MIBI is the name patients use for Sestamibi SPECT with Gating, a nuclear cardiology study that measures blood flow to the heart muscle while the heart is working under stress and at rest. Your cardiologist orders it when they need information that an electrocardiogram or echocardiogram alone cannot confirm. The study has two phases and can last several hours; planning your entire day before you arrive is part of the preparation.
What does the MIBI evaluate and what information does it give to the cardiologist?
Nuclear cardiology studies obtain physiological information about the heart that conventional studies cannot capture. The Sestamibi SPECT with Gated scan measures blood flow to the heart muscle under two distinct conditions: during exercise and at rest. This comparison allows the cardiologist to identify areas of the heart that receive less blood when working harder.
The Carolina Nuclear & Cardiovascular Institute is conducting this study to evaluate four specific conditions:
| Obstructive coronary artery disease | Myocardial perfusion abnormalities |
| Areas damaged by previous heart attack | Left ventricular ejection fraction |
Why does the cardiologist order it when other tests are not sufficient?
The electrocardiogram records the heart’s electrical activity, and the echocardiogram shows how it moves. The MIBI measures whether the heart muscle receives blood evenly while working under stress, a question the other tests can’t directly answer. That’s why it’s often used as the next step in cardiac evaluation when the doctor needs an answer the other tests didn’t provide.
The MIBI has two phases: exertion and rest
The study requires two sets of images because comparing them allows the cardiologist to detect perfusion abnormalities. If blood flow to a muscle area appears different during exertion than at rest, that difference indicates where the problem might be. With only one image, that information wouldn’t be available.
| Effort Phase | Resting Phase | |
| Aim | Capture muscle perfusion on demand | Capture muscle perfusion at baseline |
| How to induce | Treadmill or vasodilator medication | Waiting period: the tracer is naturally redistributed |
| What records | Areas with reduced flow under effort | Baseline flow + left ventricular ejection fraction |
How to prepare to arrive in the right conditions
The preparation is in place to ensure the radiopharmaceutical is distributed correctly and the images accurately reflect the condition of the heart muscle. Arriving without having followed the instructions may compromise the quality of the study and the information the cardiologist receives. The Carolina Nuclear team will confirm the exact details when scheduling your appointment, but these are the general restrictions:
| ✓ | MIBI Study Preparation |
| ✓ | Fasting is required before the study. Exact times will be confirmed by the team when scheduling. |
| ✓ | Caffeine: Restriction includes coffee, tea, chocolate, and caffeinated soft drinks. |
| ✓ | Heart medications: some may need to be paused. Only under the direction of a cardiologist. |
| ✓ | Pregnancy or breastfeeding: please inform the team when scheduling the appointment. |
What happens from the time he/she arrives until the study ends
Uncertainty about what will happen often generates more stress than the study itself. Knowing the process in advance reduces that burden. The protocol follows these steps:
| # | What happens at each stage |
| 1 | Check-up on arrival: the team confirms correct conditions (fasting, caffeine-free, no restrictions omitted). |
| 2 | Administration of the radiopharmaceutical: injection into a vein in the arm. It does not produce significant sensations. |
| 3 | Exercise phase: treadmill or vasodilator medication. The gamma camera records flow on demand. |
| 4 | Waiting period: the tracer is redistributed in the muscle. The patient remains in the center. |
| 5 | Second administration (if the protocol requires it): some protocols include a second dose. |
| 6 | Resting phase: the camera records the flow at baseline and measures the ejection fraction. |
| 7 | End of study: the result is delivered to the cardiologist who ordered the study. |
The patient remains conscious during the imaging. The Carolina Nuclear team accompanies them in all phases of the process.
What does a positive result in the MIBI mean?
A positive result indicates that an abnormality in heart muscle perfusion was detected: an area receives less blood during exertion than at rest. This finding guides the cardiologist, but it is not a definitive diagnosis. The physician interprets the result within the patient’s overall clinical context and determines the next steps.
A negative result, also called a normal result, indicates that blood flow to the heart muscle is uniform in both phases. The result is given directly to the cardiologist, who explains its clinical significance to the patient.
How to schedule your MIBI study in Nuclear Carolina
The Carolina Nuclear & Cardiovascular Institute was founded by Dr. José Oscar Morales and Dr. Lourdes García in the 1990s to bring nuclear medicine to northern and eastern Puerto Rico. Accredited by the ACR and a pioneer on the island, it serves patients from all 78 municipalities at its center in Carolina, PR. A cardiologist’s order is required for this study. To schedule an appointment, please call 787-757-5985, Monday through Friday, from 7:00 am to 4:00 pm.
Frequently Asked Questions
How long does the complete MIBI study take?
The study includes two phases and a waiting period between them. The exact duration will be confirmed by the team when scheduling your appointment.
Can I take my heart medication on the day of MIBI?
Your cardiologist will tell you which medications to pause and which to continue. Do not stop taking any medication without direct medical advice.
Does MIBI cause discomfort?
The exertion phase may cause a temporary increase in heart rate or warmth. The equipment monitors the patient at all times, and sedation is not required.
What is ejection fraction and what does it say about my heart?
It is the percentage of blood that the left ventricle pumps out with each heartbeat. The MIBI measures it to assess the heart’s pumping strength.
How much does the MIBI study cost in Puerto Rico?
The cost varies depending on your medical plan. The team will provide information on authorizations when scheduling your appointment: 787-757-5985.
MIBI is the name patients use for Sestamibi SPECT with Gating, a nuclear cardiology study that measures blood flow to the heart muscle while the heart is working under stress and at rest. Your cardiologist orders it when they need information that an electrocardiogram or echocardiogram alone cannot confirm. The study has two phases and can last several hours; planning your entire day before you arrive is part of the preparation.
What does the MIBI evaluate and what information does it give to the cardiologist?
Nuclear cardiology studies obtain physiological information about the heart that conventional studies cannot capture. The Sestamibi SPECT with Gated scan measures blood flow to the heart muscle under two distinct conditions: during exercise and at rest. This comparison allows the cardiologist to identify areas of the heart that receive less blood when working harder.
The Carolina Nuclear & Cardiovascular Institute is conducting this study to evaluate four specific conditions:
| Obstructive coronary artery disease | Myocardial perfusion abnormalities |
| Areas damaged by previous heart attack | Left ventricular ejection fraction |
Why does the cardiologist order it when other tests are not sufficient?
The electrocardiogram records the heart’s electrical activity, and the echocardiogram shows how it moves. The MIBI measures whether the heart muscle receives blood evenly while working under stress, a question the other tests can’t directly answer. That’s why it’s often used as the next step in cardiac evaluation when the doctor needs an answer the other tests didn’t provide.
The MIBI has two phases: exertion and rest
The study requires two sets of images because comparing them allows the cardiologist to detect perfusion abnormalities. If blood flow to a muscle area appears different during exertion than at rest, that difference indicates where the problem might be. With only one image, that information wouldn’t be available.
| Effort Phase | Resting Phase | |
| Aim | Capture muscle perfusion on demand | Capture muscle perfusion at baseline |
| How to induce | Treadmill or vasodilator medication | Waiting period: the tracer is naturally redistributed |
| What records | Areas with reduced flow under effort | Baseline flow + left ventricular ejection fraction |
How to prepare to arrive in the right conditions
The preparation is in place to ensure the radiopharmaceutical is distributed correctly and the images accurately reflect the condition of the heart muscle. Arriving without having followed the instructions may compromise the quality of the study and the information the cardiologist receives. The Carolina Nuclear team will confirm the exact details when scheduling your appointment, but these are the general restrictions:
| ✓ | MIBI Study Preparation |
| ✓ | Fasting is required before the study. Exact times will be confirmed by the team when scheduling. |
| ✓ | Caffeine: Restriction includes coffee, tea, chocolate, and caffeinated soft drinks. |
| ✓ | Heart medications: some may need to be paused. Only under the direction of a cardiologist. |
| ✓ | Pregnancy or breastfeeding: please inform the team when scheduling the appointment. |
What happens from the time he/she arrives until the study ends
Uncertainty about what will happen often generates more stress than the study itself. Knowing the process in advance reduces that burden. The protocol follows these steps:
| # | What happens at each stage |
| 1 | Check-up on arrival: the team confirms correct conditions (fasting, caffeine-free, no restrictions omitted). |
| 2 | Administration of the radiopharmaceutical: injection into a vein in the arm. It does not produce significant sensations. |
| 3 | Exercise phase: treadmill or vasodilator medication. The gamma camera records flow on demand. |
| 4 | Waiting period: the tracer is redistributed in the muscle. The patient remains in the center. |
| 5 | Second administration (if the protocol requires it): some protocols include a second dose. |
| 6 | Resting phase: the camera records the flow at baseline and measures the ejection fraction. |
| 7 | End of study: the result is delivered to the cardiologist who ordered the study. |
The patient remains conscious during the imaging. The Carolina Nuclear team accompanies them in all phases of the process.
What does a positive result in the MIBI mean?
A positive result indicates that an abnormality in heart muscle perfusion was detected: an area receives less blood during exertion than at rest. This finding guides the cardiologist, but it is not a definitive diagnosis. The physician interprets the result within the patient’s overall clinical context and determines the next steps.
A negative result, also called a normal result, indicates that blood flow to the heart muscle is uniform in both phases. The result is given directly to the cardiologist, who explains its clinical significance to the patient.
How to schedule your MIBI study in Nuclear Carolina
The Carolina Nuclear & Cardiovascular Institute was founded by Dr. José Oscar Morales and Dr. Lourdes García in the 1990s to bring nuclear medicine to northern and eastern Puerto Rico. Accredited by the ACR and a pioneer on the island, it serves patients from all 78 municipalities at its center in Carolina, PR. A cardiologist’s order is required for this study. To schedule an appointment, please call 787-757-5985, Monday through Friday, from 7:00 am to 4:00 pm.
Frequently Asked Questions
How long does the complete MIBI study take?
The study includes two phases and a waiting period between them. The exact duration will be confirmed by the team when scheduling your appointment.
Can I take my heart medication on the day of MIBI?
Your cardiologist will tell you which medications to pause and which to continue. Do not stop taking any medication without direct medical advice.
Does MIBI cause discomfort?
The exertion phase may cause a temporary increase in heart rate or warmth. The equipment monitors the patient at all times, and sedation is not required.
What is ejection fraction and what does it say about my heart?
It is the percentage of blood that the left ventricle pumps out with each heartbeat. The MIBI measures it to assess the heart’s pumping strength.
How much does the MIBI study cost in Puerto Rico?
The cost varies depending on your medical plan. The team will provide information on authorizations when scheduling your appointment: 787-757-5985.