Martin Dobritz

Technische Universität München, München, Bavaria, Germany

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Publications (68)163.52 Total impact

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    ABSTRACT: Neoadjuvant chemotherapy is an accepted standard of care for locally advanced esophagogastric cancer. As only a subgroup benefits, a response-based tailored treatment would be of interest. The aim of our study was the evaluation of the prognostic and predictive value of clinical response in esophagogastric adenocarcinomas. Clinical response based on a combination of endoscopy and computed tomography (CT) scan was evaluated retrospectively within a prospective database in center A and then transferred to center B. A total of 686/740 (A) and 184/210 (B) patients, staged cT3/4, cN0/1 underwent neoadjuvant chemotherapy and were then re-staged by endoscopy and CT before undergoing tumor resection. Of 184 patients, 118 (B) additionally had an interim response assessment 4-6 weeks after the start of chemotherapy. In A, 479 patients (70 %) were defined as clinical nonresponders, 207 (30 %) as responders. Median survival was 38 months (nonresponders: 27 months, responders: 108 months, log-rank, p < 0.001). Clinical and histopathological response correlated significantly (p < 0.001). In multivariate analysis, clinical response was an independent prognostic factor (HR for death 1.4, 95 %CI 1.0-1.8, p = 0.032). In B, 140 patients (76 %) were nonresponders and 44 (24 %) responded. Median survival was 33 months, (nonresponders: 27 months, responders: not reached, p = 0.003). Interim clinical response evaluation (118 patients) also had prognostic impact (p = 0.008). Interim, preoperative clinical response and histopathological response correlated strongly (p < 0.001). Preoperative clinical response was an independent prognostic factor in center A, while in center B its prognostic value could only be confirmed in univariate analysis. The accordance with histopathological response was good in both centers, and interim clinical response evaluation showed comparable results to preoperative evaluation.
    Gastric Cancer 04/2014; · 3.99 Impact Factor
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    ABSTRACT: To develop a prototype algorithm for automatic spine segmentation in MDCT images and use it to automatically detect osteoporotic vertebral fractures. Cross-sectional routine thoracic and abdominal MDCT images of 71 patients including 8 males and 9 females with 25 osteoporotic vertebral fractures and longitudinal MDCT images of 9 patients with 18 incidental fractures in the follow-up MDCT were retrospectively selected. The spine segmentation algorithm localised and identified the vertebrae T5-L5. Each vertebra was automatically segmented by using corresponding vertebra surface shape models that were adapted to the original images. Anterior, middle, and posterior height of each vertebra was automatically determined; the anterior-posterior ratio (APR) and middle-posterior ratio (MPR) were computed. As the gold standard, radiologists graded vertebral fractures from T5 to L5 according to the Genant classification in consensus. Using ROC analysis to differentiate vertebrae without versus with prevalent fracture, AUC values of 0.84 and 0.83 were obtained for APR and MPR, respectively (p < 0.001). Longitudinal changes in APR and MPR were significantly different between vertebrae without versus with incidental fracture (ΔAPR: -8.5 % ± 8.6 % versus -1.6 % ± 4.2 %, p = 0.002; ΔMPR: -11.4 % ± 7.7 % versus -1.2 % ± 1.6 %, p < 0.001). This prototype algorithm may support radiologists in reporting currently underdiagnosed osteoporotic vertebral fractures so that appropriate therapy can be initiated. • This spine segmentation algorithm automatically localised, identified, and segmented the vertebrae in MDCT images. • Osteoporotic vertebral fractures could be automatically detected using this prototype algorithm. • The prototype algorithm helps radiologists to report underdiagnosed osteoporotic vertebral fractures.
    European Radiology 01/2014; · 4.34 Impact Factor
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    ABSTRACT: Recent data suggest primary resection as the preferable approach in patients with signet ring cell gastric cancer (SRC). The aim of our retrospective exploratory study was to evaluate the influence of SRC on prognosis and response in esophagogastric adenocarcinoma treated with neoadjuvant chemotherapy. A total of 723 locally advanced esophagogastric adenocarcinomas (cT3/4 N any) documented in a prospective database from two academic centers were classified according to the WHO definition for SRC (more than 50 % SRC) and analyzed for their association with response and prognosis after neoadjuvant treatment. A total of 235 tumors (32.5 %) contained SRC. Median survival of SRC was 26.3 compared with 46.6 months (p < 0.001) for non-SRC. SRC were significantly associated with female gender, gastric localization, advanced ypT and R1/2 categories, and lower risk of surgical complications and anastomotic leakage (each p < 0.001). Clinical (21.1 vs. 33.7 %, p = 0.001) and histopathological response (less than 10 % residual tumor: 16.3 vs. 28.9 %, p < 0.001) were significantly less frequent in SRC. Clinical response (p = 0.003) and complete histopathological response (pCR) (3.4 %) (p = 0.003) were associated with improved prognosis in SRC. Clinical response, surgical complications, ypTN categories, but not SRC were independent prognostic factors in forward Cox regression analysis in R0 resected patients. Risk of peritoneal carcinomatosis was increased (p < 0.001), while local (p = 0.015) and distant metastases (p = 0.02) were less frequent than in non-SRC. Prognosis of SRC is unfavorable. Although response to neoadjuvant chemotherapy is rare in SRC, it is associated with improved outcome. Thus, chemotherapy might not generally be abandoned in SRC. A stratification based on SRC should be included in clinical trials.
    Annals of Surgical Oncology 01/2014; · 4.12 Impact Factor
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    ABSTRACT: Evaluation of a new software tool for generation of simulated low-dose computed tomography (CT) images from an original higher dose scan.
    PLoS ONE 01/2014; 9(9):e107843. · 3.53 Impact Factor
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    ABSTRACT: PURPOSE Evaluation of a new software tool for generation of simulated low-dose computed tomography (CT) images from an original higher dose scan. METHOD AND MATERIALS Original contrast-enhanced and non-enhanced CT examinations (120 kVp; 100 mAs, 80 mAs, 60 mAs, 40 mAs, 20 mAs, and 10 mAs) of a swine were acquired. Simulations of CT images with a lower radiation exposure (range 10-80 mAs) were calculated using a low-dose simulation algorithm that simulates accurately both photon noise and electronic noise that would be present in a scan at lower dose. Simulated non-enhanced images were compared to the original non-enhanced CT data of the same radiation dose level regarding density values and image noise. Four radiologists assessed the visual appearance of the simulated contrast-enhanced CT data. RESULTS Image characteristics of simulated low-dose scans were similar to the original acquisitions. Mean overall discrepancy of image noise and CT values between original and simulated CT images was 0.2 % (range -0.6 % to 0.8 %) and -0.3 % (range -2.1 % to 0.8 %), respectively, p > 0.05. Subjective observer evaluation of image appearance showed no visually detectable difference. CONCLUSION Simulated low dose images showed excellent agreement with the original scan data concerning image noise, CT density values, and subjective assessment of the visual appearance of the simulated images. CLINICAL RELEVANCE/APPLICATION An authentic low-dose simulation from actual CT examinations opens up important opportunity with regard to staff education, protocol optimization and introduction of new reconstruction techniques.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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    ABSTRACT: PURPOSE To investigate the improvement in diagnostic quality of iterative model reconstruction (IMR) algorithm for sub-mSv computed tomography angiography of the pulmonary arteries (CTA). METHOD AND MATERIALS Eighteen patients (single-center, IRB approved) were imaged on a Philips Brilliance iCT (Philips, Cleveland, OH) for visualization of the pulmonary arteries, 8 with and 10 without pulmonary artery embolism. All scans were performed at 120 kVp (average effective doses 4.34±1.99mSv). Acquisitions with reduced radiation exposure were simulated from the original CT data to 15% of the tube current, resulting in a sub-mSv average dose of 0.65±0.30mSv. Filtered backprojection (FBP) was used to reconstruct the original data (protocol A); sub-mSv data were reconstructed using FBP (protocol B) and IMR (protocol C). The performance of IMR was assessed with respect to the image quality metrics image noise and contrast-to-noise ratio (CNR) and with respect to effective dose of each protocol. Two blinded readers determined subjective image quality and assessed the detectability of pulmonary artery embolism, where ground truth was obtained from protocol A. RESULTS With IMR noise could be subjectively removed, while the image texture (look and feel) of these images differed from FBP reconstructions. Specifically, with IMR, the noise is significantly reduced by a factor up to 20 (B vs. C). This is reflected by an improvement in the contrast-to-noise ratio and improved image quality with a median image quality score of 3 (IMR, B) vs. 1 (FBP, C), p < 0.05. With respect to diagnostics the angiographic datasets protocol A and C were identical, while B was worse: To detect pulmonary artery embolism in IMR and FBP low dose images, the sensitivity was 100% for IMR and 62.5% for FBP while specificity was 100% for both protocols. CONCLUSION This simulation study indicates that by using IMR for reconstruction, pulmonary artery embolism can be detected accurately in scans with sub-mSv dose levels. CLINICAL RELEVANCE/APPLICATION IMR has the potential to reduce patient dose and improve image quality in clinical day-to-day routine.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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    ABSTRACT: The diagnostic use of computer tomography angiography (CTA) to identify perforating blood vessels for abdominal free-flap breast reconstruction was extended to estimate the three-dimensional (3D) preoperative flap volume and to compare it with the real intraoperative flap weights in order to (1) evaluate the accuracy of CTA-based 3D flap volume prediction, and (2) to analyze abdominal tissue estimation for required breast volume reconstruction. Preoperative CTA was performed in 54 patients undergoing unilateral breast reconstruction with a free, deep, inferior epigastric artery perforator flap. 3D flap volumes ([Formula: see text]) based on CTA data were calculated and compared with the actual intraoperative flap weight (g). In addition, a breast volume to flap volume ratio was calculated to analyze whether the estimated 3D abdominal flap volume would match that of the breast to be removed. 40 CTA data sets (74.1 %) fulfilled the technical requirements for a reliable determination of flap volume. 3D CTA flap volume prediction showed no relevant differences to the actual flap weight (p = 0.44) and high correlations (r = 0.998, [Formula: see text]), allowing a prediction accuracy within 0.29 [Formula: see text] 3.0 % (range: from [Formula: see text]8.77 to 5.67 %) of the real flap weight. Significantly larger flap volumes were harvested compared with the actually required breast volumes ([Formula: see text]), leading to an average of 21 % of the remnant flap tissue potentially being discarded. CTA-based 3D flap volume prediction provides accurate preoperative guidelines concerning the needed amount of abdominal tissue that can be harvested to achieve acceptable symmetry.
    International Journal of Computer Assisted Radiology and Surgery 10/2013; · 1.36 Impact Factor
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    ABSTRACT: To improve the detection of liver lesions in patients with hepatocellular carcinoma (HCC) via an iodine contrast enhancement tool. Thirty-two patients with clinically proven HCCs underwent imaging with a three-phase protocol on a 256-slice MDCT. The contrast enhancement in the reconstructed slices was improved via a post-processing tool. Mean image noise was measured in four different regions: liver lesion, healthy liver, subcutaneous fat and bone. For each image set the image noise and contrast-to-noise ratio (CNR) were assessed. For subjective image assessment, four experienced radiologists evaluated the diagnostic quality. While employing the post-processing algorithm, CNR between the liver lesion and healthy liver tissue improves significantly by a factor of 1.78 (CNRwithout vC = 2.30 ± 1.92/CNRwith vC = 4.11 ± 3.05) (P* = 0.01). All results could be achieved without a strengthening of artefacts; mean HU values of subcutaneous fat and bone did not significantly change. Subjective image analysis illustrated a significant improvement when employing post-processing for clinically relevant criteria such as diagnostic confidence. With post-processing we see a significantly improved detection of arterial uptake in hepatic lesions compared with non-processed data. The improvement in CNR was confirmed by subjective image assessment for small lesions and for lesions with limited uptake. • Enhancement with iodine-based contrast agents is an essential part of CT. • A new post-processing tool significantly improves the diagnostics of hepatocellular carcinoma. • It also improves detection of small lesions with limited iodine uptake.
    European Radiology 09/2013; · 4.34 Impact Factor
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    ABSTRACT: Neoadjuvant chemotherapy for locally advanced gastric cancer leads to major histopathological response in less than 30 % of patients. Data on interim endoscopic response assessment do not exist. This exploratory prospective study evaluates early endoscopy after 50 % of the chemotherapy as predictor for later response and prognosis. Forty-seven consecutive patients were included (45 resected; 33 R0 resections). All patients received baseline endoscopy and CT scans, after 50 % of their chemotherapy (EGD-1, CT-1) and after completion of chemotherapy (EGD-2, CT-2). Interim endoscopic response (EGD-1) was assessed after having received 50 % (6 weeks) of the planned 12 weeks of neoadjuvant chemotherapy. Post-chemotherapy response was clinically assessed by a combination of CT scan (CT-2) and endoscopy (EGD-2). Histopathological response was determined by a standardized scoring system (Becker criteria). Endoscopic response was defined as a reduction of >75 % of the tumor mass. Twelve patients were responders at EGD-1 and 13 at EGD-2. Nine patients (19.1 %) were clinical responders and 7 patients (15.6 %) were histopathological responders after chemotherapy. Specificity, accuracy, and negative predictive value of the interim EGD-1 for subsequent histopathological response were 31/38 (82 %), 36/47 (76 %), and 31/33 (93 %); and for recurrence or death, 28/30 (93.3 %), 38/47 (80.9 %), and 28/35 (80.0 %). Response at EGD-1 was significantly associated with histopathological response (p = 0.010), survival (p < 0.001), and recurrence-free survival (p = 0.009). Interim endoscopy after 6 weeks predicts response and prognosis. Therefore, tailoring treatment according to interim endoscopic assessment could be feasible, but the findings of this study should be validated in a larger patient cohort.
    Gastric Cancer 09/2013; · 3.99 Impact Factor
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    ABSTRACT: The current common and dogmatic opinion is that whole-body computed tomography (WBCT) should not be performed in major trauma patients in shock. We aimed to assess whether WBCT during trauma-room treatment has any effect on the mortality of severely injured patients in shock. In a retrospective multicenter cohort study involving 16719 adult blunt major trauma patients we compared the survival of patients who were in moderate, severe or no shock (systolic blood pressure 90-110,<90 or >110 mmHg) at hospital admission and who received WBCT during resuscitation to those who did not. Using data derived from the 2002-2009 version of TraumaRegister®, we determined the observed and predicted mortality and calculated the standardized mortality ratio (SMR) as well as logistic regressions. 9233 (55.2%) of the 16719 patients received WBCT. The mean injury severity score was 28.8±12.1. The overall mortality rate was 17.4% (SMR = 0.85, 95%CI 0.81-0.89) for patients with WBCT and 21.4% (SMR = 0.98, 95%CI 0.94-1.02) for those without WBCT (p<0.001). 4280 (25.6%) patients were in moderate shock and 1821 (10.9%) in severe shock. The mortality rate for patients in moderate shock with WBCT was 18.1% (SMR 0.85, CI95% 0.78-0.93) compared to 22.6% (SMR 1.03, CI95% 0.94-1.12) to those without WBCT (p<0.001, p = 0.002 for the SMRs). The mortality rate for patients in severe shock with WBCT was 42.1% (SMR 0.99, CI95% 0.92-1.06) compared to 54.9% (SMR 1.10, CI95% 1.02-1.16) to those without WBCT (p<0.001, p = 0.049 for the SMRs). Adjusted logistic regression analyses showed that WBCT is an independent predictor for survival that significantly increases the chance of survival in patients in moderate shock (OR = 0.73; 95%CI 0.60-0.90, p = 0.002) as well as in severe shock (OR = 0.67; 95%CI 0.52-0.88, p = 0.004). The number needed to scan related to survival was 35 for all patients, 26 for those in moderate shock and 20 for those in severe shock. WBCT during trauma resuscitation significantly increased the survival in haemodynamically stable as well as in haemodynamically unstable major trauma patients. Thus, the application of WBCT in haemodynamically unstable severely injured patients seems to be safe, feasible and justified if performed quickly within a well-structured environment and by a well-organized trauma team.
    PLoS ONE 07/2013; 8(7):68880-. · 3.53 Impact Factor
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    ABSTRACT: BACKGROUND: The role of surgery for patients with metastatic esophagogastric adenocarcinoma (EGC) is not defined. The purpose of this study was to define selection criteria for patients who may benefit from resection following systemic chemotherapy. METHODS: From 1987 to 2007, 160 patients presenting with synchronous metastatic EGC (cT3/4 cNany cM0/1 finally pM1) were treated with chemotherapy followed by resection of the primary tumor and metastases. Clinical and histopathological data, site and number of metastases were analyzed. A prognostic score was established and validated in a second cohort from another academic center (n = 32). RESULTS: The median survival (MS) in cohort 1 was 13.6 months. Significant prognostic factors were grading (p = 0.046), ypT- (p = 0.001), ypN- (p = 0.011) and R-category (p = 0.015), lymphangiosis (p = 0.021), clinical (p = 0.004) and histopathological response (p = 0.006), but not localization or number of metastases. The addition of grading (G1/2:0 points; G3/4:1 points), clinical response (responder: 0; nonresponder: 1) and R-category (complete:0; R1:1; R2:2) defines two groups of patients with significantly different survival (p = 0.001) [low risk group (Score 0/1), n = 22: MS 35.3 months, 3-year-survival 47.6%); high risk group (Score 2/3/4) n = 126: MS 12.0 months, 3-year-survival 14.2%]. The score showed a strong trend in the validation cohort (p = 0.063) [low risk group (MS not reached, 3-year-survival 57.1%); high risk group (MS 19.9 months, 3-year-survival 6.7%)]. CONCLUSION: We observed long-term survival after resection of metastatic EGC. A simple clinical score may help to identify a subgroup of patients with a high chance of benefit from resection. However, the accurate estimation of achieving a complete resection, which is an integral element of the score, remains challenging.
    European journal of surgical oncology: the journal of the European Society of Surgical Oncology and the British Association of Surgical Oncology 01/2013; · 2.56 Impact Factor
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    ABSTRACT: Evaluation of 15,000 computed tomography (CT) examinations to investigate if iterative reconstruction (IR) reduces sustainably radiation exposure. Information from 15,000 CT examinations was collected, including all aspects of the exams such as scan parameter, patient information, and reconstruction instructions. The examinations were acquired between January 2010 and December 2012, while after 15 months a first generation IR algorithm was installed. To collect the necessary information from PACS, RIS, MPPS and structured reports a Dose Monitoring System was developed. To harvest all possible information an optical character recognition system was integrated, for example to collect information from the screenshot CT-dose report. The tool transfers all data to a database for further processing such as the calculation of effective dose and organ doses. To evaluate if IR provides a sustainable dose reduction, the effective dose values were statistically analyzed with respect to protocol type, diagnostic indication, and patient population. IR has the potential to reduce radiation dose significantly. Before clinical introduction of IR the average effective dose was 10.1±7.8mSv and with IR 8.9±7.1mSv (p*=0.01). Especially in CTA, with the possibility to use kV reduction protocols, such as in aortic CTAs (before IR: average14.2±7.8mSv; median11.4mSv /with IR:average9.9±7.4mSv; median7.4mSv), or pulmonary CTAs (before IR: average9.7±6.2mSV; median7.7mSv /with IR: average6.4±4.7mSv; median4.8mSv) the dose reduction effect is significant(p*=0.01). On the contrary for unenhanced low-dose scans of the cranial (for example sinuses) the reduction is not significant (before IR:average6.6±5.8mSv; median3.9mSv/with IR:average6.0±3.1mSV; median3.2mSv). The dose aspect remains a priority in CT research. Iterative reconstruction algorithms reduce sustainably and significantly radiation dose in the clinical routine. Our results illustrate that not only in studies with a limited number of patients but also in the clinical routine, IRs provide long-term dose saving.
    PLoS ONE 01/2013; 8(11):e81141. · 3.53 Impact Factor
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    ABSTRACT: OBJECTIVES: To investigate the improvement in diagnostic image quality of an iodine contrast enhancement tool in an animal model for computed tomography (CT). METHODS: One pig was examined over several consecutive days with a CT system. The quantity of iodine as contrast medium (0.6-1.2 ml/kg) varied among different acquisitions. The contrast enhancement in the reconstructed slices was improved via a post-processing tool. The post-processing tool is an algorithm designed for enhancement of iodine contrast in CT data. Contrast-to-noise ratio (CNR), the detectability between soft-tissue and vascular structures, and quantitative image analysis were assessed. RESULTS: When reducing the quantity of contrast medium, our subjective image quality assessment revealed that it is visually possible to generate similar enhancement with less iodine. This observation was confirmed quantitatively in our CNR results. While employing the algorithm, the CNR between vascular structures and subcutaneous fat significantly improved. For unenhanced regions, we identified no change in HU values and no significant strengthening of artefacts. CONCLUSIONS: With post-processing there was a significantly improved diagnostic image quality compared with non-processed data. In particular, similar contrast enhancement could be achieved with a reduced quantity of contrast medium injected during the CT acquisition. KEY POINTS : • Enhancement with iodine based contrast agents is an essential part of CT • A new post-processing tool significantly improves diagnostic image quality • It may also help reduce the iodine load required for intravenous enhancement.
    European Radiology 10/2012; · 4.34 Impact Factor
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    ABSTRACT: OBJECTIVES: To evaluate the utility of femoral bone mineral density (BMD) measurements in routine contrast-enhanced multi-detector computed tomography (ceMDCT) using dual-energy X-ray absorptiometry (DXA) as the reference standard. METHODS: Forty-one patients (33 women, 8 men) underwent DXA measurement of the proximal femur. Subsequently, transverse sections of routine ceMDCT of these patients were used to measure BMD of the femoral head and femoral neck. The MDCT-to-DXA conversion equations for BMD and T-score were calculated using linear regression analysis. The conversion equations were applied to the MDCT data sets of 382 patients (120 women, 262 men) of whom 74 had osteoporotic fractures. RESULTS: A correlation coefficient of r = 0.84 (P < 0.05) was calculated for BMD(MDCT) values of the femoral head and DXA T-scores of the total proximal femur using the conversion equation T-score = 0.021 × BMD(MDCT) - 5.90. The correlation coefficient for the femoral neck was r = 0.79 (P < 0.05) with the conversion equation T-score = 0.016 × BMD(MDCT) - 4.28. Accordingly, converted T-scores for the femoral neck in patients with versus those without osteoporotic fractures were significantly different (female, -1.83 versus -1.47; male, -1.86 versus -1.47; P < 0.05). CONCLUSION: BMD measurements of the proximal femur were computed in routine contrast-enhanced MDCT and converted to DXA T-scores, which adequately differentiated patients with and without osteoporotic fractures. KEY POINTS : • BMD measurements of the femur could be derived from routine abdominal ceMDCT. • Derived T-scores could differentiate patients with and without osteoporotic fractures. • Attenuation measurements in the femur in ceMDCT may predict fracture risk.
    European Radiology 08/2012; · 4.34 Impact Factor
  • M Dobritz
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    ABSTRACT: CLINICAL/METHODICAL ISSUE: Misinterpretations in liver diagnostics could result in a false diagnosis, such as a parenchymatous damage or a false focal lesion. STANDARD RADIOLOGICAL METHODS: Computed tomography is a widely used diagnostic tool to visualize liver diseases. METHODICAL INNOVATIONS: Magnetic resonance imaging (MRI) is often used as a second diagnostic test to answer specific questions. PERFORMANCE: The more the condition of changes in liver parenchyma appearance in cross-sectional imaging is known the fewer mistakes will be made in the interpretation. Knowledge of these pitfalls helps to increase diagnostic accuracy. ACHIEVEMENTS: Magnetic resonance imaging could help to depict most of the pitfalls. PRACTICAL RECOMMENDATIONS: By looking at diffuse or focal liver diseases radiologists should be aware of perfusion patterns and structural changes of the liver parenchyma to make a correct diagnosis.
    Der Radiologe 07/2012; 52(8):722-6. · 0.47 Impact Factor
  • Journal of Clinical Oncology 07/2012; 30(23):e209-12. · 18.04 Impact Factor
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    ABSTRACT: Pancreatic ductal adenocarcinoma (PDAC) is one of the five most lethal malignancies worldwide and survival has not improved substantially in the past 30 years. Desmoplasia (abundant fibrotic stroma) is a typical feature of PDAC in humans, and stromal activation commonly starts around precancerous lesions. It is becoming clear that this stromal tissue is not a bystander in disease progression. Cancer-stroma interactions effect tumorigenesis, angiogenesis, therapy resistance and possibly the metastatic spread of tumour cells. Therefore, targeting the tumour stroma, in combination with chemotherapy, is a promising new option for the treatment of PDAC. In this Review, we focus on four issues. First, how can stromal activity be used to detect early steps of pancreatic carcinogenesis? Second, what is the effect of perpetual pancreatic stellate cell activity on angiogenesis and tissue perfusion? Third, what are the (experimental) antifibrotic therapy options in PDAC? Fourth, what lessons can be learned from Langton's Ant (a simple mathematical model) regarding the unpredictability of genetically engineered mouse models?
    Nature Reviews Gastroenterology &#38 Hepatology 06/2012; 9(8):454-67. · 10.43 Impact Factor
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    ABSTRACT: Benign biliary stenosis can have various causes and requires differentiation from disorders caused by malignant disease. Treatment of benign stenosis is often difficult and includes treatment modalities such as endoscopic, percutaneous or surgical interventions. Exact knowledge of the etiology and localization of the stenosis is essential when selecting the appropriate method of treatment. Here we present the case of a 71-year-old patient admitted to our hospital with cholangitis 13 years after undergoing radiotherapy of the renal bed due to hypernephroma of the right kidney. The patient was diagnosed with common bile duct stenosis due to the secondary effects of radiation, which is rarely reported in the literature. Our case covers a total treatment period of 15 years, enabling us to also discuss a viable sequence of treatment modalities in the treatment of benign bile duct stenosis.
    Der Internist 04/2012; 53(7):874-81. · 0.33 Impact Factor
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    ABSTRACT: We obtained baseline and follow-up bone mineral density (BMD) values of the lumbar spine from sagittal reformations of routine abdominal contrast-enhanced multidetector computed tomography (MDCT) using a reference phantom and assessed their performance in differentiating patients with no, existing, and incidental osteoporotic fractures of the spine. A MDCT-to-QCT (quantitative computed tomography) conversion equation for lumbar BMD measurements was developed by using 15 postmenopausal women (63 ± 12 years), who underwent standard lumbar QCT (L1-L3) and afterward routine abdominal contrast-enhanced MDCT. Sagittal reformations were used for corresponding lumbar BMD measurements. The MDCT-to-QCT conversion equation was applied to baseline and follow-up routine abdominal contrast-enhanced MDCT scans of 149 postmenopausal women (63 ± 10 years). Their vertebral fracture status (no, existing, or incidental osteoporotic fracture) was assessed in the sagittal reformations. A correlation coefficient of r = 0.914 (p < 0.001) was calculated for the BMD values of MDCT and standard QCT with the conversion equation BMD(QCT) = 0.695 × BMD(MDCT) - 7.9 mg/mL. Mean follow-up time of the 149 patients was 20 ± 12 months. Fifteen patients (10.1 %) had an existing osteoporotic vertebral fracture at baseline. Incidental osteoporotic vertebral fractures were diagnosed in 13 patients (8.7 %). Patients with existing and incidental fractures showed significantly (p < 0.05) lower converted BMD values (averaged over L1-L3) than patients without fracture at baseline and at follow-up. In this longitudinal study, BMD values of the lumbar spine derived from sagittal reformations of routine abdominal contrast-enhanced MDCT predicted incidental osteoporotic vertebral fractures.
    Calcified Tissue International 04/2012; 90(6):481-7. · 2.75 Impact Factor
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    ABSTRACT: Despite recent advances in clinical imaging modalities, differentiation of pancreatic masses remains difficult. Here, we tested the diagnostic accuracy of molecular-based imaging including 3'-deoxy-3'-[(18)F]fluorothymidine (FLT) positron emission tomography (PET) and [(18)F]fluorodeoxyglucose (FDG) PET/CT in patients with suspected pancreatic masses scheduled to undergo surgery. A total of 46 patients with pancreatic tumours suspicious for malignancy and scheduled for resective surgery were recruited prospectively. In 41 patients, FLT PET and FDG PET/CT scans were performed. A diagnostic CT performed on a routine basis was available in 31 patients. FLT PET and FDG PET/CT emission images were acquired according to standard protocols. Tracer uptake in the tumour [FDG and FLT standardized uptake value (SUV)] was quantified by the region of interest (ROI) technique. For FDG PET/CT analysis, correct ROI placement was ensured via side-by-side reading of corresponding CT images. Of 41 patients, 33 had malignancy, whereas 8 patients had benign disease. Visual analysis of FDG and FLT PET resulted in sensitivity values of 91% (30/33) and 70% (23/33), respectively. Corresponding specificities were 50% (4/8) for FDG PET and 75% (6/8) for FLT PET. In the subgroup of patients with contrast-enhanced CT (n = 31), sensitivities were 96% (PET/CT), 88% (CT alone), 92% (FDG PET) and 72% (FLT PET), respectively. Mean FLT uptake in all malignant tumours was 3.0 (range SUV(max) 1.1-6.5; mean FDG SUV(max) 7.9, range 3.3-17.8; p < 0.001). For differentiation of pancreatic tumours, FDG PET and FDG PET/CT showed a higher sensitivity but lower specificity than FLT PET. Interestingly, visual analysis of FLT PET led to two false-positive findings by misinterpreting physiological bowel uptake as pathological FLT uptake in the pancreas. Due to the limited number of patients, the clinical value of adding FLT PET to the diagnostic workup of pancreatic tumours remains to be determined.
    European Journal of Nuclear Medicine 01/2012; 39(5):846-51. · 4.53 Impact Factor