Distribution Volume Of Water Research Articles

Blood Flow and Glucose Metabolism in Stage IV Breast Cancer: Heterogeneity of Response During Chemotherapy

ObjectiveThe purpose of the study was to compare early changes in blood flow (BF) and glucose metabolism (MRglu) in metastatic breast cancer lesions of patients treated with chemotherapy.MethodsEleven women with stage IV cancer and lesions in breast, lymph nodes, liver, and bone were scanned before treatment and after the first course of chemotherapy. BF, distribution volume of water (Vd), MRglu/BF ratio, MRglu and its corresponding rate constants K1 and k3 were compared per tumor lesion before and during therapy.ResultsAt baseline, mean BF and MRglu varied among different tumor lesions, but mean Vd was comparable in all lesions. After one course of chemotherapy, mean MRglu decreased in all lesions. Mean BF decreased in breast and node lesions and increased in bone lesions. Vd decreased in breast and nodes, but did not change in bone lesions. The MRglu/BF ratio decreased in breast and bone lesions and increased in node lesions. In patients with multiple tumor lesions BF and MRglu response could be very heterogeneous, even within similar types of metastases. BF and MRglu increased in lesions of patients who experienced early disease progression or showed no response during clinical follow-up.ConclusionBF and MRglu changes separately give unique information on different aspects of tumor response to chemotherapy. Changes in BF and MRglu parameters can be remarkably heterogeneous in patients with multiple lesions.

Age, alcohol metabolism and liver disease

Alcohol consumption among the elderly has increased. Alcohol metabolism changes with age and the elderly are more sensitive to the toxic effects; this increased consumption is therefore of great clinical relevance. Metabolism of ethanol changes with advancing age because activity of the enzymes involved, such as alcohol and acetaldehyde dehydrogenase and cytochrome P-4502E1, diminish with age. The water distribution volume also decreases with age. Both lead to increased blood concentrations of ethanol. Also, elderly people take more drugs, and ethanol and these drugs may interact; therefore, alcohol consumption can modify serum drug concentrations and their toxicity. Finally, elderly people may suffer more frequently from other types of liver disease, and alcohol may exacerbate these. Over recent decades alcohol consumption has increased among those who are older than 65 years. Alcohol is more toxic in the ageing organism because of changes in its metabolism, distribution and elimination, which lead to central nervous system effects at lower levels of intake; also, ageing organs such as brain and liver are more sensitive to the toxicity of alcohol. For these reasons, alcohol should be used in moderation, especially among those of older age.

Shortened T2 after exercise in ischemic skeletal muscle

To detect skeletal muscle ischemia with transverse relaxometry after ischemic exercise. Ten subjects with intermittent claudication were studied. T2 was measured in the gastrocnemius and soleus muscles (m. gastrocnemius and m. soleus) at rest and repeatedly after exercise during 45 minutes of recovery. Prior to MRI a symptom-limited treadmill exercise was performed, and the ankle-arm blood pressure index (AAI) was measured at rest and after exercise. In the 14 legs with ischemic pain, a diverging response was found in the calf: T2 increased in m. gastrocnemius by 5.6% +/- 4.9%, but decreased in m. soleus by -1.2% +/- 4.4% (P < 0.001). Moreover, 13 regions in legs with ischemic pain and reduced AAI (from 0.7 +/- 0.2 at rest to 0.31 +/- 0.15 after exercise) had shortened T2 (-3.6% +/- 1.8%) immediately after exercise. This finding was most frequent in m. soleus and two regions of m. gastrocnemius. Recovery was delayed in the latter two regions. T2 may identify ischemic muscles after hypoxic exercise. Shortened T2 suggests a reduced water content (e.g., distribution volume of water) and may affect the upslope kinetics of an extravascular perfusion tracer. The different responses to ischemia by the soleus and gastrocnemius muscle may be due in part to their different fiber type compositions.

Structural Analysis of Hemodialysis Membranes by Evaluating Distribution Volume of Water Contained in the Membranes

The distribution volume of water contained in 31 hemodialysis membranes made from seven polymers was measured by three different methods. Water contained in the membranes was classified into three groups according to thermal mobility of the molecules. Structural analysis of the membranes was feasible through determining proportion of nonfreezing water to total water contained in the membranes.

PET: blood flow and oxygen consumption in brain tumors.

Tissue perfusion and cerebral energy metabolism in brain tumor patients are regionally abnormal, and certain patterns of pathological changes may be demonstrated in and around tumor tissue. Tumor CBF may vary widely between subjects, whereas oxygen extraction is almost always markedly reduced. This is in apparent contradiction with the tumor tissue oxygen tension data (see previous chapter): since these are low, an increase of OER would be expected. Still, as discussed above, oxygen consumption calculated from oxygen tension or PET data yield the same relative decreases (0.3) of tumor oxygen utilization compared to normal brain. This suggests that the characteristic pathological changes of tumor cell energy metabolism have diminished oxygen demand and changed the level of coupling between CBF and OER. Since all published data on OER in tumor patients have been obtained by the steady state method, possibly resulting in an underestimation of OER, it will be mandatory to apply dynamic oxygen uptake measurements to circumvent this methodological problem and e.g. to make use of distribution volume of water to correct for tissue composition as has been reported in one paper studying patients with breast tumors. Because of the conspicuous regional changes in tumor oxygen metabolism it is expected that effectivity of chemotherapeutic measures is directly reflected by characteristical adaptations of metabolism. Systematic studies in this context have not been reported to date. Whether oxygen metabolism changes would be more sensitive than just CBF measurements as indicator of treatment effectivity remains to be seen.

Quantitative measurement of local cerebral blood flow in humans by positron computed tomography and 15O-water.

A noninvasive method that employs 15O-water and positron-computed tomography (PCT) was used to measure quantitative local cerebral blood flow (lCBF) in man. 15O-Water (about 30-50 mCi) was introduced through a single-breath inhalation of 15O-carbon dioxide or through an intravenous bolus injection of 15O-water. A sequence of five 2-min PCT scans was initiated at the time of tracer administration. A series of 15-20 blood samples (1 ml each) was withdrawn from the radial artery of the subject over a period of 10 min. Oxygen-15 radioactivities in the blood samples were immediately counted in a well counter to give an input function, which together with the projection data collected by PCT were processed to provide images of 1CBF and local water distribution volume. The method was found to be convenient to use and gave good-quality images of 1CBF. Quantitative values of 1CBF in images were 59 +/- 11 and 20 +/- 4 ml/min/100 g for gray and white matter, respectively, with a gray-to-white matter ratio of 2.93 and a global flow value of 42 +/- 8 ml/min/100 g. Distribution volume of water was 0.85 +/- 0.03, 0.76 +/- 0.03, and 0.81 +/- 0.02 ml/g respectively, for gray matter, white matter, and whole brain.

Transcapillary exchange and distribution of carbon‐11 labelled ethanol in the isolated perfused rat liver

The distribution kinetics of ethanol in the isolated perfused rat liver at various flow rates and ethanol concentrations were studied by the indicator diffusion technique using 11C-labelled ethanol. A double tracer solution with 99mTc-labelled red blood cells as the vascular reference and 11C-ethanol as the test substance was injected into the catheter connected to the portal vein. Time-activity curves were monitored by a NaI(Tl) scintillation detector above the outflow catheter. The following values were obtained: 0.95 +/- 0.01 for the maximal extraction (Emax), 3.0 +/- 0.1 x flow (r = 0.98) for the capillary permeability surface area product (PScap), 18.7 +/- 2.5% for the vascular volume (V1) and 56.2 +/- 9.0% for the ethanol distribution volume (V2). The volumes were calculated from the products of mean transit time (MTT) and flow (f), and PScap was calculated from the equation PScap = -f x ln(1-Emax). The results show that the ethanol distribution in the liver is flow limited since Emax was constant at various flow rates (0.67-2.55 ml/g x min-1). The distribution volumes obtained agree well with the values for liver vascular volume and water distribution volume reported in the literature.

PERICAPILLARY GAS AND WATER DISTRIBUTION VOLUMES OF THE LUNG CALCULATED FROM MULTIPLE INDICATOR DILUTION CURVES.

Simultaneous indicator dilution curves of albumin I 131 , tritiated water, and an inert gas are identical when the indicators do not traverse a capillary bed. When the same three indicators traverse the pulmonary capillaries before sampling, the shapes of the tritiated water and inert gas dilution curves are altered by movement of these two indicators into an extravascular water space and gas space respectively. The arithmetical difference between the distribution volumes of albumin I 131 and tritiated water measures a functional extravascular water space in the lungs. The difference between tritiated water and inert gas distribution volumes is a measure of a lung gas volume in contact with perfusing capillaries. Pericapillary water distribution volume in normal dogs was found to be 4.2 ± 0.8 ml/kg and the gas distribution volume 24 ± 6 ml/kg. In normal human subjects the respective values were 1.1 ± 0.3 ml/cm height and 1.80 ± 0.28 liters/m 2 of body surface area. Changes in both gas and water distribution volumes were observed as a result of experimental pulmonary edema in dogs and in various forms of pulmonary disease in man.