Diagnostic efficacy of excretory urography with low-dose, nonionic contrast media.

A prospective, randomized, physician-blinded study was conducted to determine whether a smaller dose of low-osmolar, nonionic contrast medium can provide diagnostic information on excretory urograms equivalent to that obtained with higher doses of ionic and nonionic contrast agents. One hundred fifty adult patients who underwent excretory urography received a high-dose ionic contrast medium (diatrizoate sodium), high-dose nonionic contrast medium (iohexol), or low-dose nonionic contrast medium (iohexol). All urograms were scored for diagnostic quality. No difference in urographic quality was detected among the different doses of contrast media. The lower dose of low-osmolar nonionic contrast medium provided equivalent diagnostic information. The quality of the nephrotomograms, ureteral image, and overall image was slightly greater with diatrizoate than with a small dose of iohexol, but the difference was not significant. This study suggests that excretory urograms obtained in relatively healthy, well-prepared patients with smaller, less expensive doses of a nonionic contrast agent are at least diagnostically equivalent to those obtained with typical higher doses of ionic and nonionic agents.     

Iotrolan in urography: efficacy and tolerance in comparison with iohexol and iopamidol

Iotrolan was compared with iohexol and iopamidol for efficacy and general tolerance in excretory urography in three controlled, randomized, inte-individual, double-blind studies. Two hundred and eighty-four patients received fixed doses of 100 ml, 120 ml or 150 ml iotrolan 280 or iohexol 300/iopamidol 300 by rapid or bolus injection. Contrast quality in films taken 3–40 min after injection was rated by experienced radiologists both on an overall basis and with regard to distinct anatomical regions (parenchyma, pelvicalyceal system, ureter, bladder). In all studies, contrast quality was assessed as better in the iotrolan group. In two studies (dosages 100 and 120 ml), significant differences in contrast quality were found in lavour of iotrolan (P < 0.05), and in the third study (dosage 150 ml) there was a trend towards better contrast quality in the iotrolan group (P = 0.06). General tolerance of iotrolan was good with only minor side effects (iotrolan 6.3%, iohexol/iopamidol 9.9%), but the difference was not significant. No severe adverse reactions were observed with iotrolan. In comparison with non-ionic monomers, iotrolan shows very good efficacy and general tolerance for excretory urography.     

Iotrolan in urography: efficacy and tolerance in comparison with iohexol and iopamidol

Iotrolan was compared with iohexol and iopamidol for efficacy and general tolerance in excretory urography in three controlled, randomized, inte-individual, double-blind studies. Two hundred and eighty-four patients received fixed doses of 100 ml, 120 ml or 150 ml iotrolan 280 or iohexol 300/iopamidol 300 by rapid or bolus injection. Contrast quality in films taken 3–40 min after injection was rated by experienced radiologists both on an overall basis and with regard to distinct anatomical regions (parenchyma, pelvicalyceal system, ureter, bladder). In all studies, contrast quality was assessed as better in the iotrolan group. In two studies (dosages 100 and 120 ml), significant differences in contrast quality were found in lavour of iotrolan (P < 0.05), and in the third study (dosage 150 ml) there was a trend towards better contrast quality in the iotrolan group (P = 0.06). General tolerance of iotrolan was good with only minor side effects (iotrolan 6.3%, iohexol/iopamidol 9.9%), but the difference was not significant. No severe adverse reactions were observed with iotrolan. In comparison with non-ionic monomers, iotrolan shows very good efficacy and general tolerance for excretory urography.     

Preclinical evaluation of iotrolan as a contrast medium for angiography and urography]

Efficacy and tolerability of iotrolan, a nonionic isotonic dimer, as a contrast medium for angiography and urography were investigated in animals. In the arteriography of rabbit femur, the efficacy of iotrolan 280 mgI/ml was as good as iopamidol 300 mgI/ml and better than meglumine diatrizoate 306 mgI/ml. In rat urography, the efficacy of iotrolan 280 mgI/ml was better than both iopamidol 370 mgI/ml and iohexol 350 mgI/ml. Vascular pain was less with iotrolan 280 mgI/ml than with iohexol 300 mgI/ml in rats. Effect of iotrolan on the pulmo-cardiovascular parameters, arterial pO2, hematocrit and plasma osmolality was less than iopamidol and diatrizoate in rabbits. Iotrolan induced no renal dysfunction and diuresis where iopamidol induced diuresis in rats. Effect of iotrolan on the blood coagulation was similar to nonionic monomers and less than diatrizoate in rabbits. Because of its isotonicity, iotrolan induced little water shift in the blood vessel and urinary tract, which would result in good efficacy and tolerability. These results suggest that iotrolan is superior to ionic and nonionic monomers for angiography and urography.     

Iodixanol in paediatric gastrointestinal imaging: safety and efficacy comparison with iohexol

Iodixanol (Visipaque) is a dimeric, non-ionic iodinated contrast medium that is isotonic with blood at all clinically relevant concentrations. Iodixanol was compared in a randomized, double blind, parallel group, phase III multicentre trial with a monomeric, non-ionic contrast medium, iohexol (Omnipaque), at two concentrations assessing safety, tolerability and radiographic efficacy during contrast enhanced gastrointestinal radiography examinations of children. 154 children entered the trial; 152 formed the safety population and 147 the efficacy population. All examinations were performed following standard departmental practice. Children were assigned into either a high or low concentration group (iodixanol, 150 mgI ml(-1) and 320 mgI ml(-1) vs iohexol, 140 mgI ml(-1) and 300 mgI ml(-1)). The primary outcome measure for efficacy was the overall quality of visualization, which was assessed using a 100 mm visual analogue scale (VAS). The secondary efficacy variables assessed were quality of contrast opacification, mucosal coating and overall quality of diagnostic information. Safety evaluation involved patient follow-up for at least 48 h. Taste acceptance was also assessed. There was no statistically significant difference between the two contrast media with regard to the primary and secondary efficacy variables assessed, although higher ratings were observed for iodixanol. The 100 mm VAS score overall was 86 mm for iodixanol and 82 mm for iohexol (95% confidence interval -2.56, 10.42). The frequency of adverse events was lower for patients receiving iodixanol. Adverse events, mainly diarrhoea, occurred in 12 patients (16.2%) in the iodixanol group and 28 patients (35.9%) in the iohexol group. This reached statistical significance (p=0.006). Overall, iodixanol is well suited for examinations of the gastrointestinal tract, giving good efficacy results and fewer adverse events than iohexol.     

Intravenous urography with a new non-ionic contrast media in a clinical phase III study: iopentol vs iohexol

The safety and diagnostic efficacy of iopentol 300 mg I/ml were compared with iohexol 300 mg I/ml in 300 patients submitted for urography. The study was carried out as a double-blind, randomised parallel study where 149 patients received iopentol and 150 patients iohexol. There were no significant differences between the patients receiving the two contrast media with regard to demographic parameters, rate of injection or total dose of injected contrast media. No changes in blood pressure and no clinically important changes in heart rate were detected in the two groups. No serious adverse effects occurred. Seven patients (5%) in the iohexol and 12 patients (8%) in the iopentol group experienced adverse effects other than a sensation of warmth. Fourteen iohexol patients (9%) and 18 iopentol patients (12%) experienced warmth related to the contrast injection. Excellent films were obtained in most patients and no difference in diagnostic quality between iopentol and iohexol was observed.     

New and old contrast agents: Pharmacology,tissue opacification,and excretory urography

In equivalent doses for intravenous urograms conventional ionic contrast agents give iodine concentrations in the urine of approximately 30 mg iodine/ml, nonionic contrast media provide approximately 50 mg iodine/ml, and the ionic dimer Hexabrix approximately 70 mg iodine/mL. These new low osmolality, contrast media provide significantly higher urinary iodine concentrations than conventional ionic contrast media, provide better diagnostic quality excretory urograms, better patient tolerance, and fewer adverse side-effects and serious reactions. These new low osmolality, contrast media have significant advantages in intravenous urography in both safety and efficacy when compared to conventional higher osmolality contrast media.     

Iodixanol in intra-arterial cerebral digital subtraction angiography: a comparison with iohexol

We randomised 86 patients undergoing intra-arterial cerebral digital subtraction angiography (IADSA) to receive iodixanol (Visipaque; Nycomed, Oslo, Norway) 150 mgI/ml or iohexol (Omnipaque; Nycomed) 140 mgI/ml. The efficacy and safety of these two contrast media were compared: efficacy by evaluating the diagnostic information and radiographic density yielded by the angiograms, safety by recording all discomfort connected with the injections, and all adverse events up to 24 h after the investigation. Diagnostic information was optimal in all patients and the overall radiographic density optimal in all but one (iohexol) (P=0.49). A feeling of warmth, the only discomfort reported, was experienced by 43% and 54% of patients receiving iodixanol and iohexol, respectively (P=0.26). Two patients in the iodixanol group and five in the iohexol group reported one adverse event (nausea, dizziness, visual disturbance or paraesthesiae) (P=0.30); all were of mild severity except for one moderate adverse event in each group. Iodixanol 150 mgI/ml and iohexol 140 mgI/ml were demonstrated to be suitable for IADSA, with no clinically or statistically significant differences in efficacy, discomfort or adverse events.     

High-dose iohexol myelography

Lumbar myelography was performed with high volumes of iohexol (15-24 ml) at a concentration of 180 mgI/ml (average dose, 20 ml) in 48 patients. In 44 patients receiving more than the currently recommended upper dose limit of 17 ml, the frequency of headache (41%), nausea (14%), and vomiting (9%) was comparable to results for routine-dose lumbar metrizamide myelography. Overall, adverse reactions were more frequent, particularly at the highest dose levels, than reported for conventional-dose iohexol myelography. However, there were no occurrences of neuropsychiatric disorder, encephalopathy, or seizure. High-dose technique allows superior visualization of upper lumbar and conus detail and may be advantageous in patients with large subarachnoid spaces and in multi-level examinations. This study supports the results of previous trials that suggested the relative safety of iohexol as a contrast agent and extends those observations to a higher dose range. Because of the increased rate of adverse reactions at the highest dose levels (despite the absence of major adverse reactions), iohexol should continue to be used conservatively, with doses carefully tailored to each examination.     

Myelography with a dimeric (iodixanol) and a monomeric (iohexol) contrast medium: a clinical multicentre comparative study

The purpose of this study was to evaluate and compare the radiographic efficacy and safety of iodixanol (Visipaque; 270 and 320 mg I/ml) and iohexol (Omnipaque; 300 mg I/ml) in myelography. The study was randomized, double-blind and comparative including 398 patients from five European university clinics. The radiographic visualisation was evaluated as poor, good or excellent. Adverse events were recorded by interviewing the patients after the myelography, and each patient was given a questionnaire to be returned after 1 week. In cervical myelography with cervical puncture more films with excellent quality was obtained after iodixanol 320 mgI/ml compared with iohexol 300 mgI/ml (p = 0.009). Also in lumbar myelography iodixanol 320 mgI/ml compared favourably with iohexol 300 mgI/ml (p = 0.006). The most frequent adverse event was headache, which occurred in 5–35 % of patients during the first 24 h and in 19–61 % within the first 7 days, depending on the centre. There was no difference in frequency and severity of the adverse effects between the contrast media. Received 13 March 1997; Revision received 29 December 1997; Accepted 5 January 1997     

Contrast medium injection on CT during hepatic arteriography: comparison of two protocols

To assess the optimum method of contrast medium injection on CT during hepatic arteriography (CTHA), we performed this procedure in 37 patients using two consecutive protocols (A and B) employing different concentrations of iodine (iohexol at 140 mgI/ml and 300-350 mgI/ml), flow rates (2 ml/sec and 1 ml/sec), and contrast medium volumes (60 ml and 30 ml). Mean parenchymal enhancement of the right lobe and left lateral segment were measured and compared. Enhancement varied significantly more with protocol B, especially in the left lateral segment. These results suggest that a low iodine concentration and high injection rate are suitable for CTHA, to avoid nonuniform parenchymal enhancement.     

Use of low-osmolality contrast medium does not increase prevalence of medullary sponge kidney.

To assess the prevalence of intrapapillary linear collections of contrast medium as well as of homogeneous papillary blush on excretory urograms obtained with a low-osmolality contrast medium, iohexol was used in 300 patients. Intrapapillary linear collections of contrast medium (ie, three or more linear collections of contrast material within a papilla) were found in 10 (9.5%) of the 105 patients with renal stone disease and two (1.0%) of the 195 patients without nephrolithiasis (P less than .001). These prevalences are similar to those found in a previous study with use of a high-osmolality contrast medium (sodium amidotrizoate). The difference in the prevalence of homogeneous papillary blush between stone formers and non-stone formers was nonsignificant. The authors conclude that intrapapillary linear collections of contrast medium on excretory urograms obtained with use of a low-osmolality contrast medium should be considered to have the same clinical significance as those on excretory urograms obtained with use of a high-osmolality contrast medium, that is, as indicating the presence of medullary sponge kidney.     

Assessment of pancreatic CT enhancement using a high concentration of contrast material

OBJECTIVE: To evaluate the usefulness of pancreatic enhancement using a high concentration of contrast material in CT. METHODS: We performed abdominal CT on 125 patients after dividing them at random into five groups with two different concentrations, two different injection rates and three different injection doses: group A: 100 ml, 300 mgI/mL, 3 mL/sec; group B: 2 mL/kg, 300 mgI/mL, 3 mL/sec; group C: 1.5 mL/kg, 370 mgI/mL, 3 mL/sec; group D: 2 mL/kg, 300 mgI/mL, 5 mL/ sec; and group E: 1.5 mL/kg, 370 mgI/mL, 5 mL/sec. Among these five groups, the two groups given a concentration of 370 mgI/mL received a dose of 1.5 mL/body weight. RESULTS: The peak enhancement value of the pancreas was significantly greater in group E than in groups A and B. However, no statistically significant differences were found among the other groups. CONCLUSION: The fast injection rate using the high concentration of contrast medium provided greater enhancement of the pancreas than the slow injection rate using the routine concentration of contrast medium, and pancreatic CT enhancement depended more on the dose of iodine per second than on that of total iodine.     

High- and low-osmolar contrast agents in urography: a comparison of the appearances with respect to pyelotubular opacification and renal length

The incidence of pyelotubular opacification and the change in renal length during intravenous urography with iohexol (Omnipaque) was compared with sodium/meglumine diatrizoate (Urografin). Pyelotubular opacification was seen in 14 out of 29 urograms performed with iohexol compared with one out of 28 urograms performed with sodium/meglumine diatrizoate. This increased incidence is statistically significant and has not been previously documented. The increase in renal length following intravenous contrast medium was similar for both iohexol and sodium/meglumine diatrizoate. The significance of these findings with respect to the interpretation of urograms performed with iohexol is discussed.     

Evaluation of hypervascular hepatocellular carcinoma in cirrhotic liver by means of helical CT: comparison of different contrast medium concentrations within the same patient

PURPOSE: To compare enhancement of the aorta, portal vein, liver, and tumor with contrast medium of a higher iodine concentration to that with one of a standard iodine concentration for liver dynamic CT within the same patient with known liver cirrhosis and hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Fifty-three patients with known cirrhosis and HCC underwent repeat computed tomographic (CT) examinations within three months, the first with either 300 (n=26) or 370 mgI/ml (n=27) of nonionic contrast material. In the second examination, only concentration was altered. In 28 patients, weight was equal to or more than 65 kg, and in 25 patients it was less than 65 kg. The CT numbers (HU) of the aorta, portal vein, liver, and tumor were obtained, and CT attenuation was compared between the two concentration studies. The degree of enhancement was scored qualitatively. RESULTS: Mean enhancement values of the aorta, liver, portal vein, and tumor were greater with the 370 mgI/ml injections than with the 300 mgI/ml injections throughout the study. In visual analysis, the difference in aortic, portal venous, liver, and tumor enhancement was not statistically significant between the two groups in patients weighing less than 65 kg. However, in patients weighing 65 kg or more, strong aortic and portal venous enhancement (rated as good or excellent) occurred more frequently with the 370 mgI/ml injections than with the 300 mgI/ml injections. CONCLUSION: Higher contrast enhancement was achieved in patients who received 370 mgI/ml of contrast material, resulting in better tissue contrast between liver parenchyma and HCCs. However, this difference was not visually significant in patients weighing less than 65 kg.     

Multiphase contrast-enhanced CT of the liver with a multislice CT scanner: effects of iodine concentration and delivery rate

PURPOSE: To determine whether or not high-concentration contrast material is useful in multiphase contrast-enhanced CT of the liver with a multislice CT scanner. MATERIALS AND METHODS: One hundred twenty-four examinations, in which first- and second-pass acquisitions (double arterial phase imaging) were performed during a single breath-hold followed by third-pass acquisition, were randomized into three protocols: contrast injection at 0.07 mL/kg body weight/sec over 30 sec at an iodine concentration of 300 mgI/mL in group 1, contrast injection at 0.06 mL/kg body weight/sec over 30 sec at an iodine concentration of 350 mgI/mL in group 2, and contrast injection at 0.07 mL/kg body weight/sec over 25.7 sec at an iodine concentration of 350 mgI/mL in group 3. Each group received an equivalent iodine dose per kg body weight (2.1 mL/kg of contrast material of 300 mgI/mL). Contrast enhancement in each acquisition was measured in the aorta, portal vein, and liver. RESULTS: No statistically significant differences were seen between groups 1 and 2 in any enhancement in any acquisition. In group 3, aortic enhancement in the first-pass acquisition was significantly more intense than in groups 1 and 2, while portal venous enhancement and hepatic enhancement were equivalent. CONCLUSION: Shortening the injection duration for a given iodine dose with high-concentration contrast material (group 3) can achieve improved arterial enhancement on arterial phase images.     

Low-osmolality contrast media: Dosage comparison of ioversol and iohexol for cranial computed tomography

One hundred patients undergoing cranial computed tomography were evaluated in this prospective, randomized, double-blind comparative study. Patients received 50 mL of ioversol 320 (16 g iodine), 75 mL of ioversol 320 (24 g iodine), 100 mL of iohexol 240 (24 g iodine), 100 mL of iohexol 300 (30 g iodine) or 150 mL of iohexol 240 (36 g iodine). Twenty patients were enrolled in each treatment group. No patient in any treatment group experienced any contrast-media-related adverse reaction. Results of this study coupled with our prior work suggests that the lowest dose and optimal concentration of low-osmolality contrast media necessary to produce diagnostic cranial computed tomography is 32 g of iodine administered in a concentration of 320 mg/100 mL iodine.     

Iohexol in paediatric myelography

Summary Iohexol was introduced by lumbar puncture in a series of 148 consecutive children aged between 5 days and 16 years referred for myelography; no patient was excluded. Initially, iohexol 180 mgI/ml was used in dosage proportional to body weight varying between 5 ml and 15 ml. During the later part of the trial concentration of iodine was increased to 240 mg/ml for cases in which the dorsal region was of particular interest (69 patients) and to 300 mg/ml for 8 cervical studies. The total dose ranged up to 4.8 g and varied between 0.03 g and 0.51 gI/kg body weight. In all patients, neurological examinations were performed before and at 24 h and observations for adverse reactions continued over a period of 48 h. The contrast medium was run up to the foramen magnum or basal cisterns in 128 patients and to the upper dorsal region in the other 20. In the first 62 patients vital studies were performed over the period of the myelogram and for 24 h following, and an additional limited neurological examination was made at 6 h, and in the first 26 cases of the series EEG's were done before and at 24 h after the myelogram. Minor variations in pulse rate and blood pressure were observed but these were not of sufficient magnitude to be of clinical significance. In 7 patients there was minor, generally slow wave abnormality on the EEG taken after the procedure, but no spike or epileptogenic activity was obserse reactions. Focal increase in neurological signs, associated with backache and probably related to the mechaniccs of lumbar puncture and myelography, occurred in 3 tumour patients; otherwise no change in neurological condition was observed in any case. Minor reactions were observed in 24 other patients (16.2%); vomiting 14 (9.5%), headache 8 (5.7%), backache 6 (4.1%), stomache ache 2 (1.5%), mild pyrexia 3 (2.0%). The incidence and severity of these reactions was considerably less than with metrizamide myelography and all resolved within 2 days of the iohexol injection. In conclusion, iohexol has significant advantages over previously used non-ionic contrast media and is suitable for paediatric myelography.     

Hemodynamic and electrophysiologic effects of low osmolar contrast agents during coronary angiography in the dog and the rabbit

The electrophysiological tolerability of ioxaglate (160 mgI/ml) and iohexol (140 mgI/ml) was assessed in rabbits (n = 12 per group). There was a significant induction of ventricular fibrillation in the group given iohexol. An explanation for this phenomenon could be the lack of sodium in this preparation. Ioxaglate, iopamidol and iohexol (all at 320 mgI/ml) were also compared during coronary angiography in the dog (n = 10) after bolus administration, using the carotid approach (5 and 8 ml-0.5 ml/sec). Each dog received all the compounds in the left coronary artery and selectively in the left anterior descending artery, at random. Four dogs had lethal ventricular fibrillations after iohexol. Iopamidol and iohexol induced significant bradycardia in comparison with saline. A biphasic effect on myocardial contractility was observed with all contrast media: a short-lasting, typical decrease in dP/dt was seen with ioxaglate by the end of injection, while iohexol and iopamidol caused a similar negative inotropic effect in some cases (25%) after increasing dP/dt. The positive inotropic effect was greater with iopamidol and iohexol than with ioxaglate (p less than 0.05). The possible clinical consequences of the lack of sodium in contrast media preparations and of the changes in myocardial function are discussed in the light of the present results.     

Non-ionic contrast media: a comparison of iodine delivery rates during manual injection angiography

Iodine delivery rates (IDR) of five commonly used non-ionic contrast media were determined at room temperature (24 degrees C) and body temperature (37 degrees C). Contrast media of strength 300 mgI/ml were also evaluated at 50% dilution (150 mgI/ml) with N-saline. Iodine delivery differed significantly (p less than 0.005) between samples at room temperature: Omnipaque 350 (1163 mg/s) less than Niopam 370 (1311 mg/s) less than Omnipaque 300 (1422 mg/s) less than Niopam 300 (1635 mg/s) and Ultravist 300 (1636 mg/s). Niopam 300 and Ultravist 300 delivered 41% more iodine per second than Omnipaque 350 at room temperature. Similar differences were identified at body temperature, while delivery of individual media was on average 23.5% greater than at room temperature. No significant difference between iodine delivery rates of diluted media at room temperature or body temperature was identified. The results demonstrate that iodine delivery and hence vascular opacification are better achieved during hand-injection arteriography by using relatively low viscosity media such as Niopam 300 or Ultravist 300. In digital subtraction arteriography all 300 strength contrast media diluted to 150 strength are equally effective.