Rotational micro-CT using a clinical C-arm angiography gantry

Citation

Patel, V., Hoffmann, K. R., Ionita, C. N., Keleshis, C., Bednarek, D. R., & Rudin, S. (2008). Rotational micro-CT using a clinical C-arm angiography gantry. Medical Physics, 35(10), 4209-4218. https://doi.org/10.1118/1.2989989

Keywords

• Cone-beam CT
• Micro-CT
• Rotational Angiography (RA)
• C-arm gantry
• High-resolution imaging
• Region-of-interest (ROI)
• Artifact reduction
• Image registration
• Dual-detector system
• Dose reduction

Brief

This article presents a new 3D rotational micro-angiography (RMA) system, effectively a rotating-gantry cone-beam CT system, that provides high-resolution 2D and 3D images at a lower integral dose to the patient compared to standard systems.

Summary

The 2008 Medical Physics Letter, "Rotational micro‐CT using a clinical C‐arm angiography gantry," by V. Patel et al. describes a new technique called 3D rotational micro-angiography (RMA) to improve the resolution of images acquired using a clinical C-arm gantry system.

• Traditional rotational angiography (RA) systems, widely used for 3D rendering of vascular structures, have limited resolution (around 4 lp/mm) compared to micro-computed tomography (micro-CT) systems (approximately 10 lp/mm). However, micro-CT systems have typically relied on rotating the object being imaged or using small bore geometry, making them unsuitable for clinical imaging of human patients.
• The 3D RMA system involves mounting a high-resolution, high-sensitivity micro-angiographic fluoroscope (MAF) onto a standard clinical RA gantry. To address image truncation artifacts that can arise from the MAF's smaller field of view (FOV), the researchers acquired additional lower-dose, full-FOV images using the standard flat panel detector (FPD) on the RA gantry.
• Before reconstruction, the high-resolution MAF images and the lower-dose FPD images are spatially aligned and their pixel values matched to ensure high-quality reconstruction. This process, essentially a form of cone-beam CT, effectively calibrates the geometry of the MAF acquisitions using the calibrations already performed for the FPD system.
• Evaluations using a rabbit model with a coronary stent implanted in an artery demonstrated that the 3D RMA technique produced significantly higher resolution images compared to using the FPD alone. The FWHMs of the stent struts were noticeably smaller in the 3D RMA images, indicating better resolution and clarity.
• This dual-acquisition 3D RMA method not only minimizes truncation artifacts by combining data from both detectors but also allows for potential dose reduction. Since the FPD images primarily serve to calibrate the MAF geometry and reduce artifacts, their quality is less critical and can be acquired at a lower dose than standard FPD acquisitions.

The authors believe that this novel 3D RMA technique, essentially a rotating-gantry cone-beam CT system adapted for a clinical C-arm system, holds promise for enhancing the resolution of clinical imaging while potentially reducing patient dose.

Origin: https://aapm.onlinelibrary.wiley.com/doi/epdf/10.1118/1.2989989