A penile implant is a medical device surgically placed to treat erectile dysfunction when other therapies are unsuccessful. For men with these devices, the question of whether they can safely undergo a Magnetic Resonance Imaging (MRI) scan is a common concern. Modern penile implants are overwhelmingly safe for MRI procedures, but safety depends on the device’s specific model and materials. Understanding this compatibility is necessary because MRI is a standard diagnostic tool. The implant’s safety classification—MR Safe or MR Conditional—dictates the necessary precautions and protocols for a scan.
Understanding MRI Safety and Implant Materials
An MRI machine uses a powerful magnetic field and radio waves to create detailed images of organs and tissues within the body. The primary safety concern with any implanted medical device is the potential interaction between the magnetic field and metal components. This interaction can cause three main issues: device movement (deflection), metal heating, or device malfunctioning.
Early medical devices sometimes contained ferromagnetic materials, such as iron or nickel, which are strongly attracted to magnets and were unsafe during an MRI. Modern penile implants are constructed largely from non-ferromagnetic materials that do not react to the magnetic field. The main structural components, including the cylinders and pump, are typically made from biocompatible polymers like silicone and polyurethane.
Most contemporary implants contain small internal components made of non-magnetic metals, despite being primarily plastic-based. These metals, such as certain stainless steels, silver, or specific alloys like MP35N, are used for rear tip extenders, connectors, or springs within the pump mechanism. The inclusion of these minimal metallic parts shifts the device’s safety designation from “MR Safe” (safe under all conditions) to “MR Conditional” (safe only under specific scanning parameters).
Compatibility Status of Different Penile Implant Types
The two main types of penile implants—malleable and inflatable—each have a distinct composition affecting their MRI compatibility. Malleable, or semi-rigid, implants are the simplest, consisting of two flexible rods inserted into the penis. These rods have a silicone exterior surrounding a central core, typically made of silver or stainless steel for shape retention.
Due to this simple design and the non-ferromagnetic core materials, malleable implants are typically classified as MR Conditional. A major exception is a pair of older devices, the Dacomed Omniphase and DuraPhase, which contained significant ferromagnetic metal and are considered MR Unsafe. Although these legacy models are no longer marketed, knowing the exact device history remains important.
Inflatable, or hydraulic, penile implants are more complex, consisting of fluid-filled cylinders, a scrotal pump, and a reservoir hidden in the abdomen. These devices account for the vast majority of implants placed today. Their complexity means they contain a few more small metallic parts, often in the pump’s valve system, which is why they are uniformly classified as MR Conditional.
MR Conditional status means the device is safe for scanning only when the MRI machine operates within specified limits. These limits include the static magnetic field strength (typically up to 3 Tesla) and the maximum whole-body averaged Specific Absorption Rate (SAR), which measures radiofrequency power absorbed by the body. When these protocols are followed, the manufacturer specifies that temperature increases near the implant remain well below a dangerous level, often less than 0.5°C.
Essential Steps Before an MRI Scan
Patients with a penile implant must inform the prescribing physician and the MRI technologist about the device before the scan is scheduled. This proactive disclosure allows the facility to verify the device’s specific MRI compatibility status and ensure safety.
Patients should carry their official implant identification card, provided by the manufacturer after surgery. This card contains the device name, model number, and manufacturer, allowing the technician to consult the specific MR Conditional guidelines. If the card is unavailable, knowing the manufacturer and model is sufficient for the MRI staff to look up the required safety information.
The MRI technologist must follow the specific guidelines listed for that device model to safely perform the scan. These protocols may include limiting the scan to a specific magnetic field strength (such as 1.5T or 3T) or ensuring the scan time and SAR remain within validated limits. Adhering to these protocols is necessary to prevent device heating or movement.