Comparative occupational radiation exposure between fixed and mobile imaging systems.

OBJECTIVE: Endovascular intervention exposes surgical staff to scattered radiation, which varies according to procedure and imaging equipment. The purpose of this study was to determine differences in occupational exposure between procedures performed with fixed imaging (FI) in an endovascular suite compared with conventional mobile imaging (MI) in a standard operating room. METHODS: A series of 116 endovascular cases were performed over a 4-month interval in a dedicated endovascular suite with FI and conventional operating room with MI. All cases were performed at a single institution and radiation dose was recorded using real-time dosimetry badges from Unfors RaySafe (Hopkinton, Mass). A dosimeter was mounted in each room to establish a radiation baseline. Staff dose was recorded using individual badges worn on the torso lead. Total mean air kerma (Kar; mGy, patient dose) and mean case dose (mSv, scattered radiation) were compared between rooms and across all staff positions for cases of varying complexity. Statistical analyses for all continuous variables were performed using t test and analysis of variance where appropriate. RESULTS: A total of 43 cases with MI and 73 cases with FI were performed by four vascular surgeons. Total mean Kar, and case dose were significantly higher with FI compared with MI. (mean ± standard error of the mean, 523 ± 49 mGy vs 98 ± 19 mGy; P < .00001; 0.77 ± 0.03 mSv vs 0.16 ± 0.08 mSv, P < .00001). Exposure for the primary surgeon and assistant was significantly higher with FI compared with MI. Mean exposure for all cases using either imaging modality, was significantly higher for the primary surgeon and assistant than for support staff (ie, nurse, radiology technologist) beyond 6 feet from the X-ray source, indicated according to one-way analysis of variance (MI: P < .00001; FI: P < .00001). Support staff exposure was negligible and did not differ between FI and MI. Room dose stratified according to case complexity (Kar) showed statistically significantly higher scattered radiation in FI vs MI across all quartiles. CONCLUSIONS: The scattered radiation is several-fold higher with FI than MI across all levels of case complexity. Radiation exposure decreases with distance from the radiation source, and is negligible outside of a 6-foot radius. Modern endovascular suites allow high-fidelity imaging, yet additional strategies to minimize exposure and occupational risk are needed.

Dynamic multidetector CT and non-contrast-enhanced MR for right adrenal vein imaging: comparison with catheter venography in adrenal venous sampling.

OBJECTIVES: To evaluate visualization of the right adrenal vein (RAV) with multidetector CT and non-contrast-enhanced MR imaging in patients with primary aldosteronism. METHODS: A total of 125 patients (67 men) scheduled for adrenal venous sampling (AVS) were included. Dynamic 64-detector-row CT and balanced steady-state free precession-based non-contrast-enhanced 3-T MR imaging were performed. RAV visualization based on a four-point score was documented. Both anatomical location and variation on cross-sectional imaging were evaluated, and the findings were compared with catheter venography as the gold standard. RESULTS: The RAV was visualized in 93.2% by CT and 84.8% by MR imaging (p = 0.02). Positive predictive values of RAV visualization were 100% for CT and 95.2% for MR imaging. Imaging score was significantly higher in CT than MR imaging (p < 0.01). The RAV formed a common trunk with an accessory hepatic vein in 16% of patients. The RAV orifice level on cross-sectional imaging was concordant with catheter venography within the range of 1/3 vertebral height in >70% of subjects. Success rate of AVS was 99.2%. CONCLUSIONS: Dynamic CT is a reliable way to map the RAV prior to AVS. Non-contrast-enhanced MR imaging is an alternative when there is a risk of complication from contrast media or radiation exposure. KEY POINTS: Dynamic CT and non-contrast-enhanced MR imaging detect the right adrenal vein (RAV). Dynamic CT can visualize the RAV more than non-contrast-enhanced MR imaging. Mapping the RAV helps to achieve successful adrenal venous sampling. Sixteen per cent of RAVs share the common trunk with accessory hepatic veins.

A Coaxial Guide Wire-Catheter Technique to Facilitate Right Adrenal Vein Sampling: Evaluation in 76 Patients.

A technique to facilitate blood sampling from the right adrenal vein is described. Between May 2012 and February 2015, 148 adrenal vein sampling (AVS) procedures were attempted. In 72 procedures, a simple 5-F end-hole catheter was employed. In 76, a coaxial guide wire technique was used when blood could not be aspirated, whereby a 0.018-inch guide wire was passed through the catheter and into a branch of the right adrenal vein and the sample was drawn around the wire by using a side-arm adaptor. Successful sampling was achieved in 71 of the 72 catheter-only procedures (98.6%) and in 75 of the 76 coaxial wire-assisted procedures (98.7%). This simple technique may eliminate the need for multiple catheter exchanges during AVS.

Cerebral CT Venography Using a 320-MDCT Scanner With a Time-Density Curve Technique and Low Volume of Contrast Agent: Comparison With Fixed Time-Delay Technique.

OBJECTIVE: The purpose of this study was to compare a cerebral CT venography (CTV) technique performed on a 320-MDCT scanner with the use of a time-density curve (TDC) and a small volume of IV contrast medium (35 mL, with 15 mL used for the test bolus) with CTV performed using an established reference technique in which scanning is performed at a fixed time delay of 30 seconds with the use of a larger volume of contrast medium (100 mL). MATERIALS AND METHODS: The time of peak enhancement was determined from the TDC generated from a scan in which a test bolus dose was used. CTV was performed at the time of peak enhancement. The diagnostic quality of 31 CTV venograms acquired using this technique was compared retrospectively with the diagnostic quality of 29 CTV venograms obtained at a fixed time delay of 30 seconds. The densities in the major venous sinuses and the degree of arterial contamination on the scans acquired using the two techniques were compared using objective and semiobjective methods. The semiobjective assessments were made independently by two neuroradiologists. RESULTS: Attenuation was higher in the venous structures seen on CTV images acquired using the TDC technique. Of the scans obtained using the TDC technique, the proportion deemed to be of good quality, on the basis of a grading scale, was statistically significantly higher (p < 0.05). Also, the degree of arterial contamination was statistically significantly lower (p < 0.05). The interrater agreement for semiobjective assessments ranged from good to very good. CONCLUSION: We describe a CTV technique performed using a low volume of IV contrast medium and a TDC on a 320-MDCT scanner. This technique provides better venous opacification and lower arterial contamination compared with use of the fixed time-delay technique.

[Obstructive scleroobliteration as atreatment of varicocele].

Authors developed and used the method of obstructive scleroobliteration with use of occlusive balloon catheter as a treatment for 32 patients. Advantages of this method: 1. Possibility of scleroobliteration in isolated area of the left internal testicular vein and its branches. 2 Improvement of sclerosant influence on venous wall by means of aspiration of blood and contrast agent of blocked vein. 3. Decrease of contrast agent by means of it aspiration after performed phlebography. 4. Prophylaxis of negative effect (allergy, thrombotic complications) of sclerosant by means of it partial aspiration and extravasal compression of proximal part of vein. 5. No late relapse. This method allow to perform an effective scleroobliteration with exclusion of testicular vein and venous collateral without special technical skills and cost increase. Aspiration of sclerosant in a lumen of vein allows to decrease the amount of surgical complications.

Multidetector CT of blunt traumatic venous injuries in the chest, abdomen, and pelvis.

Venous injuries as a result of blunt trauma are rare. Even though current protocols for multidetector computed tomography (CT) of patients with trauma are designed to evaluate primarily the solid organs and arteries, blunt venous injuries may nevertheless be identified, or at least suspected, on the basis of the multidetector CT findings. Venous injuries are associated with high morbidity and mortality rates. Diagnosis of a possible venous injury is crucial because the physical findings of a venous injury are nonspecific and may be absent. This article aims to make the radiologist aware of various venous injuries caused by blunt trauma and to provide helpful hints to aid in the identification of venous injuries. Multidetector CT technology, in combination with interactive manipulation of the raw dataset, can be useful in the creation of multiplanar reconstructed images and in the identification of a venous injury caused by blunt trauma. Familiarity with direct and indirect signs of venous injuries, as well as with examples of blunt traumatic venous injuries in the chest, abdomen, and pelvis, will help in the diagnosis of these injuries.

Indirect computed tomography venography with a low-tube-voltage technique: reduction in the radiation and contrast material dose--a prospective randomized study.

OBJECTIVE: The objective of the study was to investigate the effects of low-tube-voltage computed tomography (CT) venography on qualitative and quantitative image parameters and the radiation dose. METHODS: Eighty-eight studies on 84 patients underwent pelvic and lower-extremity CT venography under protocol A (standard 120 kV with 150 mL of contrast material, n = 44) or protocol B (80 kV with 100 mL of contrast material, n = 44) on a 64-detector CT scanner. We compared the dose length product in the 2 protocols. Two blinded observers measured CT attenuation in the veins, the image noise, contrast-to-noise ratio, and figure of merit. RESULTS: The mean dose length product was significantly lower under protocol B than A (603.2 [SD, 67.2] vs 1131.7 [SD, 67.0] mGy × cm) (P < 0.01). Mean CT attenuation of the veins was significantly greater with protocol B (125.3 [SD, 16.2] vs 106.1 [SD, 16.0] Hounsfield units) (P < 0.01), and the mean image noise was also significantly higher under protocol B (6.6 [SD, 0.8] vs 4.9 [SD, 0.7] Hounsfield units) (P < 0.01). There was no difference in contrast-to-noise ratio (P = 0.46). Figure of merit was significantly higher under protocol B (P < 0.01). CONCLUSIONS: Computed tomography venography with a low-tube-voltage technique allows reducing the radiation dose and the amount of contrast material without image quality degradation.

Persistent left superior vena cava: review of the literature, clinical implications, and relevance of alterations in thoracic central venous anatomy as pertaining to the general principles of central venous access device placement and venography in cancer patients.

Persistent left superior vena cava (PLSVC) represents the most common congenital venous anomaly of the thoracic systemic venous return, occurring in 0.3% to 0.5% of individuals in the general population, and in up to 12% of individuals with other documented congential heart abnormalities. In this regard, there is very little in the literature that specifically addresses the potential importance of the incidental finding of PLSVC to surgeons, interventional radiologists, and other physicians actively involved in central venous access device placement in cancer patients. In the current review, we have attempted to comprehensively evaluate the available literature regarding PLSVC. Additionally, we have discussed the clinical implications and relevance of such congenital aberrancies, as well as of treatment-induced or disease-induced alterations in the anatomy of the thoracic central venous system, as they pertain to the general principles of successful placement of central venous access devices in cancer patients. Specifically regarding PLSVC, it is critical to recognize its presence during attempted central venous access device placement and to fully characterize the pattern of cardiac venous return (i.e., to the right atrium or to the left atrium) in any patient suspected of PLSVC prior to initiation of use of their central venous access device.

Equine venography and its clinical application in North America.

The digital venogram uses contrast radiography to evaluate the soft tissues and vasculature of the foot, thus identifying pathology attributable to laminitis. Pathology can be detected before changes appear on plain-film radiographs. When used in conjunction with clinical and radiographic findings, information gained from a venographic study informs and directs treatment. Serial venograms assess the response to treatment and help determine prognosis early in the course of therapy. If the venographic contrast pattern does not improve, either the treatment needs to be altered, or the damage is so extensive that there can be no favorable response to treatment.

A new discrete dipole kernel for quantitative susceptibility mapping.

PURPOSE: Most approaches for quantitative susceptibility mapping (QSM) are based on a forward model approximation that employs a continuous Fourier transform operator to solve a differential equation system. Such formulation, however, is prone to high-frequency aliasing. The aim of this study was to reduce such errors using an alternative dipole kernel formulation based on the discrete Fourier transform and discrete operators. METHODS: The impact of such an approach on forward model calculation and susceptibility inversion was evaluated in contrast to the continuous formulation both with synthetic phantoms and in vivo MRI data. RESULTS: The discrete kernel demonstrated systematically better fits to analytic field solutions, and showed less over-oscillations and aliasing artifacts while preserving low- and medium-frequency responses relative to those obtained with the continuous kernel. In the context of QSM estimation, the use of the proposed discrete kernel resulted in error reduction and increased sharpness. CONCLUSION: This proof-of-concept study demonstrated that discretizing the dipole kernel is advantageous for QSM. The impact on small or narrow structures such as the venous vasculature might by particularly relevant to high-resolution QSM applications with ultra-high field MRI - a topic for future investigations. The proposed dipole kernel has a straightforward implementation to existing QSM routines.

Imaging of the inferior vena cava with MDCT.

OBJECTIVE: The purpose of this pictorial essay is to illustrate the role of MDCT in the diagnosis of disease processes affecting the inferior vena cava (IVC). CONCLUSION: High-speed MDCT has the potential to replace traditional imaging techniques in the evaluation of pathologic processes involving the IVC. The ability to acquire near-isotropic data allows high-quality reconstructions in the sagittal and coronal planes and thus overcomes one of the major limitations of CT in evaluating the IVC.

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.

[Interventional radiology techniques in the treatment of Budd-Chiari syndrome]. / Zastosowanie metod radiologii interwencyjnej w zespole Budd-Chiari.

Budd-Chiari syndrome (BCS) is rare clinical state characterized by the stenosis or complete obstruction of hepatic veins. Currently interventional radiology techniques are more frequently used as a single method of treatment or as a bridge to liver transplantation. This paper presents current interventional radiology techniques used in BCS treatment. Depending on etiology of BCS two major techniques are used: transjugular intrahepatic portocaval shunts (TIPS) or percutaneous angioplasties of stenosed hepatic veins. We also present selected cases of BCS diagnosed and treated in our Department in years 1999-2003.

A pilot study of patient-specific cardiovascular MDCT dose maps and their utility in estimating patient-specific organ and effective doses in obese patients.

BACKGROUND: Estimates of effective dose (E) for cardiovascular CT are obtained from a scanner-provided dose metric, the dose-length product (DLP), and a conversion factor. These estimates may not adequately represent the risk of a specific scan to obese adults. OBJECTIVE: Our objective was to create dose maps sensitive to patient size and anatomy in the irradiated region from a patient's own CT images and compare measured E (EDoseMap) to doses determined from standard DLP conversion (EDLP) in obese adults. METHODS: 21 obese patients (mean body mass index, 39 kg/m(2)) underwent CT of the pulmonary veins, thoracic aorta, or coronary arteries. DLP values were converted to E. A Monte Carlo tool was used to simulate X-ray photon interaction with virtual phantoms created from each patient's image set. Organ doses were determined from dose maps. EDoseMap was computed as a weighted sum of organ doses multiplied by tissue-weighting factors. RESULTS: EDLP (mean ± SD, 5.7 ± 3.3 mSv) was larger than EDoseMap (3.4 ± 2.4 mSv) (difference = 2.3; P < .001). CONCLUSION: Dose maps derived from patient CT images yielded lower effective doses than DLP conversion methods. Considering over all patient size, organ size, and tissue composition could lead to better dose metrics for obese patients.

Multidetector cardiac tomography: a useful tool before cardiac resynchronization therapy.

BACKGROUND: Left ventricular lead placement in a suitable coronary vein is a key determi-nant of responsiveness to cardiac resynchronization therapy (CRT). Multidetector cardiac tomography (MDCT) is a non-invasive alternative to depict cardiac venous anatomy although coronary sinus (CS) retrograde venography (RV) is the gold standard. The aim of this study was to evaluate the accuracy of MDCT to determine the presence of CS tributaries before CRT. METHODS: A retrospective analysis of 41 consecutive patients eligible to CRT was performed. MDCT was assessed in all patients before CRT and RV was achieved in 39 patients. Both methods evaluated the presence of the inferior interventricular vein (IIV), posterior vein (PV) and lateral main vein (LMV). CS ostium diameter and distance between the CS ostium and right atrium (RA) lateral wall were also measured. RESULTS: The IIV was identified in 100% of MDCT and in 43.6% of RV. In comparison to RV, the MDCT's sensitivity to identify PV and LMV was 100% for both, kappa coefficient of 0.792 (CI 95% 0.46-0.93) and 0.69 (CI 95% 0.46-0.91), respectively. There was no significant difference between ischemic and non-ischemic patients regarding the presence of PV or LMV. Median CS antero-posterior diameter was 10.3 mm (IQR 7.5-13) and supero-inferior was 14.1 mm (IQR 11.5-17) (p < 0.01). A positive correlation (p < 0.001) between echocardiographic RA area and the distance from CS ostium to the RA lateral wall in the MDCT was observed. CONCLUSIONS: MDCT is as accurate as RV to depict CS and its tributaries (IIV, PV, LMV), and it could be useful as a non-invasive technique before CRT.

Diagnosis of deep venous thrombosis in obstetrics and gynecology by impedance phlebography.

The accurate diagnosis of deep venous thrombosis is fundamental in reducing the morbidity and mortality from thromboembolism in obstetrics and gynecology. This is the first report of the use of a noninvasive diagnostic technique, occlusive cuff impedance phlebography (IPG), on an obstetric and gynecologic service. One hundred sixteen patients were examined by IPG with an overall diagnostic accuracy of 95.6% (sensitivity, 87.5%; specificity, 93.8%). Ninety-one patients had symptoms suggestive of deep venous thrombosis, but this diagnosis was confirmed in only 26.3%. The use of IPG to screen high-risk patients prospectively and evaluate patients with pulmonary emboli is discussed. IPG is ideally suited as a diagnostic method in obstetrics and gynecology because it is accurate, noninvasive, and nonradiologic, and it may be performed at the patient's bedside.

Transillumination of the angular and frontal veins.

A 500-W fiber optics cold light used to transilluminate the angular and frontal veins allowed quick, accurate delineation of the veins for percutaneous orbital venography. It also allowed the surgeon to avoid cutting the angular vein when operating on the lacrimal sac.

Noninvasive techniques for evaluating peripheral vascular and extracranial cerebrovascular diseases.

Five hundred and fifty-eight patients have been evaluated at the peripheral vascularocular pulse blood flow laboratory over a year. The accurate correlations with angiography in the peripheral arterial investigation has been 100%, the cerebrovascular investigation has been 75% and the venous correlation has been 86 2/3%. Even though the results from ocular testing are slightly lower than reported by Kartchner and McRae, we believe that the results emphasize the delicacy of instrumentation and the degree of refinement necessary in reading of the tests. We do think, however, that a 75% accuracy does indicate this method to be of significant benefit as a noninvasive stroke screening procedure.