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94
8.2.3 Traumatic Lesions (What We Have to Search for)
Liver
Liver injuries include contusion (subtle and inhomogeneous area without vessel
displacement), laceration (clear band-like lesion, linear or branched), and parenchy-
mal or subcapsular hematoma (fl uid collection of variable attenuation and echo-
genicity within liver parenchyma or below the liver capsule).
On CEUS, liver lesions appear as markedly hypoechoic lines or bands and are
more evident than on baseline sonographic scans, also showing sharper borders
(Fig. 8.2 ). Injury conspicuity increases progressively while passing from arterial
phase scans (20–50 s from injection) to portal-sinusoidal scans (50–240 s), owing to
a progressive increase in parenchymal echogenicity. On early-phase images, subtle
hyperechogenicity (hypervascularity) can sometimes be noted around the injury,
suggesting perilesional hyperemia. In lacerative-contusive areas, CEUS allows opti-
mal depiction of defi ned lacerations, but in comparison with CT, CEUS less effec-
tively depicts the subtle contusive inhomogeneity. In a series of 87 patients, CEUS
was more sensitive than unenhanced sonography in directly showing hepatic lesions
(87 % vs. 65 %, 100 % specifi city) and correlated better with CT for injury size and
capsule involvement.
Hepatic lesions lack or have very little enhancement, appearing as hypoechoic
areas at CEUS. Although they may be visible in all three vascular phases, injuries
appear more evident during the venous phase. In the later phase, the images deterio-
rate very quickly, and the abnormalities become indistinguishable. The venous
phase is thus undoubtedly the most effi cient for liver injury detection and has been
called “the homogeneous phase.”
Some injuries, mainly in the liver, may appear quite large on CECT and smaller
on CEUS, as reported by McGahan and colleagues. Although surgical correlation is
lacking due to the conservative treatment, it is plausible that the hypoechoic area
seen with CEUS is related to the parenchymal laceration and the larger area seen
with CECT is the sum of the edema and the laceration. If this hypothesis is correct,
this is not a pitfall but an added value of CEUS, capable of distinguishing the true
lesion (laceration) from the surrounding edema. Minor lesions not seen with CEUS
may be areas of edema visible only with CECT but without clinical implication.
In liver injuries, CEUS can have some drawbacks. Because of the use of low-
emission-frequency harmonics, there is loss in spatial resolution and overall image
Tip and Tricks
• A double injection of UCA is needed for studying all the organs in all the
phases
• In the arterial phase, attention must be focused on the vessels in order to
highlight vascular injuries and UCA extravasation!
• UCAs are not eliminated from the kidney and cannot visualize lesions of
the pelvis and ureter
M. Valentino et al.
95
quality. The poor signal arising from the most deeply located lesions may give them
partially or completely unrecognized, resulting in a false-negative study. Moreover,
hepatic steatosis or fi brosis increases attenuation of the US beam reducing CEUS
capability and newly resulting in a false-negative study when exploring deep liver
portions.
Subcapsular or intraparenchymal hematoma appears as a hypoechoic area sur-
rounding or central to the organ, respectively (Fig. 8.3 ). Active hemorrhage is identi-
fi able during the fi rst phase as an extravasation of microbubbles into the hematoma.
Spleen
The spleen enhances very brightly, and UCAs accumulate in the parenchyma,
allowing lengthy examination. The superfi cial position and the small volume permit
optimal study.
Splenic injuries show a decreased or absent enhancement and are clearly seen
as opacifi cation defects, better evident during the late phase of enhancement.
A contusion appears as ill-defi ned, slightly hypoechoic areas, whereas a laceration
*
*
*
a
c
d
b
Fig. 8.2 A 19-year-old male admitted to hospital after a motor vehicle accident. ( a ) Sagittal
oblique sonogram shows a large nonhomogeneous hyperechoic area in the right lobe of the liver
( arrows ). ( b ) Color Doppler US shows the absence of vascularization. ( c ) CEUS scan in the same
position illustrates a large parenchymal laceration ( arrows ). The hepatic vessels ( asterisks ) are in
the area of the lesion, but there is no blushing. ( d ) MDCT confi rms the lesion ( arrowheads ) and the
absence of bleeding
8 CEUS: What Is It?
96
is seen as a clearly hypoechoic band, linear or branched, that is usually perpendicu-
lar to the spleen surface (Fig. 8.4 ). Contrast extravasation, indicating active bleed-
ing, is frequently seen in spleen fracture. On CEUS, it is detected as an early-phase
hyperechoic pool or jet within the splenic parenchyma or perisplenic hematomas
(Fig. 8.5 ). Differential diagnosis includes calcifi cations (already visible on baseline
images), normal vessels (different appearance and disposition), pseudoaneurysms
(limited practical value of differentiation), and uninjured parenchymal areas within
large lesions caused by contusions and lacerations (there is a different appearance
with lower echogenicity). Decreased splenic parenchymal enhancement (partial or
total) is a fi nding of traumatic infarction in vascular pedicle avulsion. According
to our previous report, the sensitivity of CEUS in detection of splenic injuries
approaches 100%.
*
ab
Fig. 8.3 A 62-year-old man admitted to hospital after a motor vehicle crash. ( a ) CEUS of the liver
reveals a fracture in the right lobe ( arrow ) with a large subcapsular hematoma ( calipers ). ( b ) MDCT
confi rms the lesions ( arrowhead and asterisk )
Fig. 8.4 Laceration of the lower
pole of the spleen. CEUS shows a
clearly hypoechoic linear band,
perpendicular to the spleen surface
( arrows )
M. Valentino et al.
97
The technique allows the exact evaluation of the number and the extension of the
lesions. Complex traumatic lesions can be easily recognized.
One disturbing factor that is not correlated to the vascular phases of the spleen is
a common, quite rapid decrease of the enhancement in the parenchymal splenic
veins. About 2–3 min following the injection, the veins become anechoic. This is
probably due to the effective fi ltration of microbubbles from the circulation on the
part of the spleen. At fi rst, this phenomenon is somewhat confusing, as the veins can
be mistaken for lacerations, but with awareness of the problem, it can be resolved.
If in doubt, a reinjection of a small amount of UCA is an effi cient solution.
Kidney
Renal injuries present as defects of vascularization in a well-perfused parenchyma.
Contusions appear as focal alterations of enhancement; interruption of the renal
profi le is consistent with a laceration (Fig. 8.6 ). Renal artery tear or thrombosis
presents with the absence of parenchymal perfusion. Focal UCA extravasation sug-
gests active hemorrhage.
a
c
b
Fig. 8.5 A 21-year-old male admitted to hospital after a motor vehicle trauma. ( a ) CEUS scan
shows a linear laceration in the lower pole of the spleen ( arrow ). ( b ) In the late phase, a focal
extravasation of UCA demonstrated an active bleeding ( arrow ). ( c ) MDCT confi rmed the lesion
( arrowhead )
8 CEUS: What Is It?
98
The homogeneous phase is still the most effective phase for the detection of trau-
matic injuries. Until today, little specifi c attention has been paid to the role of emergency
sonography in evaluating acute renal trauma. In our experience with traumatic lesions,
at CEUS a subcapsular hematoma appears as an inhomogeneous collection surrounding
the kidney while a laceration is a clear hypoechoic band, possibly associated with a
subcapsular hematoma. It is benefi cial to use a small dose of UCA for visualizing the
traumatic lesions of the kidney, since too much contrast may cause a glare that covers
very thin lacerations. If the phenomenon occurs, it can be corrected by performing a
new examination using a low dosage immediately after the bubble destruction.
Although injection of UCAs improves the sensitivity of US for identifi cation of
renal injuries, the role of this technique in clinical practice is debatable. Injury to the
renal collecting system may be overlooked at CEUS because of a lack of micro-
bubbles in urinary excretion. Small renal injuries may be unidentifi ed, especially
when perirenal hematoma is small or absent.
ab
Fig. 8.6 ( a ) CEUS shows a laceration of the left kidney with interruption of the posterior profi le
( arrows ). ( b ) MDCT confi rms the lesion ( arrowheads ) (multiplanar sagittal reconstruction)
Pitfalls
• Splenic arterial phase can mimic a scattered spleen. Lesions are visualized
in a late phase
• Peri-traumatic lesions (extracapsular hematomas) are not visible on CEUS
as on CT, because parenchyma remains well vascularized
• Contrast extravasation at CEUS imaging is detected immediately after ves-
sel opacifi cation, spreading to the hemorrhage site, and it appears as a
round/oval spot of variable sizes or as a fountain-like or serpentine-like
hyperechoic jet
• Pseudoaneurysm has an appearance very similar to contrast extravasation
but is a round or oval mass continuous with the vessel; both occurrences,
active bleeding and posttraumatic pseudoaneurysm, require a surgical
decision (surgery or embolization)
M. Valentino et al.
99
8.2.4 Nonoperative Management
Nonoperative management is today the preferred treatment for the solid organ inju-
ries of grades 1–3 according to AAST grading. All nonsurgical patients are usually
staged by abdominal CT scanning and are closely monitored in an intensive care
unit setting. Although delayed bleeding seems extremely rare, delayed rupture of
the spleen remains a major concept; therefore, patients undergo repeated imaging
procedures before discharge. Currently, CT plays an important role in the follow-
up, improving the success rate of nonsurgical management.
CEUS is ideally suited for the follow-up of abdominal solid organ lesions man-
aged conservatively, especially in young patients, because it reduces the number of
CT scans.
CEUS can be proposed for serial imaging of conservatively treated solid organ
injuries. It can be performed at the bedside safely and without radiation exposure
until the lesions are completely healed.
Suggested Reading
1. Bertolotto M, Catalano O (2009) Contrast-enhanced ultrasound: past, present, and future.
Ultrasound Clin 4:339–367
2. Catalano O, Lobianco R, Raso MM, Siani A (2005) Blunt hepatic trauma: evaluation with
contrast-enhanced sonography: sonographic fi ndings and clinical application. J Ultrasound
Med 24:299–310
3. Catalano O, Sandomenico F, Raso MM, Siani A (2005) Real-time, contrast enhanced sonogra-
phy: a new tool for detecting active bleeding. J Trauma 59:933–939
4. McGahan JP, Horton S, Gerscovich EO et al (2006) Appearance of solid organ injury with
contrast-enhanced sonography in blunt abdominal trauma: preliminary experience. AJR Am
J Roentgenol 187:658–666
5. Piscaglia F, Bolondi L (2006) The safety of SonoVue
®
in abdominal applications: retrospective
analysis of 23188 investigations. Ultrasound Med Biol 32(9):1369–1375
6. Thorelius L (2007) Emergency real-time contrast-enhanced ultrasonography for detection of
solid organ injuries. Eur Radiol 17(Suppl 6):F107–F112
7. Valentino M, Serra C, Pavlica P, Barozzi L (2007) Contrast-enhanced ultrasound for blunt
abdominal trauma. Semin Ultrasound CT MR 28:130–140
Remember
• The use of contrast agents in ultrasound signifi cantly improves detection of
solid organ injury and is an area still under investigation
• While contrast-enhanced ultrasound may evaluate solid organ injuries,
bowel and mesenteric injuries remain best assessed by CT scan
• US is less panoramic than CT, and CEUS cannot replace CT in the initial
assessment of trauma
• CEUS has the potential to replace CT in follow-up when nonoperative
treatment is realized, in an effort to minimize diagnostic radiation, espe-
cially in younger patients
8 CEUS: What Is It?
100
8. Valentino M, Serra C, Pavlica P et al (2008) Blunt abdominal trauma: diagnostic performance
of contrast-enhanced US in children-initial experience. Radiology 246:903–909
9. Valentino M, Serra C, Zironi G et al (2006) Blunt abdominal trauma: emergency contrast-
enhanced sonography for detection of solid organ injuries. AJR Am J Roentgenol 186:
1361–1367
10. Xu HX (2009) Contrast-enhanced ultrasound: the evolving applications. World J Radiol
1(1):15–24
M. Valentino et al.