Osteoporosis (porous bones) is a disease that is characterized by decreased bone strength and increased risk of fracture due to loss of bone strength from decreased bone mass and deterioration of bone micro-architecture. In particular, cortical porosity (CtPo) significantly impacts bone strength and has been associated with the progression of the disease and the occurrence of fracture. Very recently, it has become possible to assess CtPo in the appendicular skeleton in vivo through the use of high-resolution peripheral quantitative computed tomography (HR-pQCT). There are two approaches to assessing CtPo from HR-pQCT imaging data based on a threshold-based or a density-based approach. The performance of both methods was compared against gold-standard synchrotron radiation micro computed tomography (SRu CT) measurements. The threshold-based approach was found to be more highly correlated with true values of CtPo than a density-based approach. Improved CtPo measures may lead to better imaging diagnostics to detect and monitor osteoporosis.