Key words abdominal wall - thorax - thorax wall - head injury
Introduction
Currently, whole-body computed tomography (WBCT) is the fastest and the most frequently used method for cross-sectional imaging of polytraumatized injured patients. However, patient triage presents a challenge to medical personnel applying WBCT in their clinical practice. The detection of potential internal injury vs. radiation exposure of the often young patients must be taken into consideration in the clinical judgement [1 ].
In Germany, WBCT is currently recommended for polytraumatized patients according to the Association of the Scientific Medical Societies [2 ]. However, there is a large group of polytrauma patients that fulfills some criteria of suspected major trauma due to history of trauma but presents no severe clinical symptoms to qualify them for WBCT.
There is obviously a crucial need to tailor diagnostic imaging to the specific needs of patients involved in traumatic accidents. Our study investigated the skin body surface and subsurface area of patients undergoing WBCT. The body surface area (BSA) of human skin varies depending on body weight from 1.97 ± 0.143 to 3.07 ± 0.225 m2
[3 ]. This large area of accessible skin provides a unique opportunity for the easy detection of superficial post-traumatic lesions, which could be linked to more severe internal injuries. It is recognized that only serious skin injuries will be detected on a CT scan.
The aim of this study is to investigate whether the detection of a bruise, hematoma, foreign body or trapped air on WBCT was correlated with internal injuries and could become a valid diagnostic sign thus facilitating rapid detection of internal injuries. As a consequence of selective detection, cross imaging approaches could be possible, which would rapidly reduce radiation exposure of young adults after trauma. Our hypothesis was that superficial injuries at specific locations correlate with internal injuries on the WBCT emergency scan.
Materials and Methods
After Institutional Review Board approval, a retrospective analysis of 250 consecutive cases of post-traumatic patients was performed. The inclusion criteria involved all patients (> 18 years old) admitted to our university hospital during a consecutive 6-month period with whole-body emergency scan (WBCT scan was performed including the head, neck, thoracic and abdominal cavities and at least one phase with intravenous contrast agent was injected). An emergency team consisting of two surgeons with experience in emergency medicine, an experienced anesthesiologist and an experienced radiologist evaluated the inclusion criteria to perform posttraumatic cross-sectional imaging with WBCT. A decision about performing cross-sectional imaging was made after analyzing the vital signs, performing clinical examination, taking history of trauma and performing Focused Assessment with Sonography for Trauma (FAST) ultrasonographic examination. The FAST examination was performed to rule out and detect free fluid collections (interpreted as potentially active bleeding or acute hematoma) in the left and right upper abdominal quadrants, as well as the pericardial cavity or in the pouch of Douglas.
In summary, the criteria leading to a WBCT scan were as follows:
Abnormalities in vital signs.
Relevant history of trauma, such as the affection of more than two injured body regions on physical examination, high-speed accidents or falls of more than one meter.
Relevant findings in the FAST examination, such as free fluid collection or signs of any damage to internal organs.
Analysis of the cases revealed that the majority of traumas (62 %, n = 156) were caused by traffic incidents, such as automobile collisions (n = 81), two-wheeled vehicle accidents (including motorbikes and bicycles) (n = 68), and accidents involving pedestrians (n = 7). Falls from more than one meter were reported in 54 cases (22 %). The cause of trauma in 22 patients (9 %) was not established. Other traumatic incidents occurred in 18 patients (7 %) and included uncommon accidents that could not be classified into one of the groups listed above, such as domestic violence or being struck by lightning.
Superficial injuries detectable with WBCT were the following ([Table 1 ]):
Table 1
Various skin lesions and their appearance on CT scans.Tab. 1 Verschiedene Hautläsionen und deren Erscheinungsbild in CT-Scans.
type of skin lesion
imaging finding on CT scan
description
A. contusion
Subsurface tissue injured skin surface remained intact. (Clinically, within a few hours after trauma there will be a sign of bruise that develops gradually.)
B. deep bruise
Contusion of the subcutaneous tissue and the skin surface with disruption.
C. hematoma
Localized collection of blood in muscular tissue is visible without any contrast agent, due to increased volume of the organ and ongoing growth at different scan phases, when active bleeding is present.
D. foreign body
An unwanted intruded object located under the skin surface.
As an example, a small stone is visible after a motocross collision at the level of left frontal bone.
E. subcutaneous emphysema
A collection of trapped gas in a layer under a muscle.
Contusion/superficial bruise – a subcutaneous tissue injury with an intact skin surface. Clinically, within a few hours after trauma, a gradually developing bruise is observed. A bruise presents as blurred opacity of approximately 25–55 Hounsfield Units (HU), causing light hyperdensity in the subcutaneous tissue on CT ([Table 1A ]).
Deep bruise – a contusion of subcutaneous tissue with a simultaneous disruption and injury of the skin surface. On CT scan, a blurred opacity of approximately 25–55 HU and visible disruption of skin surface can be detected ([Table 1B ]).
Hematoma – a localized collection of blood in the muscular tissue, presented as hyperdensity or inhomogeneity on CT without contrast agent. Hematoma shows density of approximately 25–60 HU without contrast agent and may cause a mass effect, especially through arterial bleeding ([Table 1C ]).
Foreign body – a foreign object under the skin surface such as metallic structures, as well as stones or grains of sand are easily detected on CT as sharp well-defined structures penetrating the body surface. Many non-contrast-enhanced foreign bodies such as thick wood or glass splinters are visible due to their mass size and abnormal geometric structure in comparison to the anatomical structures. The density varies between –50 and 3500 HU ([Table 1D ]).
Subcutaneous emphysema – a collection of trapped gas in the layer beneath the skin or muscle. On CT scans, there is a subcutaneous opacity approximately of minus 200–1000 HU ([Table 1E ]).
Our targeted areas were as follows: the head including facial skeleton and neurocranium, the neck, the thorax including shoulders, the abdomen, the pelvis and proximal thigh. The extremities in full-length were not included in this study. In general, the extremities are sufficiently assessed during clinical examination and cross-sectional imaging should be only used at most on an individualized case-by-case basis (e. g. no distal pulse). It should be noted that patients with subgaleal hematoma were also included in this study. A subgaleal hematoma arises in the space between the periosteum and galea aponeurosis, and it is not considered to be of a subcutaneous nature. The variety of shapes, from circular to irregular, precluded an exact estimation of the extent, severity and volume of all lesions.
Second reading
The second retrospective reading of WBCT with special appreciation of skin lesions was recorded by an experienced radiologist and was without time pressure. However, it should be noted that the second reader was not blinded to the results of the first reading. The comparison between the internal injuries in the first and second readings was estimated [Table 6 ].
Patients
The patients in our study consisted of 163 men and 87 women (50 ± 21.7 years). Based on their history of trauma, there was no statistically significant difference in the type of trauma with regard to gender.
WBCT
CT images were acquired using a 128-row CT scanner. Patients received a tube voltage (k)V ranging between 80–140 kV. Sharp bony and soft-tissue kernels were used for image reconstruction and immediate coronal and sagittal images were generated. The first WBCT reading was always performed by a consultant radiologist and a radiology resident, and a consensus was reached as to whether internal damage was present or not. The second round of CT reading was performed by another experienced radiologist with special attention given to skin or subcutaneous lesions.
Statistics
Statistical analyses tested whether the observed skin injuries were related to a certain body area or a specific type of accident. Statistical analyses were carried out using R software (version 3.3.2). Chi-squared tests were used to test for correlations between the measured variables
Detailed correlations between the following parameters were calculated:
If a skin/subcutaneous injury as well as subgaleal hematoma was associated with intracranial bleeding/fracture or contusion of the head.
If a skin/subcutaneous injury, especially including subcutaneous emphysema, was associated with an internal contusion of the thoracic cavity.
If a skin/subcutaneous injury was especially associated with a fracture or hematoma of the neck.
If a skin/subcutaneous injury including bruise and hematoma was associated with injury of the abdominal cavity/or pelvis.
For each correlation, a separate significance level was obtained, in addition to positive predictive (PPV) and negative predictive values (NPV) corrected for multiple testing.
The trauma history was correlated with potential skin and subcutaneous damage of the head, neck, viscerocranium, thoracic cavity and abdominal cavity including the pelvis, and was reported separately. For this analysis, Fisher’s exact tests were used.
Comparison between the internal injuries from the first and second readings was estimated using McNemar’s test.
Results
Neurocranium
A superficial injury of the neurocranium was observed in 52 patients. 20 of them had a fracture or intracranial bleeding. An internal injury of the neurocranium was significantly more common in patients with skin injury (p < 0.05, Chi-squared test) yielding a positive predictive value of 38 % and a negative predictive value of 93 % ([Table 2 ], [Fig. 1 ]). Superficial injuries of the neurocranium were typically associated with a fall, uncommon accidents, which were three times more common than traffic accidents (p < 0.05) or traumas due to unknown causes.
Table 2
Correlation between superficial injuries of the neurocranium (including subgaleal hematoma) and an internal injury.Tab. 2 Korrelation zwischen einer oberflächlichen Schädigung des Neurokraniums (einschließlich eines subgalealen Hämatoms) und einer inneren Schädigung.
WBCT
superficial injury
(n = 52)
no superficial injury
(n = 198)
p-value
(Chi-squared test)
n
%
n
%
internal injury of neurocranium
20
38.5
13
6.6
< 0.001
no internal injury of neurocranium
32
61.5
185
93.4
Fig. 1 An example of injury of the neurocranium. A 22-year-old man after a traffic accident. There is contre-coup injury by frontal intracranial intraparenchymal and subarachnoidal bleeding (arrow) as well as a subgaleal hematoma (coup injury) on the contralateral occipital side (arrow).Abb. 1 Ein Beispiel für eine Verletzung des Neurokraniums. Ein 22-jähriger Mann nach einem Verkehrsunfall. Es liegt eine Contre-coup-Verletzung mit frontalen intrakraniellen intraparenchymalen und subarachnoidalen Blutungen (Pfeil) sowie ein subgaleales Hämatom auf der kontralateralen Occipitalseite (Pfeil) vor.
Viscerocranium
A superficial injury of the viscerocranium was observed in 26 patients. 12 of these had a deeper injury of the facial skeleton. The correlation was statistically significant (p < 0.05) ([Table 3 ], [Fig. 2 ]). Superficial injuries of the facial skeleton were usually related to the history of an unknown traumatic cause.
Table 3
Correlation between the superficial injuries of the viscerocranium and an internal injury.Tab. 3 Korrelation zwischen der oberflächlichen Verletzung von Viszerokranium und einer inneren Verletzung.
WBCT
superficial injury
(n = 26)
no superficial injury
(n = 224)
p-value
(Chi-squared test)
n
%
n
%
internal injury of viscerocranium
12
46.2
1
0.5
< 0.001
no internal injury of viscerocranium
14
53.9
223
99.6
Fig. 2 An example of injury of the viscerocranium. 40-year-old woman with some subcutaneous emphysema (arrow) due to communicating trauma (arrow) of a nasal cavity and subcutis after bicycle accident.Abb. 2 Ein Beispiel für eine Verletzung des Viszerokraniums. 40-jährige Frau nach einem Fahrradunfall mit subkutanem Emphysem (Pfeil) aufgrund einer kommunizierenden Verletzung (Pfeil) der Nasenhöhle und der Subkutis.
Neck
There were three patients with a superficial injury of the cervical area and no statistically significant (p > 0.05) results were observed.
Thoracic cavity
A superficial injury to the thoracic cavity was observed in 19 patients. 17 of them had a fractured rib or lung injury. There was a statistically significant correlation (p < 0.001), ([Table 4 ], [Fig. 3 ]). The PPV was nearly 89.5 %, whereas the NPP was 74 %. There was no significant correlation between the type of superficial injury and specific type of accident.
Table 4
Correlation between superficial injuries of the thoracic cavity and an internal injury.Tab. 4 Korrelation zwischen der oberflächlichen Verletzung der Brusthöhle und einer inneren Verletzung.
WBCT
superficial injury
(n = 19)
no superficial injury
(n = 231)
p-value
(Chi-squared test)
n
%
n
%
internal injury of thorax
17
89.5
60
25.8
< 0.001
no internal injury of thorax
2
11.8
171
74.0
Fig. 3 a A 53-year-old man presenting with a pneumothorax on the left side and mild lung contusion due to a rib fracture after a car accident. Air trapping in soft tissues (arrows) is also present. b A 52-year-old man with a sternum fracture (arrows) and mediastinal hematoma after a car collision. It is necessary to rule out cardiac trauma and pericardial effusion as well as pneumothorax, aortic dissection, and lung contusion.Abb. 3 a Ein Beispiel für Verletzungen in der Brusthöhle. Ein 53-jähriger Mann nach einem Autounfall, der sich mit einem Pneumothorax auf der linken Seite und einer leichten Lungenkontusion sowie einer Rippenfraktur vorgestellt hat. Ein Hautemphysem ist hier ebenfalls sichtbar und in den Weichteilen eingeschlossen (Pfeile). b Ein Beispiel für Verletzungen in der Brusthöhle. Ein 52-jähriger Mann nach einem Autounfall mit einer Brustbeinfraktur (Pfeile) und einem mediastinalen Hämatom. Ein Herztrauma und ein Perikarderguss sowie ein Pneumothorax, eine Aortendissektion und eine Lungenkontusion müssen ausgeschlossen werden.
Abdominal cavity
A superficial injury of the abdominal wall was observed in 30 patients. 11 of them had a fracture or internal injury. There was no statistically significant correlation (p > 0.05) between internal injuries and superficial lesions. The PPV was 36.7 % ([Table 5 ], [Fig. 4 ]).
Table 5
Correlation between superficial injury of the abdominal cavity and an internal injury.Tab. 5 Korrelation zwischen einer oberflächlichen Verletzung der Bauchhöhle und einer inneren Verletzung.
WBCT
superficial injury
(n = 30)
no superficial injury
(n = 220)
p-value
(Chi-squared test)
n
%
n
%
internal injury of abdomen
11
36.7
48
21.8
= 0.117
no internal injury of abdomen
19
63.3
172
78.2
Fig. 4 A 50-year-old man after a fall from a height as an example of an injury within the abdominal cavity with parenchymal disruption (arrow) involving approximately 40 % of the right lobe resulting in a grade IV AAST liver injury.Abb. 4 Ein 50-jähriger Mann nach einem Sturz aus großer Höhe als Beispiel für eine Verletzung in der Bauchhöhle mit Parenchymzerstörung (Pfeil), von der ungefähr 40 % des rechten Leberlappens betroffen sind, was zu einer AAST-Leberschädigung Grad IV entspricht.
Second reading ([Table 6 ])
Table 6
Comparison between the first and second reading due to internal damage. The second reading showed statistical importance in the thoracic region [4 ].Tab. 6 Vergleich zwischen der ersten und zweiten Befundung hinsichtlich interner Schäden. Die zweite Befundung ergab eine statistische Differenz in der Brustregion [4 ].
body part
internal injuries by first reading
internal injuries by second reading
McNemar’s test
neurocranium
23
27 (two skull fractures, not significant by all other intracranial injuries: additional subarachnoid and subdural bleeding was found)
0.134
vicerocranium
13
17 (three small not relevant fractures, one hematosinus)
0.134
neck
3
4 (one small muscular hematoma)
1
thoracic cavity
77
87 (five not dislocated rib fractures, four fractures of the lateral process of the vertebral body, one small lung contusion)
0.004
abdomen
59
61(one small subcapsular renal bleed, one not dislocated vertebral body fracture)
0.248
Comparison between the internal injuries from the first and second readings. The second reading showed statistical significance in the thoracic region (McNemar’s test = 0.0004). No vitally relevant injuries were recognized during the second reading that have been overlooked at the first reading.
Summary of the results
Superficial injuries of the skull and thorax on WBCT most likely correlate with internal injury.
No statistical correlation was observed between abdominal or cervical trauma and superficial injuries detected on the WBCT scans.
Traumatic events, such as a fall, traumas of unknown etiology, and other accidents associated with skin lesions were most likely associated with internal injuries.
Discussion
Patients with relevant traumatic incidents present an inhomogeneous group of individuals with different levels of clinical severity. The value of prioritizing WBCT for severely injured patients remains incontestable [5 ]
[6 ]. Determining which injured patients with varying degrees of severity will undergo WBCT is nowadays one of the most important decisions made by trauma teams [7 ]
[8 ]. Our study examined the use of visually accessible lesions that can be detected during simple clinical examination as potential markers for specific severe internal traumas revealed by WBCT.
Our results show that superficial injury of the thoracic wall is a valuable factor for potential internal damage, which has been confirmed by other authors [7 ]. CT scanning of the thoracic cavity allows exact visualization of treatable traumas and as a consequence makes it possible to quickly manage them. Our study verified that chest wall traumas warrant performing WBCT as they are highly correlated with internal damage and have a positive predictive value of 89 %. Previously, Collins et al. reported that severe chest wall trauma can be associated with large chest wall hematomas or free air within the chest wall. This type of injury could lead to surgical procedures and should be recognized and reported as soon as possible [9 ]
[10 ]
[11 ]. The study from Lang et al. shows that the routine use of WBCT for thoracic traumas increases the identification of so-called minor thoracic injuries [12 ].
Our study substantiates the importance of scalp trauma with any subgaleal hematoma. The positive predictive value of 38 % and negative of 93 % point out the statistical dependence. Furthermore, our observation has advantage over some clinical papers that investigated some of the related clinical scales. For example, according to the Glasgow Coma Scale, the neurological symptoms of the patient showed no evidence for a predictive value for intracranial lesions [13 ].
Another study pointed out a black eye as a possible sign of an underlying fracture in patients with a minor head injury [14 ]. Viscerocranium injuries are often identified by a selective workup. In our study they showed some statistical significance since the positive predictive value was 46 %.
The second WBCT reading discovered some missed injuries without clinical significance for the injured patients. The findings in the chest area showed some statistical significance, therefore strengthening our thesis that superficial injuries can strongly correlate with further internal injuries. The second WBCT reading should be taken into consideration to lower potential miscounted injuries and allow for the precise management of injured patients.
The assumption that all body areas would be accessible for clinical examination to the same extent as for cross-sectional imaging in polytraumatic patients was one of the limitations of our study. Certain body areas may not be accessible for clinical examination in an emergency setting, for example due to spine-stabilizing equipment. The second limitation of our study was related to the fact that our retrospective observation of the superficial lesions on CT scans was not correlated with a clinical examination. The third limitation was that data were obtained only from one university hospital center. Thus, our observations should be confirmed by multi-centric studies on larger populations.
Despite these limitations, our study opens up a new perspective regarding the field of polytrauma imaging with its variety of injuries from a real-world clinical setting. Existing studies typically focus on specific types of injuries in selected groups of patients (e. g. minor head traumas) and have consequently improved general knowledge. Yet, in the daily clinical routine, most patients suffer from multiple traumas, requiring a comprehensive and integrated approach. Therefore, our study included not just patients with isolated injuries.
Another research group [15 ] postulated that regular monitoring of WBCT findings paired with regular feedback from clinical examination would help to select patients with positive internal trauma for WBCT selection. In addition, the workflow in cases of life-threatening situations as well as the optimization of scan parameters in trauma management needs to be addressed [16 ]. There are many researchers who show no benefits of WBCT versus selective radiological workup [17 ]
[18 ]
[19 ] as well as those who point out many benefits of immediate cross-sectional imaging [20 ]
[21 ]. There are other studies that suggest a selected approach [22 ].
A discussion about indication and justification of WBCT connects the clinical and radiological workup. The commonly recommended feedback regarding WBCT findings by the radiologist to the clinician indicates great potential regarding close interdisciplinary cooperation in emergency medicine. Some authors highlight that evaluation and awareness of the clinical status is superior to the traumatic history in order to properly determine an indication for WBCT examinations [23 ].
In conclusion, we would like to raise awareness that traumatic lesions of the skin and subcutaneous tissue should not be underestimated in cross-sectional imaging reports as well as the clinical examination. Superficial lesions may justify the indication for WBCT and, as demonstrated by our study, when a superficial lesion occurs on the chest or neurocranium, an internal injury should be considered and furthermore selective cross-sectional imaging should be performed when clinically reasonable. Our findings should increase the detection of patients profiting from WBCT and help to avoid some underestimation of clinical information provided to the radiologist in their radiological reports.
