US President Donald Trump "remains in excellent overall health" after undergoing a "comprehensive executive physical", according to his White House physician.

Captain Sean Barbabella released a memo on Monday that said advanced imaging of the 79-year-old president's heart and abdomen came back "perfectly normal".

He wrote the president underwent the MRI during a physical in October, "because men of his age group benefit from thorough evaluation of cardiovascular and abdominal health".

The release comes as Democrats, including Minnesota Governor Tim Walz, have been pushing for the results of the scan amid concerns about Trump's age in his second term.

In his memo, Barbabella wrote that there was no evidence of arterial narrowing impairing blood flow or abnormalities in Trump's heart or major vessels.

The doctor added that overall, Trump's cardiovascular system "shows excellent health".

Likewise, the doctor, a US Navy emergency physician who served in Iraq and Afghanistan, said results of Trump's abdominal imaging showed that "everything evaluated is functioning within normal limits with no acute or chronic concerns".

The doctor called the scan "standard" for an "executive physical" for someone at Trump's age.

The White House had previously declined to explain why Trump had an MRI during a physical exam in October or say what part of his body was scanned.

Riding aboard Air Force One on Sunday, Trump told reporters that it was "OK with me" to release the results of the MRI.

When pressed by a reporter about which body part the MRI examined, Trump said, "I have no idea. It was just an MRI - what part of the body? It wasn't the brain, because I took a cognitive test and I aced it."

Trump underwent his annual physical screening in April.

In October, he said that he received an MRI at Walter Reed National Military Medical Centre during a visit to the White House, said was part of his "routine yearly checkup".

Trump said at the time that the MRI "was perfect".

In the memo, Barbabella said the purpose of the MRI was preventative, "to identify issues early, confirm overall health, and ensure he maintains long-term vitality and function".

White House Press Secretary Karoline Leavitt read Barbabella's memo during a news briefing on Monday.

"I think that's quite a bit of detail in the effort of transparency," Leavitt said. "The president promised it last night, and we have it delivered today."

Two outside physicians who reviewed the memo told the BBC that MRIs were "not typically standard" for preventive care.

But some people do opt for testing which is outside standard age-based guidelines, says Dr Carla Perissinotto, a geriatrics specialist at the University of California San Francisco.

Likewise, Dr Jeffrey A Linder, chief of general internal medicine at Northwestern University Feinberg School of Medicine, says the memo does not specify whether an MRI or CT scan was performed, making it difficult to know exactly what was done.

Linder says routine anatomical imaging - whether MRI or CT - is generally discouraged in asymptomatic patients because potential risks outweigh the benefits.

And even for executive physicals - which cater to busy professionals and include a host of additional tests - he says it is still uncommon for that imaging to come back "perfectly normal" with no coronary calcification.

Trump has been seen with swollen ankles and bruising on his right hand and has been spotted dozing off during meetings.

In July, the White House said that he had been diagnosed with chronic venous insufficiency, a vein condition that can result in swelling in the legs.