Section for Residents L S: U E Diego Sebastián de Jesús Castro Abstract Resumen The liver is the largest solid organ in the normal abdomen that oc - El hígado es el órgano sólido de mayor tamaño en el abdomen nor - cupies the right hypochondrium. It weighs 1500 grams approxima - mal, ocupando el hipocondrio derecho. Pesa 1500 grs aproximada - tely and has a reddish brown coloring. The Anatomy of surface mente y tiene una coloración parda rojiza. En la anatomía de recognizes 4 lobes. The first anatomist to study liver division was superficie se reconocen 4 lóbulos. El primer anatomista que estudió James Cantlie. In 1957, Goldsmith and Woodburne proposed a liver la funcionalidad hepática fue James Cantlie. En 1957, Goldsmith y segmentation system based on the suprahepatic veins. In 1957, Coi - Woodburne proponen un sistema de segmentación hepática basado naud proposed another segmentation following the portal branches en las venas suprahepáticas. En 1957, Coinaud propone otra si - from the superior view, in clockwise and in spiral sequence matching guiendo las ramificaciones portales, en el sentido de las agujas del the districts or "arrondissements" of Paris. That is to say the supra - reloj con números romanos, en secuencia espiral coincidentes con hepatic veins act as limits of independent biliary drainage and irri - los barrios o “arrondissements” de París. Es decir que las venas su - gation areas. For liver segmentation will make axial and prahepáticas actúan como límites de áreas de irrigación y drenaje longitudinal views using 3.5-5 Mhz convex probes in epigastrium, biliar independientes. Para la segmentación hepática realizaremos with angles toward right and left shoulder, allowing the visualization cortes axiales y longitudinales utilizando sondas convex de 3.5-5 segments I, II, III, IVa and b, V and VIII respectively, while with sa - MHz., en epigastrio, con angulaciones hacia hombro derecho e iz - gittal view in axillary line display segments VI, VII and VIII. Finally quierdo, permitiendo visualizar segmentos I, II, III, IV a y b, V y VIII parasagittal views will make possible to complement the visualiza - respectivamente, en tanto que con cortes sagitales en línea axilar tion of segments I, II, III, V and VIII. Understanding the anatomy visualizaremos segmentos VI, VII y VIII; finalmente los cortes para - and making correct interpretations would bring a number of unde - sagitales permitirán complementar la visualización de segmentos niable advantages for the surgeon. The segmental liver resection is I, II, III, V y VIII. Es así que el conocimiento de la anatomía y la the treatment of current choice for various diseases and tumor pro - correcta interpretación aportan una serie de ventajas innegables cesses. While Ultrasound presents the disadvantage of being opera - para el cirujano. La resección segmentaria del hígado constituye el tor-dependent, it is a method that is simple and easy to use and, at tratamiento de elección actual de las diversas afecciones y procesos the same time, it allows a significant correlation with the anatomy. tumorales. Si bien la ecografía presenta la desventaja de ser opera - dor-dependiente, es un método sencillo y fácil de utilizar, al mismo tiempo que permite una correlación notable con la anatomía. key words: Liver segmentation – Ultrasound evaluation. Palabras claves: Segmentación hepática- Evaluación ecográfica. Contact: Diego Sebastián de Jesús Castro Hospital Centro de Salud Zenón Santillán. Recibido: de abril / Aceptado: de mayo San Miguel de Tucumán - Tucumán, Argentina. Recieved: April , / Accepted: May , e-mail: [email protected] Rev. Arg. Diag. por Imágenes Vol. / Nº - Agosto, . Liver Segmentation: Ultrasound Evaluation. Castro, D. Introduction and the vena cava at the back (Fig. 2). Physicians who studied the intrahepatic division could deter - The liver is the largest solid organ in the normal ab - mine the segmentation based on the vascular and domen and it occupies the right hypochondrium al - biliary anatomy. (1, 3, 4) most entirely (Fig. 1). It weighs approximately 1,500 The first anatomist who understood that the truth grams and has a reddish brown color. It stays in its functional division of the liver did not correspond position thanks to the inferior vena cava, to which to the superficial anatomy was Sir James Cantlie, it is connected by the suprahepatic veins, to the from Scotland. Taking into account the distribution liver round ligament which replaces the umbilical of the vascular tracts, in 1987 he proposed a sepa - vein in adults, and to peritoneal attachments such ration through the plane delimited by the vesicular as coronary and triangular ligaments. bed and the inferior vena cava (called from then on From the purely anatomical point of view, it is di - Cantlie line) (Fig. 3). vided into 4 lobes: Right lobe, located at the right The current concept of an organ segment is: "The of the falciform ligament; left lobe, extended over smallest portion of an organ which contains the the stomach and located to the left of the falciform same elements of the hilum and which performs ligament; quadrate lobe, only visible in the interior the same functions of that organ." face of the liver and limited by the venous ligament to the left (Arantius canal or venous ductus), by the vesicular bed to the right and by the hepatic portal; caudate lobe or Spiegel's lobe, located between the posterior margin of the hepatic portal at the front Fig. : The liver is the largest solid organ in Fig. : Scheme of the liver surface anatomy the normal abdomen; it occupies the shows from the middle of the liver up, right hypochondrium almost entirely. the division of the liver into right and left lobes, over the anterior and supe - rior face, by the falciform ligament. From the middle of the liver down, the inferior face with quadrate and cau - date lobes. Rev. Arg. Diag. por Imágenes Vol. / Nº - Agosto, . Liver Segmentation: Ultrasound Evaluation. Castro, D. Fig. : Sir James Cantlie. First anatomist, from Scotland, who understood the functional liver division and who, in , proposed the distribution of vascular beds by a separation through the plane delimited by the vesicular site and the inferior vena cava (which came to be known as Cantlie line). Liver Segmentation lobe and divides it in a lateral and a paramedian "sector"; whereas the left lobe has the plane of the In 1957, Goldsmith and Woodburne proposed a left suprahepatic vein as a limit of the medial and segmentation system for the hepatic anatomy based lateral sectors, since they are considered terminal on the distribution of the hepatic veins: segmentary branches from the portal vein to the Middle hepatic vein which separates the right umbilical portion of the left branch (for the seg - lobe from the left lobe; right hepatic vein which di - ments IVa and IVb) and to the segment II. vides the right lobe into two segments, anterior and In Brisbane in 2000, the terminology committee posterior; left hepatic vein which divides the left of IHPBA (International lobe into two segments, medial and lateral; caudate Hepato-Pancreato-Biliary Association) agree on a lobe which is a separate segment, limited by the global division and terminology, based on the func - IVC at the back, having the venous ligament fissure tional and surgical anatomy of three orders: as an anterior margin. • First-order division: cut plane which goes According to Coinaud, the intrahepatic branches through the middle suprahepatic vein, dividing the of the portal vein do not coincide with the planes hemi-liver into right and left. of the suprahepatic veins tract. As a result of this • Second-order division (intersectional planes): premise, both venous systems are interdigitated. based on the alternation between the glissonian pe - That is to say that the suprahepatic veins act as li - dicles and hepatic veins, the right hemi-liver is di - mits of irrigation areas and independent biliary drai - vided into a posterior and an anterior segment, nage. Based on the intrahepatic distribution of the following the right suprahepatic vein (intersectional glissonian pedicles, in 1957 Coinaud presented a plane). On the other hand, the left hemi-liver is di - hepatic systematization in segments, numbering vided into medial and lateral segment, following the them clockwise for the frontal upper face and coun - round and falciform ligament plane. terclockwise for the lower face, with roman num - • Third-order division: these are the intersegmen - bers, inspired by the same spiral sequence of the tal planes, dependent upon the glissonian pedicles. neighborhoods or "arrondissements" of Paris. The In this case, segments are numbered with Arabic systematization is also based on the intraparenchy - numbers, instead of Roman. matous distribution of the hepatic hilum branches (Each of these sections is divided transversally by and on the hepatic areas dependent upon the hilum an imaginary plane which goes through the origins (Fig. 4). of the right and left Portal Vein). (1, 2) Coinaud keeps the American division of the right Rev. Arg. Diag. por Imágenes Vol. / Nº - Agosto, . Liver Segmentation: Ultrasound Evaluation. Castro, D. At present, surgeons can excise hepatic subseg - Dorsal intermediate caudate segment ments. The system by Coinaud divides the left late - 7. Upper posterior lateral zone - Segment VII - ral, anterior right and posterior right segments into Dorsal intermediate cranial segment upper and lower subsegments, and keeps the cau - 8. Upper frontal lateral zone - Segment VIII - Ven - date lobe and left middle segment as unique seg - trocranial segment ments. This data was obtained from the IHPBA Termino - Hence, we recognize the following anatomic seg - logy Committee in the IHPBA 2000 World Congress ments (classification by Healey-Coinaud-Hjorstjo- in Brisbane, Australia (5-7). Woodburne): For this article, it is necessary to remember the 1. Caudate lobe - Segment I - Dorsal segment anatomic characteristics of the liver and know the 2. Lateral upper zone - Segment II - Dorso-lateral imaging characteristics of the ultrasound evaluation, left segment in order to be able to correlate the theory with the 3.