Korean J Radiol.  2014 Feb;15(1):161-168. 10.3348/kjr.2014.15.1.161.

Time-of-Flight Magnetic Resonance Angiography for Follow-Up of Coil Embolization with Enterprise Stent for Intracranial Aneurysm: Usefulness of Source Images

• Cho YD
• Kim KM
• Lee WJ
• Sohn CH
• Kang HS
• Kim JE
• Han MH

• KMID: 1711493
• DOI: http://doi.org/10.3348/kjr.2014.15.1.161

Abstract

OBJECTIVE
The aim of this study was to determine the interobserver and intermodality agreement in the interpretation of time-of-flight (TOF) MR angiography (MRA) for the follow-up of coiled intracranial aneurysms with the Enterprise stent.
MATERIALS AND METHODS
Two experienced neurointerventionists independently reviewed the follow-up MRA studies of 40 consecutive patients with 44 coiled aneurysms. All aneurysms were treated with assistance from the Enterprise stent and the radiologic follow-up intervals were greater than 6 months after the endovascular therapy. Digital subtraction angiography (DSA) served as the reference standard. The degree of aneurysm occlusion was determined by an evaluation of the maximal intensity projection (MIP) and source images (SI) of the TOF MRA. The capability of the TOF MRA to depict the residual flow within the coiled aneurysms and the stented parent arteries was compared with that of the DSA.
RESULTS
DSA showed stable occlusions in 25 aneurysms, minor recanalization in 8, and major recanalization in 11. Comparisons between the TOF MRA and conventional angiography showed that the MIP plus SI had almost perfect agreement (kappa = 0.892, range 0.767 to 1.000) and had better agreement than with the MIP images only (kappa = 0.598, range 0.370 to 0.826). In-stent stenosis of more than 33% was observed in 5 cases. Both MIP and SI of the MRA showed poor depiction of in-stent stenosis compared with the DSA.
CONCLUSION
TOF MRA seemed to be reliable in screening for aneurysm recurrence after coil embolization with Enterprise stent assistance, especially in the evaluation of the SI, in addition to MIP images in the TOF MRA.

Keyword

Aneurysm; Coiling; Embolization; Stent; MRA

MeSH Terms

Angiography, Digital Subtraction/methods
Cerebral Angiography/methods
Embolization, Therapeutic/instrumentation/*methods
Female
Follow-Up Studies
Humans
Intracranial Aneurysm/diagnosis/radiography/*therapy
Magnetic Resonance Angiography/*methods
Male
Middle Aged
Observer Variation
Recurrence
Reference Standards
*Stents

Figure

• 

  Fig. 1 Examples of angiographic interpretation.Degree of coiled aneurysmal stability was classified as stable occlusion (A), minor recanalization (B), and major recanalization (C).

• 

  Fig. 2 Exemplary case of major recanalization.A. Cerebral angiography after coil embolization using Enterprise stent for paraclinoid internal carotid artery aneurysms showed neck remnant with small size. B. In TOF MRA performed at 6 month follow-up examination, MIP image did not show any flow within coiled aneurysm (arrow indicates stented parent artery). C. However, some flow within aneurysmal sac was suspected in source image (arrowhead indicates recanalized portion). D. Conventional angiography showed aneurysm to be visibly recanalized. TOF = time-of-flight, MRA = MR angiography

• 

  Fig. 3 Exemplary case of mismatched interpretation.One-year follow-up angiography showed major recanalization of coiled aneurysm in distal internal carotid artery (A). However, MIP (B) and source image (C) of TOF MRA failed to show any flow within aneurysm (arrows indicate coiled aneurysm). This was in contrast to source image of pre-embolization MRA (D) (arrowhead indicates untreated aneurysm). TOF = time-of-flight, MRA = MR angiography, MIP = maximal intensity projection

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