PECAM1 and neoplasm: In a preliminary study on nine patients, Yin et al showed that imaging features extracted from 18-FDG (fludeoxyglucose) PET coupled to MRI with contrast enhancement correlated closely with tumour microvascular density as evaluated by CD31-immunostaining after nephrectomy in clear cell renal carcinoma.28 Combining functional and structural features from PET-MRI showed closer correlations than using PET or MRI alone.