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

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1 McGahan et al. ontrast- Enhanced of lunt bdominal Trauma bdominal Imaging Original Research M E D E N T U R I L I M G I N G John P. McGahan 1 Stephanie Horton 1 Eugenio O. Gerscovich 1 Marijo Gillen 1 John R. Richards Michael S. ronan 1 John M. rock 1 Felix attistella 3 David H. Wisner 3 James F. Holmes JR 006; 187: X/06/ merican Roentgen Ray Society Y O F McGahan JP, Horton S, Gerscovich EO, et al. Keywords: abdominal imaging, contrast media, sonography, trauma DOI:10.14/JR Received June 3, 005; accepted after revision July, 005. Supported by an internally funded grant from the Department of Radiology, University of alifornia, Davis. 1 Department of Radiology, University of alifornia, Davis School of Medicine, U Davis Medical enter, 4860 Y St., Ste. 3100, Sacramento, ddress correspondence to J. P. McGahan (john.mcgahan@ucdmc.ucdavis.edu). Department of Emergency Medicine, University of alifornia, Davis School of Medicine, U Davis Medical enter, Sacramento, Department of Surgery, University of alifornia, Davis School of Medicine, U Davis Medical enter, Sacramento, ppearance of Solid Organ Injury with ontrast-enhanced in lunt bdominal Trauma: Preliminary Experience OJETIVE. 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. SUJETS ND METHODS. This prospective study involved identifying hepatic, splenic, and renal injuries on contrast-enhanced T. fter 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 injuries, whereas contrast-enhanced sonography depicted 0 (91%) of injuries. The average grade for conspicuity of injuries was increased from 0.67 to.33 for spleen injuries and from 1.0 to. 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. ONLUSION. ontrast-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. he main focus of sonography for T 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 (FST) []. 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]. lthough FST 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]. lthough 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 FST was 41% [6, 7]. 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 [1 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 T. Subjects and Methods This prospective study was conducted from June 004 through March of 005 and was approved by our institutional review board. Written informed 658 JR:187, September 006

2 ontrast-enhanced of lunt bdominal Trauma TLE 1: merican ssociation for the Surgery of Trauma (ST) Scale and Modified Scale for lassification of Liver Injuries ST Grade Injury Injury Description I II Subcapsular, < 10% surface apsular tear, < 1 cm 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 T and were not candidates for immediate surgery. ll patients underwent dedicated contrast-enhanced T (LightSpeed 16, GE Healthcare) of the abdomen and pelvis with IV contrast material ( ml of iohexol [Omnipaque 300, mersham Health]) injected at.5 ml/s. No oral contrast Subcapsular, 10 50% surface; intraparenchymal hematoma, < 10 cm in diameter 1 3 cm deep, < 10 cm long IS-90 Grade III Subcapsular, > 50% surface; intraparenchymal 3 hematoma, > 10 cm 3 > 3 cm parenchymal IV Parenchymal disruption involving 5 75% of hepatic lobe 4 V Vascular Parenchymal disruption involving > 75% of hepatic lobe Juxtahepatic venous injuries VI Vascular Hepatic avulsion 6 Note IS-90 = bbreviated Injury Scale, 1990 version. Modified and abbreviated from [15]. TLE : merican ssociation for the Surgery of Trauma (ST) Scale and Modified Scale for lassification of Liver Injuries ST Grade Injury Injury Description I II III Subcapsular, < 10% surface apsular tear, < 1 cm Subcapsular, 10 50% surface; intraparenchymal hematoma, < 5 cm 1 3 cm Subcapsular, > 50% surface; intraparenchymal hematoma, > 5 cm > 3 cm parenchymal material was administered. The technique used an automatic milliamperage setting from 00 to 440 m at 10 kv. Detector collimation was 1.5 mm, and scans were reconstructed at 5 mm every 5 mm. 5-minute delayed scan of the upper abdomen was obtained using a similar technique. Organ injuries detected on T were graded using a scale developed by the merican ssociation for the Surgery of Trauma for splenic, hepatic, and 5 5 IS-90 Grade IV producing devascularization (> 5% of spleen) 4 V Vascular ompletely shattered spleen Hilar vascular injury that devascularizes spleen 5 5 Note IS-90 = bbreviated Injury Scale, 1990 version. Modified and abbreviated from [15]. X = no specific grade. TLE 3: Visualization of Subcapsular s and Organ Injuries on ontrast-enhanced T, Non ontrast-enhanced, and ontrast-enhanced No. (%) of ases Detected on Injury Seen No. of ases Detected on T Non ontrast-enhanced ontrast-enhanced Spleen laceration 9 4 (44) 9 (100) Liver laceration 10 6 (60) 9 (90) Kidney laceration 3 1 (33) (66) Total no. of lacerations 11 (50) 0 (91) Subcapsular hematomas 11 4 (36) 11 (100) X 3 3 renal injuries [15 17]. modified and abbreviated version of this scale created by the Organ Injury Scaling ommittee of the merican ssociation for the Surgery of Trauma for liver and spleen injuries is presented in Tables 1 and ; for a more complete table and T modification of the tables, the reader is referred to references 15 through 17. Radiology faculty interpreting the T examinations notified the clinical coordinator when a patient had a solid organ injury detected on T. The clinical coordinator was blinded to the site of injury. different radiology faculty member not involved in interpreting the T examination and blinded to the site of the injury was notified to obtain informed consent. aseline sonography followed by contrastenhanced sonography was then performed. ll sonographic examinations were performed by the same sonographer who had more than years of experience with contrast-enhanced sonography. The radiologist who had obtained informed consent was present for the sonographic examinations. was always performed within 48 hours after the T examination. ll sonography examinations were performed on a Sequoia unit (Siemens-cuson); 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 for the contrast-enhanced sonography portion of the examination. For contrast enhancement, a 0.1-mL dose of SH U 508 (Definity, ristol-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 508 was injected, followed by imaging of the left upper quadrant of the abdomen for 3 4 minutes. In four patients, 0.-mL of SH U 508 was injected at one site because of inadequate contrast response in the organ of interest. ll injections were performed by one individual. ll video and still images were recorded for review on a workstation (Kinetics, Siemens-cuson). Only selected -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. 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 T, non contrast-enhanced sonography, and contrast-en- JR:187, September

3 McGahan et al. hanced sonography. The presence or absence of free fluid detected using T, 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 contrastenhanced sonography, contrast-enhanced sonography, and T. The scale used was adapted from atalano et al. [14], where 0 = not recognizable; 1 = low injury-to-parenchyma gradient; = medium injuryto-parenchyma gradient; and 3 = high injury-toparenchyma 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 injuries were intermediate in conspicuity on this scale. Grade 1 injuries were seen but were not as easily identified as grade injuries. The sonographic appearance of these injuries was described as hypoechoic, isoechoic, or hyperechoic. Results The results for T, non contrast-enhanced sonography, and contrast-enhanced sonography are reported in Table 3. T depicted free fluid in 10 of 0 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 0 patients as revealed on T. Eleven subcapsular hematomas of the liver or spleen were identified on T. Only four (36%) were seen on non contrast-enhanced sonography, whereas all 11 (100%) were seen Fig. 1 Splenic laceration with subcapsular hematoma in 46-year-old woman., T scan shows large splenic laceration with surrounding subcapsular hematoma., Longitudinal non contrast-enhanced sonogram shows central heterogeneous region (arrow) with normal-appearing spleen posteriorly and subcapsular hematoma anteriorly., Longitudinal contrast-enhanced sonogram shows that splenic tissue noted posteriorly appears perfused and echogenic. entral 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. on contrast-enhanced sonography (Fig. 1). There were no false-positive non contrastenhanced sonography or contrast-enhanced sonography examinations. Twenty-two solid organ injuries were detected in 0 patients on T. Non contrastenhanced sonography showed 11 (50%) of the injuries, whereas contrast-enhanced sonography showed 0 (91%) of the injuries. lassification 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.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 break- 660 JR:187, September 006

4 ontrast-enhanced of lunt bdominal Trauma TLE 4: Splenic Injury Severity ompared with Detection Rate on Non ontrast-enhanced and ontrast-enhanced Spleen on T ST lassification No. of ases Detected No. of ases Detected / Total No. of ases Non ontrast-enhanced ontrast-enhanced I 0 / / II 1 / / III 3 1 / 3 3 / 3 IV / / V Total 9 4 / 9 9 / 9 Note ST = merican ssociation for the Surgery of Trauma. TLE 5: Liver Injury Severity ompared with Detection Rate on Non ontrast-enhanced and ontrast-enhanced Liver on T ST lassification No. of ases Detected No. of ases Detected / Total No. of ases Non ontrast-enhanced ontrast-enhanced I II 3 0 / 3 / 3 III / / IV 5 4 / 5 5 / 5 V Total 10 6 / 10 9 / 10 Note ST = merican ssociation for the Surgery of Trauma. TLE 6: Spleen Injuries: omparison of onspicuity on T, Non ontrast Enhanced, and ontrast-enhanced No. of Spleen Injuries with onspicuity Score of verage onspicuity of Injury on onspicuity Score Non contrast-enhanced sonography ontrast-enhanced sonography 5.33 T Note 0 = not recognizable, 1 = low injury-to-parenchyma gradient, = medium injury-to-parenchyma gradient, 3 = high injury-to-parenchyma gradient. TLE 7: Liver Injuries: omparison of onspicuity on T, Non ontrast Enhanced, and ontrast-enhanced No. of Spleen Injuries with onspicuity Score of verage onspicuity of Injury on onspicuity Score Non contrast-enhanced sonography ontrast-enhanced sonography T Note 0 = not recognizable, 1 = low injury-to-parenchyma gradient, = medium injury-to-parenchyma gradient, 3 = high injury-to-parenchyma gradient. down 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.33 for contrast-enhanced sonography. With regard to liver injuries, the conspicuity scale increased from 1.0 for non contrast-enhanced sonography to. for contrast-enhanced sonography. Injuries that were not identified on either non contrastenhanced sonography or contrast-enhanced sonography were given a score of 0. 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. n avulsed kidney was not seen on non contrast-enhanced sonography, whereas it was identified on contrast-enhanced sonography. 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 (Fig. 1). 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. ll injuries identified on contrast-enhanced sonography were hypoechoic compared with surrounding parenchyma (Figs. 1 and ). reas of enhancement of the splenic parenchyma could be observed within stellate splenic lacerations and were similar to the appearance on T (Fig. 3). 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 T plane could not be reproduced exactly with sonography because of overlying ribs. In most patients with liver injuries, there was correlation between T, non contrastenhanced sonography, and contrast-enhanced sonography. Most commonly a hypodense region within the liver detected on T 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 contrastenhanced sonography, whereas another injury was hyperechoic with a central hypoechoic region on non contrast-enhanced sonography. This was then followed by con- JR:187, September

5 McGahan et al. trast-enhanced sonography showing a hypoechoic region in six cases (Fig. 4). 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. 5 and 6). However, within the center of the hyperechoic region, a linear hypoechoic region was identified using contrast-enhanced sonography in three cases (Figs. 5 and 6). For some of these injuries, there were minor discrepancies between the size of the injury on non contrast-enhanced sonography, contrast-enhanced sonography, and T. n example of this discrepancy is shown in Figure 5 in which a presumed large liver laceration is detected on T. Non contrast-enhanced sonography shows an echogenic area roughly corresponding to the T finding. However, contrast-enhanced sonography depicts a smaller hypoechoic region centrally Fig. Splenic laceration in 0-year-old woman., T scan of abdomen shows well-demarcated splenic laceration (arrow)., 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 T. Fig. 3 Splenic laceration in 3-year-old woman., T scan of abdomen shows regions of normal enhancing splenic tissue (arrow) within splenic laceration., ased 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 T with areas within laceration that were perfused splenic tissue (arrow). 66 JR:187, September 006

6 ontrast-enhanced of lunt bdominal Trauma surrounded by an isoechoic to hyperechoic region that appeared to enhance on contrast-enhanced sonography. Discussion 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 T was used to establish the sensitivity of sonography. When FST was compared with T by Fig. 4 Liver laceration in 46-year-old woman., T scan of liver shows fairly well-demarcated region of decreased density within liver (arrow) corresponding to area of injury., Longitudinal non contrast-enhanced sonogram was interpreted as normal., xial contrast-enhanced sonogram shows central hypoechoic region (straight arrow). Hypoechoic region was surrounded by perfused hyperechoic region (curved arrow). McGahan et al. [7], FST depicted free fluid in 63% of the patients with solid organ injuries or free fluid identified on T. ecause free fluid has been used by most authors as the sole criterion for a positive FST, contained parenchymal injuries have been shown to be missed by this approach [7, 11]. There have been few reports of FST being used to detect solid organ injury. oth McGahan et al. [7] and Rothlin et al. [6] showed a detection rate of solid organ injuries with FST of 41%, but most researchers have reported a low detection rate or have not attempted to use FST to look for solid organ injury. oth groups of authors used a modified FST 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 atalano et al. [14] who described it as the full potential sonographic technique, instead of the minimized FST 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 [1 14]. For the evaluation of splenic trauma, atalano et al. [1] showed that avascular splenic areas that were not visualized on non contrastenhanced sonography were well seen on contrast-enhanced sonography and T. 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 T should be used in patients with more severe trauma. atalano et al. JR:187, September

7 McGahan et al. [14] reviewed the use of contrast-enhanced sonography in the evaluation of liver trauma in 1 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, atalano 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 T. The initial or admission FST examination was compared with a non contrastenhanced sonography control examination followed by contrast-enhanced sonography. They found the detection rate of solid organ injuries for the admission FST examination, non contrastenhanced sonography, and contrast-enhanced sonography was 40%, 57%, and 80%, respectively. lthough 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 T in hemodynamically stable trauma patients but that it may be helpful for detecting delayed findings such as a splenic pseudoaneurysm. Fig. 5 Liver laceration in 1-year-old woman., T scan of liver shows large irregular liver injury., Longitudinal non contrast-enhanced sonogram of liver shows fairly large echogenic region of liver (arrow) that corresponds to site of injury identified on T., 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). lso note hematoma in hepatorenal fossa (straight arrow) that was not identified on initial non contrast-enhanced sonogram. 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. s documented by other researchers [0 ], 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. s 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 664 JR:187, September 006

8 ontrast-enhanced of lunt bdominal Trauma non contrast-enhanced sonography and became more conspicuous on contrast-enhanced sonography (Figs. and 3). Furthermore, regions of normal, perfused spleen could be observed within the anatomic site of injury (Fig. 3). This pattern occurred with stellate splenic lacerations and has not, to our knowledge, been previously reported using contrastenhanced sonography. Not all spleen lacerations are completely linear or wedge-shaped; instead, Fig. 6 Liver laceration in 3-year-old man., T scan of abdomen shows large irregular liver injury and subcapsular hematoma surrounding liver and spleen., Longitudinal non contrast-enhanced sonogram shows large heterogeneous hyperechoic region (arrow) noted in liver in corresponding area of injury identified on T., ontrast-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. D, ontrast-enhanced sonogram obtained in slightly different area shows there is central hypoechoic echoic region (arrow) with surrounding perfused echogenic area (arrowhead). they may be more complex or stellate, with normal areas of enhancing parenchyma seen within the region of laceration. Liver injuries were often not seen on non contrast-enhanced sonography and appeared hypoechoic on contrast-enhanced sonography [14] (Fig. 4). In some cases, these liver injuries appeared quite large on non contrast-enhanced sonography and T, but on contrast-enhanced sonography the periphery of the injured area stayed hyperechoic and the microbubbles were visualized. hypoechoic region was localized more centrally and was not perfused with administration of contrast material. lthough 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 D JR:187, September

9 McGahan et al. (Figs. 5 and 6). 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. ontrast-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]. 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 T in the characterization of a solid organ injury and subsequent triage to further intervention. lthough we did not detect any pseudoaneurysms in our series, both Poletti et al. [9] and atalano et al. [1] 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 (Fig. 5). Our study has some limitations. lthough 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 T. 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 T 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 T images that showed injuries were included. Finally, surgical correlation is lacking, but in most series, as in this one, T is considered the gold standard. In conclusion, contrast-enhanced sonography performed better than non contrastenhanced sonography for the detection of solid organ injuries. T 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 T. s proposed by Miele et al. [13] and atalano et al. [14], there may be a future role for contrastenhanced sonography in initial evaluation of patients with blunt abdominal trauma. ertainly, 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 T suite. ontrast-enhanced sonography could be used to help detect any changes in the injury and spare the patient further radiation exposure. References 1. Jehle D, Guarino J, Karamanoukian H. Emergency department in the evaluation of blunt trauma. m J Emerg Med 1993; 11: McGahan JP, Richards J, Gillen M. The focused abdominal sonography for trauma scan: pearls and pitfalls. J Ultrasound Med 00; 1: Hoffmann R, Nerlich M, Muggia-Sullam M, et al. lunt abdominal trauma in cases of multiple trauma evaluated by sonography: a prospective analysis of 91 patients. J Trauma 199; 3: Lentz K, McKenney MG, Nunez D Jr, Martin L. 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