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High-resolution ultrasound (US), as a readily available, cost-effective and harmless imaging technique, is appropriately the initial imaging modality for salivary gland lesions. Benign tumors are reported to present with regular and well-defined margins, a homogeneous hypoechoic structure and demarcated vessel distribution, whereas malignant lesions are irregular, heterogeneous and diffusely perfused. Ultrasound and color Doppler features of benign and malignant salivary gland lesions overlap, and many benign tumors, particularly pleomorphic adenomas, may appear irregularly shaped, with a heterogeneous echo-structure indistinguishable from a malignant lesion. Often skilled US operators are not always able to differentiate benign from malignant lesions. The introduction of US contrast agents has allowed further perspectives in the possible improvement of lesion characterization, and the emergence of US elastography, an innovative tool for assessing lesion stiffness/elasticity characteristics, has been advocated for differentiating salivary gland lesions. When lesions are atypical on US, contrast-enhanced magnetic resonance (MR) imaging is usually the definitive imaging modality. We present a current review of benign and malignant parotid gland tumors with emphasis on the role of multiparametric US and MR imaging.

Purpose: The main objective was to assess the effectiveness of contrast-enhanced ultrasonography (CEUS) in the diagnosis of upper urinary tract malignancies by comparing with multidetector computed tomographic urography (MDCTU) and magnetic resonance urography (MRU). Secondary objectives were to compare the tumor size measured with CEUS, MDCTU and MRU and to assess the usefulness of CEUS in distinguishing high-grade tumors from low-grade ones. Materials and Methods: In connection with this prospective study carried out from January 2009 to September 2011, 18 patients underwent MDCTU or MRU, grayscale ultrasonography (US), color Doppler ultrasonography and CEUS followed by surgery and histological examination of the specimen. Quantitative analysis was performed using perfusion software. Time intensity curves were extracted and the following parameters were considered: wash-in time, time-to-peak, maximum signal intensity and wash-out time. Results: Grayscale US identified 15/18 lesions; color Doppler showed no flow signal in 8 lesions, low color signal in 9 lesions and an intense color signal in 1 lesion; CEUS identified 17/18 lesions with the undetected lesion being the smallest one (1.2 cm) located in the upper pelvicalyceal system. Semi-quantitative analysis produced different data for high-grade and low-grade urothelial cell carcinoma (UCC). All detected upper urinary tract masses were UCCs. MRU, MDCTU and grayscale US overestimated the tumor size, while CEUS was the most accurate. Conclusion: CEUS is useful for evaluating upper urinary tract masses as this method permits differentiation between high-grade and low-grade tumors as well as distinction of the tumor from the adjacent structures and accurate mass measurements.

Angiogenesis is the basis for neoplastic growth in human tissues. Nevertheless, neovascularization may be present both in benign and malignant lesions. Although microvascular density assessment is a useful tool for the study of neoplastic vascularization, it cannot be used on a large scale because of the invasiveness of the method. When contrast-enhanced ultrasonography (CEUS) was introduced in clinical practice, the initial results in the field of breast lesions were disappointing because differentiation between benign and malignant masses was not possible. Magnetic resonance imaging (MRI) assessment of the microvascular features was therefore immediately accepted because of the higher diagnostic accuracy. However, in the last decade the sensitivity and specificity of CEUS have greatly improved due to the development of more sophisticated ultrasound (US) equipment, the introduction of second-generation contrast agents and the development of dedicated software able to perform quantitative analysis. This literature review compares the main results reported in the literature regarding the use of CEUS for the characterization of neoplastic lesions of the breast. All the authors agreed that malignant lesions show early wash-in with more intense enhancement and fast wash-out in comparison with benign masses. However, there is still no observer agreement regarding vascularization patterns, and different classifications are proposed. The conclusion of this literature review is therefore that the clinical role of CEUS in the diagnostic process and in follow-up is still to be clearly defined.Die Angiogenese ist die Ursache für neoplastische Wucherungen im humanen Gewebe. Doch die Gefäßneubildung kann sowohl bei gutartigen als auch in malignen Herdbefunden auftreten. Obwohl die Bestimmung der mikrovaskulären Dichte ein nützliches Mittel für die Untersuchung der neoplastischen Gefäßneubildung ist, kann diese invasive Methode nicht in größerem Maßstab eingesetzt werden. Mit Einführung der kontrastverstärkten Sonografie (CEUS) in die klinische Praxis waren die ersten Ergebnisse auf dem Gebiet der Herdbefunde der Brust enttäuschend, da eine Unterscheidung zwischen gutartigen und malignen Raumforderungen nicht möglich war. Wegen der höheren diagnostischen Genauigkeit wurde die Bestimmung der mikrovasalen Merkmale durch Magnetresonanz-Tomografie (MRT) sofort anerkannt. Im letzten Jahrzehnt haben sich jedoch die Sensitivität und Spezifität der CEUS durch die Entwicklung einer technisch ausgereiften Ultraschall(US)-Ausstattung, durch die Einführung von Kontrastmitteln der zweiten Generation und durch den Aufbau einer geeigneten Software für die quantitative Analyse deutlich verbessert. Dieser Literaturüberblick vergleicht die publizierten wichtigsten Ergebnisse zur Anwendung von CEUS bei der Charakterisierung neoplastischer Herdbefunde der Brust. Alle Autoren stimmen darin überein, dass maligne Herdbefunde im Vergleich zu gutartigen Raumforderungen einen frühes Wash-in und eine etwas deutlichere Verstärkung sowie eine schnelles Wash-out zeigen. Dennoch gibt es noch keine Übereinstimmung der Beobachter, was die Vaskularisierungsmuster anbelangt, und verschiedene Klassifizierungen werden vorgeschlagen. Deshalb kommt diese Übersicht zu dem Fazit, dass der klinische Stellenwert von CEUS für die Diagnosestellung und Nachsorge noch eindeutiger definiert werden muss.