Feasibility of Antegrade Contrast-enhanced US Nephrostograms to Evaluate Ureteral Patency

Abstract

Purpose To demonstrate the feasibility of contrast material-enhanced ulrasonographic (US) nephrostograms to assess ureteral patency after percutaneous nephrolithotomy (PCNL) in this proof-of-concept study. Materials and Methods For this HIPAA-compliant, institutional review board-approved prospective blinded pilot study, patients undergoing PCNL provided consent to undergo contrast-enhanced US and fluoroscopic nephrostograms on postoperative day 1. For contrast-enhanced US, 1.5 mL of Optison (GE Healthcare, Oslo, Norway) microbubble contrast agent solution (perflutren protein-type A microspheres) was injected via the nephrostomy tube. Unobstructed antegrade ureteral flow was defined by the presence of contrast material in the bladder. Contrast-enhanced US results were compared against those of fluoroscopic nephrostograms for concordance. Results Ten studies were performed in nine patients (four women, five men). Contrast-enhanced US demonstrated ureteral patency in eight studies and obstruction in two. One patient underwent two studies, one showing obstruction and the second showing patency. Concordance between US and fluoroscopic assessments of ureteral patency was evaluated by using a Clopper-Pearson exact binomial test. These results were perfectly concordant with fluoroscopic nephrostogram results, with a 95% confidence interval of 69.2% and 100%. No complications or adverse events related to contrast-enhanced US occurred. Conclusion Contrast-enhanced US nephrostograms are simple to perform and are capable of demonstrating both patency and obstruction of the ureter. The perfect concordance with fluoroscopic results across 10 studies demonstrated here is not sufficient to establish diagnostic accuracy of this technique, but motivates further, larger scale investigation. If subsequent larger studies confirm these preliminary results, contrast-enhanced US may provide a safer, more convenient way to evaluate ureteral patency than fluoroscopy. © RSNA, 2016 Online supplemental material is available for this article.

Figures

Figure 1a:

Dual-screen gray-scale (left) and CE (right) US images of the collecting system after contrast material injection via a nephrostomy tube in a 72-year-old man 1 day after PCNL. (a) Longitudinal views of the kidney with contrast material distributed throughout the renal collecting system (arrows). (b) Contrast material is distributed throughout the renal collecting system (arrowhead) and proximal ureter (arrow).

Figure 1b:

Dual-screen gray-scale (left) and CE (right) US images of the collecting system after contrast material injection via a nephrostomy tube in a 72-year-old man 1 day after PCNL. (a) Longitudinal views of the kidney with contrast material distributed throughout the renal collecting system (arrows). (b) Contrast material is distributed throughout the renal collecting system (arrowhead) and proximal ureter (arrow).

Figure 2a:

Dual-screen gray-scale (left) and CE (right) US images in a 56-year-old man with a patent collecting system 1 day after PCNL. (a) Initial preinjection images of the bladder demonstrate an indwelling Foley catheter (arrow) within a moderately distended bladder with a few foci of pre-existing air. (b) Images of the bladder 1 minute 30 seconds after injection of US contrast agent via the nephrostomy tube demonstrate robust signal from the contrast agent (arrow). (c) Fluoroscopic nephrostogram confirms ureteral patency (arrow) and contrast agent entering into the bladder.

Figure 2b:

Dual-screen gray-scale (left) and CE (right) US images in a 56-year-old man with a patent collecting system 1 day after PCNL. (a) Initial preinjection images of the bladder demonstrate an indwelling Foley catheter (arrow) within a moderately distended bladder with a few foci of pre-existing air. (b) Images of the bladder 1 minute 30 seconds after injection of US contrast agent via the nephrostomy tube demonstrate robust signal from the contrast agent (arrow). (c) Fluoroscopic nephrostogram confirms ureteral patency (arrow) and contrast agent entering into the bladder.

Figure 2c:

Dual-screen gray-scale (left) and CE (right) US images in a 56-year-old man with a patent collecting system 1 day after PCNL. (a) Initial preinjection images of the bladder demonstrate an indwelling Foley catheter (arrow) within a moderately distended bladder with a few foci of pre-existing air. (b) Images of the bladder 1 minute 30 seconds after injection of US contrast agent via the nephrostomy tube demonstrate robust signal from the contrast agent (arrow). (c) Fluoroscopic nephrostogram confirms ureteral patency (arrow) and contrast agent entering into the bladder.

Figure 3a:

US images in a 30-year-old man 1 day after PCNL for an obstructing left proximal ureteral stone with persistently obstructed system. (a) Initial gray-scale US image shows residual shadowing stones in the left collecting system (arrow). (b) Dual-screen gray-scale (left) and CE (right) images. The CE image shows bright signal (arrow) from the presence of the contrast agent signal within a mildly distended collecting system. (c) Dual-screen gray-scale (left) and CE (right) images. No contrast agent is seen in the bladder after 5 minutes. (d) Scout image prior to the fluoroscopic nephrostogram also demonstrated residual stone fragments (arrow). (e) Concordant fluoroscopic nephrostogram shows a moderately distended renal collecting system (white arrow) and contrast agent preferentially draining back along the nephrostomy tube (black arrow). No contrast agent was identified in the ureter. The patient underwent repeat nephrolithotomy and small obstructing stones were identified. One day later, a repeat CE US scan and nephrostogram both demonstrated a patent system (not shown).

Figure 3b:

US images in a 30-year-old man 1 day after PCNL for an obstructing left proximal ureteral stone with persistently obstructed system. (a) Initial gray-scale US image shows residual shadowing stones in the left collecting system (arrow). (b) Dual-screen gray-scale (left) and CE (right) images. The CE image shows bright signal (arrow) from the presence of the contrast agent signal within a mildly distended collecting system. (c) Dual-screen gray-scale (left) and CE (right) images. No contrast agent is seen in the bladder after 5 minutes. (d) Scout image prior to the fluoroscopic nephrostogram also demonstrated residual stone fragments (arrow). (e) Concordant fluoroscopic nephrostogram shows a moderately distended renal collecting system (white arrow) and contrast agent preferentially draining back along the nephrostomy tube (black arrow). No contrast agent was identified in the ureter. The patient underwent repeat nephrolithotomy and small obstructing stones were identified. One day later, a repeat CE US scan and nephrostogram both demonstrated a patent system (not shown).

Figure 3c:

US images in a 30-year-old man 1 day after PCNL for an obstructing left proximal ureteral stone with persistently obstructed system. (a) Initial gray-scale US image shows residual shadowing stones in the left collecting system (arrow). (b) Dual-screen gray-scale (left) and CE (right) images. The CE image shows bright signal (arrow) from the presence of the contrast agent signal within a mildly distended collecting system. (c) Dual-screen gray-scale (left) and CE (right) images. No contrast agent is seen in the bladder after 5 minutes. (d) Scout image prior to the fluoroscopic nephrostogram also demonstrated residual stone fragments (arrow). (e) Concordant fluoroscopic nephrostogram shows a moderately distended renal collecting system (white arrow) and contrast agent preferentially draining back along the nephrostomy tube (black arrow). No contrast agent was identified in the ureter. The patient underwent repeat nephrolithotomy and small obstructing stones were identified. One day later, a repeat CE US scan and nephrostogram both demonstrated a patent system (not shown).

Figure 3d:

US images in a 30-year-old man 1 day after PCNL for an obstructing left proximal ureteral stone with persistently obstructed system. (a) Initial gray-scale US image shows residual shadowing stones in the left collecting system (arrow). (b) Dual-screen gray-scale (left) and CE (right) images. The CE image shows bright signal (arrow) from the presence of the contrast agent signal within a mildly distended collecting system. (c) Dual-screen gray-scale (left) and CE (right) images. No contrast agent is seen in the bladder after 5 minutes. (d) Scout image prior to the fluoroscopic nephrostogram also demonstrated residual stone fragments (arrow). (e) Concordant fluoroscopic nephrostogram shows a moderately distended renal collecting system (white arrow) and contrast agent preferentially draining back along the nephrostomy tube (black arrow). No contrast agent was identified in the ureter. The patient underwent repeat nephrolithotomy and small obstructing stones were identified. One day later, a repeat CE US scan and nephrostogram both demonstrated a patent system (not shown).

Figure 3e:

US images in a 30-year-old man 1 day after PCNL for an obstructing left proximal ureteral stone with persistently obstructed system. (a) Initial gray-scale US image shows residual shadowing stones in the left collecting system (arrow). (b) Dual-screen gray-scale (left) and CE (right) images. The CE image shows bright signal (arrow) from the presence of the contrast agent signal within a mildly distended collecting system. (c) Dual-screen gray-scale (left) and CE (right) images. No contrast agent is seen in the bladder after 5 minutes. (d) Scout image prior to the fluoroscopic nephrostogram also demonstrated residual stone fragments (arrow). (e) Concordant fluoroscopic nephrostogram shows a moderately distended renal collecting system (white arrow) and contrast agent preferentially draining back along the nephrostomy tube (black arrow). No contrast agent was identified in the ureter. The patient underwent repeat nephrolithotomy and small obstructing stones were identified. One day later, a repeat CE US scan and nephrostogram both demonstrated a patent system (not shown).