Delivery systems, and methods using the same, having an ultrasound viewing window for improved imaging and a needle for ablation treatment of target tissues. In an embodiment, the target tissue is a fibroid within a female's uterus. In an embodiment, the delivery system includes a rigid shaft having a proximal end, a distal end, and an axial passage extending through the rigid shaft. In an embodiment, the axial passage is configured for removably receiving the ultrasound imaging insert having an ultrasound array disposed a distal portion.