Inclusion Criteria:  (a) eligible patients should be 18-year-old or older; (b) patients should have a histologically or cytologically confirmed diagnosis of primary bladder cancer; (c) patients should not have had any surgery, chemotherapy, immunotherapy, or any therapy before CEUS diagnosis.  Exclusion Criteria:  (a) participants with confirmed to have no carcinoma of the bladder; (b) participants with previous pelvic surgery, who had undergone therapy, any bladder surgery, or had received chemotherapy, radiotherapy or immunotherapy; (c) participants diagnosed with tumor recurrence or metastasis; (d) participants who were allergic to ultrasound contrast agents or could not tolerate CEUS examination, for instance, with recent myocardial infarction, angina pectoris, cardiac insufficiency, severe cardiac arrhythmia, a right/left cardiac shunt, severe pulmonary hypertension, uncontrolled systemic hypertension, acute respiratory distress syndrome, or chronic obstructive pulmonary disease.