Tubes, lines, catheters, and other interesting devices

Abstract

Medical devices (tubes, catheters, lines, prostheses, etc.) are a common finding on radiologic studies. Sometimes they may be misdiagnosed as a pathologic process, or an important observation concerning a medical device may be overlooked because of lack of familiarity with a particular device. This review discusses a variety of tubes, lines, catheters, and other interesting and important medical devices found on everyday radiologic studies. Whenever an unusual radiologic finding is encountered, the first question to be asked is, “Is the finding a film artifact or an artifact of the imaging modality itself (computed radiography, computed tomography [CT], ultrasound, magnetic resonance imaging [MRI], nuclear medicine)? If not, does it represent a medical device or foreign material in or on the patient?” All those who interpret radiologic studies should develop the good habits of obtaining and reviewing the patient's prior studies and should, in addition, read the prior radiology reports. Good reading habits, combined with a knowledge of imaging artifacts, medical devices, foreign bodies, and normal anatomic variants, provide a solid starting point for the interpretation of radiologic studies. One very important factor often not appreciated by radiologists and referring physicians is that, in many instances, the radiologic visibility of a medical device has been given no thought, and the device has been designed with no input from the radiologic community. To compound this problem further, devices are often purchased by a hospital or medical center for the lowest price. Those purchasing devices frequently fail to seek advice from radiologists and other physicians concerning the radiologic detectability of the devices they purchase. Medical devices are manufactured from a variety of substances known as biomaterials. These include various types of metals, polymers, rubbers, ceramics, and composites. Biomaterials are substances brought into contact with living tissue for the purpose of treating a medical or dental problem. They must be compatible with human tissues chemically, mechanically, and pharmacologically. There are many ways to classify biomaterials, such as synthetic versus “natural”, permanent versus transient, liquid versus solid, hard versus soft, and so forth. Although most life-support devices are within the patient's heart, blood vessels, lungs, or pleura, miscellaneous tubing, clamps, syringes, electrocardiograph (ECG) leads, and other apparatus often lie on or under the patient and appear on radiographs, especially chest studies. Patients may also lie on trauma boards, foam mattresses, or other similar supports. Important abdominal devices include gastrointestinal apparatus and genitourinary devices. Long intestinal tubes, feeding tubes, gastrostomy tubes, Foley catheters, suprapubic catheters, and urinary stents are frequently present in ill patients. Intrauterine contraceptive devices (IUDs) are still an important form of contraception, and dialysis catheters and ventriculoperitoneal shunts may be seen in patients of all ages. Umbilical venous and arterial catheters are frequently used in ill neonates. A variety of other interesting devices or substances are still occasionally found in patients on abdominal or pelvic imaging studies, such as tantalum mesh, pessaries, Thorotrast, and Pantopaque.