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 A two-stage design was adopted. In the dose-finding study, healthy subjects who underwent gastric ultrasound examination at the Second Medical Center of PLA General Hospital and Beijing Friendship Hospital, Capital Medical University from January to April 2022 were enrolled. Starting from an initial dose of 400 mL, the contrast agent was added in 50 mL increments, and the actual dose was determined when both criteria were met: an abdominal distension Likert score of 1 - 2 and "good" ultrasonic image quality. The associations of the dose with BMI category and sex were analyzed to construct an individualized dosing regimen. In the diagnostic performance study, patients who underwent gastric ultrasound examination at the same institutions from May 2022 to October 2023 and were subsequently diagnosed with gastric diseases by gastroscopy (and pathology) were enrolled and randomly divided into a conventional-dose group (oral administration of 500 mL) and an individualized-dose group (oral administration of 400 - 700 mL according to the above regimen). The rate of good image quality and the lesion detection rate were evaluated and compared.

Results A total of 50 subjects were enrolled in the dose-finding stage, including 28 men and 22 women, with a mean age of (51.7±20.4) years and a mean BMI of (24.4±4.3) kg/m². The established individualized dosing regimen ranged from 400 to 700 mL, with the dose increasing across BMI categories, higher in men than in women, and appropriately reduced in elderly subjects (≥60 years). A total of 102 patients were enrolled in the diagnostic performance stage, with 50 in the conventional-dose group and 52 in the individualized-dose group. No significant differences were found between the two groups in age (50.0±19.7 years vs 45.9±21.5 years, P=0.319), sex composition (male/female: 17/33 vs 13/39, P=0.322), BMI (23.8±4.1) kg/m² vs (22.9±2.8) kg/m², P=0.203, or disease spectrum (P=0.730), indicating that the two groups were comparable. The rate of good image quality in the individualized-dose group was higher than that in the conventional-dose group (38.5% vs 12.0%, P=0.002), and the lesion detection rate was also higher (73.1% vs 52.0%, P=0.046).

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.