JC Block C - Diagnostic Radiology - Urinary system Flashcards by Max Kam

Causes of renal pseudomasses

The renal parenchyma results from the fusion of several segments during intra-uterine life
 Each segment is functionally independent

 Abnormal fusion is possible

 lobulation/ junctional segment - pseudomass – normal variation***

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All modalities of urinary imaging

A. Plain radiograph (KUB):
B. Intravenous urogram (IVU):
C. Ultrasound:
D. Computed tomography:
E. Magnetic resonance imaging (MRI):
F. Arteriography:

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Function of Plain radiograph (KUB)

Can see:

Kidneys
 Calcification (calculi, Staghorn calculus)
 Size (2.5 vertebrae)
 Outline (masses)
 Position

Ureters
 Tips trans processes
 Cross pelvic brim at SIJ
 Run in paraspinal region
 calcification

Bladder
 Calcification
 Outline

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Intravenous urogram (IVU)

Structures seen

series of KUB radiographs with IV administration of iodinated contrast media:
Contrast excreted by kidneys (glomerular filtration) and can be seen on film

Opacifies:
 Pelvicalyceal systems
 Ureters
 Urinary bladder

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IVU sequence

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Lesions

Renal masses:
L = Polycystic kidney (enlarged kidney; round
areas of radiolucencies)
 R = Large renal cyst (well circumscribed)

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Lesion

Horseshoe kidney (joined at midline, increased risk
of RCC)

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Lesion

Transitional cell carcinoma of bladder

Stipple sign - trapping of contrast material within the interstices of a papillary growth produces a stippled appearance when viewed end on

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Function of Ultrasound in urinary system

 Renal size and morphology

 Renal parenchyma + abnormal calcifications: normal Dark cortex and echogenic/ fatty medulla

 Obstruction – hydronephrosis: dilated renal calyces

 Renal vessels – transplanted kidneys, renal artery stenosis

 Masses – cyst vs. solid masses E.g. bladder cancer (TCC)

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Lesion

Obstruction – hydronephrosis:
 Renal calyces are normally not seen
 In obstruction, there is backflow and static urine  calyces dilate to become visible
 The obstruction here is chronic because there is cortical thinning

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Lesion

bladder cancer (TCC):
 Intraluminal masses
 Color Doppler detects feeding blood vessels

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Lesion

Well-defined echogenic mass in the dependent portion of bladder

Doppler detects no vascularity within this mass

Likely a blood clot - resolves with bladder irrigation

Think causes of haematuria

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Computed tomography urinary system

Indications

 Further characterisation of abnormalities seen on IVU, KUB, US
 Renal colic
 Cancer staging
 Renal trauma
 CT angiogram for renal artery stenosis

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Study this

Anatomy:
Hypodense perirenal fat surrounds the kidneys

Fascia separates spaces (pathology originally spreads along the same space):
 Anterior Gerota’s fascia
 Posterior Gerota’s fascia
 Lateroconal fascia

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Lesion

obstructing calculus causing hydroureteronephrosis:

 Contrast is excreted normally from the left kidney
 But the right kidney has hydrnephrosis, hydroureter due to calculus = delay in
excretion of contrast

Lesion

bladder cancer:
 Mass projecting from bladder
 Filling defect when excrete contrast into bladder
 Early enhancement

MRI renal system

Indications

a) Further characterization of abnormalities seen on CT urogram
b) Cancer staging
c) +/- renal MRA

T staging for renal tumors

T staging:
 T1/T2: confined to kidney

 T3: extension into major veins/ perinephric tissues, but not into ipsilateral adrenal gland or beyond Gerota’s fasica

 T4: involves ipsilateral adrenal gland/ invades beyond Gerota’s fascia

 MRI is needed in T3/T4 to differentiate structures, not in T1/T2

Use of MRI in bladder cancer

Need MRI to distinguish:
 Non-muscle invasive (T2a) from invasive (T2b) tumor (disruption of hypointense rim)

 Microscopic (T3a) from (T3b) tumour extension

 T4 (e.g. invasion into uterus, vagina)

Urinary Arteriography

Indications

a) Diagnosis and treatment ofrenal artery stenosis
b) Embolization of bleeding tumors or points
c) Diagnosis and treatment of AVM

Lesion

renal artery stenosis (catheter inserted into renal artery  use balloon to open up the narrowing)

Fluoroscopy:

Types

Usage

Antegrade pyelogram:
Procedure:
 Puncture kidney percutaneously (US-guided)
 Inject contrast into the pelvicalyceal system

Retrograde pyelogram:
Procedure:
 ureteric catheter is inserted via the cystoscope into the ureter
 Contrast is injected via the ureteric catheter

Imaging study of choice for renal stones

Treatment options for renal stones

Ix for acute flank pain/ suspicion of stone disease:
 Noncontrast CT KUB

(ESWL = extracorporeal shock wave lithotripsy; URS = ureterorenoscopy; PCNL = percutaneous nephrolithotomy)

Indications for imaging acute pyelonephritis

Role of diagnostic imaging:  Not indicated in mild forms  To characterise severity and complications  Patients at risk, e.g. diabetic, elderly, immunocompromised  To assist diagnosis when the patient fails to respond to appropriate therapy within first 72 hours US – non-specific findings:  Hyperechoic/ hypoechoic/ both  Focal/ global renal enlargement  Vascular defect CT:  Striated nephrogram  Emphysematous pyelonephritis

Treatment of choice for renal stones based on size

steps in the differentiation of a renal lesion?

1. Is it a cyst?  benign 2. Does it contain macroscopic fat?  benign angiomyolipoma (AML) 3. Exclude tumor-mimics like infection and infarction, which usually present in different clinical settings. 4. Exclude metastatic disease and lymphoma; kidney involvement usually only seen in widespread disease

Case 1: |  F/57: chronic right loin pain

Dx: staghorn renal stone

Case 2:  Young lady: increasing abdominal mass  KUB: large soft tissue mass in left abdomen displacing bowel  Plain CT: large mass arising from left kidney; smaller masses in right kidney with fat densities Most likely Dx

angiomyolipomata

Case 3:  Young man: deranged renal function Dx

``` CT scans:  Multiple cysts replacing both kidneys  Some calcification in the walls of the cyst  Cysts also in the liver  Pancreas is normal ``` Dx: Polycystic kidneys

Case 4:  F/42  History of renal stones  C/o left loin pain and fever Imaging and Dx

 KUB: 3 calculi in left kidney US/ IVU to exclude obstruction in calyx or ureter: focally dilated upper pole calyx secondary to a calculus

Case 5:  M/52: left loin pain Dx

CT:  Right simple cyst  Left suspicious lesion  renal cell cancer

Case 6:  F/72: painless hematuria Features, Dx