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P Mildenberger

Publications and source records attributed to P Mildenberger.

At least 19 recordsLinked to original sources
PubMed2006

[E-Learning in radiology; the practical use of the content management system ILIAS].

PURPOSE: Due to the possibility of using different kinds of visualization, e-learning has the advantage of allowing individualized learning. A check should be performed to determine whether the use of the web-based content management system ILIAS simplifies the writing and production of electronic learning modules in radiology. MATERIALS AND METHODS: Internet-based e-learning provides access to existing learning modules regardless of time and location, since fast Internet connections are readily available. RESULTS: Web Content Management Systems (WCMS) are suitable platforms for imparting radiology-related information (visual abilities like the recognition of patterns as well as interdisciplinary specialized knowledge). The open source product ILIAS is a free WCMS. It is used by many universities and is accepted by both students and lecturers. Its modular and object-oriented software architecture makes it easy to adapt and enlarge the platform. The employment of e-learning standards such as LOM and SCORM within ILIAS makes it possible to reuse contents, even if the platform has to be changed. CONCLUSION: ILIAS renders it possible to provide students with texts, images, or files of any other kind within a learning context which is defined by the lecturer. Students can check their acquired knowledge via online testing and receive direct performance feedback. The significant interest that students have shown in ILIAS proves that e-learning can be a useful addition to conventional learning methods.

Computer-Assisted Instruction↗
PubMed2006

The Public-Key-Infrastructure of the Radiological Society of Germany.

Pretty Good Privacy (PGP) encoding is based on the Public-Key-Procedure and permits the safe transmission of medical data. Furthermore it allows the use of an electronic signature provided that keys used belong to the key owner and that the key owner's identity is guaranteed by a trusted third party. Under the auspices of the Radiological Society of Germany (Deutsche Röntgengesellschaft, DRG) its IT-Working Group (Arbeitsgemeinschaft für Informationstechnik, @GIT) built up an appropriate Certification Authority including the required Public-Key-Infrastructure. These @GIT certified PGP keys allow the legal use of telemedicine in Germany. Digital signatures based to those certified keys correspond to the advanced signature according to the German Signature Law.

Algorithms↗
PubMed2005

Standardization of teleradiology using Dicom e-mail: recommendations of the German Radiology Society.

Until recently there has been no standard for an interoperable and manufacturer-independent protocol for secure teleradiology connections. This was one of the main reasons for the limited use of teleradiology in Germany. Various teleradiology solutions have been developed in the past, but the vast majority have not been interoperable. Therefore an ad hoc teleradiology connection was impossible even between partners who were already equipped with teleradiology workstations. Based on the evaluation of vendor-independent protocols in recent years the IT Working Group (AGIT) of the German Radiology Society set up an initiative to standardize basic teleradiology. An e-mail based solution using the Dicom standard for e-mail attachments with additional encryption according to the OpenPGP standard was found to be the common denominator. This protocol is easy to implement and safe for personalized patient data and fulfills the legal requirements for teleradiology in Germany and other countries. The first version of the recommendation was presented at the 85th German Radiology Convention in 2004. Eight commercial and three open-source implementations of the protocol are currently available; the protocol is in daily use in over 50 hospitals and institutions.

Computer Communication Networks↗
PubMed2005

[Current developments in DICOM and IHE].

The broadening use of imaging management systems in radiology and other disciplines is due in large part to the success of the DICOM standard (Digital Imaging and Communications in Medicine), which has been accepted worldwide for more than 10 years and meanwhile represents one of the most successful standards in medicine. The central intent of establishing the initiative "Integrating the Healthcare Enterprise" (IHE) was to ensure interoperability of different IT systems in medical processes. IHE is essentially based on widespread standards such as DICOM or HL7. This overview article briefly addresses the principles and organization of DICOM and IHE and describes the current developments in both domains.

Database Management Systems↗
PubMed2005

[Teleradiology with DICOM e-mail: recommendations of @GIT].

E-mail is ideal for ad-hoc connections in teleradiology. The DICOM standard offers the possibility to append DICOM data types as a MIME attachment to any e-mail, thus ensuring the transmission of the original DICOM data. Nevertheless, there are additional requirements (e.g. protection of data privacy) which must be obeyed. Because of the lack of given standards which would grant interoperability as well as manufacturer independence, teleradiology has not been established in Germany until today. Therefore, the IT-Team (Arbeitsgemeinschaft fur Informationstechnologie, @GIT) of the Radiological Society of Germany (Deutsche Rontgengesellschaft, DRG) set up an initiative to standardise telemedicine by using e-mail. Its members agreed that an e-mail-based variant would be the most practicable way to a communication solution -- as easy to implement as to use. In their opinion, e-mail represents the smallest common denominator for a safe data interchange that would fulfill the legal advantages for telemedicine in Germany.

Computer Communication Networks↗
PubMed2005

[Teleradiology according to the x-ray ordinance--exemplary application of the open source software SecTelMed].

PURPOSE: Establishing a teleradiology connection according to the Rontgenverordnung (RoV) between a peripheral hospital and a university clinic will contribute to improve the radiological emergency treatment on weekends, holidays and at night. It will also better the medical care for patients and help to lower the costs. MATERIALS AND METHODS: By using the open source software SecTelMed, the radiological picture is transferred via an internet-linked SSH communication server. The integration of the teleradiological data transfer into the actual workflow is attained by using the already existing PACS infrastructure. While its installation is still under construction, it is actually employed for transferring a patient's preliminary investigations and obtaining second opinions. RESULTS: The project proves a reliable and affordable teleradiology according with RoV by using open source software. The applied infrastructure ensures an unproblematical teleradiological treatment as well as a safe picture transfer for medical consulting (second opinion) even for large CT examinations of 1,000 pictures and more. CONCLUSION: The implementation of the technical requirements on teleradiology according with the Rontgenverordnung can be reliably attained by applying the open source software SecTelMed.

Computer Communication Networks↗
PubMed2005

[Prospective benefit and effect of lipiodol marking in hepatocellular carcinoma].

PURPOSE: To assess the benefit and the effect of intraarterial lipiodol application on histological analysis of patients suspected of having HCC. To determine whether lipiodol marking leads to a better biopsy result and how lipiodol or a transarterial chemoembolization influences the histological diagnosis. MATERIALS AND METHODS: Two groups of patients were examined. Group A included 14 patients highly suspected of having an HCC which had previously been unsuccessfully biopsied. A transarterial embolization with lipiodol was performed in these patients to mark intrahepatic tumors which could not otherwise be defined in unenhanced CT. A biopsy was then repeated. Group B included 22 patients undergoing therapy using transarterial chemoembolization (TACE). A biopsy was performed to support the diagnosis of a multifocal HCC before changing the therapy. RESULTS: The transversal diameters of the biopsied tumors were similar in both groups (A: 22 mm; B: 21 mm). The length of percutaneous access was 71 mm in Group A and 88 mm in Group B. In eleven of 14 patients of Group A we confirmed the diagnosis of an HCC. Thirty-six procedures were necessary for this confirmation. In Group B we confirmed the diagnosis in 17 of 22 patients. In addition, we found typical histological modification due to hepatic cirrhosis and virus hepatitis. Lipiodol had no negative influence on the histological diagnosis. CONCLUSION: Applying lipiodol for marking and delineating HCC-suspicious liver tumors in cases of formerly negative histology seems to enhance the success of biopsy, confirming the diagnosis of an HCC.

Aged↗
PubMed2004

Assessment of right ventricular function by 16-detector-row CT: comparison with magnetic resonance imaging.

The purpose of this study was to determine right ventricular (RV) function from 16-detector-row CT by using two different software tools in comparison with MRI. Nineteen patients underwent cardiac CT. (1) With semiautomated contour detection software end-diastolic and end-systolic RV volumes were determined from short-axis CT reformations (MPR) created at every 10% of the RR-interval. (2) End-systolic and end-diastolic axial images were transformed to 3D to determine the volumes by using a threshold-supported reconstruction algorithm. Steady-state free-precession cine-MRI of the heart was done in short-axis orientation. RV function could not be analyzed in one patient because of sternal wire artifacts in MRI. Mean end-diastolic (155.4+/-54.6 ml) and end-systolic (79.1+/-37.0 ml) RV volumes determined with MPR correlated well with MRI [151.9+/-53.7 ml (r=0.98) and 75.0+/-36.0 ml (r=0.96), respectively (P<0.001)]. RV stroke volume (76.2+/-20.2 ml for MPR-CT, 76.9+/-20.7 ml for MRI, r=0.93) showed a good correlation and RV ejection fraction (50.8+/-8.4% for MPR-CT, 51.9+/-7.4% for MRI, r=0.74) only a moderate one. Threshold supported 3D reconstructions revealed insufficient correlations with MRI (r=0.31-0.59). MPR-based semiautomated analysis of cardiac 16 detector-row CT allows for RV functional analysis. The results correlate well with MRI findings. Threshold value-supported 3D reconstructions did not show satisfying results because of inhomogeneities of RV contrast enhancement.

Aged↗
PubMed2004

[Experimental in vitro study to evaluate a flat-panel detector system].

PURPOSE: To evaluate the contrast-detail performance of a flat-panel detector system, we performed a comparative study of this flat-panel system versus storage phosphor and conventional screen-film systems. MATERIALS AND METHODS: Bone models made of human humeri were prepared with foreign bodies, fracture lines and drilled holes to create artificial fractures, osteolyses or metastases. Immersed in a water bath, hard copy images of these models were acquired with the same exposure dose (55 kV; 3.2 mAs) on the flat-panel detector, two state-of-the-art storage phosphor systems (PCR, ADC) and two conventional screen-film systems (Insight, T-Mat). Using a standardized protocol with a 4-point scale for a lesion, 220 different images were analyzed as to their appearance by 5 independent radiologists. The statistical significance of the differences between the used modalities and the observers was determined with a sign test. RESULTS: Especially the drilled holes showed differences between the modalities. The flat-panel detector showed significantly slightly better results locally than the two storage phosphor systems. The same applied to the Insight screen-film systems, but the intraindividual differences between the modalities were not clinically relevant. CONCLUSION: Under the conditions of the chosen experimental design, the flat-panel detector showed results comparable to the conventional screen-film and the state of the art storage phosphor radiographs. The use in skeletal radiography is possible.

Bezoars↗
PubMed2004

[Software-assisted CT-postprocessing of the carotid arteries].

PURPOSE: A software assistant for automatic evaluation of CT-angiograms (CTA) was developed. It should enable the visualization of the vessel lumen and the quantitative evaluation of a stenosis. CTA examinations of patients with suspected carotid artery stenoses were used for the evaluation of the software assistant. MATERIALS AND METHODS: Twelve Patients with suspected high-grade stenosis of the carotid arteries underwent a CTA examination using a multislice CT scanner. The data were analyzed and evaluated using the new software assistant. The results were compared with the data of digital subtraction angiography (DSA) of these patients. RESULTS: The time of digital postprocessing with the new software-assistant took about six minutes on average. Contour extraction of the vessel, MIP and curved MPR (c-MPR) and orthogonal cross-sectional images of the vessels were calculated, followed by an automatic quantification of stenosis by the use of the c-MPR. A good correlation was found between CTA and DSA data regarding the stenosis grade (r = 0.82). Furthermore, some information could be provided about the plaque morphology. CONCLUSION: The software-assisted detection and analysis of carotid artery stenosis with the new developed program is possible within a justifiable time. DSA- and CTA-data did not show a significant difference in stenosis grading. Further development of software tools could lead to a better characterization of plaque morphology.

Carotid Arteries↗
PubMed2004

[Non-invasive assessment of coronary artery bypass grafts -- an update].

The limited lifetime and the correlation between graft occlusion and recurring symptoms underline the need for repeated imaging of coronary artery bypass grafts. CT and MRI allow for non-invasive imaging of coronary bypasses with high accuracies concerning the patency of these vessels. Multidetector CT seems to be the CT technique of choice, especially after the introduction of 16 slice CT scanners for morphologic assessment of coronary artery bypass grafts. Compared with MRI, CT is a robust technique for assessment of cardiac anastomoses, native coronary arteries, and for the detection of graft stenoses. MRI, however, is able to deliver functional information about the grafts and the recipient coronary arteries by determining the coronary flow reserve. Furthermore, it can be integrated in a multiparametric MR examination protocol. The follow-up of asymptomatic patients can primarily be done by these non-invasive techniques as nearly every third patient reveals an asymptomatic bypass occlusion 5 years after operation. Furthermore, patients with atypical complaints after the operation may undergo non-invasive imaging as long as documented patency of the bypass averts coronary angiography. Patients with recurrent angina pectoris and/or myocardial ischemia discovered by other cardiologic tests have to undergo coronary angiography.

Coronary Artery Bypass↗
PubMed2004

[CT-angiography with a 16-row CT scanner for perioperative evaluation of the hepatic arteries].

PURPOSE: To evaluate the efficiency of CT angiography (CTA) with 16-row MSCT compared with MR angiography (MRA) in analyzing the arterial anatomy in patients undergoing liver surgery. MATERIALS AND METHODS: In 30 patients, MRA and CTA studies of the abdominal vessels were reviewed. CT parameters: slice thickness 3 mm; collimation 1.5; reconstruction interval 2 mm (Philips MX 8000 IDT); 120 ml contrast media (400 mg/ml) at a rate of 4 ml/sec; acquisition of arterial-phase scans. The anatomy of the hepatic artery was evaluated from axial and reconstructed maximum-intensity-projection (MIP) images ("Slab-Viewer", Philips). MR parameters: contrast-enhanced coronal FLASH-3D sequences; slice thickness 1.4 mm; TR 3.47, TE 1.3; 1.5 T scanner (Siemens Somatom). Image quality was rated with a scoring system. Contrast enhancement of the hepatic artery and the liver parenchyma was measured. RESULTS: The image quality of CTA was rated as excellent in 18 (MRA 5); good in 8 (MRA 22); satisfactory in 4 patients (MRA 3), and non-diagnostic in 0 patient (MRA 1). Compared to MRA, the image quality of CTA was better in 15/30 patients; equal for both in 13 and worse in 2 patients. CTA provided a better depiction of the segmental branches of the hepatic arteries in 15/30 patients and revealed important anatomic variations of the hepatic artery in 8/30 patients. These variations were not be seen in MRA: e. g., MRA missed a left gastric arterial supply to the left liver. The ratio of contrast enhancement in liver parenchyma and hepatic artery was 4.7 in CTA and 4.5 in MRA. CONCLUSION: CTA with multislice scanners delivers better image quality and depiction of the hepatic arteries than MRA. Thus, MRI of the hepatic arteries can be replaced by routine CT, which is already part of the preoperative evaluation for liver transplantation.

Angiography↗
PubMed2004

[Assessment of global and regional left ventricular function with a 16-slice spiral-CT using two different software tools for quantitative functional analysis and qualitative evaluation of wall motion changes in comparison with magnetic resonance imaging].

PURPOSE: To determine global and regional left ventricular (LV) function from retrospectively gated multidetector row computed tomography (CT) by using two different semiautomated analysis tools and to correlate the results with those of magnetic resonance imaging (MRI). MATERIALS AND METHODS: Nineteen patients (5 females, 14 males, mean age 69 years) underwent 16-slice spiral-CT (MS-CT) with standard technique without administration of beta-blockers for a decrease in the cardiac rate. Ten series of images were reconstructed at every 10 % of the RR-interval. With commercially available software capable of semiautomated contour detection, end-diastolic and end-systolic LV volumes (EDV and ESV) were determined from short-axis multiplanar CT reformations (MPR). Axial images of the end-systolic and end-diastolic cardiac phase were transformed to 3D volumes (3D) to determine EDV and ESV by using a threshold-supported reconstruction algorithm dependent on the contrast enhancement of the left ventricle. Steady-state free-precession cine MR images were acquired in short-axis orientation on the same day in all but one patient. Regional wall motion was assessed qualitatively in 17 left ventricular segments and classified as normo-, hypo-, a- or dyskinetic. Bland-Altman analysis was performed to calculate limits of agreement and systematic errors between CT and MRI. RESULTS: For MPR/3D, mean end-diastolic (144.4/142.8 mL +/- 67.5/67.1) and end-systolic (66.4/68.7 mL +/- 52.1/49.9) LV volumes as determined with MS-CT correlated well with MRI measurements (147.6 mL +/- 67.6 [ r = 0.98/0.96] and 73.3 mL +/- 55.5 [ r = 0.98/0.98], respectively [ p <.001]). LV stroke volume (77.6/74.1 +/- 19.2/23.4 mL for CT vs. 74.4 mL +/- 18.4 for MRI, r = 0.92/0.74) and LV ejection fraction (58.6/55.9 % +/- 13.5/13.7 for CT vs. 55.6 % +/- 13.5 for MRI, r = 0.95/0.91) also showed good correlation (p <.001). Regional wall motion analysis revealed agreement between CT and MRI in 316/323 (97.8 %) myocardial segments. CONCLUSION: Semiautomated analysis of 16-detector row CT data sets enables global and regional volumetric and functional analysis. The CT results correlate well with MRI findings for short axis MPR and for 3D volume reconstructions, with a higher statistical spread for the 3D method. The underestimation of end-systolic and end-diastolic volumes with CT may be caused by partial volume averaging due to the lower temporal resolution as compared with MRI.

Aged↗
PubMed2004

[Evaluation of a new software tool for the automatic volume calculation of hepatic tumors. First results].

PURPOSE: Computed tomography has become the preferred method in detecting liver carcinomas. The introduction of spiral CT added volumetric assessment of intrahepatic tumors, which was unattainable in the clinical routine with incremental CT due to complex planimetric revisions and excessive computing time. In an ongoing clinical study, a new software tool was tested for the automatic detection of tumor volume and the time needed for this procedure. MATERIALS AND METHODS: We analyzed patients suffering from hepatocellular carcinoma (HCC). All patients underwent treatment with repeated transcatheter chemoembolization of the hepatic arteria. The volumes of the HCC lesions detected in CT were measured with the new software tool in HepaVison (MeVis, Germany). The results were compared with manual planimetric calculation of the volume performed by three independent radiologists. RESULTS: Our first results in 16 patients show a correlation between the automatically and the manually calculated volumes (up to a difference of 2 ml) of 96.8 %. While the manual method of analyzing the volume of a lesion requires 2.5 minutes on average, the automatic method merely requires about 30 seconds of user interaction time. CONCLUSION: These preliminary results show a good correlation between automatic and manual calculations of the tumor volume. The new software tool requires less time for accurate determination of the tumor volume and can be applied in the daily clinical routine.

Algorithms↗
PubMed2003

[Virtual organization in the digital age of radiology - principle and solution for radiologic research?].

The research project "VICORA - Virtual Institute for Computer-Assisted Radiology", funded by the German Federal Ministry of Education and Research, was initiated in the year 2000. Its virtual organization brings together physical science, engineering, information technology, clinical radiology and the medical technology industry. In the German radiology research domain VICORA serves as a model for interdisciplinary collaboration for the changing radiology paradigm illustrated by a "radiologycube". The project does not only aim at scientific goals but also considers the infrastructure, components and human resource management within a virtual organization. The common rapid prototyping platform ILAB 4 ensures user-friendly and time-efficient software that assists with the routine radiology work-flow including full DICOM functionality. By offering a new work environment and collaborative culture based on telematics and knowledge exchange in radiology research, VICORA overcomes limitations of traditional research organization.

Diagnosis, Computer-Assisted↗
PubMed2002

[The current value of percutaneous transhepatic biliary drainage].

Percutaneous transhepatic biliary drainage (PTBD) is a well established method in the treatment of obstructive jaundice. Major indications are malignant diseases. PTBD may be necessary preoperatively in cases with severe jaundice or cholangitis or as part of palliative treatment concepts. In the past, it has been proposed that a period of preoperative PTBD may improve the morbidity rates of surgery. Various studies could not prove this theory. The significance of preoperative PTBD has changed, as observed during a 15 years period in our own institution, the indications for preoperative PTBD have decreased by half. At present, the majority of treatments with PTBD are palliative (almost 70 % of all procedures). The diagnostic opportunities of the transhepatic approach (intraductal sonography, cholangioscopy, biopsy) are exploited only in few selected cases. Since the radiological approach ist considered to be invasive and related to serious complications most patients are being referred to endoscopic drainage first. Radiologists are consulted in complicated cases of jaundice and when endoscopic approaches have failed. The retrospective evaluation of more than 1000 procedures over a period of 16 years demonstrates good results with a low rate of serious complications. During the two observed periods of nine and seven years, respectively, there occurred complications like sepsis in 1.9 %/0.5 %, peritonitis in 0.5 %/0.7 %, severe bleeding in 0.5 %/1.5 %, procedure-related death in 0.8 %/0.7 %. The overall rate of serious complications was 5 %/3.4 %. These results are comparable to those of the endoscopic approach with a complication rate of 3.6-14 % and a mortality rate of 0.5 %.

Cholangiography↗
PubMed2001

Periodontal probing in comparison to diagnosis by CT-scan.

AIM: To compare clinical periodontal probing and the corresponding CT-evaluation of the loss of bone. METHOD: 639 measurement sites were studied on 95 periodontal sites. The measured length was the distance between the cemento-enamel junction (CEJ) and the pocket base on probing and the bone base of the pocket on the CT-analysis. Additionally, a comparison of the diagnostic potential of both methods regarding the furcation involvement was made. RESULTS: Clinical probing depths showed a mean value of 2.6+/-2.0 mm, while the CT-measurements exhibited a figure of 4.2+/-2.3 mm. In 49.5% of the measured sites, the difference between clinical and CT-measurement was 2mm or higher. The greatest differences between the measured values were found on the buccal and lingual sites (P=0.0004). The narrower the vertical bone defects in the CT (angle in coronal direction), the greater were the differences between the clinical probing depths and the measurements carried out on the CT (P=0.02). Clinically, in 31% of the cases the furcation involvement was underestimated or not identified at all. CONCLUSION: Computed tomography imaging techniques could be beneficial in the field of periodontal diagnosis. The results underscore the higher accuracy of the CT-technique, compared with clinical probing, while assessing periodontal breakdown and its marked superiority in the diagnosis of furcation areas, compared to the clinical examinations performed.

Alveolar Bone Loss↗