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Dive into the research topics where Stefan A. Schmidt is active.

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Featured researches published by Stefan A. Schmidt.


Scandinavian Journal of Gastroenterology | 2005

Contrast-enhanced wideband harmonic imaging ultrasound (SonoVue®): A new technique for quantifying bowel wall vascularity in Crohn's disease

Wolfgang Kratzer; Stefan A. Schmidt; Christoph Mittrach; Mark Martin Haenle; Richard Andrew Mason; Christian von Tirpitz; Sandra Pauls

Objective. To assess the possibility of quantitative determination of bowel wall vascularity using contrast-enhanced (SonoVue®) wideband harmonic imaging ultrasound and the HDI-Lab software in patients with Crohns disease. Material and methods. Twenty-one patients (13 F, 8 M, average age 33.8±12.7 years, range 21–60 years) with histologically confirmed Crohns disease and bowel wall thickness ≥5 mm were recruited for the study. All ultrasound examinations were performed using a Philips HDI 5000 scanner. Bowel wall vascularity was determined at the site of maximum bowel wall thickness at baseline and at 30, 60, 90 and 120 s following application of the contrast enhancer SonoVue (1.2 ml) using the HDI-Lab software. Results. The mean length of bowel segments exhibiting increased wall thickness was 122.3 mm (range: 23–350±74.7 mm), with a mean wall thickness of 7.6±1.2 mm. Onset of echo enhancement secondary to contrast medium application was observed after an average 13.4 s (range 7–19±4.2 s). Echo intensity corresponding to maximum vascularity was measured 30 s after application of contrast medium. Maximum average contrast medium uptake was 217.5% (range 118–466±100.1%). Conclusions. It is possible to quantify bowel wall vascularity accurately in patients with Crohns disease using contrast-enhanced pulse inversion ultrasound (low-MI).


European Journal of Radiology | 2012

Diffusion-weighted MR imaging in comparison to integrated [18F]-FDG PET/CT for N-staging in patients with lung cancer

Sandra Pauls; Stefan A. Schmidt; Markus S. Juchems; Oliver Klass; Markus Luster; Sven N. Reske; Hans-Juergen Brambs; Sebastian Feuerlein

PURPOSE The purpose of this study was to prospectively determine the diagnostic accuracy of diffusion-weighted imaging (DWI) using MRI in the staging of thoracic lymph nodes in patients with lung cancer, and to compare the performance to that of PET/CT. PATIENTS AND METHOD 20 consecutive patients (pts) with histologically proven lung cancer were included in this study. In all pts FDG-PET/CT was routinely performed to stage lung carcinoma. Additionally, MRI (1.5T) was performed including native T1w, T1w post contrast medium, T2w, and DWI sequences. Regarding the N stage based on the results of the PET/CT there were 5 patients with N0, 3 patients with N1, 5 patients with N2 and 7 patients with N3. Image analysis was performed by two radiologists (R1 and R2), respectively. The reviewers had to chose between 1 (at least one lymph node within a station is malignant) or 0 (no lymph nodes suspicious for malignancy). First the T1 post contrast sequence was analyzed. In a second step the DWI sequence (b=800) was analyzed. Both steps were performed in a blinded fashion. RESULTS MR imaging with or without DWI only agreed with the results of the PET/CT regarding the N stage in 80% of the patients-15% were understaged and 5% overstaged. There was excellent interobserver agreement; the N-staging result only differed in 1 patient for DWI, resulting in correlation coefficients of 0.98 for DWI and 1.0 for MRI. Compared to PET-CT MRI overstaged one and understaged 4 patients, while DWI overstaged one and understaged 3 patients. This resulted in correlation coefficients of 0.814 (R1 and R2) for MRI and 0.815 (R1) and 0.804 (R2) for DWI. Regarding the ADC values there were no significant differences between ipsilateral hilar (1.03 mm(2)/s ± 0.13), subcarinal (0.96 mm(2)/s±0.24), ipsilateral mediastinal (1.0mm(2)/s ± 0.18), contralateral mediastinal (0.93 mm(2)/s ± 0.23) and supraclavicular (0.9 mm(2)/s ± 0.23) lymph nodes. CONCLUSION Diffusion-weighted imaging does not show a clear advantage over conventional MR protocols in the N-staging of lung cancer. MRI with or without DWI shows a moderately correlation with PET/CT with a tendency for understaging.


European Radiology | 2008

CT-guided lung biopsy: incidence of pneumothorax after instillation of NaCl into the biopsy track

Christian Billich; Rainer Muche; Gerhard Brenner; Stefan A. Schmidt; Stefan Krüger; H.-J. Brambs; Sandra Pauls

This study was conducted to evaluate whether instillation of NaCl 0.9% solution into the biopsy track reduces the incidence of pneumothoraces after CT-guided lung biopsy. A total of 140 consecutive patients with pulmonary lesions were included in this prospective study. All patients were alternatingly assigned to one of two groups: group A in whom the puncture access was sealed by instillation of NaCl 0.9% solution during extraction of the guide needle (n = 70) or group B for whom no sealing was performed (n = 70). CT-guided biopsy was performed with a 18-G coaxial system. Localization of lesion (pleural, peripheral, central), lesion size, needle-pleural angle, rate of pneumothorax and alveolar hemorrhage were evaluated. In group A, the incidence of pneumothorax was lower compared to group B (8%, 6/70 patients vs. 34%, 24/70 patients; P < 0.001). All pneumothoraces occurred directly post punctionem after extraction of the guide needle. One patient in group A and eight patients in group B developed large pneumothoraces requiring chest tube placement (P = 0.01). The frequency of pneumothorax was independent of other variables. After CT-guided biopsy, instillation of NaCl 0.9% solution into the puncture access during extraction of the needle significantly reduces the incidence of pneumothorax.


Neoplasia | 2015

Frequence, Spectrum and Prognostic Impact of Additional Malignancies in Patients With Gastrointestinal Stromal Tumors

Klaus Kramer; S. Wolf; Benjamin Mayer; Stefan A. Schmidt; Abbas Agaimy; Doris Henne-Bruns; Uwe Knippschild; Matthias Schwab; Michael Schmieder

Currently available data on prognostic implication of additional neoplasms in GIST miss comprehensive information on patient outcome with regard to overall or disease specific and disease free survival. Registry data of GIST patients with and without additional neoplasm were compared in retrospective case series. We investigated a total of 836 patients from the multi-center Ulmer GIST registry. Additionally, a second cohort encompassing 143 consecutively recruited patients of a single oncology center were analyzed. The frequency of additional malignant neoplasms in GIST patients was 31.9% and 42.0% in both cohorts with a mean follow-up time of 54 and 65 months (median 48 and 60 months), respectively. The spectrum of additional neoplasms in both cohorts encompasses gastrointestinal tumors (43.5%), uro-genital and breast cancers (34.1%), hematological malignancies (7.3%), skin cancer (7.3%) and others. Additional neoplasms have had a significant impact on patient outcome. The five year overall survival in GIST with additional malignant neoplasms (n = 267) was 62.8% compared to 83.4% in patients without other tumors (n = 569) (P < .001, HR=0.397, 95% CI: 0.298-0.530). Five-year disease specific survival was not different between both groups (90.8% versus 90.9%). 34.2% of all deaths (n = 66 of n = 193) were GIST-related. The presented data suggest a close association between the duration of follow-up and the rate of additional malignancies in GIST patients. Moreover the data indicate a strong impact of additional malignant neoplasms in GIST on patient outcome. A comprehensive follow-up strategy of GIST patients appears to be warranted.


Injury-international Journal of The Care of The Injured | 2016

Pelvic X-ray misses out on detecting sacral fractures in the elderly – Importance of CT imaging in blunt pelvic trauma

Andreas Schicho; Stefan A. Schmidt; Kevin Seeber; Alain Olivier; Peter Richter; Florian Gebhard

Patients aged 75 years and older with blunt pelvic trauma are frequently seen in the ER. The standard diagnostic tool in these patients is the plain a.p.-radiograph of the pelvis. Especially lesions of the posterior pelvic ring are often missed due to e.g. bowel gas projection and enteric overlay. With a retrospective study covering these patients over a 3 year period in our level I trauma centre, we were able to evaluate the rate of missed injuries in the a.p.-radiograph whenever a corresponding CT scan was performed. Age, gender, and accompanying fractures of the pelvic ring were recorded. The intrinsic test characteristics and the performance in the population were calculated according to standard formulas. Thus, 233 consecutive patients with blunt pelvic trauma with both conventional radiographic examination and computed tomography (CT) were included. Thereof, 56 (23%) showed a sacral fracture in the CT scan. Of 233 pelvic X-ray-images taken, 227 showed no sacral fracture. 51 (21.7%) of these were false negative, yielding a sensitivity of just 10.5%. Average age of patients with sacral fractures was 85.1±6.1 years, with 88% being female. Sacral fractures were often accompanied by lesions of the anterior pelvic ring with pubic bone fractures in 75% of sacrum fracture cases. Second most concomitant fractures are found at the acetabulum (23.3%). Plain radiographic imaging is especially likely to miss out fractures of the posterior pelvic ring, which nowadays can be of therapeutic consequence. Besides the physicians experience in the ED, profound knowledge of insensitivity of plain radiographs in finding posterior pelvic ring lesions is crucial for a reliable diagnostic routine. Since the high mortality caused by prolonged immobilisation due to pelvic ring injuries, all fractures should be identified. We therefore provide a diagnostic algorithm for blunt pelvic trauma in the elderly.


World Journal of Gastroenterology | 2015

Parameters affecting different acoustic radiation force impulse applications in the diagnosis of fibrotic liver changes

Sabrina Galgenmueller; Heike Jaeger; Wolfgang Kratzer; Stefan A. Schmidt; Suemeyra Oeztuerk; Mark Martin Haenle; Richard Andrew Mason; Tilmann Graeter

AIM To analyze the virtual touch tissue quantification (VTTQ) and virtual touch imaging quantification (VTIQ) techniques, and identify possible factors that may influence VTTQ and VTIQ measurements. METHODS One hundred and eighty-six (104 women/82 men) of 323 subjects met the inclusion criteria (age > 18 years, no history of chronic or gastrointestinal disease, body-mass index (BMI) < 30 kg/m², a fasting period of at least three hours, no history of hepatotoxic pharmaceuticals, alcohol consumption < 24 g/d in men and < 12 g/d in women, and normal findings upon ultrasound examination of the abdomen). Measurements were taken at depths of 50 mm with VTTQ, 15 mm and 25 mm with VTIQ in the right hepatic lobe, and at 15 mm with only VTIQ in the left hepatic lobe. The examiner acquired six measurements per position, thereby giving 24 measurements in total. RESULTS The 95% confidence intervals of mean were 1.23-1.29 m/s for VTTQ and 1.29-1.37 m/s, 1.17-1.23 m/s, and 1.48-1.57 m/s for VTIQ in a depth of 15 mm and 25 mm in the right hepatic lobe and 15 mm in the left hepatic lobe. Only superficial measurements in the right hepatic lobe with the VTIQ method exhibited an effect of age on shear wave velocity. Measurements acquired using the 6C1 probe with the VTTQ method showed no dependence on BMI. By comparison, BMI influenced measurements taken with the VTIQ method using the 9L4 probe in the superficial and deep areas of the right hepatic lobe, as well as in the left hepatic lobe (P = 0.0160, P = 0.0019, P = 0.0173, respectively). Gender influenced measurements at depths of 50 mm with VTTQ and 25 mm with VTIQ in the right hepatic lobe (P = 0.0001, P = 0.0269). Significant differences were found between measurements with the 6C1 (VTTQ) and 9L4 probes (VTIQ) (P = 0.0067), between superficial and deep measurements (P < 0.0001), and between the right and left lobes of the liver (P < 0.0001). CONCLUSION Measurements in the right lobe and deep regions are preferable. Gender differences must be considered. BMI must be considered when assessing VTIQ technology.


Clinical Imaging | 2008

Assessment of pneumonia severity: multidetector-row CT in comparison to clinical score CRB-65

Sandra Pauls; Stefan Krüger; Rainer Muche; Daisy Klemen; Christian Billich; Susanne Gerstner; Stefan A. Schmidt; Vinzenz Hombach; H.-J. Brambs

This study involved 92 patients with clinically diagnosed pneumonia. Differences in the frequency of typical pattern were calculated for patients with mild pneumonia and for patients with severe pneumonia (confusion, respiratory rate, blood pressure, 65 years of age and older). The frequency of singular morphologic changes did not differ significantly between the two groups. Empyema and pleural effusion, as well as an atelectasis in combination with patchy infiltrates and a positive bronchogram/multisegmental infiltrates, seem to have an influence on severity of pneumonia.


Visceral medicine | 2018

Overstaging: A Challenge in Rectal Cancer Treatment

Jan Scheele; Stefan A. Schmidt; Sandra Tenzer; Doris Henne-Bruns; Marko Kornmann

Background: Preoperative staging, including computed tomography (CT), magnetic resonance imaging (MRI), and endoscopic ultrasound (EUS), is decisive to envisage the therapeutic concept for rectal cancer (RC). Overstaging may subject the patient to neoadjuvant therapy that does not improve survival but may lead to therapy-associated morbidity. Methods: This study retrospectively compares and values EUS, CT, and MRI in Union Internationale Contre le Cancer (UICC) stage I-III RC with a focus on overstaging. RC patients receiving primary operation only at the University Clinic Ulm were analyzed. The therapeutic relevance of preoperative staging was determined by comparison with postoperative pathological workup. Results: 244 examinations in 184 RC patients (EUS: n = 63, CT: n = 143, MRI: n = 38) revealed therapy-relevant overstaging into the T3/4 category in 10 (16%) EUS, 18 (13%) CT, and 10 (26%) MRI cases. Patients were upgraded to the N+ category in 13 (21%) EUS, 29 (20%) CT, and 11 (29%) MRI cases. As a result, UICC stages II and III turned out to be overstaged in 13 (21%) EUS, 18 (13%) CT, and 10 (26%) MRI cases. Conclusion: More than 10% therapy-relevant overstaging by any method represents a major challenge for modern RC therapy. Physicians should scrupulously consider this fact in their treatment considerations to avoid overtreatment.


International Journal of Surgery Case Reports | 2016

Challenging the limits in pancreatic surgery: A case report

Johannes Lemke; Stefan A. Schmidt; Marko Kornmann; Karl-Heinz Orend; Doris Henne-Bruns

Highlights • Despite the great progress remains challenging in many cases due to proximity of main vascular structures.• This unique cases demonstrates the complex surgical procedure of a partial pancreaticoduodenectomy in combination with a mesenterico-caval shunt.• Autoimmune pancreatitis is a relevant differential diagnosis of pancreatic conditions which may require complex surgical approaches.


International Journal of Surgery Case Reports | 2015

Ectopic spleen and liver hemangioma mimicking metastatic pancreatic neuroendocrine tumor.

Christine C. Engler; Johannes Lemke; Marko Kornmann; Thomas F. E. Barth; Stefan A. Schmidt; Doris Henne-Bruns

Highlights • IPAS (intrapancreatic accessory spleen) can mimic pancreatic neuroendocrine tumors in nuclear imaging, such as Dotatate PET-CT, due to somatostatine-receptor positivity of intrasplenic lymphocytes.• Non-invasive differentiation between intrapancreatic accessory spleens and pancreatic neuroendocrine tumors can be provided by using 99mTc-sulphur-colloid or 99mTc-tagged heat-damaged RBC Scintigraphy.• Extended preoperative radiological and nuclear medical examinations play a key role in properly differentiating suspect intrapancreatic lesions from intrapancreatic accessory spleens and prevent patients from unnecessary surgery.• We consider intrapancreatic accessory spleens a relevant differential diagnosis in patients with suspected pancreatic neuroendocrine tumors of the pancreatic tail, which should be taken into account before surgery is provided.

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