Mitigation of atmospheric Water-Vapour effects on spaceborne interferometric SAR imaging through the MM5 Numerical model

Synthetic Aperture Radar (InSAR) imaging is a well established technique to derive useful products for several land applications. One of the major limitations of InSAR is due to atmospheric e® ects, and in particular to high water vapor variability. In this work, we make an experimental analysis to research the capability of Numerical Weather Prediction (NWP) models as MM5 to produce high resolution (1 km{500 m) maps of Integrated Water Vapor (IWV) in the atmosphere to mitigate the well-known disturbances that a® ect the radar signal while traveling from the sensor to the ground and back. Experiments have been conducted over the area surrounding Rome using ERS data acquired during the three days phase in '94 and using Envisat data acquired in recent years. By means of the PS technique SAR data have been processed and the Atmospheric Phase Screen (APS) of Slave images with respect to a reference Master have been extracted. MM5 provides realistic water vapor distribution elds that can be converted into electromagnetic slant delays. PSInSAR APS's have then been compared to MM5 IWV maps revealing interesting results. MM5 IWV maps have a much lower resolution than PSInSAR APS's: the turbulent term of the atmospheric vapor field cannot be well resolved by MM5, at least with the low resolution ECMWF inputs. However, the vapor distribution term that depends on the local topography has been found quite in accordance. In this work, we will present experimental results as well as discussions over the adopted processing strategy

Numerical weather prediction models and SAR interferometry: Synergic use for meteorological and INSAR applications

Spaceborne Interferometric Synthetic Aperture Radar (InSAR) is a well established technique useful in many land applications, such as landslide monitoring and digital elevation model extraction. One of its major limitation is the atmospheric effect, and in particular the high water vapour spatial and temporal variability which introduces an unknown delay in the signal propagation. However, the sensitivity of SAR interferometric phase to atmospheric conditions could in principle be exploited and InSAR could become in certain conditions a tool to monitor the atmosphere, as it happens with GPS receiver networks. This paper describes a novel attempt to assimilate InSAR derived information on the atmosphere, based on the Permanent Scatterer multipass technique, into a numerical weather forecast model. The methodology is summarised and the very preliminary results regarding the forecast of a precipitation event in Central Italy are analysed. The work was done in the framework of an ESA funded project devoted to the mapping of the water vapour with the aim to mitigate its effect for InSAR applications

Preoperative embolization of thyroid arteries in a patient with a large cervicomediastinal hyperfunctioning goiter

We present the case of a 61-year-old male patient with chronic obstructive pulmonary disease and a large cervicomediastinal multinodular hyperfunctioning goiter that made thyroidectomy a daunting task, especially considering the risk of intraoperative bleeding. The preoperative computed tomographic (CT) scan showed the right thyroid lobe very deeply rooted in the mediastinum, below the horizontal plane passing through the aortic arch. The thyroid mass imprinted the arterious and venous innominate trunks. To avoid a median sternotomy and remove the enlarged thyroid through a cervical approach alone, we decided to reduce the goiter in volume preoperatively by embolizing the thyroid arteries. We embolized the superior and inferior left, and the inferior right thyroid arteries. We spared the superior right thyroid artery because its blood supply contributed little to thyroid perfusion. After embolization, the patient was treated with antithyroid agents and corticosteroid drug therapy. At the same time, severe leukocytosis developed, thyroid hormone values increased, and a CT scan obtained 7 days after embolization showed the thyroid unchanged in volume. We therefore discharged the patient and were waiting for his laboratory blood chemical findings to return to normal. Thirty days later the patient was readmitted to hospital, and a new CT scan showed that the thyroid mass had diminished to half its initial volume. We could therefore perform a total thyroidectomy through a cervical approach alone. The only problem arose in dissecting tight right inferior laryngeal nerve adhesions to the thyroid capsule, probably sequelae of postembolization thyroiditis. Even though preoperative thyroid-artery embolization cannot be considered a routine technique in cervicomediastinal goiter surgery, in a rare patient who presents with a voluminous goiter such as the one we describe here, it is a useful procedure

On the accuracy of integrated water vapor observations and the potential for mitigating electromagnetic path delay error in InSAR

A field campaign was carried out in the framework of the Mitigation of Electromagnetic Transmission errors induced by Atmospheric Water Vapour Effects (METAWAVE) project sponsored by the European Space Agency (ESA) to investigate the accuracy of currently available sources of atmospheric columnar integrated water vapor measurements. The METAWAVE campaign took place in Rome, Italy, for the 2-week period from 19 September to 4 October 2008. The collected dataset includes observations from ground-based microwave radiometers and Global Positioning System (GPS) receivers, from meteorological numerical model analysis and predictions, from balloon-borne in-situ radiosoundings, as well as from spaceborne infrared radiometers. These different sources of integrated water vapor (IWV) observations have been analyzed and compared to quantify the accuracy and investigate the potential for mitigating IWV-related electromagnetic path delay errors in Interferometric Synthetic Aperture Radar (InSAR) imaging. The results, which include a triple collocation analysis accounting for errors inherently present in every IWV measurements, are valid not only to InSAR but also to any other application involving water vapor sensing. The present analysis concludes that the requirements for mitigating the effects of turbulent water vapor component into InSAR are significantly higher than the accuracy of the instruments analyzed here. Nonetheless, information on the IWV vertical stratification from satellite observations, numerical models, and GPS receivers may provide valuable aid to suppress the long spatial wavelength (> 20 km) component of the atmospheric delay, and thus significantly improve the performances of InSAR phase unwrapping techniques

La chirurgia delle neoplasie delle ghiandole salivari

La parotidectomia preneurale è l'intervento di scelta delle neoplasie benigne, quando non è interessato il lobo profondo della ghiandola, così come il trattamento chirurgico delle neoplasie maligne non può che essere la parotidectomia totale. La linfectomia è da riservare ai tumori high grade, modulando la sua estensione in relazione all'invasività rilevata all'esame istologico estemporaneo nei linfonodi intraparotidei

Thyroid anaplastic tumor: our experience

We report our experience over the past 10 years in the treatment of thyroid anaplastic carcinoma analysing retrospectively 21 cases of surgical treatment (7 total thyroidectomies, 12 partial resection of the tumours and 2 biopsies). We consider the prognosis, which is invariably fatal, with no survival at 19 months and a mean survival of only 9 months, and assess the validity of a combined therapeutic approach (surgery + radiotherapy + chemotherapy) to increase survival and, above all, the patient's quality of life. The importance is stressed of through monitoring of risk factors consisting in concomitant or previous benign or malignant thyroid disease, considering total thyroidectomy to be necessary in principle for any variety of thyroid cancer. Lastly, we examine the survival trend in terms of residual disease and the presence or otherwise of remote metastases

May predictors of difficulty in thyroid surgery increase the incidence of complications? Prospective study with the proposal of a preoperative score

Abstract Background Although thyroidectomy is one of the most common surgical procedures performed worldwide, some permanent complications, despite the considerably reducing incidence, may affect dramatically the patients quality of life. The purpose of this study is to evaluate whether factors identified preoperatively and expressed in a score could be predictors of major surgical difficulty during total thyroidectomy and influence the incidence of complications. Methods A total of 164 patients who underwent total thyroidectomy were examined. For each patient we calculated a preoperative score, including seven parameters, which we evaluated to be predictors of difficulty in thyroid surgery, that is, sex, body mass index (BMI), neck length, neck extension, thyroid gland volume, thyroiditis, and increased parenchymal vascularization. The overall score was also compared with peri- and post-operative factors describing objectively the difficulty in thyroid surgery. These factors are the duration of the operation, the length of hospitalization, the incidence of complications such as hemorrhage, hypoparathyroidism, and recurrent laryngeal nerve injuries. Results There was no statistically significant association between our score and either the percentage of postoperative complications or the length of hospitalization. The operative time was the only variable remarkably associated with the score value (p < 0.00001). Comparing the duration of the operation with each of the preoperative predictive factors, we found that none of the factors reached the value of statistical significance, but a close association could be noted with the thyroid volume and the BMI. Conclusions In our study, predictors of difficulty in thyroidectomy did not affect morbidity rates, as suggested by previous studies, but only operative times, which were significantly increased in patients with higher score. Although our results have limited statistical significance, they allow us to confirm the fundamental role of a systematic use of optical magnification and microsurgical technique in thyroidectomy. Further studies, with a larger cohort of patients, are needed to validate our results and to formulate a universally accepted predictive score of difficulty in thyroidectomy preoperatively