First Human Experience with Directly Image-able Iodinated Embolization Microbeads

Abstract

Purpose: To describe first clinical experience with a directly image-able, inherently radio-opaque microspherical embolic agent for transarterial embolization of liver tumors.

Methodology: LC Bead LUMI™ is a new product based upon sulfonate-modified polyvinyl alcohol hydrogel microbeads with covalently bound iodine (~260 mg I/ml). 70-150 μ LC Bead LUMI™ iodinated microbeads were injected selectively via a 2.8 Fr microcatheter to near complete flow stasis into hepatic arteries in three patients with hepatocellular carcinoma, carcinoid, or neuroendocrine tumor. A custom imaging platform tuned for LC LUMI™ microbead conspicuity using a cone beam CT (CBCT)/angiographic C-arm system (Allura Clarity FD20, Philips) was used along with CBCT embolization treatment planning software (EmboGuide, Philips).

Results: LC Bead LUMI™ image-able microbeads were easily delivered and monitored during the procedure using fluoroscopy, single-shot radiography (SSD), digital subtraction angiography (DSA), dual-phase enhanced and unenhanced CBCT, and unenhanced conventional CT obtained 48 h after the procedure. Intra-procedural imaging demonstrated tumor at risk for potential under-treatment, defined as paucity of image-able microbeads within a portion of the tumor which was confirmed at 48 h CT imaging. Fusion of pre- and post-embolization CBCT identified vessels without beads that corresponded to enhancing tumor tissue in the same location on follow-up imaging (48 h post).

Conclusion: LC Bead LUMI™ image-able microbeads provide real-time feedback and geographic localization of treatment in real time during treatment. The distribution and density of image-able beads within a tumor need further evaluation as an additional endpoint for embolization.

Keywords: Embolization; Hepatic; Image-able.

Figures

Fig. 1

Patient 1: T2-weighted fat saturation MRI image (left) showing multiple hepatic metastases. Dual-phase CBCT, arterial phase (middle), and parenchymal phase (right), showing arterial anatomy and large confluent masses (yellow arrows) in segments VI and VII

Fig. 2

Patient 1: 3D dynamic roadmap displayed on fluoroscopy after dual-phase CBCT, target volume segmentation, automatic feeding vessel detection, and selective microcatheterization

Fig. 3

Patient 1: SSD showing retained LUMI™ microbeads (yellow arrows)

Fig. 4

Patient 1: dual-view fusion of final CBCT with beads (red) overlaid on arterial non-selective CBCT (blue) clearly identifies the vascular regions targeted by the LC Bead LUMI™ injections

Fig. 5

Patient 1: final post-embolization MIP CBCTs acquired just after the completion of embolization (left) and then 10 min later (right). In the yellow, zoomed, thin MIP slabs, the less dense perivascular blush of contrast (red arrows) washes out over time, while the higher density vessels filled with microbeads remain unchanged

Fig. 6

Patient 1: 10-min post-embolization CBCT (left) shows perivascular cloud-like contrast which continues to clear or wash out by the 48 h standard unenhanced CT (right). Some of this difference is also accounted for by the higher spatial resolution and iodine detection sensitivity of CBCT versus standard CT

Fig. 7

Patient 2: dominant segment IV lesion (yellow arrow) identified on axial contrast-enhanced MRI (left), late arterial phase conventional CT (middle), and common hepatic artery DSA prior to embolization (right)

Fig. 8

Patient 2: pre-embolization arterial phase (left) and parenchymal phase (right) dual-phase CBCT showing target lesion in segment IV (yellow arrows)

Fig. 9

Patient 2: emboguide image showing segmented target tumor and feeding vessels (left) and feeding arteries superimposed on live fluoroscopic image during selective catheterization (right)

Fig. 10

Patient 2: dual-view image of fused pre-embolization CBCT with intra-arterial contrast and post-embolization CBCT. Blue color indicates patent vessels prior to embolization, while red overlay documents the presence of LC LUMI™ microbeads. Yellow arrow points to tumor vessel which has failed to accumulate embolization microbeads

Fig. 11

Patient 2: dual-view fused MIP demonstrating the tumor vessel without LC LUMI™ microbeads (yellow arrow) identified in Fig. 10

Fig. 12

Patient 2: pre- and post-contrast CT obtained 48 h after LC LUMI™ embolization reveals a tumor zone with a paucity of microspheres (left, yellow arrow) and corresponding persistent perfused, viable tumor (right, yellow arrow). This viable tumor corresponds to the tumor vessel in Fig. 10 which failed to accumulate microbeads

Fig. 13

Patient 3: emboguide image showing segmented target tumor (blue outline) and autodetected feeding vessels (curvilinear colored lines) in multiple projections

Fig. 14

Patient 3: coronal non-contrast MIP CBCT image during embolization showing microbeads throughout the majority of the dominant tumor

Fig. 15

Patient 3: DSA post-embolization demonstrates subtraction artifact from the embolization microbeads and persistent enhancement (yellow arrow) in the inferior and posterior dominant tumor mass

Fig. 16

Patient 3: Non-contrast (left) and post-contrast (right) CT 48 h after LC LUMI™ embolization reveals an inferior tumor zone with a paucity of microspheres (left, yellow arrow) and corresponding persistent, perfused, and viable inferior tumor (right, yellow arrow)