Contrast-enhanced ultrasound (CEUS) in abdominal intervention

Abstract

The introduction of ultrasound contrast agents has rendered contrast-enhanced ultrasound (CEUS) a valuable complementary technique to address clinically significant problems. This pictorial review describes the use of CEUS guidance in abdominal intervention and illustrates such application for a range of clinical indications. Clinical application of CEUS discussed include commonly performed abdominal interventional procedures, such as biopsy, drainage, nephrostomy, biliary intervention, abdominal tumor ablation and its subsequent monitoring, and imaging of vascular complications following abdominal intervention. The purpose of this article is to further familiarize readers with the application of CEUS, particularly its specific strength over alternative imaging modalities, in abdominal intervention.

Keywords: Abdominal intervention; Contrast enhanced ultrasound; Image guided intervention; Intervention; Interventional radiology; Ultrasound; Ultrasound contrast agents.

Fig. 1

A Grayscale US. B CEUS of a hepatic abscess. Grayscale US image shows the abscess as a heterogeneous echogenic area with poorly defined margin underestimating the true extent of abscess. CEUS enables better delineation of the liver abscess and reveals a sharp boundary (red arrows) between the collection and hepatic parenchyma

Fig. 2

A Grayscale US. B CEUS of a sub-capsular renal abscess. The boundary of the non-enhancing sub-capsular collection (asterisk) is clearly shown on the CEUS but not on the grayscale US image. CEUS guidance allows insertion of the drainage catheter to be performed confidently and reduces the risk of damaging the adjacent renal parenchyma

Fig. 3

A Grayscale US. B Intravascular CEUS and C endocavitary CEUS of a hepatic abscess. Intravascular CEUS shows the enhancing hepatic parenchyma surrounding the non-enhancing abscess (red block arrow), whereas endocavitary CEUS, with the UCA instilled through the drainage tube, confirms adequate drainage catheter position and shows the morphology of the abscess cavity (asterisk)

Fig. 4

A Intravenous CEUS. B Arterial phase image of a contrast-enhanced CT. C Endocavitary CEUS with UCA injected through the nephrostomy. D Urographic phase image of a contrast-enhanced CT of a patient with ureteric injury and urinoma formation following a vascular bypass surgery. CEUS studies (A, C) definitively excluded communication between the fluid collection and the left iliac vascular graft. Although the subsequent CT (B, D) demonstrates similar findings, CEUS provided real-time imaging and instant diagnosis at patient’s bedside

Fig. 5

A Grayscale US. B Color Doppler US. C Intravenous CEUS of a large renal cell carcinoma with central necrosis (red block arrow). The grayscale and color Doppler US do not show differentiation between vascular and avascular portions of the tumor. CEUS clearly shows the avascular necrotic portion (asterisk) of the tumor to be avoided during biopsy

Fig. 6

A Grayscale US. B CEUS of an atrophic kidney targeted for a non-focal biopsy for the sampling of the renal cortex for evaluation of nephropathies. CEUS guidance improves visualization of the atrophic kidney by differentiating the enhancing renal parenchyma from the background tissue, with better delineation of the enhancing renal parenchymal outline (red arrows)

Fig. 7

CEUS-guided nephrostomy puncture. A CEUS and B grayscale images before access into the collecting system was obtained. The stylet of the access needle for nephrostomy puncture was removed and the lumen of the needle was pre-filled with a small drop of diluted microbubble UCA. C CEUS and D grayscale US images obtained immediately after the collecting system is punctured. Microbubbles are visualized in the renal collecting system (red arrow) the instance the successful puncture is made

Fig. 8

Endocavitary CEUS (left) and co-registered grayscale US (right) nephrostography images. UCA can be injected through the drainage catheter to verify the correct placement of the nephrostomy tube. In row (A), the nephrostomy tube is dislodged and there is pooling of microbubble contrast in perinephric spaces (asterisk). CEUS nephrostography following re-insertion of the nephrostomy tube (row B) confirms adequate nephrostomy placement with visualization of microbubble contrast in the renal collecting system (red arrow) and proximal ureter (red arrow head)

Fig. 9

CEUS nephrostography. Following a successful nephrostomy insertion, diagnostic evaluation can be obtained with a CEUS nephrostography by introducing microbubbles into the collecting system. A The renal pelvic (asterisk) and the ureter (red arrow heads) can be visualized. B Patent drainage into the bladder can be confirmed by the presence of microbubbles (red block arrow) in the bladder

Fig. 10

A Grayscale US and B endocavitary CEUS cholangiography: Endocavitary CEUS cholangiography with administration of UCA into the biliary system through drainage catheter confirms adequate placement and patency of the biliary drain (red arrow head) and drainage into the hepaticojejunostomy (red arrows)

Fig. 11

Endocavitary CEUS cholangiography: Endocavitary CEUS cholangiography with administration of UCA into the biliary system through a drainage catheter demonstrates drainage through the biliary anastomosis into the hepaticojejunostomy (red arrows). Pooling of microbubble contrast (asterisk) is noted near the anastomotic region, raising the suspicion of presence of a small biliary leak. However, caution should be exercised in interpretation of this finding, as pooling of microbubble contrast within a cystic duct remnant may display a similar appearance

Fig. 12

A CT (red arrow indicates the ablation zone) and B CEUS images obtained in the immediate post-ablation period following a microwave ablation of a small hepatocellular carcinoma. With its improved temporal and spatial resolution for micro-vascularity, CEUS permits exclusion of any residual vascularity at the ablation zone (asterisk) with confidence

Fig. 13

A Grayscale US and B CEUS images of the right kidney 6 months followup after cryoablation of an upper pole renal cell carcinoma. The cryoablation scar (asterisk) is noted but there are no features suggestive of local recurrence. C Grayscale US and D CEUS images 3 years following cryoablation of the same kidney with recurrence at the ablation site. The recurrence at the ablation scar (t) is of a similar echo reflectivity to the surrounding normal renal parenchyma on grayscale US. The margin (red arrows) of the isoechoic recurrence of renal tumor (t) is better delineated with CEUS due to the excellent ability of CEUS to image the differential vascularity between the tumor and surrounding renal parenchyma

Fig. 14

Grayscale US and endocavitary CEUS images of a radiologically inserted gastrostomy (RIG) tube. A small hypoechoic collection (asterisk) is present in grayscale US (A). Endocavitary CEUS (B), with administration of microbubble contrast through the gastrostomy tube, showed no accumulation of microbubble contrast in the collection, thus excluding an ongoing leak. Correct placement of the gastrostomy tube is further confirmed with visualization of microbubble contrast on CEUS (D with the corresponding grayscale US (C)) within the gastric cavity (g), which is recognizable due to presence of gastric rugae

Fig. 15

Post-renal biopsy pseudoaneurysm. A CEUS demonstrates a pseudoaneurysm (red arrow) within the right kidney. B CEUS performed 1 week following embolization of the pseudoaneurysm demonstrates absence of the pseudoaneurysm and normal perfusion of the surrounding renal parenchyma, confirming the success of the selective embolization procedure

Fig. 16

A Grayscale US image following a renal biopsy demonstrated a perinephric hematoma (boundary marked by red arrows), initially thought to be related to bleeding from the kidney. However, the corresponding CEUS (B) clearly demonstrates the pseudoaneurysm (red arrow head) is within the perinephric hematoma rather than within the kidney. c In view of the CEUS appearances, selective angiography of the right intercostal arteries was performed which indeed demonstrated a pseudoaneurysm (red arrow head) arising from a right intercostal artery. No renal arterial injury was demonstrated on angiography. CEUS in this case suggested the possible anatomic site of complicating arterial injury relating to renal biopsy and provided guidance for the subsequent embolization procedure