scholarly journals Age-Dependent Changes in Total and Free Water Content of In Vivo Human Lenses Measured by Magnetic Resonance Imaging

2021 ◽  
Vol 62 (9) ◽  
pp. 33
Author(s):  
Alyssa L. Lie ◽  
Xingzheng Pan ◽  
Thomas W. White ◽  
Ehsan Vaghefi ◽  
Paul J. Donaldson
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Water Content ◽  
Free Water ◽  
Resonance Imaging ◽  
Free Water Content ◽  
Age Dependent ◽  
Human Lenses

scholarly journals An Absolute Measurement of Brain Water Content Using Magnetic Resonance Imaging in Two Focal Cerebral Ischemic Rat Models

2000 ◽  
Vol 20 (1) ◽  
pp. 37-44 ◽  
Author(s):  
Weili Lin ◽  
Ramesh Venkatesan ◽  
Kilichan Gurleyik ◽  
Yong Y. He ◽  
William J. Powers ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Water Content ◽  
Spin Density ◽  
Absolute Measurement ◽  
Brain Water Content ◽  
Resonance Imaging ◽  
Regional Brain ◽  
Brain Water

Magnetic resonance imaging (MRI) was utilized to obtain absolute estimates of regional brain water content (W), and results were compared with those obtained with conventional wet/dry measurements. In total, 31 male Long-Evans rats were studied and divided into two groups based on the surgical procedures used to induce cerebral focal ischemia: suture (n = 18) and three-vessel ligation (TVL; n = 13) groups. Both relative spin density and T1 were extracted from the acquired MR images. After correcting for radiofrequency field inhomogeneities, T2* signal decay, and temperature effects, in vivo regional brain water content, in absolute terms, was obtained by normalizing the measured relative brain spin density of animals to that of a water phantom. A highly linear relationship between MR-estimated brain water content based on the normalized spin density and wet/dry measurements was obtained with slopes of 0.989 and 0.986 for the suture ( r = 0.79) and TVL ( r = 0.83) groups, respectively. Except for the normal subcortex of the TVL group ( P < 0.02) and the normal hemisphere of the suture group ( P < 0.003), no significant differences were observed between MR-estimated and wet/dry measurements of brain water content. In addition, a highly linear relationship between MR-measured R1 (= 1/T1) and 1/W of wet/dry measurements was obtained. However, slopes of the linear regression lines in the two groups were significantly different ( P < 0.02), indicating that different R1 values were associated with the same water content depending on the model. These results show that an absolute measurement of in vivo regional brain water content can be obtained with MRI and potentially serves as a noninvasive means to monitor different therapeutic interventions for the management of brain edema subsequent to stroke and head trauma.

Freeze tolerance in turtles: visual analysis by microscopy and magnetic resonance imaging

1994 ◽  
Vol 267 (4) ◽  
pp. R1078-R1088 ◽  
Author(s):  
B. Rubinsky ◽  
J. S. Hong ◽  
K. B. Storey
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Visual Analysis ◽  
Abdominal Cavity ◽  
Free Water ◽  
Freeze Tolerance ◽  
The Body ◽  
Resonance Imaging ◽  
Freezing And Thawing

Two visual techniques were used to analyze the patterns of natural freezing and thawing in freeze-tolerant hatchling painted turtles Chrysemys picta marginata. Directional solidification plus light microscopy of liver, heart, and skeletal muscle slices was used to compare freezing at -4 degrees C (a survivable temperature in vivo) and -20 degrees C (not survivable). At -4 degrees C tissues showed large amounts of ice in expanded extracellular and vascular spaces, occupying 36% (liver) and 61% (muscle) of total tissue volume. Cells at -4 degrees C were shrunken, but intracellular water remained; at -20 degrees C, however, cells showed little evidence of free water. Liver micrographs showed novel spherical shells of water associated with intracellular particles (apparently glycogen granules) suggesting that a noncolligative method of cell water retention was employed. Proton magnetic resonance imaging was used for noninvasive analysis of freezing and thawing in the intact animal. Images showed that freezing propagated in a directional manner through the body with ice formed first in extraorgan spaces (e.g., abdominal cavity, brain ventricles). However, thawing occurred uniformly throughout the body core, and organs melted more rapidly than the extraorgan ice surrounding them.

scholarly journals Changes in water content and distribution in Quercus ilex leaves during progressive drought assessed by in vivo 1H magnetic resonance imaging.

2010 ◽  
Vol 10 (1) ◽  
pp. 188 ◽  
Author(s):  
Jordi Sardans ◽  
Josep Penuelas ◽  
Silvia Lope-Piedrafita
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Water Content ◽  
Quercus Ilex ◽  
Resonance Imaging

The use of in vivo magnetic resonance imaging and spectroscopy to study porcine stress syndrome in young, halothane-susceptible pigs: Preliminary results

1994 ◽  
Vol 74 (1) ◽  
pp. 37-43
Author(s):  
Edward G. Janzen ◽  
Wendy A. Stewart ◽  
Rheal A. Towner ◽  
Paula J. Gareau
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Free Water ◽  
Simultaneous Increase ◽  
Resonance Spectroscopy ◽  
Resonance Imaging ◽  
Stress Syndrome ◽  
Porcine Stress Syndrome

Magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) studies on young, halothane-susceptible pigs (4 wk old) are reported. The proton image shows distinct changes in shape of the hindleg muscle as the stress syndrome develops. Simultaneous evaluations of the "free water" content by volume selective spectroscopy shows an increase of about 40% after onset of the syndrome. The in vivo phosphorus spectrum obtained as a function of time before and after the stress event clearly shows a drop in phosphocreatine with simultaneous increase in inorganic phosphate. A drop in pH can also be detected after some delay. This study illustrates the broad applicability of noninvasive MRI and MRS in investigations of porcine stress syndrome. Key words: PSS, porcine stress syndrome, MRI, magnetic resonance imaging, 31P MRS, phosphorus-31 magnetic resonance spectroscopy

scholarly journals Magnetic resonance imaging suggests functional role of previous year vessels and fibres in ring-porous sap flow resumption

2019 ◽  
Vol 39 (6) ◽  
pp. 1009-1018 ◽  
Author(s):  
Paul Copini ◽  
Frank J Vergeldt ◽  
Patrick Fonti ◽  
Ute Sass-Klaassen ◽  
Jan den Ouden ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Water Content ◽  
Water Flow ◽  
Resonance Imaging ◽  
Complex Process ◽  
Leaf Formation ◽  
Stem Water ◽  
Earlywood Vessels

Abstract Reactivation of axial water flow in ring-porous species is a complex process related to stem water content and developmental stage of both earlywood-vessel and leaf formation. Yet empirical evidence with non-destructive methods on the dynamics of water flow resumption in relation to these mechanisms is lacking. Here we combined in vivo magnetic resonance imaging and wood-anatomical observations to monitor the dynamic changes in stem water content and flow during spring reactivation in 4-year-old pedunculate oaks (Quercus robur L.) saplings. We found that previous year latewood vessels and current year developing earlywood vessels form a functional unit for water flow during growth resumption. During spring reactivation, water flow shifted from latewood towards the new earlywood, paralleling the formation of earlywood vessels and leaves. At leaves' full expansion, volumetric water content of previous rings drastically decreased due to the near-absence of water in fibre tissue. We conclude (i) that in ring-porous oak, latewood vessels play an important hydraulic role for bridging the transition between old and new water-conducting vessels and (ii) that fibre and parenchyma provides a place for water storage.

Absolute measurements of water content using magnetic resonance imaging: Preliminary findings in an in vivo focal ischemic rat model

2000 ◽  
Vol 43 (1) ◽  
pp. 146-150 ◽  
Author(s):  
R. Venkatesan ◽  
W. Lin ◽  
K. Gurleyik ◽  
Y.Y. He ◽  
R.P. Paczynski ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Water Content ◽  
Rat Model ◽  
Resonance Imaging ◽  
Absolute Measurements
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