Black-blood thrombus imaging (BTI): a contrast-free cardiovascular magnetic resonance approach for the diagnosis of non-acute deep vein thrombosis

Abstract

BackgroundDeep vein thrombosis (DVT) is a common but elusive illness that can result in long-term disability or death. Accurate detection of thrombosis and assessment of its size and distribution are critical for treatment decision-making. In the present study, we sought to develop and evaluate a cardiovascular magnetic resonance (CMR) black-blood thrombus imaging (BTI) technique, based on delay alternating with nutation for tailored excitation black-blood preparation and variable flip angle turbo-spin-echo readout, for the diagnosis of non-acute DVT.MethodsThis prospective study was approved by institutional review board and informed consent obtained from all subjects. BTI was first conducted in 11 healthy subjects for parameter optimization and then conducted in 18 non-acute DVT patients to evaluate its diagnostic performance. Two clinically used CMR techniques, contrast-enhanced CMR venography (CE-MRV) and three dimensional magnetization prepared rapid acquisition gradient echo (MPRAGE), were also conducted in all patients for comparison. All images obtained from patients were analyzed on a per-segment basis. Using the consensus diagnosis of CE-MRV as the reference, the sensitivity (SE), specificity (SP), positive and negative predictive values (PPV and NPV), and accuracy (ACC) of BTI and MPRAGE as well as their diagnostic agreement with CE-MRV were calculated. Besides, diagnostic confidence and interreader diagnostic agreement were evaluated for all three techniques.ResultsBTI with optimized parameters effectively nulled the venous blood flow signal and allowed directly visualizing the thrombus within the black-blood lumen. Higher SE (90.4% vs 67.6%), SP (99.0% vs. 97.4%), PPV (95.4% vs. 85.6%), NPV (97.8% vs 92.9%) and ACC (97.4% vs. 91.8%) were obtained by BTI in comparison with MPRAGE. Good diagnostic confidence and excellent diagnostic and interreader agreements were achieved by BTI, which were superior to MPRAGE on detecting the chronic thrombus.ConclusionBTI allows direct visualization of non-acute DVT within the dark venous lumen and has the potential to be a reliable diagnostic tool without the use of contrast medium.

Comparison Between the Diagnostic Performance of 1.5 T and 3.0 T field Strengths for Detecting Deep Vein Thrombosis Using Magnetic Resonance Black-Blood Thrombus Imaging

“…The SNR and the contrast-to-noise ratio (CNR) of the 1.5 T and 3.0 T groups were calculated using SYNGO software (Siemens), respectively, for analyzing the statistical differences between the 2 groups of images. Using methods from previous studies, [9][10][11] the apparent SNR of the thrombus, muscle, and the dark venous lumen was calculated as the mean SI divided by the standard deviation (SD) of the background (ie, SI/SD); and in order to avoid the deviation caused by different sampling resolution, SNR is normalized and compared (SNR 3.0 T ¼ SI/ SD/[voxel 3.0 T/ voxel 1.5 T ]). The apparent CNR between the thrombus and the muscle ([SI thrombus À SI muscle ]/SD) and between the thrombus and the venous lumen ([SI thrombus À SI lumen ]/SD) was also calculated.…”

“…[5][6][7][8] Recent studies have described the value of magnetic resonance (MR) black-blood thrombus imaging (BTI) in the diagnosis of thrombus. [9][10][11][12][13] To diagnosis a thrombus, it is necessary to suppress the signal flowing through the blood and to capture the signal of the stationary tissue. Because the concentrations of methemoglobin (MET-Hb) rely on the phase of the DVT, the signal intensity (SI) of the thrombus on the T1-weighted image varies.…”

“…[13][14][15] The 3dimensional imaging of BTI can provide clinicians with multidirectional image information about whether there is vascular variation, which allows a more accurate diagnosis and description of the location and size of thrombus and can even indicate the age of thrombus, which has very important significance when choosing treatment. 10,[16][17][18] Anticoagulation and thrombolytic therapies are the mainstay of DVT treatment; however, they are the most effective in the acute phase and rapidly decrease in their effectiveness as thrombus composition evolves with age. [16][17][18] The 1.5 T and 3.0 T MR systems are commonly used in the clinic.…”

“…[16][17][18] The 1.5 T and 3.0 T MR systems are commonly used in the clinic. In previous studies, [9][10][11] BTI has been used at either 3.0 T or 1.5 T field strengths for the diagnosis of DVT, respectively. Research demonstrated that BTI is an accurate diagnostic technique for DVT but to date there has been no research comparing the diagnostic performance and consistency of this technique at different field strengths.…”

Diagnosis of Deep Venous Thrombosis and Pulmonary Embolism

“…22 MRI offers the opportunity to differentiate between old and new thrombi, 22 leveraging the ability of MRI to differentiate between age of thrombi. Modifications including “Black-Blood Thrombus Imaging (BTI)” 23,24 have shown promise in dating clot chronicity. Sonographic elasticity imaging (SEI) utilizes ultrasound based techniques to assess the stiffness of clot and thus distinguish fresh from subacute/chronic clot.…”