[Contrast-enhanced sonography. Therapy control of radiofrequency ablation and transarterial chemoembolization of hepatocellular carcinoma]

[Contrast-enhanced ultrasound (CEUS) and image fusion for procedures of liver interventions]

CLINICAL/METHODICAL ISSUE

Contrast-enhanced ultrasound (CEUS) is becoming increasingly important for the detection and characterization of malignant liver lesions and allows percutaneous treatment when surgery is not possible. Contrast-enhanced ultrasound image fusion with computed tomography (CT) and magnetic resonance imaging (MRI) opens up further options for the targeted investigation of a modified tumor treatment.

METHODICAL INNOVATIONS

Ultrasound image fusion offers the potential for real-time imaging and can be combined with other cross-sectional imaging techniques as well as CEUS.

PERFORMANCE

With the implementation of ultrasound contrast agents and image fusion, ultrasound has been improved in the detection and characterization of liver lesions in comparison to other cross-sectional imaging techniques. In addition, this method can also be used for intervention procedures. The success rate of fusion-guided biopsies or CEUS-guided tumor ablation lies between 80 and 100% in the literature.

ACHIEVEMENTS

Ultrasound-guided image fusion using CT or MRI data, in combination with CEUS, can facilitate diagnosis and therapy follow-up after liver interventions.

PRACTICAL RECOMMENDATIONS

In addition to the primary applications of image fusion in the diagnosis and treatment of liver lesions, further useful indications can be integrated into daily work. These include, for example, intraoperative and vascular applications as well applications in other organ systems.

[Contrast-enhanced ultrasound (CEUS) of the liver : Critical evaluation of use in clinical routine diagnostics]

CLINICAL/METHODICAL ISSUE

Focal liver lesions are common incidental findings in abdominal ultrasound diagnostics.

STANDARD RADIOLOGICAL METHODS

Characterization of focal liver lesions solely based on b‑mode and color duplex is not feasible in all cases.

METHODICAL INNOVATIONS

Using contrast-enhanced ultrasound (CEUS) it is possible to dynamically visualize the vascularization of focal liver lesions, which enables the characterization of benign and malignant liver tumors. The advantages of CEUS are that ultrasound contrast media do not show renal, hepatic or cardiac toxicity and do not influence the thyroid gland. The approach by fusion of CEUS and contrast-enhanced cross-sectional imaging combines the advantages of both imaging modalities.

PERFORMANCE

Using CEUS focal liver lesions can be characterized with a diagnostic accuracy greater than 90%.

ACHIEVEMENTS

The use of CEUS has become an important imaging modality to evaluate unclear liver lesions.

PRACTICAL RECOMMENDATIONS

The use of CEUS provides vital information as a supplement to cross-sectional imaging and it has become an important tool in therapy planning, control and monitoring of malignant liver lesions.

[Possibilities of sonographic image fusion: Current developments]

CLINICAL/METHODICAL ISSUE

For diagnostic and interventional procedures ultrasound (US) image fusion can be used as a complementary imaging technique.

METHODICAL INNOVATIONS

Image fusion has the advantage of real time imaging and can be combined with other cross-sectional imaging techniques.

PERFORMANCE

With the introduction of US contrast agents sonography and image fusion have gained more importance in the detection and characterization of liver lesions.

ACHIEVEMENTS

Fusion of US images with computed tomography (CT) or magnetic resonance imaging (MRI) facilitates the diagnostics and postinterventional therapy control.

PRACTICAL RECOMMENDATIONS

In addition to the primary application of image fusion in the diagnosis and treatment of liver lesions, there are more useful indications for contrast-enhanced US (CEUS) in routine clinical diagnostic procedures, such as intraoperative US (IOUS), vascular imaging and diagnostics of other organs, such as the kidneys and prostate gland.

Evaluation of the diagnostic accuracy of CEUS in children with benign and malignant liver lesions and portal vein anomalies

OBJECTIVE

Comparison of the diagnostic findings of MRI, CT and CEUS in children with benign and malignant and portal venous anomalies of the liver.

MATERIALS/METHODS

Retrospective analysis of the diagnostic findings of CEUS, MRI and CT scans in 56 children (age 0-17 years) with a total of 60 benign and malignant liver lesions and anomalies of the portal vein/perfusion. All patients underwent CEUS using sulphur hexafluoride microbubbles and a multi-frequency probe (1-5 MHz, 6-9 MHz). Cine-loops were stored up to 3 minutes. MRI was performed in 38 lesions. CT was performed in 8 lesions.

RESULTS

Out of the 56 patients 49 liver lesions (48 benign, 1 malignant), 9 anomalies of the portal vein/perfusion and 2 of the biliary system were detected. 16/49 lesions were analyzed histopathologically. Using CEUS, the characterization of the lesions was possible in 45 out of 49 cases. In 32 cases, CEUS provided the exact diagnosis. Only two benign lesions were falsely categorized as malignant.Findings of MRI and CEUS were concordant in 84% of cases (n = 32/38). CEUS considered 1 benign lesion to be malignant. 2 lesions were not detectable and in 3 lesions no definite diagnosis was established using MRI.Findings of CT and CEUS were concordant in 5 of 8 cases. In 21 lesions CEUS as the only imaging modality was found to be sufficient for diagnostics.

CONCLUSION

Despite the restricted indications for using CEUS in children, it offers a high diagnostic detection rate (93%) for characterization of liver lesions and portal vein anomalies.

[Sonographic imaging of the prostate]

Accurate identification of the location of carcinoma in the prostate is essential for long-term therapeutic success, in particular for minimally invasive procedures. In recent years many new positive study results for prostate imaging have been reported which must be compared and evaluated and previous conservative assessments may need to be re-evaluated. In addition, combinations of different imaging techniques are increasingly being used in daily clinical routine. Due to technical advancements in sonographic imaging, such as elastography and contrast-enhanced ultrasound (CEUS), the detection rate of prostate cancer can be increased. An overview of the different imaging modalities and current literature are presented in this article.

Visualization, imaging and new preclinical diagnostics in radiation oncology

Innovative strategies in cancer radiotherapy are stimulated by the growing knowledge on cellular and molecular tumor biology, tumor pathophysiology, and tumor microenvironment. In terms of tumor diagnostics and therapy monitoring, the reliable delineation of tumor boundaries and the assessment of tumor heterogeneity are increasingly complemented by the non-invasive characterization of functional and molecular processes, moving preclinical and clinical imaging from solely assessing tumor morphology towards the visualization of physiological and pathophysiological processes. Functional and molecular imaging techniques allow for the non-invasive characterization of tissues in vivo, using different modalities, including computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, positron emission tomography (PET) and optical imaging (OI). With novel therapeutic concepts combining optimized radiotherapy with molecularly targeted agents focusing on tumor cell proliferation, angiogenesis, and cell death, the non-invasive assessment of tumor microcirculation and tissue water diffusion, together with strategies for imaging the mechanisms of cellular injury and repair is of particular interest. Characterizing the tumor microenvironment prior to and in response to irradiation will help to optimize the outcome of radiotherapy. These novel concepts of personalized multi-modal cancer therapy require careful pre-treatment stratification as well as a timely and efficient therapy monitoring to maximize patient benefit on an individual basis. Functional and molecular imaging techniques are key in this regard to open novel opportunities for exploring and understanding the underlying mechanisms with the perspective to optimize therapeutic concepts and translate them into a personalized form of radiotherapy in the near future.

[Preclinical imaging in animal models of radiation therapy]

CLINICAL/METHODICAL ISSUE

Modern radiotherapy benefits from precise and targeted diagnostic and pretherapeutic imaging.

STANDARD RADIOLOGICAL METHODS

Standard imaging modalities, such as computed tomography (CT) offer high morphological detail but only limited functional information on tumors.

METHODICAL INNOVATIONS

Novel functional and molecular imaging modalities provide biological information about tumors in addition to detailed morphological information.

PERFORMANCE

Perfusion magnetic resonance imaging (MRI) CT or ultrasound-based perfusion imaging as well as hybrid modalities, such as positron emission tomography (PET) CT or MRI-PET have the potential to identify and precisely delineate viable and/or perfused tumor areas, enabling optimization of targeted radiotherapy. Functional information on tissue microcirculation and/or glucose metabolism allow a more precise definition and treatment of tumors while reducing the radiation dose and sparing the surrounding healthy tissue.

ACHIEVEMENTS

In the development of new imaging methods for planning individualized radiotherapy, preclinical imaging and research plays a pivotal role, as the value of multimodality imaging can only be assessed, tested and adequately developed in a preclinical setting, i.e. in animal tumor models.

PRACTICAL RECOMMENDATIONS

New functional imaging modalities will play an increasing role for the surveillance of early treatment response during radiation therapy and in the assessment of the potential value of new combination therapies (e.g. combining anti-angiogenic drugs with radiotherapy).

[Ultrasound-guided image fusion with computed tomography and magnetic resonance imaging. Clinical utility for imaging and interventional diagnostics of hepatic lesions]

Abdominal ultrasound is often the first-line imaging modality for assessing focal liver lesions. Due to various new ultrasound techniques, such as image fusion, global positioning system (GPS) tracking and needle tracking guided biopsy, abdominal ultrasound now has great potential regarding detection, characterization and treatment of focal liver lesions. Furthermore, these new techniques will help to improve the clinical management of patients before and during interventional procedures. This article presents the principle and clinical impact of recently developed techniques in the field of ultrasound, e.g. image fusion, GPS tracking and needle tracking guided biopsy and discusses the results based on a feasibility study on 20 patients with focal hepatic lesions.

[Latest developments in ultrasound of the liver]

Abdominal ultrasound (US) is often the first-line imaging modality used to assess focal liver lesions. Due to various new gray-scaled US techniques, such as tissue harmonic imaging (THI), spatial compounding technique and speckle reduction technique, as well as contrast-enhanced techniques, abdominal ultrasound nowadays has great potential regarding detection and characterization of focal liver lesions. Furthermore, image fusion with computed tomography (CT), magnetic resonance imaging (MRI) and 3D ultrasound will most likely help to improve clinical management before and after interventional procedures. This article illustrates the principles and clinical impact of recently developed techniques in the field of ultrasound.