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]