Conversion from dose-length product to effective dose in computed tomography venography of the lower extremities

For radiation dose assessement of computed tomography (CT), effective dose (ED) is often estimated by multiplying the dose-length product (DLP), provided automatically by the CT scanner, by a conversion factor. We investigated such conversion in CT venography of the lower extremities performed in conjunction with CT pulmonary angiography. The study subjects consisted of eight groups imaged using different scanners and different imaging conditions (five and three groups for the GE and Siemens scanners, respectively). Each group included 10 men and 10 women. The scan range was divided into four anatomical regions (trunk, proximal thigh, knee and distal leg), and DLP was calculated for each region (regional DLP). Regional DLP was multiplied by a conversion factor for the respective region, to convert it to ED. The sum of the ED values for the four regions was obtained as standard ED. Additionally, the sum of the four regional DLP values, an approximate of the scanner-derived DLP, was multiplied by the conversion factor for the trunk (0.015 mSv/mGy/cm), as a simplified method to obtain ED. When using the simplified method, ED was overestimated by 32.3%−70.2% and 56.5%−66.2% for the GE and Siemens scanners, respectively. The degree of overestimation was positively and closely correlated with the contribution of the middle and distal portions of the lower extremities to total radiation exposure. ED/DLP averaged within each group, corresponding to the conversion factor, was 0.0089−0.0114 and 0.0091−0.0096 mSv/mGy/cm for the GE and Siemens scanners, respectively. In CT venography of the lower extremities, ED is greatly overestimated by multiplying the scanner-derived DLP by the conversion factor for the trunk. The degree of overestimation varies widely depending on the imaging conditions. It is recommended to divide the scan range and calculate ED as a sum of regional ED values.

Comparison study of image quality at various radiation doses for CT venography using advanced modeled iterative reconstruction

Objective We compared the image quality according to the radiation dose on computed tomography (CT) venography at 80 kVp using advanced modeled iterative reconstruction for deep vein thrombus and other specific clinical conditions considering standard-, low-, and ultralow-dose CT. Methods In this retrospective study, 105 consecutive CT venography examinations were included using a third-generation dual-source scanner in the dual-source mode in tubes A (reference mAs, 210 mAs at 70%) and B (reference mAs, 90 mAs at 30%) at a fixed 80 kVp. Two radiologists independently reviewed each observation of standard- (100% radiation dose), low- (70%), and ultralow-dose (30%) CT. The objective quality of large veins and subjective image quality regarding lower-extremity veins and deep vein thrombus were compared between images according to the dose. In addition, the CT dose index volumes were displayed from the images. Results From the patients, 24 presented deep vein thrombus in 69 venous segments of CT examinations. Standard-dose CT provided the lowest image noise at the inferior vena cava and femoral vein compared with low- and ultralow-dose CT (p < 0.001). There were no differences regarding subjective image quality between the images of popliteal and calf veins at the three doses (e.g., 3.8 ± 0.7, right popliteal vein, p = 0.977). The image quality of the 69 deep vein thrombus segments showed equally slightly higher scores in standard- and low-dose CT (4.0 ± 0.2) than in ultralow-dose CT (3.9 ± 0.4). The CT dose index volumes were 4.4 ± 0.6, 3.1 ± 0.4, and 1.3 ± 0.2 mGy for standard-, low-, and ultralow-dose CT, respectively. Conclusions Low- and ultralow-dose CT venography at 80 kVp using an advanced model based iterative reconstruction algorithm allows to evaluate deep vein thrombus and perform follow-up examinations while showing an acceptable image quality and reducing the radiation dose.

Advantages of Colour-Coded Dual-Energy CT Venography in Emergency Neuroimaging

The objective of this Pictorial Review is to describe the use of colour-coded Dual-Energy CT (DECT) to aid in the interpretation of CT Venography (CTV) of the head for emergent indications. We describe a DE CTV acquisition and post-processing technique that can be readily incorporated into clinical workflow. Colour-coded DE CTV may aid the identification and characterization of dural venous sinus abnormalities and other cerebrovascular pathologies, which can improve diagnostic confidence in emergent imaging settings.

MRI and CT-venography in the diagnosis of hemodynamic disturbances in patients with chronic lower extremities venous disorders. Part III. Possibilities of CT-investigation in diagnosing of venous hemodynamics violations

As a result of solving a large number of technical problems (increasing the area of anatomical coverage and scanning speed, increasing the signal-to-noise ratio, improving spatial and contrast resolution, building a color image quality in 3D mode, significantly reducing the radiation dose), the method of computed tomography imaging of the vascular system has won a leading position in the world today. However, if CT Angiography is used everywhere and daily in the diagnosis of arterial pathology, this method has not yet received clinical recognition in patients with chronic venous diseases.This review of the literature analyzes the scientific data published in the world on the results of CT Venography. Methods of indirect and direct contrast CT Venography are described. The possibility of using contrast CT Venography in the diagnosis of deep vein thrombosis is shown, where the accuracy, sensitivity and specificity of the method according to foreign authors is up to 97.9%, 96.8% and 100%, respectively. This method acquires particular importance in the diagnosis of pelvic vein thrombosis and inferior Vena cava, where the informative value of USDS is lower. The second clinical direction that is actively developing today is the combined use of CT Venography and CT Angiopulmonography in the diagnosis of a deadly complication of pulmonary embolism. The prospects of these attempts are preferable by the following advantages: the single-time study and the absence of the need for additional administration of contrast agents, the speed of scanning, and obtaining additional information about the state of the peripheral venous system in patients with venous thromboembolism.Another and irreplaceable tool of contrast-enhanced CT Venography can become in the study of the features of the topographic and anatomical structure of the venous bed. Using their own research, the authors demonstrate the possibilities of direct CT Venography in the visualization of the venous system of the lower extremities.The need for more accurate topical diagnostics with 3D visualization of the venous system of the lower extremities and pelvis by CT-Venography is due to the growing interest in recent years of vascular and interventional surgeons to test and more actively implement endovasal methods of correction of venous blood flow in phlebological practice.

Developmental anomalies of the superior vena cava and its tributaries: What the radiologist needs to know?

Deviations from the normal process of embryogenesis can result in various developmental anomalies of the superior vena cava (SVC). While these anomalies are often asymptomatic, they assume clinical importance during interventions such as central venous catheterisations and pacemaker implantations and during cardiothoracic surgeries while instituting cardiopulmonary bypass and for creation of cavo-pulmonary connections. Role of imaging in identifying these anomalies is indispensable. Cross-sectional imaging techniques like CT venography and magnetic resonance (MR) venography allow direct visualisation and consequently increased detection of anomalies. CT venography plays an important role in detection of SVC anomalies as it is readily available, has excellent spatial resolution, short acquisition times and potential for reconstruction of images in multiple planes. This pictorial review focuses on the developmental anomalies of the SVC and its tributaries highlighting their embryological basis, imaging appearances on CT venography and potential clinical implications, where relevant.

Vai trò của hội chứng May – Thurner trong bệnh lý huyết khối tĩnh mạch sâu chi dưới

Nhóm I: Hồi cứu hồ sơ và khảo sát lại CT Scan, chúng tôi ghi nhận 30 trường hợp huyết khối tĩnh mạch sâu chi dưới (HKTMSCD) được can thiệp lấy huyết khối bằng Fogarty, trong đó có 9/30 trường hợp được xác định HC May – Thurner. Tuổi trung bình là 44,4, tỷ lệ nam/nữ là 1/8. Tỷ lệ tái huyết khối sớm cao là 89% và điểm số VCSS (Venous Clinical Severity Score) trung bình là 7,625. Can thiệp sửa chữa tổn thương giải phẫu của HC May-Thurner chỉ thành công về mặt kỹ thuật ở 01 trường hợp. Nhóm II: Can thiệp điều trị lấy huyết khối cho 60 trường hợp, chụp khảo sát trong mổ kết hợp với hình ảnh CT cản quang thì tĩnh mạch, ghi nhận được 37/60 (61,6%) trường hợp có HC May-Thurner. Can thiệp sửa chữa tổn thương bằng nong bóng – stent thành công về mặt kỹ thuật là 35/37 (94,6%). Tỷ lệ tái huyết khối sớm cải thiện hơn rõ so với nhóm I 21,6% (8/37) và điểm số VCSS trung bình cũng cải thiện hơn là 5,025. HKTMSCD do HC May-Thurner là bệnh cảnh thường gặp trên lâm sàng. Cần lưu ý hướng đến chẩn đoán này khi người bệnh có biểu hiện sưng phù 1 bên chân Trái. Phương tiện chẩn đoán xác định dựa vào hình ảnh học với vai trò của chụp CT Venography. Điều trị theo phác đồ hiện nay là lấy huyết khối với tiêu sợi huyết tại chỗ và sửa chữa thương tổn giải phẫu bằng nong bóng và stent

CT venography correlate of transverse sinus stenosis and venous transstenotic pressure gradient in unilateral pulsatile tinnitus patients with sigmoid sinus wall anomalies

Objectives To investigate the correlation between transverse sinus stenosis (TSS) and transstenotic pressure gradient (TPG) in unilateral pulsatile tinnitus (PT) patients with sigmoid sinus wall anomalies (SSWA). Methods Fifty-seven patients with unilateral venous PT were retrospectively included. All of them underwent CT venography and catheter manometry, accompanied with SSWA. The degree, length, shape (intrinsic/extrinsic/dysplasia), location (proximal/middle/distal, referring to the relative position of TSS and the Labbé vein junction) of TSS, the types of SSWA (dehiscence/diverticulum), and the degree of transverse sinus outflow laterality were assessed, and the correlations with ipsilesional TPG were analyzed. Results The mean value of ipsilesional TPG was 7.61 ± 0.52 mmHg. The degree and length of ipsilesional TSS were positively correlated with TPG (p < 0.001, p’ < 0.001), respectively. TPG was significantly larger in patients with contralateral transverse sinus dysplasia than those without (p = 0.023) and significantly smaller in patients with ipsilesional sigmoid sinus diverticulum than those with isolated dehiscence (p = 0.001). No statistical difference in TPG was shown between ipsilesional TSSs of different shapes or locations (p > 0.05). No correlation was noted between the degree of ipsilesional transverse sinus outflow laterality and TPG (p = 0.051). Stepwise linear regression indicated that the degree (β = 9.207, 95% CI = 3.558–14.856), length (β = 0.122, 95% CI = 0.025–0.220) of ipsilesional TSS, and contralateral transverse sinus dysplasia (β = 1.875, 95% CI = 0.220–3.530) were significantly correlated with TPG (R2 = 0.471). Conclusions The degree, length of ipsilesional TSS, and contralateral transverse sinus dysplasia may be used to predict TPG in unilateral PT patients with SSWA. Key Points • CT venography may act as a screening tool to help low-probability unilateral pulsatile tinnitus (PT) patients with sigmoid sinus wall anomalies (SSWA) avoid invasive catheter manometry. • The degree and length of ipsilesional transverse sinus stenosis (TSS) are positively correlated with transtenotic pressure gradient (TPG) in unilateral PT patients with SSWA. • Ipsilesional TPG is larger in unilateral PT patients with contralateral transverse sinus dysplasia than those without and is smaller in unilateral PT patients with sigmoid sinus diverticulum than those with isolated dehiscence.

Multidetector spiral computed tomography–venography in outpatient phlebological practice

Duplex ultrasound scanning (DUS) and magnetic resonance imaging are sometimes insufficient to meet our clinical needs due to specifics of given pathology and intrinsic technical limitations of these methods. This study aims to assess the need for multispiral computed tomography–venography (CT-venography) and to evaluate its diagnostic capabilities for various disorders in primary ambulatory patients in phlebology practice.Material and Methods. From January, 2017 to December,2019, a total of 10,112 patients sought initial consultation of a phlebologist. Upon examination, the physician assigned patients to one of the proposed categories using dedicated software. Analysis of these categories demonstrated the following pattern of morbidity: 2,167 patients (21.4%) had chronic venous disorders of class С0S-1 (CEAP classification); 4,460 patients (44.1%) had varicose veins of class C2-3 (CEAP classification); 351 patients (3.5%) had varicose veins of class C4-6; 570 patients (5.6%) had other diseases including post-thrombotic syndrome, acute thrombosis, thrombophlebitis, and venous malformations; and 2,564 patients (25.4%) were suffering from non-venous disorders. DUS was performed in all cases.Results. The study demonstrated that 260 patients required CT-venography constituting 2.6% of the total number of patients who came to the clinic in the indicated period. The direct venography with contrast medium injection through the peripheral veins was used in 156 cases (60%). Patients did not have any significant complications, such as acute kidney injury or worsening of chronic renal failure, severe allergic reactions to the contrast agent, or problems with the puncture site of peripheral veins.Conclusions: 1) CT-venography allowed to achieve the accurate three-dimensional imaging of the venous system, providing, in some cases, the necessary information for finding solutions on optimal management. 2) The need for CT-venography may occur in 2.6% of patients in ambulatory phlebology practice. 3) CT-venography is useful for diagnosing angiodysplasias, postthrombotic and non-thrombotic lesions, complicated varicose veins, especially in recurrence, and in some cases of acute deep vein thrombosis. 4) DUS is mandatory for hemodynamic assessment in all patients before CT-venography.