"唯器官变化论" can be translated into English as "the theory of solely emphasizing organ changes" or, more concisely, "organocentric change theory" (though the latter is a bit more creative and may not be a widely established term; it conveys the idea of focusing centrally on organ changes).
The first option, "the theory of solely emphasizing organ changes," is more literal and clear in its meaning, highlighting that the theory places exclusive or primary emphasis on changes in organs.