 Thus far, we've discussed the differential diagnosis for astrocytoma and the pandemoma, recognizing that none of the imaging findings are absolutely reliable in making that distinction. We usually say that we're somewhere around the 70% range. We can do a little bit better with the next lesion. In this case, we again have a cervical spine lesion, and we see that the lesion has both a cystic as well as solid portion to it. Now, as I magnify this one image, you might ask the question, well, is it truly cystic, or is that just cord edema? And for that, we look at the stir image as well. And what we can see is, once again, that there does appear to be a fluid area that is corresponding to the darker signal intensity on the T1-wayed skin, more likely representing fluid rather than actual cord edema, which would be not as dark on the T1-wayed skin. So let me just magnify the T1-wayed skin and try to use my pointer here. Okay, so this is what I'm referring to. This is darker than edema. Edema might be up here, but this darker area is what is represented as a more cystic area to this mass. Now, unfortunately, astrocytomas and the pandemomas may have cystic areas. Well, let's look at the post-gadolinium enhanced image on this patient. On the post-gadolinium enhanced scan, let's magnify. What we see is a mass that has a solid area of contrast enhancement associated with the cystic area, and it's relatively well-defined and small in size. I'm just going to try to window this a little bit better for maximum benefit. Once again, the cystic component, the solid component, and then a small cystic component below. So this well-defined mass associated with nodular enhancement, as well as a cystic component, is more indicative of the hemangioblastoma for the diagnosis. One would look for additional lesions and lesions in the posterior fossa in order to make sure that the patient does not have the syndrome of von Hippel-Lindau disease. Von Hippel-Lindau disease has multiple hemangioblastomas, and in point of fact, it may have other lesions, such as renal cell carcinoma or pancreatic cysts and adenomas, et cetera. In the temporal bone, one can also see the endolemphatic sac tumor, which may be associated with Von Hippel-Lindau disease. But this is a pretty good classic case of muronadural with cyst, small lesion, well-defined hemangioblastoma of the spinal cord. We say that with hemangioblastoma, one-third of patients who have spinal cord hemangioblastomas have Von Hippel-Lindau disease, and one-third of patients who have Von Hippel-Lindau disease have a spinal hemangioblastoma.