Optimal planning aids avoidance of vessels

The complexity of the liver can make the removal of pathology difficult. The organ's dual blood supply gives it many vascular structures to avoid. So when surgery is planned, practitioners must have a good idea what they are tackling beforehand.

One of the first questions to be answered by preoperative imaging is what the scale of the problem is. The number and size of lesions present in the liver, and their precise location, are vital pieces of information. No pathology should remain hidden at this stage, no matter how small or how difficult to see.

Good lesion characterization is also critical at this stage. About 50% of patients who are candidates for liver tumor resection will have benign liver lesions as well as signs of malignancy, according to Dr. Ahmed Ba-Ssalam-ah, an associate professor of radiology at the Medical University of Vienna in Austria. Radiologists need to show the surgeon which lesions require excising and which should be left.

"You may have a patient who has a simple hemangioma or focal nodular hyperplasia in segment II of the liver and a couple of metastases in segment V. The surgeon needs to take out only the lesions in segment V. The benign lesion can be left alone," he said.

Preoperative imaging should also confirm whether surgery is required at all. Young women are often referred to liver surgeons when ultrasound has identified a lesion and clinical follow-up suggests the mass is growing, said Prof. Dr. Jan Langrehr, chief of general and visceral surgery at the Evange-lisches Waldkrankenhaus Spandau in Berlin. If the lesion is cancerous, it will need removing. But if it turns out to be a focal nodular hyperplasia, a benign growth and the second most common type of liver tumor, then surgery is not typically performed. MRI performed with a hepatocyte-specific contrast agent such as Eovist should confirm this distinction.

"These lesions don't have to be operated on, period. That is when functional information becomes important," Langrehr said.

Dr. Claude Sirlin, an assistant professor of radiology at the University of California, San Diego, has been running a prehepatectomy MRI program for the past six months. The number of referrals from surgeons is steadily increasing.