A robust multi-scale approach to quantitative susceptibility mapping.

Quantitative Susceptibility Mapping (QSM), best known as a surrogate for tissue iron content, is becoming a highly relevant MRI contrast for monitoring cellular and vascular status in aging, addiction, traumatic brain injury and, in general, a wide range of neurological disorders. In this study we present a new Bayesian QSM algorithm, named Multi-Scale Dipole Inversion (MSDI), which builds on the nonlinear Morphology-Enabled Dipole Inversion (nMEDI) framework, incorporating three additional features: (i) improved implementation of Laplace's equation to reduce the influence of background fields through variable harmonic filtering and subsequent deconvolution, (ii) improved error control through dynamic phase-reliability compensation across spatial scales, and (iii) scalewise use of the morphological prior. More generally, this new pre-conditioned QSM formalism aims to reduce the impact of dipole-incompatible fields and measurement errors such as flow effects, poor signal-to-noise ratio or other data inconsistencies that can lead to streaking and shadowing artefacts. In terms of performance, MSDI is the first algorithm to rank in the top-10 for all metrics evaluated in the 2016 QSM Reconstruction Challenge. It also demonstrated lower variance than nMEDI and more stable behaviour in scan-rescan reproducibility experiments for different MRI acquisitions at 3 and 7 Tesla. In the present work, we also explored new forms of susceptibility MRI contrast making explicit use of the differential information across spatial scales. Specifically, we show MSDI-derived examples of: (i) enhanced anatomical detail with susceptibility inversions from short-range dipole fields (hereby referred to as High-Pass Susceptibility Mapping or HPSM), (ii) high specificity to venous-blood susceptibilities for highly regularised HPSM (making a case for MSDI-based Venography or VenoMSDI), (iii) improved tissue specificity (and possibly statistical conditioning) for Macroscopic-Vessel Suppressed Susceptibility Mapping (MVSSM), and (iv) high spatial specificity and definition for HPSM-based Susceptibility-Weighted Imaging (HPSM-SWI) and related intensity projections.

Cerebral venous sinus thrombosis after vestibular schwannoma surgery: a call for evidence-based management guidelines.

OBJECTIVE Postoperative cerebral venous sinus thrombosis (CVST) is an uncommon complication of posterior fossa surgery. The true incidence of and optimal management strategy for this entity are largely unknown. Herein, the authors report their institutional incidence and management experience of postoperative CVST after vestibular schwannoma surgery. METHODS The authors undertook a retrospective review of all vestibular schwannoma cases that had been treated with microsurgical resection at a single institution from December 2011 to September 2017. Patient and tumor characteristics, risk factors, length of stay, surgical approaches, sinus characteristics, CVST management, complications, and follow-up were analyzed. RESULTS A total of 116 patients underwent resection of vestibular schwannoma. The incidence of postoperative CVST was 6.0% (7 patients). All 7 patients developed lateral CVST ipsilateral to the lesion. Four cases occurred after translabyrinthine approaches, 3 occurred after retrosigmoid approaches, and none occurred following middle cranial fossa approaches. Patients were managed with anticoagulation or antiplatelet therapy. Although patients were generally asymptomatic, one patient experienced intraparenchymal hemorrhage, epidural hemorrhage, and obstructive hydrocephalus, likely as a result of the anticoagulation therapy. However, all 7 patients had a modified Rankin scale score of 1 at the last follow-up. CONCLUSIONS Postoperative CVST is an infrequent complication, with an incidence of 6.0% among 116 patients who had undergone vestibular schwannoma surgery at one institution. Moreover, the management of postoperative CVST with anticoagulation therapy poses a serious dilemma to neurosurgeons. Given the paucity of reports in the literature and the low incidence of CVST, additional studies are needed to better understand the cause of thrombus formation and help to establish evidence-based guidelines for CVST management and prevention.

Computed tomography (CT) colonography with CT arteriography and venography for the workup of intestinal transplant candidates.

Prior to intestinal transplantation, prospective candidates must undergo a series of radiologic examinations to address a variety of clinical issues. To date, little literature exists to guide physicians in this preoperative assessment. Multiple imaging studies can provide overlapping information. We have developed a simple two- or three-test protocol to streamline the workup. Sixteen adult patients presented as potential intestinal transplant candidates to Georgetown University Hospital. All but two patients underwent the full protocol of a biphasic IV contrast-enhanced computed tomography (CT) scan of the chest, abdomen, and pelvis with rectal carbon dioxide, an upper gastrointestinal study with small bowel follow through, and fistulogram when appropriate. Three-dimensional (3-D) reconstructions of the vascular anatomy as well as the colon were also generated. A telephone survey to other transplant centers was additionally conducted to compare radiographic evaluations. Overall, 15 of the 16 scans were diagnostic. One patient required a barium enema. Mean examinations per patient was 2.4. Only one of seven other centers was performing CT colonography in prospective intestinal transplant candidates. Our protocol provided all the necessary anatomic information needed to evaluate prospective transplant candidates. CT colonography with angiography is a suitable alternative to more time-consuming radiological studies.

The role of colour Doppler sonography in the diagnosis of lower limb Klippel-Trénaunay syndrome.

AIM: To investigate the accuracy of colour Doppler sonography as compared to phlebography in patients with Klippel-Trénaunay syndrome (KTS). MATERIALS AND METHODS: From September 2004 to May 2012, 59 consecutive patients seen in Shandong medical imaging research institute with a clinical suggestion of KTS were included. Thirty-four were female and 25 were male, with a mean age of 28.4 years. Colour Doppler sonography was used to assess the lower limb veins. The main sonographic criteria for a positive diagnosis were visualization of the lateral vein or sciatic vein, capillary haemangioma, and abnormality of the deep veins. These data were compared with phlebography findings. The κ statistic was used to determine the level of agreement. The sensitivity, specificity, positive and negative predictive values, and accuracy of colour Doppler sonography as a diagnostic test were assessed. RESULTS: Colour Doppler sonography findings were positive in 21 of 59 patients with a clinical suggestion of KTS. The diagnosis was confirmed using phlebography in 22 patients. There were two false-positive results and one false-negative result by colour Doppler sonography. The κ-value was 0.892. Sensitivity, specificity, positive and negative predictive values, and accuracy for colour Doppler sonography were 95.4, 94.6, 91.3, 97.2, and 94.9%, respectively. CONCLUSION: Colour Doppler sonography is an accurate, reliable, and non-invasive investigation in the assessment of patients with suspected KTS.

Catheter venography for the assessment of internal jugular veins and azygous vein: position statement by expert panel of the International Society for Neurovascular Disease.

This document by an expert panel of the International Society for Neurovascular Disease is aimed at presenting current technique and interpretation of catheter venography of the internal jugular veins, azygous vein and other veins draining the central nervous system. Although interventionalists agree on general rules, significant differences exist in terms of details of venographic technique and interpretations of angiographic pictures. It is also suggested that debatable findings should be investigated using multimodal diagnostics. Finally, the authors recommend that any publication on chronic cerebrospinal venous insufficiency should include detailed description of venographic technique used, to facilitate a comparison of published results in this area.

Sensitivity and specificity for screening of chronic cerebrospinal venous insufficiency using a multimodal non-invasive imaging approach in patients with multiple sclerosis.

The aim of this study was to investigate whether a combination of Doppler sonography (DS) and magnetic resonance venography (MRV) on 3T MRI increases specificity for detection of chronic cerebrospinal venous insufficiency (CCSVI) in 171 (113 relapsing-remitting, 47 secondary-progressive, 11 primary progressive) patients with multiple sclerosis (MS) and 79 age- and sex matched healthy controls (HCs). One hundred ten (64.3%) MS patients and 30 (38%) HCs presented ≥2 venous hemodynamic CCSVI criteria (p<.0001). Both DS and MRV showed relatively high specificity but lower sensitivity for determining a CCSVI diagnosis in patients with MS vs HCs and between MS subgroups. In MS patients this diagnostic specificity increased to over 90% by combining internal jugular vein and vertebral vein abnormal DS and MRV findings, reflux in deep cerebral veins and MRV findings of >1 collateral veins. This study suggests that a multimodal non-invasive approach (DS and MRV) increases the specificity for a diagnosis of CCSVI in patients with MS.

ESPR uroradiology task force and ESUR paediatric working group: imaging and procedural recommendations in paediatric uroradiology, part III. Minutes of the ESPR uroradiology task force minisymposium on intravenous urography, uro-CT and MR-urography in childhood.

The ESPR working groups have addressed intravenous urography (IVU), uro-CT and MR-urography (MRU) in childhood as the last in the series of recommendations for paediatric uroradiology. The aim of this process was again to standardise paediatric uroradiologic imaging and to reduce invasiveness and radiation dose. As for the existing recommendations, the new proposals are consensus-based because evidence is lacking, use and indications have changed, or approaches on how to perform the examination in children differ in the literature (MRU). As in the previous recommendations, a thorough review of the literature and existing guidelines and recommendations has been performed. The proposals were discussed within the group and with non-member experts and colleagues from other partner disciplines. These recommendations aim to serve as a quality measure in order to standardise the procedures and thus grant comparable good quality results throughout different institutions.

[Pre-test and post-test probabilities. Who cares?]. / Vortest-Wahrscheinlichkeit - Bildgebung - Nachtest-Wahrscheinlichkeit: Wen kümmert das?

The accuracy of a diagnostic test, i.e. abdomen ultrasound in patients with suspected acute appendicitis, is described in the terms of sensitivity and specificity. According to eminent textbooks physicians should use the values of the sensitivity and specificity of a test in their diagnostic reasoning. Physician's estimate, after taking the history, the pretest-probability of the suspected illness, order one or more tests and then calculate the respective posttest-probability. In practice physicians almost never follow this line of thinking. The main reasons are; to estimate concrete illness probabilities is difficult, the values for the sensitivity and specificity of a test are most often not known by physicians and calculations during daily practice are intricate. Helpful for busy physicians are trustworthy expert recommendations which test to apply in which clinical situation.

Assessment of deep venous thrombosis in the lower extremity in Behçet's syndrome: MR venography versus Doppler ultrasonography.

Lower extremity venous thrombosis (DVT) is the most common vascular manifestation of Behçet's syndrome (BS). Currently, Doppler ultrasonography (USG) is the most commonly preferred imaging modality in the diagnosis and follow-up of patients with acute and chronic DVT. Magnetic resonance (MR) venography, a quick and a non-invasive imaging modality, is successfully used to detect DVT in various settings. We had been unaware of studies with MR venography in BS. The aim of this study is to compare the diagnostic value of true fast imaging with steady-state precession magnetic resonance (True-FISP MR) venography and Doppler USG in the assessment of chronic DVT among patients with BS. 28 BS patients with chronic lower extremity DVT were studied. Common femoral (CFV) and femoral vein (FV) on both right and left sides were examined for the presence of thrombosis, recanalisation, collaterals and reflux. There are findings of chronic DVT in all Doppler USG images of 28 patients (45 of 56 FV and 35 of 56 CFV), while MR venography detects chronic thrombotic changes in 26/28 (93%) patients (43 of 52 FV and 28 of 52 CFV). Collateral veins are detected in 19 patients (19/28) with MR venography, whereas they are present in only 7 (7/28) with USG (P = 0.003). Furthermore, patients with severe post-thrombotic syndrome are more likely to have collateral formation on the MR compared to those without (12/14 vs 7/14; P = 0.043). Among patients with BS, MR venography might be an alternative or additional method to detect chronic thrombosis in the lower extremities.

Comparison of sonography with venography in the diagnosis of deep venous thrombosis.

OBJECTIVE: To compare the findings of venous sonography with contrast venography in the detection of deep venous thrombosis (DVT) of the lower limbs. DESIGN: Prospective study. SETTING: The Kenyatta National Hospital, a teaching and referral hospital in Nairobi. SUBJECTS: Fifty five limbs in 44 patients with clinical suspicion of DVT were evaluated during the seven months study period (October 2002-April 2003). The ethics committee in the institution granted approval for the study and participants gave written informed consent. INTERVENTION: Venous sonography in which a three step protocol involving B-mode gray scale compression sonography, colour and colour Doppler sonography was obtained after contrast venography in patients with clinical suspicion of DVT. The ultrasound examination was done within 24 hours of the contrast venogram. RESULTS: The overall sensitivity of venous sonography was 88.9%, specificity 91.8% and accuracy 90.9%. Considering only DVT above the calf, the sensitivity improved to 100%. An alternative diagnosis was found by ultrasound in 48.6% of the negative for DVT cases. CONCLUSION: The accuracy of venous sonography as done locally is high and comparable to that in developed countries. We recommend that for patients with clinical suspicion of DVT, venous sonography be done as the initial imaging investigation and venography be reserved for those patients with equivocal or inadequate sonography results.

Creating normograms of dural sinuses in healthy persons using computer-assisted detection for analysis and comparison of cross-section dural sinuses in the brain.

Dural sinuses vary in size and shape in many pathological conditions with abnormal intracranial pressure. Size and shape normograms of dural brain sinuses are not available. The creation of such normograms may enable computer-assisted comparison to pathologic exams and facilitate diagnoses. The purpose of this study was to quantitatively evaluate normal magnetic resonance venography (MRV) studies in order to create normograms of dural sinuses using a computerized algorithm for vessel cross-sectional analysis. This was a retrospective analysis of MRV studies of 30 healthy persons. Data were analyzed using a specially developed Matlab algorithm for vessel cross-sectional analysis. The cross-sectional area and shape measurements were evaluated to create normograms. Mean cross-sectional size was 53.27±13.31 for the right transverse sinus (TS), 46.87+12.57 for the left TS (p=0.089) and 36.65+12.38 for the superior sagittal sinus. Normograms were created. The distribution of cross-sectional areas along the vessels showed distinct patterns and a parallel course for the median, 25th, 50th and 75th percentiles. In conclusion, using a novel computerized method for vessel cross-sectional analysis we were able to quantitatively characterize dural sinuses of healthy persons and create normograms.

Sonography for deep venous thrombosis: current and future applications.

Deep venous thrombosis (DVT) is a one of the most common problems facing the clinician in medicine today. It is often asymptomatic and goes undiagnosed with potentially fatal consequences. Ultrasound has become the "gold standard" in the diagnosis of deep venous thrombosis and with proper attention to technique sensitivity of this test is approximately 97%. An understanding of anatomy, pathophysiology, and risk factors is important. Thrombus formation usually begins beneath a valve leaflet below the knee. Approximately 40% will resolve spontaneously, 40% will become organized, and 20% will propagate. Whether or not a calf vein thrombus is identified, a repeat examination in 7 to 10 days is recommended in patients with risk factors or when deep venous thrombosis is suspected. The three main risk factors for thrombus formation are age greater than 75 years, previous history of deep venous thrombosis, and underlying malignancy. Other diagnostic studies include the contrast venogram, CT or MRI venogram, Tc99m Apcitide study, and the laboratory test D-Dimer. The D-Dimer study is being used more frequently as a screening test with 99% sensitivity in detecting thrombus, whether deep venous thrombosis or pulmonary embolism. However, specificity is only approximately 50% with many conditions leading to false-positive exams. Therefore, a negative examination is useful in avoiding other diagnostic studies, but a positive one may be misleading. Conditions that can lead to a false-positive examination include, but are not limited to diabetes, pregnancy, liver disease, heart conditions, recent surgery, and some gastrointestinal diseases. Like the sonogram, two negative D-Dimer studies a week apart exclude the diagnosis of deep venous thrombosis. Compression sonography with color Doppler remains the best overall test for deep venous thrombosis. It is easy to perform, less expensive than most "high tech" studies, can be performed as a portable examination, and is highly reliable when done properly.

Influence of variability of interpretation of contrast venography for screening of postoperative deep venous thrombosis on the results of a thromboprophylactic study.

To assess interobserver variability of venography for screening for postoperative deep venous thrombosis (DVT), we used 185 bilateral ascending contrast venograms (366 lower limbs) which were performed using the long-leg film technique, in the frame of a trial of the efficacy of two low-molecular-weight-heparin fractions (initial evaluation). These venograms were submitted in a multicenter setting to three further readers who performed a serial scoring as DVT, no DVT or non-evaluable. DVTs were diagnosed in 78, 55 and 59/366 limbs (initial evaluation: 58). The proximal locations of DVTs were 16, 9 and 16 (initial evaluation: 15) and the non evaluable limbs 3, 5 and 18 (initial evaluation: 0). Apparent pairwise agreement between the three readers ranged from 87 to 90% (true coefficient of agreement Kappa 0.63-0.70). It ranged from 89 to 93% (Kappa 0.63-0.74) for the comparison between the readers and the initial evaluation. This considerable degree of disagreement among experienced readers should be taken into account in calculating sample sizes in prospective thromboprophylactic studies. Indeed, one of the two prophylactic regimens proved to be significantly (p = 0.012, p = 0.031, p = 0.049) or non-significantly (p = 0.073) superior to the other one depending upon the reading of venograms.

Percentage of inadequate phlebograms and observer agreement in thromboprophylactic multicenter trials using standardized methodology and central assessment.

This study examines inadequacy rates for phlebography in two multicenter trials for the prevention of post-operative DVT and determines inter-and intra-observer variability in evaluating phlebograms. A total of 991 (I) and 385 (II) patients underwent bilateral phlebography in two studies of thromboprophylaxis. Phlebography was performed using a standard method designed to visualize and assess all deep veins. Each vein was scored as normal, DVT or inadequate by both local and central assessment. The study showed low inadequacy rates for phlebograms of 12.2% (121/991) and 6.5% (25/385). Inter-observer agreement (local vs. central assessment) was moderate in both studies (I: 74.8%, Kappa-value 0.41; II: 82.6%, Kappa-value 0.51). Good intra-observer agreement (within the central assessment group) was observed (I:88.8%, Kappa-value 0.75). This study demonstrates low inadequacy rates for phlebograms using a standardized methodology and superior intra-observer agreement compared to inter-observer agreement and supports the importance of central assessment of phlebograms in thromboprophylactic multicenter trials to reduce observer variability.

Diagnostic accuracy of compression ultrasonography for the detection of asymptomatic deep venous thrombosis in medical patients--the TADEUS project.

We assessed the accuracy of venous compression ultrasonography (CUS) for the detection of asymptomatic deep vein thrombosis in 122 consecutive patients, with a mean age of 69 years, who were hospitalised in an internal medicine unit. All included patients had CUS within 48 h of admission. Twelve out of 17 patients with a positive CUS underwent phlebography, as the others withdrew their consent, whereas the remaining 105 patients with a negative serial CUS testing were clinically followed-up at 3 months. We found that CUS had a sensitivity and a specificity of respectively 1 (95% CI, 0.73 to 1) and 1 (95% CI, 0.96 to 1) for the detection of asymptomatic deep vein thrombosis. Kappa-coefficients for intra-observer and inter-observer agreements were respectively 0.88 and 0.56. We concluded that venous compression ultrasonography, performed as described, fulfils requirements of a screening test that could be available for prophylactic clinical trials or epidemiological researches.

Exclusion of deep venous thrombosis with D-dimer testing--comparison of 13 D-dimer methods in 99 outpatients suspected of deep venous thrombosis using venography as reference standard.

In a direct assay comparison we evaluated the diagnostic performance of 10 novel D-Dimer assays for the exclusion of deep venous thrombosis (DVT). In addition, 3 conventional ELISA D-Dimer assays were included as reference tests. The study was performed in 99 consecutive outpatients referred to the emergency department for clinical suspicion of DVT. Venography was used as reference standard and demonstrated the presence of DVT in 50 patients (6 patients with isolated distal DVT and 44 patients with proximal DVT). The qualitative D-Dimer assays Minutex and SimpliRED and the quantitative BC DD showed overall sensitivities (for proximal and distal DVT) of only 80-83% with specificities that ranged from 87 to 94%. Overall sensitivity was 94% for the qualitative INSTANT I.A. and 98% for the quantitative Turbiquant at a cut-off level equal to the detection limit. Using different cut-off levels a sensitivity of 100% for proximal DVT and for proximal as well as distal DVT could be obtained for NycoCard, IL DD, Liatest, Tinaquant and VIDAS D-Dimer assays with specificities that ranged from 31% (NycoCard) to 71% (VIDAS) for proximal DVT and from 12% (NycoCard) to 47% (IL DD) for overall DVT. At a cut-off level equal to the upper limit of the reference range only Tinaquant and VIDAS showed a sensitivity of 100% for proximal as well as for distal DVT with a specificity of 39% and 41% respectively. The results of this study suggest that the VIDAS and Tinaquant D-Dimer assays have the highest sensitivity for the exclusion of DVT in outpatients. In outpatients that have a low or moderate pretest probability for DVT, these tests may be used in management studies where anticoagulation is withheld on the basis of D-Dimer testing alone.

Accuracy of magnetic resonance imaging in the diagnosis of deep vein thrombosis in asymptomatic patients with injuries of the lower extremity. A pilot study.

This is a prospective comparative study of magnetic resonance imaging (MRI) of the deep veins versus contrast venography in consecutive patients treated for various injuries to their lower extremities, showing no clinical symptoms of deep vein thrombosis. The majority of examinations referred to in this study were performed according to the following methodology: First, the patient was subjected to MRI. Subsequently, within a 24-h interval, he/she was subjected to contrast venography. The acquired results were compared in a blinded manner. The diagnostic indices for MRI were calculated on the assumption that the results of contrast venography were sure to give an accurate indication of either presence or absence of thrombosis. Thirty-six patients were included in the study, of which 27 (15 males) completed it. The overall incidence of distal deep venous thrombosis (DVT) was 22% (6/27). One patient showed extension of a crural thrombus into the popliteal vein. MRI did not detect any of the thrombi. This lack of result was ascribed to failure to fully demonstrate all segments of the crural veins. However, MRI did show three proximal thrombi in the superficial femoral vein, which were not shown by the venograms. Thus, both the sensitivity and specificity of MRI were 0%, so MRI proved to be of no value in the diagnosis of asymptomatic deep venous thrombosis in this study.