Radiology Notes

My notes during radiology residency, fellowship, and beyond…

Upper Limits of Normal

with one comment

if you must be a bean counter… Walls

  • Appendix = 3 mm
  • Gallbladder wall = 3 mm
  • Bowel Wall = 3 mm
  • Stomach Wall = 7-10 mm
  • Stomach Folds, fundus = 10 mm
  • Stomach Folds, antrum = 5 mm
  • Left Atrium = 4 mm
  • Left Ventricle = 12 mm
  • Esophagus = 3 mm
  • Vessel = 1 mm
  • Uterine wall during pregnancy = 3 mm
  • Endometrial wall = 16 mm (secretory phase), 5 mm (postmenopausal)
  • Bladder (distended) = 5 mm
  • Common carotid artery = 0.8 mm
  • pericardial wall = 1-3 mm

Lumen Diameters

  • Colon = 5 cm
  • Cecum = 8 cm
  • Small Bowel = 3 cm
  • Appendix = 6 mm
  • CBD = 6 mm (AFIP: not including wall, 5 mm, 6-7 mm equivical)
  • Gallbladder = 4 cm
  • trachea = 25 mm
  • Benign extra-axial CSF space >5 mm

Miscellaneous

  • Air-fluid levels = 2-5 cm
  • Liver span = 15.5 cm
  • Spleen span = 12-14 cm
  • Hiatal width = 15 mm
  • Esophageal folds = 3 mm
  • ankle joint space = 3-4 mm
  • Achilles tendon thickness = 8 mm
  • Boehler’s angle = 28-48 degress
  • cerebellar tonsils < 10y = <6 mm; >10y = ❤ mm
  • Peak Systolic Velocity <125cm/s
  • filum terminale <1.5 mm
  • atlantodental distance = 3 mm adults; 5mm kids; 8mm Downs
  • AC joint <8 mm
  • CC joint <13 mm
  • ankle mortise = 3-4 mm
  • cartilaginous cap (osteochondromas) <1 cm CT; <2 cm MRI
  • pituitary gland height = 3-8 mm adults; <10 mm puberty; >10 mm during pregnancy
  • Ovarian volume: <6y = 1cm^3, 6-10y = 1.2-2cm^3, 11-12y = 2-2.5cm^3, older = 8cm^3
  • Heel pad = 2.5 cm
  • Mean Sac Diameter – Crown Rump >5 mm
  • Yolk sac = 5 mm
  • Gallbladder polyp <5 mm
  • Uterine Wall (important in interstitial ectopic pregnancy) = 5 mm
  • Thecal sac AP = >7 mm c-spine; >10 mm L-spine
  • pineal gland = 11 mm
  • pituitary infundibulum = 2 mm
  • Welcher basal angle < 140 degrees on x-ray, < 120 degrees on MR (< 115 degrees for kids); platybasia
  • pre-dentate space >2.5 mm in adults or >4.5 mm in kids = atlantoaxial subluxation
  • foramen cecum < 10 mm
  • vestibular aqueduct <1.5 mm

Bone Displacement

  • humeral head >1 cm
  • radial head >3 mm
  • prosthesis to bone <2 mm

Spleen size by age

  • 0-3m = 6 cm
  • 3-6m = 6.5
  • 6-12m = 7
  • 1-2y = 8
  • 2-4y = 9
  • 4-6y = 9.5
  • 6-8y = 10
  • 8-10y = 11
  • 10-12y = 11.5
  • 12-15y = 12
  • 15-20y = 12 (M), 13 (F)

Liver size by age

  • 1-3m = 4-9 cm
  • 4-6m = 4.5-9.5 cm
  • 7-9 m = 6-10 cm
  • 1-2y = 6.5-10.5 cm
  • 3-4y = 7-11.5 cm
  • 5-6y = 7.5-12.5 cm
  • 7-8y = 7.5-13
  • 9-10y = 7.5-13.5 cm
  • 11-14y = 8.5-14 cm
  • 15-16y = 9.5-14.5 cm

Fetal Heart Rate

  • 2 mm embryo: 75 beats per minute
  • 5 mm embryo: 100 beats per minute
  • 10 mm embryo: 120 beats per minute
  • 15 mm embryo: 130 beats per minute
  • followup scan if <100 at 5-9 wks, <110 bpm at 10-15 wks

Aorta (using true short-axis dimension per Radiographics)

  • Thoracic Aorta = 4-5 cm ectasia; >5 cm aneurysm; 6 cm or 5 mm/6mo = surgery
    • root = 3.6 cm
    • ascending = 3.5 cm
    • arch = 2.9 cm
    • descending = 2.4-2.6 cm
  • Abdominal Aorta = 2.5-3 cm ectasia; >3 cm aneurysm

Vessels

  • Iliac artery = 1.5 cm
  • Pulmonary Arteries = 2.9 cm (pulm arterial HTN)
  • Portal Vein = 13-15 mm (portal HTN)
  • Splenic vein and SMV = 10 mm (portal HTN)
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Written by lmwong

January 16, 2010 at 10:15 am

Posted in Uncategorized

One Response

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  1. This is a very helpful refresher for my interview tomorrow!

    Shaunda

    November 30, 2010 at 8:46 pm


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