Imaging in urology,at the department of chandka medical college urology department

2. • Imaging continues to play indispensable role in diagnosis and
management of urologic diseases
• Because many urologic conditions cannot be assessed by physical
examination, conventional radiography has long been critical to
diagnosis of conditions of the adrenals, kidneys, ureters, and
bladder.
• Development of computed tomography (CT) imaging and use of
intravenous contrast agents have provided detailed anatomic,
functional, and physiologic information about urologic conditions.

3. • PLAIN FILM IMAGING (KUB)
• ULTRASONOGRAPHY
• X RAY IVU
• X RAY RETROGRADE PYELOGRAPHY
• X RAY URETHROGRAM
• CYSTOGRAM
• VCUG
• COMPUTED TOMOGRAPHY
• MAGNETIC RESONANCE IMAGING
• RADIONUCLIDE IMAGING (DISCUSSED IN PREVIOUS
PRESENTATION)

4. • Remains useful for preoperative diagnosis and
postoperative evaluation in variety of different
urologic conditions.
• Conventional radiography includes
• ABDOMINAL PLAIN RADIOGRAPHY
• INTRAVENOUS EXCRETORY UROGRAPHY
• RETROGRADE PYELOGRAPHY
• RETROGRADE URETHROGRAPHY
• CYSTOGRAPHY

5. v

12. • FILM IS TAKEN WITH PATIENT SUPINE AND SHOULD INCLUDE ENTIRE
ABDOMEN FROM BASE OF STERNUM TO PUBIC SYMPHISIS

32. • A non-invasive method of urinary tract imaging.
• It provides good images of kidneys and bladder
• Anatomical detail of ureter is poor and mid-ureter cannot be imaged at all
by ultrasound because of overlying bowel gas.
USES OF ULTRASOUND
RENAL
• Assessment of haematuria.
• Determination of nature of renal masses—can differentiate simple cysts
(smooth, well-demarcated wall, refl ecting no echoes; benign) from solid
masses (almost always malignant; cystic masses with solid components or
multiple septae or calcifi cation may be malignant), from those casting an
‘acoustic shadow’
• Can determine presence/absence of hydronephrosis (dilatation of
collecting system) in patients with abnormal renal function
• Allows ultrasound-guided nephrostomy insertion in patients with hydro-
nephrosis and renal impairment or with infected, obstructed kidneys.

33. Bladder
• Measurement of post-void residual urine volume.
• Allows ultrasound-guided placement of suprapubic
catheter.
Prostate: TRUS
• Measurement of prostate size (where gross
prostatic enlargement is suspected on the basis of a
DRE and surgery in the form of open prostatectomy
is contemplated).
• To assist prostate biopsy (allows biopsy of hypo- or
hyper-echoic lesions).
• Can establish presence of ejaculatory duct
obstruction.

34. Testes
• Assessment of patient complaining of ‘lump in
testicle (or scrotum)’—can differentiate benign
lesions (hydrocele, epididymal cyst) from
malignant testicular tumours (solid, echo poor,
or with abnormal echo pattern).
• When combined with power Doppler, can
establish the presence/ absence of testicular
blood flow in suspected torsion.

36. • It can detect very small differences in X-ray
absorption values of tissues, providing very wide
range of densities (therefore, differentiation
between tissues) when compared with plain
radiography.
• Computer calculates absorption value
(attenuation) of each pixel and reconstructs this
into an image.

37. • Attenuation values are expressed on scale from
–1000 to +1000 Hounsfi eld units
• (water = 0 air = –1000 bone = +1000).
• More recently, advances in computing power
have enabled data to be reformatted so that
images can be produced in sagittal and coronal
planes as well as in the more familiar horizontal
plane
• ‘Plain’ CT scans (without contrast) can detect
calcifi cation and calculi within urinary tract.

38. • Administration of intravenous contrast is used to
investigate haematuria,to evaluate nature of
solid renal lesions, and to determine nature of
soft tissue masses (e.g. to differentiate bowel
from lymph nodes in cancer staging CTs).
• ‘Spiral’ or ‘helical’ CT (also known as multidetec-
tor CT urography—MDCTU—when done
following intravenous contrast administration) is
very rapid scanning while table on which patient
is lying is moved though scanner. Multiple
images (‘slices’) of patient are taken.

39. • A large volume of body can be imaged in single
breath hold, thus eliminating movement artefact
and increasing spatial resolution
• Overlapping thin sections can be ‘reconstructed’
into images in multiple planes (multiplanar
reformatting—MPR) so lesions can be imaged in
multiple planes (sagittal, coronal) as opposed to
the traditional transverse sections.

41. Renal
• Investigation of renal masses—characterizes solid from
cystic lesions differentiates benign (e.g. angiomyolipoma)
from malignant solid masses (e.g. renal cell carcinoma).
• Staging of renal cancer (establishes local, nodal, and
distant spread).
• Assessment of stone size and location (within collecting
system or within parenchyma of kidney).
• - Detection and localization of site of intrarenal and
perirenal collections of pus (pyonephrosis, perinephric
abscess).
• ‘Staging’ (grading) of renal trauma.
• Determination of cause of hydronephrosis.

42. • IVU, previously the mainstay of imaging in patients with
flank pain, has been superseded by CT-KUB, a non-contrast
CT of the kidneys, ureters, and bladder.
ADVANTAGE OF C.T KUB SCAN OVER IVU
• Compared with IVU, CT-KUB Has greater specificity (97%)
and sensitivity (94–100%) for diagnosing ureteric stones.
• Can identify non-stone causes of flank pain.
• Requires no contrast administration so avoiding chance of a
contrast reaction
• Is faster, taking just few minutes to image kidneys and
ureters.
• An IVU, may take hours to identify tprecise location of the
obstructing stone.
• Is equivalent in cost to IVU in high CT volume hospitals.

43. • A non-contrast CT-KUB radiation dose:
approximately 4.7mSv compared to 1.5mSv for IVU
• Ultra-low dose CT (ULDCT) lowers radiation
exposure (0.6–2mSv), but at the expense of lower
sensitivity (68–86%) for small (<3mm) ureteric
stones.
• Contrast-enhanced ultra low dose CT (CEULDCT)
uses contrast which increases sensitivity (97%) and
specifi city (100%) for detecting small ureteric stone
disease while limiting radiation dose to levels
comparable with IVU (1.7mSv vs 1.4mSv).
Bladder
• Bladder cancer staging (establishes local, nodal, and
distant spread).

45. • A significant advantage of MRI is excellent resolution of soft
tissue, without need for IV contrast in many situations.
• To obtain MR images, patient is placed on gantry that
passes through bore of magnet.
• When exposed to a magnet field of sufficient strength, free
water protons in patient orient themselves along magnetic
field’s z-axis.
• This is head to- toe axis, straight through bore of magnet.
• An RF antenna or “coil” is placed over body part to be
imaged. It is the coil that transmits RF pulses through
patient.
• When the RF pulse stops, protons release their energy,
which is detected and processed to obtain the MR image.

46. • Weighting of image depends on how energy is
imparted through physics of pulse sequence and
whether energy is released quickly or slowly.
• Images are described as being T1 or T2 weighted.
• T1-weighted images are generated by time
required to return to equilibrium in the z-axis.
• T2-weighted images are generated by time to
return to equilibrium in xy-axis.
• On T1-weighted MR images, fluid has a low SI and
appears dark.
• T2-weighted MR images have a high SI and appear
bright.

47. • In kidney this translates into the cortex having higher SI or being
brighter than the medulla, which gives off lower signal and is
darker.
• MRI has significant advantages over other imaging modalities.
• First, and most importantly, no risks are associated with secondary
malignancies from radiation exposure
• It is the modality of choice in patients who are pregnant, suffer
from renal insufficiency, and/or have an iodine contrast allergy.
• The contrast agents in MRI are noniodinated compounds.
• Iodinated compounds as used in CT imaging function by absorbing
x-rays.
• Gd-based contrast agents function on MRI secondary to
shortening the relaxation times of water. This results in an
increase in SI (enhancement), most commonly assessed in a T1
sequence.

49. • Staging of bladder and prostate cancer
(establishes local, nodal, and distant spread).
• Good for identifying seminal vesicle invasion.
• As with CT, oedema and fibrosis cannot be
reliably distinguished from tumour within bladder
wall, leading to ‘overstaging’ of cancer.
• Especially useful for diagnosis of
phaeochromocytomas (very bright image on T2-
weighted images).

50. • Localization of undescended testes.
• Identifi cation of ureteric stones, where ionizing
radiation is best avoided (e.g. pregnant women
with loin pain).
• In authors’ experience, few radiologists seem to
be able to confidently diagnose or exclude
presence of stones on MR urography, at least in
part because this test is still so seldom used.