Pediatr Neurosurg ; Dynamic perfusion-CT PCT is a technique for measuring brain hemodynamics that uses first-pass tracer methodology following bolus infusion of intravenous iodinated contrast material. Perfusion CT with iodinated contrast material. AJR ; The effective radiation dose involved in a PCT series ranges around 1.
Using 80kVp versus kVp in perfusion CT measurement of regional cerebral blood flow. For adequate PCT data acquisition, a helical CT scanner capable of operating in the cine mode is needed.
Multislice CT scanners offer the advantage of greater tissue coverage per acquisition usually 2cm compared with single slice CT scanners typically 1cm. Quantitative assessment of regional cerebral blood flows by perfusion CT studies at low injection rates: a critical review of the underlying theoretical models. Eur Radiol ; Quantitative cerebral blood flow measurement with dynamic perfusion CT using the vascular-pixel elimination method: comparison with H2 15 O positron emission tomography. Regions of decreased hemodynamics are often represented as regions of prolonged MTT.
MTT maps have the property of generally being quite sensitive to the presence of altered brain hemodynamics. Comparing CBF, CBV, and MTT values between abnormal regions and mirror-image control regions is an effective method of measuring the degree of underperfusion present in a given case or location. Correlation of early dynamic CT perfusion imaging with whole-brain MR diffusion and perfusion imaging in acute hemispheric stroke. CT perfusion scanning with deconvolution analysis: pilot study in patients with acute middle cerebral artery stroke.
Comparison of admission perfusion computed tomography and qualitative diffusion- and perfusion-weighted magnetic resonance imaging in acute stroke patients. Prognostic accuracy of cerebral blood flow measurement by perfusion computed tomography, at the time of emergency room admission, in acute stroke patients.
Ann Neurol ; It is presently not possible to perform a PCT examination at the bedside.
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PCT has a limited spatial coverage 20 to mm thickness. However, the issue of spatial coverage will be addressed in the near future through the development of multislice CT scanners with greater arrays of elements. Accuracy of dynamic perfusion-CT with deconvolution in detecting acute hemispheric stroke. Dynamic CT perfusion imaging with acetazolamide challenge for the preprocedural evaluation of a patient with symptomatic middle cerebral artery occlusive disease. At the time of this writing, definitions of infarct core and penumbra are undergoing active research to provide understanding of how the method could potentially be used to guide therapy.
Anecdotally, in the setting of unilateral carotid occlusion, PCT imaging may be combined with vasodilatory challenge e. Monitoring cerebral perfusion after subarachnoid hemorrhage using CT. Neuroradiology ; AJNR in press. Admission perfusion CT: prognostic value in patients with severe head trauma. Relationship between brain perfusion computed tomography variables and cerebral perfusion pressure in severe head trauma patients.
Crit Care Med ; Imaging of acute ischemic brain injury: the return of computed tomography. Curr Opin Neurol ; Perfusion imaging with NMR contrast agents. Magn Reson Med ; Click here to see the Library ] , [ 73 G randin CB. Assessment of brain perfusion with MRI: methodology and application to acute stroke.
Perfusion MRI of the human brain with dynamic susceptibility contrast: gradient-echo versus spin-echo techniques.
J Magn Reson Imaging ; The used tracer is a conventional chelate of gadolinium, injected through an 18G catheter into a peripheral vein at a regular dose of 0. DSC does not expose patients to ionizing radiation. Intolerance to gadolinium chelates is very rare. The contraindications are those of MRI in general: pacemakers and some other implanted metallic or electronic devices, obesity more than kg. Fixed ferromagnetic dental devices and intracranial clips generate prominent artifacts.
Claustrophobia or agitation may require sedation. Most 1. The use of a power injector is recommended. Comparative study of methods for determining vascular permeability and blood volume in human gliomas. For qualitative hemodynamic measurements, a pre-load dose of contrast before the bolus is an easier way to minimize the effect of contrast leakage. Using commercially available softwares, various parameters can be calculated in a few minutes from the time-intensity curves measured in each pixel, allowing one to reconstruct parametric maps. These maps do not afford quantitative assessment of brain hemodynamics, but provide indicators of hemodynamic disturbances that are very useful in a clinical setting.
They can be interpreted visually or semi-quantitatively by calculating the ratio or difference between the values in a ROI placed in the abnormal area and a mirror ROI placed in the contralateral area considered as a normal reference. Note that, for the moment, there is no standardization in the interpretation of the DSC parametric maps [ 77 C ha S.
Perfusion MR imaging: basic principles and clinical applications. High resolution measurement of cerebral blood flow using intravascular tracer bolus passages. Part I: mathematical approach and statistical analysis. Absolute cerebral blood flow and volume measured by magnetic resonance imaging bolus tracking: comparison with positron emission tomography values.
This step is more complex with DSC than with PCT because the relationship between the signal intensity and the gadolinium concentration is not always linear [ 81 K iselev VG.
On the theoretical basis of perfusion measurements by dynamic susceptibility contrast MRI. Cerebral blood flow measurements by magnetic resonance imaging bolus tracking: comparison with [ 15 O] H 2 O positron emission tomography in humans. J Comput Assist Tomogr ; Cerebral blood flow and blood volume measured by magnetic resonance imaging bolus tracking after acute stroke in pigs: comparison with [ 15 O]-H 2 O positron emission tomography.
Note that, in order to interpret the DSC perfusion maps quantitatively or semi-quantitatively, it is necessary to mask out the large vessels very prominent with GRE sequences. Under this level, the signal-to-noise ratio becomes too low for a precise quantification [ 85 S chreiber WG. Cerebral blood flow and cerebrovascular reserve capacity: estimation by dynamic magnetic resonanace imaging. DSC has no age limitation and can be performed in children. MRI is not a bedside technique.
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It is not available at night and during weekends in many institutions. A spatial resolution around 1. A delay of 25min between successive contrast injections has been shown to be sufficient for repeated CBF measurements, allowing one to assess the cerebral vascular reserve.
Sequential dynamic susceptibility contrast MR experiments in human brain: residual contrast agent effect, steady state, and hemodynamic perturbation. The main clinical applications of DSC are acute stroke, chronic cerebrovascular disease, and tumors. MRI can be performed in the emergency setting of hyperacute stroke. Hyperacute stroke: simultaneous measurement of relatoive cerebral blood volume, relative cerebral blood flow, and mean tissue transit time.
J Neurol ; A threshold can be applied to DSC maps in order to identify the area at risk for infarction and predict outcome, but no consensus has been achieved regarding the specific thresholds that might distinguish reversible and irreversible ischemia [ 91 G randin CB, D uprez TP, S mith AM, Which MR-derived perfusion parameters predict infarct growth the best in hyperacute stroke?
A comparative study between relative and quantitative measurements. Perfusion-weighted magnetic resonance imaging thresholds identifying core, irreversibly infarcted tissue. Cerebrovascular reserve capacity in patients with occlusive cerebrovascular disease: assessment with dynamic susceptibility contrast-enhanced MR imaging and the acetazolamide stimulation test.
Diffusion- and perfusion-weighted imaging in vasospasm after subarachnoid hemorrhage. Cerebral gliomas: prospective comparison of multivoxel 2D chemical-shift imaging proton MR spectroscopy, echoplanar perfusion and diffusion-weighted MRI. Glioma grading: sensitivity, specificity, and predictive values of perfusion MR imaging and proton MR spectroscopic imaging compared with conventional MR imaging.
Intracranial mass lesions: dynamic contrast-enhanced susceptibility-weighted echo-planar perfusion MR imaging. Assessment of brain tumor angiogenesis inhibitors using perfusion magnetic resonance imaging: quality and analysis results of a phase I trial.
Pdf Cerebral Blood Flow Mathematical Models Instrumentation And Imaging Techniques 1988
Distinction between cerebral abscesses and high-grade neoplasms by dynamic susceptibility contrast perfusion MRI. Arterial spin labeling ASL , also called arterial spin tagging, relies on the detection of magnetically labeled water.
Once the magnetization of the inflowing water has been modified generally inverted upstream, it induces a small MR signal change downstream a few percent of the tissue magnetization. Meanwhile, the magnetization of the perfusion tracer — i. Perfusion imaging.
Measuring cerebral blood flow using magnetic resonance imaging techniques. Perfusion imaging using arterial spin labeling. Top Magn Reson Imaging ; Methodology of brain perfusion imaging. The existing techniques can be sorted out in two categories: pulsed techniques and continuous techniques, depending on how the spin labeling is performed.