CT vs. MRI

[Reborn24]

When it comes to brain hemorrhages, which is typically used?

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[CeLo]

CT is the best for brain hemorrhages (never use contrast when looking for a hemorrhage). Sorry I don't have more explanation as to why, I just skimmed this in my notes.

 

[Reborn24]

CT is the best for brain hemorrhages (never use contrast when looking for a hemorrhage). Sorry I don't have more explanation as to why, I just skimmed this in my notes.

how about infarcts. what is better?

 

[UCLAstudent]

how about infarcts. what is better?

In the head? Diffusion-weighted MRI is great for acute stroke. It is usually done in combination with a perfusion MRI.

 

[ljl1982]

how about infarcts. what is better?

http://www.emedicine.com/emerg/topic824.htm

CT is the imaging procedure of choice in evaluation of acutely injured patients or patients with acute neurologic deficit. Quick, easy, reliable, and routinely available, CT is valuable in making a firm diagnosis, as well as in excluding alternative diagnoses or the sequelae of other pathology, even in uncooperative patients. Patient monitoring is simple and safe, and CT is compatible with patient stabilization devices. Identification and localization of calvarial fractures and bony/metallic fragments are easily achieved. Assessment for acute hemorrhage and mass effect is optimal.
Contrast infusion is rarely indicated in the search for mass lesions or vascular pathology, except in patients with a history of human immunodeficiency virus infection and neurological examination abnormalities.

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MRI is valuable in the subacute setting following initial resuscitation (eg, child abuse, shearing injuries), as well as for identifying subtle abnormalities (eg, posterior fossa and brainstem injury, cortical contusions, shearing injury) and as a method to date the injury (eg, child abuse, parenchymal hemorrhage). Appropriate patient monitoring, however, is difficult and unreliable due to strong magnetic fields, time-varying magnetic gradients, and restricted access to the patient. Patient motion, due to the extended imaging time, reduces the chances of obtaining studies adequate to achieve final diagnosis. Faster machines and sequences, as well as MRI units that are more open and comfortable for unstable or acutely injured patients, are expected to improve the imaging process in the future.

The routine MRI protocol varies considerably based on strength of the unit's field, machine capabilities, and suspected diagnosis. Most centers perform sagittal T1-weighted and axial T1- and T2-weighted sequences of the brain routinely, with the addition of specific additional sequences depending on the clinical indications. T2-weighted gradient echo sequences are more sensitive for subacute/chronic parenchymal hemorrhage/shearing injuries, while fluid-attenuated inversion recovery (FLAIR) sequences have been shown to be more sensitive for subtle subarachnoid blood. Magnetic resonance angiography and venography, diffusion and perfusion imaging, and spectroscopy may all be valuable in selected circumstances.

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[jameslynton]

I agree with l1982 - however - find I visually have more detail of the structure with an MRI. You can see damage and bleeding with both. The CT scan looks gloopy to me. You know about where the issues are but you just don't see the detail like an MRI gives.
So in the end - what it comes down to is which one gives you the most information for what you are doing. If you want a general idea at a cheap cost CT - if you want detail and to figure the exact area - MRI. I am high visual person. So it may come down to how you learn/get information.
my .02s

 

[Hurricane]

I agree with l1982 - however - find I visually have more detail of the structure with an MRI. You can see damage and bleeding with both. The CT scan looks gloopy to me. You know about where the issues are but you just don't see the detail like an MRI gives.
So in the end - what it comes down to is which one gives you the most information for what you are doing. If you want a general idea at a cheap cost CT - if you want detail and to figure the exact area - MRI. I am high visual person. So it may come down to how you learn/get information.
my .02s

You don't need to see all of that detail when someone comes in with a suspected head bleed. You just need to know bleed or no bleed, and what kind (SDH, EDH, SAH, ICH), and if there's mass effect. Increasing the level of detail beyond that isn't going to change your management, so getting an MRI at this point because you like to see more structural detail has no added benefit for the patient. Actually it's probably harmful to the patient, since the process of completing an MRI (about an hour, including transport) takes much longer than a non-contrast head CT (minutes). Later when the patient is stable and recovering, the MRI is more useful. Or if the CT suggested an acute infarct, a diffusion-weighted MRI will tell you more information, like UCLA said above. But that would be after you gave the patient tPA (if they met the time window) and you'd need a CT to rule out bleeding beforehand. So in either case, you get a CT first.

CT is the best for brain hemorrhages (never use contrast when looking for a hemorrhage). Sorry I don't have more explanation as to why, I just skimmed this in my notes.

Because fresh blood and contrast both appear bright on CT, so if you give contrast, you can't be sure if the white stuff you're seeing is blood or extravasation of contrast.

🙂