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

Ans is 'a' ie MCU "Two techniques are commonly used to detect VUR. The radiocontrast MCU is most commonly used since in addition to showing VUR it provides excellent anatomical details. Isotope radionuclide cystography is more sensitive for detccting VUR , and causes less radiation exposure than the former but provides less anatomical details. Follow-up screening of pts. diagnosed to have reflux (on radiocantrast study) may be done by radionuclide cystography, which is also useful for screening siblings for reflux."