In case of vesicoureteric reflux which will be inv. of choice:

Ans is 'a' ie MCU n Two techniques are commonly used to detect VUR. The radiocontrast MCU is most commonly used since in addition to showing if provides excellent anatomical details. Isotone radionuclide cystography is more sensitive fordetecting VUR, and causes ten radiatum exposure than the former but provides ten anatomical details. Follow-up screening of pts. Diagnosed to have reflux (on radiocontrast study) may be done by radionuclide cystography, which is also useful for screening siblings for reflux. "SoMost sensitive inv. for VUR is - Radionuclide cystography Inv. of choice for VUR is -- MCU.