The value of modified time-of-flight magnetic resonance venography in evaluating anatomical variations of the internal iliac vein

Objective To evaluate the clinical value of color Doppler ultrasound(CDUS) combined with vascular enhancement technology(VET) in diagnosis of iliac vein compression syndrome(IVCS). Methods From Jan 2016 to Oct 2018, 252 patients with the lower extremities chronic venous diseases(CVD) were selected in the Second Hospital of Hebei Medical University. The ipsilateral iliac veins of the affected limbs were examined by CDUS, VET and the combined diagnosis of IVCS before X-Ray venography(XRV). Iliac vein diameter stenosis ratio(DSR)>50% in transverse section was the criterion of ultrasound diagnosis of IVCS. The stenosis site of iliac vein and indirect signs of IVCS, such as presence of collateral circulation and the retrograde flow of internal iliac vein were recorded. The cases, which had the same results in CDUS, VET and both and XRV, were divided into IVCS group and non-IVCS group. The results of XRV were taken as the gold standard, the diagnostic efficiency of the above 3 methods in diagnosis of IVCS was calculated. The cases identically diagnosed by the most effective ultrasonic method and XRV were divided into DVT group and non-DVT group according to the deep vein thrombosis in lower limbs. In the non-DVT group, there were five groups of C2-C6 on the basis of the CEAP clinical grades of CVD in lower extremity. The relationship between IVCS and different CEAP clinical grades were analyzed. The locations of common iliac vein stenosis and collateral circulation formation and internal iliac vein reverse flow were evaluated for the diagnosis of the IVCS. Results ①XRV diagnosis of IVCS was used as the gold standard. Compared with CDUS and VET alone, the sensitivity and specificity of CDUS combined with VET was the highest(all P 0.05). ④For the proportion of the iliac vein stenosis sites, the prevalence of the primary section of left common iliac vein was much higher than those of the primary section of right common iliac vein and the middle-distal sections of bilateral common iliac veins(all P 0.05). ⑤In IVCS group, which had the same results of CDUS combined with VET and XRV, there were statistical differences in the positive rate of collateral circulation and the retrograde flow of internal iliac vein(χ2=6.717, P=0.010), and the former is higher than the latter. Conclusions CDUS combined with VET has a higher diagnostic efficiency for IVCS than VET or CDUS alone. The presence of IVCS is closely related to DVT of lower extremities, but not related to clinical class of CEAP. The most common site of IVCS is the initial segment of the left common iliac vein. The presence of collateral circulation can be used as indirect indicators for the diagnosis of IVCS. Key words: Ultrasonography, Doppler, color; Vascular enhancement technology; Iliac vein compression syndrome

ObjectiveElevated shear rates are known to play a role in arterial thrombosis; however, shear rates have not been thoroughly investigated in patients with iliac vein compression syndrome (IVCS) owing to imaging limitations and assumptions on the low shear nature of venous flows. This study was undertaken to develop a standardized protocol that quantifies IVCS shear rates and can aid in the diagnosis and treatment of patients with moderate yet symptomatic compression. MethodsStudy patients with and without IVCS had their iliac vein hemodynamics measured via duplex ultrasound (US) at two of the following three vessel locations: infrarenal inferior vena cava (IVC), right common iliac vein, and left common iliac vein, in addition to acquiring data at the right and left external iliac veins. US velocity spectra were multiplied by a weighted cross-sectional area calculated from US and computed tomography (CT) data to create flow waveforms. Flow waveforms were then scaled to enforce conservation of flow across the IVC and common iliac veins. A three-dimensional (3D), patient-specific model of the iliac vein anatomy was constructed from CT and US examination. Flow waveforms and the 3D model were used as a basis to run a computational fluid dynamics (CFD) simulation. Owing to collateral vessel flow and discrepancies between CT and US area measurements, flows in internal iliac veins and cross-sectional areas of the common iliac veins were calibrated iteratively against target common iliac flow. Simulation results on mean velocity were validated against US data at measurement locations. Simulation results were postprocessed to derive spatial and temporal values of quantities such as velocity and shear rate. ResultsUsing our modeling protocol, we were able to build CFD models of the iliac veins that matched common iliac flow splits within 2% and measured US velocities within 10%. Proof-of-concept analyses (1 subject, 1 control) have revealed that patients with IVCS may experience elevated shear rates in the compressed left common iliac vein, more typical of the arterial rather than the venous circulation. These results encourage us to extend this protocol to a larger group of patients with IVCS and controls. ConclusionsWe developed a protocol that obtains hemodynamic measurements of the IVC and iliac veins from US, creates patient-specific 3D reconstructions of the venous anatomy using CT and US examinations, and computes shear rates using calibrated CFD methods. Proof-of-concept results have indicated that patients with IVCS may experience elevated shear rates in the compressed left common iliac vein. Larger cohorts are needed to assess the relationship between venous compression and shear rates in patients with IVCS as compared with controls with noncompressed iliac veins. Further studies using this protocol may also give promising insights into whether or not to treat patients with moderate, yet symptomatic compression.

We performed a prospective, blinded study to assess and compare the values of preoperative contrast venography and magnetic resonance venography in the detection of deep venous thrombosis in the thigh and pelvis of forty-five consecutive patients who had a displaced acetabular fracture. The magnetic resonance venography and contrast venography were performed an average of seven days (range, one to twenty-nine days) after the injury. Twenty-four asymptomatic thrombi were identified with magnetic resonance venography in fifteen (33 percent) of the patients. Four of the thrombi were in the superficial femoral vein, nine were in the common femoral vein, one was in the external iliac vein, seven were in the internal iliac vein, and three were in the common iliac vein. Ten (42 percent) of the twenty-four thrombi were confirmed with contrast venography; nine of them were located in the thigh. The remaining fourteen thrombi (58 percent) that had been noted on magnetic resonance venography could not be seen with contrast venography because they were located either in the deep pelvic veins or in the uninjured extremity. The thrombi in the internal iliac vein were identified only with magnetic resonance venography. Twelve of the fifteen patients who had thrombi had a filter placed in the inferior vena cava preoperatively. In eight of these patients, the filter was placed because of the findings of magnetic resonance venography alone. Magnetic resonance venography resulted in a change in the therapeutic management of ten (22 per cent) of the forty-five patients. There were no pulmonary emboli. We concluded that magnetic resonance venography is superior to contrast venography for the preoperative evaluation of proximal deep venous thrombosis in patients who have an acetabular fracture. Magnetic resonance venography is non-invasive, does not require the use of contrast medium, images the proximal aspects of both lower extremities simultaneously, and, most importantly, allows for the identification of deep venous thrombosis in the pelvis.

The valvular anatomy of the iliac venous system and its clinical implications

Diffuse generalized venulitis as the primary pathology of Behçet's disease: A comprehensive magnetic resonance venography study

Context Iliac vein compression syndrome (IVCS) or May–Thurner syndrome is an anatomically variable condition of venous outflow obstruction caused by extrinsic compression. The pathology of this condition is secondary to a partial obstruction of the common iliac vein by an overlying common iliac artery with subsequent entrapment of the left common iliac vein. Clinical presentations include, but not limited to, pain, swelling, venous stasis ulcers, and skin discoloration. With extensive deep venous thrombosis, postphlebitic syndrome, with all its sequelae, may also develop. Endovascular interventions of this syndrome have become first-line therapy. Aims To estimate the prevalence of IVCS in patients with unilateral left lower limb venous disease [chronic venous disease (CVD)], assess the sensitivity and specificity of modified computed tomography venography in the diagnosis of IVCS, and evaluate the feasibility and effectiveness of the endovascular treatment. Settings and design This was a prospective case series study. The study was performed at three tertiary referral centers in Kingdom of Saudi Arabia (Security Forces Hospital Program, Al-Noor Specialist Hospital, Makkah, Almoosa Specialist Hospital, Al-Ahsaa) and three hospitals in Egypt (Benha University Hospitals, Nile Insurance Hospital, and Kuwaiti Specialized Hospital, Benha). Patients and methods Between March 2015 and February 2018, we evaluated 369 patients with unilateral left lower limb symptomatic CVD in the outpatient clinic of vascular surgery in the study hospitals. Sixty-one symptomatic patients with IVCS who received endovascular treatment were included in our study. Statistical analysis used The initial data entry used Microsoft excel (2010 version) for logical proofreading and analysis. We expressed continuous data as mean±SD and compared continuous variables using two-sided Student’s t tests. We estimated stent patency using Kaplan–Meier method. We considered P value less than 0.05 to be statistically significant. Statistical analysis was performed by using IBM Statistical Package for the Social Sciences software (version 22 for Windows program package). Results The 1-year patency rates in the nonthrombotic and thrombotic IVCS groups were 95.7 and 80%, respectively (P=0.146). The overall primary patency rate at 1 year after treatment was 93%. Complete pain relief was achieved in 76.7% of patients. The overall edema relief rate was 78.1%. Of the 12 limbs with active ulceration before treatment, 10 (83.3%) healed completely. Conclusion IVCS is not an uncommonly encountered condition, especially among patients with unilateral left lower extremity CVD. Computed tomography venography with three-dimensional reconstruction images was more sensitive and specific as a diagnostic approach for IVCS and provided useful information for the endovascular treatment planning. Moreover, endovascular therapy is feasible and effective for treating left-sided IVCS with high technical success rate and with an acceptable complication profile. So, we concluded that endovascular treatment should be considered as the first line of therapy for patients experiencing IVCS.

Massive Pulmonary Embolism Caused by Internal Iliac Vein Thrombosis With Free-Floating Thrombus Formation in the Inferior Vena Cava

BackgroundBehçet’s Disease (BD) is a chronic multisystem vasculitis that manifests with recurrent oral/genital ulcerations and destructive inflammation affecting eyes, central nervous system, and blood vessels. Venous thrombosis is observed in...

The aim of this study was to assess the image quality and interobserver agreement of various multidetector-row computed tomographic angiography postprocessing techniques in the diagnosis of renal artery stenosis (RAS). We studied 36 patients (21 men and 15 women; mean age, 49 years) who underwent computed tomography angiography to assess renal arteries for suspected RAS. Patients were analyzed by using a multidetector-row computed tomography. Computer tomographic scans were obtained after intravenous bolus administration of 110 to 140 mL of nonionic contrast material using a 4- to 6-mL/s flow rate. We assessed every patient by using axial scans, multiplanar reconstruction (MPR), maximum intensity projection (MIP), and volume rendering (VR) techniques. For each patient and for each reconstruction method, the image quality of the main renal artery was scored as 0 for bad-quality, 1 for poor-quality, 2 for good-quality, and 3 for excellent-quality images. Two radiologists reviewed computed tomographic images independently. We calculated interobserver agreement and kappa value. We correlated the stenosis degree observed by the 2 readers with the type of reconstruction used. Overall number of renal arteries studied was 72, and we detected 24 RAS. Quality images obtained an overall (averaged between the 2 observers) value of 133 of 216, 163 of 216, and 145 of 216 for MPR, MIP, and VR, respectively. Our data underlined a statistical difference between MPR images and VR images (P < 0.001). Moreover, we noticed that the images classified as excellent were obtained from a vessel with 350 Hounsfield units or higher. Kappa value was good in MIP and VR methods evaluation but poor with the use of MPR. Reformatting techniques usually provided a high visual impact, and in our study, MIP and VR showed the best diagnostic interobserver agreement in quality and reproducibility of stenosis degree.

Objective To evaluate the diagnostic value of non-enhanced magnetic resonance venography(MRV)for deep pelvic vein disease.Methods A total of 50 patients highly suspicious of pelvic and lower extremity vein disease were enrolled in the present study,and they were subjected to lower extremity vascular 2D-TOF MRV(two-dimensional time-of-flight MR venography)examination with the following technical parameter:echo time 5-7ms,repetition time 35-45 ms,and flip angle 35°-45°.The MRV range included the scanning from low segment of inferior vena cava(IVC)to the popliteal vein(PV);the image quality was scaled into grades,and the results of MRV were compared with those of ultrasound and DSA.Results The images of all 50 patients clearly showed the scanning from low segment of IVC to the PV and its branches,with the diagnostic accuracy reaching 96.0%.The images of 25 patients clearly showed a total of 723 veins,including IVC,common iliac vein(CIV),internal iliac vein,external iliac vein(EIV),common femoral vein,deep femoral vein,superficial femoral vein and PV,with a consistent rate of 96.4%.Thrombosis from inferior segment of IVC to EIV was shown on MRV images of 9patients,while it could not be clearly and completely manifested by B-ultrasound.Ten patients received DSA simultaneously,and the MRV results of 9were in accord with those of DSA findings.MRV of one patient with thrombosis at initial segment of CIV was shown normal on DSA.Conclusion MRV for diagnosis of lower extremity vascular lesions has the advantage of non-trauma,greater scanning range,high grade contrast,excellent image delineation and intuitive convincement, making it worth popularizing in clinic.

Introduction Communications between iliac veins in the pelvis are reported to be rare occurrences, which are mostly due to developmental abnormalities. The common iliac vein is formed by the joining of the internal and external iliac veins. Here, we present a detailed morphological and histological study of a rare communication found between the internal and external iliac veins, which would prove to be of substantial value to the knowledge of vessels in the pelvis, both for clinicians and surgeons. Materials and Methods In the present study, we came across a rare communication in the form of a ladder, between the left internal and external iliac veins in a 70-year-old male cadaver. There were two communications (named upper and lower communications) between the external and internal iliac veins, before they joined to form the common iliac vein. On naked eye observation, the lumen of the right common iliac vein appeared to be wider than on the left side. The lengths of these communications and the distance between each of their attachments have been measured and tabulated. The walls of these veins, their microscopic sections and their communication involved in the case were taken. The possible causes for these variations were congenital, owing to the complicated nature of the developmental process involved in the formation of the inferior vena cava and the venous system of the lower limb. Results The structure of all the veins involved in this case and the communications were seen to be normal. The thickness of these walls were measured and tabulated for uniformity around the circumference of the wall of these veins. All the measurements from the structural variations and from the histological observations are tabulated in our results. Conclusion The complicated development sequence of these veins could have possibly led to the persistence of these communications. Such a developmental variation does not seem to pose any threat until unless encountered under clinical or surgical interventions, as the histological structure of the walls of the communications as well as the major channels connected appeared to be normal and well-developed. The detailed morphological and histological features of these structures involved in the variation along with the possible complications have been presented in the present report. Knowledge of these variations and complications due to injury plays a key role in a clinical setup.

The valvular anatomy of the iliac venous system and its clinical implications

Pelvic congestion syndrome is a chronic condition involving varicose veins in the pelvic area, resulting in dull aching pain, pelvic heaviness, palpable varicosities, and dyspareunia. The primary diagnostic modalities, computed tomography (CT) angiography and magnetic resonance (MR) angiography, can be time-consuming, expensive, and carry the risks of diagnostic radiation (CT) and intravenous contrast (CT and MR), and may not offer dynamic vascular information (CT). Recently, an increased role for ultrasound has been proposed in the diagnosis of pelvic congestion; however, the role of transvaginal (TV) duplex ultrasound has not been thoroughly investigated. Our study aims to evaluate the utility of a TV approach in the evaluation of valvular incompetence time (VIT) in seconds of the internal iliac and adnexal veins. A waiver of consent was granted by our Institutional Review Board for this retrospective review. A cohort of 36 women undergoing ultrasound evaluation for pelvic congestion syndrome was analyzed. Transvaginal and transabdominal (TA) images were obtained with reverse Trendelenburg positioning for imaging of the internal iliac veins with Valsalva maneuver to evaluate VIT, at the same visit, and the yield of each approach was compared for the presence of VIT. The number of vessels visualized, VIT, diagnostic success, and number of abnormal vessels were recorded. Between September 2018 and February 2019, 36 women underwent both TA and TV imaging. A total of 72 (100%) internal iliac veins were visualized by TV, but only 15 (21%) by TA. Of the 72 internal iliac veins imaged, 12 (17%) were shown to have valvular incompetence by TV exam, whereas only 2 (3%) were identified by TA, both of which were identified TV. Transabdominal images, when limited, were usually due to bowel gas. Transvaginal images had a higher yield for detection of internal iliac vein VIT, suggesting that the TV approach may be more sensitive and potentially more accurate versus a TA-only protocol.

To correlate prostate-specific antigen (PSA), free to total PSA percentage (fPSA%) and prostatic acid phosphatase (PAP) levels from peripheral and pelvic venous samples with prostatectomy specimens in patients with prostate adenocarcinoma and borderline elevation of PSA. In this prospective institutional review board approved study, 7 patients with biopsy proven prostate cancer had a venous sampling procedure prior to prostatectomy (mean 3.2 days, range 1-7). Venous samples were taken from a peripheral vein (PVS), the right internal iliac vein, a deep right internal iliac vein branch, left internal iliac vein and a deep left internal iliac vein branch. Venous sampling results were compared to tumour volume, laterality, stage and grade in prostatectomy surgical specimens. Mean PVS PSA was 4.29, range 2.3-6 ng/ml. PSA and PAP values in PVS did not differ significantly from internal iliac or deep internal iliac vein samples (p > 0.05). fPSA% was significantly higher in internal iliac (p = 0.004) and deep internal iliac (p = 0.003) vein samples compared to PVS. One of 7 patients had unilateral tumour only. This patient, with left-sided tumour, had a fPSA% of 6, 6, 6, 14 and 12 in his peripheral, right internal iliac, deep right internal iliac branch, left internal iliac and deep left internal iliac branch samples respectively. There were no adverse events. fPSA%, unlike total PSA or PAP, is significantly higher in pelvic vein compared to peripheral vein samples when prostate cancer is present. Larger studies including patients with higher PSA values are warranted to further investigate this counterintuitive finding.

To assess diagnostic accuracy and interobserver variability at venous enhanced subtracted peak arterial (VESPA) magnetic resonance (MR) venography compared with those at conventional venography for the diagnosis of femoral and iliac deep venous thrombosis (DVT). A single anteroposterior maximum intensity projection (MIP) venogram of the femoral and iliac veins was constructed by using VESPA MR venography in 55 symptomatic patients suspected of having lower limb DVT. All patients also underwent conventional venography, results of which were used as the standard of reference. VESPA MR venograms were interpreted by two independent reviewers (reviewers A and B) who were unaware of other results. Sensitivity and specificity of VESPA MR venography for the diagnosis of thrombus in the femoral and iliac veins were calculated. Interobserver variability was calculated for these observations by using weighted kappa with equally spaced weights for positive, nondiagnostic, and negative studies. Nondiagnostic studies were reinterpreted separately by reviewer A on the basis of source data. Sensitivity of VESPA MR venography for the femoral veins (20 of 20) and iliac veins (seven of seven) was 100% for both reviewers. Specificity was 100% (39 of 39 for reviewer A, 40 of 40 for reviewer B) for the iliac veins and 97% (31 of 32) for the femoral veins for both reviewers. Segments in which the VESPA MR venograms were nondiagnostic were excluded from this analysis. Interobserver variability as calculated by using weighted kappa for positive, negative, and nondiagnostic studies was 0.85 for femoral veins and 0.97 for iliac veins. Interpretation of the source data led to correct diagnosis in six of six cases in which the VESPA MR venograms were nondiagnostic. VESPA MR venography yielded MIP venograms that were highly accurate for the diagnosis of DVT in femoral and iliac veins. Interpretation of the studies was also highly reproducible.