Contrast-enhanced ultrasound (CEUS)
Contrast-enhanced ultrasound (CEUS) employs ultrasound contrast agents (UCAs) to enhance imaging resolution and provide real-time assessment of tissue perfusion. UCAs consist of microbubbles filled with gas, encapsulated by a lipid or protein shell. These microbubbles are small enough to pass through capillaries, enhancing the echogenicity of blood and tissues. During a CEUS procedure, a baseline ultrasound scan is performed to establish tissue morphology. Then, UCAs are injected intravenously, and ultrasound imaging is continued to monitor their distribution within the vasculature and tissue parenchyma. The microbubbles resonate in response to ultrasound waves, producing strong echogenic signals. The timing and intensity of contrast enhancement provide valuable information about tissue vascularity and perfusion dynamics. By assessing the wash-in and wash-out phases of UCAs, clinicians can differentiate between normal and abnormal tissue perfusion patterns. For instance, malignant tumours often exhibit rapid wash-in and wash-out kinetics, whereas benign lesions may demonstrate more prolonged enhancement patterns. [65] As described by Su et al, CEUS is an emerging technology that combines vascular ultrasound with the administration of intravenous contrast agents and thus provides accuracy in, for example, assessing and finding even small-lumen perforating vessels in flap planning. This modality has been shown to have high sensitivity and specificity in finding perforating vessels in anterolateral thigh flaps (ALT) and deep inferior epigastric perforator flaps (DIEP). [54]