B Frericks

Universität Basel, Bâle, Basel-City, Switzerland

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Publications (87)158.57 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Severe courses of Crohn's disease (CD) during pregnancy are rare. However, if occurring, the risk of miscarriage and low birth weight is increased. At present, only limited data is available on the treatment of CD during pregnancy. In particular, there are no standard guidelines for surgical therapy. Nevertheless, surgery is often unavoidable if complications during the course of the disease arise. This study provides a critical overview of conventional and interventional treatment options for CD complications during pregnancy and analyses the surgical experience gained thus far. For illustrative purposes, clinical cases of three young women with a severe clinical course during pregnancy are presented. After treatment-refractory for conservative and interventional measures, surgery remained as the only treatment option. In all cases, a split stoma was created after resection to avoid anastomotic leaks that would endanger the lives of mother and child. The postoperative course of all three patients was uneventful, and pregnancy remained intact until delivery. No further CD specific medication was required before birth. The management of CD patients during pregnancy requires close interdisciplinary co-operation between gastroenterologists, obstetricians, anaesthetists and visceral surgeons. For the protection of mother and child treatment should thus be delivered in a specialised centre. This article demonstrates the advantages of surgical therapy by focusing on alleviating CD complaints and preventing postoperative complications.
    International Journal of Colorectal Disease 05/2014; · 2.24 Impact Factor
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    ABSTRACT: PURPOSEWe report on a multicenter phase II trial of (90)yttrium-ibritumomab-tiuxetan ((90)YIT) as first-line stand-alone therapy for patients with follicular lymphoma (FL). PATIENTS AND METHODS Fifty-nine patients with CD20(+) FL grade 1 to 3a in stages II, III, or IV, age 50 years old or older requiring therapy were enrolled. They received (90)YIT according to standard procedure. If complete response (CR) or unconfirmed complete response (CRu) without evidence for minimal residual disease (MRD) 6 months after application of (90)YIT was achieved, patients were observed without further intervention. The same applied to patients with partial response (PR) or with stable disease (SD). Patients with CR but with persisting MRD were to receive a consolidation treatment with rituximab. Primary end point was the clinical and molecular response rate. Secondary end points were time to progression, safety, and tolerability.ResultsSix months after treatment with (90)YIT, 56% of the patients showed a CR or CRu and 31% achieved a PR. After a median follow-up of 30.6 months, the progression-free survival (PFS) was 26 months. There was a trend for shorter PFS in patients with increased lactate dehydrogenase (LDH). Of the 26 patients who had CR 12 months after (90)YIT, only three had relapsed. Median time to next treatment has not been reached. The most common toxicities were transient thrombocytopenia and leukocytopenia. Nonhematologic toxicities never exceeded grade 2 according to Common Terminology Criteria for Adverse Events (CTCAE v2.0). CONCLUSION(90)YIT is well tolerated and achieves high response rates. Patients with increased LDH tend to relapse earlier, and individuals in remission 1 year after (90)YIT appear to have long-lasting responses.
    Journal of Clinical Oncology 12/2012; · 18.04 Impact Factor
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    ABSTRACT: PURPOSE: To find out if the hepatic transit time (HTT) shortening, which was already proven in patients with liver metastases by other modalities, can also be detected with MRI. MATERIALS AND METHODS: The Patient group consisted of 20 subjects with liver metastases from colorectal cancer and the control group of 21 healthy subjects. Baseline and post contrast images were acquired before and after administration of Gd-BOPTA, using a T1-weighted bolus test sequence. Arrival times (AT) of the contrast agent for the aorta, the hepatic artery, the portal vein and one hepatic vein were determined. Based on arrival time measurements HTT were calculated. RESULTS: All analyses showed significantly shorter HTT in patients with metastases compared with healthy volunteers (P < 0.05). There were no false positives using a threshold of 10.4 s for arterial to venous HTT. For aortal to venous and portal to venous HTT a threshold of 12.5 s and 4 s was calculated, respectively. No significant correlation between HTT and involved liver segments, overall volume of metastases or subject age was found. CONCLUSION: We conclude that HTT measurements using contrast enhanced MRI with Gd-BOPTA can detect hemodynamic changes due to metastatic liver disease from colorectal cancer. J. Magn. Reson. Imaging 2012. © 2012 Wiley Periodicals, Inc.
    Journal of Magnetic Resonance Imaging 08/2012; · 2.57 Impact Factor
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    ABSTRACT: The prevalence of thyroid nodules ranges between 2% and 60% depending on the population studied. However, minimally invasive procedures like radiofrequency ablation (rfA) are increasingly used to treat tumors of parenchymatous organs, and seem to be suitable for singular thyroid nodules as well. Their successful clinical application depends on the induction of sufficiently large lesions and a knowledge of the energy parameters required for complete thermal ablation. The aim of this study was to establish a dose-response relationship for rfA of thyroid nodules. Thermal lesions were induced in healthy porcine thyroid glands ex vivo (n=110) and in vivo (n=10) using a bipolar radiofrequency system; rf was applied in a power range of 10-20 watts. During the ablation, continuous temperature measurement at a distance of 5 and 10 mm from the applicator was performed. The transversal and axial lesion diameters were measured, and the volume was calculated. Furthermore, enzyme histochemical analysis of the thyroid tissue was performed. The inducible lesion volumes were between 0.91±0.71 cm(3) at 20W and 2.80±0.85 cm(3) at 14W. The maximum temperatures after rf ablation were between 44.0±9.7°C and 61.6±13.9°C at a distance of 5 mm and between 30.0±8.6°C and 53.5±8.6°C at a distance of 10 mm from the applicator. The histochemical analysis demonstrates a complete loss of nicotinamide adenine dinucleotide phosphate-oxidase (NADPH) dehydrogenase activity in thermal lesions as a sign of irreversible cell damage. This study is the first to demonstrate a dose-response relationship for rfA of thyroid tissue. rfA is suitable for singular thyroid nodules and induces reproducible, clinically relevant lesions with irreversible cell damage in an appropriate application time.
    Journal of Surgical Research 08/2011; 169(2):234-40. · 2.02 Impact Factor
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    ABSTRACT: Peripheral MR angiography requires high resolution and arterial contrast. Neither can be obtained simultaneously due to the short arterial phase of the contrast agent. To improve temporal resolution, keyhole imaging was developed, which combines high resolution and arterial k-spaces at the time of image acquisition. Here, a related approach is introduced for image post-processing in the Fourier domain. It is demonstrated that simple substitution of the central k-space with low-resolution data leads to severe distortion. Hence, a dedicated calculation scheme is necessary for composite k-space post-processing. A solution is presented for high-resolution arterial peripheral MR angiography that uses subtraction of venous intensities from the central high-resolution k-space. The calculations in the Fourier domain do not require interpolations between the different resolutions. High-resolution steady-state MR angiography, which exhibits contrast-enhanced arteries and veins at an isotropic resolution of 0.65 mm, and standard resolution arterial first-pass MR angiography were combined to obtain images with the resolution of the steady-state images and arterial contrast. Numerical simulations on software phantoms are presented. The operation of the method is demonstrated in five patients.
    Magnetic Resonance Imaging 07/2011; 29(6):835-43. · 2.06 Impact Factor
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    ABSTRACT: : To determine the colonic mural enhancement in a rat model of inflammatory bowel disease (IBD) using gadofluorine M- and diethylenetriamine pentaacetic acid (Gd-DTPA)-enhanced magnetic resonance (MR) imaging, and to correlate the degree of enhancement with the histopathologic severity of the disease. : This study was approved by our hospital's institutional animal care and use committee. A total of 44 rats with 2 grades (mild, n = 17; and severe, n = 27) of dinitrobenzene sulfonic acid (DNBS)-induced IBD and 13 rats without IBD, were examined using a 2.4-T, small animal MR scanner. T2- and T1-weighted MR images were acquired, and sequential T1-weighted MR imaging was then performed immediately and again 15, 45, 60, and 90 minutes, and 24 hours after intravenous -injection of either gadofluorine M- or Gd-DTPA (0.1 mmol Gd/kg body weight). The signal-to-noise ratios and enhancement ratios (ER) of the colon wall were measured. For paired and group comparisons of the histopathology and MR imaging data, the Wilcoxon- and the Mann-Whitney U tests were used, and the multifactorial analysis of variance test was used to compare the time courses of the ERs. : Gadofluorine M injection resulted in significant differences in the ER of noninflamed, mildly inflamed, and severely inflamed colon wall at any time up to 24 hours after contrast injection (ER at 24 hours 2.0 ± 1.2; 10.1 ± 4.3; and 49.7 ± 10.8, respectively; P < 0.01). After Gd-DTPA injection, significant differences were observed in the ER of inflamed and noninflamed bowel at 15, 45, and 60 minutes (P < 0.01); however, no significant differences in mildly and severely inflamed bowel were observed at any time. In contrast to Gadofluorine M, there was no prolonged contrast enhancement in the inflamed colon wall after intravenous injection of Gd-DTPA (ER at 24 hours 1.6 ± 1.3; 3.4 ± 2.7; and 3.3 ± 1.6, respectively; n.s.). : Gadofluorine M-enhanced MR imaging shows a higher correlation of the wall enhancement and histopathology grading in an IBD rat model than does Gd-DTPA-enhanced imaging.
    Investigative radiology 04/2011; 46(8):478-85. · 4.85 Impact Factor
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    ABSTRACT: In situ ablation is increasingly being used for the treatment of liver malignancies. The application of these techniques is limited by the lack of a precise prediction of the destruction volume. This holds especially true in anatomically difficult situations, such as metastases in the vicinity of larger liver vessels. We developed a three-dimensional (3D) planning system for laser-induced thermotherapy (LITT) of liver tumors. The aim of the study was to validate the system for calculation of the destruction volume. LITT (28 W, 20 min) was performed in close contact to major hepatic vessels in six pigs. After explantation of the liver, the coagulation area was documented. The liver and its vascular structures were segmented from a pre-interventional CT scan. Therapy planning was carried out including the cooling effect of adjacent liver vessels. The lesions in vivo and the simulated lesions were compared with a morphometric analysis. The volume of lesions in vivo was 6,568.3 ± 3,245.9 mm(3), which was not different to the simulation result of 6,935.2 ± 2,538.5 mm(3) (P = 0.937). The morphometric analysis showed a sensitivity of the system of 0.896 ± 0.093 (correct prediction of destructed tissue). The specificity was 0.858 ± 0.090 (correct prediction of vital tissue). A 3D computer planning system for the prediction of thermal lesions in LITT was developed. The calculation of the directional cooling effect of intrahepatic vessels is possible for the first time. The morphometric analysis showed a good correlation under clinical conditions. The pre-therapeutic calculation of the ablation zone might be a valuable tool for procedure planning.
    International Journal of Colorectal Disease 03/2011; 26(6):799-808. · 2.24 Impact Factor
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    ABSTRACT: PurposeTo evaluate if erythromycin compromises liver-specific enhancement of gadoxetic acid; both compounds competing in organic anion transporting peptides (OATP) -mediated hepatocytic uptake.Materials and Methods The study was approved by institutional review board. Twelve healthy subjects (nine men, three woman; mean age, 38.7 years) were examined twice by MR imaging with prior administration of NaCl solution (placebo) or 1000 mg of erythromycin following a randomized sequence. Gadoxetic acid (0.025 mmol/kg body weight) was administered 15 min after the end of infusions. Pre- and 20 min postcontrast two-dimensional gradient-recalled-echo sequences were acquired. Relative enhancements of liver parenchyma and ratio of means were calculated from signal intensity measurements. Plasma levels of gadoxetic acid and erythromycin were determined and given in geometric means and coefficients of variation (CV).ResultsConcentration of erythromycin directly after end of infusion was 13.9 mg/L (CV 14.9%). Gadolinium plasma concentrations 5 min after gadoxetic acid administration were 138.7 μmol/L (CV 20.4%) after erythromycin infusion and 129.6 μmol/L (CV 22.8%) after placebo. Mean relative enhancements of liver parenchyma were 88.1 (SD 24.9%) after erythromycin infusion and 92.6 (SD 17.9%) after placebo. Ratio of relative enhancements was 0.951 (95% confidence interval, 0.833; 1.061; statistically not significant).Conclusion Coadministration of erythromycin has no effect on gadoxetic acid enhanced liver MR imaging. J. Magn. Reson. Imaging 2011;33:409–416. © 2011 Wiley-Liss, Inc.
    Journal of Magnetic Resonance Imaging 01/2011; 33(2):409 - 416. · 2.57 Impact Factor
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    ABSTRACT: Sigmoid diverticulitis (SD) is common in the West; its incidence is increasing as the average age of the population increases. The aim of this study was to assess the clinical outcomes of patients with acute SD and to determine whether emergency operation was associated more often with previous episodes of acute diverticulitis. All consecutive patients admitted for acute SD were recruited prospectively over an 11-year period from January 1998 to December 2008. Multiple logistic regression was used to identify risk factors for free perforation. We included 934 patients (490 men and 444 women; median age, 59.2 years): 450 (48.2%) presented for their first SD episode and 484 (51.8%) had a prior history of SD. Free perforation occurred in 152 patients: during the first episode of SD in 114 patients (25.3%), during the second in 29 (12.7%), during the third in 8 (5.9%), and during the fifth in 1 patient (0.9%; P < .001). No patient with >5 previous episodes of SD had free perforation. All 152 patients with free perforation required emergent operative intervention. After initial conservative therapy in 782 patients, 82 required early elective operative intervention owing to exacerbation of infection under antibiotic treatment. Late elective colectomy was performed in 299 patients during the inflammation-free interval, and operative intervention was recommended in 345 patients owing to complicated diverticulitis. Uncomplicated SD in 56 patients was managed conservatively. Comorbidity (>1 disorder) and the first episode of SD were identified as risk factors for free perforation on multiple logistic regression. The risk of free perforation in acute SD decreases with the number of previous episodes of SD. The first episode thus is the most dangerous for a free perforation. The indication for colectomy should not be made based on the potential risk of free perforation.
    Surgery 12/2010; 149(5):606-13. · 3.37 Impact Factor
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    ABSTRACT: This study was designed to evaluate whether the computed tomography (CT) reflects the extent of the inflammation in sigmoid diverticulitis (SD) in order to draw conclusions for selecting the appropriate treatment. Two hundred four patients who underwent resection for SD from January 2003 to December 2008 were included. The preoperative CT stage was compared with intraoperative and histological findings. Patients were classified into phlegmonous (Hansen-Stock IIa), abscess-forming (HS IIb), and free perforated (HS IIc) forms of SD. Patients with a recurrent type of diverticulitis were excluded. In the phlegmonous type (HS IIa; n = 75), we found a correlation with the preoperative stage in 52% (intraoperative) and 56% (histological), an understaging in 12% (intraoperative) and 11% (histological), and an overstaging in 36% (intraoperative) and 33% (histological). In the abscess-forming type (HS IIb, Hinchey I/II; n = 87), we found conformity in 92% (intraoperative) and 90% (histological), understaging in 3% (intraoperative) and 0% (histological), and overstaging in 5% (intraoperative) and 10% (histological). In the presence of a free perforation (HS IIc, Hinchey III/IV; n = 42), we saw conformity in 100% (intraoperative and histological). The positive predictive value for correctly diagnosing of phlegmonous type (HS IIa), abscess-forming type (HS IIb), and free perforation (HS IIc) by CT was intraoperatively (histologically) 52% (56), 92% (90), and 100% (100), respectively. The CT is one of the most accurate methods for staging in SD. However, in the phlegmonous type (HS IIa), it leads to an overestimation of the findings in every third patient. It must be clarified whether this pronounced low inflammation should really be regarded as a complicated form of SD. In contrast, the abscess-forming (HS IIb) and free perforated (HS IIc) type of complicated SD is very well reflected by CT.
    Langenbeck s Archives of Surgery 11/2010; 395(8):1009-15. · 1.89 Impact Factor
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    ABSTRACT: CASE REPORT: A 26-year-old man was admitted to hospital with a 6-month history of diarrhea and abdominal pain. Before admission, upper and lower gastrointestinal endoscopy had shown a mild erosive duodenitis and the patient was started on a proton pump inhibitor. Physical examination and laboratory tests on admission were not constructive. In addition, repeated gastrointestinal endoscopy, cross-sectional imaging and neuroendocrine markers did not point to a specific etiology. Therefore, as a provocation test, the proton pump inhibitor therapy was discontinued. Discontinuation resulted in a progression of the patient's symptoms and an endoscopic detection of duodenal ulcers. Except for the normal serum gastrin levels, this constellation was suggestive of a gastrinoma, so that further investigations were initiated. Subsequently, the diagnosis could be confirmed and the gastrinoma located. After successful pancreaticoduodenectomy, the patient was symptom-free. CONCLUSION: As part of a systematic investigation on chronic diarrhea, the work-up for neuroendocrine causes can play an important role. In this context, it should be kept in mind that some gastrinoma patients present without an elevation of serum gastrin levels. Regardless of a negative gastrin test, a typical symptom constellation should therefore prompt further investigations.
    Medizinische Klinik 04/2010; 105(4):242-5. · 0.34 Impact Factor
  • RöFo - Fortschritte auf dem Gebiet der R 03/2010; 182. · 2.76 Impact Factor
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    ABSTRACT: The indications for prophylactic surgery for phlegmonous and covered perforated type of acute sigmoid diverticulitis (SD) are currently matters of debate, and a more conservative approach has been advocated. However, it has not yet been clarified to what extent CT findings indicative of acute SD correlate with histological findings, and it is still uncertain how these findings change in the time interval between initial antibiotic treatment and late elective surgery. The aim of this study was to record time-course changes of inflammation in phlegmonous and abscess-forming diverticulitis after conservative treatment in order to check the indication for surgery. This study included all patients who underwent surgery for CT morphologically phlegmonous and covered perforated SD from January 2002 to June 2007. Two groups were formed to record time-course changes: early elective surgery (7-10 days after antibiotic treatment) and late elective surgery (4-6 weeks after conservative treatment). Exclusion criteria were emergency interventions, free perforations (Hinchey III and IV), recurrent inflammations, and contrast allergy. The extent of the inflammation recorded preoperatively by CT scan was compared with histological findings. A total of 257 patients (142 male and 115 female; mean age, 56.6 years) underwent surgery (116 early elective and 141 late elective) for phlegmonous and covered perforated SD. Phlegmonous SD was seen in 127 cases and covered perforated SD in 130 cases. In the phlegmonous type of SD, early surgery led to conformity with the preoperative stage in 56%, to more extensive findings in 11%, and to subsided inflammation in 33%. Late surgery led to conformity in 0% and to signs of subsided inflammation in 100%. In the covered perforated type of SD, early surgery led to conformity in 90%, to subsided inflammation in 10%, and to milder manifestation in 0%. In contrast, late surgery here led to conformity in 26% of the cases and to subsided inflammation in 74%. Considerable histological changes can be detected under conservative therapy. The acute inflammation subsides under antibiotic therapy as awaited. It must be clarified whether the phlegmonous form of SD should, in principal, be regarded as an indication for surgery, since it shows early and nearly complete regression of the inflammation. Otherwise, the covered perforated type of SD still shows marked inflammatory changes after conservative therapy in a high percentage of patients and should thus preferably be treated by surgery. However, the clinical appearance of the patient with sigmoid diverticulitis still remains the most important part of decision making.
    Journal of Gastrointestinal Surgery 02/2010; 14(5):812-7. · 2.36 Impact Factor
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    ABSTRACT: We present a novel technique to predict the outcome of an RF ablation, including the vascular cooling effect. The main idea is to separate the problem into a patient independent part, which has to be performed only once for every applicator model and generator setting, and a patient dependent part, which can be performed very fast. The patient independent part fills a look-up table of the cooling effects of blood vessels, depending on the vessel radius and the distance of the RF applicator from the vessel, using a numerical simulation of the ablation process. The patient dependent part, on the other hand, only consists of a number of table look-up processes. The paper presents this main idea, along with the required steps for its implementation. First results of the computation and the related ex-vivo evaluation are presented and discussed. The paper concludes with future extensions and improvements of the approach.
    The Open Biomedical Engineering Journal 01/2010; 4:16-26.
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    ABSTRACT: Fallbeschreibung: Ein 26-jähriger Patient stellte sich in der Klinik zur Abklärung einer seit 6 Monaten bestehenden chronischen Diarrhö mit Oberbauchschmerzen vor. Die Anamnese ergab den endoskopischen Vorbefund einer leichten erosiven Duodenitis mit konsekutiver Einleitung einer Protonenpumpeninhibitortherapie. Körperliche Untersuchung und Basislabor blieben ohne richtungweisenden Befund. Die weiterführende Diagnostik mit erneuter Endoskopie, Schnittbildgebung und Bestimmung der neuroendokrinen Marker ermöglichte ebenfalls keine ätiologische Zuordnung der Beschwerden. Daraufhin wurde ein Auslassversuch der Protonenpumpeninhibitortherapie durchgeführt. Dies führte zum erstmaligen endoskopischen Nachweis von duodenalen Ulzera bei einer deutlich progredienten Grundsymptomatik. Insgesamt ergab sich somit trotz negativer Labormarker eine für ein Gastrinom typische Symptomkonstellation. In der weiteren Abklärung konnten die Diagnose eines Gastrinoms gestellt und der Tumor lokalisiert werden. Nach erfolgreicher Therapie mit einer pyloruserhaltenden Pankreatikoduodenektomie war der Patient im weiteren Verlauf beschwerdefrei. Schlussfolgerung: Die Untersuchung auf eine neuroendokrine Genese kann bei einer chronischen Diarrhö Teil der systematischen differentialdiagnostischen Abklärung sein. Bei klinischem Verdacht sollte hierbei der seltene Fall eines gastrinnegativen Gastrinoms bedacht und diagnostisch abgeklärt werden. Case Report: A 26-year-old man was admitted to hospital with a 6-month history of diarrhea and abdominal pain. Before admission, upper and lower gastrointestinal endoscopy had shown a mild erosive duodenitis and the patient was started on a proton pump inhibitor. Physical examination and laboratory tests on admission were not constructive. In addition, repeated gastrointestinal endoscopy, cross-sectional imaging and neuroendocrine markers did not point to a specific etiology. Therefore, as a provocation test, the proton pump inhibitor therapy was discontinued. Discontinuation resulted in a progression of the patient’s symptoms and an endoscopic detection of duodenal ulcers. Except for the normal serum gastrin levels, this constellation was suggestive of a gastrinoma, so that further investigations were initiated. Subsequently, the diagnosis could be confirmed and the gastrinoma located. After successful pancreaticoduodenectomy, the patient was symptom-free. Conclusion: As part of a systematic investigation on chronic diarrhea, the work-up for neuroendocrine causes can play an important role. In this context, it should be kept in mind that some gastrinoma patients present without an elevation of serum gastrin levels. Regardless of a negative gastrin test, a typical symptom constellation should therefore prompt further investigations. Schlüsselwörter: Gastrinom-Chronische Diarrhö-Rezidivierende erosiv- ulzeröse Gastroduodenitis Key Words: Gastrinoma-Chronic diarrhea-Erosive ulcerative gastroduodenitis
    01/2010; 105(4):242-245.
  • Zeitschrift Fur Gastroenterologie - Z GASTROENTEROL. 01/2010; 48(08).
  • Rofo-fortschritte Auf Dem Gebiet Der Rontgenstrahlen Und Der Bildgebenden Verfahren - ROFO-FORTSCHR RONTGENSTRAHL. 01/2010; 182.
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    ABSTRACT: PURPOSE To evaluate the size and shape of ablation zones after multipolar RF ablation of malignant liver tumors and to determine affecting technical and non-technical factors. METHOD AND MATERIALS Institutional review board approval and written informed consent were obtained. Forty-four patients (26 men, 18 women; mean age, 64±9 years) with 80 malignant liver tumors (mean size, 28±15 mm) were treated with multipolar RF ablation percutaneously (n=60) or intraoperatively (n=20). Volumes and shapes of the ablation zones were evaluated on post-interventional MR by 3D planimetry and using ellipticity-, regularity-, and axial and transverse fusion indices (EI, RI, AFI, TFI). The influence of potentially affecting technical and non-technical parameters was analyzed by uni- and multivariate analyses. RESULTS Mean ablation zone volumes were 63±50 ml and 124±122 ml for the percutaneous and the intraoperative approach, respecitvely (P<0.05). Multivariate analyses revealed blood flow reduction (P<0.001), number of probes (P<0.001), and distance between the probes (P<0.001) as independent determining factors. Mean ablation zones’ EI and RI were 1.5±0.4 and 0.7±0.2, indicating slight ellipticity and moderate irregularity. Mean AFI and TFI were 1.1±0.2 and 1.0±0.2, indicating complete fusion of the ablation zones. Multivariate analyses revealed number of probes (P<0.05) and applied energy (P<0.0001) determining the EI, and distances between the probes (P<0.05) determining the AFI. If one probe was used, RI was influenced by energy (P<0.001) and blood flow reduction (P<0.05). Intrahepatic vessels had no negative effect. CONCLUSION Blood flow reduction, number and distances of probes and applied energy were independent influencing variables of volume and shape of multipolar RF ablation zones. CLINICAL RELEVANCE/APPLICATION If affecting parameters are chosen adequately multipolar RF ablation provides comparatively large ablation zones of regular shape.
    Radiological Society of North America 2009 Scientific Assembly and Annual Meeting; 12/2009
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    ABSTRACT: PURPOSE Vasovist (gadofosveset trisodium, Bayer-Schering, Germany) is a blood pool agent for MRA. In addition to conventional first pass arterial phase MRA (FP), high resolution steady state (SS) imaging is performed during the blood pool phase of Vasovist. This prospective study was performed to assess if FP combined with SS imaging provides relevant additional information compared to FP alone. METHOD AND MATERIALS 82 patients with peripheral arterial occlusive disease were included. After bolus tracking, step-by-step FP was performed (9 ml Vasovist at 1ml/s and 30 ml normal saline at 0.5ml/s) using an Avanto scanner (Siemens) and 3D T1w sequences at 0.9x0.9x1.5 voxel size followed by high resolution SS imaging at 0.65x0.65x0.65mm voxel size. In 14 patients, additional DSA was performed within 4 weeks of MRA. Two off-site blinded reader first assessed first pass MRA and then first pass MRA combined with steady state imaging in terms of diagnostic confidence and maximum degree of segmental stenosis if DSA was available. DSA served as gold standard (one blinded reader). RESULTS 813 below knee arterial segments were assessed (excluding pedal arteries). On FP, 97.5%(reader1) and 87.5%(reader2) of segments were considered diagnostic. FP+SS provided diagnostic images in 99.1%( p<0.05) and 98.0%(p<0.05). Above the knee, 97% and 95% of 401 arterial levels were diagnostic on FP and 100%(p<0.05) and 99%(P<0.05) on FP+SS. In 9.8% and 18.7% of segments/levels, additional information was provided by SS (better assessment of lesion morphology or lumen in stent). A total of 117 vessels were covered by MRA and DSA. Grading of these showed complete agreement in 79%(reader1) and 80%(reader2) between DSA and FP and in 78% and in 81% between FP+SS and DSA. Sensitivity for the detection of relevant stenoses (>50%) was 80% and 73% on FP and 77% and 78% on FP+SS; specificity was 96% and 97% for FP and did not change on FP+SS. CONCLUSION The addition of SS to FP pass imaging increased the number of diagnostic segments in a relatively small but significant proportion for both readers. CLINICAL RELEVANCE/APPLICATION Combined FP+SS MRA with Vasovist increases the number of assessable vessels and improves the validity of the examination.
    Radiological Society of North America 2009 Scientific Assembly and Annual Meeting; 12/2009
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    ABSTRACT: The objective of our study was to prospectively evaluate quantitatively and qualitatively the enhancement patterns of cirrhotic liver tissue and hepatocellular carcinoma (HCC) after administration of the hepatocyte-specific contrast agent gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) on dynamic MRI and to determine the time point of maximum liver-to-lesion contrast. Twenty-five patients with HCC in liver cirrhosis underwent 1.5-T MRI. T2-weighted turbo spin-echo and T1-weighted 3D gradient-echo sequences before and between 15 seconds and 20 minutes after the injection of 10 mL of Gd-EOB-DTPA were performed. Signal-to-noise ratios (SNRs) of liver parenchyma and liver-to-lesion contrast-to-noise ratios (CNRs) were calculated and plotted over time. Enhancement patterns of HCC were characterized qualitatively by two radiologists. The SNR of liver parenchyma increased significantly at 15 seconds and 60 seconds after contrast injection and remained stable thereafter. HCC showed positive CNR during the arterial phase and increasingly negative CNR during the further time course (p < 0.05). The maximum absolute CNR was found at 20 minutes after contrast injection. There was no correlation between the degree of enhancement at any time point and tumor grade. On qualitative evaluation, 16 HCCs showed arterial enhancement with early washout, and five showed arterial enhancement with late washout. In the remaining four HCCs, enhancement persisted until 20 minutes. Lesion conspicuity at 20 minutes after contrast injection was at least equal to or higher than it was on the remaining sequences in 19 of the 25 patients. After Gd-EOB-DTPA injection, most HCCs showed typical arterial enhancement with early washout. Liver-to-lesion contrast was best at 20 minutes.
    American Journal of Roentgenology 10/2009; 193(4):1053-60. · 2.90 Impact Factor

Publication Stats

602 Citations
158.57 Total Impact Points

Institutions

  • 2012
    • Universität Basel
      Bâle, Basel-City, Switzerland
  • 2005–2011
    • Charité Universitätsmedizin Berlin
      • Institute of Medical Biometrics and Clinical Epidemiology
      Berlín, Berlin, Germany
  • 2009
    • Universitätsspital Basel
      Bâle, Basel-City, Switzerland
  • 2008
    • Humboldt-Universität zu Berlin
      Berlín, Berlin, Germany
  • 2001–2007
    • Hannover Medical School
      • Department of Gastroenterology, Hepatology and Endocrinology
      Hannover, Lower Saxony, Germany