BackgroundD-dimer testing to rule out deep vein thrombosis is less useful in older patients because of a lower specificity. An age-adjusted D-dimer cut-off value increased the proportion of older patients (>50 years) in whom pulmonary embolism could be excluded. We retrospectively validated the efficacy of this cut-off combined with clinical probability for the exclusion of deep vein thrombosis. Design and MethodsFive management study cohorts of 2818 consecutive outpatients with suspected deep vein thrombosis were used. Patients with non-high or unlikely probability of deep vein thrombosis were included in the analysis; four different D-dimer tests were used. The proportion of patients with a normal D-dimer test and the failure rates were calculated using the conventional (500 mg/L) and the age-adjusted D-dimer cut-off (patient's age x 10 mg/L in patients >50 years). ResultsIn 1672 patients with non-high probability, deep vein thrombosis could be excluded in 850 (51%) patients with the age-adjusted cut-off value versus 707 (42%) patients with the conventional cut-off value. The failure rates were 7 (0.8; 95% confidence interval 0.3-1.7%) for the age-adjusted cut-off value and 5 (0.7%, 0.2-1.6%) for the conventional cut-off value. The absolute increase in patients in whom deep vein thrombosis could be ruled out using the ageadjusted cut-off value was largest in patients >70 years: 19% among patients with non-high probability. ConclusionsThe age-adjusted cut-off of the D-dimer combined with clinical probability greatly increases the proportion of older patients in whom deep vein thrombosis can be safely excluded.

Summary.  Background: Accurate diagnosis of acute recurrent deep vein thrombosis (DVT) is relevant to avoid improper diagnosis and unnecessary life‐long anticoagulant treatment. Compression ultrasound has high accuracy for a first episode of DVT, but is often unreliable in suspected recurrent disease. Magnetic resonance direct thrombus imaging (MR DTI) has been shown to accurately detect acute DVT. The purpose of this prospective study was to determine the MR signal change during 6 months follow‐up in patients with acute DVT. Patients/methods: This study was a prospective study of 43 consecutive patients with a first episode of acute DVT demonstrated by compression ultrasound. All patients underwent MR DTI. Follow‐up was performed with MR‐DTI and compression ultrasound at 3 and 6 months respectively. All data were coded, stored and assessed by two blinded observers. Results: MR direct thrombus imaging identified acute DVT in 41 of 43 patients (sensitivity 95%). There was no abnormal MR‐signal in controls, or in the contralateral extremity of patients with DVT (specificity 100%). In none of the 39 patients available at 6 months follow‐up was the abnormal MR‐signal at the initial acute DVT observed, whereas in 12 of these patients (30.8%) compression ultrasound was still abnormal. Conclusion: Magnetic resonance direct thrombus imaging normalizes over a period of 6 months in all patients with diagnosed DVT, while compression ultrasound remains abnormal in a third of these patients. MR‐DTI may potentially allow for accurate detection in patients with acute suspected recurrent DVT, and this should be studied prospectively.

Key Points• Diagnostic management of ipsilateral recurrent DVT of the leg is complicated because residual DVT is common and mimics acute DVT on CUS.• MRDTI is able to reproducibly distinguish acute ipsilateral recurrent DVT from 6-monthold chronic residual thrombi in the leg veins.Accurate diagnostic assessment of suspected ipsilateral recurrent deep vein thrombosis (DVT) is a major clinical challenge because differentiating between acute recurrent thrombosis and residual thrombosis is difficult with compression ultrasonography (CUS). We evaluated noninvasive magnetic resonance direct thrombus imaging (MRDTI) in a prospective study of 39 patients with symptomatic recurrent ipsilateral DVT (incompressibility of a different proximal venous segment than at the prior DVT) and 42 asymptomatic patients with at least 6-month-old chronic residual thrombi and normal D-dimer levels. All patients were subjected to MRDTI. MRDTI images were judged by 2 independent radiologists blinded for the presence of acute DVT and a third in case of disagreement. The sensitivity, specificity, and interobserver reliability of MRDTI were determined. MRDTI demonstrated acute recurrent ipsilateral DVT in 37 of 39 patients and was normal in all 42 patients without symptomatic recurrent disease for a sensitivity of 95% (95% CI, 83% to 99%) and a specificity of 100% (95% CI, 92% to 100%). Interobserver agreement was excellent (k 5 0.98). MRDTI images were adequate for interpretation in 95% of the cases. MRDTI is a sensitive and reproducible method for distinguishing acute ipsilateral recurrent DVT from 6-month-old chronic residual thrombi in the leg veins. (Blood. 2014;124(4):623-627)

Summary The potential role of the detection of residual thrombosis after deep vein thrombosis (DVT) in the differentiation of patients at risk for recurrent venous thromboembolism (VTE) has not yet been fully established and includes different definitions. We performed a systematic review in order to determine the role of residual thrombosis in predicting recurrent VTE after acute proximal DVT. Databases were searched until June 2010. Randomized, controlled trials or prospective cohort studies were eligible for inclusion if they included patients with objectively diagnosed proximal DVT, measured thrombus diameter after at least 3 months and reported recurrent VTE during follow‐up. Two authors independently reviewed articles and extracted data. Data from 11 studies were used for the current analysis; in total 3203 patients were included. Residual thrombosis was positively correlated with recurrent VTE. Large heterogeneity was present, due to differences in study population, timing and the differences in method of measuring residual thrombosis. The effect was more pronounced in patients with malignancy or was dependent on the criteria used. This systematic review shows a positive relationship between residual thrombosis and recurrent VTE during follow‐up. Assessing residual thrombosis could be useful in individual recurrence risk estimation.

SummaryDeep vein thrombosis (DVT) is a common disease that may lead to potentially fatal complications, such as pulmonary embolism. In the past decades several diagnostic tools and algorithms for DVT have been studied. Currently the combination of a clinical decision rule, D-dimer testing and compression ultrasonography has proved to be safe and effective for the diagnosis of DVT in the lower extremities. Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) can be useful as additional or secondary imaging modalities. This review will discuss the elements currently used in making the clinical diagnosis of DVT. These elements include clinical decision rules and D-dimer testing, different imaging investigations and the appropriate use of these within diagnostic algorithms in patients with clinically suspected DVT. Although current knowledge of the options available to diagnose DVT of the lower extremities is well established, there are still unresolved issues, including the optimal diagnosis of recurrent DVT and distal DVT. Furthermore, the diagnosis of DVT of the upper extremities will be discussed, including the different imaging modalities and the limitations of these techniques.