Whole-body MRI without contrast: a new way of understanding the body before symptoms appear

Some medical advances transform treatments. Others change the way we perform surgery or care for patients. But there are some that alter something even more profound: the way in which we are able to understand the human body. Diagnostic imaging falls into this category.

For thousands of years, observing the inside of the body was constrained by an obvious limitation. To find out what was happening inside the body, it was necessary to operate on it or wait for the disease to manifest itself visibly. Medicine advanced on the basis of symptoms, clinical examination and observation.

The advent of imaging techniques radically changed that relationship.

First came X-rays. Then came technologies capable of progressively increasing the depth and quality of the information available: ultrasound, computed tomography, nuclear medicine and magnetic resonance imaging. In just a few decades, we have moved from observing structures to studying tissues and, increasingly, to understanding how the body functions.

For Dr Manuel Moreu Gamazo, a specialist in Radiodiagnostics and head of the Diagnostic Imaging and Interventional Radiology Units at the Publio Cordón Memorial Hospital, few areas of medicine better reflect this transformation. In fact, he believes that “diagnostic imaging is probably the medical speciality that has advanced the most over the last 100 years”.

As part of this evolution, one of the applications that has attracted the most interest in recent years is whole-body magnetic resonance imaging (MRI), a technology that has vastly expanded our ability to observe the body without the need for invasive procedures and which is opening up new possibilities for better understanding a person’s state of health before certain symptoms appear.

How an MRI scan creates an image of the body’s interior

Although most people recognise what an MRI scanner looks like, few really understand what happens during the scan. And yet, the physical principle that enables these images to be generated is surprisingly elegant.

The human body is largely made up of water and contains an enormous number of hydrogen atoms, present both in the water and in other tissues of the body. At the centre of these atoms are particles called protons.

Magnetic resonance imaging makes use of the physical behaviour of these protons — particularly those of hydrogen, which is very abundant in the human body — to generate detailed images of the body’s interior.

When a person enters the machine’s strong magnetic field, some of these protons temporarily align themselves. The system then applies radiofrequency pulses that disrupt this alignment, enabling signals to be captured which are subsequently converted into medical images.

As Dr Moreu explains, “what we do is move the protons, and by doing so we are able to identify the various lesions and structures within the human body”.

When these protons return to their initial position, they release small amounts of energy. This signal is captured and transformed, through complex mathematical and computational processes, into extraordinarily detailed images.

In other words, MRI converts the body’s own physical behaviour into an accurate representation of its interior.

But perhaps the most profound change brought about by diagnostic imaging is not merely technological. As the specialist points out, “thanks to diagnostic imaging, we are gaining access to the human body and are able to see inside it without the need for surgical techniques or more invasive procedures”.

And that idea probably sums up one of the greatest contemporary medical advances.

Much more than just studying one region of the body

Traditionally, MRI is used to study a specific area. Whole-body MRI expands this capability and provides a more comprehensive view of the body within a single scan.

It can now provide information on structures such as the brain, the spine, the bone marrow, the abdomen, the pelvis and the musculoskeletal system, and does so without the use of ionising radiation.

At the Publio Cordón Memorial Hospital, this type of scan forms part of certain advanced health assessment programmes and is integrated into a broader multidisciplinary approach.

As Dr Moreu explains, “we are currently carrying out whole-body MRI scans that allow us to analyse the entire body structure, from the base of the skull – or even the brain – down to the knees or feet, depending on the patient’s height and the time available”, and he adds that “we can do all of this in 50–55 minutes; even if we focus solely on the torso itself—that is, from the neck to the pelvis—it takes 35 minutes”.

When technology also changes the quality of information

Although all MRI scans use the same physical principle, not all have the same capacity to generate diagnostic information.

One of the factors that most influences this ability is the strength of the magnetic field, a quantity measured in teslas (T).

To put this into perspective, the Earth’s natural magnetic field has an intensity of approximately 50 microteslas, and a small domestic magnet typically measures around 0.001 teslas. An advanced 3-tesla MRI scanner operates with a magnetic field thousands of times stronger than that of the Earth.

This means it can detect the signals emitted by the water protons in the body with greater precision and convert them into images with greater detail and higher diagnostic quality.

Although 1.5-tesla MRI scans remain the most widely used standard in clinical practice, 3-tesla systems now represent one of the most advanced technologies available for certain complex diagnostic imaging studies.

At the Publio Cordón Memorial Hospital, these types of studies are carried out using a state-of-the-art 3-tesla MRI scanner designed for advanced whole-body imaging protocols.

This technological advance has been one of the factors enabling MRI to evolve from a tool primarily aimed at visualising structures into a technology capable of providing increasingly sophisticated information about tissues.

However, the medical value of this technology does not lie solely in the anatomical scope it can cover. The real shift occurs when we stop thinking solely in terms of images and start talking about information.

When imaging begins to study tissues, not just anatomy

For years, many advanced scans relied on the use of intravenous contrast to enhance their diagnostic capabilities. Today, the picture is becoming more sophisticated.

New MRI sequences allow us to obtain extraordinarily rich information even without administering contrast in numerous clinical scenarios.

Among these, diffusion sequences stand out, as they analyse how water molecules move microscopically within tissues. This may seem like a highly technical phenomenon, but it has enormous medical utility.

Healthy tissues and certain abnormal tissues organise this movement differently. This difference can help to identify extremely subtle changes and provide information about tissue microstructure even before obvious anatomical abnormalities appear.

This principle now occupies a central place in modern MRI.

The European Society for Magnetic Resonance in Medicine and Biology published the paper ‘ESR Essentials: diffusion-weighted MRI—practice recommendations’ in *European Radiology*, in which it reviews the current role of these sequences and highlights their ability to improve diagnostic accuracy and provide information on tissue behaviour.

This development is progressively expanding the range of information we are able to obtain. As Dr Moreu summarises, today “we no longer simply know whether or not there is a tumour, but we can determine the tumour’s chemical composition, for example, in the brain using spectroscopy, or we can identify whether it is fatty or cystic, gain much more detailed pathological information about that lesion, and carry out increasingly precise staging, which enables us to make a better diagnosis for our patients”.

What it can really contribute to preventive medicine

Talking about advanced preventive medicine does not mean indiscriminately screening for disease. It means having tools that allow us to better understand the state of the body when there is an appropriate medical indication.

In this context, whole-body MRI can provide particularly useful information for identifying certain findings that subsequently require more detailed assessment. Depending on the clinical context and the protocol used, this may include inflammatory changes, musculoskeletal abnormalities, specific findings in deep tissues, or lesions whose nature must subsequently be characterised through further tests.

Furthermore, it can provide reassurance when the scan does not identify any significant findings within the patient’s individual context.

As Dr Moreu explains, it is “a very useful technique because it allows us to carry out an annual or biannual check-up – a very precise check-up, so to speak”.

Naturally, this usefulness must be understood within the appropriate clinical context and not as a universal recommendation. Because detecting an abnormality does not mean establishing a diagnosis.

In the specialist’s words, the technique “identifies this type of lesion, which we will then, of course, need to investigate in greater detail to confirm that it is indeed a tumour and not an incidental finding”. Interpretation remains just as important as observation.

What the scientific evidence says

As with any advanced medical technology, the true value of a scan does not depend solely on what it can do technically, but on the scientific knowledge that underpins when and how to use it.

In this regard, current research reveals particularly interesting findings, although it also calls for a balanced perspective.

A review published in *Cancer Imaging* analysed 6,214 whole-body MRI scans carried out on an asymptomatic population. The authors noted the ability to identify relevant findings, but also pointed out that a significant proportion required further investigation and that many findings did not necessarily correspond to clinically significant disease.

Although there is currently insufficient evidence to recommend whole-body MRI as a single, universal tool for population-based screening, scientific research does point to growing interest when it is integrated into structured medical strategies and its findings are interpreted within the clinical context of each patient and in conjunction with other diagnostic tools.

Another component of an advanced medical assessment

Precisely for this reason, whole-body MRI is not intended to replace a medical check-up or, on its own, answer all questions regarding a person’s health.

Its greatest potential is realised when it is integrated into a broader assessment. In certain advanced, multidisciplinary medical check-up programmes, it can be incorporated as a complementary tool alongside specialised clinical assessment, personal and family medical history, advanced laboratory tests, cardiovascular assessment and other tests aimed at building a more comprehensive picture of a person’s state of health.

Because the most advanced preventive medicine is not about carrying out more tests. It is about understanding better. And perhaps diagnostic imaging is also evolving in that direction.

As Dr Moreu summarises, “the more this technique advances, the more information it provides us with”. This change represents something deeper than a mere technological improvement. It represents the shift from a form of medicine that observes structures to one that is beginning to understand processes.

And perhaps that is one of the greatest achievements of contemporary diagnostic imaging: not only enabling us to see inside the body, but helping us to understand it sooner, more deeply and less invasively than ever before.

The information in this article is provided for general awareness and does not replace an individualised medical assessment.