Comparison of radiation exposure and clinical outcomes between transradial and transfemoral diagnostic cerebral approaches: a retrospective study

Introduction

Cerebral angiography remains the gold standard fluoroscopic imaging procedure for diagnosing cerebrovascular diseases, and the transfemoral arterial access (TFA) has been the conventional approach. There is a growing trend to perform Diagnostic Cerebral angiogram (DCA) using the transradial arterial access (TRA) due to recent data demonstrating improved outcomes with decreased complications,1–5 ,6 ,7 8 hence a safer and more feasible alternate technique.

Despite these advantages, TRA has also been shown to be associated with longer procedural and fluoroscopy times (FTs), with increased exposure to radiation in both cerebral3 4 9 and coronary10 11 angiography studies. Efforts to minimise radiation exposure are of paramount importance because of the potential for biological effects, including skin injuries and radiation-induced cancers.12 The parameters affecting the patient radiation dose exposure and the clinical consequences are the duration of the procedure, operator experience, catheters and devices used, independent patient and vascular characteristics (lesions or anatomic variants) as well as the type of vascular approach (TRA and TFA).13 However, the studies comparing TRA versus TFA approaches have not been comprehensive and have mostly only evaluated the absorbed radiation dose as a secondary outcome variable. Also, data on quality of life (QOL)/patient satisfaction in previous studies2 5 14 has been limited to postprocedure complication rate and recovery time. In our study, we chose a globally accepted patient reported QOL outcomes scale and to our knowledge, no prior study has also analysed and compared patient-reported QOL outcomes between these two approaches at 30 days postprocedure.

This study will also seek to identify patient and procedural variables that are associated with a high radiation dose exposure and worse clinical outcomes, which will be valuable to neurointerventionalists when transitioning from TFA to a TRA.

Methods

Results

The patients’ sociodemographic information along with their clinical status and patient care type are shown in table 1. There were no significant differences between TRA and TFA groups in gender distribution, smoking and alcohol consumption, comorbid conditions and ethnicity (p > 0.05).

FT was significantly greater in TRA compared with TFA (17.2 min vs 10.5 min; p<0.001). In addition, TRA had a significantly higher total dose (298.5 mGy vs 220.3 mGy; p=0.002) and DAP (3323.6 μGym² vs 2442 μGym²; p=0.005) when compared with TFA (table 2, figure 1). Analysis of only 6-vessel DCAs also showed that TRA had a significantly higher FT, DAP and TD in comparison to TFA (table 3). Despite observing a longer FT in TRA, results showed lesser median number of vessels injected in TRA technique (TRA vs TFA; 5 vs 6, p=0.12), and a notably lower success rate in acquiring a 6-vessel DCA (TRA vs TFA; 42.4% vs 55.7%, p=0.08) using the TRA technique (table 2).

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We performed a general linear model (figure 2) to understand better the relationship between FT and other measured variables such as vessel number and age (figure 2). With every increase of 1 vessel, the FT increased by 2.2 min for TRA (p<0.001; 95% CI 1.03 to 3.36) and by 1.3 min for TFA (p<0.001; 95% CI 0.72 to 1.83). In TRA patients, there was no statistically significant relation between FT and Age, but in TFA patients every 1-year increase in age increased mean FT by 0.17 min (p<0.001; 95% CI: 0.11 to 0.24) as seen in figure 2. The adjusted model (for CVD status, 3D status, inpatient vs outpatient care, patient age, and number of vessels) also showed that on average, FT is 6.01 min longer for the TRA patients (95% CI 4.31 to 7.71 min), and total dose is 59.1 mGy higher for the TRA patients (95% CI 6.89 to 111.31 mGy).

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Our comparative analysis also showed that younger patients (<65 years) regardless of approach had more complete 6-vessel DCAs comparing to older patients (p<0.05, figure 3). Our final comparative analysis between 6 vessel DCA and <6 vessel DCA showed more comorbid CVDs in <6 v DCAs (figure 3, CVDs in 6 vessel DCA vs <6 vessel DCA; 53% vs 69%, p<0.05). The percentages of patients who received 3D were not significantly different between TRA and TFA groups, as seen in table 2. Overall, the highest radiation exposure was recorded in older patients who underwent 3D TRA angiogram, and lowest seen in younger patients who underwent TFA without 3D.

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There was no significant difference between groups in PROGHS mental and physical t-scores at 30 days postprocedure, even though our cohort showed a significantly greater percentage of TRA procedure done in the outpatient setting. (Outpatient care, TRA vs TFA; 81.8% vs 57.1%, p=0.001) (table 1).

Discussion

The TRA approach for neuroendovascular procedures has continued to gain traction over the past several years. Recent neurointerventional and cardiointerventional studies15 16 have reported higher patient and operator preference for TRA over TFA because of a wide array of benefits, including reductions in access site-related morbidity, length of stay, major bleeding and shorter time to ambulation.1–5 10 11 However, a drawback finding in our study about patient radiation dose exposure during the initial TRA-adoption phase offers an additional perspective to TRA and TFA comparative studies.

In our first comparative analysis, TRA was found to be associated with a significantly higher radiation exposure than in TFA. In our study, we only analysed diagnostic angiograms and excluded therapeutic interventions to eliminate the complexity of treatment procedures which prolonged procedure and FT. This study was also performed during our institution’s transition to a ‘radial first’ practice. Similar higher FT in TRA have been reported in comparative studies that analysed FT as a secondary variable,3 9 and others that analysed both diagnostic and therapeutic procedures together.4 9 A possible explanation for this finding is the steep learning curve which remains a significant challenge for experienced Neurointerventionalists trained initially with TFA.2 17–19 ,20 We did not study if there is a learning curve but it is presumed from these reports that after performing 30–50 cases it can be overcome with a significant decrease in FT and improved injection success rate.

Another contributing factor was the catheters used by the initial adopters in our study which were not specifically designed for the TRA. A recent national survey2 reported that neurointerventionalists would prefer modified and improved tools designed specifically for TRA, mostly because of the technical and intraoperative challenges resulting from aforementioned comorbidities, and anatomical variants associated with the transradial route13 ultimately leading to increased vascular access time.

We explored other (confounding) variables that affected FT. Considering age as one of the factors described in previous studies,3 4 13 21 we performed an additional comparative analysis in the TRA group between the elderly (>65) and younger (<65) patients. We discovered that it may be more challenging in attaining a predefined complete 6-vessel DCA in the elderly compared with their younger counterparts with a significant increase in radiation exposure as well. Our analysis also pointed to higher cardiovascular comorbidities in the elderly as another contributing factor. Other studies3 13 21 have also demonstrated age as a predictor of failed TRA because of associated sicknesses and higher incidences of pathologic/tortuous vessel morphology in the elderly (>65 years). However, it remains unclear from our study whether better techniques and tools could have led to a complete 6-vessel DCA regardless of atherosclerosis or other pathological factors.

With the number of vessels being a confounder in the elderly population affecting FT, we performed several analyses to establish this relationship. We first compared the 6-vessel DCA cohort to a less tha 6-vessel DCA which showed a greater percentage of patients in the less than 6-vessel cohort being older (>65 years) with comorbid CVD and a corresponding higher FT. Furthermore, linear modelling (figure 2) showed that with every increase of 1 vessel the FT was a minute greater in TRA comparing to TFA. To our knowledge, no prior study has examined the relationship between these confounders affecting radiation exposure.

We reported that the type of vascular approach (TRA and TFA) did not affect the 30 days post-operative PROGHS QOL outcomes even though the majority of TRA approaches were performed in the outpatient setting (table 1). We chose to use the 10-item Patient-Reported Outcomes measurement Information System GHS because it is a well-known valid and reliable scale used in assessing and tracking the impact of healthcare interventions in health and functional disability over time. This novel finding from our 30-day postprocedural PRO adds to previous literature1–5 that only reported immediate QOL outcome with the TRA approach during the postoperative phase. These studies demonstrated a higher satisfaction rate with the radial approach mainly because of a shorter recovery time likely related to postprocedural comfort and reduced hospital stay. In our study, we did not report complication rates and cross-over cases (n=3) because first, they were too few, and second, they were not our main variables of interest in this study. Numerous previous studies have compared complications rates favouring the TRA approach.1–5 10 11

Our study has some limitations. First, our study has the inherent limitations of a retrospective study. Second, we did not include therapeutic procedures in this study. Third, we were unable to assess the learning curve because our analysis was performed during the initial TRA-adoption period. Fourth, our sample size was relatively low due to the following reasons. Patients who were lost to follow-up at 30 days were not included and that may have created a type of selection bias. Another limitation was that we excluded and did not analyse crossover cases from TRA to TFA which were only a few cases. Despite the low sample size, our results were still significant, and this speaks to the major difference in radiation dose exposure between TRA and TFA.

Our study had multiple unique strengths. First, we were able to use detailed sociodemographic and hospital data including many possible confounding variables (number of vessels successfully catheterised and 3D rotational angiograms) to complete a multivariate analysis in our study. Second, we focused on only diagnostic cerebrovascular procedures, which to our knowledge has not been reported in the literature to date for in-depth comparative radiation exposure parameters analysis. Third, all DCAs were performed with only the Biplane-Siemens Artis Q catheterisation lab. Fourth, we used widely accepted scales for functionality and overall global health in clinical outcomes analysis. Fifth, our broader inclusion criteria including age, comorbid conditions and preoperative diagnosis allowed for a more representative and generalisable sample in the setting of cerebrovascular diseases to limit selection bias.

The neurointerventionalist community largely agrees that TRA improves patient comfort, and overall there is no concern about TRA’s safety for diagnostic or therapeutic interventions. However, the increased radiation dose exposure reported in our study is a substantial drawback. With the growing trend to perform TRA DCAs, future research should address better radiation dose reduction technical skills and strategies, and the development of more TRA-specific devices.

Conclusion

Adopting a TRA for DCAs may be initially associated with longer procedure times and higher radiation dose for the patient. Better strategies and tools are needed to mitigate this effect. We hope that the results of this study will provide insights into the use of TRA for DCA for early adopters especially in older patients with CVD comorbidities. Comparative radiation exposure analysis between these two approaches with newer TRA-specific devices following the ‘initial TRA-adoption’ phase should be a focus of future inquiry.