Tumor contour irregularity on preoperative imaging: a practical and useful prognostic parameter for papillary renal cell carcinoma.

OBJECTIVES: To illustrate tumor contour irregularity on preoperative imaging with a practical method and further determine its value in predicting disease-free survival (DFS) in patients with pRCC (papillary renal cell carcinoma). METHODS: We performed a retrospective single-institution review of 267 Chinese pRCC patients between March 2009 and May 2019. Contour irregularity on cross-section was classified into smooth but distorted margin, unsmooth and sharply nodular margin, and blurred margin. Then, the ratio of the cross-section numbers of irregularity and the total tumor was defined as the contour irregular degree (CID). Cox regression and Kaplan-Meier analysis were performed to analyze the impact of CID on DFS. Then, the prognostic performance of CID was compared with pRCC risk stratification published by Leibovich et al. RESULTS: The median follow-up was 45 months (IQR: 23-69), in which 27 (10%) patients had metastasis or recurrence. Observed DFS rates were 95%, 90%, and 88% at 1, 3, and 5 years. The CID was an independent prognostic factor of DFS (HR = 1.048, 95% CI = 1.029-1.068, p < 0.001). The Kaplan-Meier plot showed that high-risk patients (CID ≥ 50%) tended to have a significantly shorter DFS (p < 0.001). The CID and Leibovich's pRCC model for DFS prediction had a C-index of 0.934 (95% CI = 0.907-0.961) and 0.833 (95% CI = 0.739-0.927) respectively. CONCLUSIONS: With our standard and practical method, the CID can be a reliable imaging marker for DFS prediction in patients with pRCC. KEY POINTS: • The updated contour irregularity was an independent parameter for predicting disease-free survival in patients with pRCC. • High-risk pRCC patients (contour irregular degree ≥ 50%) tended to have a shorter disease-free survival. • Tumor contour irregularity in pRCC risk stratification outperformed Leibovich's model from our cohort.

Differentiating between malignant and benign renal tumors: do IVIM and diffusion kurtosis imaging perform better than DWI?

OBJECTIVE: To quantitatively compare the diagnostic values of conventional diffusion-weighted imaging (DWI), intravoxel incoherent motion (IVIM), and diffusion kurtosis imaging (DKI) in differentiating between malignant and benign renal tumors. METHODS: Multiple b value DWIs and DKIs were performed in 180 patients with renal tumors, which were divided into clear cell renal cell carcinoma (ccRCC), non-ccRCC, and benign renal tumor group. The apparent diffusion coefficient (ADC), true diffusivity (D), pseudo-diffusion coefficient (D*), perfusion fraction (f), mean kurtosis (MK), and mean diffusivity (MD) maps were calculated. The diagnostic efficacy of various diffusion parameters for predicting malignant renal tumors was compared. RESULTS: The ADC, D, and MD values of ccRCCs were higher, while D*, f, and MK values were lower than those of benign renal tumors (all p < 0.025). The D* and f values of non-ccRCCs were lower than those of benign renal tumors (p = 0.002 and p < 0.001, respectively). The difference of ADC, D, MD, and MK values between non-ccRCCs and benign renal tumors was not statistically significant (p > 0.05). The ADC, D, MD, and f values of ccRCCs were higher, while MK values were lower than those of non-ccRCCs (all p < 0.001). The AUC values of ADC, D, D*, f, MK, and MD were 0.849, 0.891, 0.708, 0.656, 0.862, and 0.838 for differentiating ccRCCs from benign renal tumors, respectively. The AUC values of D* and f were 0.772 and 0.866 for discrimination between non-ccRCCs and benign renal tumors, respectively. CONCLUSION: IVIM parameters are the best, while DWI and DKI parameters have similar performance in differentiating malignant and benign renal tumors. KEY POINTS: • The D value is the best parameter for differentiating ccRCC from benign renal tumors. • The f value is the best parameter for differentiating non-ccRCC from benign renal tumors. • Conventional DWI and DKI have similar performance in differentiating malignant and benign renal tumors.

Prediction of muscle invasion of bladder cancer: A comparison between DKI and conventional DWI.

OBJECTIVES: To prospectively compare the diagnostic efficacy of conventional diffusion-weighted imaging (DWI) and diffusion kurtosis imaging (DKI) in differentiating between muscle-invasive bladder cancer (MIBC) and non-muscle-invasive bladder cancer (NMIBC). METHODS: Multiple b value DWIs were performed using a 3-T magnetic resonance (MR) imaging unit in fifty-one patients with bladder cancer including MIBC and NMIBC confirmed by histopathological findings. DWI data were postprocessed using mono-exponential and DKI models to calculate the apparent diffusion coefficient (ADC), apparent diffusional kurtosis (Kapp), and kurtosis-corrected diffusion coefficient (Dapp). Receiver-operating characteristic (ROC) analysis was performed to compare the diagnostic efficacy of all diffusion parameters. RESULTS: All parameters differed significantly between MIBC and NIMBC including increased Kapp, decreased Dapp and ADC (all p < 0.001). Only the combination of Dapp and Kapp was significantly higher than ADC (p < 0.05), whilst Dapp and Kapp were not statistically different from ADC. CONCLUSIONS: Both conventional DWI and DKI models are beneficial in differentiating between MIBC and NMIBC, whilst the combination of Dapp and Kapp can produce a more robust value than conventional ADC value in evaluating aggressiveness of bladder cancer.

No Detection of Pseudocapsule of Tumor-Parenchyma Interface on Multidetector Computed Tomography (MDCT) Images: Clinical Significance and Histological Reflections in Renal Cell Carcinoma.

OBJECTIVE: Pseudocapsule (PS) of tumor-parenchyma interface (TPI) can be detected by MDCT (ctPS) in renal cell carcinoma (RCC) with exceptions. We aim to study the prognostic implications and histological reflections of no detection of ctPS in RCC. PATIENTS AND METHODS: A total of 210 RCC patients who had MDCT examination and received nephrectomy in our institution were included in the analysis. Absence or presence of ctPS was recognized, and its associations with overall survival (OS) and progression-free survival (PFS), pathological PS (pPS) and vasculature were studied. RESULTS: A total of 172 (81.9%) patients were recognized to have a ctPS and 38 (18.1%) had no detection of it. They had comparable histology, stage, grade, and necrosis. Patients without a ctPS had significantly shortened overall survival (OS, p = 0.001) and progression-free survival (PFS, p <0.001), the significance of which persisted in multivariable analysis (OS, HR 3.104, p = 0.003; PFS, HR 3.313, p = 0.001). Nearly all tumors (34/38, 89.4%) without a ctPS actually had a pPS being detected and incompleteness of pPS was also irrelevant (p = 0.739). Compared with ctPS presence, those without a ctPS had significantly thinned pPS (0.36 vs 0.43 mm, p = 0.005). In clear-cell histology, those without a ctPS also contained increased vascular density and cross-sectional area of vessels with long diameter ≥200 um in the pPS layer (p = 0.005 and 0.011) and increased vascular density in the 500 um layer outside pPS (p = 0.017). CONCLUSION: Absence of ctPS on MDCT significantly increases the risk of adverse clinical outcome in RCC. It is the reflection of a thinner pPS and enriched vasculature of TPI rather than absence of pPS itself.