18-F fluorodeoxyglucose uptake in positron emission tomography as a pathological grade predictor for renal clear cell carcinomas

Can 18 F FDG PET/CT metabolic parameters be used to noninvasively differentiate between different histopathological subtypes and Fuhrman grades of renal cell cancer?

AIM

To evaluate relationship between metabolic PET metabolic parameters and size of the primary tumor, various histopathological subtypes of renal cell carcinoma (RCC) and Fuhrman grade of the tumors.

MATERIAL AND METHODS

Retrospective analysis of 93 biopsy-proven RCC patients who underwent pretreatment flourine 18 flourodeoxyglucose PET/computed tomography ( 18 F FDG PET/CT) was performed. Quantitative PET parameters, size of the primary tumor, histopathological subtypes and Fuhrman grades of the tumor were extracted. We tried to assess if there was any significant difference in the metabolic patterns of various histopathological subtypes of RCCs, Fuhrman grade of the tumors and size of the primary tumor.

RESULTS

A significant correlation was noted between the size of primary tumor and maximum standardized uptake value (SUV max ), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) ( P  < 0.01, P  < 0.001 and P  < 0.001, respectively). SUV max values correlated significantly with the histopathological subtype ( P  < 0.001). Further sub-analyses was also done by segregating the patients into Low grade (Fuhrman grade 1 and 2) vs. High grade (Fuhrman grade 3 and 4). SUV max , MTV and TLG were significantly different between high grade vs. low grade tumors. ROC analysis yielded cut off values for SUV max , MTV and TLG to differentiate between high grade from low grade tumors.

CONCLUSION

FDG PET/CT with the use of metabolic PET parameters can differentiate between different histopathological subtypes of RCC. Incorporation of metabolic parameters into clinical practice can potentially noninvasively identify patients with low-grade vs. high-grade RCC.

Prognostic Significance of 18F-FDG PET/CT Imaging in Survival Outcomes in Patients with Renal Cell Carcinoma

Objectives:

Renal cell carcinoma (RCC) comprises 85%-90% of primary renal malignant tumors originating from the renal tubular epithelium and has different genetic characteristics. This study aimed to investigate the potential predictive role of ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) and metabolic parameters in overall survival (OS) analysis in patients with RCC.

Methods:

¹⁸F-FDG PET/CT images of 100 patients performed for initial staging before surgical or oncological treatments were analyzed retrospectively. Maximum standard uptake value (SUV_max-T) of the primary tumor was calculated and its relationship to patient survival was analyzed. The median follow-up time was 5.61 years (0.01-8.7 years).

Results:

SUV_max-T levels in the patients ranged from 2.1 to 48.9 (median 5.9, mean 9.0±7.9). SUV_max-T was significantly higher in RCC-related death more positive than in the negative cases (p<0.001). However, there was not any statistical significance for gender and pathological subtypes on the survival outcomes of patients (p=0.264 and p=0.784). The patients’ 1-year, 3-year, and 5-year OS rates were 71%, 61%, and 57%, respectively. The highest action of SUV_max-T for estimating OS was a cut-off level of 5.4, which maintained sensitivity and specificity of 81% and 75%, respectively. However, cancer staging remained independent significance for OS (p<0.001).

Conclusion:

SUV_max of primary tumor and cancer stage were demonstrated as significant prognostic factors for OS in patients with RCC. Evaluation of 18F-FDG accumulation with PET/CT may help plan treatment strategies and predict survival outcomes of these patients at diagnosis.

Novel Imaging Methods for Renal Mass Characterization: A Collaborative Review

CONTEXT

The incidental detection of localized renal masses has been rising steadily, but a significant proportion of these tumors are benign or indolent and, in most cases, do not require treatment. At the present time, a majority of patients with an incidentally detected renal tumor undergo treatment for the presumption of cancer, leading to a significant number of unnecessary surgical interventions that can result in complications including loss of renal function. Thus, there exists a clinical need for improved tools to aid in the pretreatment characterization of renal tumors to inform patient management.

OBJECTIVE

To systematically review the evidence on noninvasive, imaging-based tools for solid renal mass characterization.

EVIDENCE ACQUISITION

The MEDLINE database was systematically searched for relevant studies on novel imaging techniques and interpretative tools for the characterization of solid renal masses, published in the past 10 yr.

EVIDENCE SYNTHESIS

Over the past decade, several novel imaging tools have offered promise for the improved characterization of indeterminate renal masses. Technologies of particular note include multiparametric magnetic resonance imaging of the kidney, molecular imaging with targeted radiopharmaceutical agents, and use of radiomics as well as artificial intelligence to enhance the interpretation of imaging studies. Among these, 99mTc-sestamibi single photon emission computed tomography/computed tomography (CT) for the identification of benign renal oncocytomas and hybrid oncocytic chromophobe tumors, and positron emission tomography/CT imaging with radiolabeled girentuximab for the identification of clear cell renal cell carcinoma, are likely to be closest to implementation in clinical practice.

CONCLUSIONS

A number of novel imaging tools stand poised to aid in the noninvasive characterization of indeterminate renal masses. In the future, these tools may aid in patient management by providing a comprehensive virtual biopsy, complete with information on tumor histology, underlying molecular abnormalities, and ultimately disease prognosis.

PATIENT SUMMARY

Not all renal tumors require treatment, as a significant proportion are either benign or have limited metastatic potential. Several innovative imaging tools have shown promise for their ability to improve the characterization of renal tumors and provide guidance in terms of patient management.

Efficacy of Pre-operative 18F-FDG PET/CT in Prognostic Prediction in Patients With Renal Cell Carcinoma

BACKGROUND/AIM

This study analyzed the parameters provided by preoperative ¹⁸ F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) for prognostic prediction of renal cell carcinoma (RCC).

PATIENTS AND METHODS

FDG-PET/CT data from 66 clear cell RCC and 19 non-clear cell RCC cases between January 2015 and October 2018 were reviewed retrospectively. We compared the two groups according to recurrence/metastasis to determine prognosis-influencing factors. Multivariate Cox hazard regression models were constructed to evaluate factors potentially predicting disease-free survival (DFS) after adjustment for confounders. DFS was then compared between groups.

RESULTS

Standardized uptake values (SUV) of the PET/CT scan were independent predictors of prognosis after adjusting for confounders. RCC cases were divided into two groups by optimal cut-off values. Differences between DFS percentages in high and low SUV groups were significant. Similar results were obtained in clear cell RCC groups.

CONCLUSION

Increased SUV of the PET/CT scan are significant predictors of worse prognoses in patients with surgically resected RCC.

18F-FDG texture analysis predicts the pathological Fuhrman nuclear grade of clear cell renal cell carcinoma

PURPOSE

This article analyzes the image heterogeneity of clear cell renal cell carcinoma (ccRCC) based on positron emission tomography (PET) and positron emission tomography-computed tomography (PET/CT) texture parameters, and provides a new objective quantitative parameter for predicting pathological Fuhrman nuclear grading before surgery.

METHODS

A retrospective analysis was performed on preoperative PET/CT images of 49 patients whose surgical pathology was ccRCC, 27 of whom were low grade (Fuhrman I/II) and 22 of whom were high grade (Fuhrman III/IV). Radiological parameters and standard uptake value (SUV) indicators on PET and computed tomography (CT) images were extracted by using the LIFEx software package. The discriminative ability of each texture parameter was evaluated through receiver operating curve (ROC). Binary logistic regression analysis was used to screen the texture parameters with distinguishing and diagnostic capabilities and whose area under curve (AUC) > 0.5. DeLong's test was used to compare the AUCs of PET texture parameter model and PET/CT texture parameter model with traditional maximum standardized uptake value (SUVmax) model and the ratio of tumor SUVmax to liver SUVmean (SUL)model. In addition, the models with the larger AUCs among the SUV models and texture models were prospectively internally verified.

RESULTS

In the ROC curve analysis, the AUCs of SUVmax model, SUL model, PET texture parameter model, and PET/CT texture parameter model were 0.803, 0.819, 0.873, and 0.926, respectively. The prediction ability of PET texture parameter model or PET/CT texture parameter model was significantly better than SUVmax model (P = 0.017, P = 0.02), but it was not better than SUL model (P = 0.269, P = 0.053). In the prospective validation cohort, both the SUL model and the PET/CT texture parameter model had good predictive ability, and the AUCs of them were 0.727 and 0.792, respectively.

CONCLUSION

PET and PET/CT texture parameter models can improve the prediction ability of ccRCC Fuhrman nuclear grade; SUL model may be the more accurate and easiest way to predict ccRCC Fuhrman nuclear grade.

Association between nuclear grade of renal cell carcinoma and the aorta-lesion-attenuation-difference

INTRODUCTION AND BACKGROUND

Several features noted on renal mass biopsy (RMB) can influence treatment selection including tumor histology and nuclear grade. However, there is poor concordance between renal cell carcinoma (RCC) nuclear grade on RMB compared to nephrectomy specimens. Here, we evaluate the association of nuclear grade with aorta-lesion-attenuation-difference (ALAD) values determined on preoperative CT scan.

METHODS AND MATERIALS

A retrospective review of preoperative CT scans and surgical pathology was performed on patients undergoing nephrectomy for solid renal masses. ALAD was calculated by measuring the difference in Hounsfield units (HU) between the aorta and the lesion of interest on the same image slice on preoperative CT scan. The discriminative ability of ALAD to differentiate low-grade (nuclear grade 1 and 2) and high-grade (nuclear grade 3 and 4) tumors was evaluated by sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under curve (AUC) using ROC analysis. Sub-group analysis by histologic sub-type was also performed.

RESULTS

A total of 368 preoperative CT scans in patients with RCC on nephrectomy specimen were reviewed. Median patient age was 61 years (IQR 52-68). The majority of patients were male, 66% (243/368). Tumor histology was chromophobe RCC in 7.6%, papillary RCC in 15.5%, and clear cell RCC in 76.9%. The majority, 69.3% (253/365) of tumors, were stage T1a. Nuclear grade was grade 1 in 5.46% (19/348), grade 2 in 64.7% (225/348), grade 3 in 26.2% (91/348), and grade 4 in 3.2% (11/348). Nephrographic ALAD values for grade 1, 2, 3, and 4 were 73.7, 46.5, 36.4, and 43.1, respectively (p = 0.0043). Nephrographic ALAD was able to differentiate low-grade from high-grade RCC with a sensitivity of 32%, specificity of 89%, PPV of 86%, and NPV of 36%. ROC analysis demonstrated the predictive utility of nephrographic ALAD to predict high- versus low-grade RCC with an AUC of 0.60 (95% CI 0.51-0.69).

CONCLUSION

ALAD was significantly associated with nuclear grade in our nephrectomy series. Strong specificity and PPV for the nephrographic phrase demonstrate a potential role for ALAD in the pre-operative setting that may augment RMB findings in assessing nuclear grade of RCC. Although this association was statistically significant, the clinical utility is limited at this time given the results of the statistical analysis (relatively poor ROC analysis). Sub-group analysis by histologic subtype yielded very similar diagnostic performance and limitations of ALAD. Further studies are necessary to evaluate this relationship further.

Glucose Metabolism Reprogramming of Primary Tumor and the Liver Is Associated With Disease-Free Survival in Patients With Early NSCLC

Purpose

Tumor promote disease progression by reprogramming their metabolism and that of distal organs, so it is of great clinical significance to study the changes in glucose metabolism at different tumor stages and their effect on glucose metabolism in other organs.

Methods

A retrospective single-centre study was conducted on 253 NSCLC (non-small cell lung cancer) patients with negative lymph nodes and no distant metastasis. According to the AJCC criteria, the patients were divided into different groups based on tumor size: stage IA, less than 3 cm (group 1, n = 121); stage IB, greater than 3-4 cm (group 2, n = 64); stage IIA, greater than 4-5 cm (group 3, n = 36); and stage IIB, greater than 5-7 cm (group 4, n = 32). All of the patients underwent baseline ¹⁸F-FDG PET/CT scans, and the primary lesion SUVmax (maximum standardized uptake value), liver SUVmean (mean standardized uptake value), spleen SUVmean, TLR (Tumor-to-liver SUV ratio) and TSR (Tumor-to-spleen SUV ratio) were included in the study, combined with clinical examination indicators to evaluate DFS (disease free survival).

Results

In NSCLC patients, with the increase in the maximum diameter of the tumor, the SUVmax of the primary lesion gradually increased, and the SUVmean of the liver gradually decreased. The primary lesion SUVmax, liver SUVmean, TLR and TSR were related to disease recurrence or death. The best predictive parameters were different when the tumor size differed. SUVmax had the highest efficiency when the tumor size was less than 4 cm (AUC:0.707 (95% CI, 0.430-0.984) tumor size < 3 cm), (AUC:0.726 (95% CI, 0.539-0.912) tumor size 3-4 cm), liver SUVmean had the highest efficiency when the tumor size was 4-5 cm (AUC:0.712 (95% CI, 0.535-0.889)), and TLR had the highest efficiency when the tumor size was 5-7 cm [AUC:0.925 (95%CI, 0.820-1.000)].

Conclusions

In patients with early NSCLC, glucose metabolism reprogramming occurs in the primary lesion and liver. With the increase in tumor size, different metabolic parameters should be selected to evaluate the prognosis of patients.

Glycolysis on F-18 FDG PET/CT Is Superior to Amino Acid Metabolism on C-11 Methionine PET/CT in Identifying Advanced Renal Cell Carcinoma at Staging

Simple Summary

Alteration of metabolism, including glycolysis and glutaminolysis in malignant tumours, has become a hallmark of cancer and related biological aggressiveness. The metabolic signature of each cancer has been actively investigated for potential new drug development. Of the metabolic imaging biomarkers, F-18 fluorodeoxyglucose (FDG) and C-11 methionine positron emission tomography/computed tomography (PET/CT) are widely studied to evaluate the degree of glucose metabolism and amino acid metabolism, respectively. In this prospective study, we found that both F-18 FDG and C-11 methionine uptakes on PET/CT were heterogeneous in renal cell carcinomas, and increased uptake was associated with higher grades of both radiotracers. Additionally, metabolic tumour volume on F-18 FDG PET/CT but not C-11 methionine PET/CT was significant in predicting advanced-stage renal cell carcinoma. These metabolic features derived with PET/CT may help in the development of new drugs targeting glucose and amino acid metabolic pathways.

Abstract

We evaluated the value of F-18 fluorodeoxyglucose (FDG) and C-11 methionine positron emission tomography/computed tomography (PET/CT) to predict high-Fuhrman grade and advanced-stage tumours in patients with renal cell carcinoma (RCC). Forty patients with RCC underwent F-18 FDG and C-11 methionine PET/CT between September 2016 and September 2018. They were classified into limited (stages I and II, n = 15) or advanced stages (stages III and IV, n = 25) according to pathological staging. Logistic regressions were used to predict the advanced stage using various parameters, including maximum standardised uptake value (SUV_max) and metabolic tumour volume (MTV). Receiver operating characteristic analyses were performed to predict high-grade tumours (Fuhrman 3 and 4). On univariate analysis, tumour size, SUV_max and MTV of F-18 FDG and C-11 methionine, and Fuhrman grades were significant predictors for the advanced stage. On multivariate analysis, F-18 FDG MTV > 21.3 cm³ was the most significant predictor (p < 0.001). The area under the curve for predicting high-grade tumours was 0.830 for F-18 FDG (p < 0.001) and 0.726 for C-11 methionine PET/CT (p = 0.014). In conclusion, glycolysis on F-18 FDG PET/CT and amino acid metabolism on C-11 methionine PET/CT were variable but increased in high-grade RCCs. Increased MTV on F-18 FDG PET/CT is a powerful predictor of advanced-stage tumours.

Semi-quantitative F-18-FDG PET/computed tomography parameters for prediction of grade in patients with renal cell carcinoma and the incremental value of diuretics

OBJECTIVE

The primary objective of the study was to evaluate the correlation between semi-quantitative F-18 FDG PET parameters and renal cell carcinoma (RCC) grade and its role in predicting the histopathological grade in RCC. The secondary objective was to evaluate the role of forced diuresis in improving the diagnostic accuracy of F-18 FDG for RCC.

METHODS

Thirty-three patients with radiologically proven RCC were included in the study. All patients underwent PET/CT on a dedicated PET/CT scanner (Biograph mCT; Siemens Medical Solutions, Erlangen, Germany) 45-60 min post-injection F-18-FDG. Patients were then injected 1 mg/kg body weight furosemide (upto 40 mg) and regional PET/CT images of abdomen were acquired after 2 h. For both baseline and post-diuretic F-18-FDG PET/CT scans, maximum standardized uptake value for tumor (SUVmax), mean SUV for tumor, metabolic tumor volume (MTV), tumor-to-liver (T/L) and tumor-to-kidney ratio (T/K) were calculated. Histopathology findings were considered as the reference standard. To assess the incremental value of diuresis in scan interpretation, visual analysis of scans was done.

RESULTS

Of 33 patients, histopathology grading was available for comparison with metabolic tumor markers in all except four. Of 29 patients (mean age = 51.89 ± 13.54 years), 20 patients had clear cell (cc) type while rest had non-cc RCC. Difference between the mean values among the categories was insignificant for all parameters except T/K. Fuhrman grading was obtained in 25 patients (17 low and eight high). SUVmax, MTV and T/L were found to be significantly different between low and high grade patients. Significantly strong positive correlation was observed between Furhman grades and tumor metabolism (r ≥ 0.5). No significant difference was observed between baseline and post-diuretic scan in any of the patients.

CONCLUSION

Semi-quantitative F-18 FDG PET parameters (SUVmax, MTV and T/L) were found to be significantly correlated with Fuhrman grade in patients with RCC and are important markers for differentiation between low- and high-grade tumors. Furthermore, forced diuresis had no incremental value in characterization of primary RCC lesions.

Mitochondrial DNA alterations underlie an irreversible shift to aerobic glycolysis in fumarate hydratase-deficient renal cancer

Understanding the mechanisms of the Warburg shift to aerobic glycolysis is critical to defining the metabolic basis of cancer. Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) is an aggressive cancer characterized by biallelic inactivation of the gene encoding the Krebs cycle enzyme fumarate hydratase, an early shift to aerobic glycolysis, and rapid metastasis. We observed impairment of the mitochondrial respiratory chain in tumors from patients with HLRCC. Biochemical and transcriptomic analyses revealed that respiratory chain dysfunction in the tumors was due to loss of expression of mitochondrial DNA (mtDNA)-encoded subunits of respiratory chain complexes, caused by a marked decrease in mtDNA content and increased mtDNA mutations. We demonstrated that accumulation of fumarate in HLRCC tumors inactivated the core factors responsible for replication and proofreading of mtDNA, leading to loss of respiratory chain components, thereby promoting the shift to aerobic glycolysis and disease progression in this prototypic model of glucose-dependent human cancer.

2-[18F]FDG PET/CT parameters associated with WHO/ISUP grade in clear cell renal cell carcinoma

PURPOSE

To explore the potential parameters from preoperative 2-[¹⁸F]FDG PET/CT that might associate with the World Health Organization/the International Society of Urological Pathology (WHO/ISUP) grade in clear cell renal cell carcinoma (ccRCC).

METHODS

One hundred twenty-five patients with newly diagnosed ccRCC who underwent 2-[¹⁸F]FDG PET/CT prior to surgery or biopsy were retrospectively reviewed. The metabolic parameters and imaging features obtained from 2-[¹⁸F]FDG PET/CT examinations were analyzed in combination with clinical characteristics. Univariate and multivariate logistic regression analyses were performed to identify the predictive factors of WHO/ISUP grade.

RESULTS

Metabolic parameters of primary tumor maximum standardized uptake value (SUVmax), tumor-to-liver SUV ratio (TLR), and tumor-to-kidney SUV ratio (TKR) were significantly different between any two of the four different WHO/ISUP grades, except those between the WHO/ISUP grade 3 and grade 4. The optimal cutoff values to predict high WHO/ISUP grade for SUVmax, TLR, and TKR were 4.15, 1.63, and 1.59, respectively. TLR (AUC: 0.841) was superior to TKR (AUC: 0.810) in distinguishing high and low WHO/ISUP grades (P = 0.0042). In univariate analysis, SUVmax, TLR, TKR, primary tumor size, tumor thrombus, distant metastases, and clinical symptoms could discriminate between the high and low WHO/ISUP grades (P < 0.05). In multivariate analysis, TLR (P < 0.001; OR: 1.732; 95%CI: 1.289-2.328) and tumor thrombus (P < 0.001; OR: 6.199; 95%CI: 2.499-15.375) were significant factors for differentiating WHO/ISUP grades.

CONCLUSION

Elevated TLR (> 1.63) and presence of tumor thrombus from preoperative 2-[¹⁸F]FDG PET/CT can distinguish high WHO/ISUP grade ccRCC effectively. 2-[¹⁸F]FDG PET/CT may be a feasible method for noninvasive assessment of WHO/ISUP grade.

Elevated tumor-to-liver standardized uptake value ratio (TLR) from preoperative 18F-FDG PET/CT predicts poor prognosis of patients with clear cell renal cell carcinoma after nephrectomy

AIM

To assess the potential of using preoperative ¹⁸F-FDG PET/CT to predict the prognosis of patients with clear cell renal cell carcinoma (ccRCC) after nephrectomy.

METHODS

Sixty-nine patients with newly diagnosed ccRCC who underwent ¹⁸F-FDG PET/CT prior to surgery were retrospectively reviewed. The metabolic parameters of maximum standardized uptake value (SUVmax) and tumor-to-liver ratio (TLR) from ¹⁸F-FDG PET/CT were obtained. Clinicopathological characteristics, including the World Health Organization/the International Society of Urological Pathology (WHO/ISUP) grade, pathological tumor node metastasis (pTNM) stage, venous tumor thrombus, and so on, were acquired. Univariate and multivariate Cox proportional hazards analyses were performed to identify the prognostic factors for disease-free survival (DFS).

RESULTS

Of the 69 patients, 25 patients (36.2%) experienced disease progression during the follow-up period. In univariate analysis, the primary tumor size (>4.85 cm), pTNM stage (Ⅲ/Ⅳ), WHO/ISUP grade (G3/4), venous tumor thrombus, adjuvant therapy, SUVmax (>3.55), and TLR (>1.66) were found to correlate with the incidence of decreased DFS (P < 0.05). In multivariate analysis, TLR (P = 0.007, HR: 5.489, 95%CI: 1.605-18.774) and pTNM stage (P = 0.024, HR: 10.385, 95%CI: 1.361-79.238) were revealed to serve as independent prognostic predictors for DFS after adjustment for other variables. Only 3 cases (8.3%) with normal TLR showed disease progression, while 22 cases (66.7%) with elevated TLR experienced disease progression.

CONCLUSION

ccRCC patients with preoperatively elevated TLR (>1.66) and high pTNM stages (Ⅲ/Ⅳ) had significantly unfavorable survival outcomes. These patients should be carefully monitored to detect the possibility of disease progression after nephrectomy as early as possible.

PCK1 Regulates Glycolysis and Tumor Progression in Clear Cell Renal Cell Carcinoma Through LDHA

Background

Suppressed gluconeogenesis and increased glycolysis are common in clear cell renal cell carcinoma (ccRCC). Phosphoenolpyruvate carboxykinase 1 (PCK1) is a rate-limiting gluconeogenesis enzyme. However, the role of PCK1 in tumor metabolism and progression remains unclear.

Methods

Artificial modulation of PCK1 (down- and upregulation) in two ccRCC cell lines was performed to explore the role of PCK1 in the glycolytic phenotype and in tumor growth and metastasis in vitro and in vivo. Sixty-two patients with ccRCC underwent ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography. The levels of PCK1 and lactate dehydrogenase A (LDHA) in ccRCC tissues and peritumor tissues were investigated with immunohistochemistry. The relationships between ¹⁸F-FDG accumulation and the expression of PCK1 and LDHA were analyzed. The mechanisms underlying the regulation of LDHA by PCK1 were analyzed using in vitro molecular techniques.

Results

PCK1 suppressed ccRCC cell growth and metastasis in vitro and inhibited tumorigenesis in nude mice by blocking the aerobic glycolysis pathway. Clinically, low levels of PCK1 expression were associated with poor prognosis in patients with ccRCC. The expression level of PCK1 was negatively correlated with tumor progression, the LDHA expression level and ¹⁸F-FDG accumulation in primary ccRCC tissue. We also demonstrated that PCK1 reduces the stability of LDHA through posttranslational regulation. Finally, we showed that the effects of PCK1 on glucose metabolism, cell proliferation and metastasis are mediated via the inhibition of LDHA.

Conclusion

Our study identified a novel molecular mechanism underlying the Warburg effect. PCK1 may serve as a candidate prognostic biomarker, and targeting the PCK1/LDHA pathway might be a new strategy to selectively inhibit tumor metabolism in human ccRCC.

Associations between FDG-PET and Ki 67-index in head and neck cancer: A meta-analysis

BACKGROUND

FDG-PET might be able to reflect histopathology features of tumors. Ki 67 in head and neck carcinomas (HNSCC). The present study sought to elucidate the association between Ki 67 index and SUVmax based upon a large patient sample.

METHODS

PubMed database was screened for studies analyzed the relationship between Ki 67 and SUV in HNSCC. Nine studies comprising 211 patients were suitable for analysis.

RESULTS

SUVmax increased with tumor grade and was statistically significant different between G1, G2, and G3 tumors. The ROC analysis for discrimination between G1/G2 and G3 tumors revealed an area under curve of 0.71. In the overall patient sample, SUVmax correlated statistically significant with Ki 67 index (r = 0.154, P = .032).

CONCLUSION

The present study identified a weak correlation between SUV values and proliferation index Ki 67 index in HNSCC in a large patient sample. Therefore, SUVmax cannot be used as surrogate parameter for proliferation activity in HNSCC.

PET-CT and PET-MR in urological cancers other than prostate cancer: An update on state of the art

Hybrid positron emission tomography with computed tomography (PET/CT) and magnetic resonance imaging (PET/MRI) have enabled the combination of morphologic and functional imaging with the promise of providing better information in guiding therapy. Further advance has been made in the past decade with the development of newer radiotracers and optimization of the technical aspects. We performed a search in PubMed, Scopus, and Google Scholar for peer-reviewed literature concerning the advances and newer developments in the imaging of nonprostate urologic cancers between 2005 and 2017. This review aims at summarizing the current evidence on PET imaging in nonprostate urologic cancers and their impact on the diagnosis, staging, prognostication, response assessment, and restaging of these malignancies. However, much of the evidence is still in infancy and has not been incorporated into routine management or the practice guidelines of National Comprehensive Cancer Network or European Society for Medical Oncology (ESMO).

Differentiation of low- and high-grade clear cell renal cell carcinoma: Tumor size versus CT perfusion parameters

PURPOSE

To compare the utility of tumor size and CT perfusion parameters for differentiation of low- and high-grade clear cell renal cell carcinoma (RCC).

MATERIALS AND METHODS

Tumor size, Equivalent blood volume (Equiv BV), permeability surface-area product (PS), blood flow (BF), and Fuhrman pathological grading of clear cell RCC were retrospectively analyzed.

RESULTS

High-grade clear cell RCC had significantly higher tumor size and lower PS than low grade. Tumor size positively correlated with Fuhrman grade, but PS negatively did.

CONCLUSIONS

Tumor size and PS were significantly independent indexes for differentiating high-grade from low-grade clear cell RCC.

Correlation between CT perfusion parameters and Fuhrman grade in pTlb renal cell carcinoma

PURPOSE

To evaluate the correlation of CT perfusion parameters with the Fuhrman grade in pT1b (4-7 cm) renal cell carcinoma (RCC).

METHODS

CT perfusion imaging and Fuhrman pathological grading of pT1b RCC were performed in 48 patients (10 grade 1, 27 grade 2, 9 grade 3, and 2 grade 4). Equivalent blood volume (BV _Equiv), permeability surface area product (PS), and blood flow (BF) of tumors were measured. Grade 1 and 2 were defined as low-grade group (n = 37), meanwhile high-grade group (n = 11) included grade 3 and 4. Comparisons of CT perfusion parameters and tumor size of the two different groups were performed. Correlations between CT perfusion parameters, Fuhrman grade (grade 1, 2, 3, and 4), and tumor size were assessed.

RESULTS

PS was significantly lower in high grade than in low-grade pT1b RCC (P = 0.004). However, no significant differences were found in BV _Equiv and BF between the two groups (P > 0.05 for both). The optimal threshold value, sensitivity, specificity, and the area under the ROC curve for distinguishing the two groups using PS were 68.8 mL/100 g/min, 0.7, 0.8, and 0.8, respectively. Negative significant correlation was observed between PS and Fuhrman grade (r = -0.338, P = 0.019).

CONCLUSIONS

The PS of pT1b RCC had negative significant correlation with Fuhrman grade. CT perfusion appeared to be a non-invasive means to predict high Fuhrman grade of pT1b RCC preoperatively and guide the optimal treatment for the patient.

Update on advances in molecular PET in urological oncology

Integrated positron emission tomography/computed tomography (PET/CT) with 2-[(18)F]fluoro-2-deoxy-D-glucose ((18)F-FDG) has emerged as a powerful tool for the combined metabolic and anatomic evaluation of many cancers. In urological oncology, however, the use of (18)F-FDG has been limited by a generally low tumor uptake, and physiological excretion of FDG through the urinary system. (18)F-FDG PET/CT is useful when applied to specific indications in selected patients with urological malignancy. New radiotracers and positron emission tomography/magnetic resonance imaging (PET/MRI) are expected to further improve the performance of PET in uro-oncology.

Imaging-based diagnosis of acute renal allograft rejection

Kidney transplantation is the best available treatment for patients with end stage renal disease. Despite the introduction of effective immunosuppressant drugs, episodes of acute allograft rejection still endanger graft survival. Since efficient treatment of acute rejection is available, rapid diagnosis of this reversible graft injury is essential. For diagnosis of rejection, invasive core needle biopsy of the graft is the “gold-standard”. However, biopsy carries the risk of significant graft injury and is not immediately feasible in patients taking anticoagulants. Therefore, a non-invasive tool assessing the whole organ for specific and fast detection of acute allograft rejection is desirable. We herein review current imaging-based state of the art approaches for non-invasive diagnostics of acute renal transplant rejection. We especially focus on new positron emission tomography-based as well as targeted ultrasound-based methods.

Clinical role of early dynamic FDG-PET/CT for the evaluation of renal cell carcinoma

OBJECTIVES

We studied the usefulness of early dynamic (ED) and whole-body (WB) FDG-PET/CT for the evaluation of renal cell carcinoma (RCC).

METHODS

One hundred patients with 107 tumours underwent kidney ED and WB FDG-PET/CT. We visually and semiquantitatively evaluated the FDG accumulation in RCCs in the ED and WB phases, and compared the accumulation values with regard to histological type (clear cell carcinoma [CCC] vs. non-clear cell carcinoma [N-CCC]), the TNM stage (high stage [3-4] vs. low stage [1-2]), the Fuhrman grade (high grade [3-4] vs. low grade [1-2]) and presence versus absence of venous (V) and lymphatic (Ly) invasion.

RESULTS

In the ED phase, visual evaluation revealed no significant differences in FDG accumulation in terms of each item. However, the maximum standardized uptake value and tumour-to-normal tissue ratios were significantly higher in the CCCs compared to the N-CCCs (p < 0.001). In the WB phase, in contrast, significantly higher FDG accumulation (p < 0.001) was found in RCCs with a higher TNM stage, higher Furman grade, and the presence of V and Ly invasion in both the visual and the semiquantitative evaluations.

CONCLUSIONS

ED and WB FDG-PET/CT is a useful tool for the evaluation of RCCs.

KEY POINTS

• ED and WB FDG-PET/ CT helps to assess patients with RCC • ED FDG-PET/CT enabled differentiation between CCC and N-CCC • FDG accumulation in the WB phase reflects tumour aggressiveness • Management of RCC is improved by ED and WB FDG-PET/CT.