Retrocrural Space Obliteration as CT Diagnostic Sign of Massive Chylothorax in Thoracic Injuries
Marco Matteoli *
Diagnostic and Interventional Radiology Unit, S. Andrea Hospital, Sapienza University, Rome, Italy.
Marta Vincigurra
Diagnostic and Interventional Radiology Unit, S. Andrea Hospital, Sapienza University, Rome, Italy.
Lara Cristiano
Diagnostic and Interventional Radiology Unit, S. Andrea Hospital, Sapienza University, Rome, Italy.
Chiara De Dominicis
Diagnostic and Interventional Radiology Unit, S. Andrea Hospital, Sapienza University, Rome, Italy.
Ilaria Mastroiacovo
Diagnostic and Interventional Radiology Unit, S. Andrea Hospital, Sapienza University, Rome, Italy.
Gioia Papale
Diagnostic and Interventional Radiology Unit, S. Andrea Hospital, Sapienza University, Rome, Italy.
Luca Tabbì
Department of Clinical and Molecular Medicine, Respiratory Science Unit, S. Andrea Hospital, Sapienza University, Rome, Italy.
Mohsen Ibrahim
Department of Thoracic Surgery, S. Andrea Hospital, Sapienza University, Rome, Italy.
Giulio Maurizi
Department of Thoracic Surgery, S. Andrea Hospital, Sapienza University, Rome, Italy.
Michele Rossi
Diagnostic and Interventional Radiology Unit, S. Andrea Hospital, Sapienza University, Rome, Italy.
Vincenzo David
Diagnostic and Interventional Radiology Unit, S. Andrea Hospital, Sapienza University, Rome, Italy.
*Author to whom correspondence should be addressed.
Abstract
Purpose: Blunt traumatic chylothorax could be distinguished in CT (Computer Tomography) scan as low attenuated fluid, due to chylomicrons inside, however blood intermixture in chylous effusion could make densitomery higher and hide chylothorax, due to the possible presence of an underlying hemothorax. The objective of the study is to demonstrate the specificity of retrocrural space obliteration, as additional CT sign to quickly identify and treat chylothorax.
Materials and Methods: This retrospective study was undertaken since May 2012 until May 2013 and included patients scheduled for MDCT (Multi Detector CT) scan before a thoracentesis procedure diagnostic for hemothorax and chylothorax. Were used as a controls, MDCT scans performed for thoracic or thoracic-abdominal trauma, or after a thoracic surgery procedure.
Results: Comparison of CT findings revealed significant difference in densitometry between the two groups of effusions (P=0,003), a difference in inability of visualization of retrocrural space (P=0,0002) and cisterna chily (P=0,0009). Inability to observe thoracic duct was not different between the two groups (P=0,8805).
Conclusion: Negative density (-16,7+8HU) in effusions, due to the presence of fat inside, was usually observed in almost 6 anterior regions or at least 2 upper anterior regions and it’s the best way to distinguish a chylo-thorax to hemo-thorax. Most accurate CT scan differentiation between post traumatic massive bloody and chylous leakage can be done after assessment of a lower densitometry of effusion and inability in observing chylous structures and fat in retrocrural space due to chylous leakage inside.
Keywords: Chylothorax, chyloperitoneum, CT scan, thoracic duct, cisternaa Chyli, retro-crural space.