Radio　frequency　ablation　(RFA)　is　a　widely　used　alternative　modality　in　the　treatment　of　tumors.　During　RFA,　temperature　monitoring　is　essential　to　ensure　accurate　and　appropriate　thermal　dosage.　Ultrasound　temperature　imaging　based　on　the　detection　of　echo　time-shift　has　been　demonstrated　to　have　good　ability　to　monitor　the　temperature　distribution.　However,　no　study　has　proven　that　the　region　of　ultrasound　temperature　imaging　can　correspond　well　to　the　practical　temperature　distribution　in　the　tissue.　In　this　study,　we　aim　to　combine　ultrasound　and　infrared　systems　to　clarify　the　correlation　between　ultrasound　temperature　imaging　and　the　practical　temperature　distribution　in　a　tissue.　Five　porcine　livers　(n　=　5)　were　ablated　using　an　RFA　system　and　monitored　with　an　ultrasound　system　to　acquire　raw　backscattered　data　for　temperature　imaging.　Meanwhile,　an　infrared　imaging　system　was　used　to　obtain　the　practical　temperature　map　of　the　tissue.　The　results　showed　that　the　temperature　distribution　detected　by　ultrasound　echo　time-shift　agreed　with　those　obtained　from　the　infrared　image.　When　the　tissue　temperature　was　higher　than　45　degrees　C,　ultrasound　temperature　imaging　is　difficult　to　describe　the　behavior　of　the　heat　transfer　in　a　homogeneous　medium.　In　this　study,　we　used　the　experimental　setup　based　on　combining　ultrasound　and　infrared　systems　to　confirm　the　reliability　and　limitations　of　ultrasound　temperature　imaging　in　RFA　monitoring.　Such　an　experimental　design　may　be　considered　as　an　indispensable　platform　for　the　development　and　optimization　of　ultrasound　temperature　imaging　techniques　in　RFA　monitoring.　(C)　2014　The　Japan　Society　of　Applied　Physics