Prostate

Question 1

Prostate: anatomy

1. Draw the prostate anatomy including muscles.
2. What are the components that can be seen on MR?
3. How does the composition of the central gland change over time?
4. Normal prostate volume?
5. Where are the neurovascular bundles located?
6. Why are the neurovascular bundles important?

Answer 1

1. See diagram.
2. Central gland (transition zone + central zone) & peripheral zone.
3. The TZ is the site of BPH. BPH is uncommon in young males so the TZ is small. However, it gets larger with BPH as men age, so the central gland is predominantly composed of TZ in older males.
4. 25ccs
5. Posterolaterally at the 5 and 7 o’clock positions (best seen on T1).
6. The NV bundles are the sites of capsular penetration, so T2 to T3 grade.

Question 2

Prostate gland zones:

• MR signal of the anterior fibromuscular zone (AFZ)?
• Central & TZs?

Answer 2

• AFZ: T1/T2 dark.
• Central & TZs: brighter than AFZ but darker than PZ.

Question 3

Prostate cancer:

Cx:

• What is normal PSA.
• Where does prostate cancer usually arise?
• Sx?

Px:

• Common cell type?
  
  • Less common cell types?
• Common location?
• Common/rare sites of spread?
• Typical LNs: first, then?
• Common sites of hematogenous spread?
• What type of lung mets are typical?

Answer 3

Cx:

• PSA: 1-4 ng/dL; >4 = elevated.
• Peripheral zone (70%) near rectum, which is why the DRE is useful.
• Urinary: nocturia, hesitancy, urgency, terminal dribble; hematuria (advanced disease); back pain (mets).

Px:

• 95% adeno (again, 70% are found in the PZ).
  
  • Rhabdomyosarcoma: younger men.
  • Leiomyosarcoma.
• Posterior/peripheral (70%); more than anterior/central (30%).
• Spread common: bladder, seminal vesicles; rare: urethra, rectum.
• LNs: pelvic first, then para-Ao and inguinal.
• Hemat: bone (90%), lung (45%), liver (25%), pleura (20%), adrenals (15%).
• Cannonball lung mets.

Question 4

Prostate cancer: Gleason score

1. What is used to score?
2. What is sampled in the Bx?
3. How is it calculated?
4. What does Gleason score predict?
5. What is the common convention for reporting Gleason scores?
6. What’s the cut-off for reporting a Gleason score?

Answer 4

1. Path specimens.
2. Sextants, done randomly, sampling the peripheral zone, apex, base.
3. Sum of 1st & 2nd most prevalent types of dysplasia on a scale of 1-5 w/ 5 being the most dysplastic.
4. 5-year biochemical risk-free survival after radical prostatectomy (Grade 1 = 96%; grade 5 = 26%).
5. The most common histologic pattern score is noted first, so a 4+3=7 is more aggressive than a 3+4=7.
6. Only those >=6.

Question 5

Prostate cancer: US & MR

1. Typical US appearance?
2. 2 primary indications for prostate MRI?
3. What are the key MR sequences for detecting prostate ca?
4. In which 3 instances may MRI miss prostate ca?

Answer 5

1. US: classically hypoechoic.
2. 1) high risk screening: neg Bx but high/rising PSA; 2) staging for Tx: to look for extracapsular extension.
3. T2: the peripheral zone is bright & prostate ca is dark. DWI: ADC will be dark, so diffusion restricted. Post-gad: enhances early & washes out, like breast ca.
4. 1) if the ca is not T2 hypo; 2) central zone ca as they are difficult to detect; 3) peripheral zone cas if the peripheral zone is not T2 bright.

Question 6

DDx T2 hypo peripheral zone?

Answer 6

1. Prostatitis: wedge-shaped, sharp border, mildly ADC-hypo, normal DWI.
2. Hemorrhage: T1W bright; T2W normal (not dark); DWI: no restriction.
3. Involutional changes from androgen-deprivational therapy:

Question 7

• What does the PI-RADS score tell you?
• Name the 5 PI-RADS categories & risks.
• What’s the sig of Gleason score 7?
• What differentiates PI-RADS 3, 4, 5?

Answer 7

• Risk of clinically significant cancer.
• PI-RADS categories:
  
  • 1: very low; clinically sig cancer highly unlikely.
  • 2: low; unlikely.
  • 3: intermediate; equivocal.
  • 4: high; clinically sig cancer likely.
  • 5: very high; highly likely.
• Gleason 7 = clinically sig prostate cancer.
• PI-RADS 3: ADC focal mild/moderate hypo; DWI iso/mild hyper.
• PI-RADS 4: 3 + DCE + or ADC focal markedly hypo; DWI markedly.
• PI-RADS 5: 4 but >=1.5cm; or definite extraprostatic extension.

Question 8

• If prostate MR findings are equivocal, what 2 things can be seen on MRS in prostate ca?

Answer 8

• Elevated choline peak
• Depressed citrate peak

Question 9

Prostate cancer: T-staging

• List the tumour stages (4).
• What’s the pivotal stage & how does Tx change there?
• How do T2a, b, c differ?

Answer 9

• See diagram.
• T2 to T3.
  
  • T2: tumour confined to prostate; Tx: radical prostatectomy.
  • T3: tumour bulges or extends through capsule & may involve seminal vesicles or nerve bundle; Tx: anti-androgen & radiotherapy.
• T2s:
  
  • T2a: <50% one lobe.
  • T2b: >50% one lobe.
  • T2c: both lobes.
    *

Question 10

Prostate cancer: N-staging

• Best sequence for nodes?
• N1, regional nodes?
• M1a, distant nodes?
• What stage do bone mets receive?

Answer 10

• DWI: all nodes will be bright.
• N1: pelvic wall, sacral, int/ext iliac.
• M1a: common iliac, Ao, inguinal, femoral, any beyond there.
• Bone mets = M1b.

Question 11

• Criteria for curable disease?
• Treatment for curable disease?

Answer 11

• Gleason <7; PSA<10 ng/L.
• Radical prostatectomy, brachytherapy or external beam radiation.

Question 12

Prostate cancer bone mets

• Best way to look for them?
• PSA level for ruling out bone mets?

Answer 12

• Bone scan.
• <20 ng/ml: has high predictive value for r/o bone mets.

Question 13

BPH

• Defn?
• Most common zone?
• Which lobe sticks up into the bladder the most?
• 3 Ix sequelae?
• Ix: classic finding.
  
  • Typical MR (3).

Answer 13

• Defn: >30ccs
• Most common zone: transitional.
• Which lobe sticks up into the bladder the most: median lobe of TZ.
• 3 Ix sequelae:
  
  • Outlet obstruction.
  • Bladder wall thickening.
  • Bladder tics.
• Ix: classic finding.
  
  • Typical MR (3): T2 hetero TZ; can restrict; may enhance w/washout.

Question 14

Prostate abscess

Ex:

• Prevalence & reason.
• Typical pt types (2) & age.

Sx: typical Sx?

Px:

• Typical bugs (2).

Ix:

• US: approach & app.
• CT: app.
• MR app.

Tx: (2)

Complication?

Answer 14

Ex:

• Rare b/c of abx for prostatitis.
• Diabetic & immunosupporessed; older (50-60yo).

Sx: dysuria, fever, suprapubic pain; UA = leukocytes.

Px:

• E.coli or Staph spp.

Ix:

• US: TRUS is very reliable; ill-defined hypoechoic areas w/enlarged/distorted gland; +/- heterog echoes.
• CT: well-defined low attenuation areas.
• MRI: T1 hypo, T2 hyper, Gd: peripheral enhancement; DWI: restricted diffusion. Thick-walled, septated, cystic lesion.
  
  • If chronic, can have a more Swiss cheese-like appearance, called “cavitary prostatitis”.

Tx: percutaneous transperineal or transrectal drainage.

Complication: emphysematous prostatitis;