fast fourier transform (fft) low pass filter  (MathWorks Inc)

Journal: Cancers

Article Title: Assessment of Ovarian Tumor Growth in Wild-Type and Lumican-Deficient Mice: Insights Using Infrared Spectral Imaging, Histopathology, and Immunohistochemistry

doi: 10.3390/cancers13235950

Figure Lengend Snippet: Analysis of collagen organization in ovarian tumor sections of wild-type and lumican-deficient mice. ( a , b ) Representative microphotographs of s.c. allograft sections stained with HES (top panel, original magnification 20×, scale bar 500 µm) in Lum +/+ ( a ) and Lum −/− mice ( b ); ( c – f ) Picrosirius red and SHG image analyses of ovarian allografts in tumors implanted in Lum +/+ mice ( c , d ) and in tumors from Lum −/− mice ( e , f ); ( c , e ) Collagen SHG images from ID8 ovarian tumors (original magnification 20×); ( d , f ) Ovarian tumor sections stained with Picrosirius red and viewed under widefield cross-polar optics (original magnification 20×, scale bar 50 µm). Birefringence of collagen fibers allows distinction between type I (red) and type III (green) collagens; ( g ) Analysis of collagen fibers intensity by SHG in tumors and healthy tissues present in each section (mean ± SD, ns: not significant); ( h ) Analysis of tumor ECM collagen organization from images derived from Gabor filtering and FFT, processed on Picrosirius red images (mean ± SD, ns: not significant); ( i ) Quantification on Picrosirius red stained sections of the relative distribution of red pixels (corresponding to type I collagen) in tumor ECM of Lum +/+ and Lum −/− sections (mean ± SD, * p < 0.05); ( j ) Quantification on Picrosirius red stained sections of the relative distribution of green pixels (corresponding to type III collagen) within tumors of Lum +/+ and Lum −/− sections (mean ± SD, * p < 0.05).

Article Snippet: To assess the basketweave structure of collagen, an innovative bioimaging approach combining Fast Fourier Transform (FFT) with Gabor filtering was applied [ ].

Techniques: Staining, Derivative Assay

Journal: Scientific Reports

Article Title: Lumican delays melanoma growth in mice and drives tumor molecular assembly as well as response to matrix-targeted TAX2 therapeutic peptide

doi: 10.1038/s41598-017-07043-9

Figure Lengend Snippet: Investigation of the relationship between lumican and intratumoral collagen organization. ( a ) Representative microphotographs of s.c. allograft sections stained with picrosirius red and viewed under dark-field cross-polar optics (original magnification ×63). Birefringence of collagen fibers allows distinction between type I (red) and type III (green) collagen. ( b , c ) Quantification of the relative distribution of red ( b , left panel ) and green ( c , left panel ) pixels as well as the corresponding intensities ( b and c , right panels ), expressed as a percentage of mean pixel intensity in the Lum +/+ (WT) group (mean ± SEM, t test, * p < 0.05). ( d ) Quantification of type I/type III ratio based on red and green pixel calculations, respectively. Individual ratios were calculated from 3 different fields per animal, and then averaged (mean ± SEM, t test, *** p < 0.001). ( e – g ) Quantification of tumor ECM collagen organization from spectra derived from Gabor filtering and FFT. ( e ) Flowchart depicting the different stages of image analysis. From grey scale-converted picrosirius-stained images, a 3 × 3 median filter is applied before Gabor filtering and then FFT. After determining the elliptical shape of the scatter pattern (see red ellipses on right panel ), measurements of the elliptical axes ( black lines ) generated from ω angle values n 1 to n 4 were performed so as to produce a collagen orientation index (N), according to displayed equations ( inset ). ( f ) Histogram displays results of collagen orientation index determination within melanoma tumors allografted to Lum +/+ or Lum −/− mice (mean ± SEM, t test, ** p < 0.01). ( g ) Correlation between calculated collagen orientation index and final tumor volume in Lum +/+ (WT, black dots ) and Lum −/− ( red dots ) mice. Linear regression was performed ( black line ) and r coefficient arising from non-parametric two-tailed Spearman test was determined. ( h ) Representative collagen SHG images from B16F1 tumors (original magnification ×20). ( i ) Collagen density of SHG images for s.c. allografts of Lum +/+ and Lum −/− animals (mean ± SEM, t test, ** p < 0.01). ( j ) Representative polar plots of SHG intensity vs . angle of laser polarization.

Article Snippet: To assess the basketweave structure of collagen, an innovative bioimaging approach combining Fast Fourier Transform (FFT) with Gabor filtering was applied .

Techniques: Staining, Derivative Assay, Generated, Two Tailed Test