 So this next patient is a 40-year-old female in the history of a gastrointestinal stromal tumor involved in the stomach and the staging CT scan was performed for further evaluation. So as we scroll through her CT imaging, we'll note that there is rather large mass within the left hepatic lobe. We can see it over here. Patient is status-posed cholecystectomy and scroll up and down through this indeterminate imaging features. So an MRI was requested to further evaluate this. So we'll start our evaluation of this patient's MRI looking at the T2 weighted sequence. And on the T2 weighted sequence performed without fat saturation, we can see a rather large mass within the left hepatic lobe. And if we were to look at its internal T2 contents within it, it looks different from some of the other stuff we've seen so far in that it's not particularly bright. Certainly not as bright as the CSF over here. And if anything, it sort of looks similar to the adjacent liver parenchyma over here. So I would say this is iso intense or minimally hyper intense with respect to the liver parenchyma on the T2 weighted images. Internally, we note that there are clefts within it over here and over here and over here, perhaps some in this location that are slightly more T2 hyper intense. We'll get back to what those represent in a little bit. On the T2 weighted sequence performed with fat saturation, we can again look at the signal within this lesion. Again, we use these turbospinecophatsat sequences to really determine the T2 content of these lesions. And again, looks quite similar to the adjacent liver parenchyma, maybe iso to slightly hyper intense on the T2 weighted images with respect to the liver parenchyma. And it certainly has these clefts within it that are much more T2 hyper intense. The next set of sequences to look at are the T1 in and out of phase. And this is what the lesion looks like on those sequences. In the out of phase image, it is iso to slightly hyper intense with respect to liver parenchyma. So it looks somewhat similar but not quite the same. And similar to the in phase image, it looks iso to slightly hyper intense with respect to the liver parenchyma. There are no areas of diminished signal on the out of phase images to suggest fat within this lesion. And there's no increased susceptibility artifact on the in phase images. At the periphery of this lesion, there is some increased susceptibility artifact over here. And that just comes from colisostectomy clips in this patient who had a prior gallbladder surgery. We'll then proceed to our T1 fatsat pre contrast image. And on this image, we can also see that the lesion overall has signal intensity that is somewhat similar to the liver parenchyma. But if you look at it very critically, we can see that it's probably if anything a little bit T1 hypo intense with respect to normal liver parenchyma normal liver parenchyma over here. What does it do when we give intravenous contrast? So we move on to our post contrast imaging sequences. We have the arterial portal venous and equilibrium phase images done over here. And I'll just settle in on a representative portion of this lesion right over here. In the arterial phase image, we note that the lesion itself has pretty homogeneous arterial hyper enhancement on the portal venous phase image. The lesion is somewhat ISO intense to slightly hyper intense with respect to liver parenchyma. So if we look at it, you can argue that some portions look very similar to the liver parenchyma or ISO intense. And some portions remain slightly more brighter than liver parenchyma. And finally on the equilibrium phase images, I would argue that it looks very, very similar to the liver parenchyma, almost completely ISO intense. Now there are certain clefts within this lesion right over there that do not enhance on the arterial phase. And these remember were T2 hyper intense. So they don't enhance on the arterial phase, but as you go from the arterial to the portal venous to the equilibrium phase images, we can see that that same area now enhances. And so we have a lesion that for all practical purposes looks very similar to the liver parenchyma on many of the sequences, except for the arterial phase where it's definitively arterial hyper enhancing. And it has a little cleft of T2 signal that fills in on our equilibrium phase images. So if this is all we had, we would suggest that this most likely reflects focal nodular hyperplasia. Now when we evaluate patient focal nodular hyperplasia, or if that's the clinical question, we often do one final phase after giving an agent which has partial hepatobiliary excretion. We brought this patient back and did that final phase. I'll show you what the lesion looks like on those images. And so here are the final set of post-contrast images performed at 20 minutes after giving intravenous contrast agent called eovist that has partial hepatobiliary excretion. So this is with eovist, and we do these as I said at 20 minutes post-contrast. See the lesion here, and it is relatively hyper intense. Some portions may be iso intense but predominantly hyper intense with respect to the liver parenchyma. And so the combination of these findings on the T2 weighted images to post-contrast imaging, the eovist findings makes the lesion characteristic of focal nodular hyperplasia. Now this is the second most common benign liver tumor after hemangioma. It occurs much more commonly in females than males. And it occurs in females typically of child-bearing age. It's often incidental, seen in up to 90% of cases is just an incidental finding. And the thought previously with FNH is that they were not responsive to estrogen at all. But the current thinking is that there may be some response to estrogen such that if patients are going to become pregnant or are pregnant or an oral contraceptive pills there is the risk of a small amount of growth associated with these lesions. However, overall there are no real complications associated with these despite that potential for growth with high estrogen states. On pathology this manifests as a mass with a central scar with radiating septations coming from it. It often looks like a central scar radiating septations. And that central scar is that portion that was T2 hyper intense and that enhanced late on the equilibrium phase. And so oftentimes when I look at a lesion and it sort of looks like an orange to me, you cut open an orange and cross-section, if it looks like that I'm going to think that this could reflect focal nodular hyperplasia.