Regional Lung Density and V?A/Q? Studied with Positron Emission Tomography: Results in Normal Subjects and in Chronic Airflow Obstruction

2015 ◽  
pp. 182-187
Author(s):  
L. H. Brudin ◽  
S. O. Valind ◽  
C. G. Rhodes ◽  
J. M. B. Hughes
Keyword(s):  
Positron Emission Tomography ◽  
Airflow Obstruction ◽  
Normal Subjects ◽  
Emission Tomography ◽  
Lung Density ◽  
Positron Emission ◽  
Regional Lung

Regional lung hematocrit in humans using positron emission tomography

1986 ◽  
Vol 60 (4) ◽  
pp. 1155-1163 ◽  
Author(s):  
L. H. Brudin ◽  
S. O. Valind ◽  
C. G. Rhodes ◽  
D. R. Turton ◽  
J. M. Hughes
Keyword(s):  
Positron Emission Tomography ◽  
Blood Volume ◽  
Venous Blood ◽  
Normal Subjects ◽  
Emission Tomography ◽  
Thoracic Wall ◽  
Positron Emission ◽  
Regional Lung ◽  
Volume Measurements ◽  
Regional Blood Volume

Regional lung hematocrit ratio (R) was measured in five normal subjects and five patients (2 with pneumonia, 2 with nephrotic syndrome with anemia, and 1 with pancreatitis) using positron emission tomography, a red cell marker 11CO, and a plasma marker [methyl-11C]albumin). The measurements were made in a transaxial thoracic section at midheart level with the subject in supine posture and with a spatial resolution of 1.7 cm. The normal regional hematocrit ratio (means +/- SE) calculated for the lung was 0.90 +/- 0.014, 0.94 +/- 0.023 for the thoracic wall, and 1.00 +/- 0.003 for the heart chambers. The regional lung hematocrit ratio in the patients ranged between 0.81 and 0.86. No correlation was found among the regional lung hematocrit ratio and regional blood volume, lung extravascular density, and the peripheral hematocrit (obtained from venous blood samples). To the extent that 70% of the pulmonary blood in the field of view is in larger vessels with normal hematocrit, the hematocrit in the capillary bed is approximately two-thirds that of the peripheral venous value. Blood volume measurements on the basis of single vascular tracers need to take account of these results.

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 Increased Functional Vascular Response in the Region of a Glioma

1998 ◽  
Vol 18 (2) ◽  
pp. 148-153 ◽  
Author(s):  
Jeffrey G. Ojemann ◽  
John M. Neil ◽  
Ann-Mary MacLeod ◽  
Daniel L. Silbergeld ◽  
Ralph G. Dacey ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Word Reading ◽  
Preoperative Assessment ◽  
Normal Subjects ◽  
Emission Tomography ◽  
Vascular Response ◽  
Positron Emission ◽  
Order Of Magnitude ◽  
Verb Generation ◽  
Increased Blood Flow

Functional imaging of a language task using positron emission tomography was performed as part of the preoperative assessment of a patient with a left supplementary motor area (SMA) tumor. Positron emission tomography scans were obtained during language tasks (verb generation and word reading of visually presented nouns) that normally lead to increased blood flow in the SMA relative to a control condition (visual fixation). In the patient, the normal SMA response was an order of magnitude larger in the region of the tumor. Other regions, such as left inferior frontal cortex and right cerebellum, showed equivalent activation in the patient and normal subjects. Histopathologic study revealed an anaplastic astrocytoma. Thus, this exaggerated vascular response to local neuronal activation occurred in the setting of a proliferation of glial cells. This is consistent with models of coupling of regional CBF and neuronal activity that implicate glia as the mediatol between neurons and vasculature. The concept that tumoral disruption of normal vascular responses could, in some cases, potentially enhance rather than dampen the response is proposed.

Age-related changes in brain: II. Positron emission tomography of frontal and temporal lobe glucose metabolism in normal subjects

1995 ◽  
Vol 66 (4) ◽  
pp. 357-370 ◽  
Author(s):  
Susan De Santi ◽  
Mony J. de Leon ◽  
Antonio Convit ◽  
Chaim Tarshish ◽  
Henry Rusinek ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Glucose Metabolism ◽  
Temporal Lobe ◽  
Normal Subjects ◽  
Emission Tomography ◽  
Age Related ◽  
Positron Emission ◽  
Age Related Changes

scholarly journals Measurement of End-Capillary Po2 with Positron Emission Tomography

1988 ◽  
Vol 8 (3) ◽  
pp. 403-410 ◽  
Author(s):  
N. M. Alpert ◽  
R. B. Buxton ◽  
J. A. Correia ◽  
R. M. Katz ◽  
R. H. Ackerman
Keyword(s):  
Positron Emission Tomography ◽  
Oxygen Saturation ◽  
Normal Subjects ◽  
Oxygen Metabolism ◽  
Emission Tomography ◽  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Protein Levels ◽  
Extraction Fraction ◽  
Positron Emission

The analysis of positron emission tomography measurements of oxygen metabolism has been extended to provide a quantitative estimate of end-capillary Po2. The principle of this extension rests on the idea that the oxygen extraction fraction can be used to calculate the end-capillary oxygen saturation of the blood. The relation between oxygen saturation and Po2 is obtained through the oxygen dissociation curve. Our studies show that in addition to the local oxygen extraction fraction, arterial Po2 and pH values are needed in the calculation, whereas fairly large variations in factors such as Pco2, hematocrit, hemoglobin, and plasma protein levels have little or no effect. Rough estimates of end-capillary Po2 can be made using standard o2 dissociation nomograms. Blood gas and acid-base properties of blood have been known for decades, making it possible to account accurately for individual differences that may be encountered when studying patients. Measurements in nine normal subjects yielded a mean end-capillary Po2 value of 31.2 mm Hg. The ability to make a quantitative visualization of altered patterns of end-capillary Po2 provides an additional dimension to the investigation of stroke disease and tumor metabolism.

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.

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