Showing papers on "Perfusion scanning published in 2015"

Endovascular Therapy for Ischemic Stroke with Perfusion-Imaging Selection

Abstract: Background Trials of endovascular therapy for ischemic stroke have produced variable results. We conducted this study to test whether more advanced imaging selection, recently developed devices, and earlier intervention improve outcomes. Methods We randomly assigned patients with ischemic stroke who were receiving 0.9 mg of alteplase per kilogram of body weight less than 4.5 hours after the onset of ischemic stroke either to undergo endovascular thrombectomy with the Solitaire FR (Flow Restoration) stent retriever or to continue receiving alteplase alone. All the patients had occlusion of the internal carotid or middle cerebral artery and evidence of salvageable brain tissue and ischemic core of less than 70 ml on computed tomographic (CT) perfusion imaging. The coprimary outcomes were reperfusion at 24 hours and early neurologic improvement (≥8-point reduction on the National Institutes of Health Stroke Scale or a score of 0 or 1 at day 3). Secondary outcomes included the functional score on the modified Rankin scale at 90 days. Results The trial was stopped early because of efficacy after 70 patients had undergone randomization (35 patients in each group). The percentage of ischemic territory that had undergone reperfusion at 24 hours was greater in the endovascular-therapy group than in the alteplase-only group (median, 100% vs. 37%; P<0.001). Endovascular therapy, initiated at a median of 210 minutes after the onset of stroke, increased early neurologic improvement at 3 days (80% vs. 37%, P = 0.002) and improved the functional outcome at 90 days, with more patients achieving functional independence (score of 0 to 2 on the modified Rankin scale, 71% vs. 40%; P = 0.01). There were no significant differences in rates of death or symptomatic intracerebral hemorrhage. Conclusions In patients with ischemic stroke with a proximal cerebral arterial occlusion and salvageable tissue on CT perfusion imaging, early thrombectomy with the Solitaire FR stent retriever, as compared with alteplase alone, improved reperfusion, early neurologic recovery, and functional outcome. (Funded by the Australian National Health and Medical Research Council and others; EXTEND-IA ClinicalTrials.gov number, NCT01492725, and Australian New Zealand Clinical Trials Registry number, ACTRN12611000969965.)

Vascular hippocampal plasticity after aerobic exercise in older adults

Abstract: Aerobic exercise in young adults can induce vascular plasticity in the hippocampus, a critical region for recall and recognition memory. In a mechanistic proof-of-concept intervention over 3 months, we investigated whether healthy older adults (60-77 years) also show such plasticity. Regional cerebral blood flow (rCBF) and volume (rCBV) were measured with gadolinium-based perfusion imaging (3 Tesla magnetic resonance image (MRI)). Hippocampal volumes were assessed by high-resolution 7 Tesla MRI. Fitness improvement correlated with changes in hippocampal perfusion and hippocampal head volume. Perfusion tended to increase in younger, but to decrease in older individuals. The changes in fitness, hippocampal perfusion and volume were positively related to changes in recognition memory and early recall for complex spatial objects. Path analyses indicated that fitness-related changes in complex object recognition were modulated by hippocampal perfusion. These findings indicate a preserved capacity of the aging human hippocampus for functionally relevant vascular plasticity, which decreases with progressing age.

A neuroradiologist’s guide to arterial spin labeling MRI in clinical practice

Abstract: Arterial spin labeling (ASL) is a non-invasive MRI technique to measure cerebral blood flow (CBF). This review provides a practical guide and overview of the clinical applications of ASL of the brain, as well its potential pitfalls. The technical and physiological background is also addressed. At present, main areas of interest are cerebrovascular disease, dementia and neuro-oncology. In cerebrovascular disease, ASL is of particular interest owing to its quantitative nature and its capability to determine cerebral arterial territories. In acute stroke, the source of the collateral blood supply in the penumbra may be visualised. In chronic cerebrovascular disease, the extent and severity of compromised cerebral perfusion can be visualised, which may be used to guide therapeutic or preventative intervention. ASL has potential for the detection and follow-up of arteriovenous malformations. In the workup of dementia patients, ASL is proposed as a diagnostic alternative to PET. It can easily be added to the routinely performed structural MRI examination. In patients with established Alzheimer’s disease and frontotemporal dementia, hypoperfusion patterns are seen that are similar to hypometabolism patterns seen with PET. Studies on ASL in brain tumour imaging indicate a high correlation between areas of increased CBF as measured with ASL and increased cerebral blood volume as measured with dynamic susceptibility contrast-enhanced perfusion imaging. Major advantages of ASL for brain tumour imaging are the fact that CBF measurements are not influenced by breakdown of the blood–brain barrier, as well as its quantitative nature, facilitating multicentre and longitudinal studies.

ASFNR recommendations for clinical performance of MR dynamic susceptibility contrast perfusion imaging of the brain.

Abstract: MR perfusion imaging is becoming an increasingly common means of evaluating a variety of cerebral pathologies, including tumors and ischemia. In particular, there has been great interest in the use of MR perfusion imaging for both assessing brain tumor grade and for monitoring for tumor recurrence in previously treated patients. Of the various techniques devised for evaluating cerebral perfusion imaging, the dynamic susceptibility contrast method has been employed most widely among clinical MR imaging practitioners. However, when implementing DSC MR perfusion imaging in a contemporary radiology practice, a neuroradiologist is confronted with a large number of decisions. These include choices surrounding appropriate patient selection, scan-acquisition parameters, data-postprocessing methods, image interpretation, and reporting. Throughout the imaging literature, there is conflicting advice on these issues. In an effort to provide guidance to neuroradiologists struggling to implement DSC perfusion imaging in their MR imaging practice, the Clinical Practice Committee of the American Society of Functional Neuroradiology has provided the following recommendations. This guidance is based on review of the literature coupled with the practice experience of the authors. While the ASFNR acknowledges that alternate means of carrying out DSC perfusion imaging may yield clinically acceptable results, the following recommendations should provide a framework for achieving routine success in this complicated-but-rewarding aspect of neuroradiology MR imaging practice.

Modern brain tumor imaging.

Abstract: The imaging and clinical management of patients with brain tumor continue to evolve over time and now heavily rely on physiologic imaging in addition to high-resolution structural imaging. Imaging remains a powerful noninvasive tool to positively impact the management of patients with brain tumor. This article provides an overview of the current state-of-the art clinical brain tumor imaging. In this review, we discuss general magnetic resonance (MR) imaging methods and their application to the diagnosis of, treatment planning and navigation, and disease monitoring in patients with brain tumor. We review the strengths, limitations, and pitfalls of structural imaging, diffusion-weighted imaging techniques, MR spectroscopy, perfusion imaging, positron emission tomography/MR, and functional imaging. Overall this review provides a basis for understudying the role of modern imaging in the care of brain tumor patients.

Diffusion and Perfusion MRI to Differentiate Treatment-Related Changes Including Pseudoprogression from Recurrent Tumors in High-Grade Gliomas with Histopathologic Evidence

Abstract: BACKGROUND AND PURPOSE: Treatment-related changes and recurrent tumors often have overlapping features on conventional MR imaging. The purpose of this study was to assess the utility of DWI and DSC perfusion imaging alone and in combination to differentiate treatment-related effects and recurrent high-grade gliomas. MATERIALS AND METHODS: We retrospectively identified 68 consecutive patients with high-grade gliomas treated by surgical resection followed by radiation therapy and temozolomide, who then developed increasing enhancing mass lesions indeterminate for treatment-related changes versus recurrent tumor. All lesions were diagnosed by histopathology at repeat surgical resection. ROI analysis was performed of the enhancing lesion on the ADC and DSC maps. Measurements made by a 2D ROI of the enhancing lesion on a single slice were recorded as ADC Lesion and rCBV Lesion , and measurements made by the most abnormal small fixed diameter ROI as ADC ROI and rCBV ROI . Statistical analysis was performed with Wilcoxon rank sum tests with P = .05. RESULTS: Ten of the 68 patients (14.7%) had treatment-related changes, while 58 patients (85.3%) had recurrent tumor only ( n = 19) or recurrent tumor mixed with treatment effect ( n = 39). DWI analysis showed higher ADC Lesion in treatment-related changes than in recurrent tumor ( P = .003). DSC analysis revealed lower relative cerebral blood volume (rCBV) Lesion and rCBV ROI in treatment-related changes ( P = .003 and P = .011, respectively). Subanalysis of patients with suspected pseudoprogression also revealed higher ADC Lesion ( P = .001) and lower rCBV Lesion ( P = .028) and rCBV ROI ( P = .032) in treatment-related changes. Applying a combined ADC Lesion and rCBV Lesion model did not outperform either the ADC or rCBV metric alone. CONCLUSIONS: Treatment-related changes showed higher diffusion and lower perfusion than recurrent tumor. Similar correlations were found for patients with suspected pseudoprogression.

Perfusion computed tomography to assist decision making for stroke thrombolysis

Abstract: The use of perfusion imaging to guide selection of patients for stroke thrombolysis remains controversial because of lack of supportive phase three clinical trial evidence. We aimed to measure the outcomes for patients treated with intravenous recombinant tissue plasminogen activator (rtPA) at a comprehensive stroke care facility where perfusion computed tomography was routinely used for thrombolysis eligibility decision assistance. Our overall hypothesis was that patients with 'target' mismatch on perfusion computed tomography would have improved outcomes with rtPA. This was a prospective cohort study of consecutive ischaemic stroke patients who fulfilled standard clinical/non-contrast computed tomography eligibility criteria for treatment with intravenous rtPA, but for whom perfusion computed tomography was used to guide the final treatment decision. The 'real-time' perfusion computed tomography assessments were qualitative; a large perfusion computed tomography ischaemic core, or lack of significant perfusion lesion-core mismatch were considered relative exclusion criteria for thrombolysis. Specific volumetric perfusion computed tomography criteria were not used for the treatment decision. The primary analysis compared 3-month modified Rankin Scale in treated versus untreated patients after 'off-line' (post-treatment) quantitative volumetric perfusion computed tomography eligibility assessment based on presence or absence of 'target' perfusion lesion-core mismatch (mismatch ratio >1.8 and volume >15 ml, core <70 ml). In a second analysis, we compared outcomes of the perfusion computed tomography-selected rtPA-treated patients to an Australian historical cohort of non-contrast computed tomography-selected rtPA-treated patients. Of 635 patients with acute ischaemic stroke eligible for rtPA by standard criteria, thrombolysis was given to 366 patients, with 269 excluded based on visual real-time perfusion computed tomography assessment. After off-line quantitative perfusion computed tomography classification: 253 treated patients and 83 untreated patients had 'target' mismatch, 56 treated and 31 untreated patients had a large ischaemic core, and 57 treated and 155 untreated patients had no target mismatch. In the primary analysis, only in the target mismatch subgroup did rtPA-treated patients have significantly better outcomes (odds ratio for 3-month, modified Rankin Scale 0-2 = 13.8, P < 0.001). With respect to the perfusion computed tomography selected rtPA-treated patients (n = 366) versus the clinical/non-contrast computed tomography selected rtPA-treated patients (n = 396), the perfusion computed tomography selected group had higher adjusted odds of excellent outcome (modified Rankin Scale 0-1 odds ratio 1.59, P = 0.009) and lower mortality (odds ratio 0.56, P = 0.021). Although based on observational data sets, our analyses provide support for the hypothesis that perfusion computed tomography improves the identification of patients likely to respond to thrombolysis, and also those in whom natural history may be difficult to modify with treatment.

Time-Dependent Computed Tomographic Perfusion Thresholds for Patients With Acute Ischemic Stroke

Abstract: Background and Purpose— Among patients with acute ischemic stroke, we determine computed tomographic perfusion (CTP) thresholds associated with follow-up infarction at different stroke onset-to-CTP and CTP-to-reperfusion times. Methods— Acute ischemic stroke patients with occlusion on computed tomographic angiography were acutely imaged with CTP. Noncontrast computed tomography and magnectic resonance diffusion–weighted imaging between 24 and 48 hours were used to delineate follow-up infarction. Reperfusion was assessed on conventional angiogram or 4-hour repeat computed tomographic angiography. T max, cerebral blood flow, and cerebral blood volume derived from delay-insensitive CTP postprocessing were analyzed using receiver–operator characteristic curves to derive optimal thresholds for combined patient data (pooled analysis) and individual patients (patient-level analysis) based on time from stroke onset-to-CTP and CTP-to-reperfusion. One-way ANOVA and locally weighted scatterplot smoothing regression was used to test whether the derived optimal CTP thresholds were different by time. Results— One hundred and thirty-two patients were included. T max thresholds of >16.2 and >15.8 s and absolute cerebral blood flow thresholds of 0.05). A statistically significant relationship existed between CTP-to-reperfusion time and the optimal thresholds for cerebral blood flow ( P <0.001; r=0.59 and 0.77 for gray and white matter, respectively) and T max ( P <0.001; r=−0.68 and −0.60 for gray and white matter, respectively) parameters. Conclusions— Optimal CTP thresholds associated with follow-up infarction depend on time from imaging to reperfusion.

Endovascular Therapy for Ischemic Stroke

Abstract: To the Editor: In their report on the Extending the Time for Thrombolysis in Emergency Neurological Deficits - Intra-Arterial (EXTEND-IA) trial, Campbell et al. (March 12 issue)(1) suggest that in MR CLEAN (Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands), local investigators might have selected patients on the basis of findings on computed tomographic (CT) perfusion imaging, although such selection was not specified in the protocol.(2),(3) We compared the effect of endovascular therapy in patients with and in those without CT perfusion data. In 166 patients without such data, the adjusted common odds . .

Imaging Evidence and Recommendations for Traumatic Brain Injury: Advanced Neuro- and Neurovascular Imaging Techniques

Abstract: SUMMARY: Neuroimaging plays a critical role in the evaluation of patients with traumatic brain injury, with NCCT as the first-line of imaging for patients with traumatic brain injury and MR imaging being recommended in specific settings. Advanced neuroimaging techniques, including MR imaging DTI, blood oxygen level– dependent fMRI, MR spectroscopy, perfusion imaging, PET/SPECT, and magnetoencephalography, are of particular interest in identifying further injury in patients with traumatic brain injury when conventional NCCT and MR imaging findings are normal, as well as for prognostication in patients with persistent symptoms. These advanced neuroimaging techniques are currently under investigation in an attempt to optimize them and substantiate their clinical relevance in individual patients. However, the data currently available confine their use to the research arena for group comparisons, and there remains insufficient evidence at the time of this writing to conclude that these advanced techniques can be used for routine clinical use at the individual patient level. TBI imaging is a rapidly evolving field, and a number of the recommendations presented will be updated in the future to reflect the advances in medical knowledge. ABBREVIATIONS: BOLD blood oxygen level– dependent; FA fractional anisotropy; MD mean diffusivity; MEG magnetoencephalography; TBI traumatic brain injury

Imaging selection in ischemic stroke: feasibility of automated CT-perfusion analysis

Abstract: BackgroundAdvanced imaging may refine patient selection for ischemic stroke treatment but delays to acquire and process the imaging have limited implementation.AimsWe examined the feasibility of imaging selection in clinical practice using fully automated software in the EXTEND trial program.MethodsCTP and perfusion-diffusion MRI data were processed using fully-automated software to generate a yes/no ‘mismatch’ classification that determined eligibility for trial therapies. The technical failure/mismatch classification error rate and time to image and treat with CT vs. MR-based selection were examined.ResultsIn a consecutive series of 776 patients from five sites over six-months the technical failure rate of CTP acquisition/processing (uninterpretable maps) was 3·4% (26/776, 95%CI 2·2–4·9%). Mismatch classification was overruled by expert review in an additional 9·0% (70/776, 95%CI 7·1–11·3%) due to artifactual ‘perfusion lesion’. In 154 consecutive patients at one site, median additional time to acquire ...

Cerebral hemodynamic changes of mild traumatic brain injury at the acute stage.

Abstract: Mild traumatic brain injury (mTBI) is a significant public health care burden in the United States. However, we lack a detailed understanding of the pathophysiology following mTBI and its relation to symptoms and recovery. With advanced magnetic resonance imaging (MRI), we can investigate brain perfusion and oxygenation in regions known to be implicated in symptoms, including cortical gray matter and subcortical structures. In this study, we assessed 14 mTBI patients and 18 controls with susceptibility weighted imaging and mapping (SWIM) for blood oxygenation quantification. In addition to SWIM, 7 patients and 12 controls had cerebral perfusion measured with arterial spin labeling (ASL). We found increases in regional cerebral blood flow (CBF) in the left striatum, and in frontal and occipital lobes in patients as compared to controls (p = 0.01, 0.03, 0.03 respectively). We also found decreases in venous susceptibility, indicating increases in venous oxygenation, in the left thalamostriate vein and right basal vein of Rosenthal (p = 0.04 in both). mTBI patients had significantly lower delayed recall scores on the standardized assessment of concussion, but neither susceptibility nor CBF measures were found to correlate with symptoms as assessed by neuropsychological testing. The increased CBF combined with increased venous oxygenation suggests an increase in cerebral blood flow that exceeds the oxygen demand of the tissue, in contrast to the regional hypoxia seen in more severe TBI. This may represent a neuroprotective response following mTBI, which warrants further investigation.

Worse stroke outcome in atrial fibrillation is explained by more severe hypoperfusion, infarct growth, and hemorrhagic transformation

Abstract: BackgroundAtrial fibrillation is associated with greater baseline neurological impairment and worse outcomes following ischemic stroke. Previous studies suggest that greater volumes of more severe baseline hypoperfusion in patients with history of atrial fibrillation may explain this association. We further investigated this association by comparing patients with and without atrial fibrillation on initial examination following stroke using pooled multimodal magnetic resonance imaging and clinical data from the Echoplanar Imaging Thrombolytic Evaluation Trial and the Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evolution studies.MethodsEchoplanar Imaging Thrombolytic Evaluation Trial was a trial of 101 ischemic stroke patients randomized to intravenous tissue plasminogen activator or placebo, and Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evolution was a prospective cohort of 74 ischemic stroke patients treated with intravenous tissue plasminogen activator at...

Value of Computed Tomographic Perfusion–Based Patient Selection for Intra-Arterial Acute Ischemic Stroke Treatment

Abstract: Background and Purpose— The utility of computed tomographic perfusion (CTP)–based patient selection for intra-arterial treatment of acute ischemic stroke has not been proven in randomized trials and requires further study in a cohort that was not selected based on CTP. Our objective was to study the relationship between CTP-derived parameters and outcome and treatment effect in patients with acute ischemic stroke because of a proximal intracranial arterial occlusion. Methods— We included 175 patients who underwent CTP in the Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in The Netherlands (MR CLEAN). Association of CTP-derived parameters (ischemic-core volume, penumbra volume, and percentage ischemic core) with outcome was estimated with multivariable ordinal logistic regression as an adjusted odds ratio for a shift in the direction of a better outcome on the modified Rankin Scale. Interaction between CTP-derived parameters and treatment effect was determined using multivariable ordinal logistic regression. Interaction with treatment effect was also tested for mismatch (core 1.2; penumbra core >10 mL). Results— The adjusted odds ratio for improved functional outcome for ischemic core, percentage ischemic core, and penumbra were 0.79 per 10 mL (95% confidence interval: 0.71–0.89; P P =0.002), and 0.97 per 10 mL (96% confidence interval: 0.92–1.01; P =0.15), respectively. No significant interaction between any of the CTP-derived parameters and treatment effect was observed. We observed no significant interaction between mismatch and treatment effect. Conclusions— CTP seems useful for predicting functional outcome, but cannot reliably identify patients who will not benefit from intra-arterial therapy.

Sensitivity of Diffusion- and Perfusion-Weighted Imaging for Diagnosing Acute Ischemic Stroke Is 97.5%

Abstract: Background and Purpose—MRI using diffusion-weighted imaging (DWI) is the most sensitive diagnostic imaging modality for early detection of ischemia, but how accurate is it and how much does perfusi...

Response to endovascular reperfusion is not time-dependent in patients with salvageable tissue

Abstract: Objective: To evaluate whether time to treatment modifies the effect of endovascular reperfusion in stroke patients with evidence of salvageable tissue on MRI. Methods: Patients from the Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evolution 2 (DEFUSE 2) cohort study with a perfusion-diffusion target mismatch were included. Reperfusion was defined as a decrease in the perfusion lesion volume of at least 50% between baseline and early follow-up. Good functional outcome was defined as a modified Rankin Scale score ≤2 at day 90. Lesion growth was defined as the difference between the baseline and the early follow-up diffusion-weighted imaging lesion volumes. Results: Among 78 patients with the target mismatch profile (mean age 66 ± 16 years, 54% women), reperfusion was associated with increased odds of good functional outcome (adjusted odds ratio 3.7, 95% confidence interval 1.2–12, p = 0.03) and attenuation of lesion growth ( p = 0.02). Time to treatment did not modify these effects ( p value for the time × reperfusion interaction is 0.6 for good functional outcome and 0.3 for lesion growth). Similarly, in the subgroup of patients with reperfusion (n = 46), time to treatment was not associated with good functional outcome ( p = 0.2). Conclusion: The association between endovascular reperfusion and improved functional and radiologic outcomes is not time-dependent in patients with a perfusion-diffusion mismatch. Proof that patients with mismatch benefit from endovascular therapy in the late time window should come from a randomized placebo-controlled trial.

Dynamic glucose enhanced (DGE) MRI for combined imaging of blood–brain barrier break down and increased blood volume in brain cancer

Abstract: Recently, natural d-glucose was suggested as a potential biodegradable contrast agent. The feasibility of using d-glucose for dynamic perfusion imaging was explored to detect malignant brain tumors based on blood brain barrier breakdown.

Limited reliability of computed tomographic perfusion acute infarct volume measurements compared with diffusion-weighted imaging in anterior circulation stroke.

Abstract: Background and Purpose—Diffusion-weighted imaging (DWI) can reliably identify critically ischemic tissue shortly after stroke onset. We tested whether thresholded computed tomographic cerebral blood flow (CT-CBF) and CT-cerebral blood volume (CT-CBV) maps are sufficiently accurate to substitute for DWI for estimating the critically ischemic tissue volume. Methods—Ischemic volumes of 55 patients with acute anterior circulation stroke were assessed on DWI by visual segmentation and on CT-CBF and CT-CBV with segmentation using 15% and 30% thresholds, respectively. The contrast:noise ratios of ischemic regions on the DWI and CT perfusion (CTP) images were measured. Correlation and Bland–Altman analyses were used to assess the reliability of CTP. Results—Mean contrast:noise ratios for DWI, CT-CBF, and CT-CBV were 4.3, 0.9, and 0.4, respectively. CTP and DWI lesion volumes were highly correlated (R2=0.87 for CT-CBF; R2=0.83 for CT-CBV; P<0.001). Bland–Altman analyses revealed little systemic bias (−2.6 mL) but ...

CT Myocardial Perfusion Imaging

Abstract: OBJECTIVE. CT myocardial perfusion imaging is rapidly becoming an important adjunct to coronary CT angiography for the anatomic and functional assessment of coronary artery disease with a single modality. Existing techniques for CT myocardial perfusion imaging include static techniques, which provide a snapshot of the myocardial blood pool, and dynamic techniques. CONCLUSION. This review provides a systematic overview of the presently available approaches for the assessment of myocardial perfusion at CT, including diagnostic accuracy and limitations.

Augmentation of Limb Perfusion and Reversal of Tissue Ischemia Produced by Ultrasound-Mediated Microbubble Cavitation

Abstract: Background— Ultrasound can increase tissue blood flow, in part, through the intravascular shear produced by oscillatory pressure fluctuations. We hypothesized that ultrasound-mediated increases in perfusion can be augmented by microbubble contrast agents that undergo ultrasound-mediated cavitation and sought to characterize the biological mediators. Methods and Results— Contrast ultrasound perfusion imaging of hindlimb skeletal muscle and femoral artery diameter measurement were performed in nonischemic mice after unilateral 10-minute exposure to intermittent ultrasound alone (mechanical index, 0.6 or 1.3) or ultrasound with lipid microbubbles (2×108 IV). Studies were also performed after inhibiting shear- or pressure-dependent vasodilator pathways, and in mice with hindlimb ischemia. Ultrasound alone produced a 2-fold increase ( P <0.05) in muscle perfusion regardless of ultrasound power. Ultrasound-mediated augmentation in flow was greater with microbubbles (3- and 10-fold higher than control for mechanical index 0.6 and 1.3, respectively; P <0.05), as was femoral artery dilation. Inhibition of endothelial nitric oxide synthase attenuated flow augmentation produced by ultrasound and microbubbles by 70% ( P <0.01), whereas inhibition of adenosine-A2a receptors and epoxyeicosatrienoic acids had minimal effect. Limb nitric oxide production and muscle phospho-endothelial nitric oxide synthase increased in a stepwise fashion by ultrasound and ultrasound with microbubbles. In mice with unilateral hindlimb ischemia (40%–50% reduction in flow), ultrasound (mechanical index, 1.3) with microbubbles increased perfusion by 2-fold to a degree that was greater than the control nonischemic limb. Conclusions— Increases in muscle blood flow during high-power ultrasound are markedly amplified by the intravascular presence of microbubbles and can reverse tissue ischemia. These effects are most likely mediated by cavitation-related increases in shear and activation of endothelial nitric oxide synthase.

Splenic Switch-off: A Tool to Assess Stress Adequacy in Adenosine Perfusion Cardiac MR Imaging.

Abstract: Failed splenic switch-off with adenosine is a new, simple observation that identifies understressed patients who are at risk for false-negative findings on myocardial perfusion MR images.

Impact of intraoperative microperfusion assessment with Pinpoint Perfusion Imaging on surgical management of laparoscopic low rectal and anorectal anastomoses.

Abstract: Aim Inadequate intestinal blood flow may contribute to anastomotic leakage accounting for substantial morbidity and mortality in colorectal surgery. Precise intraoperative assessment of microperfusion may have an impact on the surgeon0s intraoperative management and leakage rate. Method In this single center observational study we implemented and integrated intraoperative indocyanin green (ICG) based microperfusion assessment of anastomosis with Pinpoint Perfusion Imaging in a series of consecutive rectal cancer patients who underwent laparoscopic anterior and lower anterior resection with primary anastomosis during a 5-months period. Results We could demonstrate the feasibility and safety of intraoperative fluorescence angiography for colorectal microperfusion assessment. Technology implementation was immediately successful. No adverse effects have been documented related to fluorescent dye. Microperfusion angiography of the colon succeeded in all cases and assessment of perfusion imaging influenced surgical decision making in 28% of the patients, of which all patients showed primary healing of the anastomosis. We found a leakage rate of 6% with one leakage of a coloanal anastomosis in all patients. Conclusion Fluorescence angiography is an accurate tool for assessing microperfusion and is most likely associated with improved outcomes with regard to anastomotic healing.

Association of overall survival in patients with newly diagnosed glioblastoma with contrast-enhanced perfusion MRI: Comparison of intraindividually matched T1 - and T2 (*) -based bolus techniques.

Abstract: Background To compare intraindividual dynamic susceptibility contrast (DSC) and dynamic contrast enhanced (DCE) MR perfusion parameters and determine the association of DCE parameters with overall survival (OS) with the established predictive DSC parameter cerebral blood volume (CBV) in patients with newly diagnosed glioblastoma. Methods Perfusion data were analyzed retrospectively, and included scans performed preoperatively at 3.0 Tesla in 37 patients (25 males, 12 females, 39–83 years, median 65) later diagnosed with glioblastoma. All patients received standard treatment consisting of surgery and radiochemotherapy. Images were spatially coregistered and maximum region of interest-based DCE and DSC parameter measurements compared and thresholds identified using multivariate linear regression, Pearson's correlation coefficients and using receiver operating characteristic analysis. Survival analysis was performed using Kaplan-Meier curves. Results While both, elevated volume transfer constant (Ktrans) (>0.29 min−1; P = 0.041) and CBV (>23.7 mL/100 mL; P < 0.001) were significantly associated with OS, elevated CBV was associated with worse OS compared with elevated Ktrans. Ktrans was significantly correlated with the leakage correction factor K2 but not with CBV. Conclusion The combined use of DSC and DCE MR perfusion may provide additional information of prognostic value for glioblastoma patient survival prediction. As Ktrans was not tightly coupled to CBV, both parameters may reflect different stages in the pathogenetic sequence of glioblastoma growth. J. Magn. Reson. Imaging 2015;42:87–96. © 2014 Wiley Periodicals, Inc.

Dynamic Contrast-Enhanced Perfusion MRI and Diffusion-Weighted Imaging in Grading of Gliomas.

Abstract: PURPOSE Accurate glioma grading is crucial for treatment planning and predicting prognosis. We performed a quantitative volumetric analysis to assess the diagnostic accuracy of histogram analysis of diffusion-weighted imaging (DWI) and dynamic contrast-enhanced (DCE) T1-weighted perfusion imaging in the preoperative evaluation of gliomas. METHODS Sixty-three consecutive patients with pathologically confirmed gliomas who underwent baseline DWI and DCE-MRI were enrolled. The patients were classified by histopathology according to tumor grade: 20 low-grade gliomas (grade II) and 43 high-grade gliomas (grades III and IV). Volumes-of-interest were calculated and transferred to DCE perfusion and apparent diffusion coefficient (ADC) maps. Histogram analysis was performed to determine mean and maximum values for Vp and Ktrans, and mean and minimum values for ADC. Comparisons between high-grade and low-grade gliomas, and between grades II, III, and IV, were performed. A Mann-Whitney U test at a significance level of corrected P ≤ .01 was used to assess differences. RESULTS All perfusion parameters could differentiate between high-grade and low-grade gliomas (P < .001) and between grades II and IV, grades II and III, and grades III and IV. Significant differences in minimum ADC were also found (P < .01). Mean ADC only differed significantly between high and low grades and grades II and IV (P < .01). There were no differences between grades II and III (P = .1) and grades III and IV (P = .71). CONCLUSION When derived from whole-tumor histogram analysis, DCE-MRI perfusion parameters performed better than ADC in noninvasively discriminating low- from high-grade gliomas.

Comparison of the Diagnostic Performance of Four Quantitative Myocardial Perfusion Estimation Methods Used in Cardiac MR Imaging: CE-MARC Substudy.

Abstract: The diagnostic performance of quantitative perfusion measurements is not affected by the choice of tracer kinetic analysis method when stress myocardial blood flow measurements are used.