Jens Schneider

Fachhochschule Aachen, Aachen, North Rhine-Westphalia, Germany

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Publications (9)24.31 Total impact

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    ABSTRACT: To investigate radiation exposure in computed tomography (CT)-guided interventions, to establish reference levels for exposure, and to discuss strategies for dose reduction. We analyzed 1576 consecutive CT-guided procedures in 1284 patients performed over 4.5 years, including drainage placements; biopsies of different organs; radiofrequency and microwave ablations (RFA/MWA) of liver, bone, and lung tumors; pain blockages, and vertebroplasties. Data were analyzed with respect to scanner settings, overall radiation doses, and individual doses of planning CT series, CT intervention, and control CT series. Eighy-five percent of the total radiation dose was applied during the pre- and post-interventional CT series, leaving only 15% applied by the CT-guided intervention itself. Single slice acquisition was associated with lower doses than continuous CT-fluoroscopy (37mGycm vs. 153mGycm, p<0.001). The third quartile of radiation doses varied considerably for different interventions. The highest doses were observed in complex interventions like RFA/MWA of the liver, followed by vertebroplasty and RFA/MWA of the lung. This paper suggests preliminary reference levels for various intervention types and discusses strategies for dose reduction. A multicenter registry of radiation exposure including a broader spectrum of scanners and intervention types is needed to develop definitive reference levels.
    European journal of radiology 08/2013; · 2.65 Impact Factor
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    ABSTRACT: -Right heart catheterization (RHC) is the gold standard for assessment of pulmonary hemodynamics in patients with chronic thromboembolic pulmonary hypertension (CTEPH). So far, MRI has not been able to produce precise measurements of mPAP. The purpose of the study was to create a model for estimating mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR) in patients with CTEPH by high temporal resolution phase-contrast MR imaging (PC-MRI) and to correlate the results with simultaneously acquired, invasive catheter-based measurements (mPAP_sim) and with RHC measurements. -19 patients with CTEPH underwent RHC and - after digital subtraction angiography of the pulmonary arteries - subsequent PC-MRI at 1.5 T with simultaneous recording of mPAP. Velocity- and flow-time curves of PC-MRI were used to calculate absolute acceleration time (Ata), maximum of mean velocities (MV), volume of acceleration (AV), and maximum flow acceleration (dQ/dt). Based on these parameters, multiple linear regression analysis revealed maximum achievable model fit (B = 0.902) for the following linear combination equation to calculate mPAP (mPAP_cal): mPAP_cal = 69.446 - (0.521 • Ata) - (0.570 • MV) + (1.507 • AV) + (0.002 • dQ/dt). There was a statistically significant equivalence of mPAP_cal and mPAP_sim with a goodness of fit of 0.892. PVR was overestimated by calculated PVR based on PC-MRI in comparison with RHC-based measurements by a median of -112 dyn•s•cm(-5), the pairwise regression formula revealed a goodness of fit of 0.792. -PC-MRI derived parameters enable non-invasive assessment of pulmonary hemodynamics in patients with CTEPH.
    Circulation Cardiovascular Imaging 07/2013; · 5.80 Impact Factor
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    ABSTRACT: AIM: To determine local response, its predictors and survival and complication rates after DC-Bead™-TACE in patients with hepatocellular carcinoma (HCC). MATERIALS AND METHODS: DC-Beads™ are non-resorbable, polyvinyl-alcoholic hydrophilic microspheres. They release high amounts of chemotherapeutics directly into the tumour. Delivery is sustained over time, tumour feeders are embolised. We used beads from 100-300 to 500-700μm loaded with Doxorubicin (max. 150mg/4ml). Fifty patients (mean age: 68.5±8.8years) with HCC were analysed. DC-Bead™-TACE was performed once or repeated in two-month intervals. Imaging scans (CT or MRI) were done one-month following each procedure. To evaluate tumour response EASL and RECIST criteria was applied. If eligible, every patient received a non-selective TACE. RESULTS: 128 DC-Bead™ sessions were performed: 127 showed technical success, 120 successful stasis. Complications occurred in 7% (9/128): active bleeding into the tumour (n=1), liver failure (n=1), liver abscess (n=1) ascites (n=3), pleural effusion (n=1), false aneurysm (n=1) and hypoglycaemia (n=1). At imaging after the 1st, 2nd, 3rd and 4th-8th session, objective response (complete+partial) was 49%, 67%, 67% and 31%, progressive disease was seen in n=11/50. Baseline diameter and differentiation significantly impacted response. Median overall survival was 25.1months (95% [CI]: 18.3-31.9) with an estimated cumulative survival rate at one and two-to-four years of 66.7% and 45.7%, respectively. CONCLUSION: DC-Beads™ can be safely and effectively control HCC. Survival and response rates are encouraging, complications are low. Many factors are involved in response to treatment like liver function or child state.
    European journal of radiology 07/2012; · 2.65 Impact Factor
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    ABSTRACT: PURPOSE: To evaluate dose reduction in vascular angiographic procedures by using fluoroscopy capture instead of digital subtraction angiography frames for documentation. MATERIALS AND METHODS: A total of 764 consecutive vascular interventional procedures performed over a period of 1 year were retrospectively analyzed with respect to the fluoroscopy time and the resulting dose-area product (DAP), the DAP of the radiographic frames, and the overall DAP. RESULTS: A total of 70% of the total DAP was a result of the acquisition of radiographic frames, leaving only 30% being applied by fluoroscopy. CONCLUSIONS: Fluoroscopy capture should be used for documentation whenever possible. A registry of radiation exposure should not only comprise a sufficiently large number of interventions but also different intervention types to allow the development of interventional reference levels.
    Journal of vascular and interventional radiology: JVIR 07/2012; · 1.81 Impact Factor
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    ABSTRACT: To determine the most comprehensive imaging technique for the assessment of pulmonary arteries in patients with chronic thromboembolic pulmonary hypertension (CTEPH). 24 patients with CTEPH were examined by ECG-gated multi-detector CT angiography (MD-CTA), contrast-enhanced MR angiography (ce-MRA) and selective digital subtraction angiography (DSA) within 3 days. Two readers in consensus separately evaluated each imaging technique (48 main, 144 lobar and 449 segmental arteries) for typical changes like complete obstructions, vessel cut-offs, intimal irregularities, incorporated thrombus formations, and bands and webs. A joint interpretation of all three techniques served as a reference standard. Based on image quality, there was no non-diagnostic examination by either imaging technique. DSA did not sufficiently display 1 main, 3 lobar and 4 segmental arteries. The pulmonary trunk was not assessable by DSA. One patient showed thrombotic material at this level only by MD-CTA and MRA. Sensitivity and specificity of MD-CTA regarding CTEPH-related changes at the main/lobar and at the segmental levels were 100%/100% and 100%/99%, of ce-MRA 83.1%/98.6% and 87.7%/98.1%, and of DSA 65.7%/100% and 75.8%/100%, respectively. ECG-gated MD-CTA proved the most adequate technique for assessment of the pulmonary arteries in the diagnostic work-up of CTEPH patients. • A prospective single-centre study evaluated ECG-gated MDCTA, ce-MRA and DSA in CTEPH patients. • ECG-gated MD-CT angiography outperformed DSA and ce-MRA. • Right heart catheterisation should be reserved only for assessment of pulmonary haemodynamics.
    European Radiology 09/2011; 22(3):607-16. · 4.34 Impact Factor
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    ABSTRACT: To investigate the radiation exposure in non-vascular fluoroscopy guided interventions and to search strategies for dose reduction. Dose area product (DAP) of 638 consecutive non-vascular interventional procedures of one year were analyzed with respect to different types of interventions; gastrointestinal tract, biliary interventions, embolizations of tumors and hemorrhage. Data was analyzed with special focus on the fluoroscopy doses and frame doses. The third quartiles (Q3) of fluoroscopy dose values were defined in order to set a reference value for our in-hospital practice. Mean fluoroscopy times of gastrostomy, jejunostomy, right and left sided percutaneous biliary drainage, chemoembolization of the liver and embolization due to various hemorrhages were 5.9, 8.6, 13.5, 16.6, 17.4 and 25.2 min, respectively. The respective Q3 total DAP were 52.9, 73.3, 155.1, 308.4, 428.6 and 529.3 Gy*cm2. Overall, around 66% of the total DAP originated from the radiographic frames with only 34% of the total DAP applied by fluoroscopy (P<0.001). The investigators experience had no significant impact on the total DAP applied, most likely since there was no stratification to intervention-complexity. To establish Diagnostic Reference Levels (DRLs), there is a need to establish a registry of radiation dose data for the most commonly performed procedures. Documentation of interventional procedures by fluoroscopy "grabbing" has the potential to considerably reduce radiation dose applied and should be used instead of radiographic frames whenever possible.
    CardioVascular and Interventional Radiology 07/2011; 35(3):613-20. · 2.09 Impact Factor
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    ABSTRACT: OBJECTIVE: The purpose of this study was to evaluate the effectiveness of transarterial chemoembolization in the care of patients not eligible for liver transplantation. CONCLUSIONS: Prognosis depends on local response, Okuda score, alpha-fetoprotein level, and tumor size and is independent of the presence of portal venous thrombosis.
    American Journal of Roentgenology 05/2008; 190(4):1035-42. · 2.90 Impact Factor
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    ABSTRACT: These case reports demonstrate a radiologic interventional technique for removal of pull-type gastrostomy tubes. This approach proved to be a safe and efficient procedure in two patients. The procedure may be applicable in situations where endoscopic attempts fail.
    CardioVascular and Interventional Radiology 05/2008; 31(6):1252-4. · 2.09 Impact Factor