Three-dimensional broadband terahertz synthetic aperture imaging

Henry, S. G. B.; Zurk, Lisa M.; Schecklman, Scott; Duncan, Donald D.

doi:10.1117/1.oe.51.9.091603

Cited by 22 publications

(9 citation statements)

References 16 publications

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“…However, we have not yet developed any robust signal processing and data analysis routines to extract quantitative measurements based on this approach. A study by Henry et al25 suggests that this might be possible in principle. Terahertz technology is a recent technique and more work into understanding the fundamental physics of scattering in porous media is required before such an application becomes quantitative.…”

Section: Resultsmentioning

confidence: 99%

Natural approach against lipotoxic traffic in nonalcoholic fatty liver disease

Nobili¹,

Bedogni²,

Alisi³

et al. 2010

Hepatology

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We read with great interest the article by Azzalini et al., 1 who demonstrated that cigarette smoking worsens the severity of nonalcoholic fatty liver disease (NAFLD) in obese Zucker rats. In a related letter, Xu and coworkers 2 showed that cigarette smoking may act as a cofactor but not as an independent factor for NAFLD in humans. However, currently it is uncertain whether there is a significant association between smoking patterns and the severity of liver histology among patients with NAFLD. Clarification of this aspect may help to explain the underlying mechanisms and may be of clinical importance in planning preventive and therapeutic strategies. We have therefore assessed whether there is a significant association between liver histology and smoking patterns among patients with biopsy-proven NAFLD.A total of 90 consecutive outpatients with NAFLD (43 males and 47 females, mean age, 47 6 8 years) were recruited from our clinics. All patients had chronically elevated liver enzymes and hepatic steatosis detected by ultrasonography. The NAFLD diagnosis was based on liver biopsy and exclusion of other known etiologic factors of chronic liver disease (alcohol abuse or intake !20 g/day, viral hepatitis, autoimmune hepatitis, and use of hepatotoxic drugs). An experienced pathologist blinded to clinical data scored the liver biopsies according to the National Institute of Diabetes and Digestive and Kidney Diseases NASH Clinical Research Network scoring system. 3 Pack-years of smoking were calculated as the product of the duration of smoking (in years) and the average number of cigarettes smoked per day. The protocol was approved by the local ethics committee, and all participants gave written informed consent. In multivariable-adjusted linear logistic regression models, each histological feature of NAFLD (i.e., steatosis grade, necroinflammatory grade, or fibrosis stage analyzed separately) was considered as the dependent variable. Sex, age, body mass index, smoking, low-density lipoprotein cholesterol, homeostasis model assessment of insulin resistance (HOMA-IR) score, and metabolic syndrome (considered as a single clinical entity) were included as covariates.A total of 30 patients had ever smoked, 26 were past smokers, whereas 34 were current smokers. The distribution of nonsmokers, past smokers, and current smokers was not different in NAFLD patients classified according to liver histopathology (steatosis alone, borderline steatohepatitis, definite steatohepatitis). Notably, pack-years of smoking were not associated with degree of hepatic steatosis (P ¼ 0.67), necroinflammation (P ¼ 0.34), and fibrosis among patients with NAFLD (P ¼ 0.41). These results suggest that the severity of liver histopathology among patients with NAFLD is not associated with smoking patterns, after allowance for classical risk factors, insulin resistance, and the presence of the metabolic syndrome.This study has shown for the first time that the histological severity of NAFLD is not independently predicted by smoking patterns after adjus...

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Section: Resultsmentioning

confidence: 99%

Natural approach against lipotoxic traffic in nonalcoholic fatty liver disease

Nobili¹,

Bedogni²,

Alisi³

et al. 2010

Hepatology

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“…Synthetic aperture measurements were then carried out on the test object in a monostatic configuration described thoroughly in [4] and [5] with the object's front surface placed approximately 16 mm below the planar synthetic aperture. While the autocorrelation of the THz pulses produced by the system have a full width at half maximum of 2.7 ps, corresponding to a maximum bandwidth of 0.37 THz, the aperture spacing in x and y was kept to 0.060 mm to satisfy λ/4 spatial sampling up to ≈1.25 THz.…”

Section: Resultsmentioning

confidence: 99%

“…Phased array techniques, such as THz synthetic aperture (SA) tomography [4,5], offer an alternative with several advantages over conventional TPI. They allow a high degree of depth resolution without sacrificing spectral information and enable dynamic focusing to multiple depths using a single data set [6].…”

Section: Introductionmentioning

confidence: 99%

“…They allow a high degree of depth resolution without sacrificing spectral information and enable dynamic focusing to multiple depths using a single data set [6]. While 3D THz SA tomographic imaging has already been demonstrated on objects with planar boundaries [5], the more general case of objects with non-planar boundaries remains a significant barrier that will need to be overcome before such methods can be integrated into standard practice in the field of NDE. The authors' previous work [7] addressed this challenge directly by developing a procedure for correcting for the refraction introduced by curved surfaces using a parabolic equation method -split-step Fourier (SSF) back propagation -commonly used in underwater acoustics and seismology [8].…”

Section: Introductionmentioning

confidence: 99%

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Terahertz non-destructive sensing of layered materials with curved surfaces

Kniffin

Zurk

2015

2015 16th International Radar Symposium (IRS)

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Terahertz (THz) imaging has shown great potential for nondestructive evaluation (NDE) of a wide variety of manufactured products. Its ability to penetrate many non-polar dielectrics allows tomographic imaging of an object's 3D structure. The authors' previous work demonstrated the ability to produce 3D THz tomographic images of objects using a single data set collected in a 2D synthetic aperture configuration. This ability was recently expanded to allow imaging to within objects with curved boundaries by employing a split-step Fourier method to numerically back propagate the measured fields to the set of image planes that comprise the 3D tomographic image. This work presents new experimental results that demonstrate the split-step Fourier method's ability to correct for refraction and accurately quantify the thickness of a curved dielectric layer.

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“…A sample whose Figure 10 Schematic illustration of tomographic imaging with Fresnel lens extracted from [163] thickness is comparable to or greater than the Rayleigh length will not be correctly or fully imaged in depth. In those cases, SA measurements can be of great interest [166,167].…”

Section: Synthetic Aperture Processing (Sa)mentioning

confidence: 99%