For a cardiac MRI, your entire body does slide into the scanner tunnel, but your head typically ends up near the very edge of the opening or just barely inside it. The scanner needs to position your chest at the center of the magnetic field, which means your legs and feet may partially extend out the other end depending on your height. Most people find a heart MRI less confining than a brain MRI, where the head sits deep inside the bore.
How You’re Positioned in the Scanner
You lie on your back on a narrow, padded table that slides into a cylindrical tube. The tube, called the bore, is typically 60 to 70 cm (about 24 to 28 inches) in diameter. Newer machines tend to use the wider 70 cm bore, and patients consistently report less anxiety in these compared to older 60 cm models.
Because the target is your heart, the technologist positions you so your chest sits at the center of the magnet. For most adults, this places your head right at the opening of the tunnel or just a few inches inside. Taller people sometimes have their knees and lower legs extending out the far end. You won’t be sealed inside a capsule. Both ends of the tube are open, and air flows through continuously.
What Gets Placed on Your Body
Before you slide in, the team attaches a few things. Small electrode pads go on your chest so the scanner can track your heartbeat in real time. This signal synchronizes each image capture to a precise moment in your cardiac cycle, which is essential for getting sharp pictures of a moving organ. Most centers now use wireless or fiber-optic electrode systems that reduce interference from the magnetic field.
A receiver coil, sometimes described as a lightweight plastic frame or padded panel, is placed over your chest. A second flat coil panel sits underneath your back at heart level. Together, these coils act like antennas that pick up the signals your body sends back during the scan. They conform to the shape of your torso and don’t squeeze or compress you. You’ll also get earplugs or headphones, because the machine produces loud knocking and buzzing sounds throughout the exam.
What the Exam Feels Like
The scan itself typically lasts 30 to 60 minutes, though some complex studies run longer. You won’t feel any pain or sensation from the magnetic field. The main challenge is staying still and following breathing instructions. The technologist speaks to you through an intercom and periodically asks you to hold your breath for about 15 to 20 seconds at a time. These brief holds prevent chest movement from blurring the images. Between breath holds, you breathe normally and rest. The requests come in cycles throughout the exam, so you get breaks.
If contrast dye is needed, a small IV line is placed in your arm before or during the scan. The injection itself feels like a cool flush through your vein and takes only a few seconds. The dye highlights blood flow patterns and can reveal scarring or inflammation in the heart muscle.
Managing Claustrophobia
Anxiety about the enclosed space is one of the most common concerns, and it’s worth knowing your options. The 70 cm wide-bore machines that are now standard at many imaging centers feel noticeably more spacious than older models. Some facilities also offer prism mirrors or angled glasses that let you see out toward your feet and beyond the end of the tunnel, which can reduce the feeling of being closed in.
Open MRI machines do exist and have been used for cardiac imaging. These systems have wider gaps or no full tunnel at all, which helps significantly with claustrophobia. A comparative study found that image quality from open 1.0T scanners was statistically comparable to standard 1.5T tunnel systems for routine cardiac sequences, though the signal strength was lower. Not every facility has an open scanner equipped for cardiac work, so this is worth asking about when you schedule the exam.
If you know you’re prone to claustrophobia, mention it when booking. Many centers can prescribe a mild sedative you take before arriving. Keeping your eyes closed, using the headphones to listen to music, and focusing on the breathing instructions are simple strategies that help many patients get through comfortably.
How It Compares to Other MRIs
A cardiac MRI feels different from a brain or spine MRI in a few ways. Your head stays near the opening rather than deep inside the bore, which makes the experience less enclosed for most people. However, the exam tends to be longer than a standard MRI of, say, a knee or shoulder, because the heart is a moving target and the scanner needs multiple image sets timed to your heartbeat. The breath-hold requests are also unique to cardiac and abdominal scans.
You can expect to be on the table for roughly 45 minutes on average, though preparation and positioning add time on either side. Wearing loose, comfortable clothing without metal (zippers, underwire bras, belt buckles) speeds up the check-in process. You’ll change into a hospital gown if your clothes have any metal components.