Emerging deep learning techniques using magnetic resonance imaging data applied in multiple sclerosis and clinical isolated syndrome patients (Review).

Computer-aided diagnosis systems aim to assist clinicians in the early identification of abnormal signs in order to optimize the interpretation of medical images and increase diagnostic precision. Multiple sclerosis (MS) and clinically isolated syndrome (CIS) are chronic inflammatory, demyelinating diseases affecting the central nervous system. Recent advances in deep learning (DL) techniques have led to novel computational paradigms in MS and CIS imaging designed for automatic segmentation and detection of areas of interest and automatic classification of anatomic structures, as well as optimization of neuroimaging protocols. To this end, there are several publications presenting artificial intelligence-based predictive models aiming to increase diagnostic accuracy and to facilitate optimal clinical management in patients diagnosed with MS and/or CIS. The current study presents a thorough review covering DL techniques that have been applied in MS and CIS during recent years, shedding light on their current advances and limitations.

Same day discharge after chronic total occlusion interventions: A single center experience.

OBJECTIVES: To assess the feasibility and safety of same day discharge (SDD) after chronic total occlusion (CTO) percutaneous coronary intervention (PCI). BACKGROUND: CTO PCI has been associated with higher complication rates and procedural and hospitalization costs. Shortening post-PCI hospitalization length not only increases the patients' comfort but at the same time it consists an important part of cost reduction policies. METHODS: We retrospectively compared the 30-day outcomes of patients who underwent CTO PCI at the Red Cross Hospital, Greece between January 2016 and June 2019 and underwent SDD versus non-SDD. Major adverse cardiovascular events (MACE) were defined as the composite of death, myocardial infarction, urgent repeat target vessel revascularization, tamponade, and stroke. RESULTS: A total of 173 patients (mean age 63.7 ± 8.9 years) were included, of whom 51 (30%) underwent SDD. SDD patients were less likely to have diabetes mellitus (51 vs. 31%, p = .015), arterial hypertension (89 vs. 67%, p < .001), and acute coronary syndrome presentation (39.7 vs. 21.6%, p = .022), compared with non-SDD patients. Forearm access was used in all SDD patients and in 83% of the non-SDD patients. The 30-day incidence of MACE was 0% in the SDD group and 1.6% in the non-SDD group. Multivariable analysis showed that diabetes mellitus and longer procedural time were associated with lower probability of SDD (OR: 0.34, 95% CI: 0.15, 0.73 and OR: 0.29, 95% CI: 0.12, 0.71, respectively). CONCLUSIONS: SDD appears to be feasible and safe in selected patients undergoing an uncomplicated CTO PCI through forearm approach.

Extended perfusion protocol for MS lesion quantification.

This study aims to examine a time-extended dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) protocol and report a comparative study with three different pharmacokinetic (PK) models, for accurate determination of subtle blood-brain barrier (BBB) disruption in patients with multiple sclerosis (MS). This time-extended DCE-MRI perfusion protocol, called Snaps, was applied on 24 active demyelinating lesions of 12 MS patients. Statistical analysis was performed for both protocols through three different PK models. The Snaps protocol achieved triple the window time of perfusion observation by extending the magnetic resonance acquisition time by less than 2 min on average for all patients. In addition, the statistical analysis in terms of adj-R 2 goodness of fit demonstrated that the Snaps protocol outperformed the conventional DCE-MRI protocol by detecting 49% more pixels on average. The exclusive pixels identified from the Snaps protocol lie in the low k trans range, potentially reflecting areas with subtle BBB disruption. Finally, the extended Tofts model was found to have the highest fitting accuracy for both analyzed protocols. The previously proposed time-extended DCE protocol, called Snaps, provides additional temporal perfusion information at the expense of a minimal extension of the conventional DCE acquisition time.

Distal Radial Access: A Review Article.

Transradial approach (TRA) for coronary angiography and interventions has been increasingly used over the last decades and has become the default strategy in the majority of catheterization laboratories worldwide. Recently, a novel transradial access site, the distal radial access (DRA), has been proposed as an alternative to traditional TRA. Several case reports and case series have been published on this new approach over the last year showing overall good success rates. Aim of this review is to present the possible benefits and drawbacks of DRA and offer guidance on its successful use.

Right arm distal transradial (snuffbox) access for coronary catheterization: Initial experience.

BACKGROUND: Distal transradial access (dTRA) by the snuffbox approach for coronary catheterization has emerged as an alternative to the classic forearm TRA with certain advantages and limitations.The aim of this study was to evaluate the effectiveness and safety of the dTRA exclusively from the right arm. METHODS: Forty-nine consecutive patients (31 males and 18 females, mean age 64 ± 12 years), who were candidates for coronary catheterization in two cath laboratory centers, regardless of the indication, were recruited. Right dTRA was exclusively used. Radial artery patency both at the forearm and at the snuffbox region was evaluated 24 h after successful hemostasis by triplex ultrasonography. All complications were recorded until 24 h after the procedure. RESULTS: The indication for catheterization was an acute coronary syndrome in 24.5%, stable coronary artery disease in 22.4%, and other reasons in 53.1%. The overall failure attempt incidence was 10.2% and the mean puncture time 3.9 ± 4.1 min. Angiography only was performed in 81.8% and angiography followed by percutaneous coronary intervention in 18.2% of the patients. Manual hemostasis was applied in 63.6% of the patients, which had a significantly shorter duration than device hemostasis (11 ± 7 versus 198 ± 42 min, p < 0.001). No distal or forearm radial artery occlusion was observed on triplex ultrasonography 24 h after successful hemostasis. No major complications were recorded. CONCLUSIONS: This two-center study, utilizing exclusively the right dTRA, provides further data regarding the snuffbox approach in an all-comers population. Further worldwide reports will elucidate new aspects of the technique.

Single Sheath for Dual Injection Prior to CTO Intervention.

To our knowledge, this is the first reported case of a dual injection using a single sheath approach, in order to evaluate a CTO and plan a future intervention.

Parallel Stenting for Treatment of an In-stent Chronic Total Occlusion after Successful Dissection Reentry Technique.

Percutaneous coronary interventions (PCI) for chronic total occlusions (CTO) are the most challenging type of procedure in interventional cardiology and are traditionally associated with increased complexity and reduced procedural success rates. New techniques, such as retrograde approach and dissection reentry technique, offer alternatives in case of traditional antegrade wiring failure. In this paper, we present a successful implantation of a stent parallel to other existing stent in an in-stent CTO (IS-CTO) using dissection reentry technique. The technical details involved and the clues to successful outcome in an individual with in-stent CTO are discussed.

T2, T2* and spin coupling ratio as biomarkers for the study of lipomatous tumors.

BACKGROUND: Subcutaneous fat may have variable signal intensity on T2w images depending on the choice of imaging parameters. However, fatty components within tumors have a different degree of signal dependence on the acquisition scheme. This study examined the use of T2, T2* relaxometry and spin coupling related signal changes (Spin Coupling ratio, SCr) on two different imaging protocols as clinically relevant descriptors of benign and malignant lipomatous tumors. MATERIALS AND METHODS: 20 patients with benign lipomas or liposarcomas of variable histologic grade were examined at an 1.5 T scanner with Multi Echo Spin Echo (MESE) different echo spacing (ESP) in order to produce bright fat T2w images (ESP: 13.4 ms, 25 equidistant echoes) and dark fat images (ESP: 26.8 ms with 10 equidistant echoes). T2* relaxometry acquisition comprises 4 sets of in-opposed echoes (2.4-19.2 ms, ESP: 2.4 ms) Multi Echo Gradient Echo (MEGRE) sequence. All parametric maps were calculated on a pixel basis. RESULTS: Significant differences of SCr were found for five different types of lipomatous tumors (Pairwise t-test with Bonferroni correction): lipomas, well differentiated liposarcomas, myxoid liposarcomas, pleomorphic liposarcomas and poorly differentiated liposarcomas. SCr surpassed the classification performance of T2 and T2* relaxometry. DATA CONCLUSION: A novel biomarker based on spin coupling related signal loss, SCr, is indicative of lipomatous tumor histological grading. We concluded that T2, T2* and SCr can be used for the classification of fat containing tumors, which may be important for biopsy guidance in heterogeneous masses and treatment planning.

Investigating the Role of Model-Based and Model-Free Imaging Biomarkers as Early Predictors of Neoadjuvant Breast Cancer Therapy Outcome.

Imaging biomarkers (IBs) play a critical role in the clinical management of breast cancer (BRCA) patients throughout the cancer continuum for screening, diagnosis, and therapy assessment, especially in the neoadjuvant setting. However, certain model-based IBs suffer from significant variability due to the complex workflows involved in their computation, whereas model-free IBs have not been properly studied regarding clinical outcome. In this study, IBs from 35 BRCA patients who received neoadjuvant chemotherapy (NAC) were extracted from dynamic contrast-enhanced MR imaging (DCE-MRI) data with two different approaches, a model-free approach based on pattern recognition (PR), and a model-based one using pharmacokinetic compartmental modeling. Our analysis found that both model-free and model-based biomarkers can predict pathological complete response (pCR) after the first cycle of NAC. Overall, eight biomarkers predicted the treatment response after the first cycle of NAC, with statistical significance (p-value < 0.05), and three at the baseline. The best pCR predictors at first follow-up, achieving high AUC and sensitivity and specificity more than 50%, were the hypoxic component with threshold 2 (AUC 90.4%) from the PR method, and the median value of kep (AUC 73.4%) from the model-based approach. Moreover, the 80th percentile of ve achieved the highest pCR prediction at baseline with AUC 78.5%. The results suggest that the model-free DCE-MRI IBs could be a more robust alternative to complex, model-based ones such as kep and favor the hypothesis that the PR image-derived hypoxic image component captures actual tumor hypoxia information able to predict BRCA NAC outcome.

"Single Arm-Double Access" for CTO Intervention.

To our knowledge, this is the first reported case of a dual-access approach for CTO intervention using transradial and ipsilateral transulnar access. Although retrograde CTO intervention is a challenging procedure, a single arm-double access approach seems to be a feasible alternative that may be useful in patients with limited access-site availability.

Distal Versus Traditional Radial Approach for Coronary Angiography.

PURPOSE: The aim of this study was to evaluate the efficacy and safety of distal radial (DR) versus traditional radial (TR) approach during coronary angiography. METHODS: Two hundred patients scheduled to undergo transradial coronary angiography were randomized between the two approaches. Primary endpoint of the study was switching to another access site due to inability of successful target artery cannulation. Secondary endpoints were time to cannulation, total procedure duration, number of attempts, number of skin punctures and duration of manual hemostasis. Secondary safety endpoints were the rate of moderate or severe spasm, arm hematoma EASY class III or more and radial artery occlusion at discharge. Quality of life endpoint was the patient's preference of cannulation method at 30 days. RESULTS: The primary endpoint was met in 30 patients (30%) from the DR group and 2 patients (2%) from the TR group (p < 0.001). The time of cannulation was longer in the DR group compared to the TR group (269 ±â€¯251 s vs 140 ±â€¯161 s, p < 0.001), but this did not affect the total procedural duration (925 ±â€¯896 s vs 831 ±â€¯424 s, p = 0.494). The number of attempts and the number of skin punctures were more in the DR group compared to the TR group (6.8 ±â€¯6.2 vs 3.4 ±â€¯4.5, p < 0.001 and 2.4 ±â€¯1.7 vs 1.6 ±â€¯1.2, p < 0.001, respectively). However, DR treated patients had faster manual hemostasis time compared to TR treated patients (568 ±â€¯462 s vs 841 ±â€¯574 s, p = 0.002). There were no differences recorded in the safety endpoints of moderate or severe spasm, EASY grade III or more radial hematomas or the incidence of radial artery occlusion after the procedure. Patients' preference to the randomized puncture sites was the same (79% vs 85%, p = 0.358). CONCLUSION: Distal radial approach is associated with lower successful cannulation rates and shorter manual hemostasis time compared to the traditional radial approach.

Alternative access site choice after initial radial access site failure for coronary angiography and intervention.

BACKGROUND: Transradial access for coronary catheterization is more technically challenging compared to the traditional transfemoral approach and radial access failure is quite common. The aim of this study is to describe the additional steps after initial radial access site failure in a high specialized forearm approach center. METHODS: A retrospective evaluation of all coronary catheterizations performed in our Department between January 2016 and December 2016 was performed, with focus on arterial access. RESULTS: One thousand three hundred forty six procedures were evaluated. The initial access site used was right radial [1173 procedures (87.1%)], left radial [120 procedures (8.9%)], right ulnar [7 procedures (0.5%)], left ulnar [40 procedures (2.9%)] and femoral approach [6 procedures (0.4%)]. Radial artery cannulation failure was observed in 37 procedures (2.9% of 1293 procedures with initial radial approach). Failure of procedure completion after successful radial sheath insertion was observed in 46 procedures (3.6%). The alternative access site after initial radial approach failure was contralateral radial [43 procedures (51.8%)], ipsilateral ulnar [22 procedures (26.5%), contralateral ulnar [12 patients (14.5%)] and femoral approach [6 procedures (7.2%)]. CONCLUSION: Forearm arteries can be used as alternative access site after initial radial approach failure in order to reduce the use of femoral approach during cardiac catheterization.

Strategies to increase the use of forearm approach during coronary angiography and interventions.

The aim of this article is to focus on the utilization of forearm approach for cardiac catheterization in challenging groups of patients. Radial and ulnar approaches have gained significant popularity among the majority of interventional cardiologists. Multiple studies have demonstrated the feasibility, safety and efficacy of forearm route for cardiac catheterization and have highlighted the significant reduction in bleeding complications by avoiding the puncture of the groin. In this review we present the strategies need to be followed in order to apply the forearm approach in challenging group of patients.

Hand Hematoma After Cardiac Catheterization Via Distal Radial Artery.

This is the first reported case of severe hand hematoma after cardiac catheterization through the distal radial artery, with the hematoma extending distally to the sheath insertion site. The distribution of the hematoma in our case is completely different compared to the hematomas observed after traditional radial catheterization, which used to extend to the forearm. Therefore, the traditional EASY classification may not apply to hematomas after catheterization through the distal radial artery.

Assessment of DCE-MRI parameters for brain tumors through implementation of physiologically-based pharmacokinetic model approaches for Gd-DOTA.

Dynamic-contrast enhanced magnetic resonance imaging (DCE-MRI) is used for detailed characterization of pathology of lesions sites, such as brain tumors, by quantitative analysis of tracer's data through the use of pharmacokinetic (PK) models. A key component for PK models in DCE-MRI is the estimation of the concentration-time profile of the tracer in a nearby vessel, referred as Arterial Input Function (AIF). The aim of this work was to assess through full body physiologically-based pharmacokinetic (PBPK) model approaches the PK profile of gadoteric acid (Gd-DOTA) and explore potential application for parameter estimation in DCE-MRI based on PBPK-derived AIFs. The PBPK simulations were generated through Simcyp(®) platform and the predicted PK parameters for Gd-DOTA were compared with available clinical data regarding healthy volunteers and renal impairment patients. The assessment of DCE-MRI parameters was implemented by utilizing similar virtual profiles based on gender, age and weight to clinical profiles of patients diagnosed with glioblastoma multiforme. The PBPK-derived AIFs were then used to compute DCE-MRI parameters through the Extended Tofts Model and compared with the corresponding ones derived from image-based AIF computation. The comparison involved: (i) image measured AIF of patients vs AIF of in silico profile, and, (ii) population average AIF vs in silico mean AIFs. The results indicate that PBPK-derived AIFs allowed the estimation of comparable imaging biomarkers with those calculated from typical DCE-MRI image analysis. The incorporation of PBPK models and potential utilization of in silico profiles to real patient data, can provide new perspectives in DCE-MRI parameter estimation and data analysis.

Assessing Treatment Response Through Generalized Pharmacokinetic Modeling of DCE-MRI Data.

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) enables the quantification of contrast leakage from the vascular tissue by using pharmacokinetic (PK) models. Such quantitative analysis of DCE-MRI data provides physiological parameters that are able to provide information of tumor pathophysiology and therapeutic outcome. Several assumptive PK models have been proposed to characterize microcirculation in the tumoral tissue. In this paper, we present a comparative study between the well-known extended Tofts model (ETM) and the more recent gamma capillary transit time (GCTT) model, with the latter showing initial promising results in the literature. To enhance the GCTT imaging biomarkers, we introduce a novel method for segmenting the tumor area into subregions according to their vascular heterogeneity characteristics. A cohort of 11 patients diagnosed with glioblastoma multiforme with known therapeutic outcome was used to assess the predictive value of both models in terms of correctly classifying responders and nonresponders based on only one DCE-MRI examination. The results indicate that GCTT model's PK parameters perform better than those of ETM, while the segmentation of the tumor regions of interest based on vascular heterogeneity further enhances the discriminatory power of the GCTT model.

A Proposed Paradigm Shift in Initializing Cancer Predictive Models with DCE-MRI Based PK Parameters: A Feasibility Study.

Glioblastoma multiforme is the most aggressive type of glioma and the most common malignant primary intra-axial brain tumor. In an effort to predict the evolution of the disease and optimize therapeutical decisions, several models have been proposed for simulating the growth pattern of glioma. One of the latest models incorporates cell proliferation and invasion, angiogenic net rates, oxygen consumption, and vasculature. These factors, particularly oxygenation levels, are considered fundamental factors of tumor heterogeneity and compartmentalization. This paper focuses on the initialization of the cancer cell populations and vasculature based on imaging examinations of the patient and presents a feasibility study on vasculature prediction over time. To this end, pharmacokinetic parameters derived from dynamic contrast-enhanced magnetic resonance imaging using Toft's model are used in order to feed the model. K (trans) is used as a metric of the density of endothelial cells (vasculature); at the same time, it also helps to discriminate distinct image areas of interest, under a set of assumptions. Feasibility results of applying the model to a real clinical case are presented, including a study on the effect of certain parameters on the pattern of the simulated tumor.