Biomedical subjects

Rolf A Heckemann

Publications and source records attributed to Rolf A Heckemann.

5 recordsLinked to original sources

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↗

PubMed2003

COMPARE radiology: creating an interactive Web-based training program for radiology with multimedia authoring software.

RATIONALE AND OBJECTIVES: Computer-based training has two primary benefits: Content can be presented interactively, and students can choose the time, place, and pace of learning. As a subject of medical education, radiology lends itself particularly well to computer-based training because of its highly visual content. To improve the efficiency of radiology training at their institution, the authors decided to create an interactive Web-based training site. MATERIALS AND METHODS: Working with a group of medical students knowledgeable in multimedia authoring, the authors used authoring software to create "COMPARE Radiology," an interactive training program that follows the modality-based structure of the undergraduate curriculum for radiology at the University of Erlangen-Nuremberg, Erlangen, Germany, and at medical schools worldwide. RESULTS: The Web-based program offers cases and exercises in radiographic anatomy at different selectable levels of difficulty, allowing users to test and build their knowledge of radiology. Pathologic images are initially presented without any further information. Additional information (patient history, laboratory results, reports from other imaging studies, and normal images for comparison) can be retrieved selectively and successively. Further information regarding the diagnosis and pathologic findings can be found by following links to external Web sites. The COMPARE Radiology program content is extended and updated regularly. The program is subject to internal peer review and can be evaluated by the user online. CONCLUSION: The authors' experience shows that a highly interactive Web-based training program for radiology, tailored to the requirements of the target group, can be developed economically by a team of medical students using an advanced storing system, with the guidance of a radiologist and without the help of professionally trained computer experts.

Computer-Assisted Instruction↗

PubMed2002

Heterogeneous delayed enhancement of the liver after ultrasound contrast agent injection--a normal variant.

We report a characteristic heterogeneous delayed liver enhancement pattern that we have encountered in a total of 6 of approximately 1500 subjects who underwent contrast-enhanced liver ultrasonography. The heterogeneous enhancement occurred several min after contrast injection and persisted for up to 1 h. It was seen in diseased as well as healthy livers and appears to represent a "normal variant" of liver enhancement. It was observed with two different contrast agents. The cause of the described effect is unknown; it may be related to the formation of large bubbles and vascular entrapment of these bubbles in the liver.

Adult↗

PubMed2002

Which continuous US scanning mode is optimal for the detection of vascularity in liver lesions when enhanced with a second generation contrast agent?

OBJECTIVES: Microbubble echo-enhancers help in the assessment of focal liver masses by enhancing the signal from blood vessels. A variety of linear and nonlinear scanning modes are now available, but it is unclear which is optimal. A controlled comparison was performed during the infusion of such an agent (SonoVue: Bracco, Milan, Italy). METHODS AND MATERIALS: Ten patients with known focal liver lesions were studied. The diagnoses, confirmed on dual phase helical computed tomography (CT) at the same attendance were metastasis (n = 7), haemangioma (n = 2) and focal nodular hyperplasia FNH (n = 1). A dose of 12 ml SonoVue concentrated at 5 mg/ml was infused intravenously at a rate of 1 ml/min. The enhancement level was monitored with a continuous wave (CW) Doppler probe over the right radial artery and the intensity of the signal was registered at 1 s intervals. When a plateau of enhancement was reached, a single lesion in each patient was imaged using five different continuous scanning modes, fundamental grey scale (FGS); fundamental colour Doppler (FCD); fundamental power Doppler (FPD); second harmonic grey scale (HGS); and pulse inversion mode (Pim) using an HDI5000 scanner and C5-2 probe (ATL, Bothell, WA). The order of scanning modes was varied between patients using a predefined randomisation protocol. The videos (super video home system (SVHS)) were analysed offsite by two blinded readers, both experienced in contrast ultrasound of the liver. The readers were asked to score each mode in terms of its ability to detect vessels within/around the lesion at optimal enhancement. This was done using a ranking system (1, worst; 5, best) for each patient. RESULTS: Both observers scored FPD as the optimal imaging method, followed by Pim. (Scores summed across all patients, observer 1: FPD 48, Pim 42, FCD 37, HGS 21, FGS 10; observer 2: FPD 49, Pim 40, FCD 38, HGS 21, FGS 10). The differences from FPD were significant for FCD, HGS and FGS using a unpaired analysis of variance (ANOVA) comparison, with Bonferroni multiple corrections, (P<0.01, both observers). The differences between FPD and Pim were also significant both for observer 2 and for both observers combined (P<0.01), but did not reach significance for observer 1 (P = 0.19). CONCLUSIONS: In this study, FPD performed best, and the non-linear modes, performed continuously (pulse inversion and second HGS), showed no clear advantage.

Adult↗

PubMed2002

Enhancement characteristics of the microbubble agent Levovist: reproducibility and interaction with aspirin.

We investigated the reproducibility of Doppler enhancement indices following intravenous bolus injections of Levovist (Schering AG, Berlin) microbubbles. We also aimed to determine whether observations from animal studies suggesting that aspirin potentiates microbubble enhancement were reproducible in humans. In five healthy volunteers, time enhancement profiles of Doppler intensity following repeated bolus injections of Levovist were acquired from the common carotid artery, hepatic vein and kidney using spectral and power Doppler before and after oral aspirin (600 mg). Peak enhancement (PE), area under the curve (AUC) and decay slopes (lambda) were calculated. Hepatic vein contrast arrival time (AT) was determined subjectively. Well-defined carotid enhancement was seen in 19/20 injections. Reproducibility was high (r > 0.8). PE and AUG were unaffected by aspirin, but lambda was slightly reduced (P = 0.02). Renal power Doppler profiles were well defined (10/10) with no significant changes of AUC, PE or lambda after aspirin. Our study demonstrates good reproducibility of carotid spectral Doppler time intensitometry with Levovist in man. Aspirin does not have a significant effect on enhancement indices except carotid spectral Doppler decay. We conclude that aspirin is unlikely to potentiate microbubble enhancement, as seen in animal studies.

Adult↗