Effectiveness of a Brief Teaching Scenario in a Phantom-Based Learning Model for Students to Achieve Ultrasound-Guided Vascular Access—a Prospective Study

For students, early hands-on experience is very limited and often non-existent during study time. Thus, we aimed to evaluate the progress of inexperienced medical students in successfully establishing an ultrasound-guided vessel access. One brief, condensed single teaching lesson in a prior to post-teaching scenario was performed using an inexpensive, self-made phantom model. In this prospective study, medical students (n = 11) with no experience in ultrasound imaging performed an ultrasound-guided vessel access simulated by a gelatin-based phantom model. Success rates and time of procedures were measured. Afterwards, participants underwent dedicated supervised teaching in a single lesson (duration 30 min) with both theoretical information given and practical training skills shown. Then, every student performed the very same procedure again and results were compared with paired t test. Success rate of guide wire placement rose from 36.4 (4/11) to 100%. Mean number of attempts significantly decreased with 2.5 SD1.3 before and 1.2 SD0.4 after teaching (p < 0.05). Overall time to successful guide wire placement improved from 291 SD8 to 151 SD37 s (p < 0.05). With already limited training time and opportunities available during medical education, short and simple, but highly effective training tools are invaluable. With the help of an inexpensive, self-made gelatin-based phantom model for ultrasound-guided vascular access, medical students demonstrate significantly improved practical puncture skills after only one brief, condensed teaching lesson and thus an important progress with regard to their future clinical routine. The performance of ultrasound-guided vascular access can be highly improved for inexperienced medical students by applying one short teaching session using an inexpensive, self-made phantom model

Diffusion-weighted MRI improves response assessment after definitive radiotherapy in patients with NSCLC

Background Computed tomography (CT) is the standard procedure for follow-up of non-small-cell lung cancer (NSCLC) after radiochemotherapy. CT has difficulties differentiating between tumor, atelectasis and radiation induced lung toxicity (RILT). Diffusion-weighted imaging (DWI) may enable a more accurate detection of vital tumor tissue. The aim of this study was to determine the diagnostic value of MRI versus CT in the follow-up of NSCLC. Methods Twelve patients with NSCLC stages I-III scheduled for radiochemotherapy were enrolled in this prospective study. CT with i.v. contrast agent and non enhanced MRI were performed before and 3, 6 and 12 months after treatment. Standardized ROIs were used to determine the apparent diffusion weighted coefficient (ADC) within the tumor. Tumor size was assessed by the longest longitudinal diameter (LD) and tumor volume on DWI and CT. RILT was assessed on a 4-point-score in breath-triggered T2-TSE and CT. Results There was no significant difference regarding LD and tumor volume between MRI and CT (p ≥ 0.6221, respectively p ≥ 0.25). Evaluation of RILT showed a very high correlation between MRI and CT at 3 (r = 0.8750) and 12 months (r = 0.903). Assessment of the ADC values suggested that patients with a good tumor response have higher ADC values than non-responders. Conclusions DWI is equivalent to CT for tumor volume determination in patients with NSCLC during follow up. The extent of RILT can be reliably determined by MRI. DWI could become a beneficial method to assess tumor response more accurately. ADC values may be useful as a prognostic marker

Polyimide foam-like microstructures: technology and mechanical properties

We report a process for the realization of polyimide films with custom-designed microporosity based on the heat-induced depolymerization of polyimide-embedded polypropylene carbonate microstructures. The foam-like microstructures are up to 40 µm thick and incorporate air cavities with a width ranging from 20 to 200 µm, a length up to 5 mm and a height of 20 µm. We model the mechanical stress–strain properties of the microcavities using both analytical and numerical methods. The simulation data are in good agreement with the results of nanoindentation and microcompression experiments, which show the reduction of the effective Young's modulus from 5.77 ± 0.06 GPa for bulk polyimide to 2.51 ± 0.03 GPa for a foam-like layer

The Impact of Diffusion-Weighted MRI on the Definition of Gross Tumor Volume in Radiotherapy of Non-Small-Cell Lung Cancer.

OBJECTIVE:The study was designed to evaluate diffusion-weighted magnetic resonance imaging (DWI) vs. PET-CT of the thorax in the determination of gross tumor volume (GTV) in radiotherapy planning of non-small-cell lung cancer (NSCLC). MATERIALS AND METHODS:Eligible patients with NSCLC who were supposed to receive definitive radio(chemo)therapy were prospectively recruited. For MRI, a respiratory gated T2-weighted sequence in axial orientation and non-gated DWI (b = 0, 800, 1,400 and apparent diffusion coefficient map [ADC]) were acquired on a 1.5 Tesla scanner. Primary tumors were delineated on FDG-PET/CT (stGTV) and DWI images (dwGTV). The definition of stGTV was based on the CT and visually adapted to the FDG-PET component if indicated (e.g., in atelectasis). For DWI, dwGTV was visually determined and adjusted for anatomical plausibility on T2w sequences. Beside a statistical comparison of stGTV and dwGTB, spatial agreement was determined with the "Hausdorff-Distance" (HD) and the "Dice Similarity Coefficient" (DSC). RESULTS:Fifteen patients (one patient with two synchronous NSCLC) were evaluated. For 16 primary tumors with UICC stages I (n = 4), II (n = 3), IIIA (n = 2) and IIIB (n = 7) mean values for dwGTV were significantly larger than those of stGTV (76.6 ± 84.5 ml vs. 66.6 ± 75.2 ml, p<0.01). The correlation of stGTV and dwGTV was highly significant (r = 0.995, p<0.001). Yet, some considerable volume deviations between these two methods were observed (median 27.5%, range 0.4-52.1%). An acceptable agreement between dwGTV and stGTV regarding the spatial extent of primary tumors was found (average HD: 2.25 ± 0.7 mm; DC 0.68 ± 0.09). CONCLUSION:The overall level of agreement between PET-CT and MRI based GTV definition is acceptable. Tumor volumes may differ considerably in single cases. DWI-derived GTVs are significantly, yet modestly, larger than their PET-CT based counterparts. Prospective studies to assess the safety and efficacy of DWI-based radiotherapy planning in NSCLC are warranted

Aquam in altum exprimere

Les machines élévatrices d’eau ont été pendant longtemps méconnues dans l’Antiquité romaine car seule comptait l’eau courante et abondante amenée par les aqueducs. Pourtant de nombreux sites en ont livré plusieurs exemples depuis le xixe s., témoignages de la diversité des techniques. Ces dernières années, les découvertes se sont multipliées et permettent d’appréhender ces éléments fragiles car faisant souvent appel au bois, avec les méthodes d’étude les plus récentes. La Table-ronde organisée à Ausonius en 2003 a permis de faire le point de l’état des connaissances.In the ancient Roman world, where the plentiful supply of running water by the prestigious aqueducts was what mattered most, water-lifting devices remained largely unknown. Since the 19th century, however, a range of such devices, confirming the use of several different techniques, has been found in numerous sites. Moreover, as the number of such discoveries has increased in recent years, this has enabled the most up-to-date methods to be applied to these structures which, as wood elements are often used, are particulary fragile. Aquam in Altum Exprimere, the Round-table Study Day organized by Ausonius in 2003 has contributed to a general stocktaking of our present-day knowledge on this subject

The Impact of Diffusion-Weighted MRI on the Definition of Gross Tumor Volume in Radiotherapy of Non-Small-Cell Lung Cancer - Fig 3

<p>Scatter plots and Bland-Altman analysis of tumor volume <b>A.</b> Linear regression analysis with fitted line. <i>p</i> = 0.005. <b>B.</b> Bland-Altman analysis showing upper and lower limits of agreement (mean volume difference ± 2 standard deviations) between stGTV (x-axis) and dwGTV (y-axis). The p-value indicates a significant dependence of measured volume differences from the average tumor size, as tested with linear regression analysis. <b>C.</b> Bland-Altman analysis showing upper and lower limits of agreement (mean volume difference ± 2 standard deviations) between stGTV (x-axis) and dwGTV (y-axis) in logarithmic scale. In logarithmic form, no significant dependence of measured volume differences from the average tumor size was observed (tested with linear regression analysis).</p

Patient characteristics, measured tumor volumes for all 16 tumors in 15 patients.

<p>Patient characteristics, measured tumor volumes for all 16 tumors in 15 patients.</p

MRI sequences of a patient with stage T1b NSCLC in the left upper lobe.

<p><b>A</b>. T2 HASTE sequence (non-gated). <b>B.</b> ADC-map. <b>C.</b> DWI (calculated b-value of 1400). <b>D.</b> Fusion of T2 and DWI, color represents diffusion restriction.</p