Ioxilan, a third generation low osmolality nonionic contrast medium. Systemic and renal hemodynamic effects

The choice between high cost, low toxicity nonionic contrast media (CM) and low cost ionic CM poses a dilemma for radiologists. Ioxilan, a third generation nonionic CM, is obtained by simple conversion from an ionic CM. To examine how this economically promising, low osmolality CM (570 mOsm at 300 mgI/ml) affects canine systemic and renal hemodynamics, IV bolus injections of 350 mgI/ml at 2 ml/kg of Iohexol and Ioxilan were compared. Satisfactory nephrograms and pyelograms were produced by both agents, without significant differences. The effects on systemic and renal hemodynamics were minimal and statistically equal for both CM. The acute systemic and renal responses and radiographic image quality of Ioxilan and Iohexol confirm that the two compounds are biologically equivalent, and that the novel molecular design employed in Ioxilan to achieve very low osmolality also provides good biological tolerance.     

Excretory urography with iohexol: evaluation in children

A multicenter clinical study was conducted using iohexol, a second-generation nonionic contrast medium, for excretory urography performed in 130 children. Doses of iohexol (300 mg iodine/ml) ranged between 150 and 660 mgI/kg (0.5 and 2.2 ml/kg). Iohexol was tolerated well, and no significant adverse reactions occurred. Sixty-five iohexol urograms were evaluated to determine the minimum dose for adequate visualization of the kidneys and collecting systems. A dose greater than 300 mgI/kg (1.0 ml/kg) always resulted in a urogram of diagnostic quality, while visualization was insufficient for diagnosis in 10% of studies done with doses of 150-300 mgI/kg (0.5-1.0 ml/kg). Another 65 iohexol urograms were compared in a blinded manner with a similar number of studies performed using iothalamate meglumine at comparable iodine concentration and dose. Visualization of calyces and pelvoinfundibular structures achieved with iohexol was rated better with statistical significance, but there was no difference in visualization of the renal parenchyma or ureters. Use of iohexol in excretory urography may be advantageous in children who are at greatest risk for an adverse reaction to contrast media or in those most likely to benefit from use of a low osmolality contrast agent.     

Comparison of iopamidol 150 and 370 with the same iodine dosage (37 g) in urography]

Two different volumes of iopamidol (250 and 100 ml, respectively) containing 37.5 and 37 g of iodine in different concentrations (150 mgI/ml and 370 mgI/ml) were injected in the same time (10 minutes) with varying injection rates, to compare diagnostic effectiveness, image quality, distension of the collecting system, and influence of the better iodine concentration. Sixty patients of both sexes were randomly subdivided into two groups. Their renal function, blood pressure and pulse rate were normal. Their weight ranged 55-85 kg, not to change the distribution volume of the contrast medium. None of them had been given iodine compounds recently. Radiographs were taken 2, 5, 15, 25, and 30 minutes after the end of the injection. The image quality of nephrograms, pyelograms, bladder views and the degree of collecting system filling were evaluated by a blind study, using grading scores (0 to 3). In both groups image quality and degree of filling were satisfying; the volume of injected iopamidol had poor significance. The clinical findings confirm that, with a nonionic contrast medium, iodine concentration in the collecting system is the most important factor for image quality.     

A comparison of the systemic responses to rapid intravenous injections of ioxilan, iohexol, and diatrizoate in rabbits

Rapid intravenous injections of contrast media are used for angiocardiography, intravenous digital subtraction angiography (DSA), and rapid scan computed tomography procedures. These rapid intravenous injections have been shown to produce significant hemodynamic changes that appear related to contrast media osmolality. In this study the systemic responses to 2-second injections at a dose of 1.5 mL/kg were compared for a new nonionic agent, ioxilan (350 mgI/mL), and for iohexol (350 mgI/mL), meglumine/sodium diatrizoate (370 mgI/mL), and saline. Ioxilan has a lower osmolality and viscosity than iohexol and is formulated with a 3 mM sodium citrate as a buffer and anticoagulant. All of the test solutions produced statistically significant changes in arterial pressure and respiratory rate (P less than .05, Student's t-test). The decrease in arterial pressure seen with diatrizoate (20.1%) was significantly greater than the decrease seen with either ioxilan (10.2%) or iohexol (10.2%). All of the responses observed were transient and would not be of clinical concern in a healthy patient. Ioxilan, which contains the calcium binding agent, sodium citrate, and iohexol appear to cause less systemic effects then diatrizoate.     

Comparison of ionic and nonionic low-osmolar contrast media in coronary arteriography. A crossover study in children

Twenty-six patients with Kawasaki disease were observed in a prospective crossover study to compare coronary arteriography with a nonionic low-osmolar contrast medium, iopamidol 370 mgI/mL, and with an ionic low-osmolar contrast medium, ioxaglate 320 mgI/mL. A slight heart rate change and no severe arrhythmia during coronary arteriography were observed with both agents. Electrocardiographically, QTc elongation and ST-T changes were marked in ioxaglate and minimal in iopamidol. No ventricular fibrillation occurred with either agent. Both contrast media provided adequate visualization for the diagnosis of Kawasaki disease, but the contrast of the images and the visualization of details were better with iopamidol than with ioxaglate. Iopamidol seems to be superior to ioxaglate in pediatric coronary arteriography.     

A comparison of bolus chasing and static digital subtraction arteriography in peripheral vascular disease

The purpose of this study was to compare the techniques of bolus chasing angiography (BCA) and digital subtraction angiography (DSA). 75 patients with symptomatic atherosclerotic peripheral vascular disease were randomly assigned to have their lower limbs examined by BCA or DSA. Dose-area product (DAP), time of examination and dose of contrast medium were measured. Staff doses were measured with personal electronic dosemeters. Image quality was assessed from the laser printed images. DSA produced better images of vessels below the inguinal ligament, particularly the crural vessels (1/76 vs 17/74 non-diagnostic examinations, p < 0.00001) but at a higher DAP (median 53.8 Gy cm2 vs 18.9 Gy cm2, p < 0.01). Contrast medium dose was higher with BCA (29.8 gI2 vs 25.3 gI2, p < 0.01). Staff doses per unit patient dose were 2.3-3.3 times higher with BCA than DSA. Because of the poor long-term prognosis of patients with peripheral vascular disease, the improved image quality obtained by DSA justifies the increased radiation dose.     

A comparison of iopamidol and ioxaglate in CT enhancement

We evaluated the adverse reactions (AR) rate produced in patients to see if any difference related to the diferent chemotoxicities of two low-osmolality contrast media (CM), could be detected. We compared the AR rate intravenous administration for brain or body computed tomography (CT) enhancement of either the ionic CM ioxaglate 320 mgI/ml or the non-ionic iopamidol 300 mgI/ml at a dose of 0.8 gI/kg. Three hundred and thirty patients (164 ioxaglate, 166 iopamidol) were studied according to a randomized double-blind design. AR reported by the patients (subjective) and/or observed by the radiologist (objective) were recorded by the radiologist on the patients record card. Laboratory test were performed prior to and 24 h after contrast administration.Fifty-nine mild to moderate AR occurred in 30 patients (18.3%) receiving ioxaglate, 4 mild to moderate AR occurred in 2 patients (1.2%) receiving iopamidol (P < 0.05). No severe AR occurred in either group.The results of our study are comparative to the available evidence from 16 comparative randomized trials of iopamidol versus ioxaglate both after intraarterial and intravenous administration that gave an overall odds ratio of 3.9 [confidence interval (CI) 95% = 3.1–4.9].The diagnostic efficacy of the two CM was comparable. This study showed that the non-ionic CM iopamidol was better tolerated than the ionic ioxaglate after intravenous administration. We conclude that the chemotoxicity of the molecule influences the AR when CM with comparable osmolality are administered. Correspondence to: Carlo Del Favero     

Optimal iodine dose for 3-dimensional multidetector-row CT angiography of the liver

Purpose

To clarify the optimal iodine dose of contrast material for 3-dimensional multidetector-row CT angiography (3D-MDCTA) of the venous vasculature of the liver using volume rendering technique.

Materials and methods

This study included 103 patients who were randomly assigned to 5 contrast-enhanced MDCT protocol groups with different body-weight-tailored doses of contrast material: 500, 600, 630, 650, and 700 mgI/kg body weight. The arterial, portal, and hepatic parenchymal phases were obtained to evaluate enhancement values of the aorta, portal vein, and hepatic vein. Visualization of the portal and hepatic veins on the volume-rendering images of 3D-MDCTA was evaluated using a 5-point grade. Dunnett's test was used to compare the mean enhancement value and mean grades of image quality (700 mgI/kg dose group was control).

Results

The mean enhancement values of portal and hepatic vein in the group with 500 and 600 mgI/kg were significantly lower than those of the control group. During visual assessment, a significantly lower mean grades were observed in 500 mgI/kg groups for the portal vein, and 500 and 600 mgI/kg groups for hepatic vein. There were no significant intergroup differences in mean enhancement values and visual assessment among the groups using 630 mgI/kg or more.

Conclusion

Iodine doses of 630 mgI/kg was recommended for 3D-MDCTA.     

Radiographic quality and patient discomfort in sialography: comparison of iohexol with iothalamate

We have compared the usefulness of a newly developed, low osmolality contrast medium, Omnipaque 350 (75.49% iohexol, 350 mgI ml-1), for sialography with one of the established, Angioconray (80% sodium iothalamate, 480 mgI ml-1), in a double-blind, prospective randomized clinical trial in 80 patients. The diagnostic quality of the sialograms, pain during the procedure and discomfort subsequently were investigated. There was no difference in either group between the number of sialograms judged as diagnostically useful, although those of excellent quality were significantly more frequent in the Angioconray group. The level of pain on injection of the medium was significantly lower in the Omnipaque group. Eighteen per cent of the patients with Omnipaque had severe or moderate pain on injection of the contrast medium, while 63% had such pain with Angioconray. There was no difference in postprocedural discomfort between the two contrast media. We concluded that the low osmolality contrast medium is more favourable for sialography despite its lower iodine content.     

Optimal delay time for the hepatic parenchymal enhancement at the multidetector CT examination

The objective of this study was to determine the optimal scan delay time after hepatic parenchymal enhancement using a 16-channel multidetector row helical CT (MDCT) scanner. Two hundred fifty-five consecutive patients underwent biphasic CT scans using a 16-channel MDCT. In group A (n = 125), two hepatic venous phase scans (HVP1 and HVP2) were obtained at 40 and 60 seconds, after 100-HU threshold time (T100HU) in the abdominal aorta. In group B (n = 130), HVP1 and HVP2 scans were obtained 50 and 70 seconds after T100HU. Both groups were divided into subgroups that were given different contrast media. Groups A1 and B1 received a contrast medium of 300 mgI/mL; groups A2 and B2 received a contrast medium of 370 mgI/mL. Each patient was injected with contrast medium at a dose of 2 mL/kg at a rate adjusted to the patient's body weight with a constant injection duration of 47 seconds. The attenuation values (HU) for the liver, portal vein, hepatic vein, and aorta were measured. The average HU was compared between the groups. Hepatic enhancement in the images obtained at 50 and 60 seconds after T100HU was greater (P < 0.05) than in images obtained at 40 and 70 seconds. These results were obtained with both contrast media. A few patients showed greater enhancement at a 40 seconds or 70 seconds. Hepatic enhancement was significantly greater in all scans using a contrast medium dose of 370 mgI/mL compared with the 300-mgI/mL dose (P < 0.05). Independent of the concentration of contrast medium, scan delays of 50 to 60 seconds after T100HU may provide optimal hepatic enhancement.     

Evaluation of a contrast examination technique for three-dimensional CT angiography (3DCTA) of the head and craniocervical region

In three-dimensional CT angiography (3DCTA) studies, we make it a rule to use a CT number monitoring system (SureStart, Toshiba Medical Systems Company) to ensure that contrast-enhanced images are acquired at the optimal timing. However, although SureStart can accurately determine enhancement start timing, it is still possible to inject more contrast medium than necessary because the scan start time is not known with certainty. To address this problem, we conducted investigations to determine the ideal contrast examination technique using SureStart and an injector synchronization system. Our results showed that a CT number of 300 HU in the middle cerebral artery (M1) could be obtained with the injection of contrast medium for a period of 45 s (450 mgI/kg) for the head or for 50 s (450 mgI/kg) for the craniocervical region. This makes it possible to perform contrast studies with greater reproducibility by taking individual variation into consideration. Moreover, it was found that comparable results could be obtained by terminating the injection of contrast medium 15 s before the completion of the study and immediately injecting a physiological saline solution flush, permitting the volume of contrast medium to be further reduced.     

组织均衡技术在DR胸部影像中的应用优势

目的　探讨胸部直接数字化X线摄影 (DR)中 ,采用组织均衡技术的DR图像与标准DR图像的差别。方法　从我院2 0 0 3 -0 5所摄的DR胸部影像中按顺序抽取 10 0例作为分析材料 ,通过运用组织均衡技术对图像进行处理 ,比较组织均衡图像与标准DR图像的差别。结果　运用组织均衡技术的图像 ,同一幅图像上不同体厚部位的细节均可清晰显示 ;标准DR图像需调节不同的窗宽、窗位才能清晰显示不同体厚部位的细节。结论　在直接数字化X线摄影中 ,运用组织均衡技术能明显改善先前受体厚影响而难于观察部分的可视性 ,而又不牺牲其他部分的细节显示     

Quantitative and qualitative evaluation of volume of low osmolality contrast medium needed for routine helical abdominal CT

OBJECTIVE: The purpose of our study was to determine the minimum optimal dose of IV contrast medium for helical CT that can preserve image quality while reducing cost. SUBJECTS AND METHODS: Four hundred sixty-three patients from six centers were enrolled in a prospective trial in which patients were randomized into one of four weight-based dose categories of iopromide, 300 mg I/mL: 1.25, 1.50, 1.75, and 2.0 mL/kg. Six of 463 patients were excluded from analysis. A radiologist at each center who was unaware of the volume of contrast medium administered determined whether the scans were acceptable. The responses were analyzed by dose, in aggregate, and by weight. Enhancement values (in Hounsfield units) in regions of interest in the liver, pancreas, aorta, and kidneys were obtained at a single time during the scan. The participating radiologist was unaware of these values. Finally, three additional nonparticipating site observers assessed the images for acceptability, diagnostic quality, and overall level of confidence. A cost model comparing incurred charges in using 150 or 100 mL, or 1.5 mL/kg, of low osmolality contrast medium was developed from experience in an additional 303 patients. RESULTS: We found no clinically significant difference in acceptability of scans at doses greater than 1.5 mL/kg. However, significant variability occurred among the centers. The use of 1.5 mL/kg led to a savings of $9927.16 for 303 patients when compared with the use of 150 mL at list price. The cost is the same for 1.5 mL/kg or use of 100 mL of contrast medium. CONCLUSION: A weight-based dose at 1.5 mL/kg of low osmolality contrast medium can provide acceptable scans in most patients, with a significant cost savings.     

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.     

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.     

Contrast media tonicity. Part I. Effects upon IV-DSA time-concentration curve peak and width: experimental studies

Prior to the formation of an intravenous digital subtraction angiography (IV-DSA) image, contrast medium passes through the lesser circulation and is diluted by the blood volume of the heart and lungs. If the contrast medium alone influences central blood volume or cardiac output, the shape of the resultant time-concentration curve may be degraded. To the extent that contrast medium tonicity reduces curve peak or increases width, image quality for mask mode IV-DSA will suffer. To quantify the effect of contrast medium tonicity upon curve shape, contrast medium (1) at increasing iodine concentration and increasing osmolality and (2) at constant iodine concentration and increasing osmolality was injected into the right atria of mongrel dogs. In both experiments, increasing osmolality was associated with an increase in central blood volume (CBV) and cardiac output. With an increase in CBV, curve peak fell. With an increase in both CBV and cardiac output, curve width was not influenced by increasing osmolality. The effect of osmolality upon CBV was highly variable; in these experiments CBV was influenced more by subject-to-subject variability. However, on the average, higher tonicity contrast media produced curves with lower peaks. These studies suggest that isotonic contrast medium does not increase CBV and that isotonic contrast medium is preferable to hypertonic contrast medium for IV-DSA image formation.     

Computer processed fluoroscopic images for digital intravenous renal angiography

We investigated intravenous digital angiography using computer processed fluoroscopic images. Computer processed fluoroscopy (CPF) was compared to conventional digital subtraction angiography (DSA) in 39 patients referred for renal vessel evaluation. For assessment of CPF the anterior-posterior images were compared with the corresponding digital subtraction angiograms. 79% percent of DSA and 71% of CPF studies were diagnostic. Peripheral injection of contrast medium caused deterioration of CPF images. Skin dose measurements were obtained in 24 patients. The median dose for DSA was 8.2 rad, compared to 1.1 rad for CPF. It is concluded that sophisticated algorithms should be investigated for digital angiography, so that high image quality can be achieved with a reduced radiation exposure.     

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.     

A comparison of a non-ionic dimer, iodixanol with a non-ionic monomer, iohexol in low dose intravenous urography

A prospective, double-blind study of 392 patients randomized into four groups was performed to establish whether diagnostic intravenous urograms could be obtained with a lower dose of iodine when using the dimeric, non-ionic contrast medium iodixanol compared with the monomeric, non-ionic iohexol. Patients received iodixanol or iohexol containing either 9 or 12 g of iodine (gI). The primary parameter was the diagnostic quality of the 6 min film, assessed in a blinded fashion, by consensus, by four radiologists. Iodixanol at both doses was diagnostic in over 90% of cases. Iohexol was only diagnostic in 74% (9 gI) and 81.8% (12 gI). Pairwise comparisons revealed that iodixanol 9 gI was significantly better than both iohexol 9 gI (p = 0.0005) and 12 gI (p = 0.014). No significant difference was present for different doses within the same contrast medium group. Iodixanol resulted in poorer bladder distension than iohexol. Iodixanol caused significantly less discomfort than iohexol.     

冠状动脉能谱CT单能量成像与混合能量成像质量的比较——静态模型的实验研究

目的通过模拟冠状动脉静态模型分析比较能谱CT宝石能谱成像(GSI)与混合能量成像的图像质量。材料与方法采用模拟冠状动脉静态体模,体模内共3支相同的模拟冠状动脉,管腔内斑块采用人造混合斑块(120 kVp下CT值约60.0～148.6 HU)伴有三种不同程度狭窄(25%、50%及75%)。在3支模拟冠状动脉内分别注入3种不同浓度的对比剂进行扫描,模型内对比剂碘浓度由低到高依次为6.25 mgI/ml、7.89 mgI/ml、14.06 mgI/ml,分别将其定为A、B、C组。采用GE Discovery CT 750 HD扫描仪,采集120 kVp下的混合能量模式(包括混合能量标准扫描和混合能量高清扫描标准重组)及GSI能谱扫描模式;每支模拟冠状动脉分别在每种狭窄处选取4个层面的感兴趣区进行测量,分别测量管腔内CT值、模拟斑块的CT值及背景噪声,计算各层面的对比噪声比(con-trast-to-noise ratio,CNR)。同时由两名专业影像医师根据图像显示情况对感兴趣区的轴位及冠状重组图像进行评分。通过CNR及主观评分的比较评价冠状动脉的图像质量。结果比较GSI序列40～140 keV图像的CNR,A～C组均在50～60 keV具有较好的CNR,比较60 keV单能量图像与混合能量图像不同狭窄率条件下A～C组CNR,除A组浓度25%及75%狭窄率的CNR间比较没有统计学差异,B、C组浓度单能量60 keV扫描模式CNR值均高于混合能量扫描模式,其差异有统计学意义。比较不同狭窄率条件下A～C组图像质量的主观评分,60 keV单能量图像与混合能量图像相比,在对比剂浓度较低时(A组及B组)其评分均高于混合能量图像,其差异有统计学意义,而对比剂浓度相对较高的C组内50%及75%狭窄率的GSI 60 keV单能量图像与混合能量模式图像比较图像质量评分无统计学差异性。结论冠状动脉狭窄模型运用宝石能谱CT扫描,在60 keV时能够获得最佳图像质量,优化图像的CNR,较冠状动脉常规混合能量扫描模式具有更好的图像质量。