Triple contrast technique for black blood imaging with double inversion preparation.

This work reports on the development of a pulse sequence to simultaneously acquire proton density, T(1), and T(2) weighted images in a single magnetization prepared fast spin echo acquisition. The technique is based upon the application of a magnetization preparation consisting of a global inversion followed by slice-selective 180 degrees and 90 degrees pulses to prepare the signal of specific slices. Slices are acquired in an interleaved manner with time delays appropriate for the desired image contrasts. Data acquisition is repeated for all combinations of slice interleaving covering the region of interest until images from all slice locations have been acquired with all desired image contrasts. The multiple image contrasts obtained with this technique should be useful in applications where discrimination between different types of tissue components is desired, such as in the analysis of plaque in cervical carotid artery disease.     

Acute pulmonary edema after the intravenous administration of contrast media.

Acute pulmonary edema developed in two young, previously healthy women immediately after the intravenous administration of contrast media. The pulmonary edema, rare in young persons, could not be explained by classical anaphylaxis, contrast media overdose, sodium and fluid overload, or acute myocardial infarction. A nonimmunologic osmotic mechanism causing reversible pulmonary capillary leak might explain the clinical events observed in both patients. Both responded to continuous positive airway pressure (CPAP), indicating the possible utility of CPAP in treating pulmonary capillary-leak contrast reactions.     

Extracellular gadolinium-based contrast media: an overview

Increasing use is made of extracellular MRI contrast agents that alter the image contrast following intravenous administration; they predominantly shorten the T1 relaxation time of tissues. The degree and location of these changes provide substantial diagnostic information. However gadolinium-based contrast agents (Gd-CA) are not inert drugs. They may cause acute non-renal adverse reactions (e.g. anaphylactoid reactions), acute renal adverse reactions (e.g. contrast induced nephropathy), delayed adverse reactions (nephrogenic systemic fibrosis) and problems at the site of injection (e.g. local necrosis). This review describes the current status of Gd-CA, their mechanism of action, chemical structure, pharmacokinetics, dosage, elimination, nephrotoxicity and adverse events.     

Results of a double blind study of three contrast media and technic for lumbosacral radiculography

Summary The rate of side effects, the results of EMG, EEG and CSF changes after radiculography, the rates of late leptomeningeal changes and the details of the hyperosmolality following the ionic contrast media are recorded and discussed. In conclusion rules are presented for the choice of contrast medium and the examination technic for radiculography.     

MR-cholangiography with a double contrast technique

The combination of superparamagnetic particles (SPP) as a 'negative' contrast agent for the liver parenchyma and Cr-HIDA as a 'positive' one for the bile ducts was tested in dogs. The maximum effect of SPP was present about 30 minutes after injection with a reduction of the image intensity of the liver close to the background noise level at the highest dosages. This effect lasted for about 4 to 5 hours and it had disappeared after 24 hours. Before any contrast administration or after Cr-HIDA the bile ducts were not discernible, but a high signal in the gallbladder was present 15 to 30 minutes after injection of Cr-HIDA. After SPP the wider bile ducts were discernible because of the lowering of the signal intensity in the liver. When SPP were followed by Cr-HIDA, the bile had a higher signal intensity, and even tiny bile ducts were visible. After cholecystokinin visualization of the choledochus duct was achieved as well as contrast filling of the duodenum. The blood, urine, and liver function tests were found normal during the experiments. The combination of superparamagnetic particles and Cr-HIDA seems to be a promising method for MR-cholangiography. An evaluation of the anatomic structures of the liver should be possible with this method in different pathologies.     

Regulatory compliance associated with contrast media

A basic understanding of the role of regulatory agencies in governing the healthcare environment and their influence over contrast media use is required of radiographers and imaging administrators to meet the many standards of compliance. In addition, radiology management teams must consider cost effectiveness, departmental efficiency, workplace safety, and compliance in choosing to implement new products. Regulatory agencies may be classified into 2 groups, voluntary and involuntary. Involuntary agencies are governmental agencies mandating regulatory compliance by local, state, or federal laws. Voluntary agencies are precisely that, those agencies an institution voluntarily chooses to participate with, to demonstrate the quality of care they provide. Failure to follow involuntary regulatory guidelines or to participate in voluntary best practice standards jeopardizes patient safety and the quality of care provided, and exposes the institution and the individual to liability risks. Severe penalties may result from a failure to maintain regulatory compliance, including the possibility of large fines, criminal indictments, and loss of third-party reimbursement. Achieving regulatory compliance is never an easy venture with the number of regulatory agencies and standards needing to be addressed. Combining regulatory compliance with the effects of doing business provides quite a challenge for today's imaging departments. A solid knowledge base in regulatory standards along with continuous investigation of new standards will allow departments to evaluate their own processes involved in providing patient care. Recognition of areas of high risk/high volume, including contrast media use, will assist in directing the departments' focus appropriately. A thorough evaluation of the products used and their respective handing and administration, in regard to patient and workplace safety, and appropriate documentation of workplace injuries due to contrast media packaging, will assist in maintaining a high level of compliance.     

CT angiography with gadolinium-based contrast media

RATIONALE AND OBJECTIVES: To evaluate the potential use of gadolinium (Gd)-based contrast media, especially that of Gadovist, a 1-molar Gd medium, in computed tomography (CT) and compare our findings with standard iodinated contrast media. MATERIAL AND METHODS: Using a live rabbit and an acrylic CT body phantom for comparative CT imaging of Gd- and I-based media. The images were acquired at 80, 100, and 120 kVp, using fixed standard beam filtration. The phantom study used serial dilutions of the Magnevist and Ultravist 300 (2.4-molar I), whereas the animal study used different volumes of Gadovist, Magnevist (0.5 molar Gd), and Ultravist administered intravenously. RESULTS: At 80 kVp for the same injection volumes of Gadovist and Ultravist, the image contrast enhancement of the aorta with Gadovist was 40% lower than that of Ultravist. In the phantom studies, however, for the same kVp settings the CT image contrast was up to fourfold higher for Gd compared with iodine when comparing the same molar concentrations of the two elements in the solutions. CONCLUSION: These results indicate a potential of Gd-based media for clinical CT angiography and provide incentive for further investigation of this subject.     

Computed tomography with iodine-free contrast media

The purpose of this work was to evaluate the enhancement of different concentrations of gadolinium (Gd), ytterbium (Yb) and iodine in vitro and in vivo. Comparisons were made of the enhancement (HU) of Gd, Yb and iodine in concentrations ranging from 0.1 to 30 mg/ml. In vivo dynamic CT studies were performed in ten dogs with 0.5 M Gd, Yb and iodine. Time-density curves were achieved in aorta and liver. The in vitro studies confirmed a decrease in the enhancement in this order: Gd (120 kV) > Gd (137 kV) > Yb (120 kV) > Yb (137 kV) > iodine (120 kV) > iodine (137 kV). The specific enhancement of Gd was 40.8 (120 kV), of Yb 34.2 and of iodine 29.6 HU. The enhancement of the liver decreases from 21 HU (Gd) to 19 HU (Yb) and 12 HU (iodine). Gd and Yb achieved a higher aortal enhancement than iodine (190 vs 157 HU) All contrast media were well tolerated. Equimolar concentrations of Gd and Yb show a higher in vitro contrast and enhancement than iodine. Received: 17 May 1996; Revision received: 12 September 1996; Accepted: 18 October 1996