THE  CONTRIBUTIoN OF THE CT-SCAN

IN THE MANAGEMENT OF BALLISTIC WOUNDS

I MARZOUK MOUSSA, D AYADI, M MOUSSA*, N DALI, H BEN ROMDHANE **, L BEN FARHAT, A MANAMANI, L HENDAOUIMEDICAL IMAGING AND INTERVENTIONNAL DEPARTMENT, MONGI SLIM HOSPITAL, LA MARSA

*VISCERAL SURGERY DEPARTMENT, HABIB BOUGATFA HOSPITAL, BIZERTE ** MEDICAL IMAGING DEPARTMENT, HABIB BOUGATFA HOSPITAL, BIZERTE TUNISIA

VR4

OBJECTIVE To understand the basic of ballistic

wounds and its implications on CT scan exploration.

To illustrate through several cases occured during the Tunisian revolution the role of CT in the management of Gunshot

Wounds (GSWs).

FIREARMS AND THEIR PROJECTILES

• To understand the mecanisms of gunshot injuries , it is important to understand the nature of firearms and their projectiles

• We distinguish several type of firearms 1. handgun 2. Rifles 3. shotgun 1 3

2Single ProjectileLong Range

Multiple ProjectilesShort Range

Sectional diagram of a handgun bullet

Shotgun cartridges

Four groups of pellets

figures borrowed from Wilson 1998 plenary session imaging symposium : gunshot injuries :waht does a radiologist need to know?

PARTICULARITY OF GSWs• The nature and severity of a

bullet wound depend of the characteristics of the bullets and of the tissues through which it travel ,in addition to the mass and velocity of the bullets, its orientation and whether it fragments or deforms affect the nature of the wound

• None physical theory can predict with certainty the behavior of a projectile in the human body .

sample of GSWs of the chest with fragmentation ofthe bullet; secondary projectiles can involve the mediastinal structures even if they weren’t initially implied.

• Bullets injuries are most severe in friable solid organ ( liver, brain) where damage may be caused by temporary cavitation remote from the actuel bullet track.• Dense tissues (bone ) and loose tissues (subcutaneous fat) are more resistant to bullet injury .bones modify the behavior of bullets markedly, altering their course, slowing them down , and increasing their deformity and fragmentation (figure).

Abdominal Ct scan showing the inlet of the bullet (right lumbar fossa) and increased fragmentation in contact with the lumbar vertebra. The outlet was posterior to the left iliac fossa)

COMPUTED TOMOGRAPHY

• CT scan exploration is interesting for both surviving patients and foresnic study contributing to • the mapping of lesions, bullet track and

localization• the choice of the appropriate therapeutic

strategies

• Helical CT is recommended with thin slices and reconstructions in 3 planes, in bone and parenchymal windows . Reconstructions 3D surface are useful for analysis of fractures, inlet, outlet orifices and projectiles.

• Iodine contrast media injection may extend the length of examination so it can be delayed except in case of suspected vascular injury (ischemic lesions, location of the bullet close to a vascular structure) where an AngioCT of the circle of Willis in necessary.

CEREBRAL INJURIES

• GSWs to the head are the most lethal of all GSWs, and most patients do not survive.

• the two main limitations of this technique are represented by metal artifacts of the bullet and motion artifacts of the patient.

Cerebral CT showing important metallic artifacts

• Inlet and outlet orifices: a intracranial inlet is not necessarily present: it may be a non-

penetrating trauma (tangential angle) or when it is embedded in a thick bone.

Outlet orifice may be multiple and larger to the inlet one

• Ballistic Path :edema and hemorrhagic alterations allow to reconstruct the ballistic

path .• Intracranial foreign bodies :Are primary (bullet) or secondary projectiles• Bone fractures :In most cases, there are multiple fracture lines and sometimes

complex. Reconstructions 3D surface are useful.• Bleeding, edema and brain herniation• Intracranial air: pneumoencephalus or air in the cerebral ventricles

Inlet with bone fracture, trajectory of the fragment

Bone fracture, edema, haemorrage with brain herniation

Haemorrage tracing the path of the bullet, meningeal haemorage

THORAX INJURIES • CT permits correct assessment of the main thoracic

injuries, plus adequate and prompt planning of surgical treatment or support intensive care.

• The most frequent CT finding are: lung parenchyma tear and bruise Hemothorax subcutaneous chest wall emphysema Pneumothorax rib injuries Pneumomediastinum diaphragm rupture

THORAX INJURIES

Thorax CT scan with mediastinal and parenchymal windows showing hemothorax, pneumothorax, alveolar haemorrage .

Thoracic GSWs on CT scan, the secondary fragment ended the trajectory in contact of the right pulmonary artery and atrium ().

Thoracic GSWs on CT scan, the bullet ended the trajectory in parenchyma causing hemmothorax and contusion ().

ABDOMINAL INJURIES • approximately 98 % of gunshot wounds that

penetrate the abdomen produce significant intrabdominal injury, all such wounds require abdominal exploration.

• Routine laparotomy has resulted in 65 to 75 % in litterature ; non therapeutic laparotomy rate for such injury: thus selectivity on imaging is warranted.

• Such wounds could lead to the assumption of a corresponding injury to the diaphragm, an average 45-day follow-up is required.

• CT scan is not appropriate in the presence of hypotension and tachycardia, evisceration of the bowel or omentum, rebound tenderness, passage of blood through the rectum or haematemesis, haematuria, radiologic evidence of free air or a ruptured diaphragm

These patients should undergo surgical exploration first.

LIVER INJURIES• triple-contrast helical ct is recommanded• BEST examination to help the selection of patients undergoing a non operative treatement by providing information about the severity of the liver lesion.

• Follow-up CT detects liver-related complications and guide a drainage of collection.

URINARY INJURIES • Kidney injuries are commonly combined

with thoracic and abdominal injuries.• Major role of CT in

– selecting non operative patients– Showing extent of the injury, – identifying false aneurysm and active bleeding.

• Bladder injuries are most frequently seen in pelvic GSWs diagnosed on extravasations of contrast media in delayed images.

BOWEL INJURIES

• CT is less sensitive in detecting small bowel injuries most often discovered during laparotomy

• Best diagnostic clue: Bowel wall thickening > 3 mm, mesenteric infiltration ± extravasation of enteric or vascular contrast medium. Extraluminal oral contrast material: 100% specific.

• Indirect signs ++: free air, Mesenteric infiltration , Hematoma or liquefied blood.

• Because of the potential clinical consequences of missing an injury to the hollow viscus in GSWs, when CT shows localized mesenteric or pericolonic hematomas, even without other evidence to suggest perforation, findings on CT scans should be interpreted a equivocal.

penetrating wound of the right iliac fossa causing multiple perforations of small bowel and coecum. These lesions were suspected on CT in front of hemiperitoneum and thickening of bowel wall () in contact with the bullet.

BOWEL INJURIES

SPINE INJURIES • Direct injury is a consequence of the projectile crossing the spinal cord and/or

canal causing compression, contusion, or laceration of the spinal cord/ nerve roots, with or without laceration of the dura.

• Indirect injury may result from shock waves or secondary fragments damaging the neural elements.

• MDCT is very useful with 3D MIP and surface reconstructions showing anatomical views of the path, the extension of fractures, the bullet and/or secondary fragments location.

• Beside the direct injury and non stable fractures, spinal cord compression may occur after accumulation of blood and fluids.

• The use MRI to evaluate GSWs to the spine is controversial. Bullet migration from the pull of the strong magnet can possibly lead to further neurological or soft tissue damage. However, numerous reports of the use of MRI have not supported this concern * and thus remain unproven in a controlled scientific study until now.

Finitsis Am J Neuroradiol, 1999

CT scan with sagittal reconstruction of cervical spine GSWs showing spine fracture caused by secondary fragments.

CT scan of thoracic spine GSWs showing the transthoracic path and the location of the bullet in the medullary canal.

CT scan of lumbar spine GSWs showing the postero-lateral path and the burst fracture of vertebra.

FORENSIC MEDICINE AND GUNSHOT INJURIES

The use of cross-section radiological techniques in the field of forensic medicine is a relevant progressive step, because it opens, in contrast to the classical X-ray method, the way to 3D documentation.

MDCT is very helpful adjuvant to the state-of-the-art classic forensic examination of ballistic trauma with recently a growing role in virtual autopsy.

Figures borrowed from Andenmatten et al: Gunshot injuries detected by post-mortem multislice computed tomography (MSCT): A feasibility study. Legal Medicine Volume 10, Issue 6, November 2008, Pages 287–292

MDCT, surface rendering of a suicide victim. Typical star shaped contact wound to the forehead

MDCT, semitransluscent 3D bone reconstruction of the right shoulder of a homicide victim. Objects of more than 1000 Hounsfield units, such as the two bullets (arrows) are coloured blue, thus making them easily distinguishable

CONCLUSION

Gunshot injuries are very diversed. A radiologist who is familiar with the basic

principles of gunshot injuries can have a major effect on imaging and management.

CT scan exploration in the field of non fatal wounds allows a best mapping of lesions and

guide the appropriate therapeutic.

Thanks for your interest,Our special thoughts go to the Martyrs and all the Injured Tunisians during the Revolution .

The authors