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Assessment of Diagnostic Accuracy Using a Digital Camera for ...

  1. 1. Assessment Of Diagnostic Accuracy Using A Digital Camera For Teledermatology
  2. 2. Elizabeth Krupinski, PhD Ben LeSueur, BS Lansing Ellsworth, MD Norman Levine, MD Ronald Hansen, MD Nancy Silvis, MD Peter Sarantopoulos, BS Pamela Hite, MD, MBA James Wurzel, BS Ronald Weinstein, MD Ana Marie Lopez, MD, MPH
  3. 3. Patients’ Opinions* • 24% satisfied by care from non-dermatologist • 89% satisfied by care from a dermatologist • 6% believe a generalist can treat their skin disease • 87% say access to dermatologist very important to their health care *Owen SA, Maeyens E, Weary PE. Patients’ opinions regarding direct access to dermatologic specialty care. JAAD 1997;36:250-256.
  4. 4. Goal The goal of this study was to compare diagnostic accuracy of a dermatologic diagnosis based on in-person examination compared to diagnosis with still photo images acquired with a digital camera and displayed on a CRT monitor.
  5. 5. Rationale Real-time video conferencing technologies may not be available or may be too costly for some rural sites. Store-forward technologies may be more appropriate, and should be tested before they are used clinically.
  6. 6. Subjects & Readers • 308 consecutive patients referred for specialty consultation by PCP or general dermatologist to the Dermatology Clinic at the University of Arizona Health Sciences Center • 104 of these cases were ultimately biopsied • 3 board-certified specialty dermatologists
  7. 7. Exams • Each dermatologist examined approximately 1/3 of the patients in person at the AHSC clinic • Rendered either a single diagnosis (75% of the cases, n = 230) or 2 or 3 differential diagnoses (25% of the cases, n = 78) • Up to 5 photos of the lesion ROIs were taken with a digital camera by 4 medical students trained in the use of the camera • Global and close-up shots
  8. 8. The Digital Camera • Canon PowerShot600 • CCD image sensor • 832 x 608 pixels • 24-bit color resolution • f/2.5 lens • Built-in flash • 150 kB file size
  9. 9. The Display • Gateway 2000 computer • Gateway CrystalScan color monitor: 1024 x 768 • PhotoImpact Album v 3.0 display software • Brief patient history in each case folder • Randomized case presentation
  10. 10. Procedure • Approximately 2 months after in-person exams, digital images were examined • Same 3 dermatologists examined all 308 cases • Single most likely diagnosis rendered • Decision confidence: very definite, definite, probable, possible • Rate image sharpness & color: excellent, good, fair, poor • Viewing time recorded
  11. 11. Analyses • In-person diagnosis = truth • Correct match = digital diagnosis matches one of the differential possibilities listed during in- person • Incorrect mismatch = digital diagnosis does not match any of the in-person differentials • For biopsy analyses, biopsy = truth
  12. 12. Types of Cases Clinical Diagnosis Number of Cases • Malignant or Premalignant 91 • Benign Proliferations 74 • Eczema/Dermatitis 36 • Pigmented Lesions 32 • Infections/Infestations 20 • Papulosquamous Disorders 12 • Urticarial & Allergic 5 • Collagen/Vascular 1
  13. 13. Biopsied Lesions Lesion Type Number Percent • Infection/Infestation 3 3% • Pigmented Lesions 26 25% • Malignant/Premalignant 49 47% • Dermatitis/Eczema 4 4% • Benign Proliferations 12
  14. 14. Diagnostic Accuracy F = 0.011, df = 2, p = 0.989 no differences in accuracy between dermatologists 0 10 20 30 40 50 60 70 80 90 Percent Correct Incorrect 1 2 3 Reader
  15. 15. Decision Confidence 0 10 20 30 40 50 60 Percent Very Definite Definite Probable Possible 1 2 3 Ave Reader
  16. 16. Observer Variation • Intra-Observer Variation – Reader 1: 90% agreement (n = 104 cases) – Reader 2: 85% agreement (n = 102 cases) – Reader 3: 76% agreement (n = 102 cases) • Inter-Observer Variation – Reader 1 vs 2: kappa = 0.82 – Reader 1 vs 3: kappa = 0.81 – Reader 2 vs 3: kappa = 0.80
  17. 17. Correct Decisions Biopsy Cases In-Person Photo vs Photo vs Reader vs Biopsy Biopsy In-Person 1 80% 78% 87% 2 97% 76% 79% 3 90% 73% 85%
  18. 18. Biopsy vs In-Person Mismatches Biopsy In-Person Basal Cell Carcinoma Intradermal Nevus Mycosis Fungoides Psoriasis/Parapsoriasis Basal Cell Carcinoma Bowen's Disease Folliculitis Vasculitis Foreign Body Granuloma Basal Cell Carcinoma Dysplastic Nevus Melanoma Premalignant Keratosis Pyogenic Granuloma Epidermoid Cyst Basal Cell Carcinoma Basal Cell Carcinoma Foreign Body Granuloma/Dermatofibroma Seborrheic Keratosis Squamous Cell Carcinoma/Keratoacanthoma Benign Lichenoid Keratosis Basal Cell Carcinoma
  19. 19. Image Quality 0 10 20 30 40 50 60 70 80 90 Percent Excellent Good Fair Poor 1 2 3 Ave Reader
  20. 20. Correlations • Color & sharpness: r = 0.73 • Color & Decision Confidence: r = 0.48 • Sharpness & Decision Confidence: r = 0.47 • Decision confidence was not affected significantly by overall quality of the images
  21. 21. Viewing Time 0 10 20 30 40 50 60 70 80 90 100 Percent < 30 sec < 60 sec > 90 sec 1 2 3 Ave Reader
  22. 22. Correlations • View time vs color rating: r = 0.35 • View time vs sharpness rating: r = 0.24 • View time vs accuracy: r = 0.21 • View time vs confidence: r = 0.54 • View time vs single/multiple diagnoses: r = 0.15
  23. 23. Conclusions • Digital photography can be used to acquire dermatology images for telediagnosis • Image quality is overall excellent to good • Diagnostic accuracy and confidence are high • Digital image diagnoses compare favorably with in-person diagnoses and with biopsy results

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