CT

Collimated beam of X-rays which is passed circumferentially around a transverse slice of head and multiple detectors around the slice capture the emerging X-rays to produce multiple images.

These are then put together with the help of a computer to get an axial tomogram

N-acetylcysteine (NAC) is sometimes administered to patients with renal failure who are receiving intravenous contrast media. Let’s delve into the reasons behind this practice

When patients with reduced kidney function undergo imaging studies with intravenous iodinated contrast media (commonly used in CT scans), there has been historical concern about the risk of acute kidney injury (AKI).
However, it’s essential to differentiate between two types of AKI

Contrast-induced AKI (CI-AKI): This occurs specifically due to the administration of contrast media.
Contrast-associated AKI (CA-AKI): This refers to AKI that coincides with contrast media administration but may not be directly caused by it.

The true risk of CI-AKI remains uncertain for patients with severe kidney disease.
Prophylaxis with intravenous normal saline is recommended for patients who have AKI or an estimated glomerular filtration rate (eGFR) less than 30 mL/min/1.73 m² and are not undergoing maintenance dialysis.
In individual high-risk circumstances, prophylaxis may also be considered for patients with an eGFR of 30–44 mL/min/1.73 m² at the discretion of the ordering clinician.

NAC is an antioxidant and mucolytic agent.
Some studies have explored its potential role in preventing contrast-induced nephropathy (CIN) after exposure to iodinated contrast media.

A study by Tepel et al. suggested that NAC might prevent radiographic-contrast-agent-induced reductions in renal function.
Other studies have reported mixed results, and more research is needed to establish its effectiveness.