A port is a device for vascular access typically implanted in the upper chest. It consists of two parts: a subcutaneous reservoir made of plastic, titanium, or stainless steel enclosing a self-sealing silicone bubble for needle insertion; and a catheter connected to the reservoir whose tip is placed fluroscopically into the superior vena cava or other major thoracic vein.
At least a dozen companies produce these devices, the largest being AngioDynamics, Braun Medical, Bard, Cook Medical, MedComp, Navilyst Medical, and Smiths Medical. Common brand names include Port-a-Cath, Clip-a-Port, Infuse-a-Port, Medi-Port, and PowerPort.
To my knowledge, none of these commercially available portal systems is rated "MR Unsafe". Those with metal reservoirs are by definition "MR Conditional" (with relatively minor restrictions for imaging at 3T or less). Patients with metal-containing ports should be warned that they may feel a pulling or tugging sensation when placed in the scanner. However, because these devices are firmly sutured in place between the skin and chest wall there is little chance of dangerous movement or dislodgment.
Nearly all other non-port vascular access catheters and devices do not contain metal and are "MR Safe". These include Peripherally Inserted Central Catheter (PICC) lines, central venous catheters (CVCs), and tunneled catheters (e.g., Hickman, Broviac, Permacath, Leonard, and Groshong).
The single exception is the ARROW® EZ-IO® intraosseous vascular access system declared "MR Unsafe" by its manufacturer (Teleflex). The device is simply a short metal needle whose tip is placed in the marrow cavity of the tibia or other bone for infusion when peripheral vascular sites are unavailable. As their placement can be very tenuous and only slight movement can make them nonfunctional, their use in MRI is contraindicated.
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