CT Urography Technique, Normal anatomy, variants and pathology

1. CT Urography
Dr. Yash Kumar Achantani
OSR

2. Definition
A CT urography is a CT examination of the entire urinary tract
before and after the administration of IV contrast material and
includes excretory phase images.
It gives both anatomical and functional information.

3. Indications
 Hematuria
 Suspected urothelial cancer (e.g., positive urine cytology)
 Follow-up urothelial cancer
 Hydronephrosis ?etiology
 Congenital anomalies
CTU is generally performed on patients more than 40 years of
age and patients with at least one of the following: a history of
transitional cell carcinoma (and who are therefore likely to have
recurrences or metachronous tumors), positive urine cytology,
previous equivocal imaging studies, and persistent symptoms
(e.g., ongoing hematuria).

5. Basic concept of Urinary tract imaging
Comprehensive upper tract imaging must include
(a) Unenhanced axial CT of the kidneys,
(b) Enhanced CT of the abdomen and pelvis, and
(c) excretory phase enhanced images of the urinary tract obtained with
projection urography and/or axial CT images.

6. Unenhanced CT scans and plain abdominal radiographs (kidney, ureter,
and bladder [KUB], scout) are primarily used for the evaluation of
• Stone disease
• Renal parenchymal calcifications,
• Precontrast attenuation measurements of renal masses,
• Exclusion of hemorrhagic changes.

7. Contrast material–enhanced imaging, essential for complete evaluation
of the urinary tracts.
Nephrographic phase enhanced images are useful for the evaluation of
the renal parenchyma, especially in the detection and evaluation of
renal neoplasms, parenchymal scarring, and renal inflammatory disease.
 Corticomedullary differentiation nephrographic phase CT scans
obtained 30–70 seconds after the start of intravenous contrast
material injection provide information about the renal vasculature
and perfusion, although small renal masses located in the medullary
portions of the kidneys may not be appreciated.
 Homogeneous nephrographic enhanced CT scans are typically
obtained 90– 180 seconds after initiation of intravenous contrast
material administration. Homogeneous nephrographic enhanced CT
scans are more sensitive for detection and characterization of renal
masses.

8. Excretory phase obtained at 8–10 minutes following intravenous
contrast material injection is essential for assessing subtle urothelial
abnormalities including Urothelial tumors,
• Papillary necrosis,
• Caliceal deformity,
• Ureteral stricture,
• Inflammatory changes of the renal collecting systems, ureters, and
bladder.
The bladder is seen best on 20- minute and postvoiding images.

9. Techniques
 Combined CT and EU CT urography method.
 CT scanned projection radiographic (SPR) images following
intravenous contrast material administration.
 CT-Only CT Urography.

10. CT-Only CT Urography
This approach relies exclusively on the acquisition of unenhanced and
enhanced CT scans of the abdomen and pelvis, including the essential
acquisition of thin-section helical CT scans of the urinary tracts during
the excretory phase of enhancement.
No bowel preparation is necessary for this type of CT urography
examination; however, the risk of aspiration of solid food from
vomiting can be lessened by withholding oral intake for several hours
prior to the examination. In some patients, metallic hip prostheses
may result in beam hardening artifacts and make assessment
of the distal ureters and bladder difficult.

11. Techniques
 Threephase technique.
 Splitbolustechnique.
 Supplemental use of normal saline infusion and diuretic
injection.

12. Three phase protocol
 Unenhanced phase
 Nephrographic phase after 90-100 secs
 Pyelographic phase after 12-15 minutes
 4 Phase protocol (5 min and 7.5 min)

13. Split Bolus protocol
 Unenhanced Phase
 Nephro-pyelographic phase : 30 ml of nonionic contrast
material is infused and after 10 min another 100 ml of contrast
is injected
ADV: Assess tract with low radiation exposure.

14. Supplemental use of normal saline
infusion and diuretic injection.
Supplemental infusion of 250 mL of physiologic saline immediately
after injecting intravenous contrast material significantly improves
opacification of the distal ureters.
Intravenous injection of low-dose diuretics (10 mg of furosemide)
before intravenous contrast material injection also permitted less
dense, homogeneous opacification of the collecting systems compared
to supplemental infusion of 300 mL of normal saline.

15. The 7.5-minute delayed excretory phase enhanced CT acquisition
technique resulted in the most significantly increased distention of the
intrarenal collecting system and proximal ureter, followed by the saline
infusion technique.

16. Assessment of source axial CT scans, displayed by using wide window
settings similar to the bone window settings, is essential for accurate
diagnosis.
Post processing techniques including multiplanar reformation and 3D
reformatted images can be generated from excretory phase enhanced
axial CT scans, displaying the urothelial anatomy and disease in a
traditional coronal display format.
Multiplanar reformatted images in orthogonal coronal or oblique (en
face) planes help define the location and extent of the lesions shown
on axial CT images.

17. Maximum intensity projection (MIP), average intensity projection (AIP),
and perspective volume rendered reformatted images from thin (5–20
mm) and thick (35–90 mm) slabs can be generated from the original
axial data set.

19. NORMAL ANATOMY

20. NORMAL ANATOMY
FRONTAL (ANTERIOR) VIEW OF VR IMAGES

21. MIP IMAGE (POSTERIOR VIEW) VR DOUBLE DENSITY IMAGE
(POSTERIOR VIEW)

22. NORMAL VARIANTS AND
CONGENITAL ANOMALIES

23. NORMAL PAPILLARY BLUSH
Backflow into terminal
collecting ducts (papillary
ducts); Produces wedge-
shaped striated area or blush
extending from a calyx;
Usually considered normal
phenomenon.

24. PROMINENT RENAL PAPILLA

25. COMPOUND CALYX

26. PTOTIC KIDNEY
Nephroptosis (also called
floating kidney or renal ptosis) is an
abnormal condition in which
the kidney drops down into the pelvis
when the patient stands up. It is more
common in women than in men.

27. ECTOPIC KIDNEY

28. VR IMAGE MIP IMAGE

29. HORSESHOE KIDNEY

30. DOUPLEX LEFT COLLECTING SYSTEM WITH
ECTOPIC UPPER MOIETY URETER
TheWeigert-Meyer rule states that. the
upper pole ureter is the ectopic ureter
and its orifice inserts inferomedially in the
bladder in relationship to the lower pole
normal ureter.

32. BENIGN TUBULAR ECTASIA
The appearance arises from congenital dilatation/ectasia of the distal tubules
of the nephrons in a medullary pyramid.

33. CTU shows a "paintbrush" appearance to the medullary pyramid.
The strands of the "brush" are mildly dilated tubules full of contrast
(tubules dilated to ~0.2 mm).
Unlike medullary nephrocalcinosis, renal tubular ectasia cannot be seen
on a plain radiograph or a noncontrast CT.

34. CROSSED FUSED ECTOPIA
Crossed fused renal ectopia essentially refers to an anomaly where the
kidneys are fused and located on the same side of the midline.
Subtypes
type a: inferior crossed fusion
type b: sigmoid kidney
type c: lump kidney
type d: disc kidney
type e: L-shaped kidney
type f: superiorly crossed fused

37. UROLITHIASIS

38. CASE (1)
NON ENHANCED CT SHOWING
BILATERAL RENAL PELVIS
CALCULI WITH MARKED
PYELITIS.
ENHANCED CT SHOWING
GOOD ENHANCEMENT.

39. MIP; THE STONES ARE WELL-SEEN WITHIN THE
OPACIFIED RENAL PELVIS.

40. CASE (2)
THICK SLAB MIP
BILATERAL RENAL
AND UB STONES
CORONAL IMAGES
SHOWING MARKED
PYELITIS OF THE
LEFT KIDNEY

41. MIP; THE STONES ARE WELL-SEEN WITHIN THE
OPACIFIED RENAL PELVIS. MULTIPLE UB STONES.

42. CASE (3)
PRE AND POST CONTRAST SCANS.
CALCULUS IN RIGHT KIDNEY
WITH MARKED STRANDING OF
THE PERINEPHRIC FAT.

43. CASE (4)
ACUTELY OBSTRUCTED
LEFT KIDNEY WITH
PERINEPHRIC COLLECTION
(FORNICEAL RUPTURE).

44. CURVED REFORMATS
SHOWING 3 LOWER
URETERIC STONES.

45. CASE (5)
CURVED REFORMAT
LOWER URETERIC STONE
CAUSING MILD HYDRONEPHROSIS
DOUBLE DENSITY VR IMAGE
THE STONE IS DEMONSTRATED
AGAINST THE UNDERLYINGBONE

46. CASE (6)
MEDULLARY NEPHROCALCINOSIS

48. Renal medullary nephrocalcinosis is the commonest form of nephrocalcinosis and
refers to the deposition of calcium salts in the medulla of the kidney.
Due to the concentrating effects of the loops of Henle, and the biochemical milieu of
the medulla, compared to the cortex, it is 20 times more common than cortical
nephrocalcinosis.

49. RENAL INFECTIONS

50. CASE (1)
MULTIFOCAL NEPHRONIA
Nephronia refers to an intermediate stage
between acute pyelonephritis and renal
abscess, and is a focal region of interstitial
nephritis.
It appears as a wedge of poorly perfused
renal parenchyma, without a cortical rim
sign.

51. CASE (2)
OBSTRUCTED INFECTED KIDNEY
ENLARGED LEFT KIDNEY WITH MARKED STRANDING OF THE
PERINEPHRIC FAT AND OBSTRUCTING PELVIC CALCULUS

52. DOUBLE DENSITY VR IMAGE SHOWING
THE OBSTRUCTING CALCULUS

53. CASE (3)
RIGHT UPPER POLAR ABSCESS

54. RIGHT UPPER POLAR ABSCESS

55. DELAYED FILLING OF THE ABSCESS

56. RENAL SOLs

57. CASE (1)
RENAL CYST

58. SIMPLE (BOSNIAK TYPE I) RENAL CYST

59. CASE (2)
PARAPELVIC CYST

60. MULTILOCULAR PARAPELVIC CYST
WITH STRETCHING OF THE MAJOR
CALYCES

61. CASE (3)

62. BOSNIOAK TYPE II CYST WITH THIN CALCIFIED
RIM AND INTRACYSTIC SEPTUM

63. CASE (4)

64. BOSNIAK TYPE III CYST
THICK ENHANCING INCOMPLETE
SEPTUM AND IRREGULAR OUTLINES

65. CASE (5)

66. BOSNIAK TYPE IV CYST
THICK ENHANCING MURAL NODULE

67. CASE (6)
RENAL MASS

68. SOLID UPPER POLAR MASS
CLEARLY DEMONSTRATED
IN CORONAL IMAGES

69. CASE (7)

71. MALIGNANT LOWER POLAR LEFT RENAL MASS WITH
ENHANCING MALIGNANT THROMBUS WITHIN THE IVC
AND SECONDARY VARICOSITIES OF THE LEFT TESTICULAR VEIN.

72. CASE (8)
MALIGNAT SUPRARENAL MASS
WITH LIVER METASTASES

74. DISPLACED LEFT KIDNEY WITH
DOUPLEX RIGHT COLLECTING SYSTEM

75. INTRARENAL COLLECTING
SYSTEM

76. CASE (1)
PRE AND POST CONTRAST MIP IMAGES
TUBULAR DILATATION WITH TINY
CALCULI WITHIN THE DILATED TUBULES
(MEDULLARY SPONGE KIDNEY)

78. CASE (2)
Renal papillary necrosis refers to ischemic necrosis of the renal papillae.
CT urography typically demonstrates multiple small collections of contrast
material in the papillary regions peripheral to the calyces. The entire papilla
may become necrotic. The papillary defects may eventually become
peripherally calcified. Sloughed papillae appear as filling defects in the
collecting system and ureters and may obstruct them and cause renal colic

79. ACUTE PAPILLARY NECROSIS
YOUNG FEMALE PATIENT WITH
PAINLESS HEMATURIAAND
HISTORY OF ANALGESIC ABUSE

80. CASE (3)
UROTHELIAL NEOPLASM

81. MALIGNANT UROTHELIAL NEOPLASM OF THE
UPPERE CALYX IN A MIDDLE AGED MALE WITH
PAINLESS HEMATUREA

82. CASE (4)
UROTHELIAL NEOPLASM

83. ANOTHER EXAMPLE OF MALIGNANT UROTHELIAL
NEOPLASM OF THE UPPERE CALYX

84. URETERS
AS A RULE;
MALIGNANT URETERIC NEOPLASMS CHARACTERISTICALLY CAUSE
DILATATION OF THE URETER BOTH PROXIMAL AND DISTAL TO THE
LESION.

85. CASE (1)

87. CASE (2)

89. CASE (3)

91. CASE (4)

93. CASE (5)

94. FIBROVASCULAR POLYP OF THE URETER
Fibroepithelial polyp is a benign
mesodermal tumor mainly seen in adults.
Radiologically, the diagnosis is very hard
to make.
Excision is advised if
hydroureteronephrosis is seen or if the
patient is symptomatic since there is an
overlap in appearance with
transitional/urothelial cell carcinoma.

95. URINARY BLADDER

96. Transitional cell carcinoma (TCC) is the most common primary neoplasm
of the urinary bladder, and bladder TCC is the most common tumour of
the entire urinary system.
Bladder transitional cell carcinomas appear as either focal regions of
thickening of the bladder wall, or as masses protruding into the bladder
lumen, or in advanced cases, extending into adjacent tissues.
The masses are of soft tissue attenuation and may be encrusted with
small calcifications.

97. CASE (1)

99. CASE (2)
EXTRAVESICAL PARARECTAL MASS