The accuracy of multidetector Computed Tomography for preoperative staging of renal cell carcinoma

Outcomes and predictors of clinical T1 renal mass (cT1) upstaged to pathological T3a (pT3a) after partial nephrectomy: A single-center experience

OBJECTIVES

Clinical T1 (cT1) renal mass treated surgically has a good prognosis, but there is an upstaging risk that potentially threatens oncological outcomes after partial nephrectomy (PN). We aim to analyze and study the incidence, predictors, perioperative morbidity, and oncological outcomes of pT3a upstaging.

METHODOLOGY

A retrospective study of 313 patients who underwent PN for cT1 renal mass at a single center from a single tertiary referral center between 2000 and 2021 was done. Demographic, perioperative, pathological, and outcome variables were reviewed. We compared these parameters between upstaged and non-upstaged groups. Multivariate logistic regression analysis was used to study preoperative variables associated with upstaging.

RESULTS

Nineteen patients were upstaged to pT3a. Making an incidence of 6.1%. Upstaged tumors were bigger (5.02 cm vs. 4.08 cm, p = 0.004), had higher clinical stage T1b (84.2 vs. 40.5%, p < 0.001), had more tumors which were central location (21 vs. 3.4%, p < 0.001), had more endophytic and mesophytic tumors (15.8 vs. 5.8% and 52.6 vs. 9.5%, p < 0.001), and had higher R.E.N.A.L Nephrometry score (8.05 vs. 6, p < 0.001). Upstaged tumors had more operative times (227 vs. 203 min, p = 0.01), more postoperative complications (68.4 vs. 13.1%, p < 0.001), more major complications of Clavien Dindo Grade 3 and above (15.8 vs. 4.4%, p < 0.001). Age (OR 1.035, p = 0.034), Radiological tumor dimension (OR 1.578, p = 0.003), Radiological or Clinical stage (T1b) (9.19, p = 0.008), Higher Nephrometry score (Intermediate and High) (OR 6.184, p = 0.004) were preoperative predictors of upstaging. Oncological outcomes were comparable.

CONCLUSION

Tumor upstaging was uncommon with more perioperative morbidity. Higher age, larger tumor size, higher tumor stage, and higher nephrometry scores were preoperative predictors of upstaging.

Renal cell carcinoma T staging: Diagnostic accuracy of preoperative contrast-enhanced computed tomography

Renal cell carcinoma (RCC) accounts for 1-2% of all malignancies and is the most common renal tumor in adults. Imaging studies are used for diagnosis and staging. Tumor-Node-Metastasis staging strongly affects prognosis and management, while contrast-enhanced computed tomography (CECT) is regarded as a standard imaging technique for local and distant staging. The present study aimed to evaluate the accuracy of CECT for the preoperative staging of RCC by using surgical and pathological staging as the reference methods. This single-center prospective study was conducted between October 2019 and November 2021. The preoperative abdominal CT scans of patients suspected of having RCC were reviewed. Imaging data were collected, including tumor side and size, and perinephric fat invasion. Intraoperative notes were recorded, including the operation type, perinephric fat invasion, renal vein (RV) or inferior vena cava (IVC) tumor extension, and surrounding organ invasion. pathological data were collected on tumor size, RCC type, presence of clear margins, presence of renal capsule or perinephric fat invasion, renal sinus or pelvicalyceal system (PCS) invasion, segmental or main RV extension, and the involvement of Gerota's fascia and nearby organs. Preoperative CECT revealed that 42 out of 59 tumors had a greater maximum diameter than the pathological specimen, with an overall disparity of 0.25 cm. The specificity of CT for the detection of tumor invasion of the perinephric and renal sinus fat and PCS was 95%, and the sensitivity ranged from 80 to 88%. CT had an 83% sensitivity and a 95 specificity in detecting T4 stage cancer, with a 100% specificity for adrenal invasion. The concordance between radiographic and histological results for RV and IVC involvement was high, with specificities of 94 and 98%, and sensitivities of 80 and 100%, respectively. Overall accuracy for correct T staging was 80%. In conclusion, CECT is accurate in the local T staging of RCC, with high sensitivity and specificity for estimating tumor size and detecting extension to nearby structures and venous invasion.

Diagnostic performance and prognostic value of preoperative 18F-FDG PET/CT in renal cell carcinoma patients with venous tumor thrombus

Background

To observe the diagnostic efficacy of preoperative fluorine-18 fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) upon venous tumor thrombus (VTT) in patients with renal cell carcinoma (RCC), and investigate the prognostic value of imaging parameters integrated with clinicopathological characteristics in patients with VTT after nephrectomy with tumor thrombectomy.

Methods

Patients with newly diagnosed RCC who underwent 18F-FDG PET/CT were reviewed retrospectively. The diagnostic efficacy of 18F-FDG PET/CT in VTT was analyzed. Logistic regression analysis was carried out to identify the clinical variables and PET/CT variables (including maximum standardized uptake value (SUVmax) of primary tumor, VTT SUVmax and primary tumor size) for differentiating early VTT (Mayo 0-II) from advanced VTT (Mayo III-IV). Cox proportional hazard analyses were used to evaluate clinicopathological factors and PET/CT factors (including distant metastasis, primary tumor SUVmax, VTT SUVmax and primary tumor size) for disease-free survival (DFS) in patients with VTT after operation.

Results

A total of 174 eligible patients were included in this study, including 114 men (65.5%) and 60 women (34.5%), with a median age of 58 years (range, 16–81 years). The distribution of pathological tumor stage (T stage) was 56 (T1), 17 (T2), 95 (T3), and 6 cases (T4), respectively. According to WHO/ISUP grade, except for 4 cases of chromophobe cell RCC, there were 14 patients (8.0%) of grade 1, 59 patients (33.9%) of grade 2, 74 patients (42.5%) of grade 3 and 23 patients (13.2%) of grade 4. The median maximum diameter of the primary tumor on PET/CT was 7.3 cm (5.0–9.5 cm). The distal metastasis was observed in 46 patients (26.4%). Sixty-one cases (35.1%) were confirmed with VTT by pathology. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of 18F-FDG PET/CT imaging were 96.7, 99.1, 98.3, 98.3, and 98.2%, in detecting VTT, respectively, and 70.0, 100.0, 94.9, 100.0, and 94.2%, in evaluating the level of VTT, respectively. Elevated VTT SUVmax (≥5.20) could significantly distinguish the early VTT group and advanced VTT group (P = 0.010). In the prognosis analysis, elevated VTT SUVmax (≥4.30) (P = 0.018, HR 3.123, 95% CI 1.212–8.044) and distant metastasis (P = 0.013, HR 3.344, 95% CI 1.293–8.649) were significantly independent predictors for DFS.

Conclusion

Preoperative 18F-FDG PET/CT has a high diagnostic efficacy in detecting VTT and evaluating its level in RCC patients. Those patients with elevated VTT SUVmax should be carefully monitored to detect the possibility of disease progression after operation.

Role of Imaging in Renal Cell Carcinoma: A Multidisciplinary Perspective

With the expansion in cross-sectional imaging over the past few decades, there has been an increase in the number of incidentally detected renal masses and an increase in the incidence of renal cell carcinomas (RCCs). The complete characterization of an indeterminate renal mass on CT or MR images is challenging, and the authors provide a critical review of the best imaging methods and essential, important, and optional reporting elements used to describe the indeterminate renal mass. While surgical staging remains the standard of care for RCC, the role of renal mass CT or MRI in staging RCC is reviewed, specifically with reference to areas that may be overlooked at imaging such as detection of invasion through the renal capsule or perirenal (Gerota) fascia. Treatment options for localized RCC are expanding, and a multidisciplinary group of experts presents an overview of the role of advanced medical imaging in surgery, percutaneous ablation, transarterial embolization, active surveillance, and stereotactic body radiation therapy. Finally, the arsenal of treatments for advanced renal cancer continues to grow to improve response to therapy while limiting treatment side effects. Imaging findings are important in deciding the best treatment options and to monitor response to therapy. However, evaluating response has increased in complexity. The unique imaging findings associated with antiangiogenic targeted therapy and immunotherapy are discussed. An invited commentary by Remer is available online. Online supplemental material is available for this article. ^©RSNA, 2021.

Preoperative Assessment of Renal Sinus Invasion by Renal Cell Carcinoma according to Tumor Complexity and Imaging Features in Patients Undergoing Radical Nephrectomy

Objective

To identify the association between renal tumor complexity and pathologic renal sinus invasion (RSI) and evaluate the usefulness of computed tomography tumor features for predicting RSI in patients with renal cell carcinoma (RCC).

Materials and Methods

This retrospective study included 276 consecutive patients who underwent radical nephrectomy for RCC with a size of ≤ 7 cm between January 2014 and October 2017. Tumor complexity and anatomical renal sinus involvement were evaluated using two standardized scoring systems: the radius (R), exophytic or endophytic (E), nearness to collecting system or sinus (N), anterior or posterior (A), and location relative to polar lines (RENAL) nephrometry and preoperative aspects and dimensions used for anatomical classification (PADUA) system. CT-based tumor features, including shape, enhancement pattern, margin at the interface of the renal sinus (smooth vs. non-smooth), and finger-like projection of the mass, were also assessed by two independent radiologists. Univariable and multivariable logistic regression analyses were performed to identify significant predictors of RSI. The positive predictive value, negative predictive value (NPV), accuracy of anatomical renal sinus involvement, and tumor features were evaluated.

Results

Eighty-one of 276 patients (29.3%) demonstrated RSI. Among highly complex tumors (RENAL or PADUA score ≥ 10), the frequencies of RSI were 42.4% (39/92) and 38.0% (71/187) using RENAL and PADUA scores, respectively. Multivariable analysis showed that a non-smooth margin and the presence of a finger-like projection were significant predictors of RSI. Anatomical renal sinus involvement showed high NPVs (91.7% and 95.2%) but low accuracy (40.2% and 43.1%) for RSI, whereas the presence of a non-smooth margin or finger-like projection demonstrated comparably high NPVs (90.0% and 91.3% for both readers) and improved accuracy (67.0% and 73.9%, respectively).

Conclusion

A non-smooth margin or the presence of a finger-like projection can be used as a preoperative CT-based tumor feature for predicting RSI in patients with RCC.

Correlation between radiological and histopathological findings in patients undergoing nephrectomy for presumed renal cell carcinoma on computed tomography scan at Grey's Hospital

Background

The incidence of renal cell carcinoma (RCC) is increasing globally owing to the increased use of cross-sectional imaging. Computed tomography (CT) scan is the modality of choice in the diagnosis and pre-operative assessment of RCC. Nephrectomy is the standard treatment for RCC and pre-surgery biopsy is not routinely practised. The accuracy of CT diagnosis and staging in a South African population has not been established.

Objectives

To determine the accuracy of CT scan in the diagnosis and pre-operative staging of RCC at Grey’s Hospital.

Methods

A retrospective chart review was performed; CT scan reports and histopathological results of adult patients who underwent nephrectomy for presumed RCC on CT scan between January 2010 and December 2016 were compared.

Results

Fifty patients met the inclusion criteria for the study. CT significantly overestimated the size of renal masses by 0.7 cm (p = 0.045) on average. The positive predictive value of CT for RCC was 81%. Cystic tumours and those 4 cm and smaller were more likely to be benign. CT demonstrated good specificity for extra-renal extension, vascular invasion and lymph node involvement, but poor sensitivity.

Conclusion

In our South African study population, CT is accurate at diagnosing RCC, but false-positives do occur. Non-enhancing or poorly enhancing, cystic, fat-containing and small lesions (4 cm or smaller) are more likely to be benign and ultrasound-guided biopsy should be considered to avoid unnecessary surgery. CT assessment of extra-renal extension and vascular invasion is challenging and additional imaging modalities such as magnetic resonance imaging (MRI) venogram, duplex Doppler ultrasound or Positron emission tomography–computed tomography (PET/CT) may be beneficial.

Stage T3a renal cell carcinoma: staging accuracy of CT for sinus fat, perinephric fat or renal vein invasion

OBJECTIVE

To study the accuracy of CT for staging T3a (TNM 2009) renal cell carcinoma (RCC).

METHODS

Unenhanced and nephrographic phase CT studies of 117 patients (male:female = 82:35; age range, 21-86 years) with T1-T3a RCC were independently reviewed by 2 readers. The presence of sinus or perinephric fat, or renal vein invasion and tumour characteristics were noted.

RESULTS

Median (range) tumour size was 5.5 (0.9-19.0) cm; and 46 (39%), 16 (14%) and 55 (47%) tumours were pT1, pT2 and pT3a RCC, respectively. The sensitivity/specificity for sinus fat, perinephric fat and renal vein invasion were 71/79%, 83/76% and 59/93% (Reader 1) and 88/71%, 68/72% and 69/91% (Reader 2) with κ = 0.41, 0.43 and 0.61, respectively. Sinus fat invasion was seen in 47/55 (85%) cases with T3a RCC vs 16/55 (29%) and 33/55 (60%) for perinephric fat and renal vein invasion. Tumour necrosis, irregularity of tumour edge and direct tumour contact with perirenal fascia or sinus fat increased the odds of local invasion [odds ratio (OR), 2.5-3.7; p < 0.05; κ = 0.42-0.61]. Stage T3a tumours were centrally located (OR, 3.9; p = 0.0009).

CONCLUSION

Stage T3a RCC was identified with a sensitivity of 59-88% and specificity of 71-93% (κ = 0.41-0.61). Sinus fat invasion was the most common invasive feature.

ADVANCES IN KNOWLEDGE

Centrally situated renal tumours with an irregular tumour edge, inseparable from sinus structures or the perirenal fascia and CT features of tumour necrosis should alert the reader to the possibility of Stage T3a RCC (OR, 2.5-3.9).

Clinical and radiographic predictors of the need for inferior vena cava resection during nephrectomy for patients with renal cell carcinoma and caval tumour thrombus

OBJECTIVE

To evaluate the clinical and radiographic predictors of the need for partial or circumferential resection of the inferior vena cava (IVC) requiring complex vascular reconstruction during venous tumour thrombectomy for renal cell carcinoma (RCC).

PATIENTS AND METHODS

Data were collected on 172 patients with RCC and IVC (levels I-IV) venous tumour thrombus who underwent radical nephrectomy with tumour thrombectomy at the Mayo Clinic between 2000 and 2010. Preoperative imaging was re-reviewed by one of two radiologists blinded to details of the patient's surgical procedure. Univariable and multivariable associations of clinical and radiographic features with IVC resection were evaluated by logistic regression. A secondary analysis was used to assess the ability of the model to predict histological invasion of the IVC by the tumour thrombus.

RESULTS

Of the 172 patients, 38 (22%) underwent IVC resection procedures during nephrectomy. Optimum radiographic thresholds were determined to predict the need for IVC resection based on preoperative imaging included a renal vein diameter at the renal vein ostium (RVo) of 15.5 mm, maximum anterior-posterior (AP) diameter of the IVC of 34.0 mm and AP and coronal diameters of the IVC at the RVo of 24 and 19 mm, respectively. On multivariable analysis, the presence of a right-sided tumour (odds ratio 3.3; P = 0.017), an AP diameter of the IVC at the RVo of ≥24.0 mm (odds ratio 4.4; P = 0.017), and radiographic identification of complete occlusion of the IVC at the RVo (odds ratio 4.9; P < 0.001) were associated with a significantly increased risk of IVC resection. The c-index for the model was 0.81.

CONCLUSIONS

We present a multivariable model of the radiographic features associated with the need for IVC resection during tumour thrombectomy. Pending external validation, this model may be used for preoperative planning, patient counselling and planned involvement of vascular surgical colleagues in anticipation of the need for complex vascular repair.

Omental Nodular Deposits of Recurrent Chromophobe Renal Cell Carcinoma Seen on FDG-PET/CT

We present the case of a 69-year-old male with chromophobe renal cell carcinoma (RCC). Chromophobe RCC accounts for only 4% of renal cancers and it is the least aggressive type. Omental nodular deposits due to RCC metastasis are very rare and it is reported only in more aggressive forms of RCC. This is the first report that shows FluoroDeoxyGlucose - Positron Emission Tomography/Computed Tomgraphy (FDG-PET/CT) images of omental nodular deposits from chromophobe RCC. FDG-PET/CT is becoming very useful in restaging RCC with distant metastases.