Contrast Enhanced Ultrasonography for the Evaluation of Coil Embolization of Splenic Artery Aneurysm
A 65-year-old woman with compensated liver cirrhosis secondary to hepatitis C virus infection was under surveillance for early detection of hepatocellular carcinoma with ultrasonography and, due to suboptimal ultrasound feasability, at longer intervals with computed tomography (CT). During follow-up, a splenic artery aneurysm appeared and progressively increased from 18 mm to ≈30 mm in diameter over a 9-month interval. The patient had severe splenomegaly secondary to portal hypertension and hypersplenism with a low platelet count (≈30.000/mL). Percutaneous arterial embolization was proposed to the patient1 because severe portal hypertension was considered a contraindication to surgical splenectomy. Embolization was carried out, preceded by platelet infusion, using “fibered” coils and interlocking detachable coils without complications.
Eight weeks later, the patient underwent abdominal CT as part of the surveillance program for hepatocellular carcinoma; no nodule with pattern of hepatocellular carcinoma was identified; at the splenic level, frank metallic artifacts were evident and prevented assessment of treatment efficacy (Figure 1) as described in previous reports from the literature with this technique.2
To investigate the splenic aneurysm status, an attempt was made with conventional ultrasound (Figure 2) and color duplex-doppler ultrasonography, which failed to provide definitive and unquestionable information about the success of the embolization. Doppler ultrasound detected aneurismal arterial signals, but this mere detection does not signify unsuccessful of treatment because the lumen of the splenic artery is expected to remain at least partially patent (Figure 3). Briefly, ultrasonography was unable to demonstrate whether the lumen of the aneurismal sac had been completely obliterated or persisted patent (and at what extent) (Figures 2 and 3⇓). Because magnetic resonance angiography was also expected to suffer from artifacts similar to those of CT, assessment of treatment efficacy would have required digital subtraction angiography, but this is an invasive procedure with additional hazards in a patient with low platelet count. For these reasons, ultrasound was immediately integrated with contrast enhancement. Contrast enhanced ultrasound (CEUS) works at second harmonic ultrasound frequency,3 which reduces artifacts and is able to detect flowing as well as stationary microbubbles, with a sort of subtraction of background echoes (as tissues mainly produce echoes at the fundamental frequency, which is removed). CEUS was performed with a low amount of contrast agent, injected in an antecubital vein (1 mL of SonoVue, Bracco, Milan, Italy) to limit disturbance from contrast signals deriving from surrounding vessels, namely, portosystemic collaterals at the splenic hilum. CEUS clearly showed persistent patency of the peripheral parts of the aneurysm, around the metallic coils, which instead included a thrombosed core, anechoic as devoid of any contrast perfusion (Figure 4A and B; see also Movie I in the online-only Data Supplement). Such a pattern indicated an incomplete effect of the first embolization, information that was not provided by the previous CT. Based on such an examination, the patient was resubmitted to arteriography, which confirmed the findings of CEUS (Figure 5) and allowed further metallic coil deployment. Follow-up examination with CEUS 2 days later confirmed complete obliteration of the aneurysm (Figure 6A) and partial splenic infarction at the upper pole due to dislodgement of a single metallic coil (Figure 6B).
The possibility of optimal assessment of coil embolization of splenic artery aneurysm was confirmed in other patients, including 1 patient who received splenic aneurysm embolization 7 years before. Also, in this case, CEUS showed a detailed evaluation of the extent of coil-induced thrombosis and size of the residual patent lumen (Figure 7).
The present images suggest that CEUS, a low-cost, noninvasive, safe technique,4 is worth attempting to assess arterial aneurysms treated by coil embolization. CEUS is recommended even if conventional ultrasonography appears technically unsatisfactory due to artifacts because second harmonic imaging can eliminate most of them, provided that the aneurysm can be preliminarily identified with ultrasonography. CEUS is able to show contrast distribution within the aneurysm, even in the presence of coils, and it might rescue cases in which adequate assessment of the aneurysm is prevented by artifacts at CT or magnetic resonance imaging, limiting unnecessary, especially invasive radiological techniques.
Fabio Piscaglia and Luigi Bolondi received consultancy fees for giving scientific lectures during events sponsored by Bracco.
The online-only Data Supplement is available with this article at http://circ.ahajournals.org/cgi/content/full/122/11/e451/DC1.
Claudon M, Cosgrove D, Albrecht T, Bolondi L, Bosio M, Calliada F, Correas JM, Darge K, Dietrich C, D'Onofrio M, Evans DH, Filice C, Greiner L, Jäger K, Jong N, Leen E, Lencioni R, Lindsell D, Martegani A, Meairs S, Nolsøe C, Piscaglia F, Ricci P, Seidel G, Skjoldbye B, Solbiati L, Thorelius L, Tranquart F, Weskott HP, Whittingham T. Guidelines and good clinical practice recommendations for contrast enhanced ultrasound (CEUS). Update 2008Ultraschall Med. 2008; 29: 28–44.