Cost identification of abdominal aortic aneurysm imaging by using time and motion analyses

Costing in Radiology and Health Care: Rationale, Relativity, Rudiments, and Realities

Costs direct decisions that influence the effectiveness of radiology in the care of patients on a daily basis. Yet many radiologists struggle to harness the power of cost measurement and cost management as a critical path toward establishing their value in patient care. When radiologists cannot articulate their value, they risk losing control over how imaging is delivered and supported. In the United States, recent payment trends directing value-based payments for bundles of care advance the imperative for radiology providers to articulate their value. This begins with the development of an understanding of the providers' own costs, as well as the complex interrelationships and imaging-associated costs of other participants across the imaging value chain. Controlling the costs of imaging necessitates understanding them at a procedural level and quantifying the costs of delivering specific imaging services. Effective product-level costing is dependent on a bottom-up approach, which is supported through recent innovations in time-dependent activity-based costing. Once the costs are understood, they can be managed. Within the high fixed cost and high overhead cost environment of health care provider organizations, stakeholders must understand the implications of misaligned top-down cost management approaches that can both paradoxically shift effort from low-cost workers to much costlier professionals and allocate overhead costs counterproductively. Radiology's engagement across a broad spectrum of care provides an excellent opportunity for radiology providers to take a leading role within the health care organizations to enhance value and margin through principled and effective cost management. Following a discussion of the rationale for measuring costs, this review contextualizes costs from the perspectives of a variety of stakeholders (relativity), discusses core concepts in how costs are classified (rudiments), presents common and improved methods for measuring costs in health care, and discusses how cost management strategies can either improve or hinder high-value health care (realities). ^© RSNA, 2017 Online supplemental material is available for this article.

Morphologic evaluation of ruptured and symptomatic abdominal aortic aneurysm by three-dimensional modeling

OBJECTIVE

To identify geometric indices of abdominal aortic aneurysms (AAAs) on computed tomography that are associated with higher risk of rupture.

METHODS

This retrospective case-control, institutional review board-approved study involved 63 cases with ruptured or symptomatic AAA and 94 controls with asymptomatic AAA. Three-dimensional models were generated from computed tomography segmentation and used for the calculation of 27 geometric indices. On the basis of the results of univariate analysis and multivariable sequential logistic regression analyses with a forward stepwise model selection based on likelihood ratios, a traditional model based on gender and maximal diameter (Dmax) was compared with a model that also incorporated geometric indices while adjusting for gender and Dmax. Receiver operating characteristic (ROC) curves were calculated for these two models to evaluate their classification accuracy.

RESULTS

Univariate analysis revealed that gender (P = .024), Dmax (P = .001), and 14 other geometric indices were associated with AAA rupture at P < .05. In the multivariable analysis, adjusting for gender and Dmax, the AAA with a higher bulge location (P = .020) and lower mean averaged area (P = .005) were associated with AAA rupture. With these two geometric indices, the area under the ROC curve showed an improvement from 0.67 (95% confidence interval, 0.58-0.77) to 0.75 (95% confidence interval, 0.67-0.83; P < .001). Our predictive model showed comparable sensitivity (64% vs 60%) and specificity (79% vs 77%) with current treatment criteria based on gender and diameter at the point optimizing the Youden index (sensitivity + specificity - 1) on the ROC curve.

CONCLUSIONS

Two geometric indices derived from AAA three-dimensional modeling were independently associated with AAA rupture. The addition of these indices in a predictive model based on current treatment criteria modestly improved the accuracy to detect aneurysm rupture.

Fast noise reduction in computed tomography for improved 3-D visualization

Computed tomography (CT) has a trend towards higher resolution and higher noise. This development has increased the interest in anisotropic smoothing techniques for CT, which aim to reduce noise while preserving structures of interest. However, existing smoothing techniques are slow, which makes clinical application difficult. Furthermore, the published methods have limitations with respect to preserving small details in CT data. This paper presents a widely applicable speed optimized framework for anisotropic smoothing techniques. A second contribution of this paper is an extension to an existing smoothing technique aimed at better preserving small structures of interest in CT data. Based on second-order image structure, the method first determines an importance map, which indicates potentially relevant structures that should be preserved. Subsequently an anisotropic diffusion process is started. The diffused data is used in most parts of the images, while structures with significant second-order information are preserved. The method is qualitatively evaluated against an anisotropic diffusion method without structure preservation in an observer study to assess the improvement of 3-D visualizations of CT series and quantitatively by determining the reduction of the difference between low and high dose CT scans of in vitro carotid plaques.

CT angiography effectively evaluates extremity vascular trauma

Traditionally, conventional arteriography is the diagnostic modality of choice to evaluate for arterial injury. Recent technological advances have resulted in multidetector, fine resolution computed tomographic angiography (CTA). This study examines CTA for evaluation of extremity vascular trauma compared with conventional arteriography. Our hypothesis is that CTA provides accurate and timely diagnosis of peripheral vascular injuries and challenges the gold standard of arteriogram. Traumatic extremity injuries over a 5-year period were identified using a Level I trauma center registry and radiology database. Information collected included patient demographics, mechanism, imaging modality, vascular injuries, management, and follow-up. Two thousand two hundred and fifty-one patients were identified with extremity trauma. Twenty-four patients were taken directly to the operating room for evaluation and management of vascular injuries. Fifty-two underwent vascular imaging. Fourteen patients had conventional arteriograms with 13 abnormal studies: 7 were managed operatively, 2 embolized, and 4 observed. Thirty-eight patients underwent CTA with 17 abnormal scans: 9 were managed operatively, 3 embolized, and 5 observed. There were no false negatives or missed injuries. CTA provides accurate peripheral vascular imaging while additionally offering advantages of noninvasiveness and immediate availability. Secondary to these advantages, CTA has supplanted arteriography for initial radiographic evaluation of peripheral vascular injuries at our Level I trauma center. This study supports CTA as an effective alternative to conventional arteriography in assessing extremity vascular trauma.

Multidetector-row Computed Tomographic Angiography of Thoracic and Abdominal Aortic Aneurysms

OBJECTIVE

To compare the quality of multidetector-row computed tomographic angiography in patients with and without aortic aneurysms by 3 different amounts of contrast media (CM).

METHODS

A total of 115 patients with aortic aneurysms were divided into 3 groups: group A, 100 mL CM; group B, 75 mL CM with 20 mL saline flush (SF); and group C, 50 mL CM with 20 mL SF. Twenty-five patients without aortic aneurysms were also enrolled (group D, 50 mL CM with 20 mL SF). Quantitative and qualitative analyses were performed by measuring attenuation in thoracoabdominal/aortoiliac lumen, aneurysmal lumen, and superior vena cava.

RESULTS

In group C, attenuation was lower in distal than those in proximal and middle areas (P < 0.05). Contrast enhancement in abdominal aneurysmal lumen was more inhomogeneous in group C (P = 0.003). Visual analysis showed contrast enhancement was more nonuniform in group C (P = 0.004), and perivenous artifacts were more conspicuous in group A (P < 0.0001).

CONCLUSIONS

Seventy-five milliliters CM followed by 20 mL SF can produce optimal contrast enhancement at systemic multidetector-row computed tomographic angiography in patients with aortic aneurysms.

Thoracoabdominal-Aortoiliac MDCT Angiography Using Reduced Dose of Contrast Material

OBJECTIVE

The objective of our study was to compare the image quality of MDCT angiography studies obtained by injection of low doses of contrast medium with saline flush versus conventional doses of contrast medium.

MATERIALS AND METHODS

Seventy-one patients with pre- or postoperative aortic aneurysms underwent MDCT angiography throughout the thoracoabdominal-aortoiliac system using an 8-MDCT scanner. In 37 patients, 100 mL of contrast medium was injected at a flow rate of 3.0 mL/s (hereafter referred to as the 100-mL group). In 34 patients, 50 mL of contrast medium followed by a 20-mL saline flush was injected at a flow rate of 2.5 mL/s (the 50-mL group). For each group, quantitative analysis involved calculating the mean aortoiliac enhancement, plateau deviation, and contrast enhancement in the pulmonary trunk and superior vena cava (SVC). Qualitative analysis involved assessing the 3D postprocessing images.

RESULTS

Significant differences between the groups in mean aortoiliac enhancement (100-mL group vs 50-mL group, 337 +/- 6 H vs 319 +/- 5 H, p < 0.0001) and mean plateau deviation (51 +/- 4 H vs 58 +/- 4 H, p < 0.0001) were found. However, adequate arterial enhancement (>or= 200 H) was observed in 31 of 34 patients in the 50-mL group and uniform aortoiliac enhancement (< 50 H) was seen in 26 patients. Visual analysis showed no difference in contrast material magnitude and homogeneity between the groups. Furthermore, in the 50-mL group, the thoracic aorta was more clearly visualized because of a reduction in the opacity of the main pulmonary artery and SVC.

CONCLUSION

In our experience, administration of 50 mL of contrast medium followed by a 20-mL saline flush produces thoracoabdominal-aortoiliac MDCT angiographic examinations of effective quality in most cases.

CT angiography of peripheral arterial disease

Lower-extremity computed tomographic (CT) angiography (ie, peripheral CT angiography) is increasingly used to evaluate patients with peripheral arterial disease. It is therefore increasingly important for all vascular specialists to become familiar with the strengths and limitations of this new technique. The aims of this review are to explain the principles of scanning and injection technique for a wide range of CT scanners, to explain and illustrate the properties of current image postprocessing tools for effective visualization and treatment planning, and to provide an overview of current clinical applications of peripheral CT angiography.

Preliminary examination to determine the suitable contrast material injection protocol for CT angiography of the pelvis and lower extremities with a multidetector row helical scanner

PURPOSE

The aim of this study was to determine the best of three protocols for the depiction of arteries in the pelvis and lower extremities by computed tomographic angiography (CTA) with a multidetector row helical scanner.

MATERIALS AND METHODS

CTA was performed in five asymptomatic volunteers using a four-channel multidetector row helical scanner. Low-osmolar iodinated contrast material was injected at the flow rate of 3 ml/s using three protocols: 100 ml of 300 mg I/ml, 150 ml of 300 mg I/ml, and 100 ml of 350 mg I/ml. The CT number of opacified blood was measured at six levels. Three doctors independently assessed the degree of depiction of arteries on CTA images without knowing the protocol using a 3-point scale.

RESULTS

CT numbers at the level of the popliteal artery on the protocol of 150 ml of 300 mg I/ml were significantly greater than the others. The mean score for the depiction of trifurcation on the protocol of 150 ml of 300 mg I/ml was significantly greater than those in the others.

CONCLUSION

The protocol of 150 ml of 300 mg I/ml was the best for depicting arteries in the pelvis and lower extremities by CTA.

Four- and eight-channel aortoiliac CT angiography: a comparative study

PURPOSE

To compare performance parameters, contrast material load and radiation dose in a patient cohort having aortoiliac CT angiography using 4- and 8-channel multidetector CT (MDCT) systems.

METHODS

Eighteen patients with abdominal aortic aneurysms underwent initial 4-channel and follow-up 8-channel MDCT angiography. Both the 4- and 8-channel MDCT systems utilized a matrix detector of 16 x 1.25 mm rows. Scan coverage included the abdominal aorta and iliac arteries to the level of the proximal femoral arteries. For 4-channel MDCT, nominal slice thickness and beam pitch were 1.25 mm and 1.5, respectively, and for 8-channel MDCT they were 1.25 mm and 1.35 or 1.65 respectively. Scan duration, iodinated contrast material load and mean aortoiliac attenuation were compared retrospectively. Comparative radiation dose measurements for 4- and 8-channel MDCT were obtained using a multiple scan average dose technique on an abdominal phantom.

RESULTS

Compared with 4-channel MDCT, 8-channel MDCT aortoiliac angiography was performed with equivalent collimation, decreased contrast load (mean 45% decrease: 144 ml versus 83 ml of 300 mg iodine/ml contrast material) and decreased acquisition time (mean 51% shorter: 34.4 sec versus 16.9 sec) without a significant change in mean aortic enhancement (299 HU versus 300 HU, p > 0.05). Radiation dose was 2 rad for the 4-channel system and 2/1.5 rad for the 8-channel system at 1.35/1.65 pitch respectively.

CONCLUSION

Compared with 4-channel MDCT, aortoiliac CT angiography with 8-channel MDCT produces equivalent z-axis resolution with decreased contrast load and acquisition time without increased radiation exposure.

Abdominal aortic aneurysms at multi-detector row helical CT: optimization with interactive determination of scanning delay and contrast medium dose

PURPOSE

To prospectively evaluate a technique for optimizing aortoiliac enhancement at multi-detector row helical computed tomography (CT) with both the scanning delay and contrast medium dose determined by using an interactive method.

MATERIALS AND METHODS

Forty-five patients with abdominal aortic aneurysm were randomized to undergo multi-detector row helical CT with either an interactive protocol (n = 23) or a standard protocol (n = 22). Scanning delays in all patients were determined with automated triggering. Patients in the standard protocol group received 150 mL of contrast medium intravenously at 4 mL/sec. The same injection rate was used for the interactive protocol group, but the dose was reduced with discontinuation of injection at start of scanning. Quantities of contrast medium used and contrast-enhanced aortic attenuation achieved were compared. Aortoiliac enhancement was evaluated qualitatively by using a five-point scale (1 = poor, 5 = excellent). Quantitative and qualitative data were analyzed with the two-tailed t test and Wilcoxon rank sum test, respectively, to determine significance of differences (P <.05).

RESULTS

Data from six patients were excluded because of technical errors. Data were analyzed from 20 patients in the interactive protocol group and 19 in the standard protocol group. Mean contrast medium volume was 107 mL +/- 20 (standard deviation) in the interactive protocol group and 148 mL +/- 3 in the standard protocol group (P <.001). Mean contrast-enhanced attenuation at initial, peak, and final measurements was 257 HU +/- 38, 285 HU +/- 46, and 269 HU +/- 54, respectively, for the interactive protocol group, and 261 HU +/- 65, 288 HU +/- 66, and 269 HU +/- 61 for the standard protocol group (P >.05). Mean qualitative enhancement scores for interactive and standard protocol groups were 4.47 and 4.44, respectively (P =.47).

CONCLUSION

The interactive method is a simple, efficient, and reproducible way to optimize aortoiliac enhancement while reducing contrast medium dose.

Aortoiliac enhancement during computed tomography angiography with reduced contrast material dose and saline solution flush: influence on magnitude and uniformity of the contrast column

RATIONALE AND OBJECTIVES

To compare the magnitude and uniformity of aortoiliac contrast enhancement obtained from uniphasic contrast material injections versus contrast material injections with reduced iodine dose followed by a saline flush in aortoiliac multislice CT angiography (CTA).

METHODS

Twenty-nine patients with abdominal aortic aneurysms underwent aortoiliac CTA using protocols A and B. With protocol A, 120 mL contrast material (300 mgI/mL), and with protocol B, 100 mL contrast material followed by a 40-mL saline solution flush were administered at a flow rate of 4 mL/s. Quantitative analysis was performed by calculating mean aortoiliac attenuation, mean plateau deviation, and mean difference between maximum and minimum attenuation value for both groups. Qualitative analysis was performed by visual assessment of vascular enhancement using 2-dimensional and 3-dimensional postprocessing techniques.

RESULTS

The mean aortoiliac attenuation with protocol A was 291 +/- 62 HU, and with protocol B it was 285 +/- 61 HU. The difference of 6 HU was not statistically significant (P = 0.27). Mean plateau deviation was significantly smaller using protocol A than protocol B (16 +/- 9 HU vs. 20 +/- 10 HU, P = 0.03). In addition, the mean difference between maximum and minimum attenuation value was significantly smaller with protocol A than with protocol B (59 +/- 29 HU vs. 72 +/- 32 HU, P = 0.01). Visual analysis showed no difference in contrast material magnitude and homogeneity between the protocols.

CONCLUSIONS

In aortoiliac CTA, a saline solution flush after contrast material bolus allows an iodine dose reduction of approximately 20 mL without impairing the magnitude of contrast enhancement but degrades the uniformity of the contrast column. However, the degradation does not affect visual analysis.

Functional MR Imaging versus Wada Test for Evaluation of Language Lateralization: Cost Analysis

PURPOSE

To compare the total direct costs (fixed and variable costs) of functional magnetic resonance (MR) imaging and of the Wada test for evaluation of language lateralization.

MATERIALS AND METHODS

The direct fixed and variable costs of functional MR imaging (performed in 21 patients with mean age +/- SD of 15.5 years +/- 8.9) and of the Wada test (performed in 18 patients aged 19.2 years +/- 5.4) were determined prospectively with time and motion analyses. The labor of all personnel involved in evaluations of language lateralization was tracked, and involvement times were recorded to the nearest minute. All material items used in the studies were recorded. Costs of labor and of materials were determined from personnel reimbursement data and from vendor pricing, respectively. Direct fixed costs were determined from hospital accounting department records. Means (+/- SDs) were calculated for all direct fixed and variable costs. Total direct costs were determined for each procedure and compared by using the Student t test.

RESULTS

The total direct costs of the Wada test (US dollars 1130.01 +/- US dollars 138.40) and of functional MR imaging (US dollars 301.82 +/- US dollars 10.65) were significantly different (P <.001). The cost of the Wada test was 3.7 times higher than that of functional MR imaging.

CONCLUSION

Substantial savings are achievable with the use of functional MR imaging instead of the Wada test to evaluate language lateralization.

Conventional radiography, rapid MR imaging, and conventional MR imaging for low back pain: activity-based costs and reimbursement

PURPOSE

To incorporate personnel and equipment use time in an activity-based cost comparison of conventional radiography and conventional and rapid magnetic resonance (MR) imaging for low back pain (LBP).

MATERIALS AND METHODS

At each of four Seattle Lumbar Imaging Project (SLIP) sites, patients were randomized to undergo conventional radiography or rapid MR imaging of the lumbar spine. For sample SLIP patients and for similar non-SLIP patients undergoing conventional lumbar spine MR imaging as usual care in calendar year 2000, measured imaging room use and technologist and radiologist times were multiplied by costs per minute of standard equipment acquisition, personnel compensation, and related expenses. Resulting provider-perspective costs and Seattle area Medicare reimbursements for conventional MR imaging and radiography for calendar year 2001 were used to estimate future "normative" reimbursement for rapid MR imaging.

RESULTS

For 23 conventional radiography, 27 rapid MR imaging, and 38 conventional MR imaging examinations timed in calendar year 2000, all rapid MR imaging times exceeded those of conventional radiography but were less than those of conventional MR imaging. All 0.3- and 0.35-T MR imaging room and technologist times exceeded those for 1.5-T MR imaging. Average costs (in 2001 dollars) were $44 for conventional radiography, 126 US dollars for 1.5-T rapid MR imaging, 128 US dollars for 0.3-0.35-T rapid MR imaging, 267 US dollars for 1.5-T conventional MR imaging, and 264 US dollars for 0.3-0.35-T conventional MR imaging. Conclusions regarding cost differences between conventional radiography and rapid MR imaging were robust to plausible parameter value changes evaluated in sensitivity analyses. Conventional radiography reimbursement was 44 US dollars. Applying the ratio of reimbursement (620 US dollars) to costs (264-267 US dollars) for conventional MR imaging to rapid MR imaging costs predicted reimbursement of 292-300 US dollars for the new modality.

CONCLUSION

Times and costs for rapid MR imaging are roughly three times those for conventional radiography but about half those for conventional MR imaging for LBP. While current conventional radiography costs exceed reimbursement, current conventional MR and projected rapid MR imaging reimbursements exceed costs.

Aortoiliac and renal arteries: prospective intraindividual comparison of contrast-enhanced three-dimensional MR angiography and multi-detector row CT angiography

PURPOSE

To compare contrast material-enhanced three-dimensional (3D) magnetic resonance (MR) angiography and multi-detector row computed tomographic (CT) angiography in the same patients for assessment of the aortoiliac and renal arteries, with digital subtraction angiography (DSA) as the standard of reference.

MATERIALS AND METHODS

DSA, 3D MR angiography, and multi-detector row CT angiography were performed in 46 consecutive patients. A total of 769 arterial segments were analyzed for arterial stenosis by using a four-point grading system. Aneurysmal changes were noted. The time required for performing 3D reconstructions and image analysis of both MR and CT data sets was measured. Patient acceptance for each modality was assessed with a visual analogue scale. Statistical analysis of data was performed.

RESULTS

Sensitivity of MR angiography for detection of hemodynamically significant arterial stenosis was 92% for reader 1 and 93% for reader 2, and specificity was 100% and 99%, respectively. Sensitivity of CT angiography was 91% for reader 1 and 92% for reader 2, and specificity was 99% and 99%, respectively. Differences between the two modalities were not significant. Interobserver and intermodality agreement was excellent (kappa = 0.88-0.90). The time for performance of 3D reconstruction and image analysis of CT data sets was significantly longer than that for MR data sets (P <.001). Patient acceptance was best for CT angiography (P =.016).

CONCLUSION

There is no statistically significant difference between 3D MR angiography and multi-detector row CT angiography in the detection of hemodynamically significant arterial stenosis of the aortoiliac and renal arteries.

Vesicoureteral reflux imaging in children: comparative cost analysis

RATIONALE AND OBJECTIVES

The purpose of this study was to compare the costs of voiding cystourethrography (VCUG) versus radionuclide cystography (RNC) for evaluation of vesicoureteral reflux in children.

MATERIALS AND METHODS

The variable direct costs of performing 25 VCUG and 25 RNC examinations in age- and general health-matched patients suspected of having vesicoureteral reflux was determined by using time and motion analyses. All personnel directly involved in the cases were tracked, and the involvement times were recorded to the nearest minute. All material items used during the procedures were recorded. The cost of labor was determined from personnel reimbursement data, and the cost of materials, from vendor pricing. The fixed direct costs were assessed from hospital accounting records. Mean, standard deviation, and 95% confidence interval (CI) were determined for all direct (fixed and variable) costs. The total costs were determined for each procedure and compared by using the Student t test.

RESULTS

There was a significant difference (P < .0001) between the mean total direct cost of VCUG ($112.17 +/- 10.33) and that of RNC ($64.58 +/- 1.91). VCUG examination for vesicoureteral reflux in children cost 1.74 times more than RNC examination (95% CI: 1.28, 2.36).

CONCLUSION

When the technique is clinically appropriate, institutions may obtain substantial cost savings by using RNC in place of VCUG for examining children suspected of having vesicoureteral reflux.

The principles of cost-effectiveness analysis and their application

The current healthcare environment requires the evaluation of both the costs and benefits of alternative interventions for a given clinical problem. Given the increased interest in the economic evaluation of healthcare interventions, this article briefly defines various forms of economic evaluations and describes some useful steps for conducting appraisals of cost-effectiveness analyses. Studies of competing methods of treatment of abdominal aortic aneurysms greater than 5 cm are used as a clinical example of interest to the readers of this Journal. Rather than actually conducting such an analysis with existing data, we describe the principles for conducting or reviewing an economic analysis with factitious data.

Transportable versus fixed platform CT scanners: comparison of costs

PURPOSE

To compare the aggregate hospital technical costs of a transportable computed tomographic (CT) scanner used to image patients in an intensive care unit with those of a fixed platform CT scanner in the radiology department.

MATERIALS AND METHODS

Direct fixed costs (ie, machine and service contract costs) and direct variable costs (ie, personnel costs) were calculated. Indirect costs, including space costs and departmental overhead, were calculated. Total costs were calculated as the sum of indirect, direct fixed, and direct variable costs. Personnel costs were calculated from time-motion analyses involving 95 patients who underwent brain CT with either a transportable (n = 51) or a fixed platform (n = 44) CT scanner. Costs per examination were calculated by using both low- and high-examination-volume models and compared with use of the Wilcoxon rank sum test.

RESULTS

The total cost per examination for the transportable scanner ranged from 108.98 dollars to 167.20 dollars for the high- and low-volume models. Total cost per examination for the fixed platform scanner ranged from 75.24 dollars to 112.39 dollars for the high- and low-volume models. For the transportable scanner, direct fixed, variable, and overhead costs were 87.05 dollars, 70.73 dollars, and 9.42 dollars per examination, respectively, with the low-volume model. The corresponding costs for the fixed platform scanner were 46.66 dollars, 55.69 dollars, and 10.04 dollars, respectively.

CONCLUSION

The technical cost of using an in-hospital transportable CT scanner is higher than that of using a fixed platform scanner.

Abdominal aortic aneurysms: cost-effectiveness of elective endovascular and open surgical repair

PURPOSE

To evaluate the cost-effectiveness of elective endovascular and open surgical repair of infrarenal abdominal aortic aneurysms (AAAs) by taking into account short- and long-term outcomes.

MATERIALS AND METHODS

A Markov decision model was developed to evaluate quality-adjusted life-years (QALYs) and lifetime costs of endovascular and open surgical repair. The incremental cost-effectiveness ratio (CER) was calculated for endovascular repair relative to open surgery in a cohort of 70-year-old men with an AAA between 5 and 6 cm in diameter. Clinically effectiveness data were derived from the literature. Cost data were derived from Medicare reimbursement rates, the hospital database, and the literature. One- and multiple-way sensitivity analyses were performed on uncertain model parameters. Costs were converted to year 2000 U.S. dollars; future costs and outcomes were discounted at 3%.

RESULTS

The incremental CER of endovascular repair was 9,905 dollars per QALY. QALYs and lifetime costs were higher for endovascular repair than for open surgery (6.74 vs 6.52 and 39,785 dollars vs 37,606 dollars, respectively). In sensitivity analyses, the incremental CER was insensitive to immediate conversion rate and procedure mortality rate. The incremental CER was sensitive (ie, more than 75,000 dollars per QALY or endovascular repair was ruled out by dominance) to systemic-remote complications, long-term failures, and ruptures.

CONCLUSION

The results suggest that endovascular repair is a cost-effective alternative compared with open surgery for the elective repair of AAA. The benefits and cost-effectiveness are highly dependent on uncertain outcomes, however, particularly long-term failure and rupture rates.

CT angiography of the arterial system

CTA has become an important diagnostic tool in the evaluation of vascular diseases in virtually all parts of the body. Whereas CTA is able to provide images depicting exquisite anatomic detail, careful scanning technique and selection of scan parameters are critical for high quality studies. The choices to be made when prescribing a scan can seem daunting at first, but if one applies the principles outlined previously, CTA can be a relatively easy, fast, and safe diagnostic technique that is effective in the majority of patients with vascular disease.

CT angiography of the subclavian artery: utility of curved planar reformations

Despite advances in the diagnosis and treatment of peripheral vascular occlusive disease, an ever-aging population continues to provide scores of new cases requiring medical care. While traditional angiography has been the mainstay of diagnosis for many years, newer, less invasive techniques such as CT angiography with three-dimensional reformation are rapidly establishing themselves as first-line diagnostic modalities. We present a case of severe left subclavian artery stenosis that demonstrates the utility of curved planar reformation in providing a concise visual summary of the pertinent anatomy and abnormalities.

Thoracic aorta: motion artifact reduction with retrospective and prospective electrocardiography-assisted multi-detector row CT

The authors compared prospective (n = 20) and retrospective (n = 20) electrocardiography (ECG)-assisted multi-detector row computed tomography (CT) with non-ECG-assisted multi-detector row CT (n = 20) of the thoracic aorta with regard to reduction of motion-related artifacts. Image quality was rated for transverse source and sagittal oblique images of the thoracic aorta, including the aortic valve. ECG-assisted multi-detector row CT compared with non-ECG-assisted multi-detector row CT showed a significant reduction in motion artifacts for the entire thoracic aorta.

Multi-detector row CT angiography of lower extremity arterial inflow and runoff: initial experience

PURPOSE

To assess the patterns of lower extremity arterial inflow and runoff opacification with four-channel multi-detector row computed tomographic (CT) angiography in a cohort of patients with disease warranting imaging of the lower extremity arterial system.

MATERIALS AND METHODS

Twenty-four patients with symptomatic lower extremity arterial occlusive or aneurysmal disease underwent imaging with four-channel multi-detector row CT from the supraceliac abdominal aorta through the feet. Transverse sections were acquired with a 2.5-mm nominal detector width and pitch of 6.0 (3.2-mm effective section thickness) following intravenous injection of 174-185 mL of iodinated contrast medium (300 mg iodine per milliliter). In each patient, attenuation measurements were recorded in 16 arterial and 16 venous locations. In 18 patients, two radiologists assessed the detectability and stenosis degree of 21 arterial segments per patient relative to these features at conventional angiography.

RESULTS

A mean scanning time of 66 seconds was required to cover a mean of 1,233 mm, resulting in a mean of 908 transverse reconstructions. All 504 arterial segments were depicted and analyzable. Mean arterial attenuation ranged from 253 HU in the midabdominal aorta to 357 HU in the popliteal artery and 253 HU in the dorsalis pedis or posterior tibial artery measured inferior to the tibiotalar joint. Maximum mean venous enhancement (99 HU) was observed in the saphenous vein at the ankle, with all other venous stations measuring less than 74 HU.

CONCLUSION

The arteries of lower extremity inflow and runoff can be reliably depicted with minimal venous enhancement by using multi-detector row CT.

Multi-detector row CT of thoracic disease with emphasis on 3D volume rendering and CT angiography

Multi-detector row computed tomography (CT) with three-dimensional (3D) volume rendering provides a unique perspective on thoracic anatomy and disease. Multi-detector row CT allows shorter acquisition times, greater coverage, and superior image resolution. Three-dimensional volume rendering now permits real-time, interactive modification of relative pixel attenuation in an infinite number of planes and projections. In vascular imaging, this technique provides image quality that equals or surpasses that of conventional angiography. Its use has expanded to aid in diagnosis and surgical planning, often obviating conventional or digital angiography and reducing costs. It is reliable in depicting clot and the pulmonary vasculature and may also be used to evaluate thoracic venous anomalies (eg, pulmonary arteriovenous malformations) and to plan therapy. Airway imaging with multi-detector row CT with 3D volume rendering is particularly useful in the planning and follow-up of stent placement. In diffuse lung disease, this technique can increase nodule detection and help differentiate between small nodules and vessels. It is also helpful in imaging the musculoskeletal system and the thoracic cage. Multi-detector row CT with 3D volume rendering has enhanced the conventional roles of thoracic CT and challenged the supremacy of other imaging modalities. It will likely play a leading role in future radiologic research and practice.

Techniques for performing multidetector-row computed tomographic angiography

The introduction of multidetector-row computed tomography (CT) scanners has substantially improved the quality and ease of performing CT angiography. CT angiography is a robust method of volumetric vascular imaging that offers benefits over conventional angiography. As CT angiography has become a mainstream examination in many radiology departments, a discussion of techniques toward optimizing CT angiography performed with multidetector-row CT scanners is important. Key principles for optimizing spiral CT acquisition are discussed, and an explanation of multidetector-row CT principles germane to peripheral vascular imaging is presented. A discussion of contrast medium administration strategies ensues, with attention toward injection protocol and bolus timing. An overview of 3-dimensional visualization techniques is subsequently presented, followed by some general rules for CT angiographic interpretation. The article concludes with anatomically directed protocol considerations for the carotid and intracranial circulation, thoracic aorta, pulmonary arteries, abdominal aortoiliac system, renal arteries, and lower extremity arterial inflow and run-off.

Aorta and iliac arteries: single versus multiple detector-row helical CT angiography

PURPOSE

To compare single- versus four-channel helical computed tomographic (CT) aortography.

MATERIALS AND METHODS

Forty-eight patients with aortic aneurysm or dissection underwent four- and one-channel CT angiography. Scan pairs covered the thoracic inlet to the diaphragm (n = 10) and supraceliac abdominal aorta (n = 19) or thoracic inlet (n = 19) to the femoral arterial bifurcations. For four-channel CT, nominal section thickness and pitch were 2.5 mm and 6.0, respectively, and for one-channel CT, 3.0 mm and 2.0 to the infrarenal aorta and 5.0 mm and 2.0 to the femoral arteries. Effective section thickness, scanning duration, scanning coverage, dose of iodinated contrast material, and mean aortoiliac attenuation were compared. Data were summarized as speed (coverage/duration), scanning efficiency (speed/section thickness), and contrast efficiency (mean aortic attenuation/dose of contrast material).

RESULTS

At four- versus one-channel CT, CT angiography was 2.6 times faster, scanning efficiency was 4.1 times greater, contrast efficiency was 2.5 times greater, dose of contrast material was reduced (mean, 57%; 97 vs 232 mL) without a significant change in aortic enhancement, and sections were thinner (mean, 40%; 3.2 vs 5.3 mm) despite a 59% shorter scanning duration (22 vs 56 seconds).

CONCLUSION

Substantially reduced doses of contrast medium, shorter scanning durations, and narrower effective sections result with four- versus one-channel CT aortography. No advantages of one-channel CT aortography were demonstrated.