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

Application of Contrast-enhanced Ultrasound and Bosniak Classification to the Diagnosis of Cystic Renal Masses

BACKGROUND

The Bosniak classification system based on contrast-enhanced computed tomography (CECT) is commonly used for the differential diagnosis of cystic renal masses. Contrastenhanced ultrasound (CEUS) is a relatively novel technique, which has gradually played an important role in the diagnosis of cystic renal cell carcinoma (CRCC) due to its safety and lowest price.

OBJECTIVE

The aim of the study is to investigate the application value of CEUS and Bosniak classification into the diagnosis of cystic renal masses.

METHODS

32 cystic masses from January 2018 to December 2019 were selected. The images of conventional ultrasound (US), CEUS and CECT from subjects confirmed by surgical pathology were retrospectively analyzed. The Bosniak classification system of cystic renal masses was implemented using CEUS and CECT, and the diagnostic ability was compared.

RESULTS

For the 32 cystic masses, postoperative pathology confirmed 11 cases of multilocular CRCC, 15 cases of clear cell carcinoma with hemorrhage, necrosis and cystic degeneration, 5 cases of renal cysts, and 1 case of renal tuberculosis. The Bosniak classification based on CEUS was higher than that based on CECT, and the difference was statistically significant (P = .024). The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of CEUS were comparable to CECT. There was no significant difference observed in the diagnosis of CRCC (P >.05).

CONCLUSION

CEUS combined with Bosniak classification greatly improves the diagnosis of CRCC. CEUS shows a comparable diagnostic ability to CECT. In daily clinical routine, patients who require multiple examinations and present contraindications for CECT can particularly benefit from CEUS.

Recent Advances in Tracking Devices for Biomedical Ultrasound Imaging Applications

With the rapid advancement of tracking technologies, the applications of tracking systems in ultrasound imaging have expanded across a wide range of fields. In this review article, we discuss the basic tracking principles, system components, performance analyses, as well as the main sources of error for popular tracking technologies that are utilized in ultrasound imaging. In light of the growing demand for object tracking, this article explores both the potential and challenges associated with different tracking technologies applied to various ultrasound imaging applications, including freehand 3D ultrasound imaging, ultrasound image fusion, ultrasound-guided intervention and treatment. Recent development in tracking technology has led to increased accuracy and intuitiveness of ultrasound imaging and navigation with less reliance on operator skills, thereby benefiting the medical diagnosis and treatment. Although commercially available tracking systems are capable of achieving sub-millimeter resolution for positional tracking and sub-degree resolution for orientational tracking, such systems are subject to a number of disadvantages, including high costs and time-consuming calibration procedures. While some emerging tracking technologies are still in the research stage, their potentials have been demonstrated in terms of the compactness, light weight, and easy integration with existing standard or portable ultrasound machines.

A Comprehensive Commentary on the Multilocular Cystic Renal Neoplasm of Low Malignant Potential: A Urologist’s Perspective

Multilocular cystic renal neoplasm of low malignant potential (MCRNLMP) is a cystic renal tumor with indolent clinical behavior. In most of cases, it is an incidental finding during the examination of other health issues. The true incidence rate is estimated to be between 1.5% and 4% of all RCCs. These lesions are classified according to the Bosniak classification as Bosniak category III. There is a wide spectrum of diagnostic tools that can be utilized in the identification of this tumor, such as computed tomography (CT), magnetic resonance (MRI) or contrast-enhanced ultrasonography (CEUS). Management choices of these lesions range from conservative approaches, such as clinical follow-up, to surgery. Minimally invasive techniques (i.e., robotic surgery and laparoscopy) are preferred, with an emphasis on nephron sparing surgery, if clinically feasible.

Benefits of contrast-enhanced ultrasonography for interventional procedures

For evaluating unclear tumorous lesions, contrast-enhanced ultrasonography (CEUS) is an important imaging modality in addition to contrast-enhanced computed tomography and magnetic resonance imaging, and may provide valuable insights into the microvascularization of tumors in dynamic examinations. In interventional procedures, CEUS can make a valuable contribution in pre-, peri-, and post-interventional settings, reduce radiation exposure and, under certain circumstances, decrease the number of interventions needed for patients.

Advanced Fusion Imaging and Contrast-Enhanced Imaging (CT/MRI-CEUS) in Oncology

Fusion imaging depicts an innovative technique that facilitates combining assets and reducing restrictions of advanced ultrasound and cross-sectional imaging. The purpose of the present retrospective study was to evaluate the role of fusion imaging for assessing hepatic and renal lesions. Between 02/2011-08/2020, 92 patients in total were included in the study, of which 32 patients had hepatic lesions, 60 patients had renal lesions. Fusion imaging was technically successful in all patients. No adverse side effects upon intravenous (i.v.) application of SonoVue® (Bracco, Milan, Italy) were registered. Fusion imaging could clarify all 11 (100%) initially as indeterminate described hepatic lesions by computed tomography/magnetic resonance imaging (CT/MRI). Moreover, 5/14 (36%) initially suspicious hepatic lesions could be validated by fusion imaging, whereas in 8/14 (57%), malignant morphology was disproved. Moreover, fusion imaging allowed for the clarification of 29/30 (97%) renal lesions initially characterized as suspicious by CT/MRI, of which 19/30 (63%) underwent renal surgery, histopathology revealed malignancy in 16/19 (84%), and benignity in 3/19 (16%). Indeterminate findings could be elucidated by fusion imaging in 20/20 (100%) renal lesions. Its accessibility and repeatability, even during pregnancy and in childhood, its cost-effectiveness, and its excellent safety profile, make fusion imaging a promising instrument for the thorough evaluation of hepatic and renal lesions in the future.

Contrast-Enhanced Ultrasound (CEUS) for Follow-Up of Bosniak 2F Complex Renal Cystic Lesions-A 12-Year Retrospective Study in a Specialized European Center

Bosniak 2F renal cystic lesions feature morphologic characteristics between Bosniak I and III categories, the majority of which remain benign. However, a minor part of Bosniak 2F lesions may progress to malignancy. The purpose of this study was to assess Bosniak 2F cystic lesions during follow-up examinations by CEUS. One-hundred-and-twelve out of 364 patients with Bosniak 2F lesions underwent follow-up CEUS examinations between February 2008 and February 2020. Twelve out of 364 patients underwent renal surgery without follow-up CEUS. The progression rate of Bosniak 2F renal lesions detected by CEUS accounted for 7.1% (8/112 patients) after a mean of 12.9 months. The first follow-up CEUS revealed 75% of progressions (6/8), the remaining 25% (2/8) of progressions were detected during second follow-up CEUS. Underlying clear-cell renal cell carcinoma was histopathologically validated in 5/8 progressive complex cystic renal lesions. Stable sonomorphologic features were observed in 92.1% (104/112 patients). CEUS depicts a promising diagnostic imaging modality in the diagnostic work-up and follow-up of complex renal cystic lesions at higher spatial and temporal resolutions than CT or MRI. Its excellent safety profile, its easy and repeatable accessibility, and low financial costs render CEUS an attractive and powerful alternative imaging tool for monitoring complex renal cystic lesions.

Ultrasound 2020 - Diagnostics & Therapy: On the Way to Multimodal Ultrasound: Contrast-Enhanced Ultrasound (CEUS), Microvascular Doppler Techniques, Fusion Imaging, Sonoelastography, Interventional Sonography

BACKGROUND

 Ultrasound as a non-ionizing imaging procedure is one of the most important diagnostic procedures in everyday clinical practice. The technology is widely used. Due to constant technical innovations, sonographic procedures, such as contrast-enhanced ultrasound (CEUS), sonoelastography, new microvascular Doppler modalities and, as an example of interventional procedures, sonographically controlled microwave ablation (MWA), are becoming increasingly important in diagnostic imaging and interventional medicine alongside CT and MRI. However, this also requires greater expertise, specialization and qualification on the part of users.

METHOD

 This review article provides information about the range of technical innovations in ultrasound in recent years and describes the underlying technology, the clinical applications, and their diagnostic value. These are presented in the context of the current literature, explaining their advantages and disadvantages and their clinical value.

RESULTS AND CONCLUSION

 Contrast-enhanced ultrasound (CEUS), microvascular Doppler modalities, fusion imaging and elastography complement B-scan ultrasound and conventional Doppler procedures for various problems. Microwave ablation (MWA) has a firm place as an ablative procedure for local tumor therapy in different organ systems and can be performed under ultrasound guidance. Thanks to new developments, the possibilities of ultrasound are now greater than ever. Knowledge of the technology, indications, and possible applications of newer procedures is essential for adequate patient care.

KEY POINTS

  · Contrast-enhanced ultrasound (CEUS) allows an increase in sensitivity and specificity in the assessment of parenchymal lesions.. · CEUS allows the microperfusion to be visualized and quantified. For larger vessels, CEUS is an important instrument in diagnosing endoleak after stenting.. · Microvascular Doppler techniques with clutter suppression algorithms allow a more accurate representation of the smallest vessels than regular color or power Doppler.. · Elastography of the liver in diffuse hepatopathies is a noninvasive diagnostic tool to exclude higher grade fibrosis/cirrhosis.. · Microwave ablation (MWA) also offers sonographically controlled ablation of tumors..

CITATION FORMAT

· Kloth C, Kratzer W, Schmidberger J et al. Ultrasound 2020 - Diagnostics & Therapy: On the Way to Multimodal Ultrasound: Contrast-Enhanced Ultrasound (CEUS), Microvascular Doppler Techniques, Fusion Imaging, Sonoelastography, Interventional Sonography . Fortschr Röntgenstr 2021; 193: 23 - 32.

Comparison of Diagnostic Medical Sonography, Computed Tomography, Magnetic Resonance Imaging, and Contrast-Enhanced Ultrasound in the Investigation of Renal Lesions

This review explores the classification and evaluation of suspicious renal lesions across several radiologic imaging modalities. Diagnostic medical sonography (DMS), computed tomography (CT), magnetic resonance imaging (MRI), and contrast-enhanced ultrasound (CEUS) are the primary modalities used to investigate questionable lesions found within the kidneys. Renal masses may range from completely benign to malignant. They are classified based on many different features and characteristics. These lesions may be simple cystic, complex cystic, or solid in nature. Masses may also exhibit varying degrees of vascularity, septations, and calcifications. The discussed imaging modalities have varying strengths, limitations, and implications for use. Imaging techniques may be used independently or in conjunction to best diagnose and treat a patient with a suspicious renal mass. The aim of this review was to describe the diagnostic value of the imaging modalities (DMS, CT, MRI, and CEUS) and their role in the evaluation of suspicious renal lesions.

[Reliable diagnosis of cystic renal lesions]

CLINICAL/METHODICAL ISSUE

Cystic renal lesions are commonly seen during routine ultrasound examinations of the abdomen.

STANDARD RADIOLOGICAL METHODS

Some cystic renal lesions cannot be sufficiently characterized using native ultrasound. In these cases additional imaging might be necessary.

METHODICAL INNOVATIONS

Contrast-enhanced ultrasound (CEUS) is a reliable imaging modality to characterize cystic renal lesions. Contrast enhancement of septations and the cystic wall are visualized in high resolution. This information helps to categorize the cystic renal lesions applying the CEUS Bosniak classification. This classification helps to estimate the probability of a malignant etiology of cystic renal lesions.

PERFORMANCE

Using CEUS, cystic renal lesions can be characterized with a high sensitivity and specificity.

ACHIEVEMENTS

The advantages of CEUS include that there is no effect on the function of the kidneys or the thyroid gland and no radiation exposure. In some cases, additional cross-sectional imaging is necessary to optimize diagnostic accuracy.

PRACTICAL RECOMMENDATIONS

CEUS is a helpful imaging modality to characterize cystic renal lesions, to avoid unnecessary follow-ups and to detect malignant cystic renal lesions.

[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.

Fusion Imaging of Contrast-enhanced Ultrasound With CT or MRI for Kidney Lesions

AIM

To evaluate the feasibility of ultrasound (US) computed tomography (CT) or magnetic resonance imaging (MRI) fusion imaging (FI) for localization and assessment of kidney lesions.

MATERIALS AND METHODS

Twenty-eight patients with kidney lesions previously detected on CT or MRI were included in this retrospective study. All 28 patients with kidney lesions, which were indefinable (42.9%) or hard to localize (57.1%) on gray-scale US alone, underwent FI of US with CT/MRI datasets. In 23 (82%) patients with indeterminate kidney lesions, FI including contrast-enhanced US was conducted.

RESULTS

FI was successfully performed in 25 out of 28 (89.3%) patients. FI with contrast-enhanced US was able to clarify the previously detected kidney lesions in 21 out of 23 patients (91.3%).

CONCLUSION

FI is a feasible technique for localizing kidney lesions that are hard to define by grayscale US alone and the additional application of contrast-enhanced US is useful in clarifying indeterminate CT or MRI findings.

Abdominal applications of ultrasound fusion imaging technique: liver, kidney, and pancreas

Fusion imaging allows exploitation of the strengths of all imaging modalities simultaneously, eliminating or minimizing the weaknesses of every single modality. Ultrasound (US) fusion imaging provides benefits in real time from both the dynamic information and spatial resolution of the normal US and the high-contrast resolution and wider field of view of the other imaging methods. US fusion imaging can also be associated with the use of different ultrasound techniques such as color Doppler US, elastography, and contrast-enhanced US (CEUS), for better localization and characterization of lesions. The present paper is focused on US fusion imaging technologies and clinical applications describing the possible use of this promising imaging technique in the liver, kidney, and pancreatic pathologies.

Multislice computed tomography/contrast-enhanced ultrasound image fusion as a tool for evaluating unclear renal cysts

Ultrasonography is a generally accepted imaging technique for diagnosing and monitoring cystic renal lesions. The widely used Bosniak classification (I-IV) categorizes renal cystic lesions into five distinctive groups according to ultrasonography and computed tomography (CT) image criteria. For solid renal lesions, determination of vascularity is discriminatory for malignancy in most instances. In indeterminate cases, contrast-enhanced ultrasound (CEUS) and magnetic resonance imaging/CT-ultrasound image fusion are able to detect and characterize difficult pathologies, with superior performance to either technique alone. In contrast to multislice CT (MS-CT), ultrasound image fusion is a real-time imaging technique that can be used in combination with other cross-sectional imaging modalities. This technical note describes state-of-the-art image fusion of CEUS and MS-CT to detect and characterize unclear renal pathologies.

Quantitative parameters of contrast-enhanced ultrasonography for assessment of renal pathology: A preliminary study in chronic kidney disease

OBJECTIVE

To assess the severity of renal pathology in patients with chronic kidney disease (CKD) using contrast-enhanced ultrasonography (US).

METHODS

275 patients with CKD who were proven by renal biopsy and 30 healthy adults were examined using conventional US and contrast-enhanced US. Ultrasonic parameters included renal length, cortical thickness, rise time (RT), peak intensity (PI), area under the time-intensity curve (AUC), wash-in slope (WIS) and time to peak (TTP). Based on pathological scores, CKD patients were classified into mild, and moderate to severe CKD groups. The logistic regression analysis and receiver operating characteristic (ROC) curves were used.

RESULTS

PI and AUC differed significantly among the controls, mild and moderate to severe CKD groups (P < 0.05). There was significant difference in PI among the different pathology types (P < 0.05). The multivariate logistic regression analysis showed that PI was associated independently with the severity of renal pathology in patients with CKD (P < 0.05). PI less than 13.87 dB had a certain diagnostic ability, and the sensitivity and specificity were 72.5% and 64.0%, respectively.

CONCLUSIONS

Contrast-enhanced US may be useful for noninvasive assessment of the severity of renal pathology. PI may be potentially valuable for guiding therapy and follow-up in patients with CKD.