The Partition of Trace Amounts of Xenon Between Human Blood and Brain Tissues at 37°C

Veall, N.; Mallett, B. L.

doi:10.1088/0031-9155/10/3/306

Cited by 179 publications

(53 citation statements)

References 8 publications

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“…The calculated blood flow will depend substantially on the partition coefficient of the tissue under study. In our measurements of partition coefficient by the technique of Veall & Mallett (1965) the values varied very little between normal and metastatic liver tissue.…”

Section: Discussionmentioning

confidence: 68%

The blood supply of colorectal liver metastases

Taylor¹,

Bennett²,

Sherriff³

1978

Br J Cancer

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Summary.-Post-mortem studies suggest that liver metastases obtain the majority of their nutrition from the hepatic artery; however, cytotoxic arterial perfusion with or without hepatic-artery ligation has not proved entirely successful as a therapeutic regime.In this study we have measured blood flow into colorectal liver metastases using xenon-133 (133Xe) clearance in patients undergoing surgery for colorectal cancer.Pre-operative measurements after direct parenchymal injection gave a mean flow of 41-5 i 22.5 ml/min/100 g which after hepatic arterial occlusion perfusion, was reduced to a mean of 5o% of the pre-occlusion value.Dynamic blood-flow studies using the gamma camera were performed in the postoperative period by administration of 133Xe into both hepatic arterial and portal venous catheters. The initial distribution images indicated a predominant arterial perfusion to the metastases, but after hepatic-artery ligation, portal-vein perfusion to the metastases was statistically significantly increased.Hence, a compensatory haemodynamic mechanism exists which may account for the poor results of hepatic-artery ligation and perfusion alone.

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Section: Discussionmentioning

confidence: 68%

The blood supply of colorectal liver metastases

Taylor¹,

Bennett²,

Sherriff³

1978

Br J Cancer

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“…The input func tion to the brain (the arterial curve) was modeled as a rectangular pulse of duration T (saturation time) con volved with a biexponential curve described by two rel ative weights, a fast and a slow exponential constant. For a given ratio of gray/white cerebral matter, input func tion, and duration of measurement (de saturation time) D, the result of the simulation has the formJ(jg,fw) giving the "observed" Kety-Schmidt CBF value J as a function of two variables, the assumed gray and white matter blood flows (jg, fw)' In all simulations the ratio of gray/white matter weights was set at 60:40 (Veall and Mallett, 1965) and gray matter and white matter A was set to 0.85 and 1.50 mllg, respectively (Veall and Mallett, 1965). The three variables describing the arterial input function were derived from the average of all observed arterial input functions (Fig.…”

Section: Simulating Proceduresmentioning

confidence: 99%

Average Blood Flow and Oxygen Uptake in the Human Brain during Resting Wakefulness: A Critical Appraisal of the Kety—Schmidt Technique

Madsen

Holm

Herning

et al. 1993

J Cereb Blood Flow Metab

118

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Summary:The Kety-Schmidt technique can be regarded as the reference method for measurement of global aver age cerebral blood flow (average CBF) and global average cerebral metabolic rate of oxygen (average CMR02). However, in the practical application of the method, dif fusion equilibrium for inert gas tracer between the brain and its venous blood is not reached. As a consequence, normal values for CBF and CMR02 of 54 ml 100 g-I min -I and 3.5 ml100 g-I min -I obtained with the Kety Schmidt technique are an overestimation of the true val ues. Using the Kety-Schmidt technique we have per formed 57 measurements of CBF and CMR02 during EEG-verified wakeful rest in young normal adults. In or der to estimate the equilibrium values for CBF and CMR02, a simple computer-based simulation model wasIn 1944, Seymour S. Kety, then working in the laboratory of Carl F. Schmidt, developed the first method to quantitate global average cerebral blood flow (average CBF) and global average cerebral metabolic rate of oxygen (average CMR02) (Kety and Schmidt, 1945;Schmidt, 1982). The method is based on the Fick principle and thus represents a practical application of the law of conservation of matter. Due to its solid theoretical foundation, the Kety-Schmidt technique is today, 48 years later, still accepted as the reference method for determi nation of average levels of CBF and CMR02 (Siesjj

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“…12 A value of 1.10 ml/gm was used for the whole brain-blood partition coefficient for xenon 15 to yield the cerebral blood flow in ml/min/lOOgms. The final value of cerebral blood flow was calculated assuming that the 133 Xe 10-min height/area method systematically overestimates flow by 11%.…”

Section: Measurements and Calculationsmentioning
confidence: 99%

Factors which affect cerebral uptake and retention of 13NH3.
Phelps¹,
Hoffman²,
Raybaud³
1977
Stroke
90
2
35
0
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SUMMARYThe single pass extraction of ammonia (E) by cerebral capillaries was studied in vivo in rhesus monkeys with 1S N. The value of E for 13 N-ammonia was found to be less than 100%, inversely related to cerebral blood flow and to be limited by the permeability of the blood brain barrier for ammonia. A value of the permeability surface area product was determined to be 0.0040 cm 3 /sec/gm. The single pass extraction fraction, E, for 13 N-ammonia was found to be independent of arterial blood pH (in the range of 7.2 to 7.6) and of arterial blood ammonia concentration (in the range of 80-1400 ngms/100 ml). An insulin induced hypoglycemic reduction in the cerebral metabolic rate for glucose and oxygen of 54% produced a reduction in E of about 24%. When a condition of elevated arterial blood ammonia was added to hypoglycemia, the value of E and cerebral metabolic rate for oxygen remained low while the cerebral metabolic rate for glucose increased by a factor of 2.2 indicating the presence of a detoxification shunt for ammonia. Positron tomographic images of the equilibrium cross section distribution of 13 N-ammonia appeared to reflect regional differences in variations of capillary density that are found in the cerebral tissue.

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The Partition of Trace Amounts of Xenon Between Human Blood and Brain Tissues at 37°C

Cited by 179 publications

References 8 publications

The blood supply of colorectal liver metastases

The blood supply of colorectal liver metastases

Average Blood Flow and Oxygen Uptake in the Human Brain during Resting Wakefulness: A Critical Appraisal of the Kety—Schmidt Technique

Factors which affect cerebral uptake and retention of 13NH3.

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