Preliminary Study On Trlationgship Between Ultrasound Ablation For Uterine Fibroids And Signal Of MR Imaging

BackgroundUltrasound ablation ( UA) is the novel physics treatment technology that is developing quickly in 1980s. It is good penetrative, directionality and localization, and transiently (60～100℃) creates high temperature in focus localization. Because only the temperature of the target area arises, the cells around of the target area are safe. So it can ablate precisely according to the shape of the tumor. UA has treated widly all kinds of malignant tumors, such as liver cancer,prostate carcinoma,breast carcinoma,pancreatic cancer. In 2002 Wang Wei had successed treating the benign tumor--uterine fibroids, and got the satisfactory therapeutic effect. Recently many studies have documented that there is a obvious relationship between the decreased volume of fibroids and the degree of release of symptom. So how to find the best imaging method to value the effect is a key. The methods of value the effect of hypertherm ablation contain ultrasound visualization,contrast-enhanced scanning of CT,contrast-enhanced scanning of MRI, and so on. They value the effect by blood perfusion and cell metabolism. Ultrasound visualization can detect the blood perfusion, but lower resolving power . contrast-enhanced scanning of CT can observe the relationship clearly between focus of infection and tissue around it, but harm of irradiation. There is higher resolution,no irradiation,3D-visualization in contrast-enhanced scanning of MRI which is a better method, but more expensive. About the effect of ultrasound ablation, many researcher study in malignant tumors such as liver cancer,carcinoma of prostate.The purpose of the paper is to observe the rule of the change of the MRI, finding a simple method to judge the appearance of the coagulation necrosis.ObjectiveTo summarize the rule of the change of the MRI in the early period of ultrasound ablation , provide one of rules that judge the coagulation necrosis, save the resource of medical treatment.Materials and Methods1 Study subject: Patients of uterine fibroids that are suit to UA.2 UA treatment: JC-focused ultrasound tumor therapeutic system was used. The patients finished the preparation of the intestinal tract and skin. They were given Fentanyl and Midazolam to sustain awaking in ultrasound ablation. Patients prone in treatment bed, then treatment began by ultrasound guided therapeutic system. It is necessary to protect the skin,intestinal tract and nerves. Blot sonication. When there is change of gray in the the target area, replace the therapy area until finish the whole planning therapy area.3 Research and Observation indication 3.1 Result of qualitation about the change signal of MRI: patients were given MRI 1 week before and 4～8 weeks after the therapy. MR-signal contact high-signal,intermediate-signal and low-signal Detecting T1-weighted/T2-weighted and comparing the changes of the signal. Dynamic contrast-enhanced scanning showing non-perfusion is the gold standard of coagulation necrosis. Compared change of signal before and after ablation, and detect the relationship between signal and ablation.3.2 Result of quantifcation about the change signal of MRI: patients were given MRI 1 week before and 4～8 weeks after the therapy.Apply the hifuMar soft ware that can automatic drawing on target area to get the MR-value, including normal uterine muscle,uterine fibroid of before and after UA on T1WI. Dynamic contrast-enhanced scanning showing non-perfusion is the gold standard of coagulation necrosis. Compared with the change of MR-value on T1WI, and find a dialogue value that can judge the coagulation necrosis correctly.Results1 Results of qualitation: Before therapy on T1-weighted:①high-signal 1.2%,intermediate-signal 91.3%,low-signal 7.5%;②after therapy high-signal 83.8%,intermediate-signal 35.3%,low-signal 0; high-signal 100% (67/67) show necrosis; intermediate-signal 35.3% (6/13) show necrosis(P<0.05);③66 signal increase to high-signal, 100% (67/67) show necrosis, 14 signal no change,100% (7/14) show necrosis(P<0.05);④ relationship of volume between high-signal on T1-weighted and necrosis is liner (r=0.93,P<0.05).2 Results of quantifcation on T1WI: 109 massive ablated fibroids. 7 sporadic ablated fibroids(rejected).①before and after UA the myometrium is not obviously different (p>0.05);②the MR-values of ablated area are higher than the non-ablated area,fibroids and myometrium(P<0.05). The MR-values of non-ablated area,fibroids and myometrium are not obviously different (p>0.05);③after UA When the MR-value is 215, Se=0.58, Sp=0.97, PV+=0.98, PV-=0.57 , the difference of MR-value in therapeutic area and myometrium is 10.5, Se=0.91, Sp=0.86, PV+=0.92, PV-=0.85.ConclusionsAfter ultrasound ablation, MR signal on T1WI obviously becomes higher, and the high signal has much with the ablation. After UA the MR-value=215 and the difference of MR-value in therapeutic area and myometrium=10.5 can be as to the reference value that blots the appearance of ablation. The volume of ablation can be valued probably by the volume of high-signal area.