Contrast-Enhanced Ultrasound Differentiation Between Low- and High- Grade Bladder Urothelial Carcinoma and Correlation With Tumor Microvessel Density

The Current Role of Contrast-Enhanced Ultrasound (CEUS) in the Diagnosis and Staging of Bladder Cancer: A Review of the Available Literature

Contrast-enhanced ultrasound (CEUS) is an advanced imaging technique that integrates conventional US with the intravenous injection of specific US contrast agents (UCAs), combining the non-invasiveness of US with the higher accuracy of contrast-enhanced imaging. In contrast with magnetic resonance imaging (MRI), computed tomography (CT) and cystoscopy, CEUS has few contraindications, and UCAs are non-nephrotoxic agents that can be safely used in patients with kidney failure. CEUS is a well-established method for the detection of liver lesions and for echocardiography, and its indications are expanding. The updated 2018 WFUMB-EFSUMB guidelines have added the urinary bladder under non-hepatic applications of CEUS. The technique is able to distinguish between benign tissue, such as clots or hematoma, and malignant lesions by perfusing the mass with contrast agent. Thanks to the different perfusion rates of the various layers of the bladder wall, CEUS is also able to predict tumor invasion depth and stage. Despite that, current urological guidelines do not include CEUS as a plausible imaging technique for bladder urothelial carcinoma. The main reason for this omission might be the presence of scarce randomized evidence and the absence of large validated series. In this review, we describe the rationale behind the use of CEUS in bladder cancer and the added value of this imaging technique in the detection and staging of bladder lesions. In addition, we researched the available literature on the topic and then described the results of randomized clinical trials and a meta-analysis investigating the accuracy of CEUS in bladder cancer diagnosis and staging. The reported studies show that CEUS is a highly accurate diagnostic and staging tool for BC, reaching levels of specificity and sensitivity in differentiating between Ta-T1, or low-grade BC, and T2, or high-grade BC, that are comparable to those shown by the reference standard methods. Nonetheless, several limitations were found and are highlighted in this review. The aim of this study is to further validate and promote the use of CEUS as a quick, economic and effective diagnostic tool for this high-impact disease.

Contrast-enhanced ultrasound (CEUS): applications from the kidneys to the bladder

Contrast-enhanced ultrasound (CEUS) is an advanced ultrasound (US) technique utilizing ultrasound contrast agents (UCAs) to provide detailed visualization of anatomic and vascular architecture, including the depiction of microcirculation. CEUS has been well-established in echocardiography and imaging of focal hepatic lesions and recent studies have also shown the utility of CEUS in non-hepatic applications like the urinary system. The updated guidelines by the European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB) from 2018 describe the use of CEUS for non-hepatic applications. CEUS' excellent safety profile and spatial resolution make it a superior modality to conventional US and is often comparable and even superior to CECT in some instances. In comparison to other cross-sectional imaging modalities such as CECT or MRI, CEUS offers a safe (by virtue of non-nephrotoxic US contrast agents), accurate, cost-efficient, readily available, and a quick means of evaluation of multiple pathologies of the urinary system. CEUS also has the potential to reduce the overall economic burden on patients requiring long-term follow-up due to its low cost as compared to CT or MRI techniques. This comprehensive review focuses on the applications of CEUS in evaluating the urinary system from the kidneys to the urinary bladder. CEUS can be utilized in the kidney to evaluate complex cystic lesions, indeterminate lesions, pseudotumors (vs solid renal tumors), renal infections, and renal ischemic disorders. Additionally, CEUS has also been utilized in evaluating renal transplants. In the urinary bladder, CEUS is extremely useful in differentiating a bladder hematoma and bladder cancer when conventional US techniques show equivocal results. Quantitative parameters of time-intensity curves (TICs) of CEUS examinations have also been studied to stage and grade bladder cancers. Although promising, further research is needed to definitively stage bladder cancers and classify them as muscle-invasive or non-muscle invasive using quantitative CEUS to guide appropriate intervention. CEUS has been very effective in the classification of cystic renal lesions, however, further research is needed in differentiating benign from malignant renal masses.

Application of contrast-enhanced ultrasound in diagnosis and grading of bladder urothelial carcinoma

PURPOSE

To explore the application of contrast-enhanced ultrasound (CEUS) for the diagnosis and grading of bladder urothelial carcinoma (BUC).

METHODS

The results of a two-dimensional ultrasound, color Doppler ultrasound and CEUS, were analyzed in 173 bladder lesion cases. The ultrasound and surgical pathology results were compared, and their diagnostic efficacy was analyzed.

RESULTS

There were statistically significant differences between BUC and benign lesions in terms of color blood flow distribution intensity and CEUS enhancement intensity (both P < 0.05). The area under the time-intensity curve (AUC), rising slope, and peak intensity of BUC were significantly higher than those of benign lesions (all P < 0.05). The H/T (height H / basal width T)value of 0.63 was the critical value for distinguishing high- and low-grade BUC, had a diagnostic sensitivity of 80.0% and a specificity of 60.0%.

CONCLUSION

The combination of CEUS and TIC can help improve the diagnostic accuracy of BUC. There is a statistically significant difference between high- and low-grade BUC in contrast enhancement intensity (P < 0.05); The decrease of H/T value indicates the possible increase of the BUC grade.

Multiparametric ultrasound of prostate: role in prostate cancer diagnosis

Recent advances in ultrasonography (US) technology established modalities, such as Doppler-US, HistoScanning, contrast-enhanced ultrasonography (CEUS), elastography, and micro-ultrasound. The early results of these US modalities have been promising, although there are limitations including the need for specialized equipment, inconsistent results, lack of standardizations, and external validation. In this review, we identified studies evaluating multiparametric ultrasonography (mpUS), the combination of multiple US modalities, for prostate cancer (PCa) diagnosis. In the past 5 years, a growing number of studies have shown that use of mpUS resulted in high PCa and clinically significant prostate cancer (CSPCa) detection performance using radical prostatectomy histology as the reference standard. Recent studies have demonstrated the role mpUS in improving detection of CSPCa and guidance for prostate biopsy and therapy. Furthermore, some aspects including lower costs, real-time imaging, applicability for some patients who have contraindication for magnetic resonance imaging (MRI) and availability in the office setting are clear advantages of mpUS. Interobserver agreement of mpUS was overall low; however, this limitation can be improved using standardized and objective evaluation systems such as the machine learning model. Whether mpUS outperforms MRI is unclear. Multicenter randomized controlled trials directly comparing mpUS and multiparametric MRI are warranted.

Contrast-Enhanced Ultrasound in the Bladder: Critical Features to Differentiate Occupied Lesions

Objective

To study the clinical diagnostic value of contrast-enhanced ultrasound (CEUS) in bladder occupied lesions.

Methods

38 cases of conventional-ultrasound-found bladder occupied lesions did color Doppler flow imaging (CDFI) and CEUS checks. By comparing the difference between two types of blood flow imaging technologies in displaying the flow of bladder occupied lesions and observing the perfusion modes of contrast agents to enter lesions, the perfusion characteristics of CEUS were analyzed. Finally, they were contrasted with the surgical pathology results.

Results

Of all the 38 cases, there were 51 bladder occupied lesions, including 43 bladder malignant tumors, 2 bladder inverted papillomas, and 6 glandular cystitis lesions. The blood flow display rate of bladder occupied lesions was 100% using CEUS. Apparently, it was higher than that of CDFI (62.7%), and the result of these showed a statistically significant difference (P < 0.05). Using CEUS, 46 malignant lesions and 5 glandular cystitis lesions were indicated, and the diagnostic accuracy rate was 86.3%.

Conclusion

CEUS can improve the blood flow display rate of bladder occupied lesions, and it can also observe the real-time blood flow of these lesions. It can help judge their nature and has a higher clinical value in differentiating the benign from the malignant.

Contrast-enhanced ultrasound for the preoperative assessment of laryngeal carcinoma: a preliminary study

BACKGROUND

Contrast-enhanced ultrasound (CEUS) is considered an attractive imaging technique to evaluate tumor microcirculation. However, the validity of CEUS for assessing laryngeal carcinoma is unclear.

PURPOSE

To compare the performance of CEUS with conventional US and contrast-enhanced computed tomography (CECT) in the diagnosis and preoperative T-staging of laryngeal carcinoma.

MATERIAL AND METHODS

Forty-one consecutive patients with laryngeal carcinoma underwent conventional high-frequency US, CEUS, and CECT before surgery. The CEUS characteristics of laryngeal carcinoma were recorded. The imaging findings of CEUS and conventional US were compared with CECT findings and the postoperative pathological examination.

RESULTS

CEUS showed hyperenhancement in 38 cases and isoenhancement in three cases. Homogeneous distribution of contrast agent was found in 20 cases and heterogeneous distribution in 21 cases, of which 16 cases showed local perfusion defects. In the enhanced phase, rapid entry was observed in 37 cases, synchronous entry was observed in two cases, and slow entry was observed in two cases. Rapid exit was observed in 25 cases and slow exit was observed in 16 cases. The pretherapeutic T-staging accuracy was not significantly different between conventional US, CEUS, and CECT (P ≥ 0.500). A high sensitivity and specificity were achieved by CEUS in the evaluation of involvement of thyroid cartilage.

CONCLUSION

Compared with conventional US and CECT, CEUS has a reliable initial T-staging accuracy and diagnostic properties for detecting laryngeal cartilage invasion.

Contrast-Enhanced Ultrasound Characteristics of Renal Pelvis Urothelial Carcinoma and Its Relationship with Microvessel Density

We studied the characteristics of contrast-enhanced ultrasound (CEUS) in renal pelvic urothelial carcinomas and explored its performance in assessing microvessel density (MVD) of tumor tissues. We retrospectively analyzed the characteristics of 125 cases, which were confirmed pathologically to be renal pelvic urothelial carcinomas using CEUS. We performed CEUS and found that most tumors presented with an enhanced mode of "slow-in (mean = 16.7 ± 2.6 s, range: 12-25 s), hypo-enhancement and fast-out (mean = 69.3 ± 16.2 s, range: 42-113 s)." However, the wash-in pattern, homogeneity and wash-out pattern observed with CEUS was not correlated with pT stage and grade (p > 0.05). But advanced-pT-stage and high-grade tumors had a higher peak enhancement than early-pT-stage and low-grade tumors (p < 0.01). Peak enhancement obtained with CEUS can be used to evaluate the pT stage and grade of renal pelvic urothelial carcinomas more effectively. The MVD of those tissues was observed using immunohistochemical staining of cluster of differentiation 34 (CD34). MVD in the advanced-pT-stage and high-grade groups was significantly higher than that in the early-pT-stage and low-grade groups (p < 0.01). As tumor pT stage and grade improved, CEUS peak enhancement intensity and MVD of tumors also exhibited an upward trend. CEUS peak enhancement intensity has the potential to determine MVD of renal pelvic urothelial carcinomas.

Shear Wave Elasticity Differentiation Between Low- and High-Grade Bladder Urothelial Carcinoma and Correlation With Collagen Fiber Content

OBJECTIVES

To investigate the differences in the shear wave elasticity and collagen fiber content between low- and high-grade bladder urothelial carcinoma and study the relationship between elasticity and the content of collagen fiber.

METHODS

A total of 66 patients with bladder tumors who were referred to our hospital underwent transrectal or transvaginal conventional ultrasound and shear wave elasticity examinations. After bladder urothelial carcinoma was pathologically confirmed, 34 cases of low-grade and 32 cases of high-grade carcinoma were enrolled. The specimens underwent Masson trichrome staining, and image-processing software was used to quantitatively analyze the area of collagen fiber.

RESULTS

Based on conventional ultrasound, the low- and high-grade groups were similar in the number, location, interior echoes, basal portion, size, and vascularity (P > .05); nevertheless, the difference in the surface condition (smooth or rough) was statistically significant (P = .03). The high-grade group had significantly higher maximum and mean elasticity than the low-grade group (P < .01). The percentage of the collagen fiber area in the high-grade group was significantly higher than that in the low-grade group (mean ± SD, 11.45% ± 1.66% versus 7.64% ± 0.70%; P = .01). There was a positive correlation between maximum elasticity, mean elasticity, and the percentage of the collagen fiber area (r = 0.75 and 0.52, respectively; P < .01).

CONCLUSIONS

Shear wave elasticity can be used to differentiate between low- and high-grade bladder urothelial carcinoma. The elasticity of lesions has a close correlation with the content of collagen fiber, which may have an important impact on tissue stiffness and the development of bladder cancer.

Use of Contrast Ultrasound for Renal Mass Evaluation

An introduction to the expanding modality of contrast-enhanced ultrasound is provided, along with basics on contrast agents and technique. The contrast ultrasound findings of multiple renal tumors are reviewed with examples, including clear cell renal cell carcinoma, papillary renal cell carcinoma, chromophobe renal cell carcinoma, other rare renal cell carcinoma subtypes, oncocytoma, upper tract urothelial carcinoma, lymphoma, and angiomyolipoma, followed also by brief discussions of renal infections and pseudolesions.

Application of contrast-enhanced ultrasonography for large cell neuroendocrine carcinoma in the urinary bladder: a case report

Background

Large cell neuroendocrine carcinoma (LCNEC) of the urinary bladder is an uncommon malignant bladder tumor, and the overall prognosis is poor. Contrast-enhanced ultrasound (CEUS) provides a new effective modality for tumor detection and diagnosis.

Case presentation

A 30-year-old man complained of repeated painless gross haematuria for half a month. Conventional ultrasound demonstrated a hypoechoic solitary lesion with hyperechoic margins measuring 3.4 × 3.1 cm in the anterior wall of the bladder. Superb microvascular imaging (SMI) showed a strong flow signal in the mass. CEUS revealed that the lesion was characterized by hyper-enhancement in the early phase and hypo-enhancement in the late phase. The entire bladder wall was disrupted by homogeneous hyper-enhanced tumor tissue on CEUS. Time-intensity curves (TICs) showed a rapid wash-in with a high maximum signal intensity (SI) and quick wash-out. Finally, partial cystectomy was performed and the pathological examination confirmed the diagnosis of LCNEC with invasion into the whole layer of the bladder wall.

Conclusion

This case suggested that CEUS was a valuable imaging method to detect and diagnose LCNEC in the bladder, and that CEUS can provide information related to the depth of wall invasion and the microvasculature.

Contrast-enhanced Ultrasound in evaluating of angiogenesis and tumor staging of nasopharyngeal carcinoma in nude mice

OBJECTIVE

To explore the use of Contrast-enhanced Ultrasound (CEUS) in evaluating angiogenesis in a xenograft nasopharyngeal carcinoma (NPC) model in nude mice and the evolution of CEUS parameters according to the growth of NPC.

METHODS

Nude mice were divided into three groups according to experiments conducted at various times from tumor implantation (8 mice/group; group A: 4 weeks from implantation; group B:6 weeks from implantation; group C:8 weeks from implantation). CNE-2 cells were transplanted in 24 nude mice and CEUS evaluations of the tumors were performed at 4, 6 or 8 weeks from implantation. CEUS parametric perfusion images and pathological findings were recorded. R version 3.4.4 software was used to analyze the CEUS parameters and pathological findings.

RESULTS

One-way anova analysis indicated statistically significant differences among the three groups with the parameters of peak intensity (PI) (p<0.001), area wash in (AWI) (p<0.001), area wash out (AWO) (p<0.001) and tumor volumes (p<0.001).Pearson correlation coefficient analysis indicated that microvessel density (MVD) was correlated with tumor volume (r = 0.644, p = 0.001), PI (r = 0.904, p<0.0001), AWI (r = 0.547, p = 0.008) and AWO (r = 0.744, P<0.0001). Tumor volume was correlated with MVD (r = 0.644, p = 0.001), PI (r = 0.625, p = 0.002), AWI (r = 0.528, p = 0.012) and AWO (r = 0.784, p<0.001). The percentage of necrosis in histological sections was correlated with the percentage of CEUS unperfused area (r = 0.446,p = 0.038). Spearman rank correlation coefficient analysis indicated that vascular endothelial growth factor (VEGF) was correlated with PI (r = 0.462, P = 0.032). Welch t test indicated PI, AWI and AWO parameters were significantly lower than that of kidneys (p<0.001, p = 0.009, p = 0.005).

CONCLUSIONS

The CEUS parameters PI, AWI and AWO indirectly reflect the MVD and the tumor volume in our model of subcutaneous transplanted NPC in nude mice, providing precious information on angiogenesis and tumor growth. VEGF may play a role in promoting angiogenesis of NPC.

Evaluation of upper tract urothelial carcinomas by contrast-enhanced ultrasound

AIM

To describe the findings and behaviour of contrast-enhanced ultrasound in the study of upper tract urothelial tumours and to assess its usefulness for diagnosis.

MATERIAL AND METHODS

We reviewed our hospital's database over a period of 45 months to identify patients diagnosed with upper tract urothelial carcinomas. We reviewed the findings on mode B-ultrasound, contrast-enhanced ultrasound (location and qualitative assessment of intensity and washout of enhancement), and made a comparison with other techniques (computed tomography or magnetic resonance), and with the surgical specimen.

RESULTS

We found 42 patients with a diagnosis of upper tract urothelial carcinoma confirmed with surgery over the period reviewed. Twenty-eight (67%) patients underwent contrast-enhanced ultrasound. Baseline ultrasound showed hydronephrosis with or without ureteral dilatation with echogenic content occupying the renal calyx (6), pelvis (10) or ureter (12). After injection of contrast, enhancement was noticed in 100% of the lesions, with similar intensity to the cortex in 23, and less in 5. Twenty-four lesions showed early washout, before the cortex, between 40 and 55seconds after the injection. The diagnosis was correct in 27 cases. Localisation coincided with the histological specimen in 28 cases, and 3 patients had additional distal carcinoma foci.

CONCLUSION

Contrast-enhanced ultrasound is a useful technique for diagnosing upper tract urothelial tumours that increases confidence in the diagnosis.

Contrast-Enhanced Transrectal Ultrasound in Focal Therapy for Prostate Cancer

PURPOSE OF REVIEW

Contrast-enhanced transrectal ultrasound (CeTRUS) is an emerging imaging technique in prostate cancer (PCa) diagnosis and treatment. We review the utility and implications of CeTRUS in PCa focal therapy (FT).

RECENT FINDINGS

CeTRUS utilizes intravenous injection of ultrasound-enhancing agents followed by high-resolution ultrasound to evaluate tissue microvasculature and differentiate between benign tissue and PCa, with the latter demonstrating increased enhancement. The potential utility of CeTRUS in FT for PCa extends to pre-, intra- and post-operative settings. CeTRUS may detect PCa, facilitate targeted biopsy and aid surgical planning prior to FT. During FT, the treated area can be visualized as a well-demarcated non-enhancing zone and continuous real-time assessment allows immediate re-treatment if necessary. Following FT, the changes on CeTRUS are immediate and consistent, thus facilitating repeat imaging for comparison during follow-up. Areas suspicious for recurrence may be detected and target-biopsied. Enhancement can be quantified using time-intensity curves allowing objective assessment and comparison. Based on encouraging early outcomes, CeTRUS may become an alternative imaging modality in prostate cancer FT. Further study with larger cohorts and longer follow-up are needed.

Lumbrokinase/paclitaxel nanoparticle complex: potential therapeutic applications in bladder cancer

Background

Lumbrokinase (LK) is an enzyme complex with antithrombotic, antioxidant, antitumor, and immunomodulatory effects. It has been extensively studied and used in clinical anti-tumor therapy. However, its half-life is short, its bioavailability is low, and its toxicity and side effects are great, which greatly limit its clinical application. Therefore, LK is often combined with other drugs (such as immune agents, hormones, or Chinese herbal medicine) to reduce its dosage and side effects and to improve its anti-tumor effects.

Methods and results

Here, we described an LK/paclitaxel (PTX) nanocarrier based on poly(ethylene glycol)-b-(poly(ethylenediamine l-glutamate)-g-poly(ε-benzyoxycarbonyl-l-lysine)-r-poly(l-lysine)) (PEG-b-(PELG-g-(PZLL-r-PLL))). In the present study, LK and PTX were loaded by electrostatic and/or hydrophobic effects under mild conditions, thereby increasing the half-life and bioavailability of the drugs via the sustained release and enhancement of tumor site enrichment by the LK/PTX/PEG-b-(PELG-g-(PZLL-r-PLL)) complex through passive targeting. In this study, using bladder cancer cells (J82 cells) and rat bladder cancer model as the object, the structure of the nanocarrier, the relationship between drugs composition and antitumor properties were systematically studied.

Conclusion

We propose that the block copolymer PEG-b-(PELG-g-(PZLL-r-PLL)) may function as a potent nanocarrier for augmenting anti-bladder cancer pharmacotherapy, with unprecedented clinical benefits.

A glance at imaging bladder cancer

Purpose

Early and accurate diagnosis of Bladder cancer (BCa) will contribute extensively to the management of the disease. The purpose of this review was to briefly describe the conventional imaging methods and other novel imaging modalities used for early detection of BCa and outline their pros and cons.

Methods

Literature search was performed on Pubmed, PMC, and Google scholar for the period of January 2014 to February 2018 and using such words as "bladder cancer, bladder tumor, bladder cancer detection, diagnosis and imaging".

Results

A total of 81 published papers were retrieved and are included in the review. For patients with hematuria and suspected of BCa, cystoscopy and CT are most commonly recommended. Ultrasonography, MRI, PET/CT using ¹⁸F-FDG or ¹¹C-choline and recently PET/MRI using ¹⁸F-FDG also play a prominent role in detection of BCa.

Conclusion

For initial diagnosis of BCa, cystoscopy is generally performed. However, cystoscopy can not accurately detect carcinoma insitu (CIS) and can not distinguish benign masses from malignant lesions. CT is used in two modes, CT and computed tomographic urography (CTU), both for dignosis and staging of BCa. However, they cannot differentiate T1 and T2 BCa. MRI is performed to diagnose invasive BCa and can differentiate muscle invasive bladder carcinoma (MIBC) from non-muscle invasive bladder carcinoma (NMIBC). However, CT and MRI have low sensitivity for nodal staging. For nodal staging PET/CT is preferred. PET/MRI provides better differentiation of normal and pathologic structures as compared with PET/CT. Nonetheless none of the approaches can address all issues related for the management of BCa. Novel imaging methods that target specific biomarkers, image BCa early and accurately, and stage the disease are warranted.

Contrast-enhanced ultrasound of small cell carcinoma in urinary bladder: a case report and review of literature

BACKGROUND

Small cell carcinoma of the urinary bladder (SCCB) is a relatively rare malignant bladder tumor, and few reports have investigated the microvasculature of SCCB imaged using contrast-enhanced ultrasound (CEUS).

CASE PRESENTATION

A 63-year-old female was admitted to our hospital after experiencing painless gross hematuria for one week. The gray-scale ultrasound (US) demonstrated a 4.8 × 3.4 × 3.6-cm³ hypoechoic mass in the apex of the urinary bladder with a wide base and an irregular surface; the mass did not move with changes in body position. Color Doppler flow imaging (CDFI) showed rich blood flow in the mass. CEUS with low mechanical index (MI) of 0.06 confirmed a highly enhanced 5.0 × 3.3 × 3.8 cm³ mass within the bladder at the apex wall. The time-intensity curves (TICs) showed a wash-in time of 10 s, a time to peak (TTP) of 33 s, a signal intensity (SI) of 62.7% and a wash-out time > 60 s. Finally, the transurethral resection of the bladder tumor (TURBT) was performed, and the pathological examination proved the diagnosis of SCCB.

CONCLUSION

CEUS can provide valuable information related to the rich microvasculature of SCCB, which may be helpful in its diagnosis.