Currently D₂ lymph node dissection is considered as minimal extent of dissection in curative resection of gastric cancer. This study was conducted to investigated the patterns of lymph node metastasis of gastric cancer and to validate extent of lympn node dissection.

Among 117 patients with gastric cancer, 35 patients with early gastric cancer and 45 with advanced gastric cancer underwent curative gastric resection were enrolled in this study. Removed lymph nodes were classified as N₁(1~6), N₂(7~11), N₃(12~16) and the boundary of dissection was classified as D₁, D₂, D₃, D₃+α according to classification of stomach cancer research association in Korea.

The priportion of early gastric cancer was 30%(35/117). Average number of metas-tatic lymph nodes was 2 in stage II, 6 in stage IIIa, 13 in stage IIIb, 21 in stage IV(p<0.05). 2 patients with early gastric cancer had metastatic lymph node(N₁) and their lesions were over 3.0cm in size, depressed in shape. In terms of differentiation, 25(62%) patients with stage I, D1 dissection was carried out in two(5%), D₂ dissection in eleven(28%), D₃ or D₃+α dissection in twenty seven (67%). In the patients with over stage II, there was no D₁ dissection, D₂ dissection was performed only in 3(7%), D₃ or D₃+α dissection in 37(92%). Extended lymph node dissection was significantly much higher in advanced cases than in early cases. The average number of resected positive lymph nodes were higher in BORRMANN type III or type IV than in type II(p<0.01, p<0.05 respectively). All patients with positive N₂ or N₃ lymph nodes revealed the positive N₁ lymph nodes. There were 2(25%) skipped metastasis among 8 patients with positive N₃ lymph nodes.

At least D₂ lymph node dissection is needed for curative resection of gastric cancer in the patients with possible metastasis of N₁ lymph nodes, even in the those we early gastric cancer. D₃ or D₃+α dissection should be performed in the patients with possible metastasis of N₂ lymph nodes among advanced gastric cancer, even in the patients without metastasis of N₂ lymph nodes selectiely because of skipped metastasis.

We studied to determine the usefulness of dynamic magnetic resonance imaging(MRI) in the preoperative evaluation of invasion of colorectal cancer and to compare its usefulness with the conventional CT. To observe the enhancement pattern of colorectal wall after iv administration of Gd-DTPA between normal and cancerous wall.

Twenty patients with colon cancer and 8 patients with rectosigmoid cancer, who were diagnosed between October 1997 and June 1998 by barium enema, colonoscopic biopsy were evaluated. The patients population consisted of 16 men and 12 women, with ages ranging from 46 to 68 years(mean 61years). Preoperative staging was done by conventional CT and dynamic MRI. All MR images were performed with 1.5T superconducting magneting unit(Vision, Siemens, Erlangen, Germany). 2D-FLASH(Fast Low-Angle Shot) sequence was used for the dynamic and delayed images(TR/TE/NEX/FA=72.5-117.3/4.1/1/80°), and acquisition time of 13-15sec.

For the dynamic images, five MR images were obtained with a single breath hold. Precontrast images(axial, or sagittal or coronal) was obtained first, and then dynamic MR images were obtained at 30, 60, 90, 120sec after intravenous injection of 0.1mmol/kg Gd-DTPA. Ten to fifteen delayed images were also obtained with the interval of 4-5 minutes with a single breath hold. Preoperative staging of CT and MRI were decided with a consensus by two radiologists. Pathologic staging were done by TNM classification.

The dynamic MR image-determined stage of colorectal cancer correlated with histopathologic findings in 2 of 3 pT2 tumor(67%), 19 of 21 pT3(90%), and 4 of 4 pT4 tumors(100%). MRI correctily diagnosed tumor deposits of involved lymph nodes in 16 patients, overall accuracy was 57%(16/28%). And the signal intensities after IV Gd-DTPA administration between the cancerous wall and normal wall ws not significantly different at the 30, 60, and 90 seconds MR images with the indifferent Student t-test(p>0.05).

Dynamic MRI has a role for the preoperative assesment of colorectal carcinoma.