Comparative Assessment of Energy-Mapping Approaches in CT-Based Attenuation Correction for PET

Ay, Mohammad Reza; Shirmohammad, Maryam; Sarkar, Saeed; Rahmim, Arman; Zaidi, Habib

doi:10.1007/s11307-010-0303-3

Cited by 29 publications

(22 citation statements)

References 27 publications

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“…It should be noted that although the bilinear approach provides an acceptable accuracy in lung and soft tissues, it slightly overestimates l 511keV . 17 The proposed method is based on the dual-energy formulation 18,19 but requires only one CT image acquired at a single kV P for its implementation.…”

Section: Discussionmentioning

confidence: 99%

“…Several energy-mapping approaches were proposed including scaling, segmentation, hybrid (scaling/segmentation), bilinear, quadratic, and dual-energy decomposition. 17 This work compares the dual-energy and proposed virtual dual-energy approaches to the bilinear technique as the most commonly used technique on commercial PET/CT scanners.…”

Section: Iib Energy-mapping Methodsmentioning

confidence: 99%

“…Therefore, an accurate energy mapping method that converts attenuation coefficients measured at CT energies to equivalent values at 511 keV is essential. 14 Several energy-mapping techniques were proposed in the literature including: scaling, 15 segmentation, 11 hybrid (segmentation/scaling), 10 bilinear, 14,16 quadratic, 17 and the dual-energy technique. 18,19 Among the above referenced methods, the dual-energy technique presents a high accuracy, since it uses dual kV P CT scans to estimate the l-map at 511 keV.…”

Section: Introductionmentioning

confidence: 99%

“…18,19 Among the above referenced methods, the dual-energy technique presents a high accuracy, since it uses dual kV P CT scans to estimate the l-map at 511 keV. 17,20 However, the technique bears many inherent drawbacks including the additional radiation dose to the patient which makes it impractical for clinical use. 21 In this work, we propose a new method allowing the implementation of the dual-energy approach using only a single energy CT image.…”

Section: Introductionmentioning

confidence: 99%

“…This is in agreement with observations made in previous studies reporting on the assessment of the impact of variations in the attenuation map on attenuation corrected PET images. 17,29,30 Novel x-ray tube technologies, allowing switching the kV P slice by slice, can also be used for implementation of the DECT technique. However, the main drawback of this technology is the deep level of ruination of the x-ray tube during switching.…”

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confidence: 99%

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A novel energy mapping approach for CT‐based attenuation correction in PET

Teimourian

Zafarghandi

et al. 2012

Medical Physics

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Purpose: Dual-energy CT (DECT) is arguably the most accurate energy mapping technique in CTbased attenuation correction (CTAC) implemented on hybrid PET/CT systems. However, this approach is not attractive for clinical use owing to increased patient dose. The authors propose a novel energy mapping approach referred to as virtual DECT (VDECT) taking advantage of the DECT formulation but using CT data acquired at a single energy (kV P ). For this purpose, the CT image acquired at one energy is used to generate the CT image at a second energy using calculated kV P conversion curves derived from phantom studies. Methods: The attenuation map (l-map) at 511 keV was generated for the XCAT phantom and clinical studies using the bilinear, DECT, and VDECT techniques. The generated l-maps at 511 keV are compared to the reference derived from the XCAT phantom serving as ground truth. PET data generated from a predefined activity map for the XCAT phantom were then corrected for attenuation using l-maps generated using the different energy mapping approaches. In addition, the generated l-maps using the above described methods for a cylindrical polyethylene phantom containing different concentrations of K 2 HPO 4 in water were compared to actual attenuation coefficients. Likewise, CT images of five clinical whole-body studies were used to generate l-maps using the various energy-mapping approaches were compared with l-maps acquired at 511 keV using 68 Ge/ 68 Ga rod sources for the clinical studies. Results: The results of phantom studies demonstrate that the proposed method is more accurate than the bilinear technique. All three l-maps yielded almost similar results for soft and lung tissues whereas for bone tissues, the DECT and the VDECT methods produced a much smaller mean relative difference (3.0% and 2.8%, respectively) than the bilinear approach (11.8%). Likewise, the comparison of PET images corrected for attenuation using the various methods showed that the proposed method provides better accuracy (6.5%) than the bilinear method (13.4%). Clinical studies further demonstrated that, compared to the bilinear method, the VDECT approach has better agreement for bony structures with the DECT technique (1.5% versus 8.9%) and transmission scanning (8.8% versus 17.7%).

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Section: Discussionmentioning

confidence: 99%

Section: Iib Energy-mapping Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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A novel energy mapping approach for CT‐based attenuation correction in PET

Teimourian

Zafarghandi

et al. 2012

Medical Physics

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Investigating the feasibility of generating dual‐energy CT from one 120‐kVp CT scan: a phantom study

Huang

Jhan

Yang

2021

J Applied Clin Med Phys

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Introduction This study aimed to investigate the feasibility of generating pseudo dual‐energy CT (DECT) from one 120‐kVp CT by using convolutional neural network (CNN) to derive additional information for quantitative image analysis through phantom study. Methods Dual‐energy scans (80/140 kVp) and single‐energy scans (120 kVp) were performed for five calibration phantoms and two evaluation phantoms on a dual‐source DECT scanner. The calibration phantoms were used to generate training dataset for CNN optimization, while the evaluation phantoms were used to generate testing dataset. A CNN model which takes 120‐kVp images as input and creates 80/140‐kVp images as output was built, trained, and tested by using Caffe CNN platform. An in‐house software to quantify contrast enhancement and synthesize virtual monochromatic CT (VMCT) for CNN‐generated pseudo DECT was implemented and evaluated. Results The CT numbers in 80‐kVp pseudo images generated by CNN are differed from the truth by 11.57, 16.67, 13.92, 12.23, 10.69 HU for syringes filled with iodine concentration of 2.19, 4.38, 8.75, 17.5, 35 mg/ml, respectively. The corresponding results for 140‐kVp CT are 3.09, 9.10, 7.08, 9.81, 7.59 HU. The estimates of iodine concentration calculated based on the proposed method are differed from the truth by 0.104, 0.603, 0.478, 0.698, 0.795 mg/ml for syringes filled with iodine concentration of 2.19, 4.38, 8.75, 17.5, 35 mg/ml, respectively. With regards to image quality enhancement, VMCT synthesized by using pseudo DECT shows the best contrast‐to‐noise ratio at 40 keV. Conclusion In conclusion, the proposed method should be a practicable strategy for iodine quantification in contrast enhanced 120‐kVp CT without using specific scanner or scanning procedure.

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PET/MRI attenuation estimation in the lung: A review of past, present, and potential techniques

et al. 2020

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Positron emission tomography/magnetic resonance imaging (PET/MRI) potentially offers several advantages over positron emission tomography/computed tomography (PET/CT), for example, no CT radiation dose and soft tissue images from MR acquired at the same time as the PET. However, obtaining accurate linear attenuation correction (LAC) factors for the lung remains difficult in PET/MRI. LACs depend on electron density and in the lung, these vary significantly both within an individual and from person to person. Current commercial practice is to use a single‐valued population‐based lung LAC, and better estimation is needed to improve quantification. Given the under‐appreciation of lung attenuation estimation as an issue, the inaccuracy of PET quantification due to the use of single‐valued lung LACs, the unique challenges of lung estimation, and the emerging status of PET/MRI scanners in lung disease, a review is timely. This paper highlights past and present methods, categorizing them into segmentation, atlas/mapping, and emission‐based schemes. Potential strategies for future developments are also presented.

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Comparative Assessment of Energy-Mapping Approaches in CT-Based Attenuation Correction for PET

Cited by 29 publications

References 27 publications

A novel energy mapping approach for CT‐based attenuation correction in PET

A novel energy mapping approach for CT‐based attenuation correction in PET

Investigating the feasibility of generating dual‐energy CT from one 120‐kVp CT scan: a phantom study

PET/MRI attenuation estimation in the lung: A review of past, present, and potential techniques

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