Current DVT imaging

Deep vein thrombosis in the thigh: MR imaging in two cases with atypical presentations

Deep vein thrombosis (DVT) is a common clinical problem affecting the lower extremities. Prompt imaging of suspected DVT is helpful for rapid diagnosis and proper treatment. However, patients without clear predisposing factors for DVT may be directed to alternative diagnoses of a musculoskeletal disorder. The few case reports and studies of magnetic resonance (MR) imaging of unsuspected DVT are limited to the calf and knee. Here, we report two cases with a rare presentation of thigh MR imaging of unsuspected DVT. Identifying branching, abnormal intraluminal signals on fluid-sensitive imaging, or rim-enhancing tubular structures within the edema of the thigh muscle is important for differentiating intramuscular DVT from other thigh pathologies.

Deep Vein Thrombosis in Intravenous Drug Users: An Invisible Global Health Burden

The prevalence of intravenous drug use has increased in the past decade and it represents an important risk factor for deep vein thrombosis. Intravenous drug use is a global problem, with the main culprit being heroin. Peer pressure and poverty in high-risk groups such as sex workers, females, and young adults raise the risk of intravenous drug use, which expresses itself in the form of venous thromboembolism eventually. Deep vein thrombosis typically manifests itself eight years after the initial intravenous drug administration, rendering it a silent killer. Aiming to review and summarize existing articles in this context, we performed an exhaustive literature search online on PubMed and Google Scholar indexes using the keywords "Deep Venous Thrombosis (DVT)" and "Intravenous Drug Users (IVDU)." English articles that addressed epidemiology, pathogenesis, clinical manifestations, diagnosis, differential diagnosis, management, and outcomes of DVT, including those in IVDU, were selected and analyzed. The pathogenesis of DVT development in IVDU is mainly attributed to the interplay of trauma to the vessel by repeated injection and the injected drug itself. The right-sided femoral vein is the most common vein affected. Prevalent clinical presentations include local pain, swelling, and redness with typical systemic symptoms including fever, cough, dyspnea, and chest pain on top of addiction features. There appeared to be a delay in reporting symptoms, which was most likely due to the social stigma attached to IVDU. There are over 50 conditions that present with swollen and painful limbs comparable to DVT in IVDU, making precise diagnosis critical for timely treatment. Venous ultrasound is the method of choice for diagnosing DVT. Extended anticoagulant therapy with low-molecular-weight heparin combined with warfarin is the recommended treatment. Intravenous drug abusers having DVT are affected by multiple complications and poorer outcomes such as slower recovery, recurrent venous thromboembolism (VTE), and a longer hospital stay, which put them at higher risk of morbidity, mortality, reduced productivity, and economic burden.

May-Thurner syndrome: History of understanding and need for defining population prevalence

Patients with May-Thurner syndrome (MTS) are at elevated risk of developing an extensive left iliofemoral deep vein thrombosis (DVT; localized blood clot) due to an anatomical variant where the right common iliac artery compresses the left common iliac vein against the lumbar spine. While MTS was initially presumed to be rare when it was first anatomically defined in 1957, case reports of this syndrome have recently become more frequent, perhaps due to improved imaging techniques allowing for enhanced visualization of the iliac veins. Still, the population burden of this condition is unknown, and there is speculation it may be higher than generally perceived. In the present review, we (a) review history of how MTS became recognized, (b) describe practical challenges of studying MTS in population-based settings due to the specialized imaging required for diagnosis, (c) discuss why the contribution of MTS to DVT may be underestimated, (d) describe uncertainty regarding the degree of venous compression which leads to DVT, and (e) outline future research needs. Our goal is to raise awareness of MTS and spark additional research into the epidemiology of this condition, which may be an underappreciated causative venous thromboembolism risk factor.

Venous Thromboembolism and Bleeding Adverse Events in Lower Leg, Ankle, and Foot Orthopaedic Surgery with and without Anticoagulants

BACKGROUND

Currently, there is insufficient knowledge about the benefits of anticoagulant use for primary prevention of venous thromboembolism (VTE) and its inherent risk of bleeding adverse events in patients undergoing surgery distal to the knee.

METHODS

The study included patients who had undergone an orthopaedic procedure distal to the tibial articular surface when they were 18 years of age or older. Using retrospective information from a tertiary care referral center, we compared patient demographics, clinical findings, diagnostic reports, procedures performed, and the rate of symptomatic VTE and bleeding adverse events between patients who had and those who had not received anticoagulant prophylaxis. Propensity score matching was used to minimize selection bias due to prophylactic treatment allocation.

RESULTS

A total of 5,286 patients who had received anticoagulant prophylaxis for below-the-knee surgery were successfully matched with 5,286 patients who had not received anticoagulant prophylaxis for such surgery. After propensity score matching, the standardized difference between the groups was <0.1 for all baseline characteristics, indicating a negligible difference between the groups. Patients who received anticoagulant prophylaxis had a significantly lower risk of developing a VTE compared with patients who did not (39 patients [0.7%] versus 99 patients [1.9%]), with an odds ratio (OR) of 0.38 (95% confidence interval [CI], 0.25 to 0.56; p < 0.001). In contradistinction, patients who received anticoagulant prophylaxis had a significantly higher risk of developing a bleeding adverse event than those who did not (115 [2.2%] versus 55 [1.0%]; OR, 2.18 [95% CI, 1.55 to 3.09]; p < 0.001).

CONCLUSIONS

Anticoagulant prophylaxis reduced the risk of VTE after surgery distal to the tibial articular surface by 3-fold but resulted in a concomitant 2-fold increase in the risk of a bleeding adverse event. Large-scale, prospective studies are necessary to better understand the true incidence of such events, associated patient-specific risk factors, efficacy of various thromboprophylactic regimens, and patient-reported implications of such events.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Ultrasonography in Emergency Department; a Diagnostic Tool for Better Examination and Decision-Making

Context:

The aim of this study is to evaluate the applications of ultrasonography (US) as a diagnostic tool in emergency settings.

Evidence acquisition:

In the present review article, search engines and scientific databases of Google Scholar, Science Direct, PubMed, Medline, Scopus, and Cochrane were searched for the applications of US in emergencies. Finally, related articles which were published between 2000 and 2017, were selected and by reviewing them an attempt was made to evaluate various applications of US for examining and facilitating decision-making in emergency department (ED).

Results:

As a diagnostic tool, US can be of diagnostic help in emergency settings for the specialists and the treatment team regarding trauma, measuring intracranial pressure (ICP), hemothorax pneumothorax, abscess and its drainage, deep vein thrombosis (DVT), dyspnea, acute abdomen, appendicitis and biliary problems, renal colic and renal stones, shock, foreign object, bone fracture, peripheral nerve block, establishing central and peripheral venous access, lumbar puncture (LP), and confirmation of nasogastric tube (NGT) and endotracheal tube (ETT) placement.

Conclusion:

The results of this review study showed that US can be of help to EMPs as a diagnostic tool in a wide range of diseases and clinical conditions, which in turn can result in a decrease in the time needed for diagnosis and treatment, and therefore improve both the quality and quantity of the service provided in ED.

Lower extremity venous reflux

Venous incompetence in the lower extremity is a common clinical problem. Basic understanding of venous anatomy, pathophysiologic mechanisms of venous reflux is essential for choosing the appropriate treatment strategy. The complex interplay of venous pressure, abdominal pressure, venous valvular function and gravitational force determine the venous incompetence. This review is intended to provide a succinct review of the pathophysiology of venous incompetence and the current role of imaging in its management.

Thrombus-mimicking artifacts in two-point Dixon MRI: Prevalence, appearance, and severity

PURPOSE

To evaluate the incidence and severity of potentially thrombus mimicking, flow-induced misallocation artifacts in a clinical setting. Two-point "Dixon" fat-water separation methods, with bipolar readout gradients, may suffer from flow-induced fat-water misallocation artifacts. If these artifacts occur within blood vessels, they may mimic thrombus.

MATERIALS AND METHODS

Two-point Dixon coronal and axial images acquired in 102 consecutive patients were retrospectively evaluated for the presence of flow-induced artifacts in arteries and veins. Artifacts were graded on a 3-point scale (none, mild, severe) by two independent readers. Interreader agreement was evaluated with kappa statistics.

RESULTS

Reader 1 reported 63 artifacts in 46 (45%) of the cases (severe in 19 cases, 18.6%). Reader 2 reported 51 artifacts in 43 (42.2%) of the cases (severe in 18 cases, 17.6%). Misallocation of fat and water was apparent in all datasets with severe artifacts, whereas variable signal intensity changes in water and fat images were observed in mild artifacts. Interreader agreement was good for artifacts appearing in coronal images (κ = 0.7) and fair for artifact appearance in axial images (κ = 0.24).

CONCLUSION

Our study shows a high incidence of flow-induced mild and severe artifacts in a two-point Dixon method with bipolar readout gradients. This artifact should not be misinterpreted as intravascular thrombus.

LEVEL OF EVIDENCE

3 J. Magn. Reson. Imaging 2017;45:229-236.

Thrombus age is ideally measured by history or MRV prior to thrombus removal

Many factors are known to be important in order to achieve optimal results after thrombus removal for iliofemoral DVT. Not much is published in the literature about timing the treatment, though many guidelines recommend treatment within 14 days. This time span lies within the phrase of acute DVT according to the definition given in many reporting standards. This article will highlight the value of information acquired from patients directly regarding onset of symptoms versus information acquired from imaging with the purpose of a more precise selection of patients for catheter-directed thrombolysis for iliofemoral DVT. What is the value of clinical information acquired from patients and does the information from imaging have additional value?

An unusual presentation of May-Thurner syndrome in a pediatric patient with a pelvic kidney

We report a case of an adolescent who presented with a deep vein thrombosis (DVT) and clinical findings consistent with May-Thurner Syndrome. Specific imaging demonstrated direct compression of the left common iliac vein by an overlying pelvic kidney. The patient's history and clinical presentation is detailed. The discussion focuses on the potential implications for care and management of a patient with an ectopic left pelvic kidney.

A Novel Scoring System for Lower-extremity Venous Pathology Analysed Using Magnetic Resonance Venography and Duplex Ultrasound

Objectives:

To present a novel scoring system for lower-extremity venous pathology (the LOVE score) and our experiences using it in our clinical practice to identify venous pathology with duplex ultrasound (DUS) and magnetic resonance venography (MRV).

Method:

A total of 40 patients, 30 suspected of chronic venous disease and 10 with acute deep vein thrombosis (DVT) were examined from the inferior vena cava (IVC) to the popliteal vein using DUS and MRV. The image findings were reported using the LOVE score.

Results

The majority of deep veins (368 out of 378 segments) were completely visualized by both our imaging techniques and could be analysed using the LOVE score. Both imaging techniques reported comparable findings with regard to the visualization of thrombus, obstruction, collaterals, trabeculations, anatomic variations and central venous compression (e.g. May–Thurner).

Conclusions:

The LOVE score can be used to expand and standardize the documentation of imaging the deep venous system beyond thrombosis, to help identify (optimal) treatment options in patients with venous disease, in both the clinical and research setting. This first assessment shows that both DUS and MRV are capable of systematically identifying a multitude of changes in the venous system.

Multimodality imaging of the peripheral venous system

The purpose of this article is to review the spectrum of image-based diagnostic tools used in the investigation of suspected deep vein thrombosis (DVT). Summary of the experience gained by the author as well as relevant publications, regarding vein imaging modalities taken from a computerized database, was reviewed. The imaging modalities reviewed include phlebography, color Doppler duplex ultrasonography (CDDUS), computerized tomography angiography (CTA) and venography (CTV), magnetic resonance venography (MRV), and radionuclide venography (RNV). CDDUS is recommended as the modality of choice for the diagnosis of DVT. A strategy combining clinical score and D-dimer test refines the selection of patients. Phlebography is reserved for discrepant noninvasive studies.

[Importance of D-dimer testing in ambulatory detection of atypical and "silent" phlebothrombosis]

BACKGROUND/AIM

Deep venous thrombosis (DVT) is a life-threatening condition, which could be manifested with discrete symptoms (silent DVT). High mortality and disability of patients with DVT indicate the importance of early diagnosis, especially of "silent" DVT. The aim of this paper was to evaluate of reliability of early detection model for diagnosing DVT in ambulatory patients by using clinical probability of DVT presence, D-dimmer test (DD) and ultrasound evaluation (US).

METHODS

Ambulatory patients with suspected DVT were classified as "unlikely" and "likely" DVT by the Wells clinical model. The patients were randomly divided into the control and DD group. In the control group (629 patients) only US examination of lower limbs deep vein was done. All patients in the DD group (643 patients), with "unlikely" TDV, had DD, and in the positive patients US examination was done. In the "likely" patients US examination was done and negative US finding indicated DD test. Positive DD test was an indication for US examination after 7 days. The patients with initially excluded DVT were evaluated during 3 months.

RESULTS

A total number of 1 272 patients were examined; 117 (9.19%) patients were with DVT--62 (9.640%) in the DD and 55 (8.74%) in the control group. During the follow-up periods in the DD group (with 582 initially excluded DVT) we registered DVT in only one patient (0.17%). It was significantly lower (p < 0.05) compared to the control group where we registered 7 (1.10%) DVT (a group with 581 initially excluded DVT). The applied DD diagnostic strategy for 70.7% (p < 0.001) reduced the need for US examination.

CONCLUSION

The applied DD strategy in the diagnostic of DVT reduces the need for US examinations and reduces frequency of false negative results, with direct impact on cost and efficacy of procedures. DD diagnostic model should replace serial US examination in patients with suspect DVT.

Upper extremity deep vein thrombosis

Upper extremity deep vein thrombosis (UEDVT) is associated with significant morbidity and mortality. The susceptible populations and risk factors for UEDVT are well-known. The presenting symptoms can be subtle, and therefore objective testing is necessary for diagnosis. The optimal diagnostic strategy has not been determined, and more than one test may be required to exclude the diagnosis. Proper treatment reduces the occurrence of complications, and treatment should include long-term anticoagulation if the patient has no contraindications. This article discusses the risk factors, pathogenesis, diagnosis, complications, and management of UEDVT.

Endovascular Intervention for Central Venous Cannulation in Patients with Vascular Occlusion after Previous Catheterization

Objectives

This study was designed to assess endovascular intervention for central venous cannulation in patients with vascular occlusion after previous catheterization.

Methods

Patients referred for endovascular management of central venous occlusion during a 42-month period were identified from a regional endovascular database, providing prospective information on techniques and clinical outcome. Corresponding patient records, angiograms, and radiographic reports were analyzed retrospectively.

Results

Sixteen patients aged 48 years (range 0.5–76), including 11 females, were included. All patients but 1 had had multiple central venous catheters with a median total indwelling time of 37 months. Eleven patients cannulated for hemodialysis had had significantly fewer individual catheters inserted compared with 5 patients cannulated for nutritional support (mean 3.6 vs. 10.2, p<0.001) before endovascular intervention. Preoperative imaging by magnetic resonance tomography (MRT) in 8 patients, computed tomography (CT) venography in 3, conventional angiography in 6, and/or ultrasonography in 8, verified 15 brachiocephalic, 13 internal jugular, 3 superior caval, and/or 3 subclavian venous occlusions. Patients were subjected to recanalization (n=2), recanalization and percutaneous transluminal angioplasty (n=5), or stenting for vena cava superior syndrome (n=1) prior to catheter insertion. The remaining 8 patients were cannulated by avoiding the occluded route.

Conclusions

Central venous occlusion occurs particularly in patients under hemodialysis and with a history of multiple central venous catheterizations with large-diameter catheters and/or long total indwelling time periods. Patients with central venous occlusion verified by CT or MRT venography and need for central venous access should be referred for endovascular intervention.

Utility of balanced steady-state free precession MR venography in the diagnosis of lower extremity deep venous thrombosis

OBJECTIVE

The purpose of this study was to determine the sensitivity and specificity of balanced steady-state free precession MR venography in the diagnosis of lower extremity deep venous thrombosis.

SUBJECTS AND METHODS

After undergoing lower extremity ultrasound because of suspicion of deep venous thrombosis, 64 patients were prospectively recruited to undergo balanced steady-state free precession MR venography with ultrasound as the reference standard. Ultrasound images were independently interpreted by two blinded ultrasound radiologists, and MR venograms were independently interpreted by two blinded MRI radiologists. The sensitivity, specificity, positive predictive value, and negative predictive value of MR venography were calculated for the diagnoses of all deep venous thrombosis, acute thrombi, and thrombosis of the popliteal, femoral, and common femoral veins individually. Proximal extent, thrombus age, ancillary findings, and interobserver agreement calculated with the Cohen kappa test were evaluated for ultrasound and MRI. The McNemar test was used to evaluate for statistical differences in diagnostic accuracy.

RESULTS

MR venography had a sensitivity of 94.7%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 97.7% for the diagnosis of all thrombi. For acute thrombi, the MR venography and ultrasound results were completely concordant. MR venography depicted greater proximal extent in five of 18 cases in which thrombosis was found. The MR venographic findings agreed completely with the ultrasound findings in determination of thrombus age. For both ultrasound and MR venography, interobserver agreement was 100% on a per-patient basis. No statistical difference was identified in the diagnostic performance of the two techniques.

CONCLUSION

Balanced steady-state free precession MR venography is highly accurate in the diagnosis of lower extremity deep venous thrombosis.

Computer-assisted venous thrombosis volume quantification

Venous thrombosis (VT) volume assessment, by verifying its risk of progression when anticoagulant or thrombolytic therapies are prescribed, is often necessary to screen life-threatening complications. Commonly, VT volume estimation is done by manual delineation of few contours in the ultrasound (US) image sequence, assuming that the VT has a regular shape and constant radius, thus producing significant errors. This paper presents and evaluates a comprehensive functional approach based on the combination of robust anisotropic diffusion and deformable contours to calculate VT volume in a more accurate manner when applied to freehand 2-D US image sequences. Robust anisotropic filtering reduces image speckle noise without generating incoherent edge discontinuities. Prior knowledge of the VT shape allows initializing the deformable contour, which is then guided by the noise-filtering outcome. Segmented contours are subsequently used to calculate VT volume. The proposed approach is integrated into a system prototype compatible with existing clinical US machines that additionally tracks the acquired images 3-D position and provides a dense Delaunay triangulation required for volume calculation. A predefined robust anisotropic diffusion and deformable contour parameter set enhances the system usability. Experimental results pertinence is assessed by comparison with manual and tetrahedron-based volume computations, using images acquired by two medical experts of eight plastic phantoms and eight in vitro VTs, whose independently measured volume is the reference ground truth. Results show a mean difference between 16 and 35 mm(3) for volumes that vary from 655 to 2826 mm(3). Two in vivo VT volumes are also calculated to illustrate how this approach could be applied in clinical conditions when the real value is unknown. Comparative results for the two experts differ from 1.2% to 10.08% of the smallest estimated value when the image acquisition cadences are similar.

Central venous thrombosis in patients receiving long-term parenteral nutrition

Long-term parenteral nutrition (PN) is administered to patients who are unable to use their gastrointestinal tract to absorb sufficient nutrients and water to maintain their nutritional status. Patients receiving long-term parenteral nutrition are at risk of numerous complications including thrombosis of the central venous catheter used to provide nutrition. Central venous access is essential to the successful delivery of long-term PN. One of the strategies to lessen the frequency of this complication is anticoagulation therapy with warfarin. The effect of warfarin in preventing this complication may be modified by vitamin K intake. Individuals with gastrointestinal failure may receive vitamin K from a variety of sources. This review summarizes the role of warfarin in preventing central venous access thrombosis. It also summarizes potential sources of vitamin K intake in home parenteral nutrition patients, examines the evidence for recommendations regarding vitamin K intake, and considers the potential impact of increased vitamin K intake on home PN patients, particularly on the prevention of central venous thrombosis.

Prevalence of upper extremity deep venous thrombosis diagnosed by color Doppler duplex sonography in cancer patients with central venous catheters

OBJECTIVE

The purpose of this study was to review the literature concerning upper extremity deep venous thrombosis (UEDVT) diagnosed by color Doppler duplex sonography (CDDS) in cancer patients with indwelling central venous catheters (CVCs).

METHODS

From computerized databases (MEDLINE and Ovid), relevant publications regarding CDDS of the upper limb veins in cancer patients with CVCs were reviewed.

RESULTS

Patients with malignancy have a higher rate of thrombosis, which is increased by the presence of CVCs. Screening CDDS in asymptomatic patients showed CVC-related UEDVT in 11.7% to 44% of patients. In symptomatic cancer patients, the range was similar to the asymptomatic ones, 6.7% to 48%. The presence of a CVC almost doubled the incidence of UEDVT in symptomatic patients. Color Doppler duplex sonography is an accurate examination for the diagnosis of UEDVT, with sensitivity ranging from 78% to 100% and specificity ranging from 82% to 100%. The main obstacle for the diagnosis of UEDVT is the presence of overlying bones, making it difficult to visualize and impossible to directly assess by compression techniques. Color and spectral Doppler sonography and the use of small transducers aid in the diagnosis. When several parameters are evaluated in combination, CDDS is a reliable method for diagnosing CVC-related thrombosis.

CONCLUSIONS

Great variability in the prevalence of catheter-related thrombosis in cancer patients has been reported, although it is uniformly higher compared with patients without cancer. Color Doppler duplex sonography is the modality of choice for the diagnosis of CVC-related UEDVT in symptomatic cancer patients and for screening for asymptomatic thrombosis in this specific population.

(99m)Tc-NC100668, a new tracer for imaging venous thromboemboli: pre-clinical biodistribution and incorporation into plasma clots in vivo and in vitro

PURPOSE

(99m)Tc-NC100668 is a new radiotracer being developed to aid the diagnosis of thromboembolism. The structure of NC100668 is similar to a region of human alpha(2)-antiplasmin, which is a substrate for factor XIIIa (FXIIIa). The purpose of this study was to confirm the uptake of (99m)Tc-NC100668 into forming plasma clot and to establish the biodistribution of (99m)Tc-NC100668 in Wistar rats.

METHODS

The in vitro plasma clot uptake of (99m)Tc-NC100668 and other compounds with known affinities to FXIIIa was measured using a plasma clot assay. The biodistribution and blood clot uptake of radioactivity of (99m)Tc-NC100668 in normal Wistar rats and those bearing experimentally induced deep vein thrombi were investigated.

RESULTS

The in vitro uptake of (99m)Tc-NC100668 was greater than that for [(14)C]dansyl cadaverine, a known substrate of FXIIIa in the plasma clot assay. The biodistribution of (99m)Tc-NC100668 in male and female Wistar rats up to 24 h p.i. showed that radioactivity was rapidly excreted, predominantly into the urine, with very little background tissue retention. In vivo the uptake and retention of (99m)Tc-NC100668 into the blood clot was greater than could be accounted for by non-specific accumulation of the radiotracer within the blood clot.

CONCLUSION

(99m)Tc-NC100668 was retained by plasma clots in vitro and blood clots in vivo. No significant tissue retention which could interfere with the ability to image thrombi in vivo was observed. This evidence suggests that (99m)Tc-NC100668 might be useful in the detection of thromboembolism.