any one knw an answer?

[hanan]

Hi

 

i have afew Q and i relly need help with them

 

1) compare and evaluate the appearance of bone and soft tissue in an MRI scan compared with a conventional X-ray.

 

2) Explainthe factors influencing the signal intensity in MRI.

[TonyMcC]

http://www.netdoctor.co.uk/health_advice/examinations/mriscan.htm

I think this link will give you some info for Q1

http://www.mr-tip.com/serv1.php?type=db1&dbs=Signal%20Intensity

I think this will give you some info for Q2

[UniScience.Info]

Signal in MR images is high or low (bright or dark), depending on the pulse sequence used, and the type of tissue in the image region of interest. The following is a general guide to how tissue appears on T1- or T2- weighted images.

 

• Dark on T1-weighted image:
• increased water, as in edema, tumor, infarction, inflammation, infection, hemorrhage (hyperacute or chronic)
• low proton density, calcification
• flow void

• Bright on T1-weighted image:
• fat
• subacute hemorrhage
• melanin
• protein-rich fluid
• slowly flowing blood
• paramagnetic substances: gadolinium, manganese, copper
• calcification (rarely)
• laminar necrosis of cerebral infarction

• Bright on T2-weighted image:
• increased water, as in edema, tumor, infarction, inflammation, infection, subdural collection
• methemoglobin (extracellular) in subacute hemorrhage

• Dark on T2-weighted image:
• low proton density, calcification, fibrous tissue
• paramagnetic substances: deoxyhemoglobin, methemoglobin (intracellular), iron, ferritin, hemosiderin, melanin
• protein-rich fluid
• flow void

source : http://www.med.harvard.edu/AANLIB/basicsMR.html

[small bang]

Disletic much.