uchihaMadara
Ultrasound (US) is more feasible than MRI or CT scans. With US, you can get a real-time picture of parasites/worms moving around in open areas. Ultrasoundss are cheaper and safer than high-radiation CTs or high-electro magnetic resonance imaging.
It's not done more due to lack of motivation by physicians. They look for symptoms, deduce which tests to do, consult other specialists, and sometimes look for
parasites when medical history or symtomps strongly point to parasites. Few physicians specialize in parasites, so it may be a lack of recognition as well. But, if an ultrasound exam costs $1,500, many insurance claims will not justify looking for
parasites and place the financial burden on the patient. It could very well be monetary reasons, as well as lack of experience. An ultrasound is cheaper (~$200-300) for the patient if it is necessary for the patient, according to insurance companies that must cover the costs.