Liver virtual non-enhanced CT with dual-source, dual-energy CT: a preliminary study

Zhang, Longjiang; Peng, Jin; Wu, Shengyong; Wang, Z. Jane; Wang, Xinsheng; Zhou, Changsheng; Xueman, Ji; Lu, Guangming

doi:10.1007/s00330-010-1778-7

Cited by 129 publications

(69 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Moreover, the CNR was significantly higher in VNE images, and VNE images showed lower noise than TNE images, which was attributed to the noise reduction filter. Our results agreed with those of several previous studies in patients after endovascular aneurysm repair, patients with renal and adrenal masses, and patients with liver parenchymal lesions [19][20][21][22], demonstrating a comparable image quality of VNE images to that of TNE images. Therefore, if we omitted the acquisition of TNE images from our pancreatic protocol CT imaging, which was composed of pre-contrast, pancreatic and hepatic venous phase images, we could reduce approximately 14.14% (mean51.36 mSv) of the total radiation dose of our routine pancreatic protocol CT imaging (mean59.65 mSv).…”

Section: Discussionsupporting

confidence: 92%

Dual-source, dual-energy multidetector CT for the evaluation of pancreatic tumours

Chu

Lee²,

Lee³

et al. 2012

BJR

View full text Add to dashboard Cite

Objective: To investigate the potential diagnostic value of dual-energy CT (DECT) with virtual non-enhanced (VNE) and iodine-only images, and to determine the optimal mixed ratio of blended images for evaluation of pancreatic diseases. Methods: Multiphasic DECT was performed in 44 patients with focal pancreatic disease. DECT was used during the pancreatic and hepatic venous phases, and a peak kilovoltage of 120 kVp was used for both non-contrast phases. For qualitative analysis of the CT images, two radiologists assessed three image sets (VNE, iodine-only and blended images) in order to determine the acceptability of VNE in replacing true nonenhanced (TNE) images, the added value of iodine-only images and the preferred blending ratio. For quantitative analyses, the CT numbers and image noise of the pancreatic parenchyma, lesions, aorta and psoas muscle were measured. The contrastto-noise ratio of the lesion was calculated on the pancreatic phase images. The effective radiation dose for DECT and TNE images was calculated. Statistical comparisons were made using the Friedman test, the Wilcoxon test, the paired t-test and repeated measures of analysis of variation with Bonferroni correction for multiple comparisons.Results: The level of acceptance of the VNE images in replacing TNE images was 90.9%. Regarding the iodine-only images, 50% of the cases were found to have an added value. The linear-blended images with a weighting factor of 0.5 were preferred. Conclusions: DECT was able to provide high-quality VNE images that could replace TNE images and iodine-only images showing an added value. Blended images with a weighting factor of 0.5 were preferred by the reviewers. Radiological imaging is an important component in the evaluation of pancreatic disease. CT has been the initial imaging modality of choice for evaluating pancreatic pathology [1]. Recent improvements in multidetector CT (MDCT) technology, including its improved temporal and spatial resolution, facilitate the precise timing of multiphasic imaging, and have also increased the accuracy of CT for lesion detection and characterisation in the pancreas [2]. However, there are still certain problematic imaging scenarios such as the early detection of pancreatic adenocarcinoma, detection of occult neoplasms in the setting of acute or chronic pancreatitis, accuracy of pre-operative surgical staging of pancreatic malignancy and characterisation of pancreatic cystic lesions. For example, with surgical resection, a 5-year survival rate of 20% is possible only when a pancreatic cancer is small (,2 cm diameter) and there is no peripancreatic invasion [3]. Unfortunately, however, only 10-15% of pancreatic carcinomas are in this category, resulting in an overall poor survival rate [4]. These problems could be related to the inherent, limited soft-tissue contrast of MDCT or to the limited difference in vascularity between normal parenchyma and pathological lesions. Therefore, if the contrast between pancreatic lesions and pancreatic parenchyma is improved on CT scans,...

show abstract

Section: Discussionsupporting

confidence: 92%

Dual-source, dual-energy multidetector CT for the evaluation of pancreatic tumours

Chu

Lee²,

Lee³

et al. 2012

BJR

View full text Add to dashboard Cite

show abstract

“…Zhang et al (92) recently reported that the avoidance of non-contrast CT in a multiphasic CT protocol might reduce the radiation dose. De Cecco et al (93) reported similar findings, but they stated that an optimal virtual non-contrast image was only possible in patients with a low BMI.…”

Section: Gastrointestinal and Abdominal Applicationsmentioning

confidence: 99%

“…The effective dose ranges from 22.5 to 36.4 mSv and from 9.4 to 13.8 mSv for DECT and single-energy CT imaging, respectively. An increased radiation dose can be justified when unenhanced CT images are eliminated from the CT protocols, which may result in an overall radiation dose saving (92,93,105,106). Beam-hardening artifacts can be observed in thorax perfusion DECT due to the dense contrast in the superior vena cava, which can mimic an embolus.…”

Section: Limitations Of Dual-energy Mdctmentioning

confidence: 99%

Dual-energy CT revisited by multidetector ct: review of principles and clinical applications

Karçaaltıncaba

Aktaş²

2010

Diagn Interv Radiol

152

127

View full text Add to dashboard Cite

A lthough dual-energy CT (DECT) was first conceived in 1976, it has not been used widely for clinical indications (1-11). Recently, the simultaneous acquisition of dual-energy data has been introduced using multidetector CT (MDCT) with two X-ray tubes and rapid peak kilovoltage (kVp) switching (gemstone spectral imaging, GSI) (12-16). Two major advantages of DECT are material decomposition by the almost simultaneous acquisition of two image series with different kVp (80 and 140 kVp) and the elimination of misregistration artifacts. In general, noncontrast (unenhanced) images can be avoided by using the dual-energy mode for body and neurological applications; iodine can be removed from the image, and a virtual non-contrast (water) image can be acquired. The major advantage of 80-kVp compared to 140-kVp images is a higher image contrast (Fig. 1). Hounsfield unit measurements on DECT are not absolute and can change depending on the kVp used for the acquisition (at different keV). Typically, a combination of 80/140 kVp is used for DECT, but for some applications, 100/140 kVp is preferred. In this study, we summarized the clinical applications of DECT in the brain, chest and abdomen and in the cardiovascular and musculoskeletal systems (Table 1). Technique and principlesThe basic principle of dual-energy is the acquisition of 2 datasets from the same anatomic location with different kVp (usually 80 and 140 kVp) (1,2,17,18). In the early days of CT, consecutive single-slice acquisitions with different kVp were performed as a dual-energy technique, but this method suffered from breathing and partial volume artifacts (1, 2). At present, an entire body can be scanned within seconds using the DECT technique, and thus, misregistration artifacts due to breathing are eliminated.Currently, three systems are capable of the nearly simultaneous acquisition of dual-energy data during a single breath hold (12, 14, 15): 64-slice dual-source CT (Definition, Siemens Medical Systems; Erlangen, Germany), 128-slice dual-source CT (Definition Flash, Siemens Medical Systems) and high-definition 64-MDCT (Discovery 750 HD, GE Healthcare; Milwaukee, Wisconsin, USA). In the two systems available from Siemens, the two tubes (tubes A and B) use different kVp (80 and 140 kVp), and in 64-MDCT, the kVp switches from 80 to 140 kVp in less than 0.5 ms. In dual systems, there is concern regarding the susceptibility of the system to cardiac motion due to the time difference (75 or 83 ms) between the tube A and tube B acquisitions of the dual-energy data, but the dual-source CT and 64-MDCT have not been compared to evaluate this issue. The technical specifications of the DECT systems are summarized in Table 2.The images presented in this article were acquired using a 64-slice dual source CT (Definition, Siemens Medical Systems) and a 64-MDCT (Discovery 750HD, GE Healthcare). The DECT data acquired by both systems can be evaluated with a dedicated workstation using dual-energy software that ABSTRACT Although dual-energy CT (DECT) was first conceived in ...

show abstract

“…To reduce errors stemming from the CT image noise, we generate a first-pass similarity matrix from a noisy CT image and suppress noise on the CT image by matrix multiplication shown in Eq. (9). An updated similarity matrix is then produced on the noise-suppressed CT image.…”

Section: B Penalized Weighted Least-square Optimization With Similmentioning

confidence: 99%

“…Dual-energy CT (DECT) has been increasingly used for iodine quantification, 1 kidney stone characterization, [2][3][4] virtual monochromatic imaging, 5,6 lung perfusion/ventilation studies, 7 and virtual nonenhanced images [8][9][10] among a growing list of diagnostic applications. However, material differentiation via DECT still suffers from noise amplification during the signal decomposition process.…”

Section: Introductionmentioning

confidence: 99%

Noise suppression for dual-energy CT via penalized weighted least-square optimization with similarity-based regularization

et al. 2016

View full text Add to dashboard Cite

Purpose: Dual-energy CT (DECT) expands applications of CT imaging in its capability to decompose CT images into material images. However, decomposition via direct matrix inversion leads to large noise amplification and limits quantitative use of DECT. Their group has previously developed a noise suppression algorithm via penalized weighted least-square optimization with edge-preservation regularization (PWLS-EPR). In this paper, the authors improve method performance using the same framework of penalized weighted least-square optimization but with similarity-based regularization (PWLS-SBR), which substantially enhances the quality of decomposed images by retaining a more uniform noise power spectrum (NPS). Methods: The design of PWLS-SBR is based on the fact that averaging pixels of similar materials gives a low-noise image. For each pixel, the authors calculate the similarity to other pixels in its neighborhood by comparing CT values. Using an empirical Gaussian model, the authors assign high/low similarity value to one neighboring pixel if its CT value is close/far to the CT value of the pixel of interest. These similarity values are organized in matrix form, such that multiplication of the similarity matrix to the image vector reduces image noise. The similarity matrices are calculated on both high-and low-energy CT images and averaged. In PWLS-SBR, the authors include a regularization term to minimize the L-2 norm of the difference between the images without and with noise suppression via similarity matrix multiplication. By using all pixel information of the initial CT images rather than just those lying on or near edges, PWLS-SBR is superior to the previously developed PWLS-EPR, as supported by comparison studies on phantoms and a head-and-neck patient. Results: On the line-pair slice of the Catphan C 600 phantom, PWLS-SBR outperforms PWLS-EPR and retains spatial resolution of 8 lp/cm, comparable to the original CT images, even at 90% reduction in noise standard deviation (STD). Similar performance on spatial resolution is observed on an anthropomorphic head phantom. In addition, results of PWLS-SBR show substantially improved image quality due to preservation of image NPS. On the Catphan C 600 phantom, NPS using PWLS-SBR has a correlation of 93% with that via direct matrix inversion, while the correlation drops to −52% for PWLS-EPR. Electron density measurement studies indicate high accuracy of PWLS-SBR. On seven different materials, the measured electron densities calculated from the decomposed material images using PWLS-SBR have a root-mean-square error (RMSE) of 1.20%, while the results of PWLS-EPR have a RMSE of 2.21%. In the study on a head-and-neck patient, PWLS-SBR is shown to reduce noise STD by a factor of 3 on material images with image qualities comparable to CT images, whereas fine structures are lost in the PWLS-EPR result. Additionally, PWLS-SBR better preserves low contrast on the tissue image. Conclusions: The authors propose improvements to the regularization term of an optimization frame...

show abstract

Liver virtual non-enhanced CT with dual-source, dual-energy CT: a preliminary study

Abstract: VNCT(A) may potentially replace TNCT as part of a multi-phase liver imaging protocol with consequent saving in radiation dose.

Cited by 129 publications

References 17 publications

Dual-source, dual-energy multidetector CT for the evaluation of pancreatic tumours

Dual-source, dual-energy multidetector CT for the evaluation of pancreatic tumours

Dual-energy CT revisited by multidetector ct: review of principles and clinical applications

Noise suppression for dual-energy CT via penalized weighted least-square optimization with similarity-based regularization

Contact Info

Product

Resources

About