A catheter including an elongated shaft having a distal end and a proximal end, where the catheter includes a thermal element at the distal end thereof. The thermal element may be used in an ablation procedure or other procedure to heat a tissue adjacent a vessel. In some instances, the thermal element may be positioned in a first vessel and may operate to heat tissue adjacent a second vessel or adjacent an ostium between the first vessel and the second vessel. Further, the catheter may include an expandable portion on which the thermal element may be connected or positioned. The expandable portion(s) may comprise a basket or cage, a balloon, a memory shape and formable portion, and/or other mechanical expanders.