What effect will not administering potassium perchlorate before a 99mTc-pertechnetate injection have on the static brain image taken at 1 hour?

When potassium perchlorate is not administered prior to a 99mTc-pertechnetate injection, the consequence is primarily seen in the uptake of the tracer by the thyroid gland. Potassium perchlorate is used to block the uptake of pertechnetate by the thyroid, which prevents the tracer from being taken up by the thyroid gland and also, to some extent, affects other tissues historically known to absorb pertechnetate, such as the salivary glands.

In this scenario, if potassium perchlorate is not administered, the thyroid may exhibit activity, causing increased background activity that can obscure or confuse the interpretation of brain images. However, one relevant aspect is the uptake in the choroid plexus. The choroid plexus typically takes up 99mTc-pertechnetate, which may become more pronounced if the thyroid is actively absorbing the radiotracer.

As a result, the visibility of the choroid plexus on the static brain image could potentially increase, making the brain image interpretation more complex due to the high background activity from the thyroid and possibly other areas. Therefore, the assertion that the choroid plexus may be seen as an effect of not administering potassium perchlorate before the injection