Presence Of Contrast Material Research Articles

CT Fluoroscopy-Guided Interlaminar Epidural Steroid Injections in the Cervical Spine: Rate of Nontarget Injection Into the Retrodural Space of Okada.

The purpose of this study was to assess the rate of inadvertent injection into the retrodural space of Okada during CT fluoroscopy-guided interlaminar epidural steroid injection in the cervical spine. Images from cases of cervical interlaminar epidural steroid injection under CT fluoroscopic guidance performed at a single institution between November 2009 and November 2015 were obtained and reviewed. For all cases, the following information was recorded: presence or absence of contrast material within the Okada space, cervical anatomic level at which the procedure was performed, laterality of approach, trainee presence, and years of proceduralist experience. Two-tailed chi-square tests were used to assess categoric variables, and t tests were performed to assess for continuous variables predictive of nontarget injection. A total of 974 CT fluoroscopy-guided cervical interlaminar epidural steroid injections were identified in 728 patients. The presence of contrast material in the retrodural space of Okada was identified in 2.9% of cases (28/974). All cases of inadvertent injection were identified and corrected intraprocedurally. The greatest rate of inadvertent injection (4.6% [18/389]) occurred at C5-6. No variables predictive of inadvertent injection into the Okada space were identified. There was a 0.4% (4/974) complication rate, and all complications were minor. We identified a 2.9% rate of unintended injection into the retrodural space of Okada during cervical interlaminar epidural steroid injection. If unrecognized, these nontarget injections can result in treatment failure in a subset of patients who undergo cervical interlaminar epidural steroid injection. Future study is warranted to assess the rate of inadvertent Okada injection under conventional fluoroscopy and to compare the rates of detection between the two imaging-guided modalities.

Comparison of ultrasound and fluoroscopic guidance for injection in CT arthrography and MR arthrography of the hip

ObjectiveTo evaluate the usefulness of ultrasound-guided versus fluoroscopy-guided injection in CT arthrography and MR arthrography. Material and methodsWe reviewed all CT arthrography and MR arthrography studies done at our center between October 1, 2014 and October 1, 2015. We analyzed 32 studies: 26 with fluoroscopic guidance and 6 with ultrasound guidance. We compared the two techniques on the following parameters: presence of sufficient contrast material in the joint, extravasation or injection of contrast material in the soft tissues (presence of contrast material in the psoas or other soft tissues), and intra-articular gas bubbles. We used SPSS V. 20 to compare the techniques with Pearson's chi-square tests. ResultsContrast material was observed in soft tissues in 56.3% of ultrasound-guided injections, making 6.3% of the procedures invalid for diagnostic purposes. Extravasation of contrast material was observed in 53.8% of fluoroscopy-guided procedures, making 3.8% invalid for diagnostic purposes. Intra-articular gas was observed in 21.9% of ultrasound-guided studies and in 38.5% of fluoroscopy-guided studies. None of the differences between techniques were statistically significant at p<0.05. ConclusionsOur study shows that ultrasound is as useful as fluoroscopy for injecting contrast material for CT arthroscopy and MR arthroscopy; ultrasound has the advantage of not using ionizing radiation.

Feasibility of Antegrade Contrast-enhanced US Nephrostograms to Evaluate Ureteral Patency.

Purpose To demonstrate the feasibility of contrast material-enhanced ulrasonographic (US) nephrostograms to assess ureteral patency after percutaneous nephrolithotomy (PCNL) in this proof-of-concept study. Materials and Methods For this HIPAA-compliant, institutional review board-approved prospective blinded pilot study, patients undergoing PCNL provided consent to undergo contrast-enhanced US and fluoroscopic nephrostograms on postoperative day 1. For contrast-enhanced US, 1.5 mL of Optison (GE Healthcare, Oslo, Norway) microbubble contrast agent solution (perflutren protein-type A microspheres) was injected via the nephrostomy tube. Unobstructed antegrade ureteral flow was defined by the presence of contrast material in the bladder. Contrast-enhanced US results were compared against those of fluoroscopic nephrostograms for concordance. Results Ten studies were performed in nine patients (four women, five men). Contrast-enhanced US demonstrated ureteral patency in eight studies and obstruction in two. One patient underwent two studies, one showing obstruction and the second showing patency. Concordance between US and fluoroscopic assessments of ureteral patency was evaluated by using a Clopper-Pearson exact binomial test. These results were perfectly concordant with fluoroscopic nephrostogram results, with a 95% confidence interval of 69.2% and 100%. No complications or adverse events related to contrast-enhanced US occurred. Conclusion Contrast-enhanced US nephrostograms are simple to perform and are capable of demonstrating both patency and obstruction of the ureter. The perfect concordance with fluoroscopic results across 10 studies demonstrated here is not sufficient to establish diagnostic accuracy of this technique, but motivates further, larger scale investigation. If subsequent larger studies confirm these preliminary results, contrast-enhanced US may provide a safer, more convenient way to evaluate ureteral patency than fluoroscopy. © RSNA, 2016 Online supplemental material is available for this article.

Comparación de las técnicas de inyección ecográfica y radioscópica en artro-TC y artro-RM de cadera

ObjectiveTo evaluate the usefulness of ultrasound-guided versus fluoroscopy-guided injection in CT arthrography and MR arthrography. Material and methodsWe reviewed all CT arthrography and MR arthrography studies done at our center between October 1, 2014 and October 1, 2015. We analyzed 32 studies: 26 with fluoroscopic guidance and 6 with ultrasound guidance. We compared the two techniques on the following parameters: presence of sufficient contrast material in the joint, extravasation or injection of contrast material in the soft tissues (presence of contrast material in the psoas or other soft tissues), and intra-articular gas bubbles. We used SPSS V. 20 to compare the techniques with Pearson's chi-square tests. ResultsContrast material was observed in soft tissues in 56.3% of ultrasound-guided injections, making 6.3% of the procedures invalid for diagnostic purposes. Extravasation of contrast material was observed in 53.8% of fluoroscopy-guided procedures, making 3.8% invalid for diagnostic purposes. Intra-articular gas was observed in 21.9% of ultrasound-guided studies and in 38.5% of fluoroscopy-guided studies. None of the differences between techniques were statistically significant at p<0.05. ConclusionsOur study shows that ultrasound is as useful as fluoroscopy for injecting contrast material for CT arthroscopy and MR arthroscopy; ultrasound has the advantage of not using ionizing radiation.

Effects of contrast materials in IMRT and VMAT of prostate using a commercial Monte Carlo algorithm.

Contrast materials help in contouring in radiotherapy. The primary aim of this study is to investigate the effects of contrast materials in bladder on the dosimetry during prostate intensity modulated radiation therapy and volumetric modulated arc therapy. The study also investigates the difference of the two dose calculation options namely 'dose to medium (Dm)' and 'dose to water (Dw)' in a commercial Monte Carlo based treatment planning system. Eight IMRT treatment plans were retrospectively studied which were used to treat high risk prostate cancer patients. The treatment plans generated in Monaco treatment planning system use seven coplanar beams and calculated 'Dm' as the clinical option. These plans were recalculated, keeping the segments, beam angle and monitor units the same, with different relative electron densities assigned to the structure 'bladder' to mimic the presence of contrast material. The same plans were recalculated using the 'Dw' option. Further, keeping the IMRT constraints and plan calculation properties the same, these plans were re-optimised with the delivery method changed to volumetric modulated arc therapy and calculated using both 'Dm' and 'Dw' options. For all the four scenarios, it was found that for the target volumes CTV and PTV, 'minimum dose' is the only endpoint studied having a significant difference with the presence of contrast material. For bladder, the endpoint V40Gy is affected. Any significant dosimetric effect is found only when the relative electron density of the contrast material is 1.2 or more. Also, the dosimetric difference is greater when 'Dm' option is used for calculation. For rectum, the dosimetry remains unaffected. Hence, contrast materials should be contoured and assigned appropriate relative electron densities during IMRT and VMAT treatment planning of prostate. Also, the difference in dose reported with the two dose calculation options (Dm and Dw) in the presence of contrast materials is significant.

Abstract 20510: Aortic Valve Calcium Score for Paravalvular Aortic Insufficiency (AVCS II) Study in Transapical Aortic Valve Implantation

Introduction: Transapical-aortic valve implantation (TA-AVI) has evolved into a routine procedure in selected elderly high-risk patients. However, more-than-mild paravalvular leaks remain a significant drawback of current TAVI systems. The aim was to study the impact of native aortic valve calcification on paravalvular leaks in cardiac contrast-enhanced computed tomography (CT). Methods: The degree and distribution of native valve calcification were quantified using an Aortic Valve Calcium Score (AVCS) for each cusp separately (3mensio Valves™ workstation, version 7.0, 3mensio Medical Imaging B.V., Netherlands). To exclude an artificial increase of the AVCS due to the presence of contrast material, we used a threshold for density [mean aortic density + 2*D] and volume [0, 3, 5, 25 and 50 mm 3 ] of calcification. AVCS was compared to the rate of paravalvular leaks, assessed intraoperatively by echocardiography and root angiography. Results: Eighty-eight consecutive patients prior to TA-AVI with preoperative CT aged 80.0 ± 5.7 years, 51.1 % female were included. Three prosthesis sizes were used for annular diameters up to 23 mm (n = 29), 26 mm (n = 45) and 29 mm (n = 14). Mean log. EuroSCORE was 24.6 ± 15.4 % and mean STS-Score was 8.4 ± 8.3 %. The mean AVCS in patients without paravalvular leaks (n = 42) was 606.4 ± 374.3; with mild paravalvular leaks (n = 39) was 761.2 ± 530.4; and with moderate paravalvular leaks (n = 5) was 792.4 ± 515.3 with the highest calcification in the non-coronary cusp. There was no significant association between the total AVCS and paravalvular leaks (χ 2 -statistic = 2.9; P = 0.13, 551 hounsfield units). The additional use of the volume-based threshold did not lead to an increase of the association between the AVCS and paravalvular leakages. Paravalvular leaks were significantly associated with the degree (r Spearman = 0.34; χ 2 -statistic = 10.0; P = 0.02) and location of eccentric calcified plaques. Conclusions: Quantification of aortic valve calcification in contrast enhanced computed tomography shows only a weak correlation with paravalvular leakage and is therefore not reliable as a predictor, respectively. The degree of eccentric cusp calcification was significantly associated with the occurrence and location of paravalvular leaks.

MR cisternography: is it useful in the diagnosis of normal pressure hydrocephalus and the selection of “good shunt responders”?

The aim of this study was to evaluate the efficiency of MR cisternography (MRC) in the diagnosis of idiopathic normal-pressure hydrocephalus (INPH) and in the prediction of the response to shunt treatment. Thirty-six patients with the diagnosis of "probable INPH" were included in the study group and 15 asymptomatic age-matched individuals were included in the control group. Pre-contrast T1-weighted (T1W) imaging was followed by intrathecal administration of 1 ml gadopentetate dimeglumine. Post-contrast T1W images were taken at the 12th, 24th and 48th hours. The presence of contrast material in the lateral ventricles for more than 24 hours was accepted as a positive diagnosis of INPH. Data from both groups were compared statistically. Statistical significance was accepted for P < 0.05. All of the INPH patients had remaining contrast material in their lateral ventricles at the 12th and 24th hours, while only 28 (78%) patients had contrast material remaining at the 48th hour after MRC. Only 3 (20%) of the control cases had remaining contrast material in their lateral ventricles at the 24th hour. No contrast material was present in the control cases at the 48th hour. The contrast material was found to be significantly more prevalent in the INPH patients at the 24th and the 48th hours compared with the control cases (P < 0.001). Shunt placement was performed in 14 INPH patients, and eight improved after shunt placement. All patients (100%) who improved after shunt placement had remaining contrast material in their lateral ventricles at the 24th and at the 48th hours. The sensitivity and specificity of MRC in the prediction of the response to shunt treatment were 100% and 17%, respectively. MRC does not use ionizing radiation and is generally a useful procedure to diagnose NPH and to predict a positive response to shunt treatment; thus, we recommend MRC after routine MRI in patients with the presumed diagnosis of NPH.

Computerized Tomography Findings in Pediatric Renal Trauma—Indications for Early Intervention?

We sought to determine if initial computerized tomography findings in pediatric patients suffering blunt renal trauma with urinary extravasation were predictive of the need for operative intervention. A total of 17 patients with grade IV blunt renal trauma and urinary extravasation were identified between 2000 and 2007. Each computerized tomogram was reviewed to determine location, size and number of sites of extravasation, as well as the presence of contrast material in the ipsilateral ureter. These findings were compared with subsequent ureteral stent placement, percutaneous urinoma drainage, angiographic embolization and nephrectomy. A total of 13 male and 4 female patients (mean age 11.1 years) were identified. Eight patients (47%) required delayed intervention. Conservative treatment was unsuccessful in patients with absence of contrast material in the ipsilateral ureter and large separation of the upper and lower poles, and in 3 of 5 patients with multiple areas of extravasation and 4 of 5 patients with transfusion requirements. The diameter (9.6 vs 9.7 mm, p = 0.96) and location of extravasation were not predictive of subsequent intervention. Two of 5 patients with posterior extravasation required intervention, both for symptomatic urinoma. Early ureteral stent placement may be considered for pediatric patients with blunt renal trauma who demonstrate absence of contrast material in the ipsilateral ureter, since clinical indications for stent placement will likely develop. Further study may show if wide separation of the upper and lower poles, multiple areas of extravasation and transfusion requirement are factors in the decision for early intervention.

Polyp Size at CT Colonography after Electronic Subtraction Cleansing in an Anthropomorphic Colon Phantom

To evaluate the effect of various bowel contrast material concentrations and subtraction software on size measurements of well-defined polyp lesions in a colon phantom at CT colonography. Repeated scanning and a precise reference standard required the use of a colon phantom in which 21 polyps were randomly distributed. Two readers who had each reviewed computed tomographic (CT) colonographic images from more than 100 cases evaluated polyp size on images obtained when the phantom was partially filled with varying concentrations of contrast material, scanned by using CT colonography, and subjected to electronic subtraction cleansing. The single largest dimension was recorded for each reader for a randomized series of polyps. These measurements were compared with a reference standard that was based on a combination of the manufacturer's polyp size specifications and the subsequent verification of these sizes by an independent consensus panel. Six weeks after initial observations, readers evaluated images of the phantom scanned without the presence of contrast material. Polyp size estimations for the two readers for each series were compared with the reference standard to obtain a mean absolute measurement error for each reader for each series. Data for each reader were compared by using a nonparametric Kruskal-Wallis analysis of variance test. A pair-wise comparison of the experimental and control series was then performed by using the Dunn post hoc test. Contrast material dilutions resulting in an average attenuation of less than 500 HU resulted in complete subtraction and the absence of streak artifacts. There was no statistically significant difference between the average measurement error for contrast attenuations between 300 and 500 HU when compared with that of control. Streak artifact was noticeable for the highest dilution (mean, 840 HU). No statistically significant differences were observed for series in which cleansing software was used in the absence of bowel contrast material. The combination of electronic cleansing and bowel contrast enhancement in the range of 300-500 HU results in no substantial change in readers' estimations of polyp size at CT colonography.

Type II lumbar endoleaks: Hemodynamic differentiation by contrast-enhanced ultrasound scanning and influence on aneurysm enlargement after endovascular aneurysm repair

The objective of this study was to differentiate type II lumbar endoleaks on the basis of dynamic features identified by contrast-enhanced ultrasound scanning (CUS) and to evaluate the role of this differentiation in detecting abdominal aortic aneurysm (AAA) enlargement > or =1 mL/mo. Eighteen male patients (mean age, 71.8 years) with type II lumbar endoleak suspected at CUS underwent computed tomography angiography (CTA) and digital subtraction angiography (DSA). On CTA, AAA volumes and endoleak visualization and volume were assessed. At CUS, performed after a bolus of 1.5 to 2.4 mL of a second generation blood pool contrast agent, the following parameters were evaluated: presence of contrast material within the aneurysmal sac (endoleak), delay of endoleak detection (wash-in) and disappearance (washout) from the beginning of contrast injection, visualization of inflow and outflow vessels, and presence of cavity filling. Statistical analysis was performed regarding endoleak features at CUS, endoleak detection at CTA, and rate of AAA enlargement. DSA confirmed all the endoleaks. Mean +/- standard deviation wash-in and washout times were 121.9 +/- 132.6 and 337.2 +/- 193.7 seconds, respectively; a significant relation was observed between these two parameters (P < .01, analysis of variance). By Youden plots, endoleaks were classified as hyperdynamic when wash-in was <100 seconds (n = 10, 55.5%) and/or washout was <520 seconds (n = 13, 72.2%). A slower washout was associated with nonvisualized outflow (66.7%) and/or inflow arteries (66.7%) ( P < .05). Eight endoleaks (44.4%) were missed at CTA; it occurred in hypodynamic endoleaks, absence of detectable inflow or outflow vessels, and absence of cavity filling at CUS (P < .05). Overall mean AAA volume increase rate was 1.1 +/- 1.7 mL/mo. By multiple logistic regression model, the washout time > or = 520 seconds was the only independent predictor of AAA volume increase > or = 1 mL/mo (8 patients, 44.4%). Type II lumbar endoleaks show different hemodynamic features at CUS, which might influence the rate of aneurysm enlargement, addressing the need for treatment.

Single-detector helical CT in PET-CT: assessment of image quality.

CT in positron emission tomography (PET)-CT imaging is often performed as a single scan from the base of the skull to the groin, potentially resulting in degradation of the quality of CT scans depending on the position of the patient's arms and mode of breathing and the use and timing of IV contrast injection. The aim of our study was to assess the impact of artifacts on the diagnostic quality of CT scans using a single-detector helical CT scanner in PET-CT imaging. Two radiologists retrospectively evaluated the diagnostic image quality of CT scans obtained with PET-CT in 81 patients with lymphoma. The severity of the artifacts related to the position of the patient's arms beside the body, the influence of breathing motion, and the presence of contrast material in the upper thoracic veins were ranked using a 4-point scale. Performing CT with the patient's arms positioned beside the body resulted in streak artifacts, predominantly in the upper abdomen, that were graded as mild in 22%, moderate in 40%, and severe in 38% of the scans. A patient's weight significantly correlated with the degree of severity of the artifacts (p < 0.05). Shallow breathing by the patient during scanning caused blurring and double-imaging, again predominantly in the upper abdomen, that were graded as mild in 23%, moderate in 49%, or severe in 28% of the scans. In 84% of the CT scans obtained with IV contrast material, the image quality of the upper thoracic region was moderately (27%) or severely (57%) degraded by streak artifacts from highly concentrated contrast material in the upper thoracic veins. The use of a single-detector CT scanner in whole-body PET-CT decreases the image quality of CT scans because of streak artifacts that occur predominantly in scans of the upper abdomen. Scanning with the patient's arms raised eliminates the streak artifacts in scans of the abdominal region. With the new generation of PET-CT devices equipped with MDCT scanners, breathing motion artifacts can be expected to be eliminated if protocols for breath-hold CT are applied. Reversing the direction of CT scanning allows one to avoid imaging the thoracic region at a time when undiluted IV contrast material is still present in the upper thoracic veins.

The value of hysterosalpingography before reversal of sterilization procedures involving the fallopian tubes.

Knowledge of the length of the uterine end of the fallopian tube and the presence of tubal adhesions and fistulas is important when surgical reversal is undertaken in patients who have had tubal ligation. We retrospectively studied hysterosalpingograms in 127 such patients to determine their value in providing this information. The ligation was performed by using the Pomeroy technique in 57 patients. Sixty-one patients had bipolar electrocautery, six had Falope rings inserted, and three had Hulka clips applied. In all cases, the uterine ends of the tube were visualized to a point of obstruction. The sites of occlusion after Pomeroy ligation were midtubal (46%), cornual (16%), proximal ampullary (16%), proximal isthmic (14%), and intramural (8%). After the electrocautery procedure, the sites of occlusion were proximal isthmic (45%), intramural (20%), midtubal (19%), cornual (15%), and proximal ampullary (1%). When Falope rings and Hulka clips were used, the most frequent site of occlusion was midtubal (50%). Tubal adhesions, consistent with successful occlusion, were detected in 16 patients on the basis of a small confined area of extravasation of contrast material at the site of ligation. Tuboperitoneal fistulas, identified by the presence of contrast material spilled from the uterine end of the tube into the peritoneal cavity, were detected in five patients. Our results show that hysterosalpingography is a useful technique for determining the status of the uterine end of the fallopian tube after ligation when reversal of ligation is planned.