Maximizing opacification during excretory urography: effect of low-osmolarity contrast media.

Because of improved patient tolerance and decreased risks of idiosyncratic reaction, low-osmolarity contrast media are increasingly used for excretory urography. However, physiologic differences among patients may affect the optimal time for acquiring diagnostic radiographs during the pyelographic phase of the examination. A prospective, randomized, physician-blinded comparative study of 60 adult patients was undertaken to determine if the time to peak opacification of the pyelocaliceal systems differs with different doses of nonionic and ionic contrast media. Three doses of contrast media were used: a high dose (based on body weight) of a high-osmolarity ionic contrast medium, a high dose (based on body weight) of a low-osmolarity non-ionic contrast medium and a lower, fixed dose of a low-osmolarity nonionic contrast medium. The diagnostic quality of the radiographs did not differ statistically with the dose or the contrast medium. However, acquiring an additional radiograph during abdominal compression greatly increased the chance of obtaining at least one radiograph with maximal diagnostic information during the pyelographic phase. Despite potential differences among contrast media in the degree of pyelocaliceal opacification or distension and diuresis, it is not necessary to modify the timing of film acquisitions during excretory urography when lower doses of low-osmolarity agents are administered.     

New and old contrast agents: Physiology and nephrotoxicity

Newer contrast agents have recently been developed to improve patient safety and imaging quality. This survey examines renal handling of contrast media, mechanisms of contrast enhancement and questions related to renal toxicity. Methods to minimize contrast-medium-induced acute renal failure are suggested. The introduction of low osmolality contrast media promises reduced patient risk and improved renal enhancement.     

Newer contrast agents for urography

New low-osmolality ratio-3 contrast media have been shown to have less toxicity than currently used contrast media. In intravenous excretory urography, these agents give significantly higher urinary iodine concentrations, produce less diuresis, and are better tolerated by patients because of fewer unpleasant side effects. These newer low-osmolality contrast media have significant advantages in intravenous urography.     

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.     

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 contrast dose reduction for excretory urography using computed radiography

We prospectively investigated whether performing excretory urography by computed radiography (CR) - with CR's broader dynamic range and potential for post-processing - would permit lower contrast dose while maintaining usual image quality. The rationale for this experiment was to evaluate whether CR had potential in reducing the risks and costs associated with urography. Sixty sequential patients were randomly assigned to undergo computed urography with either our full (282 mg I/kg body weight) or half our usual dose (141 mg I/kg body weight) of intravenous 60% diatrizoate meglumine. Three blinded observers judged automatically post-processed full dose tomograms and KUBs as qualitatively superior to both automatically post-processed and individually, interactively post-processed half dose images. Thus, post-acquisition image manipulation could not fully compensate for diminished image quality due to contrast dose reduction.     

Comparison of intravenous drip infusion excretory urography using ionic and non-ionic contrast media

Ionic and non-ionic contrast media were compared for use in intravenous drip infusion excretory urography. Sixty consecutive cases were classified alternately into two groups, ionic and non-ionic, excluding cases which were known to have factors affecting contrast ability adversely, such as hydronephrosis, renal failure and so on. Each group consisted of 30 cases. A hundred ml of the ionic contrast medium (Diatrizoate--60% Urografin) or non-ionic contrast medium (Iopamidol--Iopamiron 300) was administered I.V. by drip infusion, each infusion taking less than 10 minutes, using a 18 G needle, and 0-minute, 10-minute and 20-minute films were obtained. Visibility of nephrogram, calyceal system, renal pelvis, ureters and bladder were evaluated, ranging from 0 to 3, by six radiologists who were not informed of the contrast medium used. Some detailed factors such as radiographic contrast and fullness of the collecting system and of the bladder were also analyzed. Visualization rate of the ureters was defined as the length of visualized ureters divided by the distance between the renal pelvis and the ureteral orifice of the bladder. There was no significant difference in visualization of nephrogram between the two groups. However, the non-ionic group was superior to the ionic group in visualization of the calyceal system and ureters with statistical significance, probably due to higher radiographic contrast of non-ionic medium. There was no statistical significance between the two groups, in fullness of the calyceal system and visualization rate of the ureters, whereas the ionic group was superior to the non-ionic group in fullness of the bladder.(ABSTRACT TRUNCATED AT 250 WORDS)     

MR contrast agents,the old and the new

Magnetic resonance (MR) contrast agents are increasingly being used to help detect and characterize various neoplastic, inflammatory and functional abnormalities. The extracellular, non-specific contrast agents gadolinium chelates are by far the most widely used. Over the past few years a number of MR organ specific contrast agents have been introduced. MRI contrast agents are generally safe and well tolerated. The present review summarizes the properties, main characteristics and imaging applications of commercially available compounds as well as safety of these agents in normal and high-risk patients.     

MR contrast agents, the old and the new

Magnetic resonance (MR) contrast agents are increasingly being used to help detect and characterize various neoplastic, inflammatory and functional abnormalities. The extracellular, non-specific contrast agents gadolinium chelates are by far the most widely used. Over the past few years a number of MR organ specific contrast agents have been introduced. MRI contrast agents are generally safe and well tolerated. The present review summarizes the properties, main characteristics and imaging applications of commercially available compounds as well as safety of these agents in normal and high-risk patients.     

Iohexol for excretory urography: a comparative study

A new iodinated nonionic contrast agent (Iohexol) was compared to an ionic contrast agent (renografin 60) in a double-blind study. Fifty-five patients with normal renal function were studied for incidence of undesirable side-effects and quality of the resultant excretory urogram. No major adverse reactions occurred. Minor side-effects due to the contrast occurred more than two times as often with Renografin than when Iohexol was used. The quality of visualization of the collecting system on urography was considered excellent in 44% of the patients receiving Iohexol as compared to a 17% frequency when Renografin was used.     

The old and the new: a study of five contrast media for urography

Five contrast media, Conray 280 and 420, Urografin 370, Uromiro Sodium 300 and Niopam 370, were compared in a randomised trial involving a total of 482 patients. The best urographic agent was Conray 420 and the worst Conray 280, these control agents defining the ends of the scoring system. Uromiro Sodium 300 was very nearly as good as Conray 420. A non-ionic agent, Niopam 370, scored nearly equal with Urografin 370; both were rather better than Conray 280. There was little difference in minor reactions between the media. No reason was found to prefer non-ionic to ionic agents for general use in urography; indeed for a diagnostic examination the sodium salt of an ionic agent is preferable.     

Orthotopic neobladder reconstruction: findings on excretory urography and CT

OBJECTIVE: The excretory urographic and CT appearance of orthotopic ileal neobladder reconstruction after cystectomy and its complications are described. MATERIALS AND METHODS: We retrospectively reviewed the excretory urograms and CT scans of 32 patients (29 men and three women, 35-76 years old) with transitional cell carcinoma of the bladder who underwent orthotopic neobladder reconstruction with anastomosis to the native urethra after cystectomy. The radiologic review consisted of 25 excretory urograms in 20 patients and 37 CT scans in 21 patients. RESULTS: On excretory urography, the afferent segment of the neobladder was identified as a contrast-filled structure in all 20 patients, and was located in the right lower quadrant in 18 (90%). On CT, the afferent segment and the neobladder were identified in all 21 patients. Delayed imaging performed after initial scanning in 12 (57%) of 21 patients was helpful for revealing detailed anatomy such as the ureteral-afferent limb anastomoses. Complications occurred in two patients and were caused by a lymphocele in one and a urine leak from the neobladder in the other. In six other patients we found evidence of recurrent or metastatic tumor or both: two had local pelvic recurrence and pelvic nodal metastases, two other patients had metastatic nodal disease, one patient had a malignant distal ureteral stricture, and the sixth patient had distant osseous metastases. CONCLUSION: Orthotopic neobladder reconstruction after cystectomy has a characteristic appearance on both excretory urography and CT. Knowledge of this appearance and the altered anatomy is useful to recognize complications and tumor recurrence. Delayed images during excretory urography and CT are useful to define the ureteral-afferent limb anastomosis with the neobladder and also to differentiate between postoperative collections.     

Radiographic findings and hypotensive reactions in excretory urography

The radiographic findings and the hypotension patterns were reviewed in 19 patients having hypotensive reactions in routine excretory urography using ionic contrast medium. The lowest systolic blood pressure was above 80 mmHg in 10 patients while below 80 mmHg in remaining 9 patients. The urogram was unremarkable as long as the systolic blood pressure was preserved above 80 mmHg. In 2 patients, whose systolic blood pressure decreased quickly beyond 80 mmHg immediately after injection of contrast medium, the pyelogram was faint or non-visualized. On the other hand, in 4 patients, whose systolic blood pressure decreased beyond 80 mmHg in several minutes after injection of contrast medium and remained under 80 mmHg for more than 20 minutes, the nephrogram was dense and the pyelogram was faint or non-visualized. Although systolic blood pressure decreased beyond 80 mmHg, the urogram was unremarkable in 3 patients. This was due to the delayed hypotension or the short duration of hypotension.