The effect of Fiber Optic RealShape technology on the reduction of radiation during complex endovascular surgery

OBJECTIVE

Despite the advantages that fenestrated endovascular aortic repair has over open repair, it is accompanied by the consequence of radiation exposure, which can result in long-term complications for both the patient and surgical staff. Fiber Optic RealShape (FORS) technology is a novel advancement that uses emitted light from a fiber optic wire and enables the surgeon to cannulate vessels in real time without live fluoroscopy. This technology has been implemented at select centers to study its effectiveness for cannulation of target vessels and its impact on procedural radiation.

METHODS

We collected prospective data on physician-modified endograft (PMEG) cases before and after the introduction of FORS technology. FORS PMEGs were matched with up to three conventional fluoroscopy cases by number of target vessels, inclusion of a bifurcated device below, aneurysm extent, and patient body mass index. The procedural radiation parameters were compared between these cohorts. Within the FORS cohort, we analyzed the rate of successful target vessel cannulation for all cases done with this technology (including cases other than PMEGs), and we compared the radiation between the cannulations using only FORS with those that abandoned FORS for conventional fluoroscopy.

RESULTS

Nineteen FORS PMEGs were able to be matched to 45 conventional fluoroscopy cases. Procedures that used FORS technology had significantly reduced total air kerma (527 mGy vs 964 mGy), dose area product (121 Gy∗cm2 vs 186 Gy∗cm2), fluoroscopy dose (72.1 Gy∗cm2 vs 132.5 Gy∗cm2), and fluoroscopy time (45 minutes vs 72 minutes). There was no difference in procedure length, total contrast, or digital subtraction angiography. Within FORS cases, 66% of cannulations were completed using only FORS. Cannulations using only FORS had significant reduction of navigation air kerma (5.0 mGy vs 26.5 mGy), dose area product (1.2 Gy∗cm2 vs 5.1 Gy∗cm2), and fluoroscopy time (0.6 minutes vs 2.3 minutes) compared with cannulations abandoning FORS for conventional fluoroscopy.

CONCLUSIONS

This study demonstrates the advantages of FORS for total procedural radiation as well as during individual cannulation tasks. The implementation of FORS for target vessel catheterization has the potential to decrease the total degree of radiation exposure for the patient and surgical staff during complex endovascular aortic surgeries.

Editor's Choice -- European Society for Vascular Surgery (ESVS) 2024 Clinical Practice Guidelines on the Management of Abdominal Aorto-Iliac Artery Aneurysms

OBJECTIVE

The European Society for Vascular Surgery (ESVS) has developed clinical practice guidelines for the care of patients with aneurysms of the abdominal aorta and iliac arteries in succession to the 2011 and 2019 versions, with the aim of assisting physicians and patients in selecting the best management strategy.

METHODS

The guideline is based on scientific evidence completed with expert opinion on the matter. By summarising and evaluating the best available evidence, recommendations for the evaluation and treatment of patients have been formulated. The recommendations are graded according to a modified European Society of Cardiology grading system, where the strength (class) of each recommendation is graded from I to III and the letters A to C mark the level of evidence.

RESULTS

A total of 160 recommendations have been issued on the following topics: Service standards, including surgical volume and training; Epidemiology, diagnosis, and screening; Management of patients with small abdominal aortic aneurysm (AAA), including surveillance, cardiovascular risk reduction, and indication for repair; Elective AAA repair, including operative risk assessment, open and endovascular repair, and early complications; Ruptured and symptomatic AAA, including peri-operative management, such as permissive hypotension and use of aortic occlusion balloon, open and endovascular repair, and early complications, such as abdominal compartment syndrome and colonic ischaemia; Long term outcome and follow up after AAA repair, including graft infection, endoleaks and follow up routines; Management of complex AAA, including open and endovascular repair; Management of iliac artery aneurysm, including indication for repair and open and endovascular repair; and Miscellaneous aortic problems, including mycotic, inflammatory, and saccular aortic aneurysm. In addition, Shared decision making is being addressed, with supporting information for patients, and Unresolved issues are discussed.

CONCLUSION

The ESVS Clinical Practice Guidelines provide the most comprehensive, up to date, and unbiased advice to clinicians and patients on the management of abdominal aorto-iliac artery aneurysms.

FACTORS INFLUENCING FLUOROSCOPY TIME IN ENDOVASCULAR TREATMENT OF ABDOMINAL ANEURYSMS: A RETROSPECTIVE STUDY

Patients who undergo endovascular aortic aneurysm repair (EVAR) may require prolonged radiation exposure affected by several factors. The objectives of this study were to document fluoroscopy time (FT) during EVAR and identify possible factors that influence it. A retrospective analysis of a 180 patients' database with abdominal infrarenal aortic aneurysms submitted to EVAR during a 7-y period was performed. The FT is evaluated regarding risk factors and comorbidities, graft type and patient-related, clinical and technical parameters. FT's median (interquartile range) was 1011 (698-1500) s. Excluder and C3 Excluder were associated with significantly lower FT values when compared with other grafts. Hypertension, dyslipidemia, age ≥ 70 y, maximum aneurysm diameter ≥ 6 cm and procedure duration ≥2 h resulted in higher FT values. A significantly lower FT was found for the operations performed in the 7th y of the study's period compared with the previous 6 y, mainly because of the use of Excluder or C3 Excluder grafts. However, these grafts did not show any significant difference in FT values during the 7 y. A significant correlation between FT with age and procedure duration was found. Nevertheless, procedure duration is a poor FT predictor in linear and logistic regressions, although is significantly correlated with FT. Dyslipidemia, procedure duration and graft type are independent predictors of FT larger than the median, whereas only the procedure duration is a predictor for FT larger than the 75th percentile value. The identified factors regarding radiation protection issues should be considered when contemplating abdominal aortic aneurysm repair, however, without compromising the procedure's efficacy. Further work is necessary to identify more potential anatomical, clinical and technical factors affecting procedures' complexity and FT and patient radiation dose during EVAR interventions.

Fusion imaging guidance for endovascular recanalization of peripheral occlusive disease

OBJECTIVE

Endovascular procedures are now the first line option for treatment of lower extremity arterial disease. Fusion imaging guidance has been reported to reduce radiation exposure and reintervention rates during fenestrated and branched endovascular repairs, but limited literature exists on its benefits during lower extremity arterial disease endovascular procedures, and more specifically peripheral occlusive disease (POD). This study aims to evaluate the radiation exposure and technical success benefits of fusion imaging guidance in a large cohort of patients treated endovascularly for complex POD.

METHODS

From January 2017 to September 2019, in a single center, all consecutive patients presenting symptomatic occlusions (Rutherford Baker categories 3 to 6) in the setting of POD and treated endovascularly were retrospectively assessed for inclusion. All procedures were performed under augmented fluoroscopy guidance (Vessel ASSIST, GE Healthcare), overlaying on live imaging the 3D path for transluminal recanalization based on the preoperative computed tomography angiography. Technical success, dose area product (DAP), total cumulated air kerma (CAK), and fluoroscopy time were collected. DAP results were compared with the literature.

RESULTS

During the study period, 179 patients were treated for iliac (n = 56) or femoropopliteal (n = 123) symptomatic arterial occlusions. Technical success was reported in 171 of 179 procedures (95.5%). The use of a re-entry catheter was required to achieve technical success in 11 patients (6.1%). Mean DAP and CAK were 15.44 Gy·cm² and 135 mGy, respectively, with a mean fluoroscopy time of 15.04 minutes. DAP and CAK were significantly higher in the iliac group when compared with the femoropopliteal group, although fluoroscopy time was not significantly different. DAP was lower than levels reported in the literature.

CONCLUSIONS

Routine use of fusion imaging guidance during POD endovascular treatment is associated with low radiation exposure, high technical success, and reduced need for re-entry systems.

KERMA-AREA PRODUCT, ENTRANCE SURFACE DOSE AND EFFECTIVE DOSE IN ABDOMINAL ENDOVASCULAR ANEURYSM REPAIR

This study aims to evaluate patient radiation dose during fluoroscopically guided endovascular aneurysm repair (EVAR) procedures. Fluoroscopy time (FT) and kerma-area product (KAP) were recorded from 87 patients that underwent EVAR procedures with a mobile C-arm fluoroscopy system. Effective dose (ED) and organs' doses were calculated utilising appropriate conversion coefficients based on the recorded KAP values. Entrance surface dose (ESD) was calculated based on KAP values and technical parameters. The mean FT was 22.7 min (range 6.4-76.8 min), resulting in a mean KAP of 36.6 Gy cm2 (range 2.0-167.8 Gy cm2), a mean ED of 6.2 mSv (range 0.3-28.5 mSv) and a mean ESD of 458 mGy (range 26-2098 mGy). The corresponding median values were 17.4 min, 25.6 Gy cm2, 4.4 mSv and 320 mGy. The threshold of 2 Gy for skin erythema was exceeded in two procedures for a focus-to-skin distance (FSD) of 40 cm and six procedures when an FSD of 30 cm was considered. The highest doses absorbed by the adrenals, kidneys, spleen and pancreas and ranged between 3.7 and 313.3 mGy (average 66.8 mGy), 3.3 and 285.1 mGy (average 60.8 mGy), 1.3 and 111.1 mGy (average 23.7 mGy), 1.1 and 92.1 mGy (average 19.6 mGy), respectively. A wide range of patient doses was reported in the literature. The radiation dose received by the patients was comparative or lower than most of the previously reported values. However, higher doses can be revealed due to the X-ray system's non-optimum use and extended FTs, mainly affected by complex clinical conditions, patients' body habitus and vascular surgeon experience. The large variation of patient doses highlights the potential to optimise the EVAR procedure by considering the balance between the radiation dose and the required image quality. Additional studies need to be conducted in increasing the vascular surgeons' awareness regarding patient dose and radiation protection issues during EVAR procedures.

A novel personalized dosimetry method for endovascular aneurysm repair (EVAR) procedures

OBJECTIVE

To estimate radiation doses for the primarily irradiated organs/tissues of patients subjected to standard endovascular aneurysm repair (EVAR) procedures using a novel personalized dosimetry method.

METHODS

Dosimetric and anthropometric data were collected prospectively for eight patients who underwent standard EVAR procedures. Patient-specific Monte Carlo simulations were performed to estimate organ/tissue doses from each of the fluoroscopic and digital subtraction angiography acquisitions involved in EVAR. Individual-specific cumulative absorbed doses were estimated for the skin, spinal bone marrow, heart, kidneys, liver, colon, bladder, pancreas, stomach, and spleen and compared to corresponding values estimated through a commercially available dosimetric software package that employs standardized phantoms.

RESULTS

The highest organ/tissue radiation doses from EVAR were found for the skin, spinal bone marrow, kidneys, and spleen as 192.4 mGy, 96.7 mGy, 72.9 mGy, and 33.6 mGy respectively, while the doses to the heart, liver, colon, bladder, pancreas, and stomach were 6.3 mGy, 14.4 mGy, 18.4 mGy, 14.8 mGy, 21.6 mGy, and 11.2 mGy respectively. Corresponding dose values using standardized phantoms were found to differ up to 151%.

CONCLUSION

Considerable radiation doses may be received by primarily exposed organs/tissues during standard EVAR. The specific size/anatomy of the patient and the variation in exposure parameters/beam angulation between different projections commonly involved in EVAR procedures should be taken into account if reliable organ dose data are to be derived.

KEY POINTS

• A novel patient-specific dosimetry method was utilized to estimate radiation doses to the primarily irradiated organs/tissues of patients subjected to standard endovascular aneurysm repair procedures. • The use of standardized mathematical anthropomorphic phantoms to derive organ dose from fluoroscopically guided procedures may result in considerable inaccuracies due to differences in the assumed organ position/volume/shape compared to patients.

Physician impact on use of fluoroscopy during endovascular procedures to improve radiation safety

OBJECTIVE

To determine whether differences exist in fluoroscopy time and radiation exposure during lower extremity endovascular procedures performed by fellowship trained vascular surgeons vs general surgeons, to minimize radiation exposure to operating room staff.

METHODS

A retrospective review of all lower extremity endovascular procedures was performed from August 1, 2014, to January 29, 2016. The procedures were performed by the surgical department's four surgeons with endovascular privileges: two vascular surgeons and two general surgeons. Only procedures involving lower extremity arterial angiograms with balloon angioplasty, stenting, or atherectomy were included. The operative records were reviewed for each case. The total fluoroscopy time and total radiation dose for each procedure were recorded. Procedures were grouped according to the number of endovascular interventions as one to two interventions, three to four interventions, and five or more interventions performed. Statistical analysis was performed with a P value of less than .05 considered significant.

RESULTS

About 271 lower extremity endovascular procedures were performed during the study period by 4 surgeons. The average age of the patient population was 70 years. The total number of procedures performed over the study period were 112, 45, 91, and 25 for surgeons 1 through 4, respectively. On average, 3.24 interventions were performed during each procedure. Vascular surgeons were found to have shorter fluoroscopy time for procedures involving one to two (7.8 vs 30.1; P < .01), three to four (9.3 vs 34.2; P < .01), and five or more (11.5 vs 51.9; P < .01) interventions. Vascular surgeons were also found to have less radiation exposure compared with general surgeons in procedures with one to two (1.69 vs 3.53; P = .001) and five or more (2.3 vs 5.4; P = .003) interventions. There was no significant difference in radiation exposure between vascular and general surgeons for procedures with three to four interventions (5.86 vs 5.59; P = .95).

CONCLUSIONS

In this small series at our institution, lower extremity endovascular procedures performed by specialty trained vascular surgeons were associated with both decreased operative fluoroscopy time and decreased radiation exposure when compared with general surgeons.

Editor's Choice - Comprehensive Literature Review of Radiation Levels During Endovascular Aortic Repair in Cathlabs and Operating Theatres

OBJECTIVE

Occupational exposure is a growing concern among the endovascular specialist community. Several types of imaging equipment are available, such as mobile C arms or hybrid rooms, and some have been shown to deliver higher levels of radiation. A literature review was conducted to identify studies reporting dose data during standard (EVAR) and complex abdominal aortic endovascular repair (fenestrated/branched EVAR [F/BEVAR]).

METHODS

A search of the MEDLINE and the Cochrane databases was performed by two independent investigators using the medical subject heading terms "aortic aneurysms", "radiation", and "humans" over a search period of 10 years. Studies with full text available in English and reporting radiation data independently from the imaging equipment type were included. Experimental studies were excluded.

RESULTS

The lowest dose-area product levels during EVAR and F/BEVAR were identified in hybrid rooms, while the highest were with fixed systems. When adherence to the as low as reasonably achievable principles was stipulated by the authors, dose reports tended to be among the lowest. Several studies, especially of F/BEVAR, report concerning levels of radiation for both patients and staff.

CONCLUSION

Modern imaging equipment type, team involvement with radiation management, and the support of recent imaging technologies such as fusion help to reduce the dose delivered during standard and complex EVAR. Investment in modern imaging technology should be considered in every centre providing endovascular management of aortic aneurysms.

[Monitoring Radiation Exposure During Surgery with Real Time Measurements: Opportunities and Limitations]

BACKGROUND

In Germany, staff exposed to radiation is monitored with official individual dosimeters. Commercially available real-time dosimeters (RTD) can be used as radiation protection dosimeters. They are worn over the apron and display the radiation dose being measured at the desired location at intervals of one second. These real-time radiation exposure measurements enable the surgical staff to take suitable measures to reduce the radiation during the operation. The objective of our study was to monitor the accuracy of the measurements taken from the real-time dosimeter and to determine the radiation scatter for individual members of the surgical staff.

MATERIALS AND METHODS

Prospective measurements of the operating team's exposure to radiation were carried out using a real-time dosimeter system in an operating room for vascular surgery equipped with a C-arm. Firstly the calibration of the RTD at the operating table was checked using a water phantom. Subsequently, measurements were taken during vascular interventions and surgery.

RESULTS

When calibrated, the values of the individual RTD revealed internal significant deviations, thus a corrective factor was calculated for each RTD. In total 55 interventions on 53 patients were studied. The average dose for the RTD of the surgeon during endovascular aortic repair (n = 11) amounted to 9 ± 9 µSv (range 3.6 - 50 µSv) and during thoracic endovascular aortic repair (n = 6) 35 ± 49 µSv (3.8 - 190.3 µSv). In the case of percutaneous transluminal angioplasty of the pelvis and of the lower extremities (n = 20), the average dose for the RTD of the surgeon was 7 ± 7 µSv (1.2 - 35 µSv) and for the angiographies of the lower extremities (n = 12) at 2 ± 3 µSv (0.2 - 15.9 µSv). The real-time dosimetry provided data which contributed to the operating team changing their behaviour in the operating room.

DISCUSSION

Since the dose values determined by the official dosimetry are generally very low, it is not possible to optimise the behaviour and thus the radiation protection using these dose values. This can be achieved with the radiation protection dosimeter and the dose reference levels can be defined in the new Radiation Protection Ordinance (StrlSchV). Instant feedback of the current dose rate at the place where the RTD is worn can lead to both the individual adjusting his or her personal behaviour and to optimisation of the individual's radiation protection. It is only possible to compare the measured data obtained with the RTD when calibration is carried out in advance.

Radiation Exposure During Transcatheter Valve Replacement: What Cardiac Surgeons Need to Know

BACKGROUND

Transcatheter aortic valve replacement (TAVR) and transcatheter mitral valve replacement expose operators to radiation. These procedures differ primarily in whether they are performed via a transfemoral (TF) or an alternative access (AA) approach. This study compared operator radiation exposure during transcatheter valve implantation when performed via a TF vs an AA approach, when performed in a catheterization lab vs a hybrid operating room (OR), and investigated the potential benefit of disposable shielding.

METHODS

Dosimeters were worn during TAVR-TF (n = 50) and TAVR-AA (n = 31) procedures by operators. All TAVR-AA procedures were performed in a hybrid OR and TF procedures were performed in either catheterization labs (n = 16) or a hybrid OR (n = 34). Disposable radiation shielding pads (RADPAD; Worldwide Innovations and Technologies, Inc, Kansas City) or a placebo were added in a randomized, blinded fashion.

RESULTS

Team radiation exposure was higher after TAVR-AA vs TAVR-TF (median 15.1 mRad [interquartile range: IQR 8.6, 32.4] vs 5.5 mRad [IQR 2.4, 9.8], P < .001). TAVR-TF procedures required the same amount of fluoroscopy time regardless of where they were performed (20.3 ± 7.4 min in hybrid OR vs 19.0 ± 6.4 min in catheterization lab, P = .55). However, radiation exposure for TAVR-TF remained higher when performed in a hybrid OR (median 9.0 mRad [IQR 4.5, 11.9] vs 2.2 mRad [IQR 1.3, 2.8], P < .001). Radiation exposure was greatest for TAVR-AA (median 15.1 mRad [IQR 8.6, 32.4]). The use of RADPAD did not decrease radiation exposure (median 9.0 mRad [IQR 4.5, 14.7] vs 9.4 mRad [IQR 2.8, 19.5], P = .82).

CONCLUSIONS

Procedures performed in the hybrid OR were associated with higher operator radiation exposure. In comparison with the TF approach, AA cases had the highest levels of operator radiation. This is particularly important in cases of transcatheter mitral valve replacement that can only be done via an AA approach. The use of disposable radiation shielding in this series did not attenuate operator radiation exposure. Radiation shielding within hybrid ORs should be scrutinized in an effort to remain on par with that found within catheterization labs.