Scan Protocols Flashcards

When performing a CT pulmonary angiography (CTPA), which scan direction is preferred?

Answer: Caudal to cranial

Caudal-to-cranial scanning in CTPA ensures the densest contrast bolus reaches the pulmonary arteries during image acquisition.

A CT enterography protocol differs from a standard abdominal CT primarily in which way?

Answer: Use of oral contrast to distend the small bowel

CT enterography uses large volumes of neutral oral contrast (e.g., VoLumen) to distend and visualize the small bowel mucosa.

Which scan phase best demonstrates hepatic metastases that are hypervascular?

Answer: Hepatic arterial phase

Hypervascular metastases enhance avidly during the hepatic arterial phase when liver parenchyma enhancement is low, maximizing lesion-to-liver contrast.

For a CT-guided biopsy protocol, which parameter is typically reduced to minimize patient dose during the procedure?

Answer: Tube current (mA)

Fluoroscopic CT guidance uses low-mA (fluoroCT) settings to reduce cumulative dose while maintaining adequate image quality for needle visualization.

A standard high-resolution CT (HRCT) chest protocol uses which reconstruction approach to evaluate interstitial lung disease?

Answer: Thin slices with high-frequency (sharp) kernel

HRCT uses thin slices (≤1.5 mm) with a high-spatial-frequency kernel to maximize edge detail of lung parenchyma and airways.

In a renal stone protocol CT, intravenous contrast is typically:

Answer: Not administered

Non-contrast CT is the gold standard for detecting urolithiasis because stones are visible without IV contrast and contrast can obscure small calculi.

Which of the following best describes a 'dual-phase' liver CT protocol?

Answer: Arterial and portal venous phases

A dual-phase liver protocol acquires images in both the hepatic arterial phase and the portal venous phase to characterize liver lesions.