Fortschritte auf dem Gebiete der Rontgenstrahlen und der Nuklearmedizin. Erganzungsband最新文献

Contrast media have been successfully used as a diagnostic aid in radiology for decades. It has, however, been necessary to accept certain, in some cases unexplained, undesirable side effects because of their physicochemical properties. The conventional preparations available have for more than 40 years been iodinated salts or acids, whose major disadvantage has been high osmolality. For some years now, a new generation of contrast media has been available. These contrast media exhibit a far lower osmolality due to the lack of ionicity. As a result of the volume load of the left ventricle by levocardiography, there is usually an increase of the left ventricular end-diastolic pressure in the pathologic range over 12 mmHg. We were able to prove this in 120 consecutive patients whom we examined. The pressure increase with the use of nonionic contrast media was considerably lower. The differentiated observation of various risk groups showed no signs of valid predictive parameters.

The algesic effects of intravascularly injected solutions of sorbitol and ionic and nonionic contrast media (CM) with high and low osmolality were tested in the perfused isolated rabbit ear connected to the body by the great auricular nerve. The threshold for the pain reflex effect was found to be at an osmolality of between 600 and 700 mosm/kg H2O, that is, at about twice the osmolality of blood. This result is consistent with results obtained to date in investigations in the non-anesthetized rat and in diagnostic examinations with CM in humans. The effects of both sorbitol and the ionic CM at a given osmolality were dose dependent only after low doses and not after a high dose. There were no pain reactions after injection of ionic and nonionic CM with a low osmolality. Release of prostacyclin was observed in preliminary tests after injection of ionic substances with high osmolality, but not after injection of CM with low osmolality.

The neuroradiologic changes after chemonucleolysis were studied in animal experiments conducted to establish whether there is any interaction between chymopapain and the contrast medium iotrolan. Twenty canine disks were examined by diskography with iotrolan 300 mg I/ml before nucleolysis with chymopapain. Twenty disks were subjected only to nucleolysis. For control purposes, another 10 disks were examined by diskography without the administration of chymopapain. The neuroradiologic follow-up study with conventional radiography, computed tomography and magnetic resonance imaging of the lumbar vertebral column revealed typical signs of the effect of chymopapain in all nucleolysed disks, regardless of whether diskography had been performed before chemonucleolysis or not. On the basis of our results, there is no need to fear an interaction between the new dimeric, nonionic contrast medium iotrolan and the substance chymopapain used for chemonucleolysis.

Iosimide is a new synthetic, nonionic, monomeric contrast medium in which a new substance, triiodine-trimesine acid, is used. It has definite advantages compared with the basic substances used in the past, diaminobenzoic acid and monoaminoisophthalic acid. Due to the high stability, the possibility of the formation of toxicologically questionable, free nuclei amino compounds disappears. Only the slightest probability of a cross-reaction with present antibodies exists, because of the low frequency in the environment. On the basis of the hydrophilic structure of the side chains, there is only a slight chemotoxicity. In a controlled, double-blind study on 100 randomized patients iosimide was tested in cerebral angiography against ioxaglate. Ioxaglate is an ionic contrast medium, popular because of its low osmolality. In this study iosimide exhibited no differences in comparison with ioxaglate with respect to the contrast, the neurological status or the liver or renal tolerance. In examining cardiovascular tolerance there is only a slight tendency toward liver changes with iosimide. Examination of the general tolerance, however, shows a statistically significant lower incidence of sensation of heat and pain with iosimide than with ioxaglate.

This study examined the opacification, dose, and tolerance of iotrolan 300 on 231 patients in ascending cervical myelography. The contrast was rated good in 188 (81.4%) of the cases and satisfactory in 40 (17.3%) of the cases. The contrast was poor in only three (1.3%) cases. In 152 patients a dose of 10 ml or less of iotrolan 300 was administered. A good contrast quality was obtained in 84.2% of all examinations. From a total of 231 patients, 146 exhibited no concomitant effects. The intensity of the headache and neck ache was recorded by the patients themselves by means of an analog scale. The frequency and degree of the postmyelographic complaints did not increase with higher doses, i.e., they were not dose dependent. Neurologic irritation, in the form of radicular symptoms, appeared in only 2 of 231 examinations. These data demonstrate that iotrolan 300 is excellent for use in ascending cervical myelography.

The difficulties with comparing data on the risks involved in the use of conventional contrast media and new low-osmolar contrast media are presented. These difficulties are a result of the necessary size of the groups to be compared and the problems of obtaining data. Prospective studies, carried out by a single researcher, probably have the greatest reliability. In multicentered studies with a larger number of participants, a number of factors must be reckoned with. The assessment of the same reaction can vary considerably, depending on the initial illness and interest of the patient or physician. This will, of course, influence the collection of the data. Due to the fact that complications and side effects are more frequent than deaths, the reduction of the first two through the use of new contrast media is statistically easier to ascertain. It can be assumed from the studies performed thus far that the risk of mortality is also reduced. Definite statistical guarantees do not as yet exist, and it is possible that they will never be produced.

Iotrolan, a nonionic, hexaiodinated dimer, is an extremely hydrophilic compound (P = 0.005). Due to its larger Stokes' radius compared with monomeric compounds such as metrizamide, the diffusion time through membranes is extended. Iotrolan deforms erythrocytes only minimally. There is practically no binding to plasma proteins. The new contrast agent has been shown to exert a very limited effect on the complement system (in vitro); it does not inhibit lysozyme (a standard enzyme) in concentrations less than 100 mg I/ml. To inhibit activity of the enzyme collagenase, much higher concentrations of iotrolan than of metrizamide or iopamidol are needed and this could offer an advantage when used for diskography preceding diskolysis with collagenase. After a single intravenous injection in rats, iotrolan has an LD50 of 28.3 g I/kg - the best general tolerance known for water-soluble contrast media thus far. The superior tolerance of iotrolan compared with iohexol and iopamidol (p less than or equal to 0.05) in rats is statistically significant. On the basis of preclinical experience, iotrolan is a very promising contrast medium for intrathecal and intravascular use.

The influence of increasing doses of contrast medium (CM; 0.75, 1.0, 1.5, and 2.0 ml iopromide/kg body weight; 300 mg I/ml) was examined in a randomized, double-blind study. An increase of the dosage resulted in a statistically significant improvement of the quality of the radiographic visualization. This was most pronounced with an increase from 0.75 to 1.0 ml/kg body weight and least pronounced with the increase from 1.5 to 2.0 ml/kg body weight. This improvement was not only visible in the overall quality, but in each part of the urinary tract, the calyces, the pelves, the ureters, and most especially at the parenchyma. Due to economic considerations at the present, a dose of 1.0 ml/kg (300 mg I/ml) is viewed as adequate. Doses below this level should be avoided due to the poorer image quality that results. From a purely medical point of view, the injection of 1.5 ml of nonionic CM/kg body weight is considered optimal.

In a double-blind comparative study between the nonionic, dimeric iotrolan and the nonionic, monomeric iopromide the urographic image quality in the dose 300 mg I/kg body weight is better after iopromide up to 20 minutes after the injection. This result appears to be in contradiction to the results of the animal experimental studies. Possible reasons are discussed.

The urinary excretion of kidney-specific marker proteins before and 120 hours after intravenous injection of either high- or low-osmolar contrast media (CM; diatrizoate, iopamidol 370) was monitored in patients after digital vascular imaging. Inclusion criteria for the randomized clinical study in a total of 40 patients (15 women, 25 men; mean age, 64.5 years) were at least 50 years of age or diabetes mellitus with normal creatinine concentration in serum. Compared with the control period, the elimination of tubular indicator enzymes alanine aminopeptidase, gamma-glutamyltranspeptidase, alkaline phosphatase, as well as of glomerular localized angiotensinase A was significantly higher in all patients after injection of the CM. The most significant differences were observed after 48 hours. In contrast, lysosomal N-acetyl-beta-D-glucosaminidase activity in urine specimens reacted less clearly and appears to be a less sensitive parameter in assessing CM nephrotoxicity. Elimination of brush border as well as of glomerular marker proteins was significantly lower after intravenous injection of low-osmolar CM iopamidol 370 (832 mOsm/kg) than after meglumine diatrizoate 76 (2100 mOsm/kg). In all 40 patients a significant decrease in creatinine clearance was observed; however, patients receiving diatrizoate had a significant decrease in creatinine clearance (period 0 versus 24 to 48 hours after CM), whereas patients after administration of iopamidol had not. No difference was found between creatinine clearance after 48 hours of CM injection within both groups of CM. Due to noninvasive parameters of kidney damage nonionic, low-osmolar CM are less nephrotoxic in potential risk patients, and should be preferred to conventional CM.