Which imaging modality is described as Hyperattenuating/Hypoattenuating?

Which imaging modality is described as Hyperattenuating/Hypoattenuating?

• A. MRI
• B. Ultrasound
• C. Nuclear Medicine (Bone Scan)
• D. CT (Computed Tomography)

Answer: (D)

CT imaging is described by hyperattenuating and hypoattenuating appearances because it measures X-ray attenuation of tissues. Tissues that attenuate more X-rays than surrounding tissues appear brighter on CT, which is called hyperattenuating. Tissues that attenuate fewer X-rays appear darker, or hypoattenuating. This depends on density and composition, with bone being highly hyperattenuating and air being hypoattenuating. MRI, ultrasound, and nuclear medicine don’t use the same attenuation-based brightness; MRI relies on magnetic properties and tissue relaxation, ultrasound on acoustic impedance and echo strength, and nuclear medicine on tracer uptake and metabolic activity. So the terms hyperattenuating and hypoattenuating are specific to CT.

CT imaging is described by hyperattenuating and hypoattenuating appearances because it measures X-ray attenuation of tissues. Tissues that attenuate more X-rays than surrounding tissues appear brighter on CT, which is called hyperattenuating. Tissues that attenuate fewer X-rays appear darker, or hypoattenuating. This depends on density and composition, with bone being highly hyperattenuating and air being hypoattenuating. MRI, ultrasound, and nuclear medicine don’t use the same attenuation-based brightness; MRI relies on magnetic properties and tissue relaxation, ultrasound on acoustic impedance and echo strength, and nuclear medicine on tracer uptake and metabolic activity. So the terms hyperattenuating and hypoattenuating are specific to CT.