The present invention relates to methods and devices for predicting restenosis, and for treating atherosclerosis to prevent or reduce the incidence of restenosis. Methods of predicting restenosis in a stenosed peripheral artery may include quantitative histology of the vessel. For example, a method of treating a stenosed artery (and particularly a peripheral artery) may include the steps of determining a level of hypercellularity and one or more of the lipid-richness and extent of inflammatory cell inclusion in the tissue. An index of restenosis based on the hypercellularity and lipid richness and/or extent of inflammatory cell inclusion in the tissue may be determined. Systems for treating or preventing restenosis may include one or more imaging modalities for imaging tissue regions and determining the level of hypercellularity and one or more of the degree of lipid-richness and the extent of inflammatory cell inclusion in the tissue region.