Comparison of Different Pulse Sequences for in Vivo Determination of T1 Relaxation Times in the Human Brain

1988 ◽  
Vol 29 (2) ◽  
pp. 231-236 ◽  
Author(s):  
L. Kjær ◽  
O. Henriksen
Keyword(s):  
Human Brain ◽  
Pulse Sequences ◽  
Relaxation Times ◽  
Clinical Work ◽  
Inversion Recovery ◽  
Tissue Type ◽  
Whole Body ◽  
T1 Relaxation

Quantitative in vivo determination of T1 relaxation times by magnetic resonance imaging (MRI) is hampered by several potential sources of error. This study focused on the influence of the radiofrequency pulse sequences applied with special attention to the significance of the repetition time (TR). T1 measurements were performed on the human brain using a whole body MR scanner operating at 1.5 tesla. Three different pulse sequences were compared including two 6-points inversion recovery (IR) sequences with TR = 2.0 s and 4.0, respectively, and a 12-points partial saturation inversion recovery (PSIR) sequence with TR varying between 0.24 and 8.0 s. The median T1 relaxation times obtained in cortical grey matter and cerebrospinal fluid were significantly shorter in the IR experiments at TR = 2 s than in those carried out at TR = 4 s. Concerning white matter the discrepancy was much less pronounced, but still statistically significant. Supplementary phantom measurements indicated that the higher T1 values are increasingly underestimated when TR is reduced to 2 s. The results suggest that the PSIR sequence or IR sequences with a TR > 2 × the T1 level of the tissue type investigated should be employed for accurate T1 determination by MRI in clinical work.

In Vivo Measurements of the T1 Relaxation Processes in the Bone Marrow in Patients with Myelodysplastic Syndrome

1989 ◽  
Vol 30 (4) ◽  
pp. 365-368 ◽  
Author(s):  
K. E. Jensen ◽  
H. Nielsen ◽  
C. Thomsen ◽  
P. G. Sørensen ◽  
H. Karle ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Myelodysplastic Syndrome ◽  
Relaxation Times ◽  
Whole Body ◽  
Relaxation Processes ◽  
Vertebral Bone ◽  
T1 Relaxation ◽  
Vertebral Bone Marrow ◽  
Body Scanner

Nine patients with myelodysplastic syndrome (MDS) were examined with magnetic resonance imaging and in vivo T1 relaxation time measurements of the vertebral bone marrow in a 1.5 tesla whole body scanner. Two patients underwent transformation to acute myeloid leukemia and were evaluated at follow-up examinations. At the time of diagnosis the T1 relaxation times of the vertebral bone marrow were significantly prolonged compared with normal values. The T1 relaxation times of the vertebral bone marrow in patients with MDS showed significantly lower values compared with patients with acute leukemia and did not differ from patients with polycythemia vera.

scholarly journals Validation and feasibility of liver T1 mapping using free breathing MOLLI sequence in children and young adults

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yeon Jin Cho ◽  
Woo Sun Kim ◽  
Young Hun Choi ◽  
Seul Bi Lee ◽  
SeungHyun Lee ◽  
...  
Keyword(s):  
Young Adults ◽  
Relaxation Times ◽  
Free Breathing ◽  
Phantom Study ◽  
Inversion Recovery ◽  
Breath Hold ◽  
T1 Relaxation ◽  
Molli Sequence ◽  
Children And Young Adults ◽  
The Mean

Abstract We investigated the feasibility of free-breathing modified Look-Locker inversion recovery (MOLLI) sequence for measuring hepatic T1 values in children and young adults. To investigate the accuracy and the reproducibility of the T1 maps, a phantom study was performed with 12 different gadoterate meglumine concentrations and the T1 relaxation times of phantoms measured with the MOLLI sequence were compared against those measured with three different sequences: spin-echo inversion recovery, variable flip angle (VFA), and VFA with B1 correction. To evaluate the feasibility of free-breathing MOLLI sequence, hepatic T1 relaxation times obtained by free-breathing and breath-hold technique in twenty patients were compared. The phantom study revealed the excellent accuracy and reproducibility of MOLLI. In twenty patients, the mean value of hepatic T1 values obtained by free-breathing (606.7 ± 64.5 ms) and breath-hold (609.8 ± 64.0 ms) techniques showed no significant difference (p > 0.05). The Bland–Altman plot between the free-breathing and breath-hold revealed that the mean difference of T1 values was − 3.0 ms (− 0.5%). Therefore, T1 relaxation times obtained by MOLLI were comparable to the values obtained using the standard inversion recovery method. The hepatic T1 relaxation times measured by MOLLI technique with free-breathing were comparable to those obtained with breath-hold in children and young adults.

RBE Determination of Acute In Vivo Effects from Very Low Dose Whole-body Exposure with Different Radiation Qualities by Three In VitroAssays

1985 ◽  
Vol 13 (1-4) ◽  
pp. 191-194 ◽  
Author(s):  
W. Porschen ◽  
H. Mühlensiepen ◽  
J. Marx ◽  
C. Lindberg ◽  
L.E. Feinendegen
Keyword(s):  
Low Dose ◽  
Whole Body ◽  
In Vivo Effects

Spin-echo methods for the determination of 31P transverse relaxation times of the ATP NMR signals in vivo

1994 ◽  
Vol 12 (1) ◽  
pp. 121-129 ◽  
Author(s):  
Klaus Straubinger ◽  
Wulf-Ingo Jung ◽  
Michael Bunse ◽  
Otto Lutz ◽  
Klaus Küper ◽  
...  
Keyword(s):  
Spin Echo ◽  
Relaxation Times ◽  
Transverse Relaxation ◽  
Nmr Signals

Detection of allergen-induced airway hyperresponsiveness in isolated mouse lungs

2006 ◽  
Vol 291 (3) ◽  
pp. L466-L472 ◽  
Author(s):  
Martin Witzenrath ◽  
Birgit Ahrens ◽  
Stefanie M. Kube ◽  
Armin Braun ◽  
Heinz G. Hoymann ◽  
...  
Keyword(s):  
Airway Hyperresponsiveness ◽  
Ex Vivo ◽  
Whole Body ◽  
Strongly Correlated ◽  
Ex Vivo Model ◽  
Isolated Lungs ◽  
Spontaneously Breathing

Airway hyperresponsiveness (AHR) is a hallmark of bronchial asthma. Important features of this exaggerated response to bronchoconstrictive stimuli have mostly been investigated in vivo in intact animals or in vitro in isolated tracheal or bronchial tissues. Both approaches have important advantages but also certain limitations. Therefore, the aim of our study was to develop an ex vivo model of isolated lungs from sensitized mice for the investigation of airway responsiveness (AR). BALB/c mice were sensitized by intraperitoneal ovalbumin (Ova) and subsequently challenged by Ova inhalation. In vivo AR was measured in unrestrained animals by whole body plethysmography after stimulation with aerosolized methacholine (MCh) with determination of enhanced pause ( Penh). Twenty-four hours after each Penh measurement, airway resistance was continuously registered in isolated, perfused, and ventilated lungs on stimulation with inhaled or intravascular MCh or nebulized Ova. In a subset of experiments, in vivo AR was additionally measured in orotracheally intubated, spontaneously breathing mice 24 h after Penh measurement, and lungs were isolated further 24 h later. Isolated lungs of allergen-sensitized and -challenged mice showed increased AR after MCh inhalation or infusion as well as after specific provocation with aerosolized allergen. AR was increased on days 2 and 5 after Ova challenge and had returned to baseline on day 9. AHR in isolated lungs after aerosolized or intravascular MCh strongly correlated with in vivo AR. Pretreatment of isolated lungs with the β2-agonist fenoterol diminished AR. In conclusion, this model provides new opportunities to investigate mechanisms of AHR as well as pharmacological interventions on an intact organ level.

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