Imaging Pearls ❯ Dual Energy ❯ Bone Removal on CTA
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- “Errors in bone segmentation were found for 1.5% of bones on dual-energy images and 12.4% of bones on single-energy images (p < 0.01). The most important differences were found in the rib cage, sternum, and pelvis. The times required for postprocessing of MIPs were similar for the dual-energy (113.5 seconds) and single-energy (106.8 seconds) techniques. The subjective image quality of the arteries was considered better for dual-energy CTA (4.5 points) than for single-energy CTA (4.1 points) owing to false cutoff of vessels during the bone removal process on the single-energy images (p = 0.026).”
Automatic bone removal technique in whole-body dual-energy CT angiography: performance and image quality
Schulz B et al
AJR 2012 Nov;199(5):W646-50 - “Errors in bone segmentation were found for 1.5% of bones on dual-energy images and 12.4% of bones on single-energy images (p < 0.01). The most important differences were found in the rib cage, sternum, and pelvis. The times required for postprocessing of MIPs were similar for the dual-energy (113.5 seconds) and single-energy (106.8 seconds) techniques.”
Automatic bone removal technique in whole-body dual-energy CT angiography: performance and image quality
Schulz B et al
AJR 2012 Nov;199(5):W646-50 - “ The subjective image quality of the arteries was considered better for dual-energy CTA (4.5 points) than for single-energy CTA (4.1 points) owing to false cutoff of vessels during the bone removal process on the single-energy images (p = 0.026).”
Automatic bone removal technique in whole-body dual-energy CT angiography: performance and image quality
Schulz B et al
AJR 2012 Nov;199(5):W646-50 - “For CTA of the trunk, the dual-energy postprocessing capabilities for 3D visualization are superior to the threshold-based bone removal of single-energy CT. Dual-energy CTA can generate boneless MIP images of substantial quality.”
Automatic bone removal technique in whole-body dual-energy CT angiography: performance and image quality
Schulz B et al
AJR 2012 Nov;199(5):W646-50 - “Bone removal, and the resultant visibility of vessel segments, were significantly better with DEBS than with MBS (p=0.011). The overall frequency of vessel-related alterations was lower in MBS compared with DEBS (p=0.001). Specifically, in the 249 vessel segments with calcified plaques, MBS generated fewer vessel alterations than DEBS (p<0.001). In the 309 vessel segments without calcified plaques, there was no difference in vessel alteration between the two techniques (p=0.22).”
Dual-energy CT angiography of pelvic and lower extremity arteries: dual-energy bone subtraction versus manual bone subtraction
Yamamoto S et al.
Clin Radiol 2010 Mar;65(3):258 - “Bone removal, and the resultant visibility of vessel segments, were significantly better with DEBS than with MBS (p=0.011). The overall frequency of vessel-related alterations was lower in MBS compared with DEBS (p=0.001). Specifically, in the 249 vessel segments with calcified plaques, MBS generated fewer vessel alterations than DEBS (p<0.001). In the 309 vessel segments without calcified plaques, there was no difference in vessel alteration between the two techniques (p=0.22).”
Dual-energy CT angiography of pelvic and lower extremity arteries: dual-energy bone subtraction versus manual bone subtraction
Yamamoto S et al.
Clin Radiol 2010 Mar;65(3):258 - AIM: To analyse the effect of dual-energy bone subtraction (DEBS) on the image quality of peripheral computed tomography (CT) angiograms.
CONCLUSION: DEBS facilitates bone removal in peripheral CT angiography, but generates more vessel alterations, particularly in the presence of calcified plaque.
Dual-energy CT angiography of pelvic and lower extremity arteries: dual-energy bone subtraction versus manual bone subtraction
Yamamoto S et al.
Clin Radiol 2010 Mar;65(3):258 - “DE CTA has substantial advantages over conventional CTA. Automatic bone subtraction is more time efficient and reliable. Automatic plaque subtraction for the first time provides a true CTA-luminogram which is easy to interpret and reduces the need for further post-processing. DE CTA provides best results in arteries of the thigh; below the knee, plaque subtraction is less accurate.”
Dual energy CT of peripheral arteries: effect of automatic bone and plaque removal on image quality and grading of stenoses.
Meyer BC et al.
Eur J Radiol 2008 Dec;68(3):414-22 - “Residual bone fragments (ribs: 46%, patella: 25%, spine: 4%, pelvis: 2%, tibia 2% of patients) were only observed with ABS. The time needed to manually remove these residual bones was 2.1+/-1.1 min and was significantly lower than the duration of manual bone removal (6.8+/-2.0 min, p<0.0001, paired t-test). A total of 1159 arteries were analyzed. Compromising vessel erosions were observed less frequently in the ABS-B dataset (10.6%) than in the MBS dataset (15.2%, p<0.001, wilcoxon's signed rank test).”
Dual energy CT of peripheral arteries: effect of automatic bone and plaque removal on image quality and grading of stenoses.
Meyer BC et al.
Eur J Radiol 2008 Dec;68(3):414-22
- “Errors in bone segmentation were found for 1.5% of bones on dual-energy images and 12.4% of bones on single-energy images (p < 0.01). The most important differences were found in the rib cage, sternum, and pelvis. The times required for postprocessing of MIPs were similar for the dual-energy (113.5 seconds) and single-energy (106.8 seconds) techniques. The subjective image quality of the arteries was considered better for dual-energy CTA (4.5 points) than for single-energy CTA (4.1 points) owing to false cutoff of vessels during the bone removal process on the single-energy images (p = 0.026).”
Automatic bone removal technique in whole-body dual-energy CT angiography: performance and image quality
Schulz B et al
AJR 2012 Nov;199(5):W646-50 - “Errors in bone segmentation were found for 1.5% of bones on dual-energy images and 12.4% of bones on single-energy images (p < 0.01). The most important differences were found in the rib cage, sternum, and pelvis. The times required for postprocessing of MIPs were similar for the dual-energy (113.5 seconds) and single-energy (106.8 seconds) techniques.”
Automatic bone removal technique in whole-body dual-energy CT angiography: performance and image quality
Schulz B et al
AJR 2012 Nov;199(5):W646-50 - “ The subjective image quality of the arteries was considered better for dual-energy CTA (4.5 points) than for single-energy CTA (4.1 points) owing to false cutoff of vessels during the bone removal process on the single-energy images (p = 0.026).”
Automatic bone removal technique in whole-body dual-energy CT angiography: performance and image quality
Schulz B et al
AJR 2012 Nov;199(5):W646-50 - “For CTA of the trunk, the dual-energy postprocessing capabilities for 3D visualization are superior to the threshold-based bone removal of single-energy CT. Dual-energy CTA can generate boneless MIP images of substantial quality.”
Automatic bone removal technique in whole-body dual-energy CT angiography: performance and image quality
Schulz B et al
AJR 2012 Nov;199(5):W646-50 - “Bone removal, and the resultant visibility of vessel segments, were significantly better with DEBS than with MBS (p=0.011). The overall frequency of vessel-related alterations was lower in MBS compared with DEBS (p=0.001). Specifically, in the 249 vessel segments with calcified plaques, MBS generated fewer vessel alterations than DEBS (p<0.001). In the 309 vessel segments without calcified plaques, there was no difference in vessel alteration between the two techniques (p=0.22).”
Dual-energy CT angiography of pelvic and lower extremity arteries: dual-energy bone subtraction versus manual bone subtraction
Yamamoto S et al.
Clin Radiol 2010 Mar;65(3):258 - “Bone removal, and the resultant visibility of vessel segments, were significantly better with DEBS than with MBS (p=0.011). The overall frequency of vessel-related alterations was lower in MBS compared with DEBS (p=0.001). Specifically, in the 249 vessel segments with calcified plaques, MBS generated fewer vessel alterations than DEBS (p<0.001). In the 309 vessel segments without calcified plaques, there was no difference in vessel alteration between the two techniques (p=0.22).”
Dual-energy CT angiography of pelvic and lower extremity arteries: dual-energy bone subtraction versus manual bone subtraction
Yamamoto S et al.
Clin Radiol 2010 Mar;65(3):258 - AIM: To analyse the effect of dual-energy bone subtraction (DEBS) on the image quality of peripheral computed tomography (CT) angiograms.
CONCLUSION: DEBS facilitates bone removal in peripheral CT angiography, but generates more vessel alterations, particularly in the presence of calcified plaque.
Dual-energy CT angiography of pelvic and lower extremity arteries: dual-energy bone subtraction versus manual bone subtraction
Yamamoto S et al.
Clin Radiol 2010 Mar;65(3):258 - “DE CTA has substantial advantages over conventional CTA. Automatic bone subtraction is more time efficient and reliable. Automatic plaque subtraction for the first time provides a true CTA-luminogram which is easy to interpret and reduces the need for further post-processing. DE CTA provides best results in arteries of the thigh; below the knee, plaque subtraction is less accurate.”
Dual energy CT of peripheral arteries: effect of automatic bone and plaque removal on image quality and grading of stenoses.
Meyer BC et al.
Eur J Radiol 2008 Dec;68(3):414-22 - “Residual bone fragments (ribs: 46%, patella: 25%, spine: 4%, pelvis: 2%, tibia 2% of patients) were only observed with ABS. The time needed to manually remove these residual bones was 2.1+/-1.1 min and was significantly lower than the duration of manual bone removal (6.8+/-2.0 min, p<0.0001, paired t-test). A total of 1159 arteries were analyzed. Compromising vessel erosions were observed less frequently in the ABS-B dataset (10.6%) than in the MBS dataset (15.2%, p<0.001, wilcoxon's signed rank test).”
Dual energy CT of peripheral arteries: effect of automatic bone and plaque removal on image quality and grading of stenoses.
Meyer BC et al.
Eur J Radiol 2008 Dec;68(3):414-22
- “One major advantage of dual-energy CT is the capability of material differentiation. In general, this property can be applied to bone removal in CT angiography for easier and faster postprocessing. In neuroradiology, material decomposition allows detection of hemorrhage on contrast-enhanced CT scans and facilitates the search for the underlying pathologic mechanism of hematomas. The combination of low radiation dose and advantageous spectral information (blood vs contrast) from these datasets justifies broad clinical implementation of dual-energy CT in neuroradiology.”
Dual-Energy CT of the Brain and Intracranial Vessels
Postma AA et al.
AJR 2012; 199:S26-33 - “One major advantage of dual-energy CT is the capability of material differentiation. In general, this property can be applied to bone removal in CT angiography for easier and faster postprocessing.”
Dual-Energy CT of the Brain and Intracranial Vessels
Postma AA et al.
AJR 2012; 199:S26-33 - “Bone removal in DECT angiography
allows easier and faster acquisition and postprocessing compared with conventional (subtraction) CTA. Removal of bone at the skull base remains a matter of concern, but the development of better reconstruction algorithms and dedicated dual-energy kernels may offer a solution.”
Dual-Energy CT of the Brain and Intracranial Vessels
Postma AA et al.
AJR 2012; 199:S26-33 - Dual-energy bone subtraction has been
shown to be faster and technically superior to threshold-based bone subtraction techniques
even when the latter are manually corrected. However, even with dual-energy bone subtraction, bone subtraction is not infrequently
incomplete.
Dual Energy CT: Vascular Applications
Vlahos I et al
AJR 2012: 199:S87-S97 - “ Compared with DSA-diagnosed stenoses
(> 75%), interpretation of dual-energy bone subtraction lower limb CT arteriography MIP
reconstructions alone show high sensitivity,
specificity, and accuracy (94–97%). Comparatively, threshold-based bone subtraction CT arteriography–derived MIPs exhibit lower corresponding values (71–77%). Dual-energy bone subtraction superiority is maintained in heavily calcified vessels (91–96%), whereas this decreases dramatically for threshold based bone subtraction (57–74%).
Dual Energy CT: Vascular Applications
Vlahos I et al
AJR 2012: 199:S87-S97 - “Dual-energy bone subtraction for cervical
CT arteriography compares very favorably
to threshold-based bone subtraction.
Early studies confirmed that dual-energy
bone subtraction was faster and more accurate versus threshold-based bone subtraction without user modification (88% vs 7% technically adequate). Threshold-based bone subtraction inferiority was predominantly due to residual bone, vessel truncations, and poorer vessel delineation, the result of extensive anatomic contact of vessels with bone.”
Dual Energy CT: Vascular Applications
Vlahos I et al
AJR 2012: 199:S87-S97
- Why can we separate bone from contrast enhanced vessels on dual energy CT scans?
- Bone Removal on Contrast Enhanced CT
- X-ray attenuation is caused by the Compton effect, coherent scatter, and the photoelectric effect
- The photoelectric effect depends on the atomic number of the material and increases with higher atomic element numbers
- Most elements in the human body have low atomic number (hydrogen, oxygen, carbon, nitrogen) and have weak photoelectric effect while some (calcium, magnesium) have a stronger photoelectric effect
- Contrast material (iodine, barium) have very strong photoelectric effect. The photoelectric effect peaks at element 55 (cesium) with iodine (53) and barium (56) in close proximity 
- “DEBR provides significant advantages, even over manually corrected SBBR. As it works completely automatically, it can effectively help to cope with the data load of CT angiography exams. Furthermore, it enables the removal of intraluminal plaques, which provides a benefit for the estimation of the residual lumen.”
The value of dual-energy bone removal in maximum intensity projections of lower extremity computed tomography angiography
Sommer WH et al
Invest Radiol 2009 May;44(5) 285-92 - “Dual-energy computed tomography (CT) makes it possible to remove bones and intraluminal plaques from angiography datasets on the basis of spectral differentiation separating iodine from calcium. The objective of this study was to evaluate the feasibility and efficiency of this technique by comparing maximum intensity projections (MIP) created with different bone removal techniques: (a) dual-energy bone removal (DEBR); (b) purely software-based bone removal without manual corrections (SBBR - MC); and (c) manually corrected software-based bone removal (SBBR + MC).”
The value of dual-energy bone removal in maximum intensity projections of lower extremity computed tomography angiography
Sommer WH et al
Invest Radiol 2009 May;44(5) 285-92 - “DE CTA has substantial advantages over conventional CTA. Automatic bone subtraction is more time efficient and reliable. Automatic plaque subtraction for the first time provides a true CTA-luminogram which is easy to interpret and reduces the need for further post-processing. DE CTA provides best results in arteries of the thigh; below the knee, plaque subtraction is less accurate.”
Dual energy CT of peripheral arteries: effect of automatic bone and plaque removal on image quality and grading of stenosis
Meyer BC et al
Eur J Radiol 2008 Dec; 68(3):414-22
- “In general, dual scan based methods that use the lowest tube voltage available, have a higher CNR than the dual energy based approaches at the same dose level. Tin filtration improves the ability to differentiate between iodine and bone for the dual energy based masking method. In clinical practice, the advantages of the dual energy masking method might outweigh its disadvantage of a slightly higher dose penalty compared to the conventional dual scan masking method.”
Automated bone removal in CT angiography: comparison of methods based on single energy and dual energy scans
van Straten M et al.
Med Phys 2011 Nov;38(11);6128-37 - “ Compared to the dual scan based methods, the dual energy based methods had the advantage that only a single scan was made without the need of image registration. This might be easier to implement in clinical practice. Vessel preservation was better with bone subtraction than with bone masking. Smaller vessels were completely occluded by the bone mask.”
Automated bone removal in CT angiography: comparison of methods based on singlr energy and dual energy scans
van Straten M et al.
Med Phys 2011 Nov;38(11);6128-37 - Dual Energy Workflow
- Who does the actual bone removal?
- When is the bone removal done (at time of interpretation or before)?
- What is the role of radiologic technologics in the workflow? - “ The second advantage of dual-energy CT imaging stems from the potential to calculate material-specific images derived mathematically from the simultaneous availability of attenuation measurements at 2 distinct energies. These material-specific data sets include virtual noncontrast images, virtual contrast, or "bone-subtracted" angiographic-like images. These techniques may confer significant advantages in the evaluation of patients with aortic disease, improving interpretation and reducing reconstruction time, while potentially reducing the need for, and associated radiation burden of, precontrast or postcontrast multiphasic imaging.”
Dual-energy computed tomography of the aorta
Viahos I, Godoy MC, Naidich DP
J Thorac Imaging 2010 Nov 25(4):289-300 - “ These material-specific data sets include virtual noncontrast images, virtual contrast, or "bone-subtracted" angiographic-like images. These techniques may confer significant advantages in the evaluation of patients with aortic disease, improving interpretation and reducing reconstruction time, while potentially reducing the need for, and associated radiation burden of, precontrast or postcontrast multiphasic imaging.”
Dual-energy computed tomography of the aorta
Viahos I, Godoy MC, Naidich DP
J Thorac Imaging 2010 Nov 25(4):289-300 - “Of the 46 patients, 13 were studied using 80/140kV and 33 with 100/140kV. There were no significant differences between the two groups in age or sex. Image quality in four segments was better in the group examined with 100/140kV. Cortical bone removal in MPR and MIP and trabecular bone removal in MIP were also better in the group examined with 100/140kV. The dose of radiation received was significantly higher in the group examined with 100/140kV (1.16 mSv with 80/140kV vs. 1.59 mSv with 100/140kV).”
Dual energy CT angiography of the carotid arteries: quality, bone subtraction, and radiation dosage using tube voltage 80/140kV versus 100/140kV
Santos Armentia E et al.
Radiologia 2012 May 15 (epub ahead of print)
“Using 100/140kV increases the dose of radiation but improves the quality of the study of arterial segments and bone subtraction.”
Dual energy CT angiography of the carotid arteries: quality, bone subtraction, and radiation dosage using tube voltage 80/140kV versus 100/140kV
Santos Armentia E et al.
Radiologia 2012 May 15 (epub ahead of print)- Dual Energy CT Scanning: Vascular Applications
1. Vascular CT with automatic bone removal critical
- runoff studies of the lower extremities
-Carotid artery imaging
- Circle of Willis and Base of the Brain
2. Virtual Non-contrast CT for Endovascular Stent Followup
3. Pulmonary embolism with blood flow maps
4. Myocardial perfusion imaging - “Initial reports have suggested that dual energy CTA (DE-CTA) can enhance diagnosis by creating bone-free data sets, which can be visualized in 3D, but a number of limitations of this technique have also been addressed. We sought to describe the performance of DE-CTA of the supraaortic vessels with a novel dual source CT system with special emphasis on image quality and post-processing related artifacts.”
Dual energy CTA of the supraaortic arteries: technical improvements with a novel dual source CT system
Lell MM et al
Eur J Radiol 2010 Nov;76(2)e6-12 - “Excellent bone suppression could be achieved, DE imaging with 100 and 140kV lead to improved image quality and vessel integrity in the shoulder region than previously reported.”
Dual energy CTA of the supraaortic arteries: technical improvements with a novel dual source CT system
Lell MM et al
Eur J Radiol 2010 Nov;76(2)e6-12