Volumetry of low-contrast liver lesions with CT: Investigation of estimation uncertainties in a phantom study

Purpose: To evaluate the performance of lesion volumetry in hepatic CT as a function of various imaging acquisition parameters. Methods: An anthropomorphic abdominal phantom with removable liver inserts was designed for this study. Two liver inserts, each containing 19 synthetic lesions with varying diameter (6–40 mm), shape, contrast (10–65 HU), and both homogenous and mixed-density were designed to have background and lesion CT values corresponding to arterial and portal-venous phase imaging, respectively. The two phantoms were scanned using two commercial CT scanners (GE 750 HD and Siemens Biograph mCT) across a set of imaging protocols (four slice thicknesses, three effective mAs, two convolution kernels, two pitches). Two repeated scans were collected for each imaging protocol. All scans were analyzed using a matched-filter estimator for volume estimation, resulting in 6080 volume measurements across all of the synthetic lesions in the two liver phantoms. A subset of portal venous phase scans was also analyzed using a semi-automatic segmentation algorithm, resulting in about 900 additional volume measurements. Lesions associated with large measurement error (quantified by root mean square error) for most imaging protocols were considered not measurable by the volume estimation tools and excluded for the statistical analyses. Imaging protocols were grouped into distinct imaging conditions based on ANOVA analysis of factors for repeatability testing. Statistical analyses, including overall linearity analysis, grouped bias analysis with standard deviation evaluation, and repeatability analysis, were performed to assess the accuracy and precision of the liver lesion volume biomarker. Results: Lesions with lower contrast and size ≤10 mm were associated with higher measurement error and were excluded from further analysis. Lesion size, contrast, imaging slice thickness, dose, and scanner were found to be factors substantially influencing volume estimation. Twenty-four distinct repeatable imaging conditions were determined as protocols for each scanner with a fixed slice thickness and dose. For the matched-filter estimation approach, strong linearity was observed for all imaging data for lesions ≥20 mm. For the Siemens scanner with 50 mAs effective dose at 0.6 mm slice thickness, grouped bias was about −10%. For all other repeatable imaging conditions with both scanners, grouped biases were low (−3%–3%). There was a trend of increasing standard deviation with decreasing dose. For each fixed dose, the standard deviations were similar among the three larger slice thicknesses (1.25, 2.5, 5 mm for GE, 1.5, 3, 5 mm for Siemens). Repeatability coefficients ranged from about 8% to 75% and showed similar trend to grouped standard deviation. For the segmentation approach, the results led to similar conclusions for both lesion characteristic factors and imaging factors but with increasing magnitude in all the error metrics assessed. Conclusions: Results showed that liver lesion volumetry was strongly dependent on lesion size, contrast, acquisition dose, and their interactions. The overall performances were similar for images reconstructed with larger slice thicknesses, clinically used pitches, kernels, and doses. Conditions that yielded repeatable measurements were identified and they agreed with the Quantitative Imaging Biomarker Alliance’s (QIBA) profile requirements in general. The authors’ findings also suggest potential refinements to these guidelines for the tumor volume biomarker, especially for soft-tissue lesions

From colorectal cancer pattern to the characterization of individuals at risk: Picture for genetic research in Latin America

Colorectal cancer (CRC) is one of the most common cancers in Latin America and the Caribbean, with the highest rates reported for Uruguay, Brazil and Argentina. We provide a global snapshot of the CRC patterns, how screening is performed, and compared/contrasted to the genetic profile of Lynch syndrome (LS) in the region. From the literature, we find that only nine (20%) of the Latin America and the Caribbean countries have developed guidelines for early detection of CRC, and also with a low adherence. We describe a genetic profile of LS, including a total of 2,685 suspected families, where confirmed LS ranged from 8% in Uruguay and Argentina to 60% in Peru. Among confirmed LS, path_MLH1 variants were most commonly identified in Peru (82%), Mexico (80%), Chile (60%), and path_MSH2/EPCAM variants were most frequently identified in Colombia (80%) and Argentina (47%). Path_MSH6 and path_PMS2 variants were less common, but they showed important presence in Brazil (15%) and Chile (10%), respectively. Important differences exist at identifying LS families in Latin American countries, where the spectrum of path_MLH1 and path_MSH2 variants are those most frequently identified. Our findings have an impact on the evaluation of the patients and their relatives at risk for LS, derived from the gene affected. Although the awareness of hereditary cancer and genetic testing has improved in the last decade, it is remains deficient, with 39%–80% of the families not being identified for LS among those who actually met both the clinical criteria for LS and showed MMR deficiency.Fil: Vaccaro, Carlos Alberto. Hospital Italiano; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: López Kostner, Francisco. No especifíca;Fil: Adriana, Della Valle. Hospital Fuerzas Armadas; UruguayFil: Inez Palmero, Edenir. Hospital de cáncer de Barretos, FACISB; BrasilFil: Rossi, Benedito Mauro. Hospital Sirio Libanes; BrasilFil: Antelo, Marina. Gobierno de la Ciudad de Buenos Aires. Hospital de Gastroenterología "Dr. Carlos B. Udaondo"; Argentina. Universidad Nacional de Lanús; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Solano, Angela Rosario. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Carraro, Dirce Maria. No especifíca;Fil: Forones, Nora Manoukian. Universidade Federal de Sao Paulo; BrasilFil: Bohorquez, Mabel. Universidad del Tolima; ColombiaFil: Lino Silva, Leonardo S.. Instituto Nacional de Cancerologia; MéxicoFil: Buleje, Jose. Universidad de San Martín de Porres; PerúFil: Spirandelli, Florencia. No especifíca;Fil: Abe Sandes, Kiyoko. Universidade Federal da Bahia; BrasilFil: Nascimento, Ivana. No especifíca;Fil: Sullcahuaman, Yasser. Universidad Peruana de Ciencias Aplicadas; Perú. Instituto de Investigación Genomica; PerúFil: Sarroca, Carlos. Hospital Fuerzas Armadas; UruguayFil: Gonzalez, Maria Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Medicina Traslacional e Ingeniería Biomédica - Hospital Italiano. Instituto de Medicina Traslacional e Ingeniería Biomédica.- Instituto Universitario Hospital Italiano de Buenos Aires. Instituto de Medicina Traslacional e Ingeniería Biomédica; ArgentinaFil: Herrando, Alberto Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Medicina Traslacional e Ingeniería Biomédica - Hospital Italiano. Instituto de Medicina Traslacional e Ingeniería Biomédica.- Instituto Universitario Hospital Italiano de Buenos Aires. Instituto de Medicina Traslacional e Ingeniería Biomédica; ArgentinaFil: Alvarez, Karin. No especifíca;Fil: Neffa, Florencia. Hospital Fuerzas Armadas; UruguayFil: Galvão, Henrique Camposreis. Barretos Cancer Hospital; BrasilFil: Esperon, Patricia. Hospital Fuerzas Armadas; UruguayFil: Golubicki, Mariano. Gobierno de la Ciudad de Buenos Aires. Hospital de Gastroenterología "Dr. Carlos B. Udaondo"; ArgentinaFil: Cisterna, Daniel. Gobierno de la Ciudad de Buenos Aires. Hospital de Gastroenterología "Dr. Carlos B. Udaondo"; ArgentinaFil: Cardoso, Florencia C.. Centro de Educación Medica E Invest.clinicas; ArgentinaFil: Tardin Torrezan, Giovana. No especifíca;Fil: Aguiar Junior, Samuel. No especifíca;Fil: Aparecida Marques Pimenta, Célia. Universidade Federal de Sao Paulo; BrasilFil: Nirvana da Cruz Formiga, María. No especifíca;Fil: Santos, Erika. Hospital Sirio Libanes; BrasilFil: Sá, Caroline U.. Hospital Sirio Libanes; BrasilFil: Oliveira, Edite P.. Hospital Sirio Libanes; BrasilFil: Fujita, Ricardo. Universidad de San Martín de Porres; PerúFil: Spirandelli, Enrique. No especifíca;Fil: Jimenez, Geiner. No especifíca;Fil: Santa Cruz Guindalini, Rodrigo. Universidade de Sao Paulo; BrasilFil: Gondim Meira Velame de Azevedo, Renata. No especifíca;Fil: Souza Mario Bueno, Larissa. Universidade Federal da Bahia; BrasilFil: dos Santos Nogueira, Sonia Tereza. No especifíca;Fil: Piñero, Tamara Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Medicina Traslacional e Ingeniería Biomédica - Hospital Italiano. Instituto de Medicina Traslacional e Ingeniería Biomédica.- Instituto Universitario Hospital Italiano de Buenos Aires. Instituto de Medicina Traslacional e Ingeniería Biomédica; Argentin

Prise en charge en imagerie du traumatisé grave (hors radiologie interventionnelle)

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