A study of imaging findings in potential liver donors found that anatomic variations are common and many of these variations can exclude a potential donor, according to findings published in the April issue of the American Journal of Roentgenology.

While imaging of potential donor livers is an important step in the living-donor liver transplantation process, the radiographic features that preclude transplantation have not been extensively catalogued, according to Lewis D. Hahn, MD, of Yale University School of Medicine in New Haven, Conn., and colleagues.

To help fill this gap in the literature, the authors retrospectively reviewed the records of 159 consecutive liver donation candidates who were evaluated for right or left lobe donation from November 2007 to January 2012 using CT angiography and cholangiography.

They found that 61 candidates (38 percent) were excluded based on imaging. Inadequate liver volume was the most common reason for exclusion based on preoperative imaging, with 40 (66 percent) of the excluded patients ruled out for this reason. Hahn and colleagues noted that this finding varies from previous studies in which few donors were excluded based on volume, which suggests that providers have gotten more cautious about preventing postdonation complications.

“Adequate liver volume is essential for both donor and recipient liver function after transplantation. Although only 20–30 percent remnant liver volume is theoretically necessary for adequate hepatic function until the liver regenerates, a minimum cutoff of 30–40 percent is typically used in the selection of donors,” wrote the authors.

The next most common reason for exclusion was the presence of vascular or biliary anatomic variants, which were present in 23 percent of the excluded. Most variants involved the arterial and biliary systems.

A minority of patients were excluded for steatosis (8 percent) and other abnormalities at CT (3 percent).

Hahn and colleagues added that two patients who were not ruled out due to preoperative imaging had anatomic abnormalities detected intraoperatively that precluded transplantation.