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Indications - MRI vs. CT

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Clinical Problem: Brain Preferred Study Contrast Comments
Headache, acute CT No Bone windows replace skull series
Headache, chronic MR Yes  
CVA MR/CT No CT if patient uncooperative
Acute Bleed CT > MR No MR may show source such as AVM or aneurysm
Brain Tumor MR Yes CT better for tumor  calcification
Seizure MR Yes  
CNS infection, abscess, meningitis MR Yes  
Dementia MR > CT No MR superior evaluation of white matter changes
Neurodegenerative disorder MR No Parkinson’s disease, etc.
Subdural hematoma CT No MR detects smaller nonsurgical SDH
MS MR Yes  
Posteria fossa, brainstem lesion MR Yes MR far superior in this region
Acoustic neuroma MR Yes CT not sufficiently accurate
Pituitary tumor MR Yes MR far superior in this region
Aneurysm MR & MRA No  
Sinus venous thrombosis MR & MRV No  
Trauma CT No  


Clinical Problem: Neck, Skull Base, Orbit Preferred Study Contrast Comments
Sinuses CT No  
Neck mass CT >> MR Yes MR only in special situations
Skull base CT No  
Nasopharynx CT Yes  
Optic nerves/orbits MR >> CT Yes CT – for calcification
Cavernous sinus MR Yes  
Cranial nerve dysfunction MR Yes  
Trauma CT No Maxillofacial CT replaces plain films
Brachial Plexus MR Yes  

***above studies read by neuroradiologists

Clinical Problem: Musculoskeletal Preferred Study Contrast Comments
Avascular necrosis MR No Bone scan if MRI contraindicated
Hip pain-negative x-rays MR No Best to look for occult hip fracture if x-rays are negative
Metastasis/Myeloma MR Yes  
Osteomyelitis/Cellulitis MR Yes  
Knee: Meniscal tear/cysts; ligamentous injury; tendon injury; bone contusion; fracture; osteochrondritis dissecans; chrondromalacia MR No  
Shoulder: rotator cuff tear; tendinitis; labral abnormality; bone injury; contusion MR No MR arthrogram if labral tear suspected
Soft tissue mass MR Yes Specific for lipoma-Detects extent/neurovascular involvement of non-lipomatous masses
Bone tumor MR Yes Evaluates extent/neurovascular involvement. CT can be good for evaluating matrix type.
Fracture MR or CT
see comments
No MRI if radiographically occult fracture is suspected. CT if fracture is seen on x-ray and position or alignment is to be addressed. CT for avulsion or small cortical fracture.
Bone bruise MR No  
Loose bodies MR or CT No Patient may need arthrography followed by CT or MRI. MRI can detect loose bodies in the presence of effusion. CT can detect ossified loose bodies. 

***above studies read by musculoskeletal fellowship trained radiologists

Clinical Problem:
Preferred Study Contrast Comments
Herniated disc, cervical or thoracic MR NO Value of contrast not well known
Lumbar herniated disc MR >> CT Yes, if previous surgery Contrast distinguishes between scar and disc after surgery
Stenosis MR >>> CT No  
Discitis MR Yes  
Metastasis, epidural tumor MR Yes MR also superior to myelography
Compression fracture,
possible tumor
MR Yes MR allows evaluation of bone marrow
Cord disease MR Yes Demyelination – syrinx
Cord tumor MR Yes