D3 and D4 lymphadenectomies include their respective compartments. AJCC criteria designates involvement of hepatoduodenal, retropancreatic, mesenteric, and para-aortic nodes (i.e., compartment III and IV) as distant metastases (9). CT criteria for lymph node metastases include size, shape, central necrosis and heterogeneity (13), (14). When these characteristics are present there is a strong correlation with metastatic involvement. However, CT sensitivity suffers because a small tumor burden in a lymph node is unlikely to produce

Inhibitors,research,lifescience,medical the morphological changes sufficient to satisfy CT criteria. In concept, PET seems an excellent adjunct therapy to detect these anatomically small but potentially metabolically active focuses of metastatic disease. However, the relatively poor spatial resolution of PET makes it less effective because of the difficulty of distinguishing Inhibitors,research,lifescience,medical compartment I and II nodes from the primary tumor itself. The real value of PET may be in the detection of “distant” Inhibitors,research,lifescience,medical metastatic disease in compartments III and

IV and not amenable to surgical resection with a standard D2 lymphadenectomy. Identification of further spread with PET imaging may influence surgical planning for a more aggressive lymphadenectomy or the decision to avoid surgery altogether as futile and unnecessarily morbid (15). Solid organ metastasis from the stomach occurs most commonly in the liver via hematogenous dissemination through the portal vein (16), (17). Lymphatic and peritoneal dissemination are also Inhibitors,research,lifescience,medical common pathways of spread in gastric malignancy. Although distant metastases are frequently detectable using contrast CT, PET is perhaps most useful in the detection of

these distant sites of solid organ metastases. A meta-analysis by Kinkel designated PET as the most sensitive noninvasive imaging modality for this purpose (18). Because radio-tracer is distributed throughout the body, larger volumes can be more Inhibitors,research,lifescience,medical easily scanned than is practical with CT. Peritoneal dissemination is a poor prognostic factor. Detection of peritoneal metastases may change the surgical strategy from curative to palliative or deter the surgeon through from laparotomy altogether. Increasingly sophisticated CT scans facilitate diagnosis of peritoneal metastases prior to visual inspection during surgery. PET may give additional sensitivity to CT. Diffuse uptake of tracer that obscures the serpiginous DAPT secretase cost outline of the bowel may be an indicator of peritoneal metastases, as well as discrete areas of local uptake along areas within the peritoneal cavity that are otherwise anatomically unexplained (i.e. outside expected nodal stations or solid viscera) (11). Response to therapy PET may predict response to preoperative chemotherapy in gastric cancer. Ott et al.