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| 2. |
- Bååth, Lars, et al.
(författare)
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Effects of nonionic monomeric and dimeric contrast media on the twitching reaction of the rat. Importance of osmolality and electrolyte content
- 1994
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Ingår i: Investigative Radiology. - 0020-9996. ; 29:11, s. 985-989
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Tidskriftsartikel (refereegranskat)abstract
- RATIONALE AND OBJECTIVES. The authors established a rat model of the twitching reaction to contrast media in striated muscle and investigated the influence of nonionic contrast medium on the twitching reaction regarding the nonionic dimer iodixanol compared with the monomer iohexol and the dimer iotrolan. The authors also studied the influences from the electrolyte additions of iodixanol. METHODS. The interval from start of contrast medium injection to start of head movement was compared for iohexol (140 and 350 mg iodine/mL), iodixanol (150 and 320 mg iodine/mL), and iotrolan (300 mg iodine/mL). Comparison was made with mannitol and mannitol containing the same electrolyte concentrations as iodixanol (150 and 320 mg iodine/mL). RESULTS. No differences in latency period were found between iohexol 140 mg iodine/mL (isotonic) and 350 mg iodine/mL (880 mOsm/kg). Iodixanol caused a lesser effect on the twitching reaction than the iohexol solutions and iotrolan. When the electrolytes of iodixanol were added to mannitol (300 mOsm/kg), there was a later onset of the twitching reaction than with electrolyte-free mannitol. CONCLUSIONS. Differences in latency period caused by a change in osmolality were not found. The interval for a twitching reaction was longer with iodixanol than with iohexol, iotrolan, and iso-osmolar mannitol. The weak effect of the iodixanol solution was probably partially caused by the electrolyte content.
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| 3. |
- Bååth, Lars, et al.
(författare)
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Sodium-calcium balance in nonionic contrast media. Effects on the risk of ventricular fibrillation in the isolated rabbit heart
- 1993
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Ingår i: Investigative Radiology. - 0020-9996. ; 28:3, s. 223-227
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Tidskriftsartikel (refereegranskat)abstract
- RATIONALE AND OBJECTIVES. During coronary arteriography the blood is replaced for a short period of time with a contrast medium (CM) solution. The CM may cause a risk of arrhythmias and ventricular fibrillation (VF). Previous investigations have shown that the addition of small amounts of sodium (10-30 mmol/L) to nonionic CM may decrease the risk of VF from these media. Calcium addition to nonionic CM may reduce a negative inotropic effect. In the current investigation, the changed risk of VF from nonionic CM with 19 to 30 mmol/L NaCl was studied when the media also contained calcium or calcium and magnesium. METHODS. An isolated rabbit heart model was used. The risk of arrhythmias and VF from the nonionic monomer iohexol and the nonionic dimer iodixanol containing 19 to 30 mmol/L NaCl with 0 to 2.5 mmol/L calcium as CaCl2 was studied. In the series with iodixanol, 0 to 0.95 mmol/L MgCl2 also was added to the solutions with sodium and calcium, but the role of magnesium was not especially evaluated in the investigation. RESULTS. Nonionic CM with small amounts of NaCl (19-30 mmol/L), without calcium or with calcium at the level of 0.05 to 0.3 mmol/L, caused the lowest risk of VF. When relatively higher additions of calcium reached the physiologic concentration of 2.5 mmol/L, the CM caused a greater risk of arrhythmias and VF. CONCLUSIONS. When calcium is added to a nonionic CM, the concentration of calcium must be balanced against the NaCl concentration to minimize the risk of VF. Excessive calcium concentration will increase the risk of VF.
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| 4. |
- Fahlvik, A K, et al.
(författare)
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Magnetic starch microspheres, efficacy and elimination. A new organ-specific contrast agent for magnetic resonance imaging
- 1990
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Ingår i: Investigative Radiology. - 0020-9996. ; 25:2, s. 113-120
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Tidskriftsartikel (refereegranskat)abstract
- A new particulate magnetic resonance (MR) contrast agent was prepared by controlled precipitation of iron oxide in an aqueous starch solution. The potential of the magnetic starch microspheres (MSM) as a hepatosplenic contrast enhancer was studied by MR spectroscopy and MR imaging. Intravascular administration of MSM to rodents showed an effective blood clearance and a tissue-specific localization of the substance. MSM doses in a range of 0.3-1.5 mg Fe/kg caused a 50% alteration in sensitive contrast parameters (ED50 doses) of liver and spleen. The contrast effect of MSM in liver and spleen was halved within 2 to 5 days. The approximated lethal MSM dose in mice was 150-200 mg Fe/kg. MSM is a tissue-specific MR contrast substance with high efficacy, rapid bioelimination, and low acute toxicity.
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| 7. |
- Karstoft, J, et al.
(författare)
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Topographic representation of the pharyngoesophageal segment during swallowing
- 1990
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Ingår i: Investigative Radiology. - 0020-9996. ; 25:2, s. 184-188
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Tidskriftsartikel (refereegranskat)abstract
- Motility of the pharyngoesophageal segment (PES) was monitored by cineradiography (50 frames a second) during barium swallow and analyzed by a computerized topographic mapping of sagittal wall motion. Through measurement of wall displacement on 20 consecutive levels of the PES, distention, contraction, and peristalsis were studied. Topographic mapping of three patients with normal PES motility, delayed opening of the cricopharyngeus, and incomplete opening of the cricopharyngeus, was performed. These topographic mappings show that "narrowing" at the level of the cricopharyngeus reflects expansion of the hypopharynx and cervical esophagus around the cricopharyngeus, rather than a true narrowing. In addition, analysis of wall motion demonstrated that abnormality of the circopharyngeus is often associated with abnormality of wall motion in the adjoining hypopharynx and cervical esophagus. Thus, topographic mapping of the cricopharyngeus is of value because it enables detailed analysis of wall motion during various pathologic conditions.
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| 8. |
- Leander, Peter, et al.
(författare)
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A comparison between IEEC, a new biodegradable particulate contrast medium, and iohexol in a tumor model of computed tomography imaging of the liver
- 1993
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Ingår i: Investigative Radiology. - 0020-9996. ; 28:6, s. 513-519
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Tidskriftsartikel (refereegranskat)abstract
- RATIONALE AND OBJECTIVES. Higher contrast between normal and pathologic tissues in the liver may enable detection of smaller lesions in computed tomography (CT). This can be obtained using a liver-specific contrast medium. The authors evaluate a new agent, IEEC (1'-Ethyloxycarbonyloxy)-ethyl-5-acetylamino-3-(N-methyl-acetylami no)-2,4,6- triiodo-benzenecarboxylate), in an animal model, as a potential contrast agent for CT scanning of the liver. The IEEC particulate contrast medium used is based on a prodrug ester design of metrizoic acid and accumulates rapidly in the liver. The particles are quickly degraded into well-known metabolites and excreted from the body. METHODS. Two groups of rabbits were inoculated with VX2-carcinoma directly into the liver by laparotomy. Computed tomography imaging studies were carried out 9 and 11 days after the inoculation. The investigation was designed as a crossover study. The first group was imaged both as controls (without contrast medium) and with the particulate contrast medium on the 9th day and with iohexol on the 11th day. The second group was imaged with iohexol on the 9th day and as controls, and with the particulate contrast medium on the 11th day. The contrast medium was administered in a dose of 100 mgI/kg. Iohexol was administered in a dose of 570 mgI/kg according to a standard clinical scheme in use at a radiology department for dynamic CT. Changes in normal liver/lesion contrast and the conspicuity of tumors were assessed. On completion of imaging studies on day 11, all animals were killed. The liver was removed and evaluated for the presence of tumors. RESULTS. At macroscopic inspection, all rabbits were found to have tumors ranging from 2 to 14 mm in diameter. The size and location of the tumors corresponded well with the CT images. In the images where the particulate contrast medium was used, the attenuation in the normal liver parenchyma and the contrast between normal liver and lesion was significantly higher compared with the images where iohexol was used or the controls. For all tumor sizes, the lesion detection capability with the particulate contrast medium was significantly higher compared with iohexol (P < .005) and controls (P < .05). CONCLUSIONS. VX2-carcinoma in rabbit liver is a useful model for studying the efficacy of contrast media in CT imaging. The particulate contrast medium IEEC improved visualization of liver tumors.
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| 9. |
- Leander, Peter, et al.
(författare)
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Early effect of gadopentetate and iodinated contrast media on rabbit kidneys
- 1992
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Ingår i: Investigative Radiology. - 0020-9996. ; 27:11, s. 922-926
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Tidskriftsartikel (refereegranskat)abstract
- RATIONALE AND OBJECTIVES. The authors compared the physiologic and nephrotoxic effects of the magnetic resonance imaging contrast medium gadopentetate with two conventional radiographic contrast media. METHODS. Rabbits were injected intravenously with one of the following solutions: 1) gadopentetate (0.1 M); 2) iohexol (300 mg I/mL); 3) metrizoate (300 mg I/mL); and 4) NaCl (0.9%). Blood samples were taken before and 5, 15, 45, 90, and 180 minutes after injection of the solutions and were analyzed for creatinine, aldosterone, and contrast media levels. Urine was sampled before and 1, 2.5, and 5 hours after injection of the solutions, and creatinine, leucine amino peptidase (LAP), alkaline phosphatase (ALP), gamma glutaryl transferase (GGT), and N-acetyl beta-D-glucosaminidase (NAG) activities were quantified. RESULTS. Contrast media clearance was similar for gadopentetate, iohexol, and metrizoate. Plasma aldosterone was significantly higher in the two groups injected with iodinated contrast agents compared with the gadopentetate and saline groups in the 3-hour samples. During the 5 hours after injection, the excretion of brushborder enzymes LAP, ALP, and gamma GT was significantly higher for all contrast media compared with pre-contrast values and 0.9% NaCl controls. NAG, a lysosomal enzyme from tubular cells, showed a significant increase compared with pre-contrast values for all contrast media. CONCLUSIONS. Intravenous injection of gadopentetate in rabbits showed nephrotoxicity of the same order as that of conventional iodinated contrast media.
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| 10. |
- Leander, Peter, et al.
(författare)
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MRI contrast media for the liver. Efficacy in conditions of acute biliary obstruction
- 1990
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Ingår i: Investigative Radiology. - 0020-9996. ; 25:10, s. 1130-1134
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Tidskriftsartikel (refereegranskat)abstract
- The authors investigated in a rat model the efficacy of magnetic resonance imaging (MRI) contrast media for evaluating the liver in conditions of acute biliary obstruction. Two liver-specific MRI contrast media, Cr-DEHIDA and Mn-DPDP, and the nonspecific agent Gd-DTPA were studied in normal rats and in rats whose bile ducts had been ligated before administration of the contrast medium. Images were made using a 2.4 T animal MRI system, and intensity enhancement of liver after contrast medium injection was calculated. Metal analyses of serum and liver tissue and T1 and T2 measurements on liver samples in vitro were performed. The differences in image intensity enhancement of liver between normal rats and rats with ligated bile ducts were not significant for any of the three contrast media. Imaging with Mn-DPDP resulted in the highest intensity enhancement of the liver compared with Cr-DEHIDA and Gd-DTPA. Contrast media concentrations in liver tissue were not significantly different between normal rats and rats with ligated bile ducts; however, Cr-DEHIDA concentrations in serum were higher after bile duct ligation. In vitro measurements of liver tissue indicated unique relaxation properties for Mn-DPDP. This investigation indicates that the contrast media studied may be useful in situations where suspected liver pathology is complicated by acute biliary obstruction.
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