Validation of the standardization framework SSTR-RADS 1.0 for neuroendocrine tumors using the novel SSTR‑targeting peptide [18F]SiTATE

OBJECTIVES

Somatostatin receptor positron emission tomography/computed tomography (SSTR-PET/CT) using [68Ga]-labeled tracers is a widely used imaging modality for neuroendocrine tumors (NET). Recently, [18F]SiTATE, a SiFAlin tagged [Tyr3]-octreotate (TATE) PET tracer, has shown great potential due to favorable clinical characteristics. We aimed to evaluate the reproducibility of Somatostatin Receptor-Reporting and Data System 1.0 (SSTR-RADS 1.0) for structured interpretation and treatment planning of NET using [18F]SiTATE.

METHODS

Four readers assessed [18F]SiTATE-PET/CT of 95 patients according to the SSTR-RADS 1.0 criteria at two different time points. Each reader evaluated up to five target lesions per scan. The overall scan score and the decision on peptide receptor radionuclide therapy (PRRT) were considered. Inter- and intra-reader agreement was determined using the intraclass correlation coefficient (ICC).

RESULTS

The ICC analysis on the inter-reader agreement using SSTR-RADS 1.0 for identical target lesions (ICC ≥ 85%), overall scan score (ICC ≥ 90%), and the decision to recommend PRRT (ICC ≥ 85%) showed excellent agreement. However, significant differences were observed in recommending PRRT among experienced readers (ER) (p = 0.020) and inexperienced readers (IR) (p = 0.004). Compartment-based analysis demonstrated good to excellent inter-reader agreement for most organs (ICC ≥ 74%), except for lymph nodes (ICC ≥ 53%).

CONCLUSION

SSTR-RADS 1.0 represents a highly reproducible and consistent framework system for stratifying SSTR-targeted PET/CT scans, even using the novel SSTR-ligand [18F]SiTATE. Some inter-reader variability was observed regarding the evaluation of uptake intensity prior to PRRT as well as compartment scoring of lymph nodes, indicating that those categories require special attention during further clinical validation and might be refined in a future SSTR-RADS version 1.1.

CLINICAL RELEVANCE STATEMENT

SSTR-RADS 1.0 is a consistent framework for categorizing somatostatin receptor-targeted PET/CT scans when using [18F]SiTATE. The framework serves as a valuable tool for facilitating and improving the management of patients with NET.

KEY POINTS

SSTR-RADS 1.0 is a valuable tool for managing patients with NET. SSTR-RADS 1.0 categorizes patients with showing strong agreement across diverse reader expertise. As an alternative to [68Ga]-labeled PET/CT in neuroendocrine tumor imaging, SSTR-RADS 1.0 reliably classifies [18F]SiTATE-PET/CT.

[Imaging of neuroendocrine tumors of the gastrointestinal tract : Value of (hybrid) imaging diagnostics in radiology]

CLINICAL/METHODICAL ISSUE

Neuroendocrine tumors (NET) represent a heterogeneous group of rare tumors that predominantly arise in the gastrointestinal tract. At the time of initial diagnosis, the NET has already spread locoregionally in about half of the patients, and 27% of patients have already developed distant metastases. Since this plays a crucial role in therapy planning, accurate diagnostic imaging is important.

STANDARD RADIOLOGICAL METHODS

Due to its high temporal and spatial resolution (multiphasic including arterial phase), computed tomography (CT) plays a decisive role in primary staging and follow-up care, while magnetic resonance imaging (MRI) with its excellent soft tissue contrast offers advantages in the assessment of parenchymal organs in the upper abdomen.

METHODICAL INNOVATIONS

Somatostatin receptor (SSR) positron emission tomography (PET) provides additional functional information that not only helps to detect the primary tumor and distant metastases, but also has a significant influence on therapeutic management in a theranostic approach.

PERFORMANCE

Hybrid imaging using SSR-PET/CT has proven to be particularly effective in the detection of NET. Compared to conventional imaging, it provides additional information in 68% of patients, which has a significant impact on clinical management.

ACHIEVEMENTS

Imaging of NET requires the combined use of various methods such as ultrasound, CT, MRI, and PET/CT to enable accurate diagnosis and effective treatment planning.

PRACTICAL RECOMMENDATIONS

SSR-PET/CT is a valuable tool for the accurate staging of neuroendocrine tumors of the gastrointestinal tract, especially with small metastases, while MRI with hepatocyte-specific contrast agent and diffusion-weighted imaging is useful for the specific assessment of liver metastases.

Diagnostic accuracy of SSR-PET/CT compared to histopathology in the identification of liver metastases from well-differentiated neuroendocrine tumors

BACKGROUND

Histopathology is the reference standard for diagnosing liver metastases of neuroendocrine tumors (NETs). Somatostatin receptor-positron emission tomography / computed tomography (SSR-PET/CT) has emerged as a promising non-invasive imaging modality for staging NETs. We aimed to assess the diagnostic accuracy of SSR-PET/CT in the identification of liver metastases in patients with proven NETs compared to histopathology.

METHODS

Histopathologic reports of 139 resected or biopsied liver lesions of patients with known NET were correlated with matching SSR-PET/CTs and the positive/negative predictive value (PPV/NPV), sensitivity, specificity, and diagnostic accuracy of SSR-PET/CT were evaluated. PET/CT reading was performed by one expert reader blinded to histopathology and clinical data.

RESULTS

133 of 139 (95.7%) liver lesions showed malignant SSR-uptake in PET/CT while initial histopathology reported on 'liver metastases of NET´ in 127 (91.4%) cases, giving a PPV of 91.0%. Re-biopsy of the initially histopathologically negative lesions (reference standard) nevertheless diagnosed 'liver metastases of NET' in 6 cases, improving the PPV of PET/CT to 95.5%. Reasons for initial false-negative histopathology were inadequate sampling in the sense of non-target biopsies. The 6 (4.3%) SSR-negative lesions were all G2 NETs with a Ki-67 between 2-15%.

CONCLUSION

SSR-PET/CT is a highly accurate imaging modality for the diagnosis of liver metastases in patients with proven NETs. However, we found that due to the well-known tumor heterogeneity of NETs, specifically in G2 NETs approximately 4-5% are SSR-negative and may require additional imaging with [18F]FDG PET/CT.

The diagnostic value of contrast-enhanced ultrasound (CEUS) for assessing hepatocellular carcinoma compared to histopathology; a retrospective single-center analysis of 119 patients1

BACKGROUND

HCC as the 6th most common tumor entity with the fourth highest mortality and an increasing prevalence especially due to today's lifestyle acquires a high attention in the clinical setting. Beside CECT and CEMRI, CEUS depicts a dynamic, low-risk and radiation free imaging method that finds its use mainly in screening and active surveillance programs.

PURPOSE

The aim of the retrospective study was to evaluate the diagnostic value of CEUS in correlation to pathologic findings.

MATERIALS AND METHODS

Between 2004 and 2018 a total number of 119 patients were included in this retrospective single-center study. Every patient underwent CEUS in addition to a native B-mode and Color-Doppler scan. After given informed consent SonoVue® (Bracco, Milan, Italy), a second-generation blood-pool agent, was used as contrast medium. Every examination was performed and interpreted by a single experienced radiologist (EFSUMB level 3). A low mechanical index (MI) of <0,2 was chosen to obtain a good imaging quality.

RESULTS

All 119 included patients received CEUS followed by a liver biopsy for inter-modality comparison. In correlation to the pathology results, CEUS showed a diagnostic sensitivity of 96,6%, a specificity of 63,9%, a PPV of 86,7% and a NPV of 88,5% by detecting liver lesions suspicious for HCC. According to the Cohen's Kappa coefficient (k = 0,659) CEUS shows a strong inter-modality agreement in comparison to the histopathological finding.

CONCLUSION

With a high sensitivity and a strong cross-modality comparability to histopathology, the CEUS is highly effective in the detection of suspicious HCC lesions.

The diagnostic performance of contrast-enhanced ultrasound (CEUS) for evaluating hepatocellular carcinoma (HCC) juxtaposed to MRI findings; a retrospective single-center analysis of 292 patients

BACKGROUND

HCC is the most frequent primary liver cancer entity. Major risk factors comprise chronic HBC and HCV infections, ALD or NAFLD. Apart from the anamnesis, the clinical examination and serologic analysis, an essential part of the diagnostic HCC work-up is due to imaging findings from sonography, CT or MRI scans. HCC lesions feature a distinct vascularization pattern: hyperenhancement during early arterial and hypoenhancement/wash-out during portal venous or delayed phases. CEUS facilitates dynamic assessment of microperfusion patterns of suspicious liver lesions.

PURPOSE

The purpose of the present retrospective single-center study was to determine the diagnostic value of CEUS for assessing HCC by comparison with findings from MRI scans.

MATERIALS AND METHODS

Between 2004-2018 292 patients with suspicious liver lesions underwent CEUS and MRI. All patients underwent native B-mode, Color Doppler and CEUS after given informed consent. The applied contrast agent was a second-generation blood pool agent (SonoVue®, Bracco, Milan, Italy). Every CEUS examination was performed and interpreted by a single experienced radiologist (EFSUMB Level 3).

RESULTS

CEUS was performed on all included patients without occurrence of any adverse effects. CEUS showed a sensitivity of 96%, a specificity of 91%, a PPV of 95% and a NPV of 94% for analyzing HCC in comparison with MRI as the diagnostic gold standard.

CONCLUSION

With a distinguished safety profile CEUS shows a high diagnostic accuracy in assessing HCC compared to corresponding results from MRI scans.

Contrast-enhanced ultrasound (CEUS) in the diagnostic evaluation of popliteal artery aneurysms, a single-center study

BACKGROUND

Popliteal artery aneurysms (PAA) are the most common peripheral artery aneurysms. Most common cause is arteriosclerosis. Acute thromboembolic limb ischemia and rupture of the PAA depict severe complications. Diagnostic tools for identifying PAAs are (Doppler) ultrasound, CT/MR angiography and DSA.

PURPOSE

The aim of the present retrospective single-center study is to assess the application and safety of CEUS for assessing untreated and treated PAAs.

MATERIALS AND METHODS

13 patients were included in this study on whom CEUS was performed between 2007-2016. CEUS examinations were performed and interpreted by an experienced single radiologist (EFSUMB Level 3).

RESULTS

CEUS allowed for the detection of PAAs in all cases. CEUS allowed for detection of partial thrombosis of PAA in 7/8 of untreated patients, proper exclusion of PAA upon femoro-popliteal bypass in 3 patients, incomplete exclusion of PAA upon femoro-popliteal bypass in 1 patient and ruling out of in-stent stenosis in 1 patient.

CONCLUSION

CEUS is a useful and safe tool for in real-time evaluation of PAAs in the pre-/post-treatment status. In addition to conventional (Doppler) ultrasound and as an alternative tool to more elaborate imaging modalities, CEUS might be integrated in the future diagnostic work-up and follow-up of PAA patients.

Performance of contrast-enhanced ultrasound (CEUS) compared to MRI in the diagnostic of gallbladder diseases

BACKGROUND

Conventional ultrasound and MRI are very important techniques for the detection of gallbladder alterations. In the past years, studies showed that the additional use of contrast media to the conventional ultrasound allows the early depiction of pathological microvessels and their flow elucidating suspect findings stipulating the prompt therapy approach.

OBJECTIVE

The study aims to evaluate the performance of CEUS in gallbladder diseases and compare it to MR imaging using histopathological findings as a gold standard.

MATERIAL AND METHODS

The retrospective mono-center study analysed 18 patients with gallbladder alterations between 2009 and 2017. All patients underwent CEUS and MRI examinations and all results were confirmed in the pathology. CEUS images were performed and interpreted by a single experienced physician.

RESULTS

CEUS imaging results compared to MR imaging of the gallbladder demonstrated a sensitivity of 100%, specificity of 93%, a positive predictive value of 67% and a negative predictive value of 100%.

CONCLUSION

CEUS enables the depiction and characterization of important vascularization's patterns facilitating the early differentiation between malignant and benign findings. In this study, CEUS displayed a better diagnostic accuracy than MRI proving to be a valuable additional tool to the established imaging modalities.

[CEUS-diagnosis of benign liver lesions]

CLINICAL/METHODICAL ISSUE

Focal liver lesions are commonly seen during routine ultrasound examinations.

STANDARD RADIOLOGICAL METHODS

With native ultrasound there are lesions that cannot be sufficiently characterized. In these cases additional imaging might be necessary.

METHODICAL INNOVATIONS

With contrast-enhanced ultrasound (CEUS), focal liver lesions can be characterized with high diagnostic accuracy. After the ultrasound contrast agent has been injected into a peripheral vein, the examiner saves video loops of the arterial, portal venous and late contrast phases. Combing the findings of native and contrast-enhanced ultrasound allows not only assessment of the etiology as benign or malignant but also detailed characterization of the focal liver lesion in most cases.

PERFORMANCE

Using CEUS, focal liver lesions can be characterized with a sensitivity of over 95% and a specificity of about 83%.

ACHIEVEMENTS

The advantages of CEUS include that there is no radiation exposure and that the ultrasound contrast agent has no effects on the function of the liver, kidneys or the thyroid gland. The main limiting factors for CEUS are bowel gas and obesity of the patient.

PRACTICAL RECOMMENDATIONS

CEUS can visualize micro- and macrovascularization of benign focal liver lesions in real time. It is a useful imaging modality in unclear cases.

[CEUS-diagnostic workup of cystic renal lesions]

CLINICAL/METHODICAL ISSUE

Cystic renal lesions are common incidental findings in radiological imaging and they should be adequately examined to be able to characterize them as benign or malignant.

STANDARD RADIOLOGICAL METHODS

It is not always possible to sufficiently characterize cystic renal lesion solely using native B‑mode sonography and color-Doppler sonography.

METHODICAL INNOVATIONS

Using contrast-enhanced ultrasound (CEUS), it is possible to dynamically evaluate the perfusion of cystic renal lesions and to characterize the potential malignancy of these lesions using the Bosniak classification in order to give recommendations regarding further work-up. CEUS can also be used in patients with contraindications for other radiological imaging modalities as it uses a contrast agent with almost no side effects.

PERFORMANCE

Using CEUS, cystic renal lesions can be reliably characterized with a diagnostic accuracy greater than 90%.

ACHIEVEMENTS

CEUS is a useful method in diagnosing and characterizing unclear cystic renal lesions and should always be considered as a viable diagnostic tool.

PRACTICAL RECOMMENDATIONS

CEUS should always be performed in initially unclear cases and is a useful additional tool for the diagnosis and characterization of unclear cystic renal lesions.

Contrast-enhanced ultrasound (CEUS) and gallbladder diseases - A retrospective mono-center analysis of imaging findings with histopathological correlation

BACKGROUND

Radiologic imaging, especially ultrasound has an important role in the assessment of gallbladder alteration. Contrast-enhanced ultrasound (CEUS) is an easy and fast imaging technique that overcomes the limitations of greyscale ultrasonography. It is a safe tool that can be used as an additional imaging modality in order to elucidate and differentiate gallbladder pathological findings.

OBJECTIVE

The aim of this retrospective study analysis is to assess the diagnostic performance of CEUS in gallbladder alterations and compare the results to the histopathological findings.

METHODS

A total of 17 patients between 2009 and 2017 with uncertain gallbladder appearance were retrospectively analysed. A single experienced physician with more than fifteen years' experience performed CEUS examinations by applying a second-generation blood pool agent (SonoVue®, Bracco, Milan, Italy). Archived images were interpreted by the same physician and compared to the histopathological findings.

RESULTS

CEUS results, when correlated to the respectively pathologic findings, presented a sensitivity of 100%, a specificity of 100%, a positive predictive value (PPV) of 100% and a negative predictive value (NPV) of 100%. All patients were successfully examined without any adverse reaction.

CONCLUSION

In conclusion, the excellent results in this study acknowledged that CEUS is a feasible alternative tool to differentiate gallbladder pathologic alterations.

Vascular rejection in renal transplant: Diagnostic value of contrast-enhanced ultrasound (CEUS) compared to biopsy

BACKGROUND

Despite of the more potent immunosuppressive medication, vascular rejection is still a major issue after renal transplantation. Renal biopsy is the gold standard diagnostic to evaluate acute and chronic allograft rejection. As it is an invasive diagnostic there is the risk of complications like haematoma, arteriovenous fistulas, active bleeding or infection. Contrast-enhanced ultrasound is a non-invasive imaging modality that allows visualising renal transplant perfusion.

OBJECTIVE

To analyse the sensitivity and specificity of contrast-enhanced ultrasound (CEUS) compared to biopsy as gold standard in diagnosing vascular rejection in renal transplant patients.

METHODS

A total of 57 renal transplant recipients with poor renal allograft function with initial diagnostic imaging between 2006 and 2017 were included in the study. Clinical data and imaging studies were analysed retrospectively. The diagnostic accuracy of CEUS in diagnosing vascular rejection of the renal transplant was compared to renal biopsy as gold standard. Out of 57 patients 7 patients showed signs of vascular rejection in biopsy. In 6 out of these 7 patients CEUS described irregularities in renal perfusion suspicious of vascular rejection.

RESULTS

CEUS showed a sensitivity of 85.7%, a specificity of 100%, a positive predictive value (PPV) of 100%, and a negative predictive value (NPV) of 98.0%.

CONCLUSIONS

CEUS is a safe, non-nephrotoxic imaging modality for the initial imaging of renal transplant recipients with elevated kidney function parameters suspicious of vascular rejection. Compared to renal biopsy as gold standard CEUS shows a high specificity and PPV in detecting signs of vascular rejection. Since sub-types of vascular rejection with cellular and humoral components with greater risk for allograft loss have been described renal biopsy is inevitable in these cases.

Contrast-enhanced ultrasound (CEUS) as a new technique to characterize suspected renal transplant malignancies in renal transplant patients in comparison to standard imaging modalities

BACKGROUND

Renal transplant patients have a higher risk for malignancies of the renal transplant. In most cases suspected renal malignancies will be detected during the regular ultrasound follow-up and will require cross-sectional imaging to rule out a malignant aetiology. But it is well known that contrast agents for computed tomography or magnetic resonance imaging are critical in patients with limited renal function.

OBJECTIVE

This study aims to compare the sensitivity and specificity of contrast-enhanced ultrasound (CEUS) and gold standard imaging modalities in characterizing suspected renal transplant malignancies in renal transplant patients.

METHODS

A total of 22 renal transplant patients who underwent one or more CEUS examinations and at least one standard imaging modality (CT or MRI) between 2005 and 2017 were included. Patient ages ranged from 28.2 years to 74.6 (mean age 55.7 years; SD±13.0 years). CEUS of 22 patients was correlated with a standard imaging modality, CT (15 out of 22) or MRI (7 out of 22), serving as gold standard.

RESULTS

CEUS showed a sensitivity of 100%, a specificity of 94.4%, a positive predictive value (PPV) of 80%, and a negative predictive value (NPV) of 100%.

CONCLUSIONS

CEUS is an eligible method to help characterizing suspected renal malignancies in renal transplant patients compared to the well-established imaging modalities CT and MRI. As an imaging modality with no nephrotoxic effects CEUS can be used repeatedly even in patients with limited renal function.

The diagnostic value of contrast-enhanced ultrasound (CEUS) as a new technique for imaging of vascular complications in renal transplants compared to standard imaging modalities

BACKGROUND

Vascular complications in renal transplant patients are a well-known issue in post transplant patient care. If malfunctioning of the renal transplant is suspected to be caused by vascular complications an early diagnosis and therapy is required to maintain the renal transplant. Computed tomography (CT), digital substraction angiography (DSA) and radioisotope renography are the gold standard imaging modalities to diagnose vascular complications.

OBJECTIVE

To analyse the sensitivity and specificity of contrast-enhanced ultrasound (CEUS) in comparison to the standard imaging modalities CT, DSA and radioisotope renography in the diagnosis of vascular complications in renal transplant patients.

METHODS

A total of 33 renal transplant recipients with elevated kidney function parameters with initial diagnostic imaging between 2006 and 2017 were included in the study. The imaging studies and clinical data were analysed retrospectively. The diagnostic accuracy of CEUS was compared to CT, DSA and renal scintigraphy respectively which are classified as gold standard for diagnosis of vascular complications in renal transplant patients. Out of 23 patients 15 patients showed vascular complications in CT, DSA or radioisotope renography and in 15 out of 15 patients CEUS detected the vascular complication.

RESULTS

CEUS showed a sensitivity of 100%, a specificity of 66.7%, a positive predictive value (PPV) of 71.4%, and a negative predictive value (NPV) of 100%.

CONCLUSIONS

CEUS is a non-nephrotoxic and safe method for the initial imaging of vascular complications in renal transplant recipients. Compared to the gold standard imaging modalities CT, DSA and radioisotope renography CEUS shows a high sensitivity and NPV in detecting vascular complications. In cases with suspected stenosis of the transplant renal artery additional DSA might be needed.

Contrast-enhanced ultrasound (CEUS) prediction of focal liver lesions in patients after liver transplantation in comparison to histopathology results

PURPOSE

To investigate the value of contrast-enhanced ultrasound (CEUS) in histologic prediction of focal liver lesions after liver transplantation.

MATERIALS AND METHODS

10 focal liver lesions in 10 patients after liver transplantation were scanned using CEUS and the CEUS results were compared with the histopathological results.

RESULTS

Among 10 focal liver lesions, 7 proofed to be histopathological benign and 3 lesions proofed to be histopathological malignant. All lesions (100%) were correctly report as benign or malignant in the report of the CEUS examination.

CONCLUSION

CEUS can be helpful in the differentiation of benign and malignant focal liver lesions in patients after liver transplantation and can be used in clinical management of focal liver lesions.

Diagnostic accuracy of contrast-enhanced ultrasound (CEUS) in monitoring vascular complications in patients after liver transplantation - diagnostic performance compared with histopathological results

PURPOSE

To analyse the diagnostic performance of contrast-enhanced ultrasound (CEUS) in patients with vascular complications and transplant rejection compared to histopathological results.

MATERIALS AND METHODS

Our study consisted of 45 retrospectively analysed patients that underwent liver transplantations between January 1993 and December 2015 and developed post-transplant vascular complications with transplant rejection. CEUS examinations took place between September 2006 and December 2015. CEUS findings were correlated with histopathological results.

RESULTS

CEUS showed a sensitivity of 61.5%, a specificity of 100.0%, a positive predictive value (PPV) of 100.0% and a negative predictive value (NPV) of 86,5% in the detection of vascular complications with post-transplant rejection. 5 examinations were reported as normal whereas the histopathological result showed a transplant rejection (false-negative).

CONCLUSION

CEUS might be a useful additional non-invasive technique for the assessment of vascular complications with post-transplant rejection in patients after liver transplantation.

Diagnosis of perinephric retroperitoneal lymphangioma supported by contrast-enhanced ultrasound (CEUS)

Lymphangiomas are a rare condition, which are characterized by multiple cystic lesions of a single or multiple organs that are thought to originate from intrauterine atypically distended and connected lymphatic tissue. We describe a case of a 56 years old woman with the final diagnosis of a perinephric lymphangioma. With the use of contrast-enhanced ultrasound (CEUS) it was possible to add valuable diagnostic information regarding the extent of the lymphangioma to surrounding tissue without the necessity to use additional ionizing radiation or nephrotoxic contrast agents.

MRI and contrast enhanced ultrasound (CEUS) image fusion of renal lesions

Ultrasound is a common and established imaging method for the initial characterization of renal lesions. The widespread used Bosniak classification (I-IV) classifies renal lesions in five individual groups using contrast-enhanced computer tomography (CE-CT), magnetic resonance imaging (MRI) and/or contrast-enhanced ultrasound (CEUS) imaging criteria. For complex pathologies, CEUS/MRI image fusion is a novel imaging technique for the differentiation of benign and malignant renal lesions. Compared to CE-CT and MRI alone, ultrasound image fusion offers the additional possibility of being a real-time imaging technique that can be used together with other cross-sectional imaging techniques.This article describes the newest possibilities of image fusion with CEUS and MRI in detection and characterization of unclear renal lesions.

Malignancies after liver transplantation: Value of contrast-enhanced ultrasound (CEUS)

PURPOSE

To evaluate the sensitivity and specificity of contrast-enhanced ultrasound (CEUS) and computed tomography (CT) in the diagnosis of malignancies after liver transplantation.

MATERIALS AND METHODS

A total of 23 patients with suspicious liver masses after liver transplantation with initial imaging series between September 2006 and September 2015 were statistically analysed. CEUS and CT were compared in their diagnosis of malignancy with CT being the gold standard. Out of 23 patients 9 patients showed malignant masses in CT, which could also be detected in 7 out 9 of cases using CEUS.

RESULTS

CEUS showed a sensitivity of 77.8%, a specificity of 100.0%, a positive predictive value (PPV) of 100.0% and a negative predictive value (NPV) of 87,5% in comparison with CT being the gold standard. In 2 cases CT showed a malignancy, contrary to the CEUS examination that was reported as normal.

CONCLUSION

CEUS seems to be an alternative option for the evaluation of malignant masses in liver transplant patients. CEUS shows a high specificity and PPV in the detection of malignant liver masses.

Comparison of magnetic resonance imaging (MRI) and contrast-enhanced ultrasound (CEUS) in the evaluation of unclear solid renal lesions

PURPOSE

To compare the sensitivity and specificity of contrast-enhanced ultrasound (CEUS) and magnetic resonance imaging (MRI) in the evaluation of unclear renal lesions to the histopathological outcome.

MATERIALS AND METHODS

A total of 36 patients with a single unclear solid renal lesion with initial imaging studies between 2005 and 2015 were included. CEUS and MRI were used for determining malignancy or benignancy and initial findings were correlated with the histopathological outcome. Out of the 36 renal masses a total of 28 lesions were malignant (77.8%) and 8 were found to be benign (22.2%). Diagnostic accuracy was testes by using the histopathological diagnosis as the gold standard.

RESULTS

CEUS showed a sensitivity of 96.4%, a specificity of 100.0%, a positive predictive value (PPV) of 100.0% and a negative predictive value (NPV) of 88,9%. MRI showed a sensitivity of 96.4%, a specificity of 75.0%, a PPV of 93.1% and a NPV of 85.7%. Out of the 28 malignant lesions a total of 18 clear cell renal carcinomas, 6 papillary renal cell carcinomas and 4 other malignant lesions, e.g. metastases, were diagnosed. Out of the 8 benign lesions a total 3 angiomyolipomas, 2 oncocytomas, 1 benign renal cyst and 2 other benign lesions, e.g. renal adenomas were diagnosed. Using CEUS, 1 lesion was falsely identified as benign. Using MRI, 2 lesions were falsely identified as benign and 1 lesion was falsely identified as malignant.

CONCLUSION

CEUS is an useful method which can be additionally used to clinically differentiate between malignant and benign renal lesions. CEUS shows a comparable sensitivity, specificity, PPV and NPV to MRI. In daily clinical routine, patients with contraindications for other imaging modalities can particularly benefit using this method.

Characterization of histological subtypes of clear cell renal cell carcinoma using contrast-enhanced ultrasound (CEUS)

INTRODUCTION

The aim of this study was to analyze the histological subtypes of clear cell renal cell carcinoma (RCC) examined by means of contrast-enhanced ultrasound (CEUS) and a second generation blood pool agent (SonoVue®, Bracco, Milan, Italy) during the pre-operative phase.

MATERIALS AND METHODS

29 patients with histologically proven subtypes of clear cell RCC were examined. A total of three patients were diagnosed with highly differentiated clear cell RCC, 21 out of 29 cases with moderately differentiated clear cell RCC and five out of 29 patients had insufficiently differentiated clear cell RCC. An experienced radiologist examined the patients with CEUS. The following parameters were analyzed: maximum signal intensity (PEAK), time elapsed until PEAK is reached (MTT), local blood flow (RBF), area under the time intensity curve (AUC) and the signal intensity (SI) during the course of time. For the groups all comparisons are made based on healthy renal parenchyma.

RESULTS

In the clear cell RCC significant differences (significance level p < 0.05) between cancerous tissue and the healthy renal parenchyma were noticed in all four parameters. Therefore, the clear cell RCC stands out due to its reduced blood volume. However, it reached the PEAK reading relatively rapidly and its signal intensity was always lower than that of the healthy renal parenchyma. In the arterial phase retarded absorption of the contrast agent was observed, followed by fast washing out of the contrast agent bubbles.In all three histological subgroups no significant differences were noticed in PEAK and SI. However, the diagrams showed the possible bias, that the group of the insufficiently differentiated clear cell RCC had the highest PEAK-value and the highest signal intensity when compared with highly and moderately differentiated clear cell RCC.

CONCLUSION

Our study suggests that CEUS may be an additional tool for non-invasive characterisation and differentiation of the three histological subtypes of clear cell RCC. Furthermore, it seems to have an additional diagnostic value in daily clinical.

Comparison of portable ultrasound system and high end ultrasound system in detection of endoleaks

PURPOSE

To compare the value of a portable ultrasound system and a high end ultrasound system in detection of endoleaks after EVAR.

MATERIAL AND METHODS

In this retrospective study, a cohort of 25 patients underwent both standard examination using a portable ultrasound system (Philips VISIQ) and a second examination using a high end ultrasound system (Philips EPIQ 7). The examination included B-mode and color Doppler in detection of endoleaks. Additional the maximum diameter of the aneurysm was measured in two planes (right-left and ventral-dorsal). The gold standard was contrast-enhanced ultrasound (CEUS) in detection of endoleaks.

RESULTS

25 patients were included in the study. Patients were predominantly male (n = 23) with an average age of 73,30±7.82 years (range 54-85). Diameters of the treated aneurysms were in the right-left plane 5,32±1.88 cm and ventral-dorsal 4,99±1.78 cm using the high end system. Diameters of the treated aneurysms were in the right-left plane 5,30±1.82 cm and ventral-dorsal 4,87±1.74 cm using portable ultrasound system. In 80% of the cases CEUS could detect an endoleak. Whereas the high end system could detect in B-mode 40% and color Doppler 45% of the cases an endoleak. The portable system could detect in B-mode 30% and in color Doppler 35% of the cases an endoleak. On both systems in B-mode a false positive endoleak was found on the same patient. All high flow endoleaks, which needed intervention, could be detected on all systems.

CONCLUSION

The high end ultrasound system does not seem to have an additional advantage in the measurement of the aneurysm diameter. Due to a higher resolution, more endoleaks could be detected in B-mode and color Doppler by using the high end system. The presence of small endoleaks could only be detected by using contrast enhanced ultrasound on an high end ultrasound system. High flow endoleaks could be reliable seen on both systems.

Parametric imaging of clear cell and papillary renal cell carcinoma using contrast-enhanced ultrasound (CEUS)

PURPOSE

The aim of this study was to analyse clear cell and papillary renal cell carcinoma (RCC) examined with contrast-enhanced ultrasound (CEUS) and a second generation blood pool agent (SonoVue®, Bracco, Milan, Italy) before clinical intervention.

MATERIALS AND METHODS

A total of 41 patients with histologically proven subtypes of RCC were examined. 29 patients had a clear cell RCC and 12 patients showed a papillary RCC. Average size in the clear cell RCC group was 6.07 cm and 1.88 cm in the papillary RCC group. An experienced radiologist examined all patients with CEUS. The following parameters were analysed: maximum signal intensity (PEAK), time elapsed until PEAK is reached (MTT), local blood flow (RBF), area under the time intensity curve (AUC) and the signal intensity (SI) during the course of time. For both groups all comparisons were made based on healthy renal parenchyma.

RESULTS

In the clear cell RCC significant differences (significance level p < 0.05) between cancerous tissue and the healthy renal parenchyma were noticed in all four parameters. The clear cell RCC showed a significant reduced blood volume. It reached the PEAK reading relatively rapidly and its signal intensity was always lower than that of the healthy renal parenchyma. In the arterial phase retarded absorption of the contrast agent was observed, followed by fast washing out of the contrast agent bubbles.In the papillary RCC group, significant findings as to PEAK and RBF as well as a slightly significant difference as to AUC were recorded. The papillary RCC had a lower blood supply and reached its PEAK reading later. Its signal intensity was also reduced. The signal intensity of papillary NCC was significantly lower compared with clear cell RCC; absorption and washing out of the contrast agent was delayed.

CONCLUSION

CEUS seems to be an useful additional method to clinically differentiate between clear cell and papillary RCC. In daily clinical use, patients with contraindication for other imaging methods, especially the magnetic resonance imaging, might particularly benefit from this method.

Contrast-Enhanced Ultrasound (CEUS) of the Kidneys by Using the Bosniak Classification

Ultrasound is the most used interdisciplinary non-ionizing imaging technique in clinical routine. Therefore, ultrasound has a special value in the diagnosis and monitoring of cystic renal lesions, which can be classified as non-complicated or complicated and by means of occurrence as solitary or multifocal lesions. The Bosniak classification (I-IV) classifies renal cysts in 5 different categories with the help of ultrasound and computed tomography image criteria and is used for decisions of further clinical treatment. Additionally to normal native B-mode sonography, several new methods are in clinical use to improve diagnostic accuracy of unclear cases. Contrast enhanced ultrasound and MRI/CT are able to find and characterize difficult pathologies. This review explains the most important pathologies of cystic lesions of the kidney and stresses the different imaging methods of native B-mode sonography and the new techniques of contrast enhanced ultrasound.