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Abdomen

HU

  • Fat < -10HU
  • Cyst 0 - 20 HU
  • Lesion Enhance = > 20 HU
  • Luminal Blood (GI Bleed)
    • Usual intestinal content: 0-15 HU
    • Unclotted blood: 30 - 45 HU
    • Clotted blood: 45 - 70 HU
    • Recent GI bleed: > 60 HU

Stomach

Gastric Mass

Bowel

Bowel Dilate

  • Small bowel: CT (≥ 2.5 cm), Plain film (≥ 3 cm)
  • Large bowel: ≥ 6 cm
  • caecum/sigmoid: ≥ 9 cm

Bowel Wall Thickening

Appendix

Appendicitis

Measurements

    • Diameter of the appendix (mid portion, short-axis plane):
    • < 6, 6 - 10, > 10 mm
    • Tip diameter (short-axis plane)
    • < 6, 6 - 10, > 10 mm
  • Thickness of the wall of the appendix (mid portion, outer wall to the inner mucosa)
    • Mucosal hyper-enhancement (relative to small bowel): Yes, No
    • Adjacent fat stranding: Yes, No
  • Appendicolith: Yes, No
  • Focal thickening of the cecum at the base of appendix: Yes, No
  • Extra luminal periappendiceal gas: Yes, No
  • Gas within the lumen of the appendix: Yes, No
  • RLQ collection (area of fluid attenuation with an enhancing wall): Yes, No

* = significant variable

Score

  1. Appendicitis definitely absent

  2. Appendicitis unlikely

  3. Indeterminate

  4. Appendicitis likely

  5. Appendicitis definitely present

HBP

IHD

Normal Size < 3 mm

CBD

  • < 0.6 cm (< 0.9 for post-cholecystectomy)
  • Age > 60 yrs can dilate 0.1 cm / 10 yrs

Gallbladder

  • Long = 9 - 11 cm
  • TV < 4 cm
  • Wall thickness < 3 mm

Gallbladder Hydrops

  • >4 cm transverse measurement
  • >9 cm longitudinal measurement
  • straight or convex borders

Liver

Size

  • Span 15 - 17 cm (sagital, at MCL)

Fatty Liver

In NC

  • Liver < 40 HU
  • Spleen - Liver > 10 HU

In PV

  • Spleen - Liver > 25 HU

In MRI: DIXON

  • \(S_{IP} =|S_{water} + S_{fat}|\)
  • \(S_{OP} =|S_{water} - S_{fat}|\)
\[ FSF = \frac{S_{fat}}{S_{water} + S_{fat}} = \frac{S_{IP} - S_{OP}}{2S_{IP}} \]

In NASH, non-alcoholic

Steatosis PDFF Threshold
0 vs ≥ 1 6.4
≤ 1 vs ≥ 2 17.4
≤ 2 vs 3 22.1
- Img

Hyperdense Liver

Pancreas

  • Main pancreatic duct diameter < 3 mm

Pancreatitis

  • Necrotizing if < 30 HU in pancreatic parenchymal phase
  • Img Summary

Worrisome Feature

  • cyst ≥3 cm
  • thickened and enhancing cyst wall
  • enhancing mural nodule <5 mm
  • main pancreatic duct 5-9 mm
  • lymphadenopathy
  • abrupt change in calibre of the pancreatic duct with distal pancreatic atrophy
  • cyst growth rate ≥5 mm in two years
  • elevated CA 19-9

Follow-up

  • largest cyst <1 cm: CT or MRI/MRCP in 6 months, then every 2 years if no change
  • largest cyst 1-2 cm: CT or MRI/MRCP 6 monthly for 1 year, then yearly for 2 years, then lengthen interval up to 2 years if no change
  • largest cyst 2-3 cm: EUS in 3-6 months, then lengthen interval up to 1 year alternating MRI with EUS as appropriate

Adrenal

  • APW = (E - D) / (E - U) x 100
  • RPW = (E - D) / E x 100

Adenoma: APW > 60, RPW > 40

D = delayed 15 minute

  • Formula

Spleen

  • < 12 cm (Normal)
  • 12 - 15 cm (Mild splenomegaly)

  • 15 cm (Mark splenomegaly)

Kidneys

Echo: slightly < liver

Size

Normal

  • Long < 10 - 12 cm
  • Cortical thickness > 1 cm

Abnormal

  • Long < 8 cm (kidney disease)

Renal Mass: Solid vs Cystic

  • > 70 HU → Hemorrhagic cyst
  • 20 - 70 HU → Danger Zone
  • 0-20 HU → Cyst
  • < - 10 HU → AML, ccRCC
  • Fig

Cyst (Bosniak)

Solid component < 25%, Exclude infect/inflam/vascular

  • II (≤ 2 mm)

    • Few (1-3) septa (may enhance, may calc)
    • In NC: Homo -9 to 20 HU, or ≥ 70 HU
    • In PV: Homo 21 - 30 HU
    • Renal protocol: Homo > 20 HU (may calc)
    • Homo Too Small to characterize

  • IIF

    • Smooth minimally thick (3 mm) wall or septa
    • Smooth thin (≤ 2 mm) many (≥ 4) septa
  • III
    • Thick (≥ 4 mm) septa or wall
    • Protrusion ≤ 3 mm, obtuse angle
  • IV
    • ≥ 4 mm protusion, acute angle

Parapelvic vs Peripelvic cysts

Parapelvic cysts

  • originate from the adjacent parenchyma and protrude into the renal sinus
  • เป็น simple cortical cyst ที่ยื่นเข้าใน renal sinus

Peripelvic cysts

  • originate within the sinus itself and have a lymphatic origin
  • IMG

Bladder

Wall thickness

  • < 0.8 cm (Collapse)
  • < 0.4 cm (Distend)

Residual Urine < 100 ml

Reproductive

Uterus

  • Size < 5 x 4 x 8 cm (AP x TV x Long)
  • ETT
    • < 1.5cm (pre-menstrual)
    • < 0.5 cm (post-Rt 25 ml (Normal) D.T. CT

Prostate

  • < 25 ml (Normal)
  • 25 - 40 ml (Prominent)

  • 40 ml (BPH)

Gleason

PSA Rt

  • PSA (normal): 0 - 4

PSA Kinetics

  • PSA velocity (PSAv)
    • Refers to the absolute rate of PSA change over time
    • abnormal if > 0.35 or 0.75 ng/ml/yr.
  • PSA doubling time

Testis

  • Normal Size: 5 cm in length, 2–3 cm in its transverse

Epididymitis & Epididymo-orchitis

  • Prehn sign positive: pain associated with epididymo-orchitis improves when the testicle is elevated

Peritoneum

Bone

Compression Fx

Osteoporotic spine fractures can be graded with the Genant classification of vertebral fractures on vertebral height loss as:

  • mild: up to 20-25%
  • moderate: 25-40%
  • severe: >40%

Spondylolisthesis

  • grade I: 0-25%
  • grade II: 26-50%
  • grade III: 51-75%
  • grade IV: 76-100%
  • grade V (spondyloptosis): >100%

Artery

SMA Syndrome

  • Aorto-mesenteric angle < 22 degree (sagital)
  • Aorto-mesenteric distance < 8mm (axial)