Finding the right tests…
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Finding the right tests…
CT Scan
CT HEAD P/C stands for plain and contrast, meaning your brain gets scanned once before any dye is injected, and again after contrast goes in through a vein in your arm. Comparing the two sets of images lets a radiologist see which structures light up with contrast and which don't, a distinction that matters for telling a tumor, infection, or old scar tissue apart from a fresh bleed. Because iodine-based contrast is used, the centre will ask about kidney function and any past allergic reaction to contrast dye beforehand. The combined scan takes longer than a plain-only CT, since two full passes are recorded instead of one.
There's no single measurement from this scan. A radiologist compares the plain and contrast images side by side and reports which areas enhanced, meaning they took up dye, versus which stayed unchanged. That comparison is the main diagnostic clue your doctor uses, more than any one number.
P/C on this scan means plain and contrast, done as one combined study rather than two separate visits.
- The first pass is a plain, non-contrast scan, giving a baseline picture of your brain and skull - Contrast dye containing iodine is then injected into a vein in your arm - A second pass captures how blood vessels and tissue absorb that dye over the following minutes
Some things, like fresh blood, show up on the plain pass alone. Others, like many tumors, abscesses, or areas of infection, only reveal their true extent once they take up contrast. Seeing both passes side by side helps a radiologist tell these apart with more confidence than either pass alone would give.
Before this scan, the centre will ask about kidney disease, diabetes, and any past reaction to contrast dye or iodine, since these affect whether contrast can be given safely. Let the staff know about any allergies or medications you're taking.
P/C means your brain is scanned twice, once without dye and once after contrast is injected. A plain scan only does the first part, without any dye.
Often yes, since contrast dye can affect kidney function. The centre may check a recent kidney function report before giving contrast, especially if you have diabetes or existing kidney disease.
Most people feel a brief coolness or warmth as the dye goes in through the vein, but it isn't described as painful. Tell the technologist right away if you feel itching, swelling, or breathlessness afterward.
It takes longer than a plain-only scan because two passes are recorded, with time in between for the contrast to circulate. Ask the centre for an estimate when you book, since it varies by protocol.
This page is general information about the test, not medical advice. Your own report's reference ranges apply — please discuss your results with your doctor.
Ask your doctor or the centre about eating and drinking before this appointment, since contrast studies sometimes call for a short fasting period beforehand.
Tell the staff before your appointment. A past reaction doesn't always rule out contrast, but the centre may take extra precautions or discuss alternatives with your doctor.
No. CT HEAD P/C compares plain and contrast images of brain tissue, while a CT angiogram is timed specifically to capture blood vessels as contrast passes through them.