Search

Objectives: Doppler ultrasound (DUS) is the main imaging modality to evaluate vascular complications of pediatric liver transplants (LT). The current study aimed to determine reference values and their change over time., Methods: A consecutive cohort of pediatric patients undergoing an LT were retrospectively included between 2015 and 2020. Timepoints for standardized DUS were intra-operative and postoperative (day 0), days 1-7, months 1 and 3, and years 1 and 2. DUS measurements of the hepatic artery (HA), portal vein (PV), and hepatic vein(s) (HV) were included if there were no complications during 2 years follow-up. Measurements consisted of: peak systolic velocity (PSV) and resistive index (RI) for the HA, PSV for the PV, and venous pulsatility index (VPI) for the HV. Generalized estimating equations were used to analyze change over time., Results: One hundred twelve pediatric patients with 123 LTs were included (median age 3.3 years, interquartile range 0.7-10.1). Ninety-five HAs, 100 PVs, and 115 HVs without complications were included. Reference values for HA PSV and RI, PV PSV, and HV VPI were obtained for all timepoints (4043 included data points in total) and presented using 5 th -95 th percentiles and threshold values. All reference values changed significantly over time (p = 0.032 to p < 0.001)., Conclusions: DUS reference values of hepatic vessels in children after LT are presented, reference values change over time with specific vessel-dependent patterns. Timepoint-specific reference values improve the interpretation of DUS values and may help to better weigh their clinical significance., Key Points: • Doppler ultrasound reference values of pediatric liver transplantations are not static but change over time. Applying the correct reference values for the specific timepoint may further improve the interpretation of the measurements. • The pattern of change over time of Doppler ultrasound measurements differs between the hepatic vessel and measurement; knowledge of these patterns may help radiologists to better understand normal postoperative hemodynamic changes., (© 2023. The Author(s).)

Objectives: Volume of necrosis in Wilms tumour is informative of chemotherapy response. Contrast-enhanced T 1 -weighted MRI (T 1 w) provides a measure of necrosis using gadolinium. This study aimed to develop a non-invasive method of identifying non-enhancing (necrotic) tissue in Wilms tumour., Methods: In this single centre, retrospective study, post-chemotherapy MRI data from 34 Wilms tumour patients were reviewed (March 2012-March 2017). Cases with multiple b value diffusion-weighted imaging (DWI) and T 1 w imaging pre- and post-gadolinium were included. Fractional T 1 enhancement maps were generated from the gadolinium T 1 w data. Multiple linear regression determined whether fitted parameters from a mono-exponential model (ADC) and bi-exponential model (IVIM - intravoxel incoherent motion) (D, D*, f) could predict fractional T 1 enhancement in Wilms tumours, using normalised pre-gadolinium T 1 w (T 1 w norm ) signal as an additional predictor. Measured and predicted fractional enhancement values were compared using the Bland-Altman plot. An optimum threshold for separating necrotic and viable tissue using fractional T 1 enhancement was established using ROC., Results: ADC and D (diffusion coefficient) provided the strongest predictors of fractional T 1 enhancement in tumour tissue (p < 0.001). Using the ADC-T 1 w norm model (adjusted R 2  = 0.4), little bias (mean difference = - 0.093, 95% confidence interval = [- 0.52, 0.34]) was shown between predicted and measured values of fractional enhancement and analysed via the Bland-Altman plot. The optimal threshold for differentiating viable and necrotic tissue was 33% fractional T 1 enhancement (based on measured values, AUC = 0.93; sensitivity = 85%; specificity = 90%)., Conclusions: Combining ADC and T 1 w imaging predicts enhancement in Wilms tumours and reliably identifies and measures necrotic tissue without gadolinium., Key Points: • Alternative method to identify necrotic tissue in Wilms tumour without using contrast agents but rather using diffusion and T 1 weighted MRI. • A method is presented to visualise and quantify necrotic tissue in Wilms tumour without contrast. • The proposed method has the potential to reduce costs and burden to Wilms tumour patients who undergo longitudinal follow-up imaging as contrast agents are not used.

Objectives: Dementia is foremost a clinical diagnosis. However, in diagnosing dementia, it is advocated to perform at least one neuroimaging study. This has two purposes: to rule out potential reversible dementia (PRD), and to help determine the dementia subtype. Our first goal was to establish if MRI combined with visual rating scales changes the clinical diagnosis. The second goal was to demonstrate if MRI contributes to a geriatrician's confidence in the diagnosis., Methods: The dementia subtype was determined prior to and after MRI. Scoring scales used were: global cortical atrophy (GCA), medial temporal atrophy (MTA), and white matter hyperintensity measured according to the Fazekas scale. The confidence level of the geriatrician was determined using a visual analogue scale., Results: One hundred and thirty-five patients were included. After MRI, the diagnosis changed in 23.7 % (CI 17.0 %-31.1 %) of patients. Change was due to vascular aetiology in 13.3 % of patients. PRD was found in 2.2 % of all patients. The confidence level in the diagnosis increased significantly after MRI (p = 0.001)., Conclusions: MRI, combined with visual rating scales, has a significant impact on dementia subtype diagnosis and on a geriatrician's confidence in the final diagnosis., Key Points: • MRI with visual rating scales changes the dementia subtype diagnosis significantly. • MRI is essential in demonstrating vascular disease as a cause of dementia. • All suspected dementia patients should undergo an MRI with visual rating scales. • MRI improves a geriatrician's confidence in the diagnosis of the dementia subtype. • MRI remains essential during the workup of dementia to exclude reversible causes.