Browsing by Author "Figueroa, Daniela "

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    Exactitud diagnóstica de la tomografía computarizada en la estadificación del cáncer de colon
    (2022) Carcamo, Leonardo C.; Imigo, Felipe ; Molina, Maria E.; Urrejola, Gonzalo ; Henriquez, Hector ; Figueroa, Daniela ; San Martin, Rodrigo
    © 2022, Sociedad de Cirujanos de Chile. All rights reserved.Introduction: Neoadjuvant therapy is an emerging treatment for selected cases of colon cancer. The decision is based on the analysis of preoperative images taken by computed tomography. However, its ability to discriminate those who could benefit from this therapy is unknown. Aim: Our objective is to determine the diagnostic accuracy of computed tomography to evaluate the colon cancer stage and its correlation among expert radiologists. Materials and Method: Diagnostic accuracy study. After sample size calculation, we randomly selected 47 patients who underwent a colonic adenocarcinoma resection with curative intent and had available images up to 60 days after surgery. The depth of tumor and lymph nodal invasion were evaluated by two expert radiologists, blinded to each other. The differences between radiologists were audited by a third one. The results were correlated with biopsy as the gold standard. We calculated sensitivity, specificity, negative predictive value, positive predictive value, and diagnostic accuracy of computed tomography. The agreement between radiologists was calculated using the kappa index. Results: The accuracy to differentiate T3-T4 tumors from T1-T2 was 89.4%. In contrast, ability to differentiate T4 tumors from T3 tumors was 65.9%. The accuracy to determine an N (+) was 66%. Agreement between radiologists was 0.929 to identify T1-2, 0.602 for T3, 0.584 for T4 tumors. To determine an N (+), the concordance was 0.521. Conclusion: Diagnostic computed tomography accuracy in colon cancer is adequate to differentiate advanced tumors. However, its ability to discriminate between T3 and T4, N (+) and the low agreement between radiologists suggests the need for complementary imaging techniques.
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    Interplay between the morphometry of the lungs and the mode of locomotion in birds and mammals
    (2007) Figueroa, Daniela; Olivares, Ricardo; Salaberry, Michel; Sabat, Pablo; Canals, Mauricio
    We studied the lung diffusion parameters of two species of birds and two species-of mammals to explore how structural and functional features may be paralleled by differences in life style or phylogenetic origin. We used two fast-flying species (one mammal and one bird), one running mammal and one bird species that flies only occasionally as models. The harmonic mean thickness of the air-blood barrier was very thin in the species we studied. An exception was the Chilean tinamou Notoprocta perdicaria, which only flies occasionally. It showed an air-blood barrier as thick as that of flightless Galliformes. We found that the respiratory surface density was significantly greater in flying species compared to running species. The estimated values for the oxygen diffusion capacity, 13,02 follow the same pattern: the highest values were obtained in the flying species, the bat and the eared dove. The lowest value was in N. perdicaria. Our findings suggest that the studied species show refinements in their morphometric lung parameters commensurate to their energetic requirements as dictated by their mode of locomotion, rather than their phylogenetic origin. The air-blood barrier appears to be thin in most birds and small mammals, except those with low energetic requirements such as the Chilean tinamou. In the species we studied, the respiratory surface density appears to be the factor most responsive to the energetic requirements of flight.