Will Fluoroscopic Follow-up after Stent-Assisted Coiling of Cerebral Aneurysms Provide Information on Recanalization?

Abstract

Fluoroscopic images for comparison (FICs) can be easily obtained for follow-up on an outpatient basis. This study retrospectively assessed the diagnostic performance of a set of FICs for evaluation of recanalization after stent-assisted coiling, with digital subtraction angiography (DSA) as the reference standard. A total of 124 patients harboring 144 stent-assisted coiled aneurysms were included. At least one month postembolization they underwent follow-up angiograms comprising a routine frontal and lateral DSA and a working-angle DSA. For analysis, FICs should be compared with the mask images of postprocedural DSAs to find recanalization. Instead of FIC acquisition, the mask images of follow-up DSAs were taken as a substitute because of the same view-making processes as FICs, full availability, and perfect coincidence with follow-up DSAs. Two independent readers evaluated a set of 169 FICs and DSA images for the presence of recanalization one month apart. Sensitivity, specificity, and interreader agreement were determined. Recanalization occurred in 24 (14.2%) cases. Of these, nine (5.3%) cases were found to have significant recanalization in need of retreatment. Sensitivity and specificity rates were 79.2% (19 of 24) and 95.9% (139 of 145) respectively for reader 1, and 66.7% (16 of 24) and 97.9% (142 of 145) for reader 2. Minimal recanalization was identified in seven out of all eight false negative cases. Excluding minimally recanalized cases in no need for retreatment from the recanalization group, calculation resulted in high sensitivity and specificity of over 94% for both readers. Interreader agreement between the two readers was excellent (96.4%; κ = 0.84). FICs may be a good imaging modality to detect significant recanalization of stent-assisted coiled aneurysms.

Keywords: embolization; fluoroscopy; follow-up studies; intracranial aneurysm; intracranial stent.

Figure 1

A true-positive case of recanalization needing retreatment after repeat embolization of a giant aneurysm. Both working-angle angiograms preembolization (A) and postembolization (B) are given to provide anatomic information when FICs are evaluated. A large recanalized sac is well demonstrated and packed with stent-assisted coiling (black arrows). A mask image of working-angle completion DSA (C) is sequentially compared with the mask images of follow-up DSAs, a substitute for FICs. A set of FICs consists of a working-angle FIC and a routine frontal FIC (not shown) and/or a lateral FIC (not shown). D) At 4 months, there is a finding of recanalization, loosening of the coil mass (white arrows), which was agreed by both readers. E) At 8 months, no change in the coil mass is found in this image, but frontal FIC demonstrates aggravated loosening (not shown), which was missed by one reader, leading both readers to disagree on recanalization. Angiograms at 4 months (F) and 8 months (G), the reference standard, confirm recanalization with respective new and increased contrast filling in the aneurysm (open arrows). Each recanalization was thought to need retreatment by both readers.

Figure 1

A true-positive case of recanalization needing retreatment after repeat embolization of a giant aneurysm. Both working-angle angiograms preembolization (A) and postembolization (B) are given to provide anatomic information when FICs are evaluated. A large recanalized sac is well demonstrated and packed with stent-assisted coiling (black arrows). A mask image of working-angle completion DSA (C) is sequentially compared with the mask images of follow-up DSAs, a substitute for FICs. A set of FICs consists of a working-angle FIC and a routine frontal FIC (not shown) and/or a lateral FIC (not shown). D) At 4 months, there is a finding of recanalization, loosening of the coil mass (white arrows), which was agreed by both readers. E) At 8 months, no change in the coil mass is found in this image, but frontal FIC demonstrates aggravated loosening (not shown), which was missed by one reader, leading both readers to disagree on recanalization. Angiograms at 4 months (F) and 8 months (G), the reference standard, confirm recanalization with respective new and increased contrast filling in the aneurysm (open arrows). Each recanalization was thought to need retreatment by both readers.

Figure 2

A false negative case associated with minimal recanalization. Compared with a working-angle angiogram preembolization (A), the same view postembolization (B) clearly shows complete occlusion of the aneurysm. C) A mask image of working-angle completion DSA shows the coil mass and proximal and distal markers of a Neuroform stent (arrowheads). D) A corresponding FIC at 4 months demonstrates no finding of recanalization, but a working-angle angiogram (E) reveals minimal recanalization (open arrow) in no need for retreatment.

Figure 2

A false negative case associated with minimal recanalization. Compared with a working-angle angiogram preembolization (A), the same view postembolization (B) clearly shows complete occlusion of the aneurysm. C) A mask image of working-angle completion DSA shows the coil mass and proximal and distal markers of a Neuroform stent (arrowheads). D) A corresponding FIC at 4 months demonstrates no finding of recanalization, but a working-angle angiogram (E) reveals minimal recanalization (open arrow) in no need for retreatment.

Figure 3

A false positive case with protruded coils put back to the aneurysm orifice over time. Compared with a working-angle angiogram preembolization (A), the same view postembolization (B) demonstrates protruded coils (white arrow) towards the arterial lumen through or beneath stent struts. A stent-assisted coiled contralateral Pcom aneurysm is also shown (black arrow). A mask image of working-angle DSA on procedural completion (C) shows the coil mass (white arrow). The same view at 9 months (D) reveals coil loosening and compaction (arrowhead), but both readers made different decisions on recanalization. A working-angle angiogram at 9 months (E) shows complete occlusion of the aneurysm with the protruded coils put back to the aneurysm orifice (arrowhead).

Figure 3

A false positive case with protruded coils put back to the aneurysm orifice over time. Compared with a working-angle angiogram preembolization (A), the same view postembolization (B) demonstrates protruded coils (white arrow) towards the arterial lumen through or beneath stent struts. A stent-assisted coiled contralateral Pcom aneurysm is also shown (black arrow). A mask image of working-angle DSA on procedural completion (C) shows the coil mass (white arrow). The same view at 9 months (D) reveals coil loosening and compaction (arrowhead), but both readers made different decisions on recanalization. A working-angle angiogram at 9 months (E) shows complete occlusion of the aneurysm with the protruded coils put back to the aneurysm orifice (arrowhead).