Diagnosis Of Acute Deep Vein Thrombosis Research Articles

Cardiovascular magnetic resonance black-blood thrombus imaging for the diagnosis of acute deep vein thrombosis at 1.5 Tesla

BackgroundThe aim was to investigate the feasibility of a cardiovascular magnetic resonance (CMR) black-blood thrombus imaging (BBTI) technique, based on delay alternating with nutation for tailored excitation black-blood preparation and a variable flip angle turbo-spin-echo readout, for the diagnosis of acute deep vein thrombosis (DVT) at 1.5 T.MethodsBBTI was conducted in 15 healthy subjects and 30 acute DVT patients. Contrast-enhanced CMR venography (CE-CMRV) was conducted for comparison and only performed in the patients. Apparent contrast-to-noise ratios between the thrombus and the muscle/lumen were calculated to determine whether BBTI could provide an adequate thrombus signal for diagnosis. Two blinded readers assessed the randomized BBTI images from all participants and made independent decisions on the presence or absence of thrombus at the segment level. Images obtained by CE-CMRV were also randomized and assessed by the two readers. Using the consensus CE-CMRV as a reference, the sensitivity, specificity, positive and negative predictive values, and accuracy of BBTI, as well as its diagnostic agreement with CE-CMRV, were calculated. Additionally, diagnostic confidence and interobserver diagnostic agreement were evaluated.ResultsThe thrombi in the acute phase exhibited iso- or hyperintense signals on the BBTI images. All the healthy subjects were correctly identified from the participants based on the segment level. The diagnostic confidence of BBTI was comparable to that of CE-CMRV (3.69 ± 0.52 vs. 3.70 ± 0.47). High overall sensitivity (95.2%), SP (98.6%), positive predictive value (96.0%), negative predictive value (98.3%), and accuracy (97.7%), as well as excellent diagnostic and interobserver agreements, were achieved using BBTI.ConclusionBBTI is a reliable, contrast-free technique for the diagnosis of acute DVT at 1.5 T.

Microparticle-associated tissue factor activity in patients with acute unprovoked deep vein thrombosis and during the course of one year

BackgroundTissue factor (TF) is the main in-vivo initiator of blood coagulation. Microparticles (MPs) are small procoagulant membrane vesicles. Elevated TF-bearing MPs have been found in different prothrombotic conditions and MP-associated TF activity may contribute to the pathogenesis of unprovoked deep vein thrombosis (DVT). ObjectiveTo determine MP-TF activity levels at diagnosis of DVT and at four additional time points during the course of one year in a well-defined group of patients with unprovoked DVT of the lower limb. Patients/MethodsIn this study, 41 patients with acute unilateral symptomatic and unprovoked DVT of the lower limb were included and followed for 1year. Venous blood samples for determination of MP-TF activity were drawn at diagnosis of acute DVT, and 1-, 3-, 6-, and 12months later. In addition, 10 young and healthy control subjects were included. ResultsThe median MP-TF activity was 0.06pg/mL (25th-75th percentile: 0.0-0.53) in patients with acute DVT and 0.18pg/mL (0.07-0.33) in healthy controls, and did not differ significantly (p=0.35). No significant changes in MP-TF activity were found in the follow-up measurements. MP-TF activity did also not differ significantly between patients with proximal- or distal DVT and between those with- or without residual DVT after 6months. ConclusionsMP-TF activity is low at the acute event in patients with unprovoked DVT of the lower limb and remains unchanged during the course of the disease. Our data do not support the hypothesis that TF-bearing MPs play a determining role in the pathogenesis of unprovoked DVT.

Evaluating the Role of Compression Stockings in Preventing Post thrombotic Syndrome: A Review of the Literature

Background. Postthrombotic syndrome (PTS) is a burdensome and costly complication of deep vein thrombosis (DVT). Up to 50% of patients with DVT will develop the disease within two years following the diagnosis of acute DVT. Various risk factors for developing PTS have been identified and different modalities have been used to prevent its development. Compression stockings have been studied for the prevention of PTS in patients diagnosed with proximal DVT. Methods. MEDLINE and EMBASE databases were searched to identify relevant original articles. Results. Several trials including two metaanalyses have examined the role of compression stockings for the prevention of PTS. Although most trials showed significant reduction in the development of PTS with the use of compression stockings, limitations in study design prevent the generalizability of the data. Two studies supported an individualized tailored duration especially in patients at low risk for developing the syndrome. A randomized double-blind placebo-controlled trial involving 800 patients is currently ongoing and may confirm the results of older studies. Conclusions. Clinical trials support the use of compression stockings in patients diagnosed with proximal DVT for the prevention of PTS.

Ultrasonography for DVT – how useful is single point augmentation?

Aims: It is unclear whether the absence of normal augmentation of spectral Doppler flow at a single point is an accurate predictor of lower limb acute deep vein thrombosis (DVT) or whether its presence reliably excludes DVT. Our main objective was to assess the role of single point augmentation of spectral Doppler flow in the diagnosis of acute DVT. Secondary objectives included identifying the augmentation response in non-DVT diagnoses. Methods: Patients attending the ultrasound department of two hospitals during an eight-month period for investigation of suspected acute DVT were eligible. Spectral Doppler assessment of the superficial femoral vein was recorded during valsalva manoeuvre and calf compression in the asymptomatic and symptomatic legs. The Doppler waveform was characterised as 'Normal' or 'Abnormal'. Standard compression ultrasonography of the symptomatic leg was then performed with the presence of DVT or an alternative diagnosis documented. Results: 167 patients underwent ultrasound examination using the study methodology. 9 patients were subsequently excluded due to bilateral DVT or inability to tolerate calf compression. The remaining 158 patients demonstrated a mean age of 65.4 years with 28 DVTs identified (17.7% of patients). Calf compression elicited a normal response in 118/130 non DVT examinations (specificity=90.8%) and was abnormal in 18/28 DVT examinations (sensitivity=64.3%). Diminished or absent augmentation was identified in alternative diagnoses that included haematoma and Baker's cyst. Conclusions: This study demonstrates that single point augmentation of venous flow has a high specificity and negative predictive value in the assessment of suspected acute DVT. However, the sensitivity is low with 35.4% of DVTs associated with normal Doppler spectra on calf compression (the majority of these missed DVTs are isolated to the calf veins). Conversely, an abnormal augmentation response may be seen in non DVT diagnoses.

Ultrasonography and diagnosis of venous thromboembolism.

Venous thromboembolism (VTE) consists of two related conditions: pulmonary embolism (PE) and deep vein thrombosis (DVT). Objective testing for VTE is crucial because the clinical diagnosis is nonspecific and insensitive, and the consequences of a missed diagnosis are serious. The purpose of this review is to discuss the utility of venous ultrasonography as the foundation for diagnosis of acute lower extremity DVT. The effectiveness and practicality of venous ultrasonography as a stand-alone examination versus theoretically attractive, but perhaps less practical, combined approaches of ultrasonography with clinical probability assessment and D-dimer testing in the diagnosis of acute DVT is also addressed. Finally, the role of venous ultrasonography in a diagnostic algorithm for suspected PE is discussed.

Screening for acute DVT: Optimal utilization of the vascular diagnostic laboratory

Since the introduction of venous duplex ultrasound scanning in the early 1980s, many articles have been published describing its use for the diagnosis of deep vein thrombosis (DVT) in symptomatic and asymptomatic high-risk patients. Although technological advances have improved B-mode imaging and Doppler signal processing in the last 2 decades, duplex ultrasonography still has limitations in the diagnosis of acute DVT. Besides those that are technological in nature, there also are limitations because of a lack of standards from one vascular laboratory to another. Studies vary according to the ultrasound techniques used, diagnostic criteria, number and types of patients studied, reimbursement guidelines, and compliance with established standards. Duplex examinations vary from unilateral to bilateral, limited to complete, proximal to distal, and imaging only to imaging combined with Doppler techniques. The sensitivity and specificity of duplex ultrasound for identifying symptomatic proximal DVT are in excess of 95%; however, these drop considerably for asymptomatic DVT in high-risk patients and in patients with isolated calf vein thrombosis. Nevertheless, the utilization of the vascular laboratory to screen for acute DVT in all patients, regardless of the limitations in specific populations, is increasing steadily, whereas reimbursement and the number of technologists available to perform these examinations is decreasing. To achieve optimal utilization of the vascular laboratory, national standards in the form of clinical pathways using evidence from the literature need to be developed and utilized. In addition, referring physicians need to be educated on the accuracy and limitations of duplex ultrasound scanning to avoid both overtreatment and undertreatment of acute DVT.