Cost-effectiveness of MR angiography in cases of limb-threatening peripheral vascular disease

Systematic Review of Economic Models Used to Compare Techniques for Detecting Peripheral Arterial Disease

BACKGROUND AND OBJECTIVE

Peripheral arterial disease (PAD) is a common condition, in which atherosclerotic narrowing in the arteries restricts blood supply to the leg muscles. In order to support future model-based economic evaluations comparing methods of diagnosis in this area, a systematic review of economic modelling studies was conducted.

METHODS

A systematic literature review was performed in June 2017 to identify model-based economic evaluations of diagnostic tests to detect PAD, with six individual databases searched. The review was conducted in accordance with the methods outlined in the Centre for Reviews and Dissemination's guidance for undertaking reviews in healthcare, and appropriate inclusion criteria were applied. Relevant data were extracted, and studies were quality assessed.

RESULTS

Seven studies were included in the final review, all of which were published between 1995 and 2014. There was wide variation in the types of diagnostic test compared. The majority of the studies (six of seven) referenced the sources used to develop their model, and all studies stated and justified the structural assumptions. Reporting of the data within the included studies could have been improved. Only one identified study focused on the cost-effectiveness of a test typically used in primary care.

CONCLUSIONS

This review brings together all applied modelling methods for tests used in the diagnosis of PAD, which could be used to support future model-based economic evaluations in this field. The limited modelling work available on tests typically used for the detection of PAD in primary care, in particular, highlights the importance of future work in this area.

The Majority of Patients Have Diagnostic Evaluation Prior to Major Lower Extremity Amputation

BACKGROUND

Critical limb ischemia (CLI) patients who do not undergo revascularization are at great risk for major lower extremity (LE) amputation. It has been reported that less than half (49%) of a reference Medicare amputation population had any diagnostic vascular evaluation prior to a major LE amputation. We were surprised by these data so we reviewed the preoperative evaluation in all patients who had a major LE amputation. We propose that significantly more patients will have a vascular evaluation prior to major LE amputation at a tertiary care referral center when a vascular surgeon does the amputation.

METHODS

A retrospective analysis of major LE amputations was performed. Patient demographics, comorbidities, type of amputation, reason for amputation, Rutherford classification, and type of preoperative vascular examination were evaluated.

RESULTS

Over 4 years, 281 patients required major LE amputation. Above-knee amputation was performed in 39.1% of patients, whereas below-knee amputation was performed in 60.9%. Amputation was performed due to CLI in 92.9% of patients, whereas 7.1% of amputations were performed due to diabetes or other reasons. Preoperative vascular evaluation was performed in 100% of patients undergoing major LE amputation. Vascular surgeon pulse examination was most common (99.3%) followed by pulse volume recordings/ankle-brachial index (78.8%), angiography (54.8%), computed tomography angiography (29.3%), duplex ultrasonography (41.3%), and magnetic resonance angiography (0.4%). Amputations most commonly occurred due to Rutherford classification VI (63.3%) with 97.2% of patients having Rutherford IV-VI classification.

CONCLUSIONS

Preoperative vascular evaluation prior to major LE amputation is achievable in the majority of patients, reported here in 100% of patients undergoing a major LE amputation. This allows us to evaluate the patient for revascularization options prior to amputation for possible limb salvage.

A systematic review of model-based economic evaluations of diagnostic and therapeutic strategies for lower extremity artery disease

Lower extremity artery disease (LEAD) is a sign of wide spread atherosclerosis also affecting coronary, cerebral and renal arteries and is associated with increased risk of cardiovascular events. Many economic evaluations have been published for LEAD due to its clinical, social and economic importance. The aim of this systematic review was to assess modelling methods used in published economic evaluations in the field of LEAD. Our review appraised and compared the general characteristics, model structure and methodological quality of published models. Electronic databases MEDLINE and EMBASE were searched until February 2013 via OVID interface. Cochrane database of systematic reviews, Health Technology Assessment database hosted by National Institute for Health research and National Health Services Economic Evaluation Database (NHSEED) were also searched. The methodological quality of the included studies was assessed by using the Philips' checklist. Sixteen model-based economic evaluations were identified and included. Eleven models compared therapeutic health technologies; three models compared diagnostic tests and two models compared a combination of diagnostic and therapeutic options for LEAD. Results of this systematic review revealed an acceptable to low methodological quality of the included studies. Methodological diversity and insufficient information posed a challenge for valid comparison of the included studies. In conclusion, there is a need for transparent, methodologically comparable and scientifically credible model-based economic evaluations in the field of LEAD. Future modelling studies should include clinically and economically important cardiovascular outcomes to reflect the wider impact of LEAD on individual patients and on the society.

Ten-year technical and clinical outcomes in TransAtlantic Inter-Society Consensus II infrainguinal C/D lesions using duplex ultrasound arterial mapping as the sole imaging modality for critical lower limb ischemia

OBJECTIVE

The aim of this study was to evaluate duplex ultrasound arterial mapping (DUAM) as the sole imaging modality when planning for bypass surgery (BS) and endovascular revascularization (EvR) in patients with critical limb ischemia for TransAtlantic Inter-Society Consensus (TASC) II C/D infrainguinal lesions.

METHODS

This was a retrospective review evaluating the accuracy of DUAM as the sole imaging tool in determining patient suitability for BS vs EvR. Primary outcomes were the sensitivity and specificity of DUAM compared with intraoperative digital subtraction angiography. Secondary outcomes were procedural, hemodynamic, and clinical outcomes, amputation-free survival, and freedom from major adverse clinical events.

RESULTS

From 2002 to 2012, a total of 4783 patients with peripheral arterial disease were referred, of whom 622 critical limb ischemia patients underwent revascularization for TASC C and D lesions (EvR: n = 423; BS: n = 199). Seventy-four percent of EvR and 82% of BS were performed for TASC D (P = .218). The DUAM showed sensitivity of 97% and specificity of 98% in identifying lesions requiring intervention. Of the 520 procedures performed with DUAM alone, there was no difference regarding the number of procedures performed for occlusive or de novo lesions (EvR: 65% and 71%; BS: 87% and 78%; P = .056). Immediate clinical improvement to the Rutherford category ≤3 was 96% for EvR and 97% for BS (P = .78). Hemodynamic success was 79% for EvR and 77% for BS (P = .72). Six-year freedom from binary restenosis was 71.6% for EvR and 67.4% for BS (P = .724). Six-year freedom from target lesion revascularization was 81.1% for EvR and 70.3% for BS (P = .3571). Six-year sustained clinical improvement was 79.5% for EvR and 66.7% for BS (P = .294). Six-year amputation-free survival was 77.2% for EvR and 74.6% for BS (P = .837). There was a significant difference in risk of major adverse clinical events between EvR and BS (51% vs 70%; P = .034). Only 16.4% of patients required magnetic resonance angiography, which tended to overestimate lesions with 84% agreement with intraoperative findings. Six-year binary restenosis was 71% for DUAM procedures compared with 55% for magnetic resonance angiography procedures (P = .001), which was solely based on the prospective modality.

CONCLUSIONS

The DUAM epitomizes a minimally invasive, economically proficient modality for road mapping procedural outcome in BS and EvR. It allows for high patient turnover with procedural and clinical success without compromising hemodynamic outcome. The DUAM is superior to other available modalities as the sole preoperative imaging tool in a successful limb salvage program.

Evaluation of meglumine gadoterate-enhanced MR angiography (MRA) compared with time-of-flight MRA in the diagnosis of clinically significant non-coronary arterial disease: a pooled analysis of data from two clinical trials

OBJECTIVES

We analysed pooled data from two clinical trials to assess the diagnostic accuracy and safety of meglumine gadoterate (Gd-DOTA)-enhanced MR angiography (MRA) relative to those of non-enhanced time-of-flight (TOF) MRA for non-coronary arterial disease. Both techniques were compared with X-ray angiography as the gold standard.

METHODS

Patients were of both sexes, were aged at least 18 years and had suspected non-coronary arterial disease. Each patient was his/her own control and underwent TOF MRA followed by Gd-DOTA-enhanced MRA, and then X-ray angiography. MRA was performed at 1.5 T (USA study) or 3 T (Republic of Korea study). The primary criterion used to evaluate efficacy was the degree to which the MRA examination agreed with X-ray angiography in assessing non-coronary arterial lesions. The performance of Gd-DOTA over TOF was assessed using a one-sided paired t-test. We also evaluated the specificity, sensitivity, image quality, examination duration and clinical safety of both MRA procedures.

RESULTS

In total, 192 patients were enrolled and received Gd-DOTA. In the intent-to-treat population (n=162), within-patient accuracy was significantly greater for Gd-DOTA than for TOF (85.8 ± 19.8% agreement between Gd-DOTA and X-ray angiography compared with 78.3 ± 24.9% agreement between TOF and X-ray angiography; p=0.0001). The sensitivity, specificity, image quality and examination duration were also better for Gd-DOTA than for TOF. There were no serious drug-related adverse events.

CONCLUSION

We conclude that Gd-DOTA-enhanced MRA is a safe and accurate procedure for detecting arterial stenosis at both 1.5 T and 3 T.

Quality-of-life assessment of fibroid treatment options and outcomes

PURPOSE

To obtain utilities (a unit of measure of a person's relative preferences for different health states compared with death or worst possible outcome) for uterine fibroids before and after treatment and to measure short-term utilities for the following uterine fibroid treatments: abdominal hysterectomy, magnetic resonance (MR) imaging-guided focused ultrasound surgery, and uterine artery embolization (UAE).

MATERIALS AND METHODS

This retrospective study was approved by the institutional review board and was HIPAA compliant. The waiting trade-off (WTO) method, a variation on the time trade-off (TTO) method, is used to obtain utilities for diagnostic procedures on the basis of the fact that people wait longer to avoid noxious tests and/or procedures. The WTO method provides short-term quality of life tolls in terms of quality-adjusted life-weeks by scaling wait times with pre- and posttreatment utilities. Utilities for uterine fibroids before and after treatment were obtained with the TTO method and a visual analog scale (VAS) by using a questionnaire administered by means of a phone interview. WTO wait times were adjusted for quality of life with VAS and TTO utilities and a transformation of VAS. Wait times were compared by using nonparametric tests. The study participants included 62 patients who had undergone abdominal hysterectomy, 74 who had undergone UAE, and 61 who had undergone MR imaging-guided focused ultrasound surgery.

RESULTS

Quality of life increased with all treatments. The median WTO wait time was higher for hysterectomy (21.6 weeks) than for UAE or MR imaging-guided focused ultrasound surgery (14.1 weeks for both) (P < .05). Quality-adjusted life-week tolls were smaller when scaled according to TTO than when scaled according to VAS or transformation of VAS.

CONCLUSION

Quality of life increased after all fibroid treatments. WTO is feasible for assessing the quality-adjusted morbidity of treatment procedures.

SUPPLEMENTAL MATERIAL

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11100704/-/DC1.

Evaluation of contrast-enhanced magnetic resonance angiography (MRA) using Gd-DOTA compared with time-of-flight MRA in the diagnosis of clinically significant non-coronary arterial disease

OBJECTIVES

This trial assessed diagnostic accuracy of contrast-enhanced magnetic resonance angiography (MRA) with meglumine gadoterate (Gd-DOTA) at 3 Tesla (T) over unenhanced MRA at 3 T in non-coronary arterial diseases by comparing their accuracy with that of the gold standard, x-ray angiography.

METHODS

Ninety-two patients with suspected non-coronary arterial disease underwent in fixed sequence unenhanced time-of flight (TOF) MRA, contrast-enhanced MRA using a Gd-DOTA bolus (intravenous bolus 0.1 mmol/kg) and x-ray angiography.

RESULTS

Eighty-four patients (71 male, 13 female; median age 64.5 years) were included in an intent-to-treat efficacy analysis. Targeted vascular areas were aorto-iliac, calf, carotid, femoral, popliteal and renal. Within-patient accuracy was significantly higher with contrast-enhanced MRA using Gd-DOTA than with unenhanced MRA (p = 0.0003). There was 84.4 +/- 17.5% agreement between contrast-enhanced MRA (Gd-DOTA) and x-ray angiography, compared with 76.8 +/- 20.4% between non-enhanced MRA and x-ray angiography. Sensitivity and specificity were also better with Gd-DOTA compared with non-enhanced MRA at the segment level. Duration of the MRA procedure was 3.5 times shorter with Gd-DOTA compared with non-enhanced MRA. Six patients reported six mild or moderate adverse events. No serious adverse events occurred.

CONCLUSIONS

Contrast-enhanced MRA using Gd-DOTA at 3 T was superior to unenhanced TOF MRA in the vascular territories investigated.

Measuring the quality-of-life effects of diagnostic and screening tests

Health-related quality of life (HRQL) is a central concept for understanding the outcomes of medical care. When used in cost-effectiveness analysis, HRQL is typically measured for conditions persisting over long time frames (years), and quality-adjusted life year (QALY) values are generated. Consequently, years are the basic unit of time for cost-effectiveness analysis results: dollars spent per QALY gained. However, shorter term components of health care may also affect HRQL, and there is increased interest in measuring and accounting for these events. In radiology, the short-term HRQL effects of screening and diagnostic testing may affect a test's cost-effectiveness, even though they may only last for days. The unique challenge in radiology HRQL assessment is to realistically tap into the testing and screening experience while remaining consistent with QALY theory. The authors review HRQL assessment and highlight methods developed to specifically address the short-term effects of radiologic screening and testing.

Methods for measuring temporary health States for cost-utility analyses

A variety of methods are available to measure preferences for temporary health states for cost-utility analyses. The objectives of this review were to summarize the available temporary health-state valuation methods, identify advantages and disadvantages of each, and identify areas for future research. We describe the key aspects of each method and summarize advantages and disadvantages of each method in terms of consistency with QALY theory, relevance to temporary health-state-specific domains, ease of use, time preference, and performance in validation studies. Two broad categories of methods were identified: traditional and adapted. Traditional methods were health status instruments, time trade-off (TTO), and the standard gamble (SG). Methods adapted specifically for temporary health-state valuation were TTO with specified duration of the health state, TTO with a lifespan modification, waiting trade-off, chained approaches for TTO and SG, and sleep trade-off. Advantages and disadvantages vary by method and no 'gold standard' method emerged. Selection of a method to value temporary health states will depend on the relative importance of the following considerations: ability to accurately capture the unique characteristics of the temporary health state, level of respondent burden and cognition, theoretical consistency of elicited preference values with the overall purpose of the study, and resources available for study development and data collection. Further research should focus on evaluating validity, reliability and feasibility of temporary health-state valuation methods.

Process utility in breast biopsy

PURPOSE

To determine whether the waiting trade-off (WTO) is feasible for differentiating short-term biopsy preferences in an acute situation where anxiety is the symptomatic disease state.

METHODS

75 women with past experience of either breast core-needle biopsy (CNB), more invasive excisional surgical biopsy (EXB), or both, had telephone WTO assessments. Patients' baseline and test-related anxiety were valued by time trade-off (TTO) used to scale the WTO. Rating scales (RS) were obtained for convergent validity assessment with WTO and TTO.

RESULTS

Data were obtained in 38 women who had both CNB and EXB ("paired") and 20 who had CNB only and 16 who had EXB only ("unpaired"). Patients rated only the procedure(s) they experienced. Median paired and mean unpaired WTO scores indicated patients were willing to wait significantly longer to avoid EXB (P = 0.0003, P = 0.0002, respectively). The waiting time difference between EXB and CNB was 2.1 weeks greater in unpaired data than paired data. RS scores comparing the procedures were significantly different only for paired data (P < 0.05). Median TTO preferences for baseline (1.00) and test anxiety (0.93) obtained in 74 patients were significantly different (P < 0.0001) and consistent with RS. Correlation was noted between WTO and RS (-0.307 to -0.453, P = 0.0205 to 0.0001). The median EXB quality-adjusted life years toll (1.5 quality-adjusted life days) calculated from pooled WTO data (paired and unpaired) from 54 patients is near a threshold in a published model.

CONCLUSION

The WTO is feasible for discriminating preferences for short-term health states in an acute medical scenario where it might have been expected to be impracticable.

Magnetic resonance angiography

MRA and MRI have become increasingly important diagnostic modalities in vascular surgery. The ability to obtain cross-sectional and angiographic images by these noninvasive and non-nephrotoxic modalities represents one of the most significant advances in vascular surgery over the past decade. We review the current status of MRI and MRA in vascular surgical practice.

Clopidogrel versus aspirin for secondary prophylaxis of vascular events: a cost-effectiveness analysis

PURPOSE

Clopidogrel is more effective than aspirin in preventing recurrent vascular events, but concerns about its cost-effectiveness have limited its use. We evaluated the cost-effectiveness of clopidogrel and aspirin as secondary prevention in patients with a prior myocardial infarction, a prior stroke, or peripheral arterial disease.

METHODS

We constructed Markov models assuming a societal perspective, and based analyses on the lifetime treatment of a 63-year-old patient facing event probabilities derived from the Clopidogrel versus Aspirin in Patients at Risk of Ischemic Events (CAPRIE) trial as the base case. Outcome measures included costs, life expectancy in quality-adjusted life-years (QALYs), incremental cost-effectiveness ratios, and events averted.

RESULTS

In patients with peripheral arterial disease, clopidogrel increased life expectancy by 0.55 QALYs at an incremental cost-effectiveness ratio of $25,100 per QALY, as compared with aspirin. In poststroke patients, clopidogrel increased life expectancy by 0.17 QALYs at a cost of $31,200 per QALY. Aspirin was both less expensive and more effective than clopidogrel in post-myocardial infarction patients. In probabilistic sensitivity analyses, our evaluation for patients with peripheral vascular disease was robust. Evaluations of stroke and myocardial infarction patients were sensitive predominantly to the cost and efficacy of clopidogrel, with aspirin therapy more effective and less expensive in 153 of 1000 simulations (15.3%) in poststroke patients and clopidogrel more effective in 119 of 1000 simulations (11.9%) in the myocardial infarction sample.

CONCLUSION

Clopidogrel provides a substantial increase in quality-adjusted life expectancy at a cost that is within traditional societal limits for patients with either peripheral arterial disease or a recent stroke. Current evidence does not support increased efficacy with clopidogrel relative to aspirin in patients following myocardial infarction.

Quand, comment et pourquoi réaliser une imagerie des artères des membres inférieurs ?

Noninvasive screening of lower limb arterial disease has long been performed using color Doppler ultrasonography, whereas surgical or endovascular treatment planning relied on conventional angiography. With continued improvements of noninvasive imaging modalities, it is now possible to image the entire lower limb vasculature without arterial catheterization. Multidetector row helical CT angiography has the advantage of visualizing the arterial lumen and arterial wall calcifications, and nephrotoxicity is reduced by decreasing amounts of contrast medium. Three-dimensional MR angiography is a safe procedure, with high contrast sensitivity, and has recently benefited from step table technology that allows a single injection of contrast medium. The literature shows that both helical CT and MR angiography have high levels of accuracy, but outcome studies of their respective role in the setting of acute and chronic lower limb ischemia are lacking. These noninvasive techniques should play a major role in two main situations: first, in critical ischemia where therapeutic planning should ideally be achieved non invasively; second, in the follow-up of treated patients presenting with recurrent ischemia.

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.

Process utility for imaging in cerebrovascular disease

RATIONALE AND OBJECTIVES

The morbidity associated with a diagnostic test can influence its cost-effectiveness, but the quantification of that morbidity is controversial. Accounting for pain and invasiveness requires the measurement of "process utility" in addition to the expected value of testing. An original time trade-off variant was applied to the imaging evaluation of cerebrovascular disease, for which differences in morbidity are important to patients.

MATERIALS AND METHODS

A "waiting trade-off" (WTO) was used to evaluate the preferences of 89 patients for magnetic resonance (MR) angiography and conventional x-ray angiography. Patients were experienced with both tests. A weighted difference was calculated between the period a patient was willing to wait for a test result and treatment after a hypothetical "ideal" test and the choice to undergo conventional angiography or MR angiography with immediate treatment. A rating scale was used to check the convergent validity of the WTO.

RESULTS

Paired data showed a highly significant difference (P = .0001) between the mean preference for conventional and MR angiography, favoring the latter and translating into a difference of 5 quality-adjusted life days. The more negatively patients judged their conventional angiographic experience, the longer they were willing to wait for the ideal test result.

CONCLUSION

The WTO provides a reasonable estimate of the relative morbidity of more invasive conventional angiographic procedures and provides a quality-adjustment term for economic analysis. Such an approach may enable more complete evaluation of the effects of other processes on medical care.

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.

Time-resolved three-dimensional contrast-enhanced MR angiography of the peripheral vessels

PURPOSE

To compare the diagnostic accuracy of time-resolved three-dimensional contrast material-enhanced magnetic resonance (MR) angiography with that of conventional angiography for imaging the lower extremity vasculature.

MATERIALS AND METHODS

Sixty-nine patients who were evaluated for possible surgical intervention underwent conventional angiography (ie, digital subtraction angiography [DSA]) and contrast-enhanced MR angiography (ie, time-resolved imaging of contrast kinetics [TRICKS]). Two independent, blinded readers evaluated vessel stenosis and occlusion at DSA and MR angiographic image readings. Sensitivity, specificity, positive and negative predictive values, and area under the receiver operating characteristic curve were analyzed with repeated-measures analysis of variance. The Cohen kappa test was performed to examine interreader variability.

RESULTS

At pooled readings, contrast-enhanced MR angiography had a sensitivity of 78% and a specificity of 98% for detection of occlusion. For detection of significant stenosis (at least one > or = 50% stenosis), sensitivity and specificity were 77% and 91%, respectively. Interreader agreement was high for detection of both occlusion (kappa = 0.76) and significant stenosis (kappa = 0.68). Sensitivity increased as MR angiographic technical parameters were optimized. When improvements resulting from coil type and injection protocol were considered, the sensitivity and specificity of TRICKS MR angiography were 89% and 97%, respectively, for occlusion detection and 87% and 90%, respectively, for significant stenosis detection.

CONCLUSION

Contrast-enhanced TRICKS MR angiography is a feasible and minimally invasive means of acquiring angiograms of the peripheral vasculature with high sensitivity and specificity.

Study design for concurrent development, assessment, and implementation of new diagnostic imaging technology

With current constraints on health care resources and emphasis on value for money, new diagnostic imaging technologies must be assessed and their value demonstrated. The state of the art in the field of diagnostic imaging technology assessment advocates a hierarchical step-by-step approach. Although rigorous, such a hierarchical assessment is time-consuming, and, given the current rapid advances in technology, results are often too late to influence management and policy decisions. The purpose of this article is to discuss a study design in which development, assessment, and implementation of new diagnostic imaging technology take place concurrently in one integrated process. An empirically based pragmatic study design is proposed for imaging technology assessment. To minimize bias and enable comparison with current technology, a randomized controlled design is used whenever feasible and ethical. Outcome measures should reflect the clinical decision-making process based on imaging information and acceptance of the new test. Outcome measures can include additional imaging studies requested, costs of diagnostic work-up and treatment, physicians' confidence in therapeutic decision making, recruitment rate, and patient outcome measures related to the clinical problem. The key feature of the proposed study design is analysis of trends in outcome measures over time.

Proximity arteriography: cost-effectiveness in asymptomatic penetrating extremity trauma

PURPOSE

Many urban trauma centers have abandoned proximity arteriography, which is defined as exclusion arteriography used to evaluate the asymptomatic patient with penetrating extremity trauma near major arteries. However, decision analysis has not been applied to study proximity arteriography.

MATERIALS AND METHODS

The cost-effectiveness of proximity arteriography was examined by creating a decision model that compared arteriography with observation after patient examination in the trauma unit. The model used predominantly literature-derived estimates for input variables and outcomes. The authors retrospectively reviewed arteriograms for 1 year to identify major occult injuries (requiring intervention) at their institution. After a resource-based cost analysis from the taxpayers' perspective, the cost-effectiveness ratio was calculated (incremental cost per quality-adjusted life year [QALY] gained) for proximity arteriography.

RESULTS

For proximity trauma, arteriography is a dominant strategy (more effective and costs less) at a prevalence of major occult injury of 5.5% or more. Observation is a dominant strategy if the prevalence is from 0% to 0.5% or 2.0%, depending on arteriography complication assumptions. In between, arteriography is cost-effective, with a ratio of $12,100 per QALY at 2.5% prevalence (base case). Besides prevalence of occult injury, the model is sensitive to outcome assumptions for occult injuries.

CONCLUSION

Proximity arteriography is a cost-effective procedure if major occult injuries equal or exceed 1.0%.

Has arteriography gotten a bad name? Current accuracy and morbidity of diagnostic contrast arteriography for aortoiliac and lower extremity arterial disease

Recently, contrast arteriography has been challenged as the diagnostic test of choice for lower extremity arterial disease because of its associated morbidity and questionable accuracy in identifying suitable distal outflow arteries. The purpose of this report was to analyze our experience to determine if these concerns were justified. We reviewed 500 consecutive contrast arteriograms performed at our hospital for aortoiliac and lower extremity arterial disease between November 1994 and November 1998. Arteriograms performed in conjunction with therapeutic procedures such as balloon angioplasty, stent placement, and thrombolysis were excluded, leaving 244 diagnostic cases for analysis. Forty-six percent (112) of patients had diabetes mellitus, 14% (34) had an elevated baseline serum creatinine (> or =1.5 mg/dL), and an additional 7% (17) were dialysis dependent. Radiologists limited contrast volume by imaging only the symptomatic extremity when appropriate and using digital subtraction techniques as indicated. Our results showed that diagnostic contrast arteriography is associated with an acceptably low morbidity, has an accuracy that is unlikely to be surpassed by other modalities, and remains the diagnostic test of choice for lower extremity arterial disease.

Contrast-enhanced peripheral MR angiography from the abdominal aorta to the pedal arteries: combined dynamic two-dimensional and bolus-chase three-dimensional acquisitions

Wang Y, Winchester PA, Khilnani NM, et al. Contrast-enhanced peripheral MR angiography from the abdominal aorta to the pedal arteries: Combined dynamic two-dimensional and bolus-chase three-dimensional acquisitions. Invest Radiol 2001;36:170-177.

RATIONALE AND OBJECTIVES

To obtain reliable contrast-enhanced peripheral MR angiography for imaging peripheral vascular disease from the abdominal aorta to the pedal arteries.

METHODS

A protocol consisting of contrast-enhanced, dynamic two-dimensional (2D) acquisition at the feet and calf and bolus-chase three-dimensional (3D) acquisition from the abdominal aorta to the calf was developed and applied in patients with peripheral vascular disease. The performance of this integrated protocol was assessed in 89 consecutive patients.

RESULTS

The bolus-chase 3D acquisition was of diagnostic quality in 100% of the acquisitions in the abdomen, 96% in the thigh, and 43% in the calf. The poor quality of the calf acquisitions was due to insufficient spatial resolution, poor arterial signal, and venous contamination. Diagnostic-quality images were obtained in 100% of the dynamic 2D acquisitions of the calf and 98% of the feet.

CONCLUSIONS

The combined dynamic 2D and bolus-chase 3D contrast-enhanced MR angiography technique provides diagnostic images of the entire lower extremity.

The costs of CT procedures in an academic radiology department determined by an activity-based costing (ABC) method

PURPOSE

The purpose of this work was to determine the costs of computed tomography (CT) procedures in a large academic radiology department, including both professional (PC) and technical (TC) components, by analyzing actual resource consumption using an activity-based costing (ABC) method and comparing them with Medicare payments.

METHOD

Over a 12 month period from July 1, 1996, to June 30, 1997, 1,011 CT procedures, representing 16 Physicians' Current Procedural Terminology (CPT) codes and 98.3% of CT studies performed, were carefully observed by a research assistant trained in ABC methodology. Information collected during these time and motion studies included personnel/machine time and direct materials used. Actual resource units used during the different activities in each CT procedure were valued using appropriate cost drivers. Unit values for both direct and overhead costs were calculated: the cost of an individual procedure equaled the sum of component costs. Costs were compared with PC and TC payments according to the 1997 Medicare Fee Schedule.

RESULTS

Total costs of CPT codes 70450 (CT Head unenhanced), 71260 (CT Chest enhanced), and 74160 (CT Abdomen enhanced), which represented 71.2% of CT studies performed, were $189.19, $273.53, and $343.20, respectively. For all 16 nonmodified CPT codes analyzed, Medicare's professional reimbursement was less than the professional cost, whereas its technical reimbursement exceeded respective cost in 14 of the 16 codes.

CONCLUSION

In the setting and time period studied, Medicare underreimbursed professional costs while overreimbursing technical costs.

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

PURPOSE

To compare the costs of performing helical computed tomographic (CT) angiography with three-dimensional rendering versus intraarterial digital subtraction angiography (DSA) for preoperative imaging of abdominal aortic aneurysms (AAAs).

MATERIALS AND METHODS

A single observer determined the variable direct costs of performing nine intraarterial DSA and 10 CT angiographic examinations in age- and general health-matched patients with AAA 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 variable direct costs of laboratory tests and using the ambulatory treatment unit for postprocedural monitoring, as well as all fixed direct costs, were assessed from hospital accounting records. The total costs were determined for each procedure and compared by using the Student t test and calculating the CIs.

RESULTS

The mean total direct cost of intraarterial DSA (+/- SD) was $1,052 +/- 71, and that of CT angiography was $300 +/- 30, which are significantly different (P < 4.1 x 10(-11)). With 95% confidence, intraarterial DSA cost 3.2-3.7 times more than CT angiography for the assessment of AAA.

CONCLUSION

Assuming equal diagnostic utility and procedure-related morbidity, institutions may have substantial cost savings whenever CT angiography can replace intraarterial DSA for imaging AAAs.

A time-tradeoff method for cost-effectiveness models applied to radiology

PURPOSE

The wait tradeoff (WTO) is a simple time-tradeoff method designed for temporary health states that uses a realistic and intuitive interface for the patient/subject. This method was tested by assessing patients' preferences for magnetic resonance angiography (MRA) versus x-ray angiography (XRA).

MATERIALS AND METHODS

The WTO was tested by telephone interview in 38 patients with atherosclerotic peripheral vascular disease, all having previously undergone both MRA and XRA. At indifference point, patients were ambivalent about having MRA or XRA and immediate treatment, versus having a waiting period for test results and treatment after a hypothetical "ideal test" that entailed no pain or risk.

RESULTS

The patients were willing to wait a mean of 42.1 days after the ideal test for results and treatment, as opposed to XRA. They were willing to wait only 16.1 days as opposed to MRA. This difference in waiting times was significant (p = 0.0001) and indicates a clear preference for MRA, in agreement with known literature.

CONCLUSION

The WTO method assesses preferences for these radiologic tests in an intuitive fashion that does not invoke artificial or irrelevant health states. This approach may also prove useful for other testing situations or short-term treatments being evaluated for cost-effectiveness.

Automated bolus chase peripheral MR angiography: initial practical experiences and future directions of this work-in-progress

Bolus chase 3-dimensional MR angiography (3D MRA) is a recent development that extends the effective field of view for arterial imaging from the typical single 40-50 cm to over 100 cm. This technique is well suited for imaging long vascular territories such as the lower extremity. Bolus chase peripheral 3D MRA is achieved with overlapping 3D gradient-echo scans during the arterial transit of a single intravenous injection of gadolinium-chelate contrast media. This technique can depict the arteries from the infrarenal aorta to the ankles in less than 2 minutes. The initial experiences with bolus chase peripheral MRA using an automated algorithm that controls both table translation and 3D data acquisition are described. Suggestions for future refinements to the technique are also discussed.

Comparison of treatment plans for lower extremity arterial occlusive disease made with electrocardiography-triggered two-dimensional time-of-flight magnetic resonance angiography and digital subtraction angiography

BACKGROUND

The purpose of the study was to determine whether preoperative treatment plans for patients with lower extremity ischemia can be made with electrocardiography (EKG)-triggered two-dimensional (2D) time-of-flight (TOF) magnetic resonance angiography (MRA) as accurately as digital subtraction angiography (DSA).

METHODS

Forty patients were prospectively evaluated with the combination of EKG-triggered 2D TOF MRA, DSA, and pulse volume recordings. Blinded reviewers graded arterial segments for disease severity. Accuracy of separate MRA- and DSA-based treatment plans was compared with the procedures performed based on all available information.

RESULTS

There was an 86% exact match between MRA- and DSA-based plans (92% MRA and 94% DSA accuracy). The MRA-based plan accurately predicted 90% of suprainguinal and 95% of infrainguinal procedures, whereas the DSA-based plan accurately predicted 100% of suprainguinal and 85% of infrainguinal procedures. Two-year primary patency was 83% for all procedures. Radiologists' review of disease severity resulted in a mean exact correlation between studies of 81% (kappa = 0.64). The agreement between radiologists interpreting the MRA was 84% (kappa = 0.7) compared with 82% (kappa = 0.66) for the DSA.

CONCLUSIONS

MRA- and DSA-based preoperative management plans were of comparable efficacy. Significant interobserver variability was seen with the interpretations of both preoperative studies. EKG-triggered 2D TOF MRA can be used to plan arterial reconstructions; however, all patients require arterial pressure measurements prior to suprainguinal repair and confirmatory intraoperative angiography during infrainguinal revascularization.

Endovascular surgery based solely on noninvasive preprocedural imaging

PURPOSE

Conventional pre-endovascular procedural evaluation uses both noninvasive testing and diagnostic arteriography. Diagnostic and therapeutic procedures often must be performed separately because of concerns about excessive contrast administration or inappropriate location of vascular access for the interventional procedure. We wanted to determine if patients could successfully undergo endovascular procedures based on noninvasive modalities alone.

METHODS

One hundred nineteen consecutive patients requiring intervention for lower-extremity ischemia were evaluated by means of physical examinations and segmental pressure measurements. Patients then underwent magnetic resonance angiography (MRA) to image native vessels or duplex scanning for failing bypass grafts. Suitable patients underwent endovascular procedures with "road map" arteriography, which was compared with preoperative duplex scanning or MRA findings. Costs of the conventional and noninvasive approaches were compared, on the basis of estimated hospital cost schedule.

RESULTS

Sixty consecutive endovascular procedures were performed in 56 patients (105 lesions angioplastied), either alone (30, 50%) or in combination (30, 50%) with another vascular reconstruction. Completely noninvasive evaluation was accomplished in 43 procedures (72%), either by means of duplex scanning (11, 18%) or MRA (32, 53%). Conventional arteriography (CA) was required in 2 patients (3%) because of MRA contraindications and in 1 patient because of complex previous arterial reconstruction. Fourteen patients had earlier CAs. The findings of the noninvasive modalities were confirmed in every case by means of intraoperative arteriography, and no additional lesions were revealed (no false positive or negative studies). After endovascular interventions, the mean patient ankle-brachial index (ABI) improved from 0.64 +/- 0.03 to 0.81 +/- 0.03 (P <.001) and the mean limb-status category improved from 3.4 +/- 0.2 to 0.8 +/- 0.2 (P <.001). There were 4 initial technical failures (7%), 1 morbidity (1%), and no mortalities. The noninvasive approach was less costly than if preprocedural diagnostic CA had been used, allowing $551 saved for each duplex scanning case and $235 saved for each MRA case. If the cost of a short-stay unit after a diagnostic arteriogram was included, the savings were greater: $695 saved for each duplex scanning case and $379 saved for each MRA case.

CONCLUSION

Endovascular procedures can be performed based on preprocedural noninvasive modalities alone. For patients requiring endovascular procedures, knowledge of the arterial anatomy before obtaining arterial access avoids the need for additional punctures or sessions (eg, antegrade puncture for femoral angioplasty after retrograde puncture for the diagnostic arteriogram). This approach is less costly than performing preprocedural diagnostic arteriography and avoids the hazards of arterial puncture and nephrotoxic contrast agents.

Comparison of two-dimensional MR digital subtraction angiography of the lower extremity with x-ray angiography

PURPOSE

To perform a preliminary evaluation of the diagnostic accuracy of contrast-enhanced, two-dimensional (2D) magnetic resonance (MR) digital subtraction angiography (DSA) of the lower extremity by comparison with x-ray angiography (XRA).

MATERIALS AND METHODS

Forty lower extremities in 22 patients were imaged at multiple levels with both XRA and 2D MR DSA. Images were retrospectively analyzed by three radiologists in a randomized blinded manner. Seventeen vascular segments were graded as an insignificant lesion, a significant lesion, or as an occlusion. With the use of segments well depicted with XRA as the gold standard, the sensitivity, specificity, and accuracy of 2D MR DSA, as compared with XRA, were evaluated. The McNemar-Stuart-Maxwell test was performed to determine the significance of any differences found.

RESULTS

Three hundred eighty-three arterial segments were evaluated with both techniques. Three hundred one segments were well depicted with XRA. There was no significant difference between 2D MR DSA and XRA for assessing the degree of occlusive disease in these 301 segments (.25 < P < .5). The sensitivity, specificity, and diagnostic accuracy of 2D MR DSA were found to be 90%, 98%, and 93%, respectively.

CONCLUSION

Two-dimensional MR DSA is an accurate method for assessing arterial lesions in the lower extremity.

Prospective evaluation of peripheral arterial occlusive disease by 2D MR subtraction angiography

The purpose of this study was to assess the diagnostic value of two-dimensional (2D) MR subtraction angiography of lower extremities in patients with symptomatic peripheral arterial occlusive disease with conventional angiography as the standard of reference. Twenty patients were prospectively included. 2D subtraction MR angiography (MRA) consisted of multisection gradient-recalled echo (GRE) acquisitions with the shortest TE available on our machine (4 msec), obtained in the coronal plane before and after intravenous bolus administration of gadolinium chelate. MR images were reconstructed after subtraction with a maximum-pixel-intensity-projection (MIP) algorithm. MRA was performed in all cases 1-4 days before diagnostic angiography. In a prospective blinded analysis, the number and location of significant (ie, >50%) stenoses and occlusions were evaluated for each vascular segment. Sensitivity and specificity were used to evaluate MRA data. Significant stenoses (38 of 46, 83%) and occlusions (66 of 67, 99%) seen at conventional angiography were identified with MRA. The sensitivity and specificity of MRA for determination of stenoses >50% or occlusions was 100% and 97%, respectively. The location and extent of stenoses and/or occlusions on MRA and angiograms were well correlated (kappa values, r = .73, P < .05). Contrast 2D MR subtraction angiography, by providing comparable information to that of conventional angiography, is well suited to evaluate the presence and severity of atherosclerotic lesions of the lower limbs.

Magnetic resonance angiography of lower-extremity arterial disease

Improvements in vascular technique have expanded the treatment options for patients with severe occlusive peripheral vascular disease. The decision to perform a major revascularization procedure in patients who are often at high risk for cardiovascular morbidity and mortality depends on the risk-benefit ratio. Detailed and accurate vascular imaging is essential and evaluating the likelihood of a successful revascularization with subsequent limb salvage. Although contrast angiography has been the time-honored reference standard imaging technique, the method is an invasive procedure with limitations and risks. MRA is a new, noninvasive vascular imaging technique that may now be added to the imaging options with the potential for improved sensitivity for finding patent runoff vessels, avoidance of morbidity, and cost equivalent to that of conventional contrast angiography. Magnetic resonance angiography is a rapidly developing and exciting new vascular imaging technique. As with any new technique, it is imperative that individual centers validate their MRA results and interpretations against the time-honored standard, which continues to be contrast arteriography. Several studies now indicate that MRA can be a cost-effective outpatient imaging technique sufficient for planning and successfully performing peripheral bypass procedures. As developments in hardware, software, and non-nephrotoxic contrast agents continue to increase, applicability of MRA in vascular surgery will continue to expand. Predictably, MRA will have a major role in the future of vascular imaging, and it is likely to supplant the need for conventional contrast angiography in the majority of patients.

Utility of magnetic resonance arteriography for distal lower extremity revascularization

PURPOSE

Magnetic resonance arteriography (MRA) of the lower extremities affords several possible advantages over conventional contrast arteriography (CA). We hypothesized that MRA of the infrageniculate vessels was sufficiently accurate to replace CA before revascularization procedures in patients with limb-threatening ischemia.

METHODS

Fifty-three extremities in 49 patients were prospectively evaluated before attempted infrageniculate revascularization procedures with preoperative infrageniculate time-of-flight MRA (cost, $170/study) and standard contrast arteriography (cost, $1310/study) of the aortoiliac and runoff vessels. Independent operative plans were formulated based on the MRA and CA results before the revascularization procedure. Intraoperative, prebypass arteriograms (IOA; cost, $46/study) were obtained in all patients to confirm the adequacy of the distal runoff. The preoperative plans formulated by the results of MRA and CA were compared with the actual procedure performed based on the IOA. All arteriograms (CA, MRA, IOA) were reviewed after the operation by two independent reviewers, and the number of patent vessel segments and those with < 50% stenosis was determined.

RESULTS

Revascularization procedures were performed in 44 of 53 extremities (83%), and amputation was performed in nine extremities (17%) because of an absence of a suitable bypass target. The CA and MRA were equally effective in predicting the optimal operative plans as determined from IOA (CA, 42 of 53 [77%] vs MRA, 40 of 53 [75%]; p = 0.79). More patent vessel segments were seen on CA than MRA (reviewer A, 229 vs 174, kappa = 0.32; reviewer B, 321 vs 314, kappa = 0.46); however, a comparable number of segments were seen if the vessels of the foot were excluded. The accuracy (reviewer A, 78% vs 68%, p = 0.003; reviewer B, 75% vs 67%, p = 0.003) and sensitivity (reviewer A, 69% vs 51%, p = 0.001; reviewer B, 68% vs 46%, p = 0.0001) of CA relative to IOA were superior to those of MRA, although the specificity was comparable (reviewer A, 86% vs 90%, p = 0.31; reviewer B, 82% vs 87%, p = 0.52). The combination of MRA and IOA would have resulted in the optimal operative plan in 51 of the 53 cases (96%) and was comparable with CA and IOA (53 of 53; 100%; p = 0.50). Substitution of MRA and IOA for CA and IOA could potentially have saved an estimated $60,420.

CONCLUSIONS

The combination of MRA and IOA provides an accurate, cost-efficient strategy for visualization of the infrageniculate vessels before revascularization procedures.

Magnetic resonance angiography in the management of lower extremity arterial occlusive disease: a prospective study

PURPOSE

We conducted a prospective study to clarify the clinical utility of magnetic resonance angiography (MRA) in the treatment of patients with lower extremity arterial occlusive disease.

METHODS

During the interval of September 1993 through March 1995, 79 patients (43% claudicants, 57% limb-threatening ischemia) were studied with both MRA and contrast arteriography (ANGIO) and underwent intervention with either balloon angioplasty (9%), surgical inflow (28%), or outflow (63%) procedures. MRA and ANGIO were interpreted by separate blinded vascular radiologists, and arterial segments from the pelvis to the foot were graded as normal or with increasing degrees of mild (25% to 50%), moderate (51% to 75%), or severe (75% to 99%) stenosis or occlusion. Treatment plans were formulated by the attending surgeon and were based initially on hemodynamic, clinical, and MRA data and thereafter with ANGIO. Additional study surgeons formulated independent and specific treatment plans based on MRA or ANGIO alone. Indexes of agreement (beyond chance) for arterial segments depicted by MRA and ANGIO were assessed (kappa value), and treatment plans formulated were compared (chi-square).

RESULTS

Precise agreement (%) and the percent of major discrepancies (segment classified as normal/mild stenosis on one study and severe stenosis/occlusion on the other) between MRA and ANGIO for respective arterial segments was as follows: common and external iliacs (n = 256) 77/3.5; superficial femoral and above-knee popliteal (n = 255) 73/6.7; below-knee popliteal (n = 131) 84/3.8; infrapopliteal runoff vessels (n = 864) 74/12.4; pedal vessels (n = 111) 69/19.8 Kappa values indicated moderate agreement (between MRA and ANGIO) beyond chance for all arterial segments. Treatment plans formulated by the attending surgeon, the MRA surgeon, and the ANGIO surgeon agreed in more than 85% of cases. Inability of MRA to assess the significance of inflow disease and inadequate detail of tibial/pedal vessels were the principal deficiencies of MRA in those cases where it was considered an inadequate examination.

CONCLUSION

These findings suggest MRA and ANGIO are nearly equivalent examinations in the demonstration of infrainguinal vascular anatomy. MRA is an adequate preoperative imaging study (and may replace ANGIO), particularly in those circumstances when the risk of ANGIO is increased or when clinical and hemodynamic evaluation predict the likelihood of straightforward aortofemoral or femoral-popliteal reconstruction.

MR angiography of the peripheral vasculature

MR angiography (MRA) for the evaluation of peripheral arterial occlusive disease is a rapidly evolving technique. Recent prospective clinical trials have indicated that MRA may play an important role in the evaluation of patients with peripheral arterial disease. This article discusses the pertinent technical aspects and limitations of peripheral MRA as well as some of the clinical data available.

Lower extremity angiography: improved image quality and outflow vessel detection with bilaterally antegrade selective digital subtraction angiography. A blinded prospective intraindividual comparison with aortic flush digital subtraction angiography

RATIONALE AND OBJECTIVES

To introduce routine bilaterally antegrade selective stationary digital subtraction angiography (DSA), and prospectively compare it with unselective stationary DSA in the detection of calf arteries and assess additional time and complication rate.

METHODS

Twenty-five patients received one unselective and two separate antegrade selective studies of each calf. Images were evaluated for image quality, number of depicted run-off vessels, and potential crural bypass recipient arteries.

RESULTS

Bilaterally antegrade selective DSA was significantly superior in image quality and motion artifacts (P < 0.01). The number of adequately depicted run-off arteries per calf increased from 79% (2.37 of 3) to 96% (2.89 of 3) for legs with advanced peripheral vascular disease (PVD). Seventy-nine instead of 62 potential bypass recipients were identified (P = 0.002). Mean procedure time needed for selective catheterizations was 7 minutes. No adverse events were seen.

CONCLUSIONS

Bilaterally antegrade selective DSA clearly is superior to aortic run-off DSA depicting tibial arteries. It requires comparatively small additional effort. Outflow vessel detection essentially is independent of advanced PVD.

The fate of bypass grafts to angiographically occult runoff vessels detected by magnetic resonance angiography

PURPOSE

Magnetic resonance angiography (MRA) is a noninvasive vascular imaging technique that is more sensitive than contrast arteriography (CA) for the detection of patent distal runoff vessels. This technique has facilitated performance of MRA-directed bypass procedures for patients who were believed not to be bypass candidates because of the absence of a suitable target vessel on the preoperative CA. The fate of bypasses to these angiographically occult runoff vessels is unknown, however, and it has been proposed that patients with angiographically occult runoff may have aggressive occlusive disease, rendering bypass procedures ultimately futile.

METHODS

Between April 1992 and February 1995, 212 autogenous vein infrageniculate bypasses were performed for limb-salvage indications, 22 (12%) to angiographically occult runoff vessels. Results of bypasses performed to angiographically occult vessels were compared with those of bypasses to CA-detected runoff vessels. Life-table analysis of graft-patency and limb-salvage rates was performed.

RESULTS

The accuracy of the MRA-predicted patency of angiographically occult vessels was confirmed in every case by the operative findings. Life-table analysis revealed no significant difference in primary graft patency (p > 0.05) or limb-salvage (p > 0.05) rates between patients with bypasses to runoff vessels seen by MRA alone. At 35 months after surgery, the primary graft patency rate was 68% for bypasses to CA-detected vessel bypass and 67% for MRA-detected vessels. The limb salvage rate was 83% for CA-detected vessel bypass patients and 78% for patients with angiographically occult runoff.

CONCLUSIONS

MRA can accurately identify patent runoff vessels not visualized by CA. Results of bypasses performed to angiographically occult runoff vessels are similar to those of bypasses performed to vessels detected by CA. MRA should be performed in patients in whom CA fails to reveal runoff vessels suitable for use in a limb-salvage procedure. The greater sensitivity of MRA may facilitate successful bypass surgery and improve the overall limb-salvage rate.