Evaluating Lower-Extremity Deep Vein Thrombosis using 3-Dimensional MR Black-Blood Thrombus Imaging: A Comparative Pilot Study

Objectives: This study aimed to evaluate the diagnostic performance of non-contrast magnetic resonance black-blood thrombus imaging (MRBTI) in detecting lower-extremity deep vein thrombosis (DVT) in comparison with computed tomography venography (CTV) and ultrasound (US). Methods: A total of 76 patients with consecutive lower-extremity DVT from March 2023 to February 2024 were included in this prospective study. All patients underwent MRBTI, CTV, and US. The image quality score and diagnostic confidence for MRBTI were determined by 2 readers independently using a 4-point scale. The sensitivity (SE), specificity (SP), accuracy (ACC), and positive and negative predictive values (PPV and NPV, respectively) of MRBTI and CTV were calculated, using the values for US as the standard of reference. The thrombus signal intensity, signal intensity ratio (SIR), and clot burden were obtained in each thrombus segment, and interobserver agreement was calculated using the interclass correlation coefficient (ICC) and Cohen kappa coefficients (κ). Results: The interobserver agreement was excellent for readers 1 and 2 in grading the quality score and diagnostic confidence level of the images (3.78 ± 0.48 vs 3.77 ± 0.49, κ = 0.821, p < 0.001; 3.94 ± 0.25 vs 3.93 ± 0.28, κ = 0.872, p < 0.001, respectively). Using the values for US as the standard, the SE, SP, PPV, NPV, and ACC of MRBTI were 90.08%, 98.54%, 94.78%, 97.12%, and 96.62% for reader 1 and 90.67%, 98.11%, 93.39%, 97.27%, and 96.42% for reader 2. Both readers strongly agreed on SIR measurements（ICC: 0.974, 95% CI: 0.968-0.979, p < 0.001）and had good agreement on clot burden （k = 0.866, p < 0.001）. Conclusions: Noncontrast-enhanced MRBTI accurately detected lower-extremity DVT and robustly quantified the entire lower-extremity thrombus signal, enabling pretreatment evaluation of deep veins in patients with DVT. Registry: Chinese Clinical Trial Registry Trial registration number: ChiCTR2500099260 (retrospectively registered) Registration Date: 2025-03-20 (retrospectively registered)