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AJR Am J Roentgenol. 2018 Jan;210(1):113-117. doi: 10.2214/AJR.17.18495. Epub 2017 Oct 18.

Apparent Diffusion Coefficient Values of Prostate Cancer: Comparison of 2D and 3D ROIs.

Author information

1
1 Department of Radiology, NYU Langone Medical Center, 550 First Ave, New York, NY 10016.
2
2 Department of Radiology, Kawasaki Medical School, Okayama, Japan.
3
3 Department of Urology, Division of Urologic Oncology, NYU Langone Medical Center, New York, NY.

Abstract

OBJECTIVE:

The purpose of this study was to compare the reproducibility and diagnostic performance of 2D and 3D ROIs for prostate apparent diffusion coefficient (ADC) measurements.

MATERIALS AND METHODS:

The study included 56 patients with prostate cancer undergoing 3-T MRI including DWI (b = 50 and 1000 s/mm2) before radical prostatectomy. Histologic findings from prostatectomy specimens were reviewed to denote each patient's dominant tumor and a benign region with visually decreased ADC. Three readers independently measured the ADCs of both areas using an ROI placed on a single slice through the lesion (2D) and an ROI encompassing all slices through the lesion (3D). Readers repeated measurements after 3 weeks. Assessment included Bland-Altman analysis (coefficient of repeatability [CR] in which lower values indicated higher reliability) and ROC analysis.

RESULTS:

For intrareader variability, the CRs across readers for all ROIs were 9.9% for 2D and 9.3% for 3D. For tumor ROIs the CRs were 10.6% for 2D and 9.6% for 3D. For interreader variability, the CRs across readers for all ROIs were 17.1% for 2D and 20.5% for 3D and for tumor ROIs were 17.9% for 2D and 22.2% for 3D. For combined reader data, the AUCs for benign and malignant findings were 0.77 for 2D and 0.78 for 3D (p = 0.146). For differentiating Gleason score (GS) 3 + 3 from GS > 3 + 3 tumors, the AUCs were 0.92 for 2D and 0.92 for 3D ROIs (p = 0.649). For differentiating GS ≤ 3 + 4 from GS ≥ 4 + 3 tumors, the AUCs were 0.70 for 2D and 0.67 for 3D ROIs (p = 0.004).

CONCLUSION:

Use of a 3D ROI did not improve intrareader or interreader reproducibility or diagnostic performance compared with use of a 2D ROI for prostate ADC measurements. Interreader reproducibility of 2D ROIs was suboptimal nonetheless.

KEYWORDS:

DWI; MRI; apparent diffusion coefficient; prostate cancer; reproducibility

PMID:
29045185
DOI:
10.2214/AJR.17.18495
[Indexed for MEDLINE]

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