Peripheral arterial calcification can be observed on radiographs and may be classified as either medial (linear calcifications in a train-track pattern) or atherosclerotic (distinct, nodular calcifications). A number of other techniques may also be used to detect peripheral arterial calcification including computed tomographic (CT) and magnetic resonance (MR) imaging, duplex ultrasonography, measurement of pulse wave velocity, echocardiography, planar radiographs, and indirectly, the ankle-brachial index.