Contrast-enhanced ultrasound using a time-intensity curve for the diagnosis of renal cell carcinoma

Evaluation of Renal Masses Using Contrast-Enhanced Ultrasound with Sonovue and Sonazoid

OBJECTIVE

To explore the differences between SonoVue and Sonazoid contrast-enhanced ultrasound (CEUS) in evaluating enhancement features of renal masses and determine the diagnostic value of CEUS in clear cell renal cell carcinoma (ccRCC).

METHODS

A total of 57 eligible patients were enrolled and divided into the ccRCC, papillary renal cell carcinoma (pRCC), non-ccRCC and non-pRCC malignancy groups, and benign mass groups based on their postsurgical histopathologic diagnosis. The enhancement features of renal masses following SonoVue and Sonazoid CEUS in each group were analyzed. Diagnostic efficiencies of SonoVue and Sonazoid CEUS for ccRCC and non-ccRCC were determined.

RESULTS

There were no significant differences in the enhancement features of renal masses with SonoVue and Sonazoid imaging in the four groups (p > .05). Both SonoVue CEUS and Sonazoid CEUS showed good diagnostic performance for the differential diagnosis of ccRCC and non-ccRCC, with sensitivities of 88.6% and 85.7%, specificities of 76.5% and 88.2%, accuracies of 84.6% and 86.5%, positive predictive values of 88.6% and 93.8%, and negative predictive values of 76.5% and 75%, respectively. There were no statistically significant differences in any of the diagnostic performance indices between the two methods (p > .05).

CONCLUSION

The CEUS features of SonoVue and Sonazoid in evaluating renal masses were similar in the vascular phase. Both SonoVue and Sonazoid CEUS showed good diagnostic performance for the differential diagnosis of ccRCC and non-ccRCC.

Spatiotemporal analysis of contrast-enhanced ultrasound for differentiating between malignant and benign breast lesions

OBJECTIVES

The aim of this study was to apply spatiotemporal analysis of contrast-enhanced ultrasound (CEUS) loops to quantify the enhancement heterogeneity for improving the differentiation between benign and malignant breast lesions.

MATERIALS AND METHODS

This retrospective study included 120 women (age range, 18-82 years; mean, 52 years) scheduled for ultrasound-guided biopsy. With the aid of brightness-mode images, the border of each breast lesion was delineated in the CEUS images. Based on visual evaluation and quantitative metrics, the breast lesions were categorized into four grades of different levels of contrast enhancement. Grade-1 (hyper-enhanced) and grade-2 (partly-enhanced) breast lesions were included in the analysis. Four parameters reflecting enhancement heterogeneity were estimated by spatiotemporal analysis of neighboring time-intensity curves (TICs). By setting the threshold on mean parameter, the diagnostic performance of the four parameters for differentiating benign and malignant lesions was evaluated.

RESULTS

Sixty-four of the 120 patients were categorized as grade 1 or 2 and used for estimating the four parameters. At the pixel level, mutual information and conditional entropy present significantly different values between the benign and malignant lesions (p < 0.001 in patients of grade 1, p = 0.002 in patients of grade 1 or 2). For the classification of breast lesions, mutual information produces the best diagnostic performance (AUC = 0.893 in patients of grade 1, AUC = 0.848 in patients of grade 1 or 2).

CONCLUSIONS

The proposed spatiotemporal analysis for assessing the enhancement heterogeneity shows promising results to aid in the diagnosis of breast cancer by CEUS.

CLINICAL RELEVANCE STATEMENT

The proposed spatiotemporal method can be developed as a standardized software to automatically quantify the enhancement heterogeneity of breast cancer on CEUS, possibly leading to the improved diagnostic accuracy of differentiation between benign and malignant lesions.

KEY POINTS

• Advanced spatiotemporal analysis of ultrasound contrast-enhanced loops for aiding the differentiation of malignant or benign breast lesions. • Four parameters reflecting the enhancement heterogeneity were estimated in the hyper- and partly-enhanced breast lesions by analyzing the neighboring pixel-level time-intensity curves. • For the classification of hyper-enhanced breast lesions, mutual information produces the best diagnostic performance (AUC = 0.893).

Comparing Sonazoid contrast-enhanced ultrasound to contrast-enhanced CT and MRI for differentially diagnosing renal lesions: a prospective multicenter study

PURPOSE

To evaluate the diagnostic performance of contrast-enhanced (CE) ultrasound using Sonazoid (SNZ-CEUS) by comparing with contrast-enhanced computed tomography (CE-CT) and contrast-enhanced magnetic resonance imaging (CE-MRI) for differentiating benign and malignant renal masses.

MATERIALS AND METHODS

306 consecutive patients (from 7 centers) with renal masses (40 benign tumors, 266 malignant tumors) diagnosed by both SNZ-CEUS, CE-CT or CE-MRI were enrolled between September 2020 and February 2021. The examinations were performed within 7 days, but the sequence was not fixed. Histologic results were available for 301 of 306 (98.37%) lesions and 5 lesions were considered benign after at least 2 year follow-up without change in size and image characteristics. The diagnostic performances were evaluated by sensitivity, specificity, positive predictive value, negative predictive value, and compared by McNemar's test.

RESULTS

In the head-to-head comparison, SNZ-CEUS and CE-MRI had comparable sensitivity (95.60 vs. 94.51%, P = 0.997), specificity (65.22 vs. 73.91%, P = 0.752), positive predictive value (91.58 vs. 93.48%) and negative predictive value (78.95 vs. 77.27%); SNZ-CEUS and CE-CT showed similar sensitivity (97.31 vs. 96.24%, P = 0.724); however, SNZ-CEUS had relatively lower than specificity than CE-CT (59.09 vs. 68.18%, P = 0.683). For nodules > 4 cm, CE-MRI demonstrated higher specificity than SNZ-CEUS (90.91 vs. 72.73%, P = 0.617) without compromise the sensitivity.

CONCLUSIONS

SNZ-CEUS, CE-CT, and CE-MRI demonstrate desirable and comparable sensitivity for the differentiation of renal mass. However, the specificity of all three imaging modalities is not satisfactory. SNZ-CEUS may be a suitable alternative modality for patients with renal dysfunction and those allergic to gadolinium or iodine-based agents.

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

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

Contrast-Enhanced Ultrasound with Optimized Aperture Patterns and Bubble Segmentation Based on Echo Phase

Amplitude modulation (AM) suppresses tissue signals and detects microbubble signals in contrast-enhanced ultrasound (CEUS) and is often implemented with checkerboard apertures. However, possible crosstalk between transmitting and non-transmitting array elements may compromise tissue suppression in AM. Using AM aperture patterns other than the conventional checkerboard approach (one on, one off) may reduce the degree of crosstalk and increase the contrast-to-tissue-ratio (CTR) compared with conventional AM. Furthermore, previous studies have reported that the phase difference between the echoes in AM pulsing sequences may be used to segment tissue and microbubbles and improve tissue signal suppression and the CTR of CEUS images. However, the CTR of the image produced by alternative AM aperture patterns and the effect of segmentation approach on these alternative apertures have not been investigated. We evaluated a number of AM aperture patterns to find an optimal AM aperture pattern that provides the highest CTR. We found that the aperture that uses alternating groups of two elements, AM2, had the highest CTR for the probe evaluated. In addition, a segmentation technique based on echo phase differences (between the full and half-pulses, ΔΦAM, between the complementary half-pulses, ΔΦhalf, and the maximum of the two ΔΦmax) was also considered in the AM aperture optimization process. The segmentation approach increases the CTR by about 25 dB for all apertures. Finally, AM2 segmented with ΔΦmax had a 7-dB higher CTR in a flow phantom and a 6-dB higher contrast in a perfused pig liver than conventional AM segmented with ΔΦAM, and it is the optimal transmit aperture design.

The quantitative evaluation of contrast-enhanced ultrasound in the differentiation of small renal cell carcinoma subtypes and angiomyolipoma

Background

Contrast-enhanced ultrasound (CEUS) has been widely used for renal lesion diagnosis and differential diagnosis. However, qualitative analysis of CEUS is subject to examinations with low reproducibility. This study aims to investigate the diagnostic value of CEUS quantitative parameters in differentiating small renal cell carcinoma (RCC) subtypes and angiomyolipoma (AML).

Methods

A retrospective analysis was performed on 97 cases of a small renal mass undergoing a CEUS before a radical or partial nephrectomy procedure. A region of interest (ROI) was placed in the tumor's maximum enhanced region (ROI_max) as much as possible, and adjacent renal cortex (ROI_refer) was selected from normal renal tissue around a mass of the same depth. The time-intensity curve (TIC) was used to analyze the ROI_max and the ROI_refer of the tumors quantitatively. Then the parameters of the ROI_max and the ROI_refer, including the differences between the parameters of the ROI_max and the ROI_refer, were analyzed statistically.

Results

In RCC and clear cell renal cell carcinoma (ccRCC), the peak intensity (PI), slope (SL), area under the curve (AUC), area under the wash-in curve (AWI), area under the wash-out curve (AWO), time to peak intensity (TTP) and the mean transit time (MTT) were statistically significant between ROI_max and ROI_refer (all P=0.000). The △PI (△PI = PI_max - PI_refer), △SL (△SL = SL_max - SL_refer), △AUC (△AUC = AUC_max - AUC_refer), △AWI (△AWI = AWI_max - AWI_refer) and △AWO (△AWO = AWO_max - AWO_refer) of RCC were significantly higher than in AML (P=0.007, 0.000, 0.003, 0.048, 0.009, respectively), while the TTP (△TTP = TTP_max - TTP_refer) and △MTT (△MTT = MTT_max - MTT_refer) of RCC were significantly lower (both P=0.000). In comparison with papillary renal cell carcinoma (pRCC) and chromophobe renal cell carcinoma (chRCC), the △PI, △SL, △AUC and △AWO of ccRCC were all larger (all P<0.05). The sensitivity, specificity, and AUC of the combination of parameter difference for differentiating RCC from AML were 100%, 81.2%, and 0.965, respectively, and for differentiating ccRCC from pRCC and chRCC, 85.71%, 85.92% and 0.911, respectively.

Conclusions

CEUS quantitative parameters have value in differentiating small RCC from AML and distinguishing ccRCC from pRCC and chRCC.

Use of Contrast Ultrasound for Renal Mass Evaluation

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

Can contrast enhanced ultrasound differentiate benign cystic nephroma from malignant multicystic renal lesions? A case report

Multicystic renal lesions pose a diagnostic dilemma and standard imaging may not be able to differentiate between benign or malignant lesions. Adult cystic nephroma and multicystic renal cell carcinoma are two such cystic renal lesions.

We describe the appearance of cystic nephroma using contrast enhanced ultrasound. We hypothesize how quantitative parameters using time intensity curves appear to be able to distinguish between cystic nephroma and other malignant lesions such as multicystic renal cell carcinoma.

This differentiation is of importance as it may obviate the need for tissue sampling and allow the clinician to recommend conservative management rather than nephrectomy.

Value of Contrast-Enhanced Ultrasound in the Diagnosis of Renal Cancer and in Comparison With Contrast-Enhanced Computed Tomography: A Meta-analysis

OBJECTIVES

The purpose of this meta-analysis was to assess the diagnostic accuracy of contrast-enhanced ultrasound (CEUS) in renal cancer and to compare it with contrast-enhanced computed tomography (CECT).

METHODS

A systematic search was performed to recruit eligible original studies published until December 2017. Two reviewers independently extracted data. A meta-analysis was performed, and the pooled sensitivity, specificity, positive and negative likelihood ratios, positive and negative predictive values, diagnostic odds ratio, summary receiver operating characteristic curve, and area under the curve were calculated. The extent and potential sources of heterogeneity were further explored. Moreover, a head-to-head comparison was also performed to compare the diagnostic value between CEUS and CECT in renal cancer.

RESULTS

Twenty-two studies were included in this meta-analysis. The summary sensitivity and specificity of CEUS for detecting renal cancer were 0.96 (95% confidence interval [CI], 0.94-0.97) and 0.82 (95% CI, 0.74-0.88), respectively. The summary diagnostic odds ratio was 102.04 (95% CI, 49.55-210.13). The area under the summary receiver operating characteristic curve was 0.97 (95% CI, 0.95-0.98). In the head-to-head comparison, CEUS showed higher diagnostic sensitivity than CECT (0.94 versus 0.85) for renal cancer, whereas the specificities were comparable between CEUS and CECT (0.77 versus 0.75).

CONCLUSIONS

Contrast-enhanced US has high sensitivity and moderate specificity in the differential diagnosis of renal cancer. The diagnostic sensitivity of CEUS in renal cancer was higher than that of CECT, suggesting that CEUS could be used as a preferred diagnostic tool for renal cancer.

Quantitative, noninvasive assessment of intra- and extraocular perfusion by contrast-enhanced ultrasonography and its clinical applicability in healthy dogs

Objective

To assess quantitative perfusion of intra‐ and extraocular regions of interest (ROIs) in conscious, healthy dogs utilizing contrast‐enhanced ultrasonography (CEUS); to compare varying enhancement with the first and second bolus injection and in the right and left eye; and to determine the most appropriate examination time.

Procedures

Gray scale ultrasonography and contrast harmonic imaging using sulfur hexafluoride were performed randomly assigned in both eyes in 10 university‐owned beagles. Perfusion parameters including slope time, time to peak (TTP), peak intensity (PI), and area under the curve (AUC) were measured at individually drawn ROIs (retrobulbar cone = ROI 1, choroid‐retina complex = ROI 2, medial = ROI 3, and lateral anterior uvea = ROI 4).

Results

Time‐intensity curve parameters revealed no significant differences in eyes examined by the first or second bolus injection (P > 0.05) or in the right or left eye (P > 0.05). Pooled data from all eyes were analyzed. Peak intensity of ROI 2 was significantly higher compared to all other ROIs (P < 0.001). Area under the curve at ROI 2 was significantly higher compared to all other ROIs (P < 0.05), and AUC at ROI 1 was significantly higher than at ROI 4 (P < 0.05). No significant differences in TTP were observed between different ROIs (P > 0.05). Ratios relative to different ROI sizes showed fastest enhancement in the retrobulbar cone and most intense perfusion in the anterior uveal regions. The first minute after contrast injection provided the highest diagnostic value.

Conclusion

Quantitative perfusion in nondiseased canine eyes revealed consistent parameters. Application of standardized CEUS protocols may be a promising diagnostic tool to differentiate ocular lesions.

Triparametric ultrasound in differentiating multicystic renal masses: a rare presentation of unilateral focal renal lymphangioma

We describe a rare case of renal lymphangioma presenting as a focal unilateral multicystic renal mass and document the first reported use of triparametric ultrasound (B-mode, Doppler, and contrast-enhanced ultrasound) in its diagnosis and discrimination from other focal multicystic lesions. Renal lymphangiomas are rare, benign, typically developmental lesions composed of cystic dilatation of the lymphatic ducts, usually occurring bilaterally as perinephric collections or parapelvic cysts mimicking hydronephrosis. Radiologists have an important role in suggesting the diagnosis, as clinical presentation can be nonspecific. Management is usually conservative; however, nephron-sparing surgery may be recommended in symptomatic individuals.

An evaluation of the clinical diagnostic value of contrast-enhanced ultrasound combined with contrast-enhanced computed tomography in space-occupying lesions of the kidney

BACKGROUND

There are a variety of space-occupying lesions of the kidney, and the benign lesions may be difficult to differentiate from the malignant ones. Therefore, an accurate judgment of the benign and malignant nature of the space-occupying lesions of the kidney is of high importance for the treatment and prognosis of these patients.

OBJECTIVE

To evaluate the diagnostic value of contrast-enhanced ultrasound (CEUS) combined with contrast-enhanced computed tomography (CECT) in space-occupying lesions of the kidney.

DATA AND METHODS

Three hundred and sixty-seven patients with space-occupying lesions of the kidney (378 lesions) were examined by CEUS and CECT, respectively, then, a combined diagnosis was made after the combination of CEUS and CECT by a multidisciplinary team. The diagnoses from the three methods were compared. The pathological results were taken as the gold standard. The sensitivity, specificity, positive and negative predictive values and area under the receiver operating characteristic (ROC) curve were calculated for the three methods. Thus, the diagnostic value of the three methods was assessed.

RESULTS

Of the 378 lesions examined, there were 301 malignant lesions and 77 benign lesions. The combined examination revealed 303 malignant lesions, with 9 benign lesions mistakenly diagnosed as malignant ones; thus, the misdiagnosis rate was 11.7%. By using the combined examination, 75 benign lesions were diagnosed, with the missed diagnosis of 7 malignant lesions, so the missed diagnosis rate was 2.3%. The sensitivity, specificity, positive and negative predictive values and area under the ROC curve with the combined examination of CEUS and CECT were 97.67% (0.950-0.989), 88.31% (0.785-0.942), 97.03% (0.942-0.985), 90.67% (0.811-0.958) and 0.930 (0.887-0.973), respectively. As compared with either CEUS or CECT alone, the difference in these indicators was of statistical significance (P<0.05). The combined examination greatly improved the sensitivity, specificity and accuracy of the diagnosis of the space-occupying lesions of the kidney.

CONCLUSION

CEUS and CECT each have advantages and disadvantages in the diagnosis of the space-occupying lesions of the kidney. The two techniques can be used in combination to compensate for the respective defects. More salient benefits can be reaped from the combined examination than from either technique used alone.

Computer-Aided Diagnosis of Focal Liver Lesions Using Contrast-Enhanced Ultrasonography With Perflubutane Microbubbles

This paper proposes an automatic classification method based on machine learning in contrast-enhanced ultrasonography (CEUS) of focal liver lesions using the contrast agent Sonazoid. This method yields spatial and temporal features in the arterial phase, portal phase, and post-vascular phase, as well as max-hold images. The lesions are classified as benign or malignant and again as benign, hepatocellular carcinoma (HCC), or metastatic liver tumor using support vector machines (SVM) with a combination of selected optimal features. Experimental results using 98 subjects indicated that the benign and malignant classification has 94.0% sensitivity, 87.1% specificity, and 91.8% accuracy, and the accuracy of the benign, HCC, and metastatic liver tumor classifications are 84.4%, 87.7%, and 85.7%, respectively. The selected features in the SVM indicate that combining features from the three phases are important for classifying FLLs, especially, for the benign and malignant classifications. The experimental results are consistent with CEUS guidelines for diagnosing FLLs. This research can be considered to be a validation study, that confirms the importance of using features from these phases of the examination in a quantitative manner. In addition, the experimental results indicate that for the benign and malignant classifications, the specificity without the post-vascular phase features is significantly lower than the specificity with the post-vascular phase features. We also conducted an experiment on the operator dependency of setting regions of interest and observed that the intra-operator and inter-operator kappa coefficients were 0.45 and 0.77, respectively.

A Pilot Clinical Study in Characterization of Malignant Renal-cell Carcinoma Subtype with Contrast-enhanced Ultrasound

Malignant renal cell carcinoma (RCC) is a diverse set of diseases, which are independently difficult to characterize using conventional MRI and CT protocols due to low temporal resolution to study perfusion characteristics. Because different disease subtypes have different prognoses and involve varying treatment regimens, the ability to determine RCC subtype non-invasively is a clinical need. Contrast-enhanced ultrasound (CEUS) has been assessed as a tool to characterize kidney lesions based on qualitative and quantitative assessment of perfusion patterns, and we hypothesize that this technique might help differentiate disease subtypes. Twelve patients with RCC confirmed pathologically were imaged using contrast-enhanced ultrasound. Time intensity curves were generated and analyzed quantitatively using 10 characteristic metrics. Results showed that peak intensity ( p = 0.001) and time-to-80% on wash-out ( p = 0.004) provided significant differences between clear cell, papillary, and chromophobe RCC subtypes. These results suggest that CEUS may be a feasible test for characterizing RCC subtypes.

Characterization of histological subtypes of clear cell renal cell carcinoma using contrast-enhanced ultrasound (CEUS)

INTRODUCTION

The aim of this study was to analyze the histological subtypes of clear cell renal cell carcinoma (RCC) examined by means of contrast-enhanced ultrasound (CEUS) and a second generation blood pool agent (SonoVue®, Bracco, Milan, Italy) during the pre-operative phase.

MATERIALS AND METHODS

29 patients with histologically proven subtypes of clear cell RCC were examined. A total of three patients were diagnosed with highly differentiated clear cell RCC, 21 out of 29 cases with moderately differentiated clear cell RCC and five out of 29 patients had insufficiently differentiated clear cell RCC. An experienced radiologist examined the patients with CEUS. The following parameters were analyzed: maximum signal intensity (PEAK), time elapsed until PEAK is reached (MTT), local blood flow (RBF), area under the time intensity curve (AUC) and the signal intensity (SI) during the course of time. For the groups all comparisons are made based on healthy renal parenchyma.

RESULTS

In the clear cell RCC significant differences (significance level p < 0.05) between cancerous tissue and the healthy renal parenchyma were noticed in all four parameters. Therefore, the clear cell RCC stands out due to its reduced blood volume. However, it reached the PEAK reading relatively rapidly and its signal intensity was always lower than that of the healthy renal parenchyma. In the arterial phase retarded absorption of the contrast agent was observed, followed by fast washing out of the contrast agent bubbles.In all three histological subgroups no significant differences were noticed in PEAK and SI. However, the diagrams showed the possible bias, that the group of the insufficiently differentiated clear cell RCC had the highest PEAK-value and the highest signal intensity when compared with highly and moderately differentiated clear cell RCC.

CONCLUSION

Our study suggests that CEUS may be an additional tool for non-invasive characterisation and differentiation of the three histological subtypes of clear cell RCC. Furthermore, it seems to have an additional diagnostic value in daily clinical.

Quantitative contrast-enhanced ultrasonography for the differential diagnosis of endometrial hyperplasia and endometrial neoplasms

The present study aimed to investigate the feasibility of applying contrast-enhanced ultrasonography (CEUS) imaging technology for distinguishing between benign and malignant endometrial lesions, and to screen markers that could be correlated with the pathological results. In this study, endometrial diseases were diagnosed by biopsy under hysteroscopy and CEUS examinations. The intensity and time parameters of the time-intensity curve (TIC) were analyzed. The mean arrival time (AT), time-to-peak (TTP), rise time (RT), washout half-time and clearance half-time of malignant lesions were shorter than those of benign lesions (P<0.05), whereas the average peak intensity (PI) and enhancement intensity (EI) of malignant lesions were higher than those of benign lesions (P<0.05). The receiver operating characteristic curve showed the following cut-off values: PI, 29.2 dB; EI, 21.35 dB; AT, 12.75 sec; TTP, 26.75 sec; RT, 13.2 sec; clearance half-time, 89.3 sec; and washout half-time, 75.45 sec. The lesions with PI, an EI higher than that of the cut-off and lesions with an AT, TTP, RT, half clearing time and washout half-time shorter than the cut-off were considered malignant. The TTP, RT and half clearing time were negatively correlated with microvessel density (MVD), i.e., MVD was higher when the TTP, RT and half clearing time were shorter. Overall, changes in the enhancement and clearing of lesions could be quantitatively analyzed by CEUS TIC and further discriminate benign from malignant lesions. In the present study, CEUS appeared to indirectly reflect blood vessel changes inside the lesions and provided a pre-operative non-invasive fast imaging method for the diagnosis of endometrial disease.

Quantitative assessment of solid renal masses by contrast-enhanced ultrasound with time-intensity curves: how we do it

PURPOSE

To discuss the evaluation of the enhancement curve over time of the major renal cell carcinoma (RCC) subtypes, oncocytoma, and lipid-poor angiomyolipoma, to aid in the preoperative differentiation of these entities. Differentiation of these lesions is important, given the different prognoses of the subtypes, as well as the desire to avoid resecting benign lesions.

METHODS

We discuss findings from CT, MR, and US, but with a special emphasis on contrast-enhanced ultrasound (CEUS). CEUS technique is described, as well as time-intensity curve analysis.

RESULTS

Examples of each of the major RCC subtypes (clear cell, papillary, and chromophobe) are shown, as well as examples of oncocytoma and lipid-poor angiomyolipoma. For each lesion, the time-intensity curve of enhancement on CEUS is reviewed, and correlated with the enhancement curve over time reported for multiphase CT and MR.

CONCLUSIONS

Preoperative differentiation of the most common solid renal masses is important, and the time-intensity curves of these lesions show some distinguishing features that can aid in this differentiation. The use of CEUS is increasing, and as a modality it is especially well suited to the evaluation of the time-intensity curve.

Quantitative evaluation of contrast-enhanced ultrasound for differentiation of renal cell carcinoma subtypes and angiomyolipoma

PURPOSE

To investigate the value of quantitative parameters of contrast-enhanced ultrasound (CEUS) in the differentiation of subtypes of renal cell carcinoma (RCC) and angiomyolipoma (AML).

METHODS

The quantitative characteristics of 341 RCCs and 88 AMLs were analyzed with quantitative software (SonoLiver). Quantitative analysis was conducted in the whole tumor (ROItumor) and the maximum enhanced area of the tumor (ROImax), acquiring the parameters of maximum intensity (IMAX), rise time (RT), time to peak (TTP), mean transit time (mTT), and area under the curve (AUC), were derived and analyzed. The difference values between ROImax and normal renal cortex (ΔPar.s, including ΔIMAX, ΔRT, ΔTTP, ΔmTT, ΔAUC) were compared among renal histotypes.

RESULTS

All time-related parameters (including RT, TTP and mTT) of ROImax were shorter than the corresponding parameters of ROItumor in RCC subtypes (all p<0.05), but made no statistical difference in AMLs (all p>0.05). There were significant differences of all ΔPar.s among RCC subtypes and AML (all p<0.01). ΔIMAX and ΔAUC showed the trend that ccRCC>AML>pRCC=chRCC. ΔTTP showed AML=pRCC=chRCC>ccRCC, ΔRT and ΔmTT showed AML>pRCC=chRCC=ccRCC. ΔmTT could distinguish RCC from AML with the area under the ROC curve (AUC) of 0.86. The AUC of ΔIMAX and ΔAUC was 0.89 and 0.92 vs 0.85 and 0.85 for discriminating between pRCC (or chRCC) and AML vs ccRCC and AML.

CONCLUSIONS

Quantitative analysis of CEUS is a useful modality in AML and RCC subtypes' differentiation, by using ΔmTT, ΔIMAX and ΔAUC.

Quantitative Assessment of Tissue Perfusion in Hepatocellular Carcinoma Using Perflubutane Dynamic Contrast-Enhanced Ultrasonography: A Preliminary Study

Our purpose in this study was to assess the relationship between contrast signal intensity (CI) and concentration of perflubutane microbubbles in a phantom experiment, and to examine the feasibility of this technique for quantitative analysis of vascularity in hepatocellular carcinoma (HCC). Microbubble solutions of the perflubutane contrast agent were prepared by mixing with purified water. We examined the relationship between CI in dB units and the concentration. Moreover, seven HCC patients were examined using real-time dynamic contrast imaging. The perfusion index was calculated from time-intensity curves generated for both HCC and surrounding liver parenchyma. We observed a linear relationship between the CI_dB and the concentration in the phantom study and a higher perfusion index in the HCC lesions relative to the surrounding liver parenchyma. Dynamic contrast-enhanced ultrasonography with perflubutane microbubbles, which exhibit linear and temporally stable characteristics under continuous ultrasound exposure, allows the collection of quantitative hemodynamic information regarding HCC.

The status of contemporary image-guided modalities in oncologic surgery

OBJECTIVE

To review the current trends in optical imaging to guide oncologic surgery.

BACKGROUND

Surgical resection remains the cornerstone of therapy for patients with early stage solid malignancies and more than half of all patients with cancer undergo surgery each year. The technical ability of the surgeon to obtain clear surgical margins at the initial resection remains crucial to improve overall survival and long-term morbidity. Current resection techniques are largely based on subjective and subtle changes associated with tissue distortion by invasive cancer. As a result, positive surgical margins occur in a significant portion of tumor resections, which is directly correlated with a poor outcome.

METHODS

A comprehensive review of studies evaluating optical imaging techniques is performed.

RESULTS

A variety of cancer imaging techniques have been adapted or developed for intraoperative surgical guidance that have been shown to improve functional and oncologic outcomes in randomized clinical trials. There are also a large number of novel, cancer-specific contrast agents that are in early stage clinical trials and preclinical development that demonstrate significant promise to improve real-time detection of subclinical cancer in the operative setting.

CONCLUSIONS

There has been an explosion of intraoperative imaging techniques that will become more widespread in the next decade.

Qualitative and quantitative analysis with contrast-enhanced ultrasonography: diagnosis value in hypoechoic renal angiomyolipoma

Objective

To evaluate the value of enhancement features and quantitative parameters of contrast-enhanced ultrasonography (CEUS) in differentiating solid hypoechoic renal angiomyolipomas (AMLs) from clear cell renal cell carcinomas (ccRCCs).

Materials and Methods

We analyzed the enhancement features and quantitative parameters of CEUS in 174 hypoechoic renal masses (32 AMLs and 142 ccRCCs) included in the study.

Results

Centripetal enhancement pattern was more common in AMLs than in ccRCCs on CEUS (71.9% vs. 23.2%, p < 0.001). At peak enhancement, all AMLs showed homogeneous enhancement (100% in AML, 27.5% in ccRCCs; p < 0.001). Quantitative analysis showed no significant difference between rise time and time to peak. Tumor-to-cortex (TOC) enhancement ratio in AMLs was significantly lower than that in ccRCCs (p < 0.001). The criteria of centripetal enhancement and homogeneous peak enhancement together with TOC ratio < 91.0% used to differentiate hypoechoic AMLs from ccRCCs resulted in a sensitivity and specificity of 68.9% and 95.8%, respectively.

Conclusion

Both qualitative and quantitative analysis with CEUS are valuable in the differential diagnosis of hypoechoic renal AMLs from ccRCCs.

Quantification of enhancement of renal parenchymal masses with contrast-enhanced ultrasound

The purpose of this study was to investigate the value of quantitative assessment of enhancement in diagnosing renal cell carcinoma (RCC) with contrast-enhanced ultrasound (CEUS). A total of 73 solid renal parenchymal masses underwent both conventional ultrasound and CEUS. We compared the difference in maximum diameters on conventional ultrasound and CEUS between the benign and malignant groups. Enhancement features derived from a time-intensity curve were also analyzed. The diameters of renal cancer were found to be larger on CEUS than on conventional ultrasound (p < 0.05). When cutoff values of 4.74 s for washout time and 8.52% for enhancement intensity at 60 s for diagnosing RCCs were applied, the sensitivity, specificity and area under the receiver operating characteristic curve were 67.3%, 95.2%, 86.5% and 65.4%, 81.0%, 68.4%, respectively. The sensitivity and specificity for these two enhancement characteristics combined as a criterion for differentiating RCCs from benign lesions were 44.0% and 99.1%, respectively. Early washout in the area of maximal intensity in the interior of the lesion and prolonged washout in the whole area of the lesion are specific CEUS manifestations suggestive of RCC.

Evaluation of renal masses with contrast-enhanced ultrasound

The clinical need for characterising small renal masses (SRMs) is increasing due to their rising incidental detection. This increase is especially seen in younger and older generations and concerns mainly SRMs. Diagnostics is mainly made by contrast-enhanced CT or MRI. However, these imaging methods fail to accurately distinguishing benign from malignant SRMs. Other disadvantages of CT or MRI are high costs, the use of ionizing radiation, nephrotoxicity induced by iodine contrast agents or nephrogenic systemic fibrosis (NSF) induced by gadolinium contrast agents. Contrast-enhanced ultrasound (CEUS) is based on ultrasonography and microbubbles to real-time visualize the renal blood flow without the use of nephrotoxic agents or ionizing radiation. This comprehensive review evaluates the capabilities of CEUS in the diagnostics of benign (angiomyolipomas, cysts, oncocytomas, pseudotumors) and malignant masses (renal cell carcinomas), and focuses on possible future treatment.