Radiation Awareness for Endovascular Abdominal Aortic Aneurysm Repair in the Hybrid Operating Room. An Instant Patient Risk Chart for Daily Practice.

PURPOSE: To determine which patient and C-arm characteristics are the strongest predictors of intraoperative patient radiation dose rates (DRs) during endovascular aneurysm repair (EVAR) procedures and create a patient risk chart. METHODS: A retrospective analysis was performed of 74 EVAR procedures, including 16,889 X-ray runs using fixed C-arm imaging equipment. Four multivariate log-linear mixed models (with patient as a random effect) were constructed. Mean air kerma DR (DRAK, mGy/s) and the mean dose area product DR (DRDAP, mGycm2/s) were the outcome variables utilized for fluoroscopy as differentiated from digital subtraction angiography (DSA). These models were used to predict the maximum radiation duration allowed before a 2-Gy skin threshold (for DRAK) or a 500-Gycm2 threshold (for DRDAP) was reached. RESULTS: The strongest predictor of DRAK and DRDAP for fluoroscopy imaging was the radiation protocol, with an increase of 200% when changing from "low" to "medium" and 410% from "low" to "normal." The strongest predictors of DRAK and DRDAP for DSA were C-arm angulation, with an increase of 47% per 30° of angulation, and body mass index (BMI), with an increase of 58% for every 5-point increase in BMI. Based on these models, a patient with a BMI of 30 kg/m2, combined with 45° of rotation and a field size of 800 cm2 in the medium fluoroscopy protocol has a predicted DRAK of 0.39 mGy/s (or 85.5 minutes until the 2-Gy skin threshold is reached). While using comparable settings but switching the acquisition to a DSA with a "2 frames per second" protocol, the predicted DRAK will be 6.6 mGy/s (or 5.0 minutes until the 2-Gy threshold is reached). CONCLUSION: X-ray radiation DRs are constantly fluctuating during and between patients based on BMI, the protocols, C-arm position, and the image acquisitions that are used. An instant patient risk chart visualizes these radiation dose fluctuations and provides an overview of the expected duration of X-ray radiation, which can be used to predict when follow-up dose thresholds are reached during abdominal endovascular procedures.

AlluraClarity Radiation Dose-Reduction Technology in the Hybrid Operating Room During Endovascular Aneurysm Repair.

PURPOSE: To evaluate the effect of radiation dose reduction with the Allura ClarityIQ image processing technology for fixed C-arms in comparison with a mobile C-arm and an Allura fixed C-arm without ClarityIQ technology during endovascular aneurysm repair (EVAR) procedures. METHODS: Radiation dose data from 85 patients (mean age 74.2±7.8 years; 68 men) undergoing EVAR with mobile and fixed C-arm fluoroscopy were retrospectively analyzed. The radiation dose parameters included the kerma area product (KAP), fluoroscopic time (FT), and number of digital subtraction angiography (DSA) frames (FrDSA). KAPtotal consisted of KAPfluoro (KAP for fluoroscopic imaging) and KAPDSA (KAP for DSA and single shots). Linear regression analysis was used to explore differences in the association of KAP with the FT, FrDSA, and body mass index (BMI) among the 3 C-arms. RESULTS: The mean KAPtotal values for mobile, Allura C-arm, and AlluraClarity C-arm for noncomplex EVARs were 56±39, 245±142, and 157±120 Gy·cm(2) (p<0.001); for complex EVARs, the values were 110±43, 874±653, and 598±319 Gy·cm(2) (p<0.001), respectively. On average, KAPfluoro tripled when the mobile C-arm was replaced by the fixed C-arm. There were no significant differences in the KAPfluoro adjusted for the FT between Allura and AlluraClarity (p=0.69). However, there was a major 61% reduction in KAPDSA from 1.36 Gy·cm(2) per DSA frame for Allura to 0.54 Gy·cm(2) per DSA frame with AlluraClarity (p=0.03). For the mobile C-arm, BMI was not associated with KAP (p=0.13). The associations of BMI with KAPfluoro and KAPDSA were significant for both fixed C-arms but were more robust for Allura compared to AlluraClarity (p=0.02 for KAPfluoro and p<0.001 for KAPDSA). CONCLUSION: Changing a mobile C-arm for a fixed C-arm in a hybrid operating suite increased the average intraoperative dose during EVAR. Upgrading the Allura fixed C-arm with ClarityIQ technology resulted in a 61% reduction in the radiation per DSA frame.

Novel C-arm-based planning robotic spinal surgery in a cadaver model using quantitative accuracy assessment methodology.

BACKGROUND: This preclinical study emulating the clinical environment quantitatively analysed the accuracy of pedicle screw insertion using a navigated robotic system. METHODS: Pedicle screws were placed from T7 to L5 in the whole-body form of a cadaver. After the insertion of multiple artificial markers into each vertebra, errors between the planned insertion path and the inserted screw were quantified using the Gertzbein-Robbins system (GRS) and offset calculation. RESULTS: A total of 22 screws were placed. Almost all (95.45% [21/22]) were classified as GRS A or B, while one (4.55%) was GRS C. The mean and standard deviations of entry, tip, and angular offset were 1.78 ± 0.94 mm, 2.30 ± 1.01 mm, and 2.64 ± 1.05°, respectively. CONCLUSIONS: This study demonstrated that pedicle screw insertion using a navigated robotic system had high accuracy and safety. A future clinical study is necessary to validate our findings.

Clinico-Radio-Histopathological Correlation by C-Arm Image-Guided Biopsy in Spinal Tuberculosis.

BACKGROUND/PURPOSE OF THE STUDY: C-arm-guided biopsy is a safe and effective technique for evaluating TB spine and is useful in planning therapy. The purpose of this study was to find a correlation between clinically and radiologically suspected TB spine and C-arm image-guided biopsy-proven cases and to study the complications encountered. METHODS: After evaluating the clinical, laboratory, X-ray and MRI findings, 92 patients with provisionally diagnosed tubercular spine were subjected to C-arm image-guided biopsy. RESULTS: Among our 92 cases, histopathology was positive in 55 cases (59.78%). Out of these 55 histologically positive cases, CBNAAT was positive in 42 cases and negative in the rest 13 cases. Overall, among the 92 cases, CBNAAT was positive in 51(55.43%) of cases, and out of these, histopathology turned out to be positive in 42 of cases. Out of 41 cases with negative CBNAAT, histopathology was suggestive of tuberculosis in 13. The strength of agreement between CBNAAT and histopathology was statistically significant (p < 0.0001; kappa = 0.511). No complication such as bleeding, nerve/cord injury, infection, injury to aorta or pneumothorax was encountered during and after the C-arm biopsy in any case. CONCLUSION: C-arm image-guided biopsy is reasonably accurate and should be used as a tool for diagnosis of TB spine. We recommend histopathological examination as a key component for the diagnosis of TB spine, as it is precise and consumes relatively shorter time. CBNAAT is more rapid but is not a substitute for histopathology for spine TB diagnosis.