INCLUSION CRITERIA:
Any normal volunteer above the age of 18 who is capable of giving informed consent.
EXCLUSION CRITERIA:
A subject will be excluded if he/she has a contraindication to MR scanning such as:
1. Brain aneurysm clip
2. Implanted neural stimulator
3. Implanted cardiac pacemaker or defibrillator
4. Cochlear implant
5. Ocular foreign body (e.g. metal shavings)
6. Insulin pump
7. Pregnant women (when uncertain, subject will undergo urine or blood testing).
8. Kidney disease
9. paralyzed hemidiaphragm
10. Morbid obesity
11. Claustrophobia
12. Any condition in the Principal Investigator's judgement which present unnecessary risk
EXCLUSION CRITERIA FOR GADOLINIUM ENHANCED STUDIES:
1. Lactating Women
2. Subjects with hemoglobinopathies
3. Asthma
4. Renal or hepatic disease.