Optimizing contrast-enhanced cone-beam CT protocol to facilitate simultaneous visualization of neurovascular pathologies and surrounding structures of interest

Abstract

<jats:sec><jats:title>Objective</jats:title><jats:p> Contrast-enhanced cone-beam computed tomography (CBCT) imaging is commonly used for evaluating neurovascular stents and their relationship to the parent artery or vascular pathologies such as arteriovenous malformations (AVMs) and dural arteriovenous fistulas (dAVFs) in the context of surrounding anatomical structures. The purpose of this study was to understand the effects of varying concentrations of contrast medium used in CBCT imaging for optimal visualization of various endovascular devices and anatomical pathologies. </jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p> Thirty-five patients with various neurovascular pathologies were included in the study. Contrast-enhanced CBCT images (20 s DR, Siemens syngo DynaCT, Siemens AG, Forchheim, Germany) were acquired in all cases, with varying dilutions of contrast medium, from 1% to 30%. The injection rate was kept constant at 3 cc/sec with an X-ray delay of two sec, and a total volume of 66 cc of diluted contrast was administered. Results from visual and quantitative analysis were reported. </jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p> Ten percent dilution of contrast medium resulted in the best image differentiation between flow-diverter devices and the parent artery. Concentrations as low as 2.5% contrast medium also resulted in identifying AVMs in the context of the surrounding brain parenchyma, whereas 20% to 30% dilution provided the best visualization of residual AVMs with prior Onyx embolization and dAVFs in the presence of bony structures. </jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p> Simultaneous visualization of brain parenchyma, bony structures, devices, and pathological anatomy using contrast-enhanced CBCT imaging is feasible with appropriate doses of iodinated contrast, and should be tailored to the individual case based on the goals of CBCT. </jats:p></jats:sec>

A technical note on intra-arterial cone-beam computed tomography for the evaluation of flow-diverter stents: Image quality differences between diluted and non-diluted contrast medium

“…3 Different percentages of contrast dilution ranging 10%-20% (10%-20% contrast media/80%-90% saline) have been adopted to avoid excess opacification of the parent vessel that may otherwise hamper proper visualization of the FD. 5,6 However, these injection parameter recommendations in the literature are derived rather empirically, and there is need for more studies to quantify the effects of different contrast concentration on the quality of CBCT for neurological applications. 5 In this technical note, we obtained contrastenhanced CBCT images using both diluted contrast and non-diluted contrast injection in the same patient population at different follow-up periods.…”

“…3 Cone-beam computed tomography (CBCT) offers higher spatial resolution that can be used as a method for the evaluation of stent deployment, wall apposition during treatment, and in-stent stenosis at follow-ups. 4,5 Higher spatial resolution comes at the expense of contrast resolution, and simultaneous visualization of the stent, arterial lumen, and vessel wall requires optimal dilution and timing of contrast medium during image acquisition. 5 However, contrast dilution ratios and injection parameters used in the literature have been determined rather empirically.…”

“…4,5 Higher spatial resolution comes at the expense of contrast resolution, and simultaneous visualization of the stent, arterial lumen, and vessel wall requires optimal dilution and timing of contrast medium during image acquisition. 5 However, contrast dilution ratios and injection parameters used in the literature have been determined rather empirically. 5,6 There are only limited data on the effects of different contrast dilutions on CBCT image quality in neurological applications.…”

“…5 However, contrast dilution ratios and injection parameters used in the literature have been determined rather empirically. 5,6 There are only limited data on the effects of different contrast dilutions on CBCT image quality in neurological applications. In most studies, 10% to 20% diluted contrast (10%-20% contrast medium mixed with 80%-90% saline) have been utilized.…”

“…In most studies, 10% to 20% diluted contrast (10%-20% contrast medium mixed with 80%-90% saline) have been utilized. 5,6 Direct contrast medium injection without any dilution was reported in a single study. 7 In angiography suites with single-head injector, CBCT with diluted contrast requires preparation and installation of diluted contrast to the injector in the midst of the procedure, adding a time delay to the procedure and requires an additional rather inconvenient step to perform.…”