After a concussion, different imaging tests may be used to look for signs of more serious injury, such as bleeding, swelling, or skull fracture, rather than to “see” the concussion itself. The most common test in emergency settings is a CT scan. A CT (computed tomography) scan uses X-rays and a computer to create quick, detailed pictures of the brain and skull. It is especially good at detecting acute problems like brain bleeds, bruising of the brain (contusions), and fractures. Because it is fast and widely available, CT is often ordered in the hours right after a head injury if there are red flag symptoms, such as repeated vomiting, worsening headache, confusion, trouble waking up, seizures, or signs of a skull fracture. However, a CT scan exposes you to a small dose of radiation, so doctors try to reserve it for situations where the results will clearly help guide diagnosis or urgent treatment.
MRI (magnetic resonance imaging) is another key tool, particularly when symptoms persist or are more complex. MRI uses a powerful magnet and radio waves to create detailed images of the brain’s soft tissues without radiation. While a CT scan is better for detecting fresh bleeding or fractures, MRI gives a clearer view of subtle brain changes, small areas of bruising, or injuries that might not show up on CT. MRI is more commonly used days to weeks after an injury, especially if a person is not recovering as expected, has unexplained symptoms, or the care team suspects underlying issues such as small areas of damage to brain pathways. Because MRI typically takes longer and can be noisy and confining, it is less commonly used in the immediate emergency situation but can be very helpful when needed to clarify the diagnosis.
In some cases, advanced imaging techniques may be used to look more closely at how the brain is functioning and how its connections are working. One such method is diffusion tensor imaging (DTI), a specialized form of MRI that maps the movement of water along white matter tracts in the brain. These tracts are like communication highways connecting different brain regions. DTI can sometimes detect microstructural changes in these pathways that are not visible on standard MRI, which may be relevant in more severe or persistent post-concussion cases or in research settings. Another form of advanced imaging is functional MRI (fMRI), which measures changes in blood flow related to brain activity. fMRI is rarely used for routine clinical concussion care but is important in research on how concussions affect memory, attention, and other functions over time.
Other imaging options are used more selectively. X-rays of the skull or neck may be ordered if there is concern about fractures in specific bones, but they do not show the brain itself and have largely been replaced by CT for evaluating head trauma. In certain complex or longstanding cases, additional tests such as PET (positron emission tomography) or SPECT (single-photon emission computed tomography) may be considered to assess brain metabolism or blood flow, though they are not standard for most concussions. These tests are generally reserved for specialized centers and particular situations, such as research studies or complicated clinical pictures where standard MRI and CT do not explain ongoing symptoms.
Healthcare providers choose among these imaging tools based on a person’s symptoms, exam findings, age, medical history, and the timing after the injury. For many people with a straightforward concussion and no warning signs of serious brain injury, no scan is needed at all. When imaging is recommended, it is usually because the results could change the immediate plan of care—for example, by revealing a bleed that needs surgery, or confirming that there is no structural damage that would require hospital admission. Understanding the role of CT, MRI, and advanced imaging can help set expectations: most typical concussions will have normal scans, and a normal scan does not mean the injury was “all in your head”—it simply means there is no visible structural damage on the imaging available today.
When imaging is recommended—and when it’s not
Imaging after a concussion is not automatic. Instead, clinicians follow evidence-based rules to decide when a scan is appropriate and when it is unlikely to help. The main question is whether the head injury might have caused a more serious problem—such as a brain bleed, significant swelling, or skull fracture—that would change urgent management. If that risk appears low based on symptoms and examination, the safest and most appropriate choice is often careful observation rather than immediate imaging.
In the minutes to hours after a head injury, a CT scan is the most common test ordered in the emergency department when there are features that raise concern for a dangerous complication. These features often include repeated or persistent vomiting, a severe or rapidly worsening headache, seizures, weakness or numbness in the arms or legs, difficulty speaking, loss of coordination, trouble waking up or staying awake, or clear confusion about time, place, or people. Signs of a skull fracture—such as blood or clear fluid leaking from the nose or ears, bruising around the eyes or behind the ears, or a visible depression in the skull—also strongly push doctors toward ordering a CT for diagnosis.
Age is another factor. Young children, especially infants, can be hard to assess because they may not be able to describe their symptoms clearly. In these cases, doctors rely on behaviors such as excessive sleepiness, irritability, decreased responsiveness, changes in feeding, or a bulging soft spot on the head to decide whether imaging is recommended. Older adults are also more likely to receive a CT after a concussion, particularly if they take blood thinners like warfarin, apixaban, or clopidogrel. These medications increase the risk that even a seemingly mild bump on the head could lead to bleeding in or around the brain, so the threshold for scanning is lower.
In the days and weeks following a concussion, MRI may be considered when symptoms do not follow the usual recovery pattern or when the clinical picture is puzzling. For example, if someone continues to have severe headaches, significant memory problems, new weakness, or difficulties with balance or vision that are not improving, a doctor may order MRI to look for less obvious injuries or other conditions that could mimic or compound concussion, such as small areas of bruising, inflammation, or older strokes. MRI is also more likely to be recommended if new neurological symptoms appear after an initial period of improvement, since that pattern raises concern that something else may be going on.
Advanced imaging such as DTI or functional MRI is generally not recommended for routine concussion diagnosis or short-term management. These techniques are more often used in research or in complex cases referred to specialty centers, for instance when symptoms are unusually severe or long-lasting and standard CT and MRI scans are normal. Even then, clinicians use advanced imaging cautiously, because we are still learning exactly how to interpret many of the subtle changes it can reveal and how those findings relate to symptoms and outcomes.
Despite common belief, most people with an uncomplicated concussion do not need any scan at all. If the person was briefly dazed, may or may not have lost consciousness, but is now alert, oriented, speaking clearly, and improving over the first few hours, and if a careful exam shows no worrying neurological signs, observation is usually preferred. In these situations, the small risk from radiation exposure with CT, the cost, and the possibility of incidental findings that may cause unnecessary anxiety outweigh the potential benefits. Instead, clinicians provide clear instructions about rest, a gradual return to activity, and specific warning signs that should prompt an immediate return for evaluation.
Similarly, imaging is not typically recommended just because symptoms like headache, dizziness, or fatigue are lingering beyond the first days, as long as they are slowly improving and there are no new or focal neurological deficits. These persistent symptoms can be part of the normal recovery process and do not necessarily indicate visible structural damage. Ordering MRI or CT solely to “prove” that a concussion happened, to clear someone for sports in the absence of concerning signs, or because of pressure from work, school, or family is generally discouraged when it will not change the treatment plan.
There are also times when imaging is delayed rather than done immediately. For example, if a person has mild symptoms, a normal examination, and no high-risk features, clinicians may recommend a period of observation at home or in a medical setting. Imaging is then reserved for situations where symptoms worsen, fail to improve as expected, or new red flags appear. In this way, scans like CT and MRI are used strategically, when needed, to support diagnosis and guide care, rather than as a blanket requirement for every head injury.
Ultimately, the decision to order imaging after a concussion is highly individualized. Clinicians weigh the mechanism of injury (such as a high-speed collision, fall from a significant height, or impact with a hard object), the person’s age, medications, past neurological history, and the timing and evolution of symptoms. They use established clinical decision rules to reduce unnecessary scans while still identifying those who truly need immediate imaging. If you are unsure why a scan was or was not recommended, it is appropriate to ask how the decision was made and what signs should prompt reevaluation.
What to expect during common brain scans
Knowing what will happen during a scan can lower anxiety and help you focus on recovery instead of worrying about the equipment. For most people evaluated after a concussion, the most common experiences are CT in the emergency department and, less often, MRI a bit later if symptoms persist or the diagnosis is unclear. Each test has its own steps, sounds, and sensations, but none of them should be painful.
In an emergency setting, a CT of the head is often done quickly soon after arrival. You may be asked to change into a hospital gown and remove metal objects such as glasses, jewelry, hairpins, or hearing aids. A technologist will have you lie on a narrow table that slides in and out of a large, doughnut-shaped machine. Unlike MRI, the CT scanner is short and open at both ends, which helps people who are uncomfortable in tight spaces. The technologist will position your head in a padded cradle to keep it still, sometimes using a soft strap or foam blocks to prevent movement that could blur the images.
During the CT, you will be asked to lie as still as possible and may be told when the table is about to move. The scanner makes quiet humming or whirring noises but is not loud. The scan itself is fast, typically taking only a few minutes, though the whole process from check-in to completion may take longer depending on how busy the department is and whether any other tests or treatments are needed. If a contrast dye is used to better outline blood vessels or certain structures, it is usually given through an IV placed in your arm or hand, and you might feel a brief warm or metallic sensation as it goes in. For many concussion evaluations, contrast is not required.
Most people are awake and able to follow instructions during CT. However, very young children or people who are extremely agitated, confused, or in pain may need extra help to stay still. In those cases, staff may use gentle wrapping, distraction techniques, or, rarely, sedation under close monitoring. After the scan, you can usually return to your room or the waiting area immediately, and a radiologist will interpret the images before sharing the results with the emergency doctor or your main provider.
MRI is a longer and more detailed test and is typically performed after the initial emergency period, especially when symptoms do not improve as expected or the care team wants a more thorough look at the brain to refine the diagnosis. Before an MRI, you will be screened carefully for any metal in or on your body, such as pacemakers, aneurysm clips, cochlear implants, certain tattoos, or metal fragments from old injuries. This is important because MRI uses a very strong magnet. All removable metal objects must come off, and you will usually change into a gown or clothing without metal snaps or zippers.
For the scan, you will lie on a table that slides into a tunnel-like machine. The inside can feel snug, with the top of the scanner close to your face. To help you stay comfortable, you may receive earplugs or headphones to reduce the loud tapping, thumping, and knocking noises the machine makes during image sequences. A small plastic device or padding may be placed around your head to keep it still and improve image quality. If you are prone to anxiety or claustrophobia, tell the staff ahead of time; they can offer strategies such as practicing deep breathing, using a call button, closing your eyes, listening to music when available, or, in some cases, a mild sedative prescribed by your doctor.
An MRI of the brain for concussion-related concerns can take 30 to 60 minutes or more, depending on how many image sets are needed and whether additional sequences or advanced imaging techniques are included. You will hear periodic instructions through a speaker, such as reminders to stay still or notifications that a new series is about to start. Some people find it helpful to count the sounds, mentally review a favorite song, or focus on slow, steady breathing. If contrast is required, an IV will be placed, and the technologist will step in briefly during the exam to inject the contrast agent; this usually causes little more than a cool sensation in the arm.
After MRI, there is no recovery period for most patients—you can usually go home or back to your usual setting right away, unless you received sedation. A radiologist reviews the images and sends a report to the clinician who ordered the scan, who will then explain what was found and how it affects your treatment plan. It is common for standard MRI to look entirely normal even when you have real and bothersome concussion symptoms. That does not mean nothing is wrong; it simply means the microscopic changes affecting brain function are below the level that current imaging can see.
In some specialty clinics or research settings, you may be scheduled for more specialized MRI-based tests such as DTI. With DTI, the procedure feels almost identical to a regular MRI, because it uses the same machine and table. The difference is in the software and the types of image sequences obtained, which track how water molecules move along nerve fibers in the brain. From your perspective, you will still be asked to lie very still in the scanner while it makes a series of loud knocking sounds during the acquisition. These studies are usually added to a standard MRI session, so the total time in the scanner may be somewhat longer.
Other advanced imaging methods, like functional MRI or certain nuclear medicine scans, are used far less often for concussion care and typically only when needed in complex cases. Functional MRI, for example, might require you to perform simple tasks—such as looking at pictures, pressing a button, or thinking about certain words—while images are taken to see which regions of your brain are active. Nuclear medicine tests like PET or SPECT involve an injection of a small amount of radioactive tracer followed by a waiting period and then scanning. Staff will give you specific instructions if any of these are recommended, including how long you should plan to be at the facility and whether you need to avoid certain foods, drinks, or medications beforehand.
Across all of these tests, staff are trained to prioritize safety and communication. You can ask questions at any point, request clarification about what will happen next, or let the technologist know if you are experiencing discomfort. For children, caregivers are often allowed to stay in the room for MRI (without metal objects) to provide reassurance, and child-friendly explanations or distractions like videos may be available. For CT, parents or caregivers may be asked to stand behind a protective barrier during the scan. Understanding each step, from changing clothes and removing metal to lying still and hearing various sounds, can make the process feel more predictable and less intimidating.
How imaging results guide concussion treatment
Once imaging is completed, the results become one piece of a larger puzzle that includes your symptoms, neurological examination, medical history, and the way your condition changes over time. For concussion care, the most important question is usually not just “What does the scan show?” but “How do these findings affect safety, monitoring, and the pace of recovery?” This is why the same CT or MRI result can lead to different treatment plans for different people, depending on age, medications, and overall health.
If CT or MRI shows a clear structural injury—such as a brain bleed, skull fracture, or large contusion—the immediate priority is to prevent the injury from worsening. In these situations, imaging guides urgent decisions like whether you need neurosurgery, admission to an intensive care unit, or close observation in the hospital. For example, a small, stable bleed might be treated with careful monitoring, repeated scans to ensure it is not growing, and strict limits on activity. A larger bleed causing pressure on the brain might require surgery to remove the blood and relieve that pressure. Imaging in these cases also helps clinicians adjust medications, such as reversing blood thinners when safe, and tailor blood pressure and fluid management to protect the injured brain.
When imaging is normal or shows only very mild, nonspecific changes, the focus shifts toward symptom-based management rather than structural repair. A normal scan after a concussion is common and can actually be reassuring: it reduces concern for life-threatening problems and allows the care team to recommend home observation, gradual return to activity, and outpatient follow-up instead of hospital admission. In this context, imaging results help set appropriate expectations. Your provider can explain that, although the scan did not show visible damage, the brain still needs time to recover from functional changes that are too subtle to detect with current techniques. This conversation can validate symptoms while also steering you away from unnecessary procedures or medications that a normal scan makes less likely to help.
Imaging also plays a role in determining how closely and how long you need to be monitored after the initial injury. If a CT scan reveals a small area of bleeding that is not severe enough to require surgery, you may stay in the hospital for neurologic checks and possibly undergo a repeat scan several hours or a day later to ensure the bleed is not expanding. Conversely, if imaging is normal, your provider may still recommend a period of observation—either in the emergency department or at home with a responsible adult—before you resume regular activities. The presence or absence of findings on imaging helps clinicians decide which path is safer and when it is reasonable to transition from hospital-based care to home care.
For people whose symptoms persist beyond the expected recovery window, MRI and, in some settings, advanced imaging can help refine the diagnosis and shape a longer-term treatment plan. For instance, an MRI might reveal small areas of prior injury, microbleeds, or changes in white matter that suggest a more complicated brain trauma than initially recognized. In those cases, clinicians may recommend a more cautious and extended period of cognitive and physical rest, earlier referral to specialists such as neurologists or physiatrists, and more intensive rehabilitation services. Findings from DTI or other advanced imaging—while not used routinely—can, in complex cases, support decisions to involve specialized concussion clinics, cognitive rehabilitation, or vocational therapy to help with return-to-work planning.
Even when imaging does not pinpoint a clear structural cause of ongoing symptoms, a reassuring CT or MRI can still guide treatment by helping rule out other conditions that might require very different approaches. For example, if severe headaches and visual changes raise concern for a brain tumor, stroke, or hydrocephalus, a normal MRI allows the care team to refocus on post-concussion headache management rather than invasive testing. This may lead to tailored medication choices, such as migraine-specific drugs, as well as non-drug strategies like vestibular therapy, vision therapy, or graded exercise programs, knowing that serious structural causes have been reasonably excluded.
Imaging results often influence return-to-play and return-to-work decisions, especially when needed for safety in high-risk environments. In sports, an abnormal scan showing bleeding or significant contusion generally means strict avoidance of contact sports until the injury has fully stabilized and a specialist has cleared participation. Even after the scan has normalized or stabilized, guidelines usually require that symptoms have resolved and that the athlete has successfully completed a stepwise return-to-play protocol. In jobs involving heights, heavy machinery, driving, or weapons, any imaging evidence of acute structural damage may lead to temporary work restrictions while the brain heals, followed by reevaluation with both clinical exams and, occasionally, repeat imaging to document recovery.
Imaging can also help differentiate between concussion-related cognitive or emotional changes and those caused by other neurological conditions, which in turn shapes the type of rehabilitation recommended. For example, if MRI reveals evidence of prior strokes, longstanding small vessel disease, or other patterns of injury, the provider may combine concussion management with strategies to address those conditions—such as controlling blood pressure, treating sleep apnea, or adjusting medications that affect thinking and mood. This integrated approach is important because preexisting brain changes can make concussion symptoms more intense or longer lasting, and imaging gives a clearer picture of what the brain was like before and after the new injury.
In pediatric cases, imaging results affect not only immediate care but also how clinicians and families plan for school and activities. A normal CT in an otherwise healthy child with a typical concussion allows for a home-based recovery focused on rest, a brief reduction in school workload, and a gradual return to sports under supervision. If MRI later shows subtle structural injuries or associated findings such as small hemorrhages, the care team may coordinate with school personnel to arrange longer-term academic adjustments—like shorter school days, extra time for tests, or reduced screen use—and may recommend formal neuropsychological testing to track attention, memory, and learning over time.
For adults with persistent symptoms that affect work performance, imaging can help support or refine referrals to rehabilitation services. A scan that shows additional injuries, such as diffuse axonal injury or small contusions, may prompt early involvement of occupational therapy, speech-language pathology (for cognitive-communication issues), or vocational rehabilitation. These professionals can develop targeted strategies to manage fatigue, memory lapses, and slowed processing speed in real-world settings. Even when images are normal, the documented absence of dangerous structural problems can facilitate a focus on practical coping strategies, mental health support, and structured, graded increases in workload rather than repeated emergency evaluations or unnecessary medical procedures.
In legal and insurance contexts, imaging sometimes intersects with decisions about coverage, disability, and compensation. While a normal CT or MRI does not mean the concussion is insignificant, some insurers or employers may place undue emphasis on imaging findings. Clinicians can use the results, together with documented symptoms and examination findings, to advocate for appropriate accommodations and therapies. In some complex or disputed cases, advanced imaging from specialized centers may be used to add detail to the diagnosis, though interpretation must be done cautiously and always in the context of the full clinical picture.
Throughout the recovery process, imaging findings are repeatedly weighed against how you are feeling and functioning. If new or worsening symptoms develop—such as increased headaches, repeated vomiting, seizures, or new weakness—providers may compare current status with prior scans to see whether repeat imaging is justified. In this way, CT, MRI, and, in select cases, advanced imaging are not standalone answers but tools used at key decision points. They help clinicians decide when to act urgently, when to reassure and observe, when to slow down the pace of activity, and when to bring in additional specialists, always with the goal of protecting the brain and supporting a safe, durable recovery.
Limitations of imaging and warning signs to watch for
Even though ct, mri, and advanced imaging have become more sophisticated, they still have important limitations in the context of concussion. Most concussions do not cause changes that are visible on standard scans, because the injury typically affects how brain cells function and communicate rather than producing large areas of bleeding or obvious structural damage. Current clinical imaging tools are designed primarily to detect things like hemorrhages, fractures, or major contusions, not subtle disruptions in networks of neurons. This is why many people with very real and sometimes disabling symptoms end up with “normal” reports, which can feel confusing or discouraging if you expected the scan to provide a clear diagnosis.
Even advanced imaging techniques such as dti and functional mri, which can sometimes reveal microstructural or functional changes, have constraints. These methods are sensitive but not very specific—meaning that small abnormalities may appear in people without any symptoms, or may not be directly related to the concussion. Differences between scanners, software, and analysis methods also make it difficult to compare results from one center to another. For this reason, advanced imaging is usually reserved for research or very complex clinical situations, and its findings are interpreted cautiously and always in combination with your history, examination, and overall pattern of recovery. It is rarely used to make yes-or-no decisions about return to work, sports, or school.
Another limitation is that imaging offers only a snapshot in time. A normal scan right after injury does not guarantee that problems will not develop later, and an abnormal scan does not always predict how someone will function weeks or months down the line. Small areas of bleeding can look dramatic on ct but cause relatively minor long-term issues, whereas a normal mri does not rule out persistent problems with concentration, mood, or sleep. This is why clinicians emphasize follow-up and symptom monitoring rather than relying on a single scan to forecast the entire course of recovery.
Incidental findings are also common and can complicate the picture. A ct or mri might reveal unrelated issues such as benign cysts, old tiny strokes, or age-related changes that have nothing to do with the concussion. While it is sometimes helpful to know about these findings, they can also create anxiety and lead to further testing that does not change treatment. Providers must carefully distinguish between what is relevant to the recent head injury and what is simply part of the background landscape of the brain. Asking your clinician to explain which findings matter for your diagnosis and which do not can help you avoid unnecessary worry.
Because imaging has these limits, what you feel and how you function remain central to decision-making. A “normal” scan does not mean you should push through severe symptoms, and an “abnormal” scan does not automatically mean your recovery will be poor. Imaging is one tool among many, and it is most useful when needed to answer a specific question—such as whether there is a dangerous bleed or swelling that requires urgent treatment—rather than as a broad screening test for every possible concern after a concussion.
Despite the limitations of imaging, there are clear warning signs after a head injury that should prompt immediate medical attention, whether or not you have had scans before. You should seek urgent evaluation if headaches become suddenly severe or rapidly worse, especially if they feel different from your usual headaches. Repeated vomiting, new seizures, or any episode where you lose consciousness again after the initial injury are particularly concerning. These symptoms can signal bleeding, swelling, or other complications that may not have been present earlier, and a repeat ct or mri may be appropriate to reassess your brain and guide diagnosis and treatment.
Changes in mental status are another red flag. Worsening confusion, difficulty recognizing people or places, trouble following simple instructions, or increasing agitation or unusual behavior should never be ignored. Family members and friends often notice these shifts first, since the person with the concussion may not be fully aware of them. Slurred speech, new trouble finding words, or sudden difficulty understanding language are also reasons to seek emergency care right away. These signs can indicate evolving brain dysfunction that may or may not show up on imaging, but they always require prompt clinical evaluation.
New or progressive weakness, numbness, or clumsiness in the arms, legs, or face are also important warning signs. If you notice that one side of your body feels weak, heavy, or “not working right,” or if your balance suddenly worsens to the point that walking becomes unsafe, you should be evaluated urgently. Vision changes—such as double vision, loss of part of your visual field, or a sudden inability to focus—also merit immediate attention. These symptoms may suggest that the injury is affecting specific brain areas controlling movement, sensation, or sight, and they often prompt clinicians to repeat or add imaging when needed to clarify the diagnosis.
Certain symptoms in children require particular vigilance, since kids may have difficulty explaining what they feel. For infants and toddlers, warning signs include a bulging soft spot on the head, inconsolable crying, refusing to eat or drink, repeated vomiting, excessive sleepiness, or a sudden drop in activity level. In older children, look for increasing confusion, trouble waking, loss of interest in favorite activities, or new problems walking or speaking. Any of these should lead to prompt medical assessment, even if an earlier scan was normal or no imaging was done. Children’s brains are still developing, and close observation—sometimes combined with imaging—is crucial when concerning signs appear.
Mood and behavior changes can be more subtle but are still important to monitor. Feeling a bit irritable or emotional can be part of normal concussion recovery, but sudden, extreme shifts—such as intense agitation, aggression, expressing thoughts of self-harm, or profound withdrawal from others—should not be dismissed as “just stress.” These changes may reflect the brain’s response to injury, emerging mental health issues, or a combination of both. While imaging may or may not show anything new in these situations, these symptoms warrant rapid evaluation by a medical professional, who can decide whether imaging is appropriate and arrange mental health support and safety planning.
Any pattern of symptoms that initially improved and then suddenly worsens is a key warning sign. For example, if headaches, dizziness, and fatigue were gradually getting better over several days and then you develop a sharp increase in pain, new vomiting, or marked confusion, this change in trajectory is more concerning than symptoms that are slowly and steadily improving. In such cases, clinicians often consider repeat ct or mri, especially if you are on blood thinners, have bleeding disorders, or have other risk factors. Trust your instincts and those of people who know you well—if something feels significantly different or “not right,” it is better to be evaluated promptly than to wait and hope it passes.
