CT Urography

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 ).

4. Basic concept of Urinary tract imaging Comprehensive upper tract imaging must include 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.

5. 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.

6. 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.

7. 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.

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

9. 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.

10. Techniques Three phase technique. Split bolus technique. Supplemental use of normal saline infusion and diuretic injection.

11. 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)

12. 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.

13. 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.

14. 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.

15. 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.

16. 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.

17. NORMAL ANATOMY

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

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

20. NORMAL VARIANTS AND CONGENITAL ANOMALIES

21. 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.

22. PROMINENT RENAL PAPILLA

23. COMPOUND CALYX

24. 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.

25. ECTOPIC KIDNEY

26. VR IMAGE MIP IMAGE

27. HORSESHOE KIDNEY

28. DOUPLEX LEFT COLLECTING SYSTEM WITH ECTOPIC UPPER MOIETY URETER The Weigert - 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.

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

30. 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.

31. 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

32. UROLITHIASIS

33. CASE (1) NON ENHANCED CT SHOWING BI L ATER A L R EN A L P EL V IS C ALC U L I W IT H MA R K ED PYELITIS. ENH A N C E D C T SH OW I N G GOOD ENHANCEMENT.

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

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

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

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

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

39. CURVED REFORMATS SHOWING 3 LOWER URETERIC STONES.

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

41. CASE ( 6 ) MEDULLARY NEPHROCALCINOSIS

42. 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 .

43. RENAL INFECTIONS

44. 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.

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

46. DOUBLE DENSITY VR IMAGE SHOWING THE OBSTRUCTING CALCULUS

47. CASE (3) RIGHT UPPER POLAR ABSCESS

48. RIGHT UPPER POLAR ABSCESS

49. DELAYED FILLING OF THE ABSCESS

50. RENAL SOLs

51. CASE ( 1 ) RENAL CYST

52. SIMPLE (BOSNIAK TYPE I) RENAL CYST

53. CASE ( 2 ) PARAPELVIC CYST

54. MULTILOCULAR PARAPELVIC CYST WITH STRETCHING OF THE MAJOR CALYCES

55. CASE ( 3 )

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

57. CASE ( 4 )

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

59. CASE ( 5 )

60. BOSNIAK TYPE IV CYST THICK ENHANCING MURAL NODULE

61. CASE ( 6 ) RENAL MASS

62. SOLID UPPER POLAR MASS CLEARLY DEMONSTRATED IN CORONAL IMAGES

63. CASE ( 7 )

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

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

66. DISPLACED LEFT KIDNEY WITH DOUPLEX RIGHT COLLECTING SYSTEM

67. INTRARENAL COLLECTING SYSTEM

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

69. 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

70. ACUTE PAPILLARY NECROSIS YOUNG FEMALE PATIENT WITH PAINLESS HEMATUR I A AND HISTORY OF ANALGESIC ABUSE

71. CASE (3) UROTHELIAL NEOPLASM

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

73. CASE (4) UROTHELIAL NEOPLASM

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

75. U RETE RS AS A RULE; MALIGNANT URETERIC NEOPLASMS CHARACTERISTICALLY CAUSE DILATATION OF THE URETER BOTH PROXIMAL AND DISTAL TO THE LESION .

76. CASE (1)

77. CASE (2)

78. CASE (3)

79. CASE ( 4 )

80. CASE ( 5 )

81. 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.

82. URINARY BLADDER

83. 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.

84. CASE (1)

85. CASE (2) EXTRAVESICAL PARARECTAL MASS