Scan Ready · Modality education
Different tests. Different clinical questions.
No modality is best for every condition. Understand what each test can show, how to prepare and what to discuss with your referring doctor.
Educational information, not a diagnosis; local protocols and clinician assessment determine imaging.
CT & CT angiography
Fast cross-sectional views using X-rays
- Common uses
- Often useful for acute adult abdominal problems, complex fractures, lungs and selected vessel questions. CT protocols differ: noncontrast, IV contrast, HRCT, CTA and low-dose CT are not interchangeable.
- Limitations & alternatives
- Radiation exposure and contrast risks must be justified. CT is not the first test for every symptom; ultrasound or MRI may better answer a particular question.
- Preparation
- Bring the referral and earlier scans. Contrast scans may need kidney-function and previous-reaction checks. Follow appointment-specific fasting instructions; do not stop medicines yourself.
- Safety & pregnancy
- CT uses ionizing radiation. Tell staff about possible pregnancy, kidney disease and previous contrast reactions. Necessary CT is not automatically excluded in pregnancy: the clinician weighs benefits and risks.
MRI, MRA & MRV
Detailed soft-tissue views using a magnet
- Common uses
- Brain, spinal cord, ligaments, liver, bile ducts and prostate questions often benefit from tailored MRI. MRA examines arteries and MRV veins; contrast is not required for every protocol.
- Limitations & alternatives
- Longer and sensitive to movement. Some implants need special conditions or prevent scanning. MRI is not a reason to delay emergency treatment.
- Preparation
- Bring earlier scans and implant details. Complete metal/implant safety screening; discuss claustrophobia or sedation before the visit. Fasting depends on the protocol.
- Safety & pregnancy
- MRI has no ionizing radiation, but implant compatibility must be checked. Gadolinium may require kidney assessment; it is generally avoided in pregnancy unless essential. Tell staff about pregnancy and prior reactions.
Ultrasound & Doppler
Real-time views and blood-flow assessment
- Common uses
- Often first for gallbladder, thyroid, pregnancy and many pelvic/pediatric concerns. Doppler evaluates blood flow and suspected limb clots.
- Limitations & alternatives
- Gas, body build and the area examined can limit views. A nondiagnostic scan may need another study selected by the clinician.
- Preparation
- Bring the referral and previous reports. Preparation varies: gallbladder studies may require fasting, pelvic studies may need a full bladder. Confirm with reception; respect any fluid restriction.
- Safety & pregnancy
- Ultrasound uses sound waves, not ionizing radiation; IV contrast is not usual for these studies. Internal pelvic scans need informed consent. Pregnancy and age influence the scan approach.
X-ray
A quick overview of bones or the chest
- Common uses
- Often the initial test for a suspected limb fracture, arthritis or selected chest symptoms. CT may clarify complex bone injury; MRI may show soft tissue or an occult fracture.
- Limitations & alternatives
- A normal X-ray does not rule out all disease. It provides less soft-tissue detail than MRI.
- Preparation
- Remove jewellery over the area and bring prior images. Usually no fasting; follow any special instructions.
- Safety & pregnancy
- Uses ionizing radiation, usually less than CT. Tell staff if pregnancy is possible; the clinical need and body area guide precautions.
Echocardiography
Ultrasound of heart structure and function
- Common uses
- Often first to assess heart pumping, valves and fluid around the heart. Coronary CT answers a different question about coronary anatomy, not a replacement for echo.
- Limitations & alternatives
- Some views are limited; specialist echo, cardiac MRI or CT may follow. This is education, not a claim that every service is offered at the centre—ask reception about availability.
- Preparation
- Routine transthoracic echo usually needs no fasting. Transesophageal or stress echo has different instructions; confirm with the treating team.
- Safety & pregnancy
- Routine echo has no ionizing radiation or usual IV contrast. Special echo tests may involve medicines, contrast or sedation and need separate safety checks.
Pregnancy guidance: ultrasound or MRI is often preferred when it answers the question. Clinically necessary CT/X-ray should not be withheld solely because of pregnancy; the treating team weighs urgency, benefit and risk. ACOG · RadiologyInfo