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Effects of a high-pitch protocol and a hybrid iterative reconstruction algorithm on image quality of cerebral
Yuji Iyama1,2, Takeshi Nakaura3,4, Masafumi Kidoh5
1Diagnostic Radiology, Amakusa Medical Center, kameba 854-1, Amakusa, Kumamoto, 863-0046, Japan. iyamayuuji28@gmail.com.
Insights
High-pitch computed tomography angiography (CTA) with hybrid iterative reconstruction (HIR) significantly lowers radiation dose. This advanced technique maintains diagnostic image quality, reducing venous enhancement and noise for clearer imaging.
Area of Science:
- Radiology
- Medical Imaging
- Cardiovascular Imaging
Background:
- 3D-computed tomography angiography (3D-CTA) is crucial for vascular imaging.
- Optimizing radiation dose while maintaining image quality is a key challenge in CTA.
- High-pitch protocols and iterative reconstruction techniques offer potential solutions.
Purpose of the Study:
- To evaluate the diagnostic image quality and radiation dose of 3D-CTA.
- To compare a high-pitch protocol with hybrid iterative reconstruction (HIR) against standard protocols.
Main Methods:
- Prospective study comparing three protocols: standard pitch with filtered back-projection (FBP), high-pitch with FBP, and high-pitch with HIR.
- Quantitative analysis of radiation dose (CTDIvol), image noise, and arterial/venous attenuation.
- Qualitative assessment of image noise, arterial contrast, and venous overlap by two readers.
Main Results:
- High-pitch protocols (B/C) significantly reduced radiation dose (CTDIvol) compared to standard protocol (A).
- Protocol B (high-pitch, FBP) showed increased image noise compared to protocol A.
- Protocol C (high-pitch, HIR) demonstrated comparable arterial attenuation to A but reduced venous attenuation and enhancement.
Conclusions:
- 3D-CTA using a high-pitch protocol combined with HIR effectively reduces radiation dose.
- This approach achieves diagnostic image quality with acceptable levels of image noise and reduced venous enhancement.
- High-pitch CTA with HIR represents a promising advancement for dose reduction in vascular imaging.
Purpose:
To evaluate the image quality and the radiation dose of 3D-computed tomography angiography (3D-CTA) with a high-pitch protocol and a hybrid iterative reconstruction (HIR).
Materials And Methods:
This was a prospective study and thirty patients were scanned at a 0.51-helical pitch with filtered back-projection (FBP, protocol-A), and 30 patients were scanned at a 0.91-helical pitch with FBP and HIR (protocol-B and C). The mean volume CT dose index (CTDI(vol)), image noise, and mean cerebral arterial and venous attenuation were compared between the three protocols. Two readers assessed image noise, arterial contrast and venous overlap.
Results:
The mean CTDI(vol) of protocol-B/C (38.9 mGy) was lower than that of protocol-A (49.7 mGy). Mean image noise of protocol-B [12.6 ± 1.3 Hounsfield units (HU)] was higher than that of protocol-A (10.3 ± 1.2 HU). There was no significant difference in arterial attenuation between protocol-A (327.5 ± 57.5 HU) and C (327.7 ± 59.4 HU). Venous attenuation of protocol-C (148.5 ± 50.4 HU) was lower than that of protocol-A (185.9 ± 50.6 HU). In qualitative analysis, the image noise of protocol-B was higher than that of protocol-A/C. Venous enhancement of protocol-B/C was more inconspicuous than that of protocol-A.
Conclusions:
3D-CTA with a high-pitch protocol and HIR can reduce radiation dose while decreasing venous enhancement and image noise to an adequate level for diagnosis.
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