 With that discussion, we'll move on to carcinomatosis metastatic disease. Some of the most common primary tumors to do this, do it through local spread into the peritoneum, and that would be ovarian cancer, GI malignancies, most commonly gastric, esophageal, colorectal, and appendix, the gallbladder, and the pancreas. There are of course other diseases that can occur in, such as HCC, endometrial, all of these are less common. Then you can have hematogenous spread of carcinomatosis as opposed to these others which are generally localized spread that spill into the peritoneal cavity and spread. You can have hematogenous spread from breast cancer, lung, or melanoma most commonly, traditional cell carcinoma, and then there are entities called peritoneal sarcomatosis or lymphomatosis that are a bit less common but possible as well. What you need to do here again is when you see any findings of carcinomatosis, search for the primary tumor and that's going to help tell you if this is metastatic disease or primary tumor. Ultimately, you still will need pathologic confirmation, but a relevant history can be helpful. Did they have their ovaries out because they had an ovarian cancer history? You can look for the primary tumor itself, look at the gallbladder, look at the colon, look at the pancreas to see if that's the primary that it's originating from. On this contrast enhanced CT, this patient had a history of colorectal cancer that had been removed previously. On the axial images right here, we can see denoted by the arrows, these slight hypodensities that are really quite subtle. In this area, it's a common place for diaphragmatic slips, which is when the diaphragm gets a little bit lax and can almost have some folds in, as you see right here, that can almost look mass like in the liver. As you see these nodules, remember to look on maybe a sagittal or coronal image to see whether we believe these are real or whether we think these are benign. As we scroll down a little bit further, because now I'm already starting to think that this is a peritoneal process right here, I'm going to look for disease elsewhere. You can look in the mesentery, but I often like to look in the dependent locations because that's where they tend to occur. So I might look in the paracallic gutter, and you can see a soft tissue nodule right here. You can look down deeper into the pelvis, because oftentimes they will collect down here in the most dependent portion of the body. Right here we have this soft tissue nodule right here. It's separate from the prostate, which is down here in the seminal vesicles, a little bit higher. This is superior to that. In these cases, you can always look at the prior as well to see if these nodules were there. They've always been there. They are just nodules of uncertain significance, or are they growing in this case? These nodules were new or were enlarging. Again, we mentioned using different images, different sequences, to determine whether this is in the liver or outside of the liver. It will also help you decide whether you can biopsy these. If it's in the liver, it's much easier to biopsy the liberation as a radiologist percutaneously than it is to biopsy the subcapsular lesion. It can help determine management as well if they need tissue. In this case, you can see by the arrow is hypodensity right here. It almost looks like it's pushing the liver this way. It's centered right in between the diaphragm and here. This is going to be a peritoneal process. These are metastatic disease, not necessarily within the liver, but more likely along the peritoneum along the lining of the liver itself. Another one right here. Again, you can make out a little bit here that's pushing on the liver as opposed to being within the liver itself. You see this tiny little divot right here, little divot right here that tells you it is an extra peritoneum process. It is not within the liver itself. This is a companion case, also patient with the history of colorectal carcinoma. We can already see at the lung bases that there are pulmonary nodules that are hypoenhancing heterogeneously, most likely metastatic disease. It's a good example of one right there. As we go down here, you see a lymph node right here, just superior to the diagram. But as we're coming down, you can also see this person had a hepatectomy. Here's the suture line right here. They probably had metastatic disease at their colon, which was treated surgically. If you're scrolling through axially right here, that might be all that you notice. You might see this over here, this soft tissue density here, but we have clips here. This looks like a little bit of remnant spleen after a splenectomy, whether it was purposeful or post-traumatic splenectomy, that being more likely. Again, that might be all that you see. We have the lung nodules. However, if you go to the coronal images and scroll through here, here's that lymph node along the diaphragm in the chest cavity itself. As we go back through this liver here, you'll notice all of this right here, which was missed on the axial initially, if you're not looking closely. You can see there's diaphragm right here, the peritoneal lining is going to be here. These are large soft tissue lesions, even pushing upon the kidney right here. These are peritoneal metastases. In this particular patient, they didn't really have disease much elsewhere in the abdomen. If you go back to the axial images, those large soft tissue nodules, which are so apparent on the coronal image are right here. Once you know to look for them, quite obvious that they're there, but very easy when you're scrolling through here looking at the liver to miss this and just think this is diaphragm as you're going through. Again, here's some diaphragmatic slips right here for very similar density to the soft tissue process of metastatic disease that is right here. When you're looking for peritoneal disease, coronal images really are your friend. You're going to find more of these than you do just looking on axial images. If you're not sure on axial images, I also find coronals or sagens are really helpful to confirm what you're seeing if it is a soft tissue process or if it is a normal process like a diaphragm slip.