R Felix

Charité Universitätsmedizin Berlin, Berlín, Berlin, Germany

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Publications (461)1061.47 Total impact

  • International Journal of Hyperthermia 11/2009; 25(7):517-28. · 2.59 Impact Factor
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    International Journal of Hyperthermia 11/2009; 25(7):499-511. · 2.59 Impact Factor
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    ABSTRACT: To assess image quality and overall accuracy of 3-Tesla (3T)-sustained high-resolution magnetic resonance (MR) imaging for diagnostic preoperative workup in suspected rectal carcinoma. Twenty-three patients with suspected rectal cancer underwent unenhanced and contrast-enhanced fat-suppressed pelvic high-resolution MR imaging using a four-channel phased-array pelvic coil at 3T. Image quality, tumor stage, distance from the anorectal margin, and sphincter-saving resectability were prospectively assessed by two blinded readers. The results were correlated with clinical, surgical, and histopathologic findings. In all 23 patients, MR images were of diagnostic quality, and malignancy was correctly identified in 21 patients. The accuracy for determining sphincter-saving resectability was 100% (19/19). T stage and N stage were correctly diagnosed in 95% and 91%, respectively. MRI allowed correct identification of tumor extension and its relation to surgically relevant pelvic structures including the anorectal margin and mesorectal fascia. Transverse T2-weighted fast spin-echo images compared superiorly to all other sequences for the diagnosis of mesorectal infiltration and lymph node involvement. Moreover, transverse fat-suppressed contrast-enhanced T1-weighted images were valuable for identifying tumor infiltration, while sagittal sections were useful for the detection of longitudinal tumor extension. MR imaging with phased-array receiver coils at 3T facilitated both visualization of different pathologic conditions of the rectum and accurate determination of tumor stage in rectal carcinomas. Thus, this noninvasive diagnostic approach appeared highly suitable for the assessment of patients with suspected rectal carcinoma.
    Acta Radiologica 06/2007; 48(4):379-87. · 1.33 Impact Factor
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    ABSTRACT: Assessing response to radiation therapy in patients with high grade gliomas is needed upon making decisions toward further therapy strategies. Currently used standard imaging tools such as CT and MRI are not sensitive enough to detect early therapy effects. We prospectively investigated if single photon emission computed tomography (SPECT) using radiolabelled amino acid derivate (123)I-methyltyrosine (IMT) would be useful for this aim. 10 patients with histologically proven high grade gliomas, who were candidates for radiation therapy, were enrolled in this investigation. All patients were examined by IMT SPECT before radiation therapy and 4 weeks after the initiation of the hypofractionated application of 40 Gy. Patients were followed up for 39 months; the tumours to background ratios (T/B) for IMT under/before radiation therapy were correlated to survival times. Initially, SPECT depicted an abnormal intratumoural IMT uptake in all patients (mean T/B ratios 1.37-1.87). In four out of 10 patients, the mean T/B ratios decreased by more than 10% under radiation therapy. In six other patients, the BQ decreased by less than 10% or increased. There were no significant correlations between the degree of changes in T/B and survival (r = -0.1, p = 0.973). Serial IMT SPECT measurements allow detection of changes in amino acid accumulation in high-grade gliomas under radiation therapy. However, these changes seem to possess no prognostic value in respect to survival prediction.
    The British journal of radiology 05/2007; 80(952):274-8. · 2.11 Impact Factor
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    ABSTRACT: To evaluate the accuracy of magnetic resonance angiography (MRA) for preoperative assessment of hepatic vascular anatomy in liver donors before living related liver transplantation. A total of 55 consecutive living liver donors (mean age 42 years, range 18-68 years) underwent multiphase contrast-enhanced MRA of the hepatic vessels. Two readers categorized vessel visualization on a five-point scale and recorded vascular anatomy or variations thereof for the arterial, portal venous and venous systems. All 55 living liver donors subsequently underwent right hemihepatectomy for hemiliver donation, and preoperative MRA results were correlated with surgical findings. Overall vessel visualization assessment demonstrated good or very good ratings for the majority of patients. For hepatic arteries, the mean score was 4.4+/-0.8 (mean+/-standard deviation), and for the portal venous and venous systems it was 4.6+/-0.7 and 4.3+/-0.8, respectively. Among all 55 donors, 16 (29%) demonstrated accessory or replaced hepatic arteries, and seven (13%) and 20 (36%) donors had surgically relevant portal vein (trifurcation or early right posterolateral branching types) and hepatic vein variations, respectively. Correlation coefficients between MRA and surgery were 0.94, 1.00 and 0.91 for hepatic arteries, portal veins and hepatic veins, respectively. In the preoperative evaluation before living related liver donation, contrast-enhanced MR angiography was a highly accurate, noninvasive tool for visualizing the hepatic vasculature and variations thereof in liver donor candidates.
    Acta Radiologica 03/2007; 48(1):20-6. · 1.33 Impact Factor
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    ABSTRACT: In addition to planar parathyroid scintigraphy, SPECT and image fusion with CT/MR improve adenoma detection in primary hyperparathyroidism (pHPT). This study evaluated the use of a hybrid SPECT-CT device concerning image fusion and attenuation correction (AC). The data of 26 patients with pHPT, preoperatively examined by (99m)Tc-sestamibi dual-phase scintigraphy plus SPECT-CT (low-dose CT), was retrospectively evaluated by two observers in a consensus reading. The images of planar scintigraphy, non-attenuation corrected SPECT (SPECT(NAC)), attenuation corrected SPECT (SPECT(AC)) and SPECT(AC)-CT were interpreted and compared to the results of surgery. The effect of AC on focus intensity was semiquantified by determination of the tumor-to-background (TB) ratio for SPECT(AC) and SPECT(NAC). Finally, the TB(AC)/TB(NAC)-ratio was calculated for each focus and correlated to the distance of a focus from the body surface. 20/26 (77%) patients were positive in planar scintigraphy. One focus was detected by SPECT only. AC of SPECT-data increased image contrast but had no impact on the detection rate. Additional SPECT(AC)-CT image fusion facilitated the localization of three mediastinal foci. In the semiquantitative analysis an increase in TB after AC was observed, although there was no strong correlation between depth of the focus (16-60 mm) and the TB(AC)/TB(NAC)-ratio (r = 0.213, p = 0.353). The detection rate of planar scintigraphy is only slightly improved by SPECT imaging. Due to the low spatial resolution of the CT component, the benefit of image fusion is limited to mediastinal foci. However, as TB and image contrast is measurably improved after AC there is a potential to improve the sensitivity of parathyroid SPECT.
    Nuklearmedizin 02/2007; 46(1):15-21. · 1.67 Impact Factor
  • Rofo-fortschritte Auf Dem Gebiet Der Rontgenstrahlen Und Der Bildgebenden Verfahren - ROFO-FORTSCHR RONTGENSTRAHL. 01/2007; 179.
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    ABSTRACT: To evaluate a handheld vacuum-assisted device system for magnetic resonance image (MRI)-guided breast lesion biopsy. In 32 patients, a total of 42 suspicious breast lesions (mean diameter 7.5 mm for mass lesions, 11.6 mm for non-masslike diffuse lesions) seen with MRI (no suspicious changes in breast ultrasound or mammography) were biopsied (27 lateral, 15 medial) using a 10G vacuum-assisted breast biopsy device under MR guidance. Histology of biopsy specimens was compared with final histology after surgery or follow-up in benign lesions. In all biopsies, technical success was achieved. Histology revealed 11 lesions with ductal carcinoma in situ (DCIS) or invasive cancer, three with intermediate lesions (LCIS) and 28 with benign breast lesions (adenosis, infected hematoma). In one patient with discordant results of MRI and histology, surgical excision revealed medullary cancer. In the follow-up (mean 18 months) of the histological benign lesions, no breast cancer development was observed. Besides minor complications (hematoma, n = 6), with no further therapeutic interventions, no complications occurred. MRI-guided breast lesion biopsy using a handheld vacuum-assisted device is a safe and effective method for the work-up of suspicious lesions seen with breast MRI without changes in mammography or ultrasound. In the case of discordant histology of vacuum biopsy and breast MRI appearance, surgical excision is recommended.
    Acta Radiologica 12/2006; 47(9):907-13. · 1.33 Impact Factor
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    ABSTRACT: To evaluate the ready-to-use iodine-containing polyvinyl alcohol (I-PVA) dissolved in the low angiotoxic solvent N-methyl pyrrolidone (NMP) for embolization of porcine wide-necked aneurysms. Fourteen broad-based carotid sidewall aneurysms were surgically constructed in 7 swine. I-PVA (40%) in NMP was injected under temporary balloon occlusion bridging the aneurysm neck. After 4 weeks, follow-up angiography, multisection CT angiography (MSCTA), and 3T MR imaging including MR angiography (MRA) sequences were performed. Afterward, harvested aneurysms were investigated histopathologically. The liquid embolic was well visible under fluoroscopy and displayed a favorable precipitation pattern, allowing for controlled polymer delivery. Ten aneurysms (71%) were initially completely occluded, whereas in 1 aneurysm, a minimal polymer leakage was observed. The other 4 aneurysms (29%) were almost completely occluded. One animal suffered a lethal rebleeding from the anastomosis after uneventful embolization. Aneurysms embolized with I-PVA could be discriminated well from the parent artery without beam-hardening artifacts on MSCTA, and no susceptibility artifacts were encountered on MR imaging. Histologic examination revealed all aneurysms covered with a membrane of fibroblasts and an endothelial cell layer while a moderate intraaneurysmal inflammatory response to the polymer was observed. I-PVA dissolved in NMP has proved its effectiveness for the embolization of experimental wide-necked aneurysms. This precipitating liquid embolic offers several interesting features in that it needs no preparation before use and no radiopaque admixtures, the latter allowing for artifact-free evaluation of treated aneurysms with MSCTA and MRA. Moreover, it uses NMP as a solvent, which has only a low angiotoxicity.
    American Journal of Neuroradiology 11/2006; 27(9):1849-55. · 3.17 Impact Factor
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    ABSTRACT: The organic solvent dimethyl-sulfoxide (DMSO), as a commonly used vehicle for nonadhesive liquid embolics, is not devoid of local angiotoxic effects. We compared microvascular toxicities of superselective infusions of DMSO with potentially more compatible solvents in swine rete mirabile. Fourteen swine underwent angiography for superselective catheterization of 28 arteries of the rete while electrocardiography and intra-arterial pressure were continuously monitored. The investigated solvents were DMSO, dimethyl isosorbide (DMI), ethyl lactate, glycofurol 75, N-methyl pyrrolidone (NMP), and solketal. Control infusion of saline ruled out catheter induced vasospasm in all cases. Each artery of the rete was infused only once with 0.8 mL of one of the solvents over 60 seconds. Acute angiographic and hemodynamic consequences were evaluated. Blood samples were assessed for signs of intravascular hemolysis. Brains and retia were harvested for gross and histopathologic investigation. On the basis of the angiographic data, DMSO induced the most pronounced vasospasm with the longest recovery period of all solvents investigated. Ethyl lactate, glycofurol 75, and solketal elicited less severe vasospasms and accordingly resolved much more quickly. DMI and NMP induced only minimal vasospasms with comparably short duration. No solvent caused significant hemodynamic alterations or hemolysis. Gross inspection of brains showed no abnormalities, whereas histopathologic examination revealed mostly nonspecific findings. One rete exposed to solketal displayed possible causal histotoxic changes. DMI and NMP produced far less vasospasm than DMSO. No changes in hemodynamic or hemolytic parameters and no histopathologic findings were observed with infusion of these solvents.
    American Journal of Neuroradiology 11/2006; 27(9):1900-6. · 3.17 Impact Factor
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    ABSTRACT: A systematic comparison of three-dimensional MR (magnetic resonance) thermography and planning calculations in phantoms for the hyperthermia (HT) SIGMA-Eye applicator. We performed 2 x 6 experiments in a homogeneous cylindrical and a heterogeneous elliptical phantom by adjusting 82 different patterns with different phase control inside an MR tomograph (Siemens Magnetom Symphony, 1.5 Tesla). For MR thermography, we employed the proton resonance frequency shift method with a drift correction based on silicon tubes. For the planning calculations, we used the finite-difference time-domain (FDTD) method and, in addition, modeled the antennas and the transforming network. We generated regions according to a segmentation of bones and tissue, and used an interpolation technique with a subgrid of 0.5 cm size at the interfaces. A Gauss-Newton solver has been developed to adapt phases and amplitudes. A qualitative agreement between the planning program and measurements was obtained, including a correct prediction of hot spot locations. The final deviation between planning and measurement is in the range of 2-3 W/kg, i.e., below 10%. Additional HT phase and amplitude adaptation, as well as position correction of the phantom in the SIGMA-Eye, further improve the results. HT phase corrections in the range of 30-40 degrees and HT amplitude corrections of +/- 20-30% are required for the best agreement. The deviation /MR-FDTD/, and the HT phase/amplitude corrections depend on the type of phantom, certain channel groups, pattern steering, and the positioning error. Appropriate agreement between three-dimensional specific absorption rate distributions measured by MR-thermography and planning calculations is achieved, if the correct position and adapted feed point parameters are considered. As long as feed-point parameters are uncertain (i.e., cannot be directly measured during therapy), a prospective planning will remain difficult. However, we can use the information of MR thermography to better predict the patterns in the future even without the knowledge of feed-point parameters.
    Medical Physics 11/2006; 33(10):3912-20. · 2.91 Impact Factor
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    ABSTRACT: Background/aims: An experimental model for the preclinical evaluation of contrast enhancement patterns in melanoma was developed.Methods: Melanotic and amelanotic tumor cells B16F1 and B16a implanted into murine skin were depicted with magnetic resonance imaging (MRI) at a pixel size of 78×78 urn and 1 mm slice thickness. Tumor signal intensities were evaluated in user defined ROIs (regions of interest). Signal intensity changes were determined from signal intensity-time curves. Percent enhancement, slope of the signal intensity curve and percent signal intensity increase were also determined. Percent enhancement was calculated: (SIenhanced-SIpiain)/SIplain× 100 [SI=signal intensity]. The slope of the signal intensity curve was calculated: (SImax-SIplain)/(SIplain× SImax) × 100 (%/min). Percent signal intensity increase was calculated: (SImax-SIplai)/SIplain× 100.Results: Following i.v. administration of Gd-DTPA and G-DTPA-polylysine, all tumors showed pronounced contrast enhancement. Contrast enhancement and the slope of signal intensity to time curves did not distinguish melanotic from amelanotic melanomas (P>0.05).Conclusions: The animal model presented is well suited for evaluation of contrast enhancement in melanoma by MRI. Contrast enhancement of melanoma in MRI is comparable with the enhancement seen in other tumors.
    Skin Research and Technology 10/2006; 4(1):49 - 53. · 1.41 Impact Factor
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    ABSTRACT: The aim of the current study was to investigate the feasibility of real-time 3D (4D) ultrasound-guided biopsy. Between 2003 and 2005, 53 patients with suspicious lymph nodes or solid tumours underwent 4D ultrasound-guided core needle biopsy using a 4D US-System (Voluson 730, GE/Kretztechnik, Austria). The results were documented prospectively and compared to a matched series of 53 conventional 2D ultrasound-guided core biopsies. 4D ultrasound-guided biopsy can be performed using multiplanar views or a combination of cross-sectional and rendered images. Assessment of additional 3D images during the biopsy procedure was helpful in 34 % of the cases. In the differentiation of malignant and benign lesions, 4D ultrasound guided biopsy yielded 35 true-positive results, 12 true-negative results and 5 false-negative results. The sensitivity and specificity for the diagnosis of malignancy was 87.5 % and 94.4 %, respectively (control group: 89.5 % and 94.4 %). There was one case of insufficient tissue sampling in the 4D targeting group and 2 cases in the control group. No complications were observed related to the biopsy procedure. 4D ultrasound-guided biopsy is feasible and can improve visualisation of biopsy procedures by multiplanar display or 3D rendering. Although the accuracy is comparable to that of conventional 2D biopsy, this technique may be helpful for biopsy of lesions with close relation to relevant anatomical structures.
    Ultraschall in der Medizin 09/2006; 27(4):324-8. · 4.12 Impact Factor
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    ABSTRACT: Assessment of perfusion with 15O-labelled water (H215O) requires measurement of the arterial input function (AIF). The arterial time activity curve (TAC) measured using the peripheral sampling scheme requires corrections for delay and dispersion. In this study, parametrizations with and without arterial spillover correction for fitting of the tissue curve are evaluated. Additionally, a completely noninvasive method for generation of the AIF from a dynamic positron emission tomography (PET) acquisition is applied to assess perfusion of pelvic tumours. This method uses a volume of interest (VOI) to extract the TAC from the femoral artery. The VOI TAC is corrected for spillover using a separate tissue TAC and for recovery by determining the recovery coefficient on a coregistered CT data set. The techniques were applied in five patients with pelvic tumours who underwent a total of 11 examinations. Delay and dispersion correction of the blood TAC without arterial spillover correction yielded in seven examinations solutions inconsistent with physiology. Correction of arterial spillover increased the fitting accuracy and yielded consistent results in all patients. Generation of an AIF from PET image data was investigated as an alternative to arterial blood sampling and was shown to have an intrinsic potential to determine the AIF noninvasively and reproducibly. The AIF extracted from a VOI in a dynamic PET scan was similar in shape to the blood AIF but yielded significantly higher tissue perfusion values (mean of 104.0 +/- 52.0%) and lower partition coefficients (-31.6 +/- 24.2%). The perfusion values and partition coefficients determined with the VOI technique have to be corrected in order to compare the results with those of studies using a blood AIF.
    Physics in Medicine and Biology 07/2006; 51(11):2883-900. · 2.70 Impact Factor
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    ABSTRACT: The present study compares quality of life (QoL) after neoadjuvant radiochemotherapy with or without hyperthermia in patients with advanced rectal cancer. Between April 1994 and May 1999, 137 patients were treated by neoadjuvant radiochemotherapy with (69 patients (50.4%)) or without (68 patients (49.6%)) hyperthermia. Forty-six patients (33.6%) filled-out a 'Gastrointestinal Quality of Life Index' (GIQLI) questionnaire at four time points (before and after neoadjuvant therapy, early after surgery and after long-term follow-up) and were included in the present study. There were no statistically significant differences in the global GIQLI index between patients treated with neoadjuvant radiochemotherapy with and without hyperthermia at any time point. The longitudinal analysis of GIQLI values in both treatment groups showed specific profiles that were identical in both treatment groups. Occurrence of severe toxicity during the neoadjuvant therapy in both arms lead to a significant temporary reduction of QoL scores at TP2 without any detrimental long-term effects. Patients with sphincter preservation and patients with sphincter resection reported similar QoL scores during long-term follow-up. Neoadjuvant radiochemotherapy with and without hyperthermia has similar effects on the QoL of patients with locally advanced rectal cancer. The addition of hyperthermia during the neoadjuvant therapy with the potentially associated inconveniences has no negative effects on QoL.
    International Journal of Hyperthermia 07/2006; 22(4):301-18. · 2.59 Impact Factor
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    ABSTRACT: We studied the midbrain SERT availability in patients with major depression and assessed the relation of SERT occupancy by citalopram to the treatment response. 21 non-medicated patients with major depression and 13 healthy controls were examined by [(123)I]-ADAM SPECT. The midbrain SERT availability (SERT V(3)'') was calculated using individual MRI scans. In 13/21 patients SPECT was repeated 7 days after oral medication with citalopram (10 mg/day). We found no significant difference in the mean midbrain SERT availability between the studied patients with major depression and healthy controls (0.86 +/- 0.27 vs. 0.71 +/- 0.44, p = 0.069). The mean SERT occupancy accounted to 61%. The degree of SERT blockade by citalopram did not correlate with the reduction in HAMD total score. Treatment with low-dosed citalopram caused individually variable occupancy of the midbrain-SERT and a rapid clinical improvement in 54% of the investigated patients.
    Journal of Neural Transmission 06/2006; 113(5):659-70. · 3.05 Impact Factor
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    ABSTRACT: To characterize cystic pancreatic lesions and tumors with magnetic resonance imaging (MRI), and to assess the value of morphological criteria in differentiating pseudocysts versus cystic tumors and benign versus malignant cystic tumors. Twenty-three patients with cystic pancreatic tumors or lesions underwent plain and contrast-material-enhanced MRI, including magnetic resonance cholangiopancreatography (MRCP). The MR findings were characterized and analyzed by two readers, and the role of various imaging criteria and combinations thereof for final lesion assignment were assessed. Final diagnoses were obtained from the results of open surgery (n = 19) and/or biopsy (n = 4). Final diagnoses included cystic tumors (n = 11) and pseudocysts (n = 12). The lesions were located in the head (56%) and body or tail (44%). Lesion diameters ranged from 7 to 50 mm. Various lesion contrast enhancement patterns were observed for both benign and malignant lesions. Serous cystadenomas were located in the head, they were lobulated, and had wall diameters < or = 2 mm; with the combination of these characteristics all patients with serous cystadenoma could be identified, whereas in no other patient was this constellation observed. MRI facilitated the diagnosis of serous cystadenomas, although no definite morphologic criterion for the differentiation between pseudocysts and mucinous cystadenomas was identified. In consideration of the substantial therapeutic consequences, either diagnostics in unclear cystic pancreatic lesions should comprise cyst fluid analysis if necessary, or eligible patients should be referred for surgical resection.
    Acta Radiologica 03/2006; 47(2):121-9. · 1.33 Impact Factor
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    ABSTRACT: To determine the values of effective dose and partial body dose for the radiologist and the assistant during transarterial chemoembolization (TACE) of hepatocellular carcinoma (HCC) und to compare the doses with the dose limits. In 65 TACE of HCC cases, values of various surface doses for the radiologist and the assistant were measured. The measurements were performed with the help of thermoluminescence dosemeters (TLD) that were attached to the eyebrows, over the lobes of the thyroid gland, to the breasts, abdomen and symphysis, and to the hands and the lower legs. The measured surface dose values were used as indicators of the exposure of the organs and tissues located near the surface, i. e. eye lens, thyroid gland, breast, testes and tibia. They were also seen as conservative estimations of tissues deep inside the body and the extremities. The highest surface dose for the radiologist was measured at the lower leg (0.58 +/- 0.28 mSv) and the highest surface dose for the assistant was measured at the right lower leg (0.24 +/- 0.20 mSv) since it was closer to the tube than the left side, followed by the dose values at the also unprotected areas of the eyebrows, lobes of the thyroid gland and the hands. The estimated value of the effective dose was 0.06 +/- 0.03 mSv for the radiologist and 0.04 +/- 0.01 mSv for the assistant. With regard to the relationship between the dose limits according to the German X-ray regulation and the measured values and with regard to the maximum possible number of interventions per year, the partial body dose of the red bone marrow in the lower leg provided the greatest limitation, followed by the partial body dose of the muscle in the lower leg and the effective dose. In order to meet the dose limits, especially the lower leg should be protected, and the effective dose should also be reduced.
    RöFo - Fortschritte auf dem Gebiet der R 03/2006; 178(2):185-90. · 2.76 Impact Factor
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    ABSTRACT: This study assessed the value of image fusion with (18)F-fluorodeoxyglucose-positron emission tomography (FDG-PET) and magnetic resonance imaging (MRI) in patients suspected of having pancreatic cancer. 32 patients (12 women, 20 men; age 24-79 years; mean 56.6 years) were included. All patients underwent whole-body FDG-PET examinations and contrast-enhanced MRI. Image fusion used a semiautomatic voxel-based algorithm. Separate reading, side-by-side analysis and evaluation of fused PET/MRI images were performed. Results were correlated to histopathology (n = 30), or clinical follow-up (n = 2). 15/32 patients had pancreas cancer and 17/32 patients benign disease. The sensitivity and specificity for cancer detection by FDG-PET were 93 and 41% for visual and 86 and 58% for semiquantitative analysis whereas MRI achieved 100 and 76% respectively. Topographical assignment of PET foci by image fusion was superior to side-by-side analysis in 11/39 (28%) foci (in 8/32 patients). However, a true impact on therapeutic strategy was observed only in 1/8 patients as the presence of multiple metastases, irresectable primaries or medical reasons for inoperability prevented a curative setting. Compared to side-by-side analysis, PET/MRI image fusion improves the anatomical assignment and interpretation of FDG foci. The therapeutic benefit for the patient however is limited in patients with multiple lesions or incurable primaries.
    Pancreatology 02/2006; 6(6):512-9. · 2.04 Impact Factor
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    ABSTRACT: To evaluate the feasibility and potential advantages of the radiofrequency ablation of liver tumors using new MRI-compatible semiflexible applicators in a closed-bore high-field MRI scanner. We treated 8 patients with 12 malignant liver tumors of different origin (5 colorectal carcinoma, 2 cholangiocellular carcinoma, 1 breast cancer) under MRI guidance. Radiofrequency ablation (RFA) was performed using 5 cm Rita Starburst Semi-Flex applicators (Rita Medical Systems, Milwaukee, WI, USA) which are suitable for MR- and CT-guided interventions and a 150 W RF generator. All interventions were performed in a closed-bore 1.5 T high-field MRI scanner for MRI-guided RFA using fast T1-weighted gradient echo sequences and T2-weighted ultra-turbo spin echo sequences. Control and follow-up MRI examinations were performed on the next day, at 6 weeks, and every 3 months after RFA. Control MRI were performed as double-contrast MRI examinations (enhancement with iron oxide and gadopentetate dimeglumine). All interventions were performed with the patient under local anesthesia and analgo-sedation. The mean diameter of the treated hepatic tumors was 2.4 cm (+/-0.6 cm, range 1.0-3.2 cm). The mean diameter of induced necrosis was 3.1 cm (+/-0.4 cm). We achieved complete ablation in all patients. Follow-up examinations over a duration of 7 months (+/-1.3 months, range 4-9 month) showed a local control rate of 100% in this group of patients. All interventions were performed without major complications; only 2 subcapsular hematomas were documented. RFA of liver tumors using semiflexible applicators in closed-bore 1.5 T scanner systems is feasible. These applicators might simplify the RFA of liver tumors under MRI control. The stiff distal part of the applicator facilitates its repositioning.
    CardioVascular and Interventional Radiology 01/2006; 29(2):270-5. · 2.14 Impact Factor

Publication Stats

4k Citations
1,061.47 Total Impact Points


  • 1999–2007
    • Charité Universitätsmedizin Berlin
      • Department of Radiation Oncology and Radiotherapy
      Berlín, Berlin, Germany
  • 1995–2006
    • Humboldt University of Berlin
      • Department of Biology
      Berlin, Land Berlin, Germany
  • 2005
    • Universitätsklinikum Freiburg
      • Department of Radiation Medicine
      Freiburg, Lower Saxony, Germany
  • 1995–2002
    • Deutsches Herzzentrum Berlin
      • • Cardiothoracic and Vascular Surgery
      • • Department of Congenital Heart Disease / Pediatric Cardiology
      Berlín, Berlin, Germany
  • 2001
    • Max-Delbrück-Centrum für Molekulare Medizin
      Berlín, Berlin, Germany
  • 1998–2001
    • Technische Universität Berlin
      Berlín, Berlin, Germany
  • 1999–2000
    • Goethe-Universität Frankfurt am Main
      • • Institut für Diagnostische und Interventionelle Radiologie
      • • Zentrum der Inneren Medizin
      Frankfurt am Main, Hesse, Germany
  • 1985–2000
    • Freie Universität Berlin
      • Department of Oncology
      Berlín, Berlin, Germany
  • 1993
    • University of California, San Francisco
      San Francisco, California, United States