MRI scan visualization of a dissolving blood clot.

Unclogging the Mystery: Can Advanced Imaging Spot Blood Clots That Will Dissolve?

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Nico Varela in Health & Wellness June 2025 • 4 min read.

"A new MRI technique shows promise in predicting which deep vein thrombi will respond to clot-busting treatment, potentially saving patients from unnecessary risks."


Deep vein thrombosis (DVT), the formation of blood clots in the deep veins of the legs, is a serious condition. If left untreated, DVT can lead to pulmonary embolism (PE), a life-threatening blockage in the lungs. Current treatment strategies often involve catheter-directed thrombolysis (CDT), a procedure where clot-dissolving drugs are delivered directly to the thrombus.

However, CDT isn't always successful and carries significant risks, including bleeding complications. Determining which patients will benefit from CDT and who might be better served by alternative therapies remains a challenge. Thrombus age, often based on patient history, is an unreliable indicator, and a more precise way to assess clot composition is needed.

Now, a new study presented at the 19th Meeting of the European Venous Forum offers a promising solution. Researchers have successfully translated a non-contrast Magnetic Resonance Imaging (MRI) technique, previously tested in animal models, into a clinical setting to predict thrombus lysability – the likelihood of a clot to dissolve with treatment.

MSTI: A New Window into Thrombus Composition

MRI scan visualization of a dissolving blood clot.

The study, led by Justinas Silickas and colleagues from King's College London, explored the use of multi-sequence thrombus imaging (MSTI) in patients with acute iliofemoral DVT (clots in the iliac and femoral veins). MSTI involves a specialized MRI protocol that assesses various characteristics of the thrombus, including:

The MSTI technique, performed using a 3-Tesla MR scanner with a 32-channel cardiac coil, takes approximately 35 minutes. Patients underwent MSTI prior to thrombolysis, and the success of lysis was determined by contrast venography (assessing residual thrombus and the need for stenting).

  • T1 Mapping: Measures the relaxation times of water molecules within the thrombus, providing information about its age and composition.
  • Magnetization Transfer: Assesses the interaction between water and macromolecules in the thrombus, reflecting its structural integrity.
  • Diffusion-Weighted Imaging: Measures the movement of water molecules, indicating the density and organization of the thrombus.
The study involved 39 patients. The results showed significant differences in thrombus characteristics between clots that lysed successfully and those that did not. Specifically, non-lysed thrombi had higher T1 relaxation times and mean ADC values compared to lysed thrombi. Magnetization Transfer (MTR) values did not differ significantly between the groups.

Personalized DVT Treatment on the Horizon?

This study demonstrates the potential of MSTI to identify patients with iliofemoral DVTs who are most likely to respond to thrombolysis. By using cut-off values for T1 relaxation time, MTR, and ADC, the researchers achieved a sensitivity of 89% and specificity of 100% in distinguishing lysed and non-lysed thrombi. This suggests that MSTI could be used to stratify patients for CDT, avoiding unnecessary risks and costs in those unlikely to benefit. The researchers emphasize the need for further optimization of image analysis methods and validation of these findings in collaboration with other centers. However, this study represents a significant step towards personalized DVT treatment, potentially improving outcomes and reducing complications for patients with this common and potentially life-threatening condition.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

Everything You Need To Know

1

What is deep vein thrombosis (DVT), and why should I be concerned about it?

Deep vein thrombosis (DVT) is the formation of blood clots in the deep veins, typically in the legs. This is dangerous because if these clots break loose, they can travel to the lungs and cause a pulmonary embolism (PE), which is a life-threatening blockage. Therefore, early detection and appropriate treatment of DVT are crucial to prevent serious complications. The article discusses how a new MRI technique might help to improve DVT treatment.

2

What is multi-sequence thrombus imaging (MSTI), and what does it aim to achieve?

Multi-sequence thrombus imaging (MSTI) is a specialized MRI technique designed to assess the characteristics of blood clots, or thrombi. MSTI uses a combination of different MRI measurements like T1 Mapping, Magnetization Transfer, and Diffusion-Weighted Imaging to provide detailed information about the clot's age, composition, and structure. The goal of MSTI is to predict whether a clot will dissolve with clot-busting treatment.

3

What is T1 Mapping, and what does it tell us about blood clots?

T1 Mapping is a component of the MSTI technique that measures the relaxation times of water molecules within a thrombus. This measurement provides insights into the thrombus's age and composition, which are important factors in determining how likely the clot is to dissolve with treatment. Higher T1 relaxation times in non-lysed thrombi may indicate differences in clot structure or age that affect their response to thrombolysis.

4

What is Magnetization Transfer, and how does it contribute to understanding thrombus composition?

Magnetization Transfer is another component of the MSTI technique which assesses the interaction between water and macromolecules within a thrombus, reflecting its structural integrity. While the study did not find significant differences in Magnetization Transfer values between lysed and non-lysed thrombi, it remains a valuable parameter for understanding clot composition in conjunction with other MSTI measurements.

5

What is Diffusion-Weighted Imaging, and how does it help in assessing blood clots?

Diffusion-Weighted Imaging is an MRI technique used in MSTI to measure the movement of water molecules within a thrombus. It provides information about the density and organization of the thrombus. The study showed that non-lysed thrombi had higher mean ADC values compared to lysed thrombi, suggesting differences in water diffusion and clot structure that may affect their response to thrombolysis.

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