New flutemetamol F18 formulation to see if it works as well as current for brain amyloid imaging

Inclusion Criteria:

* The participant is at least 50 years of age
* The participant (or a legally authorized representative of the participant) has read, signed, and dated an informed consent form (ICF) before any study procedures are performed.
* The participant has been referred for PET imaging with VIZAMYL (flutemetamol F 18 injection) to estimate amyloid β neuritic plaque density for a) evaluation of suspected AD or other causes of cognitive decline and/or b) assessment of participant eligibility for amyloid β-directed therapy for MCI or mild AD as described in the prescribing information of the therapeutic products.
* The participant is able and willing to comply with all study procedures, including lying supine and still in the PET scanner for at least 60 minutes (approximately 2.5 hours total per imaging session, including a break that will be approximately 30 minutes).
* The participant is surgically sterile (has had documented bilateral oophorectomy, bilateral salpingectomy, hysterectomy, bilateral orchidectomy, and/or vasectomy with confirmation of success), postmenopausal (cessation of menses for more than 1 year), or:

  1. If the participant can become pregnant, the participant must:

     * use a highly effective method of contraception from Screening until 30 days after the last dose of flutemetamol F 18 injection,
     * have negative results for serum or urine human chorionic gonadotropin pregnancy tests performed at Screening and on the imaging days (with the result known before each administration), and
     * agree not to harvest or donate eggs until at least 30 days after the last dose of IMP.
  2. If the participant can impregnate another person and has a sexual partner who can become pregnant, the participant and partner must use adequate contraception from Screening until 90 days after the last dose of flutemetamol F 18 injection, and the participant must agree not to harvest or donate sperm from screening through 90 days after the last dose of flutemetamol F 18 injection. If the participant has a sexual partner who is already pregnant, both the participant and the partner must provide written informed consent, and both must agree to abstain from any form of sexual contact for at least 24 hours after flutemetamol F 18 injection administration, and both must agree that once sexual contact resumes, they will use condoms until at least 90 days after administration of the last dose of flutemetamol F 18 injection.

Exclusion Criteria:

* The participant received or plans to receive another IMP within 30 days before signing informed consent until the end of participation in this study.
* The participant has been treated with, or is being treated with, any medicinal product (drug, biologic, or device) believed to be disease-modifying with regard to MCI or AD (such as an anti-amyloid drug), or initiation of such a medical product cannot be postponed until the participant is no longer in this study.
* Including participation in this study, the participant will have received \>50 mSv total radiation exposure from medical procedures/tests in the past 12 months.
* The participant has had a procedure (therapeutic or diagnostic) involving a radioisotope and it is not possible to wait at least 4 disintegration half-lives before PET imaging.
* The participant has a measured or estimated glomerular filtration rate (eGFR) \<60 mL/min/1.73 m2 based on eligibility serum laboratory assessments.
* The participant has a total bilirubin level \>1.5X the upper limit of normal (ULN) and/or an aspartate transaminase (AST; serum glutamic-oxaloacetic transaminase \[SGOT\]) level \>3X ULN, and/or an alanine transaminase (ALT, serum glutamic-pyruvic transaminase \[SGPT\]) level \>3X ULN based on eligibility serum laboratory assessments.
* Except for the participant's cognitive impairment, the participant has a history or current evidence of any condition, therapy, or other circumstance that might confound the results of the study, interfere with participation for the full duration of the study, or put the participant at undue risk as judged by the investigator, such that it is not in the best interest of the participant to participate in this study.
* The participant has known/suspected structural abnormalities such as a space-occupying lesion or medical devices such as stents, coils, or electrodes in any key region that may interfere with PET imaging or interpretation/analysis of image data.
* The participant is pregnant, planning to become pregnant, or lactating.
* The participant has known or suspected diabetes.
* The participant is not willing or able to fast completely (except for water and any required medications) for at least 6 hours before administration of IMP until after the post-dose blood samples have been collected on each imaging day.
* The participant has known or suspected allergy or hypersensitivity to either IMP or any of their ingredients (including PS80).
* The participant was previously enrolled in this study.