Combined rare anatomic variants: persistent primitive olfactory artery and azygos pericallosal artery

The persisting primitive olfactory artery (PPOA) is a rare anatomic variation of the anterior cerebral artery (ACA), being encountered in less than 1% of cases. Different morphological types were reported previously. In type 3, only once reported previously, the PPOA gives off two branches, a nasal one which courses in the olfactory sulcus to supply the territory of the anterior ethmoidal artery, and the callosomarginal artery. It is reported here a combination of rare anatomic variants found in a 71-year-old male patient investigated by computed tomography angiography. A left PPOA left the A1 segment of the ACA and was classified as subtype 3b, as its branches were the nasal one and a frontal trunk, not the callosomarginal artery. That PPOA had a characteristic hairpin turn applied on the anterior fossa floor. The ACA continued as azygos pericallosal artery, which is also a rare finding. As the nasal branch of the PPOA and its hairpin turn is closely related to the anterior fossa floor, such variant should be carefully documented when combined approaches of the skull base are planned by rhinologists and neurosurgeons.

Minimizing contrast media dose in CT pulmonary angiography with high-pitch technique

OBJECTIVES

To perform CT pulmonary angiography (CTPA) using a minimal amount of iodinated contrast media.

METHODS

47 patients (25 females) with mean age 69 years (range 41-82 years) referred for contrast-enhanced chest CT were prospectively included in this Phase IV clinical drug trial. All participants underwent a study specific CTPA in addition to the chest CT. The participants received 80 mg I/kg body weight Iohexol contrast media using a preparatory saline bolus, a dual flow contrast/saline bolus and a saline flush, and a scanner protocol with 80 kVp dual source high-pitch mode. Three readers independently assessed the image quality on the 3-point scale non-diagnostic, adequate or good-excellent image quality. Additionally, the pulmonary arterial contrast opacification was measured.

RESULTS

On average, the patients received 16.8 ml Iohexol 350 mg I/mL (range 12-20 ml). Mean patient weight was 71 kg (range 50-85 kg). Identically for all readers, pulmonary embolism (PE) was detected in 1/47 participants. The median number of examinations visually scored concerning pulmonary embolism as good-excellent was 47/47 (range 44-47); adequate 0/47 (0-3) and non-diagnostic 0/47 (range 0-0). The proportion adequate or better examinations was for all readers 47/47, 100% [95% confidence interval 92-100%]. The mean attenuation ± standard deviation in the pulmonary trunk was 325 ± 72 Hounsfield unit (range 165-531 Hounsfield unit).

CONCLUSIONS

Diagnostic CTPA with 17 ml contrast media is possible in non-obese patients using low kVp, high pitch and carefully designed contrast media administration.

ADVANCES IN KNOWLEDGE

By combining several procedures in a CTPA protocol, the contrast media dose can be minimized.

Assessment of the glomerular filtration rate (GFR) in kidney transplant recipients using Bayesian estimation of the iohexol clearance

Background Plasma iohexol clearance (CLiohexol) is a reference technique for glomerular filtration rate (GFR) determination. In routine practice, CLiohexol is calculated using one of several formulas, which have never been evaluated in kidney transplant recipients. We aimed to model iohexol pharmacokinetics in this population, evaluate the predictive performance of three simplified formulas and evaluate whether a Bayesian algorithm improves CLiohexol estimation. Methods After administration of iohexol, six blood samples were drawn from 151 patients at various time points. The dataset was split into two groups, one to develop the population pharmacokinetic (POPPK) model (n = 103) and the other (n = 48) to estimate the predictive performances of the various GFR estimation methods. GFR reference values (GFRref) in the validation dataset were obtained by non-compartmental pharmacokinetic (PK) analysis. Predictive performances of each method were evaluated in terms of bias (ME), imprecision (root mean square error [RMSE]) and number of predictions out of the ±10% or 15% error interval around the GFRref. Results A two-compartment model best fitted the data. The Bayesian estimator with samples drawn at 30, 120 and 270 min allowed accurate prediction of GFRref (ME = 0.47%, RMSE = 3.42%), as did the Brøchner-Mortensen (BM) formula (ME = - 0.0425%, RMSE = 3.40%). With both methods, none of the CL estimates were outside the ±15% interval and only 2.4% were outside the ±10% for the BM formula (and none for the Bayesian estimator). In patients with GFR ≤30 mL/min/1.73 m2, the BM formula performed very well, while the Bayesian method could not be evaluated in depth due to too small a number of patients with adequate sampling times. Conclusions GFR can be estimated with acceptable accuracy in kidney transplant patients using the BM formula, but also using a Bayesian algorithm.

Compatibility of Melphalan in Iodinated Contrast Media

Melphalan is used in selective ophthalmic artery infusion chemotherapy. In the procedure to catheterize the ophthalmic artery in selective ophthalmic artery infusion chemotherapy, the microcatheter is usually filled with an iodinated contrast medium. It is not known whether mixing of iodinated contrast medium with melphalan solutions promotes precipitation of melphalan during selective ophthalmic artery infusion chemotherapy. The objective of the present study was to examine the compatibility of melphalan and iodinated contrast medium. In the experiments, melphalan solutions were prepared with and without iodinated contrast medium (iohexol 300 mg Iodine/mL or ioversol 74%). Melphalan solution of clinically relevant concentration (0.45 mg/mL) in the absence of iodinated contrast medium was evaluated as a reference. The 0.45-mg/mL melphalan solution was diluted with iodinated contrast medium at 1:9 and 1:1 ratios to form solutions comprising iodinated contrast medium at 10% or 50% (v/v), and each was evaluated. The formation of particles was examined using filtration (pore size 0.45 µm) followed by high-performance liquid chromatography at four quarterly time intervals (15 min, 30 min, 45 min, and 60 min) over a 1-hour period after solution preparation. High-performance liquid chromatography analysis of microfiltered solutions did not reveal evidence of melphalan crystal formation over a 60-minute period for the solutions studied. The filtration studies suggest that mixing of the iodinated contrast medium with melphalan solutions does not result in significant melphalan precipitation.

Contrast Extravasation using Power Injectors for Contrast-Enhanced Computed Tomography in Children: Frequency and Injury Severity

PURPOSE

To evaluate the safety of power injectors for contrast-enhanced computed tomography (CT) in children, namely: the prevalence and injury severity of contrast extravasations related to power injectors and the factors associated with these events.

METHODS

The need to obtain informed consent was waived for this HIPAA-compliant and IRB approved retrospective study. Around 2429 contrast-enhanced CT performed with a power injector were identified during a 3-year period. Data collected included patient demographic, power injector, and contrast agent information. The patients' symptoms, severity of injury and treatment with contrast extravasation were recorded. Around 1496 cases (823 boys, 673 girls) were included in the analysis. Independent-sample t test and Chi-square were used. For a sub-analysis using the extravasation cases, nonparametric tests were used.

RESULTS

The mean age was 9.5 ± 6.1 years. The most common access site, catheter site, and contrast agent used were the antecubital fossa, 22 gauge and Iohexol. The mean peak pressure was 68.9 ± 62.3 psi and the flow rate was 1.7 ± 0.9 mL/s. Eighteen cases of contrast extravasation were identified with a mean age of 11.2 ± 6.2 years. There were seven mild, six moderate, and five severe. Cases with extravasation had significantly higher peak pressure (p < 0.001) and flow rate (p < 0.001) compared to those without extravasation. Patients who received Iohexol-350 had significantly more contrast extravasation compared to those who used Iohexol-300 (p = 0.03). However, after post-hoc correction, only peak pressure (p < 0.01) and flow rate (p = 0.01) remained significant.

CONCLUSION

The use of power injectors in children undergoing contrast-enhanced CT is associated with a low rate of extravasation and of long-term injury.

Abdominal lymphatic drainage after thoracic duct ligation and cisterna chyli ablation in clinically normal cats

OBJECTIVE

To characterize abdominal lymphatic drainage in cats after thoracic duct ligation (TDL) and cisterna chyli ablation (CCA).

ANIMALS

7 purpose-bred research cats.

PROCEDURES

Baseline CT lymphangiography was performed. A popliteal lymph node was injected with iohexol, and images were acquired at 5-minute intervals for 15 minutes. Cats underwent TDL and CCA; methylene blue was used to aid in identifying lymphatic vessels. The CT lymphangiography was repeated immediately after and 30 days after surgery. All cats were euthanized and necropsied.

RESULTS

Results of baseline CT lymphangiography were unremarkable for all 7 cats. Only 5 cats completed the study. Leakage of contrast medium at the level of the cisterna chyli was seen on CT lymphangiography images obtained from all cats immediately after surgery. Evaluation of 30-day postoperative CT lymphangiography images revealed small branches entering the caudal vena cava in 2 cats, leakage of contrast medium into the caudal vena cava with no visible branches in 1 cat, and no contrast medium in the caudal vena cava in 2 cats. Contrast medium did not flow beyond the level of the cisterna chyli in any cat. Gross examination during necropsy revealed that all cats had small lymphatic vessels that appeared to connect to local vasculature identified in the region of the cisterna chyli.

CONCLUSIONS AND CLINICAL RELEVANCE

Abdominal lymphaticovenous anastomoses formed after TDL and CCA in cats. This would support use of these procedures for treatment of cats with idiopathic chylothorax, although additional studies with clinically affected cats are warranted.

Iohexol-measured glomerular filtration rate in children and adolescents with chronic kidney disease: a pilot study comparing venous and finger stick methods

BACKGROUND

Measurement of glomerular filtration rate by iohexol disappearance (iGFR) has become a gold standard in the pediatric chronic kidney disease (CKD) population. The need for serial phlebotomy can be difficult and minimizing venipunctures would be beneficial. Furthermore, finger stick collection for dried blood spot (DBS) may be more tolerable in the pediatric population, and equivalence between these two methods may further simplify the process.

METHODS

This was a cross-sectional study in children and adolescents 1 to 21 years with stages I-IV CKD. Iohexol was infused and blood drawn 10, 30, 120, and 300 min later. Blood spots on filter paper were collected by finger stick after each of the latter two blood draws. The rate of iohexol plasma disappearance was used to calculate GFR. Pearson's correlation coefficient and bias, Students t test, and Bland-Altman graphical representations were used to compare methods.

RESULTS

Forty-one patients were recruited. The mean creatinine was 1.13 mg/dL (SD 0.45), the mean 4-point iGFR was 73.2 ml/min/1.73m² (SD 27.5) and the mean 2-point iGFR was 75.6 ml/min/1.73m² (SD 27.3). Correlation between 2-point and 4-point venous GFR was r = 0.97; p < 0.001. The correlation between the DBS and the 2-point venous GFR was r = 0.95; p < 0.001, with no significant bias. Ninety-four percent of the 2-point GFR's were within 10% of the 4-point GFR's and 80% of DBS-GFRs were within 10% of the 2-point GFR's.

CONCLUSIONS

The 2-point iGFR was highly correlated and agreed well with the 4-point iGFR. The same was true for the DBS method and the 2-point venous method. DBS sampling by finger stick sampling at 2 time points after iohexol infusion gave an acceptably accurate measurement of GFR.

Piston-Based vs Peristaltic Pump-Based CT Injector Systems

PURPOSE

To compare the fluid delivery performance of 2 different technologies for administration of iodinated contrast media in computed tomography (CT).

METHODS

The maximum achievable flow rate and the steady-state flow rate variance of a piston-based contrast media injector system (Stellant MP, MEDRAD) was compared with peristaltic pump-based injector systems (CT motion, Ulrich Medical; CT Exprès, Bracco). The contrast media iopromide (Ultravist) and iopamidol (Isovue) were used at 2 concentrations each (300 and 370 mg I/mL) and 3 catheter sizes (18, 20, and 22 G) to test the injector performance.

RESULTS

Average maximum achievable flow rates for room temperature iopromide (370 mg I/mL) using a 20 G catheter were 7.6, 7.1, and 4.8 mL per second for the Stellant MP injector, CT motion injector, and CT Exprès injector, respectively. The Stellant MP injector achieved significantly higher flow rates compared to the CT Exprès injector for all catheter sizes tested (P<.001). Higher flow rates also were observed for the Stellant MP injector compared to the CT motion injector, with 20 G and 22 G catheters (P<.001). The Stellant MP injector featured a constant steady-state flow rate (variance<0.04 mL/s), whereas the other systems injected in a pulsatile fashion, with significantly greater variance (P<.001).

DISCUSSION

To the authors' knowledge, this is the first reported laboratory study providing preliminary evidence of differences between the fluid delivery performance of CT injection systems. Additional investigations using a dedicated flow phantom simulating human physiological flow parameters should be conducted, and depending on the results, a clinical study could assess the effect on image quality.

CONCLUSION

The piston-based injector demonstrated higher maximum achievable flow rates and more consistent steady-state flow when compared to peristaltic pump-based injectors.

The Differential Flow of Epidural Local Anaesthetic via Needle or Catheter: A Prospective Randomized Double-blind Study

The extent of epidural anaesthesia and pattern of spread of contrast medium, using different injection techniques, has not been well documented. Therefore, in this prospective, randomized, double-blind study, the extent of anaesthesia and pattern of spread of contrast medium following an epidural bolus injection, via either a Tuohy needle or an epidural catheter, were compared.

The study had two parts. In the first, 59 of 79 patients scheduled for a lower extremity operation under epidural anaesthesia were randomly allocated to one of the two groups. Anaesthesia was achieved with an epidural injection of 10 to 15 ml (including a 3 ml test dose) of 0.75% ropivacaine and fentanyl 25 μg via either a Tuohy needle (Group N, n=31) or a catheter (Group C, n=28). The level of sensory anaesthesia was recorded. In the second part, the remaining 20 patients were randomized to initially receive 5 ml of contrast medium via either a Tuohy needle (Group NE, n=10) or a catheter (Group CE, n=10). The extent of spread was recorded radiologically.

Unilateral or missed blocks and additional dose requirement were absent in Groups N and C. No differences were found in the extent of sensory anaesthesia or the spread of contrast medium. Twenty per cent of catheter tips lay outside the lateral margins of the vertebral bodies.

We found that an epidural bolus injection, via either a Tuohy needle or a catheter, made no difference in regard to spread of local anaesthetic or contrast medium in the epidural space.

CT-guided transforaminal epidural steroid injections: do needle position and degree of foraminal stenosis affect the pattern of epidural flow?

OBJECTIVE

To determine the effect of needle position and foraminal stenosis on contrast flow directionality during CT-guided transforaminal epidural steroid injections (TFESI).

MATERIALS AND METHODS

One hundred five consecutive CT-guided injections were performed in 68 patients (mean age, 65.5 years) from January 1 to December 31 2017, all with preceding MRI. Two readers independently reviewed CT images to assess needle position and to determine direction of contrast flow, which was defined as central or peripheral. The MRIs were independently reviewed by the readers to determine the degree of foraminal stenosis. Inter-reader agreement for both was evaluated with the kappa statistic. Analyses were performed to determine effect of needle position, degree of foraminal stenosis, and volume of contrast injected with directionality of contrast flow, and association between contrast flow directionality with immediate post-procedural pain scores.

RESULTS

Central direction of contrast flow was demonstrated in 41/78 (52.6%) of cases with posterolateral needle position, and 20/27 (74.1%) with central or anteromedial needle position (p = 0.07). There was no difference in direction of contrast flow with high-grade versus absence of high-grade neuroforaminal narrowing, or with volume of contrast injected. There was no difference in immediate post-procedure pain scores regardless of contrast flow directionality.

CONCLUSIONS

Needle position is not significantly associated with contrast flow directionality during CT-guided TFESI, although there was a trend towards relatively decreased central flow with posterolateral positioning. Degree of foraminal stenosis and volume of injected contrast did not affect contrast flow directionality. There was no difference in immediate post-procedural pain scores with either direction of contrast flow.

Influence of injection protocol and measurement technique on computed tomographic assessment of glomerular filtration rate in healthy Beagles

OBJECTIVE To compare values of CT-derived glomerular filtration rate (GFR) determined by 3 contrast-medium injection protocols and 4 measurement techniques in healthy Beagles. ANIMALS 9 healthy Beagles (mean ± SD weight, 13.2 ± 1.6 kg). PROCEDURES Each dog underwent 3 iohexol-injection protocols (700 mg of iodine/kg administered at a constant rate over 20 seconds, 700 mg of iodine/kg administered following an exponentially decelerated injection over 20 seconds, and 350 mg of iodine/kg at a constant rate over 10 seconds) during dynamic, whole renal-volume CT in randomized order with an interval of ≥ 7 days between experiments. Values of GFR determined from Patlak plots derived by use of 4 measurement techniques (standard transverse section, optimized transverse section, dorsal reconstruction, and volume calculation techniques) were compared. RESULTS The measurement technique influenced the mean ± SD GFR results (standard transverse section technique, 2.49 ± 0.54 mL/kg/min; optimized transverse section technique, 2.72 ± 0.52 mL/kg/min; dorsal reconstruction technique, 3.00 ± 0.60 mL/kg/min, and volume calculation technique, 2.48 ± 0.51 mL/kg/min). The lower iodine dose resulted in a significantly higher GFR value (3.00 ± 0.65 mL/kg/min), compared with that achieved with either higher dose administration (constant rate injection, 2.54 ± 0.45 mL/kg/min and exponentially decelerated injection, 2.47 ± 0.48 mL/kg/min). CONCLUSIONS AND CLINICAL RELEVANCE In healthy Beagles, the CT-derived GFR measurements obtained after injection of a full dose of contrast medium were reduced, compared with measurements obtained after injection of a half dose. This finding is important with regard to potential nephrotoxicosis in dogs with impaired renal function and for GFR measurement with CT-contrast medium protocols.

Computed tomography portography of patients with cirrhosis with normal body mass index: Comparison between low-tube-voltage CT with low contrast agent dose and conventional CT

This study is to investigate the computed tomography (CT) image quality of the low- tube-voltage protocol with low contrast agent dose.CT portography was performed in 118 cirrhosis patients with body mass index (BMI) less than 25 kg/m under 2 protocols: Protocol A, tube voltage of 90 kVp/395 mAs and contrast agent dosage of 1.2 mL/kg, and, Protocol B, tube voltage of 120 kVp/200 mAs and contrast agent dosage of 1.5 mL/kg.The number of patients in each protocol was 59. The CT value noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) in portal veins was comparatively analyzed between the 2 protocols. The subjective image quality was further assessed on 5-point scales. Radiation dose was also recorded and statistical analysis was performed.The CT value, CNR, and SNR of the images were higher at 90 kVp than those at 120 kVp (P < .05). There was no significant difference in image noise between the 2 protocols (P > .05). The CT dose index volume, dose-length product, and effective dose at 90 kVp were 18.2%, 16.0%, and 16.0% less than that at 120 kVp, respectively. There was no difference in image quality score between the 2 protocols (P > .05). The average amount of contrast agent was decreased by 17.8% when the 90 kVp protocol was used.CT portography at 90 kVp combined with low-dosage contrast agent leads to a significant reduction in radiation dose and improved SNR and CNR, without deterioration of image quality.

Measured Glomerular Filtration Rate After Kidney Donation: No Evidence of Accelerated Decay

BACKGROUND

The rate of measured glomerular filtration rate (GFR) change in kidney donor years after donation has not been adequately addressed. Whether this change is accelerated in the setting of 1 kidney is also understudied.

METHODS

Two hundred fourteen randomly selected donors underwent serial GFR measurements of nonradioactive iohexol. Estimated GFR at each visit was calculated using the Chronic Kidney Disease Epidemiology Collaboration and Modification of Diet in Renal Disease study equations.

RESULTS

Glomerular filtration rate visits were 4.8 ± 1.3 years apart and the second occurring 16.9 ± 9.1 years after donation. Most (97.7%) were white, 60.8% female, and 78.5% were related to their recipient. Most, 84.6%, had a GFR of 60 mL/min per 1.73 m or higher, 14.0% had a GFR between 45 and 60 mL/min per 1.73 m, and 1.4% had a GFR less than 45 mL/min per 1.73 m. Between visits 1 and 2, 56.5% had a GFR decline, 36.0% increase, and in 7.5%, there was no change. Overall, GFR declined at a rate of -0.42 mL/min per 1.73 m per year. Of GFR estimating models, only Chronic Kidney Disease Epidemiology Collaboration-Creatinine equation produced a slope that was steeper than measured GFR.

CONCLUSIONS

Nearly 2 decades postdonation GFR declined at a rate similar to that seen in the general population, and in one third, GFR continues to increase.

320-row CT transcatheter aortic valve replacement planning with a single reduced contrast media bolus injection

OBJECTIVE

To reduce the iodine load required for CT Transcatheter Aortic Valve Replacement (TAVR) planning on a 320-row scanner by acquiring the two CT TAVR steps (ECG-gated aortic root CTA and non-gated aorto-ilio-femoral CTA) within a single contrast media bolus injection.

METHODS

50 consecutive patients (82.6±6.9 years; 56% female) were prospectively enrolled and underwent a TAVR planning using a 320-row CT, with ECG-gated aortic root CTA immediately followed by a non-gated aorto-iliac acquisition, all within a single bolus of 40-70mL of Iohexol 350mgI/mL. The Iodine load, image quality, SNR, CNR and radiation dose were compared using a Mann-Whitney test to that of 24 consecutive patients (84.3±4.8 years, 58% female) previously imaged on a 64-row scanner with a conventional two-step protocol.

RESULTS

Iodine load was reduced by 44%. All examinations were of diagnostic quality, with improvement of the aortic root CTA image quality (4.9±0.3 versus 4.6±0.5, p<0.01) and a non-significant decrease of the aorto-iliac CTA image quality (4.7±0.6 versus 4.9±0.3, p = 0.07). SNR and CNR were significantly improved in the aortic root CTA (14.0±5.3 and 10.4±4.5 versus 10.3±4.2 and 6.8±3.3, p<0.01 for both) and non-significantly higher in the aorto-iliac CTA (16.5±8.0 and 14.1±7.9 versus 14.7±5.5 and 12.5±5.0, p = 0.42 and p = 0.66). Total radiation dose was reduced by 32%.

CONCLUSION

320-row CT scanner enables a 44% reduction of iodine load in TAVR planning, while maintaining excellent aorto-ilio-femoral arterial enhancement and lowering radiation dose.

Effect of iodinated contrast medium on thyroid function: a study in children undergoing cardiac computed tomography

BACKGROUND

Few studies, and with conflicting results, have evaluated the potential effects of iodinated contrast media on children's thyroid function.

OBJECTIVE

To investigate the effects of iodinated contrast medium on thyroid function in neonates, infants and young children with congenital heart disease undergoing cardiac computed tomography (CT).

MATERIALS AND METHODS

We retrospectively evaluated 10 neonates (group 1) and 23 infants and young children (group 2) without thyroid or renal disease for serum levels of thyroid-stimulating hormone, free triiodothyronine and free thyroxine before contrast-enhanced cardiac CT, 48 h after CT and at discharge from the hospital. Cardiac CT was performed with intravenous administration of 1.14±0.17 mL/kg of body weight of iopromide (containing 370 mg of iodine/mL).

RESULTS

Group 1 had a reduction of thyroid-stimulating hormone from baseline to 48 h post injection (P=0.002). Group 2 had a reduction of thyroid-stimulating hormone median levels from baseline to 48 h post injection and an increase from 48 h to discharge (P=0.0005 and P=0.0001, respectively).

CONCLUSION

Intravenous iodinated contrast medium in children with congenital heart disease caused transient thyroid-stimulating hormone decrease 48 h after CT, with thyroid-stimulating hormone returning to normal range at discharge.

Bilateral Sustained Nephrograms After Parenteral Administration of Iodinated Contrast Material: A Potential Biomarker for Acute Kidney Injury, Dialysis, and Mortality

OBJECTIVE

To determine whether persistent bilateral global nephrograms are associated with acute kidney injury (AKI), dialysis, and mortality.

PATIENTS AND METHODS

All patients who underwent (1) contrast-enhanced computed tomography (CT) or cardiac catheterization with iohexol between January 1, 2000, and December 31, 2014, and (2) noncontrast abdominal CT in the subsequent 24±6 hours were identified. Patients without preprocedure and postprocedure creatinine measurements or who received additional contrast material were excluded. Nephrograms were identified by radiologist review and CT attenuation measurements. Univariate and multivariate analyses were performed to determine nephrogram risk factors. Acute kidney injury (defined as a creatinine level of ≥0.5 mg/dL or Kidney Disease: Improving Global Outcomes stages 1-3), dialysis, and mortality proportions were compared between patients with and without bilateral global nephrograms using the Fisher's exact test.

RESULTS

A total of 123 patients met all inclusion criteria. The proportion of patients with a nephrogram was 37.4% (n=46), with a higher proportion following interventional (67% [18 of 30]) vs diagnostic (27.3% [9 of 33]) catheterization or contrast-enhanced computed tomography (31.7% [19 of 60]). Age (P=.002), chronic kidney disease (P=.05), and acute hypotension or shock (P=.02) were significant risk factors for nephrogram development. Patients with nephrogram had significantly higher rates of AKI (37.0% [17 of 46] vs 5.2% [4 of 77]; odds ratio [OR], 10.7 [95% CI, 3.31-34.5]; P<.001), dialysis (17.4% [8 of 46] vs 1.3% [1 of 77]; OR, 16.0 [95% CI, 1.93-133]; P=.001), and mortality (15.2% [7 of 46] vs 1.3% [1 of 77]; OR, 13.6 [1.62-115]; P=.003) than patients without nephrogram.

CONCLUSION

The presence of persistent bilateral global nephrograms suggests an increased risk of AKI, dialysis, and mortality when compared with patients whose kidneys fully eliminated the contrast material.

Iso-Osmolar Iodixanol Induces Less Increase in Circulating Endothelial Microparticles In Vivo and Less Endothelial Apoptosis In Vitro Compared with Low-Osmolar Iohexol

Background and Aims

There is no consensus on whether iodixanol is superior to iohexol. This study aimed to compare the effects of iodixanol and iohexol on circulating endothelial microparticles (EMPs) in stable coronary artery disease (CAD) patients with diabetes mellitus (DM), and also their cytotoxic effects on human umbilical vein endothelial cells (HUVECs) in vitro.

Methods

100 CAD patients with DM were randomly assigned to receive iso-osmolar contrast medium iodixanol (group I) or low-osmolar iohexol (group II) during coronary angioplasty. An additional 49 CAD patients without DM receiving iohexol were recruited as group III. Circulating CD31+/CD41a- EMPs, CD62E+ EMPs, and CD31+/CD41a+ platelet microparticles (PMPs) were determined by flow cytometry. In vitro, the cytotoxic effects of iodixanol and iohexol on HUVECs were determined.

Results

Circulating CD31+/CD41a- EMPs and PMPs were significantly increased after angioplasty in all 3 groups, while CD62E+ EMPs significantly decreased in group I. CD31+/CD41a- EMPs and PMPs were significantly higher in group II than group I or III. In vitro, both contrast media induced EMP release and inhibited the viability and induced apoptosis of HUVECs, as well as increasing Bax and cleaved caspase-3 and decreasing Bcl-2. The above effects were less evident in iodixanol than in iohexol.

Conclusions

Compared with iohexol, iodixanol induces less release of EMPs in both CAD patients with DM during angioplasty and in vitro HUVEC culture, which is associated with less pronounced proapoptotic effects of iodixanol on HUVECs.

Clinical Study Registration Number

This study is registered with ChiCTR-TRC-14005183.

Study on the Correlation between Barium Radiography and Pulmonary Infection rate in the Evaluation of Swallowing Function

OBJECTIVES

To compare the results respectively obtained from the utilization of 60% barium sulfate suspension and Iohexol as contrast agents for videofluoroscopic swallowing studies and the relationship between the clinical application of the two kinds of contrast agents and the incidence of pneumonia.

METHODS

Sixty cases of stroke patients with dysphagia were selected in rehabilitation department of our hospital, and the gender, age, position of the disease, and stroke nature between groups had no significant difference. Among which, 30 patients who were administered 350 mgI/ml Iohexol, and the other 30 patients with 60% barium sulfate suspension as contrast agent. We performed videofluoroscopic swallowing studies with barium 60% versus Iohexol within 1 week after admission and 2 weeks after admission.

RESULTS

After 2 weeks in hospital, the aspiration pneumonia incidence of two groups was statistically significant (p<0.05), the pneumonia incidence of Iohexol group was lower than barium sulfate group which might have a impossble relevance with barium aspiration.

CONCLUSIONS

During the videofluoroscopic swallowing study of dysphagia after stroke, barium sulfate can enhance the pneumonia incidence, and Iohexol can be widely applied in videofluoroscopic swallowing study.

Qualitative and Quantitative Assessment of Abdominal and Pelvic CT Image Quality Using Iopromide With Different Concentrations of Iodine (300 and 370 mg I/mL)

OBJECTIVE

The purpose of this study was to analyze the quality of MDCT images obtained using iopromide with two different concentrations of iodine (300 and 370 mg I/mL) in daily clinical settings.

SUBJECTS AND METHODS

Patients from 38 hospitals in China undergoing abdominal or pelvic CT with iopromide were prospectively recruited. MDCT was performed using iopromide with an iodine concentration of 300 or 370 mg I/mL. CT quality image was graded as excellent, good, adequate, and poor. Objective indicators were the contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR). Outcomes were compared according to organ studied, tumor type (benign vs malignant), saline usage, and type of MDCT (16-MDCT vs 64-MDCT).

RESULTS

A total of 4506 patients (63.7% men) with a mean (± SD) age of 56.3 ± 14.1 years and mean body mass index (weight in kilograms divided by the square of height in meters) of 23.2 ± 3.3 were included. Iopromide with 300 mg I/mL was used for 3042 patients (67.5%), and 370 mg I/mL was used for 1464 patients (32.2%). A total of 1847 scans (41.0%) had excellent image quality, 2454 (54.5%) had good quality, 176 (3.9%) had adequate quality, and 29 (0.6%) had poor quality. No differences were noted between CT scans that did or did not use saline, 16-MDCT versus 64-MDCT scans, and 300 versus 370 mg I/mL iopromide. Variations in the CNR and SNR were noted between the two iodine concentrations with respect to other parameters examined.

CONCLUSION

Iopromide with both concentrations of iodine provided acceptable image quality, though according to CNR and SNR, one or the other may provide better quality in different situations.

Prospective comparison of dual-energy CT aortography using 70% reduced iodine dose versus single-energy CT aortography using standard iodine dose in the same patient

PURPOSE

To compare dual-energy computed tomography (DECT) aortography using a 70% reduced iodine dose to single-energy CT (SECT) aortography using a standard iodine dose in the same patient.

METHODS

Twenty-one patients with a prior SECT aortography using standard iodine dose had DECT aortography using 70% reduced iodine dose. Section 120 kVp images were compared to DECT images reconstructed at both 50 and 77 keV. Reviewers measured image noise and attenuation in the aorta at eight locations from proximal to distal and subjectively scored vascular enhancement on a four-point scale. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. The volume CT dose index (CTDI_vol) for each exam was recorded.

RESULTS

Mean iodine dose was 50 g for SECT and 15 g for DECT (70% reduction). Mean aortic attenuation was similar for section 120 kVp (350 ± 67 HU) and DECT 50 keV (338 ± 57 HU, p = 0.547) but was lower at 77 keV (152 ± 23 HU). Measured image noise was greatest at 50 keV (12 ± 5 HU) and was lowest at 77 keV (7 ± 2 HU, p > 0.001). There was no difference in SNR or CNR between 120 kVp and 50 keV (p > 0.05). Mean subjective vascular enhancement scores for SECT were between good and excellent (3.33-3.69), and for DECT at 50 keV were between moderate and good (2.54-2.93, p < 0.0001). CTDI_vol was 13.6 mGy for SECT and 13.1 mGy for DECT (p = 0.637).

CONCLUSION

70% Reduced iodine DECT aortography may result in similar aortic attenuation, CNR, SNR, and lower although acceptable subjective image scores when compared to standard iodine SECT aortography in the same patient.

Selection of peripheral intravenous catheters with 24-gauge side-holes versus those with 22-gauge end-hole for MDCT: A prospective randomized study

PURPOSE

To compare the 24-gauge side-holes catheter and conventional 22-gauge end-hole catheter in terms of safety, injection pressure, and contrast enhancement on multi-detector computed tomography (MDCT).

MATERIALS & METHODS

In a randomized single-center study, 180 patients were randomized to either the 24-gauge side-holes catheter or the 22-gauge end-hole catheter groups. The primary endpoint was safety during intravenous administration of contrast material for MDCT, using a non-inferiority analysis (lower limit 95% CI greater than -10% non-inferiority margin for the group difference). The secondary endpoints were injection pressure and contrast enhancement.

RESULTS

A total of 174 patients were analyzed for safety during intravenous contrast material administration for MDCT. The overall extravasation rate was 1.1% (2/174 patients); 1 (1.2%) minor episode occurred in the 24-gauge side-holes catheter group and 1 (1.1%) in the 22-gauge end-hole catheter group (difference: 0.1%, 95% CI: -3.17% to 3.28%, non-inferiority P=1). The mean maximum pressure was higher with the 24-gauge side-holes catheter than with the 22-gauge end-hole catheter (8.16±0.95kg/cm² vs. 4.79±0.63kg/cm², P<0.001). The mean contrast enhancement of the abdominal aorta, celiac artery, superior mesenteric artery, and pancreatic parenchyma in the two groups were not significantly different.

CONCLUSION

In conclusion, our study showed that the 24-gauge side-holes catheter is safe and suitable for delivering iodine with a concentration of 300mg/mL at a flow-rate of 3mL/s, and it may contribute to the care of some patients, such as patients who have fragile and small veins. (Trial registration: UMIN000023727).

Carbon Dioxide as Contrast Medium to Guide Endovascular Aortic Aneurysm Repair

BACKGROUND

Iodine contrast medium (ICM) is considered to be gold standard in endovascular procedures, but its nephrotoxicity and hypersensitivity limit the widespread use. Carbon dioxide (CO₂) is considered as an alternative for endovascular procedures in patients with contraindication to ICM. However, no studies have compared the outcomes of endovascular aneurysm repair (EVAR) performed with ICM or CO₂ among patients with no contraindication to ICM.

METHODS

From May 2012 to April 2014, 36 patients with abdominal aortic aneurysms underwent EVAR in a prospective, randomized, and controlled study. Patients were randomized into 2 groups, CO₂ or ICM group.

RESULTS

We were able to perform the proposed procedures in all patients in this study. There were no conversions to open surgery and no CO₂-related complications. Endovascular material costs, duration of surgery, and time of fluoroscopy were similar between groups, and the cost of the contrast media was smaller in the CO₂ group than in the ICM group. Among CO₂ group procedures, 62.5% of the patients needed ICM complementary use.

CONCLUSIONS

The use of CO₂ as a contrast medium for EVAR is an alternative in patients with no restriction for ICM, with similar outcomes when compared to ICM, regarding duration of surgery, duration of fluoroscopy, and endovascular material costs. Using CO₂, there were no changes in creatinine clearance and no risk of hypersensitivity reactions; moreover, there was a reduction in contrast-related costs for EVAR procedures. However, in our study, additional use of ICM to visualize the internal iliac artery was needed in most procedures.

Arterial enhancement at abdominal CT angiography: Low- versus high-osmolality contrast media

Purpose: To evaluate the effects of contrast media pharmokinetic differences on aortic enhancement at abdominal CT angiography and to determine whether these effects are of clinical relevance.

Material and Methods: Two hundred and twelve patients referred for abdominal CT angiography were included in the study. All abdominal CT angiograms were performed with the same parameters (collimation 3 mm, pitch ratio 1.7, scan delay 30 s) after i.v. injection of 120 ml of contrast medium at 3 ml/s. After randomization, patients received either iobitridol 300 (low-osmolar, 300 mg I/ml), iobitridol 350 (low-osmolar, 350 mg I/ml) or ioxithalamate 350 (high-osmolar, 350 mg I/ml). The time attenuation curves obtained with the three contrast media were compared.

Results: The time attenuation curve obtained with ioxithalamate 350 was not parallel to those obtained with iobitridol 300 and iobitridol 350. Mean peak enhancements obtained with iobitridol 350 and ioxithalamate 350 were not significantly different but iobitridol 350 provided higher mean peak enhancement than iobitridol 300. Mean delays of the peak enhancements were the same with the three contrast media. After peak enhancement, the decrease of aortic opacification under a selected threshold of 200 HU was significantly slower with iobitridol 350 than with iobitridol 300 and ioxithalamate 350, whereas iobitridol 300 and ioxithalamate 350 showed no significant differences.

Conclusion: For a given iodine concentration, low-osmolality contrast media provide longer aortic opacification and may be recommended for CT angiography when long acquisition times are needed.

Differentiation of pyogenic hepatic abscesses from malignant mimickers using multislice-based texture acquired from contrast-enhanced computed tomography

BACKGROUND

Pyogenic hepatic abscess may mimic primary or secondary carcinoma of the liver on contrast-enhanced computed tomography (CECT). The present study was to explore the usefulness of the analysis of multislice-based texture acquired from CECT in the differentiation between pyogenic hepatic abscesses and malignant mimickers.

METHODS

This retrospective study included 25 abscesses in 20 patients and 33 tumors in 26 subjects who underwent CECT. To make comparison, we also enrolled 19 patients with hepatic single simple cyst. The images from CECT were analyzed using a Laplacian of Gaussian band-pass filter (5 filter levels with sigma weighting ranging from 1.0 to 2.5). We also quantified the uniformity, entropy, kurtosis and skewness of the multislice-based texture at different sigma weightings. Statistical significance for these parameters was tested with one-way ANOVA followed by Tukey honestly significant difference (HSD) test. Diagnostic performance was evaluated using the receiver operating characteristic (ROC) curve analysis.

RESULTS

There were significant differences in entropy and uniformity at all sigma weightings (P<0.001) among hepatic abscesses, malignant mimickers and simple cysts. The significant difference in kurtosis and skewness was shown at sigma 1.8 and 2.0 weightings (P=0.002-0.006). Tukey HSD test showed that the abscesses had a significantly higher entropy and lower uniformity compared with malignant mimickers (P=0.000-0.004). Entropy (at a sigma 2.0 weighting) had the largest area under the ROC curve (0.888) in differentiating abscesses from malignant mimickers, with a sensitivity of 81.8% and a specificity of 88.0% when the cutoff value was set to 3.64.

CONCLUSION

Multislice-based texture analysis may be useful for differentiating pyogenic hepatic abscesses from malignant mimickers.

Dual-energy CT Aortography with 50% Reduced Iodine Dose Versus Single-energy CT Aortography with Standard Iodine Dose

RATIONALE AND OBJECTIVES

Because many patients with aortic pathology also have compromised renal function, we wished to investigate dual-energy computed tomography (DECT) aortography with 50% reduced iodine dose compared to single-energy computed tomography (SECT) aortography with standard iodine dose.

MATERIALS AND METHODS

Fifty patients had DECT aortography with 50% reduced iodine dose. Thirty-four of these patients had prior SECT aortography with standard iodine dose. DECT images were reconstructed at both 50 and 77 keV and were compared to SECT 120 kVp images. Reviewers measured aortic attenuation, image noise, and scored vascular enhancement. Signal-to-noise ratios (SNR) and contrast-to-noise ratios (CNR) were calculated. Volume CT dose index was recorded.

RESULTS

Mean iodine dose was 47 g for SECT and 24 g for DECT. Aortic attenuation was highest at reduced iodine dose DECT 50 keV (570 ± 105 Hounsfield units [HU]) compared to 77 keV (239 ± 40 HU) or to standard iodine dose SECT 120 kVp (356 ± 69 HU) (P < 0.05). Image noise was greatest at 50 keV compared to 77 keV and 120 kVp (P < 0.05) but was similar between 77 keV and 120 kVp (P > 0.05). SNR and CNR were the same at 50 keV and 120 kVp (P > 0.05). Mean vascular enhancement scores were all above 3.0 (good, typical enhancement). Volume CT dose index was 11.7 mGy for DECT and 11.8 mGy for SECT (P = 0.37).

CONCLUSIONS

DECT aortography with 50% reduced iodine reconstructed at 50 keV resulted in significantly greater aortic attenuation, good subjective vascular enhancement, and comparable SNR and CNR compared to standard iodine dose SECT. DECT image noise at 77 keV was similar to SECT at 120 kVp.

Dynamic computed tomographic determination of scan delay for use in performing cardiac angiography in clinically normal dogs

OBJECTIVE

To determine the scan delay for use in performing cardiac CT angiography in dogs.

ANIMALS

4 clinically normal adult Beagles.

PROCEDURES

In a crossover study, 12 formulations of iohexol solutions differing in iodine dose (300, 400, and 800 mg/kg) and concentration (undiluted and diluted 1:1, 1:2, and 1:3 with saline [0.9% NaCl] solution) were administered IV to each dog. Dynamic CT angiography was performed to evaluate enhancement characteristics of each formulation, with the region of interest set over the aorta. Time-attenuation curves (TACs) were obtained and analyzed.

RESULTS

Peak arc-type TACs were obtained after administration of all undiluted formulations. Curve shape changed from peak arc type to plateau type as the total volume of the contrast solution (ie, dilution) increased. Prolonged peaks characteristic of plateau-type TACs suggested that a sufficient period of homogeneous attenuation could be achieved for CT scanning with administration of higher iohexol dilutions (1:2 or 1:3) containing higher iodine doses (400 or 800 mg/kg). In particular, attenuation values for plateau-type TACs remained between 200 and 300 Hounsfield units for > 16 seconds after the plateau endpoint was reached for 1:2 and 1:3 dilutions containing an iodine dose of 800 mg/kg. Scan delays of 13 to 17 seconds were computed for those 2 formulations.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that for clinically normal dogs, a scan delay of 13 to 17 seconds could be used to perform cardiac CT angiography with iohexol solutions containing an iodine dose of 800 mg/kg at dilutions of 1:2 or 1:3.

Pulmonary Artery Imaging in Patients with Chronic Thromboembolic Pulmonary Hypertension: Comparison of Cone-Beam CT and 64-Row Multidetector CT

PURPOSE

To compare the depiction of pulmonary arteries in pulmonary arterial catheter-based contrast-enhanced cone-beam CT with peripheral intravenous contrast-enhanced multidetector CT in patients with suspected chronic thromboembolic pulmonary hypertension.

MATERIAL AND METHODS

In 20 patients (15 men and 5 women, 63.4 y ± 16.3), cone-beam CT using a catheter placed in the main pulmonary artery and 64-row multidetector CT using an appropriate venous access were performed. Contrast enhancement was measured in the main pulmonary artery, the right and left pulmonary arteries, and the left atrium. The amount of peripheral vessel conspicuity adjacent to the pleural surface (distance from vessel-to pleura) was measured. Two readers (R1, R2) independently evaluated the pulmonary arteries for image quality and pathologic findings in both modalities.

RESULTS

Contrast density was higher in the main pulmonary artery and right and left pulmonary arteries (P < .002) and lower in the left atrium (P = .001) on cone-beam CT. The smallest distance between clearly delineated vessels and the pleura was significantly lower on cone-beam CT images (P < .0001). Interobserver agreement was good for cone-beam CT (κ = 0.79) and multidetector CT (κ = 0.78), whereas intermodality agreement was moderate (R1, κ = 0.60; R2, κ = 0.59). Both readers detected more weblike stenoses with cone-beam CT (76; 22%) compared with multidetector CT (25; 7%).

CONCLUSIONS

Cone-beam CT shows improved contrast between pulmonary arteries and the left atrium and allows a more detailed depiction of the pulmonary arteries.

Low contrast medium and radiation dose for hepatic computed tomography perfusion of rabbit VX2 tumor

AIM: To evaluate the feasibility of low contrast medium and radiation dose for hepatic computed tomography (CT) perfusion of rabbit VX2 tumor.

METHODS: Eleven rabbits with hepatic VX2 tumor underwent perfusion CT scanning with a 24-h interval between a conventional tube potential (120 kVp) protocol with 350 mgI/mL contrast medium and filtered back projection, and a low tube potential (80 kVp) protocol with 270 mgI/mL contrast medium with iterative reconstruction. Correlation and agreement among perfusion parameters acquired by the conventional and low dose protocols were assessed for the viable tumor component as well as whole tumor. Image noise and tumor-to-liver contrast to noise ratio during arterial and portal venous phases were evaluated.

RESULTS: A 38% reduction in contrast medium dose (360.1 ± 13.3 mgI/kg vs 583.5 ± 21.5 mgI/kg, P < 0.001) and a 73% decrease in radiation dose (1898.5 mGy • cm vs 6951.8 mGy • cm) were observed. Interestingly, there was a strong positive correlation in hepatic arterial perfusion (r = 0.907, P < 0.001; r = 0.879, P < 0.001), hepatic portal perfusion (r = 0.819, P = 0.002; r = 0.831, P = 0.002), and hepatic blood flow (r = 0.945, P < 0.001; r = 0.930, P < 0.001) as well as a moderate correlation in hepatic perfusion index (r = 0.736, P = 0.01; r = 0.636, P = 0.035) between the low dose protocol with iterative reconstruction and the conventional protocol for the viable tumor component and the whole tumor. These two imaging protocols provided a moderate but acceptable agreement for perfusion parameters and similar tumor-to-liver CNR during arterial and portal venous phases (5.63 ± 2.38 vs 6.16 ± 2.60, P = 0.814; 4.60 ± 1.27 vs 5.11 ± 1.74, P = 0.587).

CONCLUSION: Compared with the conventional protocol, low contrast medium and radiation dose with iterative reconstruction has no significant influence on hepatic perfusion parameters for rabbits VX2 tumor.

Low kV settings CT angiography (CTA) with low dose contrast medium volume protocol in the assessment of thoracic and abdominal aorta disease: a feasibility study

OBJECTIVE

To assess the diagnostic quality of low dose (100 kV) CT angiography (CTA), by using ultra-low contrast medium volume (30 ml), for thoracic and abdominal aorta evaluation.

METHODS

67 patients with thoracic or abdominal vascular disease underwent multidetector CT study using a 256 slice scanner, with low dose radiation protocol (automated tube current modulation, 100 kV) and low contrast medium volume (30 ml; 4 ml s(-1)). Density measurements were performed on ascending, arch, descending thoracic aorta, anonymous branch, abdominal aorta, and renal and common iliac arteries. Radiation dose exposure [dose-length product (DLP)] was calculated. A control group of 35 patients with thoracic or abdominal vascular disease were evaluated with standard CTA protocol (automated tube current modulation, 120 kV; contrast medium, 80 ml).

RESULTS

In all patients, we correctly visualized and evaluated main branches of the thoracic and abdominal aorta. No difference in density measurements was achieved between low tube voltage protocol (mean attenuation value of thoracic aorta, 304 HU; abdominal, 343 HU; renal arteries, 331 HU) and control group (mean attenuation value of thoracic aorta, 320 HU; abdominal, 339; renal arteries, 303 HU). Radiation dose exposure in low tube voltage protocol was significantly different between thoracic and abdominal low tube voltage studies (490 and 324 DLP, respectively) and the control group (thoracic DLP, 1032; abdomen, DLP 1078).

CONCLUSION

Low-tube-voltage protocol may provide a diagnostic performance comparable with that of the standard protocol, decreasing radiation dose exposure and contrast material volume amount.

ADVANCES IN KNOWLEDGE

Low-tube-voltage-setting protocol combined with ultra-low contrast agent volume (30 ml), by using new multidetector-row CT scanners, represents a feasible diagnostic tool to significantly reduce the radiation dose delivered to patients and to preserve renal function, while also maintaining adequate diagnostic quality images in assessment of aorta.

Evaluations of extracellular pH within in vivo tumors using acidoCEST MRI

PURPOSE

A practical, noninvasive method is needed to measure the extracellular pH (pHe) within in vivo tumors to longitudinally monitor tumor acidosis. We have optimized a biomedical imaging method, termed acidoCEST MRI, to provide noninvasive assessments of tumor pHe in preclinical models of mammary carcinoma.

METHODS

A CEST-FISP MRI method was optimized to detect the chemical exchange saturation transfer (CEST) of two amide protons of a clinically approved CT contrast agent, iopromide. The ratio of the two CEST effects was used to measure pH. Routes of administration of iopromide were evaluated to ensure sufficient delivery of the agent to the tumor. The optimized acidoCEST MRI method was then used to evaluate the change in tumor pHe following alkalinizing bicarbonate treatment.

RESULTS

The acidoCEST MRI protocol measured pH between 6.2 and 7.2 pH units. Greater delivery of iopromide was shown to improve the precision of the measurement of tumor pHe, but the agent did not influence the tumor pHe. AcidoCEST MRI was used to longitudinally monitor the effect of bicarbonate treatment on the pHe of tumors and bladders.

CONCLUSION

This study demonstrates that an optimized acidoCEST MRI method is a practical, noninvasive method for assessing changes in tumor acidosis.

Iontophoretic transdermal sampling of iohexol as a non-invasive tool to assess glomerular filtration rate

PURPOSE

To explore the potential of non-invasive reverse iontophoresis transdermal extraction of iohexol as a marker of glomerular filtration rate.

METHODS

A series of in vitro experiments were undertaken to establish the feasibility of iohexol reverse iontophoresis and to determine the optimal conditions for the approach. Subsequently, a pilot study in paediatric patients was performed to provide proof-of-concept.

RESULTS

The iontophoretic extraction fluxes of iohexol in vitro were proportional to the marker subdermal concentration and the reverse iontophoretic technique was able to track changes dynamically in simulated pharmacokinetic profiles. Reverse iontophoresis sampling was well tolerated by the four paediatric participants. The deduced values of the iohexol terminal elimination rate constant from transdermal reverse iontophoresis sampling agreed with those estimated by conventional blood sampling.

CONCLUSIONS

Reverse iontophoretic transdermal extraction fluxes mirrored the subdermal concentration profiles of iohexol, a relatively large neutral marker of glomerular filtration both in vitro and in vivo. The efficiency of extraction in vivo was well predicted by the in vitro model used.

An evaluation of the use of oral contrast media in abdominopelvic CT

OBJECTIVES

To evaluate the diagnostic efficacy of different oral contrast media (OCM) for abdominopelvic CT examinations performed for follow-up general oncological indications. The objectives were to establish anatomical image quality criteria for abdominopelvic CT; use these criteria to evaluate and compare image quality using positive OCM, neutral OCM and no OCM; and evaluate possible benefits for the medical imaging department.

METHODS

Forty-six adult patients attending a follow-up abdominopelvic CT for general oncological indications and who had a previous abdominopelvic CT with positive OCM (n = 46) were recruited and prospectively placed into either the water (n = 25) or no OCM (n = 21) group. Three radiologists performed absolute visual grading analysis (VGA) to assess image quality by grading the fulfilment of 24 anatomical image quality criteria.

RESULTS

Visual grading characteristics (VGC) analysis of the data showed comparable image quality with regards to reproduction of abdominal structures, bowel discrimination, presence of artefacts, and visualization of the amount of intra-abdominal fat for the three OCM protocols.

CONCLUSION

All three OCM protocols provided similar image quality for follow-up abdominopelvic CT for general oncological indications.

KEY POINTS

• Positive oral contrast media are routinely used for abdominopelvic multidetector computed tomography • Experimental study comparing image quality using three different oral contrast materials • Three different oral contrast materials result in comparable CT image quality • Benefits for patients and medical imaging department.

Safety and tolerability of iopromide intravascular use: a pooled analysis of three non-interventional studies in 132,012 patients

BACKGROUND

Determining the safety of contrast agents is challenging. In the absence of large controlled clinical trials, non-interventional (post-marketing surveillance) studies provide an opportunity to clearly investigate the safety profile of contrast agents.

PURPOSE

To assess the safety profile of iopromide in contrast-enhanced X-ray in clinical practice, using pooled data from three non-interventional studies.

MATERIAL AND METHODS

All studies were international, multicenter, non-interventional studies examining iopromide tolerability in clinical practice. Patients received iopromide (iodine concentrations of 300 mg/mL or 370 mg/mL) via intravenous or intra-arterial administration according to the diagnostic indication and in compliance with the local package insert.

RESULTS

In total, 132,012 patients (37 countries, >1600 centers) were included. Overall, 3823 patients (2.49%) reported an adverse drug reaction (ADR) and 1983 patients (1.50%) reported an ADR without tolerance indicators (injection site warmth, feeling hot or injection site pain, of mild intensity only). This is a similar rate to other low osmolar contrast media. In most patients, ADRs were mild (n = 2632; 1.99% of all patients) and did not require any action (n = 2799; 2.12% of all patients). ADRs were more common among women (n = 1680 [2.8%]) than men (n = 1586 [2.2%]) and among younger patients (<18 years: n = 98 [3.2%]) than older patients (18-49 years: n = 1261 [3.5%]; 50-69 years: n = 1224 [2.2%]; ≥70 years: n = 362 [1.5%]). The most common ADRs were injection site warmth/feeling hot, nausea/vomiting, and dysguesia. Forty-five serious ADRs were reported in 19 patients. ADRs were more common in at-risk patients (5.00%) than in the overall population.

CONCLUSION

This pooled analysis confirms the well-established good safety profile of iopromide in clinical practice in Asian and European countries and the USA.

Use of electrical nerve stimulation to monitor lumbosacral epidural needle placement in cats

OBJECTIVE

To determine the minimal electrical threshold (MET) necessary to elicit muscle contraction of the pelvic limb or tail when an insulated needle is positioned outside (METout) and inside (METin) the lumbosacral epidural space in cats.

STUDY DESIGN

Prospective, blinded study.

ANIMALS

Twelve mixed-breed healthy adult cats, scheduled for a therapeutic procedure where lumbosacral epidural administration was indicated.

METHODS

Under general anesthesia, an insulated needle was advanced through tissues of the lumbosacral interspace until its tip was thought to be just dorsal to the interarcuate ligament. An increasing electrical current (0.1 ms, 2 Hz) was applied through the stimulating needle in order to determine the MET necessary to obtain a muscle contraction of the pelvic limb or tail (METout), and then 0.05 mL kg−1 of iohexol was injected. The needle was further advanced until its tip was thought to be in the epidural space. The MET was determined again (METin) and 0.2 mL kg−1 of iohexol was injected. The cats were maintained in sternal position. Contrast medium spread was determined through lateral radiographic projections.

RESULTS

The radiographic study confirmed the correct needle placement dorsal to the interarcuate ligament in all cats. When the needle was placed ventrally to the interarcuate ligament, iohexol was injected epidurally in ten and intrathecally in two cats. The METout and METin was 1.76 ± 0.34 mA and 0.34 ± 0.07 mA, respectively (p < 0.0001).

CONCLUSION AND CLINICAL RELEVANCE

Nerve stimulation can be employed as a tool to determine penetration of the interarcuate ligament but not the piercing of the dura mater at the lumbosacral space in cats.

Exposure to low- vs iso-osmolar contrast agents reduces NADPH-dependent reactive oxygen species generation in a cellular model of renal injury

Contrast-induced nephropathy represents the third cause of hospital-acquired acute renal failure. This study investigated the effects of low- vs iso-osmolar contrast medium (CM) exposure on NADPH-dependent reactive oxygen species (ROS) generation by tubular cells. X-ray attenuation of iohexol, iopamidol, and iodixanol was assessed at equimolar iodine concentrations and their effects on human renal proximal tubular cells (PTCs) were evaluated with equally attenuating solutions of each CM. Cytotoxicity, apoptosis, and necrosis were investigated by trypan blue exclusion, MTT assay, and annexin V/propidium iodide assay, respectively. ROS production was assessed by DCF assay, NADPH oxidase activity by the lucigenin-enhanced chemiluminescence method, and Nox4 expression by immunoblot. Yielding the same X-ray attenuation, CM cytotoxicity was assessed in PTCs at equimolar iodine concentrations. More necrosis was present after incubation with iohexol and iopamidol than after incubation with equal concentrations of iodixanol. Iohexol and iodixanol at low iodine concentrations induced less cytotoxicity than iopamidol. Moreover, both iohexol and iopamidol induced more apoptosis than iodixanol, with a dose-dependent effect. ROS generation was significantly higher with iopamidol and iohexol compared to iodixanol. NADPH oxidase activity and Nox4 protein expression significantly increased after exposure to iopamidol and iohexol, with a dose-dependent effect, compared with iodixanol. CM-induced Nox4 expression and activity depended upon Src activation. In conclusion, at angiographic concentrations, iodixanol induces fewer cytotoxic effects on cultured tubular cells than iohexol and iopamidol along with a lower induction of Nox4-dependent ROS generation. This enzyme may, thus, represent a potential therapeutic target to prevent iodinated CM-related oxidative stress.

Distribution pattern of sonographically guided iliopsoas injections: cadaveric investigation using coned beam computed tomography

OBJECTIVES

To investigate the distribution pattern of sonographically guided iliopsoas (IP) injections in an unembalmed cadaveric model.

METHODS

A single experienced operator completed 10 sonographically guided IP injections in 5 unembalmed cadaveric pelvic specimens (4 male and 1 female; ages 55-95 years; body mass indices, 15.5-27.5 kg/m(2)) using a previously described in-plane, lateral-to-medial approach short axis to the tendon. Each injection consisted of 7 mL of a 20% dilution of contrast material injected between the IP tendon and the acetabular rim using a 22-gauge, 87.5-mm (3½-in) needle. To facilitate interpretation of contrast patterns, 2 additional injections were performed on single hips: sonographically guided 14 mL contrast-latex IP injection and sonographically guided superficial IP "peritendinous" injection with 7 mL of contrast-latex. Immediately before and after each injection, fluoroscopic images were obtained with a fixed C-arm equipped with coned beam computed tomography. After each injection, radiographic images were evaluated by a board-certified, fellowship-trained musculoskeletal radiologist to determine injectate distribution. Specimens receiving contrast-latex injections were dissected 48 hours after injection to determine the anatomic location of the injectate.

RESULTS

Nine of 10 IP injections (90%) produced characteristic "U-shaped" flow patterns covering 50% to nearly 100% of the IP tendon circumference and resembling previously published IP bursograms. One injection was excluded because the majority of the latex was within the pectineus muscle, likely due to technical factors. Latex flowed an average of 5.3 cm (range, 0.3-7.9 cm) cephalad and 5.2 cm (range, 1.0-7.5 cm) caudad to the acetabular rim. The large-volume (14-mL) IP injection produced a similar flow pattern to the 7 mL injections, whereas the superficial peritendinous injection produced a contrast pattern consistent with intramuscular flow. Subsequent dissection confirmed bursal flow for the 14-mL injection, whereas the superficial peritendinous injection placed latex within the superficial portion of the IP muscle (ie, intramuscular).

CONCLUSIONS

Sonographically guided IP injections using an in-plane, lateral-to-medial technique place injectate into the IP bursa between the IP tendon and the acetabular rim. Within the limits of this cadaveric investigation, this sonographically guided 7-mL IP "bursa" injection may provide a minimum of 50% circumferential IP tendon coverage and approximately 5 cm of cephalad and caudad flow. There does not appear to be a peritendinous space deep to the IP tendon at the acetabular rim that is both outside the bursa and amenable to sonographically guided injection. Injections into the superficial aspect of the IP using 7-mL volumes may not deliver injectate deep to the IP tendon and therefore may represent a fundamentally different injection.

128-slice acceletated-pitch dual energy CT angiography of the head and neck: comparison of different low contrast medium volumes

BACKGROUND

Our study aims to evaluate the image quality and feasibility of 128-slice dual-energy CTA (DE-CTA) for supra-aortic arteries using reduced amounts of contrast medium (CM).

METHODS

A prospective study was performed in 54 patients receiving CTA of the head and neck with a 128-slice dual-source CT system. Patients were randomized into two groups with a volume of either 40 mL of CM (Group I) or 50 mL of CM (Group II). Arterial and venous enhancements were recorded for quantitative assessment. Qualitative assessments for images without bone removal (BR) were based on a) the visualization of the circle of Willis and b) streak artifacts due to residual CM in the subclavian or internal jugular veins ipsilateral to injection of CM. Qualitative assessment of dual-energy images using BR was based on the presence of bone remnants and vessel integrity. Quantitative data was compared using the Student t test. The χ(2) test was used for the qualitative measurements of streak artifacts in veins while the Mann-Whitney U test was used for the qualitative measurements of images with BR.

RESULTS

Arterial and venous attenuation was significantly higher in Group II (P=0.000). Image quality regarding the circle of Willis was excellent in both groups (3.90±0.30 for Group I and 4.00±0 for Group II) . Imaging of the internal jugular veins was scored higher in Group I (1.87±0.72) compared with Group II (1.48±0.51) (P=0.021). Within Group I using BR, mean scores for bone remnants did not differ significantly (P>0.05) but mean scores of vessel integrity (P<0.05) did.

CONCLUSIONS

Contrast-enhanced head and neck CTA is feasible using a scan protocol with low amounts of contrast medium (40 mL) on a 128-slice dual-energy CTA. The 40-mL protocol provides satisfactory image quality before and after dual-energy bone-removal post-processing.

Poly(iohexol) nanoparticles as contrast agents for in vivo X-ray computed tomography imaging

Biocompatible poly(iohexol) nanoparticles, prepared through cross-linking of iohexol and hexamethylene diisocyanate followed by coprecipitation of the resulting cross-linked polymer with mPEG-polylactide, were utilized as contrast agents for in vivo X-ray computed tomography (CT) imaging. Compared to conventional small-molecule contrast agents, poly(iohexol) nanoparticles exhibited substantially protracted retention within the tumor bed and a 36-fold increase in CT contrast 4 h post injection, which makes it possible to acquire CT images with improved diagnosis accuracy over a broad time frame without multiple administrations.

Recommended iodine dose for multiphasic contrast-enhanced mutidetector-row computed tomography imaging of liver for assessing hypervascular hepatocellular carcinoma: multicenter prospective study in 77 general hospitals in Japan

RATIONALE AND OBJECTIVES

To determine the recommended iodine dose of contrast material (CM) for hepatic arterial-dominant phase (HAP) and hepatic parenchymal phase (HPP) imaging to assess hypervascular hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

This was a prospective study including 348 patients with hypervascular HCC in 77 hospitals as a postmarketing surveillance to investigate the effects of body weight-tailored dose of CM (300 mgI/mL of iohexol) for hepatic multiphasic contrast-enhanced multidetector-row computed tomography imaging. Informed consent was obtained from all patients who were enrolled. The tumor-to-liver contrast (TLC) of HAP images was assessed qualitatively (QL-TLC) and quantitatively (QT-TLC [HU]; computed tomography [CT] value of tumor-CT value of hepatic parenchyma). Minimal and sufficient QT-TLC were defined as CT values corresponding to the median and 75% of QL-TLC assigned with "good," respectively. The recommended iodine dose was estimated by the relationship between iodine dose (mgI/kg) and QT-TLC.

RESULTS

There was a good correlation between QL-TLC and QT-TLC. The recommended iodine dose of CM for HAP imaging was considered to be in the range of 567-647 mgI/kg based on minimal (33.7 HU) and sufficient QT-TLC (40.9 HU). Meanwhile, the recommended dose of CM for HPP imaging was 572 mgI/kg as a dose that gives hepatic enhancement more than 50 HU during HPP imaging.

CONCLUSIONS

The recommended iodine dose of CM for HAP and HPP imaging may be different, being 567-647 mgI/kg and 572 mgI/kg, respectively, in assessing hypervascular HCC.

Visualisation of the rectoanal inhibitory reflex with a modified contrast enema in children with suspected Hirschsprung disease

BACKGROUND

Patients with Hirschsprung disease lack the normal rectoanal inhibitory reflex, which can be studied with anorectal manometry or US.

OBJECTIVE

To see whether the rectoanal inhibitory reflex could be visualised with a modified contrast enema, thereby increasing the diagnostic accuracy of the contrast enema and reducing the number of rectal biopsies.

MATERIALS AND METHODS

Fifty-nine boys and 42 girls (median age, 12 months) with suspected Hirschsprung disease were examined with a modified contrast enema, supplemented with two injections of cold, water-soluble contrast medium, to induce the reflex. Two paediatric radiologists evaluated the anonymised examinations in consensus. The contrast enema findings were correlated with the results of rectal biopsy or clinical follow-up.

RESULTS

Five boys and one girl (median age, 7.5 days) were diagnosed with Hirschsprung disease. The negative predictive value of the rectoanal inhibitory reflex was 100%. A contrast enema with signs of Hirschsprung disease in combination with an absent rectoanal inhibitory reflex had the specificity of 98% and sensitivity of 100% for Hirschsprung disease.

CONCLUSION

The modified contrast enema improves the radiological diagnosis of Hirschsprung disease. By demonstrating the rectoanal inhibitory reflex in children without Hirschsprung disease, we can reduce the proportion of unnecessary rectal biopsies.

A novel minimally invasive technique to create a rabbit VX2 lung tumor model for nano-sized image contrast and interventional studies

BACKGROUND

The rabbit VX2 lung cancer model is a large animal model useful for preclinical lung cancer imaging and interventional studies. However, previously reported models had issues in terms of invasiveness of tumor inoculation, control of tumor aggressiveness and incidence of complications.

PURPOSE

We aimed to develop a minimally invasive rabbit VX2 lung cancer model suitable for imaging and transbronchial interventional studies.

METHODS

New Zealand white rabbits and VX2 tumors were used in the study. An ultra-thin bronchoscope was inserted through a miniature laryngeal mask airway into the bronchus. Different numbers of VX2 tumor cells were selectively inoculated into the lung parenchyma or subcarinal mediastinum to create a uniform tumor with low incidence of complications. The model was characterized by CT, FDG-PET, and endobronchial ultrasound (EBUS). Liposomal dual-modality contrast agent was used to evaluate liposome drug delivery system in this model.

RESULTS

Both peripheral and mediastinal lung tumor models were created. The tumor making success rate was 75.8% (25/33) in the peripheral lung tumor model and 60% (3/5) in the mediastinal tumor model. The group of 1.0×10(6) of VX2 tumor cells inoculation showed a linear growth curve with less incidence of complications. Radial probe EBUS visualized the internal structure of the tumor and the size measurement correlated well with CT measurements (r(2) = 0.98). Over 7 days of continuous enhancement of the lung tumor by liposomal contrast in the lung tumor was confirmed both CT and fluorescence imaging.

CONCLUSION

Our minimally invasive bronchoscopic rabbit VX2 lung cancer model is an ideal platform for lung cancer imaging and preclinical bronchoscopic interventional studies.

[Bolus contrast-enhanced multislice spiral computed tomography of the chest: new possibilities in the diagnosis of lung diseases]

OBJECTIVE

To elaborate optimal programs for bolus contrast-enhanced multislice spiral computed tomography (MSCT) of the chest for different types of tomographic scanners and in some lung diseases.

MATERIAL AND METHODS

Contrast-enhanced MSCT findings were analyzed in 637 patients, 536 of whom presented with a focal pathological process in the lung and 101 had pulmonary emphysema.

RESULTS

There is evidence proving the expedience of using the contrast medium iopromide that has an optimal balance between the high concentration of iodine and its excellent tolerance due to low osmolarity and low viscosity.

CONCLUSION

Intravenous bolus contrast-enhancement using an automated injector can visualize chest organs in different phases of contrast enhancement, by significantly improving the quality of diagnosis and achieving 100% disease diagnosis comparable with its morphological diagnosis.