Common Questions Patients Ask About CT Scans and Scores

Doctors order a non-contrast head CT scan right after a patient arrives with sudden weakness, headache, or confusion. The scan shows whether bleeding has occurred inside the brain and helps locate the hematoma. Teams repeat the scan within hours because blood can expand quickly in the first day. A second image often reveals growth that changes the plan for blood pressure control or surgery.

Radiation from one head CT equals roughly 2 millisieverts. This amount matches the background radiation a person receives over eight months from natural sources. The lens of the eye and thyroid receive very little exposure during a head scan. Hospitals keep doses low while still producing clear images measured in Hounsfield units that distinguish fresh blood at 40 to 90 HU from brain tissue.

Why Repeat Scans Within the First Day

Most hematoma growth happens inside six hours. A repeat CT at six hours or sooner catches expansion before symptoms worsen. Studies show that an increase of 33 percent in volume raises the chance of poor outcome. The ABC2-SPH score uses the later scan if it shows larger volume or new intraventricular blood. The treating team decides the exact timing based on the patient’s Glasgow Coma Scale and blood pressure readings.

Radiation Dose in Everyday Terms

A single head CT delivers about 2 mSv. For comparison, a chest X-ray gives 0.1 mSv and a flight from New York to London gives 0.1 mSv. The risk of future cancer from one scan remains below one in 2000 for adults. Children and pregnant patients receive extra shielding. Radiologists adjust tube current in milliamperes to limit dose while keeping image noise low enough to measure hematoma borders accurately.

Why Volume Numbers Differ Between Hospitals

Two radiologists may draw slightly different borders around the same bleed. The ABC/2 method multiplies length, width, and height then divides by two. A 5-millimetre shift in any diameter can change calculated volume by several millilitres. Software tools that perform planimetry sometimes give 10 percent lower numbers than manual ABC/2. Location matters too: deep bleeds near the basal ganglia compress tissue differently than lobar bleeds. The treating team reviews images directly rather than relying on one reported number.

How the ABC2-SPH Score Can Change

The ABC2-SPH mortality score starts with five factors: age, Glasgow Coma Scale on arrival, hematoma volume in millilitres by ABC/2, presence of intraventricular hemorrhage, and deep versus lobar site. A repeat CT may show larger volume or new intraventricular extension, which raises the score. Neurologic decline can lower the Glasgow Coma Scale and push the estimate higher. Scores therefore reflect a moment in time. The treating team tracks trends and updates families as new data arrive.

• Age over 80 adds points to the ABC2-SPH score.
• Glasgow Coma Scale below 9 signals higher 30-day mortality risk.
• Hematoma volume above 30 millilitres increases the score.
• Intraventricular blood adds one point regardless of volume.
• Deep location near the thalamus or basal ganglia adds risk compared with lobar sites.
• Repeat imaging within 24 hours often changes at least one variable.

What “Cannot Exclude” Means in a Report

Radiologists write “cannot exclude” when an image does not give 100 percent certainty. Small amounts of blood along the tentorium may look like beam-hardening artifact. A thin extra-axial collection might represent either acute blood or chronic fluid. The phrase tells the clinical team to weigh the finding against the patient’s story and laboratory results. It does not mean the diagnosis is present; it means the scan alone cannot rule it out. The treating team integrates this language with the neurologic exam.

“Clinical Correlation Recommended” Explained

This phrase reminds readers that images form only one part of the picture. A 15-millilitre thalamic bleed may look stable on CT but produce profound weakness if it presses on the internal capsule. Conversely, a large frontal hematoma may cause only mild confusion if the patient has good brain reserve. The report therefore defers final judgment to the bedside team. The ABC2-SPH score supplies a population-based estimate, not a personal prediction. The treating team combines the score, serial exams, and repeat imaging to guide decisions.

Evidence behind the ABC2-SPH score comes from large observational cohorts. No single number replaces bedside judgment. Hematoma volume measured on CT remains an estimate because blood mixes with brain tissue at the edges. Small measurement differences of 5 millilitres can shift a borderline score. Families should ask the treating team how the latest scan and clinical findings fit together for their relative.

Repeat imaging helps because expansion occurs in about one-third of patients in the first 24 hours. Yet even stable scans do not guarantee a fixed outcome. Swelling peaks later, and medical complications can still arise. The score therefore serves as one data point among many. The treating team updates the picture hourly with vital signs, laboratory values, and neurologic checks.

Radiation risk stays low for a head CT, yet teams limit scans to those that change management. A follow-up image at 24 hours often guides the decision to continue intensive care or begin comfort measures. The phrase “clinical correlation recommended” underscores that the scan is a tool, not the final answer. The treating team translates every report into language that matches the patient’s individual course.