Sabine Dettmer

Teaching surgery, radiology and anatomy together: the mix enhances motivation and comprehension

PurposePreclinical and clinical topics are often separated in medical education. For example, surgery and radiology are often taught much later than anatomy. The aim of this study was to establish and to evaluate an interdisciplinary course combining these closely related subjects to enhance medical comprehension.MethodsTwo tutorials each lasting one term were offered to second year medical students, in which clinical topics were implemented linking anatomy to surgical and radiological knowledge. A questionnaire was used to evaluate the success of this approach.ResultsThe motivation of the students was above average and the practical work was done accurately. The students confirmed that the course improved anatomical comprehension (>95%) and that the learned matters were relevant for their future (90%). Furthermore, interest in the subjects was higher after the course (>85%). Critical suggestions were to extend the course and to include more topics.ConclusionsA mix of surgery, radiology and anatomy is a teaching concept, which leads to high acceptance and interest in medical students.

Micro-computed tomography of pulmonary fibrosis in mice induced by adenoviral gene transfer of biologically active transforming growth factor-β1.

BackgroundMicro-computed tomography (micro-CT) is a novel tool for monitoring acute and chronic disease states in small laboratory animals. Its value for assessing progressive lung fibrosis in mice has not been reported so far. Here we examined the importance of in vivo micro-CT as non-invasive tool to assess progression of pulmonary fibrosis in mice over time.MethodsPulmonary fibrosis was induced in mice by intratracheal delivery of an adenoviral gene vector encoding biologically active TGF-ß1 (AdTGF-ß1). Respiratory gated and ungated micro-CT scans were performed at 1, 2, 3, and 4 weeks post pulmonary adenoviral gene or control vector delivery, and were then correlated with respective histopathology-based Ashcroft scoring of pulmonary fibrosis in mice. Visual assessment of image quality and consolidation was performed by 3 observers and a semi-automated quantification algorithm was applied to quantify aerated pulmonary volume as an inverse surrogate marker for pulmonary fibrosis.ResultsWe found a significant correlation between classical Ashcroft scoring and micro-CT assessment using both visual assessment and the semi-automated quantification algorithm. Pulmonary fibrosis could be clearly detected in micro-CT, image quality values were higher for respiratory gated exams, although differences were not significant. For assessment of fibrosis no significant difference between respiratory gated and ungated exams was observed.ConclusionsTogether, we show that micro-CT is a powerful tool to assess pulmonary fibrosis in mice, using both visual assessment and semi-automated quantification algorithms. These data may be important in view of pre-clinical pharmacologic interventions for the treatment of lung fibrosis in small laboratory animals.

Phenotyping Chronic Lung Allograft Dysfunction Using Body Plethysmography and Computed Tomography

Restrictive subtype of chronic lung allograft dysfunction (CLAD) was recently described after lung transplantation. This study compares different definitions of a restrictive phenotype in CLAD patients and impact on survival. Eighty‐nine CLAD patients out of 1191 screened patients (September 1987 to July 2012) were included as complete longitudinal lung volume measurements and chest computed tomography (CT) after CLAD onset was available. CT findings and lung volumes were quantified and survival was calculated for distinctive groups and predictive factors for worse survival were investigated. Graft survival in patients with total lung capacity (TLC) between 90% and 81% of baseline (BL) (n = 13, 15%) in CLAD course was similar to those with TLC >90% BL (n = 64, 56%; log‐rank test p = 0.9). Twelve patients (13%) developed a TLC ≤80% BL and 10 (11%) had significant parenchymal changes on CT, of whom 6 (46%) also had TLC ≤80% BL. CT changes correlated with TLC ≤80% BL (Φ‐coefficient = 0.48, p = 0.001). Patients with either TLC ≤80% or significant CT changes (n = 16, 18%) had a significantly reduced survival (log‐rank p < 0.001). Forced vital capacity loss at CLAD onset was associated with poorer survival but did not correlate with the TLC or CT changes. A restrictive subtype of CLAD may be defined by either TLC ≤80% BL or severe parenchymal changes on chest CT.

Dipeptidyl peptidase IV (DPP4)-deficiency attenuates diet-induced obesity in rats: Possible implications for the hypothalamic neuropeptidergic system

The underlying mechanisms controlling food intake and satiety are thoroughly controlled, but seem to be insufficient under conditions of almost unlimited food supply. Hence, overweight and obesity are serious problems especially in industrialized countries. To assess the possible influence of CD26, exerting a dipeptidyl peptidase activity (DPP4) cleaving several energy homeostasis-relevant peptides, we investigated wild type and DPP4-deficient dark agouti rats in a model of diet-induced obesity and found a reduced weight gain in DPP4-deficient rats. When investigating the specific increase of whole body fat volume by MRI to assess the distribution pattern (subcutaneous vs. intraabdominal), there was an altered ratio under dietary conditions only in DPP4-deficient rats, which was due to lower intraabdominal fat amounts. Furthermore, we investigated the number of cells immunopositive for the leptin receptor (OB-R), the orexigenic leptin antagonist neuropeptide Y (NPY), as well as of the NPY receptors Y1, Y2, and Y5 within hypothalamic nuclei. Independent from the body weight, higher levels of NPY and all receptors were expressed in DPP4-deficent rats. Under obese conditions, hypothalamic Y2-levels were reduced in both strains. Concerning NPY and Y1, there were partly oppositional effects, with reduced hypothalamic Y1 levels only in wild types, and increased NPY levels only in DPP4-deficient rats. These effects might be responsible for unaltered food intake in DPP4-deficent rats compared to wild types, despite reduced weight gain. However, since the food intake remained unaffected, these effects suggest that DPP4 exerts its effects on intraabdominal fat also via peripheral actions.

Improved imaging of Cochlear nerve hypoplasia using a 3-tesla variable flip-angle turbo spin-echo sequence and a 7-cm surface coil

Magnetic resonance imaging of the temporal bone has an important role in decision making with regard to cochlea implantation, especially in children with cochlear nerve deficiency. The purpose of this study was to evaluate the usefulness of the combination of an advanced high‐resolution T2‐weighted sequence with a surface coil in a 3‐Tesla magnetic resonance imaging scanner in cases of suspected cochlear nerve aplasia.

Endobronchial ultrasound guided fine needle aspiration versus transcervical mediastinoscopy in nodal staging of non small cell lung cancer: a prospective comparison study

BackgroundAt present only few studies directly compare the diagnostic yield of endobronchial ultrasound guided fine needle aspiration (EBUS-FNA) and transcervical video-assisted mediastinoscopy (TM) for mediastinal lymph node staging in patients with NSCLC. If and when EBUS-FNA may replace TM as Gold Standard remains controversial.MethodsFrom April 2008 to December 2009, 36 patients with mediastinal lymphadenopathy underwent simultaneous EBUS-FNA/ TM at our institution. Among them were 26 patients with confirmed or suspected NSCLC.ResultsA total of 133 samples were obtained by EBUS-FNA and 157 samples by TM. EBUS-FNA achieved significantly less conclusive, but more indeterminate pathological results in comparison to TM (78.7% vs. 98.6%, p < 0.001; 14.9% vs. 1.4%, p = 0.007). Less paratracheal nodes were sampled by EBUS-FNA (right: 46.2% vs. 88.5%, p = 0.003; left: 23.1% vs. 65.4%, p = 0.005), while sampling rates in the subcarinal localisation were comparable (96.2% vs. 80.8%, p = NS). Among patients with confirmed NSCLC and conclusive EBUS-FNA/ TM findings (n = 18), the prevalence of N2/N3 disease was 66.7% (n = 12) according to TM findings. Diverging nodal stages were found in five patients (27.8%). Three patients who were N2 negative in EBUS-FNA were upstaged to N2 or N3 by TM, two patients with N2 status in EBUS-FNA were upstaged to N3 by TM.ConclusionsCompared to TM, EBUS-FNA had a lower diagnostic yield and resulted in systematic mediastinal nodal understaging. At this point we suggest corroborating negative EBUS-FNA results by transcervical mediastinoscopy.

Quantification of pathologic air trapping in lung transplant patients using ct density mapping: Comparison with other ct air trapping measures

To determine whether density mapping (DM) is more accurate for detection and quantification of pathologic air trapping (pAT) in patients after lung transplantation compared to other CT air trapping measures. One-hundred forty-seven lung and heart-lung transplant recipients underwent CT-examinations at functional residual capacity (FRC) and total lung capacity (TLC) and PFT six months after lung transplantation. Quantification of air trapping was performed with the threshold-based method in expiration (EXP), density mapping (DM) and the expiratory to inspiratory ratio of the mean lung density (E/I-ratio MLD). A non-rigid registration of inspiration-expiration CT-data with a following voxel-to-voxel mapping was carried out for DM. Systematic variation of attenuation ranges was performed for EXP and DM and correlated with the ratio of residual volume to total lung capacity (RV/TLC) by Spearman rank correlation test. AT was considered pathologic if RV/TLC was above the 95th percentile of the predicted upper limit of normal values. Receiver operating characteristic (ROC) analysis was performed. The optimal attenuation range for the EXP method was from -790 HU to -950 HU (EXP-790 to -950HU ) (r = 0.524, p<0.001) to detect air trapping. Within the segmented lung parenchyma, AT was best defined as voxel difference less than 80 HU between expiration and registered inspiration using the DM method. DM correlated best with RV/TLC (r = 0.663, p<0.001). DM and E/I-ratio MLD showed a larger AUC (0.78; 95% CI 0.69–0.86; 0.76, 95% CI 0.67–0.85) than EXP -790 HU to -950 HU (0.71, 95% CI 0.63–0.78). DM and E/I-ratio MLD showed better correlation with RV/TLC and are more suited quantitative CT-methods to detect pAT in lung transplant patients than the EXP-790HU to -950HU.

Lung tumour growth kinetics in SPC-c-Raf-1-BB transgenic mice assessed by longitudinal in-vivo micro-CT quantification

BackgroundSPC-c-Raf-1-BxB transgenic mice develop genetically induced disseminated lung adenocarcinoma allowing examination of carcinogenesis and evaluation of novel treatment strategies. We report on assessment of lung tumour growth kinetics using a semiautomated region growing segmentation algorithm.Methods156 non contrast-enhanced respiratory gated micro-CT of the lungs were obtained in 12 SPC-raf transgenic (n = 9) and normal (n = 3) mice at different time points. Region-growing segmentation of the aerated lung areas was obtained as an inverse surrogate for tumour burden. Time course of segmentation volumes was assessed to demonstrate the potential of the method for follow-up studies.ResultsMicro-CT allowed assessment of tumour growth kinetics and semiautomated region growing enabled quantitative analysis. Significant changes of the segmented lung volumes over time could be shown (p = 0.009). Significant group differences could be detected between transgenic and normal animals for time points 8 to 13 months (p = 0.043), when marked tumour progression occurred.ConclusionThe presented region-growing segmentation algorithm allows in-vivo quantification of multifocal lung adenocarcinoma in SPC-raf transgenic mice. This enables the assessment of tumour load and progress for the study of carcinogenesis and the evaluation of novel treatment strategies.

CT at onset of chronic lung allograft dysfunction in lung transplant patients predicts development of the restrictive phenotype and survival

PURPOSE To describe early signs for restrictive subtype of chronic lung allograft dysfunction (CLAD) after lung transplantation in computed tomography (CT) and to evaluate the predictive value for disease progression and survival. MATERIAL AND METHODS 52 CT examinations in lung transplant patients at CLAD onset were scored for CT features referring to airways disease, parenchymal or pleural abnormality. Patients with and without later development of restrictive CLAD (TLC≤80%) were compared. A radiological score for inflammation including pleural effusion, central and peripheral ground glass opacities and consolidations was calculated and used for survival analysis. RESULTS CT of patients with later development of restrictive CLAD showed significantly more often abnormalities at CLAD onset, in particular consolidations (57% vs. 4%; p<0.001) and ground glass attenuations (71% vs. 7%; p<0.001) than those of patients without the restrictive phenotype. CT score for inflammation was significantly higher in patients with than without later restrictive CLAD (3.4 vs. 0.6; p<0.001). Survival of patients with a high score (>2) for inflammation in CT at CLAD onset was significantly lower than of those with a low score (443 vs. 2415 days; p=0.019). CONCLUSIONS CT at CLAD onset differs in patients with/without later development of the restrictive phenotype. It is therefore an indicator for future development of restrictive CLAD and predictor for survival. It should be implemented in the diagnostic work-up at diagnosis of CLAD.

Bronchial wall measurements in patients after lung transplantation: evaluation of the diagnostic value for the diagnosis of bronchiolitis obliterans syndrome.

Objectives To prospectively evaluate quantitative airway wall measurements of thin-section CT for the diagnosis of Bronchiolitis Obliterans Syndrome (BOS) following lung transplantation. Materials and Methods In 141 CT examinations, bronchial wall thickness (WT), the wall area percentage (WA%) calculated as the ratio of the bronchial wall area and the total area (sum of bronchial wall area and bronchial lumen area) and the difference of the WT on inspiration and expiration (WTdiff) were automatically measured in different bronchial generations. The measurements were correlated with the lung function parameters. WT and WA% in CT examinations of patients with (n = 25) and without (n = 116) BOS, were compared using the unpaired t-test and univariate analysis of variance, while also considering the differing lung volumes. Results Measurements could be performed in 2,978 bronchial generations. WT, WA%, and WTdiff did not correlate with the lung function parameters (r<0.5). The WA% on inspiration was significantly greater in patients with BOS than in patients without BOS, even when considering the dependency of the lung volume on the measurements. WT on inspiration and expiration and WA% on expiration did not show significant differences between the groups. Conclusion WA% on inspiration was significantly greater in patients with than in those without BOS. However, WA% measurements were significantly dependent on lung volume and showed a high variability, thus not allowing the sole use of bronchial wall measurements to differentiate patients with from those without BOS.