scholarly journals Method for Imaging the States of Water by Nuclear Magnetic Resonance in Low-water-containing Apple Bud and Stem Tissues

1993 ◽  
Vol 118 (5) ◽  
pp. 628-631 ◽  
Author(s):  
Merle M. Millard ◽  
Dehua Liu ◽  
Michael J. Line ◽  
Miklos Faust
Keyword(s):  
Magnetic Resonance Imaging ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Malus Domestica ◽  
Woody Plants ◽  
Relaxation Times ◽  
Tissue Type ◽  
Proton Density ◽  
Resonance Imaging ◽  
T2 Relaxation

Magnetic resonance imaging estimates unreasonably high T2 times when creating T2 images in woody plants when tissues contain a limited amount of water. We developed a system to correct such images. Tissue distribution of proton density and states of water were determined by creating images of proton density and T2 relaxation times in summerdormant (paradormant) apple (Malus domestica Borkh.) buds. These images reveal that the proton density and water states obviously are not distributed uniformly in the bud and stem; but, the distribution of water depends greatly on the tissue type (bark, xylem, or meristem of the stem), and there are differences in the states of water even within the same tissue. At low proton density T2, calculated relaxation times were unreasonably high in tissues, with the exception of meristem of the shoot. In buds that were induced to grow and in which proton density was higher, T2 times appeared as expected. Variance of T2 times in tissues containing little water was 50 times higher than in those with a higher water content. Data with such high variance were excluded from the images; thus, the image was “corrected.” Corrected images of T2 times fit the distribution of water indicated by the proton density images well.

scholarly journals States of Water in Summer-dormant Apple Buds Determined by Proton Magnetic Resonance Imaging

1993 ◽  
Vol 118 (5) ◽  
pp. 632-637 ◽  
Author(s):  
Dehua Liu ◽  
Miklos Faust ◽  
Merle M. Millard ◽  
Michael J. Line ◽  
Gary W. Stutte
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Relaxation Times ◽  
Free Water ◽  
Potential Gradient ◽  
Growth Potential ◽  
Proton Density ◽  
Resonance Imaging ◽  
T2 Relaxation ◽  
Terminal Bud

Magnetic resonance imaging was used to determine water states in paradormant apple (Malus domestica Borkh.) buds and during early events when buds resumed growth. Proton density and states of water were determined by creating image maps of proton density and relaxation times (T2). Summer-dormant (paradormant) buds had T2 relaxation times up to 30 ms. This water in bud tissues is considered relatively free compared to water that had T2 relaxation times of <1 ms in other parts of the stem and bark. Buds were forced to grow either by pruning off the terminal bud or by starting the bud with thidiazuron (TDZ). Both treatments gave essentially the same results. After treatment, buds started to grow immediately and water moved into the stem and into the bud. As there was more free water in the bud, T2 values ranged up to 50 ms. There appeared to be an inhibitory gradient down on the shoot, which was removed temporarily by excising the top bud. However, between the 2nd and 10th day after removal of the top bud this dominance was reinstated by the highest bud on the stem, which eventually formed a shoot. TDZ treatment overcame this inhibitory gradient effect. There was also a growth potential gradient coinciding with the inhibitory gradient. The growth of lower buds was much slower than that of the upper buds. The growth potential gradient was not overcome by TDZ treatments.

Evaluation of Relaxation Time Measurements by Magnetic Resonance Imaging

1987 ◽  
Vol 28 (3) ◽  
pp. 345-351 ◽  
Author(s):  
L. Kjær ◽  
C. Thomsen ◽  
O. Henriksen ◽  
P. Ring ◽  
M. Stubgaard ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Relaxation Time ◽  
Magnetic Resonance ◽  
Diffusion Processes ◽  
Relaxation Times ◽  
Gradient Field ◽  
Maximum Deviation ◽  
Resonance Imaging ◽  
T2 Relaxation ◽  
T1 And T2

Several circumstances may explain the great variation in reported proton T1 and T2 relaxation times usually seen. This study was designed to evaluate the accuracy of relaxation time measurements by magnetic resonance imaging (MRI) operating at 1.5 tesla. Using a phantom of nine boxes with different concentrations of CuSO4 and correlating the calculated T1 and T2 values with reference values obtained by two spectrometers (corrected to MRI-proton frequency=64 MHz) we found a maximum deviation of about 10 per cent. Measurements performed on a large water phantom in order to evaluate the homogeneity in the imaging plane showed a variation of less than 10 per cent within 10 cm from the centre of the magnet in all three imaging planes. Changing the gradient field strength apparently had no influence on the T2 values recorded. Consequently diffusion processes seem without significance. It is concluded that proton T1 and T2 relaxation times covering the majority of the biologic range can be measured by MRI with an overall accuracy of 5 to 10 per cent. Quality control studies along the lines indicated in this study are recommended.

scholarly journals Nuclear Magnetic Resonance Imaging of Grape Buds during the Photoperiodic Induction of Dormancy

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 898D-898 ◽  
Author(s):  
Anne Fennell ◽  
M.J. Line ◽  
M. Faust
Keyword(s):  
Magnetic Resonance Imaging ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Water Status ◽  
Relaxation Times ◽  
The State ◽  
Nuclear Magnetic Resonance Imaging ◽  
Photoperiodic Induction ◽  
Resonance Imaging ◽  
T1 And T2

Changes in water status have been associated with various stages of dormancy and freezing tolerance in woody perennials. Recent studies in apple indicate that changes in the state (bound vs. free) of bud water are strongly correlated with the end of dormancy. In this study nuclear magnetic resonance imaging (NMRI) was used to monitor changes in the state of bud water during the photoperiodic induction of endo-dormancy in Vitis riparia. Bud water status was monitored using proton relaxation times from T1 and T2 images determined at 2, 4, and 6 weeks of long (LD) or short (SD) photoperiod treatments. Bud dormancy was determined by monitoring budbreak in plants defoliated after photoperiod treatments. NMRI allowed nondestructive monitoring of changes in tissue water state. T1 and T2 maps indicated changes in the state of the water in bud and stem tissues during the 6 weeks of treatment. Differences in relaxation times for nondormant and dormancy-induced (reversible) buds were not clear. However, T2 relaxation times were lower in the dormant buds than in the nondormant buds.

scholarly journals Identifying Differential Tissue Response in Grape (Vitis riparia) During Induction of Endodormancy Using Nuclear Magnetic Resonance Imaging

2001 ◽  
Vol 126 (6) ◽  
pp. 681-688 ◽  
Author(s):  
Anne Fennell ◽  
Michael J. Line
Keyword(s):  
Magnetic Resonance Imaging ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Relaxation Times ◽  
Nuclear Magnetic Resonance Imaging ◽  
Tissue Response ◽  
Resonance Imaging ◽  
Vitis Riparia ◽  
Differential Tissue ◽  
Nuclear Magnetic

Physiological and biophysical changes were monitored during shoot maturation and bud endodormancy induction in grape (Vitis riparia Michx.) under controlled environments. Growth, dry weight (DW), periderm development, bud endodormancy, and nuclear magnetic resonance imaging (MRI) T2 relaxation times were monitored at 2, 4, or 6 weeks of long-photoperiod [long day (LD), 15 h, endodormancy inhibition] or short-photoperiod [short day (SD), 8 h, endodormancy induction] treatments at 15/9 h day/night thermoperiod of 25/20 ± 3 °C. Shoots on LD plants grew throughout the entire study period, although the rate of growth decreased slightly during the 6th week. Shoot growth slowed significantly after 2 weeks of SD, was minimal by the 4th week of SD and most of the shoot tip meristems had abscised after 6 weeks of SD. Endodormancy was induced after 4 weeks of SD. DW of the stem and buds increased with increasing duration of LD and SD. While bud DW increased more under SD than LD, stem DW increased more under LD than SD. T2 relaxation times were calculated from images of transverse sections of the grape node. There was a slight decrease in the T2 times in the node tissues with increased duration of LD treatment, whereas SD induced a significant decrease in T2 times during endodormancy induction. T2 values for the node decreased after 4 weeks of SD, coinciding with endodormancy induction. Separation of node tissues into bud, leaf gap, and the remainder of the stem and analysis of the proportion of short and long T2 times within those tissues indicated differential tissue response. A greater proportion of short T2 times were observed in the 2-week SD leaf gap tissue than in the LD and the proportion of short T2 times continued to increase with subsequent SD treatment. Bud and all other stem tissues had a greater proportion of short T2 times after 4 weeks of SD, coinciding with bud endodormancy induction. The proportion of short and long T2 times in a tissue was a better indicator of endodormancy than the averaged T2 time for the tissue. Thus, MRI allows nondestructive identification of differential tissue response to photoperiod treatments and makes it possible to separate normal vegetative maturation responses from endodormancy induction.

Age dependency of cartilage magnetic resonance imaging T2 relaxation times in asymptomatic women

2004 ◽  
Vol 50 (9) ◽  
pp. 2820-2828 ◽  
Author(s):  
Timothy J. Mosher ◽  
Yi Liu ◽  
Qing X. Yang ◽  
Jing Yao ◽  
Ryan Smith ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Relaxation Times ◽  
Age Dependency ◽  
Resonance Imaging ◽  
T2 Relaxation ◽  
Asymptomatic Women

PRIMARY MALIGNANT MELANOMA OF THE CEREBELLOPONTINE ANGLE

Neurosurgery ◽  
2006 ◽  
Vol 59 (6) ◽  
pp. E1336-E1336 ◽  
Author(s):  
Chima O. Oluigbo ◽  
Stephen R. Cooke ◽  
Peter A. Flynn ◽  
Kishor A. Choudhari
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Malignant Melanoma ◽  
Cerebellopontine Angle ◽  
Clinical Presentation ◽  
Relaxation Times ◽  
Primary Malignant Melanoma ◽  
Resonance Imaging ◽  
T2 Relaxation ◽  
T1 And T2

Abstract OBJECTIVE To present a rare case of a primary malignant melanoma of the central nervous system presenting as a cerebellopontine angle (CPA) tumor and to delineate aspects of the clinical presentation and magnetic resonance imaging scan characteristics that may suggest this unusual condition. CLINICAL PRESENTATION The clinical presentation consisted of a short duration of right-sided sensorineural hearing loss, facial weakness, and ataxia in a previously healthy man. Brain magnetic resonance imaging scans showed a right-sided CPA tumor exhibiting shortening of T1 and T2 relaxation times, but overall neuroradiological features were not consistent with any commonly occurring CPA tumors. INTERVENTION Gross total excision of the lesion was accomplished via a right suboccipital craniectomy. Histological examination revealed a malignant melanoma. A detailed search excluded extracranial primary melanoma. CONCLUSION Correlation of clinical and imaging findings offer the most important clues in the diagnosis of such unusual primary malignant tumors of the CPA. A history of rapid onset of audiovestibular symptoms, presence of facial palsy, and shortening of T1 and T2 relaxation times on magnetic resonance imaging scans should arouse the clinician's suspicions.

scholarly journals From signal-based to comprehensive magnetic resonance imaging

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Gyula Kotek ◽  
Laura Nunez-Gonzalez ◽  
Mika W. Vogel ◽  
Gabriel P. Krestin ◽  
Dirk H. J. Poot ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Relaxation Times ◽  
Homogeneous Magnetic Field ◽  
Proton Density ◽  
Resonance Imaging ◽  
Experimental Conditions ◽  
Magnetic Resonance Parameters ◽  
Magnetic Resonance Imaging Mri

AbstractWe present and evaluate a new insight into magnetic resonance imaging (MRI). It is based on the algebraic description of the magnetization during the transient response—including intrinsic magnetic resonance parameters such as longitudinal and transverse relaxation times (T1, T2) and proton density (PD) and experimental conditions such as radiofrequency field (B1) and constant/homogeneous magnetic field (B0) from associated scanners. We exploit the correspondence among three different elements: the signal evolution as a result of a repetitive sequence of blocks of radiofrequency excitation pulses and encoding gradients, the continuous Bloch equations and the mathematical description of a sequence as a linear system. This approach simultaneously provides, in a single measurement, all quantitative parameters of interest as well as associated system imperfections. Finally, we demonstrate the in-vivo applicability of the new concept on a clinical MRI scanner.

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