scholarly journals Assessment of ischemic penumbra in patients with hyperacute stroke using amide proton transfer (APT) chemical exchange saturation transfer (CEST) MRI

2013 ◽  
Vol 27 (2) ◽  
pp. 163-174 ◽  
Author(s):  
Anna Tietze ◽  
Jakob Blicher ◽  
Irene Klaerke Mikkelsen ◽  
Leif Østergaard ◽  
Megan K. Strother ◽  
...  
Keyword(s):  
Proton Transfer ◽  
Chemical Exchange ◽  
Chemical Exchange Saturation Transfer ◽  
Amide Proton ◽  
Ischemic Penumbra ◽  
Saturation Transfer ◽  
Hyperacute Stroke ◽  
Amide Proton Transfer ◽  
Cest Mri

Amide proton transfer imaging for differentiation of tuberculomas from high-grade gliomas: Preliminary experience

2021 ◽  
pp. 197140092110027
Author(s):  
Karthik Kulanthaivelu ◽  
Shumyla Jabeen ◽  
Jitender Saini ◽  
Sanita Raju ◽  
Atchayaram Nalini ◽  
...  
Keyword(s):  
Proton Transfer ◽  
Chemical Exchange ◽  
Spin Echo ◽  
Chemical Exchange Saturation Transfer ◽  
Amide Proton ◽  
High Grade ◽  
Saturation Pulse ◽  
Amide Proton Transfer ◽  
High Grade Gliomas ◽  
Amide Protons

Purpose Tuberculomas can occasionally masquerade as high-grade gliomas (HGG). Evidence from magnetisation transfer (MT) imaging suggests that there is lower protein content in the tuberculoma microenvironment. Building on the principles of chemical exchange saturation transfer and MT, amide proton transfer (APT) imaging generates tissue contrast as a function of the mobile amide protons in tissue’s native peptides and intracellular proteins. This study aimed to further the understanding of tuberculomas using APT and to compare it with HGG. Method Twenty-two patients ( n = 8 tuberculoma; n = 14 HGG) were included in the study. APT was a 3D turbo spin-echo Dixon sequence with inbuilt B0 correction. A two-second, 2 μT saturation pulse alternating over transmit channels was applied at ±3.5 ppm around water resonance. The APT-weighted image (APTw) was computed as the MT ratio asymmetry (MTRasym) at 3.5 ppm. Mean MTRasym values in regions of interest (areas = 9 mm2; positioned in component with homogeneous enhancement/least apparent diffusion coefficient) were used for the analysis. Results MTRasym values of tuberculomas ( n = 14; 8 cases) ranged from 1.34% to 3.11% ( M = 2.32 ± 0.50). HGG ( n = 17;14 cases) showed MTRasym ranging from 2.40% to 5.70% ( M = 4.32 ± 0.84). The inter-group difference in MTRasym was statistically significant ( p < 0.001). APTw images in tuberculomas were notable for high MTRasym values in the perilesional oedematous-appearing parenchyma (compared to contralateral white matter; p < 0.001). Conclusion Tuberculomas demonstrate lower MTRasym ratios compared to HGG, reflective of a relative paucity of mobile amide protons in the ambient microenvironment. Elevated MTRasym values in perilesional parenchyma in tuberculomas are a unique observation that may be a clue to the inflammatory milieu.

scholarly journals Can Chemical Exchange Saturation Transfer (CEST MRI) be used as biomarker of disease progression in Prion Disease?

2021 ◽  
Author(s):  
Eleni Demetriou ◽  
Mohamed Tachrount ◽  
Matthew Ellis ◽  
Jacqueline Linehan ◽  
Sebastian Brandner ◽  
...  
Keyword(s):  
Disease Progression ◽  
Prion Protein ◽  
Prion Disease ◽  
Neurodegenerative Disorders ◽  
Chemical Exchange ◽  
Chemical Exchange Saturation Transfer ◽  
Amide Proton ◽  
Saturation Transfer ◽  
Protein Deposition ◽  
Cest Mri

Human prion diseases are fatal neurodegenerative disorders that may have prolonged asymptomatic incubation periods. However, the underlying mechanism by which prions cause brain damage remains unclear. In turn, characterization of early pathological aspects would be of benefit for the diagnosis and potential treatment of these progressive neurodegenerative disorders. We investigated chemical exchange saturation transfer (CEST) MRI based on its exquisite sensitivity to cytosol protein content as a surrogate for prion disease pathology. Three groups of prion-infected mice at different stages of the disease underwent conventional magnetic resonance imaging and CEST MRI at 9.4T. For each mouse, chemical exchange contrasts were measured by applying five RF powers at various frequency offsets using magnetization transfer asymmetries. Relayed Nuclear Overhauser effects (NOE*) and amide proton transfer (APT*) were also assessed. For comparison, CEST MRI measurements were also made in healthy control mice brains. Here we show that alterations in CEST signal were detected before structural modifications or any clinical signs of prion disease. The detected CEST signal displayed different patterns at different stages of the disease indicating its potential for use as a longitudinal marker of disease progression. Highly significant correlations were found between CEST metrics and histopathological findings. A decline in NOE signal was positively correlated with abnormal prion protein deposition (R2 = 0.91) in the thalami of prion infected mice. Moreover, the NOE signal was negatively correlated with astrogliosis (R2 = 0.71) in the thalamus. No significant correlations were detected between NOE signals and spongiosis. MTR asymmetry at 3.5 ppm was also correlated with astrogliosis (R2 = 0.59), and prion protein deposition (R2 = 0.63) in thalamus. No significant changes were detected in APT* between prion-infected and control mice at all stages of the disease. Finally, MTR asymmetry between 2.8 and 3.2 ppm was correlated with prion protein deposition (R2 = 0.47) in the thalamus of prion -infected mice. To conclude, CEST MRI has potential utility as a biomarker of neurodegenerative processes in prion disease

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