Anqin Li^{1}, Zhen Li^{1}, Haojie Li^{1}, and Daoyu Hu^{1}

To evaluate the utility of volumetric
histogram analysis originated from
reduced field-of-view (r-FOV) diffusion-weighted (DW) imaging for small (<
4cm) solid renal mass subtypes at 3-T MR. Differences of ADC histogram parameters among different subtypes of renal tumor were compared. Benign tumors had significantly lower
mean ADC, median ADC,
10^{th}, 25^{th}, 75^{th},
90^{th} percentiles ADC,
SD and entropy values compared to malignant tumors. ADC histogram analysis
of the entire lesion was complementary to the mean ADC measure and may have a certain value to help
differentiate the majority of subtypes of small solid renal tumor.

1. Cornelis F, Tricaud E, Lasserre AS, et al. Routinely performed multiparametric magnetic resonance imaging helps to differentiate common subtypes of renal tumours. Eur Radiol 2014; 24:1068–1080.

2. Zhang YD, Wu CJ, Wang Q, et al. Comparison of Utility of Histogram Apparent Diffusion Coefficient and R2* for Differentiation of Low-Grade From High-Grade Clear Cell Renal Cell Carcinoma. AJR Am J Roentgenol 2015; 205(2):W193-201.

3. Korn N, Kurhanewicz J, Banerjee S, et al. Reduced-FOV excitation decreases susceptibility artifact in diffusion-weighted MRI with endorectal coil for prostate cancer detection. Magn Reson Imaging 2015; 33(1):56-62.

4. Gaing B, Sigmund EE, Huang WC, et al. Subtype differentiation of renal tumors using voxel-based histogram analysis of intravoxel in coherent motion parameters. Invest Radiol 2015; 50(3):144–152.

Figure
1:
Bland–Altman plots of interobserver variability in the measurement of ADC volumetric histogram parameters. The average
difference between two radiologists and
the degree of agreement (×1.96 times SD)
are showed. ADC values are expressed in ×10^{-5}mm^{2}/s.

Figure 2: Box-and-whisker plot analyses of histogram
analysis of ADC parameters between benign renal tumors and malignant renal
tumors. ADC values are expressed in ×10^{-5}mm^{2}/s. Stars
demonstrate statistically significant. Circles indicate outliers.

Figure 3: Receiver operating characteristic curves of using significant
histogram parameters to differentiate benign tumors from malignant tumors.

Figure 4: Images in a 30-year-old
man with clear cell RCC. Axial T1-weighted
(A) and T2-weighted image (B) show a lesion in left renal with heterogeneous signal
intensity. The colored ADC map was obtained after selecting the ROI, and
then embed with the axial r-FOV DW image (C). Corresponding histogram of whole-tumor (D) shows a relatively higher ADC values, standard deviation and entropy. The mean
ADC, median ADC, 10^{th}, 25^{th}, 75^{th}, 90^{th}
percentiles ADC and SD were 191.57, 193.50, 136.00, 166.00, 219.00, 245.50 and 44.25 ×10^{-5}mm^{2}/s, respectively.
Skewness, kurtosis and entropy were -0.33, 0.68 and 5.15, respectively.

Figure 5: Images in a 61-year-old woman with oncocytoma.
Axial T1-weighted (A) and T2-weighted image (B) show a lesion in right renal with relatively homogeneous signal intensity. The colored ADC
map was obtained after selecting the ROI, and then embed with the axial r-FOV
DW image (C). Corresponding histogram of
whole-tumor (D) shows a relatively lower ADC
values, standard deviation and entropy. The mean
ADC, median ADC, 10^{th}, 25^{th}, 75^{th}, 90^{th}
percentiles ADC and SD were 136.64, 137.50,
114.50, 127.50, 148.50, 159.00 and 19.89 ×10^{-5}mm^{2}/s, respectively.
Skewness, kurtosis and entropy were -1.02, 3.80 and 4.26, respectively.