Contrast-enhanced ultrasound in abdominal trauma

140 Review article Contrast-enhanced ultrasound in abdominal trauma Asim Afaq, Chris Harvey, Zaid Aldin, Edward Leen and David Cosgrove Increasing evidence supports a role for contrast-enhanced ultrasound in the assessment of blunt abdominal trauma. Accurate definition of organ injury can be demonstrated, as well as extension to solid organ capsule and even vascular injury. Low-dose contrast is needed for renal imaging, to avoid obscuration of deeper structures from intense cortical enhancement. The liver should be evaluated in the arterial phase for active bleeding and in the late phase for lacerations. The spleen is best assessed in the delayed phase, thereby limiting misinterpretation of early heterogeneous contrast uptake. Typical sonographic features of traumatic injuries of the solid abdominal organs are described. Although contrast-enhanced computed tomography is the gold standard modality for imaging abdominal organ traumatic injury, contrast-enhanced Aim To critically review the use of contrast-enhanced ultrasound (CEUS) in abdominal trauma and to illustrate the typical sonographic features of traumatic injuries of the solid abdominal organs. Background In recent years, the nonsurgical approach to manage blunt abdominal trauma has increased significantly. This accounts for 70–90% of cases of hepatic injury and for approximately 60% of patients with splenic injury, stable enough for imaging assessment. As a result, the number of cases of complications, which are indicators of failure of nonsurgical management also have increased [1]. These include cases of active bleeding, pseudoaneurysms, arteriovenous fistulas and haemorrhage due to delayed rupture [1–3]. Contrast-enhanced computed tomography (CECT) is the gold standard for imaging cases of blunt abdominal trauma [4]. This modality allows assessment of soft tissue and bone injury and has the capacity to search for complications of nonsurgical management. Ultrasound (US) is frequently used as a first-line measure and as a focused assessment with sonography for trauma (FAST). US can expedite surgical management in those cases in which free intraperitoneal fluid is identified. Although highly sensitive to free fluid, quick and portable these studies can lead to false negative results, including not detecting those organ injuries in which there is no significant free fluid. False positive results from FAST studies may occur in cases in which the fluid detected is Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s website (www.euro-emergencymed.com). 0969-9546 c 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins ultrasound has developed a role in the emergency setting, particularly in low-energy injuries and in follow-up of traumatic injuries. European Journal of Emergency Medicine 19:140–145 c 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins. European Journal of Emergency Medicine 2012, 19:140–145 Keywords: abdominal organ injury, contrast-enhanced ultrasound, trauma Imperial College Healthcare NHS Trust, London, UK. Correspondence to Dr Chris Harvey, Consultant Radiologist, Department of Imaging, Hammersmith Hospital. London W12 0HS, UK Tel: +44 0208 383 3389; fax: +44 0208 383 3121; e-mail: chris.harvey@imperial.nhs.uk Received 3 March 2011 Accepted 13 May 2011 not related to traumatic pathology, such as in patients with ascites, and in those with free fluid associated with ovulation [5]. A number of techniques have been adopted to improve US assessment of abdominal injury. These include highresolution transducers, tissue harmonic imaging, catheter balloon distension and power Doppler to identify vascular defects. Increasing evidence supports a role for CEUS in the assessment of blunt abdominal trauma [6,7]. Accurate definition of organ injury can be demonstrated, as well as extension to solid organ capsule and even vascular injury. Contrast medium pooling, and extravasation within the haematoma or the abdominal cavity are particularly useful features to help us to decide which patients are surgical candidates [6]. Training and how to conduct the study In the UK, the current Royal College of Radiologists’ recommendations for medical and surgical specialities performing CEUS studies are ‘level 3 training’ [8]. This is an advanced level of practice that would equate to a consultant radiologist with subspecialty practice with a significant commitment to US [8]. At an advanced level of practice, the European Federation of Societies for Ultrasound in Medicine and Biology states that it is desirable to be able to give off-line second opinions on examinations by less experienced CEUS practitioners, to perform technically difficult and specialized CEUS examinations, to perform advanced CEUS-guided invasive procedures, to conduct substantial research in CEUS, to teach CEUS at all levels and to be aware of and to pursue developments in CEUS [9]. DOI: 10.1097/MEJ.0b013e328348c980 Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. Contrast-enhanced ultrasound in abdominal trauma Afaq et al. 141 Many other European countries have similar required levels of training. US contrast agents are becoming more widely used and trauma applications are covered in the study by Claudon et al. [10], which is due to be updated later in 2011. CEUS is recommended as an extension of FAST scanning. In our institute, CEUS studies are usually performed by sonographers and registrars with a consultant present. Microbubble-specific modes are available on all high-end US scanners. These commonly consist of a split-screen display with one screen depicting a bubble-specific signal and the other screen being an altered B-mode (standard unenhanced) image to allow tracking of a lesion. A few mobile US scanners have contrast modes and the image quality continues to improve. The cost of a vial of contrast agent is approximately 60 h, although this can be divided for at least two applications. CEUS is performed immediately after B-mode (standard unenhanced) US. At this stage, the operator may already have some idea of the location of organ injury. With the monitor divided into B mode and CEUS modes, a 2.4-ml bolus of second-generation blood pool agent (e.g., SonoVue, Bracco, Italy) is injected through peripheral intravenous access. The rate of contrast uptake varies among the organs, which makes the kidneys the ideal first target to assess. A1/4–1/2 of a normal dose should be used for evaluation of the kidneys. This is to avoid obscuration of deeper renal structures due to intense cortical enhancement. The liver should be evaluated in the arterial phase for active bleeding and in the late phase for lacerations. The spleen is best assessed in a delayed phase, thereby limiting misinterpretation of early heterogeneous contrast uptake and allowing optimal evaluation of lacerations, which are best seen after 40 s. The following are examples of CEUS studies in blunt abdominal injuries (contrast pulse sequencing, Siemens AG, Erlangen, Germany). A large, poorly defined area of heterogenous echogenicity measuring up to 10 cm (demarcated by calipers) in maximal diameter, occupies much of the right lobe of the liver. No vascularity was present in this region and the history together with the B-mode findings were in keeping with haemorrhage into the liver parenchyma (Fig. 1a). Scanned in a slightly different plane to Fig. 1a, part of the same abnormality is now evaluated with CEUS, with an image on the left, taken 2 min 25 s after injection of 2.4 ml of SonoVue contrast. This shows considerably better delineation of the site of the bleeding (larger nonenhancing area demarcated by calipers, with two smaller areas shown by white arrows on left image) with the B-mode image (right) (Fig. 1b). Lacerations are best seen in the late phase, whereas the arterial phase is best for active bleeding (Fig. 2). Fig. 1 The assessment takes on average not more than 6 min in total, but in case if there are areas that require a longer time to assess, a second bolus of 2.4 ml of SonoVue contrast can be given if needed without any additional risk. The minimum time, however, is comparable with the total time (door to door) of an emergency computed tomography (CT) study [6]. Imaging findings Traumatic injuries can appear similar in different solid abdominal organs. Contusions that are hypoechoic on B-mode US are often better delineated on CEUS, as the parenchyma is enhanced. Lacerations can appear as a hypoechoic linear deficiency, usually orientated perpendicular to the organ surface. Haematomas are represented by nonenhancing areas. Infarcts also can be identified, which may not be demonstrable on conventional B-mode US [7]. (a) and (b) Intraparenchymal hepatic haemorrhage. Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. 142 European Journal of Emergency Medicine 2012, Vol 19 No 3 Fig. 2 Subcapsular liver laceration. The image on the right is the CEUS study, 17 s after injection of 2.4 ml of SonoVue contrast. The white arrow indicates a thin, wedge-shaped area of filling defect extending from the capsule in segment 8 of the liver, which is in keeping with a laceration. The abnormality is much more difficult to identify on the B-mode US image (see white arrow on the image on the right). (Fig. 3 – Video clip, Supplemental Digital Content 1, http://links. lww.com/EJEM/A8). Figure 4: The B-mode image (white arrow on the image on the right) demonstrates a relatively poorly defined area of reduced echogenicity in the left lobe of the liver, measuring 1.9  1.3 cm. The CEUS image taken at 34 s postinjection of 2.4 ml of SonoVue contrast shows marked improvement in definition in the margins of the lesions (white arrow on the image on the left). The lesion is demonstrated as a nonenhancing area, surrounded by normally enhancing liver parenchyma. The kidneys should be scanned for up to 2 min. Most injuries involve the cortex. In the case below, the images on the right are taken at 20 and 49 s postinjection of 2.4 ml of SonoVue contrast, showing a well-defined area of nonenhancement in the renal cortex at the midpole of the left kidney (white arrow). This is surrounded by normally enhancing renal parenchyma. Figure 5: The images on the right are of the CECT study performed on the same day showing a well-defined linear area of low attenuation in the left renal cortex, corresponding to laceration shown on the CEUS images (white arrow, upper right image) and showing a haematoma surrounding the lower pole of the left kidney (white arrow, lower right image). Perhaps, one of the most exciting uses over recent years has been the ability of CEUS to detect active bleeding. Catalano et al. [11] were able to demonstrate active extravasation as a round, hyperechoic pool or as a fountain-like hyperechoic jet in patients with hepatic, splenic and renal injuries, as well as in cases of abdominal aortic aneurysm rupture, splenic angiosarcoma rupture, postsurgical bleeding after abdominal aortic aneurysm repair and postsplenectomy bleeding. Considering the recently published studies on CEUS, Valentino et al. [12] found 84 lesions using CT in 133 patients with abdominal trauma. These were 48 splenic, 21 hepatic, 13 adrenal and two pancreatic. B-mode US detected fluid or parenchymal alterations in 59 of 84 patients, whereas CEUS detected 81 of 84 of the traumatic lesions and ruled out traumatic lesions in 48 of 49 patients with a negative CT. Thorelius [13] found that CEUS was able to replace CT in patients with mild-to-moderate blunt abdominal Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. Contrast-enhanced ultrasound in abdominal trauma Afaq et al. 143 Fig. 4 A small hepatic contusion. Fig. 5 Renal trauma. CPS, contrast pulse sequencing. Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. 144 European Journal of Emergency Medicine 2012, Vol 19 No 3 trauma to one flank and that the technique was able to detect very thin lacerations on the parenchyma of the abdominal organs. Valentino et al. [6] also studied a group of paediatric patients with abdominal trauma. CECT found 14 solid organ injuries in 12 patients in a series of 27 consecutive children, and CEUS found 13 of the 14 lesions. Conventional US found free fluid, parenchymal injury or both in eight of the 12 patients with positive CT. Clevert et al. [14] showed that CEUS identified each of the 18 solid organ injuries as demonstrated on CECT in 78 patients, whereas US alone detected 15 of the injuries. In 156 patients with 107 traumatic abdominal abnormalities, Catalano et al. [7] confirmed that CEUS was more sensitive than US. This group found sensitivity, specificity and accuracy to improve from 79, 82 and 80% to 94, 89 and 92%. False negatives were also demonstrated; however, minor injuries without relevant consequences to either patient management or prognosis. Manetta et al. [15] successfully followed up 11 patients who were conservatively managed for abdominal trauma, until resolution on the initially identified lesions, found on both CEUS and CT. Tang et al. [16] showed a high level of concordance between CEUS and CECT in induced hepatic and splenic traumas in anaesthetized dogs. In a separate study, Tang et al. [17] also successfully demonstrated transcutaneous haemostatic injection of induced hepatic injuries using contrast US guidance, suggesting an alternative technique in the management of hepatic haemorrhage. More recently, Li et al. [18] showed that CEUS-guided percutaneous injection may provide a safe, feasible and effective therapy for blunt splenic trauma. Conclusion The precise evaluation of traumatic solid abdominal lesions is imperative for appropriate management. The use of second-generation contrast agents has been shown to improve the definition of lesion, increasing the accuracy of size determination and also of lesion margins and relationships with the organ capsule and vessels. This information directly influences management decisions, most critically, if the patient has to undergo surgical or nonsurgical management. The knowledge of imaging signs and the relationship with prognosis has been gained from studies on the role of CT in trauma [19]. The fact that CEUS is relatively of low cost and quickly performed at the bedside may allow a role for the assessment of isolated moderate abdominal trauma cases. Multiple groups have confirmed the improved sensitivity, specificity and accuracy of CEUS when compared with US [20,21]. These parameters are almost comparable to CECT. The assessment of active extravasation adds a whole new dimension on the usefulness of this technique, and animal models have suggested that the CEUS combined with percutaneous haemostatic agents may be an exciting future treatment of hepatic haemorrhage. Although CECT will not be replaced by CEUS, there are a number of situations in which it is particularly useful. Current guidelines view CEUS as an ‘off-label’ indication in trauma, suitable for the study of isolated low, but not high-energy injuries [10]. Further uses include clarification of CT studies, which may have been suboptimal from artefact/patient movement, and also in the follow-up of trauma. The role in follow-up would reduce the number of CT studies required in groups in which ionizing radiation dose is of particular importance, including children and pregnant women, as well as those patients who are at an increased risk of adverse effects from iodinated contrast. Acknowledgements Conflicts of interest There are no conflicts of interest. References 1 2 3 4 5 6 7 8 9 10 11 12 13 Carrillo EH, Wohltmann C, Richardson JD, Polk HC Jr. Evolution in the treatment of complex blunt liver injuries. Curr Probl Surg 2001; 38: 1–60. Galvan DA, Peitzman AB. Failure of nonoperative management of abdominal solid organ injuries. Curr Opin Crit Care 2006; 12:590–594. Becker CD, Mentha G, Terrier F. Blunt abdominal trauma in adults: Role of CT in the diagnosis and management of visceral injuries. Part 1: Liver and spleen. Eur Radiol 1998; 8:553–562. Federie MP, Courcoulas AP, Powell M, Ferris JV, Peitzman AB. Blunt splenic injury in adults: clinical and CT criteria for management, with emphasis on active extravasation. Radiology 1998; 206:137–142. Soudack M, Epelman M, Maor R, Hayari L, Shoshani G, Heyman-Reiss A, et al. Experience with focused abdominal sonography for trauma (FAST) in 313 pediatric patients. J Clin Ultrasound 2004; 32:53–61. Valentino M, Serra C, Pavlica P, Barozzi L. Blunt abdominal trauma: Diagnostic performance of contrast enhanced US in children – Initial experience. Radiology 2008; 246:903–909. Catalano O, Aiani L, Barozzi L, Bokor D, De Marchi A, Faletti C, et al. CEUS in abdominal trauma: multicenter study. Abdom Imaging 2009; 34:225–234. Ultrasound Training Recommendations for Medical and Surgical Specialties. The Royal College of Radiologists 2005. http://www.rcr.ac.uk/docs/ radiology/pdf/ultrasound.pdf. [Accessed 30 April 2011]. European Federation of Societies for Ultrasound in Medicine and Biology. Minimum Traiing Requirements for the Practice of Ultrasound in Europe. Appendix 14. Contrast Enhanced Ultrasound 2010. http://www.efsumb. org/guidelines/Appendix%2014%20Minimum%20Training%20CEUS %202010.pdf. [Accessed 30 April 2011]. Claudon M, Cosgrove D, Albrecht T, Bolondi L, Bosio M, Calliada F, et al. Guidelines and good clinical practice recommendations for contrast enhanced ultrasound (CEUS)-update 2008. Ultraschall Med 2008; 29: 28–44. Catalano O, Cusati B, Nunziata A, Siani A. Active abdominal bleeding: contrast enhanced sonography. Abdom Imaging 2006; 31:9–16. Valentino M, Ansaloni L, Catena F, Pavlica P, Pinna AD, Barozzi L. Contrastenhanced ultrasonography in blunt abdominal trauma: considerations after 5 years of experience. Radiol Med 2009; 114:1080–1093. Thorelius L. Emergency real-time contrast-enhanced ultrasonography for detection of solid organ injuries. Eur Radiol 2007; 17 (Suppl 6): F107–F111. Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. Contrast-enhanced ultrasound in abdominal trauma Afaq et al. 145 14 Clevert DA, Weckbach S, Minaifar N, Clevert DA, Stickel M, Reiser M. Contrast-enhanced ultrasound versus MS-CT in blunt abdominal trauma. Clin Haemorheol Microcirc 2008; 39:155–169. 15 Manetta R, Pistoia ML, Bultrini C, Stavroulis E, Di Cesare E, Masciocchi C. Ultrasound enhanced with sulphur-hexafluoride-filled microbubbles agent (SonoVue) in the follow up of mild liver and spleen trauma. Radiol Med 2009; 114:771–779. 16 Tang J, Li W, Lv F, Zhang H, Zhang L, Wang Y, et al. Comparison of grayscale contrast-enhanced ultrasonography with contrast-enhanced computed tomography in different grading of blunt hepatic and splenic trauma: an animal experiment. Ultrasound Med Biol 2009; 35:566–575. 17 Tang J, Lv F, Li W, Zhang H, Luo Y, An L, et al. Contrast-enhanced sonographic guidance for local injection of a hemostatic agent for management of blunt hepatic hemorrhage: a canine study. AJR Am J Roentgenol 2008; 191:W107–W111. 18 19 20 21 Li W, Tang J, Lv F, Zhang H, Zhang S, An L. Effectiveness and safety of CEUS-guided haemostatic injection for blunt splenic trauma: an animal experiment. Radiol Med 2010; 115:1080–1086. Mirvis SE, Whitthey NO, Vainwright JR, Gens DR. Blunt hepatic trauma in adults: CT base classification and correlation with prognosis and treatment. Radiology 1989; 171:27–32. Seitz K, Strobel D, Bernatik T, Blank W, Friedrich-Rust M, Herbay A. Contrast-enhanced ultrasound (CEUS) for the characterization of focal liver lesions-prospective comparison in clinical practice: CEUS versus CT (DEGUM multicenter trial). Ultraschall Med 2009; 30: 383–389. Trillaud H, Bruel JM, Valette PJ, Vilgrain V, Schmutz G, Oyen R, et al. Characterization of focal liver lesions with SonoVue-enhanced sonography: international multicenter-study in comparison to CT and MRI. World J Gastroenterol 2009; 15:3748–3756. Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.