scholarly journals On the Uniqueness of Cerebral Blood Flow Measured by the in vivo Autoradiographic Strategy and Positron Emission Tomography

1983 ◽  
Vol 3 (4) ◽  
pp. 432-441 ◽  
Author(s):  
Bernard E. Howard ◽  
Myron D. Ginsberg ◽  
William R. Hassel ◽  
Alan H. Lockwood ◽  
Philip Freed
Keyword(s):  
Positron Emission Tomography ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Regional Blood Flow ◽  
Normal Subjects ◽  
Pet Scan ◽  
Emission Tomography ◽  
Start Time ◽  
Positron Emission

Factors are examined in this report which govern the uniqueness and sensitivity of regional cerebral blood flow (rCBF), as determined by an in vivo autoradiographic strategy and positron emission tomography (PET), and a series of theorems is derived which specify conditions under which a unique relationship between cumulative cranial activity of the tracer ( C) and regional blood flow ( f) may be assured. It is demonstrated that, independent of the specific form of the arterial tracer input function, flow is a unique function of C whenever the start time ( T1) of the PET scan is coincident with the start of tracer infusion. Other theorems state that, even for nonzero T1s, a unique solution for flow may be expected, as long as the duration of the scan is sufficiently short. The implementation of this theory is illustrated using arterial tracer activity curves obtained in three normal subjects by a multiple arterial sampling procedure following the bolus i. v. infusion of 20–30 μCi of [15O]water. Based on these arterial curves, it is confirmed that the C vs. f relationship resulting from scan parameters T1 = 0 and T2 = 1.5 min (i.e., a PET scan of 90 s commencing with tracer infusion) has an excellent separation of flow values within the range of physiological interest, whereas a 90-s scan beginning at time T1 = 1.7 min results in poorer separation of flow values and loss of the monotonic relationship between C and f at higher flows. The results of this study serve to clarify the in vivo autoradiographic method for measuring rCBF in humans and help to define favorable study parameters for assuring uniqueness and sensitivity of the flow measurement.

scholarly journals A Simplified in vivo Autoradiographic Strategy for the Determination of Regional Cerebral Blood Flow by Positron Emission Tomography: Theoretical Considerations and Validation Studies in the Rat

1982 ◽  
Vol 2 (1) ◽  
pp. 89-98 ◽  
Author(s):  
Myron D. Ginsberg ◽  
Alan H. Lockwood ◽  
Raul Busto ◽  
Ronald D. Finn ◽  
Cathy M. Butler ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Regional Cerebral Blood Flow ◽  
Animal Studies ◽  
Blood Flow Rate ◽  
Emission Tomography ◽  
Regional Cerebral Blood ◽  
Positron Emission

A simplified mathematical model is described for the measurement of regional cerebral blood flow by positron emission tomography in man, based on a modification of the autoradiographic strategy originally developed for experimental animal studies. A modified ramp intravenous infusion of radiolabeled tracer is used; this results in a monotonically increasing curvilinear arterial activity curve that may be accurately described by a polynomial of low degree (= z). Integrated cranial activity C̄ B is measured in regions of interest during the latter portion of the tracer infusion period (times T1 to T2). It is shown that [Formula: see text] where each of the terms A x is a readily evaluated function of the blood flow rate constant k, the brain:blood partition coefficient for the tracer, the cranial activity integration limits T1 and T2, the coefficients of the polynomial describing the arterial curve, and an iteration factor n that is chosen to yield the desired degree of precision. This relationship permits generation of a table of C̄ B vs. k, thus facilitating on-line computer solution for blood flow. This in vivo autoradiographic paradigm was validated in a series of rats by comparing it to the classical autoradiographic strategy developed by Kety and associates. Excellent agreement was demonstrated between blood flow values obtained by the two methods: CBF in vivo = CBFclassical X 0.99 − 0.02 (units in ml g−1 min−1; correlation coefficient r = 0.966).

scholarly journals Cerebral Blood Flow Measurements by Magnetic Resonance Imaging Bolus Tracking: Comparison with [15O]H2O Positron Emission Tomography in Humans

1998 ◽  
Vol 18 (9) ◽  
pp. 935-940 ◽  
Author(s):  
Leif Østergaard ◽  
Peter Johannsen ◽  
Peter Høst-Poulsen ◽  
Peter Vestergaard-Poulsen ◽  
Helle Asboe ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Magnetic Resonance ◽  
Normal Subjects ◽  
Emission Tomography ◽  
Flow Measurements ◽  
Bolus Tracking ◽  
Positron Emission ◽  
Blood Flow Measurements

In six young, healthy volunteers, a novel method to determine cerebral blood flow (CBF) using magnetic resonance (MR) bolus tracking was compared with [15O]H2O positron emission tomography (PET). The method yielded parametric CBF images with tissue contrast in good agreement with parametric PET CBF images. Introducing a common conversion factor, MR CBF values could be converted into absolute flow rates, allowing comparison of CBF values among normal subjects.

scholarly journals Somatotopic mapping of the primary motor cortex in humans: activation studies with cerebral blood flow and positron emission tomography

1991 ◽  
Vol 66 (3) ◽  
pp. 735-743 ◽  
Author(s):  
S. T. Grafton ◽  
R. P. Woods ◽  
J. C. Mazziotta ◽  
M. E. Phelps
Keyword(s):  
Positron Emission Tomography ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Motor Cortex ◽  
Repeated Measures ◽  
Primary Motor Cortex ◽  
Emission Tomography ◽  
Precentral Gyrus ◽  
Positron Emission

1. The somatotopic representation of the human primary motor cortex was examined noninvasively with estimates of cerebral blood flow (CBF) obtained with positron emission tomography. Twelve normal subjects performed a motor tracking task with the arm, first finger, tongue, and great toe commensurate with the bolus injection of radioactive H215O. Images of the relative percent increase of blood flow, compared with control studies, demonstrated reproducible foci of CBF increases in the motor cortex in every subject. Each motor task could be localized to a predictable site on a coronal section containing the precentral gyrus. 2. In reproducibility experiments of repeated measures, it was determined that two foci of activation in the primary motor cortex could be discriminated with a 95% confidence if they were separated by 5.4 mm. 3. In five subjects with matched magnetic resonance imaging studies, the sites of activation were variable with respect to surface anatomy and could be found at the depth of sulci or the surface of gyri. The findings were similar to previously reported electrophysiological studies using direct cortical stimulation. 4. The method may be applied to the in vivo functional mapping of the primary motor cortex in patients with cerebral disorders.

scholarly journals Effects of Acetazolamide on Cerebral Blood Flow, Blood Volume, and Oxygen Metabolism: A Positron Emission Tomography Study with Healthy Volunteers

2001 ◽  
Vol 21 (12) ◽  
pp. 1472-1479 ◽  
Author(s):  
Hidehiko Okazawa ◽  
Hiroshi Yamauchi ◽  
Kanji Sugimoto ◽  
Hiroshi Toyoda ◽  
Yoshihiko Kishibe ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Metabolic Rate ◽  
Blood Volume ◽  
Cerebral Blood Volume ◽  
Capillary Blood ◽  
Emission Tomography ◽  
Positron Emission ◽  
Capillary Blood Volume

To evaluate changes in cerebral hemodynamics and metabolism induced by acetazolamide in healthy subjects, positron emission tomography studies for measurement of cerebral perfusion and oxygen consumption were performed. Sixteen healthy volunteers underwent positron emission tomography studies with15O-gas and water before and after intravenous administration of acetazolamide. Dynamic positron emission tomography data were acquired after bolus injection of H215O and bolus inhalation of15O2. Cerebral blood flow, metabolic rate of oxygen, and arterial-to-capillary blood volume images were calculated using the three-weighted integral method. The images of cerebral blood volume were calculated using the bolus inhalation technique of C15O. The scans for cerebral blood flow and volume and metabolic rate of oxygen after acetazolamide challenge were performed at 10, 20, and 30 minutes after drug injection. The parametric images obtained under the two conditions at baseline and after acetazolamide administration were compared. The global and regional values for cerebral blood flow and volume and arterial-to-capillary blood volume increased significantly after acetazolamide administration compared with the baseline condition, whereas no difference in metabolic rate of oxygen was observed. Acetazolamide-induced increases in both blood flow and volume in the normal brain occurred as a vasodilatory reaction of functioning vessels. The increase in arterial-to-capillary blood volume made the major contribution to the cerebral blood volume increase, indicating that the raise in cerebral blood flow during the acetazolamide challenge is closely related to arterial-to-capillary vasomotor responsiveness.

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