['We studied stagnation of the blood in hepatic metastatic lesions of colorectal cancer.', 'Twenty-two hepatic tumors in 11 patients with liver metastases of colorectal cancers were investigated in this study. With a catheter inserted into the roots of the proper hepatic artery, 5 to 10 mCi 133Xe was injected. The half-time (t1/2) was calculated for the tumor region based on the washout curve by the compartmental method and expressed as the intratumor retention time of the blood.', 'Transcatheter arterial chemoembolization with iodized oil (Lipiodol) and cisplatin was effective in eight (50%) of 16 tumors that were hypervascular but in only one (17%) of six tumors that were hypovascular (p < 0.05). Regardless of the hypervascular tumor, transcatheter arterial chemoembolization was not effective in tumors that had shown a t1/2 of less than 80 seconds. Seven of eight good-responding lesions that were hypervascular and had a long t1/2 (187 +/- 74.6 seconds) revealed characteristic fireworks-shaped accumulation of Lipiodol.'] Is delayed washout of intratumor blood flow associated with good response to intraarterial chemoembolization for liver metastasis of colorectal cancer?