Keywords
children, injuries - infants, injuries - CT - trauma
Prompt completion of a whole-body CT examination is a fundamental part of trauma room
care for polytrauma patients in Germany [1]. In light of the risks that ionizing radiation poses for young patients, pediatric
surgeons and radiologists need to determine and review the indication for CT on a
conservative basis. A severe mechanism of injury alone is not sufficient to indicate
whole-body CT. A preceding careful clinical examination and ultrasound examination
based on eFAST or FAST ((extended) Focused Assessment with Sonography in Trauma) and
thus experience treating children are required. Compared to dedicated pediatric trauma
centers, general trauma centers are 1.8 times more likely to perform whole-body CT,
which highlights the fact that a lack of routine and experience treating injured children
can result in unnecessary diagnostic testing [2]. Even in pediatric trauma centers, injuries are found in only 1/3 of cases [3]. The majority of patients examined in this way are treated conservatively and an
indication for surgery is typically determined on the basis of symptoms and not imaging.
Therefore, CT does not have any direct therapeutic consequences in these cases [4]. So when should whole-body CT be performed and when can it be omitted?
For general radiologists, who usually do not have experience performing clinical examinations
of children, this decision can only be made on an interdisciplinary basis in coordination
with the entire trauma team. At the same time, a potentially severely injured child
represents a particularly stressful situation for treating physicians and requires
quick decisions. With the goal of providing radiologists with decision support in
such situations, this article addresses the advantages and disadvantages of whole-body
CT in children and the determination of the indication based on the relevant guidelines
and recently published clinical decision criteria for selecting the correct diagnostic
workup, with suggestions for protocol selection, special injury patterns, and typical
pitfalls.
How important is radiation protection in children?
How important is radiation protection in children?
Whether a single diagnostic dose of X-ray radiation increases cancer risk in general
and to a greater extent in children is controversial. The linear no threshold (LNT)
model which provides the foundation for most federal regulations is based on the assumption
that the increase in cancer rates seen in Hiroshima and Nagasaki after the atomic
bombing can be extrapolated linearly to lower radiation doses. In contrast, the hormesis
effect hypothesizes that low doses of ionizing radiation activate the DNA repair mechanisms
and could thus even have positive effects [5]. Therefore, it is unclear whether a single CT examination actually presents a real
health risk [6]. Calculations based on the LNT model estimate a lifetime incidence of up to one
additional case of cancer per 500 abdominal CT examinations or 1000 head CT examination
after exposure during childhood. However, these calculations are based in some cases
on significantly higher effective dose values than used in modern devices [7]. The actual disease rate is difficult to determine due to the very low incidence
of oncological diseases in children and young adults, the rare use of ionizing radiation
in childhood and adolescence, and the long observation periods. Therefore, most published
studies are retrospective registry studies with heterogeneous results. Multiple studies
observed an elevated risk for brain tumors or leukemia after head CT examinations
but the average dose values were higher than generally accepted today [8]
[9]
[10]. A recently published study could not establish an increase in risk from a single
CT examination. A greater risk was only seen in the case of 4 or more CT examinations,
especially in young patients < 6 years old [11]. However, an initial evaluation of the large European EPI-CT study was also able
to show an increased risk for brain tumors even in the case of low radiation doses
with a corresponding linear increase in risk at higher doses, which is supported by
the LNT model. Based on the calculations of the authors, approx. one additional brain
tumor per 10,000 head CT examinations occurred within 5–15 years of exposure [12]. Due to the ambiguity of the available data, there is consensus among most professional
societies that the indication especially for multiple CT examinations in young patients
should be reviewed critically. At the same time, the individual risk posed by a single
CT examination in children is probably very low so that parents can be reassured regarding
any concerns they may have about radiation. A clinically necessary CT examination
should never be skipped.
Dose reduction in pediatric CT examinations
Dose reduction in pediatric CT examinations
If a CT examination is performed in a child, the radiologist is responsible for selecting
the correct protocol, ensuring that the examination is performed correctly in accordance
with the guidelines of the German Medical Association on quality assurance, and for
applying all available dose reduction methods like iterative reconstructions, tube
voltage reduction, increased pitch factor, and device-specific automatic exposure
control with dynamic tube current modulation – with constant adjustment of the image
quality. The German Commission on Radiological Protection recommends the use of radiation
protection particularly for the eyes and thyroid, and in children also for the mammary
gland as applicable. Alternatively, many devices also have sectional tube current
modulation with a reduction of the direct organ dose [13]. However, particularly in the field of emergency diagnostics, its use should not
delay the examination. Many of the CT scanners currently available for emergency diagnostic
workup also allow reduction of the tube voltage, which is associated with a dose reduction
and can also improve the ability to delimit the contrast bolus by approaching the
k-edge of iodine [14]. Therefore, particularly in slender/small children, the tube voltage should be reduced,
depending on the device as low as 70 keV. Moreover, additional filters – e.g., tin
filters – are now widely available and can contribute to a significant dose reduction
especially in non-contrast examinations [15]. Furthermore, dual-energy protocols can reduce the number of contrast phases by
generating virtual non-contrast or monoenergetic reconstructions [16]. The photon counting technology that was recently introduced on the market provides
even further possibilities. By registering individual photons including their energy
in the detector, virtual monoenergetic images can be subsequently generated even without
the use of a dual energy scan – with simultaneously high detector efficiency and a
lack of electronic noise in the signal since only the photon signal is included in
the reconstruction [17]. New deep learning-based algorithms promise a further dose reduction with consistent
image quality for the future [18].
Questionable benefit of whole-body CT in injured children
Questionable benefit of whole-body CT in injured children
The main advantages of whole-body CT are the very high sensitivity and specificity
for detecting relevant injuries, the fact that it is largely examiner-independent,
and the fast implementation in the acute situation. Therefore, it has become established
as the modality of first choice when diagnosing polytrauma patients. The positive
effect of whole-body CT on morbidity and mortality in adult trauma care is well established
[1]
[19]. However, similar studies including children could not detect any positive effect
of whole-body CT on survival [20]
[21]. The authors attribute the results to the more frequent occurrence of isolated head
injuries without torso trauma and to the more rare occurrence of trauma to the bones
of the chest and pelvis, for which the greatest benefit of whole-body CT is assumed.
At the same time, sonographic examination of the abdominal organs in children is often
easier for anatomical reasons. Therefore, in an article recently published in the
Deutsches Ärzteblatt, Berger et al. recommend very conservative determination of the
indication for whole-body CT and prefer in most cases a combination of thorough and
possibly repeat sonographic examination and an organ-centered diagnostic workup (e.g.
isolated head CT) depending on the clinical examination and the injury mechanism [21]. A further alternative, if available, is whole-body MRI with abbreviated protocols
adapted to the acute situation [22]. As a rule, the risk of an injury not being diagnosed or being diagnosed too late
(delayed diagnosis of injury, DDI) should always be taken into consideration and a
necessary CT examination should never be withheld from an injured child.
Indication determination and modality selection
Indication determination and modality selection
In the current S2k guidelines on pediatric polytrauma care, whole-body CT continues
to play an important role since, for example, the indication is broad in the case
of “suspicion of blunt chest or abdominal trauma”. In contrast, the British guidelines,
for example, generally advise against whole-body CT in patients < 16 years and require
the indication to be separately determined for each body region [23]. All indications for whole-body CT according to the German S2k guidelines are listed
in [Table 1]
[24].
Table 1 Indications for whole-body CT based on the currently valid S2K guidelines “pediatric
polytrauma care” [20].
|
Changes in vital signs
|
Injury pattern
|
|
Loss of consciousness, intubation as a result of the trauma
|
Pediatric polytrauma
|
|
GCS ≤ 13 due to trauma
|
Suspicion of blunt chest or abdominal trauma
|
|
Oxygen saturation < 90%
|
Paralysis or suspicion of severe spinal injury
|
|
Changes in breathing rate
|
Unstable pelvis
|
|
Signs of shock (be sure to use age-based reference values)
|
At least 2 long bone fractures
|
|
Signs of severe injury (e.g., fracture with severe soft-tissue injury, amputation)
|
As a rule, according to the guidelines for both children and adults, the indication
for whole-body CT should be determined on the basis of the clinical examination and
not just depending on the trauma mechanism. Whole-body CT requires a suspected diagnosis
of polytrauma even after the primary survey (clinical examination, vital signs, FAST
ultrasound), i.e., an injury or a combination of injuries that could be life-threatening
alone or in combination [1]
[24].
If a decision against whole-body CT is made on this basis, a targeted diagnostic workup
can be performed based on the clinical findings. To prevent unnecessary diagnostic
testing and radiation exposure, there are different clinical decision criteria for
identifying patients with a very low risk of a relevant injury. The criteria of the
“Pediatric Emergency Care Applied Research Network” (PECARN), which were developed
in large multicenter studies in North America, are probably the most well known.
Head
The “PECARN rules” are the most established criteria for the indication for head CT.
They have been externally validated many times, see [Fig. 1]
[25]. In the German health care system, inpatient monitoring of uncertain cases is a
good alternative to initial head CT so that the indication can be determined on a
more conservative basis. Due to the higher sensitivity for most injuries and the lack
of radiation, magnetic resonance imaging (MRI), if available, is also a suitable alternative
for initial imaging in stable patients or for follow-up in the case of increasing
or persistent symptoms. In newborns and infants with an open fontanel, ultrasound
of the head is also possible but should not delay cross-sectional imaging when indicated
[26].
Fig. 1 PECARN criteria for determining the indication for head CT in mild head trauma [21]; ci-TBI: clinically important traumatic brain injury.
Spine
The existing clinical decision criteria for diagnostic imaging of spine and torso
injuries in children are unfortunately less established. The “NEXUS” criteria for
identifying injuries to the cervical spine that are widely used for adults could not
be sufficiently validated in children [27]. The PECARN criteria listed in [Table 2] have a high sensitivity of 98%. However, with strict application, the percentage
of patients to be examined could increase [28]
[29]. CT is rarely needed on an isolated basis but rather is typically performed as part
of an indicated head CT examination or whole-body CT examination. To clarify unclear
isolated spinal injuries, MRI is more sensitive, especially for ligament and intraspinal
injuries. Many guidelines continue to recommend acquiring X-ray images on two planes
as the basic diagnostic workup, but MRI is also being increasingly used for radiation-free
primary diagnosis as in our hospital [30].
Table 2 PECARN criteria for cervical spine and abdomen. If all criteria are met, X-ray (cervical
spine) and cross-sectional imaging (abdomen) are usually not needed [25]
[31].
|
Cervical spine
|
-
No impaired consciousness
-
No focal-neurological deficit
-
No torticollis
-
No neck pain
-
No severe torso injury
-
No fall injury
-
No high-speed traffic accident
-
No predisposing preexisting disease (e.g. Down syndrome, disease of the musculoskeletal
system)
|
|
Abdomen
|
|
Chest
Multiple studies have examined the added benefit of CT compared to conventional chest
X-ray in children. Hemothorax, pneumothorax, pneumomediastinum, and rib injuries can
also be visualized with high sensitivity on conventional X-ray. Injuries additionally
seen on CT only change the clinical management in exceptional cases. The most important
indication for chest CT is a suspected aortic injury. This is typically only seen
in the case of high speed trauma and is rarely an isolated occurrence so that whole-body
CT is usually indicated in these highly rare cases [32]
[33]
[34]
[35]
[36]. Due to the higher heart rate of pediatric patients compared to adults, significant
pulsation artifacts can occur particularly in the ascending aorta and can complicate
detection of an aortic dissection. Consequently, an ECG-triggered examination or an
examination with a high pitch factor (flash mode) should be considered [31]
[37]. Retrospective studies were able to show that clinically relevant isolated chest
injuries are very rare [38]
[39]. Therefore, isolated chest CT should only be performed in exceptional cases during
diagnostic workup in the trauma room. Conventional X-ray is typically sufficient in
the case of suspected chest trauma without polytrauma. Ultrasound is also a suitable
radiation-free alternative, particularly for the detection of pleural effusion. However,
the sensitivity with respect to pneumothorax is heterogeneous in the literature. In
the majority of published studies, ultrasound tends to have slightly better sensitivity
in adults than X-ray. This has not yet been able to be confirmed in children [40]
[41]. In groups with heterogeneous ultrasound training, very low sensitivities of only
16.8% have been described in some cases. Therefore, routine use requires prior examiner
training in the trauma room or it cannot be performed at all times [42].
Abdomen
The PECARN criteria for identifying children with a very low risk of therapeutically
relevant intraabdominal injury are listed in [Table 2]. If none of these criteria are met, the risk of overlooking an injury requiring
intervention is 0.1%. The greatest risk is in the case of visible trauma to the abdominal
wall, a seat belt sign, or decreased GCS (5.4%), which are strong indicators for abdominal
CT [43]. By introducing these structured criteria in the diagnostic workflow, Leeper et
al. were able to show a significant reduction in the number of CT examinations being
performed. Therapeutically relevant, higher grade organ injuries were still detected,
while the number of diagnosed, low grade injuries decreased [44]. Abdominal ultrasound can be used as an alternative diagnostic method. However,
particularly for FAST ultrasound performed prior to CT, the sensitivity for the detection
of intraabdominal injuries in children is low (between 27.8% and 56.5%) compared to
CT [45]
[46]. In the case of repeat examination by an experienced examiner combined with clinical
examination result, the sensitivity can increase to 87% [47]. When ultrasound contrast agent (CEUS – contrast-enhanced ultrasound) is used, the
sensitivity increases to 85–100%. Moreover, a lack of perfusion and active bleeding
can be visualized [48]. Unfortunately, properly trained examiners are not available around the clock in
many hospitals.
Extremities
Extremity injuries are usually examined by acquiring X-ray images on 2 planes. If
the first plane shows an indication for surgery, this is usually sufficient so that
the patient can be spared additional pain due to positioning [24]. When performing whole-body CT, fractures of the upper extremities, which are usually
secured to the upper body in the case of pain, can also be visualized on CT and correspondingly
reconstructed. Examination of the lower extremities is indicated particularly in complex
joint fractures and is associated with low additional radiation exposure so that it
can be performed following whole-body CT to avoid a time delay due to repositioning
and the acquisition of additional X-ray images.
Preclinical care – selecting a suitable trauma center
Preclinical care – selecting a suitable trauma center
As stated above, the number of CT examinations depends on the hospital's level of
experience with pediatric emergencies. Therefore, a decision should be made preclinically
as to whether the child needs to be transported to a pediatric trauma center. In the
future, telemedicine concepts as already used, for example, for stroke assessment
can provide support for selecting a suitable hospital [49]. Using a tablet at the accident location, it is possible to digitally transfer data
to the trauma center (e.g., NIDAmobile, medDV) so that important information can be
provided in advance particularly in adult medicine. Rogers et al. were able to show
the advantage of telemedicine techniques for emergency care by exchanging information
between the trauma center and the community hospital [50]. Pediatric emergency care appears to be a particularly useful area of application
since telemedicine support could have a significant benefit due to the rarity of pediatric
trauma [51]. Dayal et al. were able to show an improvement in the condition of transferred children
after the introduction of telemedicine consultations [52]. Therefore, Universitätsmedizin Mannheim is working on implementing telemedicine
concepts in pediatric emergency care.
Implementation: Examination protocols
Implementation: Examination protocols
The current guidelines recommend a non-contrast head CT examination in children and
adolescents < 15 years in whom whole-body CT is to be performed, followed by a monophasic
examination from the base of the skull to the pelvis in a venous contrast phase, alternatively
with administration of a split contrast bolus [24]. The contrast bolus is split and is administered with a time delay based on the
patient's weight, 45–65 seconds and 15–25 seconds before image acquisition [53]. The authors describe improved simultaneous contrast enhancement of arteries and
parenchymatous organs in a single-phase examination. The same is true for an isolated
CT examination of the abdomen [47].
The protocol can be supplemented by CT venography of the head if non-contrast CT examination
shows fractures in contact with the venous sinuses. In the case of injuries to the
urinary tract, a further examination in the excretion phase is usually indicated [24]. In individual cases, biphasic (arterial and venous) imaging can be indicated in
the case of suspicion of active bleeding [54]. In the case of an isolated head CT examination, some authors recommend including
the cervical spine up to C3 since upper cervical spine injuries are most common in
small children [30].
Depending on the selected protocol, the contrast dose is typically 1.5–2 ml/kg body
weight when using hyperosmolar contrast agents. Depending on the pump system that
is used, IV access, and the child's weight, manual injection may be needed. Use of
a 3-way valve system for the contrast agent and a saline solution for flushing is
recommended here to avoid time delays due to syringe changes. In the case of small-lumen
access, the contrast agent can be diluted 1:1 with a saline solution to lower the
viscosity. The location with the lowest radiation exposure for the examiner is directly
next to the gantry. However, it is typically possible to leave the room due to the
delay in monophasic examinations [55].
Typical injury patterns and pitfalls
Typical injury patterns and pitfalls
The typical injury patterns in children are age-dependent, partly due to anatomical
characteristics and partly due to a difference in activities. In small children, falls
are the dominant injury pattern. Since the head is large in proportion to the rest
of the body, head injuries are most common. With increasing age, activities involving
sports and road traffic increase and the incidence of body injuries increases. The
presence of head and chest injuries is associated with greater mortality [38]
[39]
[56].
Bones and ligaments in children have greater elasticity so that fractures of the axial
skeleton are rarer compared to adults. Isolated ligament lesions without an unstable
fracture are more common, are often not or only indirectly visible on CT, and require
primary or additional MRI examination. Particularly in small children, the majority
of detected injuries occur in the upper cervical spine due to the large size of the
head in proportion to the body and the consequently higher center of gravity. Atlanto-occipital
and atlanto-axial dislocation injuries are a typical example of injuries that occur
in young children but are rarely seen in adults, see [Fig. 2]
[30]
[57].
Fig. 2 Atlanto-axial dislocation in a 10-year-old boy. Clearly visible dislocation without
fracture on 3D MIP (left) and incongruence between the C1 and C2 vertebrae at the
level of the facet joint (right).
Thoracic injuries are typically not an isolated occurrence. However, in the case of
polytrauma, they are associated with increased mortality [38]. Due to the increased elasticity of bone in children, organ injuries without rib
fracture are not uncommon, e.g., lung contusions and lesions of the upper abdominal
organs. Injuries to the liver, spleen, and kidneys can be treated conservatively more
often in children than in adults. [Fig. 3] and [Fig. 4] show an example of dramatic image findings that were able to be treated without
surgery. In this connection, a precise evaluation regarding active bleeding on CT
angiography is important since the detection of active extravasation into the peritoneum
is a strong predictor of the failure of conservative management. This must be communicated
accordingly especially in the case of spleen lacerations, which are almost always
treated conservatively in children [54]. The second most injured organ after the upper abdominal organs is the bowel. This
injury is more common in children than adults [58]. Another critical injury is renal artery dissection, which must be ruled out with
duplex sonography if contrast-enhanced CT is not performed.
Fig. 3 Grade IV spleen trauma in a 12-year-old boy. The injury could be successfully treated
conservatively.
Fig. 4 4-year-old patient with grade IV renal laceration with extensive retroperitoneal hematoma
and tear of the lower pole of the kidney after trauma to the flank region resulting
from a fall, secondary finding of partially visualized grade II splenic laceration.
After placement of a ureteral stent, the patient could be successfully treated conservatively.
Especially infants and toddlers under the age of 3 years can be victims of child abuse.
However, the parents often provide a different medical history. Suspicious findings
requiring further clarification include subdural hematoma and upper cervical spine
injuries without corresponding trauma, dorsal rib fractures, sternum fractures, spinous
process fractures, metaphyseal apophyseal fractures of the extremities (bucket handle
fracture due to shaking of the extremities), and general presumably repeat injuries.
In the case of all pediatric trauma patients and particularly in the case of injury
patterns not corresponding to the injury mechanism, a non-accidental injury should
always be considered as a differential diagnosis and further workup in interdisciplinary
child protection teams should be performed as needed [59]
[60]. A typical presentation in the trauma room is an infant with lethargy. A non-contrast
head CT scan and ultrasound examination of the chest and abdomen are typically initially
sufficient for diagnosis in the case of corresponding suspicion.
Conclusion
It is essential for radiologists participating in the care of injured children to
be familiar with pediatric characteristics in order to determine the indication for
imaging and select, perform, and interpret imaging methods. Whole-body CT is only
one possibility for the diagnostic workup and should only be used after careful consideration
due to children's increased sensitivity to radiation and the often lower treatment
relevance in children. The indication for CT is typically determined separately for
each region of the body and on an interdisciplinary basis, ideally at a pediatric
trauma center. If the situation allows, ultrasound and MRI are often suitable radiation-free
alternatives for imaging injured children.
Die schnelle Durchführung einer Ganzkörper-Computertomografie (GK-CT) ist elementarer
Bestandteil der Schockraumversorgung von polytraumatisierten Patienten in Deutschland
[1]. Angesichts der besonderen Risiken ionisierender Strahlung für junge Patienten fällt
dem Kinderchirurgen und Radiologen die Aufgabe zu, die Indikation kritisch zu stellen
und zu prüfen. Ein schwerer Unfallmechanismus allein ist dabei nicht ausreichend,
um eine GK-CT zu indizieren, sondern bedarf einer vorhergehenden sorgfältigen klinischen
Untersuchung und Sonografie nach eFAST oder FAST-Schema ((extended) Focused Assessment
with Sonography in Trauma) – und damit Erfahrung in der Behandlung von Kindern. Allgemeine
Traumazentren führen im Vergleich zu dezidierten Kindertraumazentren 1,8-mal so oft
eine GK-CT-Diagnostik durch, was unterstreicht, dass fehlende Routine und Erfahrung
im Umgang mit verletzten Kindern zu einer Überdiagnostik führen können [2]. Selbst in Kindertraumazentren werden nur in 1/3 der Fälle Verletzungen gefunden
[3]. Der Großteil der so untersuchten Patienten wird konservativ behandelt und eine
eventuelle OP-Indikation wird in der Regel auf Basis der Klinik und nicht der Bildgebung
entschieden, das CT zieht also in diesen Fällen keine unmittelbare therapeutische
Konsequenz nach sich [4]. Wann sollte also ein GK-CT durchgeführt werden und wann kann darauf verzichtet
werden?
Für einen in der klinischen Untersuchung von Kindern meist unerfahrenen Allgemeinradiologen
kann diese Entscheidung nur im interdisziplinären Dialog mit dem gesamten Schockraumteam
gelingen. Gleichzeitig stellt ein potenziell schwerverletztes Kind eine besondere
Belastungssituation für die beteiligten Behandler dar und verlangt rasche Entscheidungen.
Um den Radiologen in dieser Situation als Entscheidungsstütze zu dienen, beschäftigt
sich der Hauptteil dieses Artikels mit den Vor- und Nachteilen der GK-CT bei Kindern,
Indikationsstellung nach den betreffenden Leitlinien und in den letzten Jahren veröffentlichten
klinischen Entscheidungskriterien für die Wahl der richtigen Diagnostik, ergänzt um
Vorschläge zur Protokollwahl sowie besondere Verletzungsmuster und typische Fallstricke.
