Power injection of contrast media using central venous catheters: feasibility, safety, and efficacy

Risk Factors for Contrast Media Extravasation in Intravenous Contrast-Enhanced Computed Tomography: An Observational Cohort Study

RATIONALE AND OBJECTIVES

To identify the risk factors for contrast media (CM) extravasation and provide effective guidance for reducing its incidence.

MATERIALS AND METHODS

We observed adult inpatients (n = 38 281) who underwent intravenous contrast-enhanced computed tomography between January 1, 2018, and December 31, 2022. Risk factors for CM extravasation were evaluated using univariate and multivariate logistic regression.

RESULTS

Among the 38 281 inpatients who underwent enhanced computed tomography angiography, 3885 received peripherally inserted central venous catheters (PICCs) and 34 396 received peripheral short catheters. In 3885 cases of PICCs, no CM extravasation occurred, but in five cases, ordinary PICCs that are unable to withstand high pressure were mistakenly used; three of those patients experienced catheter rupture, and eventually, all five patients underwent unplanned extubation. Among 34 396 cases of peripheral short catheters, 224 (0.65%) had CM extravasation. Female sex (odds ratio [OR]=1.541, 95% confidence interval [CI]: 1.111-2.137), diabetes (OR=2.265, 95% CI: 1.549-3.314), venous thrombosis (OR=2.157, 95% CI: 1.039-4.478), multi-site angiography (OR=9.757, CI: 6.803-13.994), and injection rate ≥ 3 mL/s (OR=6.073, 95% CI: 4.349-8.481) were independent risk factors for CM extravasation. Due to peripheral vascular protection measures in patients with malignant tumor, there was a low incidence of CM extravasation (OR=0.394, 95% CI: 0.272-0.570).

CONCLUSION

Main risk factors for CM extravasation are female, diabetes, venous thrombosis, multi-site angiography, and injection rate ≥ 3 mL/s. However, patients with malignant tumor have a low incidence of CM extravasation.

CLINICAL IMPACT

Analysis of these risk factors can help reduce the incidence of CM extravasation.

Practical use of the central venous access port for contrast-enhanced CT: comparison with peripheral intravenous access regarding enhancement and safety

AIM

To evaluate the efficacy of using the central venous (CV) port compared with peripheral intravenous access for contrast-material injection for contrast enhancement during the portal venous phase.

MATERIALS AND METHODS

Patients were divided into three groups: CV delay, CV routine, and peripheral access (PA) groups. Patients in the CV delay group underwent injection in the arm-down position with an additional delay, while those in the CV routine and PA groups underwent injections with the routine injection protocol for portal venous phase imaging. Contrast enhancement was evaluated by measuring the mean radiodensity (Hounsfield units) values for the aortic arch, abdominal aorta, inferior vena cava, portal vein, and spleen. The peak injection pressure was recorded and compared among the three groups.

RESULTS

No complications related to power injection were observed during 119 contrast-material injections performed using the CV port device. The CV delay group showed significantly lower radiodensity values than the PA group (165.7 ± 20.1 versus 181 ± 19 HU [p<0.01] for the portal vein); however, no significant differences in mean radiodensity values were observed between the CV routine and PA groups (p>0.05). The median peak injection pressure was 73.5, 67, and 47 psi in the CV delay, CV routine, and PA groups, respectively (p<0.01).

CONCLUSION

The CV port can be used for safe contrast-material injection while maintaining contrast enhancement on portal venous phase comparable to that achieved with peripheral intravenous access.

Development of a method to measure regional perfusion of the lung in anesthetized ponies using computed tomography angiography and the maximum slope model

OBJECTIVE

To develop a method based on CT angiography and the maximum slope model (MSM) to measure regional lung perfusion in anesthetized ponies.

ANIMALS

6 ponies.

PROCEDURES

Anesthetized ponies were positioned in dorsal recumbency in the CT gantry. Contrast was injected, and the lungs were imaged while ponies were breathing spontaneously and while they were mechanically ventilated. Two observers delineated regions of interest in aerated and atelectatic lung, and perfusion in those regions was calculated with the MSM. Measurements obtained with a computerized method were compared with manual measurements, and computerized measurements were compared with previously reported measurements obtained with microspheres.

RESULTS

Perfusion measurements obtained with the MSM were similar to previously reported values obtained with the microsphere method. While ponies were spontaneously breathing, mean ± SD perfusion for aerated and atelectatic lung regions were 4.0 ± 1.9 and 5.0 ± 1.2 mL/min/g of lung tissue, respectively. During mechanical ventilation, values were 4.6 ± 1.2 and 2.7 ± 0.7 mL/min/g of lung tissue at end expiration and 4.1 ± 0.5 and 2.7 ± 0.6 mL/min/g of lung tissue at peak inspiration. Intraobserver agreement was acceptable, but interobserver agreement was lower. Computerized measurements compared well with manual measurements.

CLINICAL RELEVANCE

Findings showed that CT angiography and the MSM could be used to measure regional lung perfusion in dorsally recumbent anesthetized ponies. Measurements are repeatable, suggesting that the method could be used to determine efficacy of therapeutic interventions to improve ventilation-perfusion matching and for other studies for which measurement of regional lung perfusion is necessary.

Optimizing Identification of Power Injectable Ports on the Scout Images for Multidetector Computed Tomography Procedures

OBJECTIVE

The objective of this study was to assess the impact of tube voltage and image display on the identification of power ports features on anterior-posterior scout images to inform optimal workflow for multidetector computed tomography (MDCT) examinations.

MATERIALS AND METHODS

Four ports, representing variable material composition (titanium/silicone), shapes, and computed tomography (CT) markings, were imaged on an adult anthropomorphic chest phantom using a dual-source MDCT at variable peak tube voltages (80, 100, 120, 150, and Sn150 kVp). Images were reviewed at variable image display setting by 5 blinded readers to assess port features of material composition, shape, and text markings as well as overall preferred image quality.

RESULTS

Material composition was correctly identified for all ports by all readers across all kilovoltage-peak settings. The identification by shape was more reliable than CT markers for all but one of the ports. CT marker identification was up to 80% for titanium ports at window level settings optimized for metal (window width, 200; window center, -150) and at a soft tissue setting (window width, 400; window center, 40) for silicone ports. Interreader agreement for best image quality per kilovoltage-peak setting was moderate to substantial for 3 ports (k = 0.5-0.62) but only fair for 1 port (k = 0.27). The highest overall rank for image quality was given unanimously to Sn150 kVp for imaging titanium ports and 100 kVp for silicone ports.

CONCLUSIONS

Power port identification on MDCT scout images can be optimized with modification of MDCT scout acquisition and display settings based on the main port material.

Improved Computed Tomography Contrast Injection Rates Through Implantable Chest Power Ports

OBJECTIVE

The aim of this study was to optimize chest port contrast injections using stepwise improvements.

METHODS

Ex vivo injections were tested. Two hundred scans using power port injections were then evaluated.

RESULTS

The highest flow rate was achieved using a 19G access needle, larger diameter tubing, and warmed contrast.The mean injection rates in baseline and postimprovement groups were 2.7 ± 0.4 and 4.8 ± 0.4 mL/s, respectively (P < .0001).

CONCLUSION

Component optimization of the port apparatus can maximize contrast flow rates.

Optimization of Pediatric Body CT Angiography: What Radiologists Need to Know

OBJECTIVE. Pediatric CT angiography (CTA) presents unique challenges compared with adult CTA. Because of the ionizing radiation exposure, CTA should be used judiciously in children. The pearls offered here are observations gleaned from the authors' experience in the use of pediatric CTA. We also present some potential follies to be avoided. CONCLUSION. Understanding the underlying principles and paying meticulous attention to detail can substantially optimize dose and improve the diagnostic quality of pediatric CTA.

Unusual intravascular complication of right internal jugular vein catheter piercing the SVC into the pericardium: Case report

Iatrogenic superior vena cava pericardial fistula caused by central venous catheterization is rare but can lead to life-threatening condition. Despite the potential risk of pericardial effusion causing pericardial tamponade, a conservative watch and wait management strategy can be safely adopted if such procedural complication is encountered. Herein, we present a case of an incidental finding of a central venous catheter perforating the wall of the superior vena cava into the pericardium, which probably occurred during injection of intravenous contrast agent on computed tomography pulmonary angiogram study.  

Power contrast injections through a totally implantable venous power port: A retrospective multicenter study

Objectives

To evaluate the feasibility and safety of power injection of contrast media through totally implantable venous power ports during computed tomography scans in oncologic patients.

Methods

The study population consisted of 417 patients who underwent computed tomography scan through a totally implantable venous power port. Clinical data were examined. Logistic regression analysis was used to assess the associations between clinical covariables and computed tomography scan failure.

Results

Successful computed tomography scans were achieved in 534 of 540 examinations (98.9%). Logistic regression analysis showed that contrast media above a 350 concentration was significantly associated with computed tomography scan failure (95% confidence interval: 1.01–1.13, p = 0.012). No major complications were noted.

Conclusions

Power injection of contrast media through a totally implantable venous power port for computed tomography examination is feasible and safe. This procedure provides an acceptable alternative in oncologic patients with inadequate peripheral intravenous access when computed tomography examination with contrast enhancement is needed.

Hydrothorax Due to Extravasation of Intravenous Contrast after Power Injection through Right Subclavian Catheter

We report a case of hydrothorax after receiving intravenous (IV) contrast material by power injector through right subclavian central venous catheter (CVC) line. A 38-year-old woman presented to the local emergency department with hypotension after a pedestrian accident. After resuscitation, CVC was inserted into her right subclavian vein and fluid was administered well before computed tomography (CT) enhancement. Contrast-enhanced CT scan showed a large amount of extravasation of contrast material and fluid collection in the thoracic and pericardial cavities which was not shown in non-enhanced CT scan. During operation, vascular perforation was found in right subclavian vein. This case highlights that emergency physicians must keep in mind the possibility of vessel injury after CVC insertion and contrast material is preferably injected via peripheral IV access.

Systematic review of the safety and efficacy of contrast injection via venous catheters for contrast-enhanced computed tomography

•

In ICU patients, contrast injection via central venous catheters is a safe alternative to peripheral injection.

•

Implementing a safety protocol before power injection via central venous catheters is advisable.

•

The quality of scans varies and remains not sufficiently investigated in scans with higher flow rates.

Objective

To examine the safety and efficacy of contrast injection through a central venous catheter (CVC) for contrast-enhanced computed tomography (CECT).

Methods

A systematic literature search was performed using PubMed. Studies were deemed eligible if they reported on the use of CVCs for contrast administration. Selected articles were assessed for their relevance and risk of bias. Articles with low relevance and high risk of bias or both were excluded. Data from included articles was extracted.

Results

Seven studies reported on the use of CVCs for contrast administration. Catheter rupture did not occur in any study. The incidence of dislocation ranged from 2.2-15.4%. Quality of scans was described in three studies, with less contrast enhancement of pulmonary arteries and the thoracic aorta in two studies, and average or above average quality in one study. Four other studies used higher flowrates, but did not report quality of scans.

Conclusion

Contrast injection via CVCs can be performed safely for CECT when using a strict protocol. Quality of scans depended on multiple factors like flow rate, indication of the scan, and cardiac output of the patient. In each patient, an individual evaluation whether to use the CVC as access for contrast media should be made, while bolus tracking may be mandatory in most cases.

Bursting pressure of triple-lumen central venous catheters under static and dynamic loads

INTRODUCTION

Central venous catheter (CVC) access is commonplace in intensive care units. Patients undergoing computed tomographic angiography require injection of contrast at high flow rates (4.5 mL/s), often CVC access is not used due to safety concerns. The CVC might rupture at high flow rates, resulting in CVC fragmentation and embolization or contrast extravasation.The objective of this study is to determine the pressure required to burst a CVC under static load and compare this to the pressure generated by injection of contrast at high flow rates (dynamic load) through the distal (16-g) lumen of a triple-lumen CVC.

METHODS

We gathered 16-cm long triple-lumen CVCs (n = 14) from patients with an average dwell time of 5.2 days (±2.7 days). Half the CVCs (n = 7) were subjected to static testing, where the distal lumen was occluded with the guidewire and super glue at the distal end of the catheter. The CVC was then placed into a 10-cm deep water bath at 37°C to simulate in vivo conditions and water was injected until catheter rupture. Dynamic pressure testing was done with the remaining catheters, with radio-contrast injected through the unoccluded distal lumen at flow rates of 4.5 mL/s, then 7 mL/s. Pressures were recorded throughout injection.

RESULTS

During static testing, 6/7 CVCs burst at the distal lumen where the glue was applied, the remaining CVC burst proximal to the hub. PSI at burst during static testing was 184.2 PSI (95% confidence interval [CI] 174.3-194.1 PSI). During dynamic testing the mean peak pressures at 7 mL/s was 81.1 PSI (95% CI 73-89.2 PSI). At 4.5 mL/s the mean peak pressure was 47.9 PSI (95% CI 42.9-52.9 PSI).

CONCLUSIONS

No CVCs failed under dynamic loading with injection of contrast at flow rates (4.5 and 7 mL/s) high enough to support computed tomographic angiography. This suggests 16-cm triple-lumen CVCs can be used safely.

Complications after implantation of subcutaneous central venous ports (PowerPortⓇ)

BACKGROUND

The aim of our study was revised as follows: to clarify the postoperative complications of multifunctional central venous ports and the risk factors for such complications to promote the safe use of the PowerPort system in the hospital.

METHODS

The study group comprised 132 patients in whom implantable central venous access ports (PowerPort^Ⓡ) were placed in our hospital from March 2014 through December 2015. The approach used for port placement was the subclavian vein in 43 patients (33%), the internal jugular vein in 87 patients (66%), and the femoral vein in 2 patients (1%).

RESULTS

Postoperative complications occurred in 8 patients (6%). The catheter was removed because of infection in 4 patients and catheter kinking in 1 patient. Port extravasation occurred in 3 patients. No patient had catheter pinch-off. The mean operation time was 74 min (range, 32 to 171). No patients had intraoperative bleeding or pneumothorax. Benign disease was a risk factor for postoperative complications (p = 0.009).

CONCLUSION

PowerPort is a multifunctional port. Benign disease was a risk factor for postoperative complications. Because many types of subcutaneously implanted ports are used in our hospital, we had to inform the hospital staff about the functions of PowerPort.

Power-injectable ports: safety during placement, therapeutic use, and contrast administration during computed tomography procedures

PURPOSE

To determine the safety of power-injectable ports during placement, therapeutic use, and administration of intravenous contrast material using automated mechanical injectors.

METHODS

This retrospective, single institution study examined all patients undergoing placement of a power-injectable port between May 1, 2006 and June 30, 2010, with follow-up data collected through October 31, 2010. Electronic records and PACS were searched for patient demographics, placement indication, device placed, placement site, attending operator, and complications. The number of CECT scans performed for patients with indwelling ports, rate of port access for such studies, and contrast extravasation or device failure events during power injection of contrast were recorded and compared to the results of all other methods of venous access for CECT scans.

RESULTS

In total, 313 ports were placed in 307 patients. Device dwell time ranged from 3 to 1506 days with a mean of 577. A total of 20 (6.5%) complications were identified during the study period, all of which were late. There was no statistically significant difference in complication rates between five attending operators. Patients with ports underwent 676 CECT scans during which the port was injected 142 times (20.9%). Neither extravasation nor device failure occurred during any scan, yielding no statistically significant difference when compared to the results of other venous access methods.

CONCLUSIONS

Power-injectable tunneled catheters with attached subcutaneous ports are safe with low rates of complication during placement and dwell time. Power injection of contrast through these ports may be as safe as power injection using other venous access methods.

Pressure injectors for radiologists: A review and what is new

Pressure Injectors are used routinely in diagnostic and interventional radiology. Advances in medical science and technology have made it is imperative for both diagnostic as well as interventional radiologists to have a thorough understanding of the various aspects of pressure injectors. Further, as many radiologists may not be fully conversant with injections into ports, central lines and PICCs, it is important to familiarize oneself with the same. It is also important to follow stringent operating protocols during the use of pressure injectors to prevent complications such as contrast extravastion, sepsis and air embolism. This article aims to update existing knowledge base in this respect.

[The administration of intravenous contrast agents: extravasations]

Local extravasation of intravenous contrast material is a relatively common complication that radiologists need to know about. The risk of extravasation is greater in children, the elderly, and unconscious patients. Although most extravasations are mild and do not lead to further complications, some can result in severe lesions that require surgery, especially in cases that are associated with compartment syndrome. We describe the main characteristics of extravasations, comment on different treatments, and propose a protocol for dealing with them.

Effectiveness of the new injection program 'saline test injection mode' for use power injector in pediatric contrast CT

To improve the safety of the use of a power injector for pediatric contrast CT, we newly developed a saline test injection mode for a power injector and investigated its usefulness. We used an injection route and investigated the relationship of the injection pressure to the injection rate of saline and the contrast medium. From this relationship, we investigated it was possible to estimate the change of pressure injection of contrast medium from the pressure change of saline injection. The correlation between the saline test injection pressure and the contrast medium injection pressure was investigated in 64 clinical cases. The detection rate of side effects from the saline test injection was investigated in 473 patients. Regarding the correlation between the injection rate and pressure for both saline and contrast, the pressure rose as the rate increased. The contrast medium injection pressure could be estimated from the correlation observed with saline. The clinical data were obtained had a relationship similar to that with phantom data. The detection rate of side effects from the saline test injection was 4.4% in the clinical cases. In these cases, examinations were completed by re-establishing an injection route or administering hypnotics. Our results suggest that contrast medium pressure can be estimated from a saline test injection, thus aiding in prediction of the risk of injection abnormality. Reactions to injections could be observed in the present study, facilitating the prevention of examination failure. Countermeasures can be taken against the cause of the reaction, and the examination can be performed after confirming the absence of a reaction to injection. Therefore, a saline test injection may be useful in pediatric contrast CT.

Totally implantable venous power ports of the forearm and the chest: initial clinical experience with port devices approved for high-pressure injections

OBJECTIVES

To evaluate the technical success, clinical outcome and safety of percutaneously placed totally implantable venous power ports (TIVPPs) approved for high-pressure injections, and to analyse their value for arterial phase CT scans.

METHODS

Retrospectively, we identified 204 patients who underwent TIVPP implantation in the forearm (n=152) or chest (n=52) between November 2009 and May 2011. Implantation via an upper arm (forearm port, FP) or subclavian vein (chest port, CP) was performed under sonographic and fluoroscopic guidance. Complications were evaluated following the standards of the Society of Interventional Radiology. Power injections via TIVPPs were analysed, focusing on adequate functioning and catheter's tip location after injection. Feasibility of automatic bolus triggering, peak injection pressure and arterial phase aortic enhancement were evaluated and compared with 50 patients who had had power injections via classic peripheral cannulas.

RESULTS

Technical success was 100%. Procedure-related complications were not observed. Catheter-related thrombosis was diagnosed in 15 of 152 FPs (9.9%, 0.02/100 catheter days) and in 1 of 52 CPs (1.9%, 0.002/100 catheter days) (p<0.05). Infectious complications were diagnosed in 9 of 152 FPs (5.9%, 0.014/100 catheter days) and in 2 of 52 CPs (3.8%, 0.003/100 catheter days) (p>0.05). Arterial bolus triggering succeeded in all attempts; the mean injection pressure was 213.8 psi. Aortic enhancement did not significantly differ between injections via cannulas and TIVPPs (p>0.05).

CONCLUSIONS

TIVPPs can be implanted with high technical success rates, and are associated with low rates of complications if implanted with sonographic and fluoroscopic guidance. Power injections via TIVPPs are safe and result in satisfying arterial contrast. Conventional ports should be replaced by TIVPPs.

Safety and feasibility in highly concentrated contrast material power injections for CT-perfusion studies of the brain using central venous catheters

INTRODUCTION

CT perfusion studies play an important role in the early detection as well as in therapy monitoring of vasospasm after subarachnoid hemorrhage. High-flow injections via central venous catheters are not recommended but may sometimes be the only possibility to obtain high-quality images.

MATERIALS AND METHODS

We retrospectively analyzed our data for CT perfusions performed with power injection of contrast material with an iodine concentration of 400mg/ml via the distal 16G lumen of the Arrow three and five lumen central venous catheter with preset flow rates of 5ml/s.

RESULTS

104 examinations with central venous catheters were evaluated (67 with five lumen and 37 with three lumen). No complications were observed. Mean flow rates were 4.4±0.5ml/s using the three lumen catheter and 4.6±0.6ml/s using the five lumen catheter respectively. The mean injection pressure measured by the power injector was 200.7±17.5psi for the three lumen central venous catheter and 194.5±6.5psi for the five lumen catheter, respectively.

CONCLUSION

Following a strict safety protocol there were no complications associated with power injections of contrast material containing 400mg iodine/ml with preset flow rates up to 5ml/s via the distal 16G lumen of the Arrow multi-lumen central venous catheter. However, since power-injections are off-label use with Arrow central venous catheters, this procedure cannot be recommended until potential safety hazards have been ruled out by the manufacturer.

Gavecelt Consensus Statement on the Correct use of Totally Implantable Venous Access Devices for Diagnostic Radiology Procedures

The use of totally implantable venous access devices in radiology may be associated with complications such as occlusion of the system (because of the high density of some contrast), infection (if the port is not handled in aseptic conditions, using proper barrier protections), and mechanical complications due to the high-pressure administration of contrast by automatic injectors (so-called power injector), including extravasation of contrast media into the soft tissues, subintimal venous or myocardial injection, or serious damage to the device itself (breakage of the external connections, dislocation of the non-coring needle, or breakage of the catheter).

The last problem – i.e., the damage of the device from a power injection – is not an unjustified fear, but a reality. A warning by the US Food and Drug Administration of July 2004 reports around 250 complications of this kind, referring to both port and central venous catheters and peripherally inserted central catheter systems, which occurred over a period of several years; in all cases, the damage occurred during the injection of contrast material by means of power injectors for computed tomography or magnetic resonance imaging procedures.

Though the risk associated with the use of ports in radiodiagnostics is thus clear, it has been suggested that administration of the contrast material via the port may have some advantage in terms of image quality, increased comfort for the patient, and maybe more accurate reproducibility of the patient's own follow-up exams. This contention needs to be supported by evidence.

Also, since many cancer patients who need frequent computed tomography studies already have totally implantable systems, it would seem reasonable to try to define how and when such systems may safely be used.

The purpose of this consensus statement is to define recommendations based on the best available evidence, for the safe use of implantable ports in radiodiagnostics.

Clinical benefit of power-injectable port systems: a prospective observational study

OBJECTIVE

To prospectively evaluate the clinical benefit of a central venous port system, which is approved for contrast media injection during contrast enhanced computed tomography.

MATERIALS AND METHODS

At a university teaching hospital, 98 patients (59 female, 39 male; median age 61.7 years; range 23-83) had a power-injectable central venous port catheter system implanted. All implantations were performed under ultrasonographic and fluoroscopic guidance by interventional radiologists. Procedure related immediate (up to 24 h after implantation), early (<30 days after implantation) and late complications were documented. The frequency of port system use for contrast enhanced computed tomography scans was also considered. Any port capsule migration was assessed indirectly by determining the catheter tip position. The intended follow-up period was 180 days.

RESULTS

An overall complication rate of 0.69 for 1,000 catheter days in 78 evaluated ports was recorded (12 ports affected, 15.4%). During the observational period, 40 of 104 contrast enhanced computed tomography scans were performed utilizing the port for contrast media administration (38.5%). 30 catheter tip retractions of more than 3 cm were observed in 82 patients (36.6%). Overall, tip dislocations were statistically more frequent in the female subgroup.

CONCLUSION

The complication rate found in this study is comparable to those, which have been published for standard port systems. The utilization of the device for contrast media injection during contrast enhanced computed tomography scans should be increased. Finally, the port capsule has to be carefully positioned and fixed to prevent migration.

The use of central venous catheters for intravenous contrast injection for CT examinations

The use of intravenous (i.v.) contrast media in CT examinations is often of great value in improving diagnostic accuracy. The preferable route of administration is via a peripheral i.v. cannula, with powered injectors allowing reliable delivery of rapid flow rates. However, many patients with a pre-existing central venous access device may have difficult peripheral access and there is a temptation to use the central device for delivery of contrast media. This review summarises the available evidence for the safe and effective use of these devices to assist the radiologist in balancing the relative risks and benefits of their use for contrast medium injection.

Feasibility of power contrast injections and bolus triggering during CT scans in oncologic patients with totally implantable venous access ports of the forearm

BACKGROUND

Conventional totally implantable venous access ports (TIVAPs) are not approved for power contrast injections but often remain the only venous access site in oncologic patients. Therefore, these devices can play an important role if patients with a TIVAP are scheduled for a contrast-enhanced computed tomography (ceCT) as vascular access may become more difficult during the course of chemotherapy.

PURPOSE

To evaluate the feasibility and safety of power injections in conventional TIVAPs in the forearm and to analyze the feasibility of bolus triggering during CT scans.

MATERIAL AND METHODS

In this retrospective study we analyzed 177 power injections in 141 patients with TIVAPs in the forearm. Between October 2008 and March 2010 all patients underwent power injections (1.5 mL/s, 150 psi) via the TIVAP for ceCT because conventional vascular access via a peripheral vein had failed. Adequate functioning and catheter's tip location after injection were evaluated. Peak injection pressure and attenuation levels of aorta, liver and spleen were analyzed and compared with results of 50 patients who were injected via classical peripheral cannulas (3 mL/s, 300 psi). Feasibility of automatic scan initiation was evaluated. In vitro the port was stressed with 5 mL/s (300 psi).

RESULTS

One TIVAP showed tip dislocation with catheter rupture. Three (2.1%) devices were explanted owing to assumed infection within 4 weeks after the injection. Mean injection pressure was 121.9 +/-24.1 psi. Triggering with automatic scan initiation succeeded in 13/44 (29.6%) scans. Injection via classical cannulas resulted in significantly higher enhancement (p < 0.05). In vitro the port system tolerated flow rates of up to 5 mL/s, injection pressures of up to 338 psi.

CONCLUSION

Power injection is a safe alternative for patients with TIVAPs in the forearm if classic vascular access ultimately fails. Triggering was successful in one-third of the attempts. Image quality in the arterial phase scan may be hampered. In vitro results suggest that the device tolerates even higher flow rates.

Intravenous contrast medium administration and scan timing at CT: considerations and approaches

The continuing advances in computed tomographic (CT) technology in the past decades have provided ongoing opportunities to improve CT image quality and clinical practice and discover new clinical CT imaging applications. New CT technology, however, has introduced new challenges in clinical radiology practice. One of the challenges is with intravenous contrast medium administration and scan timing. In this article, contrast medium pharmacokinetics and patient, contrast medium, and CT scanning factors associated with contrast enhancement and scan timing are presented and discussed. Published data from clinical studies of contrast medium and physiology are reviewed and interpreted. Computer simulation data are analyzed to provide an in-depth analysis of various factors associated with contrast enhancement and scan timing. On the basis of basic principles and analysis of the factors, clinical considerations and modifications to protocol design that are necessary to optimize contrast enhancement for common clinical CT applications are proposed.

Multidetector CT in children: current concepts and dose reduction strategies

The recent technical development of multidetector CT (MDCT) has contributed to a substantial increase in its diagnostic applications and accuracy in children. A major drawback of MDCT is the use of ionising radiation with the risk of inducing secondary cancer. Therefore, justification and optimisation of paediatric MDCT is of great importance in order to minimise these risks ("as low as reasonably achievable" principle). This review will focus on all technical and non-technical aspects relevant for paediatric MDCT optimisation and includes guidelines for radiation dose level-based CT protocols.

Aortic and hepatic contrast enhancement with abdominal 64-MDCT in pediatric patients: effect of body weight and iodine dose

OBJECTIVE

The purpose of our study was to retrospectively evaluate the effect of body weight and iodine dose on aortic and hepatic contrast enhancement in pediatric patients who underwent 64-MDCT of the abdomen and pelvis.

MATERIALS AND METHODS

Eighty-seven consecutive pediatric patients (50 boys and 37 girls; median age, 12.1 years; age range, 3.8-17.6 years) underwent standard abdominopelvic CT with a 64-MDCT scanner. Contrast medium (350 mg I/mL) was injected using a power injector at 2 mL/s followed by 15-20 mL of saline flush. According to our CT protocol, the volume of administered contrast medium was approximately 1.8 mL/kg of body weight, up to the maximum volume of 80 mL. CT scanning was initiated 60 seconds after the start of the contrast medium injection. CT attenuations of the aorta and liver were measured. For each patient, the injected contrast medium iodine mass per body weight index (g I/kg) (hereafter, iodine mass body index) was calculated. Linear regression analysis was performed between iodine mass body index and aortic and hepatic attenuations.

RESULTS

A wide range of patient weights (19-82 kg; mean, 48.6 kg [95% CI, 45.3-51.9 kg]) and contrast volumes (30-80 mL; median, 80.0 mL) were observed. The median attenuations were 149.0 HU (141.0-160.0 HU) for the aorta and 113.5 HU (109.5-120.0 HU) for the liver. Moderately high correlations were observed between iodine mass body index and aortic (Spearman's rho [r(s)] = 0.60 [0.45-0.72]; p < 0.001) and hepatic (r(s) = 0.60 [0.42-0.70]; p < 0.001) attenuations. The regression formulae for aortic attenuation (58.4 + 176.3 x iodine mass body index [p < 0.001]) and hepatic attenuation (58.7 + 108.5 x iodine mass body index [p < 0.001]) indicate that 1.5 and 1.8 mL/kg (350 mg I/mL) of contrast media are required to achieve 116 and 127 HU, respectively, of contrast-enhanced attenuation in the liver.

CONCLUSION

In our study, using abdominal 64-MDCT in pediatric patients, we found that approximately 1.5 mL/kg, or 0.525 g I/kg, yields 116 HU of hepatic attenuation or 50-55 HU of hepatic enhancement.

Choosing the right intravenous catheter

Infusion therapy in the home has been common for many years. The therapies appropriate for home infusion are numerous. The type of access device provided for the infusion is an important consideration for safe and effective care. That choice will take into consideration physician and patient preference and length of therapy. However, paramount to this decision are the characteristics of the infusate. It is essential to know the pH and osmolality of the drug as well as its potential vesicant properties. The nurse needs to act as the patient advocate to ensure that proper catheter selection is made. Patient teaching should be aimed at recognition of complications and immediate interventions to avoid problems.

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

RATIONALE AND OBJECTIVES

Computed tomographic angiography (CTA) requires the rapid injection of contrast media ideally through an 18-gauge intravenous line in the antecubital fossa. Patients with CVCs undergoing CTA, however, are typically injected at low rates for two reasons: the potential for catheter failure and because of the lack of manufacturer recommendations for high injection rates typically used during CTA. The purpose of the study is to measure the injection rate thresholds of CVC. The results suggest that CVC can be used at high injection rates that are now typically used with peripheral intravenous catheters during CTA.

MATERIALS AND METHODS

We used 16-cm-long catheters and 20-cm-long catheters in six groups (n = 5 for each catheter length). After the catheters were placed into a water bath, each group was injected at 5, 10, 15, 20, 25, and 30 ml/sec. New contrast, pressure tubing, and catheters were used for each test.

RESULTS

No catheter ruptures were encountered during the experiment, but there was one episode of power injector tubing rupture during the injection of a 16-cm catheter at an injection rate of 30 ml/sec.

CONCLUSION

No catheter failures were demonstrated in this study using injection rates well above those used in conventional CTA. Power injector tubing failure was demonstrated at an injection rate of 30 ml/sec, which generated mean pressures in the 16-cm catheters of 920 psi (tubing rating per manufacturer is 300 psi). This study demonstrated no catheter or injector tubing failure at injection rates of 5 to 25 ml/sec.

Safety and Efficacy of Pressure-Limited Power Injection of Iodinated Contrast Medium Through Central Lines in Children

OBJECTIVE

The purpose of this study was to evaluate the safety and efficacy of pressure-limited power injection of contrast medium through central lines for pediatric body CT examinations.

SUBJECTS AND METHODS

All patients with a central line who were referred for body CT examinations requiring an i.v. contrast agent were prospectively evaluated. The power injector was pressure limited to 25 psi (172 kPa). A standard dose of 2 mL/kg of iodinated contrast medium was power-injected through the central line. Two pediatric radiologists scored all examinations on a scale of 1 (poor) to 5 (superior) for adequacy of contrast enhancement. Regression and receiver operating characteristic analyses were performed.

RESULTS

The subjects were 63 patients 0.3-22 years old. Nineteen of these patients had tunneled lines, 18 had ports, and 26 had peripherally inserted central catheters. There were no complications related to power injection. Regression analysis showed a significant association between patient weight and contrast enhancement adequacy score (p < 0.001), higher patient weights yielding lower contrast enhancement adequacy scores. Receiver operating characteristic analysis showed a weight cutoff of 30 kg as a reasonable predictor of adequacy of contrast enhancement. For patients weighing 30 kg or more, the average contrast enhancement score was 2.4 (suboptimal to adequate). For patients weighing less than 30 kg, the average contrast enhancement score was 3.4 (adequate to good).

CONCLUSION

Pressure-limited power injection through central lines in children is safe. The contrast enhancement obtained with 25 psi (172 kPa) pressure-limited injection is acceptable only for patients who weigh less than 30 kg.

A Practical Approach to CT Angiography of the Neck and Brain

Computed tomography angiography (CTA) is a rapidly developing technology with great potential. This is particularly true for evaluating neurovascular disease. Clinical stroke because of atherosclerotic disease of the carotid and vertebral arteries is a common examination indication; areas of stenosis, and soft and calcified plaque along the entire vessel, not only at the carotid bifurcation, permit a full assessment of the patient's disease process. Other diseases including dissection, trauma, intracranial stenosis, thrombosis, and aneurysms can be readily diagnosed. Although duplex ultrasound may be a first line examination in many patients, both magnetic resonance angiography (MRA) and CTA offer distinct advantages over it. CTA and MRA are both highly accurate but CTA has several key advantages. CTA has been advanced by the development of improved multidetector CT (MDCT) and workstations that postprocess the data. Methods to obtain quality CTA images and to rapidly analyze the data for abnormalities are the subject of this chapter. In addition, evolving techniques in future CT scanners and workstations, and developing methods of vulnerable plaque and CT perfusion imaging are discussed.

Computed tomography angiography and computed tomography perfusion in ischemic stroke: A step-by-step approach to image acquisition and three-dimensional postprocessing

Recent technical advances in both image acquisition and postprocessing have enabled computed tomography angiography (CTA) with computed tomography perfusion to become front-line tools for acute stroke evaluation in many institutions. This article provides a step-by-step approach to utilizing these technologies, particularly in the rapid triage of appropriate stroke patients to reperfusion therapies. The specific contrast injection, image acquisition, and 3D postprocessing protocols for high-quality CTA, currently in use at our institution, are delineated. An important point of emphasis is how preliminary angiographic and cerebral perfusion observations can be made immediately at the scanner to expedite emergent therapy. Also explored is the manner in which a dedicated 3D lab can support a high clinical volume, including a large percentage of emergent studies. An accurate yet time-efficient approach for the neuroradiologist to integrate 3D interpretation with CTA source data review is offered. Several important imaging and interpretive pitfalls in stroke CTA are illustrated.

Central line pump infusion and large volume mediastinal contrast extravasation in CT

The use of multidetector CT scanners for CT angiography requires rapid injection of radiographic contrast media. Central venous catheters are now widely used for this purpose. Several complications may occur while using central venous access for rapid, large volume contrast injection such as catheter rupture and contrast extravasation. We describe a case in which inadvertent malposition of a central venous catheter led to a high volume extravasation of contrast in the mediastinum in a trauma patient.

Technique of Pediatric Thoracic CT Angiography

CT angiography is now an accepted application of contemporary multidetector row CT. Faster scanning, thinner slices, and improvement in intravenous contrast enhancement are benefits that have offered unique opportunities for pediatric thoracic angiographic evaluation, and often obviate routine angiography. Pediatric CT angiography can be challenging but adherence to a relatively straightforward step-by-step method, emphasizing patient preparation and technical familiarity, can result in excellent examinations even in the smallest infants and most complex clinical scenarios.

Pediatric thoracic CT angiography

One of the principal benefits of contemporary multidetector row computed tomography (MDCT) has been the ability to obtain high-quality data sets for evaluation of the cardiovascular system. The benefits of the greater number of detector rows and submillimeter image thicknesses were quickly recognized and are especially advantageous in children. For example, since imaging is performed so quickly, issues with motion are minimized. This is a substantial benefit of CTA compared with MR imaging, the traditional noninvasive cross sectional modality for pediatric cardiovascular imaging. This, together with faster and more powerful computers, including improved transfer and storage capabilities, offers improved depiction of the heart, great vessels, other vasculature, and adjacent intrathoracic structures in a fashion that is well accepted by clinical colleagues. In order to be successful, however, one must have an understanding of the technology and often unique technical considerations in infants and children. With this familiarity, excellent cardiovascular examinations can be performed even in the most challenging case.

Power Injection of Microcatheters: An In Vitro Comparison

PURPOSE

To determine the tolerance of 0.021-inch and 0.027-inch microcatheters to power injection in an in vitro flow model.

MATERIALS AND METHODS

Twenty-four microcatheters (0.021-inch, n = 13; 0.027-inch, n = 11) were injected with iothalamate meglumine through a flow model with use of a power injector and high-pressure tubing. Catheters used included Rebar (0.021-inch, n = 4; 0.027-inch, n = 4), Transit (0.021-inch, n = 3; 0.027-inch, n = 3), Renegade (0.021-inch, n = 4; 0.027-inch, n = 4), and Renegade STC-18 (0.021-inch, n = 2) models. Through the 0.021-inch microcatheters, 5-second injections were performed at an initial rate of 0.7 mL/sec. Injection rates were increased by 0.5 mL/sec and the process was repeated until the pressure approached 1,000 psi or catheter breakage occurred. A similar process was repeated for the 0.027-inch catheters starting at a rate of 3.4 mL/sec.

RESULTS

The 0.021-inch catheters were injected 303 times and the 0.027-inch catheters were injected 210 times. Three catheter failures occurred, with all breaks occurring at pressures greater than manufacturer recommendations. The 0.027-inch catheters as a group tolerated significantly higher injection rates than the 0.021-inch catheters. Of the 0.021-inch catheters, the STC-18 also provided superior maximum flow and volume compared with the Renegade catheter. The Rebar catheter tolerated significantly lower maximum injection rates and volumes than the other 0.027-inch catheters.

CONCLUSIONS

The majority of microcatheters can be power-injected in vitro at pressures far greater than manufacturer recommendations. When fractures occur, they are near the hub of the catheter. Significantly greater rates of injection are possible through 0.027-inch catheters.

Safety and Feasibility of Using a Central Venous Catheter for Rapid Contrast Injection Rates

OBJECTIVE

Our aim was to determine the safety and feasibility of using a central venous catheter for rapid contrast injections during CT.

MATERIALS AND METHODS

An in vitro experiment was performed using a 7-French Arrow-Howes multilumen central venous catheter. Each catheter port was tested by varying contrast agent flow rates delivered by a power injector. Contrast media specifications were kept similar to routine clinical practice. The in vivo experiment included 104 cases in which rapid contrast injections, 3.0-5.0 mL/sec, were delivered through a central venous catheter for dynamic CT examinations. Patient monitoring for early complications of contrast extravasation, cardiac arrhythmia, and allergic reactions was performed. Contrast injections were monitored for pressure limitation, automatic flow-rate adjustment, and catheter injury. Chart review was performed for delayed complications of mediastinal hematoma, infection, or catheter malfunction.

RESULTS

During the in vitro experiment, all desired flow rates, 3.0-9.9 mL/sec, could be delivered through the central venous catheter with no catheter injury. No immediate or early patient or catheter complications were observed during the in vivo experiment. Follow-up evaluation revealed that 18 blood cultures and one catheter culture were positive for bacterial growth. In a subgroup of 43 patients, five contrast injections were pressure-limited by the power injector, and only one had the flow rate automatically adjusted to 3.6 mL/sec from 4.0 mL/sec.

CONCLUSION

Rapid contrast injection rates, at 3.0-5.0 mL/sec, through the Arrow-Howes multilumen central venous catheter are feasible and safe in the clinical setting. However, a strict protocol should be followed to avoid possible serious complications.

Technical considerations in renal CT

CT is a robust, rapid means of evaluation for a wide spectrum of urologic disorders. The evaluation of renal trauma, urologic malignancy, urolithiasis, and vascular anatomy is well suited to CT techniques. Subtle adjustments in the technical parameters and timing of the study, however, can optimize the evaluation based on the clinical setting. As CT is more widely used, often repeatedly on an individual patient, radiation exposure must be minimized while still obtaining diagnostic image quality.