Morphometric scores for renal tumors: what does the radiologist need to know?

New Preoperative Nomogram Using the Centrality Index to Predict High Nuclear Grade Clear Cell Renal Carcinoma

Objective

Nuclear grading is an independent prognosis factor of clear-cell renal cell carcinoma (ccRCC). A non-invasive preoperative predictive WHO/International Society of Urologic Pathology (WHO/ISUP) grading of ccRCC model is needed for clinical use. The anatomical complexity scoring system can span a variety of image modalities. The Centrality index (CI) is a quantitatively anatomical score commonly used for renal tumors. The purpose of this study was to develop a simple model to predict WHO/ISUP grading based on CI.

Materials and methods

The data in this study were from 248 ccRCC patients from five hospitals. We developed three predictive models using training data from 167 patients: a CI-only model, a valuable clinical parameter model and a fusion model of CI with valuable clinical parameters. We compared and evaluated the three models by discrimination, clinical usefulness and calibration, then tested them in a set of validation data from 81 patients.

Results

The fusion model consisting of CI and tumor size (valuable clinical parameter) had an area under the curve (AUC) of 0.82. In the validation set, the AUC was 0.85. The decision curve showed that the model had a good net benefit between the threshold probabilities of 5–80%. And the calibration curve showed good calibration in the training set and validation set.

Conclusion

This study confirms that CI is associated with the WHO/ISUP grade of ccRCC, and the possibility that a bivariate model incorporating tumor size may help urologist’s evaluation patients’ prognostic.

Renal Cell Carcinoma: Accuracy of Multidetector Computed Tomography in the Assessment of Renal Sinus Fat Invasion

PURPOSE

The purpose of this study was to evaluate the accuracy of multidetector computed tomography (MDCT) in the preoperative assessment of renal sinus fat invasion (RSFI) in patients with renal cell carcinoma (RCC) and to assess imaging features that improve detection of RSFI on CT.

METHODS

This is a single-institution retrospective review of 53 consecutive patients with histologically proven RCC who underwent triple-phase preoperative contrast MDCT prior to partial or radical nephrectomy. Two experienced radiologists (R1 and R2), blinded to the final histology result, independently reviewed the preoperative MDCT studies to assess for RSFI. Histopathology was used as the gold standard for the presence of RSFI.

RESULTS

Of 55 surgically resected RCCs that were evaluated with contrast-enhanced MDCT, 34.5% (19/55) of RCCs had RSFI on final histopathology. Multidetector CT demonstrated high sensitivity (R1, 100%; R2, 93.7%) for the detection of RSFI, but a low positive predictive value (R1, 40%; R2, 53%) and specificity (R1, 38.4%; R2, 66.6%). Interreader agreement for RSFI was moderate (κ = 0.56). Renal tumors were significantly larger in cases with RSFI (6.3 ± 3.219 cm) than tumors without RSFI (4.1 ± 2.9 cm) (P = 0.0275). Renal sinus fat invasion was more commonly associated to an irregular tumor margin at the tumor renal sinus fat interface (P < 0.001).

CONCLUSIONS

Multidetector computed tomography demonstrates a high sensitivity but low positive predictive value in diagnosing RSFI with implications for prognosis and treatment planning. Tumor size, location, irregular tumor margin at the tumor/renal sinus interface, and invasion into pelvicaliceal structures can aid in the diagnosis of RSFI on preoperative MDCT.