When we're treating these tumors for local tumor control we're really aggressive in ablating them. So we have a rib metastasis here, and we won't just put one probe in it and call it a day. We have to make sure that we have adequate cold temperatures surrounding the entire tumor with margin
to make sure that we can provide a long-lasting effect for these patients, rather than this case in which patient has a spinal metastasis, we put one probe in part of it and leave a little corner of tumor
when our goal is local tumor control that's not really adequate. And local recurrence really matters so in this study this is one example study of a patient who had surgical replacement of renal cell carcinoma, bone metastases.
And in this study they show that threefold higher hazard ratio of death in patients who develop local tumor recurrence at the site of the resection. So if we can, extrapolating that surgical data to ablation we wanna make sure we get that local control.
Unfortunately as we treat aggressively we are more at risk for developing complications. In this large metastasis that's in the supra-acetabulum here we try to be very cautious that we don't actually have that ice ball encroach upon the femoral head,
as opposed to this equally large metastasis in the supra-acetabulum where we actually have the ice that if you extrapolate those into that femoral head and then several months later the patient develops femoral head collapse and fracture, and their pain recurs.
But it's really key to pay attention during
you know, your procedure. Patient movement during the procedure leads to misregistration of the overlay objects. And inaccurate needle placement. And so you really have to kind of periodically verify this registration and alignment.
This an example just from a case where you can see that the overlay is off from the actual fluoroscopic image. Which means that all of the objects that are tied to that overlay are also gonna be off.
And so while the needle guidance and the advanced imaging can be helpful, you do have to kind of pay attention as a proceduralist to what you're doing, and whether it makes sense fluoroscopically. So you can see here that this
bullseye orientation needle guidance placement is really not exactly where it needs to be. It really should be shifted over a little bit more, into this AP corridor. So registration becomes kind of a iterative process during cases.
Segmentation or volumetric overlay is basically overlaying either a shaded volume or a contour of a volume. The edges of the overlay volume can kind of be tangential to whichever orientation of the detector,
as it changes in real time. Again, drawn on the cross sectional CT data, using kind of segmentation type software. The use of this is really to mark a volume, or kind of a curvilinear surface. So you can either use this as to mark target volumes
that you're intending to ablate or cavities that you're intending to fill with cement. But you can also mark areas that you want to stay away from. Particularly in say the joint space, or the acetabulum or such. So this is an example, kind of on the left,
of you know, two different areas, volumetric areas kind of segmented out on the cross sectional data and how this looks on the three dimensional volumetric model on the right. So the yellow would be kinda this area of tumor, and destruction in the bone that we're intending to fill,
and the red being the actual joint space itself, that we wanna stay out of.