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Holger Greess

Publications and source records attributed to Holger Greess.

12 recordsLinked to original sources
PubMed2006

Klinefelter syndrome and mediastinal germ cell tumors.

UNLABELLED: Precocious puberty is not a typical manifestation of patients with Klinefelter syndrome (KS). However, there is an increased incidence of mediastinal germ cell tumors (M-GCT) in KS, whereas the discussion of a generally higher tumor risk in this condition is still controversial. A rare subgroup of KS patients consists of prepubertal children with precocious puberty due to human chorionic gonadotropin (hCG)-producing M-GCTs. We present clinical data on a boy with KS and sexual precocity, and summarize the published data on 12 boys with KS out of 54 cases of KS and M-GCT. CLINICAL REPORT: an 8.5-year-old boy presented with signs of precocious puberty. Laboratory analyses (suppressed gonadotropins, elevated testosterone) and thoracic CT demonstrated a beta-human chorionic gonadotropin (beta-hCG) and alpha(1)-feto protein (alpha-FP) secreting mediastinal tumor. Histological analysis showed a mixed germ cell tumor comprising choriocarcinoma (CH), embryonal carcinoma (EC), mature teratoma (MT), and yolk sac tumor (YS). He was successfully treated by surgery and adjuvant chemotherapy. Epianalysis of published cases: all KS patients (n = 12), age 4-9 years, presented with precocious sexual development (PP), whereas the older ones showed thorax-associated symptoms, mainly chest pain, dyspnea, and cough. The histological distribution was also age-dependent with mixed germ cell tumors predominantly in younger patients. Thus, M-GCTs are strongly associated with precocious puberty in young boys with KS. Therefore, a karyotype analysis should be included in the clinical work-up of boys with precocious puberty and M-GCT. There is still no convincing explanation for the association of M-GCTs and KS.

Child↗
PubMed2006

www.tnt-radiology.de: Teach and be taught radiology: implementation of a web-based training program based on user preferences as determined by survery.

RATIONALE AND OBJECTIVES: To create a Web-based training program addressing the needs of a large, heterogeneous audience of users. MATERIALS AND METHODS: We defined our target group as consisting of medical professionals who teach radiology, or who, by their own perception, would benefit from improving their radiologic image interpretation skills. We interviewed 483 members of this group, eliciting their preferences with regard to layout, interactivity, contents, and other categories (11 in total). Considering majority preferences as recommendations and using the help of a special interest group of medical students, we assembled 500 teaching cases over a 1-year period into an interactive training program and made it available on the World Wide Web. RESULTS: Important preferences expressed by majorities of interviewees were: high levels of interactivity, clear layout, intuitive usability, short page load times, permissibility of saving content locally, cost-free access, consideration of user input in the site development. To our knowledge, our web program TNT-Radiology, accessible at , is the first to implement all of these recommendations simultaneously. CONCLUSIONS: We have created a Web-based program usable for teaching and learning radiologic image interpretation that meets the needs of a heterogeneous target audience to an unprecedented extent.

Computer-Assisted Instruction↗
PubMed2005

COMPARE/Radiology, an interactive Web-based radiology teaching program evaluation of user response.

RATIONALE AND OBJECTIVES: The aim of this study is to assess user benefits of COMPARE/Radiology, a highly interactive World Wide Web-based training program for radiology, as perceived by its users. MATERIALS AND METHODS: COMPARE/Radiology (http://www.idr.med.uni-erlangen.de/compare.htm), an interactive training program based on 244 teaching cases, was created by the authors and made publicly available on the Internet. An anonymous survey was conducted among users to investigate the composition of the program's user base and assess the acceptance of the training program. In parallel, Web access data were collected and analyzed using descriptive statistics. RESULTS: The group of responding users (n = 1370) consisted of 201 preclinical medical students (14.7%), 314 clinical medical students (22.9%), 359 residents in radiology (26.2%), and 205 users of other professions (14.9%). A majority of respondents (1230; 89%) rated the interactivity of COMPARE/Radiology as good or excellent. Many respondents use COMPARE/Radiology for self-study (971; 70%) and for teaching others (600; 43%). Web access statistics show an increase in number of site visits from 1248 in December 2002 to 4651 in April 2004. CONCLUSION: Users appreciate the benefits of COMPARE/Radiology. The interactive instructional design was rated positively by responding users. The popularity of the site is growing, evidenced by the number of network accesses during the observation period.

Computer-Assisted Instruction↗
PubMed2005

[Indications for validity of computed tomography and magnetic resonance imaging of the temporomandibular joint].

Recurrent pains of the temporomandibular joint represent a frequent symptom with numerous different causes. CT and MRI can reliably show the cause of these disorders and therefore have substituted conventional X-ray imaging. Modern multi-slice-CT (MSCT) allows for examination of the skull base including the mandible in a very short time with thinnest slice collimation (0.75mm). With 2D- and 3D-reformations reconstructed out of this volume data set in parasagittal, coronal or any other arbitrary slice orientation excellent imaging of fractures and bony changes of arthrosis as well as benign and malignant tumors of the temporomandibular joint can be performed. MRI offers very good soft tissue contrast in order to visualize the intra-articular disc, the ligaments and muscles, as well the possibility to acquire cross sectional images in any user-defined orientation. MRI is the method of choice to diagnose ,,internal derangement", particularly displacement of the intra-articular disc and inflammatory disease of the temporomandibular joint. The present paper will provide diagnostic strategies for the use of MSCT or MRI imaging concerning the different causes of disorders of the temporomandibular joint.

Arthralgia↗
PubMed2005

Ten years experience with piezoelectric extracorporeal shockwave lithotripsy of gallbladder stones.

BACKGROUND: A critical review of the experience with extracorporeal shockwave lithotripsy (ESWL) of gallbladder stones is needed to clarify whether this method should continue to be applied to patients. METHODS: Patients with symptomatic gallbladder stones were treated by piezoelectric ESWL according to a prospective protocol between 1988 and 1997. ESWL treatment was limited to a maximum of three (solitary stones <20 mm diameter) to five sessions (larger solitary or multiple stones) and 3000 pulses per session. Univariate and multivariate analyses of pretreatment and treatment variables were performed to investigate their impact on fragmentation efficacy and stone clearance. A tree-based analysis was used to identify prognostically homogenous subgroups of individuals with maximum benefit from ESWL. RESULTS: Four hundred and eight patients, 76% female and 24% male, with a mean age of 46 (SD, 13) years, were selected for evaluation. Cox regression analysis identified three pretreatment variables with significant prognostic impact: (1) number of gallstones >1 (relative risk, 2.6 (95% CI, 1.9-3.5)), (2) size of stones >17 mm (1.7 (1.4-2.2)), and (3) computed tomography (CT) density of stones >55 Hounsfield units (H) (1.4 (1.1-1.8)). According to tree-based analysis, the stone clearance rate after 1 year was 85% (95% CI, 75-91%) for solitary stones <16 mm, 79% (70-86%) for solitary stones > or =16 mm with a CT density <84 H, 45% (32-55%) for solitary stones > or =16 mm with a CT density > or =84 H, and 42% (30-51%) for multiple stones. Five years after stone clearance, recurrence occurred in 43% of patients (95% CI, 39-47%). CONCLUSIONS: ESWL treatment showed an acceptable stone clearance in the case of small solitary gallbladder stones (<16 mm) or larger solitary stones with a CT density <84 H, but a very low success rate in the case of multiple stones. The poor long-term success, however, is an important argument against the use of ESWL of gallbladder stones.

Adolescent↗
PubMed2005

Fat obliteration in paranasal sinuses: a comparative magnetic resonance imaging and histopathologic study.

OBJECTIVES: To assess postoperative changes after fat tissue obliteration of the paranasal sinuses with the use of magnetic resonance imaging (MRI) and correlate the findings with correspondent histology. STUDY DESIGN: By using an animal model with fat obliteration of the maxillary paranasal sinus. METHODS: We correlated postoperative changes of the fatty tissues by means of histopathologic analysis and MRI. The study group included 15 rabbits undergoing autologous fat tissue obliteration of their maxillary paranasal sinus. After 1 month (n = 5), 3 months (n = 5), and 6 months (n = 5), both MRI and histopathologic evaluations of the fatty tissue status were performed. Contrast enhanced MRI was used to identify vital fat tissue. Subsequently, MRI findings were compared with a correspondent histologic status and proliferative factors such as angio- and osteogenesis and presence of abundant granulocytes, macrophages, and giant cells. RESULTS: After a period of 6 months, the obliteration sites in all animals showed vital fat tissues, whereas at 1 month after surgery, vital fat tissue was rarely observed. The microscopic appearance of the obliteration tissue after 1 month was characterized by fat tissue necrosis and distinct tissue reactions including blood vessel dilatation, abundant macrophages, granulocytes, and lymphocytes. MRI after 1 month showed a clear contrast enhancement because of the hyperemia and inflammation reaction. CONCLUSION: Fat tissue transplants used for obliteration of paranasal sinuses are almost completely degraded after transplantation and replaced by vital fat tissue over a period of at least 6 months. Contrast enhanced MRI is a well-suited technique for follow-up imaging and assessing the transplant vascularization and tissue remodeling status.

Adipose Tissue↗
PubMed2005

Metastatic and inflammatory cervical lymph nodes as analyzed by contrast-enhanced color-coded Doppler ultrasonography: quantitative dynamic perfusion patterns and histopathologic correlation.

Use of contrast-enhanced color-coded Doppler (ultra)sonography (CCDS) in evaluating enlarged lymph nodes has been subject to numerous attempts to define criteria for differentiation between benign and malignant lesions. Evaluation of dynamic perfusion patterns with contrast-enhanced CCDS in cervical lymph nodes offers new possibilities of differential diagnosis. A total of 28 patients with clinically enlarged lymph nodes were included in this study. Contrast-enhanced CCDS was performed on each patient. The color signals from nodes <15 mm in diameter were analyzed with a specialized computer program. Each node was later examined through immunohistochemical staining. Vascularization as shown by unenhanced CCDS was significantly greater in metastatic lymph nodes than in reactively enlarged lymph nodes (8.66% versus 2.81%; p = .01). The maximum vascularization area after contrast injection did not show any significant change (26.61% versus 28.63%; p = .75). Comparison of values obtained before and after contrast enhancement showed the largest relative increase in vascularization in inflammatory lymph nodes, from a factor of 19.55 to a factor of 10.03 (p = .025). Dynamic values such as contrast enhancement, behavior of dynamic values referred to time, and the evaluated vascularized area did not show any significant difference. The metastatic lymph nodes (5.46 versus 3.33; p = .007) predominantly consisted of large blood vessels. The increased vascularization in the unenhanced CCDS examination of metastatic lymph nodes seems to be associated with the increased number of large blood vessels. An increased vessel density, due to a greater number of total vessels, is related to an inflammatory process. Color Doppler mapping has been proven to depict useful aspects distinguishing benign from malignant lymph nodes of the neck; however, a definitive differentiation between lymph nodes involved with malignancy and inflammatory changes remains difficult.

Adult↗
PubMed2004

Multiplanar functional imaging of the larynx and hypopharynx with multislice spiral CT.

The purpose of this study is to evaluate multislice spiral CT (MSCT) in multiplanar functional imaging of the larynx and hypopharynx and to define the optimal image planes for the delineation of the tumor and specific anatomical structures. Forty patients with suspected tumors of the larynx or hypopharynx were examined with MSCT during quiet breathing (QB), E-phonation (EP) and modified Valsalva maneuver (VM). Images were read in the axial, coronal and sagittal planes. Overall image quality, delineation of the tumor and anatomic structures for different conditions and orientations were graded using a three-point scale; the conditional permutation test was applied to detect quality differences. Differences between image types were statistically significant. The axial plane was superior in overall image quality and the delineation of the tumor, pyriform sinus, vocal cords and fat within the parapharyngeal/visceral space. The coronal plane was best for delineating the ventricle and the paraglottic space, the sagittal plane for the retropharyngeal and the preepiglottic space. For tumor detection, sensitivity, specificity and accuracy were 0.92, 1.0 and 0.93 for QB.ax, 0.94, 0.8 and 0.92 for EP.ax and 0.85, 1.0 and 0.87 for VM.ax, respectively. Examination during QB should be the standard procedure; additional scanning with EP improved tumor assessment.

Female↗
PubMed2004

Improvement of image quality of multislice spiral CT scans of the head and neck region using a raw data-based multidimensional adaptive filtering (MAF) technique.

The purpose was to evaluate the potential of the multidimensional adaptive filtering (MAF) technique by investigating its effects on image noise and image quality in multislice spiral CT (MSCT) examinations of the head and neck region. Fifty patients with head and neck tumors were examined using MSCT with a high resolution protocol. Reconstructions were performed using dedicated reconstruction software with a standard algorithm both without and with MAF using different modification. In all reconstructions, we measured the noise in seven different anatomical structures. The image quality and image noise were rated on a five-point scale. There was a significant (P<0.05) reduction in mean pixel noise in the reconstructions using MAF in comparison to the standard reconstructions, but there was no significant difference between the different modification fractions. With MAF the mean reduction in noise level was 60%, depending upon body shape and anatomical region. Independently from the used modification fraction, MAF led to a significant (P<0.05) improvement of image quality. In direct comparison of the different filter strength, the optimal image quality was achieved in the investigations with 15% MAF. The use of MAF facilitates the distinction of anatomical and pathological structures from artifacts in the supraclavicular fossae and the upper mediastinum, whereas the image quality of the upper portions of the neck remained unchanged. MAF improved image quality by reducing the noise level and removing noise structures without loss of image sharpness. This technique offers new perspectives to reduce the patient dose.

Adipose Tissue↗
PubMed2004

ELERA: a WWW application for evaluating and developing radiologic skills and knowledge.

RATIONALE AND OBJECTIVES: To provide an online facility for evaluating, comparing, and building expertise in radiologic anatomy and clinical radiology. MATERIALS AND METHODS: Project participants were recruited from an experienced special interest group of students at the local medical school. A rigid protocol was agreed upon, defining and assigning the tasks of case selection, data entry, test task creation, and peer review. The presentation of test tasks and evaluation of user input was implemented as a custom web application. RESULTS: ELERA, an online assessment and learning resource based on 1,650 pathologic cases and 550 anatomy cases, was created and made publicly accessible as a world wide web application. CONCLUSION: The project design facilitated the creation of a free, highly accessible and user-friendly resource that offers capabilities for individual longitudinal and intersubject comparative assessment.

Computer-Assisted Instruction↗
PubMed2002

Dose reduction in CT examination of children by an attenuation-based on-line modulation of tube current (CARE Dose).

In a controlled patient study we investigated the potential of attenuation-based on-line modulation of the tube current to reduce milliampere values (mAs) in CT examinations of children without loss of image quality. mAs can be reduced for non-circular patient cross sections without an increase in noise if tube current is reduced at those angular positions where the patient diameter and, consequently, attenuation are small. We investigated a technical approach with an attenuation-based on-line control for the tube current realised as a work-in-progress implementation. The CT projection data are analysed in real time to determine optimal mAs values for each projection angle. We evaluated mAs reduction for 100 spiral CT examinations with attenuation-based on-line modulation of the tube current in a group of children. Two radiologists evaluated image quality by visual interpretation in consensus. We compared the mAs values read from the CT scanner with preset mAs of a standard protocol. Four different scan regions were examined in spiral technique (neck, thorax, abdomen, thorax and abdomen). We found the mAs product to be reduced typically by 10-60% depending on patient geometry and anatomical regions. The mean reduction was 22.3% (neck 20%, thorax 23%, abdomen 23%, thorax and abdomen 22%). In general, no deterioration of image quality was observed. There was no correlation between the age and the mean mAs reduction in the different anatomical regions. By classifying the children respectively to their weight, there is a positive trend between increasing weight and mAs reduction. We conclude that mAs in spiral CT examinations of children can be reduced substantially by attenuation-based on-line modulation of the tube current without deterioration of image quality. Attenuation-based on-line modulation of tube current is efficient and practical for reducing dose exposure to children.

Adolescent↗