Διασφάλιση Ποιότητας στη Λειτουργική Μαγνητική Απεικόνιση - fMRI

Η παρούσα διπλωματική εργασία πραγματοποιήθηκε με σκοπό την διασφάλιση ποιότητας και τη δημιουργία τιμών αναφοράς στη λειτουργική μαγνητική απεικόνιση, στον καινούριο μαγνητικό τομογράφο της εταιρίας Phillips, στατικού μαγνητικού πεδίου 3Τ, του Πανεπιστημιακού Γενικού Νοσοκομείου Ιωαννίνων. Η διασφάλιση της ποιότητας πραγματοποιήθηκε εξετάζοντας τη σταθερότητα του απεικονιστικού συστήματος, σύμφωνα με τα πρωτόκολλα της AAPM και του FBIRN, μακροπρόθεσμα και βραχυπρόθεσμα, καθώς επίσης και την συμπεριφορά του με χρήση κάποιων παραμέτρων και εξαρτημάτων, όπως τα συνήθη φώτα, τον δυναμικό φωτισμό μαζί με τον βιντεοπροβολέα του συστήματος και τη χρήση του υποστηρικτικού συστήματος λειτουργικής απεικόνισης SensaVue, που δίνει το οπτικό ερέθισμα στον ασθενή. Αν και το πρωτόκολλο της AAPM δεν επαρκεί για την εκτίμηση της σταθερότητας του συστήματος, εξάγει κάποιους βασικούς δείκτες, που ποσοτικοποιούν την παρουσία παραμορφώσεων ή ghosting, που είναι σημαντικά στις εξετάσεις λειτουργικής. Η ανάλυση πραγματοποιήθηκε πάνω στο ομοίωμα του συστήματος και με χρήση δύο διαφορετικών πηνίων εγκεφάλου. Οι δείκτες λογαριάστηκαν με τη βοήθεια προγράμματος (script) που αναπτύχθηκε σε περιβάλλον Matlab, το οποίο εξήγαγε και τις χαρακτηριστικές εικόνες που περιγράφει το πρωτόκολλο του FBIRN. Οι δείκτες που εξήχθησαν ήταν οι SNR, SFNR, Percent fluctuation και Drift, με τους τρεις πρώτους να έχουν άμεση συσχέτιση με την σταθερότητα συναρτήσει του χρόνου, αφού παράγονται με βάση τα 200 δυναμικά της κεντρικής τομής του ομοιώματος που μελετήθηκαν στην παρούσα ανάλυση. Η μελέτη έδειξε ότι το απεικονιστικό σύστημα χαρακτηρίζεται από καλή μακροπρόθεσμη και βραχυπρόθεσμη σταθερότητα, καθώς και ότι οι παράγοντες-εξαρτήματα δεν επηρεάζουν την λειτουργία του.This study was carried out with the aim of performing quality assurance and creating reference values in functional Magnetic Resonance Imaging, using a new Phillips 3T MRI scanner, recently installed at the University Hospital of Ioannina. Quality assurance was carried out by examining the long and short term stability of the imaging system in accordance to the protocols of AAPM and FBIRN, as well as assessing the influence of some peripheral factors, such as the room’s lights, the ambient lights along with system projector and functional MRI support system SensaVue, which is used for delivering visual stimulus to the patient. Although the AAPM protocol is not specialized to assess system stability, it extracts some key indices, such as distortions and ghosting, which are important for functional imaging exams. The analysis was performed using the scanner’s phantom, and two different brain coils. The indices were calculated using a script developed in Matlab, which also exported the images described in the FBIRN protocol. The indices calculated were SNR, SFNR, Percent Fluctuation and Drift with the first three directly associated with system’s stability over time, since they are produced based using the 200 dynamic scans of the center slice of the phantom. The study showed that the imaging system is characterized by good long and short term variability, and the peripheral factors do not affect its operation or stability

The role of allopurinol′s timing in the ischemia reperfusion injury of small intestine

INTRODUCTION: Allopurinol acts protectively in the ischemia reperfusion injury of the small intestine. The aim of this experimental study is to define the ideal time of administration of allopurinol, in experimental models of ischemia/reperfusion. MATERIALS AND METHODS: We used 46 rabbits that were divided into four groups. Group A was the control. In Group B allopurinol was administered 10 min before ischemia and in Group C 2 min before reperfusion. In Group D, allopurinol was administered before ischemia and before reperfusion in half doses. Blood samples were collected at three different moments: (t(1)) prior to ischemia, (t(2)) prior to reperfusion, and (t(3)) after the end of the reperfusion, in order to determine superoxide dismutase (SOD) and neopterin values. Specimens of the intestine were obtained for histological analysis and determination of malondialdehyde (MDA). RESULTS: In Group A, mucosal lesions were more extensive compared to those of the other three groups. Similarly, MDA, SOD and neopterin values were significantly higher. On the contrary, Group D showed the mildest mucosal lesions, as well as the lowest MDA, SOD and neopterin values. Finally, the lesions and the above mentioned values were bigger in Group C than in Group D. CONCLUSIONS: The administration of allopurinol attenuates the production and damage effect of free oxygen radicals during ischemia reperfusion of the small intestine, thus protecting the intestinal mucosa. Its maximum beneficial action is achieved when administered both before ischemia and before reperfusion of the small intestine

The Role of Carbon Nanoparticles in Lymph Node Dissection and Parathyroid Gland Preservation during Surgery for Thyroid Cancer: A Systematic Review and Meta-Analysis

Thyroid cancer is the most common endocrine malignancy with an increasing incidence over the past few years. Surgery is considered the primary therapeutic option, which often involves lymph node dissection. The aim of this study was to assess the role of carbon nanoparticles, a novel agent, in thyroid cancer surgery. For that purpose, we conducted a systematic review of the literature on MEDLINE, EMBASE, Scopus, Cochrane and Google Scholar databases from 1 January 2002 to 31 January 2022. Ultimately, 20 articles with a total number of 2920 patients were included in the analysis. The outcome of the analysis showed that the use of carbon nanoparticles is associated with a higher number of harvested lymph nodes (WMD, 1.47, 95% CI, 1.13 to 1.82, p < 0.001) and a lower rate of accidental parathyroid gland removal (OR 0.34, CI 95% 0.24 to 0.50, p < 0.001). Based on these results, we suggest that carbon nanoparticles are applied in thyroid cancer surgery on a wider scale, so that these findings can be confirmed by future research on the subject

Anatomical Schemata Revealed by the Critical View of Safety Approach: A Proposal of the Hellenic Task Force on the Typology of Safe Laparoscopic Cholecystectomy (HETALCHO)

Background and objectives: Laparoscopic cholecystectomy (LC) is the most commonly performed operation in general surgery in the Western World. Gallbladder surgery, although most of the time simple, always offers the possibility of unpleasant surprises. Despite progress, the incidence of common bile duct injury is 0.2–0.4%, causing devastating implications for the patient and the surgeon. This is mainly due to the failure to identify the normal anatomy properly. The literature review reveals a lack of structured knowledge in the surgical anatomy of cholecystectomy. The aim of this study was to develop a framework with a common anatomical language for safe laparoscopic and open cholecystectomy. Materials and Methods: The Hellenic Task Force group on the typology for Safe Laparoscopic Cholecystectomy performed a critical review of the literature on the laparoscopic anatomy of cholecystectomy. The results were compared with those of a clinical study of 279 patients undergoing LC for uncomplicated symptomatic gallstone disease. Results: Fourteen elements encountered during LC under the critical view of safety (CVS) approach were determined. The typical vascular–biliary pedicle with one cystic duct distributed laterally (or caudally) and one cystic artery medially (or cranially) lying at any point of the hepatocystic space was found in 66% of the cases studied. Anatomical schemata were formulated corresponding to the norm and four variations. Conclusions: The proposed cognitive anatomical schemata summarize simply what one can expect in terms of deviation from the norm. We believe that the synergy between the correct application of the CVS and the structured knowledge of the surgical anatomy in cholecystectomy helps the surgeon to handle non-typical structures safely and to complete the laparoscopic or open cholecystectomy without vascular–biliary injuries