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CHAPTER 96: Urologic Imaging

Mariano M Volpacchio; Catherine A D’Agostino; Sofia Bakken; Christopher J Palestro; Robin J Warshawsky; Gregory M Grimaldi; John S Pellerito; Ernesto P Molmenti

NORMAL URINARY IMAGING (FIGures 96-1 AND 96-2)

FIGURE 96-1

Normal transplant percutaneous nephrostogram. Note the percutaneous needle (red arrow) used for injection of contrast into the collecting system (green arrow) of the transplant kidney. The ureter (blue arrow) and bladder (yellow arrow) can be identified.

A radiograph shows the kidney, ureter, and bladder. The radiograph highlights a needle that is in contact with a branched tubular collecting structure. The ureter is shown connecting to the bladder.
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FIGURE 96-2

Normal 99mTc-MAG3 renal scan. There is normal parenchymal uptake, cortical transit, and excretion of tracer. The renogram curve is typical of normal function.

A radiograph and a graph plotting kidney activity. The radiograph shows a chart that depicts kidney function and a bean-shaped kidney connected to a tubular structure. The data in the graph are as follows. The vertical axis plots activity ranging from 0 to 9000 in increments of 1000 and the horizontal axis plots minutes ranging from 0.0 to 22.0 in increments of 2.2. The curve starts close to the origin and peaks at (2,8800), thereafter it decreases gradually to end at (20,3000). Two vertical lines start to meet the horizontal axis at 2 and 8 respectively.
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URINARY OBSTRUCTION (FIGS. 96-3 TO 96-24)

  • Most obstructions occur at the ureterovesical junction or in the distal transplant ureter

  • In the immediate postoperative period, obstructions are usually associated with:

    • Technical factors:

      • Tight anastomosis

      • Torsion/twisting of the ureter

    • Edema

    • Blood clots

  • In a more delayed fashion, contributing factors include:

    • Fibrosis

    • Ischemia

    • Rejection

    • Infections

    • Mass effect

    • Adhesions

    • Calculi

  • Ultrasound images (usually the initial modality of choice) should be interpreted with caution

    • Dilatation of the collecting system may be absent in:

      • early stages

      • instances of parenchymal fibrosis

    • Most transplant kidneys have a prominent renal pelvis

    • Dilatation of the transplant ureter and collecting system may be due to reflux from a full bladder

    • Dilatation may persist from previous instances of treated obstruction

  • Nuclear scintigrams may show clearance of the radiotracer.

  • Antegrade pyelograms not only can diagnose obstructions, but also show the site and type of stenosis and may be used as a guide to percutaneous treatment

FIGURE 96-3

Hydronephrosis. These two ultrasound images show marked dilatation of the collecting system (green arrow), renal pelvis (yellow arrow), and ureter (white arrow). When obtaining such studies, the bladder should be empty in order to avoid an inaccurate reading associated with urinary reflux.

A radiograph highlights enlarged regions of the collecting system.
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FIGURE 96-4

Hydronephrosis. These two ultrasound images show marked dilatation of the collecting system (green arrow), renal pelvis (yellow arrow), and ureter (white arrow). When obtaining such studies, the bladder should be empty in order to avoid an inaccurate reading associated with urinary reflux.

A radiograph highlights an enlarged region at the center of the kidney. The ureter connecting to the kidney is labeled.
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FIGURE 96-5

As shown in the image above, the presence of an extra-renal pelvis (green arrow) is a frequent finding in transplantation and should not be confused with hydronephrosis. When hydronephrosis is present it is coexistent with calyceal dilatation.

A radiograph highlights the presence of an extra renal pelvis outside the renal sinus.
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FIGURE 96-6

Renal cysts (green arrow) in the allograft are part of the differential diagnosis.

A radiograph highlights a rounded renal cyst.
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FIGURE 96-7

Patient who presented with hydronephrosis (blue arrows) on ultrasound (Figure 96-7) and percutaneous nephrostomy studies. (Figures 96-8 and 96-9). Focal strictures (green arrows) were observed at the ureterovesical junction, with some passage of contrast into the ...

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