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Purpose: We describe a clinical grade, "active", monopole antenna‐based metallic guidewire that has a continuous shaft‐to‐tip image profile, a pre‐shaped tip‐curve, standard 0.89 mm (0.035″) outer diameter, and a detachable connector for catheter exchange during cardiovascular catheterization at 0.55T. Methods: Electromagnetic simulations were performed to characterize the magnetic field around the antenna whip for continuous tip visibility. The active guidewire was manufactured using medical grade materials in an ISO Class 7 cleanroom. RF‐induced heating of the active guidewire prototype was tested in one gel phantom per ASTM 2182‐19a, alone and in tandem with clinical metal‐braided catheters. Real‐time MRI visibility was tested in one gel phantom and in‐vivo in two swine. Mechanical performance was compared with commercial equivalents. Results: The active guidewire provided continuous "profile" shaft and tip visibility in‐vitro and in‐vivo, analogous to guidewire shaft‐and‐tip profiles under X‐ray. The MRI signal signature matched simulation results. Maximum unscaled RF‐induced temperature rise was 5.2°C and 6.5°C (3.47 W/kg local background specific absorption rate), alone and in tandem with a steel‐braided catheter, respectively. Mechanical characteristics matched commercial comparator guidewires. Conclusion: The active guidewire was clearly visible via real‐time MRI at 0.55T and exhibits a favorable geometric sensitivity profile depicting the guidewire continuously from shaft‐to‐tip including a unique curved‐tip signature. RF‐induced heating is clinically acceptable. This design allows safe device navigation through luminal structures and heart chambers. The detachable connector allows delivery and exchange of cardiovascular catheters while maintaining guidewire position. This enhanced guidewire design affords the expected performance of X‐ray guidewires during human MRI catheterization. [ABSTRACT FROM AUTHOR]

Purpose: This work aims to fabricate RF antenna components on metallic needle surfaces using biocompatible polyester tubing and conductive ink to develop an active interventional MRI needle for clinical use at 0.55 Tesla. Methods: A custom computer numeric control‐based conductive ink printing method was developed. Based on electromagnetic simulation results, thin‐film RF antennas were printed with conductive ink and used to fabricate a medical grade, 20‐gauge (0.87 mm outer diameter), 90‐mm long active interventional MRI needle. The MRI visibility performance of the active needle prototype was tested in vitro in 1 gel phantom and in vivo in 1 swine. A nearly identical active needle constructed using a 44 American Wire Gauge insulated copper wire‐wound RF receiver antenna was a comparator. The RF‐induced heating risk was evaluated in a gel phantom per American Society for Testing and Materials (ASTM) 2182‐19. Results: The active needle prototype with printed RF antenna was clearly visible both in vitro and in vivo under MRI. The maximum RF‐induced temperature rise of prototypes with printed RF antenna and insulated copper wire antenna after a 3.96 W/kg, 15 min. long scan were 1.64°C and 8.21°C, respectively. The increase in needle diameter was 98 µm and 264 µm for prototypes with printed RF antenna and copper wire‐wound antenna, respectively. Conclusion: The active needle prototype with conductive ink printed antenna provides distinct device visibility under MRI. Variations on the needle surface are mitigated compared to use of a 44 American Wire Gauge copper wire. RF‐induced heating tests support device RF safety under MRI. The proposed method enables fabrication of small diameter active interventional MRI devices having complex geometries, something previously difficult using conventional methods. [ABSTRACT FROM AUTHOR]

Purpose: This work aims to demonstrate the use of an "active" acousto‐optic marker with enhanced visibility and reduced radiofrequency (RF) ‐induced heating for interventional MRI. Methods: The acousto‐optic marker was fabricated using bulk piezoelectric crystal and π‐phase shifted fiber Bragg grating (FBGs) and coupled to a distal receiver coil on an 8F catheter. The received MR signal is transmitted over an optical fiber to mitigate RF‐induced heating. A photodetector converts the optical signal into electrical signal, which is used as the input signal to the MRI receiver plug. Acousto‐optic markers were characterized in phantom studies. RF‐induced heating risk was evaluated according to ASTM 2182 standard. In vivo real‐time tracking capability was tested in an animal model under a 0.55T scanner. Results: Signal‐to‐noise ratio (SNR) levels suitable for real‐time tracking were obtained by using high sensitivity FBG and piezoelectric transducer with resonance matched to Larmor frequency. Single and multiple marker coils integrated to 8F catheters were readout for position and orientation tracking by a single acousto‐optic sensor. RF‐induced heating was significantly reduced compared to a coax cable connected reference marker. Real‐time distal tip tracking of an active device was demonstrated in an animal model with a standard real‐time cardiac MR sequence. Conclusion: Acousto‐optic markers provide sufficient SNR with a simple structure for real‐time device tracking. RF‐induced heating is significantly reduced compared to conventional active markers. Also, multiple RF receiver coils connected on an acousto‐optic modulator can be used on a single catheter for determining catheter orientation and shape. [ABSTRACT FROM AUTHOR]

Background: Pericardial effusion drainage in patients with significant pulmonary hypertension (PH) has been questioned because of hemodynamic collapse concern, mainly because of right ventricular (RV) function challenging assessment. We aimed to assess RV function changes related to pericardiocentesis in patients with and without PH. Methods: Consecutive patients with symptomatic moderate‐to‐large pericardial effusion who had either echocardiographic or clinical signs of cardiac tamponade and who underwent pericardiocentesis from 2013 to 2018 were included. RV speckle‐tracking echocardiography analysis was performed before and after pericardiocentesis. Patients were stratified by significant PH (pulmonary artery systolic pressure [PASP] ≥50 mm Hg). Results: The study cohort consisted of 76 patients, 23 (30%) with PH. In patients with PH, both end‐diastolic and end‐systolic areas (EDA, ESA) increased significantly after pericardiocentesis (22.6 ± 8.0 cm2–26.4 ± 8.4 cm2, P =.01) and (15.9 ± 6.3 cm2–18.7 ± 6.5 cm2, P =.02), respectively. However, RV function indices including fractional area change (FAC: 30.6 ± 13.7%–29.1 ± 8.8%, P =.61) and free‐wall longitudinal strain (FWLS: −16.7 ± 6.7 to −15.9 ± 5.0, P =.50) remained unchanged postpericardiocentesis. In contrast, in the non‐PH group, after pericardiocentesis, EDA increased significantly (20.4 ± 6.2–22.4 ± 5.9 cm2, P =.006) but ESA did not (14.9 ± 5.7 vs 15.0 ± 4.6 cm2, P =.89), and RV function indices improved (FAC 27.9 ± 11.7%–33.1 ± 8.5%, P =.003; FWLS −13.6 ± 5.4 to −17.2 ± 3.9%, P <.001). Conclusion: Quantification of RV size and function can improve understanding of echocardiographic and hemodynamic changes postpericardiocentesis, which has the potential to guide management of PH patients with large pericardial effusion. [ABSTRACT FROM AUTHOR]

Migration is a critical aspect of ocean ecosystems, and understanding this phenomenon answers ecological and management questions. Given the difficulty in tracking ocean animals across large distances, the extent to which different ray species perform long‐distance movements, such as migrations, remains unknown. This study used passive acoustic telemetry to track the movements of endemic diamond Gymnura natalensis and critically endangered duckbill Aetomylaeus bovinus rays along the South African coastline using a collaborative nationwide network of coastal acoustic receivers for up to 7 years. Duckbill rays were detected significantly more frequently than diamond rays, but both species moved between the south and east coasts of South Africa (traveling up to 1167 km). Tagged individuals were detected significantly more often in their tagging locations during summer months but traveled significantly further distances during winter months. Furthermore, movement models fitted to individual duckbill rays' annual net‐squared displacement identified most individual annual movements as migratory. This evidence suggests that both diamond and duckbill rays make eastward winter migrations and return to specific areas along the coastline during the summer months. The exceptions to this were diamond rays tagged on the east coast that were not found to migrate seasonally, which supports previous research that there is intraspecific variability in migrations for ray species. These findings have implications for understanding ray migration not only on a global scale but also locally for spatial management interventions and population delineation. [ABSTRACT FROM AUTHOR]

The article presents a study that explores the experience of a single centre and uses a retrospective design to evaluate Sickle cell disease (SCD). Topics discussed include SCD is an autosomal recessive disease caused by a single point mutation in the HBB gene, mentions the cardiac catheterisation (CC), as an important part of the evaluation of patients with SCD, and information on the comparision of haemoglobin levels before and after CC with post-CC exacerbations.