P104 FEASIBILITY AND ROLE OF ECHOCONTRAST EVALUATION IN PATIENTS WITH LVAD

Background

Advanced heart failure is a clinical syndrome characterized by persistent or progressive symptoms of heart failure despite optimal medical therapy. Left ventricular assist device (LVAD) brings survival benefits and improvement in quality of life, compared with conventional medical treatments. Development of Right ventricle failure in patients with LVAD has a direct effect on mortality and hospitalization.

Purpose

evaluation of clinical safety and feasibility of echocontrast in patients implanted with 3 different types of LVAD; improvement in the visualization of heart structures; intra and inter–operator agreement of RV assesement with and without contrast. Methods 43 patients were implanted with LVAD, 7 patients (16%) with Jarvik 2000, 31 (72%) with HeartMAte 3, 5 (12%) with (HeartWAre HVAD). Nine patients (21%) had contraindication or refused contrast. In 3 (7%) patients was technically challenging to obtain apical images at all levels. Two (5%) patients lost their follow–up. Our final population was of 29 (67%) patients (mean age 65±7 y; 100% Male). We assessed the reproducibility of these measurements between two different expert blind operators

Results

Total 329 (64%) of 516 RV wall segments were available for qualitative analysis without contrast vs 451 (87%) with contrast (p < 0.001) with a significant improvement of the evaluability of regional contractility (especially due to the better evaluation of medial and apical segments of lateral and anterior walls) and FAC (41% vs 90%, p < 0.001). Evaluation of TAPSE, TR and sPAP was similar with and without contrast (p=NS). All the RV parameters showed little inter–operator variability when measured with contrast. TAPSE, FAC, and RWMA showed an excellent reproducibility (ICC >0.86) while it was good for 2D–baseline derived parameters (ICC = 0.74) showing improvement of inter operator reproducibility in the evaluation of regional contractility in the contrast echocardiography modality.

Conclusion

EC is safe with all the types of LVAD examined. Accurate and reproducible visualization of RV is imperative for reliability of information, a routine use of EC could play a pivotal role in interpreting RV features. EC improves RV morphologic and functional judgment allowing greater accuracy and precision in the assessment of both global and regional RV functions. This finding may have important clinical improvement, especially in the future for analysis focused in RV prognostic role in LVAD patients.

Feasibility and role of echocontrast evaluation of patients with LVAD

Funding Acknowledgements

Type of funding sources: None.

Background

In patients with Advanced heart failure (AHF) long-term support with durable mechanical circulatory support (MCS) devices such as left ventricular assist device (LVAD) brings survival benefits and improvement in quality of life, compared with conventional medical treatments. Development of RVF in patients with LVAD has a direct effect on mortality and is associated with prolonged length of stay in intensive care unit and in-hospital stay and with poor quality of life. Purpose: the evaluation of clinical safety and feasibility of  echocontrast (EC) in patients implanted with 3 different types of LVAD (HeartWAre HVAD, Jarvik 2000, HeartMate 3); the assessment of the improvement in the visualization of heart structures; the intra and inter-operator agreement of RV measurements (FAC, TAPSE, sPAP, TR,  regional wall motion abnormalities) with and without contrast. Methods: Between 2014 and 2019, 43 patients were implanted with LVAD, in particular 7 (16%) patients were implanted with Jarvik 2000, 31 (72%) with HeartMAte 3, 5 (12%) pts with HeartWAre HVAD. Nine patients (21%) either had contraindication or refused contrast injection. In 3 (7%) patients, it was technically challenging to obtain apical images at all levels. Two (5%) patients lost their follow-up. Our final population was of 29 (67%) patients. We also assessed the reproducibility of these measurements between two different expert operators (blind analysis). Results:  We observed no allergic reaction to EC. Total 329 (64%) of 516 RV wall segments were available for qualitative analysis without contrast vs 451 (87%) with contrast (p < 0.001) with a significant improvement of the evaluability of regional contractility and FAC  (41% vs 90%, p < 0.001). Evaluation of TAPSE, TR and sPAP was similar with and without contrast (p = NS) All the RV parameters showed little inter-operator variability when measured with contrast. TAPSE, FAC, and RWMA showed an excellent reproducibility (ICC >0.86) while it was good for 2D-baseline derived parameters (ICC = 0.74) showing improvement of inter operator reproducibility in the evaluation of regional contractility in the contrast echocardiography modality. Conclusion: EC is safe with all the types of LVAD we examined. Accurate and reproducible visualization of RV is imperative for reliability of information, a routine use of EC could play a pivotal role in interpreting RV features.  EC improves RV morphologic and functional judgment; allowing greater accuracy and precision in the assessment of both global and regional RV functions. This finding may have important clinical improvement, especially in the future for analysis focused in RV prognostic role in LVAD patients

Analysis of tumour microstructure estimation from conventional diffusion MRI and application to skull-base chordoma. Annu Int Conf IEEE Eng Med Biol Soc 2021;2021:3761-3764. [PMID: 34892054 DOI: 10.1109/embc46164.2021.9630129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Skull-base chordoma (SBC) is a rare tumour whose molecular and radiological characteristics are still being investigated. In neuro-oncology microstructural imaging techniques, like diffusion-weighted MRI (DW-MRI), have been widely investigated, with the apparent diffusion coefficient (ADC) being one of the most used DW-MRI parameters due to its ease of acquisition and computation. ADC is a potential biomarker without a clear link to microstructure. The aim of this work was to derive microstructural information from conventional ADC, showing its potential for the characterisation of skull-base chordomas. Sixteen patients affected by SBC, who underwent conventional DW-MRI were retrospectively selected. From mono-exponential fits of DW-MRI, ADC maps were estimated using different sets of b-values. DW-MRI signals were simulated from synthetic substrates , which mimic the cellular packing of a tumour tissue with well-defined microstructural features. Starting from a published method, an error-driven procedure was evaluated to improve the estimates of microstructural parameters obtained through the simulated signals. A quantitative description of the tumour microstructure was then obtained from the DW-MRI images. This allowed successfully differentiating patients according to histologically-verified cell proliferation information.Clinical Relevance - The impact on cancer management derives from the expected improvement of radiation treatment quality tailored to a patient-specific non-invasive description of tumour microstructure.

Dosimetric effect of variable rectum and sigmoid colon filling during carbon ion radiotherapy to sacral chordoma

PURPOSE

Carbon ion radiotherapy (CIRT) is sensitive to anatomical density variations. We examined the dosimetric effect of variable intestinal filling condition during CIRT to ten sacral chordoma patients.

METHODS

For each patient, eight virtual computed tomography scans (vCTs) were generated by varying the density distribution within the rectum and the sigmoid in the planning computed tomography (pCT) with a density override approach mimicking a heterogeneous combination of gas and feces. Totally full and empty intestinal preparations were modelled. In addition, five different intestinal filling conditions were modelled by a mixed density pattern derived from two combined and weighted Gaussian distributions simulating gas and feces respectively. Finally, a patient-specific mixing proportion was estimated by evaluating the daily amount of gas detected in the cone beam computed tomography (CBCT). Dose distribution was recalculated on each vCT and dose volume histograms (DVHs) were examined.

RESULTS

No target coverage degradation was observed at different vCTs. Rectum and sigma dose degradation ranged respectively between: [-6.7; 21.6]GyE and [-0.7; 15.4]GyE for D_50%; [-377.4; 1197.9] and [-95.2; 1027.5] for AUC; [-1.2; 10.7]GyE and [-2.6; 21.5]GyE for D_1%.

CONCLUSIONS

Variation of intestinal density can greatly influence the penetration depth of charged particle and might compromise dose distribution. In particular cases, with large clinical target volume in very close proximity to rectum and sigmoid colon, it is appropriate to evaluate the amount of gas present in the daily CBCT images even if it is totally included in the reference planning structures.

Development and validation of a new set-up simulator dedicated to ocular proton therapy at CNAO

An Eye Tracking System (ETS) is used at CNAO for providing a stable and reproducible ocular proton therapy (OPT) set-up, featuring a fixation light (FL) and monitoring stereo-cameras embedded in a rigid case. The aim of this work is to propose an ETS set-up simulation algorithm, that automatically provides the FL positioning in space, according to patient-specific gaze direction and avoiding interferences with patient, beam and collimator. Two configurations are provided: one in the CT room for acquiring images required for treatment planning with the patient lying on a couch, and one related to the treatment room with the patient sitting in front of the beam. Algorithm validation was performed reproducing ETS simulation (CT) and treatment (room) set-up for 30 patients previously treated at CNAO. The positioning accuracy of the device was quantified through a set of 14 control points applied to the ETS case and localizable both in the CT volume and in room X-ray images. Differences between the position of ETS reference points estimated by the algorithm and those measured by imaging systems are reported. The corresponding gaze direction deviation is on average 0.2° polar and 0.3° azimuth for positioning in CT room and 0.1° polar and 0.4° azimuth in the treatment room. The simulation algorithm was embedded in a clinically usable software application, which we assessed as capable of ensuring ETS positioning with an average accuracy of 2 mm in CT room and 1.5 mm in treatment room, corresponding to gaze direction deviations consistently lower than 1°.

Integration of spatial distortion effects in a 4D computational phantom for simulation studies in extra-cranial MRI-guided radiation therapy: Initial results

PURPOSE

Spatial distortions in magnetic resonance imaging (MRI) are mainly caused by inhomogeneities of the static magnetic field, nonlinearities in the applied gradients, and tissue-specific magnetic susceptibility variations. These factors may significantly alter the geometrical accuracy of the reconstructed MR image, thus questioning the reliability of MRI for guidance in image-guided radiation therapy. In this work, we quantified MRI spatial distortions and created a quantitative model where different sources of distortions can be separated. The generated model was then integrated into a four-dimensional (4D) computational phantom for simulation studies in MRI-guided radiation therapy at extra-cranial sites.

METHODS

A geometrical spatial distortion phantom was designed in four modules embedding laser-cut PMMA grids, providing 3520 landmarks in a field of view of (345 × 260 × 480) mm³ . The construction accuracy of the phantom was verified experimentally. Two fast MRI sequences for extra-cranial imaging at 1.5 T were investigated, considering axial slices acquired with online distortion correction, in order to mimic practical use in MRI-guided radiotherapy. Distortions were separated into their sources by acquisition of images with gradient polarity reversal and dedicated susceptibility calculations. Such a separation yielded a quantitative spatial distortion model to be used for MR imaging simulations. Finally, the obtained spatial distortion model was embedded into an anthropomorphic 4D computational phantom, providing registered virtual CT/MR images where spatial distortions in MRI acquisition can be simulated.

RESULTS

The manufacturing accuracy of the geometrical distortion phantom was quantified to be within 0.2 mm in the grid planes and 0.5 mm in depth, including thickness variations and bending effects of individual grids. Residual spatial distortions after MRI distortion correction were strongly influenced by the applied correction mode, with larger effects in the trans-axial direction. In the axial plane, gradient nonlinearities caused the main distortions, with values up to 3 mm in a 1.5 T magnet, whereas static field and susceptibility effects were below 1 mm. The integration in the 4D anthropomorphic computational phantom highlighted that deformations can be severe in the region of the thoracic diaphragm, especially when using axial imaging with 2D distortion correction. Adaptation of the phantom based on patient-specific measurements was also verified, aiming at increased realism in the simulation.

CONCLUSIONS

The implemented framework provides an integrated approach for MRI spatial distortion modeling, where different sources of distortion can be quantified in time-dependent geometries. The computational phantom represents a valuable platform to study motion management strategies in extra-cranial MRI-guided radiotherapy, where the effects of spatial distortions can be modeled on synthetic images in a virtual environment.

Inter-fractional monitoring of [Formula: see text]C ions treatments: results from a clinical trial at the CNAO facility

The high dose conformity and healthy tissue sparing achievable in Particle Therapy when using C ions calls for safety factors in treatment planning, to prevent the tumor under-dosage related to the possible occurrence of inter-fractional morphological changes during a treatment. This limitation could be overcome by a range monitor, still missing in clinical routine, capable of providing on-line feedback. The Dose Profiler (DP) is a detector developed within the INnovative Solution for In-beam Dosimetry in hadronthErapy (INSIDE) collaboration for the monitoring of carbon ion treatments at the CNAO facility (Centro Nazionale di Adroterapia Oncologica) exploiting the detection of charged secondary fragments that escape from the patient. The DP capability to detect inter-fractional changes is demonstrated by comparing the obtained fragment emission maps in different fractions of the treatments enrolled in the first ever clinical trial of such a monitoring system, performed at CNAO. The case of a CNAO patient that underwent a significant morphological change is presented in detail, focusing on the implications that can be drawn for the achievable inter-fractional monitoring DP sensitivity in real clinical conditions. The results have been cross-checked against a simulation study.

Efficacy of memantine in schizophrenic patients: A systematic review

Introduction

Several evidences support the hypothesis that glutamatergic dysfunction may be implicated in the pathogenesis of schizophrenia and in the last few year great interest has been focused on the role of the N-methyl-D-aspartate receptor (NMDAR). Memantine is a noncompetitive NMDARs antagonist, binds the same site of NMDARs of Mg2+, endogenous blocker of NMDARs, with moderate affinity, rapid unblocking kinetics and strong functional voltage-dependency. Memantine does not affect the physiological activation of NMDARs whereas it blocks the sustained activation under pathological conditions. Preclinical studies have demonstrated that memantine at high concentrations targets many receptors, including serotonin, nicotinic acetylcholine, sigma-1 and serotonin and dopamine receptors.

Objectives

Increasing interest in memantine add-on therapy in schizophrenic patients with negative and cognitive symptoms may suggest that memantine could be a new promising treatment in schizophrenia.

Aims

The aim of this update was to evaluate clinical data about the memantine effectiveness in schizophrenic patients.

Methods

We searched on PubMed to identify original studies about the use of memantine in treatment of schizophrenic patients. The search conducted on June 16th, 2016 yielded 135 records. Neuf papers met our inclusion criteria.

Results

Negative symptoms improved in the large majority of patients treated, however there is not a clear evidence on cognitive and positive symptoms (Table 1)

Conclusions

Memantine therapy in schizophrenic patients has given unclear results. It seems that memantine improves mainly negative symptoms, while cognitive and positive symptoms did not improve significantly. Further trials with a more numerous sample are required obtain an objective result.

Table 1

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Party Hard: Drug-related Fatalities in Ibiza from 2010 to 2016

Introduction

Illicit drug use is well known as an important contributor to the global burden of diseases, but the physical and psychopathological risks of recreational drugs misuse are often underestimated and drug-related fatalities in specific settings are under-investigated.

Objectives and methods

In the framework of the EU-funded project “EU-Madness”, we collected and analysed all the reports of drug-related fatalities in Ibiza from January 2010 to September 2016, with the aim of characterising the sample, and identifying the involved substances and the nature of deaths associated with their consumption.

Results

Overall, 58 drug-related fatalities were registered from 2010 to September 2016 (87.9% males, 12.1% females, mean age 33.16; females were significantly younger than males). Most of the deceased were Britons (36.2%), followed by Spanish (22.4%), Italians (6.9%) and Germans (5.2%). In half the cases, the substance identified in post-mortem analyses was a stimulant; in 24.1% of the sample it was a depressor a prescription drug or more than two substances in 22.4%. Most of the fatalities were due to cardiovascular accidents (62%); 22.4% were deaths by drowning, 12% by fall from heights and 3.4% were due to mechanical asphyxia.

Conclusions

According to the results from our sample, stimulants (mainly MDMA and cocaine) are the substances of abuse involved in most drug-caused fatalities. The number of fatalities per year has been steadily increasing, but the growing diffusion of novel psychoactive substances (NPS) does not seem to be a direct cause (although better methods of their analysis in post-mortem samples should be designed).

Disclosure of interest

The authors have not supplied their declaration of competing interest.

A novel framework for spatial normalization of dose distributions in voxel-based analyses of brain irradiation outcomes

PURPOSE

To devise a novel Spatial Normalization framework for Voxel-based analysis (VBA) in brain radiotherapy. VBAs rely on accurate spatial normalization of different patients' planning CTs on a common coordinate system (CCS). The cerebral anatomy, well characterized by MRI, shows instead poor contrast in CT, resulting in potential inaccuracies in VBAs based on CT alone.

METHODS

We analyzed 50 meningioma patients treated with proton-therapy, undergoing planning CT and T1-weighted (T1w) MRI. The spatial normalization pipeline based on MR and CT images consisted in: intra-patient registration of CT to T1w, inter-patient registration of T1w to MNI space chosen as CCS, doses propagation to MNI. The registration quality was compared with that obtained by Statistical Parametric Mapping software (SPM), used as benchmark. To evaluate the accuracy of dose normalization, the dose organ overlap (DOO) score was computed on gray matter, white matter and cerebrospinal fluid before and after normalization. In addition, the trends in the DOOs distribution were investigated by means of cluster analysis.

RESULTS

The registration quality was higher for the proposed method compared to SPM (p < 0.001). The DOO scores showed a significant improvement after normalization (p < 0.001). The cluster analysis highlighted 2 clusters, with one of them including the majority of data and exhibiting acceptable DOOs.

CONCLUSIONS

Our study presents a robust tool for spatial normalization, specifically tailored for brain dose VBAs. Furthermore, the cluster analysis provides a formal criterion for patient exclusion in case of non-acceptable normalization results. The implemented framework lays the groundwork for future reliable VBAs in brain irradiation studies.

Time-resolved volumetric MRI in MRI-guided radiotherapy: an in silico comparative analysis

MRI-treatment units enable 2D cine-MRI centred in the tumour for motion detection in radiotherapy, but they lack 3D information due to spatio-temporal limits. To derive time-resolved 3D information, different approaches have been proposed in the literature, but a rigorous comparison among these strategies has not yet been performed. The goal of this study is to quantitatively investigate five published strategies that derive time-resolved volumetric MRI in MRI-guided radiotherapy: Propagation, out-of-plane motion compensation, Fayad model, ROI-based model and Stemkens model. Comparisons were performed using an MRI digital phantom generated with six different patient-derived motion signals and tumour-shapes. An average 4D cycle was generated as well as 2D cine-MRI data with corresponding 3D in-room ground truth. Quantitative analysis was performed by comparing the estimated 3D volume to the ground truth available for each 2D cine-MRI sample. A grouped patient statistical analysis was performed to evaluate the performance of the selected methods, in case of tumour tracking or motion estimation of the whole anatomy. Analyses were also performed based on patient characteristics. Quantitative ranking of the investigated methods highlighted that Propagation and ROI-based model strategies achieved an overall median tumour centre of mass 3D distance from the ground truth of 1.1 mm and 1.3 mm, respectively, and a diaphragm distance below 1.6 mm. Higher errors and variabilities were instead obtained for other methods, which lack the ability to compensate for in-room variations and to account for regional changes. These results were especially evident when further analysing patient characteristics, where errors above 2 mm/5 mm in tumour/diaphragm were found for more irregular breathing patterns in case of out-of-plane motion compensation, Fayad and Stemkens models. These findings suggest the potential of the proposed in silico framework to develop and compare strategies to estimate time-resolved 3DMRI in MRI-guided radiotherapy.

MRI-guidance for motion management in external beam radiotherapy: current status and future challenges

High precision conformal radiotherapy requires sophisticated imaging techniques to aid in target localisation for planning and treatment, particularly when organ motion due to respiration is involved. X-ray based imaging is a well-established standard for radiotherapy treatments. Over the last few years, the ability of magnetic resonance imaging (MRI) to provide radiation-free images with high-resolution and superb soft tissue contrast has highlighted the potential of this imaging modality for radiotherapy treatment planning and motion management. In addition, these advantageous properties motivated several recent developments towards combined MRI radiation therapy treatment units, enabling in-room MRI-guidance and treatment adaptation. The aim of this review is to provide an overview of the state-of-the-art in MRI-based image guidance for organ motion management in external beam radiotherapy. Methodological aspects of MRI for organ motion management are reviewed and their application in treatment planning, in-room guidance and adaptive radiotherapy described. Finally, a roadmap for an optimal use of MRI-guidance is highlighted and future challenges are discussed.

Thrombocytopenia in high-risk patients with antiphospholipid syndrome

Essentials The prevalence of thrombocytopenia in patients with antiphospholipid syndrome is not well defined. We studied triple positive patients with antiphospholipid syndrome and its catastrophic variant. Prevalence of thrombocytopenia was 6% and 100% in patients who developed the catastrophic form. In triple positive patients thrombocytopenia is low and platelets drop during the catastrophic form.

SUMMARY

Background Thrombocytopenia is the most common non-criteria hematological feature in patients with antiphospholipid syndrome (APS). This condition is more common in patients with catastrophic APS (CAPS). Objectives To evaluate the prevalence of thrombocytopenia in a large series of high-risk patients with APS, and to assess the behavior of the platelet count during CAPS. Methods/Patients This was a cross-sectional study in which we analyzed the platelet counts of a homogeneous group of high-risk APS patients (triple-positive). Six of these patients developed a catastrophic phase of the disease, and the platelet count was recorded before the acute phase, during the acute phase, and at recovery. Results The mean platelet count in 119 high-risk triple-positive patients was 210 × 109 L-1 . With a cut-off value for thrombocytopenia of 100 × 109 L-1 , the prevalence of thrombocytopenia was 6% (seven patients). No difference between primary APS and secondary APS was found. In patients who suffered from CAPS, a significant decrease from the basal count (212 ± 51 × 109 L-1 ) to that at the time of diagnosis (60 ± 33 × 109 L-1 ) was observed. The platelet count became normal again at the time of complete remission (220 ± 57 × 109 L-1 ). A decrease in platelet count always preceded the full clinical picture. Conclusions This study shows that, in high-risk APS patients, the prevalence of thrombocytopenia is low. A decrease in platelet count was observed in all of the patients who developed the catastrophic form of the disease. A decrease in platelet count in high-risk APS patients should be considered a warning signal for disease progression to CAPS.

The role of platelets in antiphospholipid syndrome

Despite extensive research, the pathogenesis of antiphospholipid syndrome (APS) remains obscure in many aspects. However, it is widely accepted that thrombosis is the result of a hypercoagulable state caused by antibodies directed against β2-glycoprotein I (β2-GPI), a protein whose physiological role is unknown. Although underestimated, platelets may be involved in APS and its thrombotic manifestations, especially arterial, in several ways. Thrombocytopenia is the most relevant non-criteria manifestation of APS, possibly caused by direct binding of anti-β2-GPI antibodies or anti-β2-GPI-β2-GPI complexes. On the other hand, platelets may have a key role in APS-related thrombosis due to the presence of multiple receptors that can interact with anti-β2-GPI antibodies (especially apolipoprotein E receptor 2' (apoER2') and glycoprotein Ibα (GPIbα)) with consequent release of different procoagulant mediators such as thromboxane B2, platelet factor 4 (PF4), and platelet factor 4 variant (CXCL4L1). The aim of this review is to put together evidence on the possible role of platelets in APS and to stimulate further research on the issue.

Enhanced Surface Registration Techniques for Patient Positioning Control in Breast Cancer Radiotherapy

Experimental data, describing patient inter-fractional set-up errors in the clinical practice of breast radiotherapy, were exploited to simulate the performance in errors detection and correction of a constrained surface registration procedure, based on a hybrid configuration of control points (passive and laser). During 47 treatment sessions in three patients undergoing post-quadrantectomy radiotherapy, an opto-electronic localizer was used to acquire the three-dimensional coordinates of the hybrid control points, being two passive markers placed on selected skin landmarks on the sternum. Laser scanning technique was also applied for the acquisition of the 3-D surface model of the irradiated body area, which was used as reference for the automatic position correction procedure. A constrained surface registration algorithm was applied to estimate the rigid spatial transformation, describing the local errors affecting the control points. The improvement of the irradiation geometrical setup, by correcting the patient position according to the estimated spatial transformation parameters, was simulated. Results showed that the proposed surface registration method allowed us to detect and significantly (Wilcoxon signed rank analysis) reduce the initial misalignments, which exhibited overall median and 75th percentile values equal to 4.26 mm and 5.76 mm. Simulated residual errors dropped down to median and 75th percentile values measuring 2.95 mm and 3.87 mm, respectively. These results confirmed the high potentiality of surface registration techniques for the opto-electronic automatic patient positioning control in breast cancer radiotherapy.