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Observation
April 2015

High-Dynamic-Range Dermoscopy Imaging and Diagnosis of Hypopigmented Skin Cancers

Author Affiliations
  • 1Department of Dermatology, University Hospital Zürich, Zürich, Switzerland
  • 2Dermatology Service, Memorial Sloan Kettering Cancer Center, New York, New York
 

Copyright 2015 American Medical Association. All Rights Reserved. Applicable FARS/DFARS Restrictions Apply to Government Use.

JAMA Dermatol. 2015;151(4):456-457. doi:10.1001/jamadermatol.2014.4714

Acquiring digital dermoscopy images has become routine practice in the offices of many dermatologists around the world. While the main purposes of acquiring digital dermoscopy images are documentation and short- and long-term monitoring,1,2 these images can be enhanced to magnify features or sharpen contrast, making it easier to better visualize dermoscopic structures that are otherwise not as conspicuous.3,4 The photographic technique known as high-dynamic-range (HDR) imaging, a digital technique that produces a greater dynamic range (DR) of luminosity across the image than standard imaging, can enhance some dermoscopic structures.

In digital photography, DR describes the ratio between the maximum and minimum of detectable light intensities. It is measured in exposure value (EV) differences (known as stops) between the brightest and darkest parts of the image that show detail. An increase of 1 EV represents a doubling of the light intensity. The DR of the human eye is 6.5 EVs. Modern digital cameras have a DR up to 14 EVs, which is far superior to that of the human eye.

High-dynamic-range images are normally produced by capturing multiple standard photographs at different exposure settings: One image is taken underexposed (too dark), another with normal exposure, and a third overexposed (too bright). These images are subsequently combined to form a single image with a broader tonal range.

Dermoscopy attachments for mobile phones are now readily available and are already widely used for routine documentation purposes. While HDR image acquisition was previously relegated to only high-end digital single-lens-reflex cameras, the new generation of mobile phones is now able to acquire good-quality HDR images. Thus, it is now possible to effortlessly capture HDR images by simply turning on the HDR mode in the camera settings on their mobile phone.

Report of Case

To illustrate the usefulness of HDR dermoscopy, we present the case of a patient with a hypopigmented macule of unknown duration located on the back. A standard dermoscopic image of this lesion is seen in the Figure, A, while Figure, B shows the HDR dermoscopic image of the same lesion. The pigmented structures at the periphery are more conspicuous in HDR mode and can now easily be identified as spoke wheellike structures and leaflike areas. The blood vessels are also rendered more conspicuous and can now be easily identified as arborizing telangiectasia. Furthermore, the crystalline structures in the center of the lesion have become more noticeable. While the diagnosis of basal cell carcinoma can be made on the basis of conventional dermoscopy (Figure, A), it is more obvious in the dermoscopic HDR image (Figure, B).

Figure.
Conventional and HDR Dermoscopy Images of a Hypopigmented Basal Cell Carcinoma
Conventional and HDR Dermoscopy Images of a Hypopigmented Basal Cell Carcinoma

A, The conventional dermoscopy image was acquired with an iPhone 4S (Apple Inc) with the high-dynamic-range (HDR) mode turned off. The iPhone was attached to DermLite DL3 dermoscope (3Gen) via the DermLite iPhone connector kit. While the diagnostic dermoscopy structures are visible, they not very conspicuous. B, The HDR dermoscopy image was acquired using the same equipment and techniques as in panel A but with the camera’s HDR mode turned on. The diagnostic dermoscopy criteria such as spoke wheel-like structures and leaflike areas as well as the blood vessels appear more conspicuous than by conventional dermoscopy and can be easily identified.

Discussion

High-dynamic-range dermoscopy images of equivocal hypopigmented lesions have the potential to facilitate accurate dermoscopic diagnosis by making some dermoscopic structures appear more conspicuous. This may be particularly helpful for novice dermoscopy trainees.5 In conclusion, HDR dermoscopy imaging can now easily be acquired with many mobile phone cameras attached to a dermoscope, and these images can serve to augment the physician’s vision, leading to better diagnostic accuracy.

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Article Information

Corresponding Author: Ralph P. Braun, MD, Department of Dermatology, University Hospital Zürich, Gloriastr 31, 8091 Zürich, Switzerland (ralph.braun@usz.ch).

Published Online: December 23, 2014. doi:10.1001/jamadermatol.2014.4714.

Conflict of Interest Disclosures: Dr Braun receives royalties from the Atlas of Dermoscopy, Handbook of Dermoscopy, and Atlas de Dermoscopie and donations of medical equipment from 3GEN and Canfield. Dr Marghoob declares royalties from the Atlas of Dermoscopy and the Handbook of Dermoscopy; consultancies from DermSpectra; honoraria from 3GEN; stock ownership or options in the American Dermoscopy Meeting; grants from 3GEN and Canfield; and donations of medical equipment from 3GEN, Canfield, and Heine. No other disclosures are reported.

References
1.
Kittler  H, Binder  M.  Follow-up of melanocytic skin lesions with digital dermoscopy: risks and benefits.  Arch Dermatol. 2002;138(10):1379.PubMedGoogle ScholarCrossref
2.
Kittler  H, Guitera  P, Riedl  E,  et al.  Identification of clinically featureless incipient melanoma using sequential dermoscopy imaging.  Arch Dermatol. 2006;142(9):1113-1119.PubMedGoogle ScholarCrossref
3.
Seidenari  S, Bellucci  C, Bassoli  S, Arginelli  F, Magnoni  C, Ponti  G.  High magnification digital dermoscopy of basal cell carcinoma: a single-centre study on 400 cases.  Acta Derm Venereol. 2014;94(6):677-682.PubMedGoogle ScholarCrossref
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Blum  A, Ellwanger  U, Luedtke  H.  Features Amplifying Dermoscopy (FAD) for better evaluation in difficult pigmented and non-pigmented melanocytic skin tumors.  J Dtsch Dermatol Ges. 2014;12(1):77-79.PubMedGoogle Scholar
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Sato  T, Tanaka  M.  Improved detection of dermoscopic structures by high dynamic range image conversion. Presented at the American Dermoscopy Meeting; August 15-17, 2013; Glacier National Park, Whitefish, Montana.
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    1 Comment for this article
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    Limitations of High-Dynamic-Range Dermoscopy Imaging (HDRI) dermatologists should take note of
    Shunjie Chua(1)(2), Mark Pitts(3), Jing Li(4) | (1):Duke NUS Graduate Medical School (2) Duke University School of Medicine (3):Pritzker School of Medicine, University of Chicago (4) Jiangsu University Affliated Hospital
    Dear Editor, We read with great interest the article “High-Dynamic-Range Dermoscopy Imaging and Diagnosis of Hypopigmented Skin Cancers”1 by Braun and colleague. This is because it is informs of the potential utility of the use of the high-dynamic-range imaging (HDRI) in dermatology where it can improve the diagnostic accuracy of physicians. It also offers mentions that this can be done by easily by mobile phones which are connected to dermatoscopes, potentially improving the reach and ease of access of this technology. However, the use of HDRI in cellphones for dermatoscopy might not be as perfect as portrayed by the article and we would like to share two limitations of the HDRI which we felt are relevant to its application in dermatology. One limitation is also one of its noted strength in the article. HDRI is known to be able to widen the dynamic range to one that is above the human eye. This feature might be able to make dermatoscopic features more conspicuous and make it helpful for novice dermatoscopic trainees. But it might also result in the production of imaging artifacts. This could potentially lead to potential misinterpretation by trainees. The other limitation lies in the fact that HDRI in cellphones is produced by software which varies between different cellphones and models. There is no industrial standard by which the images are acquired and reconstituted to form the image of higher tonality2. The image captured is also affected by camera characteristics such as gamma curves, sensor resolution, noise, photometric calibration and spectral calibration affect resulting high-dynamic-range images3. The great variety of different cellphones with different HDRI processing software carried by different trainees and physicians could result in high degrees of inter-rater variability and poor reproducibility of findings on lesions. This might bring up problems when findings are being discussed or in contentionAcknowledgements: The authors are thankful for Micheal R Zenn, Howard Levinson,Scott T Hollenbeck , Tey Hong Liang and Jeff Chua Ming Xuan for their supervision and education. References 1. Braun R, Marghoob A. High-Dynamic-Range Dermoscopy Imaging and Diagnosis of Hypopigmented Skin Cancers. JAMA Dermatol.. 2014;:10.2. Asla Sa. High Dynamic Range Image Reconstruction (Synthesis Lectures on Computer Graphics and Animation). Claypool Publishers1 ed. Morgan & 2008.3. Erik Reinhard, Wolfgang Heidrich, Paul Debevec, Sumanta Pattanaik. High Dynamic Range Imaging, Second Edition: Acquisition, Display, and Image-Based Lighting. 2 ed. Morgan Kaufmann; 2010.
    CONFLICT OF INTEREST: None Reported
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