label: Juxtaphrenic peak
label_lc: juxtaphrenic peak
description: "A juxtaphrenic peak is a small triangular opacity based at the apex of the dome of a hemidiaphragm, associated with upper lobe volume loss of any cause (eg, postirradiation fibrosis or upper lobectomy). It is most readily appreciated on a frontal chest radiograph. The peak is caused by upward retraction of the inferior accessory fissure or an intrapulmonary septum associated with the pulmonary ligament."