Abstract: Background　In clinical gastric ultrasound examinations, a uniform oral dose of 500 mL of ultrasound contrast agent is conventionally administered. Patients with a small gastric volume may experience abdominal distension and other discomforts, while those with a large gastric volume present insufficient gastric wall distension and fold artifacts that interfere with image quality, which can hardly meet clinical requirements.Objective　To investigate the clinical value of an individualized dose of ultrasound contrast agent based on body mass index (BMI) and gender in improving gastric wall visualization and the diagnosis of gastric lesions. Methods　Healthy subjects who underwent gastric ultrasound examinations in the Ultrasound Group of the Department of Health Medicine, the Second Medical Center of PLA General Hospital and the Department of Ultrasound Medicine, Beijing Friendship Hospital, Capital Medical University from January to April 2022 were enrolled for a dosage study to construct a dosage model. Combined with the 5-point Likert scale and ultrasonic image quality, an individualized dosage of contrast agent based on BMI and gender was determined. Patients who underwent gastric ultrasound examinations at the same institution from May 2022 to October 2023 and were subsequently diagnosed with gastric diseases by gastroscopy (and pathological examination) were enrolled and divided into an individualized dose group and a conventional dose group. Gastric wall distension status, as well as diagnostic sensitivity and specificity, were evaluated.Results　Fifty healthy subjects were enrolled in the dose-finding study, and an individualized contrast agent dosage regimen as well as a corresponding dosage model based on BMI, gender and other factors were established. A total of 102 patients were enrolled in the diagnostic efficacy study, including 50 in the conventional dose group (Standard oral contrast agent: 500 mL) and 52 in the individualized dose group (Oral contrast agent: 400 - 1 000 mL). On ultrasound examination, the proportion of patients with "poor" gastric wall distension was 56.0% in the conventional dose group and 9.6% in the individualized dose group. The proportion of "fair" gastric wall distension increased from 32.0% to 51.9%, and the proportion of "good" gastric wall distension increased from 12.0% to 38.5%. Ultrasound image quality analysis showed that gastric wall distension was significantly optimized (P＜0.001). In terms of diagnostic performance, the number of successfully detected lesions in the individualized dose group was 38 cases, accounting for 73.1%, which was significantly higher than that in the conventional dose group (26 cases, accounting for 52.0%)(P=0.028).Conclusion　This preliminary study suggests that an individualized dosing range of gastric ultrasound contrast agent guided by BMI stratification combined with sex may improve gastric ultrasound image quality and increase the detection rate of gastric lesions.