Discrimination between newly formed and aged thrombi using empirical mode decomposition of ultrasound B-scan image

Precision Navigation of Venous Thrombosis Guided by Viscosity-Activatable Near-Infrared Fluorescence

Thrombus are blood clots formed by abnormal hemostasis in blood vessels and are closely associated with various diseases such as pulmonary embolism, myocardial infarction and stroke. Early diagnosis and treatment of thrombus is the key to reducing the high risk of thrombotic disease. Given that early thrombus is small in early size, free instability, wide regional distribution and fast formation, it is urgent to develop all-inclusive detection methods that combine high signal-to-noise ratio, in situ dynamic and rapid in-depth tissue imaging. Near-infrared (NIR) fluorescence imaging, with its excellent high spatiotemporal resolution and tissue penetration depth, is a powerful technique for direct visualization of thrombotic events in situ. Considering the fibrin highly expressed in the thrombus is a typical thrombotic target. Moreover, the viscosity of the thrombus is markedly higher than its surroundings. Therefore, we developed a fibrin-targeting and viscosity-activating thrombus NIR fluorescent probe (TIR-V) for high-resolution and high-sensitivity in situ lighten-up thrombus. TIR-V has the advantages of good thrombus targeting, significant "off-on" fluorescence specific response to viscosity, bright NIR fluorescence and good biocompatibility. The thrombus is clearly delineated by a high signal-to-noise ratio NIR fluorescence imaging, enabling imaging detection and precise navigation of thrombotic regions. This work demonstrates the potential of TIR-V as a bifunctional probe for definitive diagnostic imaging and direct navigation of thrombotic lesions in clinical applications.

Morphologic change in deep venous thrombosis in the lower extremity after therapeutic anticoagulation

Background

To evaluate the anticoagulant treatment response in venous thrombi with different morphologies (size, shape, and echogenicity) by measuring the change in thrombus thickness.

Materials and methods

This was a retrospective cohort study of 97 lower extremity DVT patients diagnosed by venous ultrasound between March 2014 and February 2018. The demographics, clinical risk factors, anticoagulant treatment, and ultrasound findings at the first diagnosis and 2–6 months after treatment were evaluated.

Results

The anticoagulant treatment with LMWH followed by VKAs showed a significant decrease in the mean maximum difference in lower extremity DVT thrombus thickness compared with VKAs alone (P-value < 0.001). After adjustment by treatment, the thrombi found in dilated veins showed a significant decrease in the thickness of such thrombi compared with those found in small veins: 4 mm vs. 0 mm (Coef. = 3, 95% CI: 1.9, 4.1 and P-value < 0.001). Anechoic and hypoechoic thrombi showed a significant decrease in the thickness compared with hyperechoic thrombi: 5 mm vs. 0 mm (Coef. = 4, 95% CI: 3.25, 4.74 and P-value < 0.001) and 3 mm vs. 0 mm (Coef. = 2, 95% CI: 1.34, 42.66 and P-value < 0.001), respectively. Concentric thrombi showed a significant decrease in thickness compared with eccentric thrombi: 4 mm vs. 0 mm (Coef. = 2, 95% CI: 1.45, 2.55 and P-value < 0.001).

Conclusion

The anticoagulant treatment with LMWH followed by VKAs shows a significant decrease in lower extremity DVT thrombus thickness compared with VKAs alone. After adjustment by treatment, the morphologic finding of acute thrombi shows a significantly decreased thickness compared with the morphologic finding of chronic thrombi.

Non-invasive imaging techniques for the differentiation of acute and chronic thrombosis

Thrombosis is the localized clotting of blood that can occur in both the arterial and venous circulation. It is a key factor in the pathogenesis of acute coronary syndrome, myocardial infarction and stroke and the primary cause of deep vein thrombosis and pulmonary embolism. Rapid and accurate diagnosis of thrombotic episodes is crucial in reducing the morbidity and potential mortality associated with arterial and venous thrombotic disorders by allowing early targeted therapeutic interventions. From a clinical perspective the ability to accurately assess the age and composition of thrombus is highly desirable given that anticoagulation and, in particular, fibrinolytic therapies are more effective in treating acute rather than chronic thrombosis. While there are no imaging tests used in routine clinical practice that can reliably determine the age of thrombus and differentiate between acute and chronic thrombosis there are several emerging non-invasive techniques that can provide an indication of the age of a thrombus depending on its location in the body. Examples of techniques developed for venous thrombosis include Doppler imaging with venous duplex ultrasonography, ultrasound B-mode imaging integrated with IER (intrinsic mode functions-based echogenicity ratio), elastography, scintigraphy imaging with ^99mTc-recombinant tissue plasminogen activator (^99mTc-rt-PA), and magnetic resonance direct thrombus imaging (MDRTI). Magnetic resonance imaging (MRI) has been used to noninvasively detect and differentiate acute and chronic arterial and venous thrombosis. These methods have limitations that need further investigation to enable cost-effective and clinically relevant treatment practices to be established in the future. This review will discuss the difference between acute and chronic thrombosis and the role of non-invasive imaging techniques in discriminating between the two.