Quality assurance of multi­echo data used for myelin water mapping through residual bootstrapping

Myelin water mapping aims to quantify the myelin content within the brain using the short T2 time of water trapped between myelin sheets. Multi-exponential fitting of the T2 decay can be used to derive the myelin water fraction (MWF), a quantitative measure that can be applied to investigate myelin change in neurodevelopment and disease. Investigations into the sensitivity of MWF to data quality are limited. Here we demonstrate the influence of residuals on the MWF. These residuals are the fitting error of the non-negative least square algorithm, which fits an exponential curve to the intensity decay curve of multi-echo data. The aim is to obtain a visual representation of the influence of noise and other external influences on the myelin mapping procedure.status: publishe

Multicomponent T2 relaxation complements diffusion MRI in the characterization of T2 hyperintensities related with Neurofibromatosis type 1

In Neurofibromatosis type 1 (NF1), socalled “unidentified bright objects“(UBOs), have been shown to correlate with learning difficulties[1]. Although the exact nature of UBOs is not known, one hypothesis is vacuolization of the myelin sheath and astroglial cell proliferation. The present in vivo study assesses the microstructure of UBOs using diffusion kurtosis imaging (DKI) and myelin water imaging (MWI).status: publishe

Improved Microstructural Characterisation of T2-hyperintense lesions by combining multi-shell diffusion MRI and myelin water imaging

status: publishe

Investigating the long-term effects of systemic chemotherapy on brain white matter using multi-shell diffusion MRI and myelin water imaging

status: publishe

Investigating the long-term effects of systemic chemotherapy on brain white matter using multi-shell diffusion MRI and myelin water imaging

status: publishe

Magnetic resonance parametric mapping of the spleen for non-invasive assessment of portal hypertension

Objectives!#!In patients with advanced liver disease, portal hypertension is an important risk factor, leading to complications such as esophageal variceal bleeding, ascites, and hepatic encephalopathy. This study aimed to determine the diagnostic value of T1 and T2 mapping and extracellular volume fraction (ECV) for the non-invasive assessment of portal hypertension.!##!Methods!#!In this prospective study, 50 participants (33 patients with indication for trans-jugular intrahepatic portosystemic shunt (TIPS) and 17 healthy volunteers) underwent MRI. The derivation and validation cohorts included 40 and 10 participants, respectively. T1 and T2 relaxation times and ECV of the liver and the spleen were assessed using quantitative mapping techniques. Direct hepatic venous pressure gradient (HVPG) and portal pressure measurements were performed during TIPS procedure. ROC analysis was performed to compare diagnostic performance.!##!Results!#!Splenic ECV correlated with portal pressure (r = 0.72; p < 0.001) and direct HVPG (r = 0.50; p = 0.003). No significant correlations were found between native splenic T1 and T2 relaxation times with portal pressure measurements (p > 0.05, respectively). In the derivation cohort, splenic ECV revealed a perfect diagnostic performance with an AUC of 1.000 for the identification of clinically significant portal hypertension (direct HVPG ≥ 10 mmHg) and outperformed other parameters: hepatic T2 (AUC, 0.731), splenic T2 (AUC, 0.736), and splenic native T1 (AUC, 0.806) (p < 0.05, respectively). The diagnostic performance of mapping parameters was comparable in the validation cohort.!##!Conclusion!#!Splenic ECV was associated with portal pressure measurements in patients with advanced liver disease. Future studies should explore the diagnostic value of parametric mapping accross a broader range of pressure values.!##!Key points!#!• Non-invasive assessment and monitoring of portal hypertension is an area of unmet interest. • Splenic extracellular volume fraction is strongly associated with portal pressure in patients with end-stage liver disease. • Quantitative splenic and hepatic MRI-derived parameters have a potential to become a new non-invasive diagnostic parameter to assess and monitor portal pressure

Investigating the long-term effects of systemic chemotherapy on brain white matter using multi-shell diffusion MRI and myelin water imaging

status: publishe