CT vs MRI: Comparison and Considerations

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Questions and Answers

Based on the information provided, what did the interpreting radiologist conclude about the initial non-contrast CT head?

There is evidence of a right sided infarct.

There is a suspicious CT abnormality to correlate with the patient's symptoms. (correct)

There is no acute infarct. Consider EEG.

There is no evidence of acute infarct. Send the patient home.

Which imaging modality is the most sensitive for evaluating an acute brain infarct?

CTA head with contrast

MRA brain without contrast and MRA neck with contrast

CT head with contrast

MRI brain without contrast (correct)

According to the information provided, which of the following is a characteristic CT finding of an acute cerebral infarct?

Hyperintense on T1 and hypointense on T2/FLAIR

Hyperdense (bright) vessel sign (correct)

Sulcal effacement or asymmetrically larger sulci

Hypointense on DWI

Which of the following is a characteristic MRI finding of an acute cerebral infarct?

Hyperintense on DWI (C) Signup and view all the answers

What is the appropriate next step in imaging for this patient, based on the information provided?

Proceed directly to MRI brain without contrast (D) Signup and view all the answers

Which of the following is a common limitation of non-contrast CT in the evaluation of acute cerebral infarction?

May not show evidence of acute infarct in the first few hours (D) Signup and view all the answers

Which of the following statements accurately compares CT and MRI?

Patient cooperation is more important for MRI than for CT scans. (D) Signup and view all the answers

Which of the following organizations publishes appropriateness criteria for clinical imaging exams?

American College of Radiology (C) Signup and view all the answers

Which of the following factors should be considered when selecting between CT and MRI for imaging?

All of the above (D) Signup and view all the answers

Which imaging modality is generally preferred for patients with pacemakers or aneurysm clips?

CT (D) Signup and view all the answers

What is a key advantage of MRI over CT in terms of patient safety?

MRI does not involve ionizing radiation exposure. (A) Signup and view all the answers

Which type of Le Fort fracture is characterized by involvement of the zygomatic arch?

Le Fort III (C) Signup and view all the answers

Which of the following is NOT a typical indication for using IV gadolinium contrast in MRI neuroimaging?

Evaluating stroke, trauma, or degenerative spine disease (C) Signup and view all the answers

Which neuroimaging modality is typically performed without contrast for evaluating the head and neck vasculature?

MRA of the head (D) Signup and view all the answers

When would a CT of the head and neck soft tissues typically be performed with contrast?

Both a and b (D) Signup and view all the answers

Study Notes

Acute Cerebral Infarct

61-year-old female presents with acute onset right-sided weakness and aphasia, history of atrial fibrillation, hypertension, COPD, and discontinued anticoagulation due to frequent falls
Interpreting radiologist concludes that there is evidence of a right-sided infarct

Imaging Modalities for Acute Brain Infarct

Most sensitive imaging modality: MRI brain without contrast (hyperintense on DWI)
CT head: may not show acute infarct, especially in the first few hours; signs include hypodense areas, loss of gray/white differentiation, and swelling/edema
MRI: hyperintense on DWI, hypointense on T1, and hyperintense on T2/FLAIR; signs include loss of gray/white differentiation and sulcal effacement

CT vs MRI

CT: cheaper, faster, uses ionizing radiation, and has lower patient cooperation requirements
MRI: more expensive, takes longer, does not use ionizing radiation, and requires higher patient cooperation

ACR Appropriateness Criteria

Published by the American College of Radiology (ACR)
Extremely helpful for determining appropriateness of clinical imaging exams

Neuroimaging Exams

CT Neuroimaging exams: usually performed without contrast, except for CTs of head and neck soft tissues, CT angiograms, and CT venograms
MR Neuroimaging exams: IV gadolinium contrast indicated for infection, primary tumors or metastatic disease, demyelinating disease, and a few others; not usually necessary for stroke, trauma, or degenerative spine disease

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Description

Learn about the differences between CT and MRI scans, including cost, safety, acquisition time, patient cooperation, and use of contrast material. Understand the appropriateness criteria for choosing between CT and MRI in medical imaging.