Contrast-enhanced ultrasound: beyond the liver

Emergency radiology

US has a relevant role in the initial assessment of non-traumatic emergencies of the abdomen, sometimes being conclusive and some other times for selecting the patients for further imaging with CT. Injection of a contrast medium may give to the radiologist additional information to that obtained at baseline US and Doppler examination, since real-time, contrast-enhanced US (CEUS) may allow observing findings in the abdomen not recognizable at baseline US or even at color Doppler imaging. Extravascular use of microbubbles may also be useful in clinical practice to rapidly solve a number of unclear aspects. CEUS has a number of distinct advantages in acute patients, including its quickness, low invasiveness, and its possible bedside use. The information based on contrast enhancement is useful for initial diagnosis, therapeutic decision making, and follow-up of the critically ill patients. The purpose of this review is to illustrate the possibilities and limitations of abdominal CEUS in the acute setting, with special emphasis on the detection and characterization of acute inflammatory processes, infarcts, and hemorrhages.

Bedside contrast-enhanced sonography of critically ill patients

The transfer of critically ill patients to the radiology department is, in itself, potentially dangerous, so radiologists are frequently asked to perform bedside sonographic studies in the intensive care unit, surgical or medical department, sterile area, and operating room. In these circumstances, injection of a contrast agent may give the radiologist relevant additional information, which is useful for diagnosis and for better therapeutic management of these critically ill patients. Contrast-enhanced sonography may allow detection of findings not recognizable on baseline sonography or even color Doppler imaging. In this pictorial essay, we highlight the value of real-time contrast-enhanced sonography when performed at the bedside in critically ill patients.

Splenic hemangiomas: contrast-enhanced sonographic findings

OBJECTIVES

The purpose of this study was to illustrate the baseline appearance and enhancement patterns of splenic hemangiomas on contrast-enhanced sonography.

METHODS

Two experienced radiologists retrospectively reviewed by consensus baseline and contrast-enhanced sonographic examinations of 27 patients (14 women and 13 men; mean age, 58.7 years) with 27 splenic hemangiomas (mean size, 2 cm) confirmed by splenectomy, biopsy, computed tomography, and magnetic resonance imaging and follow-up.

RESULTS

On baseline sonography, 77.8% of the lesions showed a homogeneous echo texture that was mainly hyperechoic. Color Doppler imaging did not show any signal in 81.5% of the cases. After contrast agent injection, 59.2% of the splenic hemangiomas showed different degrees of contrast enhancement in the arterial phase followed by isoenhancement in the late parenchymal phase. Among these, 2 hemangiomas showed peripheral globular enhancement in the arterial phase, followed by progressive centripetal fill-in. In 29.6% of the cases, some degree of contrast enhancement was appreciable, but the hemangiomas remained substantially hypoechoic throughout the contrast-enhanced sonographic examinations, whereas in 11.1%, the combination of contrast enhancement in the arterial phase followed by wash-out in the late parenchymal phase was evident.

CONCLUSIONS

Isoechogenicity to spleen parenchyma in all phases is the most frequent typical enhancement pattern of splenic hemangiomas observed on contrast-enhanced sonography. Nevertheless, these lesions may show atypical contrast enhancement patterns; therefore, further assessment with cross-sectional techniques is needed.

Analysis of achilles tendon vascularity with second-generation contrast-enhanced ultrasound

PURPOSE

To compare morphological, power Doppler, and contrast-enhanced ultrasound (CEUS) features of the Achilles tendon between asymptomatic athletes and athletes who had undergone surgical repair of a previous rupture.

METHODS

Twenty-four athletes were divided in two groups (A and B). Group A included 14 patients with a median age of 32 years (range 27 to 47 years) who had undergone surgical repair for unilateral Achilles tendon rupture. Group B (control group) included 10 subjects with a median age of 34 years (range 27 to 40 years) with no previous or present history of tendinopathy. All patients were evaluated with ultrasound, power Doppler, and CEUS with second-generation contrast agent. We studied the uninjured Achilles tendon in athletes of group A and either the left or the right Achilles tendon of the athletes in group B.

RESULTS

CEUS showed a significantly greater ability to detect a greater number of vascular spots within the uninjured tendon of group A compared to group B (<0.05).

CONCLUSIONS

In athletes who had suffered a tear of an Achilles tendon, CEUS detected small vessels that were not identified by power Doppler ultrasound in the uninjured contralateral Achilles tendon. CEUS is useful to evaluate vascularity not detected by other imaging techniques. Vascularity in the uninjured tendon seems to be increased in patients who had a previous rupture.

CEUS in abdominal trauma: multi-center study

The objective of this study was to evaluate the concordance of US and contrast-enhanced US (CEUS) with CT in the assessment of solid organ injury following blunt trauma. Patients underwent complete US examination, including free fluid search and solid organ analysis. CEUS followed, using low-mechanical index techniques and SonoVue. CT was performed within 1 h. Among 156 enrolled patients, 91 had one or more abnormalities (n = 107) at CT: 26 renal, 38 liver, 43 spleen. Sensitivity, specificity, and accuracy for renal trauma at baseline US were 36%, 98%, and 88%, respectively, after CEUS values increased to 69%, 99%, and 94%. For liver baseline US values were 68%, 97%, and 90%; after CEUS were 84%, 99%, and 96%. For spleen, results were 77%, 96%, and 91% at baseline US and 93%, 99%, and 97% after CEUS. Per patient evaluation gave the following results in terms of sensitivity, specificity and accuracy: 79%, 82%, 80% at baseline US; 94%, 89%, and 92% following CEUS. CEUS is more sensitive than US in the detection of solid organ injury, potentially reducing the need for further imaging. False negatives from CEUS are due to minor injuries, without relevant consequences for patient management and prognosis.

Active abdominal bleeding: contrast-enhanced sonography

Active contrast medium extravasation is a recognized and important angiographic and computed tomographic (CT) sign of bleeding. It is an indicator of active, ongoing, and potentially life-threatening hemorrhage and, hence, of the need for an immediate surgical or interventional treatment. Sonography (US) is frequently used as the first imaging option for screening patients with traumatic and nontraumatic abdominal emergencies. Owing to the current possibilities of low-mechanical index, real-time, contrast-specific systems, it is now possible to detect a contrast leakage by using US. This finding opens new possibilities in the assessment and management of several abdominal emergencies, including trauma (initial workup and monitoring), spontaneous hematomas, and rupture of aneurysms or masses. This article describes the technique, findings, possibilities, and limitations of contrast-enhanced US in the evaluation of active abdominal bleeding.