[en] Implantation of subcutaneous port systems is routinely performed in patients requiring repeated long-term infusion therapy. Ultrasound- and fluoroscopy-guided implantation under local anesthesia is broadly established in interventional radiology and has decreased the rate of complications compared to the surgical approach. In addition, interventional radiology offers the unique possibility of simultaneous management of venous occlusion. We present a technique for recanalization of central venous occlusion and angioplasty combined with port placement in a single intervention which we performed in two patients. Surgical port placement was impossible owing to occlusion of the superior vena cava following placement of a cardiac pacemaker and occlusion of multiple central veins due to paraneoplastic coagulopathy, respectively. In both cases the affected vessel segments were dilated with balloon catheters and the port systems were placed thereafter. After successful dilatation, the venous access was secured with a 25-cm-long, 8-Fr introducer sheath, a subcutaneous pocket prepared, and the port catheter tunneled to the venipuncture site. The port catheter was introduced through the sheath with the proximal end connected to a 5-Fr catheter. This catheter was pulled through the tunnel in order to preserve the tunnel and, at the same time, allow safe removal of the long sheath over the wire. The port system functioned well in both cases. The combination of recanalization and port placement in a single intervention is a straightforward alternative for patients with central venous occlusion that can only be offered by interventional radiology.

[en] The purpose of this study was to assess the accuracy of automated nodal quantification in a phantom. MDCT of a phantom with 17 synthetic lymph nodes of different sizes (diameter 6.0-30.0 mm) was performed at varying tube currents, reconstruction kernels and slice thicknesses. RECIST diameter and volume were measured using an automated software tool. Results were compared with the reference diameter and volume by calculating the absolute percentage error (APE). Degree of agreement between software and reference measurements was evaluated by computing corresponding concordance correlation coefficients (CCC). Under varying tube currents the mean APE (CCC) varied between 5.18% and 10.12% (0.95-0.99) for RECIST diameter and between 7.22% and 16.21% (0.94-1.00) for the volume. At different reconstruction kernels the mean APE values ranged between 7.20% and 7.55% (0.99) (RECIST) and between 8.96% and 14.42% (1.00) (volume). With different slice thicknesses the mean APE values differed from 5.81% to 9.20% (0.97-0.99) (RECIST) and from 8.16% to 22.66% (0.99-1.00) (volume). Regarding RECIST criteria and volume, automated evaluation of lymph nodes in a phantom demonstrated a high accuracy under varying MDCT parameters. (orig.)

[en] The purpose of this study was to evaluate the influence of different peripheral vein catheter sizes on the injection pressure, flow rate, injection duration, and intravascular contrast enhancement. A flow phantom with a low-pressure venous compartment and a high-pressure arterial compartment simulating physiological circulation parameters was used. High-iodine-concentration contrast medium (370 mg iodine/ml; Ultravist 370) was administered in the venous compartment through peripheral vein catheters of different sizes (14, 16, 18, 20, 22, and 24 G) using a double-head power injector with a pressure limit of 325 psi. The flow rate was set to 5 ml/s, with a total iodine load of 36 g for all protocols. Serial CT scans at the level of the pulmonary artery and the ascending and the descending aorta replica were obtained. The true injection flow rate, injection pressure, injection duration, true contrast material volume, and pressure in the phantom during and after injection were continuously monitored. Time enhancement curves were computed and both pulmonary and aortic peak time and peak enhancement were determined. Using peripheral vein catheters with sizes of 14-20 G, flow rates of approximately 5 ml/s were obtained. During injection through a 22-G catheter the pressure limit was reached and the flow rate was decreased, with a consecutive decreased pulmonary and aortic contrast enhancement compared to the 14- to 20-G catheters. Injection through a 24-G peripheral vein catheter was not possible because of disconnection of the canula due to the high flow rate and pressure. In summary, intravenous catheters with sizes of 14-20 G are suitable for CT angiography using an injection protocol with a high flow rate and a high-iodine-concentration contrast medium.

[en] Osteoid osteoma is a painful benign tumour, which is commonly treated by radiofrequency ablation (RFA). The goal of this study is to assess the value of contrast-enhanced magnetic resonance imaging (MRI) for predicting clinical success after RFA of osteoid osteoma. Twenty consecutive patients (14 male, 6 female; mean age 23.3 ± 13.4 years) suffering from osteoid osteoma underwent unenhanced and contrast-enhanced T1-weighted MRI the day after RFA. Post-interventional contrast enhancement of the nidus was analyzed by comparing signal-to-noise ratios (SNR) of the nidus before and after contrast administration. The SNR between pre- and post-contrast scans was computed. There were no significant differences in SNR between pre- and post-contrast scans in the area of ablation (P = 0.1583), while the SNR exceeded one in four patients, indicating residual contrast enhancement. In three of these patients clinical symptoms recurred, requiring re-ablation, while one patient remained free from symptoms during follow-up. In patients with a pre- and post-contrast SNR of ≤1.18 no local recurrence was observed. Contrast enhancement on T1-weighted MRI imaging seems to be predictive of clinically unsuccessful RFA in osteoid osteoma. Patients with a SNR increase of ≥20% after contrast administration might be considered for re-ablation to avoid symptomatic tumour recurrence.

[en] To compare intra-individual contrast enhancement in multi-detector-row computed tomography (MDCT) using contrast media (CM) containing 300, 370 and 400 mg iodine per ml (mgI/ml). Six pigs underwent repeated chest MDCT using three different CM (iopromide 300, iopromide 370, iomeprol 400). An identical iodine delivery (IDR) rate of 1.5 gI/s and a constant total iodine dose of 300 mg/kg body weight were used. Dynamic CT were acquired at the level of the pulmonary artery, and the ascending and descending aorta. After the time enhancement curves were computed, the pulmonary and aortic peak enhancement, time to peak and plateau time above 300 HU were calculated. Intra-individual peak contrast enhancement was significantly higher for the 300 mgI/ml contrast medium compared with the 370 and 400 mgI/ml media: pulmonary trunk 595 HU vs 516 HU (p = 0.0093) vs 472HU (p = 0.0005), and aorta 505 HU vs 454 HU (p = 0.0008) vs 439 HU (p = 0.0001), respectively. Comparison of time to peaks showed no significant difference. Plateau times were significantly longer for the 300 mgI/ml than for the 370 and 400 mgI/ml CM at all anatomical sites. Given normalised IDR and total iodine burden, the use of CM with a standard concentration with 300 mg iodine/ml provides improved contrast enhancement compared with highly concentrated CM in the chest. (orig.)

[en] Completely implantable access ports for high pressure contrast media injection have been in use in clinical routine for a relatively short time. The purpose of our study was to compare a high pressure port system with a standard port system with regard to implantation and complications. In 94 oncological patients a completely implantable access port was implanted. Patients (n = 49) planned for oncological follow-up computed tomography (CT) received a high pressure port system. Other patients (n = 45) received a standard port system. Intrainterventional pain perception, postinterventional catheter tip migration and complications were analyzed. No major periinterventional complications occurred. Intrainterventional pain perception was not significantly different between the two groups. A significantly lower rate of tip migration was observed in the high pressure port group (P = 0.03) and when the port system was implanted on the right side (P = 0.03). In the standard port group catheter occlusion occurred in three patients (7%) and a catheter loop in one patient (2%) whereas no such complications occurred within the high pressure port group. Venous thrombosis was detected in one patient (2%) with a high pressure port; this did not occur in the standard port group. Implantation and use of a high pressure port device is safe and reliable: the complications are comparable to those of a standard port device. High pressure port systems should be considered for implantation, especially in patients who will require frequent CTs.

[en] Purpose: To determine the safest and most tolerable method for totally implantable access ports (TIAPs) particularly in regard to patient's pain perception and catheter-related complications. Materials and methods: From January 2007 to October 2008 a subcutaneous TIAP (Bardport, Bard Access System, UT, USA) was implanted in 138 oncological patients (60 male, 78 female; 18-85 years old; mean age of 56 ± 6 years) by experienced interventional radiologists. 94 TIAP were implanted through the subclavian vein (subclavian group) and 44 TIAP were implanted through the internal jugular vein (jugular group). Intrainterventional pain perception (visual analogue scale from 1 to 10), postinterventional catheter tip migration and radiation dose were documented for each method and implantation side and differences were compared with Wilcoxon t-test. For ordinal variables, comparison of two groups was performed with the Fisher's exact test. Results: No severe periinterventional complication occurred. Inadvertent arterial punctures without serious consequences were reported in one case for the jugular group versus four cases in the subclavian group. Significantly (p < 0.05) lower pain perception, radiation dose and tip migration rate were observed in the jugular group. Catheter occlusions occurred in 4% (n = 4) of the subclavian group versus 2% (n = 1) of the jugular group. The corresponding values for vein thrombosis and catheter dislocation were 3% (n = 3) and 1% (n = 1) in the subclavian group, while none of those complications occurred in the jugular group. Conclusion: Both techniques, the TIAP implantation via fluoroscopy-guided subclavian vein puncture and via ultrasound-guided jugular vein puncture, are feasible and safe. Regarding intrainterventional pain perception, radiation dose, postinterventional catheter tip position and port function the jugular vein puncture under ultrasound guidance seems to be advantageous.

[en] Purpose: To evaluate the influence of different saline chaser volumes and different saline chaser flow rates on the intravascular contrast enhancement in MDCT. Materials and methods: In a physiological flow phantom contrast medium (120 ml, 300 mgI/ml, Ultravist 300) was administered at a flow rate of 6 ml/s followed by different saline chaser volumes (0, 30, 60 and 90 ml) at the same injection rate or followed by a 30-ml saline chaser at different injection rates (2, 4, 6 and 8 ml/s). Serial CT-scans at a level covering the pulmonary artery, the ascending and the descending aorta replica were obtained. Time-enhancement curves were computed and both pulmonary and aortic peak enhancement and peak time were determined. Results: Compared to contrast medium injection without a saline chaser the pushing with a saline chaser (30, 60, and 90 ml) resulted in a statistically significant increased pulmonary peak enhancement (all p = 0.008) and prolonged peak time (p = 0.032, p = 0.024 and p = 0.008, respectively). Highest aortic peak enhancement values were detected for a saline chaser volume of 30 ml. A saline chaser flow rate of 8 ml/s resulted in the highest pulmonary peak enhancement values compared to flow rates of 2, 4 and 6 ml/s (all p = 0.008). Aortic peak enhancement showed the highest values for a flow rate of 6 ml/s. Conclusion: A saline chaser volume of 30 ml and an injection rate of 6 ml/s are sufficient to best improve vascular contrast enhancement in the pulmonary artery and the aorta in MDCT.