Aortic aneurysmal disease has potentially devastating and life-threatening consequences requiring surgical intervention. There is an increasing preference for endovascular aortic repair (EVAR) over open repair. One well known complication of EVAR is endoleaks, which can lead to sac pressurization and subsequent sac expansion, rendering the previously treated aneurysm at risk of rupture. As this can occur at any time, there is a recommendation for life-long surveillance and treatment. In particular, the greatest challenge is the differentiation of endoleak type and location, which significantly impacts the treatment algorithm. Diagnosis of endoleak is often challenging with respect to the differentiation of endoleak type and location, thereby affecting treatment. Subtraction and iodine mapping is a new application of single source computed tomography (CT) technology that has the potential to be used as an alternative diagnostic tool for endoleak. It is well described in the diagnosis of vascular pathology in the lungs such as pulmonary embolism. This study explores the utility of iodine mapping as a tool for the diagnosis and management of endoleak as an alternative to traditional multiphase CT angiography, dual-energy CT, and ultrasound.

We conducted a pilot study using iodine mapping of subtraction CT technology compared to other diagnostic modalities such as traditional multiphase CT angiography, and dual energy CT for the detection of endoleak. A literature review was conducted, and our search parameters were extended across Embase and Medline.

Pulmonary perfusion studies have demonstrated that single-source subtraction CT is as efficacious as dual-energy source for iodine map reconstruction. Dual-energy CT has been demonstrated to yield similar sensitivity and specificity, with lower radiation exposure when compared to traditional multiphase CT. A study using phantom models have demonstrated reduced contrast-to-noise ratio in the single-source subtraction imaging compared to dual-energy CT. In addition, contrast boost techniques have also demonstrated efficacy in endoleak detection compared to conventional multiphase CT angiography. Subtraction iodine mapping offers improved parameters such as reduced iodinated contrast burden, radiation dose and cost effectiveness compared to other CT modalities.

Subtraction with iodine mapping from a single-source CT has the potential to be an alternative imaging modality for identification and interrogation of endoleaks. There are limited studies on the detection of endoleak utilising iodine mapping for diagnosis. Our pilot study demonstrates the benefits of this modality in the investigation of endoleaks following EVAR. Further validation studies comparing iodine mapping to current gold standard of multi-phase CT would provide robust data on efficacy of iodine mapping for the detection of endoleaks after EVAR.

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