3 Diagnostic Imaging
Learn how to prepare for common diagnostic imaging examinations, recognize key safety and aftercare considerations, and interpret findings in clinical context.
Preparation and interpretation
Before an examination, verify the patient’s identity, the requested study, relevant symptoms, and ability to follow instructions. Ask about possible pregnancy, allergies or previous contrast reactions, kidney disease, medications, and prior imaging. Preparation varies by examination and facility, so follow the specific instructions rather than assuming fasting or medication changes are needed.
A radiologist interprets the images and sends a report to the ordering clinician. Imaging findings must be considered alongside the patient’s history and examination; a finding should not automatically be treated as a diagnosis on its own.
Most routine X-rays need no special preparation. Remove jewelry and other objects that could obscure the image; a gown may be provided. Tell the care team if pregnancy is possible. The patient may need to hold still or briefly hold their breath.
Routine X-rays are painless and ordinarily require no recovery period. Because they use ionizing radiation, the clinical team weighs the expected benefit against exposure and uses appropriate imaging protocols. If contrast is used for a particular X-ray study, follow the study-specific contrast instructions.
Bone generally appears relatively white, air dark, and soft tissues in shades of gray. A fracture may appear as a break or abnormal alignment in bone; interpretation depends on the view and clinical context.
Remove metal that could interfere with the images. Fasting is required for some examinations but not all, so follow the facility’s directions. Before intravenous , report previous contrast reactions, kidney disease, and relevant medical conditions or medications. The care team determines whether kidney-function assessment or other precautions are needed. Do not independently stop a medication such as metformin; follow the clinician’s instructions and local protocol. Tell the care team if pregnancy is possible.
CT produces cross-sectional images. It can show features such as a fracture, organ enlargement, a mass, or a kidney stone. Contrast enhancement describes how tissue takes up intravenous contrast; it can help characterize structures but does not establish a diagnosis by itself.
CT contrast and aftercare
A brief warm or flushed feeling, metallic taste, or urge to urinate can occur during injection and usually passes quickly. Report breathing difficulty, facial or throat swelling, widespread hives, or other sudden severe symptoms immediately. Pain or swelling at the IV site may indicate and should be reported.
Without sedation, most patients can resume usual activities. Drink fluids if advised, particularly after oral barium contrast, and seek advice for persistent symptoms such as severe constipation after barium.
Complete MRI safety screening before entering the scanner area. Report every implant or device, prior surgery, and possible metal fragments, especially in or near the eye. Do not assume an implant is safe or unsafe: the MRI team must confirm the exact device and its conditions for scanning before clearance. Remove metal and electronic belongings. The scanner is noisy, so hearing protection is provided. Remain still and use the call device if uncomfortable.
MRI uses magnetic fields and radio waves, not ionizing radiation. It provides detailed soft-tissue images. Radiologists assess signal patterns and, when used, contrast enhancement. Abnormal signal can indicate many different processes and must be interpreted in context rather than treated as a diagnosis by itself.
MRI contrast and aftercare
Tell the team about kidney disease, a prior gadolinium reaction, and possible pregnancy. The team assesses whether contrast is appropriate and whether additional screening is needed. Reactions are uncommon but can occur; report hives, itching, or other symptoms promptly. If not sedated, patients can generally resume usual activities after the examination.
Preparation depends on the body area. Some abdominal examinations require fasting, while some pelvic examinations require a full bladder. Confirm the specific instructions before arrival. uses sound waves and does not use ionizing radiation.
Most external examinations require no special aftercare, and normal activities can resume immediately. Internal-probe examinations may cause mild discomfort. If sedation is used, follow discharge instructions for recovery and transportation.
can help distinguish a fluid-filled structure from a solid one and assess blood flow with Doppler. A finding such as a cyst or reduced flow requires interpretation by a qualified clinician in light of the full study and symptoms.
Preparation depends on the specific study. Report medications, supplements, allergies, recent illness, and possible pregnancy or breastfeeding. Some tests require changes to food, drink, or medication, so follow the examination-specific instructions. Imaging may begin after a delay and can take place over several hours or more than one day.
uses a , which may be given by injection, swallowed, or inhaled. It shows patterns of tracer distribution, providing information about tissue function as well as anatomy. For example, a bone scan may show areas of increased uptake. Such areas can have several causes and may require correlation with other imaging or tests; uptake alone does not prove cancer or another specific condition.
Unless told otherwise, usual activities can generally resume after the examination. The tracer naturally decays and is often passed in urine or stool; drinking fluids may help clear it. Follow the imaging team’s instructions about contact with others, pregnancy, and breastfeeding, because precautions vary by tracer and examination. Mild injection-site pain or redness should resolve; report persistent or worsening symptoms. Significant reactions are uncommon.
Applying imaging safety and interpretation
Apply these principles to common questions:
For an abdominal , do not assume whether fasting or drinking water is required. Instructions vary: some abdominal studies require fasting, while some pelvic studies require a full bladder. Confirm the exact instructions for the ordered study.
If a patient reports a cardiac device but does not know its model, pause MRI preparation and notify the MRI team. The team must identify and verify the exact device and its MRI conditions before the patient is cleared to enter the scanner area.
A brief warm flush and metallic taste during iodinated-contrast CT can be expected and usually pass quickly. Breathing difficulty, facial or throat swelling, widespread hives, and other sudden severe symptoms require immediate reporting.
Pain and swelling around an IV after CT contrast injection may indicate .
A patient taking metformin should not stop it independently before CT with intravenous contrast. Medication changes should follow individualized instructions from the prescribing or imaging team.
After , follow study-specific instructions, drink fluids if advised, and follow directions about close contact, pregnancy, or breastfeeding. Precautions depend on the and examination.
Increased uptake in one region on a bone scan does not establish a specific diagnosis. It has multiple possible causes and requires clinical correlation; additional tests may be needed.
On a routine X-ray, bone generally appears white or light gray, while air appears dark.