scholarly journals Role of MR Sequences in the Assessment of Gadolinium-dependent T1 Signal Intensity Increase after Repeated Exposure to Linear Gadolinium-based Contrast Agents

Radiology ◽  
2017 ◽  
Vol 282 (1) ◽  
pp. 299-300
Author(s):  
Carlo Cosimo Quattrocchi ◽  
Daniela Longo
Keyword(s):  
Contrast Agents ◽  
Signal Intensity ◽  
Repeated Exposure ◽  
Intensity Increase ◽  
Mr Sequences

scholarly journals No Signal Intensity Increase in the Dentate Nucleus on Unenhanced T1-weighted MR Images after More than 20 Serial Injections of Macrocyclic Gadolinium-based Contrast Agents

Radiology ◽  
2017 ◽  
Vol 282 (3) ◽  
pp. 699-707 ◽  
Author(s):  
Alexander Radbruch ◽  
Robert Haase ◽  
Pascal J. Kieslich ◽  
Lukas D. Weberling ◽  
Philipp Kickingereder ◽  
...  
Keyword(s):  
Contrast Agents ◽  
Signal Intensity ◽  
Dentate Nucleus ◽  
Intensity Increase ◽  
Mr Images

Cerebrospinal Fluid Signal Intensity Increase on FLAIR MR Images in Patients under General Anesthesia: The Role of Supplemental O2

Radiology ◽  
2001 ◽  
Vol 218 (1) ◽  
pp. 152-156 ◽  
Author(s):  
Anastasia V. Deliganis ◽  
David J. Fisher ◽  
Arthur M. Lam ◽  
Kenneth R. Maravilla
Keyword(s):  
Cerebrospinal Fluid ◽  
General Anesthesia ◽  
Signal Intensity ◽  
Intensity Increase ◽  
Mr Images ◽  
Fluid Signal

scholarly journals The role of breast magnetic resonance imaging in the diagnosis of ductal carcinoma in situ

2013 ◽  
Vol 141 (5-6) ◽  
pp. 402-408 ◽  
Author(s):  
Mirjan Nadrljanski ◽  
Zorica Milosevic ◽  
Vesna Plesinac­Karapandzic ◽  
Branislav Goldner
Keyword(s):  
Contrast Enhancement ◽  
Signal Intensity ◽  
Carcinoma In Situ ◽  
Ductal Carcinoma ◽  
Breast Magnetic Resonance Imaging ◽  
Intensity Increase ◽  
Resonance Imaging ◽  
Breast Magnetic Resonance

Ductal carcinoma in situ (DCIS), the noninvasive breast malignant tumor originates from the terminal ductal?lobular units (TDLU). The typical feature of DCSI is the formation of calcifications. Up to 90% of DCIS are diagnosed on mammographic examinations, as clinically asymptomatic. Between 10% and 20% of DCIS remain mammographically occult due to the lack of calcifications and/ or small tumor dimensions. Contrast?enhanced breast magnetic resonance imaging (MRI) detects mammographically occult breast lesions, thus defining morphologic features of the lesion and the dynamics of signal intensity changes due to contrast enhancement. Distribution of contrast enhancement - signal intensity increase in DCIS most frequently includes segmental, ductal and linear patterns, followed by regional enhancement pattern, while the intralesional contrast uptake most frequently includes the nodular pattern with the areas of confluence. Post? contrast signal intensity increase in DCIS is most frequently fast in the initial phase (wash?in), while the whole dynamic of contrast?enhancement includes either of the three possible time?intensity curve (TIC) types (persistent, plateau or washout), although the plateau TIC is considered to be more frequent. Breast MRI has high sensitivity in the diagnosis of invasive breast cancer, varying from 90% to 100%; the sensitivity in the diagnosis of DCIS is lower (77?96%). For the time being, the primary role of MRI in DCIS is planning of breast?conserving surgery (BCS) for the evaluation of lesion extension. Further development of MRI in the diagnosis of DCIS includes the implementation of the principles of functional and molecular imaging.

scholarly journals Perceived truth of statements and simulated social media postings: an experimental investigation of source credibility, repeated exposure, and presentation format

2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Lena Nadarevic ◽  
Rolf Reber ◽  
Anne Josephine Helmecke ◽  
Dilara Köse
Keyword(s):  
Social Media ◽  
Source Credibility ◽  
Repeated Exposure ◽  
Presentation Format ◽  
The Internet ◽  
Additive Effects ◽  
Fake News ◽  
Source Information ◽  
Internet Age

Abstract To better understand the spread of fake news in the Internet age, it is important to uncover the variables that influence the perceived truth of information. Although previous research identified several reliable predictors of truth judgments—such as source credibility, repeated information exposure, and presentation format—little is known about their simultaneous effects. In a series of four experiments, we investigated how the abovementioned factors jointly affect the perceived truth of statements (Experiments 1 and 2) and simulated social media postings (Experiments 3 and 4). Experiment 1 explored the role of source credibility (high vs. low vs. no source information) and presentation format (with vs. without a picture). In Experiments 2 and 3, we additionally manipulated repeated exposure (yes vs. no). Finally, Experiment 4 examined the role of source credibility (high vs. low) and type of repetition (congruent vs. incongruent vs. no repetition) in further detail. In sum, we found no effect of presentation format on truth judgments, but strong, additive effects of source credibility and repetition. Truth judgments were higher for information presented by credible sources than non-credible sources and information without sources. Moreover, congruent (i.e., verbatim) repetition increased perceived truth whereas semantically incongruent repetition decreased perceived truth, irrespectively of the source. Our findings show that people do not rely on a single judgment cue when evaluating a statement’s truth but take source credibility and their meta-cognitive feelings into account.

The Role of Water Exchange in Attaining Maximum Relaxivities for Dendrimeric MRI Contrast Agents

1996 ◽  
Vol 2 (12) ◽  
pp. 1607-1615 ◽  
Author(s):  
Éva Tóth ◽  
Dirk Pubanz ◽  
Sylvain Vauthey ◽  
Lothar Helm ◽  
André E. Merbach
Keyword(s):  
Contrast Agents ◽  
Water Exchange ◽  
Mri Contrast Agents ◽  
Mri Contrast

scholarly journals The Role of Serotonin in MDMA Self-administration in Rats

2021 ◽  
Author(s):  
◽  
Sarah Bradbury
Keyword(s):  
Negative Impact ◽  
Primary Objective ◽  
Repeated Exposure ◽  
Lesion Group ◽  
Control Group ◽  
Self Administration ◽  
Initial Exposure ◽  
Abstinence Period

<p>Rationale: The profile of acquisition for MDMA self-administration differs from that of amphetamine and cocaine self-administration in that fewer rats meet an acquisition criterion and the latency to acquisition is longer. These characteristics of MDMA self-administration may be because it preferentially stimulates serotonin (5HT) release whereas self-administration has generally been attributed to enhanced dopamine (DA) neurotransmission. Because 5HTergic agonists are not self-administered and increased synaptic 5HT decreased self-administration of other drugs, MDMA self-administration may be initially inhibited by the pronounced 5HT response. Accordingly, the acquisition of MDMA self-administration might proceed as a result of deficits in 5HT neurotransmission and a corresponding disinhibition of DA neurotransmission.  Objective: The primary objective was to determine the role of 5HT in the acquisition and maintenance of MDMA self-administration.  Methods: MDMA-induced increases of extracellular 5HT and DA and their primary metabolites were measured in the DA terminal regions of the nucleus accumbens (NAc) using in vivo microdialysis, prior to the commencement of MDMA self-administration. The relationship between MDMA-induced increases of neurotransmitter levels and the acquisition of MDMA self-administration was assessed. A subsequent study depleted brain 5HT by administering the neurotoxin, 5,7 – DHT, or vehicle into the lateral ventricle of the left hemisphere, prior to the commencement of MDMA self-administration. The proportion of subjects that acquired MDMA self-administration and the latency to acquire MDMA self-administration was compared for the two groups. In order to determine effects of MDMA self-administration on 5HT and DA responses, behaviours that reflect 5HT and/or DA neurotransmission were measured 5 or 14 days after self-administration of 165 mg/kg MDMA, or 14 days after vehicle self-administration. These time periods were chosen because they reflect a period of 5HT deficits (5 days) and recovery (14 days). Finally, the effect of abstinence on MDMA self-administration was measured.  Results: The MDMA-induced increase of extracellular 5HT was significantly lower for the group that subsequently acquired MDMA self-administration but the MDMA-induced increase in DA was not different from the group that failed to acquire self-administration. 5, 7-DHT administration significantly decreased tissue levels of 5HT, but not DA. MDMA self-administration was facilitated by the lesion; 100% of the lesion group acquired MDMA self-administration, whereas only 50% of the control group acquired self-administration. Five days following the last MDMA self-administration session, DAergic behaviours were enhanced and 5HTergic behaviours were reduced relative to the control group. These differences in 5HTergic mediated behaviours were not apparent 14 days after self-administration but the DAergic behaviours remained elevated. The pattern of self-administration did not differ as a function of the length of the abstinence period.  Conclusions: The variability in acquisition of MDMA self-administration was related to the magnitude of the 5HT response evoked by initial exposure to MDMA. These findings suggested that predisposing differences in the 5HT response might explain differences in the variability in acquisition of MDMA self-administration. The negative impact of 5HT on the acquisition of MDMA self-administration was clearly demonstrated following a 5, 7-DHT lesion. Thus, 5HT limits the development of MDMA self-administration. With repeated exposure to self-administered MDMA, behavioural responses indicative of 5HT activation were reduced whereas behavioural indices of DA activation were increased. The maintenance of MDMA self-administration was comparable regardless of whether there was a forced abstinence period or not. These data are consistent with the hypotheses that 5HT is inhibitory to the acquisition, but not the maintenance, of MDMA self-administration. Rather, the maintenance of self-administration might reflect sensitised DA responses that became apparent following repeated exposure.</p>

The role of hydrogen bonding in tuning CEST contrast efficiency: A comparative study of intra and inter molecular hydrogen bonding

2022 ◽  
Author(s):  
Shalini Pandey ◽  
Subhayan Chakraborty ◽  
Rimilmandrita Ghosh ◽  
Divya Radhakrishnan ◽  
Saravanan Peruncheralathan ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Comparative Study ◽  
Contrast Agents ◽  
Diagnostic Tool ◽  
Molecular Hydrogen

The effectiveness of MRI as a diagnostic tool have increased tremendously after the discovery of contrast agents (CA). Most of the clinically approved CAs at present are relaxation based and...

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