A multiple-pulse sequence for improved selective excitation in magnetic resonance imaging

1985 ◽  
Vol 12 (4) ◽  
pp. 413-418 ◽  
Author(s):  
Dwight G. Nishimura
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Pulse Sequence ◽  
Selective Excitation ◽  
Resonance Imaging ◽  
Multiple Pulse

scholarly journals Optimization of pulse sequences in ultrafast magnetic resonance imaging for the diagnosis of acute abdominal pain caused by gastrointestinal disease

2020 ◽  
Vol 9 (8) ◽  
pp. 205846012094924 ◽  
Author(s):  
Akitoshi Inoue ◽  
Akira Furukawa ◽  
Norihisa Nitta ◽  
Kai Takaki ◽  
Shinichi Ohta ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Abdominal Pain ◽  
Magnetic Resonance ◽  
Diagnostic Accuracy ◽  
Acute Abdominal Pain ◽  
Pulse Sequence ◽  
Pulse Sequences ◽  
Resonance Imaging ◽  
True Fisp ◽  
Significant Difference

Background Magnetic resonance imaging (MRI) is widely used to diagnose acute abdominal pain; however, it remains unclear which pulse sequence has priority in acute abdominal pain. Purpose To investigate the diagnostic accuracy of MRI and to assess the conspicuity of each pulse sequence for the diagnosis of acute abdominal pain due to gastrointestinal diseases Material and Methods We retrospectively enrolled 60 patients with acute abdominal pain who underwent MRI for axial and coronal T2-weighted (T2W) imaging, fat-suppressed (FS)-T2W imaging, and true-fast imaging with steady-state precession (True-FISP) and axial T1-weighted (T1W) imaging and investigated the diagnosis with endoscopy, surgery, histopathology, computed tomography, and clinical follow-up as standard references. Two radiologists determined the diagnosis with MRI and rated scores of the respective sequences in assessing intraluminal, intramural, and extramural abnormality using a 5-point scale after one month. Diagnostic accuracy was calculated and scores were compared by Wilcoxon-signed rank test with Bonferroni correction. Results Diagnostic accuracy was 90.0% and 93.3% for readers 1 and 2, respectively. Regarding intraluminal abnormality, T2W, FS-T2W, and True-FISP imaging were superior to T1W imaging in both readers. FS-T2W imaging was superior to True-FISP in reader 2 ( P < 0.0083). For intramural findings, there was no significant difference in reader 1, whereas T2W, FS-T2W, and True-FISP imaging were superior to T1W imaging in reader 2 ( P < 0.0083). For extramural findings, FS-T2W imaging was superior to T2W, T1W, and True-FISP imaging in both readers ( P < 0.0083). Conclusion T2W and FS-T2W imaging are pivotal pulse sequences and should be obtained before T1W and True-FISP imaging.

In vivo Measurement of Water Self Diffusion in the Human Brain by Magnetic Resonance Imaging

1987 ◽  
Vol 28 (3) ◽  
pp. 353-361 ◽  
Author(s):  
C. Thomsen ◽  
O. Henriksen ◽  
P. Ring
Keyword(s):  
Magnetic Resonance Imaging ◽  
White Matter ◽  
Magnetic Resonance ◽  
Tissue Characterization ◽  
Pulse Sequence ◽  
Benign Intracranial Hypertension ◽  
Resonance Imaging ◽  
Self Diffusion ◽  
Brain Water

A new pulse sequence for in vivo diffusion measurements by magnetic resonance imaging (MRI) is introduced. The pulse sequence was tested on phantoms to evaluate the accuracy, reproducibility and inplane variations. The sensitivity of the sequence was tested by measuring the self diffusion coefficient of water with different temperatures. This phantom study showed that the water self diffusion could be measured accurately and that the inplane deviation was less than ±10 per cent. Seven healthy volunteers were studied with a 10 mm thick slice through the lateral ventricles, clear differences between grey and white matter as well as regional differences within the white matter were seen. In two patients with infarction, alternations in water self diffusion were seen in the region of the infarct. Likewise, pronounced changes in brain water self diffusion were observed in a patient with benign intracranial hypertension. The results indicate that brain water self diffusion can be measured in vivo with reasonable accuracy. The clinical examples suggest that diffusion measurements may be clinically useful adding further information about in vivo MR tissue characterization.

Normal and Abnormal Temporomandibular Joints as Demonstrated by Magnetic Resonance Imaging

1986 ◽  
Vol 27 (3) ◽  
pp. 331-333
Author(s):  
D. L. Kreipke ◽  
D. J. Conces ◽  
A. Sondhi ◽  
J. C. Lappas ◽  
G. T. Augustyn
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Pulse Sequence ◽  
Mandibular Condyle ◽  
Joint Space ◽  
High Signal ◽  
Resonance Imaging ◽  
Posterior Portion ◽  
Signal Structure ◽  
Condylar Head

Magnetic resonance imaging of the temporomandibular joint (TMJ) was performed on two normal volunteer subjects and two symptomatic subjects using a 0.15 T resistive magnet. A spin echo pulse sequence with a TE of 38 ms and a TR of 500 ms was employed. The TMJ meniscus is a low signal structure, and the bilaminar zone behind it is a relatively high signal structure. In normal closed mouths, the demarcation between meniscus and bilaminar zone is located at the vertex position above the mandibular condyle. When the condyle translates, the posterior portion of the meniscus bulges into the joint space. Dislocated meniscus can be identified by a gray mass anterior to the condylar head. The joint space is filled with the higher signal of the bilaminar zone. In non-reducible dislocations, the meniscus remains anterior to the condylar head with opening of the mouth. Reduced dislocations appear similar to normal joints in the open mouth. References

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