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DOI:10.2214/AJR.05.0946
AJR 2006; 187:658-666
© American Roentgen Ray Society


Original Research

Appearance of Solid Organ Injury with Contrast-Enhanced Sonography in Blunt Abdominal Trauma: Preliminary Experience

John P. McGahan1, Stephanie Horton1, Eugenio O. Gerscovich1, Marijo Gillen1, John R. Richards2, Michael S. Cronan1, John M. Brock1, Felix Battistella3, David H. Wisner3 and James F. Holmes2

1 Department of Radiology, University of California, Davis School of Medicine, UC Davis Medical Center, 4860 Y St., Ste. 3100, Sacramento, CA 95817.
2 Department of Emergency Medicine, University of California, Davis School of Medicine, UC Davis Medical Center, Sacramento, CA 95817.
3 Department of Surgery, University of California, Davis School of Medicine, UC Davis Medical Center, Sacramento, CA 95817.

Received June 3, 2005; accepted after revision July 22, 2005.

 
Supported by an internally funded grant from the Department of Radiology, University of California, Davis. Address correspondence to J. P. McGahan (john.mcgahan{at}ucdmc.ucdavis.edu).


Abstract
Top
Abstract
Introduction
Subjects and Methods
Results
Discussion
References
 
OBJECTIVE. The purpose of this study was to compare the detection rate of injury and characterize imaging findings of contrast-enhanced sonography and non-contrast-enhanced sonography in the setting of confirmed solid organ injury.

SUBJECTS AND METHODS. This prospective study involved identifying hepatic, splenic, and renal injuries on contrast-enhanced CT. After injury identification, both non-contrast-enhanced sonography and contrast-enhanced sonography were performed to identify the possible injury and to analyze the appearance of the injury. The sonographic appearance of hepatic, splenic, and renal injuries was then analyzed, and the conspicuity of the injuries was graded on a scale from 0 (nonvisualization) to 3 (high visualization).

RESULTS. Non-contrast-enhanced sonography revealed 11 (50%) of 22 injuries, whereas contrast-enhanced sonography depicted 20 (91%) of 22 injuries. The average grade for conspicuity of injuries was increased from 0.67 to 2.33 for spleen injuries and from 1.0 to 2.2 for liver injuries comparing non-contrast-enhanced with contrast-enhanced sonography, respectively, on a scale from 0, being nonvisualization, to 3, being high visualization. The splenic injuries appeared hypoechoic with occasional areas of normal enhancing splenic tissue within the laceration with contrast-enhanced sonography. Different patterns were observed in liver injuries including a central hypoechoic region. In some liver injuries there was a surrounding hyperechoic region.

CONCLUSION. Contrast-enhanced sonography greatly enhances visualization of liver and spleen injuries compared with non-contrast-enhanced sonography. Solid organ injuries usually appeared hypoechoic on contrast-enhanced sonography, but often a hyperechoic region surrounding the injury also was identified with liver injuries.

Keywords: abdominal imaging • contrast media • sonography • trauma


Introduction
Top
Abstract
Introduction
Subjects and Methods
Results
Discussion
References
 
The main focus of sonography for the patient with blunt abdominal trauma is the detection of free fluid. In one original report, this sonographic examination consisted of only a single view of Morison's pouch to detect free fluid [1]. However, during its evolution over the past three decades, sonography for blunt abdominal trauma has become more standardized and is now termed "focused abdominal sonography for trauma" (FAST) [2]. Early studies showed the sensitivity of sonography, using detection of free fluid alone, to be in the range of 90%, with specificities of from 97% to 100% [3-6]. Although FAST is primarily used for the detection of free fluid in the abdomen or pelvis, there have been studies showing the ability to detect parenchymal organ injury [6, 7]. Although most researchers have either ignored detection of solid organ injury or reported a low detection rate [1], there have been studies in which detection of solid organ injury with FAST was 41% [6, 7]. A limitation of sonography using only free fluid as the sole criterion of injury is that parenchymal injuries requiring surgery or embolization may be present without free fluid [8-11].

More recently, several authors have reported an increased detection rate of solid organ injury in patients with blunt abdominal trauma using contrast-enhanced sonography [12-14]. In this study, we present our preliminary data using contrast-enhanced sonography to detect solid organ injury in patients with blunt abdominal trauma and compare contrast-enhanced sonography and non-contrast-enhanced sonography with CT.


Subjects and Methods
Top
Abstract
Introduction
Subjects and Methods
Results
Discussion
References
 
This prospective study was conducted from June 2004 through March of 2005 and was approved by our institutional review board. Written informed consent was obtained from all patients. Subjects considered for inclusion were 18 years old or older who had an injury of the liver, spleen, or kidney detected on CT and were not candidates for immediate surgery. All patients underwent dedicated contrast-enhanced CT (LightSpeed 16, GE Healthcare) of the abdomen and pelvis with IV contrast material (120-150 mL of iohexol [Omnipaque 300, Amersham Health]) injected at 2.5 mL/s. No oral contrast material was administered. The technique used an automatic milliamperage setting from 200 to 440 mA at 120 kV. Detector collimation was 1.25 mm, and scans were reconstructed at 5 mm every 5 mm. A 5-minute delayed scan of the upper abdomen was obtained using a similar technique.

Organ injuries detected on CT were graded using a scale developed by the American Association for the Surgery of Trauma for splenic, hepatic, and renal injuries [15-17]. A modified and abbreviated version of this scale created by the Organ Injury Scaling Committee of the American Association for the Surgery of Trauma for liver and spleen injuries is presented in Tables 1 and 2; for a more complete table and CT modification of the tables, the reader is referred to references 15 through 17.


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TABLE 1: American Association for the Surgery of Trauma (AAST) Scale and Modified Scale for Classification of Liver Injuries

 

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TABLE 2: American Association for the Surgery of Trauma (AAST) Scale and Modified Scale for Classification of Liver Injuries

 

Radiology faculty interpreting the CT examinations notified the clinical coordinator when a patient had a solid organ injury detected on CT. The clinical coordinator was blinded to the site of injury. A different radiology faculty member—not involved in interpreting the CT examination and blinded to the site of the injury—was notified to obtain informed consent. Baseline sonography followed by contrast-enhanced sonography was then performed. All sonographic examinations were performed by the same sonographer who had more than 2 years of experience with contrast-enhanced sonography. The radiologist who had obtained informed consent was present for the sonographic examinations. Sonography was always performed within 48 hours after the CT examination.

All sonography examinations were performed on a Sequoia unit (Siemens-Acuson); baseline scan images of the right upper quadrant, left upper quadrant, mid epigastrium, right flank, left flank, and pelvis were obtained using a 4-MHz convex transducer. Tissue harmonics were used with a 4-MHz convex transducer using a low mechanical index of 0.3-0.6 for the contrast-enhanced sonography portion of the examination. For contrast enhancement, a 0.1-mL dose of SH U 508A (Definity, Bristol-Myers Squibb) was injected within 30 seconds into an antecubital vein followed by a 10-mL saline flush. Immediately after contrast injection, the right upper quadrant of the abdomen was scanned for 3-4 minutes until the enhancement effect began to subside. Then another 0.1-mL dose of SH U 508A was injected, followed by imaging of the left upper quadrant of the abdomen for 3-4 minutes. In four patients, 0.2-mL of SH U 508A was injected at one site because of inadequate contrast response in the organ of interest. All injections were performed by one individual. All video and still images were recorded for review on a workstation (Kinetics, Siemens-Acuson). Only selected 2-second video clips of the examinations, including at least arterial, venous, and delayed images, were obtained. Injections were separated by a time interval of approximately 5-7 minutes. The total time for the examination was approximately 15 minutes; the SD of the time needed for each examination was not calculated.

A data sheet was completed by both radiologists noting the presence or absence of injury and, if present, the extent of solid organ injury shown on CT, non-contrast-enhanced sonography, and contrast-enhanced sonography. The presence or absence of free fluid detected using CT, non-contrast-enhanced sonography, and contrast-enhanced sonography was noted by both radiologists. The injury was graded based on its conspicuity from 0 to 3 for non-contrast-enhanced sonography, contrast-enhanced sonography, and CT. The scale used was adapted from Catalano et al. [14], where 0 = not recognizable; 1 = low injury-to-parenchyma gradient; 2 = medium injury-to-parenchyma gradient; and 3 = high injury-to-parenchyma gradient. Thus for grade 0, the echogenicity of the suspected region of injury and the echogenicity of the noninjured parenchyma were nearly equal and the injury was not seen. In grade 3 injuries, the echogenicity of the region of injury was very different from the echogenicity of the noninjured parenchyma and the region of injury was easily identified. Grade 1 and grade 2 injuries were intermediate in conspicuity on this scale. Grade 1 injuries were seen but were not as easily identified as grade 2 injuries. The sonographic appearance of these injuries was described as hypoechoic, isoechoic, or hyperechoic.


Figure 1
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Fig. 1A Splenic laceration with subcapsular hematoma in 46-year-old woman. CT scan shows large splenic laceration with surrounding subcapsular hematoma.

 


Figure 2
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Fig. 1B Splenic laceration with subcapsular hematoma in 46-year-old woman. Longitudinal non-contrast-enhanced sonogram shows central heterogeneous region (arrow) with normal-appearing spleen posteriorly and subcapsular hematoma anteriorly.

 


Figure 3
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Fig. 1C Splenic laceration with subcapsular hematoma in 46-year-old woman. Longitudinal contrast-enhanced sonogram shows that splenic tissue noted posteriorly appears perfused and echogenic. Central region (arrow), which is nonperfused, is more hypoechoic and corresponds to region of splenic laceration. More anterior hypoechoic region corresponding to subcapsular hematoma remains hypoechoic.

 

Results
Top
Abstract
Introduction
Subjects and Methods
Results
Discussion
References
 
The results for CT, non-contrast-enhanced sonography, and contrast-enhanced sonography are reported in Table 3. CT depicted free fluid in 10 of 20 patients. There was no difference in the detection of free fluid between non-contrast-enhanced sonography and contrast-enhanced sonography; both showed free fluid in the same 10 of 20 patients as revealed on CT. Eleven subcapsular hematomas of the liver or spleen were identified on CT. Only four (36%) were seen on non-contrast-enhanced sonography, whereas all 11 (100%) were seen on contrast-enhanced sonography (Figs. 1A, 1B, and 1C). There were no false-positive non-contrast-enhanced sonography or contrast-enhanced sonography examinations.


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TABLE 3: Visualization of Subcapsular Hematomas and Organ Injuries on Contrast-Enhanced CT, Non–Contrast-Enhanced Sonography, and Contrast-Enhanced Sonography

 

Twenty-two solid organ injuries were detected in 20 patients on CT. Non-contrast-enhanced sonography showed 11 (50%) of the 22 injuries, whereas contrast-enhanced sonography showed 20 (91%) of the 22 injuries. Classification of hepatic and splenic injuries and the number of each type are presented in Tables 4 and 5. The only liver injury not visualized on contrast-enhanced sonography during prospective review was a 2.5-cm laceration in the left lobe. However, during retrospective review of the video record, this laceration could be identified as a linear hypoechoic region. The conspicuity scale breakdown for the spleen and liver injuries is presented in Tables 6 and 7. The average conspicuity grade for the splenic injuries increased from 0.67 for non-contrast-enhanced sonography to 2.33 for contrast-enhanced sonography. With regard to liver injuries, the conspicuity scale increased from 1.0 for non-contrast-enhanced sonography to 2.2 for contrast-enhanced sonography. Injuries that were not identified on either non-contrast-enhanced sonography or contrast-enhanced sonography were given a score of 0.


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TABLE 4: Splenic Injury Severity Compared with Detection Rate on Non–Contrast-Enhanced Sonography and Contrast-Enhanced Sonography

 

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TABLE 5: Liver Injury Severity Compared with Detection Rate on Non–Contrast-Enhanced Sonography and Contrast-Enhanced Sonography

 

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TABLE 6: Spleen Injuries: Comparison of Conspicuity on CT, Non–Contrast Enhanced Sonography, and Contrast-Enhanced Sonography

 

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TABLE 7: Liver Injuries: Comparison of Conspicuity on CT, Non–Contrast Enhanced Sonography, and Contrast-Enhanced Sonography

 

There were three renal injuries in which only a renal laceration with a subcapsular hematoma was seen on non-contrast-enhanced sonography. These injuries were better seen with contrast-enhanced sonography. An avulsed kidney was not seen on non-contrast-enhanced sonography, whereas it was identified on contrast-enhanced sonography. A renal laceration was not seen with contrast-enhanced sonography.

The echogenicity of liver and spleen injuries before and after contrast administration was of particular interest. Splenic injuries were most often hypoechoic when visualized on non-contrast-enhanced sonography (Figs. 1A, 1B, and 1C). Three of four injuries seen on non-contrast-enhanced sonography were hypoechoic compared with the surrounding parenchyma. On contrast-enhanced sonography, these injuries appeared more conspicuous and hypoechoic against the surrounding enhanced splenic parenchyma. All injuries identified on contrast-enhanced sonography were hypoechoic compared with surrounding parenchyma (Figs. 1A, 1B, 1C, 2A, and 2B). Areas of enhancement of the splenic parenchyma could be observed within stellate splenic lacerations and were similar to the appearance on CT (Figs. 3A and 3B). The avascular regions appeared hypoechoic and devoid of contrast microbubbles on contrast-enhanced sonography, whereas microbubbles could be seen in the surrounding parenchyma. Unfortunately, in our imaging studies, the transaxial CT plane could not be reproduced exactly with sonography because of overlying ribs.


Figure 4
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Fig. 2A Splenic laceration in 20-year-old woman. CT scan of abdomen shows well-demarcated splenic laceration (arrow).

 

Figure 5
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Fig. 2B Splenic laceration in 20-year-old woman. Non-contrast-enhanced sonogram was interpreted as showing normal findings, whereas this axial contrast-enhanced sonogram shows well-demarcated hypoechoic splenic laceration (arrow), which correlated with appearance on contrast-enhanced CT.

 

Figure 6
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Fig. 3A Splenic laceration in 23-year-old woman. CT scan of abdomen shows regions of normal enhancing splenic tissue (arrow) within splenic laceration.

 

Figure 7
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Fig. 3B Splenic laceration in 23-year-old woman. Based on longitudinal non-contrast-enhanced sonogram (not shown), spleen was interpreted as normal; however, this axial contrast-enhanced sonogram shows splenic laceration corresponding to region on CT with areas within laceration that were perfused splenic tissue (arrow).

 
In most patients with liver injuries, there was correlation between CT, non-contrast-enhanced sonography, and contrast-enhanced sonography. Most commonly a hypodense region within the liver detected on CT corresponded to a heterogeneous hyperechoic region on non-contrast-enhanced sonography. In four of six cases in which injury was seen on non-contrast-enhanced sonography, the appearance of the liver injury compared with surrounding parenchyma was hyperechoic. One injury was hypoechoic on non-contrast-enhanced sonography, whereas another injury was hyperechoic with a central hypoechoic region on non-contrast-enhanced sonography. This was then followed by contrast-enhanced sonography showing a hypoechoic region in six cases (Figs. 4A, 4B, and 4C). However, a different pattern was identified in some liver injuries. In these cases, the hyperechoic region of injury detected on non-contrast-enhanced sonography was also identified on contrast-enhanced sonography. The periphery of this hyperechoic region appeared to enhance on contrast-enhanced sonography in three cases (Figs. 5A, 5B, 5C, 6A, 6B, 6C, and 6D). However, within the center of the hyperechoic region, a linear hypoechoic region was identified using contrast-enhanced sonography in three cases (Figs. 5A, 5B, 5C, 6A, 6B, 6C, and 6D).


Figure 8
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Fig. 4A Liver laceration in 46-year-old woman. CT scan of liver shows fairly well-demarcated region of decreased density within liver (arrow) corresponding to area of injury.

 

Figure 9
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Fig. 4B Liver laceration in 46-year-old woman. Longitudinal non-contrast-enhanced sonogram was interpreted as normal.

 

Figure 10
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Fig. 4C Liver laceration in 46-year-old woman. Axial contrast-enhanced sonogram shows central hypoechoic region (straight arrow). Hypoechoic region was surrounded by perfused hyperechoic region (curved arrow).

 

Figure 11
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Fig. 5A Liver laceration in 21-year-old woman. CT scan of liver shows large irregular liver injury.

 

Figure 12
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Fig. 5B Liver laceration in 21-year-old woman. Longitudinal non-contrast-enhanced sonogram of liver shows fairly large echogenic region of liver (arrow) that corresponds to site of injury identified on CT.

 

Figure 13
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Fig. 5C Liver laceration in 21-year-old woman. Longitudinal contrast-enhanced sonogram shows echogenic region (arrowhead) to be perfused and to appear slightly more echogenic than normal liver. However, there was nonperfused central hypoechoic region (curved arrow). Also note hematoma in hepatorenal fossa (straight arrow) that was not identified on initial non-contrast-enhanced sonogram.

 

Figure 14
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Fig. 6A Liver laceration in 32-year-old man. CT scan of abdomen shows large irregular liver injury and subcapsular hematoma surrounding liver and spleen.

 

Figure 15
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Fig. 6B Liver laceration in 32-year-old man. Longitudinal non-contrast-enhanced sonogram shows large heterogeneous hyperechoic region (arrow) noted in liver in corresponding area of injury identified on CT.

 

Figure 16
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Fig. 6C Liver laceration in 32-year-old man. Contrast-enhanced sonogram shows that some of peripheral region that appeared hyperechoic on non-contrast-enhanced sonogram is perfused (arrowhead). However, more centrally, there is hypoechoic region (arrow) that corresponds to region of liver laceration, hematoma, or both.

 
For some of these injuries, there were minor discrepancies between the size of the injury on non-contrast-enhanced sonography, contrast-enhanced sonography, and CT. An example of this discrepancy is shown in Figures 5A, 5B, and 5C in which a presumed large liver laceration is detected on CT. Non-contrast-enhanced sonography shows an echogenic area roughly corresponding to the CT finding. However, contrast-enhanced sonography depicts a smaller hypoechoic region centrally surrounded by an isoechoic to hyperechoic region that appeared to enhance on contrast-enhanced sonography.


Discussion
Top
Abstract
Introduction
Subjects and Methods
Results
Discussion
References
 
Initial reports about the use of sonography in patients with blunt abdominal trauma concentrated on detection of free fluid in the abdomen, and in many early studies, there were very high sensitivity rates for this application. For instance, Rothlin and associates [6] reported a sensitivity rate of 90.0% and a specificity of 99.5% of the sonographic examination in patients with blunt abdominal trauma. However, as suggested by Rozycki et al. [18], the reason for this high sensitivity rate was that patient outcome rather than CT was used to establish the sensitivity of sonography. When FAST was compared with CT by McGahan et al. [7], FAST depicted free fluid in 63% of the patients with solid organ injuries or free fluid identified on CT. Because free fluid has been used by most authors as the sole criterion for a positive FAST, contained parenchymal injuries have been shown to be missed by this approach [7, 11].

There have been few reports of FAST being used to detect solid organ injury. Both McGahan et al. [7] and Rothlin et al. [6] showed a detection rate of solid organ injuries with FAST of 41%, but most researchers have reported a low detection rate or have not attempted to use FAST to look for solid organ injury. Both groups of authors used a modified FAST scan, which included not only an examination to check for free fluid, but also an examination to evaluate the solid organs using sonography. This same approach is used by Catalano et al. [14] who described it as the "full potential" sonographic technique, instead of the "minimized" FAST evaluating only free fluid. More recently, there have been a number of reports evaluating the use of contrast-enhanced sonography for the detection of solid organ injury [12-14]. For the evaluation of splenic trauma, Catalano et al. [12] showed that avascular splenic areas that were not visualized on non-contrast-enhanced sonography were well seen on contrast-enhanced sonography and CT.

Miele et al. [13] also reported promising results with contrast-enhanced sonography for the detection of liver injuries. They concluded that contrast-enhanced sonography could be the first diagnostic imaging study for patients with minor trauma, whereas CT should be used in patients with more severe trauma. Catalano et al. [14] reviewed the use of contrast-enhanced sonography in the evaluation of liver trauma in 21 patients. On the basis of their findings, they characterized contrast-enhanced sonography as a promising tool in the initial assessment and follow-up of patients with blunt liver trauma.

In another study, Catalano et al. [19] showed contrast-enhanced sonography to be useful for detecting intraabdominal vascular injuries, such as ruptured abdominal aortic aneurysms. However, Poletti et al. [9] took a more cautious approach with the use of contrast-enhanced sonography.

They compared three different types of sonograms to CT. The initial or admission FAST examination was compared with a non-contrast-enhanced sonography control examination followed by contrast-enhanced sonography. They found the detection rate of solid organ injuries for the admission FAST examination, non-contrast-enhanced sonography, and contrast-enhanced sonography was 40%, 57%, and 80%, respectively. Although encouraged by this improved detection rate with contrast-enhanced sonography, they were discouraged because 18% of solid organ injuries were missed on contrast-enhanced sonography even after low-quality examinations had been eliminated. Their conclusion was that contrast-enhanced sonography cannot be recommended to replace CT in hemodynamically stable trauma patients but that it may be helpful for detecting delayed findings such as a splenic pseudoaneurysm.

In reviewing our data, there are several interesting observations. The first is the difference in appearance of parenchymal organ injury between the non-contrast-enhanced sonography and subsequent contrast-enhanced sonography examinations. As documented by other researchers [20-22], the appearance of an organ injury on non-contrast-enhanced sonography may be hyperechoic, mixed echogenic, or hypoechoic. However, this pattern changes with the administration of contrast material. As the rest of the organ is perfused and becomes hyperechoic, the area of injury is hypoperfused and becomes more hypoechoic and conspicuous compared with the surrounding parenchyma. In the spleen, the injury was often hypoechoic on non-contrast-enhanced sonography and became more conspicuous on contrast-enhanced sonography (Figs. 2A, 2B, 3A, and 3B). Furthermore, regions of normal, perfused spleen could be observed within the anatomic site of injury (Figs. 3A and 3B). This pattern occurred with stellate splenic lacerations and has not, to our knowledge, been previously reported using contrast-enhanced sonography. Not all spleen lacerations are completely linear or wedge-shaped; instead, they may be more complex or stellate, with normal areas of enhancing parenchyma seen within the region of laceration.


Figure 17
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Fig. 6D Liver laceration in 32-year-old man. Contrast-enhanced sonogram obtained in slightly different area shows there is central hypoechoic echoic region (arrow) with surrounding perfused echogenic area (arrowhead).

 
Liver injuries were often not seen on non-contrast-enhanced sonography and appeared hypoechoic on contrast-enhanced sonography [14] (Figs. 4A, 4B, and 4C). In some cases, these liver injuries appeared quite large on non-contrast-enhanced sonography and CT, but on contrast-enhanced sonography the periphery of the injured area stayed hyperechoic and the microbubbles were visualized. A hypoechoic region was localized more centrally and was not perfused with administration of contrast material. Although surgical correlation is lacking for these liver injuries treated conservatively, it is plausible that the central hypoechoic region is the laceration and that the surrounding hyperechoic region is severely injured tissue that had a mixture of viable and nonviable tissues (Figs. 5A, 5B, 5C, 6A, 6B, 6C, and 6D). This imaging appearance was also reported by Poletti et al. [9] who postulated that contrast-enhanced sonography may give further insight into the true nature of an injury. For instance, they reported a number of patients with solid organ injuries that were not detected on contrast-enhanced sonography. These injuries were most often minor ones, which may have been affected by edema (contusions), whereas more significant injuries such as lacerations are seen as hypoechoic regions on contrast-enhanced sonography. Contrast-enhanced sonography may thus change our understanding of injuries to solid organs. If this hypothesis is correct, contrast-enhanced sonography may have importance in further characterizing true lacerations from injuries in which edema (contusion) is the predominate pattern [9]. A limitation of the study is the small number of patients, but if this hypothesis were confirmed by a large series, contrast-enhanced sonography could become an important adjunct to CT in the characterization of a solid organ injury and subsequent triage to further intervention.

Although we did not detect any pseudoaneurysms in our series, both Poletti et al. [9] and Catalano et al. [12] have shown that pseudoaneurysms are clearly depicted by contrast-enhanced sonography as a well-delineated and focal hyperechoic region. They concluded that contrast-enhanced sonography may have a role in the detection of delayed pseudoaneurysm from blunt abdominal trauma [19], but this finding needs to be confirmed with further prospective studies.

We detected all 11 subcapsular hematomas on contrast-enhanced sonography compared with detection of only four of the 11 on non-contrast-enhanced sonography. One explanation for this discrepancy in detection is that free fluid appears hypoechoic on non-contrast-enhanced sonography, whereas subcapsular hematomas are echogenic. However, with contrast-enhanced sonography, these hematomas have little or no perfusion of contrast material, and thus appear hypoechoic compared with normal surrounding parenchyma (Figs. 5A, 5B, and 5C).

Our study has some limitations. Although reviewers were blinded to the site of organ injury on contrast-enhanced sonography and non-contrast-enhanced sonography, they were not blinded to the fact that an injury had been identified on CT. Even so, in only 50% of the cases was an injury identified on non-contrast-enhanced sonography. This rate is not much greater than the 41% previously reported in the literature [6, 7]. The second limitation is that, unfortunately, not all CT planes could be exactly reproduced by sonography because of the overlying ribs. Third, this series is limited in the numbers of injuries. Furthermore, specificity could not be determined because only CT images that showed injuries were included. Finally, surgical correlation is lacking, but in most series, as in this one, CT is considered the gold standard.

In conclusion, contrast-enhanced sonography performed better than non-contrast-enhanced sonography for the detection of solid organ injuries. CT is the gold standard in the evaluation of patients with blunt abdominal trauma, and it remains the imaging study of choice in patients who are hemodynamically stable. Non-contrast-enhanced sonography continues to have an important role in the triage of patients with blunt abdominal trauma who are not hemodynamically stable and cannot undergo CT. As proposed by Miele et al. [13] and Catalano et al. [14], there may be a future role for contrast-enhanced sonography in initial evaluation of patients with blunt abdominal trauma. Certainly, contrast-enhanced sonography can be used in the follow-up of hospitalized patients with a known solid organ injury who are managed conservatively and who cannot be easily moved to the CT suite. Contrast-enhanced sonography could be used to help detect any changes in the injury and spare the patient further radiation exposure.


References
Top
Abstract
Introduction
Subjects and Methods
Results
Discussion
References
 

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