Usefulness of collagen type IV in the detection of significant liver fibrosis in nonalcoholic fatty liver disease José Tadeu Stefano; Laura Vilar Guedes; Arthur Alencar Arrais de Souza; Denise Siqueira Vanni; Venâncio Avancini Ferreira Alves; Flair José Carrilho; Alvaro Largura; Marco Arrese; Claudia P. Oliveira;