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Results of the use of a new water-soluble contrast medium (metrizamide) in the posterior fossa of the baboon.

An investigation was made of the use of a new water-soluble contrast material (metrizamide) for posterior-fossa radiography in the baboon. The experiments showed that the concentration of metrizamide needed to produce adequate radiographs from sub-occipital injections into the posterior fossa always produced generalized seizures. Intraventricular injection produced excellent radiographs from metrizamide concentrations, which did not result in either clinical or EEG seizure activity. Seizures, when they occurred, were easily controlled with pentobarbitone and phenytoin. In all the experiments, ECG changes were found, which disappeared after some hours.

Animals↗

Quality of urograms in infants: a comparison of sodium diatrizoate, metrizamide and iohexol.

A consecutive series of 314 intravenous urograms performed in infants were reviewed and assessed for quality. The first 106 examinations were performed using sodium diatrizoate (Hypaque 270) as the contrast medium, the next 98 patients received metrizamide (Amipaque 280) and the final 110 received iohexol (Omnipaque 300). Thirty-five patients had to be excluded from the study for a variety of reasons, after which there were totals of 98 in the diatrizoate, 90 in the metrizamide and 91 in the iohexol groups. Assessing quality in terms of nephrographic and pyelographic density, sodium diatrizoate was found to be better than the non-ionic agents. Although the differences reached statistical significance they are small and unlikely to affect the information obtained in clinical practice. There was no difference in overall quality between metrizamide and iohexol. Comparing the degree of pyelographic distension and ureteric visualization using the three agents, no difference was found between the groups.

Diatrizoate↗

Metrizamide in neonatal and childhood small bowel obstruction.

Metrizamide (Amipaque) has been used to image the bowel of four neonates and one older child with possible bowel obstruction. In each case, barium and hypertonic water-soluble agents, such as Gastrografin and Hypaque, were contraindicated. In each case, the metrizamide study provided unique formation altering the management of the patient. Metrizamide provides a new method of evaluating selected difficult cases of suspected bowel obstruction in the newborn, and in older children it may help to distinguish between postoperative ileus and mechanical obstruction.

Child↗

Computed tomography of the brain stem with intrathecal metrizamide. Part I: the normal brain stem.

In summary, the anatomic details of the brain stem are exquisitely demonstrated with metrizamide CT. The obex is the zone of transition from the closed medulla, which has a conical pear-shaped appearance to the quadriconcave open medulla. The pyramids and inferior olivary nuclei characterize the anterior surface of the open medulla, whereas the median sulcus and the cranial nerve nuclei constitute the floor of the fourth ventricle at the same level. The mushroomlike appearance of the pontomedullary junction is easily reproducible with the restiform bodies forming the posteriorly diverging biped. The seventh and eighth nerves are usually seen at this level or on the adjacent higher section of the low pons. The brachia pontis are well delineated in almost their entire length at the level of the low pons as they bound the fourth ventricle laterally. The trigeminal nerves are seen at the level of the midpons, which is a few millimeters lower than the isthmus. The latter constitutes the junction of the pons with the mesencephalon. The colliculi divide the midbrain into two levels of axial cross section: the inferior collicular level, which may or may not show the trochlear nerve, and the superior collicular level, which features anteriorly the suprasellar cistern and its contents. Air is an inadequate contrast agent for CT for the demonstration of the surface features of the brain stem because of partial filling of the cisterns and meniscus formation that precludes a detailed outline. Metrizamide, however, with careful technique, fills the fourth ventricle and subarachnoid space both infra- and supratentorially. High-resolution scanning using primary reconstruction, and thin tomographic sections of no more than 5 mm are a necessity for metrizamide CT. Consecutive scans should not be spaced more than 5 mm apart if all the features of the brain stem are to be evaluated. The demonstration of the various grooves and protuberances on the surface of the brain stem provides a unique opportunity for evaluating focal atrophy and focal swelling henceforth impossible to visualize consistently.

Brain Stem↗

Iohexol versus metrizamide for lumbar myelography: double-blind trial.

Lumbar myelography was performed in 50 patients; 25 received iohexol (an investigational aqueous contrast agent) and 25 received metrizamide. The two media produced radiographs of equal quality. However, iohexol is stable in solution, while metrizamide is not. Further, markedly less morbidity resulted from iohexol. These features indicate that iohexol may be superior to metrizamide as a contrast agent for lumbar myelography.

Adult↗

Metrizamide CT myelography in cervical myelopathy and radiculopathy: correlation with conventional myelography and surgical findings.

Conventional myelography, metrizamide computed tomographic (CT) myelography, and surgical findings were correlated in 30 patients with cervical radiculopathy and/or myelopathy. In 60% of patients, metrizamide CT myelography provided significant additional information including better characterization of the abnormality, lateralization if the conventional myelogram was indeterminate, more definitive demonstration of cord atrophy, foraminal narrowing not appreciated on myelography, and demonstration of abnormalities distal to a myelographic block. In no case was a myelographic abnormality not detected on metrizamide CT myelography. In patients with cervical myelopathy, a cross-sectional diameter of the cord equaling less than 50% of the subarachnoid space is predictive of poor patient response to surgical intervention.

Adult↗

Evaluation of periventricular hypodensity in experimental hydrocephalus by metrizamide CT ventriculography.

Hydrocephalus was induced in 13 dogs by injecting kaolin into the cisterna magna and was evaluated by computerized tomography (CT) scans. Modification of periventricular hypodensity was observed by metrizamide-enhanced CT ventriculography. Periventricular hypodensity was seen as early as 12 hours after kaolin injection. On CT ventriculography, metrizamide stayed longer in the ventricles of hydrocephalic dogs than in those of normal dogs, and migrated into the areas of periventricular hypodensity; the changes became significant within 12 to 24 hours. Four of the dogs were killed immediately after CT ventriculography, and the iodine concentration was measured. Iodine concentration was highest in the periventricular white matter, followed by the basal ganglia, and it was low in the cerebral and cerebellar cortex. When the change in Hounsfield units found by CT ventriculography at the regions of interest was compared to the actual iodine concentrations, the figures were quite compatible. Similarly, the specific gravity was measured in tissue from various parts of the brain of two hydrocephalic dogs, and compared against the value of that from five normal dogs. The specific gravity values were particularly low in the periventricular white matter of the hydrocephalic brains, suggesting a higher water content in that region. Since the increased migration of metrizamide occurred at the same region, it is suggested that development of periventricular hypodensity is due to increased transit of cerebrospinal fluid from the ventricles to the white matter.

Animals↗

A double-blind clinical trial of iopamidol versus metrizamide for lumbosacral myelography.

A double-blind study was performed to compare metrizamide with the new iodinated water-soluble nonionic contrast medium, iopamidol, for conventional and computerized tomography lumbosacral myelography. Both contrast agents were used in 30 patients, and were equivalent in terms of image quality and clinical accuracy. Headaches and nausea were less severe using iopamidol. The most striking difference was found in adverse neurobehavioral reactions and associated electroencephalographic abnormalities, which were noted in 17% of the metrizamide group but were not seen with the use of iopamidol. Iopamidol appears to be superior to metrizamide for intrathecal applications. An explanation of the differential neurotoxicity is provided.

Clinical Trials as Topic↗

Localization of dural fistulas using metrizamide digital subtraction fluoroscopic cisternography.

Demonstration of the exact site of dural fistulas in cases of cerebrospinal fluid rhinorrhea is difficult. Previous reports have described the use of metrizamide cisternography combined with either hypocycloidal tomography or computerized tomography; however, direct, dynamic, real-time visualization of the fistula is difficult with instillation of a minimal dose of metrizamide using those methods. A digital video subtraction fluoroscopy system can visualize the actual site of the fistula directly and dynamically using only a small amount of metrizamide.

Adult↗

Advantages of ambulatory metrizamide myelography with contrast CT tomography.

Outpatient metrizamide cervical and lumbar myelography complimented by CT scanning is a safe and effective method of assessing the contents of the neural canal. By minimizing the dose of metrizamide and using a small needle, the incidence of side effects is reduced. The techniques of needle insertion metrizamide injection and radiography as well as pre- and post procedure care are described in detail.

Adult↗

The use of metrizamide for isopyknic separation and enrichment of Plasmodium falciparum schizonts from continuous culture.

Plasmodium falciparum-parasitized erythrocytes obtained from continuous in vitro cultures were fractionated over metrizamide density gradients. Late developmental stage schizonts were isolated from uninfected erythrocytes and other intracellular blood stage forms (rings and trophozoites) by centrifugation through 15% metrizamide. Schizonts comprised, on the average, 85% of the total number of cells recovered from the top fraction of the gradient with the remaining cells being predominantly uninfected erythrocytes. The mean percentage of schizonts recovered was 27% relative to the estimated number of mature forms present before fractionation. The concentrated schizonts were viable based upon their ability to complete schizogony and undergo a new cycle of reinvasion and schizogony in vitro. In addition, in these short term synchronous cultures the newly infected cells were able to incorporate radiolabeled hypoxanthine. This function was inhibited by the addition of chloroquine to these 45- to 46-hour cultures. Metrizamide-purified schizonts should be useful for further study and characterization of the unique metabolic, biochemical, and immunological properties of the malaria parasite.

Centrifugation, Density Gradient↗

Reduction of the gastrointestinal side effects of metrizamide myelography with oral dexamethasone.

A prospective, double-blind study was undertaken to assess the effectiveness of oral dexamethasone premedication in reducing a variety of side effects associated with metrizamide myelography. We also examined the relationship between side effects and needle size, total metrizamide dose, radiographic findings, and personality. Patients were randomly assigned to either a placebo group (44 patients) or a dexamethasone group (38 patients). All patients completed a 24-item symptom checklist before and 24 hr after lumbar myelography. In addition, all patients completed the Minnesota Multiphasic Personality Inventory prior to myelography. Analysis of variance demonstrated a statistically significant decrease in the frequency of gastrointestinal side effects (loss of appetite, nausea, vomiting) in the dexamethasone group. There were no significant differences between the two groups for the other 21 symptoms examined. We concluded that premedication with oral dexamethasone significantly reduces the gastrointestinal side effects associated with metrizamide myelography. This reduction was especially important in older patients.

Administration, Oral↗

Pediatric myelography with metrizamide.

Ninety-four children were examined with metrizamide (Amipaque). Overall, the quality of the examinations in the lumbar-low thoracic region was generally equivalent to that obtained with iophendylate. Supine myelography is unfortunately still a necessity in a large number of cases. The side effects, especially nausea and vomiting, slight temperature elevation and fever, are considerably higher with metrizamide and also higher than previously reported in adults. Advantages of metrizamide over oily media are the absorption of the medium which eliminates the need for post-procedure removal and the higher rate of conus demonstration in the prone position; both facilitate the examination. The ability to follow myelography with computer scanning is also beneficial.

Adolescent↗

Computer tomography of the spinal canal using metrizamide.

Eleven patients have been examined by whole body CT employing the EMI CT 5000 following lumbar injection of 10 ml of metrizamide (Amipaque) 170 mg I/ml. The distribution, flow and dilution of the contrast medium have been investigated. The results suggest that whilst metrizamide is necessary in the spinal canal to demonstrate the neural axis and pathologic processes affecting it, it appears to enter the extracellular space of the spinal cord during the first hour and achieves an equilibrium in the subarachnoid space and spinal cord from 3 to 6 hours. The medium may concentrate in a second compartment, possibly intracellular, from 3 to 6 hours. The effect of spectral filtering by metrizamide on the attenuation values of the spinal cord has been modelled and shown not to be significant at the anticipated dilution of the medium in the cerebrospinal fluid space and the spinal canal.

Humans↗

Iohexol 240 mgr I/ml and metrizamide 240 mgr I/ml in lumbar myelography. Report from a randomized double blind study.

A parallel, double blind, randomized study, comparing iohexol 240 mg I/ml and metrizamide 240 mg I/ml in lumbar myelography was carried out. Fifty patients were admitted to the study, and 1 patient was excluded after entry. Of the 49 patients included, 28 were males and 21 females, aged between 18 and 72 years. A dose of 10.5 ml of contrast medium was administered. A detailed neurological examination, and measurement of blood pressure and heart rate were performed before and 24 h after myelography. EEG was recorded in 37 patients. All patients were observed for adverse reactions for 48 h. Adverse reactions were reported in 14 of 26 patients examined with iohexol, and in 13 of 23 patients examined with metrizamide. EEG changes were observed in 7 patients examined with metrizamide, no changes were observed in patients examined with iohexol. The image quality was judged good or excellent in all cases, with the upper level of contrast medium brought to the level of L1 in the majority of cases.

Adolescent↗

Use of pentobarbital sodium to reduce seizures in dogs after cervical myelography with metrizamide.

We conducted a prospective study to examine the effect of pentobarbital administration on the development of seizures in dogs that had undergone cervical myelography with metrizamide while anesthetized with halothane. Thirty dogs scheduled for cervical myelography were assigned to 3 groups. Dogs in group 1 received no pentobarbital. Those in group 2 were administered pentobarbital (5 mg/kg, IM) before induction of anesthesia, and those in group 3 received pentobarbital at the end of the procedure when the anesthetic vaporizer was turned off. Anesthesia was induced with thiamylal sodium in all dogs and was maintained with halothane. Dogs that underwent surgery immediately after the myelography were not included in the study. A significant difference was not found among the 3 groups in terms of number of dogs that had seizures, mean body weight of the dogs, duration of anesthesia after injection of metrizamide, time from extubation to first seizure, volume of metrizamide injected, or clinician performing the myelography.

Anesthesia, General↗

Evaluation of spinal infections by plain radiographs, computed tomography, intrathecal metrizamide, and CT-guided biopsy.

16 cases of spinal infection were reviewed to evaluate the usefulness of plain radiographs, noncontrast computed tomography (CT), computed tomographic metrizamide myelography (CTMM), plain film metrizamide myelography, and CT-guided biopsy techniques. Noncontrast CT was more useful than plain films in the evaluation of disc space and bony involvement and soft tissue extension of infection into the paraspinal spaces. CTMM was needed for evaluation of epidural or subdural involvement of infection in the cervical and thoracic spine, while plain film metrizamide myelography was useful as a survey for CTMM. CT-guided biopsy was definitive in establishing the etiology of the offending organism.

Adolescent↗

Iohexol versus metrizamide for cervical myelography: double-blind trial.

Cervical myelography was performed by lateral C1-C2 puncture in 60 patients. Thirty patients received iohexol (an investigational aqueous contrast agent) and 30 received metrizamide in order to provide a prospective, randomized, double-blind trial comparing these contrast media. The two media produced radiographs of equal quality. Contrast-related morbidity was suffered by four patients (13%) in the iohexol group and by 11 patients (37%) in the metrizamide group. These features indicate that iohexol is superior to metrizamide as a contrast agent for cervical myelography.

Adult↗