Sanjeeva P. Kalva

Quality Improvement Guidelines for the Performance of Inferior Vena Cava Filter Placement for the Prevention of Pulmonary Embolism

i PREAMBLE The membership of the Society of Interventional Radiology (SIR) Standards of Practice Committee represents experts in a broad spectrum of interventional procedures from both the private and academic sectors of medicine. Generally Standards of Practice Committee members dedicate the vast majority of their professional time to performing interventional procedures; as such they represent a valid broad expert constituency of the subject matter under consideration for standards production. Technical documents specifying the exact consensus and literature review methodologies as well as the institutional affiliations and professional credentials of the authors of this document are available upon request from SIR, 3975 Fair Ridge Dr., Suite 400 N., Fairfax, VA 22033.

Using the K-edge to improve contrast conspicuity and to lower radiation dose with a 16-MDCT: a phantom and human study.

Purpose: To study the effect of tube current (milliamperes; mA) and potential (peak kilovolt; kVp) on the attenuation values and contrast-to-noise ratios of iodine- and gadolinium-based contrast media (CM) for computed tomography angiography (CTA). Materials and Methods: Phantom Study: A water-filled phantom with five 20-mL syringes filled with 1:20 dilution of 282, 300, 370, and 400 milligrams of iodine per milliliter concentration CM and gadopentetate dimeglumine (Magnevist, Berlex Laboratories, Wayne, NJ, 0.5 mol/L) was scanned with a 16-multidetector CT using 80, 100, 120, and 140 kVp and 500-millisecond gantry rotation time. The milliampere was either fixed at 100, 200, 300, and 380 or automatically adjusted with noise indices of 15, 20, and 25 or manually adjusted to maintain a constant image noise. The attenuation value (Hounsfield unit; HU) and its standard deviation of CM in each syringe and of the water phantom were obtained. Statistical analysis was performed to determine difference between attenuation values and contrast medium-to-water contrast-to-noise ratios at various kVp and mA selection. Human Study: Three groups of patients had CTA for abdominal aortic aneurysm with similar computed tomography parameters, varying only in kVp selection of either 100 (group A), 120 (group B), or 140 (group C). Another group (group D) had CTA at 100 kVp but with the CM volume reduced to 60%. The CTA studies were evaluated for the quality of axial and 3D images; attenuation values in the aorta, superior mesenteric artery, and iliac arteries; image noise; and scanner-estimated radiation dose. Statistical analysis was performed to determine the difference in image quality and radiation dose among the groups. Results: Phantom Study: In comparison with 140 kVp, regardless of selected milliampere or noise indices, images acquired at 80, 100, and 120 kVp showed 90.8% to 94.2%, 47% to 49.7%, and 18.9% to 20.7% (P < 0.0001) increase in HU of iodine-based CM, respectively, and 62.9%, 39.6%, and 16.8% (P < 0.0001) increase in HU of gadolinium-based CM, respectively. Human Study: The axial images in all the groups were diagnostically acceptable. There was significantly inferior quality of axial images associated with greater image noise in group A and group D (P < 0.01) in comparison with group C, but there was no difference in the quality of 3D images among the 4 groups. In comparison with group C, there was significantly higher attenuation of the aorta, superior mesenteric artery, and iliac arteries in group A (P < 0.01), group B (P < 0.05), and group D (P < 0.01). The radiation dose (CT dose index volume) decreased to 12 ± 4 in groups A and D compared with 17 ± 4 in group B and 24 ± 5 in group C. Conclusions: Lower kVp increases the attenuation of iodinated and gadolinium CM. CTA of the abdominal aorta performed at low kVp results in higher attenuation in aorta with reduced radiation dose and without degrading the diagnostic image quality. The iodinated CM volume can be reduced by reducing kVp during CTA.

Quality improvement guidelines for the treatment of lower-extremity deep vein thrombosis with use of endovascular thrombus removal.

Suresh Vedantham, MD, Patricia E. Thorpe, MD, John F. Cardella, MD, Chair, Clement J. Grassi, MD, Nilesh H. Patel, MD, Hector Ferral, MD, Lawrence V. Hofmann, MD, Bertrand M. Janne d’Othée, MD, Vittorio P. Antonaci, MD, Elias N. Brountzos, MD, Daniel B. Brown, MD, Louis G. Martin, MD, Alan H. Matsumoto, MD, Steven G. Meranze, MD, Donald L. Miller, MD, Steven F. Millward, MD, Robert J. Min, MD, Calvin D. Neithamer Jr., MD, Dheeraj K. Rajan, MD, Kenneth S. Rholl, MD, Marc S. Schwartzberg, MD, Timothy L. Swan, MD, Richard B. Towbin, MD, Bret N. Wiechmann, MD, and David Sacks, MD, for the CIRSE and SIR Standards of Practice Committees

Quality Improvement Guidelines for Diagnostic Arteriography

PREAMBLE The membership of the Society of Interventional Radiology (SIR) Standards of Practice Committee represents experts in a broad spectrum of interventional procedures from the private and academic sectors of medicine. Generally, Standards of Practice Committee member dedicate the vast majority of their professional time to performing interventional procedures; as such, they represent a valid, broad expert constituency of the subject matter under consideration for standards production.

MR imaging of the gallbladder: a pictorial essay.

The gallbladder serves as the repository for bile produced in the liver. However, bile within the gallbladder may become supersaturated with cholesterol, leading to crystal precipitation and subsequent gallstone formation. The most common disorders of the gallbladder are related to gallstones and include symptomatic cholelithiasis, acute and chronic cholecystitis, and carcinoma of the gallbladder. Other conditions that can affect the gallbladder include biliary dyskinesia (functional), adenomyomatosis (hyperplastic), and postoperative changes or complications (iatrogenic). Ultrasonography (US) has been the traditional modality for evaluating gallbladder disease, primarily owing to its high sensitivity and specificity for both stone disease and gallbladder inflammation. US performed before and after ingestion of a fatty meal may also be useful for functional evaluation of the gallbladder. However, US is limited by patient body habitus, with degradation of image quality and anatomic detail in obese individuals. With the advent of faster and more efficient imaging techniques, magnetic resonance (MR) imaging has assumed an increasing role as an adjunct modality for gallbladder imaging, primarily in patients who are incompletely assessed with US. MR imaging allows simultaneous anatomic and physiologic assessment of the gallbladder and biliary tract in both initial evaluation of disease and examination of the postoperative patient. This assessment is accomplished chiefly through the use of MR imaging contrast agents excreted preferentially via the biliary system.

Clinical Practice Guidelines for Endovascular Abdominal Aortic Aneurysm Repair: Written by the Standards of Practice Committee for the Society of Interventional Radiology and Endorsed by the Cardiovascular and Interventional Radiological Society of Europe and the Canadian Interventional Radiology Association

From the Department of Radiology, Division of Vascular Imaging and Intervention (T.G.W., S.P.K., K.Y., S.W.), Massachusetts General Hospital, Boston, Massachusetts; Department of Medical Imaging (S.K.), Scarborough General Hospital, Toronto, Ontario, Canada; Department of Interventional Radiology (P.D.), West Allis Memorial Hospital, Milwaukee, Wisconsin; Department of Radiology, Division of Interventional Radiology (B.J.D.), University of Maryland Medical Center, Baltimore, Maryland; Department of Radiology (S.C.R.), University of California San Diego Medical Center, San Diego, California; and Department of Radiology (J.F.C.), Geisinger Health System, Danville, Pennsylvania. Received May 4, 2010; final revision received May 24, 2010; accepted July 11, 2010. Address corre-

Natural History and CT Appearances of Aortic Intramural Hematoma

Rupture of the vasa vasorum into the media of the aortic wall results in an aortic intramural hematoma. Characteristic findings of an aortic intramural hematoma include a crescentic hyperattenuating fluid collection at unenhanced computed tomography (CT) and a smooth, nonenhancing, thickened aortic wall at contrast material-enhanced CT. The CT appearance of untreated intramural hematomas evolves over time, and decreased attenuation is a clue to the chronicity of a hematoma. CT is particularly useful for evaluating aortic intramural hematomas because it allows their differentiation from aortic dissections, which have similar clinical manifestations, and permits an exact determination of their location-crucial information for surgical planning. On the basis of CT findings, some hematomas may be expected to resolve spontaneously, whereas others may be identified as posing a high risk for serious complications such as aortic dissection, aneurysm, and rupture. Appropriate clinical management is aided by accurate recognition of diagnostically specific CT features and awareness of their significance.

16-MDCT angiography in living kidney donors at various tube potentials: impact on image quality and radiation dose.

OBJECTIVE The objective of our study was to compare the performance of 16-MDCT angiography at various peak kilovoltage (kVp) settings and the impact of the different settings on image quality and on radiation dose in adult kidney donors. MATERIALS AND METHODS Sixty-two renal donors (32 men, 30 women) who underwent 16-MDCT were divided into three groups: 18 subjects were studied at 140 kVp (group A); 20, at 120 kVp (group B); and 24, at 100 kVp (group C). Other constant scanning parameters were as follows: detector collimation, 0.625 mm; table feed, 9.375 mm/rotation; gantry rotation time, 500 milliseconds; and automatic current tube modulation (ATCM) using a noise index of 15. A total of 135-140 mL of iodinated contrast material (300 mg I/mL) was administered at 5 mL/s via an 18-gauge cannula, and arterial phase scanning was initiated using a bolus-tracking technique. Two observers evaluated image quality of the axial and 3D images and the visibility of branch order in the superior mesenteric artery (SMA) and renal arteries. Attenuation (in Hounsfield units [H]) in the aorta, SMA, and main renal artery was also measured by placing a region of interest. Radiation dose measurements were based on the scanner-generated CT dose index volume (CTDI(vol)). Each parameter tested was compared among the three groups using a nonparametric analysis of variance test, and a p value of 0.05 was considered significant. RESULTS Differences in the quality of the axial images existed between groups A and C (p < 0.001) and between groups B and C (p < 0.01); the image quality of the 3D images and the visibility of branch order in the SMA and renal arteries were comparable for all groups. The difference in mean attenuation of the aorta, SMA, and renal arteries was significant between groups A and C (p < 0.001) and between groups B and C (p < 0.01). All groups had 100% diagnostic accuracy in identifying the number of renal arteries on the side of nephrectomy. The mean radiation dose in CTDI(vol) was 25 +/- 3 mGy at 140 kVp, 17 +/- 4 mGy at 120 kVp, and 12 +/- 3 mGy at 100 kVp (p < 0.001). CONCLUSION Our initial observations suggest that the image quality of 16-MDCT angiography performed at 120 kVp is similar to that of CT angiography (CTA) performed at 140 kVp in adult kidney donors but with a significant radiation dose reduction. CTA at 100 kVp results in higher image noise but provides diagnostically acceptable images with significant radiation dose reduction compared with CTA at 120 or 140 kVp.

Suprarenal inferior vena cava filters: a 20-year single-center experience.

PURPOSE To assess the clinical safety and efficacy of suprarenal inferior vena cava (IVC) filters during long-term follow-up. MATERIALS AND METHODS In this retrospective study, the authors collected the following data about patients who underwent suprarenal IVC filter placement at their institution between 1988 and 2007: demographics, clinical presentation, indications for filter placement, reasons for placing the filter in the suprarenal IVC, type of filter, frequency of pulmonary embolism (PE) after filter placement, and filter-related problems during follow-up. RESULTS Seventy patients (32 male and 38 female patients; mean age, 60 years) had suprarenal IVC filters. Sixty-two patients presented with symptoms of venous thromboembolism (VTE) and eight had incidental asymptomatic VTE at imaging. Indications for filter placement were as follows: contraindication to anticoagulation (n = 48), complications and/or failure of anticoagulation (n = 12), added protection (n = 8), and prophylaxis (n = 2). Suprarenal placement was chosen due to IVC thrombus (n = 41), intrinsic and/or extrinsic narrowing of the infrarenal IVC (n = 9), renal and/or gonadal vein thrombus (n = 3), congenital IVC anomalies (n = 6), pelvic mass (n = 5), pregnancy (n = 3), and other reasons (n = 3). The following filters were used: Greenfield (n = 29), Simon Nitinol (n = 5), Vena-Tech (n = 3), TrapEase (n = 22), OptEase (n = 3), Tulip (n = 6), Birds Nest (n = 1), and Recovery (n = 1). During follow-up (mean, 573 days +/- 953), postfilter PE was suspected in 10 patients; eight patients underwent computed tomography (CT), one of whom had PE at CT. None developed new symptoms of caval thrombosis. Abdominal CT (performed in 30 patients at a mean of 543 days +/- 768) showed thrombus in the filter in three patients, fracture in one patient, and penetration of the IVC wall in two patients. CONCLUSIONS Suprarenal filters are safe and effective in preventing PE. The placement of IVC filters above the renal veins does not carry an added risk of complications.

“Recovery™” Vena Cava Filter: Experience in 96 Patients

The purpose of the study was to assess the clinical safety and efficacy of the “RecoveryTM” (Bard) inferior vena cava (IVC) filter. We retrospectively evaluated the clinical and imaging data of patients who had a “RecoveryTM” IVC filter placed between January 2003 and December 2004 in our institution. The clinical presentation, indications, and procedure-related complications during placement and retrieval were evaluated. Follow-up computed tomography (CT) examinations of the abdomen and chest were evaluated for filter-related complications and pulmonary embolism (PE), respectively. “Recovery” filters were placed in 96 patients (72 males and 24 females; age range: 16–87 years; mean: 46 years). Twenty-four patients presented with PE, 13 with deep vein thrombosis (DVT) and 2 with both PE and DVT. The remaining 57 patients had no symptoms of thromboembolism. Indications for filter placement included contraindication to anticoagulation (n = 27), complication of anticoagulation (n = 3), failure of anticoagulation (n = 5), and prophylaxis (n = 61). The device was successfully deployed in the infrarenal (n = 95) or suprarenal (n = 1) IVC through a femoral vein approach. Retrieval was attempted in 11 patients after a mean period of 117 days (range: 24–426). The filter was successfully removed in nine patients (82%). Failure of retrieval was due to technical difficulty (n = 1) and the presence of thrombus in the filter (n = 1). One of the nine patients who had the filter removed developed IVC thrombus after retrieval and another had an intimal tear of the IVC. Follow-up abdominal CT (n = 40) at a mean of 80 days (range: 1–513) showed penetration of the IVC by the filter arms in 11, of which 3 had fracture of filter components. In one patient, a broken arm migrated into the pancreas. Asymmetric deployment of the filter legs was seen in 12 patients and thrombus within the filter in 2 patients. No filter migration or caval occlusion was encountered. Follow-up chest CT (n = 27) at a mean of 63 days (range: 1–386) showed PE in one patient (3%). During clinical follow-up, 12 of 96 patients developed symptoms of PE and only 1 of the 12 had PE on CT. There was no fatal pulmonary embolism in our group of patients following “Recovery” filter placement. However, the current version of the filter is associated with structure weakness, a high incidence of IVC wall penetration, and asymmetric deployment of the filter legs.