Browsing by Subject "Non-invasive"

Now showing 1 - 3 of 3
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    A composite score using quantitative magnetic resonance cholangiopancreatography predicts clinical outcomes in primary sclerosing cholangitis
    (Elsevier, 2023-06-29) Vuppalanchi, Raj; Are, Vijay; Telford, Alison; Young, Liam; Mouchti, Sofia; Ferreira, Carlos; Kettler, Carla; Gromski, Mark; Akisik, Fatih; Chalasani, Naga; Radiology and Imaging Sciences, School of Medicine
    Background & aims: Magnetic resonance cholangiopancreatography (MRCP) for evaluation of biliary disease currently relies on subjective assessment with limited prognostic value because of the lack of quantitative metrics. Artificial intelligence-enabled quantitative MRCP (MRCP+) is a novel technique that segments biliary anatomy and provides quantitative biliary tree metrics. This study investigated the utility of MRCP+ as a prognostic tool for the prediction of clinical outcomes in primary sclerosing cholangitis (PSC). Methods: MRCP images of patients with PSC were post-processed using MRCP+ software. The duration between the MRCP and clinical event (liver transplantation or death) was calculated. Survival analysis and stepwise Cox regression were performed to investigate the optimal combination of MRCP+ metrics for the prediction of clinical outcomes. The resulting risk score was validated in a separate validation cohort and compared with an existing prognostic score (Mayo risk score). Results: In this retrospective study, 102 patients were included in a training cohort and a separate 50 patients formed a validation cohort. Between the two cohorts, 34 patients developed clinical outcomes over a median duration of 3 years (23 liver transplantations and 11 deaths). The proportion of bile ducts with diameter 3-5 mm, total bilirubin, and aspartate aminotransferase were independently associated with transplant-free survival. Combined as a risk score, the overall discriminative performance of the MRCP+ risk score (M+BA) was excellent; area under the receiver operator curve 0.86 (95% CI: 0.77, 0.95) at predicting clinical outcomes in the validation cohort with a hazard ratio 5.8 (95% CI: 1.5, 22.1). This was superior to the Mayo risk score. Conclusions: A composite score combining MRCP+ with total bilirubin and aspartate aminotransferase (M+BA) identified PSC patients at high risk of liver transplantation or death. Prospective studies are warranted to evaluate the clinical utility of this novel prognostic tool. Impact and implications: Primary sclerosis cholangitis (PSC) is a disease of the biliary tree where inflammation and fibrosis cause areas of narrowing (strictures) and expansion (dilatations) within the biliary ducts leading to liver failure and/or cancer (cholangiocarcinoma). In this study, we demonstrate that quantitative assessment of the biliary tree can better identify patients with PSC who are at high risk of either death or liver transplantation than a current blood-based risk score (Mayo risk score).
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    Non invasive approach for the detection of human arterial blockages via photo acoustic modelling
    (2017-12) Kakani, Monika; Rizkalla, Maher
    This research focuses on the detection of arterial blockage due to LDL (low density lipoprotein). Arterial blockages are related to two kinds of fats LDL and the HDL. HDL being the good fat, the patient does not have to undergo the biopsy, while in case of LDL, biopsy should be performed. Issues associated with invasive approaches raise safety concerns for patients such as infection, longer operation durations, longer recovery time etc. This research focuses on a noninvasive imaging technique to detect the kind of block age. Photo acoustic approach was investigated in order to simulate human tissues leading to medical diagnosis and treatment. Photo acoustic imaging involves production of an image on absorption of laser pulses. The laser pulses are further scattered and absorbed producing heat. The goals of the study were to categorize the type of the tissue materials based on the output temperature distribution via IR sensors and reflected acoustic waves via acoustic pressure sensors. The reflected acoustic wave and IR thermal distribution may be applied towards arterial blockages to differentiate the different types of tissue layers. The simulation results should have implications towards the future implementation of the practical devices and system. Parameters including energy levels, tissue thicknesses, frequencies, penetration depth, and the densities of the LDL/HDL fat materials were considered. Various energy pulses; 1j, 3j, and 5j were considered as input sources to the tissue materials (single or multi layers). The simulated layers considered in the study were the skin, bone, blood, and fat cells. The temperature and acoustic pressure response over the various layers were analyzed for the detection of blockages. The ndings of the temperature and acoustic pressure ranges can be detected by MEMS/NEMS (Micro electro mechanical systems/ nano electro mechanical systems) sensors, such as IR and Piezoelectric devices. Bioheat and acoustic wave equations were solved simultaneously using COMSOL software for multiple layers. The proper boundary conditions were provided in the solutions of these equations. The scattering and transmission acoustic wave, and the temperature distributions, may be used as guide to the integrated sensor system design for future consideration. The simulation was performed in four stages: (1) Single layer and multiple layers at a given frequency and energy level (2) Multiple layers at a given frequency for different energy levels (3) Multiple layers at a given energy level for different frequency and (4) Multiple layers at a given frequency and energy levels with different size tissues. The simulation results showed that a range of acoustic pressure between 240 and 260 need to be detected, with a di erential temperature distribution in kelvin range. Power pulses of 10MPa showed a temperature change of 175, which is believed to be within the exible substrate sensing devices that may be used for the practical model of this research. The thesis covers a proposed system for the practical model following the simulation results received in this study.
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    Relationship Between Three Commonly Used Non-invasive Fibrosis Biomarkers and Improvement in Fibrosis Stage in Patients With NASH
    (Wiley, 2019-02-21) Chalasani, Naga; Abdelmalek, Manal F.; Loomba, Rohit; Kowdley, Kris V.; McCullough, Arthur J.; Dasarathy, Srinivasan; Neuschwander-Tetri, Brent A.; Terrault, Norah; Ferguson, Beatrice; Shringarpure, Reshma; Shapiro, David; Sanyal, Arun J.; Medicine, School of Medicine
    Non-invasive biomarkers are needed for monitoring changes in liver histology in patients with non-alcoholic steatohepatitis (NASH). Obeticholic acid (OCA) was shown to improve fibrosis in patients with NASH in the FLINT trial; a post hoc analysis of these data was performed to determine the relationship between 3 non-invasive fibrosis markers and liver fibrosis improvement. Methods In the Phase 2b FLINT trial, patients were randomised (1:1) to receive 25 mg OCA or placebo once daily for 72 weeks. Aspartate aminotransferase:platelet ratio index (APRI), fibrosis-4 (FIB-4) index, and non-alcoholic fatty liver disease fibrosis score (NFS) were evaluated in serum at baseline and weeks 24, 48, 72, and 96. Liver biopsies were obtained at baseline and 72 weeks. Results In patients with fibrosis improvement at week 24, scores were reduced by a median of 34% for APRI, 10% for FIB-4, and 4% for NFS. Reductions in APRI (p=0.015) and FIB-4 (p=0.036), but not NFS (p=0.201) at week 24, significantly correlated with ≥1-stage improvement in histologic fibrosis at week 72. Reductions in APRI at week 72 were significantly correlated with fibrosis improvement at week 72 (p=0.012). Patients receiving OCA had significant reductions in all markers compared with patients receiving placebo at week 72 [APRI and FIB-4 (p<0.0001); NFS (p<0.05)]. Conclusions Readily available non-invasive markers may predict improvement in liver fibrosis in patients with NASH. Upon external confirmation and further refinement in larger populations, these markers may serve as surrogate end points in NASH clinical trials.