The largest internal organ in the human body, the liver consists of numerous lobules connected to an extensive duct system, which leads to the hepatic duct, a duct that transports liver-produced bile to the gall bladder and the first part of the small intestine.
Bile made by the liver helps break down fats and rid the body of waste products, but the liver does much more. It helps change food into energy, clears poisons from the blood, creates some of the proteins in blood plasma, and helps regulate clotting. Though x-rays and ultrasound imaging are used in diagnosing liver problems, in many cases computed tomography (CT) is the radiology study of choice because of the level of detail CT depicts.
CT of the Liver
If a person has jaundice, physicians may order a CT scan of the liver, because it can distinguish between obstructive and non-obstructive jaundice. CT scans of the liver can also be used for guiding biopsies and tissue aspiration from the liver. A CT scan creates detailed cross-sectional images and can help with identification of several types of liver tumors, as well as information on tumors’ size, shape, and location within the liver and associated ducts.
Though CT scans take longer than traditional radiology studies like x-rays, the detail that results makes the extra time worthwhile. For some liver CT scans, patients drink an oral contrast liquid that helps outline the intestines so structures are more readily identifiable. For some scans, patients are injected with intravenous (IV) contrast agent. With suspected liver cancer, patients may have a set of scans without contrast agent as well as during administration of IV contrast agent. Together, these scans can help distinguish benign from malignant liver tumors.
Why CT Is the Preferred Imaging Method with Liver Cancer Metastases
Radiology studies of cancer metastases to the liver typically produce nonspecific results, and biopsies are often required for final diagnosis. CT scans are the radiology study of choice for evaluating liver metastases, often providing excellent imaging at less expense than magnetic resonance imaging (MRI) and positron emission tomography (PET). The liver’s dual blood supply helps enhance the appearance of liver metastases on CT scans compared with what a normal liver CT looks like. For tiny lesions, however, doctors may choose MRI or PET for superior resolution of details, even though these imaging studies are more expensive.
Using CT to Build a Virtual 3D Model of the Liver
CT scans create cross-sectional “slice” views of tissues, and enough of these “slices” can be put together to create a virtual 3D model of the structures seen on the scans. Creating a 3D model of the liver from CT scan slices can be tremendously beneficial because it can help physicians estimate liver volume and get a clearer idea of characteristics of abnormalities. Turning all the CT slices into a 3D model is done slice-by-slice rather than all at once, for accuracy, even though it’s a slow process.
Researchers at University College London have developed an automated process for creating a 3D virtual model from CT scans that could revolutionize the process. They created what they call a self-reparameterizing active contour model that uses information in an entire set of liver CT slices at once rather than considering all of them individually. The researchers compared the 3D model results to 3D virtual liver models made slice-by-slice, and were encouraged by the results. Automated 3D models tended to show about 5% less liver volume compared to manually calculated 3D models, but they think they know why.
In some of the datasets evaluated, the CT scans were performed using contrast agents, which causes vascular structures to show up as bright white. Manual creation of 3D liver models incorporates the volume of vascular structures that are entirely surrounded by liver tissue into volume calculations, whereas the automated process does not. The researchers are refining their technique and hope it will make diagnoses requiring 3D visualization of the liver to be done significantly faster in the future.
Radiology and Diagnosis of Liver Anomalies
The radiologists who own and operate SteleRAD have the experience necessary to know which radiology study is most appropriate for a given patient. Radiologists like Kenneth P. Morrison, MD specialize in CT studies like those used to diagnose liver cancer, and every SteleRAD radiologist has completed a four-year diagnostic imaging residency and is Board certified by the American Board of Radiology. If you would like to know more, we invite you to call us at 954-358-5250 or contact us online at any time.