Male or female greater than or equal to 18 years of age.

Body weight less than or equal to 120 kg.

If female, be surgically sterile for at least one year, be post-menopausal for at least one year, or test negative on a pregnancy test by urine or blood within 48 hours prior to MS-325 administration.

Ability to comprehend and a willingness to sign an Informed Consent Form.

Stable medical condition at time of MS-325 administration with no major clinical cardiovascular events within 30 days of MS-325 administration.

Fasted from liquids and solids for two hours prior to MS-325 administration.

Must have a positive diagnostic quality coronary x-ray angiogram which demonstrated coronary artery stenosis(es) of at least 50 percent diameter stenosis in at least one proximal coronary artery vessel between five and 30 days prior to MS-325 administration; angiographic data must be available for loan to an angiographic core lab in order for the patient to be included in the trial.

Normal sinus rhythm.

Willing to abstain from alcohol from 24 hours prior to MS-325 administration through 72-96 hours following MS-325 administration.

No prior coronary bypass graft or coronary stent of the target vessel.

No acute or chronic condition which would limit the patient's ability to complete the study.

No history of claustrophobia.

No receipt of any investigational drug within 30 days prior to

MS-325 administration.

No previous exposure to MS-325; no previous exposure to other contrast agents in other contrast enhanced MR or x-ray studies within five days prior to MS-325 administration.

No major clinical cardiovascular events, coronary angioplasty, or major surgery within 30 days prior to MS-325 administration.

No scheduled x-ray angiography within five days prior to MS-325 administration.

No supine blood pressure less than 100/60 mm HG with pulse rate less than 50 beats per minute (bpm), or supine blood pressure greater than 160/100 m HG with pulse rate greater than 100 bpm, unless deemed not clinically significant by the Principal Investigator.

No history of involuntary motion disorder.

No persons unable to lay on back for 120 minutes.

No persons with known serum creatinine levels greater than 1.5 mg/dL or clinical evidence of severe renal impairment; serum creatinine levels must be determined at least 72 hours post-x-ray angiography but prior to MS-325 administration.

No known SGPT (ALT) and SGOT (AST) levels exceeding three times the upper limit of the study center's normal range; no known serum bilirubin greater than 1.75 mg/dL or clinical evidence of severe hepatic disease.

No specific magnetic resonance (MR) exclusion criteria (i.e., pacemaker, ear implants, internal defibrillator, internal defibrillator, internal infusion pump), as well as institution-specific requirements.

No metal implants or clips in field of view (FOV).

No female who is pregnant or currently lactating.

No recent history of clinically significant anemia (less than or equal to 8.0 g/dL).

No history of sickle cell anemia.

No clinical suspicion of worsening in vascular status of target artery between time of x-ray angiogram and MS-325 administration.

Not received warfarin within seven days prior to MS-325 administration.