Endovascular navigation with Fiber Optic RealShape technology

OBJECTIVE

Fiber Optic RealShape (FORS) technology has recently been introduced as an adjunctive guidance technology that allows real-time three-dimensional visualization of dedicated endovascular devices while avoiding radiation exposure. It consists of equipment which sends pulses of light through hair-thin optical fibers that run within a dedicated hydrophilic wire and selective catheters. The purpose of the study was to report the observed benefits and limitations related to the first edition of FORS technology.

METHODS

Data were collected prospectively from the first 50 patients undergoing FORS-guided endovascular repair at a single center between February 2020 and February 2021 as part of the global multicenter FORS Learn registry. All consecutive, elective procedures with one or more navigation tasks attempted with FORS were included. Factors related to FORS navigation task success were assessed. The time required for the catheterization of each task as well as the amount of radiation exposure (fluoroscopy time, dose area product, and estimated skin dose) were collected. A per-task analysis was conducted. End points included the success rate in achieving a stable FORS-guided catheterization, catheterization time, and radiation dose during catheterization.

RESULTS

During the study period from February 2020 to February 2021, 50 patients were treated using FORS technology. Forty-five patients were treated for aortic aneurysm, 4 for iliac artery aneurysm, and 1 for splenic artery aneurysm. Overall, 201 navigation tasks were completed for these procedures and FORS was used in 186 tasks (92.5%). No FORS-related complication was recorded and a success rate of 60.2% (n = 116) was observed. Target vessel (TV) angle of 45° or greater, TV stenosis, and the renal arteries as navigation tasks (compared with celiac artery or superior mesenteric artery) were associated with a lower success rate. Catheterization of a TV through a branch more frequently required a standard catheter in combination with the FORS-enabled guidewire. Successful task catheterization using FORS guidance was associated with a shorter catheterization time 6 minutes (interquartile range, 3-11 minutes) versus 16 minutes (interquartile range, 10-24 minutes) (P < .001) and lower radiation exposure compared with unsuccessful catheterization (dose area product, 4.4 cGy/cm² vs 12.5 cGy/cm²; P < .001).

CONCLUSIONS

FORS technology was implemented successfully as a new guidance technology in a complex endovascular aortic repair program and was associated with an encouraging success rate and a high potential for radiation reduction.

Radiation-free Thoracic Endovascular Aneurysm Repair with Fiberoptic and Electromagnetic Guidance:A Phantom Study

PURPOSE

The purpose of this study was to evaluate the feasibility and accuracy of a radiation-free implantation of a thoracic aortic stent-graft employing fiberoptic and electromagnetic tracking in an anthropomorphic phantom.

MATERIALS AND METHODS

An anthropomorphic phantom was manufactured based on computed tomography angiography (CTA) data from a patient. An aortic stent-graft application system was equipped with a fiber Bragg gratings fiber and three electromagnetic sensors. The stent-graft was navigated in the phantom by three interventionalists using the tracking data generated by both technologies. One implantation procedure was performed. The technical success of the procedure was evaluated using digital subtraction angiography and pre- and post-interventional CTA. Tracking accuracy was determined at various anatomical landmarks based on separately acquired fluoroscopic images. The mean/maximum errors were measured for the stent-graft application system and the tip/end of the stent-graft.

RESULTS

The procedure resulted in technical success with a mean error below 3 mm for the entire application system and <2 mm for the position of the tip of the stent-graft. Navigation/implantation and handling of the device were rated sufficiently accurate and on a par with comparable, routinely used stent-graft application systems.

CONCLUSION

Our study demonstrates successful stent-graft implantation during a thoracic endovascular aortic repair procedure employing advanced guidance techniques and avoiding fluoroscopic imaging. This is an essential step in facilitating the implantation of stent-grafts and reducing the health risks associated with ionizing radiation during endovascular procedures.

Two manoeuvres to facilitate the oral insertion of LMA CTrach™

Background and Aims:

LMA CTrach^TM, a new intubating conduit, has a thicker shaft compared to that of the intubating laryngeal mask airway (ILMA) due to the embedded optical fibres of the system. This causes difficulty during insertion despite normal mouth opening. Utility of two manoeuvres to overcome this was evaluated.

Methods:

From our experience with LMA CTrach^TM we found that two manoeuvres can be helpful to facilitate the insertion of LMA (a) dorsal and downward pressure over the shaft at the point where it hinges against the incisors while continuing the one handed rotational insertion of LMA (b) Lateral insertion of the LMA till the cuff is inside the oral cavity and then rotation of the LMA by 90° and then complete the insertion. A retrospective analysis of 200 insertions of LMA CTrach^TM was done to evaluate the utility of these manoeuvres.

Results:

Out of 200 insertions, 15 were found to be difficult. Manoeuvre “a” was applied in 13 cases to facilitate the insertion and manoeuvre “b” was applied in 2 cases where insertion was not possible despite manoeuvre “a'. Insertion was successful in these cases after the application of the described manoeuvres.

Conclusion:

The two manoeuvres described above can be useful when LMA CTrach^TM insertion into the oral cavity is obstructed by the incisor teeth.

First in Human Clinical Feasibility Study of Endovascular Navigation with Fiber Optic RealShape (FORS) Technology

OBJECTIVE

Endovascular procedures are conventionally conducted using two dimensional fluoroscopy. A new technology platform, Fiber Optic RealShape (FORS), has recently been introduced allowing real time, three dimensional visualisation of endovascular devices using fiberoptic technology. It functions as an add on to conventional fluoroscopy and may facilitate endovascular procedures. This first in human study assessed the feasibility of FORS in clinical practice.

METHODS

A prospective cohort feasibility study was performed between July and December 2018. Patients undergoing (regular or complex) endovascular aortic repair (EVAR) or endovascular peripheral lesion repair (EVPLR) were recruited. FORS guidance was used exclusively during navigational tasks such as target vessel catheterisation or crossing of stenotic lesions. Three types of FORS enabled devices were available: a flexible guidewire, a Cobra-2 catheter, and a Berenstein catheter. Devices were chosen at the physician's discretion and could comprise any combination of FORS and non-FORS devices. The primary study endpoint was technical success of the navigational tasks using FORS enabled devices. Secondary study endpoints were user experience and fluoroscopy time.

RESULTS

The study enrolled 22 patients: 14 EVAR and eight EVPLR patients. Owing to a technical issue during start up, the FORS system could not be used in one EVAR. The remaining 21 procedures proceeded without device or technology related complications and involved 66 navigational tasks. In 60 tasks (90.9%), technical success was achieved using at least one FORS enabled device. Users rated FORS based image guidance "better than standard guidance" in 16 of 21 and "equal to standard guidance" in five of 21 procedures. Fluoroscopy time ranged from 0.0 to 52.2 min. Several tasks were completed without or with only minimal X-ray use.

CONCLUSION

Real time navigation using FORS technology is safe and feasible in abdominal and peripheral endovascular procedures. FORS has the potential to improve intra-operative image guidance. Comparative studies are needed to assess these benefits and potential radiation reduction.

[Acoustic response characteristics of posterior intralaminar nucleus of auditory thalamus in mice]

Objective: To study the response characteristics of the posterior intralaminar nucleus (PIN) of auditory thalamus in VGluT2-Cre transgenic adult mice when exposed to white noise and 10K pure tone stimulation. Methods: All adult male Vglut2-Cre mice (8-12 weeks) were used in this study between Oct, 2017 and Oct, 2018. Using the calcium signal fiber photometry method, optic fiber was employed to locate on PIN by injecting AAV-hSyn-DIO-GCaMP6m virus, and thereafter, the activity of the target cluster neurons during different acoustic stimuli was recorded. Matlab was used for data processing and statistical analysis. Results: (1)In both white noise and 10 kHz pure tone as a continuous three-second stimulation, the peak amplitude of calcium signal activity generated in PIN by white noise was superior to that of pure tone, the statistic result showed significantly difference (n=6, t=2.404, P=0.037 1) . (2)In addition, when white noise and 10K pure tone played as consecutive 3 or 5 pips within three-second stimulation, the stimulus-following ability in a consecutive 3 pulses play within 3 seconds was far better than a consecutive 5 pips play within 3 seconds (in both white noise and 10 kHz pure tone), yet consecutive 3 pips play showed greater signal attenuation speed than that in consecutive 5 pips play, the statistic result showed significantly difference (n=6, t=2.748 P=0.033 4) .(3)Regardless of the intra-group comparisons between white noise and 10 kHz pure tone stimulation, PIN showed better signal response in a consecutive 3 pips play than consecutive 5 pips play or a continuous three-second stimulation. When came to the statistical analysis, the acoustic response degree of a continuous three-second stimulation was an intermediate between two others, both consecutive 3 or 5 pips play showed significantly difference. Conclusions: The results suggest that under the same acoustic intensity, VGluT2-Cre transgenic adult mice's PIN shows greater signal response in white noise than pure tone. PIN shows greater signal attenuation to repetition play of 10 kHz pure tone, which implies PIN shows stronger adaptation to 10 kHz pure tone than to white noise. Lastly, PIN is more responsive to a complex sound information (white noise) than to simple sound information (pure tone).

Thermal injury to common operating room materials by fiber optic light sources and endoscopes

PURPOSE

To determine the thermal energy damage potential by heat sources, such as endoscopes and fiber optic light cables, in contact with materials commonly placed around an operating room (OR) table.

MATERIALS AND METHOD

Injury by xenon and halogen light sources were tested by direct and indirect contact using fiber optic light bundle cables and scopes at light intensities between ranging from Standby to 100%. The scopes had diameters ranging from 2.7 mm to 10 mm and were set at varying angles. The materials tested were surgical drapes, cotton towels, child shirts, child pants, lap sponges, X-ray detectable sponges, and Mayo covers. The damage potential was determined qualitatively by presence of smoking or smell of burning.

RESULTS

Permutations involving direct contact were able to cause thermal injury, while permutations involving indirect contact, endoscopes, or halogen lamp were not. The xenon light source with the fiber optic light cable created thermal injury at light intensities of 50%, 75%, and 100%. Time to injury increased as light intensity was decreased. Only the surgical drape, child shorts, and cotton towel showed evidence of burn injury.

CONCLUSIONS

This report supports the potential for thermal injury to the patient secondary to fiber optic light sources, although this potential may be limited in extent. The injury risk can be reduced by avoiding direct contact to materials overlying the patient, confirming standby mode or 25% light intensity, and maintaining the endoscope connected to the fiber optic cable at all times.

Agreement between fiber optic and optoelectronic systems for quantifying sagittal plane spinal curvature in sitting

Spinal posture affects how individuals function from a manual wheelchair. There is a need to directly quantify spinal posture in this population to ultimately improve function. A fiber optic system, comprised of an attached series of sensors, is promising for measuring large regions of the spine in individuals sitting in a wheelchair. The purpose of this study was to determine the agreement between fiber optic and optoelectronic systems for measuring spinal curvature, and describe the range of sagittal plane spinal curvatures in natural sitting. Able-bodied adults (n = 26, 13 male) participated. Each participant assumed three sitting postures: natural, slouched (accentuated kyphosis), and extension (accentuated lordosis) sitting. Fiber optic (ShapeTape) and optoelectronic (Optotrak) systems were applied to the skin over spinous processes from S1 to C7 and used to measure sagittal plane spinal curvature. Regions of kyphosis and lordosis were identified. A Cobb angle-like method was used to quantify lordosis and kyphosis. Generalized linear model and Bland-Altman analyses were used to assess agreement. A strong correlation exists between curvature values obtained with Optotrak and ShapeTape (R(2) = 0.98). The mean difference between Optotrak and ShapeTape for kyphosis in natural, extension, and slouched postures was 4.30° (95% LOA: -3.43 to 12.04°), 3.64° (95% LOA: -1.07 to 8.36°), and 4.02° (95% LOA: -2.80 to 10.84°), respectively. The mean difference for lordosis, when present, in natural and extension postures was 2.86° (95% LOA: -1.18 to 6.90°) and 2.55° (95% LOA: -3.38 to 8.48°), respectively. In natural sitting, the mean ± SD of kyphosis values was 35.07 ± 6.75°. Lordosis was detected in 8/26 participants: 11.72 ± 7.32°. The fiber optic and optoelectronic systems demonstrate acceptable agreement for measuring sagittal plane thoracolumbar spinal curvature.