A Subharmonic-Aided Pressure Estimate Technology for Prediction of Response to Systemic Therapy in Gastric Cancer Liver Metastases

Inclusion Criteria:

* Age ≥ 18 years.
* Histologically or radiologically confirmed, initially diagnosed and have not undergone any treatment gastric liver metastasis (GCLM).
* Lesion size ≤ 6 cm (preferably located adjacent to major anatomical structures such as large vessels or bile ducts).
* Lesion depth ≤ 10 cm on ultrasound imaging.
* Planned to receive guideline-recommended first-line systemic therapy.
* The target lesion has not undergone any prior systemic or local treatment, including surgery, ablation, embolization, targeted therapy, or investigational agents, before enrollment.
* Willingness to provide written informed consent.

Exclusion Criteria:

* Inability to cooperate with contrast-enhanced ultrasound or subharmonic imaging examinations (e.g., dyspnea when lying supine or excessive out-of-plane motion).
* Know or suspected allergy to the contrast agent or other contraindications to its use.
* Target lesion not previously evaluated or managed according to standard systemic treatment protocols.
* Clinically unstable condition, advanced-stage disease, or patients with an unpredictable clinical course that may affect treatment tolerance or follow-up.
* Pregnant or breastfeeding women. 6.Inability to understand or comply with the study protocol, including the requirement to complete follow-up visits and examinations.