Contrast-enhanced ultrasonography of the prostate: various imaging findings that indicate prostate cancer

Diagnostic accuracy of qualitative and quantitative magnetic resonance imaging-guided contrast-enhanced ultrasound (MRI-guided CEUS) for the detection of prostate cancer: a prospective and multicenter study

PURPOSE

To evaluate the diagnostic value of MRI-guided contrast-enhanced ultrasound (CEUS) for prostate cancer (PCa) diagnosis, and characteristics of PCa in qualitative and quantitative CEUS.

MATERIAL AND METHODS

This prospective and multicenter study included 250 patients (133 in the training cohort, 57 in the validation cohort and 60 in the test cohort) who underwent MRI, MRI-guided CEUS and prostate biopsy between March 2021 and February 2023. MRI interpretation, qualitative and quantitative CEUS analysis were conducted. Multitree extreme gradient boosting (XGBoost) machine learning-based models were applied to select the eight most important quantitative parameters. Univariate and multivariate logistic regression models were constructed to select independent predictors of PCa. Diagnostic value was determined for MRI, qualitative and quantitative CEUS using the area under receiver operating characteristic curve (AUC).

RESULTS

The performance of quantitative CEUS was superior to that of the qualitative CEUS and MRI in predicting PCa. The AUC was 0.779 (95%CI 0.70-0.849), 0.756 (95%CI 0.638-0.874) and 0.759 (95%CI 0.638-0.879) of qualitative CEUS, and 0.885 (95%CI 0.831-0.940), 0.802 (95%CI 0.684-0.919) and 0.824 (95%CI 0.713-0.936) of quantitative CEUS in training, validation and test cohort, respectively. Compared with quantitative CEUS, MRI achieved less well performance for AUC 0.811 (95%CI 0.741-0.882, p = 0.099), 0.748 (95%CI 0.628-0.868, p = 0.539) and 0.737 (95%CI 0.602-0.873, p = 0.029), respectively. Moreover, the highest specificity of 80.6% was obtained by quantitative CEUS.

CONCLUSION

We developed a reliable method of MRI-guided CEUS that demonstrated enhanced performance compared to MRI. The qualitative and quantitative CEUS characteristics will contribute to improved diagnosis of PCa.

The combined value of mpUS and mpMRI-TRUS fusion for the diagnosis of clinically significant prostate cancer

Objective

To evaluate the combined efficacy of multiparametric ultrasonography (mpUS) and multiparametric magnetic resonance imaging/transrectal ultrasound (mpMRI-TRUS) fusion for detecting clinically significant prostate cancer (csPCa).

Methods

From November 2019 to September 2021, biopsy-naïve patients underwent mpMRI-TRUS fusion imaging combined with mpUS-guided targeted biopsies (TB) and systematic biopsies (SB). To further evaluate the additional diagnostic value of mpUS, the imaging features of 202 focus obtained from fusion imaging were assessed. The diagnostic accuracies of mpMRI-TRUS fusion imaging and the combination of mpMRI-TRUS fusion imaging with mpUS for csPCa were comparatively evaluated.

Results

A total of 202 prostate lesions (160 patients) were included in the final analysis, of which 105 were csPCa, 16 were ciPCa, and 81 were noncancerous. The median patient age was 69 (65–73) years and the median tPSA was 22.07 (11.22–62.80) ng/mL. For csPCa, the detection rate of TB was higher than that of SB (50.0% vs. 45.5%, p < 0.05). The imaging characteristics of mpUS in the PCa and non-PCa groups were significantly different (p < 0.001). When compared with mpMRI-TRUS fusion imaging, the positive predictive value, false positive rate, and area under the curve (AUC) of csPCa diagnosis by mpMRI-TRUS fusion imaging combined with mpUS increased by 11.30%, decreased by 19.58%, and increased from 0.719 to 0.770 (p < 0.05), respectively.

Conclusion

TB can improve the detection rate of csPCa and hence can be effectively used in the diagnosis and risk assessment of csPCa. The mpUS-enriched valuable diagnostic information for mpMRI-TRUS fusion imaging and their combination showed a higher diagnostic value for csPCa, which can guide subsequent clinical treatment.

Recent advances of multi-modal ultrasound in image-guided prostate-targeted biopsy

Prostate-targeted biopsy is usually the preferred method over systematic biopsy because it can effectively detect prostate cancer using only a few puncture cores with fewer complications. With the development of ultrasound, it has gained multimodal technological upgrades, such as the emergence of contrast-enhanced ultrasound, ultrasound elastography, and three-dimensional ultrasonography. Moreover, multimodal ultrasound has played an increasingly significant role in prostate-targeted biopsies.

Imaging findings of prostate tuberculosis by transrectal contrast-enhanced ultrasound and comparison with 2D ultrasound and pathology

Objectives:

This study aimed to investigate the contrast-enhanced ultrasound (CEUS) appearances of prostate tuberculosis (PTB) and its correlation with histopathology.

Methods:

Clinical, transrectal ultrasonography (TRUS) and CEUS data of 12 PTB patients confirmed by pathology were retrospectively analyzed, and compared to the pathological findings to identify the pathological structures corresponding to different image enhancement areas.

Results:

No specific characteristics could be found for the clinical appearances. Enlarged gland, hypoechoic lesions and calcification due to PTB could be found by TRUS, which were also non-specific. CEUS showed hypo- or non-enhanced lesions with varying size, which were related to different pathological stages of PTB. The incidence rate of non-enhanced lesions was 83.3%. The detection rate of suspected lesion by CEUS was significantly higher than that by TRUS (χ² = 8.000, p = 0.005). Histopathology showed that the hypoenhanced area consisted of tuberculous granulomas, caseous necrosis and incomplete destruction of the glands, while the non-enhanced area consisted of caseous or liquified necrosis.

Conclusion:

CEUS could improve the detection rate of PTB lesions, and the diversity of its manifestations was related to different pathological structures. An enlarged, soft gland with non-enhanced on CEUS may provide valuable information for the diagnosis of PTB, but it is not a substitute for biopsy due to the diversity of CEUS findings.

Advances in knowledge:

When the lesions of prostate gland are unclear in TRUS examination, CEUS is an ideal option for the detection of lesions, which is conducive to targeted guidance of biopsy areas.

Transrectal Ultrasound and Photoacoustic Imaging Probe for Diagnosis of Prostate Cancer

A combined transrectal ultrasound and photoacoustic (TRUS-PA) imaging probe was developed for the clear visualization of morphological changes and microvasculature distribution in the prostate, as this is required for accurate diagnosis and biopsy. The probe consisted of a miniaturized 128-element 7 MHz convex array transducer with 134.5° field-of-view (FOV), a bifurcated optical fiber bundle, and two optical lenses. The design goal was to make the size of the TRUS-PA probe similar to that of general TRUS probes (i.e., about 20 mm), for the convenience of the patients. New flexible printed circuit board (FPCB), acoustic structure, and optical lens were developed to meet the requirement of the probe size, as well as to realize a high-performance TRUS-PA probe. In visual assessment, the PA signals obtained with the optical lens were 2.98 times higher than those without the lens. Moreover, the in vivo experiment with the xenograft BALB/c (Albino, Immunodeficient Inbred Strain) mouse model showed that TRUS-PA probe was able to acquire the entire PA image of the mouse tight behind the porcine intestine about 25 mm depth. From the ex vivo and in vivo experimental results, it can be concluded that the developed TRUS-PA probe is capable of improving PA image quality, even though the TRUS-PA probe has a cross-section size and an FOV comparable to those of general TRUS probes.

Contrast-enhanced transrectal ultrasound can reduce collection of unnecessary biopsies when diagnosing prostate cancer and is predictive of biochemical recurrence following a radical prostatectomy in patients with localized prostate cancer

Background

To investigate the value of using contrast-enhanced transrectal ultrasound (CETRUS) to reduce unnecessary collection of biopsies during prostate cancer diagnosis and its utility in predicting biochemical recurrence in patients with localized prostate cancer.

Methods

This was a prospective study of suspected prostate cancer patients who were evaluated with CETRUS followed by a prostate biopsy. Prostate blood flow via CETRUS was graded using a 5-point scale. The relationship between CETRUS score and biopsy outcome was then analyzed for all patients; univariate and multi-variate analyses were used to determine the probable prognostic factors for biochemical recurrence in patients with localized prostate cancer that underwent a radical prostatectomy.

Results

A total of 347 patients were enrolled in the study. Prostate cancer was found in 164 patients. A significant positive correlation (r = 0.69, p < 0.001) was found between CETRUS scores and prostate cancer incidence. Using CETRUS scores ≥2 as the threshold for when to biopsy could have safely reduced the number of biopsies taken overall by 12.1% (42/347) and spared 23.0% (42/183) of patients from undergoing an unnecessary biopsy. 77 patients with localized prostate cancer underwent a radical prostatectomy. The median follow-up time was 30 months (range: 8–56 months) and 17 of these 77 patients exhibited biochemical recurrence during the follow-up period. 3-year biochemical recurrence-free survival rates were 86% for patients with low CETRUS scores (≤ 3) and 59% for patients with high scores (> 3; p = 0.015). Multivariate Cox regression analysis indicated that CETRUS score was an independent predictor of biochemical recurrence (HR: 7.02; 95% CI: 2.00–24.69; p = 0.002).

Conclusions

CETRUS scores may be a useful tool for reducing the collection unnecessary biopsy samples during prostate cancer diagnosis and are predictive of biochemical recurrence in patients with localized prostate cancer following a radical prostatectomy.

Contrast-enhanced ultrasound with dispersion analysis for the localization of prostate cancer: correlation with radical prostatectomy specimens

PURPOSE

To determine the value of two-dimensional (2D) contrast-enhanced ultrasound (CEUS) imaging and the additional value of contrast ultrasound dispersion imaging (CUDI) for the localization of clinically significant prostate cancer (csPCa).

METHODS

In this multicentre study, subjects scheduled for a radical prostatectomy underwent 2D CEUS imaging preoperatively. CUDI maps were generated from the CEUS recordings. Both CEUS recordings and CUDI maps were scored on the likelihood of presenting csPCa (any Gleason ≥ 4 + 3 and Gleason 3 + 4 larger than 0.5 mL) by five observers and compared to radical prostatectomy histopathology. An automated three-dimensional (3D) fusion protocol was used to match imaging with histopathology. Receiver operator curve (ROC) analysis was performed per observer and imaging modality.

RESULTS

133 of 216 (62%) patients were included in the final analysis. Average area under the ROC for all five readers for CEUS, CUDI and the combination was 0.78, 0.79 and 0.78, respectively. This yields a sensitivity and specificity of 81 and 64% for CEUS, 83 and 56% for CUDI and 83 and 55% for the combination. Interobserver agreement for CEUS, CUDI and the combination showed kappa values of 0.20, 0.18 and 0.18 respectively.

CONCLUSION

The sensitivity and specificity of 2D CEUS and CUDI for csPCa localization are moderate. Despite compressing CEUS in one image, CUDI showed a similar performance to 2D CEUS. With a sensitivity of 83% at cutoff point 3, it could become a useful imaging procedure, especially with 4D acquisition, improved quantification and combination with other US imaging techniques such as elastography.

Design and Fabrication of a Miniaturized Convex Array for Combined Ultrasound and Photoacoustic Imaging of the Prostate

Although transrectal ultrasound (TRUS) imaging is widely used for screening and diagnosing prostate cancer, it is often not found on TRUS images, depending on its stage, size, and location. In addition, due to the weak echo signal and the low contrast of TRUS images, it is difficult to diagnose early-stage prostate cancers and distinguish malignant tumors from benign prostatic hyperplasia. For this reason, TRUS image-guided biopsy is mandatory to confirm the malignancy of the suspicious tumor, but the diagnostic accuracy of initial biopsy is only 20%-30%, so that the patients inevitably undergo repeated biopsies. TRUS-photoacoustic (TRUS-PA) imaging is one way to resolve those problems. However, the development of a TRUS-PA probe, in which an ultrasound array transducer and optical fibers are integrated, is demanding because the overall size of the probe should be as small as possible for the convenience of the patients, while providing the desired performances. Here, we report a recently developed TRUS-PA probe. The core element of the TRUS-PA is a miniaturized 128-element, 7-MHz convex array transducer of which size in the lateral and elevational directions is 11.4 and 5 mm, respectively. A new concept of a flexible printed circuit board was also developed to limit the size of the TRUS-PA probe to less than 15 mm. From the performance evaluation, it was found that the developed array with a field-of-view of 134° has a center frequency of 6.75 MHz, a -6-dB fractional bandwidth of 66%, and a crosstalk of less than -45 dB. In the tissue-mimicking phantom test and ex vivo experiments, the miniaturized convex array proved to be capable of providing combined US and PA images with acceptable imaging quality in spite of its small size.

Comparison of contrast-enhanced ultrasound targeted biopsy versus standard systematic biopsy for clinically significant prostate cancer detection: results of a prospective cohort study with 1024 patients

PURPOSE

To assess contrast-enhanced ultrasound (CEUS) targeted biopsy (TB) for clinically significant prostate cancer (PCa) detection compared with systematic biopsy (SB).

METHODS

A total of 1024 consecutive patients scheduled for prostate biopsy were enrolled in this prospective study. CEUS was performed by an experienced radiologist blinded to all clinical data. Suspicious lesions on postcontrast images were sampled in addition to standard 12-core SB. The clinically significant PCa detection rate by CEUS-TB was evaluated in comparison with SB in the total cohort and in different subgroups.

RESULTS

In 378 of 1024 patients (36.9%), the diagnosis of PCa was histologically confirmed. PCa was detected by CEUS-TB in 306 patients (29.9%, 306/1024) and SB in 317 patients (31.0%, 317/1024, P = 0.340). Among 378 PCa patients, 326 (86.2%, 326/378) were diagnosed with significant PCa using Epstein criteria. The significant PCa detection rate of CEUS-TB was 28.7% (294/1024), which was higher than that of SB (25.3%, 259/1024, P = 0.000). CEUS-TB resulted in 67 additional cases of clinically significant PCa, including 51 patients missed by SB and 16 patients under-graded by SB. Conversely, SB detected 32 additional significant PCa missed by TB. In the subgroup analysis, CEUS-TB yielded a higher significant cancer detection rate than SB in patients with a PSA level ≤ 10.0 ng/ml or prostate volume from 30 to 60 ml.

CONCLUSION

The clinically significant PCa detection rate could be improved by the extra sampling of abnormalities on postcontrast images, especially in patients with a PSA level ≤ 10.0 ng/ml or prostate volume from 30 to 60 ml.

Contrast Enhanced Ultrasound as a Radiation-Free Alternative to Fluoroscopic Nephrostogram for Evaluating Ureteral Patency

PURPOSE

We compared contrast enhanced ultrasound and fluoroscopic nephrostography in the evaluation of ureteral patency following percutaneous nephrolithotomy.

MATERIALS AND METHODS

This prospective cohort, noninferiority study was performed after obtaining institutional review board approval. We enrolled eligible patients with kidney and proximal ureteral stones who underwent percutaneous nephrolithotomy at our center. On postoperative day 1 patients received contrast enhanced ultrasound and fluoroscopic nephrostogram within 2 hours of each other to evaluate ureteral patency, which was the primary outcome of this study.

RESULTS

A total of 92 pairs of imaging studies were performed in 82 patients during the study period. Five study pairs were excluded due to technical errors that prevented imaging interpretation. Females slightly predominated over males with a mean ± SD age of 50.5 ± 15.9 years and a mean body mass index of 29.6 ± 8.6 kg/m². Of the remaining 87 sets of studies 69 (79.3%) demonstrated concordant findings regarding ureteral patency for the 2 imaging techniques and 18 (20.7%) were discordant. The nephrostomy tube was removed on the same day in 15 of the 17 patients who demonstrated antegrade urine flow only on contrast enhanced ultrasound and they had no subsequent adverse events. No adverse events were noted related to ultrasound contrast injection. While contrast enhanced ultrasound used no ionizing radiation, fluoroscopic nephrostograms provided a mean radiation exposure dose of 2.8 ± 3.7 mGy.

CONCLUSIONS

A contrast enhanced ultrasound nephrostogram can be safely performed to evaluate for ureteral patency following percutaneous nephrolithotomy. This imaging technique was mostly concordant with fluoroscopic findings. Most discordance was likely attributable to the higher sensitivity for patency of contrast enhanced ultrasound compared to fluoroscopy.

Value of three-section contrast-enhanced transrectal ultrasonography in the detection of prostate cancer

BACKGROUND

To assess the efficacy of three-section contrast-enhanced transrectal ultrasonography (CETRUS) in prostate cancer (PCa) detection.

METHODS

A total of 169 consecutive patients with either PSA level ≥ 4 ng/ml or abnormal digital rectal examination findings were prospectively enrolled in this single center study. All patients underwent baseline transrectal ultrasonography (TRUS) and three-section CETRUS by one investigator blinded to any clinical data before TRUS-guided transperineal biopsy. The performances of baseline TRUS, single-section, and three-section CETRUS for PCa detection were compared.

RESULTS

On a per-patient basis, the sensitivity, specificity, and overall accuracy for detecting PCa with three-section CETRUS was 92.3%, 69.2%, and 78.1%, respectively. In comparison with conventional (single-section) CETRUS (sensitivity 75.4%, specificity 72.1%, and accuracy 73.4%), three-section CETRUS performed significantly better (p < 0.05, McNemar test). Additionally, the low-grade PCa detection rate for three-section CETRUS was significantly higher than that of conventional CETRUS (26.7% versus 10.2%, p < 0.05).

CONCLUSIONS

Our study demonstrated a significant benefit of three-section CETRUS relative to conventional CETRUS, and this technique may find more PCa patients eligible for active surveillance. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:304-309, 2017.

Contrast-enhanced transrectal ultrasound for prediction of prostate cancer aggressiveness: The role of normal peripheral zone time-intensity curves

To assess the role of time-intensity curves (TICs) of the normal peripheral zone (PZ) in the identification of biopsy-proven prostate nodules using contrast-enhanced transrectal ultrasound (CETRUS). This study included 132 patients with 134 prostate PZ nodules. Arrival time (AT), peak intensity (PI), mean transit time (MTT), area under the curve (AUC), time from peak to one half (TPH), wash in slope (WIS) and time to peak (TTP) were analyzed using multivariate linear logistic regression and receiver operating characteristic (ROC) curves to assess whether combining nodule TICs with normal PZ TICs improved the prediction of prostate cancer (PCa) aggressiveness. The PI, AUC (p < 0.001 for both), MTT and TPH (p = 0.011 and 0.040 respectively) values of the malignant nodules were significantly higher than those of the benign nodules. Incorporating the PI and AUC values (both, p < 0.001) of the normal PZ TIC, but not the MTT and TPH values (p = 0.076 and 0.159 respectively), significantly improved the AUC for prediction of malignancy (PI: 0.784–0.923; AUC: 0.758–0.891) and assessment of cancer aggressiveness (p < 0.001). Thus, all these findings indicate that incorporating normal PZ TICs with nodule TICs in CETRUS readings can improve the diagnostic accuracy for PCa and cancer aggressiveness assessment.

The standards of an ultrasound examination of the prostate gland. Part 1

The article discusses the principles of the proper performance of the ultrasound examination of the prostate gland. The paper has been divided into two parts: the general one and the detailed one. The first part presents the necessary requirements referring to the ultrasound apparatus for performing transabdominal examinations of the urinary bladder and the prostate gland as well as for transrectal examinations of the prostate gland. The paper also describes the techniques of performing both examinations together with the methods of measuring the capacity of the urinary bladder and the volume of the prostate gland. It also mentions the most frequent indications for performing the examinations as well as diagnostic algorithms applied in case of finding irregularities. The transabdominal ultrasonography is a part of the examination of the abdominal organs and it should be performed in patients complaining of dysuric symptoms. An addition to the examination, especially when the prostate gland is enlarged, should be the measurement of the capacity of the urinary bladder and the assessment of the amount of residual urine after voiding. The indications for the endosonographic examination of the prostate gland are patological changes found in the per rectum examination, elevated concentration of the prostate-specific antigen in the blood serum, cancer and inflammations of the prostate gland if an abscess is suspected, qualification for surgery in the course of benign prostatic hyperplasia and the diagnostics of disorders of ejaculation. A standard procedure performed in case of prostate cancer for the purpose of obtaining specimens for the histopathology examination is biopsy carried out with transrectal ultrasound imaging. The paper presents the indications and techniques of performing prostate biopsy, as well as the types of biopsies together with the necessary preparation and the protection against its side effects for the patient. The paper also lists the necessary elements of the description of the presented procedures. The second part of the paper presents the application of the ultrasound examination in benign prostatic hyperplasia, in cases of inflammation and in prostate cancer.

Feasibility of Retrograde Ureteral Contrast Injection to Guide Ultrasonographic Percutaneous Renal Access in the Nondilated Collecting System

OBJECTIVES

Ultrasound-guided percutaneous nephrolithotomy (PCNL) has become increasingly utilized. Patients with nondilated collecting systems represent a challenge: the target calix is often difficult to visualize. Here we report pilot study results for retrograde ultrasound contrast injection to aid in percutaneous renal access during ultrasound-guided PCNL.

PATIENTS AND METHODS

From April to July 2016, consecutive patients over the age of 18 years with nondilated collecting systems on preoperative imaging who presented for PCNL were enrolled. B-mode ultrasound imaging was compared with contrast-enhanced mode with simultaneous retrograde injection of Optison™ via an ipsilateral ureteral catheter.

RESULTS

Five patients (four males and one female) with renal stones underwent PCNL with retrograde ultrasound contrast injection during the study period. Mean body mass index was 28.3 ± 5.6 kg/m² and mean stone size was 24.5 ± 12.0 mm. Under B-mode ultrasound, all patients demonstrated nondilated renal collecting systems that appeared as hyperechoic areas, where it was difficult to identify a target calix for puncture. Retrograde contrast injection facilitated delineation of all renal calices initially difficult to visualize under B-mode ultrasound. Renal puncture was then performed effectively in all cases with a mean puncture time of 55.4 ± 44.8 seconds. All PCNL procedures were completed without intraoperative complications and no adverse events related to ultrasound contrast injection occurred.

CONCLUSION

Retrograde ultrasound contrast injection as an aide for renal puncture during PCNL is a feasible technique. By improving visualization of the collecting system, it facilitates needle placement in challenging patients without hydronephrosis. Future larger scale studies comparing its use to standard ultrasound-guided technique will be required to validate this concept.

The utility and limitations of contrast-enhanced ultrasound for the diagnosis and treatment of prostate cancer

In association with the widespread use of prostate specific antigen (PSA) screening, the numbers of men identified with early-stage prostate cancer (PCa) are increasing in the developed countries, including Japan. However, the accurate localization of PCa lesions in diagnostic imaging is still difficult because PCa has a tendency to be multifocal in the prostate gland. Contrast-enhanced ultrasound (CEUS) improves the detection of PCa by visualizing cancerous lesions in order to target a needle biopsy. CEUS has the potential to enable not only accurate diagnoses but also novel treatments such as focal therapy. The combination of CEUS and other modalities is expected to improve the diagnosis of PCa and its treatment.

Contrast-enhanced transrectal ultrasonography for detection and localization of prostate index tumor: correlation with radical prostatectomy findings

OBJECTIVE

To evaluate the ability of contrast-enhanced transrectal ultrasonography (CETRUS) to detect and localize prostate index tumor.

METHODS

Eighty-three patients with biopsy-proven prostate cancer (PCa), who were scheduled to undergo radical prostatectomy, were enrolled in this prospective study. Each patient underwent baseline grayscale and CETRUS imaging of the prostate according to a standardized protocol before the operation. Ultrasonography findings (CETRUS and grayscale imaging) were correlated with step-section histopathology.

RESULTS

Overall, 53 and 68 tumor foci were detected by grayscale imaging and CETRUS, respectively. The combination of grayscale imaging and CETRUS allowed identification of 89 of the 232 cancer foci (38.4%). The sensitivity of combined imaging was significantly superior to that of grayscale imaging (P<.01) and CETRUS (P<.05). Additionally, the prostate index tumor detection rate by the use of grayscale imaging, CETRUS, and their combination was 42 of 83 (50.6%), 53 of 83 (63.9%), and 67 of 83 (80.7%), respectively. The combined approach performed significantly better than grayscale and CETRUS imaging (P<.001 and P<.05, respectively). The index tumor detection rate of CETRUS was higher than that of grayscale imaging, but no significant difference was found (P>.05).

CONCLUSION

Our study has demonstrated significantly improved detection of both PCa and index tumor with a combined approach of CETRUS and grayscale imaging compared with baseline grayscale technique only, and this technique may be applicable to focal therapy of PCa.

Are hypoechoic lesions on transrectal ultrasonography a marker for clinically significant prostate cancer?

Purpose

To investigate the relationship of transrectal ultrasound (TRUS) findings with the pathological characteristics of prostate cancer (PCa).

Materials and Methods

The study was conducted retrospectively by analyzing the data for 970 patients who underwent prostate biopsies. Gleason scores and other clinical variables were compared between PCa patients with and without hypoechoic lesions on TRUS.

Results

Of the 970 patients, PCa was diagnosed in 291 (30%). Of these, high-grade PCa (Gleason score of 7 or more) was diagnosed in 190 (65%). The cancer detection rate was higher in patients with hypoechoic lesions (43.9%) than in those without hypoechoic lesions (21.4%, p<0.001). High-grade PCa was detected more often in patients with hypoechoic lesions than in those without hypoechoic lesions (p<0.001). Independent predictors for high-grade PCa by logistic regression analysis included hypoechoic lesions on TRUS and abnormal digital rectal examination findings.

Conclusions

Patients with PCa who had hypoechoic lesions on TRUS had more aggressive pathological disease than did those without lesions. Therefore, hypoechoic lesions on TRUS could be a marker for clinically significant PCa.

The value and limitations of contrast-enhanced transrectal ultrasonography for the detection of prostate cancer

OBJECTIVES

To evaluate the role of contrast-enhanced transrectal ultrasonography (CE-TRUS) for detecting prostate carcinoma.

METHODS

Sixty-five patients with elevated serum prostate-specific antigen (PSA) and/or abnormal digital rectal examination (DRE) were assessed using transrectal ultrasound (TRUS) and CE-TRUS. In all the patients, CE-TRUS was performed with intravenous injection of contrast agent (SonoVue, 2.4 ml) before biopsy. The cancer detection rates of the two techniques were compared. False-positive and false-negative findings related to CE-TRUS were analyzed in comparison to the pathological results of biopsy or radical prostatectomy. The targeted biopsy to abnormal CE-TRUS areas was also compared to systematic biopsy.

RESULTS

Prostate cancer was detected in 29 of the 65 patients. CE-TRUS showed rapid focal enhancement or asymmetric vessels of peripheral zones in 28 patients; 23 of them had prostate cancer. CE-TRUS had 79.3% sensitivity, compared to 65.5% of TRUS (P<0.05). There were five false-positive and six false-negative findings from CE-TRUS. Benign prostate hyperplasia, and acute and chronic prostatitis were important causes related to the false-positive results of CE-TRUS. Prostate cancer originating from the transition zone or peripheral zone with lower PSA levels, small-size foci, and moderately or well-differentiated tumor was missed by CE-TRUS. The cancer detection rate of targeted biopsy (75%, 33/44 cores) was significantly higher than one of systematic biopsy (48.2%, 162/336) in those 28 cases (P<0.05). In addition, no significant correlation was found between the cancer detection rate with CE-TRUS and serum PSA levels.

CONCLUSION

CE-TRUS may improve the detection rate of prostate cancer through targeted biopsy of contrast-enhanced abnormalities. Our findings indicate that systematic biopsies should not be eliminated on the basis of false-positive and false-negative findings related to CE-TRUS.

Contrast-enhanced transrectal ultrasonography: measurement of prostate cancer tumor size and correlation with radical prostatectomy specimens

OBJECTIVES

To determine the accuracy of contrast-enhanced transrectal ultrasonography for tumor size measurements of hypoechoic prostate cancer foci located in the peripheral zone.

METHODS

A total of 55 men scheduled for radical prostatectomy, with biopsy-proven cancer in hypoechoic foci located in the peripheral zone, were consecutively enrolled in the present prospective study. Each patient underwent grayscale ultrasound and contrast-enhanced transrectal ultrasonography of the prostate according to a standardized protocol. The maximum tumor diameter on grayscale imaging and contrast-enhanced transrectal ultrasonography was compared with that determined using histopathology.

RESULTS

A mean underestimation was documented to be approximately 3.9 mm and 0.6 mm for grayscale and contrast-enhanced transrectal ultrasonography imaging, respectively. Grayscale and contrast-enhanced transrectal ultrasonography imaging underestimated measurements by 76.67% (46 of 60) and 48.33% (29 of 60), whereas overestimated measurements were 20% (12 of 60) and 26.67% (16 of 60), respectively. A strong correlation was observed between contrast-enhanced transrectal ultrasonography and histopathological measurements (r = 0.91, P < 0.0001). A weak linear correlation was found between grayscale and histopathological measurements (r = 0.59, P < 0.0001). Bland-Altman analysis results were in complete accordance with correlation analysis results. For cases with maximum histopathological tumor diameters ≤10 mm and >10 mm, 40% (6 of 15) and 86.67% (39 of 45) were index tumors, respectively (P < 0.0001).

CONCLUSIONS

Contrast-enhanced transrectal ultrasonography is significantly more accurate than conventional grayscale imaging for measuring prostate tumor size, especially for tumors with a diameter >10 mm, and it might have a role in preoperative assessment of prostatic index tumor sizes.

Multiparametric ultrasound of the prostate: adding contrast enhanced ultrasound to real-time elastography to detect histopathologically confirmed cancer

PURPOSE

We prospectively assessed whether a combined approach of real-time elastography and contrast enhanced ultrasound would improve prostate cancer visualization.

MATERIAL AND METHODS

Between June 2011 and January 2012, 100 patients with biopsy proven prostate cancer underwent preoperative transrectal multiparametric ultrasound combining real-time elastography and contrast enhanced ultrasound. After initial elastographic screening for suspicious lesions, defined as blue areas with decreased tissue strain, each lesion was allocated to the corresponding prostate sector. The target lesion was defined as the largest cancer suspicious area. Perfusion was monitored after intravenous injection of contrast agent. Target lesions were examined for hypoperfusion, normoperfusion or hyperperfusion. Imaging results were correlated with final pathological evaluation on whole mount slides after radical prostatectomy.

RESULTS

Of 100 patients 86 were eligible for final analysis. Real-time elastography detected prostate cancer with 49% sensitivity and 73.6% specificity. Histopathology confirmed malignancy in 56 of the 86 target lesions (65.1%). Of these 56 lesions 52 (92.9%) showed suspicious perfusion, including hypoperfusion in 48.2% and hyperperfusion in 48.2%, while only 4 (7.1%) showed normal perfusion patterns (p = 0.001). The multiparametric approach decreased the false-positive value of real-time elastography alone from 34.9% to 10.3% and improved the positive predictive value of cancer detection from 65.1% to 89.7%.

CONCLUSIONS

Perfusion patterns of prostate cancer suspicious elastographic lesions are heterogeneous. However, the combined approach of real-time elastography and contrast enhanced ultrasound in this pilot study significantly decreased false-positive results and improved the positive predictive value of correctly identifying histopathological cancer.

Applications of transrectal ultrasound in prostate cancer

Transrectal ultrasound (TRUS) was first developed in the 1970s. TRUS-guided biopsy, under local anaesthetic and prophylactic antibiotics, is now the most widely accepted method to diagnose prostate cancer. However, the sensitivity and specificity of greyscale TRUS in the detection of prostate cancer is low. Prostate cancer most commonly appears as a hypoechoic focal lesion in the peripheral zone on TRUS but the appearances are variable with considerable overlap with benign lesions. Because of the low accuracy of greyscale TRUS, TRUS-guided biopsies have become established in the acquisition of systematic biopsies from standard locations. The number of systematic biopsies has increased over the years, with 10-12 cores currently accepted as the minimum standard. This article describes the technique of TRUS and biopsy and its complications. Novel modalities including contrast-enhanced modes and elastography as well as fusion techniques for increasing the sensitivity of TRUS-guided prostate-targeted biopsies are discussed along with their role in the diagnosis and management of prostate cancer.

Contrast-enhanced ultrasound in abdominal imaging

The administration of a contrast agent is considered an essential tool to evaluate abdominal diseases using Ultrasound. The most targeted organ is the liver, especially to characterize focal liver lesions and to assess the response to percutaneous treatment. However, the expanding abdominal indications of contrast-enhanced ultrasound make this technique an important tool in the assessment of organ perfusion including the evaluation of ischemic, traumatic, and inflammatory diseases.

Usefulness of perflubutane microbubble-enhanced ultrasound in imaging and detection of prostate cancer: phase II multicenter clinical trial

PURPOSE

To explore the possibility of targeted biopsy (TBx) using transrectal ultrasound (US) with perflubutane microbubbles, we studied the findings of different cancerous tissue imaging modalities and evaluated needle biopsy in prostate cancer (PCa) using contrast-enhanced US (CEUS) in a multicenter clinical trial.

METHODS

Seventy-one patients undergoing prostate biopsy received intravenous injection of perflubutane microbubbles (Sonazoid(®)). We evaluated and compared images obtained by CEUS. The safety observation period was 2 days after contrast administration.

RESULTS

Among the 30 patients with cancer, one or more sites with findings suggestive of cancer in CEUS were detected in 23 patients (32.4%) by TBx. Although 22 patients had positive cores of cancer by systematic biopsy (SBx), 8 patients had positive cores of cancer in TBx alone (11.3%). There was a significant difference in cancer detection rate by TBx between two cohorts with PSA < 10 ng/mL (22.9%) and PSA ≥ 10 ng/mL (52.2%) (P < 0.02). Close observation of various CEUS findings with Sonazoid(®) enabled targeting of cancerous areas, and consequently, a significant difference (P < 0.05) in the detection rate of cancer was recognized in the transition zone (TZ): SBx; 21/120 (17.5%) and TBx; 17/55 (30.9%). The incidence of adverse events was 6.7% and that of adverse reactions was 4%.

CONCLUSIONS

CEUS with Sonazoid(®) improved the detection rate of PCa by visualizing cancerous lesions. More detailed examination of CEUS images provided efficient characterization especially in the TZ area. TBx according to this procedure is expected to enable a lower number of biopsies and more accurate diagnosis of PCa.

Novel contrast-enhanced ultrasound imaging in prostate cancer

Purpose

The purposes of this paper were to present the current status of contrast-enhanced transrectal ultrasound imaging and to discuss the latest achievements and techniques now under preclinical testing.

Objective

Although grayscale transrectal ultrasound is the standard method for prostate imaging, it lacks accuracy in the detection and localization of prostate cancer. With the introduction of contrast-enhanced ultrasound (CEUS), perfusion imaging of the microvascularization became available. By this, cancer-induced neovascularisation can be visualized with the potential to improve ultrasound imaging for prostate cancer detection and localization significantly. For example, several studies have shown that CEUS-guided biopsies have the same or higher PCa detection rate compared with systematic biopsies with less biopsies needed.

Materials and methods

This paper describes the current status of CEUS and discusses novel quantification techniques that can improve the accuracy even further. Furthermore, quantification might decrease the user-dependency, opening the door to use in the routine clinical environment. A new generation of targeted microbubbles is now under pre-clinical testing and showed avidly binding to VEGFR-2, a receptor up-regulated in prostate cancer due to angiogenesis. The first publications regarding a targeted microbubble ready for human use will be discussed.

Conclusion

Ultrasound-assisted drug delivery gives rise to a whole new set of therapeutic options, also for prostate cancer. A major breakthrough in the future can be expected from the clinical use of targeted microbubbles for drug delivery for prostate cancer diagnosis as well as treatment.

Contrast-enhanced sonography in pediatrics

Microbubble US contrast agents are composed of an outer shell of protein, phospholipid or polymer that encase air or perfluorocarbon gas. These contrast agents have been widely used in adult cardiology patients to improve endocardial border delineation and have been proved safe and well tolerated in this patient population. There is also a growing body of literature elucidating the value of contrast-enhanced sonography to distinguish benign from malignant liver lesions in adults and to characterize non-hepatic adult malignancies. Because these agents have not been approved for pediatric use in many countries, less is known of the value of contrast-enhanced sonography in children. In this review I will discuss several proven and potential pediatric applications of contrast-enhanced sonography.