Radiographic features of potential donor livers that precluded donation.

OBJECTIVE: The objective of our study was to catalog the anatomic features shown on preoperative CT that precluded living-donor liver donation. MATERIALS AND METHODS: We retrospectively reviewed the records of 159 consecutive candidates who were evaluated for potential right or left lobe liver donation from November 2007 to January 2012 using MDCT angiography and cholangiography. For the potential donors who were excluded secondary to findings depicted on preoperative imaging, we determined which findings precluded donation. RESULTS: In two (1%) patients who had no prohibitive preoperative imaging findings, anatomic abnormalities were detected intraoperatively that precluded transplantation. Sixty-one (38%) candidates were excluded from liver donation on the basis of imaging findings. Of these patients, 40 (66%) had inadequate liver volume, 14 (23%) had vascular or biliary variants, five (8%) had steatosis, and two (3%) were found to have renal cell carcinoma. Arterial and biliary variants were the most common reason for exclusion based on anatomic findings. CONCLUSION: Inadequate liver volume was the most common reason for exclusion based on preoperative imaging. Arterial and biliary anatomic variants precluded both right and left lobe transplantation in a number of cases.

Prospective assessment of dynamic CT and MR cholangiography in functional biliary pain.

OBJECTIVE: The objectives of our study were to assess the feasibility of dynamic CT and MR cholangiography during gallbladder stimulation, to compare CT and MR cholangiography with biliary scintigraphy, and to identify morphologic differences between patients with functional biliary pain and healthy control subjects. SUBJECTS AND METHODS: In this prospective study, 30 patients with functional biliary pain underwent biliary scintigraphy, CT cholangiography, and MR cholangiography before and during 45-minute sincalide infusions. Thirty healthy control subjects also underwent MR cholangiography with sincalide infusion. IV contrast agents (iodipamide meglumine or gadobenate dimeglumine) were administered before scanning. CT and MR images were qualitatively and quantitatively analyzed. RESULTS: Diagnostic images were obtained of all participants. There was good agreement for gallbladder ejection fraction (EF) at 40 minutes by all three methods (Lin's concordance correlation coefficient ≥ 0.6). Gallbladder contraction and refilling occurred more promptly by CT and MR cholangiography than scintigraphy. CT and MR cholangiography showed previously undiagnosed gallstones in two patients (7%). Gallbladder shape was categorized as straight, curved, or folded; a folded gallbladder was present in 37% and 23% of patients at baseline and 40 minutes, respectively, versus in 3% of control subjects at both times (p ≤ 0.004). Asymmetric patterns of gallbladder contraction occurred in 10 patients (33%) and four control subjects (13%) (p = 0.13). CONCLUSION: Dynamic CT cholangiography and MR cholangiography performed during pharmacologic stimulation accurately measure gallbladder EFs and detect missed gallstones. Gallbladder shape before and during contraction differs between patients with functional biliary pain and healthy control subjects. Dynamic CT cholangiography and MR cholangiography are promising techniques that might improve selection of patients to undergo cholecystectomy for functional biliary pain.

Preliminary experience of 256-row multidetector computed tomographic angiography for detecting cerebral aneurysms.

OBJECT: Multidetector computed tomographic angiography (MDCTA) has played an increasing role in detecting cerebral aneurysms. This study was performed to investigate the diagnostic accuracy of the upgraded 256-row MDCTA in the detection of cerebral aneurysms. METHODS: We identified 93 patients who had undergone both MDCTA and digital subtraction angiography (DSA) before surgery for the detection of cerebral aneurysms. Two and one independent blinded readers reviewed the MDCTA images and DSA images, respectively. The sensitivity, specificity, accuracy, and positive and negative predictive values were calculated for the image interpretation from the two CTA readers and one DSA reader using the combination of DSA and intraoperative findings as the reference standard. RESULTS: A total of 77 intracranial aneurysms were detected in 67 of the 93 patients. The overall sensitivity, specificity, and accuracy of the 256-row MDCTA in the detection of cerebral aneurysms were 96.10%, 92.31%, and 94.23%, respectively. For aneurysms larger than 5 mm, the overall sensitivity, specificity, and accuracy were 100%, 92.31%, and 96.83%, respectively. For aneurysms smaller than 5 mm, the overall sensitivity, specificity, and accuracy were 92.50%, 92.31%, and 92.42%, respectively. There was no significant difference for the sensitivity, specificity, and accuracy of 256-row MDCTA to detect cerebral aneurysm according to the conscious level of the patients. CONCLUSIONS: To detect cerebral aneurysms larger than 5 mm, 256-row MDCTA is an imaging method with a satisfactory diagnostic performance equal to that of DSA. However, its diagnostic performance for aneurysms smaller than 5 mm is still inferior to that of DSA.

Comparison of multidetector computed tomography angiography and cholangiography performed at 80 and 120 kVp in live liver donors.

OBJECTIVE: The objective of this study was to compare the radiation exposure and image quality of contrast-enhanced multidetector computed tomography angiography (CTA) and computed tomography cholangiography (CTC) performed for living liver donor evaluation using 80 and 120 kVp. METHODS: Ninety-three potential liver donors who underwent preoperative contrast-enhanced 64 multidetector CTA and CTC were retrospectively divided into 2 groups: at 80 and at 120 kVp. An institutional review board waiver was obtained. Signal-to-noise ratio and contrast-to-noise ratio of the hepatic artery and common bile duct were obtained. The dose-length product was recorded. Image quality and visibility of hepatic artery and biliary tract anatomy were evaluated. Mann-Whitney U test was used for statistical evaluation. RESULTS: Mean hepatic artery/common bile duct signal-to-noise ratio was 28.9/28.6 (SD, 14.2/10.0) at 80 kVp and 27.6/25.8 (SD, 8.0/6.2) at 120 kVp (P = 0.61/0.099). Mean hepatic artery/common bile duct contrast-to-noise ratio was 24.8/23.3 (SD, 12.9/8.6) at 80 kVp and 22.2/19.3 (SD, 7.7/5.0) at 120 kVp (P = 0.76/0.005). Mean CTA/CTC dose-length product was 279/281 (SD, 42/52) mGy-cm at 80 kVp and 407/451 (SD, 208/243) mGy-cm at 120 kVp (P = 0.026/0.002). Computed tomography cholangiography image quality and visibility of biliary tract anatomy were not significantly different at 80 versus 120 kVp (all P > 0.13). Computed tomography angiography image quality was significantly lower (P < 0.01), and the noise scores significantly higher (P < 0.01) at 80 versus 120 kVp, but diagnostic. CONCLUSIONS: Contrast-enhanced CTA and CTC performed at 80 kVp result in comparable image quality and anatomical evaluation with reduced radiation exposure when compared with 120 kVp.

[Constipation syndrome: methods for measuring the speed of intestinal transit]. / Síndrome estreñimiento: métodos para medir la velocidad de tránsito intestinal.

In the present article, I remind what I presented, in a symposium performed in our Society on the constipation syndrome, in relation with the definition and the determinant factors of this syndrome, and, in addition, with the methods we have created to determine physiologically the velocity of the intestinal transit, specially colonic.

Computed tomographic cholangiography in living liver transplant donors: factors determining the degree of contrast enhancement.

OBJECTIVE: To determine factors affecting liver and bile duct contrast enhancement during computed tomographic cholangiography (CTC) in living-donor transplant candidates. METHODS: Forty-four candidates underwent preoperative triphasic CT followed by intravenous infusion of 20 mL of iodipamide for CTC. Body size indices and liver volume were correlated to parenchymal and biliary enhancement. Bile duct visibility was compared to duct enhancement. RESULTS: Poorly visualized first- and second-order bile ducts demonstrated diminished enhancement (P < 0.015). Both CTC parenchymal and biliary enhancement correlated inversely with body surface area, height, and weight (P < 0.001); inverse correlation was also seen between liver volume and parenchymal enhancement (P < 0.001). A moderately positive correlation was noted between CTC biliary and parenchymal portal venous enhancement (r = 0.421; P = 0.004). CONCLUSIONS: Computed tomographic cholangiography parenchymal and biliary enhancement diminishes with increased body size and liver volume, supporting a need for adjustable contrast dosing. Portal venous parenchymal enhancement may serve as a preinfusion indicator.

CT cholangiography in potential liver donors: effect of premedication with intravenous morphine on biliary caliber and visualization.

PURPOSE: To retrospectively determine whether premedication with intravenously administered morphine improves bile duct caliber and visualization in potential liver donors undergoing computed tomographic (CT) cholangiography. MATERIALS AND METHODS: This was a retrospective single institution study approved by the institutional review board and compliant with requirements of the HIPAA. Multidetector CT cholangiography was performed after slow infusion of 20 mL of iodipamide meglumine 52% diluted in 80 mL of normal saline in 143 consecutive potential liver donors (81 men and 62 women; mean age, 37 years); 43 received premedication with intravenous morphine sulfate (0.04 mg per kilogram of body weight) and 100 did not. Two independent readers recorded common bile duct diameter and area on axial CT images. Readers also scored bile duct visualization, including all second-order biliary branches, on a four-point scale (0, not seen; 3, excellent visualization). RESULTS: For scans obtained without and those obtained with morphine, there was no significant difference in the mean common bile duct diameter (4.1 vs 4.3 mm for reader 1 and 4.4 vs 4.6 mm for reader 2, respectively; P > .39 for both readers), in common bile duct area (20.7 vs 21.5 mm(2), for reader 1 and 21.3 vs 20.2 mm(2) for reader 2, respectively, P > .60 for both), or in second-order bile duct visualization score (2.34 vs 2.36 for reader 1 and 2.58 vs 2.50 for reader 2, respectively; P > .5 for both). CONCLUSION: The results suggest that premedication with intravenous morphine prior to CT cholangiography in potential liver donors does not increase bile duct caliber or improve biliary visualization.

The choleretic effect of iodipamide.

It is well established that a number of organic anions are excreted by the liver into bile in association with a marked increase in bile flow. Previous studies have shown that iodipamide (3,3'-(adipoyl-diimino)bis[2,4,6-triiodobenzoic acid]), the radiographic contrast material used for intravenous cholangiography, is a potent choleretic. Experiments were performed in unanesthetized dogs to determine if the increased bile flow produced by iodipamide is canalicular or ductular in origin, to quantitate the choleresis associated with iodipamide and taurocholate excretion, and to correlate these findings with the results of in vitro studies in which the osmotic activities of iodipamide and taurocholate in both isotonic saline and bile were determined. The plasma erythritol clearance increase linearly with the excretion of iodipamide, indicating that iodipamide stimulates canalicular bile flow. The choleretic potency of iodipamide (22 ml/mmol) is approximately 3 times that of taurocholate (7.8 ml/mmol), yet the osmotic activity of iodipamide in bile (1.5 mosmol/mmol) is only twice as great as that of taurocholate in bile (0.8 mosmol/mmol). It therefore appears that, per unit of effective osmotic solute secreted, iodipamide carries more water into the bile canaliculi than does taurocholate.

Two hepatic cytoplasmic protein fractions, Y and Z, and their possible role in the hepatic uptake of bilirubin, sulfobromophthalein, and other anions.

Two hepatic cytoplasmic protein fractions, designated Y and Z, which bind sulfobromophthalein (BSP), bilirubin, and other organic anions, have been separated by G75 Sephadex gel filtration. The physiologic role of these protein fractions has been investigated. They are present in the 110,000 g supernatant fraction from the livers of all the species tested (rats, mice, guinea pigs, Rhesus monkeys, sheep, and man). Tissues which do not preferentially extract BSP or bilirubin from plasma do not contain these fractions, with the exception of small intestinal mucosa which contains Z. Anion binding by Y and Z fractions is not due to contamination with albumin. These fractions are responsible for the cytoplasmic localization of bilirubin in Gunn rats, and the fractions bind bilirubin, BSP, or indocyanine green (ICG), whether given in vivo or added in vitro to liver supernate from normal rats. Flavaspidic acid-N-methylglucaminate, bunamiodyl, and iodipamide, drugs known to interfere with the hepatic uptake mechanism, compete with bilirubin and BSP for binding to Z. These proteins appear to be important in the transfer of organic anions from plasma into the liver and provide a tool for the investigation of hepatic uptake mechanisms.

New substrates of the multispecific bile acid transporter in liver cells: interference of some linear renin inhibiting peptides with transport protein(s) for bile acids.

Interactions between some stable linear peptides with renin inhibitory activity and a multispecific transport system in the basolateral plasma membrane of liver cells was studied on cell suspensions. The peptides used in our experiments were taken up by liver cells and subsequently eliminated without any biotransformation (e.g., proteolysis). No degradation products could be detected in the extracellular medium by thin-layer chromatography. All peptides tested inhibited the uptake of physiological and of some foreign substrates of the multispecific bile acid transporter (MT). The phalloidin response of liver cells was also inhibited to a similar degree in a concentration-dependent manner. The potency of inhibition did not correlate with the lipophilic properties of the peptides. On the other hand a tight correlation could be documented between the inhibition of cholate transport and that of the phalloidin response. Transport inhibition of typical substrates of the MT by the above renin inhibitors was competitive. In contrast, the transport of a typical substrate of the bilirubin carrier (rifampicin), of amino acids (alpha-aminoisobutyric acid), long chain fatty acids (oleic acid) and cationic compounds (thiamin hydrochloride) was not inhibited by the same renin inhibitors. These results indicate that linear renin inhibiting peptides are taken up into liver cells by carrier proteins related to the MT.

Characterization of site I on human serum albumin: concept about the structure of a drug binding site.

Human serum albumin (HSA) possesses at least three sites or areas for high-affinity binding of drugs. Of these sites, site I was investigated by series of ultrafiltration and equilibrium dialysis experiments. Three ligands, acenocoumarol, dansyl-L-asparagine (DNSA) and n-butyl p-aminobenzoate (n-butyl p-ABE) were employed as marker ligands. Each ligand binds to a single high-affinity site on HSA, and binding studies with different pairs of the ligands revealed independent high-affinity binding. Preliminary displacement studies performed with the typical site I binding drugs warfarin, phenylbutazone and iodipamide showed different displacement patterns of the three marker ligands. These studies were followed by stringent competition experiments involving all possible combinations of the three test ligands themselves and of these and the three marker ligands. On the basis of the results obtained it seems that the acenocoumarol and DNSA binding regions correspond to the warfarin and azapropazone binding regions, respectively, of site I reported by others (Fehske, Schläfer, Wollert and Müller (1982) Mol. Pharmacol. 21, 387-393). The new binding region, represented by n-butyl p-ABE, is probably located adjacent to the acenocoumarol binding region but apart from that of DNSA. We have elaborated a model for binding site I in which we propose novel nomenclatures, region Ia, Ib, and Ic for the acenocoumarol, DNSA and n-butyl p-ABE binding regions, respectively. Furthermore, the relation between these regions and the high-affinity binding sites for other drugs have been discussed.

Iodipamide uptake by rat liver plasma membrane vesicles enriched in the sinusoidal fraction: evidence for a carrier-mediated transport dependent on membrane potential.

Iodipamide, a cholecystographic agent, is known to be taken up by isolated hepatocytes by a mechanism similar or identical with the inward transport of bile salts (Petzinger, E., Joppen, C. and Frimmer, M. (1983) Naunyn-Schmiedeberg's Arch. Pharmacol. 322, 174-179). To elucidate its mode of transport, uptake of iodipamide was studied by rapid-filtration techniques on plasma membrane vesicles enriched in the sinusoidal fraction. Uptake was found to be dependent upon the temperature, the intravesicular volume, a gradient of monovalent cations (Na+, K+ or Li+) and the substrate concentration (saturation kinetics with respect to iodipamide: apparent Km = 70 microM, Vmax = 0.31 nmol per mg protein per min at 100 mM NaCl and 25 degrees C). Countertransport and transstimulation in tracer exchange experiments indicate that in vesicles, iodipamide uptake rather than binding occurs. Na+ could be replaced by K+ or Li+ in our system without any effect. However, in the presence of choline chloride a slight, but distinct reduction occurred. Iodipamide uptake was inhibited by cholate, phalloidin, 4,4'-diisothiocyanato-1,2-diphenylethane-2,2'-disulfonic acid and by bromosulfophthalein with inhibition being competitive in the case of cholate and non-competitive in the case of bromosulfophthalein. Alteration of the membrane potential by addition of NO3-, SCN- or SO4(2-) modified the uptake rate for iodipamide. The above results support our earlier hypothesis that the hepatocellular uptake of iodipamide is due to a carrier-mediated transport, probably similar to that of bile acids. However, translocation of iodipamide is assumed to be driven by the membrane potential only and not by Na+ contransport.

Volume rendering of three-dimensional drip infusion CT cholangiography in patients with suspected obstructive biliary disease: a retrospective study.

The purpose of this study was to evaluate the diagnostic potential of prolonged drip infusion CT cholangiography (DIC-CT) using meglumine iotroxate (Biliscopin) and 3D volume rendering in patients with suspected obstructive biliary disease. From a material of 142 patients who had undergone a drip infusion CT, all cases with a verified surgical or endoscopic retrograde cholangiography (ERC) diagnosis (n=33) were selected. Age-matched controls were selected from the remaining examinations. Three radiologists reviewed all 66 examinations in retrospect, independently as well as in consensus. The image quality and the estimated diagnostic quality were rated as good or moderate in 91% of the 198 reviews. The consensus sensitivity and specificity for diagnosing biliary stones was 88% and 94%, respectively (with sensitivities ranging from 88% to 94% for individual observers, and specificities from 86% to 96%). Two out of three strictures were observed. No false positive strictures were described. The use of volume rendering technique (VRT) improved diagnostic certainty in 28/198 (14%) of the evaluations. The visualization of ductal stones was improved in 18/48 (38%). No differences in diagnostic quality between single and multislice CT were observed. We conclude that a detailed image of the biliary tree with good sensitivity and specificity can be obtained by means of bilirubin-governed infusion time DIC-CT with volume rendering reconstruction.

Hyperthermic responses to central injections of some peptide and non-peptide opioids in the guinea-pig.

Intracerebroventricular administration of prototype non-peptide opioid receptor (mu, kappa, sigma) agonists, morphine, ketocyclazocine and N-allyl normetazocine (SKF 10,047) and an agonist at both kappa and sigma receptors, pentazocine, induced hyperthermia in guinea-pigs. Similar administration of peptide opioids like beta-endorphin (BE), methionine enkephalin (Met-E), leucine enkephalin (Leu-E) and their synthetic analogues D-ala2-methionine-enkephalinamide (D-ala2-Met-E) and D-ala2-leucine-enkephalinamide (D-ala2-Leu-E) also caused hyperthermia. Of the three anion transport systems (iodide, hippurate and liver-like) present in the choroid plexus, only the liver-like transport system seems to be important to central inactivation of beta-endorphin, D-ala2-Met-enkephalin and D-ala2-Leu-enkephalin since iodipamide (an inhibitor of the liver-like transport system) augmented the hyperthermia. Prostaglandins (PG) and norepinephrine (NE) were not involved in peptide- and non-peptide opioid-induced hyperthermia because a prostaglandin synthesis inhibitor, indomethacin, and an alpha-adrenergic receptor blocker, phenoxybenzamine, had no thermolytic effect. Likewise cAMP was not required since a phosphodiesterase inhibitor, theophylline, did not accentuate the hyperthermia due to administration of peptide and non-peptide opioids. Naloxone-sensitive receptors were involved in the induction of hyperthermia by morphine and beta-endorphin since naloxone attenuated the effect. In contrast, the hyperthermic responses to ketocyclazocine, SKF 10,047, pentazocine, Met-enkephalin, Leu-enkephalin, D-ala2-Met-enkephalin and D-ala2-Leu-enkephalin were not antagonized by naloxone. Lack of antagonism of naloxone on pyrogen, arachidonic acid, PGE2, dibutyryl cAMP and NE-induced hyperthermia indicates that endogenous opioid peptides are not likely to be central mediators of the hyperthermia induced by these agents.

Prostacyclin-induced hyperthermia: implication of a protein mediator.

Intracerebroventricular administration of prostacyclin (PGI2) at room temperature (21 degrees C) induced dose-related hyperthermia in rabbits and also produced hyperthermia at low (4 degrees C) and high (30 degrees C) ambient temperatures. The PGI2-induced hyperthermia was not mediated by its stable metabolite 6-keto prostaglandin F1 alpha. Of the three anion transport systems (iodide, hippurate and liver-like) present in the choroid plexus, only the liver transport system seems to be important to central inactivation of pyrogen, prostaglandin E2 (PGE2) and the PGI2. Iodipamide (an inhibitor of the liver transport system) augmented the hyperthermia produced by PGI2, PGE2 and pyrogen. Phenoxybenzamine and pimozide had no thermolytic effect on PGI2-induced hyperthermia. After norepinephrine (NE) and dopamine levels were depleted by 6-hydroxydopamine, PGI2 still induced hyperthermia. Indomethacin and SC-19220 (a PG antagonist) did not antagonize PGI2-induced hyperthermia. Furthermore, the hyperthermia due to PGI2 was not accentuated by theophylline. In contrast, the hyperthermic response to PGI2 was attenuated by central administration of the protein synthesis inhibitor, anisomycin. These results indicate that PGI2-induced hyperthermia is not mediated by NE, dopamine, PGS, cyclic AMP, but, rather, that a protein mediator is implicated in the induction of fever by PGI2.

Uptake of thallium-201 in enlarged thyroid glands: concise communication.

We have investigated the thyroid uptake of Tl-201 in 37 patients with various types of goiter, and in six with normal thyroids. Significant thallium uptake was found in all cases in which there was thyroid enlargement, including Graves' disease, toxic thyroid nodule, primary hypothyroidism, simple goiter, Hashimoto's disease, thyroid carcinoma, and thyroid adenoma. If goiter was absent, however, there was no demonstrable uptake--e.g., in secondary hypothyroidism, subacute thyroiditis, and the normal controls. Thallium uptake did not correlate with thyroid function tests such as BMR, T3-RU, T3, T4, TSH, antithyroid antibodies, or the 24-hr I-131 uptake. In 23 patients with diffuse goiter, on the other hand, maximum Tl-201 uptake correlated well with thyroid weight: r = 0.836 (p less than 0.001); y = 0.02 x + 0.06.

Cholic acid accumulation by the ciliary body and by the iris of the primate eye.

Cholic acid accumulates in both the ciliary body and the iris of the primate eye during in vitro incubations at 37 degrees C for 1 hr. Incubation at 0 degrees C depresses uptake in both tissues. The washout of preaccumulated cholic acid occurs some 3.4 times faster from the iris than from the ciliary body. The mechanism of cholic acid accumulation in both tissues is less sensitive to inhibition by high iodipamide concentrations and also is less sensitive to inhibition by high hippurate concentrations than the mechanism of p-aminohippurate (PAH) accumulation. Therefore, although overlap may exist, the cholic acid--uptake mechanism differs from the PAH-uptake mechanism in both the primate ciliary body and the primate iris.

Accumulation and elimination of particulate iodipamide ethyl ester in the lungs and kidneys of the rat. A morphological study.

Particulate iodipamide ethyl ester, a new hepatolienographic x-ray contrast agent, was intravenously injected into rats. Lung and kidney biopsies taken at various intervals after the injection were examined by light and electron microscopy. IDE particles could be found in the lung capillaries phagocytized by polymorphonuclear neutrophils (PMNs). There were also free particles in the alveolar capillaries in the samples taken 5 min to 4 hours after the injection. No aggregates or emboli were seen. Two days or more after the injection no intra- and extracellular particles were present. The PMNs underwent transient local hydropic degeneration; the lung cells were morphologically intact. In the kidneys, the particles first appeared in both cortical and medullary capillaries. No emboli were observed. The kidney cells did not ingest IDE, but polymorphonuclear neutrophils (PMNs) with ingested IDE were often seen loosely attached to the glomerular capillary walls. In addition, free particles were evident in the capillaries in the samples taken up to 1 hour after injection. All particles in subsequent kidney samples were located in PMNs in the glomeruli. After three or more days the renal tissue was totally devoid of particulate IDE. No morphological evidence of kidney cell injury was observed.

Cholangiographic excretion studies: a comparison of iodipamide and iodoxamate in the dog.

Iodoxamic acid is a new hexaiodinated cholegraphic contrast agent. The methylglucamine salts of iodoxamate and iodipamide were administered to labrador dogs as an intravenous infusion. Bile salts were also infused. The biliary concentration and output of the two agents were compared. Bile flow rate, bile salt concentration and bile salt output with the two agents were also compared. The biliary output of iodoxamate (0.70-0.78 mumol/min/kg) was more than 50% higher than the iodipamide output (0.46 mumol/min/kg). Bile salt output and concentration with iodoxamate infusion were lower than with iodipamide infusion. The bile flow rate was higher with the new agent. The complementary effects of increased contrast output and decreased bile salt output with the new agent led to a significantly higher biliary iodine concentration compared with iodipamide. The results of this study support the suggestion that iodoxamate represents a significant advance in the cholegraphic contrast media field.

Uptake and dissolution of particulate iodipamide ethyl ester in the spleen. A morphologic study.

Iodipamide ethyl ester (IDE) is an experimental particulate contrast agent being developed for CT image enhancement of the liver and spleen. IDE particles are phagocytized by the reticuloendothelial cells after an intravenous injection. The uptake and dissolution of IDE particles were studied in the spleen with light and electron microscopy. Two minutes after injection, intra- and extracellular IDE particles were found in the red pulp of the spleen. Highest concentration of IDE was seen in the marginal zone surrounding the white pulp. Particles also were seen elsewhere in the red pulp but only occasionally between the outermost cells of the white pulp. The extracellular particles disappeared within 4 hours postinjection. At one day postinjection, the amount of intracellular IDE particles had begun to decrease. Electron micrographs showed that the intracellular particles dissolved gradually in the phagocytes and caused transient degenerative morphologic changes. At three days postinjection, practically all IDE particles had disappeared from the spleen. Polystyrene latex particles were used as controls. They were phagocytized like the IDE particles, but they did not disappear from the phagocytes. IDE particles caused no morphologic injuries in nonphagocytic cells of the spleen.