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1. URINARY Radiology
Lecture : I

2. ❑The four basic examinations of the urinary tract are
ultrasound, intravenous urography (IVU), computed
tomography (CT) and radionuclide examinations.
❑MRI, arteriography and studies requiring catheterization
or direct puncture of the collecting systems are limited to
selected patients.
❑FDG PET- CT has limitations due to excretion of the
tracer in the renal tract and poor uptake in many
urological malignancies.
❑Ultrasound, CT and MRI are essentially used for
anatomical information. Radionuclide examinations is
functional study. IVU provides both functional and
anatomical informations.

3. Abdominal Radiography : KUB
❑Renal outline may be visible adjacent to the upper lumbar spine
and should be bilaterally symmetric and measure between 3 and 4
lumbar vertebrae in length.
❑The ureters are examined by knowledge of their normal course.
❑40% to 60% of urinary tract stones are diagnosed on plain
radiographs.
❑The sensitivity for detection of stones is limited when the calculi
are small, of lower density composition, or when there is
overlapping stool, bony structures, or air obscuring the stones in
addition to other calcifications in the abdomen including vascular
calcifications, pancreatic calcifications, gallstones, ...

4. ❑Phleboliths have lucent centers.
❑Emphysematous pyelonephritis, may be diagnosed on plain
films by mottled or linear collections of air within the renal
parenchyma.
❑Bony lesions, such as sclerotic bony changes, can suggest
metastatic prostate cancer, and lytic bony lesions can be seen
with disseminated RCA.
❑The bony changes of renal osteodystrophy may be seen.
❑Vertebral anomalies are associated with congenital
malformations of the urinary tract.

5. The normal adult renal
length, measured by
ultrasound,is 9–12 cm.
Renal length varies with
age, being maximal in the
young adult. There may be
a difference between the
two kidneys, normally of
less than 1.5 cm
Ultrasound
Ultrasound is the first line investigation in most patients.

6. Small kidney

7. Large kidney

8. Urography
❑Using intravenous iodinated contrast medium.
❑It has largely been replaced by a combination of ultrasound and
CT urography:
- CT has the advantage of being highly sensitive for the detection of
stones, including those that may be radiolucent on plain film.
- Allows the characterization of renal lesions and the detection of
ureteric lesions.
- Demonstrates the surrounding retroperitoneal and abdominal
tissues.
- CT overcomes the overlap of superimposed tissues, which can
cause difficulty when interpreting traditional IVU.

9. Indications

10. Notes on interpretation of IVU
❑Kidneys should be in their normal positions. The left kidney is usually higher
than the right.
❑Whole of both renal outlines should be identified.
❑The renal parenchymal width should be uniform and symmetrical, between
2and 2.5cm.
❑Minor indentations between normal calices are due to persistent fetal
lobulations. All other local indentations are scars.
❑A bulge of the renal outline may be due to a mass or a cyst, which often
displaces and deforms the adjacent calices. An important normal variant
causing a bulge of the outline is the so called ‘splenic hump’.
❑The normal length of the adult kidney at IVU is between 10 and 16 cm (higher
than size measured on U/S mainly due to radiographic magnification of the
image).

12. ❑Calices : evenly distributed and reasonably symmetrical. Cupped shaped
Caliceal dilatation : due to destruction of the papilla or obstruction.
❑The normal renal pelvis and pelviureteric junction are funnel shaped.
❑The ureters are usually seen in only part of their length on any one film
of IVU because of obliteration of the lumen by peristalsis.
❑Dilatation of the renal pelvis and ureter may be secondary to
obstruction but there are other causes (e.g. congenital variant or
secondary to vesicoureteric reflux).
❑Filling defects within the pelvis and ureters should be identified.
❑Bladder should have a smooth outline. Normal smooth indentations
from above owing to the uterus or the sigmoid colon, and from below by
muscles of the pelvic floor.

14. CT urography

15. Radionuclide examination
• Renogram : measures renal function.
• Dimercaptosuccinic acid (DMSA) scan : Scans renal
morphology and for evaluating renal scarring.

16. Renogram
❑Using gamma camera.
❑The two agents of choice are:
- 99mTc Diethylene Triamine Pentacetic Acid ( 99mTc DTPA) and
- 99mTc mercaptoacetyl triglycine (MAG3).
❑Serial images over 20 minutes show progressive excretion and clearance
of activity from the kidneys. Computerized quantitative assessment
enables a renogram curve to be produced and the relative function of
each kidney to be calculated.
The main indications for a renogram are:
❑ Measurement of relative renal function in each kidney – this may help
the surgeon decide between nephrectomy and more conservative
surgery.
❑ Investigation of urinary tract obstruction, particularly pelviureteric
junction obstruction.
❑ Investigation of renal transplants.

17. Tc99m DTPA Renogram
A- Vacular phase
B- Filtration phase
C- Excretion phase
D- Renogram curve

18. Retrograde and antegrade pyelography
❑In situations where the information cannot be achieved by less invasive
means, e.g. IVU, CT or MRI to confirm a possible transitional cell carcinoma
in the renal pelvis or ureter.
Voiding cystourethrogram (micturating cystogram)
❑The entire process is observed fluoroscopically to identify vesicoureteric
reflux. The bladder and urethra can be assessed during voiding to
demonstrate strictures or urethral valves
Urethrography
❑Ascending and voiding cystourethrography.
❑The usual indications for the examination are the identification of urethral
strictures and to demonstrate extravasation from the urethra or bladder
neck following trauma.
Renal arteriography
❑It is mainly used to confirm the CT or MRI findings of vascular anatomy
prior to renal surgery and to confirm renal artery stenosis prior to
percutaneous balloon angioplasty

20. Urinary tract disorders

21. Acute pyelonephritis
➢Usually ascending infection in 85% of cases.
➢Stones, congenital anomalies, obstruction, VUR, pregnancy,
diabetes can predispose to infection.
➢Most patients with acute urinary tract infection do not
require urgent imaging investigations.
➢In patients presenting with signs of infection associated with
pain, particularly if the symptoms are not settling with antibiotics,
ultrasound and plain films may diagnose underlying stones,
obstruction or abscess formation.
➢Investigation of the renal tract is indicated in all children with a
confirmed urinary tract infection. The aim is to identify an
abnormality, such as reflux, which could lead to
renal damage, if left untreated .

22. ❑Radiological features
❑IVU: Focal or diffuse renal swelling ( due to oedema ), Delayed
and poor pelvicalyceal system filling and Dense, persistent or
striated nephrogram may be seen.
❑US Normal in 80%, focal (lobar) or diffuse renal swelling , the
affected segments are hypoechoic with reduced corticomedullary
differentiation, identify any stones or scarring, and to demonstrate
or rule out hydronephrosis or hydroureter.
❑CECT / MRI : shows areas of patchy areas of abnormal ( increased
/persistent / striated/or reduced) parenchymal enhancement.
❑DMSA Can demonstrate renal scar.
• Complications: abscess formation, emphysematous
pyelonephritis, xanthogranulomatous pyelonephritis, cortical
atrophy and renal failure.

24. Tuberculosis
❑Usually blood borne spread from a lung focus. The kidneys are the
2nd commonest site of TB.
❑In the early stages of the disease, the ultrasound and IVU may be
normal.
IVU/CT:
❑Although both kidneys are seeded, clinical manifestations are usually
unilateral (>70% of cases)
❑Early: an enlarged kidney, irregularity and destruction of ≥1
papillae (resembling papillary necrosis),.
❑Late: an atrophic kidney
Renal Calcifcation in 30%. Usually irregular calcification, cloudy dilated
calyces, calcified cavities or pyonephrosis , progressing to TB
autonephrectomy. Calcifcation implies healing but does not mean that
the disease is inactive.
❑Ureteric calcifcation: this is the 2nd commonest site of
calcifcation with a typical beaded appearance.
❑Calcifcation of the bladder, vas deferens and seminal vesicles are
rarely seen

25. ❑Cavitations: these are usually irregular, communicate with the
collecting system, widespread cavitations may mimic hydronephrosis
❑Fibrotic strictures: these can occur anywhere within the renal tract
– Hydrocalycosis: due to a partial stricture of a major
infundibulum (the infundibulum appears ‘cut off’ with a complete
stricture) creating a ‘phantom calyx’
– Ureter: a ‘corkscrew’ appearance (due to multiple stenoses) or a
‘pipestem’ appearance (due to a rigid and aperistaltic ureter)
– Renal pelvis: a ‘purse string’ stenosis
❑ Bladder:
– Early: trabeculation, bladder wall irregularity, a slight decrease
in capacity
– Late: a thick-walled small-capacity bladder demonstrating
calcification. Bladder TB is almost always associated with renal TB
and often there is
VUR into a widely dilated upper tract .

27. Renal abscesses
- A heterogeneous renal cystic mass with thick
fluid and gas contents showing enhancing thick
irregular wall /± perinephric inflammation on
CT and MRI
Perinephric abscess
- A perinephric rim-enhancing fluid collection
- Loss of the renal outline (±psoas shadow)
- Poor/or no renal excretion
Pyonephrosis
- Pus within dilated pelvicalyceal system
- An obstructed kidney (e.g. secondary to a
calculus or PUJ obstruction).
- There may be a renal or perinephric abscess
- Thickening of the renal pelvis (>2 mm)

28. Emphysematous pyelonephritis
❑A rare fulminating form of acute
necrotic pyelonephritis due to gas-
producing organism (usually E.
coli), associated with diabetes and
obstruction.
Emphysematous pyelonephritis
Gas within the renal
parenchyma, high mortality rate
(>60%) and it may require
nephrectomy.
Emphysematous pyelitis has a
lower mortality rate, and
percutaneous drainage and
antibiotics may be sufficient

29. Xanthogranulamatous pyelonephritis
-Chronic pyelonephritis complicating chronic UT infection and
obstruction (A renal struvite / staghorn calculi (70%).
-Associated with diabetes
-May be diffuse (common) or focal (uncommon) forms.
-Enlarged (global or focal) non-excreting kidney and dilated
affected pelvicalyces
-Multiple non- or rim-enhancing low attenuation areas (-15 to -20
HU)
-Perinephric extension (± a thickened Gerota’s fascia) is common,
hilar/ para-aortic adenopathy.

30. Chronic pyelonephritis (reflux nephropathy)
➢Most damage occurs in the first years of life.
➢The severity of reflux diminishes as the child gets older.
➢The condition is often bilateral and asymmetrical.
➢The signs of reflux nephropathy are:
• Local reduction in renal parenchymal width (scar formation).
The distance between the calix and the adjacent renal outline is
usually substantially reduced and may be as little as 1 or 2 mm.
The upper and lower calices are the most susceptible to damage
from reflux. IVU, DMSA radionuclide scans and ultrasound are all
useful for demonstrating cortical scars.
• Dilatation of the calices in the scarred areas. The dilatation is
the result of atrophy of the pyramids.
• Overall reduction in renal size partly from loss of renal
substance and partly because the scarred areas do not grow.
• Dilatation of the affected collecting system from reflux may be
seen.
• Vesicoureteric reflux may be demonstrated at micturating
(voiding) cystography.

31. Shrunken kidney with multiple scars and
pelvicalyceal dilatation