Repeatability of diffusion-weighted MRI of the prostate using whole lesion ADC values, skew and histogram analysis

Abstract

To investigate the repeatability of diffusion-weighted imaging parameter including ADC-derived histogram values in prostate cancer. Methods: 10 patients with prostate cancer were prospectively recruited to a retest cohort. 3 T diffusion-weighted MRI of the prostate was acquired consecutively with patient getting off the scanner between studies. Prostatectomy-histopathology defined tumour regions-of-interest were outlined on ADC maps and diffusionweighted metrics including histograms were calculated. The coefficient of reproducibility (CoR) and Bland-Altman plots were used to assess repeatability. Results: 10 th centile, 90 th centile, and median ADC showed good repeatability with mean difference ranging from-0.005 to-0.025 × 10 3 mm 2 s-1 , and CoR ranging from 0.271-0.294 × 10 3 mm 2 s-1 of scan 1 mean). Two measures of heterogeneity and simplified texture, IQR and mean local range, had only moderate repeatability. IQR had a mean difference of-0.032 × 10 3 mm 2 s-1 between scans with CoR 0.181 × 10 3 mm 2 s-1 (56% of scan 1 mean). Mean local range had a mean difference-0.008 × 10 3 mm 2 s-1 between scans (37% of scan 1 mean). Bland-Altman plots showed good repeatability for test and re-test analysis for median, percentile and mean range values. All ADC values had good reliability regardless of whether the tumour border was included in quantitative analysis. ADC histogram skew had poor repeatability, CoR 0.78 × 10 3 mm 2 s-1 (373% of scan 1 mean). Conclusion: 10 th and 90 th centile ADC demonstrated sufficient repeatability for clinical use. However, more advanced measures of heterogeneity such as histogram skew, IQR, or mean local range may be limited by their repeatability.

Diffusion kurtosis MRI as a predictive biomarker of response to neoadjuvant chemotherapy in high grade serous ovarian cancer

“…In this study the patient number was too small to permit reliable hypothesis testing of the multiple parameters that would be produced by histogram or textural analysis. Future work with a larger number of patients could however extend this study to assess intervoxel heterogeneity of water movement by using histogram analysis 35,36 or Haralick textural features 37 .…”

Molecular imaging of the prostate: Comparing total sodium concentration quantification in prostate cancer and normal tissue using dedicated 13C and 23Na endorectal coils

“…The coefficient of variation between the coils was only 12%, which is comparable to the repeatability and reproducibility error of around 10% reported for ADC measurements of restricted diffusion, used routinely in clinical MRI assessment of the prostate. [32][33][34] There was one notable outlier (Patient 6) with a PZ tumor with a TSC value of 38.5 mM measured with the 23 Na coil, compared with 58.9 mM with the 13 C coil; this tumor was a small (volume 0.79 cm 3 ), peripherally located tumor and the discrepancy in the findings may have related to partial voluming effects.…”

“…The total number of patients assessed was relatively small. 32,33 TSC estimates will be affected by the SNR, which in turn is affected by the coil resonant frequency, and is accounted for in the quantitative measurements. Furthermore, the gyromagnetic ratio of the sample is not affected by the frequency of the coil, and so is not expected to directly affect the TSC estimates.…”

Bi-exponential versus mono-exponential diffusion-weighted imaging for evaluating prostate cancer aggressiveness after radical prostatectomy: a whole-tumor histogram analysis

“…A recent study by Tristan Barrett et al. found that advanced measures of heterogeneity such as histogram skewness had poor repeatability (32). Their results may explain the limited diagnostic performance of skewness and kurtosis values in our study.…”