Impact of measurement method on interobserver variability of apparent diffusion coefficient of lesions in prostate MRI

Hiroaki Takahashi, Kotaro Yoshida, Akira Kawashima, Nam Ju Lee, Adam T. Froemming, Daniel A. Adamo, Ashish Khandelwal, Candice W. Bolan, Matthew T. Heller, Robert P. Hartman, Bohyun Kim, Kenneth A. Philbrick, Rickey E. Carter, Lance A. Mynderse, Mitchell R. Humphreys, Jason C. Cai, Naoki Takahashi

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Purpose To compare the inter-observer variability of apparent diffusion coefficient (ADC) values of prostate lesions measured by 2D-region of interest (ROI) with and without specific measurement instruction. Methods Forty lesions in 40 patients who underwent prostate MR followed by targeted prostate biopsy were evaluated. A multi-reader study (10 readers) was performed to assess the agreement of ADC values between 2D-ROI without specific instruction and 2D-ROI with specific instruction to place a 9-pixel size 2D-ROI covering the lowest ADC area. The computer script generated multiple overlapping 9-pixel 2D-ROIs within a 3D-ROI encompassing the entire lesion placed by a single reader. The lowest mean ADC values from each 2D-small-ROI were used as reference values. Inter-observer agreement was assessed using the Bland-Altman plot. Intraclass correlation coefficient (ICC) was assessed between ADC values measured by 10 readers and the computer-calculated reference values. Results Ten lesions were benign, 6 were Gleason score 6 prostate carcinoma (PCa), and 24 were clinically significant PCa. The mean±SD ADC reference value by 9-pixel-ROI was 733 ± 186 (10−6 mm2/s). The 95% limits of agreement of ADC values among readers were better with specific instruction (±112) than those without (±205). ICC between reader-measured ADC values and computer-calculated reference values ranged from 0.736–0.949 with specific instruction and 0.349–0.919 without specific instruction. Conclusion Interobserver agreement of ADC values can be improved by indicating a measurement method (use of a specific ROI size covering the lowest ADC area).

Original languageEnglish (US)
Article numbere0268829
JournalPloS one
Issue number5 May
StatePublished - May 2022

ASJC Scopus subject areas

  • General


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