Miniaturized T2MR Magnetic Resonance System for Analysis of Hemostasis and Detection of Impaired and Prothrombotic Blood Disorders

Abstract 1118

There are no currently available tests to rapidly assess and reliably identify both impaired hemostasis and hypercoagulable states, in part because of difficulties in measuring integrated reactions in whole blood using a single sensitive and clinically useful platform. Methods like T2 magnetic resonance (T2MR) can provide rich information from complex samples, such as changes in the blood during hemostasis, by measuring signals emanating from the hydrogen nuclei within the sample, primarily in water. We used a 14”x6”x7” portable instrument to measure changes in T2MR that provide a continuous report on the dynamically changing microscopic environment of water during coagulation of whole blood (WB), platelet-poor or platelet-rich plasma (PRP).

In these initial foundational studies, we measured T2MR continuously over 20 mins using 34 μL blood samples from consented normal adult donors. We tested clotting of WB initiated by the addition of thrombin or kaolin + calcium. Platelet activation was achieved in WB by addition of ADP or arachidonic acid in the presence of reptilase and factor XIIIa with and without addition of the platelet inhibitors aspirin or 2-methylthioadenosine 5'-monophosphate (2-MeSAMP) and results were confirmed by standard platelet aggregometry. At normal platelet counts from 1.5–3×10⁵/μL and normal hematocrit (HCT) from 38%-48%, T2MR gave two curves corresponding to: (1) water trapped within a retracted clot and (2) water in the surrounding liquid, i.e. serum (Fig. 1a). Platelet counts <1×10⁵/μL or addition of aspirin or 2-MeSAMP eliminated the signal originating from clot retraction (Fig. 1b). High platelet counts (3–13×10⁵/μL) and high thrombin concentrations (10 u/mL) led to a third, even more highly ordered signal (Fig. 1c). The signal also revealed the influence of hematocrit on clot formation/retraction over a wide range of values (20%-73%). Platelet inhibition by aspirin or 2-MeSAMP decreased or eliminated the signal originating from clot retraction (Fig. 1d).

Our proof-of-principle studies show that T2MR technology can be applied to measurement of blood clotting across a range of hemostatic conditions. This single technology may be applicable to the study, diagnosis, and management of a spectrum of disorders that range from impaired hemostasis to hypercoagulable states. These T2MR studies represent the first application of this technology to hemostasis and thrombosis. Additional studies will be needed to develop a more complete understanding of the biochemical events measured by T2MR and to more fully explore its clinical utility.

Figure 1.

View largeDownload slide

Examples of T2MR 3D surfaces for 34 μL of citrated whole blood mixed activated by adding a dried formulation of CaCl₂ (11 mM) and kaolin (<0.25%) for (a) a normal platelet count (2.82×10⁵ platelets/μL); (b) thrombocytopenia (9.0×10⁴ platelets/μL); and (c) thrombocytosis (1.0×10⁶ platelets/μL). All samples were reconstituted blood in the same way. (d) Citrated whole blood activated by ADP in the presence of 2-MeSAMP.

Figure 1.

View largeDownload slide

Examples of T2MR 3D surfaces for 34 μL of citrated whole blood mixed activated by adding a dried formulation of CaCl₂ (11 mM) and kaolin (<0.25%) for (a) a normal platelet count (2.82×10⁵ platelets/μL); (b) thrombocytopenia (9.0×10⁴ platelets/μL); and (c) thrombocytosis (1.0×10⁶ platelets/μL). All samples were reconstituted blood in the same way. (d) Citrated whole blood activated by ADP in the presence of 2-MeSAMP.

Close modal