Contrast enhanced ultrasound (CEUS) – an unique monitoring technique to assess microvascularization after buried flap transplantation

Experimental study of contrast-enhanced ultrasound in the evaluation of random-pattern flap blood supply in the early postoperative stage in rats

PURPOSE

This study aims to investigate whether contrast-enhanced ultrasound (CEUS) could be used to reveal the status of blood supply of the superficial flap of rat model in the early postoperative stage.

METHODS

One viable and one ischemic random-pattern flap were prepared on the left and right back of the same rat respectively with a number of 40. CEUS examinations were applied within 12 h and 7 days postoperatively, and the quantitative measurements of microvascular blood volume (BV) of the base and the end of both flaps were expressed using acoustic intensity as a ratio to that of the healthy skin.

RESULTS

Within 12 h post operation, there was a smaller BV value of the ischemic ends than that of both the ischemic bases and viable ends (p < 0.001), while no difference was indicated between ischemic bases and viable bases or between viable bases and viable ends. The same result was provided 7 days post operation.

CONCLUSION

Microcirculation of superficial tissues such as random-pattern flaps in this rat model can be assessed quantitatively by CEUS. It could sensitively and accurately reveal the objective status of tissue perfusion in the early postoperative stage.

The discriminatory diagnostic value of multimodal ultrasound combined with blood cell analysis for granulomatous lobular mastitis and invasive ductal carcinoma of the breast

OBJECTIVE

To explore the discriminatory diagnostic value of multimodal ultrasound(US) combined with blood cell analysis (BCA) for Granulomatous Lobular Mastitis (GLM) and Invasive Ductal Carcinoma (IDC) of the breast.

METHODS

A total of 157 breast disease patients were collected and divided into two groups based on postoperative pathological results: the GLM group (57 cases with 57 lesions) and the IDC group (100 cases with 100 lesions). Differences in multimodal ultrasound features and the presence of BCA were compared between the two groups. The receiver operating characteristic (ROC) curve was used to calculate the optimal cutoff values, sensitivity, specificity, 95% confidence interval (CI), and the area under the curve (AUC) for patient age, lesion size, lesion resistive index (RI), and white blood cell (WBC) count in BCA. Sensitivity, specificity, positive predictive value, negative predictive value, diagnostic accuracy, and AUC were calculated for different diagnostic methods.

RESULTS

There were statistically significant differences (P < 0.05) observed between GLM and IDC patients in terms of age, breast pain, the factors in Conventional US (lesion size, RI, nipple delineation, solitary/multiple lesions, margin, liquefaction area, growth direction, microcalcifications, posterior echogenicity and abnormal axillary lymph nodes), the factors in CEUS (contrast agent enhancement intensity, enhancement pattern, enhancement range, and crab-like enhancement) and the factors in BCA (white blood cells, neutrophils, lymphocytes and monocytes). ROC curve analysis results showed that the optimal cutoff values for distinguishing GLM from IDC were 40.5 years for age, 7.15 cm for lesion size, 0.655 for lesion RI, and 10.525*109/L for white blood cells. The diagnostic accuracy of conventional US combined with CEUS (US-CEUS) was the highest (97.45%). The diagnostic performance AUCs for US-CEUS, CEUS, and US were 0.965, 0.921 and 0.832, respectively.

CONCLUSION

Multifactorial analysis of multimodal ultrasound features and BCA had high clinical application value in the differential diagnosis of GLM and IDC.

Update of Contrast-enhanced Ultrasound in Musculoskeletal Medicine: Clinical Perspectives - A Review

Contrast-enhanced ultrasound (CEUS) uses an intravascular contrast agent to enhance blood flow signals and assess microcirculation in different parts of the human body. Over the past decade, CEUS has become more widely applied in musculoskeletal (MSK) medicine, and the current review aims to systematically summarize current research on the application of CEUS in the MSK field, focusing on 67 articles published between January 2001 and June 2021 in online databases including PubMed, Scopus, and Embase. CEUS has been widely used for the clinical assessment of muscle microcirculation, tendinopathy, fracture nonunions, sports-related injuries, arthritis, peripheral nerves, and tumors, and can serve as an objective and quantitative evaluation tool for prognosis and outcome prediction. Optimal CEUS parameters and diagnostic cut off values for each disease category remain to be confirmed.

Sentinel lymph node detection by combining nonradioactive techniques with contrast agents: State of the art and prospects

The status of sentinel lymph nodes (SLNs) has a substantial prognostic value because these nodes are the first place where cancer cells accumulate along their spreading route. Routine SLN biopsy ("gold standard") involves peritumoral injections of radiopharmaceuticals, such as technetium-99m, which has obvious disadvantages. This review examines the methods used as "gold standard" analogs to diagnose SLNs. Nonradioactive preoperative and intraoperative methods of SLN detection are analyzed. Promising photonic tools for SLNs detection are reviewed, including NIR-I/NIR-II fluorescence imaging, photoswitching dyes for SLN detection, in vivo photoacoustic detection, imaging and biopsy of SLNs. Also are discussed methods of SLN detection by magnetic resonance imaging, ultrasonic imaging systems including as combined with photoacoustic imaging, and methods based on the magnetometer-aided detection of superparamagnetic nanoparticles. The advantages and disadvantages of nonradioactive SLN-detection methods are shown. The review concludes with prospects for the use of conservative diagnostic methods in combination with photonic tools.

Contrast-enhanced ultrasound with perfusion analysis in patients with venous malformations before and after percutaneous treatment with ethanol-gel

INTRODUCTION

Percutaneous sclerotherapy is a well-established treatment option for venous malformations (VM). A recently established sclerosing agent is ethanol-gel. Aim of this study was to identify, if contrast-enhanced ultrasound (CEUS) with an integrated perfusion analysis allows for differentiation between untreated VM, healthy tissue, and with gelified ethanol treated malformation tissue.

MATERIAL AND METHODS

In this institutional review board approved prospective study symptomatic VM patients underwent CEUS at exactly the same position before and after sclerotherapy with ethanol-gel. Two experienced sonographers performed all examinations after the bolus injection of microbubbles using a multi-frequency probe with 6 -9 MHz of a high-end ultrasound machine. An integrated perfusion analysis was applied in the center of the VM and in healthy, surrounding tissue. For both regions peak enhancement (peak), time to peak (TTP), area under the curve (AUC), and mean transit time (MTT) were evaluated. Wilcoxon signed rank test was executed; p-values <0.05 were regarded statistically significant.

RESULTS

In 23 patients including children (mean age 25.3 years, 19 females) before treatment all identified parameters were significantly higher in the VM center compared to healthy tissue (peak: p < 0.01; TTP: p < 0.01; AUC: p < 0.01; MTT: p < 0.01). Comparing the VM center before and after treatment, TTP (p < 0.02) and MTT (p < 0.01) reduced significantly after sclerotherapy. In surrounding tissue only peak changed after treatment in comparison to pre-treatment results (p = 0.04). Comparing data in the VM center with surrounding tissue after sclerotherapy, results still differed significantly for peak (p < 0.01), TTP (p < 0.01), and AUC (p < 0.01), but assimilated for MTT (p = 0.07).

CONCLUSION

All with CEUS identified parameters seem to be excellent tools for differentiating between VM and healthy tissue. TTP and MTT could distinguish between with ethanol-gel sclerotized VM portions and untreated malformation parts and thereby might assist the monitoring of sclerotherapy with ethanol-gel.

Contrast-Enhanced Ultrasound for Musculoskeletal Applications: A World Federation for Ultrasound in Medicine and Biology Position Paper

This World Federation for Ultrasound in Medicine and Biology position paper reviews the diagnostic potential of ultrasound contrast agents for clinical decision-making and provides general advice for optimal contrast-enhanced ultrasound performance in musculoskeletal issues. In this domain, contrast-enhanced ultrasound performance has increasingly been investigated with promising results, but still lacks everyday clinical application and standardized techniques; therefore, experts summarized current knowledge according to published evidence and best personal experience. The goal was to intensify and standardize the use and administration of ultrasound contrast agents to facilitate correct diagnoses and ultimately to improve the management and outcomes of patients.

Negative pressure-induced hyperemia, a new modality in the monitoring of skin paddle containing free flaps

BACKGROUND

In free tissue transfer, monitoring is paramount to timely detect vascular complications. Although various technical methods have been introduced, clinical flap monitoring and, particularly, capillary refill test (CRT) remain the gold standard. In pale flaps, CRT is challenging as it relies on the color difference between blanched and perfused skin. We proposed a new method of negative pressure-induced hyperemia (NPIH) using handheld electrical negative pressure devices to improve flap monitoring.

METHODS

Forty consecutive patients who received 42 free flaps in our institution were included in the study. Postoperatively, digital photographs were taken during CRT and NPIH, and the color difference (ΔE) was calculated based on the images. Additionally, three surgeons and three nurses evaluated the ease of assessment of capillary refill and NPIH on each flap using five grades.

RESULTS

NPIH yielded a significantly higher color difference than CRT with a mean ΔE of 10.3 ± 3.3 versus 6.8 ± 4.2. Although for CRT, ΔE of 14 flaps was <5 and of seven flaps <3, all flaps had a ΔE of >5 for NPIH. Subjectively, both surgeons and nurses found NPIH in all flaps to be easier to assess with a mean score of 1.1 ± 0.3 versus 1.8 ± 1.1 for CRT. However, some flaps were found to be challenging or not assessable by CRT.

CONCLUSION

NPIH represents a safe, easily applicable, and cheap addition to the established clinical and technical examination methods and may offer advantages over conventional CRT in detecting arterial complications in pale flaps.

Diagnostic accuracy of contrast-enhanced ultrasound (CEUS) in monitoring vascular complications in patients after liver transplantation - diagnostic performance compared with histopathological results

PURPOSE

To analyse the diagnostic performance of contrast-enhanced ultrasound (CEUS) in patients with vascular complications and transplant rejection compared to histopathological results.

MATERIALS AND METHODS

Our study consisted of 45 retrospectively analysed patients that underwent liver transplantations between January 1993 and December 2015 and developed post-transplant vascular complications with transplant rejection. CEUS examinations took place between September 2006 and December 2015. CEUS findings were correlated with histopathological results.

RESULTS

CEUS showed a sensitivity of 61.5%, a specificity of 100.0%, a positive predictive value (PPV) of 100.0% and a negative predictive value (NPV) of 86,5% in the detection of vascular complications with post-transplant rejection. 5 examinations were reported as normal whereas the histopathological result showed a transplant rejection (false-negative).

CONCLUSION

CEUS might be a useful additional non-invasive technique for the assessment of vascular complications with post-transplant rejection in patients after liver transplantation.

Impact of groin flap ischemia-reperfusion on red blood cell micro-rheological parameters in a follow-up study on rats

BACKGROUND

Flap hypoperfusion or ischemia-reperfusion (I/R) may occur during preparation-transposition procedures and by postoperative thrombotic complications. Behind the microcirculatory disturbances micro-rheological alterations are also supposed.

OBJECTIVE

We aimed to investigate the groin flap I/R with following-up micro-rheological parameters.

METHODS

Anesthetized rats were subjected to Control or I/R groups. Groin flaps were prepared bilaterally, pedicled on the superficial epigastric vessels. In Control group the flaps were re-sutured after one hour, while in I/R group microvascular clips were applied on the pedicles for 60 minutes, then the flaps were repositioned. Besides daily wound control, before the operation and on the 1st, 3rd, 5th, 7th and 14th postoperative days blood samples were collected for testing red blood cell (RBC) deformability (rotational ektacytometry) and aggregation (light-transmission aggregometry).

RESULTS

RBC deformability significantly worsened by the 3rd-7th postoperative day in I/R group. RBC aggregation enhanced significantly by the 1st day, in I/R group it remained elevated on the 3rd day as well. In a complicated case with unilateral flap necrosis, RBC deformability and aggregation worsening was outlined from its group (base, 1st, 3rd day).

CONCLUSION

Wound healing affected micro-rheological parameters in the early postoperative period. Flap I/R exacerbated the alterations. The parameters markedly worsened in case of flap necrosis.