Identification of Factors Influencing Cumulative Long-Term Radiation Exposure in Patients Undergoing EVAR

Safe Follow-Up after Endovascular Aortic Repair with Unenhanced MRI: The SAFEVAR Study

We aimed to investigate whether unenhanced magnetic resonance imaging (MRI) could represent a safe and highly sensitive tool for endoleak screening in patients treated with endovascular aneurysm repair (EVAR) using computed tomography angiography (CTA) as a reference standard. Patients who underwent CTA for EVAR follow-up at our institution were prospectively enrolled. All MRI examinations were performed with a 1.5 T unit. The true-FISP and HASTE sequences of the MRI scans were assessed for the presence of hyperintensity within the aneurysm sac outside the graft, whereas phase-contrast through-plane sequences were used for blood flow quantification. We included 45 patients, 5 (11%) of whom were female. The median age was 73 years (IQR 68−78 years). Among our patients, 19 (42%) were positive for endoleaks at CTA, of whom 13 (68%) had type II endoleaks and 6 (32%) had type I endoleaks. There were no significant differences in age, sex, aneurysm type, prosthesis type, or contrast-to-noise ratio between hyperintensity and thrombus between patients with and without endoleaks (p > 0.300). The combined evaluation of true-FISP and HASTE yielded 100% sensitivity (95% CI: 79−100%) and 19% specificity (95% CI: 7−40%). Patients with a positive CTA had a median thrombus flow of 0.06 L/min (IQR 0.03−0.23 L/min), significantly greater than that of patients with a negative CTA (p = 0.007). Setting a threshold at 0.01 L/min, our MRI protocol yielded 100% sensitivity, 56% specificity, and an AUC of 0.76 (95% CI 0.60−0.91). In conclusion, unenhanced MRI has perfect sensitivity for endoleak detection, although with subpar specificity that could be improved with phase-contrast flow analysis.

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.

New predictors of aneurysm sac behavior after endovascular aortic aneurysm repair

OBJECTIVES

This study aimed to identify new predictors of sac behavior after endovascular aortic aneurysm repair (EVAR) and to investigate whether sac behavior is associated with long-term clinical outcomes.

METHODS

A total of 168 patients undergoing successful EVAR for abdominal aortic aneurysms with CTA follow-up of at least 1 year were included. Predictors of aneurysm sac behavior and its impact on long-term clinical outcomes were retrospectively analyzed.

RESULTS

According to sac behavior, eligible patients were stratified into the sac regression group (n = 79, 47.0%) and the sac non-regression group (n = 89, 53.0%). Patients in the regression group were younger (p = 0.036) and more likely to take sarpogrelate hydrochloride postoperatively (p = 0.011) than those in the non-regression group. The incidence of postimplantation syndrome (PIS) was significantly higher in the regression group (p = 0.005). On multivariate analysis, sac regression was more likely to occur in those with PIS (hazard ratio [HR], 1.68; 95% confidence interval [CI], 1.07-2.64; p = 0.023) and less likely to occur in those with transient type II endoleaks (HR, 0.43; 95% CI, 0.20-0.95; p = 0.037) and higher thrombus density within the sac on follow-up CTA (HR, 0.97; 95% CI, 0.95-0.99; p = 0.013). Non-regression of the sac was associated with significantly higher rates of re-intervention during the follow-up period (p = 0.001).

CONCLUSIONS

In addition to type II endoleaks, PIS and thrombus density are new predictors of aneurysm sac behavior, and sac regression is significantly associated with lower rates of re-intervention.

KEY POINTS

• After endovascular aortic aneurysm repair (EVAR), patients with sac regression were younger and more likely to take sarpogrelate hydrochloride postoperatively than those with sac non-regression. • The incidence of postimplantation syndrome (PIS) was significantly higher in patients with sac regression. • In our analysis, PIS and thrombus density within the sac were newly identified predictors of aneurysm sac behavior after EVAR.