scholarly journals MRI-based thermal dosimetry and diffusion-weighted imaging of MRI-guided focused ultrasound thermal ablation of uterine fibroids

2009 ◽  
Vol 29 (2) ◽  
pp. 404-411 ◽  
Author(s):  
Magdalini C. Pilatou ◽  
Elizabeth A. Stewart ◽  
Stephan E. Maier ◽  
Fiona M. Fennessy ◽  
Kullervo Hynynen ◽  
...  
Keyword(s):  
Thermal Ablation ◽  
Diffusion Weighted Imaging ◽  
Focused Ultrasound ◽  
Uterine Fibroids ◽  
Diffusion Weighted ◽  
Mri Guided ◽  
And Diffusion

scholarly journals Peripheral Nerve Focused Ultrasound Lesioning—Visualization and Assessment Using Diffusion Weighted Imaging

2021 ◽  
Vol 12 ◽  
Author(s):  
Matthew R. Walker ◽  
Jidan Zhong ◽  
Adam C. Waspe ◽  
Karolina Piorkowska ◽  
Lananh N. Nguyen ◽  
...  
Keyword(s):  
Nervous System ◽  
Peripheral Nerve ◽  
Diffusion Weighted Imaging ◽  
Quantitative Assessment ◽  
Focused Ultrasound ◽  
Non Invasive ◽  
Diffusion Weighted ◽  
Sciatic Nerves ◽  
And Diffusion

Objectives: Magnetic resonance-guided focused ultrasound (MRgFUS) is a non-invasive targeted tissue ablation technique that can be applied to the nervous system. Diffusion weighted imaging (DWI) can visualize and evaluate nervous system microstructure. Tractography algorithms can reconstruct fiber bundles which can be used for treatment navigation and diffusion tensor imaging (DTI) metrics permit the quantitative assessment of nerve microstructure in vivo. There is a need for imaging tools to aid in the visualization and quantitative assessment of treatment-related nerve changes in MRgFUS. We present a method of peripheral nerve tract reconstruction and use DTI metrics to evaluate the MRgFUS treatment effect.Materials and Methods: MRgFUS was applied bilaterally to the sciatic nerves in 6 piglets (12 nerves total). T1-weighted and diffusion images were acquired before and after treatment. Tensor-based and constrained spherical deconvolution (CSD) tractography algorithms were used to reconstruct the nerves. DTI metrics of fractional anisotropy (FA), and mean (MD), axial (AD), and radial diffusivities (RD) were measured to assess acute (<1–2 h) treatment effects. Temperature was measured in vivo via MR thermometry. Histological data was collected for lesion assessment.Results: The sciatic nerves were successfully reconstructed in all subjects. Tract disruption was observed after treatment using both CSD and tensor models. DTI metrics in the targeted nerve segments showed significantly decreased FA and increased MD, AD, and RD. Transducer output power was positively correlated with lesion volume and temperature and negatively correlated with MD, AD, and RD. No correlations were observed between FA and other measured parameters.Conclusions: DWI and tractography are effective tools for visualizing peripheral nerve segments for targeting in non-invasive surgical methods and for assessing the microstructural changes that occur following MRgFUS treatment.

The Added Value of Inflow-Based Vascular-Space-Occupancy and Diffusion-Weighted Imaging in Preoperative Grading of Gliomas

2021 ◽  
pp. 1-8
Author(s):  
Haimei Cao ◽  
Xiang Xiao ◽  
Jun Hua ◽  
Guanglong Huang ◽  
Wenle He ◽  
...  
Keyword(s):  
Diagnostic Accuracy ◽  
Roc Curve ◽  
Diffusion Weighted Imaging ◽  
Low Grade ◽  
High Grade ◽  
Mr Images ◽  
Vascular Space ◽  
Diffusion Weighted ◽  
High Grade Gliomas ◽  
And Diffusion

Objectives: The present study aimed to study whether combined inflow-based vascular-space-occupancy (iVASO) MR imaging (MRI) and diffusion-weighted imaging (DWI) improve the diagnostic accuracy in the preoperative grading of gliomas. Methods: Fifty-one patients with histopathologically confirmed diffuse gliomas underwent preoperative structural MRI, iVASO, and DWI. We performed 2 qualitative consensus reviews: (1) structural MR images alone and (2) structural MR images with iVASO and DWI. Relative arteriolar cerebral blood volume (rCBVa) and minimum apparent diffusion coefficient (mADC) were compared between low-grade and high-grade gliomas. Receiver operating characteristic (ROC) curve analysis was performed to compare the tumor grading efficiency of rCBVa, mADC, and the combination of the two parameters. Results: Two observers diagnosed accurate tumor grade in 40 of 51 (78.4%) patients in the first review and in 46 of 51 (90.2%) in the second review. Both rCBVa and mADC showed significant differences between low-grade and high-grade gliomas. ROC analysis gave a threshold value of 1.52 for rCBVa and 0.85 × 10−3 mm2/s for mADC to provide a sensitivity and specificity of 88.0 and 81.2% and 100.0 and 68.7%, respectively. The area under the ROC curve (AUC) was 0.87 and 0.85 for rCBVa and mADC, respectively. The combination of rCBVa and mADC values increased the AUC to 0.92. Conclusion: The combined application of iVASO and DWI may improve the diagnostic accuracy of glioma grading.

scholarly journals The role of magnetic resonance cholangiopancreatography and diffusion-weighted imaging for the differential diagnosis of obstructive biliary disorders

2017 ◽  
Vol 21 (1) ◽  
Author(s):  
Zeynep Cetiner-Alpay ◽  
Fatma Kulali ◽  
Aslihan Semiz-Oysu ◽  
Yasar Bukte ◽  
Kamil Ozdil
Keyword(s):  
Magnetic Resonance ◽  
Sensitivity And Specificity ◽  
Gold Standard ◽  
Diffusion Weighted Imaging ◽  
Magnetic Resonance Cholangiopancreatography ◽  
Malignant Tumours ◽  
Diagnostic Efficacy ◽  
Diffusion Weighted ◽  
Sensitivity Specificity ◽  
And Diffusion

Background: Although endoscopic retrograde cholangiopancreatography (ERCP) is accepted as the gold standard, there is a place for magnetic resonance cholangiopancreatography (MRCP) and diffusion-weighted imaging (DWI) in the diagnosis of obstructive biliary disorders.Aim: To compare the findings of MRCP with ERCP in patients with obstructive biliary disorders and to investigate the diagnostic efficacy of MRCP combined with DWI.Study design: Retrospective, analytic, cross-sectional study.Methods: The MRCP images of 126 patients who underwent both MRCP and ERCP owing to biliary obstruction were reviewed. Nine patients were excluded because of incomplete diagnostic workup or a long period (>3 months) between MRCP and ERCP. Ninety-two patients underwent DWI, which was also evaluated. The sensitivity, specificity and accuracy of MRCP and DWI were analysed.Results: The sensitivity, specificity and accuracy of MRCP according to ERCP results as the gold standard was 97%, 71% and 93% for assessment of biliary dilatation; 100%, 94.7% and 97.5% for the diagnosis of choledocholithiasis; 93.7%, 100% and 99% for the identification of benign strictures; 100%, 100% and 100% for the diagnosis of malignant tumours; and 100%, 100% and 100% for the detection of complicated hydatid cysts; respectively. The sensitivity and specificity of DWI for the diagnosis of malignant tumour was 100%. In the detection of choledocholithiasis, the sensitivity and specificity of DWI was 70.8% and 100%.Conclusions: MRCP is an alternative, non-invasive, diagnostic modality, comparable with ERCP for the evaluation of pancreaticobiliary diseases. DWI can be helpful for diagnosis of choledocholithiasis and tumours.

scholarly journals Palatal lesions: discriminative value of conventional MRI and diffusion weighted imaging

2016 ◽  
Vol 89 (1059) ◽  
pp. 20150911 ◽  
Author(s):  
Ying Yuan ◽  
Weiqing Tang ◽  
Mengda Jiang ◽  
Xiaofeng Tao
Keyword(s):  
Diffusion Weighted Imaging ◽  
Conventional Mri ◽  
Diffusion Weighted ◽  
Discriminative Value ◽  
And Diffusion
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