As use of multislice computed tomography (CT) scanners becomes more common, contrast protocols are being re-evaluated. Some procedures, such as CT angiography, require faster injection rates than had been used previously. This, in turn, has led to increased concern regarding extravasation of contrast material. To address these changing needs, imaging personnel are turning to increasingly sophisticated power injectors.

Digital injector offers extravasation detection feature

E-Z-EM (Westbury, NY) recently introduced the EmpowerCT injector, with their proprietary Extrasvasation Detection Accessory (EDA) technology (Figure 1).

The all-digital system allows flow rate adjustment at any time during the procedure from 0.1 to 10 mL/sec, in 0.1-mL increments, either remotely or at the injector head. The pressure can be set from 20 to 300 pounds per square inch (psi) in increments of 1 psi. The system can also be set for a specific pressure that it should not exceed; the flow rate will be reduced or paused automatically if that pressure is reached. A high-contrast EL display at the injector head offers a real-time display of system parameters, pressure, syringe volume, orientation, and EDA system status. The injector head and controller display swivel independently, so the system can be positioned on either side of the gantry.

Syringes can be filled manually or automatically, or prefilled syringes may be used. Contrast may be placed in an automatic warmer.

All functions can be controlled at the workstation via a touch-screen display. Up to 50 anatomically referenced preprogrammed procedures can be stored in the system.

The company's EDA technology monitors for changes in skin impedance indicative of a clinically significant extravasation. If such changes are noted, the system automatically alerts the operator and pauses the procedure. Although the injector head can be rotated 270š, the system will not operate unless the injector head is positioned properly to avoid the risk of air embolism. If a problem arises during the procedure, spoken cues alert the operator and the injection may be paused at either the injector head or at the remote touch screen.

New syringe loader and MR infusion system from Medrad

Medrad, Inc. (Indianola, PA) recently unveiled a new CT Syringe Loader that allows contrast syringes to be filled outside the scan room.

The manufacturer reports that moving the filling process out of the scanning area may reduce room preparation time and increase throughput. In addition, with the continuous volume range of up to 200 mL, radiology personnel can control the amount of contrast administered using weight-based dosing protocols.

The CT Syringe Loader can be mounted on a wall and is compatible with the vendor's EnVision, Vistron, and MCT Plus vascular injectors and syringes, as well as QFT, Spike, and bulk contrast containers.

Medrad also recently announced that they have received 510(k) clearance from the U.S. Food and Drug Administration (FDA) to begin marketing their new Continuum MR Compatible Infusion System (Figure 2). With this system, patients can continue to receive intravenous medications throughout the course of a magnetic resonance (MR) imaging procedure.

The system can deliver up to three fluids via a single line and incorporates an automatic free-flow protection feature. The device is designed to be positioned close to the patient and uses minimal priming volumes to reduce waste of medications.

The company, which debuted Continuum at the Radiological Society of North America (RSNA) annual meeting in Chicago earlier this month, expects the system to be available worldwide by early 2003.

New MR contrast agent detects malignancy in lymph nodes

In other contrast imaging news, a recent study found that a new MR contrast agent was able to distinguish malignant from normal axillary lymph nodes accurately, one of the most important prognostic factors, in breast cancer patients. ¹

The ultrasmall superparamagnetic iron oxide contrast agent (Combidex) from Advanced Magnetics, Inc. (Cambridge, MA) and Cytogen Corp. (Princeton, NJ) was tested in 18 patients with breast cancer who were scheduled for surgery. MR imaging of the breast and axillary lymph nodes was performed within 24 to 36 hours of the administration of Combidex. The study results were then compared with the histopathologic analysis. Use of the new agent resulted in a sensitivity of 82%, a specificity of 100%, and a positive predictive value of 100%.

"Treatment strategy in patients with breast cancer is dependent not only on the extent of the primary tumor but also on axillary lymph node staging," said H. Joseph Reiser, PhD, president and chief executive officer of Cytogen Corp. "We believe that Combidex can play an important role in the staging of metastatic disease in a variety of cancers, especially through providing additional information in the determination of lymph node status. This information is key to allowing cancer patients and their physicians to make more appropriate treatment decisions."

Combidex received an approvable letter for use in the diagnosis of lymph node disease, subject to certain conditions, from the FDA in June 2000.

"We are very encouraged by the results of this new study," said Jerome Goldstein, chairman and chief executive officer of Advanced Magnetics. "We continue to work with the FDA to resolve the outstanding issues and remain hopeful that we will be successful in this effort."

AIUM issues statement warning against entertainment use of US

The American Institute of Ultrasound in Medicine (AIUM) recently issued a statement reiterating its opposition to the use of ultrasound for entertainment purposes. The statement was prompted by the emergence of companies providing keepsake fetal ultrasound videos to expectant mothers and their families.

The AIUM notes that "although there are no confirmed biological effects from ultrasound at the present time, the possibility exists that such biological effects may be identified in the future." Therefore, they recommend that ultrasound only be used to provide medical benefit to the patients.

A second concern raised by the society is that patients may misinterpret the session as a medical examination. "Many pregnant women expect that their ultrasound examination will identify problems. This is not the case with entertainment sonograms," said Alfred B. Kurtz, MD, AIUM president. "Entertainment sonograms do not assess fetal well being. The personnel performing these studies are often unskilled, while most 3D and 4D studies require considerable expertise. Therefore, at times, the images created can be disappointing or give a misleading appearance to the fetus. An entertainment sonogram is a misuse of ultrasound technology and should not be offered," he continued. "In addition, it should not replace a medically indicated ultrasound examination."

The FDA concurs with the AIUM position, stating that "persons who promote, sell, or lease ultrasound equipment for making keepsake fetal videos should know that the FDA views this as an unapproved use of a medical device. Those who subject individuals to ultrasound exposure using a diagnostic ultrasound device (a prescriptive device) without a physician's order may be in violation of state or local laws or regulations regarding the use of a prescriptive device." The entire FDA statement can be viewed at http://www.fda.gov/cdrh/consumer/fetalvideos.html.