Date Published: October 29, 2019
Publisher: Springer US
Author(s): Yajuan Li, Xialing Huang, Yuwei Xia, Liling Long.
To explore the value of CT-enhanced quantitative features combined with machine learning for differential diagnosis of renal chromophobe cell carcinoma (chRCC) and renal oncocytoma (RO).
Sixty-one cases of renal tumors (chRCC = 44; RO = 17) that were pathologically confirmed at our hospital between 2008 and 2018 were retrospectively analyzed. All patients had undergone preoperative enhanced CT scans including the corticomedullary (CMP), nephrographic (NP), and excretory phases (EP) of contrast enhancement. Volumes of interest (VOIs), including lesions on the images, were manually delineated using the RadCloud platform. A LASSO regression algorithm was used to screen the image features extracted from all VOIs. Five machine learning classifications were trained to distinguish chRCC from RO by using a fivefold cross-validation strategy. The performance of the classifier was mainly evaluated by areas under the receiver operating characteristic (ROC) curve and accuracy.
In total, 1029 features were extracted from CMP, NP, and EP. The LASSO regression algorithm was used to screen out the four, four, and six best features, respectively, and eight features were selected when CMP and NP were combined. All five classifiers had good diagnostic performance, with area under the curve (AUC) values greater than 0.850, and support vector machine (SVM) classifier showed a diagnostic accuracy of 0.945 (AUC 0.964 ± 0.054; sensitivity 0.999; specificity 0.800), showing the best performance.
Accurate preoperative differential diagnosis of chRCC and RO can be facilitated by a combination of CT-enhanced quantitative features and machine learning.
The incidence of renal cell carcinoma is increasing worldwide . Chromophobe cell carcinoma (chRCC) of the kidney is second only to clear cell carcinoma of the kidney and papillary cell carcinoma of the kidney [1–3]. Renal oncocytoma (RO) is a benign renal tumor, accounting for about 3–7% of all renal tumors [4, 5]. Medical imaging plays an important role in the clinical management of renal tumors, such as detection of renal tumors, prediction of benign and malignant tumors, grading, and surgical treatment [6, 7]. Studies have shown that chRCC and RO not only overlap in morphological and immunological manifestations, but also have similar imaging manifestations [8, 9]. Although some researchers believe that a central scar is the characteristic of RO, its proportion is only about 33% [4, 6], but there are also a few cases of chRCC with a central scar . Therefore, it is obviously impossible to distinguish the two pathological types by the presence or absence of a central scar. Some reports suggest that there are some differences in the enhancement degree of CT between the two . The enhancement in chRCC is slightly higher than that in RO, but the difference in the CT value is small and is greatly influenced by subjective factors. There are also studies showing that many MR findings for chRCC and RO are quite similar, such as a central scar, segmental enhancement inversion, and enhancement characteristics of each phase, none of which can accurately identify the two .
In 2004, the World Health Organization formally classified chRCC as a new pathological classification of renal tumors. The incidence of chRCC is second only to that of renal clear cell and renal papillary cell carcinomas ; moreover, it has potential for metastasis. RO is a benign tumor with good prognosis . Presently, surgical treatment, including partial and radical nephrectomy, is an effective method for treating local renal tumors. Radical nephrectomy can lead to an increased risk of chronic kidney disease, and is associated with an increased risk of cardiovascular disease morbidity and mortality. Compared to radical nephrectomy, a partial nephrectomy can preserve partial renal function, reduce overall mortality, and reduce the incidence of cardiovascular disease . Therefore, radical nephrectomy should be avoided when nephron retention is achievable. Percutaneous renal biopsy is the most commonly used preoperative examination method, and it has 97% accuracy rate for distinguishing malignant renal masses . However, the diagnosis of chRCC and RO on percutaneous renal biopsy presents difficulties .