Key Points
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Cancer-related structural alterations in lung tissue and individual cells can often be readily observed, but can be difficult to quantify using conventional metrics, such as length or volume
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Fractals are mathematical constructs that appear infinitely self-similar over a range of scales
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Many biological entities, including the lung, can be considered as fractals within a limited scaling range known as a 'scaling window'
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A fractal dimension (FD) is a non-integer value that relates how the detail and complexity of an object changes with scale
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FD can be used to quantify complex shapes and patterns in a range of clinical and biological images, including those illustrating DNA, cellular architectural, histopathological, and radiological features
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Fractal dimension can detect subtle changes in images and could potentially provide clinically useful information relating to tumour type, stage, and response to therapy
Abstract
Fractals are mathematical constructs that show self-similarity over a range of scales and non-integer (fractal) dimensions. Owing to these properties, fractal geometry can be used to efficiently estimate the geometrical complexity, and the irregularity of shapes and patterns observed in lung tumour growth (over space or time), whereas the use of traditional Euclidean geometry in such calculations is more challenging. The application of fractal analysis in biomedical imaging and time series has shown considerable promise for measuring processes as varied as heart and respiratory rates, neuronal cell characterization, and vascular development. Despite the advantages of fractal mathematics and numerous studies demonstrating its applicability to lung cancer research, many researchers and clinicians remain unaware of its potential. Therefore, this Review aims to introduce the fundamental basis of fractals and to illustrate how analysis of fractal dimension (FD) and associated measurements, such as lacunarity (texture) can be performed. We describe the fractal nature of the lung and explain why this organ is particularly suited to fractal analysis. Studies that have used fractal analyses to quantify changes in nuclear and chromatin FD in primary and metastatic tumour cells, and clinical imaging studies that correlated changes in the FD of tumours on CT and/or PET images with tumour growth and treatment responses are reviewed. Moreover, the potential use of these techniques in the diagnosis and therapeutic management of lung cancer are discussed.
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References
American Cancer Society. Cancer Facts and Figures 2015 [online], (2015).
Siegel, R., Ma, J., Zou, Z. & Jemal, A. Cancer statistics, 2014. CA Cancer J. Clin. 64, 9–29 (2014).
Mozley, P. D. et al. Change in lung tumor volume as a biomarker of treatment response: a critical review of the evidence. Ann. Oncol. 21, 1751–1755 (2010).
Mandelbrot, B. B. The Fractal Geometry of Nature (W. H. Freeman & Co. Ltd, 1982).
Peitgen, H.-O., Ju¨rgens, H. & Saupe, D. Chaos and fractals: New Frontiers of Science 2nd edn (Springer-Verlag, 2004).
Legner, P. Fractals . Mathigon—World of Mathematics [online], (2015).
Ristanovic´, D. & Milosevic´, N. T. Fractal analysis: methodologies for biomedical researchers. Theor. Biol. Forum 105, 99–118 (2012).
Mandelbrot, B. How long is the coast of Britain? Statistical self-similarity and fractional dimension. Science 156, 636–638 (1967).
Eghball, B., Hergert, G. W., Lesoing, G. W. & Ferguson, R. B. Fractal analysis of spatial and temporal variability. Geoderma 88, 349–362 (1999).
Lopes, R. & Betrouni, N. Fractal and multifractal analysis: a review. Med. Image Anal. 13, 634–649 (2009).
Dubuc, B., Quiniou, J. F., Roques-Carmes, C., Tricot, C. & Zucker, S. W. Evaluating the fractal dimension of profiles. Phys. Rev. A 39, 1500–1512 (1989).
Jelinek, H. F. & Fernandez, E. Neurons and fractals: how reliable and useful are calculations of fractal dimensions? J. Neurosci. Methods 81, 9–18 (1998).
Karperien, A., Ahammer, H. & Jelinek, H. F. Quantitating the subtleties of microglial morphology with fractal analysis. Front. Cell. Neurosci. 7, 3 (2013).
Nonnenmacher, T. F., Baumann, G., Barth, A. & Losa, G. A. Digital image analysis of self-similar cell profiles. Int. J. Biomed. Comput. 37, 131–138 (1994).
Smith, T. G. Jr, Lange, G. D. & Marks, W. B. Fractal methods and results in cellular morphology—dimensions, lacunarity and multifractals. J. Neurosci. Methods 69, 123–136 (1996).
Iannaccone, P. M. & Khokha, M. (eds) Fractal Geometry in Biological Systems: An Analytical Approach (CRC Press, 1996).
Peleg, S., Naor, J., Hartley, R. & Avnir, D. Multiple resolution texture analysis and classification. IEEE Trans. Pattern Anal. Mach. Intell. 6, 518–523 (1984).
Tolle, C. R., McJunkin, T. R. & Gorsich, D. J. An efficient implementation of the gliding box lacunarity algorithm. Physica D 237, 10 (2008).
Plotnick, R. E., Gardner, R. H., Hargrove, W. W., Prestegaard, K. & Perlmutter, M. Lacunarity analysis: a general technique for the analysis of spatial patterns. Phys. Rev. E Stat. Phys. Plasmas Fluids Relat. Interdiscip. Topics 53, 5461–5468 (1996).
Borys, P., Krasowska, M., Grzywna, Z. J., Djamgoz, M. B. & Mycielska, M. E. Lacunarity as a novel measure of cancer cells behavior. Biosystems 94, 276–281 (2008).
Weibel, E. R. What makes a good lung? Swiss Med. Wkly 139, 375–386 (2009).
Iber, D. & Menshykau, D. The control of branching morphogenesis. Open Biol. 3, 130088 (2013).
Kitaoka, H., Takaki, R. & Suki, B. A three-dimensional model of the human airway tree. J. Appl. Physiol. (1985) 87, 2207–2217 (1999).
Glenny, R. W. Emergence of matched airway and vascular trees from fractal rules. J. Appl. Physiol. (1985) 110, 1119–1129 (2011).
Fleury, V., Gouyet, J.-F. & Léonetti, M. (eds) Branching in Nature: Dynamics and Morphogenesis of Branching Structures, From Cell to River Networks (Springer-Verlag, 2001).
West, B. J. Physiology in fractal dimensions: error tolerance. Ann. Biomed. Eng. 18, 135–149 (1990).
Nelson, T. R., West, B. J. & Goldberger, A. L. The fractal lung: universal and species-related scaling patterns. Experientia 46, 251–254 (1990).
Alencar, A. M. et al. Physiology: dynamic instabilities in the inflating lung. Nature 417, 809–811 (2002).
Suki, B. et al. Mechanical failure, stress redistribution, elastase activity and binding site availability on elastin during the progression of emphysema. Pulm. Pharmacol. Ther. 25, 268–275 (2012).
Bates, J. H. & Suki, B. Assessment of peripheral lung mechanics. Respir. Physiol. Neurobiol. 163, 54–63 (2008).
Boser, S. R., Park, H., Perry, S. F., Ménache, M. G. & Green, F. H. Fractal geometry of airway remodeling in human asthma. Am. J. Respir. Crit. Care Med. 172, 817–823 (2005).
Gehr, P., Bachofen, M. & Weibel, E. R. The normal human lung: ultrastructure and morphometric estimation of diffusion capacity. Respir. Physiol. 32, 121–140 (1978).
Losa, G. A. The fractal geometry of life. Riv. Biol. 102, 29–59 (2009).
Landini, G. & Rippin, J. W. Quantification of nuclear pleomorphism using an asymptotic fractal model. Anal. Quant. Cytol. Histol. 18, 167–176 (1996).
Bancaud, A. et al. Molecular crowding affects diffusion and binding of nuclear proteins in heterochromatin and reveals the fractal organization of chromatin. EMBO J. 28, 3785–3798 (2009).
Lieberman-Aiden, E. et al. Comprehensive mapping of long-range interactions reveals folding principles of the human genome. Science 326, 289–293 (2009).
Grosberg, A. Y. Nechaev, S. K. & Shakhnovich, E. I. The role of topological constraints in the kinetics of collapse of macromolecules. J. Phys. (France) 49, 2095–2100 (1988).
Metze, K. Fractal dimension of chromatin: potential molecular diagnostic applications for cancer prognosis. Expert Rev. Mol. Diagn. 13, 719–735 (2013).
Peng, C. K. et al. Fractal landscape analysis of DNA walks. Physica A 191, 25–29 (1992).
Peng, C. K. et al. Long-range correlations in nucleotide sequences. Nature 356, 168–170 (1992).
Arakawa, K. et al. Genome Projector: zoomable genome map with multiple views. BMC Bioinformatics 10, 31 (2009).
Jeffrey, H. J. Chaos game representation of gene structure. Nucleic Acids Res. 18, 2163–2170 (1990).
Almeida, J. S. Sequence analysis by iterated maps, a review. Brief. Bioinform. 15, 369–375 (2014).
Tsai, I. J., Otto, T. D. & Berriman, M. Improving draft assemblies by iterative mapping and assembly of short reads to eliminate gaps. Genome Biol. 11, R41 (2010).
Peng, C. K. et al. Quantifying fractal dynamics of human respiration: age and gender effects. Ann. Biomed. Eng. 30, 683–692 (2002).
West, B. J. Fractal physiology and the fractional calculus: a perspective. Front. Physiol. 1, 12 (2010).
Mutch, W. A., Graham, M. R., Girling, L. G. & Brewster, J. F. Fractal ventilation enhances respiratory sinus arrhythmia. Respir. Res. 6, 41 (2005).
Gutierrez, G. et al. Decreased respiratory rate variability during mechanical ventilation is associated with increased mortality. Intensive Care Med. 39, 1359–1367 (2013).
Seely, A. J. et al. Do heart and respiratory rate variability improve prediction of extubation outcomes in critically ill patients? Crit. Care 18, R65 (2014).
Lee, L. H. et al. Digital differentiation of non-small cell carcinomas of the lung by the fractal dimension of their epithelial architecture. Micron. 67, 125–131 (2014).
Vasiljevic, J. et al. Application of multifractal analysis on microscopic images in the classification of metastatic bone disease. Biomed. Microdevices 14, 541–548 (2012).
US National Institutes of Health. ImageJ [online], (2015).
Karperien, A. FracLac for ImageJ. US National Institutes of Health [online], (2013).
Fudenberg, G., Getz, G., Meyerson, M. & Mirny, L. A. High order chromatin architecture shapes the landscape of chromosomal alterations in cancer. Nat. Biotechnol. 29, 1109–1113 (2011).
Misteli, T. Higher-order genome organization in human disease. Cold Spring Harb. Perspect. Biol. 2, a000794 (2010).
Irinopoulou, T., Rigaut, J. P. & Benson, M. C. Toward objective prognostic grading of prostatic carcinoma using image analysis. Anal. Quant. Cytol. Histol. 15, 341–344 (1993).
Streba, C. T. et al. Fractal analysis differentiation of nuclear and vascular patterns in hepatocellular carcinomas and hepatic metastasis. Rom. J. Morphol. Embryol. 52, 845–854 (2011).
Shtivelman, E. et al. Molecular pathways and therapeutic targets in lung cancer. Oncotarget 5, 1392–1433 (2014).
Hayano, K., Yoshida, H., Zhu, A. X. & Sahani, D. V. Fractal analysis of contrast-enhanced CT images to predict survival of patients with hepatocellular carcinoma treated with sunitinib. Dig. Dis. Sci. 59, 1996–2003 (2014).
Kido, S., Kuriyama, K., Higashiyama, M., Kasugai, T. & Kuroda, C. Fractal analysis of internal and peripheral textures of small peripheral bronchogenic carcinomas in thin-section computed tomography: comparison of bronchioloalveolar cell carcinomas with nonbronchioloalveolar cell carcinomas. J. Comput. Assist. Tomogr. 27, 56–61 (2003).
Michallek, F. & Dewey, M. Fractal analysis in radiological and nuclear medicine perfusion imaging: a systematic review. Eur. Radiol. 24, 60–69 (2014).
Miwa, K. et al. FDG uptake heterogeneity evaluated by fractal analysis improves the differential diagnosis of pulmonary nodules. Eur. J. Radiol. 83, 715–719 (2014).
Al-Kadi, O. S. Assessment of texture measures susceptibility to noise in conventional and contrast enhanced computed tomography lung tumour images. Comput. Med. Imaging Graph. 34, 494–503 (2010).
Dimitrakopoulou-Strauss, A. et al. Prediction of short-term survival in patients with advanced nonsmall cell lung cancer following chemotherapy based on 2-deoxy-2-[F-18]fluoro-D-glucose-positron emission tomography: a feasibility study. Mol. Imaging Biol. 9, 308–317 (2007).
Dimitrakopoulou-Strauss, A., Pan, L. & Strauss, L. G. Quantitative approaches of dynamic FDG-PET and PET/CT studies (dPET/CT) for the evaluation of oncological patients. Cancer Imaging 12, 283–289 (2012).
Al-Kadi, O. S. & Watson, D. Texture analysis of aggressive and nonaggressive lung tumor CE CT images. IEEE Trans. Biomed. Eng. 55, 1822–1830 (2008).
Hayano, K., Lee, S. H., Yoshida, H., Zhu, A. X. & Sahani, D. V. Fractal analysis of CT perfusion images for evaluation of antiangiogenic treatment and survival in hepatocellular carcinoma. Acad. Radiol. 21, 654–660 (2014).
Doubal, F. N. et al. Fractal analysis of retinal vessels suggests that a distinct vasculopathy causes lacunar stroke. Neurology 74, 1102–1107 (2010).
Lee, J., Zee, B. C. & Li, Q. Detection of neovascularization based on fractal and texture analysis with interaction effects in diabetic retinopathy. PLoS ONE 8, e75699 (2013).
Talu, S. Fractal analysis of normal retinal vascular network. Oftalmologia 55, 11–16 (2011).
Di Ieva, A. et al. Computer-assisted and fractal-based morphometric assessment of microvascularity in histological specimens of gliomas. Sci. Rep. 2, 429 (2012).
Di Ieva, A. et al. Fractal dimension as a quantitator of the microvasculature of normal and adenomatous pituitary tissue. J. Anat. 211, 673–680 (2007).
Di Ieva, A. et al. Euclidean and fractal geometry of microvascular networks in normal and neoplastic pituitary tissue. Neurosurg. Rev. 31, 271–281 (2008).
Di Ieva, A., Grizzi, F., Sherif, C., Matula, C. & Tschabitscher, M. Angioarchitectural heterogeneity in human glioblastoma multiforme: a fractal-based histopathological assessment. Microvasc. Res. 81, 222–230 (2011).
Goutzanis, L. P. et al. Vascular fractal dimension and total vascular area in the study of oral cancer. Head Neck 31, 298–307 (2009).
Al-Kadi, O. S. A multiresolution clinical decision support system based on fractal model design for classification of histological brain tumours. Comput. Med. Imaging Graph. 41, 67–79 (2014).
Ferro, D. P. et al. Fractal characteristics of May-Grünwald-Giemsa stained chromatin are independent prognostic factors for survival in multiple myeloma. PLoS ONE 6, e20706 (2011).
Pasqualato, A. et al. Shape in migration: quantitative image analysis of migrating chemoresistant HCT-8 colon cancer cells. Cell Adh. Migr. 7, 450–459 (2013).
Pantic, I., Harhaji-Trajkovic, L., Pantovic, A., Milosevic, N. T. & Trajkovic, V. Changes in fractal dimension and lacunarity as early markers of UV-induced apoptosis. J. Theor. Biol. 303, 87–92 (2012).
Fuseler, J. W., Millette, C. F., Davis, J. M. & Carver, W. Fractal and image analysis of morphological changes in the actin cytoskeleton of neonatal cardiac fibroblasts in response to mechanical stretch. Microsc. Microanal. 13, 133–143 (2007).
Park, S. H. et al. Texture analyses show synergetic effects of biomechanical and biochemical stimulation on mesenchymal stem cell differentiation into early phase osteoblasts. Microsc. Microanal. 20, 219–227 (2014).
Qian, A. R. et al. Fractal dimension as a measure of altered actin cytoskeleton in MC3T3-E1 cells under simulated microgravity using 3-D/2-D clinostats. IEEE Trans. Biomed. Eng. 59, 1374–1380 (2012).
Qi, Y. X., Wang, X. D., Zhang, P. & Jiang, Z. L. Fractal and Image Analysis of Cytoskeletal F-Actin Orgnization in Endothelial Cells under Shear Stress and Rho-GDIα Knock Down in 6th World Congress of Biomechanics (WCB 2010): In Conjunction with 14th International Conference on Biomedical Engineering (ICBME) and 5th Asia Pacific Conference on Biomechanics (APBiomech). IFMBE Proceedings Vol. 31 (eds Lim, C. T. & Goh, J. C.) 1051–1054 (Springer, 2010).
Di Ieva, A. Fractal analysis of microvascular networks in malignant brain tumors. Clin. Neuropathol. 31, 342–351 (2012).
Brodatz, P. Textures: A Photographic Album for Artists and Designers (Peter Smith Publisher, Incorporated, 1981).
Florindo, J. B., Landini, G. & Bruno, O. M. Texture descriptors by a fractal analysis of three-dimensional local coarseness. Digit. Signal Process. 42, 70–79 (2015).
Jimenez, J. et al. A Web platform for the interactive visualization and analysis of the 3D fractal dimension of MRI data. J. Biomed. Inform. 51, 176–190 (2014).
Vakoc, B. J. et al. Three-dimensional microscopy of the tumor microenvironment in vivo using optical frequency domain imaging. Nat. Med. 15, 1219–1223 (2009).
Véhel, J. L. & Legrand, P. Signal and image processing with FracLab in Thinking in Patterns: Fractals and Related Phenomena in Nature (ed. Novak. M. M.). 321–322 (World Scientific, 2004).
ThéMA. Fractalyse—Fractal Analysis Software [online], (2015).
Silijkerman, F. Ultra fractal 5 [online], (2014).
Reuter, M. Image Analysis: Fractal Dimension—FDim [online], (2015).
Acknowledgements
The work of the authors is supported in part by the NIH National Cancer Institute (grant P30 CA014599 to the University of Chicago Cancer Research Foundation). The work of R.S. is supported by the Mesothelioma Applied Research Foundation, the Guy Geleerd Memorial Golf Invitational–V-Foundation for Cancer Research.
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F.E.L., G.C.C., N.A.C., T.A.H., M.W.V. and R.S. wrote the article and contributed to all stages of the preparation of the manuscript for submission. In addition, H.J.Z. and C.-T.C. contributed to researching data for the article, and S.D.M. and E.E.V. made substantial contributions to discussion of content. All authors reviewed/edited the manuscript before submission.
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Supplementary information
Sierpinski gasket chaos game.
This video demonstrates the Sierpinski triangle chaos game. The game unfolds as follows: the corners of a triangle are labelled with the numbers 1–6, assigning two numbers to each corner. Starting at a random point plotted within the triangle, a die is cast and a new point is plotted halfway from the starting point towards the corner labelled with the number rolled; this process is repeated for multiple iterations, plotting a new point for each roll of the die. After sufficient iterations, the ensemble of points visited during the game forms a fractal image, in this case the Sierpinski gasket, which is shown in the final frame. (MOV 692 kb)
Self-similarity across multiple scales of the fractal image generated by chaos game representation of the chromosome 2 DNA sequence.
The fractal pattern of a chaos game was generated using the DNA sequence of chromosome 2, as shown in Figure 4b. In this chaos game, each corner of a square was assigned a DNA base (either A, C, G, or T), and starting at point in the centre of the square, a new point was plotted at half the distance from this point towards the corner corresponding to the first base in the DNA sequence of chromosome 2; the next point was plotted halfway between this position and the corner corresponding to the second base. This process was repeated for each base in the DNA sequence. In this video we zoom in on the resulting fractal image, to illustrate a defining feature of a fractal: self-similarity over a range of scales. (MOV 12433 kb)
Supplementary Figure 1
Method of calculating the fractal dimension of histological samples. (DOC 2588 kb)
Supplementary Figure 2
Method of calculating the fractal dimension of lung tumour–stroma interface on clinical contrast-enhanced CT images. (DOC 287 kb)
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Lennon, F., Cianci, G., Cipriani, N. et al. Lung cancer—a fractal viewpoint. Nat Rev Clin Oncol 12, 664–675 (2015). https://doi.org/10.1038/nrclinonc.2015.108
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DOI: https://doi.org/10.1038/nrclinonc.2015.108