CT Perfusion Image Noise Reduction via Frequency Space Merging
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Solution Overview
Problem
CT perfusion imaging techniques face challenges with low signal-to-noise ratio (SNR) due to prolonged acquisition times, leading to poorer image quality compared to CT contrast angiograms, which require shorter x-ray doses and faster snapshot acquisitions.
Innovation Solution
The method involves registering CT perfusion and angiography images, transforming them into frequency space, merging the central frequency space of perfusion images with the peripheral frequency space of angiography images using a normalized response curve, and inversely transforming the merged images to enhance image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If CT perfusion imaging uses prolonged acquisition times to reduce x-ray dose, then radiation dose is reduced, but signal-to-noise ratio deteriorates
Solution Approach 1:
The patent merges a low-frequency component from a first image (acquired during contrast agent passage) with a high-frequency component from a second image (acquired at a different time point) to create a combined image. This combining operation allows the low-frequency anatomical information and contrast timing to be preserved while high-frequency spatial details are maintained, achieving improved signal-to-noise ratio without requiring increased radiation dose or prolonged acquisition time
2Loss of information
If CT perfusion imaging uses prolonged acquisition times, then dynamic flow properties can be captured, but image quality deteriorates due to noise
Solution Approach 1:
The patent combines frequency components from images acquired at different time points during contrast agent passage. The low-frequency component captures the dynamic flow properties and contrast timing, while the high-frequency component provides sharp spatial details. This merging allows dynamic flow information to be preserved without sacrificing image quality to noise
3Measurement precision
If CT contrast angiogram uses snapshot acquisition, then signal-to-noise ratio is improved, but acquisition time increases
Solution Approach 1:
The patent acquires a second image at a different time point (preliminarily or subsequently) that captures high-frequency spatial information. This preliminary or subsequent acquisition of structural detail allows the first snapshot image to focus on capturing the dynamic contrast phase, and the combination of both images provides complete information without requiring extended acquisition time
Data Source
AI summary
A method for enhancing images of an object includes registering a fixed image with cine images of the same object. Next, the fixed image and the cine images are transformed into frequency space representations thereof. A central portion of the frequency space cine images are merged with a peripheral portion of frequency space fixed image using a defined normalized response curve or a predefined normalized response curve (or both) to form a merged image. Finally, the method includes inversely transforming the merged image into enhanced cine images of the object.