetration depth, and acquisition rate of each instrument show complimentary features that should be taken into account when choosing a system for a particular clinical measurement. © 2009 Society
TL;DR: After chemoradiation therapy, findings at perfusion CT are a significant predictor of early tumor response and overall survival among patients with non-small cell lung cancer.
Abstract: OBJECTIVE. The objectives of this study were to prospectively evaluate changes in tumor perfusion after chemoradiation therapy and to investigate the feasibility of perfusion CT for prediction of early tumor response and prognosis of non–small cell lung cancer.SUBJECTS AND METHODS. Perfusion CT was performed on an MDCT scanner with 50 mL of iodinated contrast material injected at 4 mL/s. The quality of each functional map was rated from 0 to 3 for 123 patients with confirmed lung cancer. A subset of images was independently reviewed by two radiologists to measure interobserver and intraobserver variability. Perfusion parameters and tumor response were assessed for 35 patients with non–small cell lung cancer who underwent chemoradiation therapy. Progression-free survival and overall survival were analyzed for 22 patients who underwent repeated perfusion CT after therapy.RESULTS. Image quality was graded 2 (moderate) or 3 (good) in 68.2% of cases. High interobserver and intraobserver correlations of perfusi...
TL;DR: It is suggested that negative-pressure wound therapy should be used with caution on tissues with compromised vascularity, particularly when used circumferentially, because perfusion beneath negative- pressure wound therapy decreases for increasing suction pressure.
Abstract: BACKGROUND A recent study demonstrated that negative-pressure wound therapy increases underlying tissue pressure. This finding is incongruous with studies using laser Doppler that show that perfusion is immediately increased on initiation of suction. This study investigated perfusion in negative-pressure wound therapy using two alternative modalities. METHODS Radioisotope perfusion imaging was used to determine perfusion beneath circumferential negative-pressure wound therapy dressings on 20 healthy hands (n = 20). Ten hands received suction pressures of -400 mmHg and 10 received -125 mmHg, with the contralateral hand used as a control without any suction. Transcutaneous partial pressure of oxygen was used to determine perfusion beneath noncircumferential negative-pressure wound therapy dressings on 12 healthy legs (n = 12), with each volunteer being sequentially randomized to receive suction pressures of -400 and -125 mmHg, respectively. RESULTS Tissues undergoing circumferential negative-pressure wound therapy demonstrated a mean reduction in perfusion of 40 +/- 11.5 percent (p < 0.0005) and 17 +/- 8.9 percent (p < 0.0005) at suction pressures of -400 mmHg and -125 mmHg, respectively. Perfusion reduction at -400 mmHg was significantly greater than at -125 mmHg (p < 0.015). In the noncircumferential negative-pressure wound therapy group, there was a mean reduction in transcutaneous partial pressure of oxygen of 7.35 +/- 7.4 mmHg (p < 0.0005) and 5.10 +/- 7.4 mmHg (p < 0.0005) at suction pressures of -400 mmHg and -125 mmHg, respectively. There was a tendency for greater reductions in the -400 mmHg group, but this was not significantly different from the -125 mmHg group (p = 0.07). CONCLUSIONS These findings demonstrate that perfusion beneath negative-pressure wound therapy decreases for increasing suction pressure. Thus, it is suggested that negative-pressure wound therapy should be used with caution on tissues with compromised vascularity, particularly when used circumferentially.
TL;DR: CMR imaging provides robust risk stratification for patients who present with symptoms of ischemia and provides strong and complementary prognostic implication for cardiac death or acute MI.
Abstract: Background— Recent studies have demonstrated the significant prognostic value of stress cardiac magnetic resonance (CMR) myocardial perfusion imaging. Apart from characterizing reversible perfusion defect (RevPD) from flow-limiting coronary stenosis, CMR late gadolinium enhancement (LGE) imaging is currently the most sensitive method for detecting subendocardial infarction (MI). We therefore tested the hypothesis that characterization of these 2 processes from coronary artery disease by CMR can provide complementary prognostic values. Methods and Results— We performed CMR myocardial perfusion imaging followed by LGE imaging on 254 patients referred with symptoms of myocardial ischemia. At a median follow-up of 17 months, 49 cardiac events occurred, including 12 cardiac deaths, 16 acute MIs, and 21 cardiac hospitalizations. RevPD and LGE both maintained a >3-fold association with cardiac death or acute MI (death/MI) when adjusted for each other and for the effects of patient age and gender (adjusted hazard...
TL;DR: Admission PS measurement appears promising for distinguishing patients with acute stroke who are likely from those who are not likely to develop HT, and at stepwise multivariate analysis.
Abstract: Purpose: To determine whether admission computed tomography (CT) perfusion–derived permeability–surface area product (PS) maps differ between patients with hemorrhagic acute stroke and those with nonhemorrhagic acute stroke. Materials and Methods: This prospective study was institutional review board approved, and all participants gave written informed consent. Forty-one patients who presented with acute stroke within 3 hours after stroke symptom onset underwent two-phase CT perfusion imaging, which enabled PS measurement. Patients were assigned to groups according to whether they had hemorrhage transformation (HT) at follow-up magnetic resonance (MR) imaging and CT and/or whether they received tissue plasminogen activator (TPA) treatment. Clinical, demographic, and CT perfusion variables were compared between the HT and non-HT patient groups. Associations between PS and HT were tested at univariate and multivariate logistic regression analyses and receiver operating characteristic (ROC) analysis. Results...
TL;DR: A comprehensive CT acute stroke protocol delivered a mean effective dose of 16.4 mSv, which is approximately six times the dose of an unenhanced CT head, which should be balanced with the benefits of the detailed anatomic and physiologic data obtained.
Abstract: The objective of this study was to determine the radiation dose delivered during comprehensive computed tomography (CT) imaging for acute stroke. All CT examinations performed over 18 months using our acute stroke protocol were included. Protocol includes an unenhanced CT head, CT angiography from the arch to vertex, CT perfusion/permeability, and an enhanced CT head. All imaging was acquired with a 64-MDCT. Examinations where any element of the protocol was repeated or omitted due to mistimed injection or patient motion were excluded. Dose-length products (DLP) for all components of each examination were obtained from dose reports generated at the time of acquisition, separating neck, and head calculations. Effective doses for each examination were calculated using the DLP and normalized values of effective dose per DLP appropriate for the body regions imaged. Ninety-five examinations were included. Mean DLP was 6,790.0 mGy·cm. Effective doses ranged from 11.8 to 27.3 mSv, mean effective dose of 16.4 mSv. Mean effective dose for acquisition of the unenhanced head was 2.7 mSv. Largest contribution to effective dose was the CTA with a mean effective dose of 5.4 mSv. Mean effective dose for the CT perfusion was 4.9 mSv. A comprehensive CT acute stroke protocol delivered a mean effective dose of 16.4 mSv, which is approximately six times the dose of an unenhanced CT head. These high-dose results must be balanced with the benefits of the detailed anatomic and physiologic data obtained. Centers should implement aggressive dose reduction strategies and freely use MR as a substitute.
TL;DR: In stable patients having serial SPECT MPI, quantification is more reproducible than visual for magnitude of perfusion abnormality, suggesting its superiority for use in randomized clinical trials and monitoring the effects of therapy in an individual patient.
TL;DR: PAMPA-BBB is high throughput, low cost and has good prediction of in vivo BBB permeability, and therefore, it is a valuable tool in drug discovery to screen compounds for the rate of brain penetration.
TL;DR: Perfusion and permeability magnetic resonance (MR) imaging can now measure parameters such as cerebral blood volume and vascular permeability, which can be directly correlated with these histopathologic changes as well as molecular markers such as VEGF.
TL;DR: These guidelines summarize the current views of the European Association of Nuclear Medicine Neuroimaging Committee (ENC) and aim to achieve a high quality standard for brain perfusion SPECT imaging, which will increase the diagnostic impact of this technique in clinical practice.
Abstract: These guidelines summarize the current views of the European Association of Nuclear Medicine Neuroimaging Committee (ENC) The purpose of the guidelines is to assist nuclear medicine practitioners when making recommendations, performing, interpreting, and reporting the results of brain perfusion single photon emission computed tomography (SPECT) studies using (99m)Tc-labelled radiopharmaceuticals The aim is to achieve a high quality standard for brain perfusion SPECT imaging, which will increase the diagnostic impact of this technique in clinical practice The present document replaces a former version of the guideline published in 2001 which was inspired by the Society of Nuclear Medicine Procedure Guideline for Brain Perfusion SPECT [1], the views of the Society of Nuclear Medicine Brain Imaging Council [2], and the individual experience of experts in European countries The guidelines are intended to present information specifically adapted to European practice The information provided should be taken in the context of local conditions and regulations
TL;DR: Arterial spin labeling (ASL) imaging soon will be available as a routine clinical perfusion imaging sequence for a significant number of MR imaging scanners, and familiarity with the available sequence parameter options and the common appearances of pathology facilitates perfusion interpretation.
University of Maryland Medical Center1, University of California, San Francisco2, University of Ottawa3, Beth Israel Deaconess Medical Center4, Vanderbilt University Medical Center5, University of Washington6, Turku University Hospital7, University of California, Los Angeles8, Montefiore Medical Center9