Microwave　(MW)　ablation　is　a　minimally　invasive　therapeutic　strategy　for　the　local　treatment　of　solid　malignancies　that　has　received　much　attention　over　the　past　few　years.　It　is　very　important　to　detect　and　evaluate　lesions　generated　by　MW　during　treatment　procedures.　This　study　describes　one　new　ultrasonic　imaging　technique　to　characterize　lesions　based　on　estimation　of　relative　changes　in　tissue　properties　derived　from　backscattered　RF　data.　A　single　microwave　heating　antenna　was　used　to　produce　coagulation　in　vitro　pig　liver　tissues.　The　RF　signals　were　recorded　as　outputs　from　a　modified　diagnostic　ultrasound　system.　The　integrated　backscatter　values,　which　can　be　used　as　an　indicator　of　the　microstructure　and　backscattering　property　of　tissues,　were　calculated　in　water-bath　experiment　and　MW　treatment.　The　rule　of　change　in　integrated　backscatter　values　with　temperature　has　been　analyzed　by　statistics　through　water-bath　experiment.　The　integrated　backscatter　ratio　values　were　subsequently　used　to　form　images　revealing　the　lesion　areas.　It　is　possible　using　ultrasonic　integral　backscatter　to　monitor　microwave　coagulation.　The　result　shows　that　this　approach　can　be　used　to　identify　the　normal　and　coagulated　tissue　caused　by　temperature　rise　and　provide　the　information　of　tissue　damage.　©　2010　IEEE.