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80-kVp CT using Iterative Reconstruction in Image Space algorithm for the detection of hypervascular hepatocellular carcinoma: phantom and initial clinical experience.

Hur S, Lee JM, Kim SJ, Park JH, Han JK, Choi BI - Korean J Radiol (2012)

Bottom Line: IRIS effectively reduced image noise, and yielded 29% higher CNR than the FBP at equivalent tube voltage and current in the phantom study.Mean effective dose was 2.63-mSv with protocol A and 1.12-mSv with protocols B and C.CT using the low-tube-voltage, intermediate-tube-current and IRIS help improve lesion-to-liver CNR of HCC in thin adults during the arterial phase at a lower radiation dose when compared with the standard technique using 120-kVp and FBP.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea.

ABSTRACT

Objective: To investigate whether the low-tube-voltage (80-kVp), intermediate-tube-current (340-mAs) MDCT using the Iterative Reconstruction in Image Space (IRIS) algorithm improves lesion-to-liver contrast at reduced radiation dosage while maintaining acceptable image noise in the detection of hepatocellular carcinomas (HCC) in thin (mean body mass index, 24 ± 0.4 kg/m(2)) adults.

Subjects and methods: A phantom simulating the liver with HCC was scanned at 50-400 mAs for 80, 100, 120 and 140-kVp. In addition, fifty patients with HCC who underwent multiphasic liver CT using dual-energy (80-kVp and 140-kVp) arterial scans were enrolled. Virtual 120-kVP scans (protocol A) and 80-kVp scans (protocol B) of the late arterial phase were reconstructed with filtered back-projection (FBP), while corresponding 80-kVp scans were reconstructed with IRIS (protocol C). Contrast-to-noise ratio (CNR) of HCCs and abdominal organs were assessed quantitatively, whereas lesion conspicuity, image noise, and overall image quality were assessed qualitatively.

Results: IRIS effectively reduced image noise, and yielded 29% higher CNR than the FBP at equivalent tube voltage and current in the phantom study. In the quantitative patient study, protocol C helped improve CNR by 51% and 172% than protocols A and B (p < 0.001), respectively, at equivalent radiation dosage. In the qualitative study, protocol C acquired the highest score for lesion conspicuity albeit with an inferior score to protocol A for overall image quality (p < 0.001). Mean effective dose was 2.63-mSv with protocol A and 1.12-mSv with protocols B and C.

Conclusion: CT using the low-tube-voltage, intermediate-tube-current and IRIS help improve lesion-to-liver CNR of HCC in thin adults during the arterial phase at a lower radiation dose when compared with the standard technique using 120-kVp and FBP.

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Axial CT image of phantom at tube voltage of 100 kVP and 150 mAs. Fifth tube was selected as target lesion to simulate subtle hypervascular HCC nodules.
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Figure 1: Axial CT image of phantom at tube voltage of 100 kVP and 150 mAs. Fifth tube was selected as target lesion to simulate subtle hypervascular HCC nodules.

Mentions: A liver phantom was created using agar mixed with a water-soluble contrast agent (Diatrizoatemeglumine and diatrizoate sodium-solution; Gastrografin, Bayer-Schering, Berlin, Germany) to attain a similar attenuation coefficient of the liver parenchyma during the late arterial phase (Fig. 1). From the liver CT images of our pilot study using the dual-energy CT scanning mode for HCCs, we were able to measure the attenuation value of the liver during the late arterial phase as 64 ± 7.8 HU at 120 kVp (0.3 linear blending image). Based on this data, the amount of Gastrografin (0.8 mL per 100 mL agar) was selected to simulate a contrast-enhanced liver during the late arterial phase. The mean attenuation values of the liver phantom were 78 HU for 120 kVp scanning and 130 HU for 80 kVp scanning.


80-kVp CT using Iterative Reconstruction in Image Space algorithm for the detection of hypervascular hepatocellular carcinoma: phantom and initial clinical experience.

Hur S, Lee JM, Kim SJ, Park JH, Han JK, Choi BI - Korean J Radiol (2012)

Axial CT image of phantom at tube voltage of 100 kVP and 150 mAs. Fifth tube was selected as target lesion to simulate subtle hypervascular HCC nodules.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3303898&req=5

Figure 1: Axial CT image of phantom at tube voltage of 100 kVP and 150 mAs. Fifth tube was selected as target lesion to simulate subtle hypervascular HCC nodules.
Mentions: A liver phantom was created using agar mixed with a water-soluble contrast agent (Diatrizoatemeglumine and diatrizoate sodium-solution; Gastrografin, Bayer-Schering, Berlin, Germany) to attain a similar attenuation coefficient of the liver parenchyma during the late arterial phase (Fig. 1). From the liver CT images of our pilot study using the dual-energy CT scanning mode for HCCs, we were able to measure the attenuation value of the liver during the late arterial phase as 64 ± 7.8 HU at 120 kVp (0.3 linear blending image). Based on this data, the amount of Gastrografin (0.8 mL per 100 mL agar) was selected to simulate a contrast-enhanced liver during the late arterial phase. The mean attenuation values of the liver phantom were 78 HU for 120 kVp scanning and 130 HU for 80 kVp scanning.

Bottom Line: IRIS effectively reduced image noise, and yielded 29% higher CNR than the FBP at equivalent tube voltage and current in the phantom study.Mean effective dose was 2.63-mSv with protocol A and 1.12-mSv with protocols B and C.CT using the low-tube-voltage, intermediate-tube-current and IRIS help improve lesion-to-liver CNR of HCC in thin adults during the arterial phase at a lower radiation dose when compared with the standard technique using 120-kVp and FBP.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea.

ABSTRACT

Objective: To investigate whether the low-tube-voltage (80-kVp), intermediate-tube-current (340-mAs) MDCT using the Iterative Reconstruction in Image Space (IRIS) algorithm improves lesion-to-liver contrast at reduced radiation dosage while maintaining acceptable image noise in the detection of hepatocellular carcinomas (HCC) in thin (mean body mass index, 24 ± 0.4 kg/m(2)) adults.

Subjects and methods: A phantom simulating the liver with HCC was scanned at 50-400 mAs for 80, 100, 120 and 140-kVp. In addition, fifty patients with HCC who underwent multiphasic liver CT using dual-energy (80-kVp and 140-kVp) arterial scans were enrolled. Virtual 120-kVP scans (protocol A) and 80-kVp scans (protocol B) of the late arterial phase were reconstructed with filtered back-projection (FBP), while corresponding 80-kVp scans were reconstructed with IRIS (protocol C). Contrast-to-noise ratio (CNR) of HCCs and abdominal organs were assessed quantitatively, whereas lesion conspicuity, image noise, and overall image quality were assessed qualitatively.

Results: IRIS effectively reduced image noise, and yielded 29% higher CNR than the FBP at equivalent tube voltage and current in the phantom study. In the quantitative patient study, protocol C helped improve CNR by 51% and 172% than protocols A and B (p < 0.001), respectively, at equivalent radiation dosage. In the qualitative study, protocol C acquired the highest score for lesion conspicuity albeit with an inferior score to protocol A for overall image quality (p < 0.001). Mean effective dose was 2.63-mSv with protocol A and 1.12-mSv with protocols B and C.

Conclusion: CT using the low-tube-voltage, intermediate-tube-current and IRIS help improve lesion-to-liver CNR of HCC in thin adults during the arterial phase at a lower radiation dose when compared with the standard technique using 120-kVp and FBP.

Show MeSH
Related in: MedlinePlus