Detection of Neck Recanalization with Follow-up Contrast-enhanced MR Angiography after Renal Artery Aneurysm Coil Embolization

An Update on Embolization for Pulmonary Arteriovenous Malformations

Pulmonary arteriovenous malformations are abnormal connections between a pulmonary artery and a pulmonary vein that can lead to ischemic stroke and brain abscess due to right-to-left shunting of blood. Embolization is currently considered the first treatment option for pulmonary arteriovenous malformations owing to its minimal invasiveness. This review updates the indications and techniques for the embolization of pulmonary arteriovenous malformations and determines the persistence of pulmonary arteriovenous malformations following embolization based on the most recent literature.

Contrast-enhanced magnetic resonance angiography for monitoring an embolized renal artery aneurysm: A case report and literature review

This case report describes a 69-year-old male patient with a renal artery aneurysm that was followed up with contrast-enhanced magnetic resonance angiography at 8 months after coil embolization treatment. Due to the disappearance of residual lumen with few metal artifacts, the therapeutic effect was satisfactory. At present, the indications for the treatment of renal artery aneurysms are still controversial and there are very few reports of postembolization images of renal artery aneurysms, with no criteria for reintervention and few reports for monitoring the embolized aneurysms. Further reports and research are still needed for the treatment of this rare disease.

Selective occlusion of splenic artery aneurysms with the coil packing technique: the impact of packing density on aneurysm reperfusion correlated between contrast-enhanced MR angiography and digital subtraction angiography

PURPOSE

The aim was to evaluate the relationship between coil packing densities after splenic artery aneurysm (SAA) treatment using detachable microcoils and rates of SAA reperfusion and to suggest a post-treatment surveillance protocol using contrast-enhanced MRA.

MATERIALS AND METHODS

Evaluated were 16 patients (4 men; mean age 46.7), who underwent true SAA embolization using detachable microcoils (Concerto, Medtronic). SAAs were treated by selective coil packing (CP) or stent-assisted coil exclusion (SAC). Contrast-enhanced magnetic resonance angiography (CE-MRA) and digital subtraction angiography (DSA) were performed at 3 months post-procedure and correlated.

RESULTS

Primary CP was used in 13 patients, while SAC was used in three patients. On follow-up, complete aneurysm occlusion was seen in seven patients (43.8%). Sac reperfusion occurred in nine patients (56.2%) and was demonstrated in all CE-MRA and six DSA studies. Mean aneurysm packing density was 20.10 ± 8.05% for the CP group and 32.90 ± 11.95% for the SAC group (p = 0.038). There was a significant difference in the incidence of aneurysm sac reperfusion on CE-MRA study between CP and SAC (9 vs. 0). No sac reperfusion was seen in aneurysms with packing densities ≥ 29%, irrespective of either embolization method.

CONCLUSION

Favorable midterm results for coil packing of SAAs seem to depend on the coil packing density with a coil volume approximately a quarter of the aneurysm volume being most effective. Follow-up should involve the use of CE-MRA as this modality has been shown to be superior over DSA in detecting aneurysm reperfusion and coil compaction.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Follow-up of true visceral artery aneurysm after coil embolization by three-dimensional contrast-enhanced MR angiography

PURPOSE

We aimed to evaluate the outcomes of coil embolization of true visceral artery aneurysms by three-dimensional contrast-enhanced magnetic resonance (MR) angiography.

MATERIALS AND METHODS

We used three-dimensional contrast-enhanced MR angiography, which included source images, to evaluate 23 patients (mean age, 60 years; range, 28-83 years) with true visceral artery aneurysms (splenic, n=15; hepatic, n=2; gastroduodenal, n=2; celiac, n=2; pancreaticoduodenal, n=1; gastroepiploic, n=1) who underwent coil embolization. Angiographic aneurysmal occlusion was revealed in all cases. Follow-up MR angiography was conducted with either a 1.5 or 3 Tesla system 3-25 months (mean, 18 months) after embolization. MR angiography was evaluated for aneurysmal occlusion, hemodynamic status, and complications.

RESULTS

Complete aneurysmal occlusion was determined in 22 patients (96%) on follow-up MR angiography (mean follow-up period, 18 months). Neck recanalization, which was observed at nine and 20 months after embolization, was confirmed in one of eight patients (13%) using a neck preservation technique. In this patient, a small neck recanalization covered by a coil mass was demonstrated. The complete hemodynamic status after embolization was determined in 21 patients (91%); the visualization of several collateral vessels, such as short gastric arteries, after parent artery occlusion was poor compared with that seen on digital subtraction angiography in the remaining two patients (9%). An asymptomatic localized splenic infarction was confirmed in one patient (4%).

CONCLUSION

Our study presents the follow-up results from three-dimensional contrast-enhanced MR angiography, which confirmed neck recanalization, the approximate hemodynamic status, and complications. This effective and less invasive method may be suitable for serial follow-up after coil embolization of true visceral aneurysms.

Triaxial system in re-embolization for recanalization of pulmonary arteriovenous malformations

Background

Recanalization occurs occasionally, following coil embolization of pulmonary arteriovenous malformations (PAVM), and can lead to ischemic stroke; therefore re-embolization is important. A 1.9-Fr. no-taper microcatheter that can be inserted into a 2.7-Fr. microcatheter (named the triaxial system) has recently become available, and contributes to super-selective catheterization for small or tortuous vessels. The aim of this study was to evaluate the usefulness of re-embolization for recanalization of PAVM using the triaxial system.

Material/Methods

Recanalization was diagnosed in 8 patients with 13 PAVMs between June 2011 and November 2012, and re-embolization was attempted with a conventional microcatheter at first in all 13 PAVMs. However, in three of them it failed with the conventional microcatheter, and then the system was exchanged to the triaxial system. Thus, re-embolization using the triaxial system was performed in 3 PAVMs of 3 female patients, with a median age of 63 years (range, 46–73 years). We assessed technical success, complications, and outcome.

Results

The disappearance of recanalization was confirmed by angiography in all re-embolization procedures (technical success rate was 100%). Re-embolization was then successfully achieved inside the original coils, and no branch artery of normal lung tissue was embolized. There were no complications related with this procedure. The blood flow of recanalization was decreased in all cases in a follow-up of 27–33 months (median, 31).

Conclusions

Triaxial system appears to be useful for recanalization of PAVM, especially in difficult cases with a conventional system.

Evaluation of contrast-enhanced MR angiography in the follow-up of visceral arterial aneurysms after coil embolization

BACKGROUND

The placement of detachable coil has become the alternative method of treating visceral arterial aneurysms (VAAs). Imaging follow-up is necessary after coil embolization because of frequent incomplete occlusion.

PURPOSE

To compare contrast-enhanced magnetic resonance angiography (CE-MRA) at 3T with a reference standard of digital subtraction angiography (DSA) for the evaluation of VAAs after coil embolization.

MATERIAL AND METHODS

We treated 15 patients with VAA with coil embolization; eight had splenic artery aneurysms and seven had renal artery aneurysms. We packed the aneurysmal sac preserving native arterial circulation. For follow-up, all patients underwent CE-MRA at 3T and DSA. The results were classified according to coil occlusion: Class 1, complete occlusion; Class 2, residual neck; Class 3, aneurysmal filling.

RESULTS

CE-MRA revealed 11 complete occlusions and four residual necks. DSA follow-up showed 12 complete occlusions and three residual necks. No aneurysmal filling occurred after treatment. Comparison of CE-MRA and DSA findings showed 93% agreement (14/15). CE-MRA allowed the detection of a residual neck in one misclassified case in which DSA showed occlusion. Coil-related artifacts were minimal and did not interfere with evaluation of the occlusion status of the VAAs.

CONCLUSION

CE-MRA at 3T provides high-quality images equivalent to DSA for the evaluation of VAAs after coil embolization. We suggest that CE-MRA at 3T might be used as the primary method for follow-up of VAAs after coil embolization.

Time-resolved Magnetic Resonance Angiography for assessment of recanalization after coil embolization of visceral artery aneurysms

Background:

Follow-up imaging after coil embolization of visceral artery aneurysms is important for detecting recanalization. However, CT examination is susceptible to coil artifacts, which sometimes makes it difficult to assess recanalization. We report 2 cases where recanalization was successfully visualized using time-resolved magnetic resonance angiography after coil embolization of visceral artery aneurysms (one case of right internal iliac artery aneurysm and one case of splenic artery aneurysm). Repeat coil embolization was successfully performed.

Case Report:

Case 1. An 80-year-old male patient with right internal iliac artery (IIA) aneurysm underwent coil embolization. Aneurysm was located at the bifurcation of the right IIA and therefore, after making a femorofemoral bypass, the distal part of the right IIA, aneurysm and the common iliac artery were embolized with a coil. One year later, the size of the aneurysm seemed to have increased on CT. However, the details were not determined because of metal artifacts. Thus, time-resolved MRA was performed and showed minute vascular flow inside the aneurysm. Angiography was subsequently performed and blood flow inside the aneurysm was visualized similar to the findings in time-resolved MRA. Coil embolization was performed once more and vascular flow inside the aneurysm disappeared. Case 2. A 36-year-old male patient with a splenic artery aneurysm underwent coil packing with preservation of splenic artery patency. Four years later, coil compaction was suspected in a CT scan, but CT could not evaluate recanalization because of severe metal artifacts. Angiography was subsequently performed, showing recanalization of the aneurysm as did the time-resolved MRA. Therefore, coil embolization of the aneurysm and splenic artery was performed again.

Conclusions:

Follow-up imaging after coil embolization of visceral artery aneurysms is important for detecting recanalization. However, it is sometimes difficult to assess recanalization with CT because of artifacts caused by metal. In our cases, recanalization of aneurysms was clearly shown by time-resolved MRA and re-embolization was successfully performed.

In conclusion, time-resolved MRA appears to be useful in assessment of recanalization of visceral artery aneurysms after coil embolization.

Endovascular treatment of eight renal artery aneurysms

BACKGROUND

Renal artery aneurysms (RAA) are a relatively rare vascular entity. Treatment could be either surgical or via an endovascular route. The main aim of therapy is to prevent lethal rupture.

PURPOSE

To evaluate the angiographic and clinical results after endovascular treatment (EVT) of eight renal artery aneurysms.

MATERIAL AND METHODS

From January 2000 to June 2011, 18 patients presented with 18 renal artery aneurysms. One was classified as Rundback type I, 15 were type II, and two aneurysms were type III. Endovascular treatment was considered unsafe in 10 cases (all were Rundback type II), and were referred to surgery. The remaining eight aneurysms were treated endovascularly during altogether nine sessions. Among these, four patients were asymptomatic, three were hypertensive, and one presented with ipsilateral flank pains. Aneurysmal sac diameter varied between 12 and 50 mm. EVT included selective coil embolization in five cases, covered stents in two cases, and parent artery occlusion in one.

RESULTS

Follow-up with CT angiography was obtained in all endovascularly treated aneurysms (range 6-54 months, mean 15 months). Complete durable occlusion was achieved in all aneurysms except one, which showed re-expansion after 20 months and was retreated with covered stent implantation. Clinically silent, branch occlusion occurred after four procedures with subsequent limited (less than 25%) ischemic parenchymal loss. All patients were discharged with preserved renal function. Clinical improvement was noted in all symptomatic patients.

CONCLUSION

Endovascular treatment of renal artery aneurysms is an adequate treatment and can be proposed, if feasible, as first step.