Objective To further improve the amount of gadolinium located on tumor, a gadolinium chelate enhanced magnetic resonance imaging pretargeting with avidin-biotin system technique was adopted and the enhancing characteristics of difference of signal intensity at various scan timing were investigated in our experiment. Methods (1) Anti-CEA antibody CL -3 was biotinylated in a mixture with antibody to NHS-LS-biotin with a molar ratio of 1/30-50. (2) After the reaction of GdCl 3 and DTPA-B, the unconjugated gadolinium was removed by chromatography on G-10 column. (3) Steps for pretargeting tumor: First step, McAb-B was injected intravenously into nude mice on the first day. Second step, avidin (Av) and streptavidin (SA) were injected intraperitoneally 24 hours later. Third step, Gd-DTPA-Bt was injected intravenously 48 hours after the first injection. MRI was performed with plain scans, enhanced scans at 20 minutes, 2 hours, 8 hours, and 24 hours after the third step. Signal intensities of tumor and muscles were measured. The pretargeting effect was compared with those of Gd-DTPA-McAb and Gd-DTPA. Results (1) Each monoclonal antibody conjugated with 11-23 biotin and the immunoactivity of biotinylated antibody with 12 biotin/antibody was 94.9%. (2) The enhancing effect of pretargeting approach was tumor specific. Contrarily that of Gd-DTPA was not. (3) The enhancing rate of signal intensity specificity of pretargeting approach was 43%, while that of McAb-Gd-DTPA was 17.9% only, so the enhancing ratio was 2.4. Conclusion Pretargeting approach using avidin -biotin system improves the amounts of gadolinium locating on tumors and yields a specific enhancing effect. It is a promising modality which promotes the ability of Gd labeled magnetic resonance immunoimaging in the detection of colon cancer and its recurrence.

Objective:To explore the ultrasonography and classification management strategy for adult atrial septal aneurysm (ASA).Methods:Of 138 patients diagnosed with ASA by the transthoracic echocardiography (TTE), in No.83 Army Hospital and No.988 Hospital of Joint Logistic Support Force from January 2015 to October 2019, 103 underwent the transesophageal echocardiography (TEE), and all were examined by the right heart contrast transthoracic echocardiography (cTTE). According to the semi-quantitative method, the shunt was graded, classified, and managed through follow-up or surgical treatment.Results:In the resting state, among 138 patients, 26 cases were detected by TTE as ASA with patent foramen ovale (PFO), showing left-to-right shunt. Among 112 patients with no shunt detected by TTE, 103 cases underwent TEE, of whom 44 cases had PFO and left-to-right shunt. The detection rate of PFO shunt by TEE was significantly higher than that of TTE (42.72% vs 18.84%, P<0.001). Out of the 138 patients who underwent cTTE, 96 cases had different degrees of right-to-left shunt. According to the semi-quantitative standard, there were 15 cases of grade Ⅰ, 28 cases of grade Ⅱ, and 53 cases of grade Ⅲ. The detection rate of cTTE was significantly higher than that of TTE and TEE (69.56% vs 18.84% and 42.72%, both P<0.001). Among these 96 patients with right-to-left shunt detected by cTTE, 52 cases (54.17%) were clinically diagnosed as cryptogenic stroke, with right-to-left shunt in 6 cases of grade Ⅰ, 12 cases of grade Ⅱ, and 34 cases of grade Ⅲ. The number of new infarcts in patients with grade Ⅱ or Ⅲ shunts who received PFO closure via catheter was significantly lower than that of patients who did not receive closure therapy (0 vs 27.27%, P=0.011). Conclusion:ASA combined with PFO and right-to-left shunts were detected more frequently by ultrasonography combined with cTTE in adults, this helps to formulate a reasonable management strategy.