Free Computed Tomography (CT Brain) Questions and Answers — Questions and Answers
Question 1: Brain non-contrast CT: Hypertension history and rapid start of left facial droop. What does the picture depict?
- Subdural haemorrhage
- Subarachnoid haemorrhage
- Intracerebral haemorrhage (Correct answer)
- Intraventricular haemorrhage
- Enhancing mass
Correct answer: Intracerebral haemorrhage
The clinical presentation of hypertension and rapid onset of neurological deficits like left facial droop strongly suggests an acute stroke. On a non-contrast CT scan, acute hemorrhage appears hyperdense (bright white) due to the high protein content of fresh blood. Intracerebral hemorrhage (ICH) is bleeding directly into the brain parenchyma, often associated with uncontrolled hypertension, and would appear as a focal hyperdensity within the brain tissue.
Question 2: Poor historian, his perplexity has grown over the past few weeks. What does the picture depict?
- Subarachnoid haemorrhage
- Left subdural collection
- Bilateral subdural collections (Correct answer)
- Brain atrophy without evidence of haemorrhage
- Intraventricular haemorrhage
Correct answer: Bilateral subdural collections
A 'poor historian' and 'perplexity growing over weeks' suggests a chronic or subacute process, which is characteristic of chronic subdural hematomas. These collections of blood or fluid accumulate slowly in the subdural space, often appearing isodense or hypodense to brain tissue on CT, and can cause gradual neurological symptoms. Bilateral collections are common, especially in elderly patients or those with brain atrophy.
Question 3: Colon cancer patient after brain contrast MRI Which diagnosis is more likely?
- Two enhancing metastases (Correct answer)
- Two benign meningiomas
- Subarachnoid haemorrhage
- Two primary brain tumors
- Two areas of normal calcification
Correct answer: Two enhancing metastases
In a patient with a known history of colon cancer, the presence of new brain lesions that enhance with contrast on an MRI is highly suspicious for metastatic disease. Colon cancer frequently metastasizes to the brain. Enhancing lesions typically indicate a breakdown of the blood-brain barrier, which is common in aggressive tumors like metastases, making this the most likely diagnosis.
Question 4: Non-contrast CT brain: anticoagulated patient with right hemiparesis and abrupt onset of disorientation. What does the picture depict?
- Intraventricular haemorrhage (Correct answer)
- Subdural haemorrhage
- Enhancing mass
- Calcification of the choroid plexus
- Epidural haemorrhage
Correct answer: Intraventricular haemorrhage
An anticoagulated patient experiencing abrupt neurological deficits like right hemiparesis and disorientation is at high risk for intracranial hemorrhage. On a non-contrast CT, acute blood appears hyperdense (bright white). Intraventricular hemorrhage (IVH) refers to bleeding into the ventricular system of the brain, which would appear as bright, dense material filling or layering within the ventricles on the CT scan.
Question 5: The quantity of detector rows X Size of each detector is Section Width; for example, 64 x 0.625 is 40mm. <br> <br> Beam Collimation/Number of Detector Rows = Detector Collimation, where 0.625 = 40 mm/64.
- Desired Quality in a CT Detector: High Dynamic Range
- MSCT Beam Collimation Consists of: Beam (Formula) (Correct answer)
- MSCT Beam Collimation Consists of: Post-Patient Collimation
- MSCT Beam Collimation Consists of: Beam
Correct answer: MSCT Beam Collimation Consists of: Beam (Formula)
This question describes the fundamental formulas used in Multi-Slice Computed Tomography (MSCT) to determine beam and detector collimation. The provided equations illustrate how the total section width is calculated from the number of detector rows and the size of each detector, and how detector collimation is derived from beam collimation. This directly relates to the technical specifications of the X-ray beam in MSCT systems.
Question 6: BEAM COLLIMATION and DETECTOR COLLIMATION settings determine the section width in the MSCT System.
- SSCT Beam Collimation Consists of:
- Collimation (msct)-detector (section) collimation
- MSCT Beam Collimation Consists of:
- MSCT Beam Collimation Consists of: Post-Patient Collimation (Correct answer)
Correct answer: MSCT Beam Collimation Consists of: Post-Patient Collimation
In Multi-Slice Computed Tomography (MSCT), both pre-patient and post-patient collimation are critical for defining the section width and managing radiation dose. Post-patient collimation, located just before the detectors, further refines the X-ray beam after it has passed through the patient. This ensures that only the desired X-rays reach the detectors, contributing to precise slice thickness and optimal image quality.
Question 7: A digital radiograph was produced while the patient bed was translated (moved) through the gantry, maintaining the X-ray tube and detector array in place.
- What Does a SSCT AND MSCT require?
- What is a Scout Image in CT ? (Correct answer)
- What is the purpose of Flying Focal Spot Technology ?
- What is the purpose of an scout image in CT ?
Correct answer: What is a Scout Image in CT ?
The description accurately defines the acquisition of a scout image in CT, also known as a topogram or surview. A scout image is a preliminary digital radiograph produced by translating the patient bed through the gantry while the X-ray tube and detector array remain stationary. This image is essential for planning the subsequent axial or helical CT scans, allowing the technologist to define the precise scan range and angle.
Question 8: What is the typical Hounsfield Unit (HU) range for normal brain tissue on a non-contrast CT scan?
- Magnetic Resonance Imaging (MRI)
- Computed Tomography (CT) (Correct answer)
- Positron Emission Tomography (PET)
- Ultrasound
Correct answer: Computed Tomography (CT)
The Hounsfield Unit (HU) is the standard unit of measurement used to quantify tissue density in Computed Tomography (CT) scans. It is a scale that assigns a value of 0 HU to water and approximately -1000 HU to air, allowing for the differentiation of various tissues based on their X-ray attenuation properties. This unit is fundamental to interpreting CT images.
Question 9: What is the typical Hounsfield Unit (HU) range for normal brain tissue on a non-contrast CT scan?
- -100 to 100 HU (Correct answer)
- 0 to 50 HU
- 100 to 200 HU
- 200 to 300 HU
Correct answer: -100 to 100 HU
Normal brain tissue on a non-contrast CT scan typically has Hounsfield Unit (HU) values ranging from approximately 20-40 HU for gray matter and slightly lower for white matter. The option of -100 to 100 HU provides a broader range that encompasses these normal values, distinguishing brain parenchyma from much denser structures like bone (hundreds of HU) or less dense structures like CSF (around 0-10 HU) or fat (negative HU).
Question 10: Which type of intracranial hemorrhage appears hyperdense on a CT scan?
- Subdural hemorrhage
- Epidural hemorrhage (Correct answer)
- Subarachnoid hemorrhage
- Intraventricular hemorrhage
Correct answer: Epidural hemorrhage
All types of acute intracranial hemorrhage, including epidural, subdural, subarachnoid, and intraventricular, appear hyperdense (bright white) on a non-contrast CT scan. This is due to the high protein content of fresh blood, which causes it to attenuate X-rays more than surrounding brain tissue. An epidural hemorrhage, which collects between the dura mater and the inner surface of the skull, will clearly demonstrate this hyperdensity.
Question 11: Which type of brain lesion commonly presents as a ring-enhancing lesion on contrast-enhanced CT?
- Cyst
- Glioma
- Hematoma
- Abscess (Correct answer)
Correct answer: Abscess
A ring-enhancing lesion on a contrast-enhanced CT scan is a classic and highly suggestive finding for a brain abscess. The central necrotic core of the abscess typically does not enhance, while the surrounding inflamed and vascularized capsule, which has a disrupted blood-brain barrier, takes up the contrast material. This creates the characteristic ring-like appearance, aiding in diagnosis.
Question 12: What is the primary advantage of using contrast enhancement in brain CT imaging?
- Improved spatial resolution
- Reduced radiation dose
- Enhanced visualization of blood vessels (Correct answer)
- Faster image acquisition
Correct answer: Enhanced visualization of blood vessels
Contrast agents, typically iodine-based, are injected intravenously and absorb X-rays more effectively than surrounding tissues. This differential absorption makes structures like blood vessels, tumors, and areas of inflammation appear brighter on the CT scan. This enhanced contrast allows for improved detection and characterization of vascular abnormalities, such as aneurysms or arteriovenous malformations, and helps differentiate pathological tissues from normal brain parenchyma.
Question 13: Which type of brain imaging is most useful for assessing the presence of calcifications?
- Magnetic Resonance Imaging (MRI)
- Computed Tomography (CT) (Correct answer)
- Positron Emission Tomography (PET)
- Ultrasound
Correct answer: Computed Tomography (CT)
Computed Tomography (CT) scans are highly effective at detecting calcifications due to their principle of measuring X-ray attenuation. Calcium has a very high density and thus strongly attenuates X-rays, appearing very bright (hyperdense) on a CT image. This makes CT superior to other imaging modalities like MRI, which often struggles to visualize calcifications clearly, for this specific purpose.
Question 14: A patient presents with sudden severe headache, often described as "the worst headache of their life." Which type of brain hemorrhage is most likely?
- Subdural hemorrhage
- Epidural hemorrhage
- Subarachnoid hemorrhage (Correct answer)
- Intracerebral hemorrhage
Correct answer: Subarachnoid hemorrhage
A subarachnoid hemorrhage (SAH) is characterized by bleeding into the subarachnoid space, often caused by a ruptured aneurysm. The sudden onset of an excruciating headache, frequently described by patients as 'the worst headache of my life,' is the classic and most indicative symptom of SAH. This distinct presentation helps clinicians differentiate it from other types of intracranial hemorrhages.
Question 15: Which CT scan view provides the best visualization of the interhemispheric fissure?
- Axial
- Coronal (Correct answer)
- Sagittal
- Oblique
Correct answer: Coronal
The interhemispheric fissure is the deep groove that separates the two cerebral hemispheres, running from the front to the back of the brain. A coronal CT scan view, which slices the brain from ear to ear (like looking at the face), provides an optimal cross-sectional image along the length of this fissure. This orientation allows for a clear and extensive visualization of its entire extent and any associated pathology.
Question 16: Which brain imaging technique is most sensitive for detecting acute ischemic strokes?
- Magnetic Resonance Imaging (MRI) (Correct answer)
- Computed Tomography (CT)
- Positron Emission Tomography (PET)
- Single-Photon Emission Computed Tomography (SPECT)
Correct answer: Magnetic Resonance Imaging (MRI)
Magnetic Resonance Imaging (MRI), particularly with diffusion-weighted imaging (DWI) sequences, is the most sensitive technique for detecting acute ischemic strokes. DWI can detect changes in water movement within brain tissue that occur minutes after the onset of ischemia, often before any changes are visible on a standard CT scan. This early detection is crucial for timely intervention and treatment to minimize brain damage.
Free Computed Tomography (CT Brain) Questions and Answers
Brain non-contrast CT: Hypertension history and rapid start of left facial droop.
What does the picture depict?