Conditional Variational Autoencoder for Learned Image Reconstruction

Learned image reconstruction techniques using deep neural networks have recently gained popularity and have delivered promising empirical results. However, most approaches focus on one single recovery for each observation, and thus neglect information uncertainty. In this work, we develop a novel computational framework that approximates the posterior distribution of the unknown image at each query observation. The proposed framework is very flexible: it handles implicit noise models and priors, it incorporates the data formation process (i.e., the forward operator), and the learned reconstructive properties are transferable between different datasets. Once the network is trained using the conditional variational autoencoder loss, it provides a computationally efficient sampler for the approximate posterior distribution via feed-forward propagation, and the summarizing statistics of the generated samples are used for both point-estimation and uncertainty quantification. We illustrate the proposed framework with extensive numerical experiments on positron emission tomography (with both moderate and low-count levels) showing that the framework generates high-quality samples when compared with state-of-the-art methods

Uncertainty quantification in medical image synthesis

Machine learning approaches to medical image synthesis have shown outstanding performance, but often do not convey uncertainty information. In this chapter, we survey uncertainty quantification methods in medical image synthesis and advocate the use of uncertainty for improving clinicians’ trust in machine learning solutions. First, we describe basic concepts in uncertainty quantification and discuss its potential benefits in downstream applications. We then review computational strategies that facilitate inference, and identify the main technical and clinical challenges. We provide a first comprehensive review to inform how to quantify, communicate and use uncertainty in medical synthesis applications

Inspiratory muscle workload due to dynamic intrinsic PEEP in stable COPD patients: effects of two different settings of non-invasive pressure-support ventilation.

BACKGROUND: In severe stable hypercapnic COPD patients the amount of pressure time product (PTP) spent to counterbalance their dynamic intrinsic positive end expiratory pressure (PEEPi,dyn) is high: no data are available on the best setting of non invasive pressure support ventilation (NPSV) to reduce the inspiratory muscle workload due to PEEPi,dyn. METHODS: The objectives of this randomised controlled physiological study were: 1. To measure the inspiratory muscle workload due to PEEPi,dyn 2. To measure the effects on this parameter of two settings of NPSV in stable COPD patients with chronic hypercapnia admitted in a Pulmonary Division of two Rehabilitation Centers. Twenty-three stable COPD patients with chronic hypercapnia on domiciliary nocturnal NPSV for 30 +/- 20 months were submitted to an evaluation of breathing pattern, PEEPi,dyn, inspiratory muscle workload and its partitioning during both assisted and unassisted ventilation. Two settings of NPSV were randomly applied for 30 minutes each: i- "at patient's comfort" (C): Inspiratory pressure support (IPS) was the maximal tolerated pressure able to reduce awake PaCO2 with the addition of a pre-set level of external PEEP (PEEPe); ii- "physiological setting" (PH): the level of IPS able to achieve a > 40% and < 90% decrease in transdiaphragmatic pressure in comparison to spontaneous breathing (SB). A PEEPe level able to reduce PEEPi,dyn by at least 50% was added. RESULTS: During SB the tidal diaphragmatic pressure-time product (PTPdi/b) was 17.62 +/- 7.22 cmH2O*sec, the component due to PEEPi,dyn (PTPdiPEEPi,dyn) being 38 +/- 17% (range: 16-65%). Compared to SB,PTPdiPEEPi,dyn was reduced significantly with both settings, the reduction being greater with PH compared to C. CONCLUSIONS: In conclusion in severe COPD patients with chronic hypercapnia the inspiratory muscle workload due to PEEPidyn is high and is reduced by NPSV at a greater extent when ventilator setting is tailored to patient's mechanics

A pilot study of nurse-led, home monitoring for patients with chronic respiratory failure and with mechanical ventilation assistance.

We assessed the feasibility of telemedicine for home monitoring of 45 patients with chronic respiratory failure (CRF) discharged from hospital. The patients transmitted pulsed arterial saturation (pSat) data via a telephone modem to a receiving station where a nurse was available for a teleconsultation. A respiratory physician was also available. Scheduled and ad hoc appointments were conducted. Thirty-five patients were on home mechanical ventilation, 13 with invasive and 22 with non-invasive devices. The main diagnosis was chronic obstructive pulmonary disease (COPD). The follow-up period was 176 days (SD 69). In all, 376 calls for scheduled consultations were received and 83 ad hoc consultations were requested by the patients. The actions taken were: 55 therapy modifications, 19 hospitalizations in a respiratory department for decompensated CRF, three hospitalizations in an intensive care unit (ICU), 22 requests for further investigations, 25 contacts with the general practitioner (GP), 66 demands for respiratory consultations and 10 calls for the emergency department. The mean time recorded for the 459 calls was 16 min/patient/week. In 82% of calls, a pSat recording was received successfully. The nurse time required to train the users in the operation of the pSat instrument was high (mean time 30 min). However, the results showed that home monitoring was feasible, and useful for titration of oxygen, mechanical ventilation setting and stabilization of relapse

Hsa-miR-210-3p expression in breast cancer and its putative association with worse outcome in patients treated with Docetaxel

MicroRNA-210-3p is the most prominent hypoxia regulated microRNA, and it has been found significantly overexpressed in different human cancers. We performed the expression analysis of miR-210-3p in a retrospective cohort of breast cancer patients with a median follow-up of 76 months (n = 283). An association between higher levels of miR-210-3p and risk of disease progression (HR: 2.13, 95%CI: 1.33-3.39, P = 0.002) was found in the subgroup of patients treated with Epirubicin and Cyclophosphamide followed by Docetaxel. Moreover, a cut off value of 20.966 established by ROC curve analyses allowed to discriminate patients who developed distant metastases with an accuracy of 85% at 3- (AUC: 0.870, 95%CI: 0.690-1.000) and 83% at 5-years follow up (AUC: 0.832, 95%CI: 0.656-1.000). Whereas the accuracy in discriminating patients who died for the disease was of 79.6% at both 5- (AUC: 0.804, 95%CI: 0.517-1.000) and 10-years (AUC: 0.804. 95%CI: 0.517-1.000) follow-up. In silico analysis of miR-210-3p and Docetaxel targets provided evidence for a putative molecular cross-talk involving microtubule regulation, drug efflux metabolism and oxidative stress response. Overall, our data point to the miR-210-3p involvement in the response to therapeutic regimens including Docetaxel in sequential therapy with anthracyclines, suggesting it may represent a predictive biomarker in breast cancer patients

Macular impairment in fabry disease: A morpho-functional assessment by swept-source OCT angiography and focal electroretinography

PURPOSE. Fabry disease (FD) is a multiorgan X-linked condition characterized by a deficiency of the lysosomal enzyme alpha-galactosidase A, resulting in a progressive intralysosomal deposit of globotriaosylceramide. The aim of this study was to evaluate the macular ultrastructure of the vascular network using optical coherence tomography angiography (OCTA) and to evaluate macular function using focal electroretinography (fERG) in Fabry patients (FPs). METHODS. A total of 20 FPs (38 eyes, mean age 57 \ub1 2.12 SD, range of 27\u201380 years) and 17 healthy controls (27 eyes, mean age 45 years \ub1 20.50 SD, range of 24\u201365 years) were enrolled in the study. Color fundus photography, swept-source optical coherence tomography (SS-OCT), OCTA and fERG were performed in all subjects. The OCTA foveal avascular zone (FAZ), vasculature structure, superficial and deep retinal plexus densities (images of 4.5 X 4.5 mm) and fERG amplitudes were measured. Group differences were statistically assessed by Student\u2019s t-test and ANOVA. RESULTS. In the FP group, the FAZ areas of the superficial and deep plexuses were enlarged (P = 0.036, t = 2.138; P < 0.001, t = 3.889, respectively), the vessel density was increased in the superficial plexus, and the fERG amplitude was reduced (P < 0.001, t = 10.647) compared with those in healthy controls. No significant correlations were found between the structural and functional data. CONCLUSIONS. OCTA vascular abnormalities and reduced fERG amplitudes indicate subclinical signs of microangiopathy with early retinal dysfunction in FPs. This study highlights the relevance of OCTA imaging analysis in the identification of abnormal macular vasculature as an ocular hallmark of FD