User-defined Vascular Input Function Curves: Influence on Mean Perfusion Parameter Values and Signal-to-Noise Ratio

Kealey, Susan; Loving, Vilert A.; DeLong, David M.; Eastwood, James D.

doi:10.1148/radiol.2312030489

Cited by 49 publications

(37 citation statements)

References 8 publications

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“…Establishing a uniform and standard postprocessing technique is essential for maintaining good reproducibility (Fig 2). 39,40 Use of standard head immobilization techniques and adequate patient coaching are important to minimize patient motion. Waaijer et al 41 studied PCT images in 20 patients with unilateral symptomatic carotid artery stenosis to assess the reproducibility of quantitative CTP parameters.…”

Section: Pctmentioning

confidence: 99%

The Acetazolamide Challenge: Techniques and Applications in the Evaluation of Chronic Cerebral Ischemia

Vagal¹,

Leach²,

Fernández-Ulloa³

et al. 2009

AJNR Am J Neuroradiol

167

116

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SUMMARY:The acetazolamide (ACZ) challenge test is a useful clinical tool and a reliable predictor of critically reduced perfusion. In patients with chronic steno-occlusive disease, the ability to maintain normal cerebral blood flow by reducing vascular resistance secondary to autoregulatory vasodilation is compromised. Identification of the presence and degree of autoregulatory vasodilation (reflecting the cerebrovascular reserve) is a significant prognostic factor in patients with chronic cerebrovascular disease. The pharmacologic challenge of a vasodilatory stimulus such as ACZ can also be used to optimize the treatment strategies for these patients. The pathophysiology, methods, and clinical applications of the ACZ challenge test are discussed in this article. Viability of the cerebral parenchyma is dependent on the ability of the brain vasculature to provide adequate levels of cerebral blood flow (CBF). In patients with chronic stenoocclusive disease, the ability to maintain normal CBF by reducing vascular resistance is compromised. Identification of the degree of autoregulatory vasodilation reflects cerebrovascular reserve (CVR), which is a significant prognostic factor in chronic cerebrovascular disease.1-5 Flow reserve can be assessed with the use of paired blood flow measurements, with the initial measurement obtained at baseline and the second, after a vasodilatory stimulus, such as acetazolamide (ACZ). 6 Pathophysiology of Chronic Cerebrovascular DiseaseChronic cerebral hypoperfusion is usually the result of occlusion or stenosis of large arteries in the neck or the circle of Willis. Clinical symptoms and manifestations of brain ischemia in patients with chronic cerebrovascular disease (CVD) develop as a consequence of 2 main mechanisms: embolic events from atherosclerotic plaques resulting in local compromise of blood flow and systemic hemodynamic alterations that further reduce an already compromised cerebral perfusion state. 7The hemodynamic changes due to a decline in cerebral perfusion pressure have been studied by many investigators. 6,[8][9][10][11] Chronic CBF restriction causes a progressive decrease in cerebral perfusion pressure (CPP). Initially, decreases of CPP cause varying degrees of autoregulatory vasodilation of small distal arterioles.12 Powers 10 and Powers et al 11 proposed a 2-stage classification of hemodynamic impairment in patients with CVD. In stage I (autoregulatory vasodilation), autoregulation reduces cerebral vascular resistance. CBF and oxygen extraction fraction (OEF) are not significantly changed. Increases of cerebral blood volume (CBV) and mean transit time (MTT) are 2 parameters that reflect this initial phase of compensatory autoregulatory vasodilation. Further decreases of CPP beyond cerebral autoregulatory vasodilation capacity eventually result in stage II (autoregulatory failure), characterized by decreases of CBF and increases of OEF. When the CBF decreases, neurons increase the fraction of oxygen extracted from the blood to maintain normal neurologic function. ...

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Section: Pctmentioning

confidence: 99%

The Acetazolamide Challenge: Techniques and Applications in the Evaluation of Chronic Cerebral Ischemia

Vagal¹,

Leach²,

Fernández-Ulloa³

et al. 2009

AJNR Am J Neuroradiol

167

116

View full text Add to dashboard Cite

show abstract

“…6,7 This calculation is a noise-sensitive process, 8 and better signal-intensity enhancement will necessarily result in more robust analysis. 9 Because tissue enhancement at any given time during the passage of contrast through the cerebral vasculature depends on the actual amount of contrast agent in the intravascular space, one approach to improve signal-intensity visibility would be to increase the iodine concentration of the contrast material used. To this end, we aimed to evaluate whether increasing contrast agent iodine concentration alone, while keeping the total load of iodine injected constant, resulted in better peak opacification and, thus, enhancement of normal brain tissue in patients with acute stroke symptoms during their evaluation by using first-pass CTP.…”

mentioning

confidence: 99%

Increasing Contrast Agent Concentration Improves Enhancement in First-Pass CT Perfusion

Silvennoinen¹,

Hamberg²,

Valanne³

et al. 2007

American Journal of Neuroradiology

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“…As the absolute CTP parameters, CBV, CBF, MTT and TTP have potential variability caused by the venous output scaling factor and postprocessing steps (7,9). To reduce the variability, the relative CTP parameters including interhemispheric ratios for CBV and CBF, and the interhemispheric differences for MTT and TTP, can be used to evaluate cerebral perfusion (7,9).…”

Section: Sun H Et Al: Ctp For Detecting Cerebral Vasospasm Followingmentioning

confidence: 99%

“…To reduce the variability, the relative CTP parameters including interhemispheric ratios for CBV and CBF, and the interhemispheric differences for MTT and TTP, can be used to evaluate cerebral perfusion (7,9). Unfortunately, the relative CTP parameters were not selected as a research subject for all included articles, and we cannot extract this data for the less variable analysis.…”

Section: Sun H Et Al: Ctp For Detecting Cerebral Vasospasm Followingmentioning

confidence: 99%

Evaluating the diagnostic accuracy of CT perfusion in patients with cerebral vasospasm after aneurysm rupture: a meta-analysis

Sun¹,

Zhang²,

Ma³

et al. 2014

Turkish Neurosurgery

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AIm: Computed tomography perfusion (CTP) has recently been used to identify regions of potential ischemia due to cerebral vasospasm, and CTP parameters are able to quantitatively evaluate brain parenchymal perfusion. We performed a meta-analysis as an update of a previous paper published in 2010 and aimed at evaluating the diagnostic accuracy of CTP and CTP parameters for vasospasm after aneurysm rupture. mATERIAL and mETHods: Relevant articles published between January 2005 and May 2013 were systematically searched for analysis without language restrictions from the PubMed/MEDLINE, Embase, and Cochrane databases. The data of CTP parameters, including CBV, CBF, MTT and TTP, were extracted for analysis, and the pooled sensitivity, specificity, PLR, NLR, DOR and the sROC curve were determined. REsuLTs:Three relevant articles and a total of 98 patients were finally involved in the analysis. The pooled sensitivity, specificity, PLR, NLR, DOR, and AUC of CTP for diagnosing cerebral vasospasm were 94%, 90%, 8.22, 0.06, 141.09, and 0.9802, respectively. Through the evaluation of CTP parameters, MTT had a higher sensitivity (91%) while CBF had a higher specificity (93%). CoNCLusIoN:CT perfusion has a great diagnostic value to detect cerebral vasospasm compared with DSA in patients with aneurysmal subarachnoid hemorrhage (aSAH). As CTP parameters, CBF and MTT quantitatively evaluate brain parenchymal perfusion. soNuÇ: BTP testinin anevrizmal subaraknoid hemorajili (aSAK) hastalarda serebral vazospazmı belirlemede anjiyografiye kıyasla önemli diyagnostik değeri vardır. BTP parametreleri olan CBF ve MTT beyin parankimi perfüzyonunu kantitatif olarak değerlendirirler.ANAHTAR sÖZCÜKLER: BTP, BT perfüzyon, BTP parametreleri, Vazospazm, Serebral vazospazm ABBREVIATIoNs: CTP: computed tomography perfusion, CBV: cerebral blood volume, CBF: cerebral blood flow, mTT: mean transit time, TTP: time to peak, PLR: positive likelihood ratio, NLR: negative likelihood ratio, doR: diagnostic odds ratio, CIs: confidence intervals, sRoC: summary receiver-operating characteristic, dsA: digital substraction angiography, asAH: aneurysmal subarachnoid hemorrhage.

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User-defined Vascular Input Function Curves: Influence on Mean Perfusion Parameter Values and Signal-to-Noise Ratio

Cited by 49 publications

References 8 publications

The Acetazolamide Challenge: Techniques and Applications in the Evaluation of Chronic Cerebral Ischemia

The Acetazolamide Challenge: Techniques and Applications in the Evaluation of Chronic Cerebral Ischemia

Increasing Contrast Agent Concentration Improves Enhancement in First-Pass CT Perfusion

Evaluating the diagnostic accuracy of CT perfusion in patients with cerebral vasospasm after aneurysm rupture: a meta-analysis

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