An In-vivo Prospective Study of the Diagnostic Yield and Accuracy of Optical Biopsy Compared with Conventional Renal Mass Biopsy for the Diagnosis of Renal Cell Carcinoma: The Interim Analysis.

BACKGROUND

Lack of accuracy in preoperative imaging leads to overtreatment of benign renal masses (RMs) or indolent renal cell carcinomas (RCCs). Optical coherence tomography (OCT) is real time and high resolution, enabling quantitative analysis through attenuation coefficient (μ, mm).

OBJECTIVE

To determine the accuracy and diagnostic yield of OCT and renal mass biopsy (RMB) for the differentiation of benign RMs versus RCC and oncocytoma versus RCC.

DESIGN, SETTING, AND PARTICIPANTS: From October 2013 to June 2016, 95 patients with solid enhancing RMs on cross-sectional imaging were prospectively included. All patients underwent subsequent excision or ablation.

INTERVENTION

Percutaneous, image-guided, needle-based OCT followed by RMB in an outpatient setting under local anaesthesia.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Accuracy and diagnostic yield, μ correlated to resection pathology or second biopsy during ablation. Tables (2×2) for RMB, receiver operating characteristic curve for OCT. Mann-Whitney test to differentiate μ of RMs.

RESULTS AND LIMITATIONS

RMB diagnostic yield was 79% with sensitivity, specificity, positive predictive value, and negative predictive value (NPV) of 100%, 89%, 99%, and 100%, respectively. Diagnostic yield and added value of OCT to differentiate RCC from benign was 99% and 15%, respectively. Significant difference was observed in median μ between benign RMs (3.2mm, interquartile range [IQR]: 2.65-4.35) and RCCs (4.3mm, IQR: 3.70-5.00), p=0.0171, and oncocytomas (3.38mm, IQR: 2.68-3.95) and RCCs (4.3mm, IQR: 3.70-5.00), p=0.0031. OCT showed sensitivity, specificity, positive predictive value. and NPV of 91%, 56%, 91%, and 56%, respectively, to differentiate benign RMs from RCCs and 92%, 67%, 95%, and 55%, respectively, to differentiate oncocytoma from RCC. Limitations include two reference standards and heterogeneity benign RMs.

CONCLUSIONS

Compared with RMB, OCT has a higher diagnostic yield. OCT accurately distinguishes benign RMs from RCCs, and oncocytoma from RCCs, although specificity and NPV are lower.

PATIENT SUMMARY

Optical coherence tomography, a new optical scan, exhibits similar sensitivity and positive predictive value than renal mass biopsy, although lower specificity and negative predictive value. Optical coherence tomography has a higher diagnostic yield for diagnosing renal cell carcinoma.