Accidental Intrathecal Injection of Ionic Contrast: Case Report and Review of the Literature.

BACKGROUND: Ionic contrast, if accidentally injected into the intrathecal space during routine imaging studies or interventional procedures, may significantly interfere with neuronal activity, potentially causing ascending tonic-clonic seizure syndrome and even death. As a result, ionic contrast is strictly contraindicated for intrathecal use. Rapid recognition of the condition followed by prompt management, typically involving aggressive cerebrospinal fluid (CSF) drainage, is critical to improving patient outcome. Lumbar drain has previously been well described as a management strategy. CASE DESCRIPTION: We present a case of accidental intrathecal injection of an ionic contrast agent, iothalamate meglumine, in a patient undergoing cervical epidural steroid injection. This patient was managed successfully with drainage of CSF using an external ventricular drain alone. CONCLUSION: Our literature review and analysis of the previously published cases demonstrate that aggressive CSF drainage is essential to improve outcomes, and in some cases an external ventricular drain alone may be effectively used.

Acceptability of oral iodinated contrast media: a head-to-head comparison of four media.

OBJECTIVE: To assess the palatability of iodinated oral contrast media commonly used in abdominopelvic CT and CT colonography (CTC). METHODS: 80 volunteers assessed the palatability of a 20-ml sample of a standard 30 mg ml(-1) dilution of Omnipaque® (iohexol; GE Healthcare, Cork, Ireland), Telebrix® (meglumine ioxithalamate; Guerbet, Aulnay-sous-Bois, France), Gastromiro® (iopamidol; Bracco, High Wycombe, UK) and Gastrografin® (sodium diatrizoate and meglumine diatrizoate; Bayer, Newbury, UK) in a computer-generated random order. RESULTS: Gastrografin is rated significantly less palatable than the remaining media (p<0.005). Omnipaque and Telebrix are significantly more palatable than Gastromiro. No difference existed between Omnipaque and Telebrix. 39% of participants would refuse to consume the quantities of Gastrografin required for a CTC examination compared with Telebrix (7%) and Omnipaque (9%) (p<0.05). CONCLUSION: Omnipaque and Telebrix are significantly more palatable than both Gastromiro and Gastrografin, with participants more willing to ingest them in larger quantities as well as being less expensive. ADVANCES IN KNOWLEDGE: Omnipaque and Telebrix are significantly more palatable iodinated oral contrast media than both Gastromiro and Gastrografin, which has potential implications in compliance with both abdominopelvic CT and CTC.

Contrast media-doped hydrodissection during thermal ablation: optimizing contrast media concentration for improved visibility on CT images.

OBJECTIVE: The purpose of this study is to determine a concentration of iodinated contrast media in saline and 5% dextrose in water (D5W) for organ hydrodissection, a technique used to physically separate and protect tissues adjacent to thermal ablations. MATERIALS AND METHODS: A total of 28 samples were prepared from 1:1000-1:1 iohexol or iothalamate meglumine contrast media in either normal saline or D5W. Samples alone or juxtaposed with a homogeneous liver-mimicking phantom were imaged by CT using 80-120 kVp and 10-300 mAs. Mean CT numbers and noise were measured from the fluid, background air, phantom adjacent to the fluid, and phantom distant from the fluid. Visibility was determined from the contrast-to-noise ratio between the fluid and phantom, whereas streaking artifact was quantified by relative noise in the phantom. Measures were individually fit using multiple linear regression to determine an optimal contrast-to-fluid ratio for increased visualization without streaking. Contrast media- and blood-doped saline and D5W were also tested to determine whether such doping altered their electrical conductivity. RESULTS: Iohexol concentration most influenced CT number; volumetric ratios of 1:1000-1:1 produced 20 HU to over 3000 HU. CT numbers were weakly dependent on x-ray tube voltage, whereas contrast-to-noise ratio and streaking artifacts were somewhat dependent on tube output. An optimal ratio of iohexol in fluid was determined to be 1:50. There was no significant difference between the electrical impedances of doped and pure saline or D5W (p > 0.5, all cases). CONCLUSION: A 1:50 ratio of iohexol in saline or D5W provides an optimal combination of increased visibility on CT without streaking artifacts.

Reducing the oral contrast dose in CT colonography: evaluation of faecal tagging quality and patient acceptance.

AIM: To evaluate the minimal iodine contrast medium load necessary for an optimal computed tomography colonography tagging quality. MATERIALS AND METHODS: Faecal occult blood test positive patients were randomly selected for one of three iodine bowel preparations: (1) 3 × 50 ml meglumine ioxithalamate (45 g iodine), (2) 4 × 25 ml meglumine ioxithalamate (30 g iodine); or (3) 3 × 25 ml (22.5 g iodine) meglumine ioxithalamate. Two experienced readers assessed the tagging quality per colonic segment on a five-point scale and the presence of adherent stool. Also semi-automatic homogeneity measurements were performed. Patient acceptance was assessed with questionnaires. RESULTS: Of 70 eligible patients, 45 patients participated (25 males, mean age 62 years). Each preparation group contained 15 patients. The quality of tagging was insufficient (score 1-2) in 0% of segments in group 1; 4% in group 2 (p<0.01 versus group 1); and 5% in group 3 (p=0.06 versus group 1). In group 1 in 11% of the segments adherent stool was present compared with 49% in group 2 and 41% in group 3 (p<0.01, group 2 and 3 versus group 1). Homogeneity was 85, 102 (p<0.01), and 91 SD HU (p=0.26) in groups 1, 2, and 3, respectively. In group 1 two patients experienced no burden after contrast agent ingestion compared to one patient in group 2 and nine patients in group 3 (p=0.017). CONCLUSION: A dose of 3 × 50 ml meglumine ioxithalamate is advisable for an optimal tagging quality despite beneficial effects on the patient acceptance in patients receiving a lower dose.

Focal confluent fibrosis in cirrhotic liver: natural history studied with serial CT.

OBJECTIVE: The objective of this study was to assess the long-term natural history of focal confluent fibrosis in cirrhotic liver with CT. MATERIALS AND METHODS: Two radiologists retrospectively reviewed in consensus 118 liver CT examinations in 26 patients (19 men, seven women; age range, 32-68 years; mean age, 50 years) performed over approximately 6 years. Helical CT scans were obtained before and 30-35 and 65-70 seconds after injection of 125-150 mL of contrast medium at a rate of 4-5 mL/s. Proof of cirrhosis was based on liver transplantation (n = 6), biopsy (n = 9), or imaging findings (n = 11). The number, location, and attenuation of fibrotic lesions and presence of trapped vessels were evaluated. Variation of hepatic retraction associated with the development of focal confluent fibrosis lesions was assessed using the ellipsoid volume formula and an arbitrary retraction index. RESULTS: Each radiologist identified 41 focal confluent fibrosis lesions. All lesions were identified by both radiologists. Twelve patients (46%) had a single lesion, 13 (50%) had two lesions, and one (4%) had three lesions. Thirty-four (83%) of 41 lesions were located in segment IV, VII, or VIII. Thirty-two lesions (78%) were hypoattenuating on unenhanced images, 25 lesions (61%) were hypoattenuating on hepatic arterial phase images, and 20 lesions (49%) were isoattenuating on portal venous phase images. Seven lesions (17%) were or became hyperattenuating at follow-up on portal venous phase images. Trapped vessels were found in six lesions (15%). The retraction index showed a significant increase over time (r = 0.423, p < or = 0.0001). CONCLUSION: The degree of capsule retraction associated with focal confluent fibrosis evolves with time and relates to the natural evolution of cirrhosis.

Assessment of iothalamate plasma clearance: duration of study affects quality of GFR.

BACKGROUND AND OBJECTIVES: Measurement of GFR is important for the management of chronic kidney disease (CKD). Although bolus administration of radiocontrast agents is commonly used to measure GFR, the optimal duration of sampling to assess their plasma clearance is unknown. The purpose of this study was to evaluate whether the duration of plasma sampling influences precision and estimation of GFR. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: GFR was measured by sampling plasma 12 times over 5 h in 56 patients with CKD (mean age 64 yr, 98% men, 79% Caucasian, 34% diabetics, estimated GFR 31.8 +/- 14.2 ml/min/1.73 m(2)). In a subset of 12 patients we measured GFR by sampling plasma 17 times over 10 h. RESULTS: Short sampling intervals considerably overestimated GFR measured using total plasma iothalamate clearance, especially in larger patients. In the higher estimated GFR group (>30 ml/min/1.73 m(2)), the 5-h GFR was 17% higher and 2-h GFR 54% higher compared with the 10-h GFR, which averaged 40.3 ml/min/1.73 m(2). In the lower estimated GFR group (<30 ml/min/1.73 m(2)), the 5-h GFR was 36% higher and 2-h GFR 126% higher compared with the 10-h GFR, which averaged 22.2 ml/min/1.73 m(2). Short sampling duration also reduced the precision of the estimated GFR from 1.67% for 10-h GFR, to 3.48% for 5-h GFR, and to 7.07% for 2-h GFR. CONCLUSIONS: GFR measured over a longer duration with multiple plasma samples spanning the distribution and elimination phases may improve precision and provide a better measure of renal function.

Severe reaction to intravenous administration of an ionic iodinated contrast agent in two anesthetized dogs.

CASE DESCRIPTION: Acute severe systemic reactions developed during i.v. administration of an ionic iodinated contrast agent (iothalamate meglumine) in 2 dogs undergoing contrast-enhanced computed tomography. CLINICAL FINDINGS: Both dogs developed marked changes in heart rate and systolic arterial blood pressure during or immediately after i.v. administration of the contrast agent. The first dog became profoundly hypertensive and bradycardic with poor oxygenation, apparent bronchospasm, and prolonged diarrhea. The second dog became hypotensive and tachycardic with erythema on the ventral aspect of the abdomen and pelvic limbs, periocular edema, and diarrhea. TREATMENT AND OUTCOME: Both dogs were treated for shock by means of i.v. fluid administration, and anesthesia was discontinued. The first dog was placed on a ventilator to improve oxygenation but was hypertensive and unresponsive for 6.5 hours following contrast agent administration. Bloody diarrhea persisted once consciousness was regained. The dog was discharged 3 days after contrast agent administration, and diarrhea resolved 15 days later. The second dog responded to phenylephrine administration, but urine output appeared low immediately following recovery from anesthesia. Urine output was normal the following day, and the dog was released 36 hours after contrast administration with no residual adverse effects. CLINICAL RELEVANCE: Findings highlighted the potential risk for severe reactions associated with i.v. administration of ionic iodinated contrast agents in dogs. Both hypertensive and hypotensive responses were seen. Supportive care for systemic manifestations was effective in these 2 dogs, and extended hospitalization was not necessary.

Comparison of neutral oral contrast versus positive oral contrast medium in abdominal multidetector CT.

To determine whether neutral contrast agents with water-equivalent intraluminal attenuation can improve delineation of the bowel wall and increase overall image quality for a non-selected patient population, a neutral oral contrast agent (3% mannitol) was administered to 100 patients referred for abdominal multidetector row computed tomography (MDCT). Their results were compared with those of 100 patients given a positive oral contrast agent. Qualitative and quantitative measurements were done on different levels of the gastrointestinal tract by three experienced readers. Patients given the neutral oral contrast agent showed significant better qualitative results for bowel distension (P < 0.001), homogeneity of the luminal content (P < 0.001), delineation of the bowel-wall to the lumen (P < 0.001) and to the mesentery (P < 0.001) and artifacts (P < 0.001), leading to a significant better overall image quality (P < 0.001) than patients receiving positive oral contrast medium. The quantitative measurements revealed significant better distension (P < 0.001) and wall to lumen delineation (P < 0.001) for the patients receiving neutral oral contrast medium. The present results show that the neutral oral contrast agent (mannitol) produced better distension, better homogeneity and better delineation of the bowel wall leading to a higher overall image quality than the positive oral contrast medium in a non-selected patient population.

Sweet's syndrome-like neutrophilic dermatosis resulting from exposure to a radiocontrast agent.

Radiocontrast agents are known to be the cause of many cutaneous manifestations. The present report describes a unique case of a Sweet's syndrome-like neutrophilic dermatosis that recurred three times over 5 years following administration of a radiocontrast agent administered during the course of an intravenous pyelography.

Evaluation of the effects of noniodinized and iodinized ionic contrast media and gadoteric acid in acute necrotizing pancreatitis: experimental study in rabbits.

OBJECTIVE: To evaluate the effects of iodine contrast media and gadoteric acid in acute necrotizing pancreatitis. METHODS: Fifty rabbits were distributed in 5 groups: 10 rabbits were assigned in the control group (group 5) and 40 rabbits were assigned in the pancreatitis group, wherein acute necrotizing pancreatitis was induced through retrograde injection of 5% sodium taurocholate (1 mL/kg weight) in the main pancreatic duct. After 3 hours, they were randomized to receive endovenous iodinized nonionic contrast medium (group 1), iodinized ionic contrast medium (group 2), gadoteric acid (group 3), and physiological serum at 0.9% (group 4). Six hours after induction of pancreatitis, these animals were reoperated. During surgery, pancreatic tissue flow through laser Doppler, hematometric values, biochemistry, and histopathology analysis by hematoxylin and eosin were done. Statistical analysis using Kruskal-Wallis, Fisher-Freeman-Halton, and parametric t tests was performed. RESULTS: There was statistical significance when comparing tissue flow before and after induction of pancreatitis (P < 0.0001). Ionic and nonionic contrast media and gadoteric acid did not increase the grade of pancreatic necrosis (P > 0.05). CONCLUSIONS: Ionic and nonionic contrast media and gadoteric acid did not produce adverse effects in the present model of acute necrotizing pancreatitis.

Injection rate threshold of triple-lumen central venous catheters: an in vitro study.

RATIONALE AND OBJECTIVES: Computed tomographic angiography (CTA) requires the rapid injection of contrast media ideally through an 18-gauge intravenous line in the antecubital fossa. Patients with CVCs undergoing CTA, however, are typically injected at low rates for two reasons: the potential for catheter failure and because of the lack of manufacturer recommendations for high injection rates typically used during CTA. The purpose of the study is to measure the injection rate thresholds of CVC. The results suggest that CVC can be used at high injection rates that are now typically used with peripheral intravenous catheters during CTA. MATERIALS AND METHODS: We used 16-cm-long catheters and 20-cm-long catheters in six groups (n = 5 for each catheter length). After the catheters were placed into a water bath, each group was injected at 5, 10, 15, 20, 25, and 30 ml/sec. New contrast, pressure tubing, and catheters were used for each test. RESULTS: No catheter ruptures were encountered during the experiment, but there was one episode of power injector tubing rupture during the injection of a 16-cm catheter at an injection rate of 30 ml/sec. CONCLUSION: No catheter failures were demonstrated in this study using injection rates well above those used in conventional CTA. Power injector tubing failure was demonstrated at an injection rate of 30 ml/sec, which generated mean pressures in the 16-cm catheters of 920 psi (tubing rating per manufacturer is 300 psi). This study demonstrated no catheter or injector tubing failure at injection rates of 5 to 25 ml/sec.

A novel approach to flexor hallucis longus tenography.

OBJECTIVE: This article presents a technically simple and more accurate approach to flexor hallucis longus (FHL) tenography than any we found reported in the literature. CONCLUSION: Tenography is used to evaluate and treat tenosynovitis. Standard FHL tenography protocol involves either direct percutaneous access of the FHL synovial sheath posterior to the medial malleolus or indirect filling of the FHL sheath from an injection of the flexor digitorum longus (FDL) tendon sheath, which often communicates with the FHL tendon sheath. However, with these methods, difficulty entering the FHL sheath may be encountered. We adapted our technique to access the FHL sheath as it courses below the sustentaculum talus. Our early experience with five cases using this technique reflects a 100% success rate with accurate needle placement within the FHL tendon sheath, thereby improving procedural efficiency.

Prospective comparison of helical CT of the abdomen and pelvis without and with oral contrast in assessing acute abdominal pain in adult Emergency Department patients.

PURPOSE: This prospective study compares the agreement of nonenhanced helical computed tomography (NECT) with oral contrast-enhanced computed tomography (CECT) in Emergency Department (ED) patients presenting with acute abdominal pain. MATERIALS AND METHODS: One hundred eighteen patients presenting to the ED with acute abdominal pain undergoing CT were enrolled over a 13-month period using convenience sampling. Exclusion criteria included acute trauma, pregnancy, unstable patients, and patients suspected of having urinary calculi. Patients were scanned helically using 5-mm collimation before and approximately 90 min after oral contrast administration. Both exams were prospectively interpreted by different attending radiologists in a blinded fashion using an explicit data sheet specifying the presence or absence of 28 parameters relating to various common diagnoses. RESULTS: The 118 patients had a mean age of 49 years, a male: female ratio of 7:13, and a median height, weight, and BMI of 166 cm, 80 kg, and 29, respectively. The most common indications for the study included appendicitis (32%) and diverticular disease (12%). Pain maximally localized to the right lower quadrant in 37% and the left lower quadrant in 21%. There were 21 patients that had significant disagreement of interpretations between NECT and CECT resulting in a simple agreement of 79% (95% CI: 70-87%). For specific radiologic parameters, agreement ranged from 77 to 100%. A post hoc agreement analysis was subsequently performed by two radiologists and only five paired scans were identified as discordant between the NECT and CECT. For only one of these patients did both radiologists agree that there was a definite discordant result between the two studies. A final unblinded consensus review demonstrated that much of the disagreement between the interpretations was related to interobserver variation. CONCLUSION: There is 79% simple agreement between NECT and CECT in diagnosing various causes of acute abdominal pain in adult ED patients. Post hoc analysis indicates that a significant portion of the discordance was attributable to interobserver variability. This data suggests that NECT should be considered in adult ED patients presenting with acute abdominal pain.

Virtual cystoscopy by intravesical instillation of dilute contrast medium: preliminary experience.

PURPOSE: We determined whether virtual cystoscopy based on helical data sets can yield urinary capabilities similar to those achieved by fiber-optic cystoscopy. MATERIALS AND METHODS: A total of 11 patients with ultrasound detected bladder tumors underwent pelvic CT as a single volumetric scan after preliminary bladder distention with saline mixed with contrast medium using a 6Fr infant feeding tube. Cystoscopy was simulated based on a 3-dimensional helical CT data set in real time. Source raw CT data for virtual cystoscopy were reconstructed and navigation was done in real time using surface rendering navigation software. These images and findings were then compared with conventional cystoscopy findings. RESULTS: An attenuation gradient of 350 HU between the vesical mucosa and urine was noted. Two of the 14 tumors (11 patients) were missed and each was 0.7 cm. All tumors greater than 0.9 cm were detected. Overall sensitivity was 85.7%. There were no false-positive findings. There was good correlation with tumor location and size. The ureteral orifices and their relationship to the tumor were also well appreciated. Subtle mucosal changes on conventional cystoscopy were not delineated by virtual cystoscopy. CONCLUSIONS: Our method of instilling dilute contrast medium in the bladder offers an excellent attenuation gradient. The overall sensitivity of tumor detection is better than that reported for intravenous contrast medium and pneumocystoscopy.

Power injection of microcatheters: an in vitro comparison.

PURPOSE: To determine the tolerance of 0.021-inch and 0.027-inch microcatheters to power injection in an in vitro flow model. MATERIALS AND METHODS: Twenty-four microcatheters (0.021-inch, n = 13; 0.027-inch, n = 11) were injected with iothalamate meglumine through a flow model with use of a power injector and high-pressure tubing. Catheters used included Rebar (0.021-inch, n = 4; 0.027-inch, n = 4), Transit (0.021-inch, n = 3; 0.027-inch, n = 3), Renegade (0.021-inch, n = 4; 0.027-inch, n = 4), and Renegade STC-18 (0.021-inch, n = 2) models. Through the 0.021-inch microcatheters, 5-second injections were performed at an initial rate of 0.7 mL/sec. Injection rates were increased by 0.5 mL/sec and the process was repeated until the pressure approached 1,000 psi or catheter breakage occurred. A similar process was repeated for the 0.027-inch catheters starting at a rate of 3.4 mL/sec. RESULTS: The 0.021-inch catheters were injected 303 times and the 0.027-inch catheters were injected 210 times. Three catheter failures occurred, with all breaks occurring at pressures greater than manufacturer recommendations. The 0.027-inch catheters as a group tolerated significantly higher injection rates than the 0.021-inch catheters. Of the 0.021-inch catheters, the STC-18 also provided superior maximum flow and volume compared with the Renegade catheter. The Rebar catheter tolerated significantly lower maximum injection rates and volumes than the other 0.027-inch catheters. CONCLUSIONS: The majority of microcatheters can be power-injected in vitro at pressures far greater than manufacturer recommendations. When fractures occur, they are near the hub of the catheter. Significantly greater rates of injection are possible through 0.027-inch catheters.

Peak contrast enhancement in CT and MR angiography: when does it occur and why? Pharmacokinetic study in a porcine model.

PURPOSE: To investigate pharmacokinetic and physiologic factors that determine the time to peak intravenous contrast medium enhancement in computed tomographic (CT) and magnetic resonance (MR) angiography in the porcine mid-abdominal aorta. MATERIALS AND METHODS: Four pigs were imaged repeatedly in seven to eight sets: For each set, 20 dynamic CT scans were obtained at a fixed aortic level after intravenous injection of contrast medium. From a physiologically based compartment model, aortic contrast enhancement curves were generated by varying contrast medium injection duration from 1 to 40 seconds. Contrast enhancement curves and times to peak aortic enhancement from the experiment and model were compared. Time to peak aortic enhancement obtained from the injection with the shortest duration was considered the time to peak test bolus contrast enhancement. Mathematic and pharmacokinetic analyses were performed to investigate factors that determine peak enhancement. RESULTS: Empiric and compartmental model times to peak aortic enhancement were in good agreement. Time to peak aortic enhancement corresponded to the weighted sum of injection duration and time to peak test bolus enhancement. With increasing injection duration, the relative contribution of injection duration to peak aortic enhancement time increased. When injection duration was longer than time to peak test bolus enhancement, time to peak aortic enhancement increased linearly with injection duration and occurred shortly after completion of injection. However, when injection duration was shorter than time to peak test bolus enhancement, time to peak aortic enhancement was determined predominantly by time to peak test bolus enhancement and only gradually increased with injection duration. CONCLUSION: Time to peak aortic enhancement is determined by the relative contributions of injection duration and contrast medium traveling time and may well be explained by contrast medium volumetric inflow and recirculation physiology.

Comparative cytotoxicity of low-osmolar nonionic and high-osmolar ionic contrast media to dog gallbladder epithelial cells.

BACKGROUND: Most studies of the adverse effects of x-ray contrast media used in ERCP have focused on post-ERCP pancreatitis. However, the biliary epithelial cells are also exposed to contrast media during ERCP and acute cholangitis is also a serious complication of ERCP. The present study compared the cytotoxicity with gallbladder epithelial cells of ionic and nonionic contrast agents. METHODS: A high-osmolar ionic contrast agent (meglumine ioxithalamate) and a low-osmolar nonionic contrast agent (iopromide) were tested. Monolayer cell cultures of dog gallbladder epithelial cells were used. The cells were exposed to the 2 contrast agents with increasing iodine concentration and osmolality for 2 days. Cell number, S-phase fraction, aneuploidy, and supernatant LDH activities were measured each day. RESULTS: Cell growth was more severely inhibited by ioxithalamate than iopromide (p < 0.05) and strongly dependent on the osmolality of contrast agent. The cytostatic effect estimated by S-phase fraction was more pronounced for ioxithalamate. Chromosomal damage determined by aneuploidy was more frequently detected with ioxithalamate. CONCLUSIONS: High-osmolar ionic contrast media are more cytotoxic than low-osmolar nonionic contrast media to gallbladder epithelial cells. Animal and clinical studies are needed to estimate the clinical implications of these findings.

Multiphasic injection method for uniform prolonged vascular enhancement at CT angiography: pharmacokinetic analysis and experimental porcine model.

PURPOSE: To determine if multiphasic injection provides uniform, prolonged vascular contrast medium enhancement at computed tomographic (CT) angiography. MATERIALS AND METHODS: With a computer-based, compartmental model of the cardiovascular system, theoretic analysis was performed to estimate an injection algorithm for uniform, prolonged vascular enhancement. For algorithm validation, four pigs were scanned after intravenous injection of 50 or 70 mL of contrast medium (282 mg of iodine per milliliter). Uni-, bi-, and multiphasic injection schemes were tested. In most cases, the initial injection rate was 2 mL/sec. In each CT study, 27 dynamic images were acquired every 2 seconds at a fixed mid-abdominal aortic level. Time-enhancement curves were calculated. Injection duration, peak aortic enhancement, and enhancement uniformity (duration of enhancement achieved within 90% of the peak [90% DCE]) were evaluated. RESULTS: Theoretic and experimental results agreed well. Compared with uniphasic injection, biphasic injection resulted in more prolonged enhancement but generated two enhancement peaks with a valley between, and multiphasic injection yielded more uniform and prolonged enhancement. With 50- and 70-mL multiphasic injections, respectively, injection duration increased by 32% and 51%, peak enhancement decreased by 19% and 18%, and 90% DCE increased by 81% and 94%. CONCLUSION: Uniform, prolonged vascular enhancement, which is desirable for CT angiography and essential for steady-state quantification of blood volume in organs, can be achieved with multiphasic injection.

Experimental study of mortality and morbidity of contrast media and standardized fecal dose in the peritoneal cavity.

BACKGROUND: The use of radiographic contrast media in the setting of possible bowel ischemia and potential perforation is known to be associated with increased clinical risk. However, there is a lack of controlled studies using a standard native fecal load to define and compare the intrinsic mortality and morbidity among options of contrast media currently available to the radiologist. We have compared the mortality and gross and histopathologic morbidity of a standard intraperitoneal native fecal dose in the guinea pig, using barium, two iodinated media, saline and air. MATERIALS AND METHODS: The study was performed on adult Hartley guinea pigs. A standard native fecal solution with a colony count of 10(8) aerobes and 2 x 10(7) anaerobes was prepared, and the LD50 of intraperitoneal injection of the solution was determined. The standard solution at the LD50 dose was then used to compare the mortality and morbidity when commercial barium sulfate (18% w/v), Conray 30 (iothalamate meglumine 30%), 1:1 dilution of Conray 30 with sterile water, termed Conray "15" (iothalamate meglumine 15%), saline and air, were added to the intraperitoneal injection of the fecal solution in five groups of 20 animals each. Mortality and acute (96 h) and chronic (30 days) gross and histopathology were assessed and graded according to a standard system and analyzed statistically. RESULTS: Barium was significantly more deleterious than the dilute water-soluble iodinated media, saline and air. Mortality occurred within 24 h in the barium group and within the initial 48 h in all groups as follows: barium 19/20 (95%); Conray 30 16/20 (80%); Conray "15" 7/20 (35%); saline 0; air 0. Acute gross and histopathology showed extensive grade 4 lesions in 19/19 barium animals; less severe lesions were present in a lesser percentage of the animals in the other four groups. Entirely chronic lesions were present only in the single surviving barium animal and were non-significant (< 400 microns) or absent in the other four groups. CONCLUSIONS: In our study, barium incurred the most significant deleterious short and long-term effects in the setting of fecal peritonitis. Dilute water-soluble media offer a much greater margin of safety. Saline under sonographic guidance is less deleterious than any of the positive radiographic contrast media. However, in our study, air was the safest contrast medium in the setting of peritoneal soiling.