Diagnostic Imaging The Urinary System

1. Diagnostic ImagingThe Urinary System Dr. LeeAnn Pack Diplomate ACVR

2. Retroperitoneal Space • Should be fat opacity ventral to sublumbar musculature • Retroperitoneal fat allows visualization of the kidneys • Thigh musculature often overlies caudal aspect and causes an increased opacity • Bifurcation of the deep circumflex iliacs often seen ventral to approximately L4

3. Retroperitoneal Space -Should be fat opacity -Thigh muscles will overlie caudal aspect

4. Retroperitoneal Space • Always examine the retroperitoneal space • Identify the kidneys cranially • Will see the sublumbar musculature • May see circular mineral looking opacities ventral to L4 and 5—circumflex iliac arteries • May see thigh musculature overlying the caudal aspect of the retroperitoneal space • Remainder should be fat opacity

5. Loss of Detail in the Retroperitoneal Space • Consider the following • Young animal with minimal body fat • Emaciated animal • Free fluid in the space • Mass in the space

6. Young Animal • This animal lacks body fat • Notice the poor detail in the retroperitoneal space and also in the peritoneal space

7. Fluid in the Retroperitoneal Space • Will see loss of detail • Fat opacity replaced with soft tissue-may have a streaky/whispy appearance • Most common fluids to consider are urine (generally trauma related) and blood (trauma, ruptured tumor, bleeding disorder • An IVP is indicated to distinguish

8. Fluid in the Retroperitoneal Space • Notice the loss of detail in the RS • Streaky soft tissue opacities are seen

9. Mass in the RPS • Will distend RPS if mass is large enough • May have mass effect on other organs • Consider kidney, adrenal, lymph node, body wall as most likely sources

10. Kidneys • Evaluate on both lateral and VD view • Best measured on the VD view • Right kidney—T13-L1 (dog), L1-L4 (cat) • Left kidney—L2-L4 (dog), L2-L5 (cat) • Dog: 2.5-3.5 times the length of L2 • Cat: 2.4-3.0 times the length of L2

11. Canine rt lt

12. Feline -kidneys usually easier to ID -shape is more round than the dog

13. Renal Calculi

14. IVP • Also called EU- excretory urogram • Start with a well prepared abdomen (enema) • Patient must be well hydrated! • Always do survey films • Inject 400mg I/lb intravenously as a bolus • Acquire films immediately, 5, 10, 20 and 40 minutes (both lateral and VD)

15. IVP Phases • Arteriogram-immediately • Nephrogram-within 20 seconds of injection • Pyelogram-begins 3-5 minutes post injection • Cystogram-as contrast is cleared into the lower urinary tract

16. Arteriogram • Documents initial blood flow to the kidney • Phase is very short • Seldom imaged • Occasionally will see a vascular blush if the first image is literally taken immediately at the time of injection

17. Nephrogram • Contrast is filtered and accumulates within the renal tubules • Should see good initial opacification that gradually fades over the study period • Opacification of the kidneys should be uniform and symmetrical

18. Pyelogram • Contrast is outlining the collecting system • Will be able to evaluate the renal pelvis and diverticuli • Pelvis should be <2mm wide • Recesses should be <1mm wide • Proximal ureters should be <2.5mm

19. Cystogram • This is contrast material entering the lower urinary tract • Will see segmental images of the ureters and the outline of the bladder • A formal cystogram is superior for imaging the bladder

20. Renal Anatomy -renal pelvis -renal sinus -diverticuli -cortex -medulla -ureter

21. Normal IVP-Immediate Films Nephrogram Phase

22. Normal IVP-Five Minutes Nephrogram and Pyelogram

23. Normal IVP-Twenty Minutes Pyelogram and Cystogram

24. Contrast Induced Renal Failure • See opacification of kidneys that persists or becomes more intense over time • Hypotension—acute tubular necrosis—tubular obstruction—acute renal failure • Generally reversible but important to recognize this • Liver and GI are alternative routes of excretion

25. Contrast Induced Renal Failure-several hours post IVP -kidneys still opacified -contrast material within Gi tract -contrast material within the gall bladder

26. Kidneys • Always assess for number, size, shape, margination, location and opacity • Changes observed on radiographs will help you to refine your differential diagnosis list • Can you see them? Normal in size? What is the contour like? Any opacification changes?

27. Small Regularly Shaped Kidney • Most likely a congenital anomaly-hypoplasia • Usually bilateral and therefore usually young dogs with signs of renal disease • Can see with some chronic diseases but those are more commonly irregularly shaped • IVP-usually poor but uniform opacification with normal clearance into the lower urinary tract

28. Small Irregularly Shaped Kidney • May involve one or both kidneys • Consider the following • End-stage kidney • Infarcts • Chronic pyelonephritis • Chronic nephritis

29. Renal Irregularities Note the renal marginal irregularities

30. Large Regularly Shaped Kidneys • May be unilateral or bilateral • Consider the following • Acute pyelonephritis/nephritis • Hydronephrosis • LSA • Large parenchymal cyst or perirenal pseudocyst • FIP • Amyloidosis • Compensatory hypertrophy

31. Hydronephrosis-Bilateral -Suggestive of obstruction at trigone -This was secondary to TCC

32. Hydronephrosis-Unilateral -Hydronephrosis secondary to TCC

33. Polycystic Renal Disease • Most commonly diagnosed in young Persians and Himalayans • Congenital disease-multiple parenchymal renal cysts • May have cysts in other organs -liver, pancreas

34. Polycystic Renal Disease -Large irregularly shaped kidneys -Cat is also in thin body condition-possibly secondary to renal dysfunction -Cysts enlarge and destroy normal tissue

35. Perirenal Pseudocysts • These are outside the renal parenchyma and may be within the capsule or outside the capsule • Most common in older male cats • Kidney is enlarged and smoothly marginated-shape depends on the symmetry of the cyst

36. Renal Neoplasms • Kidney(s) are generally enlarged and irregularly shaped due to a mass • Occasionally will see mineralization associated with the neoplasm • Nephrogram-inhomogenous opacification, marginal irregularity +/- filling defects • Pyelogram-pelvis and diverticuli may be distorted-mass could obstruct pelvis

37. Renal Neoplasm IVP-irregular margin -pelvic distortion Irregular on surveys

38. LSA • This is the most common renal neoplasm in the cat and also occurs in dogs • Generally bilateral • May be regular or irregularly marginated-some are more uniformly infiltrated • May see evidence of other organ involvement-spleen, liver, LN

39. Abnormal Renal Opacity • Mineralization-calculi, parenchymal mineralization or deposition, or neoplastic mineralization • Gas-may be renal or perirenal

40. Ureters • Small soft tissue structures extending from the renal pelvis to the bladder • Normally not seen on survey films

41. Normal

42. Hydroureter • Seldom seen on survey films • May see tubular soft tissue structure in the RPS if the dilation is severe • Best documented with contrast-IVP

43. Hydroureter -occasionally you may see enlarged ureters on plain films

44. Hydroureter -usually requires contrast opacification to identify the dilated ureter(s)

45. Severe Hydroureter

46. Ureteral Calculi • Examine the RPS carefully for mineral opacities • They may be very small-best seen on the lateral but try to identify on both views • *remember the deep circumflex arteries-they will look like small calculi

47. Ureteral Calculi

48. Ectopic Ureter • Usually shows evidence if hydroureter on that affected side • May also see hydronephrosis in the kidney • Ureter may enter the vagina, tunnel by bladder, urethra etc. • Oblique views made at 5 minutes

50. Ureteral Rupture • Most of the ureter is within the RPS—becomes peritoneal as it enters the bladder • May see loss of detail in the RPS or the peritoneal space due to urine leakage • IVP-free contrast material in the RPS or the peritoneal space