Shear wave elastography for localization of prostate cancer lesions and assessment of elasticity thresholds: implications for targeted biopsies and active surveillance protocols

Clinical practice of the transrectal shear-wave elastography in benign prostatic hyperplasia

OBJECTIVE

To investigate the practical value of the transrectal two-dimensional shear-wave elastography (SWE) in benign prostatic hyperplasia (BPH).

METHODS

Consecutive male participants with and without BPH constituted the BPH and control group respectively were enrolled prospectively between March and December 2022. Transrectal conventional ultrasound and SWE examinations for the prostate were performed on these participants. Data of quantitative stiffness of the transitional zone (TZ) and peripheral zone (PZ) of prostate, volume of prostate (VP) and volume of TZ (VTZ) and prostate specific androgen (PSA), etc., were collected. Linear regression analyses were used to investigate the associations between quantitative stiffness data and other clinical parameters.

RESULTS

There were 200 participants evaluated, including 100 healthy participants and 100 BPH patients. For every one-year increment in age, it was correlated with 0.50 kPa increasement of TZ stiffness. VP and VTZ were correlated with TZ stiffness. Higher TZ stiffness was associated with higher free prostate specific antigen (PSA) and total PSA.

CONCLUSIONS

The prostate is stiffer and larger in BPH group compared to control group. Quantitative stiffness of the TZ was related with age, VP, VTZ and PSA.

Clinical Validation of Multiparametric Ultrasound for Detecting Clinically Significant Prostate Cancer Using Computer-Aided Diagnosis: A Direct Comparison with the Magnetic Resonance Imaging Pathway

We present the protocol for a study testing the hypothesis that a computer-aided diagnosis (CAD) system for three-dimensional multiparametric ultrasound (3D mpUS) is noninferior to magnetic resonance imaging (MRI) in guiding prostate biopsies for detection of clinically significant prostate cancer (csPCa). The prospective study has a fully paired design for assessment of diagnostic accuracy and is registered on ClinicalTrials.gov as NCT06281769. A total of 438 biopsy-naïve men scheduled for prostate MRI evaluation because of an abnormal digital rectal examination and/or elevated serum prostate-specific antigen will be included. All patients will undergo both MRI (multiparametric or biparametric) and 3D mpUS with CAD (PCaVision). Suspicious lesions will be independently identified using each imaging technique. MRI targeted biopsy (TBx) and/or PCaVision TBx will be performed if suspicious lesions are identified on imaging. When both PCaVision and MRI identify lesions in an individual patient, the TBx order for this patient will be randomized. Three TBx samples per lesion will be taken for a maximum of two lesions per modality. The primary objective is the detection rate for csPCa (International Society of Urological Pathology grade group [GG] ≥2) with the PCaVision versus the MRI TBx pathway. The noninferiority margin for the absolute difference in detection rates is set at a difference of 5%. Secondary outcomes are the proportion of men in whom TBx could have been safely omitted in each pathway. Additional diagnostic accuracy analyses will be performed for different definitions of PCa (GG ≥3; GG ≥2 with cribriform growth and/or intraductal carcinoma; and GG 1). The frequency of insufficient image quality for the two pathways will also be assessed. Lastly, we will determine the diagnostic performance for csPCa detection at various 3D mpUS image quality thresholds for PCaVision.

Can 3D Multiparametric Ultrasound Imaging Predict Prostate Biopsy Outcome?

OBJECTIVES

To assess the value of 3D multiparametric ultrasound imaging, combining hemodynamic and tissue stiffness quantifications by machine learning, for the prediction of prostate biopsy outcomes.

METHODS

After signing informed consent, 54 biopsy-naïve patients underwent a 3D dynamic contrast-enhanced ultrasound (DCE-US) recording, a multi-plane 2D shear-wave elastography (SWE) scan with manual sweeping from base to apex of the prostate, and received 12-core systematic biopsies (SBx). 3D maps of 18 hemodynamic parameters were extracted from the 3D DCE-US quantification and a 3D SWE elasticity map was reconstructed based on the multi-plane 2D SWE acquisitions. Subsequently, all the 3D maps were segmented and subdivided into 12 regions corresponding to the SBx locations. Per region, the set of 19 computed parameters was further extended by derivation of eight radiomic features per parameter. Based on this feature set, a multiparametric ultrasound approach was implemented using five different classifiers together with a sequential floating forward selection method and hyperparameter tuning. The classification accuracy with respect to the biopsy reference was assessed by a group-k-fold cross-validation procedure, and the performance was evaluated by the Area Under the Receiver Operating Characteristics Curve (AUC).

RESULTS

Of the 54 patients, 20 were found with clinically significant prostate cancer (csPCa) based on SBx. The 18 hemodynamic parameters showed mean AUC values varying from 0.63 to 0.75, and SWE elasticity showed an AUC of 0.66. The multiparametric approach using radiomic features derived from hemodynamic parameters only produced an AUC of 0.81, while the combination of hemodynamic and tissue-stiffness quantifications yielded a significantly improved AUC of 0.85 for csPCa detection (p-value < 0.05) using the Gradient Boosting classifier.

CONCLUSIONS

Our results suggest 3D multiparametric ultrasound imaging combining hemodynamic and tissue-stiffness features to represent a promising diagnostic tool for biopsy outcome prediction, aiding in csPCa localization.

Tissue-Mimicking Material Fabrication and Properties for Multiparametric Ultrasound Phantoms: A Systematic Review

Medical imaging has allowed for significant advancements in the field of ultrasound procedures over the years. However, each imaging modality exhibits distinct limitations that differently affect their accuracy. It is imperative to ensure the quality of each modality to identify and eliminate these limitations. To achieve this, a tissue-mimicking material (TMM) phantom is utilised for validation. This study aims to perform a systematic analysis of tissue-mimicking materials used for creating ultrasound phantoms. We reviewed 234 studies on the use of TMM phantoms in ultrasound that were published from 2013 to 2023 from two research databases. Our focus was on studies that discussed TMMs' properties and fabrication for ultrasound, elastography, and flow phantoms. The screening process led to the selection of 16 out of 234 studies to include in the analysis. The TMM ultrasound phantoms were categorised into three groups based on the solvent used; each group offers a broad range of physical properties. The water-based material most closely aligns with the properties of ultrasound. This study provides important information about the materials used for ultrasound phantoms. We also compared these materials to real human tissues and found that PVA matches most of the human tissues the best.

The Performance of Different Parametric Ultrasounds in Prostate Cancer Diagnosis: Correlation with Radical Prostatectomy Specimens

BACKGROUND

Prostate cancer is a prevalent cancer among men. Multiparametric ultrasound [mpUS] is a diagnostic instrument that uses various types of ultrasounds to diagnose it. This systematic review aims to evaluate the performance of different parametric ultrasounds in diagnosing prostate cancer by associating with radical prostatectomy specimens.

METHODOLOGY

A review was performed on various ultrasound parameters using five databases. Systematic review tools were utilized to eliminate duplicates and identify relevant results. Reviewers used the Quality Assessment of Diagnostic Accuracy Results [QUADAS-2] to evaluate the bias and applicability of the study outcomes.

RESULT

Between 2012 and 2023, eleven studies were conducted to evaluate the performance of the different ultrasound parametric procedures in detecting prostate cancer using grayscale TRUS, SWE, CEUS, and mpUS. The high sensitivity of these procedures was found at 55%, 88.6%, 81%, and 74%, respectively. The specificity of these procedures was found to be 93.4%, 97%, 88%, and 59%, respectively. This high sensitivity and specificity may be associated with the large lesion size. The studies revealed that the sensitivity of these procedures in diagnosing clinically significant prostate cancer was 55%, 73%, 70%, and 74%, respectively, while the specificity was 61%, 78.2%, 62%, and 59%, respectively.

CONCLUSIONS

The mpUS procedure provides high sensitivity and specificity in PCa detection, especially for clinically significant prostate cancer.

Case report: Prostatic malakoplakia: a rare disease that has a profile mimicking prostate cancer

Prostatic malakoplakia (PMP) is a rare inflammatory disease, and misdiagnosis on imaging is a major reason for unnecessary punctures; however, information on imaging is even rarer. Five patients with PMP between May 2022 and February 2023 were enrolled in this study to summarize the imaging manifestations. All patients underwent ultrasound (US)-guided prostate biopsy and were confirmed by pathology, and the presence of prostate cancer was also excluded by pathology. The five patients, with a median age of 71 years (range = 58-74 years), had a median total prostate-specific antigen (T-PSA) of 10.40 ng/mL (range = 1.74-63.42 ng/mL). In two patients, chest computed tomography showed pulmonary infections. All patients underwent magnetic resonance imaging (MRI). Of these patients, four had a Prostate Imaging-Reporting and Data System (PIRADS) score of 5, while one had a score of 4. The lesions were mostly distributed in the peripheral zone of the prostate and appeared as a high signal on T1-weighted imaging (T1WI) and a low signal on T2-weighted imaging (T2WI). In the US examination, four patients had abnormal prostate morphology, with an unsmooth envelope and non-uniform parenchymal echogenicity. Four patients had increased prostate volume. US showed a hypoechoic nodule with non-uniform internal echogenicity, and an abundant internal blood flow signal was detected by color Doppler US. PSA, MRI, and US were not specific for PMP in our study, but we found that a history of co-infection may be helpful in an accurate diagnosis and to avoid unnecessary biopsy.

Quantifying the Impact of Cancer on the Viscoelastic Properties of the Prostate Gland using a Quasi-Linear Viscoelastic Model

Pathological disorders can alter the mechanical properties of biological tissues, and studying such changes can help to better understand the disease progression. The prostate gland is no exception, as previous studies have shown that cancer can affect its mechanical properties. However, most of these studies have focused on the elastic properties of the tissue and have overlooked the impact of cancer on its viscous response. To address this gap, we used a quasi-linear viscoelastic model to investigate the impact of cancer on both the elastic and viscous characteristics of the prostate gland. By comparing the viscoelastic properties of segments influenced by cancer and those unaffected by cancer in 49 fresh prostates, removed within two hours after prostatectomy surgery, we were able to determine the influence of cancer grade and tumor volume on the tissue. Our findings suggest that tumor volume significantly affects both the elastic modulus and viscosity of the prostate (p-value less than 2%). Specifically, we showed that cancer increases Young's modulus and shear relaxation modulus by 20%. These results have implications for using mechanical properties of the prostate as a potential biomarker for cancer. However, developing an in vivo apparatus to measure these properties remains a challenge that needs to be addressed in future research. STATEMENT OF SIGNIFICANCE: This study is the first to explore how cancer impacts the mechanical properties of prostate tissues using a quasi-linear viscoelastic model. We examined 49 fresh prostate samples collected immediately after surgery and correlated their properties with cancer presence identified in pathology reports. Our results demonstrate a 20% change in the viscoelastic properties of the prostate due to cancer. We initially validated our approach using tissue-mimicking phantoms and then applied it to differentiate between cancerous and normal prostate tissues. These findings offer potential for early cancer detection by assessing these properties. However, conducting these tests in vivo remains a challenge for future research.

Multi-Frequency 3D Shear Wave Absolute Vibro-Elastography (S-WAVE) System for the Prostate

This article describes a novel system for quantitative and volumetric measurement of tissue elasticity in the prostate using simultaneous multi-frequency tissue excitation. Elasticity is computed by using a local frequency estimator to measure the three-dimensional local wavelengths of steady-state shear waves within the prostate gland. The shear wave is created using a mechanical voice coil shaker which transmits simultaneous multi-frequency vibrations transperineally. Radio frequency data is streamed directly from a BK Medical 8848 transrectal ultrasound transducer to an external computer where tissue displacement due to the excitation is measured using a speckle tracking algorithm. Bandpass sampling is used that eliminates the need for an ultra-fast frame rate to track the tissue motion and allows for accurate reconstruction at a sampling frequency that is below the Nyquist rate. A roll motor with computer control is used to rotate the transducer and obtain 3D data. Two commercially available phantoms were used to validate both the accuracy of the elasticity measurements as well as the functional feasibility of using the system for in vivo prostate imaging. The phantom measurements were compared with 3D Magnetic Resonance Elastography (MRE), where a high correlation of 96% was achieved. In addition, the system has been used in two separate clinical studies as a method for cancer identification. Qualitative and quantitative results of 11 patients from these clinical studies are presented here. Furthermore, an AUC of 0.87±0.12 was achieved for malignant vs. benign classification using a binary support vector machine classifier trained with data from the latest clinical study with leave one patient out cross-validation.

3-D Transducer Mounted Shear Wave Absolute Vibro-Elastography: Proof of Concept

Quantitative tissue stiffness characterization using ultrasound (US) has been shown to improve prostate cancer (PCa) detection in multiple studies. Shear wave absolute vibro-elastography (SWAVE) allows quantitative and volumetric assessment of tissue stiffness using external multifrequency excitation. This article presents a proof of concept of a first-of-a-kind 3-D hand-operated endorectal SWAVE system designed to be used during systematic prostate biopsy. The system is developed with a clinical US machine, requiring only an external exciter that can be mounted directly to the transducer. Subsector acquisition of radio frequency (RF) data allows imaging of shear waves with a high effective frame rate (up to 250 Hz). The system was characterized using eight different quality assurance phantoms. Due to the invasive nature of prostate imaging, at this early stage of development, validation of in vivo human tissue was instead carried out by intercostally scanning the livers of n = 7 healthy volunteers. The results are compared with 3-D magnetic resonance elastography (MRE) and an existing 3-D SWAVE system with a matrix array transducer (M-SWAVE). High correlations were found with MRE (99% in phantoms, 94% in liver data) and with M-SWAVE (99% in phantoms, 98% in liver data).

Comparative Assessment of Different Ultrasound Technologies in the Detection of Prostate Cancer: A Systematic Review and Meta-Analysis

The present study aimed to assess the diagnostic test accuracy of different ultrasound scanning technologies in the detection of prostate cancer. A systematic search was conducted using the Cochrane Guidelines for Screening and Diagnostic Tests. We performed a systematic search in the international databases PubMed, Medline, Ovid, Embase and Cochrane Library. Searches were designed to find all studies that evaluated Micro-US, mpUS, SWE and CEUS as the main detection modalities for prostate cancer. This study was registered with Research Registry of systematic review and meta-analysis. The QUADAS-2 tool was utilized to perform quality assessment and bias analysis. The literature search generated 1376 studies. Of these, 320 studies were screened for eligibility, with 1056 studies being excluded. Overall, 26 studies with a total of 6370 patients met the inclusion criteria. The pooled sensitivity for grayscale, CEUS, SWE, Micro-US and mpUS modalities were 0.66 (95% CI 0.54-0.73) 0.73 (95% CI 0.58-0.88), 0.82 (95% CI 0.75-0.90), 0.85 (95% CI 0.76-0.94) and 0.87 (95% CI 0.71-1.03), respectively. Moreover, the pooled specificity for grayscale, CEUS, SWE, Micro-US and mpUS modalities were 0.56 (95% CI 0.21-0.90), 0.78 (95% CI 0.67-0.88), 0.76 (95% CI 0.65-0.88), 0.43 (95% CI 0.28-0.59) and 0.68 (95% CI 0.54-0.81), respectively. In terms of sensitivity, substantial heterogeneity between studies was detected (I2 = 72%, p = 0.000 < 0.05). In relation to specificity, extreme heterogeneity was detected (I2 = 93%, p = 0.000 < 0.05). Some studies proved that advanced ultrasound modalities such as mpUS, Micro-US, shear-wave elastography, contrast enhanced and micro-ultrasound are promising methods for the detection of prostate cancer.

The Relationship of Testicular Sonoelastography with Gonadotropin Hormone Levels and Sperm Parameters

Background: Elastography is a non-invasive medical imaging technique that helps determine the stiffness of organs and other structures in our body. In this study, we investigated the effectiveness of elastography in the diagnosis of infertility. Aim

In this study, we aimed to examine the relationship between testicular elastography and hormonal parameters and sperm parameters.

Patients and Methods

The study included 136 patients, 272 testicles were examined, and the mean age of the study participants was 30.1 years. Testicular tissue stiffness was measured by scrotal ultrasonographic shear wave elastography. Gonadotropin and testosterone hormones were measured from blood samples. Spermiogram parameters were studied manually.

Results

The control group included 66 patients, and the varicocele group consisted of 70 patients. Testicular stiffness degrees of the control group were measured as 4.29 kPa for the right testis and 4.23 kPa for the left testis. The varicocele group was divided into grades 1, 2, and 3 according to physical examination. In group 1 (grade 1), the right testis was 4.07 ± 1.24 kPa and the left testis was 3.77 ± 0.98 kPa. In group 2 (grade 2), the right testis was 4.31 ± 1.40 kPa and the left testis was 3.98 ± 0.93 kPa. In group 3 (grade 3), the right testis was 4.73 ± 1.50 kPa and the left testis was 3.99 ± 1.68 kPa. Hormone and sperm parameters were not statistically significant when comparing the control and varicocele groups. There was no statistical significance between the testicular tissue stiffness degrees of the control and varicocele groups. Hormone and spermiogram findings were also similar in groups.

Conclusion

It is known that varicocele leads to histological tissue changes in the testes. These changes result in tissue softness and loss while affecting sperm parameters and testosterone levels in a negative way. Before varicocele surgery, there is a need for new imaging methods with more sensitivity that can detect tissue changes in the testes.

Comparison of Strain and Shear Wave Elastography in Prostate Cancer Detection

The aim of the study was to compare strain elastography with shear wave elastography in prostate cancer detection by comparing data gained during elastography with histological analysis after prostatectomy. Thirty patients with prostate cancer qualified for radical prostatectomy were enrolled into the study. All patients underwent transrectal strain elastography and shear wave elastography during pre-surgical evaluation. In each prostate, 36 regions were evaluated separately whether there was a suspicious prostate cancer lesion or not. Subsequently, the same regions were analyzed during histological analysis of the resected gland. Strain elastography and shear wave elastography (overall stiffness cutoff value = 35 kPa) in our study were characterized by overall sensitivities of 58.9% and 65.3% and specificities of 71.8% and 70.2%, respectively. Cutoff values specific to the zones in the shear wave elastography examination (peripheral zone: 35 kPa, transitional zone: 45 kPa) were characterized by an overall prostate cancer detection sensitivity and specificity of 63.4% and 73% respectively. Shear wave elastography examination revealed a higher sensitivity versus strain elastography, 63.4% versus 58.9% (p = 0.038, p < 0.05), and comparable specificity, 73.0% versus 71.8% (p = 0.547, p > 0.05), respectively. Sensitivity in prostate cancer detection for both methods is higher for larger lesions (except Gleason score 5 massive lesions in strain elastography). Controversially we observed a decrease in sensitivity for strain elastography in the detection of lesions with a large diameter and a Gleason score of 5 near the prostate capsule. Overall sensitivity in the diagnosis of prostate cancer is more significant for shear wave elastography versus strain elastography.

Clinical Trial Protocol: Developing an Image Classification Algorithm for Prostate Cancer Diagnosis on Three-dimensional Multiparametric Transrectal Ultrasound

Introduction and hypothesis

The tendency toward population-based screening programs for prostate cancer (PCa) is expected to increase demand for prebiopsy imaging. This study hypothesizes that a machine learning image classification algorithm for three-dimensional multiparametric transrectal prostate ultrasound (3D mpUS) can detect PCa accurately.

Design

This is a phase 2 prospective multicenter diagnostic accuracy study. A total of 715 patients will be included in a period of approximately 2 yr. Patients are eligible in case of suspected PCa for which prostate biopsy is indicated or in case of biopsy-proven PCa for which radical prostatectomy (RP) will be performed. Exclusion criteria are prior treatment for PCa or contraindications for ultrasound contrast agents (UCAs).

Protocol overview

Study participants will undergo 3D mpUS, consisting of 3D grayscale, 4D contrast-enhanced ultrasound, and 3D shear wave elastography (SWE). Whole-mount RP histopathology will provide the ground truth to train the image classification algorithm. Patients included prior to prostate biopsy will be used for subsequent preliminary validation. There is a small, anticipated risk for participants associated with the administration of a UCA. Informed consent has to be given prior to study participation, and (serious) adverse events will be reported.

Statistical analysis

The primary outcome will be the diagnostic performance of the algorithm for detecting clinically significant PCa (csPCa) on a per-voxel and a per-microregion level. Diagnostic performance will be reported as the area under the receiver operating characteristic curve. Clinically significant PCa is defined as the International Society of Urological grade group ≥2. Full-mount RP histopathology will be used as the reference standard. Secondary outcomes will be sensitivity, specificity, negative predictive value, and positive predictive value for csPCa on a per-patient level, evaluated in patients included prior to prostate biopsy, using biopsy results as the reference standard. A further analysis will be performed on the ability of the algorithm to differentiate between low-, intermediate-, and high-risk tumors.

Discussion and summary

This study aims to develop an ultrasound-based imaging modality for PCa detection. Subsequent head-to-head validation trials with magnetic resonance imaging have to be performed in order to determine its role in clinical practice for risk stratification in patients suspected for PCa.

Stiffer-Matrix-Induced PGC-1α Upregulation Enhanced Mitochondrial Biogenesis and Oxidative Stress Resistance in Non-small Cell Lung Cancer

Introduction

Metabolic strategies in different microenvironments can affect cancer metabolic adaptation, ultimately influencing the therapeutic response. Understanding the metabolic alterations of cancer cells in different microenvironments is critical for therapeutic success.

Methods

In this study, we cultured non-small cell lung cancer cells in three different microenvironments (two-dimensional (2D) plates, soft elastic three-dimensional (3D) porous 2 wt% scaffolds, and stiff elastic 3D porous 4 wt% scaffolds) to investigate the effects of different matrix elasticity as well as 2D and 3D culture settings on the metabolic adaptation of cancer cells.

Results

The results revealed that PGC-1α expression is sensitive to the elasticity of the 3D scaffold. PGC-1α expression was markedly increased in cancer cells cultured in stiff elastic 3D porous 4 wt% scaffolds compared with cells cultured in soft elastic 3D porous 2 wt% scaffolds or 2D plates, enhancing mitochondrial biogenesis and oxidative stress resistance of non-small cell lung cancer through increased reactive oxygen species (ROS) detoxification capacity. However, phosphofructokinase-1 (PFK-1) expression, a key rate-limiting enzyme in glycolysis, did not change significantly in the three microenvironments, indicating that microenvironments may not affect the early stage of glycolysis. Conversely, monocarboxylate transporter 1 (MCT1) expression in 3D culture was significantly reduced compared to 2D culture but without significant difference between soft and stiff scaffolds, indicating that MCT1 expression is more sensitive to the shape of the different cultures of 2D and 3D microenvironment surrounding cells but is unaffected by the scaffold elasticity.

Conclusions

Together, these results demonstrate that differences in the microenvironment of cancer cells profoundly impact their metabolic response.

Application of Multiple Ultrasonic Techniques in the Diagnosis of Prostate Cancer

Methods for diagnosing prostate cancer (PCa) are developing in the direction of imaging. Advanced ultrasound examination modes include micro-Doppler, computerized-transrectal ultrasound, elastography, contrast-enhanced ultrasound and microultrasound. When two or more of these modes are used in PCa diagnosis, the combined technique is called multiparameter ultrasound (mp-US). Mp-US provides complementary information to multiparameter magnetic resonance imaging (mp-MRI) for diagnosing PCa. At present, no study has attempted to combine the characteristics of different ultrasound modes with advanced classification systems similar to the PIRADS system in mpMRI for the diagnosis of PCa. As an imaging method, mp-US has great potential in the diagnosis of PCa.

Alternatives for MRI in Prostate Cancer Diagnostics-Review of Current Ultrasound-Based Techniques

The purpose of this review is to present the current role of ultrasound-based techniques in the diagnostic pathway of prostate cancer (PCa). With overdiagnosis and overtreatment of a clinically insignificant PCa over the past years, multiparametric magnetic resonance imaging (mpMRI) started to be recommended for every patient suspected of PCa before performing a biopsy. It enabled targeted sampling of the suspicious prostate regions, improving the accuracy of the traditional systematic biopsy. However, mpMRI is associated with high costs, relatively low availability, long and separate procedure, or exposure to the contrast agent. The novel ultrasound modalities, such as shear wave elastography (SWE), contrast-enhanced ultrasound (CEUS), or high frequency micro-ultrasound (MicroUS), may be capable of maintaining the performance of mpMRI without its limitations. Moreover, the real-time lesion visualization during biopsy would significantly simplify the diagnostic process. Another value of these new techniques is the ability to enhance the performance of mpMRI by creating the image fusion of multiple modalities. Such models might be further analyzed by artificial intelligence to mark the regions of interest for investigators and help to decide about the biopsy indications. The dynamic development and promising results of new ultrasound-based techniques should encourage researchers to thoroughly study their utilization in prostate imaging.

The challenge of prostate biopsy guidance in the era of mpMRI detected lesion: ultrasound-guided versus in-bore biopsy

The current recommendation in patients with a clinical suspicion for prostate cancer is to perform systematic biopsies extended with targeted biopsies, depending on mpMRI results. Following a positive mpMRI [i.e. Prostate Imaging Reporting and Data System (PI-RADS) ≥3], three targeted biopsy approaches can be performed: visual registration of the MRI images with real-time ultrasound imaging; software-assisted fusion of the MRI images and real-time ultrasound images, and in-bore biopsy within the MR scanner. This collaborative review discusses the advantages and disadvantages of each targeting approach and elaborates on future developments. Cancer detection rates seem to mostly depend on practitioner experience and selection criteria (biopsy naïve, previous negative biopsy, prostate-specific antigen (PSA) selection criteria, presence of a lesion on MRI), and to a lesser extent dependent on biopsy technique. There is no clear consensus on the optimal targeting approach. The choice of technique depends on local experience and availability of equipment, individual patient characteristics, and onsite cost-benefit analysis. Innovations in imaging techniques and software-based algorithms may lead to further improvements in this field.

The role of diagnostic ultrasound imaging for patients with known prostate cancer within an active surveillance pathway: A systematic review

BACKGROUND

The use of multiparametric magnetic resonance imaging (mpMRI) within active surveillance of prostate cancer programmes is identified by the UK National Institute for Health and Care Excellence (NICE guideline NG 131 2019) as having a role for monitoring disease. The widespread demands on mpMRI capacity may limit its use in surveillance. It is therefore timely to review the options that modern ultrasound imaging present to this cohort of patients in the monitoring of prostate cancer.

METHODS

Between April and September 2020, 10 databases were searched to recruit studies for the review. Three reviewers evaluated the publications for inclusion. Characteristics including the inclusion criteria for the study cohort, how disease was determined, identification of disease progression, and the modality and mode of imaging used were reviewed. Given the paucity of full text articles, a meta-analysis was not possible. A narrative review was undertaken.

RESULTS

In total, 12 studies, utilising the range of ultrasound parameters of B-mode, micro-ultrasound, colour Doppler, contrast ultrasound and elastography were included. The review demonstrated that micro-ultrasound offers promise as an imaging tool comparable with mpMRI. However, this is an emerging technology with limited availability. Analysis of the data further demonstrated that by combining the diagnostic features provided by multiple modes reviewed, ultrasound has a role in the diagnostic imaging of patients on active surveillance.

CONCLUSION

Providing a multiparametric approach is utilised, stable ultrasound findings may allow for increased intervals between biopsy for men on surveillance. The advent of micro-US offers promise as an imaging modality within an active surveillance pathway but requires further verification.

Prostate Cancer Gleason Score From Biopsy to Radical Surgery: Can Ultrasound Shear Wave Elastography and Multiparametric Magnetic Resonance Imaging Narrow the Gap?

Objectives

To investigate the impact of ultrasound shear wave elastography (USWE) and multiparametric magnetic resonance imaging (mpMRI) in predicting a change in biopsy-assigned Gleason Score (GS) after radical surgery for localised prostate cancer (PCa).

Method

A total of 212 men opting for laparoscopic radical prostatectomy (LRP) between September 2013 and June 2017 were recruited into this study. All the participants had 12-core transrectal ultrasound (TRUS) biopsies and imaging using USWE and mpMRI before radical surgery. The predictive accuracy for imaging modalities was assessed in relation to upgrading and downgrading of PCa GS between the biopsies and radical prostatectomy using Student's t-test and multivariable logistic regression analyses. A decision analysis curve was constructed assessing the impact of nomogram on clinical situations using different thresholds of upgrading probabilities.

Results

Most GS 6 diseases on biopsies were upgraded on radical surgery (37/42, 88.1%). Major downgrading was seen in GS 8 category of disease (14/35; 37.1%), whereas no alteration was observed in GS 7 on biopsies in most men (55/75; 73.3%). In univariate analysis, higher preoperative prostate-specific antigen (PSA) (p = 0.001), higher prostate-specific antigen density (PSAD) (p = 0.002), stiffer USWE lesions (p = 0.009), and higher prostate imaging-reporting and data system (PIRADS) (p = 0.002) on mpMRI were significant predictors of upgrading. In multivariate logistic regression analyses, only PSA (p = 0.016) and USWE-measured tissue stiffness (p = 0.029) showed statistical significance in predicting upgrading.

Conclusions

Measurement of tissue stiffness using USWE in clinically localised PCa can predict upgrading of GS and has the potential to improve patient management options.

Characterisation of Collagen Re-Modelling in Localised Prostate Cancer Using Second-Generation Harmonic Imaging and Transrectal Ultrasound Shear Wave Elastography

Prostate cancer has a poor prognosis and high mortality rate due to metastases. Extracellular matrix (ECM) re-modelling and stroma composition have been linked to cancer progression, including key components of cell migration, tumour metastasis, and tissue modulus. Moreover, collagens are one of the most significant components of the extracellular matrix and have been ascribed to many aspects of neoplastic transformation. This study characterises collagen re-modelling around localised prostate cancer using the second harmonic generation of collagen (SHG), genotyping and ultrasound shear wave elastography (USWE) measured modulus in men with clinically localised prostate cancer. Tempo-sequence assay for gene expression of COL1A1 and COL3A1 was used to confirm the expression of collagen. Second-harmonic generation imaging and genotyping of ECM around prostate cancer showed changes in content, orientation, and type of collagen according to Gleason grades (cancer aggressivity), and this correlated with the tissue modulus measured by USWE in kilopascals. Furthermore, there were clear differences between collagen orientation and type around normal and cancer tissues.

Prostate Cancer Ultrasound: Is Still a Valid Tool?

Purpose of Review

The main purpose of this paper review is to highlight the latest ultrasound (US) imaging technologies of the prostate gland, an organ increasingly at the center of attention in the field of oncological diseases of the male sex, which needs a 360° evaluation in order to obtain tailored therapeutic planning. Specialist urological evaluation is designated for this purpose, together with integrated prostate imaging which currently tends to focus more and more on the use of US imaging and its state-of-the-art technologies in iconographic diagnosis, biopsy and, sometimes, treatment of prostatic cancer.

Recent Findings

In particular, the main tools to which reference is made, represent a valid aid to basic US technologies already widely known and diffused, like the grayscale US or the Doppler US, for a "multiparametric" evaluation of the prostate cancer. The concept of multiparametricity is explained by the integration of prostate imaging obtained both with the US evaluation of the gland before and after administration of contrast medium, with the elaboration of parametric maps of quantitative measurement of the enhancement, and with elastography that provides information about the tissue consistency, a finding that strongly relates with the degree of cellularity and with the tumor grading.

Summary

Prostate cancer screening consists of dosing serum levels of prostate-specific antigen (PSA) and performing digit-rectal examination (DRE), more or less associated with transrectal prostate ultrasound (TRUS). However, although these are the most common techniques in clinical practice, they have numerous limitations and make the diagnosis of prostate cancer often challenging. The purpose of mp-US is to enrich the clinical-laboratory data and, above all, the standard US imaging with further details to strengthen the suspicion of malignancy of a prostate tumor, which needs to be addressed to diagnostic deepening with biopsy. This review article provides a summary of the current evidence on mp-US imaging in the evaluation of a clinically significant prostate cancer, comparing the data obtained to the imaging of mp-MRI, the reference tool both in diagnosis and staging.

Transthoracic ultrasound shear wave elastography for the study of subpleural lung lesions

PURPOSE

The aim of this study was to assess whether new-generation shear wave elastography (SWE) is suitable for the characterization of lung subpleural lesions.

METHODS

In total, 190 consecutive patients with subpleural lung lesions received ultrasonography and SWE. Patients with suspected malignancy underwent ultrasound-guided transthoracic needle biopsy. Final diagnoses were made on the basis of patients' clinical course, microbiological studies, and histological results. SWE was also performed in 25 healthy volunteers.

RESULTS

We found no statistically significant differences in stiffness between lung carcinomas, lung metastases, and pneumonia (P=0.296) or between different histological types of lung cancer (P=0.393). Necrosis was associated with reduced stiffness in pneumonia. Excluding necrotic lesions, pneumonia showed higher stiffness than lung carcinomas (2.95±0.68 m/s vs. 2.60±0.54 m/s, P=0.006). Chronic pneumonia showed increased stiffness (3.03±0.63 m/s), probably due to the presence of fibrotic tissue on histology. Pleural effusion was associated with a statistically significant reduction in stiffness, both in lung carcinomas (P=0.004) and lung metastases (P=0.002). The presence of air in healthy lung tissue may lead to incorrect speed estimates due to shear wave reflection (very high values, 14.64±2.19 m/s).

CONCLUSION

Transthoracic SWE could not distinguish lung malignancy from pneumonia, or between different histological types of lung carcinomas. In particular, SWE seems unable to resolve the clinical dilemma of chronic subpleural consolidations.

Evaluation of the effect of 3D porous Chitosan-alginate scaffold stiffness on breast cancer proliferation and migration

Breast cancer (BCa) is one of the most common cancers for women and metastatic BCa causes the majority of deaths. The extracellular matrix (ECM) stiffens during cancer progression and provides biophysical signals to modulate proliferation, morphology, and metastasis. Cells utilize mechanotransduction and integrins to sense and respond to ECM stiffness. Chitosan-alginate (CA) scaffolds have been used for 3D culture, but lack integrin binding ligands, resulting in round cell morphology and limited cell-material interaction. In this study, 2, 4, and 6 wt% CA scaffolds were produced to mimic the stages of BCa progression and evaluate the BCa response to CA scaffold stiffness. All three CA scaffold compositions highly porous with interconnected pores and scaffold stiffness increased with increasing polymer concentration. MDA-MB-231 (231) cells were cultured in CA scaffolds and 2D cultures for 7 d. All CA scaffold cultures had similar cell numbers at 7 d and the 231 cells formed clusters that increased in size during the culture. The 2 wt% CA had the largest clusters throughout the 7 d culture compared with the 4 and 6 wt% CA. The 231 cell migration was evaluated on 2D surfaces after 7 d culture. The 6 wt% CA cultured cells had the greatest migration speed, followed by 4 wt% CA, 2D cultures, and 2 wt% CA. These results suggest that 231 cells sensed the stiffness of CA scaffolds without the presence of focal adhesions. This indicates that a non-integrin-based mechanism may explain the observed mechanotransduction response.

THE ROLE OF ULTRASOUND ELASTOGRAPHY IN THE DIAGNOSIS OF PATHOLOGIC CONDITIONS OF TESTICLES AND SCROTUM

Several years ago, elastography emerged as a potentially very useful ultrasound technique that is currently used in diagnostic workup of the breast, liver and some other organ systems, whereas for other ones it is still mainly in the phase of research. The aim of the study was to compare elasticity index (EI) of testicles using strain elastography in healthy subjects and those with pathologic changes of testicles/scrotum. A total of 117 patients were included in the study. Measurements were performed on a Logiq E9 ultrasound system using strain elastography. In healthy subjects, the mean EI value was 1.34±0.35 for right testis and 1.49±0.47 for left testis. Increased mean EI values were found in the following six conditions: patients with varicocele, infertile patients, solitary testis after orchidectomy of the other testicle because of tumor, patients with testicular tumors, patients after orchidopexy of undescended testicle, and patients with congenitally smaller testicle. There is a paucity of literature data on the use of elastography in testes, as well as on normal elastography values in testicular tissue. Strain elastography was demonstrated to be a valuable method to acquire additional information in patients with pathologic changes in testicles/scrotum. These data provide reference values for further research in a larger sample of subjects.

Characterisation of Prostate Lesions Using Transrectal Shear Wave Elastography (SWE) Ultrasound Imaging: A Systematic Review

BACKGROUND

ultrasound-based shear wave elastography (SWE) can non-invasively assess prostate tissue stiffness. This systematic review aims to evaluate SWE for the detection of prostate cancer (PCa) and compare diagnostic estimates between studies reporting the detection of all PCa and clinically significant PCa (csPCa).

METHODS

a literature search was performed using the MEDLINE, EMBASE, Cochrane Library, ClinicalTrials.gov, and CINAHL databases. Studies evaluating SWE for the detection of PCa using histopathology as reference standard were included.

RESULTS

16 studies including 2277 patients were included for review. Nine studies evaluated SWE for the detection of PCa using systematic biopsy as a reference standard at the per-sample level, with a pooled sensitivity and specificity of 0.85 (95% CI = 0.74-0.92) and 0.85 (95% CI = 0.75-0.91), respectively. Five studies evaluated SWE for the detection of PCa using histopathology of radical prostatectomy (RP) specimens as the reference standard, with a pooled sensitivity and specificity of 0.71 (95% CI = 0.55-0.83) and 0.74 (95% CI = 0.42-0.92), respectively. Sub-group analysis revealed a higher pooled sensitivity (0.77 vs. 0.62) and specificity (0.84 vs. 0.53) for detection of csPCa compared to all PCa among studies using RP specimens as the reference standard.

CONCLUSION

SWE is an attractive imaging modality for the detection of PCa.

Targeting Mechanotransduction in Osteosarcoma: A Comparative Oncology Perspective

Mechanotransduction is the process in which cells can convert extracellular mechanical stimuli into biochemical changes within a cell. While this a normal process for physiological development and function in many organ systems, tumour cells can exploit this process to promote tumour progression. Here we summarise the current state of knowledge of mechanotransduction in osteosarcoma (OSA), the most common primary bone tumour, referencing both human and canine models and other similar mesenchymal malignancies (e.g., Ewing sarcoma). Specifically, we discuss the mechanical properties of OSA cells, the pathways that these cells utilise to respond to external mechanical cues, and mechanotransduction-targeting strategies tested in OSA so far. We point out gaps in the literature and propose avenues to address them. Understanding how the physical microenvironment influences cell signalling and behaviour will lead to the improved design of strategies to target the mechanical vulnerabilities of OSA cells.

Elastography Targeted Prostate Biopsy in Patients under Active Surveillance

OBJECTIVE

The aim of this study was to examine elastography-based prostate biopsy in prostate cancer (PCa) patients under active surveillance.

PATIENTS AND METHODS

We relied on PCa patients who opted for active surveillance and underwent elastography targeted and systematic follow-up biopsy at the Braunschweig Prostate Cancer Center between October 2009 and February 2015. Each prostate sextant was considered as an individual case. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy (ACC) for elastography to predict follow-up biopsy results were analyzed, respectively, and 95 % confidence intervals (CIs) were carried out by using 2000 bootstrapping sample analyses.

RESULTS

Overall, 50 men and 300 sextants were identified. Overall, 27 (54%) men and 66 (22%) sextants harbored PCa at follow-up biopsy. Sensitivity, specificity, PPV, NPV, and ACC for elastography to predict follow-up biopsy results were: 19.7 (95% CI: 11.9-27.3), 86.8 (95% CI: 82.7-90.3), 29.6 (95% CI: 14.6-46.0), 79.3 (95% CI: 71.6-86.5), and 72.0% (95% CI: 65.7-78.3), respectively.

CONCLUSIONS

We recorded limited reliability of elastography-based prediction of follow-up biopsy results in active surveillance patients. Based on our analyses, we can neither recommend to rely exclusively on elastography-based targeted biopsies nor to delay or to omit follow-up biopsies based on elastography results during active surveillance.

3D porous chitosan-chondroitin sulfate scaffolds promote epithelial to mesenchymal transition in prostate cancer cells

Prostate cancer (PCa) is a common cancer in men that is curable prior to metastasis, when its prognosis worsens. Chondroitin sulfate (CS) is found in the extracellular matrix of normal prostate tissue and PCa, with greater content in metastatic PCa. Biomaterial scaffolds containing CS have yet to be evaluated for tumor microenvironment applications. Three-dimensional porous chitosan-CS (C-CS) scaffolds were developed and evaluated for PCa culture. Three C-CS scaffold compositions were prepared with 4 w/v% chitosan and 0.1, 0.5, and 1.0 w/v% CS and named 4-0.1, 4-0.5, and 4-1, respectively. The C-CS scaffolds had 90-95% porosity, average pore sizes between 143 and 166 μm, and no significant difference in scaffold stiffness. PC-3 and 22Rv1 PCa cells were cultured on the C-CS scaffolds to study the effect of CS on PCa growth and epithelial to mesenchymal transition (EMT). All C-CS scaffold compositions supported PCa growth and the 4-1 scaffolds had the greatest cell numbers for both PC-3 and 22Rv1. The C-CS scaffolds promoted upregulated EMT marker expression compared to 2D cultures with the greatest EMT marker expression in 4-1 scaffolds. Increasing CS concentration promoted upregulated vimentin expression in PC-3 cultures and N-cadherin and MMP-2 expression in 22Rv1 cultures. C-CS scaffolds promoted docetaxel drug resistance in PC-3 and 22Rv1 cultures and the 4-1 scaffold cultures had the greatest drug resistance. These results indicate that C-CS scaffolds are a promising in vitro platform for PCa.

Detection of clinically significant prostate cancer in biopsy-naïve men: direct comparison of systematic biopsy, multiparametric MRI- and contrast-ultrasound-dispersion imaging-targeted biopsy

OBJECTIVES

To compare and evaluate a multiparametric magnetic resonance imaging (mpMRI)-targeted biopsy (TBx) strategy, contrast-ultrasound-dispersion imaging (CUDI)-TBx strategy and systematic biopsy (SBx) strategy for the detection of clinically significant prostate cancer (csPCa) in biopsy-naïve men.

PATIENTS AND METHODS

A prospective, single-centre paired diagnostic study included 150 biopsy-naïve men, from November 2015 to November 2018. All men underwent pre-biopsy mpMRI and CUDI followed by a 12-core SBx taken by an operator blinded from the imaging results. Men with suspicious lesions on mpMRI and/or CUDI also underwent MRI-TRUS fusion-TBx and/or cognitive CUDI-TBx after SBx by a second operator. A non-inferiority analysis of the mpMRI- and CUDI-TBx strategies in comparison with SBx for International Society of Urological Pathology Grade Group [GG] ≥2 PCa in any core with a non-inferiority margin of 1 percentage point was performed. Additional analyses for GG ≥2 PCa with cribriform growth pattern and/or intraductal carcinoma (CR/IDC), and GG ≥3 PCa were performed. Differences in detection rates were tested using McNemar's test with adjusted Wald confidence intervals.

RESULTS

After enrolment of 150 men, an interim analysis was performed. Both the mpMRI- and CUDI-TBx strategies were inferior to SBx for GG ≥2 PCa detection and the study was stopped. SBx found significantly more GG ≥2 PCa: 39% (56/142), as compared with 29% (41/142) and 28% (40/142) for mpMRI-TBx and CUDI-TBx, respectively (P < 0.05). SBx found significantly more GG = 1 PCa: 14% (20/142) compared to 1% (two of 142) and 3% (four of 142) with mpMRI-TBx and CUDI-TBx, respectively (P < 0.05). Detection of GG ≥2 PCa with CR/IDC and GG ≥3 PCa did not differ significantly between the strategies. The mpMRI- and CUDI-TBx strategies were comparable in detection but the mpMRI-TBx strategy had less false-positive findings (18% vs 53%).

CONCLUSIONS

In our study in biopsy-naïve men, the mpMRI- and CUDI-TBx strategies had comparable PCa detection rates, but the mpMRI-TBX strategy had the least false-positive findings. Both strategies were inferior to SBx for the detection of GG ≥2 PCa, despite reduced detection of insignificant GG = 1 PCa. Both strategies did not significantly differ from SBx for the detection of GG ≥2 PCa with CR/IDC and GG ≥3 PCa.

Why Are Viscosity and Nonlinearity Bound to Make an Impact in Clinical Elastographic Diagnosis?

The adoption of multiscale approaches by the biomechanical community has caused a major improvement in quality in the mechanical characterization of soft tissues. The recent developments in elastography techniques are enabling in vivo and non-invasive quantification of tissues' mechanical properties. Elastic changes in a tissue are associated with a broad spectrum of pathologies, which stems from the tissue microstructure, histology and biochemistry. This knowledge is combined with research evidence to provide a powerful diagnostic range of highly prevalent pathologies, from birth and labor disorders (prematurity, induction failures, etc.), to solid tumors (e.g., prostate, cervix, breast, melanoma) and liver fibrosis, just to name a few. This review aims to elucidate the potential of viscous and nonlinear elastic parameters as conceivable diagnostic mechanical biomarkers. First, by providing an insight into the classic role of soft tissue microstructure in linear elasticity; secondly, by understanding how viscosity and nonlinearity could enhance the current diagnosis in elastography; and finally, by compounding preliminary investigations of those elastography parameters within different technologies. In conclusion, evidence of the diagnostic capability of elastic parameters beyond linear stiffness is gaining momentum as a result of the technological and imaging developments in the field of biomechanics.

Diagnostic Value of Transrectal Shear Wave Elastography for Prostate Cancer Detection in Peripheral Zone: Comparison with Magnetic Resonance Imaging

Objective: To assess the diagnostic value of transrectal shear wave elastography (SWE) for detecting prostate cancer (PCa) in peripheral zone and compare it with magnetic resonance imaging (MRI). Materials and Methods: Two hundred twenty-one patients suspected of PCa were enrolled, in which 172 patients of them underwent both SWE and MRI. Elastic value was measured in the area prepared for systematic biopsy and suspicious lesion detected on B-mode or SWE, histopathological result was compared for each biopsy. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were derived by obtaining optimal threshold from receiver operating characteristic (ROC) curve. The correlation between the stiffness of PCa and Gleason scores, prognostic grades, and percentage of cancer in biopsy were evaluated by Spearman rank correlation. Multivariate logistic regression analysis was performed to determine predictors for diagnosing PCa. The diagnostic capacity of MRI and SWE for detecting PCa and clinically significant PCa in the peripheral zone were assessed by comparing area under curve of ROC curve. Results: A value of 42 kPa was used as the cutoff for differentiating benign from malignant prostatic tissue; the sensitivity, specificity, PPV, NPV, and accuracy were 78.97%, 90.67%, 71.30%, 93.66% and 88.03%, respectively. Rank correlation analysis revealed that the stiffness of PCa had a correlation with Gleason score, prognostic grade, and percentage of cancer in biopsy. On multivariate analysis, the age, free prostate-specific antigen (PSA), PSA density, SWE, and MRI were independent predictors for diagnosing PCa. There was no statistical difference for diagnosing PCa between SWE and MRI (p = 0.259). However, for clinically significant PCa, the diagnostic capacity of SWE was a little higher than MRI (p = 0.013). Conclusions: SWE may provide additional information for PCa detection, which could increase the positive rate of PCa in targeted biopsy and reduce unnecessary biopsy. SWE is compatible with MRI for detecting PCa in the peripheral zone.

Advanced ultrasound in the diagnosis of prostate cancer

The diagnosis of prostate cancer (PCa) can be challenging due to the limited performance of current diagnostic tests, including PSA, digital rectal examination and transrectal conventional US. Multiparametric MRI has improved PCa diagnosis and is recommended prior to biopsy; however, mp-MRI does miss a substantial number of PCa. Advanced US modalities include transrectal prostate elastography and contrast-enhanced US, as well as improved B-mode, micro-US and micro-Doppler techniques. These techniques can be combined to define a novel US approach, multiparametric US (mp-US). Mp-US improves PCa diagnosis but is not sufficiently accurate to obviate the utility of mp-MRI. Mp-US using advanced techniques and mp-MRI provide complementary information which will become even more important in the era of focal therapy, where precise identification of PCa location is needed.

Quantitative assessment of treatment efficacy in keloids using high-frequency ultrasound and shear wave elastography: a preliminary study

The purpose of this study was to investigate the performance of high-frequency ultrasound (HFUS) and shear wave elastography (SWE) in the quantitative evaluation of therapeutic responses of keloids. 43 patients with 76 keloids were recruited into this study. In keloids and symmetrical sites, the skin thickness was measured using HFUS and skin stiffness expressed as elastic moduli (Young's modulus and shear wave velocity) was measured using SWE. The coefficient of variation values were calculated by using difference values of skin elastic moduli and skin thickness. A significant increase of both skin stiffness and thickness appeared in pre-treated keloids compared with post-treated keloids (P < 0.001) and normal controls (P < 0.001), respectively. Stiffness in post-treated keloids and normal skins was significantly different (P < 0.001), while the difference in thickness measurements showed no significance (P = 0.56, >0.05). The coefficient of variation of Young's modulus was the highest when compared between (i) pre-treated keloids and theirs site-matched areas; (ii) pre-treated and post-treated keloids. SWE, which showed greater ability in determining the extent of keloids recovery, may provide an ideal tool to assess the stiffness of keloids and theirs therapeutic response.

Tissue ACE phenotyping in prostate cancer

Epithelial cells of prostate express significant level of ACE and, as a result, seminal fluid has 50-fold more ACE than plasma. The substitution of highly specialized prostate epithelial cells by tumor cells results in dramatic decrease in ACE production in prostate tissues. We performed detailed characterization of ACE status in prostate tissues from patients with benign prostate hyperplasia (BPH) and prostate cancer (PC) using new approach- ACE phenotyping, that includes evaluation of: 1) ACE activity with two substrates (HHL and ZPHL); 2) the ratio of the rates of their hydrolysis (ZPHL/HHL ratio); 3) the ratio of immunoreactive ACE protein to ACE activity; 4) the pattern of mAbs binding to different epitopes on ACE – ACE conformational fingerprint - to reveal conformational changes in prostate ACE due to prostate pathology. ACE activity dramatically decreased and the ratio of immunoreactive ACE protein to ACE activity increased in PC tissues. The catalytic parameter, ZPHL/HHL ratio, increased in prostate tissues from all patients with PC, but was did not change for most |BPH patients. Nevertheless, prostate tissues of several patients diagnosed with BPH based on histology, also demonstrated decreased ACE activity and increased immunoreactive ACE protein/ACE activity and ZPHL/HHL ratios, that could be considered as more early indicators of prostate cancer development than routine histology. Thus, ACE phenotyping of prostate biopsies has a potential to be an effective approach for early diagnostics of prostate cancer or at least for differential diagnostics of BPH and PC.

Automated multiparametric localization of prostate cancer based on B-mode, shear-wave elastography, and contrast-enhanced ultrasound radiomics

OBJECTIVES

The aim of this study was to assess the potential of machine learning based on B-mode, shear-wave elastography (SWE), and dynamic contrast-enhanced ultrasound (DCE-US) radiomics for the localization of prostate cancer (PCa) lesions using transrectal ultrasound.

METHODS

This study was approved by the institutional review board and comprised 50 men with biopsy-confirmed PCa that were referred for radical prostatectomy. Prior to surgery, patients received transrectal ultrasound (TRUS), SWE, and DCE-US for three imaging planes. The images were automatically segmented and registered. First, model-based features related to contrast perfusion and dispersion were extracted from the DCE-US videos. Subsequently, radiomics were retrieved from all modalities. Machine learning was applied through a random forest classification algorithm, using the co-registered histopathology from the radical prostatectomy specimens as a reference to draw benign and malignant regions of interest. To avoid overfitting, the performance of the multiparametric classifier was assessed through leave-one-patient-out cross-validation.

RESULTS

The multiparametric classifier reached a region-wise area under the receiver operating characteristics curve (ROC-AUC) of 0.75 and 0.90 for PCa and Gleason > 3 + 4 significant PCa, respectively, thereby outperforming the best-performing single parameter (i.e., contrast velocity) yielding ROC-AUCs of 0.69 and 0.76, respectively. Machine learning revealed that combinations between perfusion-, dispersion-, and elasticity-related features were favored.

CONCLUSIONS

In this paper, technical feasibility of multiparametric machine learning to improve upon single US modalities for the localization of PCa has been demonstrated. Extended datasets for training and testing may establish the clinical value of automatic multiparametric US classification in the early diagnosis of PCa.

KEY POINTS

• Combination of B-mode ultrasound, shear-wave elastography, and contrast ultrasound radiomics through machine learning is technically feasible. • Multiparametric ultrasound demonstrated a higher prostate cancer localization ability than single ultrasound modalities. • Computer-aided multiparametric ultrasound could help clinicians in biopsy targeting.

Prediction of Postprostatectomy Biochemical Recurrence Using Quantitative Ultrasound Shear Wave Elastography Imaging

Objectives: To determine the prognostic significance of tissue stiffness measurement using transrectal ultrasound shear wave elastography in predicting biochemical recurrence following radical prostatectomy for clinically localized prostate cancer.

Patients and Methods: Eligible male patients with clinically localized prostate cancer and extraperitoneal laparoscopic radical prostatectomy between November 2013 and August 2017 were retrospectively selected. Information of potential biochemical recurrence predictors, including imaging (ultrasound shear wave elastography and magnetic resonance imaging), clinicopathological characteristics, and preoperative prostate specific antigen (PSA) levels were obtained. Recurrence-free survival (Kaplan–Meier curve) and a multivariate model were constructed using Cox regression analysis to evaluate the impact of shear wave elastography as a prognostic marker for biochemical recurrence.

Results: Patients experienced biochemical recurrence in an average of 26.3 ± 16.3 months during their follow-up. A cutoff of 144.85 kPa for tissue stiffness measurement was estimated for recurrence status at follow-up with a sensitivity of 74.4% and a specificity of 61.7%, respectively (p < 0.05). In univariate analysis, shear wave elastography performed well in all preoperative factors compared to biopsy Gleason Score, PSA and magnetic resonance imaging; in multivariate analysis with postoperative pathological factors, shear wave elastography was statistically significant in predicting postoperative biochemical recurrence, which improved the C-index of predictive nomogram significantly (0.74 vs. 0.70, p < 0.05).

Conclusions: The study revealed that quantitative ultrasound shear wave elastography-measured tissue stiffness was a significant imaging marker that enhanced the predictive ability with other clinical and histopathological factors in prognosticating postoperative biochemical recurrence following radical prostatectomy for clinically localized prostate cancer.

Shear Wave Elastography in Rectal Cancer Staging, Compared with Endorectal Ultrasonography and Magnetic Resonance Imaging

The goal of the study described here was to investigate the value of shear wave elastography (SWE) in pre-operative staging of rectal cancer. Fifty-five patients with rectal cancer underwent pre-operative conventional endorectal ultrasonography (ERUS), SWE and enhanced magnetic resonance imaging (MRI) examinations. Pathologic results were used as the gold standard for cancer staging. The concordance rate with pathologic stage by ERUS and MRI and the stiffness values measured by SWE for tumors in different stages were compared. The concordance rates for cancer staging were 72.7% and 70.9% for conventional ERUS and enhanced MRI, respectively; the difference was not significant (p > 0.05). SWE indicated that the mean and maximum stiffness values of the tumors increased with advance in stage. The differences in stiffness values between T1 and T2, T1 and T3-4, as well as T2 and T3-4, were all statistically significant (p < 0.001). When the maximum stiffness values of 65.0 and 90.7 kPa are used for the diagnosis of T1, T2 and local advanced rectal cancer, the concordance rate of cancer staging was 85.5%, which was slightly higher than those of ERUS and MRI, although the difference was not statistically significant (p > 0.05). SWE is useful in judging the depth of invasion of rectal tumors. The value of tumor stiffness can provide a quantifiable indicator for pre-operative diagnosis of cancer staging and can be used as a supplement to conventional ERUS. Further studies with larger sample sizes are needed.

Utility of shear wave elastography to detect papillary thyroid carcinoma in thyroid nodules: efficacy of the standard deviation elasticity

BACKGROUND/AIMS

The aim of this study was to address the role of the elasticity index as a possible predictive marker for detecting papillary thyroid carcinoma (PTC) and quantitatively assess shear wave elastography (SWE) as a tool for differentiating PTC from benign thyroid nodules.

METHODS

One hundred and nineteen patients with thyroid nodules undergoing SWE before ultrasound-guided fine needle aspiration and core needle biopsy were analyzed. The mean (EMean), minimum (EMin), maximum (EMax), and standard deviation (ESD) of SWE elasticity indices were measured.

RESULTS

Among 105 nodules, 14 were PTC and 91 were benign. The EMean, EMin, and EMax values were significantly higher in PTCs than benign nodules (EMean 37.4 in PTC vs. 23.7 in benign nodules, p = 0.005; EMin 27.9 vs. 17.8, p = 0.034; EMax 46.7 vs. 31.5, p < 0.001). The EMean, EMin, and EMax were significantly associated with PTC with diagnostic odds ratios varying from 6.74 to 9.91, high specificities (86.4%, 86.4%, and 88.1%, respectively), and positive likelihood ratios (4.21, 3.69, and 4.82, respectively). The ESD values were significantly higher in PTC than in benign nodules (6.3 vs. 2.6, p < 0.001). ESD had the highest specificity (96.6%) when applied with a cut-off value of 6.5 kPa. It had a positive likelihood ratio of 14.75 and a diagnostic odds ratio of 28.50.

CONCLUSION

The shear elasticity index of ESD, with higher likelihood ratios for PTC, will probably identify nodules that have a high potential for malignancy. It may help to identify and select malignant nodules, while reducing unnecessary fine needle aspiration and core needle biopsies of benign nodules.

Diagnostic Performance of Multiparametric Transrectal Ultrasound in Localized Prostate Cancer: A Comparative Study With Magnetic Resonance Imaging

OBJECTIVES

The aim of this study was to compare the diagnostic performance of multiparametric transrectal ultrasound (TRUS), including grayscale imaging, color Doppler imaging, shear wave elastography, and contrast-enhanced ultrasound, to that of multiparametric magnetic resonance imaging (MRI), including T2-weighted, diffusion-weighted, and dynamic contrast-enhanced MRI, in the diagnosis of localized prostate cancer (PCa; lesions at stage T2 or lower).

METHODS

Seventy-eight patients were prospectively enrolled, including 40 in a benign prostate group and 38 in a localized PCa group (≤T2). The diagnostic performance of multiparametric TRUS and multiparametric MRI in detecting localized PCa was analyzed with surgical and biopsy pathologic results as the references.

RESULTS

Multiparametric TRUS had higher sensitivity, negative predictive value, and accuracy than multiparametric MRI (97.4% versus 94.7%, 96.9% versus 92.3%, and 87.2% versus 76.9%, respectively) for detecting localized PCa. The mean area under the receiver operating characteristic curve ± SD for multiparametric TRUS was 0.874 ± 0.043 (95% confidence interval, 0.790-0.959), and it was 0.774 ± 0.055 (95% confidence interval, 0.666-0.881) for multiparametric MRI.

CONCLUSIONS

Our results suggest that multiparametric TRUS has high diagnostic performance in the diagnosis of localized PCa. Multiparametric TRUS is compatible with multiparametric MRI in the detection of localized PCa (≤T2).

3D porous chitosan-alginate scaffold stiffness promotes differential responses in prostate cancer cell lines

Prostate cancer (PCa) is a leading cause of death for men worldwide. Most PCa patients die from metastasis and bone is the most common metastatic site. Three dimensional (3D) porous chitosan-alginate (CA) scaffolds were developed for bone tissue engineering and demonstrated for culture of cancer cells and enrichment of cancer stem cells. However, only a single scaffold composition was studied. Three compositions of 3D porous CA scaffolds (2, 4, and 6 wt%) were used to investigate the effect of scaffold stiffness on PCa cell response with PC-3, C4-2B, and 22Rv1 cell lines. The PC-3 cells formed cell clusters while the C4-2B and 22Rv1 cells formed multicellular spheroids. The three cell lines demonstrated stiffness independent cell growth and expressed phenotypic PCa biomarkers. The osteoblastic PCa lines C4-2B and 22Rv1 mineralized in basal media, while the osteolytic PC-3 line did not, demonstrating that CA scaffold cultures revealed differences in PCa phenotypes. The CA scaffolds are a 3D culture platform that supports PCa growth and phenotypic expression with adjustable scaffold stiffness to mimic stages of metastatic progression. Further investigation of the scaffolds for co-culture of PCa cells with fibroblasts and primary PCa cell culture should be conducted to develop a platform for screening chemotherapies.

Comparative Diagnostic Accuracy of Contrast-Enhanced Ultrasound and Shear Wave Elastography in Differentiating Benign and Malignant Lesions: A Network Meta-Analysis

Background: We performed a network meta-analysis to compare the diagnostic accuracy of contrast-enhanced ultrasound (CEUS) and shear wave elastography (SWE) in differentiating benign and malignant lesions in different body sites.

Methods: A computerized literature search of Medline, Embase, SCOPUS, and Web of Science was performed using relevant keywords. Following data extraction, we calculated sensitivity, specificity, positive likelihood ratio (LR), negative LR, and diagnostic odds ratio (DOR) for CEUS, and SWE compared to histopathology as a reference standard. Statistical analyses were conducted by MetaDiSc (version 1.4) and R software (version 3.4.3).

Results: One hundred and fourteen studies (15,926 patients) were pooled in the final analyses. Network meta-analysis showed that CEUS had significantly higher DOR than SWE (DOR = 27.14, 95%CI [2.30, 51.97]) in breast cancer detection. However, there were no significant differences between CEUS and SWE in hepatic (DOR = −6.67, 95%CI [−15.08, 1.74]) and thyroid cancer detection (DOR = 3.79, 95%CI [−3.10, 10.68]). Interestingly, ranking analysis showed that CEUS achieved higher DOR in detecting breast and thyroid cancer, while SWE achieved higher DOR in detecting hepatic cancer. The overall DOR for CEUS in detecting renal cancer was 53.44, 95%CI [29.89, 95.56] with an AUROC of 0.95, while the overall DOR for SWE in detecting prostate cancer was 25.35, 95%CI [7.15, 89.89] with an AUROC of 0.89.

Conclusion: Both diagnostic tests showed relatively high sensitivity and specificity in detecting malignant tumors in different organs. Network meta-analysis showed that CEUS had higher diagnostic accuracy than SWE in detecting breast and thyroid cancer, while SWE had higher accuracy in detecting hepatic cancer. However, the results were not statistically significant in hepatic and thyroid malignancies. Further head-to-head comparisons are needed to confirm the optimal imaging technique to differentiate each cancer type.

Quantitative Elastography of Rectal Lesions: The Value ofShear Wave Elastography in Identifying Benign and Malignant Rectal Lesions

We evaluate the value of shear wave elastography (SWE) in diagnosing benign and malignant rectal lesions. A total of 96 lesions were reviewed in this study; endorectal ultrasound (ERUS) and SWE examinations were performed before surgery in all cases. Elasticity parameters including mean elastographic index (E_mean), maximum elastographic index (E_max) and minimum elastographic index (E_min) were analyzed. Correlations between elastographic parameters and histopathological results were studied. Inter-observer and intra-observer agreement was analyzed. Of the 96 rectal lesions, 72 were malignant and 24 were benign. Compared with ERUS, ERUS + SWE had higher sensitivity (93.0% vs. 88.9%), specificity (83.3% vs. 79.2%), positive predictive value (94.4% vs. 92.7%), negative predictive value (80.0% vs. 70.4%) and overall accuracy (90.6% vs. 86.4%). In receiver operating characteristic curve analysis, E_mean and E_max had larger areas under the curve: 0.92 and 0.91, respectively. The optimal cutoff value was 61.3 kPa for E_mean (sensitivity = 88.9%, specificity = 87.5%) and 63.4 kPa for E_max (sensitivity = 94.4%, specificity = 83.3%). We obtained κ values of 0.83 (95% confidence interval [CI]: 0.72-0.95) for ERUS and 0.90 (95% CI: 0.81-0.99) for ERUS + SWE of differential diagnosis in two observers. The intra-class correlation coefficients for intra-observer variability of stiffness (E_mean) in malignant lesions, benign lesions, surrounding normal rectal wall in malignant lesions and surrounding normal rectal wall in benign lesions were 0.91 (95% CI: 0.86-0.94), 0.94 (95% CI: 0.88-0.97), 0.92 (95% CI: 0.88-0.95) and 0.89 (95% CI: 0.77-0.95), respectively. SWE is a promising tool that yields valuable quantitative data additional to that provided by ERUS examination in rectal lesions. The cutoff value 61.3 kPa for E_mean may serve as a complementary tool in diagnosis of rectal lesions.

Multiparametric ultrasound: evaluation of greyscale, shear wave elastography and contrast-enhanced ultrasound for prostate cancer detection and localization in correlation to radical prostatectomy specimens

BACKGROUND

The diagnostic pathway for prostate cancer (PCa) is advancing towards an imaging-driven approach. Multiparametric magnetic resonance imaging, although increasingly used, has not shown sufficient accuracy to replace biopsy for now. The introduction of new ultrasound (US) modalities, such as quantitative contrast-enhanced US (CEUS) and shear wave elastography (SWE), shows promise but is not evidenced by sufficient high quality studies, especially for the combination of different US modalities. The primary objective of this study is to determine the individual and complementary diagnostic performance of greyscale US (GS), SWE, CEUS and their combination, multiparametric ultrasound (mpUS), for the detection and localization of PCa by comparison with corresponding histopathology.

METHODS/DESIGN

In this prospective clinical trial, US imaging consisting of GS, SWE and CEUS with quantitative mapping on 3 prostate imaging planes (base, mid and apex) will be performed in 50 patients with biopsy-proven PCa before planned radical prostatectomy using a clinical ultrasound scanner. All US imaging will be evaluated by US readers, scoring the four quadrants of each imaging plane for the likelihood of significant PCa based on a 1 to 5 Likert Scale. Following resection, PCa tumour foci will be identified, graded and attributed to the imaging-derived quadrants in each prostate plane for all prostatectomy specimens. Primary outcome measure will be the sensitivity, specificity, negative predictive value and positive predictive value of each US modality and mpUS to detect and localize significant PCa evaluated for different Likert Scale thresholds using receiver operating characteristics curve analyses.

DISCUSSION

In the evaluation of new PCa imaging modalities, a structured comparison with gold standard radical prostatectomy specimens is essential as first step. This trial is the first to combine the most promising ultrasound modalities into mpUS. It complies with the IDEAL stage 2b recommendations and will be an important step towards the evaluation of mpUS as a possible option for accurate detection and localization of PCa.

TRIAL REGISTRATION

The study protocol for multiparametric ultrasound was prospectively registered on Clinicaltrials.gov on 14 March 2017 with the registry name 'Multiparametric Ultrasound-Study for the Detection of Prostate Cancer' and trial registration number NCT03091231.

A Novel Scoring System for Prediction of Prostate Cancer Based on Shear Wave Elastography and Clinical Parameters

OBJECTIVE

To develop a novel scoring system for the prediction of prostate cancer (PCa).

METHODS

We assessed 127 patients who underwent a prostate biopsy. Prior to biopsy, we performed shear wave elastography (SWE), transrectal ultrasound, digital rectal exam, total prostatic specific antigen, PSA density (PSAD), and free PSA/total PSA ratio (F/T). We developed an 11-point scoring system based on SWE and these clinical parameters.

RESULTS

PCa was diagnosed in 51 (40.2%) of 127 patients and 192 (25.2%) of 762 sextants on initial biopsy. ROC curve analyses showed that the cutoff value (COV) for SWE was 40.8 kpa at the sextant level. The AUC of score system based on the SWE and clinical parameters (0.911) was significantly different from scoring systems based on SWE alone (0.842) or clinical parameters alone (0.868). For this 11-point scoring system, the optimal COV, Youden index, sensitivity, specificity, PPV, NPV, and AUC were 3 points, 0.66, 76.5% 89.5%, 82.98%, 85.00%, and 0.911, respectively. There were 68 negative biopsy results in patients with 0-3 points, and the detection rate of PCa was 100% in patients with scores exceeding 6 points.

CONCLUSION

This 11-point scoring system based on SWE and clinical parameters has the good diagnostic performance for predicting PCa. It may be useful in selecting patients for biopsy, substantially reducing the number of unnecessary biopsies while ensuring that few cancers are missed.