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Updated: Jul 1, 2026

Diaphragmatic Ultrasound in Adults: Image Acquisition and Interpretation
Published on: January 31, 2025
The diaphragmatic crura and retrocrural space: normal imaging appearance, variants, and pathologic conditions
Carlos S Restrepo1, Andres Eraso, Daniel Ocazionez
1Department of Radiology, University of Texas Health Science Center, 7703 Floyd Curl Dr, Mail Code 7800, San Antonio, TX 78229-3900, USA. crestr@gmail.com
Abstract:
The retrocrural space (RCS) is a small triangular region within the most inferior posterior mediastinum bordered by the two diaphragmatic crura. Multiplanar imaging modalities such as computed tomography and magnetic resonance imaging allow evaluation of the RCS as part of routine examinations of the chest, abdomen, and spine. Normal structures within the retrocrural region include the aorta, nerves, the azygos and hemiazygos veins, the cisterna chyli with the thoracic duct, fat, and lymph nodes. There is a wide range of normal variants of the diaphragmatic crura and of structures within the RCS. Diverse pathologic processes can occur within this region, including benign tumors (lipoma, neurofibroma, lymphangioma), malignant tumors (sarcoma, neuroblastoma, metastases), vascular abnormalities (aortic aneurysm, hematoma, azygos and hemiazygos continuation of the inferior vena cava), and abscesses. An understanding of the anatomy, normal variants, and pathologic conditions of the diaphragmatic crura and retrocrural structures facilitates diagnosis of disease processes within this often overlooked anatomic compartment.
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