Radiology Notes

My notes during radiology residency, fellowship, and beyond…

Archive for the ‘mri’ Category

Vascular Anomalies, ISSVA Classification

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2 categories: vascular tumors or vascular malformations. Distinction determines therapy.

Vascular Tumors

  • infantile hemangiomas: grow rapidly after birth, GLUT1+
  • congenital hemangiomas (RICH and NICH): fully mature at birth, GLUT1-
  • Tufted angioma
  • Kaposiform hemangioendothelioma
  • Spindle cell hemangioendotheliomas
  • Dermatologic acquired vascular tumors

Vascular malformations (slow)

  • capillary malformation (port-wine stain, telangiectasia, angiokeratoma)
  • venous malformation
  • lymphatic malformation

Vascular malformations (fast)

  • arterial malformation
  • arteriovenous fistula
  • arteriovenous malformation

PDF link

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Written by lmwong

April 23, 2012 at 12:57 pm

MRI Hand and Wrist anatomy link

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A nice PDF link to an old radiographics article diagraming MRI hand and wrist anatomy in a concise fashion: http://radiographics.rsna.org/content/8/6/1171.full.pdf

Written by lmwong

April 9, 2012 at 4:03 pm

Posted in hand, mri, msk, wrist

Red Marrow

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  • more water content, bright on T2
  • amorphous and feathery, flame shaped
  • metaphyseal and metadiaphyseal
  • smoking and obesity, middle aged females

Written by lmwong

July 12, 2011 at 7:32 am

Posted in bone, mri, msk

MRI Appearance of blood and timing

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T1 T2 Time Blood
It Be Iso Bright <2-4 hrs OxyHg
IDy Iso Dark 1-3d DeOxyHg
BiDy Bright Dark 3-7d Intracellular MetHg
BaBy Bright Bright 1-2 wks Extracellular MetHg
DooDoo Dark Dark >2 wks Hemosiderin

Written by lmwong

January 14, 2009 at 5:28 am

Posted in mri, neuro

Bright on T1

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  • Blood
  • Fat
  • Protein
  • Melanin
  • Contrast

Written by lmwong

April 29, 2008 at 2:51 am

Posted in differential, mri

Acute Ischemic Stroke

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Cytotoxic edema is cell death with efflux of K and influx of Ca, Na, and water. Edema peaks at day 7.

CT noncontrast

  • Hyperdense artery sign on brain windows = thrombus; MCA most common (asymmetric)
  • Loss of gray-white matter distinction, loss of insular ribbon;
  • Parenchymal hypodensity = edema/cell necrosis
  • Gyral swelling = 12-24hrs
  • Hemorrhagic transformation = 24-48hrs
  • if negative, get MRI
MRI
  • Perfusion defect = ADC dark, DWI bright
  • Edema = T1 low, T2 high
  • if MRI negative and still strong clinical suspicion, do MRA or CTA neck/head

Stroke Timing

Time CT MRI
Minutes no change absent flow void, arterial enhancement, DWI high
2-6 hrs hyperdense artery sign, insular ribbon sign brain swelling (T1), subtle T2 high
6-12 hrs sulcal effacement, decreased attenuation T2 high
12-24 hrs decreased attenuation T1 low
3-7 d max swelling
3-21 d gyral enhancement
30-90 d encephalomalacia, loss of enhancement

Which vessel territory?

Causes of acute stroke by age group
Pediatrics
  • CHD
  • Blood dyscrasias
  • meningitis
  • arterial dissection
  • trauma
  • extracorporeal membrane oxygenation (ECMO)
  • venous thrombosis
Young Adult
  • Cardiac emboli
  • ASD
  • drug abuse
  • arterial dissection
  • coagulopathy
  • venous thrombosis
Elderly
  • ASD
  • cardiac emboli
  • coagulopathy
  • amyloid
  • vasculitis
  • venous thrombosis

Written by lmwong

April 12, 2008 at 3:12 pm

Posted in ct, mri, neuro, stroke

L Spine MRI Dictation

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Indication: [x].

Technique: An MRI of the lumbar spine was performed utilizing the following sequences: [x]

Comparison: [x]

Findings: Normal lumbar lordosis is preserved. Lumbar vertebral heights and alignment are maintained. No expansile or destructive osseous lesion is seen. No focal disk herniation, spinal canal or neural foramina stenosis is identified. The conus and cauda equina appear normal; the conus terminates at the [x] level. No epidural mass or collection is seen.

Impression: Normal lumbar spine MRI.

Written by lmwong

April 9, 2008 at 11:04 am