Differentiation of benign from malignant focal splenic lesions using sulfur hexafluoride-filled microbubble contrast-enhanced pulse-inversion sonography. AJR Am J Roentgenol. 2009;193:709-721. [PMID: 19696284 DOI: 10.2214/ajr.07.3988]

Diagnostic performance of different imaging modalities for splenic malignancies: A comparative meta-analysis

Background and objectives

The spleen hosts both benign and malignant lesions. Despite multiple imaging modalities, the distinction between these lesions poses a diagnostic challenge, marked by varying diagnostic accuracy levels across methods. In this study, we aimed to evaluate and compare the diagnostic performance of various imaging techniques for detecting malignant splenic lesions.

Methods

Following PRISMA guidelines, we searched PubMed, Scopus, and Web of Sciences databases for studies evaluating imaging techniques in detecting malignant splenic lesions. Data extraction included diagnostic accuracy metrics, and methodological quality was assessed using QUADAS-2. Diagnostic Test Accuracy meta-analyses were conducted using R (version: 4.2.1). Subgroup analyses and meta-regression were performed to compare different modalities and clinical settings.

Results

Our study included 28 studies (pooled sample size: 2358), primarily using retrospective designs with histopathology as the reference standard. PET scan demonstrated the highest diagnostic accuracy (AUC: 92 %), demonstrating a sensitivity of 93 % (95 % CI: 80.4 % - 97.7 %) and a specificity of 82.8 % (95 % CI: 71.1 % - 90.4 %). Contrast-enhanced ultrasound (CEUS), Contrast-enhanced CT scan, and contrast-enhanced MRI also showed impressive performance with AUCs of 91.4 %, 90.9 %, and 85.3 %, respectively. Differences among these modalities were not statistically significant, but they outperformed non-contrast-enhanced methods. PET and CEUS exhibited higher specificity for lymphoma cases compared to studies including other malignancies.

Conclusion and clinical implications

Overall, PET emerges as the best modality for splenic malignancies, and CEUS and CE-MRI show promise as potential alternatives, notably due to their reduced radiation exposure. Further research is essential for precise malignancy differentiation.

B-Mode Ultrasound and Contrast-Enhanced Ultrasound for the Detection of Splenic Involvement in Hodgkin Lymphoma: A Retrospective Analysis of 112 Patients

PURPOSE

To assess splenic involvement using B-mode ultrasound (US) and contrast-enhanced ultrasound (CEUS) compared with standard imaging with contrast-enhanced computerized tomography (CT) / 18-fluorodeoxyglucose positron-emission tomography (PET-CT) in patients with Hodgkin lymphoma.

MATERIALS AND METHODS

Imaging data from 112 patients from 12/2003 to 10/2022 with histologically confirmed Hodgkin lymphoma during staging or relapse were analyzed for splenic lymphoma involvement. In all patients, standard imaging (CT/PET-CT), along with B-mode US and CEUS examinations, was performed. Evidence of focal splenic lesions (FSLs) found by imaging procedures was suggestive of splenic involvement. Follow-up imaging was performed in each patient after treatment, and treatment response indicated definitive splenic involvement.

RESULTS

40 patients (35.7%) were identified by imaging modalities as having splenic involvement, which was confirmed by response during follow-up. Standard CT/PET-CT imaging detected splenic involvement in 36/112 patients (32.1%). FSLs were detected with B-mode US in 38 patients (33.9%) and CEUS in 36 patients (32.1%). The sensitivity of standard imaging, B-mode US, and CEUS was 90%, 95%, and 90%, respectively.

CONCLUSION

B-mode US examination is a diagnostic method used in addition to standard imaging for the detection of splenic involvement in Hodgkin lymphoma. CEUS does not provide additional benefit compared to B-mode US and the standard reference procedure.

Acoustic Radiation Force Impulse (ARFI) Elastography of Focal Splenic Lesions: Feasibility and Diagnostic Potential

PURPOSE

Nontraumatic focal splenic lesions (FSL) are rare, and the need for tissue diagnosis must be weighed against the very high risk of bleeding after a splenic biopsy. The aim of this study was to explore the feasibility and diagnostic potential of acoustic radiation force impulse (ARFI) elastography as a noninvasive method for different benign and malignant FSLs. No human studies on the elastographic characteristics of FSL exist.

METHODS

This was a retrospective analysis of 34 patients with FSLs, who underwent abdominal B-mode ultrasound (B-US), contrast-enhanced ultrasound (CEUS), and standardized ARFI examinations between October 2021 and December 2022 at our university hospital. The inclusion criteria were: (i) FSL size ≥ 1 cm; (ii) 10 valid ARFI measurements of the FSL, as well as of the normal splenic parenchyma (NSP) as an in vivo reference; and (iii) diagnostic confirmation of FSL etiology based on histological examination (8/34; 23.5%) or clinical evaluation, which included a clinical and sonographic follow-up (FU), CEUS morphology, and/or morphology on cross-sectional imaging (26/34; 76.5%). CEUS was performed on all patients and the FSLs were classified according to the current guidelines; cross-sectional imaging was available for 29/34 (85.3%). The mean FU duration was 25.8 ± 30.5 months. The mean ARFI velocity (MAV) of the FSL (MAVL), the NSP (MAVP), and the ratio of the MAVL to the MAVP (MAVL/P) were calculated and compared.

RESULTS

Of the 34 FSLs, 13 (38.2%) were malignant (mFSL) and 21 (61.8%) were benign (bFSL). The MAVL of all 34 FSLs (2.74 ± 0.71 m/s) was lower than the MAVP (3.20 ± 0.59 m/s), p = 0.009, with a mean MAVL/P ratio of 0.90 ± 0.34. No significant differences in the MAVL were observed between the mFSL (2.66 ± 0.67 m/s) and bFSL (2.79 ± 0.75 m/s). There were also no significant differences between the MAVP in patients with mFSL (3.24 ± 0.68 m/s) as compared to that in the patients with bFSL (3.18 ± 0.55 m/s). Likewise, the MAV L/P ratio did not differ between the mFSL (0.90 ± 0.41 m/s) and bFSL (0.90 ± 0.30 m/s) groups.

CONCLUSION

ARFI elastography is feasible in evaluating the stiffness of FSLs. The lesions' stiffness was lower than that of the NSP, regardless of the FSL etiology. However, differentiation between benign and malignant FSL with the help of this elastographic method does not appear possible. Larger prospective studies are needed to validate these findings.

The Spectrum of Solitary Benign Splenic Lesions-Imaging Clues for a Noninvasive Diagnosis

Cross-sectional imaging of the upper abdomen, especially if intravenous contrast has been administered, will most likely reveal any acute or chronic disease harbored in the spleen. Unless imaging is performed with the specific purpose of evaluating the spleen or characterizing a known splenic lesion, incidentally discovered splenic lesions pose a small challenge. Solitary benign splenic lesions include cysts, hemangiomas, sclerosing angiomatous nodular transformation (SANT), hamartomas, and abscesses, among others. Sarcoidosis and tuberculosis, although predominantly diffuse micronodular disease processes, may also present as a solitary splenic mass lesion. In addition, infarction and rupture, both traumatic and spontaneous, may take place in the spleen. This review aims to describe the imaging features of the most common benign focal splenic lesions, with emphasis on the imaging findings as these are encountered on routine cross-sectional imaging from a multicenter pool of cases that, coupled with clinical information, can allow a definite diagnosis.

Applications of Contrast-Enhanced Ultrasound in Splenic Studies of Dogs and Cats

Simple Summary

Contrast-enhanced ultrasound (CEUS) is a noninvasive imaging technique that has become a reliable tool for identifying and monitoring lesions in both human and animals. In the last decade, its use in veterinary diagnostic imaging has gained increasing importance, and it can be reliable in everyday clinical practice. However, there is a lack of reviews describing existing CEUS results in the study of splenic lesions, which is of particular importance in dogs and cats. This information is important for validating its efficacy, to facilitate decision making related to sampling procedures and diagnosis, or even as a means to select CEUS as an alternative diagnostic tool in specific cases. Our goal was to review the existing studies of CEUS applications for splenic ultrasound studies in cats and dogs, present these results in a systematic manner, and combine this information into practical guidelines that can be used to help diagnosis and interpretation in both clinical cases and research.

Abstract

Contrast-enhanced ultrasound (CEUS) is an emerging technology in veterinary medicine involving the administration of intravenous contrast agents, and it is increasingly recognized for its high potential as a diagnostic imaging tool for small animals. This exam is easy and quick to perform, safe and reliable, and allows for the differentiation of lesions. It permits the identification of lesions that may require more invasive procedures, from those that can be safely dismissed to those that can be followed-up with ultrasound imaging. Although it has been extensively reviewed for use in human medicine, there is an overall lack of information about the application of this technique for cats and dogs, particularly in splenic studies, which can be particularly important for small animals. The present review describes and summarizes the CEUS applications used for splenic analysis in cats and dogs, providing a basic overview of CEUS technology with examples of common and uncommon features of focal splenic lesions. It also systematically gathers the results obtained for benign and malignant splenic lesions described in the literature, whilst providing guidelines for their interpretation. Furthermore, it presents the advantages of using CEUS for splenic analysis in cats and dogs and the main factors that may influence the quality of the imaging and the accuracy of the diagnosis. This type of knowledge can be used to provide a framework to help veterinarians make informed decisions regarding the use of this emerging technique for splenic lesions, guiding their interpretation of CEUS findings in the splenic ultrasounds of cats and dogs.

Contrast-enhanced US of the Liver and Kidney: A Problem-solving Modality

Contrast-enhanced US (CEUS) has an important role as a supplement to CT or MRI in clinical practice. The main established utilizations are in the liver and the kidney. The primary advantages of CEUS compared with contrast-enhanced CT or MRI relate to its superior contrast resolution, real-time continuous scanning, pure intravascular nature, portability, and safety-especially in patients with renal impairment or CT or MRI contrast agent allergy. This article focuses on the use of CEUS in the liver and kidney.

Identification of secondary splenic lymphoma with contrast-enhanced ultrasound in the pediatric population. A case report

Contrast-enhanced ultrasound scan (CEUS) is the application of ultrasound contrast agents (UCAs) to traditional ultrasound. Our aim is to report the use of CEUS for a prompt assessment of a suspected secondary splenic lymphoma in a child, which, in our experience, has allowed an accurate description of the parenchymal perfusion and vascularization pattern, leading to a confident diagnosis. We suggest that CEUS will replace Magnetic resonance imaging (MRI) or Computed tomography (CT) as standard imaging option for differential diagnosis of spleen lesions in pediatric population. As a result this will lead to decreasing the overall use of ionizing radiation and reducing the time interval to a certain diagnosis.

Contrast-enhanced ultrasound of the spleen, pancreas and gallbladder in children

Gray-scale and color/power Doppler ultrasound (US) are the first-line imaging modalities to evaluate the spleen, gallbladder and pancreas in children. The increasing use of contrast-enhanced ultrasound (CEUS) as a reliable and safe method to evaluate liver lesions in the pediatric population promises potential for imaging other internal organs. Although CEUS applications of the spleen, gallbladder and pancreas have been well described in adults, they have not been fully explored in children. In this manuscript, we present an overview of the applications of CEUS for normal variants and diseases affecting the spleen, gallbladder and pancreas. We highlight a variety of cases as examples of how CEUS can serve in the diagnosis and follow-up for such diseases in children. Our discussion includes specific examination techniques; presentation of the main imaging findings in various benign and malignant lesions of the spleen, gallbladder and pancreas in children; and acknowledgment of the limitations of CEUS for these organs.

Contrast-Enhanced Ultrasound Imaging Features of Focal Splenic Tuberculosis

Background

The aim of this study was to characterize the contrast-enhanced ultrasound imaging features of focal splenic tuberculosis.

Material/Methods

We retrospectively analyzed the conventional ultrasound (US) and contrast-enhanced ultrasound (CEUS) imaging features of 22 patients with splenic TB confirmed by surgical histopathology or biopsy.

Results

Conventional US demonstrated that 15 of the 22 patients had a single lesion, while 7 had multiple lesions. The maximum diameter of the lesions ranged from 1.0 to 3.7 cm. Of the 22, 17 were detected with hypoecho and 5 were detected with complex echo by conventional US. Seven (7/22) were detected with blood flow signals by color Doppler flow image (CDFI). CUES demonstrated that 18 cases (81.8%, 18/22) began to enhance in the arterial phase, mostly followed by slow wash-out in the intermediate or late parenchymal phase, and 4 (18.2%, 4/22) presented with non-enhancement during all phases. The enhancement patterns were categorized into 4 types: Type I, homogeneous enhancement (2/22); Type II, rim-like enhancement (12/22); Type III, septation-like enhancement (4/22); and Type IV, non-enhancement (4/22).

Conclusions

CEUS showed that splenic TB lesions were enhanced in the arterial phase, followed by slow washed out or persistent enhancement in the intermediate and late parenchymal phases. The rim- or septation-like enhancement may be helpful for diagnosing splenic TB. The splenic lesions presenting round hypoecho by conventional US and complete non-enhancement by CEUS are highly suspicious of splenic TB.

Focal splenic lesions: Imaging spectrum of diseases on CT, MRI and PET/CT

The spleen can be affected by a variety of diseases. Some of them are readily identified as variations of normal or benign diseases on imaging. However, for a substantial number of focal splenic abnormalities, the diagnosis can be difficult so that histopathologic analysis may be required for a definite diagnosis. In this review, the typical splenic abnormalities that can be diagnosed with imaging with a high degree of confidence are illustrated. The complementary role of computed tomography (CT), magnetic resonance imaging and positron emission tomography/CT that helps make a diagnostic approach is discussed. Finally, current applications and future trends of radiomics and artificial intelligence for the diagnosis of splenic diseases are addressed.

Contrast-Enhanced Ultrasound in Children: Implementation and Key Diagnostic Applications

Contrast-enhanced ultrasound (CEUS) utilization is expanding rapidly, particularly in children, in whom the modality offers important advantages of dynamic evaluation of the vasculature, portability, lack of ionizing radiation, and lack of need for sedation. Accumulating data establish an excellent safety profile of ultrasound contrast agents in children. Although only FDA-approved for IV use in children for characterizing focal liver lesions and for use during echocardiography, growing off-label applications are expanding the diagnostic potential of ultrasound. Focal liver lesion evaluation is the most common use of CEUS, and the American College of Radiology Pediatric LI-RADS Working Group recommends including CEUS for evaluation of a newly discovered focal liver lesion in many circumstances. Data also support the role of CEUS in hemodynamically stable children with blunt abdominal trauma, and CEUS is becoming a potential alternative to CT in this setting. Additional potential applications that require further study include evaluation of pathology in the lung, spleen, brain, pancreas, bowel, kidney, female pelvis, and scrotum. This review explores the implementation of CEUS in children, describing basic principles of ultrasound contrast agents and CEUS technique and summarizing current and potential IV diagnostic applications based on pediatric-specific supporting evidence.

Value of Contrast-Enhanced Ultrasound in the Differential Diagnosis of Focal Splenic Lesions

Purpose

To identify and validate contrast-enhanced ultrasound (CEUS) features for differentiating malignant from benign splenic lesions.

Patients and Methods

Splenic lesions in 123 patients who underwent conventional ultrasound (B-mode US) and CEUS were included in this study. Two radiologists evaluated the sonograms of B-mode and CEUS. Statistical analysis was performed to identify significant imaging predictors for splenic malignant lesions. Two other radiologists independently reviewed B-mode and CEUS sonograms and diagnosed the lesions based on proposed criteria as 1) benign, 2) probably benign, 3) probably malignant or 4) malignant. The diagnostic efficiency between B-mode US and CEUS was compared.

Results

Common imaging findings of malignant lesions included hypoechoic, ill-defined margin, absence of cystic/necrotic portion, presence of splenomegaly on B-mode US, and hypoenhancement, rapid washout and presence of intralesional vessels on CEUS (P < 0.05). Among them, three independent features were identified using multivariate logistic regression analysis: hypoechoic pattern, hypoenhancement pattern and intralesional vessels. When three of these findings were combined as a predictor for splenic malignant lesions, 22 (55.0%) of 40 malignant splenic lesions were identified with a specificity of 100%. The diagnostic performance of two readers using receiver operating characteristic curve analysis was 0.622 and 0.533, respectively, for B-mode US, which was significantly improved to 0.908 and 0.906 for CEUS (P < 0.001). The degree of other diagnostic efficiency and inter-reader agreement also increased with CEUS compared to B-mode US.

Conclusion

CEUS may provide more useful information than B-mode US and improve the diagnosis efficiency for distinguishing malignant from benign splenic lesions.

Ultrasound imaging of abdominal sarcoidosis: State of the art

Since it has been recognized that sarcoidosis (SA) is not an exclusive disorder of the lungs but can also affect other organs such as the liver and spleen, efforts have been made to define specific imaging criteria for the diagnosis of the single organ involvement, and the concept has been reinforced that the exclusion of alternative causes is important to achieve the correct diagnosis. Ultrasound (US) is a useful tool to evaluate patients with suspected abdominal SA, such as of the liver, spleen, kidney, pancreas and other organs, showing findings such as organomegaly, focal lesions and lymphadenopathy. While the diagnosis of abdominal SA is more predictable in the case of involvement of other organs (e.g., lungs), the problem is more complex in the case of isolated abdominal SA. The recent use of contrast-enhanced ultrasound and endoscopic ultrasound elastography has provided additional information about the enhancement patterns and tissue rigidity in abdominal SA. Here we critically review the role of US in abdominal SA, reporting typical findings and limitations of current evidence and by discussing future perspectives of study.

Diagnosis of congenital and acquired focal lesions in the neck, abdomen, and pelvis with contrast-enhanced ultrasound: a pictorial essay

Contrast-enhanced ultrasound (CEUS) is a versatile imaging modality that improves the diagnostic potential of conventional ultrasound. It allows for portable imaging at the bedside. In this paper, we illustrate how CEUS can be used in evaluating several focal lesions in the pediatric population, including liver hemangioma, telangiectasias, splenic hamartomas, and bladder lesions. We describe the ultrasound findings and contrast enhancement patterns associated with these lesions. Findings are correlated with MRI, CT, and/or pathology when available. This paper demonstrates the value of CEUS in improving characterization of many focal lesions in the pediatric population.

CONCLUSION

CEUS is a valuable bedside technique for use in the pediatric population to evaluate focal lesions in various organs, and will allow for safe, more efficient diagnostic imaging. What is Known: • CEUS offers many advantages over CT and MRI and is underutilized in the United States. • It is only FDA approved for vesicoureteral reflux and liver in the pediatric population. However, off label uses are well described. What is New: • This pictorial essay describes ultrasound findings and contrast enhancement patterns associated with liver hemangioma, liver telangiectasia, splenic hamartoma, hemorrhagic ovarian cyst, urachal remnant, spinning top urethras, and kaposiform hemangioendothelioma. • We demonstrate the utility of CEUS in expanding the diagnostic potential of conventional ultrasound.

Role of CT in Differentiating Malignant Focal Splenic Lesions

Objective

The purpose of this study was to asses the CT findings and clinical features differentiating malignant from benign focal splenic lesions.

Materials and Methods

Among 673 patients with splenectomy, we included 114 patients with pathologically confirmed focal splenic lesions (malignant = 66, benign = 48). Two radiologists retrospectively assessed CT findings including: size, number, solid component, margin, wall, calcification, contrast-enhancement, lymph node (LN) enlargement and possible malignancy. We assessed clinical features including age, sex, underlying malignancy, fever, and leukocytosis. Multivariate logistic regression analysis was performed to identify significant predictors of malignant lesion. We used receiver operating curve analysis for determination of diagnostic performance.

Results

Common findings of malignant lesions include enhanced, mainly solid, ill-defined margin, absence of splenomegaly, absence of the wall, absence of calcification, LN enlargement, and presence of underlying malignancy (p < 0.05). Among them, mainly solid features (odds ratio [OR], 39.098, p = 0.007), LN enlargement (OR, 6.326, p = 0.005), and presence of underlying malignancy (OR, 8.615, p = 0.001) were significant predictors of malignancy. The mean size of benign splenic lesions (5.8 ± 3.3 cm) was larger than that of malignant splenic lesions (4.0 ± 3.4 cm). Diagnostic performance of CT findings by two reviewers using receiver operating characteristic curve analysis for differentiation of malignant lesions was 0.856 and 0.893, respectively.

Conclusion

Solid nature of the splenic mass on CT images, LN enlargement, and presence of underlying malignancy are significant predictors of malignant splenic lesion.

The value of contrast-enhanced dynamic and diffusion-weighted MR imaging for distinguishing benign and malignant splenic masses

OBJECTIVE

To assess the value of contrast-enhanced dynamic and diffusion-weighted (DW) MR imaging for differentiating malignant from benign splenic lesions.

METHODS

This retrospective study included 51 patients with 35 benign and 16 malignant focal splenic lesions. All patients underwent contrast-enhanced dynamic and DW MR imaging. Two radiologists evaluated the MR images in consensus. Significant imaging findings on univariate and multivariate analyses were identified and their diagnostic performance for predicting the malignant splenic lesion was analyzed. Using receiver-operating characteristic analysis, the optimal cut-off of the apparent diffusion coefficient (ADC) value corresponding to the maximal Youden's index (J) for differentiating the two groups was determined.

RESULTS

In univariate analysis, low signal intensity (SI) on the arterial, portal and 3-min delayed-phase images, high or iso SI on the DW image, iso or low SI on the ADC map, the presence of diffusion restriction and arterial hypovascularity with a progressive enhancement pattern were more frequently observed (p < 0.05) in malignant splenic lesions. The ADC value was significantly lower for malignancy than for benignancy (0.78 ± 0.24 vs 1.16 ± 0.53 × 10(-3) mm(2) s(-1); p < 0.001). The optimal cut-off ADC value for differentiating the two groups was 0.995 × 10(-3) mm(2) s(-1). In multivariate analysis, findings that differentiated malignant from benign splenic lesions were low SI on the 3-min delayed-phase image [odds ratio (OR), 27.68; p = 0.006] and the presence of diffusion restriction (OR, 48.01; p = 0.002). When two of these criteria were combined, 12 (75.0%) of 16 malignant splenic masses were identified with a specificity of 100%.

CONCLUSION

Contrast-enhanced dynamic and DW MR imaging may be helpful for differentiating malignant from benign splenic lesions. A low SI on the 3-min delayed phase and diffusion restriction are the most reliable findings for the differentiation of malignant from benign splenic lesions.

ADVANCES IN KNOWLEDGE

Dynamic and DW MR imaging help in distinguishing malignant from benign splenic lesions. A low SI on the 3-min delayed phase and diffusion restriction are the most reliable findings for the differentiation of malignant from benign splenic lesions.

Isolated sarcoidosis of accessory spleen in the greater omentum: A case report

Sarcoidosis is a multisystemic disease of unknown origin characterized by the formation of non-caseating granulomas. Thoracic involvement is the most common presentation; however, sarcoidosis can involve almost any other organ. To the best of our knowledge there have been only 10 cases of splenic sarcoidosis reported in the English literature, with no reports of sarcoidosis of an accessory spleen. The present study reports a case of isolated sarcoidosis of an accessory spleen in the greater omentum, which was identified postoperatively in a 44-year-old female. Chest X-ray results were normal. Gastric endoscopy demonstrated an ulcer in the antrum, which was confirmed to be a signet-ring cell carcinoma via biopsy. Computed tomography of the abdomen revealed mild thickening of the posterior antrum, and a mass in the inferior pole of the left kidney. Intraoperatively, no masses were detected in the liver and spleen. Moreover, no enlarged lymph nodes were detected in the abdominal cavity, pelvic cavity, mesenteric and para-aorta. Following a radical distal gastrectomy and left radical nephrectomy, postoperative pathology demonstrated signet-ring cell carcinoma in the antrum, left renal clear cell cancer and a red lesion measuring 0.5×0.5 cm in the greater omentum, which was similar to the spleen in the splenic cavity and was regarded as an accessory spleen. Following exclusion of fungi and acid-fast bacilli as causative agents, sarcoidosis of the accessory spleen in the greater omentum was confirmed. The patient recovered uneventfully and was discharged on day 8 postoperation. The patient remained alive after two-year follow-up without sarcoidosis and malignant tumor recurrence. The present case demonstrated that, intraoperatively, comprehensive exploration should be conducted to exclude the accessory spleen, which may also suffer from sarcoidosis.

[A case of splenic hamartoma diagnosed by contrast-enhanced ultrasonography and magnetic resonance imaging]

Splenic hamartoma is a very rare benign tumor, which is usually found incidentally after splenectomy or autopsy. Although percutaneous needle biopsy can be performed, it carries a high risk of bleeding after the procedure. Therefore, diagnosis is usually made by surgical resection. Herein, we report a case of splenic hamartoma diagnosed by magnetic resonance imaging and contrast-enhanced ultrasonography, which enables visualization of the unique signals of microbubbles in the vessels in real time. Relevant literature is also reviewed.

Off-Label Use of Ultrasound Contrast Agents for Intravenous Applications in Children: Analysis of the Existing Literature

OBJECTIVES

The purpose of this study was to collect and analyze the published data related to intravenous (IV) use of ultrasound (US) contrast agents in children.

METHODS

We searched the literature to collect all of the published studies reporting the IV administration of a second-generation US contrast agent in children.

RESULTS

We analyzed 9 case series and 5 case reports, as well as 5 individual cases, of pediatric contrast-enhanced US use reported in a study group that also included adults. We found that 502 children underwent contrast-enhanced US examinations (mean age, 9.7 years; range, 1 day-18 years). Most patients (89%) were injected with the sulfur hexafluoride contrast agent SonoVue (Bracco SpA, Milan, Italy). The mean dose used was 1.5 mL (range, 0.1-9.6 mL). Only 10 patients (2%) had adverse reactions related to the contrast agent administration: 1 life-threatening anaphylactic shock and 9 mild transitory adverse effects. We additionally found 38 papers in which the study groups included at least 1 child; thus, we obtained a total of 540 reported cases of off-label use of IV US contrast agents in children. The most frequent target organ was the liver, and most indications were related to space-occupying lesion characterization and abdominal evaluations after blunt trauma. Some studies also evaluated the diagnostic performance of contrast-enhanced US in different clinical scenarios and found very good accuracy. Concordance between contrast-enhanced US imaging and the respective reference-standard imaging methods ranged between 83% and 100% in different studies.

CONCLUSIONS

Our results support the idea that the IV use of US contrast agents in children is safe, feasible, diagnostically robust, and effective.

EFFECT OF SEDATION ON CONTRAST-ENHANCED ULTRASONOGRAPHY OF THE SPLEEN IN HEALTHY DOGS

Contrast-enhanced ultrasound of the spleen enables the dynamic assessment of the perfusion of this organ, however, both subjective and quantitative evaluation can be strongly influenced by sedative agent administration. The purpose of this prospective, experimental study was to test effects of two sedative agents on splenic perfusion during contrast-enhanced ultrasound of the spleen in a sample of healthy dogs. Contrast-enhanced ultrasound of the spleen was repeated in six healthy Beagles following a cross-over study design comparing three protocols: awake, butorphanol 0.2 mg/Kg intramuscular (IM), and dexmedetomidine 500 μg/m(2) IM. After intravenous injection of a phospholipid stabilized sulfur hexafluoride microbubble solution (SonoVue®, Bracco Imaging, Milano, Italy), the enhancement intensity and perfusion pattern of the splenic parenchyma were assessed and perfusion parameters were calculated. Normal spleen was slightly heterogeneous in the early phase, but the parenchyma was homogeneous at a later phase. Sedation with butorphanol did not modify perfusion of the spleen. Dexmedetomidine significantly reduced splenic enhancement, providing diffuse parenchymal hypoechogenicity during the entire examination. Measured parameters were significantly modified, with increased arrival time (AT; (< 0.0001) and time to peak (TTP; P < 0.0001), and decreased peak intensity (PI; P = 0.0108), wash-in (P = 0.0014), and area under the curve (AUC; P = 0.0421). Findings supported the use of butorphanol and contraindicated the use of dexmedetomidine as sedatives for splenic contrast ultrasound procedures in dogs. Short-term and diffuse heterogeneity of the spleen in the early venous phase was determined to be a normal finding.

Contrast-enhanced ultrasound of the spleen

Abnormalities in the spleen are less common than in most other abdominal organs. However, they will be regularly encountered by ultrasound practitioners, who carefully evaluate the spleen in their abdominal ultrasound studies. Conventional grey scale and Doppler ultrasound are frequently unable to characterise focal splenic abnormalities; even when clinical and laboratory information is added to the ultrasound findings, it is often not possible to make a definite diagnosis. Contrast-enhanced ultrasound (CEUS) is easy to perform, inexpensive, safe and will usually provide valuable additional information about splenic abnormalities, allowing a definitive or short differential diagnosis to be made. It also identifies those lesions that may require further imaging or biopsy, from those that can be safely dismissed or followed with interval ultrasound imaging. CEUS is also indicated in confirming the nature of suspected accessory splenic tissue and in selected patients with abdominal trauma. This article describes the CEUS examination technique, summarises the indications for CEUS and provides guidance on interpretation of the CEUS findings in splenic ultrasound.

Laparoscopic splenectomy for a littoral cell angioma of the spleen: Case report

A littoral cell angioma (LCA) is a primary vascular tumor of the spleen, that can have malignant potential and may present association with other malignancies. This is a case of LCA that was discovered incidentally in a 79-year-old woman who presented with a polycythemia at the time of consultation. The neoplasm was evaluated by ultrasound and computed tomography. The patient underwent a splenectomy that revealed LCA by pathological evaluation. The post-operative outcome was favorable with no complications or recurrent disease. This case presentation, clinical, radiographic, and pathological features of an uncommon splenic tumor can be studied in order to advance our knowledge in our understanding of LCA.

Differentiation of malignant from benign focal splenic lesions: added value of diffusion-weighted MRI

OBJECTIVE

The objective of our study was to evaluate the added value of diffusion-weighted imaging (DWI) for distinguishing between malignant and benign focal splenic lesions.

MATERIALS AND METHODS

This study included 53 patients with 11 malignant and 42 benign splenic lesions who underwent gadoxetic acid-enhanced MRI and DWI. Qualitative and quantitative analyses were conducted for splenic lesions. Two blinded observers evaluated the two image sets--that is, the conventional MR images alone versus the combined conventional MR and DW images--and scored their confidence for malignancy of splenic lesions. The Fisher exact test and Mann-Whitney U test were performed, and diagnostic performance values (ROC curve analysis) were evaluated.

RESULTS

All malignant lesions showed a progressive hypovascular enhancement pattern, whereas the hypervascular enhancement patterns were shown in only benign lesions (n = 20, 47.6%) (p < 0.05). The mean apparent diffusion coefficient (ADC) of the malignant lesions (0.73 × 10(-3) mm(2)/s) was significantly lower than that of the benign lesions (1.21 × 10(-3) mm(2)/s) (p < 0.001). The addition of DW images to conventional MR images showed a significant improvement for predicting malignant splenic lesions (area under ROC curve [Az] without DW images vs with DW images: 0.774 vs 0.983 for observer 1 and 0.742 vs 0.986 for observer 2) (p < 0.001). In addition, the diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of combined conventional MR and DW images were higher than those of conventional MR images alone.

CONCLUSION

The addition of DWI to conventional MRI improves differentiation of malignant from benign splenic lesions.

Hepatosplenic sarcoidosis: contrast-enhanced ultrasound findings and implications for clinical practice

Sarcoidosis is a complex granulomatous disease that affects virtually every organ and tissue, with a prevalence that varies significantly among the sites involved. The role of conventional imaging, such as computed tomography and magnetic resonance imaging, in the assessment of hepatosplenic sarcoidosis is well established by revealing organ enlargement, multiple discrete nodules, and lymphadenopathy. In this review, we aim to describe contrast-enhanced ultrasound (CEUS) findings in liver and spleen involvement by sarcoidosis, reporting evidence from the literature and cases from our experience, after a brief update on safety profile, cost-effectiveness, and clinical indications of this novel technique. Furthermore, we highlight potential advantages of CEUS in assessing hepatosplenic sarcoidosis that may be useful in the clinical practice.

The Mysterious Organ. Spectrum of Focal Lesions within the Splenic Parenchyma: Cross-Sectional Imaging with Emphasis on Magnetic Resonance Imaging

Incidental splenic lesions are frequently encountered at imaging performed for unrelated causes. Splenic cysts, hemangiomas, and lymphomatous involvement are the most frequently encountered entities. Computed tomography and sonography are commonly used for initial evaluation with magnetic resonance imaging reserved as a useful problem-solving tool for characterizing atypical and uncommon lesions. The value of magnetic resonance imaging lies in classifying these lesions as either benign or malignant by virtue of their signal-intensity characteristics on T1- and T2-weighted imaging and optimal depiction of internal hemorrhage. Dynamic contrast-enhanced sequences may improve the evaluation of focal splenic lesions and allow characterization of cysts, smaller hemangiomas, and hamartomas. Any atypical or unexplained imaging feature related to an incidental splenic lesion requires additional evaluation and/or follow-up. Occasionally, biopsy or splenectomy may be required for definitive assessment given that some of tumours may demonstrate uncertain biologic behavior.

Real-time contrast enhanced ultrasound imaging of focal splenic lesions

OBJECTIVE

To investigate the imaging features of focal splenic lesions (FSLs) on contrast-enhanced ultrasound (CEUS).

METHODS

Thirty two patients with FSLs proved by pathology were retrospectively analyzed. CEUS was performed using intravenous bolus injection of 2.4 ml sulfur hexafluoride-filled microbubble contrast agent and real time scanning. There were hemangioma (n=7), lymphoma (n=8), true cyst (n=3), infarction (n=4), hematolymphangioma (n=2), metastasis tumor (n=2), and one for each of the following entities extramedullary hemopoiesis, hamartoma, tuberculosis, Langerhans' cell histiocytosis, inflammatory pseudotumor and myxofibrosarcoma.

RESULTS

Among 21 benign lesions, 4 infarctions and 3 cysts presented non-enhancement throughout CEUS scanning, and the other 14 lesions displayed various enhancement levels with 6 (42.9%) hyper-enhancement, 2 (14.3%) iso-enhancement and 6 (42.9%) hypo-enhancement in arterial phase and 11 (78.6%) hypo-enhancement, 1 (7.1%) iso-enhancement and 2 (14.3%) hyper-enhancement in late phase, respectively. The enhancement pattern included 9 (64.3%) homogeneous, 4 (28.6%) heterogeneous and 1 (7.1%) rim-like enhancement. As for the malignant FSLs, all the lesions became completely or extensively hypo-enhancement during the late phase no matter their vascularity during arterial phase.

CONCLUSIONS

The CEUS features reported in this series may enrich the knowledge for CEUS characterization of FSLs.

Littoral cell angioma of the spleen: sonographic-pathologic comparison

OBJECTIVES

The purpose of this study was to evaluate the sonographic and pathologic features of littoral cell angioma of the spleen in 7 patients.

METHODS

The sonographic appearance in 7 cases of littoral cell angioma confirmed by surgical pathologic examination was retrospectively reviewed. All underwent color Doppler imaging. Two underwent contrast-enhanced sonography. The sonographic appearance was compared with pathologic findings.

RESULTS

Splenic lesions were solitary in 5 cases and multiple in 2 cases. The masses ranged from 10 to 64 mm in maximum diameter. Five hypoechoic and 2 hyperechoic lesions on grayscale sonography corresponded to few and multiple blood-filled spaces on pathologic examination, respectively. Four hypovascular lesions, 1 hypervascular lesion, and the other 2 hypervascular lesions full of color flow signals on color Doppler imaging corresponded to few, several, and multiple arteries on pathologic examination. On contrast-enhanced sonography, 1 hypervascular lesion full of color flow signals showed homogeneous hyperenhancement for 8 minutes during the arterial and parenchymal phases. One hypovascular lesion showed inhomogeneous isoenhancement transiently during the arterial phase and became hypoechoic later.

CONCLUSIONS

Littoral cell angioma is a primary vascular splenic neoplasm with variable features on grayscale sonography and color Doppler imaging as well as contrast-enhanced sonography. The sonographic appearance of littoral cell angioma mainly depends on the type and number of tumor vessels.

Pitfalls of contrast-enhanced ultrasound (CEUS) in the diagnosis of splenic sarcoidosis

By observing the real-time behavior of focal liver lesions at three vascular phases (arterial, portal-venous, and late), contrast-enhanced ultrasound (CEUS) has been successfully applied to differentiate benign from malignant hepatic nodules. In recent years, numerous studies highlighted the usefulness of CEUS also for other applications such as abdominal trauma, renal, pancreatic, thyroid, and inflammatory bowel diseases, supporting its role even in differentiating benign from malignant splenic nodules. Therefore, the European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB) recently updated the guidelines for the use of ultrasound contrast agents in clinical practice, pointing out the indication to characterize splenic parenchymal inhomogeneity or suspected lesions found on conventional ultrasound (BUS). We describe the case of a patient with a history of colon cancer and finding, at BUS and CEUS, of hypoechoic lesions with a highly suggestive pattern for metastases, subsequently histologically proved to be splenic localizations of a benign and multisystemic granulomatous disease such as sarcoidosis. We therefore reviewed the current literature focusing on the role of CEUS in differentiating benign from malignant splenic lesions, emphasizing on the lack of data and numerical shortage of sarcoidosis derived-lesions in the available studies. We conclude that sarcoidosis remains a diagnosis of exclusion and new studies are needed before defining precise indications of CEUS in these patients.

Contrast-enhanced ultrasound in abdominal imaging

The administration of a contrast agent is considered an essential tool to evaluate abdominal diseases using Ultrasound. The most targeted organ is the liver, especially to characterize focal liver lesions and to assess the response to percutaneous treatment. However, the expanding abdominal indications of contrast-enhanced ultrasound make this technique an important tool in the assessment of organ perfusion including the evaluation of ischemic, traumatic, and inflammatory diseases.

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.

Contrast-enhanced ultrasound of the spleen: an introduction and pictorial essay

A wide variety of pathologies can produce focal lesions within the spleen. These are being more frequently encountered as imaging technology improves. It is vital that radiologists are aware of these pathologies to enable accurate diagnosis. The role of ultrasound contrast in splenic disease will be discussed and illustrated with cases likely to be encountered by general and abdominal radiologists.

Real-time contrast-enhanced ultrasound in diagnosing of focal spleen lesions

OBJECTIVE

To investigate the features of focal spleen lesions (FSLs) on contrast-enhanced ultrasound (CEUS) imaging.

MATERIALS AND METHODS

CEUS with a blot injection of SonoVue was performed in 48 patients with 75 FSLs (median diameter 2.6cm) and their perfusion characteristics were analyzed by using contrast pulse sequences (CPS) technique.

RESULTS

Among 19 malignant lesions (10 metastases, 7 lymphoma, 1 hemangiosarcoma, 1 epithelioid hemangioendothelioma) and 56 benign lesion (23 hemangiomas, 14 cysts, 8 infarctions, 4 splenic ruptures, 3 tuberculosis, 2 abscess, 1 pseudoaneurysm, 1 lymphangioma), 25 benign lesions were demonstrated nonenhancement. For malignancy, 50.0% (5/10) metastases and 57.1% (4/7) lymphomas were showed hypoenhancement in the arterial phase, and 18 (94.7%) of malignant lesions were hypo-enhancement in the parenchymal phase. Among 31 benign lesions with enhancement, 27 (87.1%) were showed isoenhancement or hyperenhancement in the arterial phase and 22 (71.0%) lesions were isoenhancement or hyperenhancement in the parenchymal phase. The sensitivity, specificity and accuracy of diagnosis for FSLs were 91.1%, 95.0% and 92.0% for CEUS and 75.0%, 84.2% and 77.3% respectively, for the conventional baseline ultrasound (BUS).

CONCLUSION

Real-time CEUS can provide valuable information for the diagnosis and differential diagnosis of FSLs.

Contrast-enhanced ultrasound features of primary splenic lymphoma

We report a case of primary splenic lymphoma incidentally detected on abdominal ultrasound as a well-defined homogenous hypoechoic splenic mass. Further characterization with contrast-enhanced ultrasound showed the mass to enhance homogenously during the arterial phase to a degree similar to that of the normal splenic parenchyma followed by rapid washout becoming hypoenhanced on delayed phase.

Contrast-enhanced ultrasound: The evolving applications

Contrast-enhanced ultrasound (CEUS) is a major breakthrough for ultrasound imaging in recent years. By using a microbubble contrast agent and contrast-specific imaging software, CEUS is able to depict the micro- and macro-circulation of the targeted organ, which in turn leads to improved performance in diagnosis. Due to the special dual blood supply system in the liver, CEUS is particularly suitable for liver imaging. It is evident that CEUS facilitates improvement for characterization of focal liver lesions (FLLs), detection of liver malignancy, guidance for interventional procedures, and evaluation of treatment response after local therapies. CEUS has been demonstrated to be equal to contrast-enhanced computed tomography or magnetic resonance imaging for the characterization of FLLs. In addition, the applicability of CEUS has expanded to non-liver structures such as gallbladder, bile duct, pancreas, kidney, spleen, breast, thyroid, and prostate. The usefulness of CEUS in these applications is confirmed by extensive literature production. Novel applications include detecting bleeding sites and hematomas in patients with abdominal trauma, guiding percutaneous injection therapy and therefore achieving the goal of using interventional ultrasonography in managing splenic trauma, assessing the activity of Crohn’s disease, and detecting suspected endoleaks after endovascular abdominal aneurysm repair. Contrast-enhanced intraoperative ultrasound (US) and intracavitary use of CEUS have been developed and clinically studied. The potential use of CEUS involves sentinel lymph node detection, drug or gene delivery, and molecular imaging. In conclusion, the advent of CEUS has greatly enhanced the usefulness of US and even changed the status of US in clinical practice. The application of CEUS in the clinic is continuously evolving and it is expected that its use will be expanded further in the future.