Breast cancer-related lymphedema: differentiating fat from fluid using magnetic resonance imaging segmentation

Background: Lymphedema is an iatrogenic complication after breast cancer treatment in which lymph fluid in the affected limb progresses to fat deposition and fibrosis that are amenable to liposuction treatment. Magnetic resonance imaging (MRI) for lymphedema can differentiate fat tissue from fluid, but estimating relative volumes remains problematic.

Methods and results: Patients underwent routine bilateral arm MRI both before and after liposuction for advanced lymphedema. The threshold-based level set (TLS) segmentation method was applied to segment the geometric image data and to measure volumes of soft tissue (fat, muscle, and lymph fluid) and bone. Bioimpedance testing (L-Dex®) to detect extracellular fluid was also used. Volumes derived by using TLS or girth measurement were evaluated and showed consistent agreement, whereas L-Dex showed no significant reduction between pre- and postoperative measures. The percentage median volume difference between the affected and unaffected sides was 132.4% for girth measures compared with 137.2% for TLS (p = 0.175) preoperatively, and 99.8% and 98.5%, respectively (p = 0.600), postoperatively. MRI segmentation detected reductions in fat (median 52.6%, p = 0.0163) and lymph fluid (median 66%, p = 0.094), but the volumes of muscle and bone were relatively constant.

Conclusions: MRI imaging with TLS technology may be a useful tool to quantitatively measure fat tissue and fluid for patients with advanced lymphedema and may assist in the selection of eligible liposuction candidates at initial assessment and follow-up of patients who proceed with surgery.