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Radiology Of The Urinary Tract

  1. Radiography:
    1. X-rays are electromagnetic waves with photon energies that fall between those of gamma rays and ultraviolet radiation in electromagnetic spectrum. Q
      1. The basic radiological studies commonly used are: Plain KUB, IVP, RGU, AGP, MCU, RGU and Angiogram. These studies can be enhanced by digital radiographic subtraction.
  • Plain Film:
  1. Plain film provides soft tissue shadow of the kidney and gives a rough idea of size (Shrunken kidney in renal failure indicate medical rather than surgical cause), number and location of kidney.   
  2. It demonstrates the: foreign body, bones, abnormal calcifications (stone, calcified aneurysm/ hydatid cyst, calcified ovarian cyst and calcified lymph nodes).
  3. Renal stone in lateral view overlies the spine. Q  Plain X-ray KUB is 1st i/c in renal stone. GB stone ant lo spine.
  1. Intrvenous Pyelography (Intravenous Urography):
    1. In this procedure after a initial plain film, films are taken at timed interval after the IV injection of iodine containing contrast media, which is promptly excreted by the kidney.
    2. It is commonly used for obstruction and to delineate lesions like; Papillary necrosis, medullary sponge kidney, Tumours etc.
    3. Contrast media are ionic (Iodopyracet, Acetrizoate, Diatrizoate, Iothalmate and dimmer of iothalmic acid) and non-ionic (Metrizamide, Iopamidol, Iohexol and ioxalate).
    4. Non-ionic contrast media are safer in cases of history of allergy to iodinated compounds.
    5. If patient is on metformin, stop metformin for 48 hr after IVP, herance of inhand incidence of lactic acidosis. Q
  2. Retrograde Urogram: It is helpful in cases of unsatisfactory excretory urogram; history of adverse reaction to IV contrast media or other method of imaging is unavailable.  It may precipitate urinary tract infection.
  3. Antegrade Pyelography: It is occasionally done when urinary tact imaging is necessary but excretory or retrograde urography has failed or is contraindicated, or when there is nephrostomy tube in place and delineation of upper tract is desired.
  • Micturating Cystourethrography / Reatrograde Urethrography:
  1. Cystogram is obtained by instilling a radiographic contrast media in the bladder and obtain an x-ray film. This outlines the bladder.
  2. Then the patient is asked to micturate and voiding films are taken and this is called MCU.
  3. The urethra can be imaged by obtaining an x-ray while retrograde injection of the contrast in urethra.
  4. MCU is required in lesions of the posterior urethra (PU valves), RGU is more helpful for examining the anterior urethra.
  5. MCU & RGU both require for urethral stricture. Q
Characteristic Appearances
 ADPKD Spider leg or Bell deformity
  Bubble or Swiss cheese appearance on IVP
 Infantile PKD Sunburst pattern on IVP
 Medullary Sponge Kidney Bristles on brush appearance's
  Bouquet of flower appearance on IVP
 Multicystic Dysplastic Kidney Bunch of grapes appearances
 Renal Artery Aneurysm Ring like calcification's
 Ectopic Ureteric Orifice Drooping lily sign on IVP
 Retrocaval Ureter Fish hook or Reverse 'J' deformity on IVP
 Retroperitoneal Fibrosis Medial pulling of ureter or pipestem ureter
  (Pipestem ureter is also seen in TB)
 CA Renal Pelvis Goblet sign or stipple sign on RGP
On PR examination of a male which can not be felt.  (AIIMS Nov 09)
a. Anorectal ring                            
b. Prostate  
c. Ureter                                         
d. Bulb of penis
Ans. C. Ureter
  1. Sonography
    1. Basic Principles:
      1. Sound frequency greater than 20 KHz in called ultrasound.
      2. The frequencies, commonly used in medical practice are between 3.5-10 MHz. Q
    2. Clinical Application:
      1. Ultrasound is commonly used for the evaluation of bladder, prostate, kidney, testis and penis.
      2. In kidney it evaluates size, cortical thickness, echogenicity, cortico-medullary differentiation, mass lesion and cyst.
      3. In the bladder it helps in detecting stone, tumour bladder wall thickness and residual urine.
      4. Prostatic size, calculi and echogenicity can be determined with the help of USG.
      5. Stones appear as hyper echoic (white) while malignancy as hypo echoic (black) shadow.
      6. Higher the frequency, better is the resolution and poor penetration, thus for superficial examination (e.g. testis) higher frequency probes are used.  Q
  2. Computerized Axial Tomography
    1. Basic principle:
      1. In CT scan a thin x-ray film is passed through the patient, and absorbed in a linear array of solid-state or gas detector.
      2. Digital computers assemble and integrate the collected x-ray transmission data to reconstruct a cross sectional image (Tomogram).
      3. CT works on density difference. The unit of CT number is HU (Hounsfield unit). This relative density scale of numbers assigns a value of 0 for water, -1000 for air and +1000-2000 for bone.  
    2. Clinical Application:
      1. MRI in urological diseases gives more or less same information as CT scan, but MR angiography, which does not require contrast media is useful in evaluating renal transplant vessels and renal vein, tumour, thrombus and renal artery stenosis.
      2. Contrast used in MRI is gadolinium. Q It is contraindicated in cases of metallic prosthesis.

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