The role of molecular imaging in the characterization of renal masses

Molecular Imaging Diagnosis of Renal Cancer Using 99mTc-Sestamibi SPECT/CT and Girentuximab PET-CT-Current Evidence and Future Development of Novel Techniques

Novel molecular imaging opportunities to preoperatively diagnose renal cell carcinoma is under development and will add more value in limiting the postoperative renal function loss and morbidity. We aimed to comprehensively review the research on single photon emission computed tomography/computed tomography (SPECT/CT) and positron emission tomography computed tomography (PET-CT) molecular imaging and to enhance the urologists' and radiologists' knowledge of the current research pattern. We identified an increase in prospective and also retrospective studies that researched to distinguish between benign and malignant lesions and between different clear cell renal cell carcinoma subtypes, with small numbers of patients studied, nonetheless with excellent results on specificity, sensitivity and accuracy, especially for ^99mTc-sestamibi SPECT/CT that delivers quick results compared to a long acquisition time for girentuximab PET-CT, which instead gives better image quality. Nuclear medicine has helped clinicians in evaluating primary and secondary lesions, and has lately returned with new and exciting insights with novel radiotracers to reinforce its diagnostic potential in renal carcinoma. To further limit the renal function loss and post-surgery morbidity, future research is mandatory to validate the results and to clinically implement the diagnostic techniques in the context of precision medicine.

A review of 99mTc-sestamibi SPECT/CT for renal oncocytomas: A modified diagnostic algorithm

99mTc-sestamibi SPECT/CT is a promising nuclear medicine imaging investigation for benign renal lesions such as renal oncocytomas. The purpose of this article is to i) review the current literature on 99mTc-sestamibi SPECT/CT, ii) to review to current application of 99mTc-sestamibi SPECT/CT for indeterminate renal lesion imaging, and iii) to discuss present limitations and areas for future research. The literature has been reviewed up to April 2022 for articles relating to the application of 99mTc-sestamibi SPECT/CT for benign renal lesions including a recently published systematic review and meta-analysis performed by the authors. One study evaluating 99mTc-sestamibi SPECT alone and five studies evaluating 99mTc-sestamibi SPECT/CT have been performed to date. 99mTc-sestamibi SPECT/CT demonstrates high sensitivity and specificity for detecting benign renal lesions, particularly renal oncocytomas. 99mTc-sestamibi SPECT/CT demonstrates near-perfect specificity for benign and low-grade renal lesions. The optimal quantified threshold ratio for tumor-to-background renal parenchyma radiotracer uptake for a positive result is > 0.6. In this article, we propose a modified diagnostic algorithm for small enhancing renal masses measuring 1-4 cm in which suspected benign lesions after conventional imaging are considered for 99mTc-sestamibi SPECT-CT. In this algorithm, positive studies can be monitored with active surveillance rather than requiring invasive biopsy and/or targeted therapy.

A 25-year perspective on evaluation and understanding of biomarkers in urologic cancers

The past 25 years have witnessed an explosion of investigative attempts to identify clinically useful biomarkers which can have meaningful impacts for patients with urologic cancers. However, in spite of the enormous amount of research aiming to identify markers with the hope of impacting patient care, only a handful have proven to have true clinical utility. Improvements in targeted imaging, pan-omics evaluation, and genetic sequencing at the tissue and single-cell levels have yielded many potential targets for continued biomarker investigation. This article, as one in this series for the 25th Anniversary Issue of Urologic Oncology: Seminars and Original Investigations, serves to give a perspective on our progress and failures over the past quarter-century in our highest volume urologic cancers: prostate, bladder, and kidney cancers.

Targeted PET/CT imaging for clear cell renal cell carcinoma with radiolabeled antibodies: recent developments using girentuximab

PURPOSE OF REVIEW

Conventional imaging is unable to differentiate clear cell renal cell carcinoma (ccRCC) from other more indolent and benign renal tumors. Positron emission tomography/computed tomography (PET/CT) using radiolabeled antibodies may aid in detecting both localized and metastatic ccRCC. The purpose of this review is to summarize recent literature regarding the use of radiolabeled antibodies for imaging of ccRCC.

RECENT FINDINGS

Two recent studies evaluated the use of radiolabeled anticarbonic anhydrase IX antibody girentuximab for the imaging of ccRCC. PET/CT with 89zirconium-labeled girentuximab (89Zr-girentuximab PET/CT) was used to guide clinical decision making in 16 patients with localized disease. It had a high specificity for detecting ccRCC with 6/6 resected lesions with uptake proven to be ccRCC, all lesion without uptake showed to be indolent during follow-up. Clinical management was changed in 36% (5/14) of patients with the metastatic disease based on outcomes of the scan. Furthermore, in 42 patients 89Zr-girentuximab PET/CT combined with CT outperformed CT alone or combined with 18F fludeoxyglucose PET for detection of metastasis.

SUMMARY

89Zr-girentuximab PET/CT has the ability to diagnose ccRCC in localized disease. In metastatic disease, it enables the differentiation of ccRCC from non-ccRCC cancers and the evaluation of disease extent. 89Zr-girentuximab PET/CT diagnostic accuracy is currently evaluated in a multicenter phase III trial.

Collaborative Review: Factors Influencing Treatment Decisions for Patients with a Localized Solid Renal Mass

CONTEXT

With the addition of active surveillance and thermal ablation (TA) to the urologist's established repertoire of partial (PN) and radical nephrectomy (RN) as first-line management options for localized renal cell carcinoma (RCC), appropriate treatment decision-making has become increasingly nuanced.

OBJECTIVE

To critically review the treatment options for localized, nonrecurrent RCC; to highlight the patient, renal function, tumor, and provider factors that influence treatment decisions; and to provide a framework to conceptualize that decision-making process.

EVIDENCE ACQUISITION

A collaborative critical review of the medical literature was conducted.

EVIDENCE SYNTHESIS

We identify three key decision points when managing localized RCC: (1) decision for surveillance versus treatment, (2) decision regarding treatment modality (TA, PN, or RN), and (3) decision on surgical approach (open vs minimally invasive). In evaluating factors that influence these treatment decisions, we elaborate on patient, renal function, tumor, and provider factors that either directly or indirectly impact each decision point. As current nomograms, based on preselected patient datasets, perform poorly in prospective settings, these tools should be used with caution. Patient decision aids are an underutilized tool in decision-making.

CONCLUSIONS

Localized RCC requires highly nuanced treatment decision-making, balancing patient- and tumor-specific clinical variables against indirect structural influences to provide optimal patient care.

PATIENT SUMMARY

With expanding treatment options for localized kidney cancer, treatment decision is highly nuanced and requires shared decision-making. Patient decision aids may be helpful in the treatment discussion.

Combining contrast-enhanced ultrasound, CT perfusion and 99mTc-Sestamibi SPECT/CT to guide diagnosis in a case of solid renal tumour

Definitive, pre-operative differentiation of solid renal lesions by ultrasound, contrast-enhanced multiphasic CT or MRI examinations is often not possible. An increasing amount of literature indicates the added value of ^99mTc-Sestamibi SPECT/CT, CT perfusion and contrast-enhanced ultrasound in the pre-operative characterisation of solid renal tumours. This case report presents the diagnostic approach of a solid renal tumour that turned out to be a hybrid oncocytic chromophobe tumour in a patient with Stage 3 renal failure by combining the three aforementioned modern examination techniques.

Dual-Phase 99mTc-MIBI SPECT/CT in the Characterization of Enhancing Solid Renal Tumors: A Single-Institution Study of 147 Cases

PURPOSE

The aim of this study was to investigate the value of dual-phase Tc-MIBI SPECT/CT in the differential diagnosis between benign and malignant enhancing solid renal tumors.

PATIENTS AND METHODS

Totally, 180 patients were imaged with dual-phase Tc-MIBI SPECT/CT, which was performed 30 minutes and 90 minutes after Tc-MIBI administration. Among them, 147 patients with 148 histologically proved solid renal tumors met the selection criteria and were included for the final analysis. Relative quantification was performed by measuring the radioactive uptake ratio of tumor to the normal renal parenchymal background for both early and delayed images.

RESULTS

Benign renal tumors (4 renal oncocytomas and 8 lipid-poor angiomyolipomas) demonstrated a significantly higher early relative uptake value (ERUV) and delayed relative uptake value (DRUV) than malignant renal tumors (n = 136; both P < 0.0001). The ERUV cutoff value of 0.53 helped to differentiate benign from malignant renal tumors, with sensitivity of 100%, specificity of 94.8%, and accuracy of 95.3% for the diagnosis of benign renal tumors. The DRUV cutoff value of 0.50 helped to differentiate benign from malignant renal tumors, with sensitivity of 100%, specificity of 96.3%, and accuracy of 96.6% for the diagnosis of benign renal tumors. There was no statistically significant difference between the efficacy of ERUV and DRUV in the differential diagnosis between benign and malignant renal tumors (P = 0.5). The efficacies of ERUV and DRUV were all significantly higher than the retention index (both P < 0.0001).

CONCLUSIONS

Both early and delayed phase Tc-MIBI SPECT/CT are helpful for distinguishing benign renal oncocytoma and lipid-poor angiomyolipoma from malignant renal tumors, and the delayed phase imaging tends to show higher diagnostic accuracy.

Dynamic 68Ga-PSMA-11 PET/CT for the Primary Evaluation of Localized Renal Mass: A Prospective Study

The potential role of prostate-specific membrane antigen (PSMA) PET/CT in non-prostate cancer tumors has shown promising results. We examined the performance of dynamic ⁶⁸Ga-PSMA-11 PET/CT (DPSMA) for the evaluation of localized renal mass. Methods: A prospective case series of patients with a newly diagnosed renal mass who were referred for surgery was examined. DPSMA was performed in a standardized manner before surgery. The final surgical histology served as the standard of reference. PSMA expression in the tumor vasculature was assessed and staining intensity was scored. Tracer uptake and PSMA expression were compared between benign and malignant tissue. Results: Of 29 enhancing renal masses evaluated in 27 patients, 24 (83%) were malignant lesions. The median SUV_mean of benign and malignant lesions was 2.3 (interquartile range [IQR], 2.2-2.7) and 6.8 (IQR, 4.2-10.1), respectively (P = 0.009). Median SUV_max of benign and malignant lesions was 3.8 (IQR, 3.3-4.5) and 9.4 (IQR, 5.4-15.8), respectively (P = 0.015). The median washout coefficient (K ₂) was significantly lower in malignant lesions than in benign lesions (0.17 vs. 0.70, P = 0.02). Positive PSMA staining was found in 20 of 24 malignant lesions and in 2 of 5 benign lesions (P = 0.04). Conclusion: This pilot study demonstrated DPSMA uptake and kinetics in localized renal masses. Increased ⁶⁸Ga-PSMA-11 tracer uptake and intratumoral retention correlate with PSMA expression in malignant renal tumors compared with benign renal masses, supporting further assessment of DPSMA as a potential tool for evaluating localized renal masses.

Diagnostic accuracy of 99mTc-sestamibi SPECT/CT for detecting renal oncocytomas and other benign renal lesions: a systematic review and meta-analysis

PURPOSE

The primary objectives of this systematic review and meta-analysis were to evaluate the diagnostic accuracy of 99mTc-sestamibi SPECT/CT for detecting renal oncocytoma versus (1) all other renal lesions and (2) chromophobe renal cell carcinoma (ChrRCC) alone.

METHODS

A systematic review of MEDLINE, EMBASE, Scopus, the Cochrane Library, and the Gray Literature was performed. Original articles with > 5 patients evaluating oncocytomas versus other renal lesions with SPECT/CT using a pathological reference standard were included. Patient, clinical, imaging, and performance parameters were independently acquired by two reviewers. Meta-analysis was performed using a bivariate mixed-effects regression model.

RESULTS

Four articles with a total of 117 renal lesions were included in analysis. The pooled and weighted sensitivity and specificity values of 99mTc-sestamibi SPECT/CT for detecting (1) renal oncocytoma versus other renal lesions were 92% (95% CI 72-98%) and 88% (95% CI 79-94%), respectively, and (2) 89% and 67%, respectively, for renal oncocytoma versus ChrRCC. The specificity for the detecting the oncocytoma-ChrRCC spectrum was 96% (95% CI 84-99%). The sensitivity and specificity for detecting benign versus malignant renal lesions were 86% (95% CI 66-95%) and 90% (95% CI 80-95%), and 88% and 95% when HOCTs were characterized as benign. All reporting studies used a cut-off tumor-to-background renal parenchyma radiotracer uptake ratio of > 0.6 for positive studies.

CONCLUSION

99mTc-sestamibi SPECT/CT demonstrates a high sensitivity and specificity for characterizing benign and low-grade renal lesions. This test can help improve the diagnostic confidence for patients with indeterminate renal masses being considered for active surveillance.

Long Non-Coding RNA DUXAP8 Enhances Renal Cell Carcinoma Progression via Downregulating miR-126

Background

Renal cell carcinoma (RCC) is one of the common malignant tumors in the urinary system, which endangers human health for a long time. The past decade, the molecular biology of renal cell carcinoma has made considerable progress, so that we have a more profound understanding of renal cell carcinoma. Molecular biological mechanism of renal cell carcinoma remains to be explored. Evidence indicates that long non-coding RNAs (lncRNAs) may be important players in human cancer progression, including RCC. In this study, we found that a newly discovered pseudogene-derived lncRNA named DUXAP8, a 2107-bp RNA, was remarkably upregulated in RCC.

Material/Methods

Expression of lncRNA DUXAP8 was determined by a qRT-PCR assay in RCC tissues. The proliferation and invasion of RCC cell were measured by a cell proliferation assay and a Transwell invasion assay. Expression of miR-126 was detected by real-time PCR. Interactions between lncRNA DUXAP8 and miR-126 were measured by a luciferase reporter assay and an RNA-pull down assay. In vivo experiments were used to detect tumor formation.

Results

Together, our study not only identifies lncRNA DUXAP8 as a negative regulator of renal cancer with potential clinical value, but also reveals a regulatory mechanism by long non-coding RNAs to control tumor development.

Conclusions

Results from this study provide evidence that lncRNA DUXAP8 enhances renal cell carcinoma progression via downregulating of miR-126, which offers a new approach for the treatment of RCC.