Prostate zones and tumor morphological parameters on magnetic resonance imaging for predicting the tumor-stage diagnosis of prostate cancer

Abstract

Purpose: To determine whether the morphological parameters of prostate zones and tumors on magnetic resonance imaging (MRI) can predict the tumor-stage (T-stage) of prostate cancer (PCa) and establish an optimal T-stage diagnosis protocol based on three-dimensional reconstruction and quantization after image segmentation.

Methods: A dataset of the prostate MRI scans and clinical data of 175 patients who underwent biopsy and had pathologically proven PCa from January 2018 to November 2020 was retrospectively analyzed. The authors manually segmented and measured the volume, major axis, and cross-sectional area of the peripheral zone (PZ), transition zone, central zone (CZ), anterior fibromuscular stroma, and tumor. The differences were evaluated by the One-Way analysis of variance, Pearson's chi-squared test, or independent samples t-test. Spearman's correlation coefficient and receiver operating characteristic curve analyses were also performed. The cut-off values of the T-stage diagnosis were generated using Youden's J index.

Results: The prostate volume (PV), PZ volume (PZV), CZ volume, tumor's major axis (TA), tumor volume (TV), and volume ratio of the TV and PV were significantly different among stages T1 to T4. The cut-off values of the PV, PZV, CZV, TA, TV, and the ratio of TV/PV for the discrimination of the T1 and T2 stages were 53.63 cm³, 11.60 cm³, 1.97 cm³, 2.30 mm, 0.90 cm³, and 0.03 [area under the curves (AUCs): 0.628, 0.658, 0.610, 0.689, 0.724, and 0.764], respectively. The cut-off values of the TA, TV, and the ratio of TV/PV for the discrimination of the T2 and T3 stages were 2.80 mm, 8.29 cm³, and 0.12 (AUCs: 0.769, 0.702, and 0.688), respectively. The cut-off values of the TA, TV, and the ratio of TV/PV for the discrimination of the T3 and T4 stages were 4.17 mm, 18.71 cm³, and 0.22 (AUCs: 0.674, 0.709, and 0.729), respectively.

Conclusion: The morphological parameters of the prostate zones and tumors on the MRIs are simple and valuable diagnostic factors for predicting the T-stage of patients with PCa, which can help make accurate diagnoses and lateral treatment decisions.

Keywords: Magnetic resonance imaging; neoplasm-stage; prostate neoplasms; prostate zones; tumor volume.

Figure 1

Flowchart of patient inclusion and exclusion. PCa, prostate cancer; T2WI, T2-weighted imaging; MRI, magnetic resonance imaging.

Figure 2

Tumor segmentation (dashed box) on different magnetic resonance imaging sequences, including T2WI (a), DWI (b = 1000 s/mm2) (b), and ADC map (c) (Software: Syngo Quick Brower). fT2WI, fat-suppressed T2 weighted imaging; DWI, diffusion-weighted imaging; ADC, apparent diffusion coefficient.

Figure 3

Three-dimensional reconstruction, spatial relationship, and location of prostate cancer lesions in different T-stages. Column A1–D1, three-dimensional reconstruction of the prostate and adjacent structures in the left view. Column A2–D2, A3–D3, and A4–D4, three-dimensional reconstruction of the tumor and prostate in the left, front, and upper views, in which the prostate, seminal vesicles, and bladder are semi-transparent. Column A5–D5, tumor segmentation in axial magnetic resonance images. Row A1–A5, T1 PCa; row B1–B5: T2 PCa; row C1–C5, T3 PCa; row D1–D5, T4 PCa. PCa, prostate cancer; PZ, peripheral zone; TZ, transition zone; CZ, central zone; AFMS, anterior fibromuscular stroma; B, bladder; SV, seminal vesicles; R, rectum; U, urethral canal; P, prostate; T-stages, tumor-stages.

Figure 4

Anatomic morphology, three-dimensional shape, and spatial relationship of prostatic zones in different tumor stages. Column A1–D1, three-dimensional reconstruction of the prostate and adjacent structures in the left view. Column A2–D2, A3–D3, and A4–D4, three-dimensional reconstruction of the PZ, TZ, CZ, and AFMS in the left, upper, and front view, in which the PZ and TZ are semi-transparent. Column A5–D5, PZ, TZ, CZ, and AFMS segmentation in axial magnetic resonance imaging. Row A1–A5, T1 PCa; row B1–B5, T2 PCa; row C1–C5, T3 PCa; row D1–D5, T4 PCa. PCa, prostate cancer; PZ, peripheral zone; TZ, transition zone; CZ, central zone; AFMS, anterior fibromuscular stroma; B, bladder; SV, seminal vesicle; R, rectum; U, urethral canal; P, prostate.

Figure 5

Receiver operating characteristic curves of the morphological parameters of the tumors for discrimination of T1 and T2 (a), T2 and T3 (b), and T3 and T4 (c). TA, tumor’s major axis; TV, tumor volume; TV/PV, the volume ratio of TV and PV; ROC, receiver operating characteristic; AUC, area under the curve.