On the fluid-tissue contrast behavior of high-resolution steady-state sequences

In general, MR image contrast is expected to be resolution independent, but a pronounced loss of contrast is observed between fluids and tissues with contemporary musculoskeletal protocols (typical inplane resolution << 1 mm) using nonbalanced steady‐state free precession, such as double echo steady state. For nonbalanced steady‐state free precession, diffusion sensitivity increases with increasing spoiler moments which increase with decreasing voxel size, suggesting diffusion damping as the major cause for the observed contrast variation. This is confirmed by simulations and measurements indicating that for fluids, diffusion effects become apparent already for resolutions Δx < 1 mm, whereas tissues typically require Δx < 200 μm. Gradient spoiling, however, is generically not minimized but frequently applied along the readout direction. For anisotropic steady‐state free precession scans, the loss of contrast between fluids and tissues from diffusion can thus be minimized by simply moving the spoiler gradients to the lowest resolution direction. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.     

Predictive value of early and late residual 18F-fluorodeoxyglucose and 18F-fluorothymidine uptake using different SUV measurements in patients with non-small-cell lung cancer treated with erlotinib

Purpose

To evaluate the predictive value of early and late residual ¹⁸F-fluorodeoxyglucose (FDG) and ¹⁸F-fluorothymidine (FLT) uptake using different SUV measurements in PET in patients with advanced non-small-cell lung cancer (NSCLC) treated with erlotinib.

Methods

We retrospectively reviewed data from 30 patients with untreated stage IV NSCLC who had undergone a combined FDG PET and FLT PET scan at 1?week (early) and 6?weeks (late) after the start of erlotinib treatment. Early and late residual FDG and FLT uptake were measured in up to five lesions per scan with different quantitative standardized uptake values (SUV_max, SUV_2Dpeak, SUV_3Dpeak, SUV₅₀, SUV_A50, SUV_A41) and compared with short-term outcome (progression vs. nonprogression after 6?weeks of erlotinib treatment). Receiver-operating characteristics (ROC) curve analysis was used to determine the optimal cut-off value for detecting nonprogression after 6?weeks. Kaplan-Meier analysis and the log-rank test were used to evaluate the association between residual uptake and progression-free survival (PFS).

Results

Nonprogression after 6?weeks was associated with a significantly lower early and late residual FDG uptake, measured with different quantitative parameters. In contrast, nonprogression after 6?weeks was not associated with early and late residual FLT uptake. Furthermore, patients with a lower early residual FDG uptake measured in terms of SUV_max and SUV_2Dpeak had a significantly prolonged PFS (282?days vs. 118?days; p?=?0.022) than patients with higher values. Similarly, lower late residual FDG uptake and early residual FLT uptake measured in terms of SUV_3Dpeak, SUV_A50 and SUV_A41, and late FLT uptake measured in terms of SUV_3Dpeak and SUV_A50 was associated with an improved PFS.

Conclusion

Early and late residual FDG uptake, measured using different quantitative SUV parameters, are predictive factors for short-term outcome in patients with advanced NSCLC treated with erlotinib. Additionally, low residual FDG and FLT uptake early and late in the course of erlotinib treatment is associated with improved PFS.     

Prognostic value of HPV-mRNA in sentinel lymph nodes of cervical cancer patients with pN0-status

Up to 15% of patients with cervical cancer and pN0-status develop recurrent-disease. This may be due to occult metastatic spread of tumor cells. We evaluated the use of human-papillomavirus-(HPV)-mRNA as a molecular marker for disseminated tumor cells to predict the risk of recurrence. For this prospective, multi-center prognostic study, 189 patients free of lymphnode metastases by conventional histopathology could be analyzed. All patients underwent complete lymphadenectomy. Of each sentinel node (SLN) a biopsy was taken for the detection of HPV-E6-E7-mRNA. Median follow-up time after surgery was 8.1 years. HPV-mRNA could be detected in SLN of 52 patients (27.5%). Recurrence was observed in 22 patients. Recurrence-free-survival was significantly longer for patients with HPV-negative SLN (log rank p = 0.002). By Cox regression analysis the hazard ratio (95%CI) for disease-recurrence was 3.8 (1.5 – 9.3, p = 0.004) for HPV-mRNA-positive compared to HPV-mRNA-negative patients. After adjustment for tumor size as the most influential covariate the HR was still 2.8 (1.1 – 7.0, p = 0.030). In patients with cervical cancer and tumor-free lymph nodes by conventional histopathology HPV-mRNA-positive SLN were of prognostic value independent of tumor size. Particularly, patients with tumors larger than 20mm diameter could possibly benefit from further risk stratification using HPV-mRNA as a molecular marker.     

Abdominal aortic aneurysm repair in cardiac high risk patients – medication, surgery or stent?

With increasing age of the general population, a higher awareness of the disease, better screening methods and the option of less invasive therapeutical strategies, the incidence of abdominal aortic aneurysms (AAA) is rising steadily. Since AAA is a disease of the elderly patient with generalized atherosclerosis, there is a high coincidence with other vascular morbidities. Especially the presence of coronary artery disease and concomitant left ventricular dysfunction proves many of those patients to be cardiac high risk patients with respect to an operative approach. On the other hand, a high coincidence of severe peripheral arterial occlusive disease might hamper the endovascular approach and endovascular therapy might carry a high risk for these patients as well. Therefore, it is of utmost importance to consider how and when cardiac high risk patients with AAA should be treated. In this review therefore special aspects such as the choice of medical treatment, the need of preoperative coronary revascularization and the situation in old patients are discussed in detail.     

Strategy for robust detection of insertions, deletions, and point mutations in CEBPA, a GC-rich content gene, using 454 next-generation deep-sequencing technology

CEBPA mutations are of prognostic relevance in acute myeloid leukemia (AML) and are currently detected using a combination of denaturing high-performance liquid chromatography (DHPLC), gene scan/fragment length analysis, and direct Sanger sequencing. Next-generation deep pyrosequencing, principally, allows for the highly sensitive detection of molecular mutations. However, standard 454 chemistry laboratory procedures lack efficient amplification of guanine-cytosine (GC)-rich amplicons during the emulsion PCR (emPCR) steps allowing direct massively parallel clonal amplification of PCR products. To solve this problem, we investigated six distinct emPCR conditions. The coding sequence of CEBPA was subdivided into four overlapping amplicons: GC content for amplicon 1, 74%; amplicon 2, 76%; amplicon 3, 77%; and amplicon 4, 69%. A new emPCR condition, improving the standard titanium assay, presents a robust solution to sequence amplicons with a GC content of up to 77%. Moreover, this assay was subsequently tested on a larger independent cohort of 23 AML patients. For each patient, a median of 737 reads was generated (coverage range, 397-fold to 1194-fold) and therefore allowed a robust detection of insertions, deletions, and point mutations. In conclusion, next-generation amplicon sequencing enables the highly sensitive detection of molecular mutations and is a feasible assay for routine assessment of GC-rich content amplicons.     

Novel Method for Three-Dimensional Facial Expression Recognition Using Self-Normalizing Neural Networks and Mobile Devices

Introduction To date, most ways to perform facial expression recognition rely on two-dimensional images, advanced approaches with three-dimensional data exist. These however demand stationary apparatuses and thus lack portability and possibilities to scale deployment. As human emotions, intent and even diseases may condense in distinct facial expressions or changes therein, the need for a portable yet capable solution is signified. Due to the superior informative value of three-dimensional data on facial morphology and because certain syndromes find expression in specific facial dysmorphisms, a solution should allow portable acquisition of true three-dimensional facial scans in real time. In this study we present a novel solution for the three-dimensional acquisition of facial geometry data and the recognition of facial expressions from it. The new technology presented here only requires the use of a smartphone or tablet with an integrated TrueDepth camera and enables real-time acquisition of the geometry and its categorization into distinct facial expressions. Material and Methods Our approach consisted of two parts: First, training data was acquired by asking a collective of 226 medical students to adopt defined facial expressions while their current facial morphology was captured by our specially developed app running on iPads, placed in front of the students. In total, the list of the facial expressions to be shown by the participants consisted of “disappointed”, “stressed”, “happy”, “sad” and “surprised”. Second, the data were used to train a self-normalizing neural network. A set of all factors describing the current facial expression at a time is referred to as “snapshot”. Results In total, over half a million snapshots were recorded in the study. Ultimately, the network achieved an overall accuracy of 80.54% after 400 epochs of training. In test, an overall accuracy of 81.15% was determined. Recall values differed by the category of a snapshot and ranged from 74.79% for “stressed” to 87.61% for “happy”. Precision showed similar results, whereas “sad” achieved the lowest value at 77.48% and “surprised” the highest at 86.87%. Conclusions With the present work it can be demonstrated that respectable results can be achieved even when using data sets with some challenges. Through various measures, already incorporated into an optimized version of our app, it is to be expected that the training results can be significantly improved and made more precise in the future. Currently a follow-up study with the new version of our app that encompasses the suggested alterations and adaptions, is being conducted. We aim to build a large and open database of facial scans not only for facial expression recognition but to perform disease recognition and to monitor diseases’ treatment progresses.     

Beobachtungen und Versuche Über Dermo graphismus

Ohne Zusammenfassung