Low-Dose 4-Dimensional Computed Tomographic Angiography for Diagnosing Indeterminate Endoleak After Hybrid Arch Repair: A Case Report

AIM: To present a case in which low-dose 4-dimensional computed tomographic angiography (4D-CTA) enabled precise classification of a type II endoleak following hybrid arch repair for chronic type B aortic dissection, in the setting of inconclusive findings on conventional CTA. CASE: A 74-year-old woman underwent hybrid arch repair with left common carotid-subclavian bypass and thoracic endovascular aortic repair for chronic type B aortic dissection. Six years postoperatively, aneurysm sac enlargement was noted. Conventional CTA with a 2-phase protocol (early arterial and delayed venous phases) could not distinguish between type Ia and type II endoleaks. Low-dose 4D-CTA (dose-length product: 302.6 mGy·cm) revealed delayed contrast enhancement within the sac during the late arterial phase, consistent with a type II endoleak originating from the left subclavian artery (LSCA). Targeted coil embolization was successfully performed to resolve the endoleak, and contrast inflow from a branch of the LSCA was confirmed by intraprocedural angiography. CONCLUSION: Low-dose 4D-CTA allowed for precise classification of the endoleak and guided appropriate reintervention. This modality represents a useful and practical tool for endoleak evaluation, especially when standard imaging is inconclusive.Clinical ImpactThis case highlights the diagnostic value of 4-dimensional computed tomographic angiography (4D-CTA) in classifying endoleaks after thoracic endovascular aortic repair (TEVAR), particularly when standard CTA is inconclusive. The 4D-CTA identified a type II endoleak from the left subclavian artery, enabling definitive diagnosis and targeted coil embolization. Notably, the scan was performed using a low-dose protocol (dose-length product: 302.6 mGy·cm), substantially lower than the >1000 mGy·cm reported in prior studies while preserving diagnostic quality. Standardized low-dose 4D-CTA protocols may support broader clinical adoption for endoleak evaluation.