Inclusion Criteria for BPS group:
1. Be 18 years of age or older and female;
2. Be diagnosed with BPS (persistent or recurrent pain in the bladder area accompanied by at least one other symptom, such as increased pain when the bladder is full, and frequent urination during the day and/or at night, according to the current diagnostic criteria and clinical guidelines, without any of the conditions listed in the "Exclusion Criteria" below);
3. Persistence of symptoms for more than 6 months;
4. Visual analogue scale (VAS) of pain ≥ 4;
5. O'Leary-Sant Interstitial Cystitis questionnaire (IC-Q) score of 12 or more, with pain and nocturia domain scores \>2;
6. Pelvic Pain and Urgency/Frequency Patient Symptom Scale (PUF) \>13;
7. No history of cystoscopy within 2 years.
Exclusion Criteria for BPS group:
1. With proliferative cystoplasty or previous surgery or any pharmacological and non-pharmacological treatment for BPS;
2. Pregnant or lactating women;
3. Contraindications to MRI;
4. Average urine output less than 40 ml or more than 400 ml;
5. Haematuria (more than 1+ in urine dipstick test);
6. Evidence of current urinary tract infection at the time of recruitment;
7. Tuberculosis of the genitourinary system or cancer of the bladder or uroepithelial cancer;
8. Recurrent urinary tract infection;
9. History of hysterectomy, mid-urethral sling, pelvic organ prolapse repair, vaginal delivery or caesarean section, prostate surgery or treatment within 6 months;
10. History of neurological disease such as cerebral infarction, multiple sclerosis, or Parkinson's disease;
11. Reliance on catheterisation; including clean intermittent catheterisation or indwelling catheterisation;
12. Planned rehabilitation therapy affecting bladder function.
Inclusion Criteria for Control group:
1. Be 18 years of age or older and female;
2. With symptoms of bladder pain (defined as persistent or recurrent pain in the bladder area accompanied by at least one other symptom, such as increased pain when the bladder is full, and frequent urination during the day and/or at night) according to current diagnostic criteria and clinical guidelines;
3. Have a pain visual analogue scale (VAS) ≥ 4;
4. Evidence of a current urinary tract infection;
5. Pelvic Pain and Urgency/Frequency Patient Symptom Scale (PUF) \>13;
6. No history of cystoscopy within 2 years.
Exclusion Criteria for Control group:
1. With proliferative cystoplasty or previous surgery or any pharmacological and non-pharmacological treatment for BPS;
2. Pregnant or lactating women;
3. Contraindications to MRI;
4. Average urine output less than 40 ml or more than 400 ml;
5. Tuberculosis of the genitourinary system or cancer of the bladder or uroepithelial cancer;
6. History of hysterectomy, mid-urethral sling, pelvic organ prolapse repair, vaginal delivery or caesarean section, prostate surgery or treatment within 6 months;
7. History of neurological disease such as cerebral infarction, multiple sclerosis, or Parkinson's disease;
8. Dependence on catheterisation; including clean intermittent catheterisation or indwelling catheterisation;
9. Planned rehabilitation that affects bladder function.
