Study On Invasion Of Gastric Wall In Advanced Gastric Cancer By Triphasic Spiral CT

Purpose: To analyze the features and to evaluate intramural invasion ofadvanced gastric cancer by triphasic spiral CT. Methods: Triphasic spiral CTand doub1e-contrast upper gastrointestinal examinations were performed in31 patients with advanced gastric cancer proved histologically Hypotonicagent (654-2) im and water filling of the stomach were administrated beforeCT scan. Axial CT images were obtained at 25~30 sec (arterial-dominantphase) \ 70~80sec (nonequilibrium phase, be equal to portal venous-dominant phase) and 180~240sec (equilibrium phase) after the start of bolusinjection and multiplanar reconstruction (MPR) images were obtainedthereafter. Results: The detectability by triPhasic spiral CT scanning ofadvanced gastric cancer was 100%. The thickness and length of the lesions were19.79t10.50mm and 79.98t29.48mm respectively 82.l4%(23/28) could bedistinguished and 17.86%(5/28) indistinguished clearly with normal gastric wall.Uninvolved gastric wall showed as a smooth line and homogeneousenhancement. The enhancing appearances of 1esions were varied in differentphases. In the arterial-dominant phase, 35.48% of the lesion showed two lnyerswith a marked enhancement in the inner side and unenhancement in the outerside; 51 .62% showed heterogeneous enhancement within the lesions and 12.90%showed mild homogeneous enhancement of the entire tumor. 67.74% of thecases (21/31) demonstrated most clearIy in the arteriaLdominant phase. In thenonequilibrim phase, 64.52% showed that the enhancing degree in the inner sidedecreased while that in the outer side increased. Therefore, the whole lesionshowed heterogeneous enhancement; 19.35% showed three layers with markedenhancing inner lnyer, massbe enhancing outer layer and a discontinuous 1ow-attenuation stripe between them; l6.13% showed homogeneous enhancement.l2.90% of the cases (4/3l) demonstrated most clearly in the nonequilibrimphase. In the equilibrium phase, 87.10% showed homogeneous enhancementwith decrease of their enhancing degree; in 12.9l% of the cases, their enhancingdegree decreased, but sti1l stratified. 6.45% of the cases (2/3l) demonstratedmost clearly in the equilibrium phase. 12.90% of the cases (4/31) demonstrated fclearly in all the three phases. Correlating with pathology the overall accuracyof T-staging was 78.94%(15/l9). The accuracy of differentiation between T2and T3 lesions was 8l.25%(13/16). MPR prevented T-staging error in 3advanced gastric cancer. Conclusion: Arterial-dominant phase scanning oftriphasic spiral CT with hypotonia and water fi1ling is useful c1inica1ly indetecting tumor and evaluating its extent along the gastric wall. The equilibriumphase scanning has high accuracy in evaluating the depth of tumor invasion.For discovering liver metastasis, nonequi1ibrium phase is necessary. MPR ishelpful in further viewing the re1ationship of the lesion with its adjacent organs.