MRI as a tool to assess surgical margins and pseudocapsule features directly following partial nephrectomy for small renal masses

Current Application of Navigation Systems in Robotic-Assisted and Laparoscopic Partial Nephrectomy: Focus on the Improvement of Surgical Performance and Outcomes

Kidney cancer represents the third most prevalent malignancy among all types of genitourinary cancer worldwide. Currently, there is a growing trend of employing partial nephrectomy for the management of large and complex tumors. Surgical outcomes are associated with some amendable surgical factors, including warm ischemic time, pedicle clamping, preserved volume of renal parenchyma, appropriate surgical strategy, and precise resection of the tumor. Improving surgical performance is pivotal for achieving favorable surgical outcomes. Due to advancements in imaging visualization technology and the shift of the medical paradigm toward precision medicine, an increasing number of navigation systems have been implemented in partial nephrectomy procedures. The navigation system can assist surgeons in formulating optimal surgical strategies and enhance the safety, precision, and feasibility of resecting complex renal tumors. In this review, we provide an overview of currently available navigation systems and their feasible applications, with a focus on how they contribute to the improvement of surgical performance and outcomes during robotic-assisted and laparoscopic partial nephrectomy.

Qualitative and quantitative characteristics of CEUS for renal cell carcinoma and angiomyolipoma: a narrative review

Incidental findings of renal masses are increasing. However, a substantial portion of surgically treated renal masses turn out to be benign on histopathological examination. Thus, there is a clear need for improved pre-surgical assessment to minimize unnecessary invasive procedures. The challenge intensifies when distinguishing between renal cell carcinoma (RCC) and angiomyolipoma (AML) in renal lesions smaller than 4 cm with minimal adipose tissue. In such cases, contrast-enhanced ultrasound (CEUS) has emerged as a valuable diagnostic tool, by utilizing both qualitative and quantitative parameters. Quantitative measures offer objectivity, reliability, and reproducibility compared to qualitative parameters, enabling the characterization of RCC subtypes and differentiation from AML. Qualitative features as enhancement pattern, degree, and peak were less helpful in distinguishing triphasic minimal fat AML (TAML) from epithelioid AML (EAML), with the pseudocapsule sign potentially being the only distinguishing qualitative feature. The pseudocapsule sign was more frequently observed in ccRCCs (38.0%) than in AMLs (15.6%). Moreover, it was detected in 40.0% of EAMLs and 34.5% of ccRCCs but not in TAMLs due to similar growth patterns between EAMLs and low-grade ccRCCs. Quantitative measures such as the time-to-peak (TTP) ratio can further enhance diagnostic accuracy and also TOC ratio should be considered, as it was higher in clear cell RCCs (ccRCCs) and in EAMLs compared to TAMLs, indicating behavior similar to ccRCCs. However, CEUS remains an operator-dependent exam.

Characteristics of peritumoral pseudocapsule in small renal cell carcinoma and its influencing factors

BACKGROUND

The aim of this study was to investigate the peritumoral pseudocapsule (PC) status and identify the factors influencing PC status in small renal cell carcinoma (RCCs).

METHODS

A total of 147 patients with small RCC (≤4 cm) who had undergone tumor enucleation (TE) were assigned into three groups according to PC status: complete PC, PC absence, and PC invasion. Computed tomography (CT) imaging and clinicopathological features were compared among the three groups. Univariate and multivariate analyses were performed to identify factors associated with incomplete PC.

RESULTS

The number of patients with complete PC, PC absence, and PC invasion was 87 (59%), 20 (14%), and 40 (27%), respectively. Compared with the other two groups, tumors with complete PC were most common in clear cell RCC (CCRCC) and showed a hyperenhancement pattern (92%) and clear boundary (63%) on CT scanning images (p < 0.001). PC absence was most common in female patients (50%), whereas PC invasion was more common in male patients (85%) (p = 0.017). The tumor diameter in the PC absence group (2.24 ± 0.93 cm) was shorter compared with that of the complete PC group (2.88 ± 0.76 cm) and PC invasion group (3.16 ± 0.64 cm) (p < 0.001). Univariate and multivariate analysis showed that hypoenhancement pattern, unclear boundary, and non-CCRCC subtype were independent risk factors of incomplete PC.

CONCLUSIONS

Hypoenhancement pattern, unclear boundary, and non-CCRCC subtype were significant predictors of incomplete PC in small RCCs. It remains to be established whether TE is an appropriate procedure for patients with incomplete PC.

Diagnostic Performance of Contrast-Enhanced Ultrasound in the Evaluation of Small Renal Masses: A Systematic Review and Meta-Analysis

Ultrasound (US) is a highly sensitive imaging tool in the detection of renal masses. However, the detection rate of small renal masses (SRMs) (<4 cm) is still limited. In this scenario, contrast-enhanced ultrasound (CEUS) is a relatively novel, but increasingly utilized, diagnostic modality which aims to increase the overall diagnostic ability in the identification of SRMs. In consequence, we performed a systematic review (SR) and pooled meta-analysis to investigate the diagnostic performance of CEUS in the evaluation of SRMs confirmed by pathology. A SR up to April 2022 was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The diagnostic performance of CEUS was evaluated basing on malignant vs. benign SMRs. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) from eligible studies were pooled, and summary receiver operating characteristic (SROC) curves were constructed for each endpoint. Overall, five qualified studies were deemed suitable for this meta-analysis. Finally, diagnostic performance of CEUS showed an accuracy of 0.93 in detecting malignant masses (sensitivity of 0.94, PPV of 0.95, specificity of 0.78, and NPV of 0.73). Taken together, CEUS may represent a promising minimally invasive diagnostic tool for characterization of SMRs, since it allows clinicians to identify malignant lesions.

The Value of Contrast-Enhanced Ultrasound in Diagnosing Small Renal Cell Carcinoma Subtypes and Angiomyolipoma

OBJECTIVES

To retrospectively explore the value of contrast-enhanced ultrasound (CEUS) in differentiating small renal cell carcinomas (RCCs) from angiomyolipomas (AMLs), and distinguishing between clear cell RCC (ccRCC), papillary RCC (pRCC), and chromophobe RCC (chRCC).

METHODS

A total of 151 patients with small renal masses (110 ccRCCs, 12 pRCCs, 9 chRCCs, and 20 AMLs) were enrolled between August 2016 and October 2019.

RESULTS

There were significant differences in terms of enhancement intensity (EI), enhancement homogeneity, perilesional rim-like enhancement (PRE), wash in, and wash out (WO) between RCC and AML (P = .000, .011, .000, .001, .000, respectively). Although there was no significant difference in EI between pRCC and chRCC (P = .272), EI of ccRCC was higher than that of pRCC (P = .000) and chRCC (P = .010). Multivariate regression analysis showed PRE and fast WO were related to RCC (OR = 18.189, 15.141, respectively). Although there were no significant differences in the sensitivity and area under the curve (AUC) between PRE and fast WO (95.0% vs. 95.0%, P = 1.000 and .880 vs. 0.799, P = .123, respectively), the specificity of PRE in predicting RCC was higher than that of fast WO (80.92% vs. 64.89%, P = .011). The sensitivity, specificity, and AUC of the two characteristics combination for differentiating RCC from AML were 95.0%, 90.8%, and 0.920, respectively, and that of EI for differentiating between ccRCC, pRCC, and chRCC were 81.0%, 78.2%, and 0.796, respectively.

CONCLUSIONS

CEUS has value in differentiating small RCCs from AMLs and distinguishing ccRCC, a subtype associated with a greater likelihood of malignant behavior from pRCC and chRCC.

Intraoperative imaging in pathology-assisted surgery

The pathological assessment of surgical specimens during surgery can reduce the incidence of positive resection margins, which otherwise can result in additional surgeries or aggressive therapeutic regimens. To improve patient outcomes, intraoperative spectroscopic, fluorescence-based, structural, optoacoustic and radiological imaging techniques are being tested on freshly excised tissue. The specific clinical setting and tumour type largely determine whether endogenous or exogenous contrast is to be detected and whether the tumour specificity of the detected biomarker, image resolution, image-acquisition times or penetration depth are to be prioritized. In this Perspective, we describe current clinical standards for intraoperative tissue analysis and discuss how intraoperative imaging is being implemented. We also discuss potential implementations of intraoperative pathology-assisted surgery for clinical decision-making.

Detection of a peritumoral pseudocapsule in patients with renal cell carcinoma undergoing robot-assisted partial nephrectomy using enhanced MDCT

To investigate the detection of peritumoral pseudocapsule (PC) using multi-detector row computed tomography (MDCT) for tumors resected by robot-assisted laparoscopic partial nephrectomy (RAPN) for T1 renal cell carcinoma (RCC). Study participants included 206 patients with clinical T1 RCC who underwent RAPN between October 2017 and February 2018. Two radiologists who were blinded to the pathological findings evaluated the computed tomography (CT) images. Radiological diagnosis of a PC was defined by a combination of observations, including a low-attenuation rim between the tumor and renal cortex in the cortico-medullary phase and a high-attenuation rim at the edge of the tumor in the nephrogenic or excretory phase. A PC was detected on CT in 156/206 tumors (76%) and identified by pathology in 182/206 (88%) tumors including 153/166 (92%) clear cell RCC, 13/14 (93%) papillary RCC, and 7/16 (44%) chromophobe RCC. In the whole cohort, CT findings showed a sensitivity of 81.3% (148/182), specificity of 66.7% (16/24), and positive predictive value of 94.9% (148/156). When the data were stratified according to pathological subtypes, MDCT was observed to have a sensitivity of 86.9% (133/153) and specificity of 61.5% (8/13) in clear cell RCC, sensitivity of 38.5% (5/13) and specificity of 100% (1/1) in papillary RCC, and sensitivity of 44.4% (4/7) and specificity of 66.7% (6/9) in chromophobe RCC. A low or high-attenuation rim around the tumor in the cortico-medullary or nephrographic-to-excretory phase indicates a PC of RCC, though the accuracy is not satisfactory even with 64- or 320-detector MDCT.

The clinical value of indocyanine green fluorescence navigation system for laparoscopic partial nephrectomy in the case of complex renal clear cell carcinoma (R.E.N.A.L score ≥7)

Objective: We demonstrated the potential clinical utility of the indocyanine green (ICG) fluorescence navigation system for laparoscopic partial nephrectomy in the case of complex renal clear cell carcinoma (R.E.N.A.L score ≥7).

Methods: Compared with the general laparoscopic partial nephrectomy and ICG fluorescence laparoscopic partial nephrectomy, a series of indicators were analyzed: the basic information like age, sex, and the tumor location; the operative information like the time of renal ischemia, the blood loss, and the complications; and other important indexes like the renal function, the volume of the tumor, and the weight of the specimens.

Results: 60 patients were included in this study. 21 patients in the group of fluorescence laparoscopy, and 39 patients in the group of general laparoscopy. There was no statistical difference for most indexes except the renal function. Preoperative serum creatinine was close (82.4±11.7 vs. 77.5±12.7, mmol/l, p=0.15). However, the patients in the group of fluorescence laparoscopy got a smaller serum creatinine growth degree (12.9±5.3 vs. 17.9±7.3, mmol/l, p=0.008), and a less decreasing level of GFR (16.5±6.4 vs. 24.4±9.8, mL/(min*1.73m²), p=0.001) after the operation. In addition, the average volume of the tumor (28.8±9.8 vs. 26.9±8.2, cm³, p=0.43) and the weight of the specimens (32.3±10.4 vs. 33.9±8.9, g, p=0.52) were no statistical difference. But the group of fluorescence laparoscopy had a smaller ratio of the weight/ the volume (1.13±0.06 vs. 1.28±0.10, g/cm³, p<0.001). And the two groups had a similar test-positivity rate of surgical margins (p=0.19).

Conclusion: Without increasing the rate of positive surgical margins, ICG fluorescence navigation system for laparoscopic partial nephrectomy for complex renal clear cell carcinoma could conserve more normal renal tissue.

7-T MRI of explanted liver and ex-vivo pancreatic specimens: prospective study protocol of radiological-pathological correlation feasibility (the EXLIPSE project)

The study focuses on radiological-pathological correlation between imaging of ex vivo samples obtained by a 7-T scanner and histological examination. The specimens will be derived from native explanted cirrhotic livers, liver grafts excluded from donation because of severe steatosis, and primary pancreatic tumours. Magnetic resonance imaging (MRI) examinations will be performed within 24 h from liver or pancreatic lesion surgical removal. The MRI protocol will include morphological sequences, quantitative T1, T2, and fat-, water-fraction maps with Cartesian k-space acquisition, and multiparametric methods based on a transient-state “MRI fingerprinting”. Finally, the specimen will be fixed by formalin. Qualitative imaging analysis will be performed by two independent blinded radiologists to assess image consistency score. Quantitative analysis will be performed by drawing regions of interest on different tissue zones to measure T1 and T2 relaxation times as well as fat- and water-fraction. The same tissue areas will be analysed by the pathologists. This study will provide the possibility to improve our knowledge about qualitative and quantitative abdominal imaging assessment at 7 T, by correlating imaging characteristics and the corresponding histological composition of ex vivo specimens, in order to identify imaging biomarkers. Trial registration: ClinicalTrials.gov: 13646. Registered 9 July 2019—retrospectively registered

Can acoustic radiation force impulse imaging (ARFI) accurately diagnose renal masses?: A protocol of systematic review and meta-analysis

BACKGROUND

Renal masses are increasingly being discovered because of the wide accessibility of modern high resolution imaging procedures. Previous clinical studies have reported that acoustic radiation force impulse imaging (ARFI) is used for diagnosis of renal masses. However, no study has investigated this topic systematically. Therefore, this study will evaluate the diagnostic value of ARFI for the diagnosis of renal masses.

METHODS

A systematic search using the databases of Cochrane Library, EMBASE, Pubmed, WANGFANG, and China National Knowledge Infrastructure will be performed to identify studies in which patients with renal masses are assessed by ARFI. Two investigators will independently screen the literature and extract the data. Any discrepancies will be resolved via discussion with the senior author. Study quality will be assessed by the Quality Assessment of Diagnostic Accuracy Studies 2 tool, and pooled sensitivity and specificity of various ARFI findings for the diagnosis of renal masses will be determined. Summary receiver operating characteristic curve will be used to assess the overall performance of ARFI.

RESULTS

This study will evaluate the diagnostic value of ARFI for the diagnosis of renal masses through sensitivity, specificity, positive and negative likelihood ratio, and diagnostic odds ratio.

CONCLUSION

This study will summarize the most recent evidence that focusing on the diagnosis of ARFI for renal masses.

STUDY REGISTRATION

INPLASY202060105.

Diagnostic accuracy of contrast-enhanced ultrasound in the detection of small renal masses: A protocol of systematic review and meta-analysis

BACKGROUND

The small renal masses (SRMs) were defined that the diameter of renal masses measured by enhanced image was ≤4 cm. The diagnostic accuracy of contrast-enhanced ultrasound (CEUS) for SRMs is apparently variable among previous studies. Hence, this study will evaluate the diagnostic accuracy of CEUS in the identification of benign and malignant SRMs.

METHODS

A comprehensive search using the databases of Cochrane Library, Embase, PubMed, WANGFANG, and China National Knowledge Infrastructure will be carried out to identify studies in which patients with SRMs are assessed by CEUS. Two investigators will independently screen the literature and extract the data. Any discrepancies will be resolved via discussion with the senior author. Study quality will be assessed by the Quality Assessment of Diagnostic Accuracy Studies 2 tool, and pooled sensitivity and specificity of various CEUS findings for the diagnosis of SRMs will be determined. Summary receiver operating characteristic curve will be used to assess the overall performance of CEUS.

RESULTS

This study will evaluate the diagnostic accuracy of CEUS for the diagnosis of SRMs through sensitivity, specificity, positive and negative likelihood ratio, and diagnostic odds ratio.

CONCLUSION

This study will summarize the most recent evidence that focusing on the diagnosis of CEUS for SRMs.

STUDY REGISTRATION

INPLASY202060040.

A preoperative nomogram predicting the pseudocapsule status in localized renal cell carcinoma

Background

Tumor enucleation (TE) surgery for localized renal cell carcinoma (RCC) relies on a complete peritumoral pseudocapsule (PC). Study objective was to develop a preoperative model to predict PC status.

Methods

The prediction model was developed in a cohort that consisted of 170 patients with localized RCC, and data was gathered from 2010 to 2015. Multivariable logistic regression analysis and R were used to generate this prediction model. The statistical performance was assessed with respect to the calibration, discrimination, and clinical usefulness.

Results

The prediction model incorporated the systemic inflammatory markers [neutrophil-lymphocyte ratio (NLR); albumin-globulin ratio (AGR)], CT imaging features (tumor size and necrosis), and clinical risk factors (BMI). The model showed good discrimination, with a C-index of 0.85 (0.78–0.91), and good calibration (P=0.60). The sensitivity and specificity were 62% and 94% respectively. Decision curves and clinical impact curve demonstrated that the current model was clinically useful.

Conclusions

We constructed a model that incorporated both the systematic inflammatory markers and clinical risk factors. It can be conveniently used to preoperatively predict the individualized risk of PC invasion and identify the best candidates to receive TE surgery.

The independent indicators for differentiating renal cell carcinoma from renal angiomyolipoma by contrast-enhanced ultrasound

Background

The value of contrast-enhanced ultrasound (CEUS) in differentiating between renal cell carcinoma (RCC) and angiomyolipoma (AML) was analyzed. The purpose of this study was to identify the independent indicators of CEUS for predicting RCC.

Methods

A total of 172 renal tumors (150 RCCs, 22 AMLs) in 165 patients underwent conventional ultrasound (CUS) and CEUS examinations before radical or partial nephrectomy, and the features on CUS and CEUS were analyzed.

Results

There were significant differences in echogenicity, blood flow signals in color Doppler flow imaging (CDFI), peak intensity, homogeneity of enhancement, wash in, wash out, and perilesional rim-like enhancement between RCC and AML (P < 0.05 for all). Multivariate analysis indicated that perilesional rim-like enhancement (P = 0.035, odds ratio [OR] = 9.907, 95% confidence interval [CI]: 1.169–83.971) and fast wash out (P = 0.001, OR = 9.755, 95%[CI]: 2.497–38.115) were independent indicators for predicting RCC. The area under the receiver operating characteristic (ROC) curve (AUC) for perilesional rim-like enhancement was 0.838 (95% CI: 0.774–0.890) with 76.7% sensitivity and 90.9% specificity, while the AUC of fast wash out was 0.833 (95% CI:0.768–0.885) with 74.7% sensitivity and 81.8% specificity.

Conclusions

This study indicated that CEUS has value in differentiating RCC and AML. Present perilesional rim-like enhancement and fast wash out may be important indicators for predicting RCC.

MRI examination of resected malignant bone tumor can be an option for assessment of the osseous surgical margin

OBJECTIVE

Confirming the surgical osseous margin of a resected malignant bone tumor macroscopically before reconstruction with a prosthesis is ideal. However, making the cut-surface of the femur specimen during surgery is difficult because of the hard bone tissue. In order to resolve this problem, the possibility of intraoperative MRI was considered.

METHODS

MRI was performed at the surgical unit for five malignant femoral bone tumors that included two osteosarcomas and one undifferentiated high-grade sarcoma, and two metastatic tumors immediately after the tumor resection. The specimens were prepared in plastic containers with saline.

RESULTS

The osseous surgical margins were confirmed to be those planned pre-operatively in all cases without metal-induced artifacts. The T₁ weighted image (WI) was useful for evaluation of the osseous surgical margin, whereas the T₂WI was useful for confirmation of extraosseous soft-tissue.

CONCLUSION

The MRI was performed post-operatively as a preliminary evaluation of the technique. However, a limited sequence (i.e. coronal T₁WI) with short examination time could be performed during surgery for the sole purpose of assessing the osseous margin.

ADVANCES IN KNOWLEDGE

MRI examination of a resected malignant bone tumor specimen has not been reported, and can be an option for assessment of the osseous surgical margin.