What is included in the imaging evaluation of renal cell carcinoma (RCC)?

Updated: Dec 13, 2018
  • Author: Deborah A Baumgarten, MD, MPH; Chief Editor: Eugene C Lin, MD  more...
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Answer

Although a variety of examinations (ultrasound [US], magnetic resonance imaging [MRI], angiography) can be used in the workup of patients with suspected RCC, the preferred method of imaging is dedicated renal computed tomography (CT). In most cases, this single examination can be used to detect and stage RCC and to provide information for surgical planning without additional imaging. [1, 2, 3]

High resolution, reproducibility, reasonable preparation and acquisition time, and acceptable cost allow CT to remain as the primary choice for radiologic imaging. MRI is an important alternative in patients requiring further imaging and in cases of allergies, pregnancy, or surveillance. Because of concern over radiation exposure, there has been a trend toward more use of MRI. [9, 10]

A systematic review, by Vogel et al, of 40 studies with a combined 4354 patients compared CT, MRI, positron emission tomography (PET) CT, and ultrasonography for diagnosing and staging RCC in adults. For CT, median sensitivity and specificity were 88% and 75%, respectively; MRI, 87.5% and 89%. Staging sensitivity and specificity for CT were 87% and 74.5%, while MRI showed a median sensitivity of 90% and specificity of 75%. Contrast-enhanced US had a median diagnostic sensitivity of 93% and mediocre specificity, and the diagnostic performance of unenhanced US was poor. [11]

Oliva et al compared the characteristics on MRI of papillary renal cell tumors and clear cell tumors and noted that they had a similar appearance and signal intensity ratio on T1-weighted images, but on T2-weighted images, most papillary tumors were hypointense and most clear cell tumors were hyperintense. A tumor T2 signal intensity ratio of 0.66 or less had a specificity of 100% and a sensitivity of 54% for papillary tumors. [12]

A meta-analysis, by Chiarello et al, of 13 studies involving 275 papillary RCC lesions and 758 other renal masses that used MRI to differentiate papillary RCC from other renal lesions found moderate sensitivity and excellent specificity of quantitative enhancement in the corticomedullary phase (sensitivity of 79.6% and specificity of 88.1%). [10]

Taouli et al compared diffusion-weighted MRI with contrast-enhanced MRI to compare the ability to diagnose renal lesions. They found that although diffusion-weighted images can be used to characterize renal lesions (eg, differentiate solid tumors from oncocytomas and characterize histologic subtype), such images are less accurate than contrast-enhanced images. The area under the curve (AUC), sensitivity, and specificity of diffusion-weighted imaging were 0.856, 86%, and 80%, respectively, whereas the AUC, sensitivity, and specificity of contrast-enhanced MR imaging were 0.944, 100%, and 89%, respectively. [13] MRI findings correlate well with aggressive histology in the progression of RCC. [14]

In the few patients in whom the CT findings are equivocal, MRI or US can be useful. Recent literature suggests a use for contrast-enhanced Doppler US for lesions that show equivocal enhancement at CT. Angiography is rarely used in the workup of suggested RCC, but it can provide information about the origin of the tumor in troublesome cases. At present, no accepted protocol has been developed for RCC screening among asymptomatic individuals in the general population. Patients with a hereditary predisposition for RCC should be periodically examined by using dedicated renal CT.

(See the renal cell carcinoma images below.)

Case 2. Large renal cell carcinoma. Delayed tomogr Case 2. Large renal cell carcinoma. Delayed tomogram.
Case 2. Large renal cell carcinoma. Sonogram. Case 2. Large renal cell carcinoma. Sonogram.
Case 2. Large renal cell carcinoma. Contrast-enhan Case 2. Large renal cell carcinoma. Contrast-enhanced CT scan.
Case 3. Small left renal cell carcinoma is subtle Case 3. Small left renal cell carcinoma is subtle on this intravenous urographic image.
Case 3. Small renal cell carcinoma. Tomogram. Case 3. Small renal cell carcinoma. Tomogram.
Case 3. Small renal cell carcinoma. Contrast-enhan Case 3. Small renal cell carcinoma. Contrast-enhanced CT scan.

According to Guzzo et al, multidetector CT with 3-dimensional mapping is effective in accurately characterizing the level of venous thrombus in patients with renal cell carcinoma. When excluding patients with segmental venous involvement only, the concordance rate between multidetector CT and pathologic findings was 84%, and multidetector CT predicted the level of tumor thrombus in 26 of 27 patients (96%). The investigators noted that in patients with renal cell carcinoma in whom multidetector CT fails to detect tumor thrombus, it is unlikely that a tumor thrombus will be found at surgery that would change the surgical approach. [1]

After studying 298 cases of RCC and oncocytoma using preoperative multiphasic multidetector CT, Young et al concluded that this approach can assist in discriminating clear cell RCC from other forms of RCC. [15]

Studies have been done on the use of radiogenomics to aid in prognosis and management. In a  study of imaging features and mutational status in patients with clear cell renal cell carcinoma, 103 patients were examined with CT (81 patients), MRI (19), and both CT and MRI (3). Images were downloaded from The Cancer Imaging Archive. VHL (N = 52) and PBRM1 (N = 24) were the most common mutations. BAP1 mutation was associated with ill-defined tumor margins and presence of calcification, and MUC4 mutation was associated with exophytic growth. [16]

Dual-energy CT (DECT) can be used to measure iodine and calcium concentrations and increase the iodine signal to help differentiate pathologic processes and clarify the internal structure of mass lesions. DECT can also potentially reduce the radiation dose by applying virtual noncontrast images, eliminating the need for precontrast CT. [17]


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