Two-Year Follow-Up of Contrast Stasis within the Sac in Unruptured Aneurysm Coil Embolization: Progressive Thrombosis or Enlargement?

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Fig 1.
Right posterior communicating artery aneurysm with contrast stasis. A, This initial angiogram obtained immediately after coiling in a working projection during the arterial phase reveals grade 1 obliteration (packing attenuation, 30.3%) with a small neck remnant. B, This venous phase image shows medium-sized (6.8%) contrast stasis near the aneurysmal dome. C and D, Six-month follow-up CE-MRA and CE-TOF source images show the neck remnant (arrow), but no inflow into the coiled aneurysm. E, This angiogram obtained in the same working projection during the venous phase 2 years after coil embolization shows no contrast stasis.
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Fig 2.
Anterior communicating artery aneurysm with contrast stasis. A, Arterial phase angiogram obtained immediately after coil embolization in a working projection reveals grade 2 obliteration (packing attenuation, 24.5%) with a neck remnant and no contrast filling in the coil mass. B, Initial angiogram in a lateral projection during the venous phase shows a small (4.1%) amount of contrast stasis. C and D. Six-month follow-up CE-MRA and CE-TOF source images show the neck remnant (arrow), but no inflow into the coil mass. E, Venous phase lateral-projection angiogram at the 2-year follow-up shows no contrast stasis.

Table 1:

Aneurysm location patterns and prevalence of contrast stasis

Location	Total (n = 301)	No Contrast Stasis (n = 197, 65.4%)	Contrast Stasis (n = 104, 34.6%)
Internal carotid	201 (66.8%)	120 (61.0%)	81 (77.9%)
Proximal intradural or ophthalmic	131 (43.5%)	74 (37.6%)	57 (54.8%)
Posterior communicating	35 (11.6%)	22 (11.2%)	13 (12.5%)
Bifurcation	13 (4.3%)	12 (6.1%)	1 (1.0%)
Other	22 (7.3%)	12 (6.1%)	10 (9.6%)
Anterior choroidal	7 (2.3%)	7 (3.6%)	0 (0.0%)
Cavernous	14 (4.7%)	4 (2.0%)	10 (9.6%)
Cervical	1 (0.3%)	1 (0.5%)	0 (0.0%)
Anterior cerebral	34 (11.3%)	25 (12.6%)	9 (8.7%)
Anterior communicating	29 (9.6%)	23 (11.6%)	6 (5.8%)
Proximal to anterior communicating	3 (1.0%)	0 (0.0%)	3 (2.9%)
Pericallosal	2 (0.7%)	2 (1.0%)	0 (0.0%)
Middle cerebral	31 (10.3%)	28 (14.3%	3 (2.9%)
Proximal to bifurcation	8 (2.7%)	8 (4.1%)	0 (0.0%)
Bifurcation	23 (7.6%)	20 (10.2%)	3 (2.9%)
Distal to main bifurcation	0 (0.0%)	0 (0.0%)	0 (0.0%)
Posterior circulation	35 (11.6%)	24 (12.1%)	11 (10.5%)
Basilar bifurcation	17 (5.6%)	12 (6.1%)	5 (4.8%)
Basilar trunk	1 (0.3%)	1 (0.5%)	0 (0.0%)
Posterior cerebral	1 (0.3%)	1 (0.5%)	0 (0.0%)
Superior cerebellar	5 (1.7%)	3 (1.5%)	2 (1.9%)
Anterior inferior cerebellar	1 (0.3%)	1 (1.0%)	0 (0.0%)
Posterior inferior cerebellar	1 (0.3%)	1 (0.5%)	0 (0.0%)
Other	9 (3.0%)	5 (2.5%)	4 (3.8)
Vertebral	9 (3.0%)	5 (2.5%)	4 (3.8%)

Table 2:

The basic characteristics of the 2 study groups according to the occurrence of contrast stasis

Table 3:

Incidence of recanalization and retreatment according to the presence of contrast stasis

	Total	No Contrast Stasis	Contrast Stasis	PValue
Recanalization	44/301 (14.6%)	29/197 (14.7%)	15/104 (14.4%)	1.000
Size				.930
Small			3/24 (12.5%)
Medium			7/49 (14.6%)
Large			5/31 (16.1%)
Location				.540
Proximal			3/12 (25.0%)
Center			2/16 (12.5%)
Peripheral			10/76 (13.2%)
Recanalization type				.320
Neck growth	12/44 (27.3%)	10/29 (34.5%)	2/15 (13.3%)
Coil compaction	24/44 (54.5%)	14/29 (48.3%)	10/15 (66.7%)
Coil degradation	8/44 (18.2%)	5/29 (17.2%)	3/15 (20.0%)
Retreatment	11/44 (25.0%)	7/29 (24.1%)	4/15 (26.7%)	1.000