Lecture 10: Radiology of the Renal Tract

Question 1

Role of imaging

Answer 1

1. History: Listen, Question, Diagnose (90%)

2. Tests: Imaging to confirm diagnosis (+ additional specific location) or find something new

Question 2

6 Types of Imaging

Answer 2

1. Plain Film/X-ray
2. Intravenous urogram IVU (Plain x-ray + injected contrast)
3. Ultrasound
4. CT
5. MRI
6. Nuclear Medicine

Question 3

Plain Film

Answer 3

First resort
Cheap + Uses radiation
1. Radio-opaque stones
2. Non-radio-opaque stones
3. Uric Acid
- Gout patients have uric acid filled/calcium absent stones –> suffer pain but cannot see stones (non-radio-opaque)
Note: Little stones cause biggest problems (enter ureter 5nm)

Question 4

Pretest probability

Answer 4

Patient: Maori, male, gout, renal colic
= increased likelihood of uric acid stone
Plain x-ray wont help locate

Question 5

Symptomatic differences b/w Appendicitis and Renal Colloid

Answer 5

Appendicitis: fever. Painful to breath –> dont want to move at all (burst peritoneum)
Renal Colloid: Ureters run down Transverse processes –> Loin-Groin pain (referred pain in testes)
- occurs in waves from high up –> extremely restless
- worst pain possible
Blood in urine

Question 6

IVU

Answer 6

Intravenous Urogram

• plain x-ray + injected contrast
  e. g. Blockage(tumour, stone, blood clot) –> Dye held in major calyces

Question 7

Ultrasound

Answer 7

High frequency Sound waves
No radiation –> first tool for Children
Operator dependant (crisp picture with good technique)
- echogenic line (capsule), high echogenicity vessels
Patient body habitus dependant (Fatter –> decreased chance of sound waves travelling as far –> decreased clarity kidney)
Useful for:
1. Renal stones 2. Renal obstruction 3. Renal mass 4. Bladder lesions (cannot assess ureters)

Question 8

Why cant a US assess ureters?

Answer 8

US ideal when water present

- air is deaf to Ultrasound

Question 9

CT

Answer 9

More accurate
Soft tissues assess, fluid, calcification
Expensive
significant radiation
may need IV contrast dye
Useful for: Stone (calculi), tumour, trauma, infection
- Non light = Blockage
- cancer in renal vein image*

Question 10

MRI

Answer 10

Excellent Soft tissue evaluation and fluid
Expensive
No radiation, Use on someone who is comfortable;patient;doesnt wriggle;no traumatic experiences
Longer scan time 30-45mins
Useful for:
1. Soft tissue abnormality
2. Renal tumour
3. Infection
Can have arteriogram w. MRI

Question 11

Nuclear Medicine

Answer 11

Gamma camera + Radioisotopes (Inject Radioactive dye)
Functional Test: assess Function and Excretion of kidneys
Still involves radiation
Useful for obstruction

Question 12

Renal imaging

Answer 12

1. Antenatal (pre-birth)
2. Pediatrics
3. Adult
   Differ by:
4. Clinical concerns (examination skills)
5. Radiation issues (child/baby/teenager vs adult)
   Note: need to do a discussion re balance of risks
   - IF the benefits outweigh the theoretical risks, then tend to do it

Question 13

Antenatal Renal imaging

Answer 13

1. Congenital abnormality (agenesis, polycystic kidneys, multi-cystic dysplastic)
2. Obstructed kidneys (PUJ, posterior urethral valve)
3. Reflux
   Note: all can be skilfully identified and treated if had correct clinical history and imaging

Question 14

Antenatal Congenital abnormality: Agenesis (re. renal imaging)

Answer 14

No kidneys
- will survive until born
- due to circulation passing through placenta in womb
Therefore need to diagnose early
Clue: Baby tends to pee into amniotic fluid –> Decreased fluid

Question 15

Antenatal Congenital abnormality: Polycystic Kidney (re. renal imaging)

Answer 15

abnormal kidney development –> decreased function
- sometime only effects one of the kidneys
Bilaterally enlarged echogenic kidneys (large and non-functioning)

Question 16

Antenatal abnormality: Reflux (re. renal imaging)

Answer 16

Ureters enter at a steep angle
Contracting bladder should temporarily close the ureter to pee out front
Ureter at steep angle –> patient pees straight up –> “water hammer” back up into kidney –> kidney damage –> young teenagers with kidney damage –> Need transplant or Dialysis

Question 17

Dilated and Thin cortex

Answer 17

dont know if is PUJ or reflux

more tests required

Question 18

Antenatal Obstructed abnormality: PUJ (re. renal imaging)

Answer 18

Little boys w membrane b/w bladder and urethra in penis –> blocks outflow of bladder –> nothing can empty –> dribble urine

Question 19

MCU

Answer 19

Micturating Cystourethrogam

- Vesico-ureteric reflux (watch baby pee)

Question 20

Posterior Urethral valves

Answer 20

Posterior urethral valve (PUV) disorder is an obstructive developmental anomaly in the urethra and genitourinary system of male newborns. A posterior urethral valve is an obstructing membrane in the posterior male urethra as a result of abnormal in utero development.

Question 21

Clinical scenario: Young 25 yr old man, left flank radiation to groin, haematuria, no fever, normal WCC

Answer 21

Likely to be Renal Colic
- cant see stone in x-ray
1. US : show kidney stone location and dilation
2. CT: coming down to groin + blood
Note: not one answer, depends on the clinical story

Question 22

Renal Colic

Answer 22

12% of population will have urinary stone during lifetime (common)
Severe abdominal pain, radiating to gonad
“Writhing in pain” : difficulty lying still
Common stone location: narrowest part of ureter as entering base of bladder

Question 23

Calculi

Answer 23

“stranding”: streaking of fat. epicentre of problem
- swollen and stranded kidney with non-moving stone
Peri-nephric stranding: around kidney
Peri-ureteric stranding: ureter
Hydronephrosis

Question 24

Stone size and CT

Answer 24

Size of stone correlates with treatment
>6nm = 99% likelihood of eventual need for intervention = otherwise will just get infected (WONT PASS STONE)
-appears as swollen/fat ureter, almost holding the stone

Question 25

Clinical scenario: 42 year old woman, right flank pain, fever, high WCC

Answer 25

Kidney Infection “pilonephritis” –> abscess puss
Diagnosis: US - local and targeted examination
- Puss: appears as grey speckles
- Abscess: mass hanging off kidney
Need to drain both puss and abscess
CT: could be tumour or abscess. But clinical story proves it isnt cancer

Question 26

Clinical scenario: elderly 85 yr old man, recurrent urinary tract infection

Answer 26

Note: unusual for men to get urinary tract infection
1. US : enlarge prostate surrounding the bladder
- both kidneys markedly Dilated and Thin –> long term problem of decreased renal function
2. Catheter into enlarged prostate –> prostates squeezes around prostatic urethra –> obstructs outflow of bladder –> infect bladder
Symptoms:
a) peeing frequently
b) Artificial dehydration: tend to drink less after 3pm

Question 27

Clinical scenario: 22 yr old woman, decreased renal function, high urea and creatinine

Answer 27

Polycystic kidneys –congenital/hereditary

• Slow penetrating gene: only occur sin 20’s maybe early 30s –> (potentially passed onto future generations)
• By now kidneys are no longer functioning well
• associated with cysts in liver and pancreas
  1. US: non-obstructing cysts replace nephrons/glomeruli –> kidneys less able to function
  2. Dialysis if full kidneys

Question 28

Clinical Scenario: 25 year old man crashed his mountain bike in the forest

Answer 28

History: how he came off his bike, what hit what
Blood in urine? : shattered kidneys + soft tummy (kidneys are retroperitoneal, sit in own compartment)
Bleeding Retroperitoneal kidneys –> sit in own compartments shielded by fascia –> bleeding w/o blood appearing in abdomen –> Decreased BP, white, tachycardia
Treatment: LEAVE and support retro-peritoneal tamponade (be aware are dealing with a potentially dangerous situation)
CT: haematoma shows spilt renal artery/kidney. partially functioning. injury has gone through to liver OR kidney completely torn off –> no longer functioning at all