Sparse sampling computed tomography (SpSCT) for detection of pulmonary embolism: a feasibility study

Area of Science:

• Medical Imaging
• Radiology
• Diagnostic Imaging

Background:

• Pulmonary embolism (PE) diagnosis relies on computed tomography pulmonary angiography (CTPA).
• Reducing radiation dose in CTPA is crucial for patient safety.
• Sparse sampling computed tomography (SpSCT) is an emerging technique for dose reduction.

Purpose of the Study:

• To evaluate SpSCT for detecting PE at reduced radiation doses.
• To assess subjective and objective image quality criteria with SpSCT.
• To compare SpSCT performance against full sampling (FS) CTPA.

Main Methods:

• Simulated low-dose CTPA scans were created from 20 patients' data at 100% down to 3.1% of the clinical dose.
• Sparse sampling (2-SpSCT and 4-SpSCT) was simulated by using every second or fourth projection.
• Radiologists assessed subjective image quality, diagnostic confidence, sensitivity, specificity, accuracy, and AUC; objective contrast-to-noise ratio (CNR) was also evaluated.

Main Results:

• 100% sensitivity for PE detection was achieved with 2-SpSCT and 4-SpSCT at 25% and 12.5% dose levels.
• SpSCT demonstrated higher sensitivity, specificity, accuracy, and AUC compared to FS CTPA across all dose levels.
• 4-SpSCT provided significantly higher subjective image quality than FS CTPA (p < 0.01), with all examinations rated diagnostic at 12.5% dose.

Conclusions:

• SpSCT enables significant radiation dose reduction in CTPA, down to 12.5% of the clinical dose (0.38 mSv effective dose).
• High image quality and diagnostic confidence are maintained with SpSCT even at substantially reduced dose levels.
• SpSCT represents a novel hardware solution for acquiring fewer projection images, leading to substantial dose reduction in clinical practice.