Differentiation of Vascular Characteristics Using Contrast-Enhanced Ultrasound Imaging

Ultrasound Imaging Enables Longitudinal Tracking of Vascular Changes that Correlate with Immune Response After Radiotherapy

Background

While immunotherapy shows great promise in patients with triple negative breast cancer, many will not respond to treatment. Radiotherapy has the potential to prime the tumor-immune microenvironment for immunotherapy. However, predicting response is difficult due to tumor heterogeneity across patients, which necessitates personalized medicine strategies that incorporate tumor tracking into the therapeutic approach. Here, we investigated the use of ultrasound (US) imaging of the tumor vasculature to monitor the tumor response to treatment.

Methods

We utilized ultrafast power doppler US to longitudinally track the vascular response to radiotherapy. We used 4T1 (metastatic) and 67NR (non-metastatic) breast cancer models to determine if US measurements corroborate conventional histological analysis of tumor vessels. To evaluate the effects of radiation, tumor volume and vascular index were calculated using US, and the correlation between vascular changes and immune cell infiltration was determined.

Results

US tumor measurements and the quantified vascular response to radiation were confirmed with caliper measurements and immunohistochemistry staining, respectively, demonstrating a proof-of-principle method for non-invasive vascular monitoring. Additionally, we found significant infiltration of CD8 + T cells into irradiated tumors 10 days after radiation, which followed a sustained decline in vascular index and an increase in splenic CD8 + T cells that was first observed 1 day post-radiation.

Conclusions

Our findings reveal that ultrafast power doppler US can evaluate changes in tumor vasculature that are indicative of shifts in the tumor-immune microenvironment. This work may lead to improved patient outcomes through observing and predicting response to therapy.

Superficial Bifurcated Microflow Phantom for High-Frequency Ultrasound Applications

OBJECTIVE

To evaluate and optimize high-frequency ultrasound (HFUS) imaging techniques that visualize the morphology of microscale vasculatures, many studies have used flow phantoms with straight channels. However, the previous phantoms lack the complexity of microvessels to simulate a realistic vascular environment in a shallow depth. This study was aimed at devising a new protocol for fabrication of a microflow phantom with bifurcated geometry at a superficial region.

METHODS

The proposed protocol involved the following features: (i) a bifurcated flow tract model 300 µm in diameter was debossed on the surface of a tissue slab made of polyvinyl alcohol cryogel, and (ii) a wall-less lumen was created via bonding tissue slabs to put a lid on the debossed flow tract. The structure of the created microflow phantom was evaluated using 2-D and 3-D power Doppler imaging with a 30 MHz HFUS modality.

RESULTS

Ultrasound imaging revealed that the desired flow tract with bifurcation was successfully created in the phantom at a depth of 2-5 mm from the ultrasound probe. The diameters of the flow tract measured in the axial direction were 307 ± 3.7 µm in the parent branch and 232 ± 18.2 and 256 ± 23.3 µm in the two daughter branches, respectively.

CONCLUSION

The experiments revealed that the proposed protocol for creating a microscale intricate flow tract with desired dimensions and depth is valid. This new phantom will facilitate further improvement in the ultrasound technologies for the precise visualization of superficial complex vasculatures such as those in skin layers.

Value of Micro Flow Imaging in the Prediction of Adenomatous Polyps

OBJECTIVE

The aim of this study was to assess the value of micro flow imaging (MFI) in distinguishing adenomatous polyps from cholesterol polyps.

METHODS

A total of 143 patients who underwent cholecystectomy for gallbladder polyps were retrospectively analyzed. B-mode ultrasound (BUS), color Doppler flow imaging (CDFI), MFI and contrast-enhanced ultrasound (CEUS) were performed before cholecystectomy. The weighted kappa consistency test was used to evaluate the agreement of vascular morphology among CDFI, MFI and CEUS. Ultrasound image characteristics, including BUS, CDFI and MFI images, were compared between adenomatous polyps and cholesterol polyps. The independent risk factors for adenomatous polyps were selected. The diagnostic performance of MFI combined with BUS in determining adenomatous polyps was compared with CDFI combined with BUS.

RESULTS

Of the 143 patients, 113 cases were cholesterol polyps, and 30 cases were adenomatous polyps. The vascular morphology of gallbladder polyps was more clearly depicted by MFI than CDFI, and it had better agreement with CEUS. Differences in maximum size, height/width ratio, hyperechoic spot and vascular intensity on CDFI and MFI images were significant between adenomatous polyps and cholesterol polyps (p < 0.05). The maximum size, height/width ratio, and vascular intensity on MFI images were independent risk factors for adenomatous polyps. For MFI combined with BUS, sensitivity, specificity and accuracy were 90.00%, 94.69% and 93.70%, respectively. Area under the receiver operating characteristic curve (AUC) of MFI combined with BUS was significantly higher than that of CDFI combined with BUS (AUC = 0.923 vs. 0.784).

CONCLUSION

Compared with CDFI combined with BUS, MFI combined with BUS had higher diagnostic performance in determining adenomatous polyps.

Application of Contrast-enhanced Ultrasound and Bosniak Classification to the Diagnosis of Cystic Renal Masses

BACKGROUND

The Bosniak classification system based on contrast-enhanced computed tomography (CECT) is commonly used for the differential diagnosis of cystic renal masses. Contrastenhanced ultrasound (CEUS) is a relatively novel technique, which has gradually played an important role in the diagnosis of cystic renal cell carcinoma (CRCC) due to its safety and lowest price.

OBJECTIVE

The aim of the study is to investigate the application value of CEUS and Bosniak classification into the diagnosis of cystic renal masses.

METHODS

32 cystic masses from January 2018 to December 2019 were selected. The images of conventional ultrasound (US), CEUS and CECT from subjects confirmed by surgical pathology were retrospectively analyzed. The Bosniak classification system of cystic renal masses was implemented using CEUS and CECT, and the diagnostic ability was compared.

RESULTS

For the 32 cystic masses, postoperative pathology confirmed 11 cases of multilocular CRCC, 15 cases of clear cell carcinoma with hemorrhage, necrosis and cystic degeneration, 5 cases of renal cysts, and 1 case of renal tuberculosis. The Bosniak classification based on CEUS was higher than that based on CECT, and the difference was statistically significant (P = .024). The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of CEUS were comparable to CECT. There was no significant difference observed in the diagnosis of CRCC (P >.05).

CONCLUSION

CEUS combined with Bosniak classification greatly improves the diagnosis of CRCC. CEUS shows a comparable diagnostic ability to CECT. In daily clinical routine, patients who require multiple examinations and present contraindications for CECT can particularly benefit from CEUS.

Quantitative Analysis of Contrast-Enhanced Ultrasound That Can Be Used to Evaluate Angiogenesis during Patellar Tendon Healing in Rats

Objective

To investigate the efficacy of contrast-enhanced ultrasound (CEUS) in quantitatively evaluating angiogenesis during patellar tendon healing in rats.

Methods

A total of 40 Sprague-Dawley rats were used in this study. The patellar tendons of 30 rats (60 limbs) that underwent incision and suture were treated as the operation group and monitored after 7, 14, and 28 days. The normal patellar tendons of 10 rats (20 limbs) were treated as the control group and monitored on day 0. The ultrasound examination was used to evaluate the structure and blood perfusion of the patellar tendon. Immunohistochemistry was used to assess angiogenesis, and the biomechanical test was used to verify functional recovery of the patellar tendon.

Results

The tendons in the operation group were significantly thickened compared with those in the control group (p < 0.01). The peak intensity (PI) in CEUS of the tendons showed a clear difference at each time point after the surgery (p < 0.01). PI increased in the operation group with a maximum on day 7, and then gradually decreased until day 28 when PI was close to the basic intensity (BI) in the control group (p > 0.05). It was consistent with the change of the CD31-positive staining areas representing angiogenesis of the injured patellar tendons. The PI was positively correlated with the CD31-positive staining area fraction (R = 0.849, p < 0.001). The failure load and tensile strength of the repaired patellar tendons in the operation group increased over time. The PI showed negative correlations with the failure load (R = -0.787, p < 0.001) and tensile strength (R = -0.714, p < 0.001).

Conclusion

The PI in CEUS could quantitatively reflect the time-dependent change in the blood supply of the healing site, and the PI correlated with histologic and biomechanical properties of the healing tendon. Quantitative analysis of contrast-enhanced ultrasound could be a useful method to evaluate angiogenesis in healing tendons.

[Differential diagnosis of gallbladder polypoid lesions by micro-flow imaging]

OBJECTIVE

To explore the value of micro-flow imaging (MFI) in evaluating blood flow characteristics and differential diagnosis of gallbladder polypoid lesions.

METHODS

We retrospectively analyzed the clinical data and ultrasound images of 73 patients with gallbladder polypoid lesions, including 24 patients with pathologically confirmed neoplastic polyps (n=24) and 49 with non-neoplastic polyps (n=49). All the patients underwent conventional ultrasound, MFI and contrast enhanced ultrasound (CEUS) before cholecystectomy. The blood flow characteristics of the lesions in color Doppler flow imaging (CDFI) and MFI were compared, and the consistency of the findings by these two modalities with those of CEUS were evaluated by weighted Kappa consistency test. The diagnostic performance of MFI for gallbladder polypoid lesions was assessed.

RESULTS

There were significant differences between MFI and CDFI in the evaluation of blood flow characteristics of gallbladder polypoid lesions (χ²=37.684, P < 0.001). MFI showed better performance than CDFI in displaying the blood flow characteristics of the polyps. The consistency in the findings was 0.118 between CDFI and CEUS and 0.816 between MFI and CEUS. The sensitivity, specificity and accuracy of MFI in distinguishing neoplastic polyps from non-neoplastic polyps were 75.00%, 93.88% and 87.67%, respectively.

CONCLUSION

MFI has a good consistency with CEUS in displaying the blood flow characteristics of gallbladder polypoid lesions and can accurately distinguish neoplastic polyps from non-neoplastic polyps, thus providing new ultrasound diagnostic evidence to support clinical decisions on optimal treatments of gallbladder polypoid lesions.

Testicular Microvascular Flow Is Altered in Klinefelter Syndrome and Predicts Circulating Testosterone

CONTEXT

Experimental studies on Klinefelter syndrome (KS) reported increased intratesticular testosterone (T) levels coexisting with reduced circulating levels. Abnormalities in testicular microcirculation have been claimed; however, no studies investigated in vivo testicular blood flow dynamics in humans with KS.

OBJECTIVE

To analyze the testicular microcirculation in KS by contrast-enhanced ultrasonography (CEUS) and correlate vascular parameters with endocrine function.

DESIGN AND SETTING

Prospective study. University setting.

PATIENTS

Sixty-eight testicular scans, 34 testes from 19 T-naïve subjects with KS and 34 testes from age-matched eugonadal men (control) who underwent CEUS for incidental nonpalpable testicular lesions.

MAIN OUTCOMES

CEUS kinetic parameters.

RESULTS

CEUS revealed slower testicular perfusion kinetics in subjects with KS than in age-matched controls. Specifically, the wash-in time (P = 0.018), mean transit time (P = 0.035), time to peak (P < 0.001), and wash-out time (P = 0.004) were all prolonged. Faster testicular blood flow was associated with higher total T levels. Principal component analysis and multiple linear regression analyses confirmed the findings and supported a role for reduced venous blood flow as independent predictor of total T levels.

CONCLUSIONS

Testicular venous blood flow is altered in KS and independently predicts T peripheral release.

MOFs-Based Nitric Oxide Therapy for Tendon Regeneration

Tendon regeneration is still a great challenge due to its avascular structure and low self-renewal capability. The nitric oxide (NO) therapy emerges as a promising treatment for inducing the regeneration of injured tendon by angiogenesis. Here, in this study, a system that NO-loaded metal-organic frameworks (MOFs) encapsulated in polycaprolactone (PCL)/gelatin (Gel) aligned coaxial scaffolds (NMPGA) is designed and prepared for tendon repair. In this system, NO is able to be released in vitro at a slow and stable average speed of 1.67 nM h^-1 as long as 15 d without a burst release stage in the initial 48 h. Furthermore, NMPGA can not only improve the tubular formation capability of endothelial cells in vitro but also obviously increase the blood perfusion near the injured tendon in vivo, leading to accelerating the maturity of collagen and recovery of biomechanical strength of the regenerated tendon tissue. As a NO-loaded MOFs therapeutic system, NMPGA can promote tendon regeneration in a shorter healing period with better biomechanical properties in comparison with control group by angiogenesis. Therefore, this study not only provides a promising scaffold for tendon regeneration, but also paves a new way to develop a NO-based therapy for biomedical application in the future.