The research was conducted over ten years and included clinics in Australia, the United Kingdom and the United States.
It found in almost one in ten participants, a previously-undetected primary cancer could be detected after one scan.
Dr Mandy Ballinger, lead researcher at the Garvan Institute in Sydney, said seven per cent of people who were screened picked up a new primary cancer that hadn’t been known about before.
“The findings are very significant,” she said.
“This is the best evidence that we have so far that we can use whole-body MRI in this high-risk cancer population to detect cancers at an early stage."
The study is centred on a hereditary condition known as Li-Fraumeni syndrome.
The disease is caused by a genetic mutation that affects one in 2,500 people.
Dr Ballinger said these patients are more susceptible to cancers anywhere in the body.
"By the time people reach the age of 30, there is a 50 per cent chance that they will have had a cancer by that age. By the time they get to age 70, it's almost 100 per cent chance of developing cancer for females, and it's over 80 per cent for males. So it's a really devastating syndrome for families."
A full-body MRI scan showed Natalie Coutts, a mother of two, has Li-Fraumeni.
Natalie Coutts with her son Benji and father Robert Source: SBS
Cancer has been at the centre of Ms Coutts' family tragedies.
She says over 20 years, the disease has killed her six-year-old nephew Toby, her uncle Terry and sister Rachael.
Her father, Robert, died of leukaemia two years ago.
"In the early 90s my nephew became unwell, and he was diagnosed with a brain tumour and unfortunately he passed away at the age of six,” she said.
“Four years later my uncle was diagnosed with pancreatic cancer at the age of 49, and he unfortunately didn't make it. And then my sister at the age of 29 became unwell in 1998 and she passed away."
Researchers have found full-body MRIs are more effective for people at high genetic risk.
A seven per cent detection rate is more than triple the arte of breast cancer detection in high-risk patients.
Ms Coutts says the study has given her renewed hope.
"It's really difficult but because I'm in the study, with the full body MRI, I just feel that I'm more in control. It happens yearly, I get various other tests as well in conjunction with the study. Having the screening it's just, you know, it's made me a lot more relaxed."
Full body MRIs cost $1,200 and are currently not covered by Medicare.
Dr Ballinger hopes the findings will eventually lead the government to change that.
"Certainly we would be aiming for a submission for a Medicare item number to be able to cover the cost of whole-body MRI in these people that are at extremely high lifetime risk."