scholarly journals Dynamic diffusion‐weighted hyperpolarized 13 C imaging based on a slice‐selective double spin echo sequence for measurements of cellular transport

2018 ◽  
Vol 81 (3) ◽  
pp. 2001-2010 ◽  
Author(s):  
Xucheng Zhu ◽  
Jeremy W. Gordon ◽  
Robert A. Bok ◽  
John Kurhanewicz ◽  
Peder E.Z. Larson
Keyword(s):  
Spin Echo ◽  
Cellular Transport ◽  
Double Spin ◽  
Diffusion Weighted ◽  
Spin Echo Sequence ◽  
Dynamic Diffusion

Double spin-echo sequence for rapid spectroscopic imaging of hyperpolarized 13C

2007 ◽  
Vol 187 (2) ◽  
pp. 357-362 ◽  
Author(s):  
Charles H. Cunningham ◽  
Albert P. Chen ◽  
Mark J. Albers ◽  
John Kurhanewicz ◽  
Ralph E. Hurd ◽  
...  
Keyword(s):  
Spin Echo ◽  
Spectroscopic Imaging ◽  
Hyperpolarized 13C ◽  
Double Spin ◽  
Spin Echo Sequence

scholarly journals Evaluating the Origin of the Brain Metastatic Tumors by Using DWI Parameters

2019 ◽  
Vol 6 (3) ◽  
pp. 92-97
Author(s):  
Farnoush Mousavi ◽  
Fariborz Faeghi ◽  
Hamed Javadian ◽  
Hamidreza Haghighatkhah ◽  
Saeed Oraee-Yazdani
Keyword(s):  
Breast Cancer ◽  
Lung Cancer ◽  
Brain Metastases ◽  
Diffusion Weighted Imaging ◽  
Spin Echo ◽  
Metastatic Tumors ◽  
Diffusion Weighted ◽  
Spin Echo Sequence ◽  
Adc Values ◽  
The Brain

Background: Brain metastases are the most common tumors in the human central nervous system (CNS), with an occurrence 10 times higher than primary brain tumors in adults. A radiologist usually diagnoses these tumors. Typically, magnetic resonance imaging (MRI) has been used to evaluate the status and number of metastases, the design of surgical treatment or radiotherapy, and the response to treatment. This study aimed to consider the origin of metastatic tumors of the brain using diffusionweighted imaging sequence. Methods: In this study, 95 lesions observed in 51 patients with different types of brain metastasis who analyzed with standard brain MRI protocols such as T2-weighted fast spin-echo in sagittal, coronal and axial planes and T1-weighted spin-echo sequences before and after injection of contrast enhancement and diffusion-weighted imaging. The diffusion-weighted imaging included an echoplanar spin-echo sequence with two b values (0,1000 s/mm) and calculated apparent diffusion coefficient (ADC) maps. We measured the ADC-value on normalized ADC maps and compared them with different methods. ANOVA was used to compare ADC among all groups as well as T-test for every two groups. Results: The results showed that patients with lung cancer (squamous cell carcinoma, SCC) had the lowest mean ADC (658.70*10-3 mm2 /s) and breast cancer patients with the highest mean ADC(935.52*10-3 mm2 /s). This study demonstrated that most Brain metastases had low and intermediate ADC values. The analysis showed no significant difference among all groups. However, ADC values in breast cancer and kidney and lung (adenocarcinoma) were statistically higher in comparison to other groups. There were no critical discrepancies between ADC values in brain metastases from Breast cancer and lung cancer (adenocarcinoma) and kidney. Conclusion: It seems that evaluating the origin of the brain metastatic tumors by using diffusion imaging (DWI) parameters could be helpful to prevent invasive methods like biopsies in some situations. Although it needs more studies to achieve this purpose.

scholarly journals Empirical field mapping for gradient nonlinearity correction of multi-site diffusion weighted MRI

2020 ◽  
Author(s):  
Colin B. Hansen ◽  
Baxter P. Rogers ◽  
Kurt G. Schilling ◽  
Vishwesh Nath ◽  
Justin A. Blaber ◽  
...  
Keyword(s):  
Spin Echo ◽  
Statistical Tests ◽  
Mean Diffusivity ◽  
Ground Truth ◽  
B Value ◽  
Correction Method ◽  
Spatial Gradient ◽  
Phantom Data ◽  
Diffusion Weighted ◽  
Spin Echo Sequence

ABSTRACTBackgroundAchieving inter-site / inter-scanner reproducibility of diffusion weighted magnetic resonance imaging (DW-MRI) metrics has been challenging given differences in acquisition protocols, analysis models, and hardware factors.PurposeMagnetic field gradients impart scanner-dependent spatial variations in the applied diffusion weighting that can be corrected if the gradient nonlinearities are known. However, retrieving manufacturer nonlinearity specifications is not well supported and may introduce errors in interpretation of units or coordinate systems. We propose an empirical approach to mapping the gradient nonlinearities with sequences that are supported across the major scanner vendors.Study TypeProspective observational studySubjectsA spherical isotropic diffusion phantom, and a single human control volunteerField Strength/Sequence3T (two scanners). Stejskal-Tanner spin echo sequence with b-values of 1000, 2000 s/mm2 with 12, 32, and 384 diffusion gradient directions per shell.AssessmentWe compare the proposed correction with the prior approach using manufacturer specifications against typical diffusion pre-processing pipelines (i.e., ignoring spatial gradient nonlinearities). In phantom data, we evaluate metrics against the ground truth. In human and phantom data, we evaluate reproducibility across scans, sessions, and hardware.Statistical TestsWilcoxon rank-sum test between uncorrected and corrected data.ResultsIn phantom data, our correction method reduces variation in mean diffusivity across sessions over uncorrected data (p<0.05). In human data, we show that this method can also reduce variation in mean diffusivity across scanners (p<0.05).ConclusionOur method is relatively simple, fast, and can be applied retroactively. We advocate incorporating voxel-specific b-value and b-vector maps should be incorporated in DW-MRI harmonization preprocessing pipelines to improve quantitative accuracy of measured diffusion parameters.

Chemical Shift Selective Magnetic Resonance Imaging of the Optic Nerve in Patients with Acute Optic Neuritis

1988 ◽  
Vol 29 (6) ◽  
pp. 629-632 ◽  
Author(s):  
H. B. W. Larsson ◽  
C. Thomsen ◽  
J. Frederiksen ◽  
O. Henriksen ◽  
J. Olesen
Keyword(s):  
Magnetic Resonance Imaging ◽  
Optic Nerve ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Optic Neuritis ◽  
Spin Echo ◽  
Resonance Imaging ◽  
Double Spin ◽  
Acute Optic Neuritis ◽  
Spin Echo Sequence

Optic neuritis is often the first manifestion of multiple sclerosis (MS). Sixteen patients with acute optic neuritis and one patient with benign intracranial hypertension (BIH) were investigated by magnetic resonance imaging, using a chemical shift selective double spin echo sequence. In 3 of the 16 patients, abnormalities were seen. In one patient with bilateral symptoms, signal hyperintensity and swelling of the right side of the chiasm were found. In another patient the optic nerve was found diffusely enlarged with only a marginally increased signal in the second echo. In the third patient an area of signal hyperintensity and swelling was seen in the left optic nerve. In the patient with BIH the subarachnoid space which surrounds the optic nerves was enlarged. Even using this refined pulse sequence, avoiding the major artefact in imaging the optic nerve, the chemical shift artefact, lesions were only shown in 3/16 (19%) of the patients with optic neuritis. Nevertheless, the presented chemical shift selective double spin echo sequence may be of great value for detection of retrobulbar lesions.

scholarly journals Improvement of sensitivity and specificity for laminar BOLD fMRI with double spin-echo EPI in humans at 7 T

NeuroImage ◽  
2021 ◽  
pp. 118435
Author(s):  
SoHyun Han ◽  
Seulgi Eun ◽  
HyungJoon Cho ◽  
Kâmil Uludaǧ ◽  
Seong-Gi Kim
Keyword(s):  
Sensitivity And Specificity ◽  
Spin Echo ◽  
Bold Fmri ◽  
Double Spin
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