RADIOLOGY CORNER

Military Medicine, Aug 2008 by Backus, Christopher, Folio, Les

Answer to last month's radiology case (#26) and image: Lung laceration with loculated blood, active bleeding, contusion and hemothorax

(Case #27 appears at the end of this article)

The following case demonstrates the importance of emergent imaging in victims of gunshot wound to the chest. The AP chest in our case highlights findings that correlate well with support of follow up CT Angiogram of the chest. This case also exemplifies description of complex planes now available with modern CT imaging capabilities described here as para-axial, para-coronal and parasagittal reconstructions.

History

Our patient is a 31 year old active duty male deployed troop suffering a gunshot wound (GSW) to the left chest. This war casualty was med-evaced from field conditions to a combat hospital in Iraq. The patient was hemodynamically stable in the ER, further stabilized, with the following AP chest image obtained to evaluate involvement and estimate missile trajectory. This, combined with the clinical observation of single entrance wound to upper left chest anteriorly, demonstrated the bullet overlying the mediastinum, likely posterior.

Summary of Findings:

Figure 1 demonstrates the bullet overlying the mediastinum, likely posterior based on anterior entrance clinically. A wedge-shaped opacity consistent with consolidation represents contusion and laceration with loculated blood (seen on CT) from the missile path through the involved left lung. Blunting of the left costophrenic angle is noted, as well as overall haziness of left lung field peripherally, representing hemothorax (confirmed by CT). Surgical staples are noted in the enlarged soft tissues of the left lateral chest wall.

Figure 2 confirms the lung contusion on the para-axial reformation aligned with the trajectory of the missile path. Parenchymal tearing is evident by the obliquely oriented, sausage-shaped opacity representing bleeding into a resultant laceration (see companion case in full-text version of this article for example of cavity that is not filled with blood). The surrounding cloud-like high attenuation region represents contusion from ballistic effects (such as tumbling / shock wave) that follow a projectile, similar to the wake of a boat as it travels through water.

Diagnosis

Lung laceration with loculated blood in resultant cavity, active bleeding, contusion and hemothorax

Patient discussion:

The CXR demonstrated classic findings of lung contusion, hemothorax and projectile. In hemodynamically stable patients such as ours, an immediate CT Angiography of the chest is obtained to evaluate potential major vascular or cardiac involvement, active bleeding, missile path, hemothorax or pneumothorax, and lung involvement. The follow-up CT validated the extensive hemothorax and bloodfilled cavity in left lung. Bullet trajectory is influenced by mass, velocity, and shape of the projectile, whether the projectile enters cleanly, without yaw, or is "tumbling" upon entry.1 Some projectiles will complete their flight with the base of bullet forward.2 CT is a tool commonly used to determine the trajectory or wound path a bullet took through tissues.3

Volumetric imaging and resultant multiplanar reformations in the complex planes described here helped guide surgeons more definitively on this case, while maximizing resources for other casualties being diagnosed and treated simultaneously. The para-axial and para-sagittal planes are graphically represented in Figure 4. Please see the on-line full text version for more discussion on the complex planes of modern MDCT imaging.

CASE # 27

The answer to this case will appear in the next issue of Military Medicine

History: This 45 year old male was in a room when a grenade exploded. The patient initially thought he sustained only minor injuries and did not report to the hospital. He presented to the emergency room five days following his injury with severe unilateral epistaxis and a small entrance wound on left cheek (Figure 1). On physical examination the patient had a scar likely representing a normally healing entrance wound on his left cheek (left). A CTA of the head para-axial plane is demonstrated in Figure 2.

What is (are) the finding(s)? What is the differential diagnosis? Best diagnosis?

References:

1. Volgas DA, Stannard JP, Alonso JE. Ballistics: a primer for the surgeon. Injury 2005; 36 (3):373-9.

2. Folio LR, McHugh, Hoffman M. "The Even Number Guide: A Method for Accounting for Ballistic Injuries." Radiol Technol. 2007 Jan/Feb; 78(3):197-203.

3. Bruckner BA, Norman M, Scott BG. CT Tractogram: technique for demonstrating tangential bullet trajectories. J Trauma 2006; 60 (6): 1362-3.

Acknowledgements.

The authors would like to thank our artist, Sofia del Castillo, for her excellent descriptive illustrations.

Contributors: LT Christopher Backus, USAF*, COL Les Folio, MC, USAF, SFS*

Series Editor: COL Les Folio, MC, USAF, SFS

* Uniformed Services University of the Health Sciences, Bethesda, MD.

The full text version is available in a downloadable PDF file on the AMSUS page of the USUHS website at: http://rad,usuhs.mil/amsus.html