In Situ Magnetic Resonance Microscopy

Hollett, M D; Cofer, Gary P.; Johnson, G. Allan

doi:10.1097/00004424-198712000-00009

Cited by 37 publications

(25 citation statements)

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“…[13] the ratio of the currents in the two coils-in this instance, it is 4.56 with a 90°p hase difference. It remains to find the field in the positively rotating frame using Eq.…”

Section: Currents and Fieldsmentioning

confidence: 81%

Use of mutually inductive coupling in probe design

Hoult

Tomanek

2002

Concepts Magn. Reson.

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An analysis is presented of mutually inductive coupling in probe design. It is assumed that near field couplings predominate and that lumped constants may therefore be employed. Using three published designs as examples, analytic techniques are presented for assessing B 1 field strength, losses, and signal-to-noise ratio in increasingly complex situations. The perturbing effect of the B 1 field from a matching coil is examined and it is shown that if the coil is too close to the sample there can be an asymmetry introduced in the rotating frame B 1 field. It is then shown that such asymmetries are potentially a general feature of inductively coupled, loaded coils. The importance of suppressing unwanted resonances is highlighted if tuning and matching are to be orthogonal, a potential advantage of mutually inductive matching. Finally, a lumped-constant simulation is briefly described for those situations where an analytic approach becomes too cumbersome.

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“…[13] the ratio of the currents in the two coils-in this instance, it is 4.56 with a 90°p hase difference. It remains to find the field in the positively rotating frame using Eq.…”

Section: Currents and Fieldsmentioning

confidence: 81%

Use of mutually inductive coupling in probe design

Hoult

Tomanek

2002

Concepts Magn. Reson.

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“…Recently a number of researchers have exploited the potential of this tool to develop MR microscopy, in which sections through soft tissues can be viewed at <50 mm resolution to permit noninvasive microscopy on live animals (56)(57)(58)(59). This approach has been used to quantify edema and fibrosis in the lungs of animals exposed to paraquat (60), as well as edema in animals exposed to hyperoxia and ozone U.…”

Section: Noninvasive Methods Of Imaging the Lungmentioning

confidence: 99%

Identification of Subpopulations That Are Sensitive to Ozone Exposure: Use of End Points Currently Available and Potential Use of Laboratory-Based End Points under Development

Devlin¹

1993

Environmental Health Perspectives

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A number of epidemiological studies have attempted to assess the effect of recurrent ozone exposure in humans. For the most part, they have failed to document convincingly an association between chronic ozone exposure and differences in lung function performance or respiratory symptoms. This is not surprising given the small respiratory effects observed in animals chronically exposed to ozone and assuming that people with abnormal respiratory function resulting from other occupational or environmental exposures, such as tobacco smoke, would make up a much larger percentage of the population than people with respiratory effects attributable to ozone. Therefore, either more sensitive end points must be developed to detect subtle changes due to chronic ozone exposure, or ways of selecting subpopulations that are especially sensitive to ozone must be devised. It has been well documented that there are large and reproducible differences in the acute response of individuals to ozone as measured by pulmonary function tests. Recently, it has also been shown that there are large differences in the acute response of individuals to ozone as measured by inflammatory and other biochemical parameters. This paper discusses the problems of selecting individuals who are sensitive to ozone depending on the end point chosen. It also describes potential new sensitive end points that might be available for ozone epidemiology studies in the near future. -Environ Health Perspect 101 (Suppl 4): 225-230 (1993).

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“…Another microimaging modality to visualize serial sections is magnetic resonance microscopy (26,45,94). The resolution of magnetic resonance microscopy depends directly on the magnetic field strength (38).…”

Section: Three-dimensional Analysis Of Serial Sectionsmentioning

confidence: 99%

The use of microcomputed tomography to study microvasculature in small rodents

Bentley

Ortiz

Ritman

et al. 2002

American Journal of Physiology-Regulatory, Integrative and Comp

135

109

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The use of microcomputed tomography to study microvasculature in small rodents. Am J Physiol Regulatory Integrative Comp Physiol 282: R1267-R1279, 2002 10.1152/ajpregu.00560.2001.-Appropriate nephron function is dependent on the intrarenal arrangement of blood vessels. The preferred and primary means to study the architecture of intrarenal circulation has been by filling it with opaque substances such as india ink, radio-opaque contrast material, or various polymers for study by light or scanning electron microscopy. With such methodologies, superficial vessels may obscure deep vessels and little quantitative information may be obtained. Serial-section microtomy has not been practical because of problems relating to alignment and registration of adjacent sections, lost sections, and preparation time and effort. Microcomputed tomography (micro-CT) overcomes such limitations and provides a means to study the three-dimensional architecture of filled vessels within an intact rodent kidney and to obtain more quantitative information. As an example of micro-CT's capabilities, we review the use of micro-CT to study the alterations in renal microvasculature caused by the development of liver cirrhosis after chronic bile duct ligation. In this example, micro-CT evidence shows a selective decrease in cortical vascular filling in the kidney, with a maintenance of medullary vascular filling. These changes may contribute to the salt and water retention that accompanies cirrhosis. These results indicate that micro-CT is a promising method to evaluate renal vascular architecture in the intact rodent kidney relative to physiological and pathological function. kidney; imaging; microcirculation; vasculature APPROPRIATE NEPHRON FUNCTION appears to be dependent on the detailed three-dimensional interrelationship of blood vessels with the tubular components. Many techniques and/or methods have been developed to examine the microanatomic arrangement of pre-and postglomerular vasculature (4,29,36,40,54,55,59,71,98). In this respect, such efforts were prompted by early studies showing that urinary excretion varied in relation to the intrarenal environment and was dependent on the coupling of renal microcirculation and tubular components. In 1947, Trueta and colleagues (96), studying the crush syndrome in rabbits, observed that there was a shift of blood flow from the renal cortex to the medulla during hemorrhage. They suggested this shift to be the major explanation for the lack of urine flow, despite a preservation of renal blood flow (RBF). The shift of blood flow within the renal cortex from superficial short nephrons to deep long nephrons was later observed in sodium-retaining states such as cardiac insufficiency, hepatic cirrhosis, or hypovolemia (1,18,53,104). showed that changes in renal perfusion pressure, within a range (75-130 mmHg) in which RBF remains unchanged (RBF autoregulation), were followed by dramatic changes in sodium excretion. This situation is comparable to that seen in the early stages Address for reprint requ...

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In Situ Magnetic Resonance Microscopy

Cited by 37 publications

References 0 publications

Use of mutually inductive coupling in probe design

Use of mutually inductive coupling in probe design

Identification of Subpopulations That Are Sensitive to Ozone Exposure: Use of End Points Currently Available and Potential Use of Laboratory-Based End Points under Development

The use of microcomputed tomography to study microvasculature in small rodents

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