The Histopathologic Reaction of Rabbit Lungs after Intrabronchial Application of Contrast Agents

PURPOSE: The aim of this study was to determine a safe gastrointestinal contrast agent that could be used in various clinical situations where there is a risk of aspiration using a rabbit model. MATERIALS AND METHODS: 30 healthy white rabbits were used. The rabbits were divided into 5 groups containing six animals each, one control group (anesthesia only) and 4 groups receiving various contrast agents [Solotop (Barium sulphate suspension), Gastrografin (Sodium and meglumine amidotrizoate), and Telebrix (Meglumine ioxitalamate), Visipaque (Iodixanol)]. The contrast agents were injected selectively into a main bronchus via a catheter inserted under fluoroscopy guidance. The rabbits were sacrificed either 1 day or 7 days after injecting the contrast agents, and the tissue reaction of the bronchi and lungs were examined both macro- and microscopically. The level of alveolar septal thickening, peribronchiolar lymphocytic infiltration, pulmonary congestion and edema, inflammatory exudate in the alveoli or bronchiolar lumina, microabscess formation, necrosis, pigmentation of materials injected, and fibropurulent pleurisy were evaluated and graded according to the severity as follows: no change, mild, moderate, marked in degree. RESULTS: The common microscopic findings were alveolar septal thickening and peribronchiolar lymphocytic infiltration. Pulmonary congestion and edema, inflammatory exudate in the alveoli or bronchiolar lumina were observed in 21 out of 24 rabbits receiving the contrast agents. Pigmentation of the materials injected was observed only in the group receiving Solotop. An inflammatory exudate in the alveoli and bronchiolar/bronchial lumina, microabscess formation, and necrosis were noted in most groups, but was more frequent and severe in the group receiving Gastrografin. CONCLUSION: The histopathological reactions of the rabbit lungs after the intrabronchial application of a contrast agent showed variable degrees of inflammatory reactions. Gastrografin produced most severe and extensive reaction, Solotop and Telebrix a moderate reaction, and Visipaque a minimal reaction. Therefore, a non-ionic dimeric contrast agent such as Visipaque may be the safest contrast agent in the lung when a GI tract examination is performed in clinical situations where there is a risk of aspiration.

Hepatic CT Enhancement: Comparison between Dimeric and Monomeric Nonionic Contrast Agents in Rabbits

PURPOSE: To determine the hepatic and vascular enhancement profiles with nonionic dimeric, iodixanol, contrast agent in the rabbit and to compare them with nonionic monomeric, ioversol, contrast agent. MATERIALS AND METHODS: Seven rabbits initially underwent hepatic dynamic CT scan with either iodixanol or ioversol, followed by repeated CT scan with other unused contrast agent with one week interval between scans. Pre and post contrast attenuation values of hepatic parenchyma, aorta and portal vein were measured sequentially. The mean enhancement of the hepatic parenchyma, aorta and portal vein were compared between two agents. The mean peak enhancement and peak enhancement time of the liver, aorta, and portal vein were also compared. RESULTS: The attenuation values of ioversol showed a greater mean hepatic enhancement than iodixanol from 18 seconds to 39 seconds after injection (from late arterial phase to early portal venous phase) with a statistical significance (p<0.05). The mean peak enhancement of hepatic parenchyma, aorta and portal vein was also greater using ioversol than iodixanol, but the mean peak enhancement times of ioversol and iodixanol were nearly identical. CONCLUSION: Ioversol may have the greater effects than iodixanol on hepatic tumor conspicuity, especially from late arterial phase to early portal veneous phase.

Paired Comparison of Iopamidol and Iopromide in Hepatic Arteriography

PURPOSE: To compare the clinical efficacy of iopamidol 370 and iopromide 370, as used in hepatic arteriography, in terms of their safety, patient tolerance, and image quality. MATERIALS AND METHODS: Between February and April 2001, 30 patients (M:F=27:3; mean age, 57 years) with hepatocellular carcinoma underwent hepatic angiography in which iopamidol 370 was used for transcatheter arterial chemoembolization (TAE). Sensations of heat or pain following contrast injection, a patient's distress or discomfort levels, and any side effects of the contrast media were monitored, and afterwards patients were asked whether they were aware of any differences between iopamidol 370 and iopromide 370, which had been used in hepatic angiography for previous TAE prior to February 2001. Three experienced independent radiologists assessed the diagnostic efficacy of the contrast media in terms of overall image quality, which was statistically analysed using Wilcoxon's signed ranks test. RESULTS: No patient experienced sensations of heat or pain during angiography, or showed any objective distress or discomfort, though two suffered mild nausea during angiography with iopamidol 370. None was aware of any difference between iopromide 370 and iopamidol 370. In terms of overall image quality, the diagnostic efficacy of contrast media in all patients was 'good'to 'excellent', with no significant difference between iopromide 370 and iopamidol 370 (p>0.05). CONCLUSION: In hepatic arteriography, the clinical efficacy of iopamidol 370 is comparable with that of another nonionic contrast medium, iopromide 370, in terms of safety, tolerance, and image quality. Iopamidol 370 is thus a useful alternative medium.

Clinical Efficacy of Pamiray® as a Nonionic Intravenous Contrast Material for Abdominal CT

PURPOSE: To compare the clinical efficacy of Pamiray (iopamidol) as an intravenous nonionic contrast material in abdominal CT with that of Ultravist (iopromide), an established nonionic contrast agent. MATERIALS AND METHODS: Thirty patients who had undergone abdominal CT using Ultravist during the previous two-year period underwent abdominal CT using Pamiray after written consent to its use had been obtained. During scanning using both of these media, the regions of interest facility was used to measure, in Hounsfield units, attenvation in the liver, bilateral kidneys, aorta, portal vein, and inferior vena cava, and the paired t test was used to assess the statistical significance of the findings. The severity of adverse effects, if any, experienced during contrast material injection was classified as mild or severe, and their frequency was examined. RESULTS: There was no significant difference between Pamiray and Ultravist in terms of the degree of contrast enhancement observed (p>0.05). During scanning in which Pamiray was used, three patients felt hot and two experienced mild nausea, but in none were adverse effects severe. CONCLUSION: For abdominal CT, Pamiray is comparable to Ultravist in terms of contrast enhancement. Where the use of a nonionic contrast medium is required, Pamiray could thus be a useful clinical alternative.

Efficacy of Pamiray(R) as a Nonionic Intravenous Contrast Material: Experimental Study Using Normal Rabbits

PURPOSE: To evaluate the efficacy of Pamiray(R) as an intravenous nonionic contrast material by comparing it with an established nonionic contrast material (Iopamiro(R)). MATERIALS AND METHODS: Forty adult New Zealand white rabbits weighing about 3.0 kg were used in this study. Aortography and urography (scout, 5, 15 and 30 minutes delay after injection) were performed in ten rabbits with Pamiray(R) (370 mgI/mL) and in other ten rabbits with Iopamiro(R) (370 mgI/mL). All twenty rabbits under-went abdominal triple-phase spiral CT before and 5 and 30 seconds after injection of the contrast material. The degree of contrast enhancement seen on aortograms and intravenous urograms was determined using a three-point scale by two radiologists, who reached a consensus. CT attenuation expressed in Hounsfield units (HU) was measured using the regions of interest (ROIs) facility in the liver, bilateral kidneys, aorta, portal vein, and inferior vena cava. The Mann-Whitney U test was used in image evaluation for intergroup comparisons. RESULTS: There was no significant difference between the two groups in the degree of contrast enhancement seen on aortograns. In urography, however, Iopamiro(R) was superior to Pamiray(R) in demonstrating calyces of the right kidney on 15-minute delay images and Pamiray(R) was superior to Iopamiro(R) in demonstrating the right ureter and the renal pelvis on five minute-delay images and the left ureter on 30 minutes delay (p<.05). Peak enhancement of the aorta during the first phase of bdominal CT was higher in the group in which Pamiray(R) was used. CONCLUSION: When normal rabbits were used for aortography, abdominal CT, and urography, Pamiray(R), provided more effective contrast enhancement than a previously used nonionic contrast material, namely Iopamiro(R). There were, however, slight differences in the enhancement features of renal calyces and ureters seen on 5-and 15-minute urograms.

Comparative Study between Gastro g rafin Enema and Air Enema CT: Evaluation of the Diagnostic Accuracy of Lesion Detection and Staging of Colorectal Cancer

PURPOSE: We compared the use of diluted gastrografin enema- and air enema CT for the evaluation of the diagnostic accuracy of preoperative lesion detection and the staging of colorectal carcinoma. MATERIALS AND METHODS: Forty-two patients (43 lesions) with colorectal carcinoma, diagnosed by barium enema and/or colonoscopy, underwent preoperative diluted (2.5%) gastrografin enema CT, and in another 26 patients (27 lesions) with colorectal carcinoma, air enema CT was performed. The presence or absence of lesion, its spread (T), and peritumoral lymph node (N) were analyzed. All patients underwent surgery and pathologic confirmation was obtained. RESULTS: Gastrografin enema CT and air enema CT demonstrated the primary tumor in 97.7% (42 of 43) and 96.3% of cases (26 of 27), respectively. A comparison of gastrografin enema CT and the pathologic results showed that the disease was correctly staged as T2 in five of six cases, as T3 in 28 of 31, and as T4 in two of five. Using air enema CT, the disease was correctly staged as T2 in three of three cases, as T3 in 17 of 21, and as T4 in one of two. Overall, carcinoma was correctly staged by gastrografin enema CT in 83% of cases (35 of 42) and by air enema CT in 81% (21 of 26). Nodal involvement was accurately detected in 64% of cases (27 of 42) using gastrografin enema CT and in 69% (18 of 26) using air enema CT. CONCLUSIONS: These findings suggest that the use of gastrografin enema or air enema CT does not significantly affect the diagnostic outcome.

Comparative Study between Gastro g rafin Enema and Air Enema CT: Evaluation of the Diagnostic Accuracy of Lesion Detection and Staging of Colorectal Cancer

PURPOSE: We compared the use of diluted gastrografin enema- and air enema CT for the evaluation of the diagnostic accuracy of preoperative lesion detection and the staging of colorectal carcinoma. MATERIALS AND METHODS: Forty-two patients (43 lesions) with colorectal carcinoma, diagnosed by barium enema and/or colonoscopy, underwent preoperative diluted (2.5%) gastrografin enema CT, and in another 26 patients (27 lesions) with colorectal carcinoma, air enema CT was performed. The presence or absence of lesion, its spread (T), and peritumoral lymph node (N) were analyzed. All patients underwent surgery and pathologic confirmation was obtained. RESULTS: Gastrografin enema CT and air enema CT demonstrated the primary tumor in 97.7% (42 of 43) and 96.3% of cases (26 of 27), respectively. A comparison of gastrografin enema CT and the pathologic results showed that the disease was correctly staged as T2 in five of six cases, as T3 in 28 of 31, and as T4 in two of five. Using air enema CT, the disease was correctly staged as T2 in three of three cases, as T3 in 17 of 21, and as T4 in one of two. Overall, carcinoma was correctly staged by gastrografin enema CT in 83% of cases (35 of 42) and by air enema CT in 81% (21 of 26). Nodal involvement was accurately detected in 64% of cases (27 of 42) using gastrografin enema CT and in 69% (18 of 26) using air enema CT. CONCLUSIONS: These findings suggest that the use of gastrografin enema or air enema CT does not significantly affect the diagnostic outcome.