Right-to-left Research Articles

Electrical impedance tomography in anaesthetised chickens (Gallus domesticus).

The applicability of electrical impedance tomography (EIT) in birds is unknown. This study aimed to evaluate the use of EIT in anaesthetised chickens in four recumbency positions. Four adult Hyline chickens were anaesthetised with isoflurane in oxygen, and intubated endotracheally for computed tomography (CT). A rubber belt was placed around the coelom caudal to the shoulder joint. A chicken-specific finite element (FE) model, which is essential to generate anatomically accurate functional EIT images for analysis, was constructed based on the CT images obtained at the belt level. Ten additional chickens were anaesthetised with the same protocol. An EIT electrode belt was placed at the same location. The chickens were breathing spontaneously and positioned in dorsal, ventral, right and left lateral recumbency in a randomised order. For each recumbency, raw EIT data were collected over 2 min after 13 min of stabilisation. The data were reconstructed into functional EIT images. EIT variables including tidal impedance variation (TIV), centre of ventilation right to left (CoVRL) and ventral to dorsal (CoVVD), right to left (RL) ratio, impedance change (ΔZ) and eight regional impedance changes including the dorsal, central-dorsal, central-ventral and ventral regions of the right and left regions were analysed. Four breathing patterns (BrP) were observed and categorised based on the expiratory curve. A linear mixed model was used to compare EIT variables between recumbencies. Fisher's exact test was used to compare the frequencies of breathing patterns for each recumbency. The ΔZ observed was synchronous to ventilation, and represented tidal volume of the cranial air sacs as confirmed by CT. Significant differences were found in CoVVD and regional impedance changes between dorsal and ventral recumbencies (P < 0.05), and in CoVRL, RL ratio and regional impedance changes between right and left recumbencies (P < 0.05), which suggested a tendency for the distribution of ventilation to shift towards non-dependent air sacs. No differences were found for TIV and respiratory rate between recumbencies. Recumbency had a significant effect on the frequencies of each of the four BrPs (P = 0.001). EIT can monitor the magnitude and distribution of ventilation of the cranial air sacs in different recumbencies in anaesthetised chickens.

18F]pFBC, a Covalent CLIP-Tag Radiotracer for Detection of Viral Reporter Gene Transfer in the Murine Brain.

Preclinical models of neurological diseases and gene therapy are essential for neurobiological research. However, the evaluation of such models lacks reliable reporter systems for use with noninvasive imaging methods. Here, we report the development of a reporter system based on the CLIP-tag enzyme and [18F]pFBC, an 18F-labeled covalent CLIP-tag-ligand synthesized via a DoE-optimized and fully automated process. We demonstrated its specificity using a subcutaneous xenograft model and a model of viral vector-mediated brain gene transfer by engineering HEK293 cells and striatal neurons to express membrane-tethered CLIP-tag protein. After in vitro characterization of the reporter, mice carrying either CLIP-tag expressing or control subcutaneous xenografts underwent dynamic [18F]pFBC PET imaging. The CLIP-tag expressing xenografts showed a significantly higher uptake than control xenografts (tumor-to-muscle ratio 5.0 vs 1.7, p = 0.0379). In vivo, metabolite analysis by radio-HPLC from plasma and brain homogenates showed only one radio-metabolite in plasma and none in the brain. In addition, [18F]pFBC showed fast uptake and rapid clearance from the brain in animals injected with adeno-associated virus (AAV)-CLIP in the right striatum but no right-to-left (R-L) uptake difference in the striata in the acquired PET data. In contrast, autoradiography showed a clear accumulation of radioactivity in the AAV-CLIP-injected right striatum compared to the sham-injected left striatum control. CLIP-tag expression and brain integrity were verified by immunofluorescence and light sheet microscopy. In conclusion, we established a novel reporter gene system for PET imaging of gene expression in the brain and periphery and demonstrated its potential for a wide range of applications, particularly for neurobiological research and gene therapy with viral vectors.

Dosimetric Comparison of 3D Conformal Radiotherapy (3D-CRT), Intensity-Modulated Radiotherapy (IMRT), and Volumetric-Modulated Arc Therapy (VMAT) in Cardiac-Sparing Whole Lung Irradiation.

Introduction Whole lung irradiation (WLI) is used for the treatment of lung metastasis in Wilms tumor and Ewing sarcoma; however, cardiac complications are one of the concerns. We report the dosimetric advantages of WLI using volumetric-modulated arc therapy (VMAT) and present a dosimetric comparison of VMAT with anteroposterior-posteroanterior (AP-PA) and static-field intensity-modulated radiation therapy (IMRT). Additionally, we evaluated the dosimetric impact of respiratory motion and intra-fractional motion during VMAT treatment. Methods Seven patients were recruited in this study. AP-PA, IMRT, one-isocenter (1-IC) VMAT, and 2-IC VMAT were planned on the maximum inspiration and expiration CT, respectively. The prescribed dose was 15 Gy in 10 fractions. To determine the effects of respiratory motion, the CT series was replaced and the dose was evaluatedwhile maintaining the beam information. To determine the effect of patient motion, perturbed dose calculations were performed using a two-IC VMAT. The perturbation doses were calculated by shifting only the IC of the one side beam by 3mm or 5 mm in the right-to-left (RL) direction. Results The mean heart dose was 1467.0 cGy, 790.0 cGy, 764.2 cGy, and 738.4 cGy for AP-PA, IMRT, 1-IC VMAT, and 2-IC VMAT, respectively. When the expiration CT plan was recalculated with inspiration CT, Dmax increased approximately by 8%. In the 2-IC VMAT plan, the D50%, D98%, and D2% dose differences were within ±2%, even with a 5 mm IC shift. Conclusion We confirmed a significant dosimetric advantage of VMAT over other techniques. 2-IC VMAT should be consideredan effective treatment option during irradiation for large target volumes.

Nonreciprocal phase shifts in spatiotemporally varying materials

Materials with spatiotemporally varying properties exhibit nonreciprocal wave propagation characteristics. Nonreciprocity is predominantly identified by a left-to-right (L-R) transmission amplitude that is different from the right-to-left (R-L) transmission amplitude; a significant difference in the transmitted amplitudes is often desirable in this context. We review nonreciprocal vibration transmission in discrete mechanical systems with spatiotemporally modulated elasticity. We discuss the importance of the transmitted phase in this context, specifically that the difference between the L-R and R-L transmitted phases can be the main contributor to breaking of reciprocity in short systems. We show that the formulation of the problem in terms of response envelopes provides a computationally efficient path for exploring the steady-state nonreciprocal transmission characteristics of spatiotemporally modulated materials. In particular, we use this technique to identify response regimes that are characterized by a nonreciprocal phase shift in transmitted vibrations while maintaining equal transmitted amplitudes or energies.

A Patient with Right-to-Left Shunt Atrial Septal Defect Without Pulmonary Hypertension

We present a case of atrial septal defect (ASD) in a 27-year-old young woman who presented with a right-to-left shunt despite normal pulmonary artery pressure without anomalous pulmonary venous drainage and only mild tricuspid regurgitation (TR), but it was associated with right ventricular dysfunction. Considering the dysfunction of the right heart and significant dilatation of the tricuspid annulus, the surgeon still decided to repair ASD and perform tricuspid valvuloplasty. The surgery lasted approximately three hours, and the whole procedure was smooth and uneventful. Her postoperative recovery was uneventful and discharged in good condition. The occurrence of right-to-left (R-L) shunting in patients with ASD is uncommon and is usually an ominous sign, heralding irreversible pulmonary hypertension (PH). There is little information about similar shunts for patients without PH and tricuspid regurgitation (TR), and the majority of these patients have an anatomic anomaly that favors this type of shunt. ASD with R-L shunt without Eisenmenger physiology is rarely reported and may be underestimated due to difficulty in its diagnosis. Intraoperative transesophageal echocardiography (TEE) examination should not only focus on cardiac structure but also the evaluation of ventricular function. Right-to-left shunt is possible in ASD patients even with normal pulmonary arterial pressure.

Impact of Amplitude and Phase of fMRI time series for Functional Connectivity Analysis

PurposeSeveral studies in the field of fMRI have reported the synchrony between the brain regions using instantaneous phase (IP) representation (derived from analytic representation of BOLD time series). We hypothesized that instantaneous amplitude (IA) representation from different brain regions might give additional information to the functional brain networks. To validate this, we explored this representation of resting state BOLD fMRI signal for deriving resting state networks (RSNs) and compared it with the IP representation based RSNs. MethodResting state fMRI data of 100 healthy adults (age=20–35 years, 54 females) from the population of 500 Subjects of HCP dataset were studied. Data was acquired using a 3T scanner in four runs (15-min each) with the phase encoding directions: Left to Right (LR), Right to Left (RL). These four runs were acquired in two sessions, and subjects were asked to keep their eyes open with a fixation on a white cross. The IA and IP representations were derived from a narrow-band filtered BOLD time series using Hilbert transforms and a seed-based approach is used to compute the RSNs in the brain. ResultsThe experimental results demonstrate that within the frequency range 0.01–0.1 Hz, IA representation based RSNs have the highest similarity score between the two sessions for the motor network. Whereas for fronto-parietal network, IP based activation maps have the highest similarity score for all the frequency bands. For higher frequency band (0.198–0.25 Hz) consistency of the obtained RSNs across two sessions reduced for both IA and IP representations. Fusion of IA and IP representations based RSNs in comparison to those of IP based representation, leads to 3–10% improvement in the similarity scores between the default mode network obtained for the two sessions. In addition, the same comparison demonstrates 15–20% improvement for the motor network in the frequency bands: 0.01–0.04 Hz, 0.04–0.07 Hz, slow5 (0.01–0.027 Hz) and slow-4 (0.027–0.073 Hz). It is also observed that the similarity score between two sessions using instantaneous frequency (IF) (derivative of unwrapped IP) representation in exploring functional connectivity (FC) networks is comparable with those obtained using IP representation. ConclusionOur findings suggest that IA-representation based measures can estimate RSNs with the reproducibility between the sessions comparable to that of the IP representation-based methods. This study demonstrates that IA and IP representations contain the complementary information of BOLD signal, and their fusion improves the results of FC.

Ductus arteriosus flow predicts outcome in neonates with congecsion.

To investigate whether the pattern of flow through the ductus arteriosus (DA) is associated with the need for extracorporeal membrane oxygenation support (ECMO) or death in neonates with congenital diaphragmatic hernia (CDH). Retrospective observational study. German level III Neonatal Intensive Care Unit. One hundred and nine CDH neonates were born between March 2009 and May 2021. DA flow pattern was assessed in echocardiograms obtained within 24 h of life by measuring flow time and velocity time integral (VTI) for both left-to-right (LR) and right-to-left (RL) components of the ductal shunt. A VTI ratio (VTILR/VTIRL) < 1.0 and an RL relative flow time (flow timeRL/(Flow timeLR+Flow timeRL)) >33% were defined as markers of abnormal flow patterns. The primary outcome was the need for ECMO. The secondary outcome was death. Seventy-two patients (51.8%) had a VTI ratio <1.0, 73 (52.5%) an RL relative flow time >33%. Fifty-nine patients (42.4%) had an alteration of both values. Need for ECMO was present in 37.4% (n = 52), while 19.4% (n = 27) died. A VTI ratio <1.0 had the highest diagnostic accuracy for the need for ECMO, (sensitivity 82.7%, specificity 66.7%, negative predictive value [NPV] 86.6%, and positive predictive value [PPV] 59.7%) as well as for death (sensitivity 77.8%, specificity 54.5%, NPV 91.0%, and PPV 29.2%). Patients with VTI ratio <1.0 were 4.7 times more likely to need ECMO and 3.3 times more likely to die. VTI ratio values correlated significantly with pulmonary hypertension (PH) severity (r = -0.516, p < 0.001). A VTI ratio <1.0 is a valuable threshold to identify high-risk CDH neonates. For improved risk stratification, other parameters-for example, left ventricular cardiac dysfunction-should be combined with DA flow assessment.

Secure and Compact Elliptic Curve Scalar Multiplication with Optimized Inversion

Abstract Elliptic curve cryptography (ECC) is a typical public key cryptography technique that can ensure equivalent security with considerably smaller key sizes than Rivest-Shamir-Adleman (RSA). Hence, various implementations based on ECC are recommended for block chain and Internet of Things (IoT) devices. Because elliptic curve scalar multiplication (ECSM) is a fundamental computation in ECC, enhancing the security and efficiency of ECSM is important. ECSM specifies a scalar multiplication algorithm and elliptic curve addition formulae. Elliptic curve addition formulae on affine coordinates are compact from a memory cost perspective but weak against side channel attacks. Elliptic curve complete addition (CA) formulae can achieve secure ECSMs but are inefficient. A newly proposed secure ECSM, which uses a right-to-left (RL) scalar multiplication algorithm and (extended) affine coordinates, takes advantage of elliptic curve addition formulae on affine coordinates. However, it can only scan the input scalars from right to left. We propose new ECSMs, which can scan the input scalars from left to right (LR) based on (extended) affine coordinates. We also prove that our LR ECSMs satisfy secure generality without requiring exceptional computations. We enhance the efficiency of both LR and RL ECSMs with optimized inversion. Our LR ECSM with a memory of 12 field elements reduces that of the Montgomery ladder and Joye’s LR with CA formulae by 36.84% and that of 2-ary RL with (extended) affine coordinates by 14.29%, respectively. Our compact ECSMs are fit for applications on IoT devices and block chain, with a critical memory requirement.

Iatrogenic Atrial Septal Defect after Intracardiac Echocardiography-Guided Left Atrial Appendage Closure: Incidence, Size, and Clinical Outcomes

The data on iatrogenic atrial septal defect (iASD) after left atrial appendage closure (LAAC), especially intracardiac echocardiography (ICE)-guided LAAC, are limited. Compared with transesophageal echocardiography (TEE)- or digital subtraction angiography (DSA)-guided LAAC, the transseptal puncture (TP) ICE-guided LAAC is more complicated. Whether or not ICE-guided TP increases the chances of iASD is controversial. We investigate the incidence, size, and clinical outcomes of iASD after ICE-guided LAAC. A total of 177 patients who underwent LAAC were enrolled in this study and were assigned to the ICE-guided group (group 1) and the TEE- or DSA-guided group (group 2). Echocardiography results and clinical performances at months 2 and 12 post-procedure were collected from the electronic outpatient records. A total of 112 and 65 patients were assigned to group 1 and group 2, respectively. The incidence of iASD at follow-up (FU) month 2 was comparable between the groups (21.4% in group 1 vs. 15.4% in group 2, p = 0.429). At month 12 of FU, the closure rate of iASD was comparable to that of group 2 (70.6% vs. 71.4%, p = 1.000). No right-to-left (RL) shunt was observed among the iASD patients during the FU. Numerically larger iASD were observed in group 1 patients at month 2 of FU (2.8 ± 0.9 mm vs. 2.2 ± 0.8 mm, p = 0.065). No new-onset of pulmonary hypertension and iASD-related adverse events were observed. Univariable and multivariable logistic regression analysis showed that ICE-guided LAAC was not associated with the development of iASD (adjusted OR = 1.681; 95%CI, 0.634-4.455; p = 0.296). The ICE-guided LAAC procedure does not increase the risk of iASD. Despite the numerically large size of the iASD, it did not increase the risk of developing adverse complications.

Two Cultural Processing Asymmetries Drive Spatial Attention.

Cultural routines, such as reading and writing direction (script direction), channel attention orientation. Depending on one's native language habit, attention is biased from left-to-right (LR) or from right-to-left (RL). Here, we further document this bias, as it interacts with the spatial directionality that grounds time concepts. We used a spatial cueing task to test whether script direction and the grounding of time in Portuguese (LR, Exp. 1) and Arabic (RL, Exp. 2) shape visuomotor performance in target discrimination. Temporal words (e.g., tomorrow, yesterday) were presented as cues in two modalities: visual (Exp. 1-2) and auditory (Exp. 1). Gaze movement (Exp. 1) and speed of discrimination decisions (Exp. 1-2) of targets presented to the left or right sides of the screen were assessed. As predicted, the interaction between target location and time concepts was significant across both modalities and linguistic communities. Additionally, LR participants detected the target on the right side of the screen faster after a future word than the target on the left side of the screen after a past word cue. In contrast, RL participants detected the target on the left side of the screen faster when the cue word was a future word than the target on the right side of the screen cued by a past word. In both modalities, the initial eye-gaze movement (Exp. 1) was responsive to the cue's time referent, further confirming that time orients attention. An additional bias was observed for the first fixation onset, which landed earlier on the target set that matched habitualized spatial routines. We conclude that scanning regularities are shaped by writing habits and bodily grounded categorical features.

Children gradually construct spatial representations of temporal events.

English-speaking adults often recruit a "mental timeline" to represent events from left-to-right (LR), but its developmental origins are debated. Here, we test whether preschoolers prefer ordered linear representations of events and whether they prefer culturally conventional directions. English-speaking adults (n=85) and 3- to 5-year-olds (n=513; 50% female; ~47% white, ~35% Latinx, ~18% other; tested 2016-2018) were told three-step stories and asked to choose which of two image sequences best illustrated them. We found that 3- and 4-year-olds chose ordered over unordered sequences, but preferences between directions did not emerge until at least age 5. Together, these results show that children conceptualize time linearly early in development but gradually acquire directional preferences (e.g., for LR).

CHEST PAIN DILEMMA IN A PATIENT WITH TWO LEFT TO RIGHT SHUNTS

CHEST PAIN DILEMMA IN A PATIENT WITH TWO LEFT TO RIGHT SHUNTS

Abstract 117: Contrast-enhanced Transcranial Doppler Ultrasonography Versus Transesophageal Echocardiography As Screening Tool In Embolic Stroke

Introduction: Right-to-left (RtL) intracardiac and intrapulmonary shunts are associated with embolic stroke. Although contrast-enhanced transcranial doppler ultrasonography (ceTCD) and transesophageal echocardiography (TEE) are used in embolic stroke work up, there are no standardized guidelines as to which test should be considered as ‘gold standard’. Our objective is to evaluate the sensitivity of contrast-enhanced TCD and TEE in detecting right-to-left shunt to determine respective utilities as screening tools. Methods: Electronic medical records of subjects presenting with acute neurological symptoms who had ceTCD and TEE were evaluated. Sensitivity and specificity were calculated. Based on the respective prevalence of intracardiac and intrapulmonary shunts, positive predictive value, negative predictive value, and test accuracy were determined for ceTCD and TEE. Social Science Statistics was used for data analysis. Results: From June 2016 to August 2021, of 7,498 ischemic stroke patients, 260 patients were suspected of having strokes related to right to left shunts and underwent ceTCD and TEE for detection of cardioembolic sources for stroke. A positive right-to-left shunt was detected in 83 subjects. Detection by ceTCD was confirmed by the operator for 81 patients while 2 were considered false positive results (delayed sporadic High Intensity Transient Signals (HITS)). Sensitivity of ceTCD was 97.65% (95% CI [91.76%, 99.71%]). No safety concerns were identified in patients undergoing ceTCD. Of those with positive ceTCD (68.57%, n=35) were detected by Valsalva, and all of those 35 patients had negative TEE. TEE had sensitivity of 70.34% (95% CI [61.23%, 78.39%]). Conclusion: Contrast-enhanced TCD has superior sensitivity, is cost-effective, practical, and a safe alternative to TEE in identifying intracardiac or intrapulmonary shunts. Screening superiority of ceTCD may lie in ability to elicit shunts during Valsalva maneuvers. To our knowledge this is the largest single center series confirming ceTCD as a gold standard tool for screening of right to left shunts.

Abstract 1122‐000180: Contrast‐Enhanced Transcranial Doppler Ultrasonography Versus Transesophageal Echocardiography as Screening Tool in Embolic Stroke

Introduction : Right‐to‐left (RtL) intracardiac and intrapulmonary shunts are associated with embolic stroke. Although contrast‐enhanced transcranial doppler ultrasonography (ceTCD) and transesophageal echocardiography (TEE) are used in embolic stroke work up, there are no standardized guidelines as to which test should be considered as ‘gold standard’. Our objective is to evaluate the sensitivity of contrast‐enhanced TCD and TEE in detecting right‐to‐left shunt to determine respective utilities as screening tools. Methods : Electronic medical records of subjects presenting with acute neurological symptoms who had ceTCD and TEE were evaluated. Sensitivity and specificity were calculated. Based on the respective prevalence of intracardiac and intrapulmonary shunts, positive predictive value, negative predictive value, and test accuracy were determined for ceTCD and TEE. Social Science Statistics was used for data analysis. Results : From June 2016 to August 2021, of 7,498 ischemic stroke patients, 260 patients were suspected of having strokes related to right to left shunts and underwent ceTCD and TEE for detection of cardioembolic sources for stroke. A positive right‐to‐left shunt was detected in 83 subjects. Detection by ceTCD was confirmed by the operator for 81 patients while 2 were considered false positive results (delayed sporadic High Intensity Transient Signals (HITS)). Sensitivity of ceTCD was 97.65% (95% CI [91.76%, 99.71%]). No safety concerns were identified in patients undergoing ceTCD. Of those with positive ceTCD (68.57%, n = 35) were detected by Valsalva, and all of those 35 patients had negative TEE. TEE had sensitivity of 70.34% (95% CI [61.23%, 78.39%]). Conclusions : Contrast‐enhanced TCD has superior sensitivity, is cost‐effective, practical, and a safe alternative to TEE in identifying intracardiac or intrapulmonary shunts. Screening superiority of ceTCD may lie in ability to elicit shunts during Valsalva maneuvers. To our knowledge this is the largest single center series confirming ceTCD as a gold standard tool for screening of right to left shunts.

Importance of direct right-to-left shunt as high-risk patent foramen ovale associated with cryptogenic stroke.

Because transcatheter closure of patent foramen ovale (PFO) has become effective for preventing cryptogenic stroke (CS), it is necessary to determine high-risk PFO associated with CS. This study aimed to clarify the importance of direct right-to-left (RL) shunt through the PFO for identifying high-risk PFO. We analyzed 137 patients with and without CS who were confirmed to have PFO. The timing of RL shunt through the PFO was evaluated by cardiac cycles after right atrium (RA) opacification on saline contrast transesophageal echocardiography. Direct RL shunt was defined as microbubbles crossing the PFO before and at the same time of RA opacification. Cardiac cycles of microbubbles crossing the PFO were shorter in patients with CS than in those without CS (2.0 ± 2.2vs .5 ± 1.1, p<0.01). Direct RL shunt was more frequently observed in patients with CS than in those without CS (77%vs 29%, p<0.01), with a sensitivity of 79% and a specificity of 71% for the association with CS. Multivariate analysis revealed that direct RL shunt was related to atrial septal aneurysm and low-angle PFO. Regarding functional features of PFO, the detection rate of CS was 50% for large RL shunt alone, and was increased to 83% when direct RL shunt was added. Direct RL shunt was associated with CS and had the incremental value in detecting PFO associated with CS for large RL shunt. The timing of RL shunt can be valuable for identifying high-risk PFO.

Impact of Time Interval Between Diagnostic and Planning MRI on Tumor Volume and Anatomic Displacement for Brain Metastases Undergoing Stereotactic Radiosurgery

Stereotactic radiosurgery (SRS) is increasingly used in brain metastasis patients. However, the impact of the timing on tumor volume change and tumor anatomical displacement between the diagnostic and treatment planning imaging is not well studied.Consecutive patients diagnosed with brain metastases and treated with SRS between July, 2017 and June, 2020 were evaluated. Only patients who underwent an institutionally standardized diagnostic MRI (MRI-1) and a treatment planning MRI (MRI-2) with identical imaging parameters were included. The impact of histology, inter-scan interval, lesion location, volume and size were evaluated on final lesion size, volume and anatomic displacement. Correlations were assessed using Kendall's rank correlation. The Kruskal Wallis rank sum test was used for all other comparisons.We included 101 eligible patients (531 lesions) with median inter-scan interval of 8 days (range: 1-42); 50% were NSCLC and 25% breast cancer. The three most common locations of lesions were the frontal (181 lesions, 34%), temporal (96, 18%), cerebellar (91, 17%) lobes. Median MRI-1 diameter and volume were 0.50 cm (Range: 0.23-0.89 cm) and 0.06 cm3 (Range: 0.01-4.62 cm3), respectively. Median percentage change in lesion diameter and volume were +9.5% (Range: -8.4% to +61.2%) and +20% (Range: -20% to +200%), respectively. Overall, there was a statistically significant change in percent tumor volume change between MRI-1 to MRI-2 (P = 0.01). Directional displacements exceeded 1 mm in 18 (3%) lesions in right to left (RL), 28 (5%) superior to inferior (SI), and 25 (4.7%) anterior to posterior (AP) directions. Overall, 355 (67%) lesions had any displacement in at least 1 direction between MRI-1 and MRI-2 and 205 (38%) in all 3 directions. Median lesion centroid displacement was 0.48 mm (0.10-3.09 mm) and was larger than 1 mm in 66 (12%) lesions. Differences were also observed across tumor histologies (P = 0.01); melanoma brain metastases had the largest magnitude changes. Tumor displacement also differed across various histologies with largest displacement in renal cell carcinoma metastases (P < 0.001). Magnitude of displacement was also significantly associated with tumor location (P = 0.03) with the largest displacement in parietal lobe lesions. Across all lesions, there was a difference in tumor size change in patients treated on corticosteroids (P = 0.01).Volumetric and positional changes can occur during the planning process for SRS and are histology and location specific. Additional analyses are key to understanding the impact of each of these variables, corticosteroids, and systemic therapy to better understand and model tumor dynamics.T. Kutuk: None. R.P. Tolakanahalli: None. A. Williams: None. M.C. Tom: Research Grant; Blue Earth Diagnostics. J.D. Vadhan: None. H. Appel: None. M.D. Hall: Research Grant; Florida Department of Health; Proton Collaborative Group (PCG) Executive Council. D. Wieczorek: None. S.D. Davis: None. M.W. McDermott: Consultant; Stryker, Diende. V. Siomin: None. M.D. Chuong: Research Grant; ViewRay, AstraZeneca. Honoraria; ViewRay, Sirtex, Accuray. Speaker's Bureau; ViewRay, Sirtex, Accuray. Advisory Board; ViewRay, Advanced Accelerator Applications. Travel Expenses; ViewRay, AstraZeneca, Accuray; Particle Therapy Cooperative Group. Manages the operations and activities within the proton center; Miami Cancer. M.P. Mehta: None. A. Gutierrez: Honoraria; ViewRay, Elekta. R. Kotecha: None.

Segmental evaluation of right ventricular systolic function in atrial septal defect (ASD) type II patients

Abstract Introduction A left to right (LR) shunt in atrial septal defect (ASD) may cause right heart and pulmonary overfilling, at the expense of the systemic circulation. Purpose The study objective was to evaluate the impact of LR shunt on left (LV) and right ventricular (RV) filling, function, and myocardial strain by using cardiovascular magnetic resonance imaging (CMR). Methods Thirty-five ASD type secundum patients (42±18 y.o.) were compared to a control group (n=40). Cine imaging was used to calculate ventricular volumes and ejection fraction (EF), global longitudinal (GLS) and circumferential (GCS), free wall (FW) and interventricular septal (IVS) longitudinal strain. Phase-contrast imaging was used to calculate pulmonary flow to systemic flow ratio (Qp/Qs). Results Qp/Qs was 2.2±0.60 (range 1.3–3.6), which resulted in higher RV end-diastolic volume/BSA (EDVi, 152±42 vs. 82±11 ml/m2), lower LV EDVi (72±17 vs. 83±10 ml/m2), and higher RV/LV EDVi ratio (2.1±0.5 vs. 1±0.1) compared to controls (all p&amp;lt;0.001) [Figure 1]. Patients also presented with higher RV, but lower LV indexed stroke volumes (both p&amp;lt;0.001), and a strong trend toward lower RVEF (p=0.08). They demonstrated significantly lower RV GLS (p=0.03) and longitudinal IVS strain (p&amp;lt;0.001) [Figure 2]. RV FW strain or RV GCS did not differ among study groups. Shunt severity correlated with RV size and stroke volume, right atrial size and pulmonary trunk diameter (all p&amp;lt;0.001). In contrast, no correlation was identified with functional nor strain parameters. Conclusion Cardiac remodeling in ASD patients with long-standing LR shunt negatively affects RV systolic performance, which is likely related to longitudinal septal dysfunction. Funding Acknowledgement Type of funding sources: None. Figure 1Figure 2

Importance of saline contrast transthoracic echocardiography for evaluating large right-to-left shunt in patent foramen ovale associated with cryptogenic stroke

Transcatheter closure of patent foramen ovale (PFO) is an effective therapy for preventing recurrent stroke in very specific patient cohorts, such as cryptogenic stroke (CS). The identification of high-risk PFO, which is more likely to be linked to CS, is essential. This study aimed to assess the accuracy of saline contrast transthoracic echocardiography (TTE) for evaluating large right-to-left (RL) shunt. We enrolled 119 patients with or without CS who were confirmed to have PFO by transesophageal echocardiography (TEE) or catheterization. The severity of RL shunt evaluated by TTE and TEE was classified as follows: small (< 10 microbubbles), moderate (10–20 microbubbles), and large (> 20 microbubbles). With TTE, large RL shunt was observed in 94 (79%) of 119 patients, including 66 of 74 with CS and 28 of 45 without CS. With TEE, large RL shunt was observed in 33 (28 %) patients, including 26 with CS and 7 without CS. TTE showed large RL shunt more frequently than TEE (p < 0.01). Large RL shunt evaluated by TTE had a sensitivity of 89 % and an accuracy of 70 % for the association with CS, whereas large RL shunt evaluated by TEE had a sensitivity of 35% and an accuracy of 56 %. Accuracy was significantly greater in TTE than in TEE (p = 0.02). In conclusion, TTE identified large RL shunt associated with CS with higher sensitivity and accuracy compared to TEE. Our findings suggest that the decision for device closure should be made based on the severity of RL shunt by TTE.

Diagnosis and endovascular management of pulmonary arteriovenous malformations.

Pulmonary arteriovenous malformations (PAVM) are abnormal communication of a branch of the pulmonary artery and pulmonary vein circumventing the intervening pulmonary capillaries. This results in a right-to-left (R-L) shunt and its related manifestations, which include hampered gas exchange leading to hypoxaemia, dyspnoea, paradoxical emboli leading to stroke, cerebral abscess, myocardial infarction and pulmonary haemorrhage due to rupture of the PAVM. Endovascular transcatheter embolization of the feeding vessels with coils or occlusion devices is the current standard care of treatment and preferred treatment modality. The articles aim to provide insights into the current trends in diagnosis, the current recommendations, approach and management options for patients with PAVM.

Bidirectional Dynamic Change in Shunt Flow Across a Small Ventricular Septal Defect in a Patient With a Left Ventricular Assist Device

A 50-year-old man implanted with a durable left ventricular assist device (LVAD; HeartMate 3, Abbott Laboratories, Chicago, IL) for idiopathic dilated cardiomyopathy was transferred to our hospital for further follow-up. He had not been diagnosed with any intracardiac shunts before LVAD implantation. On admission, echocardiography revealed a small left-to-right (L-R) shunt flow across the interventricular septum, indicating muscular ventricular septal defect (VSD). As the pump speed was raised during an echocardiographic ramp test for LVAD optimization, the L-R shunt flow at low pump speed (Fig.