Should We Use Contrast-Enhanced Ultrasound (CEUS) for the Characterization of Nonpalpable Testicular Lesions? An Analysis from a Cost-Effectiveness Perspective

PURPOSE

 Accurate characterization of testicular lesions is crucial to allow for correct treatment of malignant tumors and to avoid unnecessary procedures in benign ones. In recent years, contrast-enhanced ultrasound (CEUS) proved to be superior in specifying the dignity of small, nonpalpable testicular lesions (< 1.5 cm) compared to native B-mode and color Doppler ultrasound which were previously regarded as the primary imaging method. However, the cost-effectiveness of CEUS has not been evaluated yet. The aim of this study was to analyze the cost-effectiveness of CEUS as compared to unenhanced ultrasound for the characterization of nonpalpable testicular lesions.

METHODS

 A decision model based on Markov simulations estimated lifetime costs and quality-adjusted life years (QALYs) associated with unenhanced ultrasound and CEUS. Model input parameters were obtained from recent literature. Deterministic sensitivity analysis of diagnostic parameters and costs was performed. Also, probabilistic sensitivity analysis using Monte-Carlo Modelling was applied. The willingness-to-pay (WTP) was set to $100 000/QALY.

RESULTS

 In the base-case scenario, unenhanced ultrasound resulted in total costs of $5113.14 and an expected effectiveness of 8.29 QALYs, whereas CEUS resulted in total costs of $4397.77 with 8.35 QALYs. Therefore, the unenhanced ultrasound strategy was dominated by CEUS in the base-case scenario. Sensitivity analysis showed CEUS to be the cost-effective alternative along a broad range of costs.

CONCLUSION

 Contrast-enhanced ultrasound is a cost-effective imaging method for the characterization of nonpalpable testicular lesions.

Use of colour duplex ultrasound as a first line surveillance tool following EVAR is associated with a reduction in cost without compromising accuracy

INTRODUCTION

CT scanning remains the postoperative surveillance imaging modality of choice following EVAR. Concerns regarding cost, exposure to ionising radiation and intravenous contrast have led to a search for a less expensive, equally efficacious and safer method of monitoring EVAR patients after endograft deployment. This study evaluated the cost saving obtained if CDUS was employed as a first line surveillance tool following EVAR, as well as comparing the two entities in terms of efficacy.

PATIENTS & METHODS

Postoperative surveillance CTs and CDUS scans in the 145 patients who have undergone EVAR from 1st June 2003 to 1st July 2010 were compared for the detection of endoleak and determination of residual sac size.

RESULTS

Adopting a protocol where CDUS was employed as the first line surveillance tool following EVAR would result in a reduction in the number of postoperative CTs required in 2010 from 235 to 36. Based on 2010 costings, this would equate to an estimated reduction in expenditure from €117,500 to €34,915 a saving of €82,585. CDUS had a sensitivity of 100% and a specificity of 85% in the detection of endoleaks compared to CT. The positive predictive value was 28% and negative predictive value 100%. The Pearson Coefficient correlation of 0.96 indicates a large degree of correlation between CDUS and CT when measuring residual aneurysm size following EVAR.

CONCLUSION

CDUS can replace CT as the first line surveillance tool following EVAR. This is associated with a significant reduction in the cost of surveillance without any loss of imaging accuracy.

The role of imaging in Graves’ disease: A cost-effectiveness analysis

According to many guidelines, scintigraphy remains the first suggested diagnostic procedure in hyperthyroid patients in spite of the widespread availability of ultrasounds. The aim of this study was to evaluate the cost-effectiveness of sonography versus scintigraphy in the management of Graves's disease, and to assess ultrasound features suggesting cancer in detecting thyroid nodules. Among 1470 hyperthyroid patients evaluated in our department from 2002 to 2005, 426 (29%) had Graves' disease: echographic and scintigraphic features were not suggestive of GD in 20/426 (4.8%) and 11/426 (2.6%) patients, respectively (p=0.763), even if one of the two procedures was almost always diagnostic. Ultrasound identified 68/426 (16%) patients with a concomitant solid lesion, while scintigraphy detected only 9/426 (2.1%) "cold" nodules (p<0.001). Thyroid cancer was diagnosed in 30/68 (47.7%) patients. Malignancy presented at ultrasound investigation blurred margins (26.7% versus 15.8%), microcalcifications (33.3% versus 28.9%) and an anteroposterior and transverse diameter ratio>or=1 (73.3% versus 71.1%); more frequently than benign nodules, but this was not statistically significant. The total cost to obtain a diagnosis by ultrasound was euro14645.34 (euro13312.5 for echography+euro1332.84 for scintigraphy in the 29 patients "negative" at echographic evaluation for GD) versus euro19922.71 by scintigraphy (euro19578.96 for scan+euro343.75 for ultrasounds in the 11 patients "negative" at scintigraphy). Our data show no difference in terms of diagnosis between sonography and scintigraphy. Indeed, scintigraphy was less sensitive in detecting nodules (often of malignant nature) than ultrasound, and, moreover, with a consequent increase of the direct cost of nodule management when scintigraphy is the first line procedure. In conclusion, according to our results, we suggest that ultrasounds with color-Doppler evaluation should be performed as first step in all hyperthyroid patients, and that scintigraphic examination should be limited only to the uncommon cases, where physician's observation, laboratory assays and/or ultrasounds are not diagnostic.

Does the adjunct of ecographic contrast medium Levovist improve the detection rate of prostate cancer?

OBJECTIVES

To evaluate whether the adjunct of an ultrasound contrast medium improves the detection rate of prostate cancer.

METHOD

In 34 patients, scheduled to undergo a trans-perineal extended prostate biopsy, we carried out a color-Doppler ultrasound (CDU) of the prostate before and after i.v. injection of Levovist, an ultrasound contrast medium. Further bioptic samples were taken in the areas where a marked increase in vascularization was noticed.

RESULTS

The overall diagnostic sensitivity, specificity and efficiency were respectively 72.7, 56.2 and 62.9% for transrectal ultrasound (TRUS); 80, 56.2 and 65.3% for CDU and 88.8, 54.5 and 68% for CDU after Levovist injection; 66.5, 72.6 and 65.1% for digito-rectal examination (DRE); 100, 51.4 and 65.4% for total PSA; and 100, 88.8 and 94.3% for PSA free/total. In the 16 patients with prostate carcinoma, the sensitivity of CDU after Levovist was 92.3, 66% for both DRE and TRUS, and 80% for DRE plus TRUS.

CONCLUSIONS

Considering the cost and the results obtained (high sensitivity and low specificity), a routine use of Levovist does not seem indicated in patients undergoing prostatic biopsy. An exception may be represented by patients with both negative DRE and TRUS.

Cost-effectiveness of diagnostic imaging work-up and treatment for patients with intermittent claudication in The Netherlands

OBJECTIVE

to determine the societal cost-effectiveness of various management strategies, including both the diagnostic imaging work-up and treatment, for patients with intermittent claudication in The Netherlands.

METHODS

a decision-analytic model was used and included probability and quality of life data available from the literature. A cost-analysis was performed in a university setting in The Netherlands. Imaging work-up options included magnetic resonance angiography (MRA), color-guided duplex ultrasound, or intraarterial digital subtraction angiography (DSA) and treatment options were percutaneous transluminal angioplasty with selective stent placement if feasible or bypass surgery. Management strategies were defined as combinations of imaging work-up and treatment options. A conservative strategy with no imaging work-up and walking exercises was considered as reference. Main outcome measures were quality-adjusted life years (QALYs), lifetime costs (euro), and incremental cost-effectiveness (CE) ratios. The base-case analysis evaluated 60-year-old men with severe unilateral intermittent claudication of at least one year duration.

RESULTS

the range in QALYs and costs across management strategies that considered angioplasty as only treatment option was small (maximum difference: 0.0033 QALYs and 451 euros). Similarly, the range was small across management strategies that considered angioplasty if feasible otherwise bypass surgery (maximum difference: 0.0033 QALYs and 280 euros). MRA in combination with angioplasty (6.1487 QALYs and 8556 euros) had a CE ratio of 20,000 euros/QALY relative to the conservative strategy. The most effective strategy was DSA in combination with angioplasty if feasible otherwise bypass surgery (6.2254 QALYs and 18,583 euros) which had a CE ratio of 131,000 euros/QALY relative to MRA in combination with angioplasty.

CONCLUSION

the results suggest that the imaging work-up with non-invasive imaging modalities can replace DSA for the work-up of patients with intermittent claudication without a substantial loss in effectiveness and a minimal cost-reduction. Management strategies including angioplasty are cost-effective in the Netherlands but although strategies including bypass surgery are more effective, their incremental costs are very high.

Pretreatment imaging workup for patients with intermittent claudication: a cost-effectiveness analysis

PURPOSE

To determine the optimal imaging strategy in pretreatment workup of patients with intermittent claudication with use of noninvasive imaging modalities and intraarterial digital subtraction angiography (DSA).

MATERIALS AND METHODS

A decision-analytic model that considered test characteristics such as sensitivity, complications induced by the test, implications of missing lesions, and the consequences of overtreating patients, was developed to evaluate the societal cost-effectiveness (CE) of magnetic resonance (MR) angiography, duplex ultrasonography (US), and DSA. Our main outcome measures were quality-adjusted life years (QALYs), lifetime costs (in dollars), and incremental CE ratios. The base-case analysis considered a cohort of 60-year old male patients without a history of coronary artery disease who presented with severe claudication to undergo pretreatment imaging workup.

RESULTS

The range in effectiveness and lifetime costs among different diagnostic workup strategies was small (largest difference in effectiveness: 0.025 QALYs; largest difference in lifetime costs: $1,800). If treatment was limited to angioplasty in patients with suitable lesions, MR angiography had an incremental CE ratio of $35,000 per QALY compared with no diagnostic workup, and DSA had an incremental CE ratio of $471,000 per QALY compared with MR angiography. If treatment options included both angioplasty and bypass surgery, DSA had an incremental CE ratio of $179,000 per QALY compared with no diagnostic workup, and MR angiography and duplex US were less effective and more costly.

CONCLUSIONS

The differences in costs and effectiveness among diagnostic imaging strategies for patients with intermittent claudication are slight and MR angiography or duplex US can replace DSA without substantial loss in effectiveness and with a slight cost reduction.

Role of preoperative color doppler ultrasound scan in the evaluation of the risk of injury of major branches of the middle hepatic vein during laparoscopic cholecystectomy

During laparoscopic cholecystectomy, the separation of the gallbladder from the liver bed may sometimes cause severe hemorrhages. One reason for severe hemorrhages may be injury to the major branches of the middle hepatic vein (MHV), which may be too close or adherent to the gallbladder. In our institutional experience of 798 laparoscopic cholecystectomies, no major hemorrhage from the gallbladder bed has been encountered. The aim of this prospective study was to investigate the relationship between the major branches of the MHV and the gallbladder bed in our patients. We measured the distance of the closest branches of the MHV from the gallbladder bed by color Doppler ultrasound scan. The mean and the median distances of the closest branch of the MHV to the gallbladder was found to be 17.4 +/- 6.2 mm and 17.7 mm, respectively (range, 6-29.1 mm). In conclusion, the distance of the closest branch of the MHV to the gallbladder bed in our patient population seems to allow for a safe laparoscopic cholecystectomy.

Doppler ultrasonography in singleton pregnancies at risk of intrauterine growth retardation-- a national estimate

BACKGROUND

In order to assess the organizational and economical implications of Doppler ultrasonography used in high risk pregnancies, a national estimate of the use in singleton pregnancies with risk of small for gestational age (>2 SD below mean birthweight) (SGA) or intrauterine growth retardation (IUGR) was needed.

METHODS

Through retrospective analyzes of both national registry data, and local clinical and ultrasonic records from Copenhagen University Hospital annual populations of singleton pregnant women with suspected IUGR and/or infants born SGA were described. The antenatal care program for assessing pregnancies with suspected IUGR was described.

RESULTS

In 1996 2.8% of all singleton infants were born SGA. The population had increased risk of perinatal mortality and morbidity, and about 40% had labor induced or were delivered by caesarean section, compared to 15% of the infants with normal birthweight. In the local population 79 (3.3%) of singleton infants were born SGA and 2/3 of these were considered SGA or IUGR before delivery. Of all singleton pregnancies, a total of 88 (3.7%) were assessed by ultrasonic fetometry because of a risk or clinical suspicion of SGA, and 49 (55.7%) of these pregnancies resulted in a SGA infants. Combining national and local data it is estimated that in Denmark, about 2000 women (3.1%) will be referred for ultrasonic fetometry each year because of a risk or clinical suspicion of SGA and have a mean of 2.5 fetometries. About 75% (1500) will be further assessed by Doppler ultrasonography and have a mean of 3.4 Doppler examinations.

CONCLUSION

The annual number of Doppler ultrasonography examinations in singleton pregnancies with increased risk of or signs of IUGR is estimated to be about 5000.

Colour flow Doppler ultrasound of the carotid bifurcation: can it replace routine angiography before carotid endarterectomy?

The objective of this study was to assess the diagnostic accuracy of colour flow Doppler ultrasound (CFD) and its potential to replace digital subtraction angiography (DSA) before carotid endarterectomy (CEA). All patients undergoing CFD of the carotid bifurcation in our department over a period of 1-1/2 years for whom both CFD and DSA results were available were included in the study. We evaluated the feasibility of CFD, its diagnostic accuracy and its potential to diagnose clinically significant stenosis (50%, 70% and 90% NASCET type diameter stenosis) compared with DSA. 225 carotid bifurcations in 116 patients met the criteria for evaluation (biplane arterial DSA without superimposition). Data analysis yielded the following diagnostic performance of CFD: sensitivity for a 50% stenosis 91.4% (95% confidence interval (CI) 83.3--96.2%), specificity 93.2% (95% CI 87.1--96.8%) and accuracy 92.4% (95% CI 88.4--95.4%); sensitivity for a 70% stenosis 89.2% (95% CI 81.9--94.1%), specificity 96.2% (95% CI 90.5--98.6%) and accuracy 92.4% (95% CI 88.4--95.4%). In 9 of 116 cases, carotid angiography was used to evaluate inconclusive CFD results. DSA disclosed relevant information not suspected by CFD in only 1 of the 116 cases. Thus, 91% (106/116) of the angiographies could have been dispensed with without loss of information. One major stroke occurred during diagnostic DSA. We conclude that DSA of the carotid arteries is unnecessary when CFD is unequivocal. The diagnostic gain of DSA must be counterweighted against its potential risks.

[Ultrasound study before surgery of varicose veins]

Ultrasonographic investigation of the various forms of chronic venous insufficiency has substantial advantages compared to diagnosis with the competing phlebogram, particularly preoperatively. Important details such as side branches in the region of the groin, course variations of the small saphenous vein and insufficiency of the perforators in the lower leg are sometimes missed in the antegrade phlebogram. However, it is absolutely necessary to take these into consideration in order to attain a substained good result of surgery. With adequate qualification of the investigator and using all ultrasound techniques, diagnosis by sonography is better than by means of antegrade phlebogram. There are clear specifications for the documentation. With regard to costs and time required, ultrasonographic investigation of chronic venous insufficiency is superior to the antegrade phlebogram and can be repeated at any time.

Duplex scan surveillance during the first year after infrainguinal autologous vein bypass grafting surgery: costs and clinical outcomes compared with other surveillance programs

PURPOSE

In this study we assessed the costs and clinical outcomes of duplex scan surveillance during the first year after infrainguinal autologous vein bypass grafting surgery and compared duplex scan surveillance, ankle-brachial index surveillance, and clinical follow-up.

METHODS

In a clinical study, 293 patients (mean age, 70.1 years; 58.7% men) with peripheral arterial disease were observed in a duplex scan surveillance program after infrainguinal autologous vein bypass grafting surgery. Costs were calculated from the health care perspective for surveillance and subsequent interventions from 30 days to 1 year postoperatively. All costs are presented in 1995 US dollars per patient. In a simulation model, we estimated the costs and amputations of duplex scan surveillance, ankle-brachial index surveillance, and clinical follow-up conditional on the indication for surgery. The main outcome measure was the incremental cost per major amputation per patient avoided during the first postoperative year.

RESULTS

Duplex scan surveillance was the least expensive ($2823) and resulted in the fewest major amputations (17 per 1000 patients examined), compared with ankle-brachial index surveillance ($5411 and 77 amputations per 1000 patients) and clinical follow-up ($5072 and 77 amputations per 1000 patients). In patients treated for critical limb ischemia, duplex scan surveillance was the least expensive ($2974) and resulted in the fewest major amputations (19 per 1000 patients). Under all surveillance programs, 13 major amputations per 1000 patients treated for intermittent claudication were performed, and clinical follow-up had the lowest costs ($1577). In a sensitivity analysis that assumed that duplex scan surveillance could have avoided six major amputations per 1000 patients treated for intermittent claudication compared with the other programs, duplex scan surveillance had an incremental cost of $80,708 per major amputation per patient avoided compared with clinical follow-up.

CONCLUSION

Duplex scan surveillance is highly effective for patients treated for critical limb ischemia, leading to a reduction of major amputations and consequently to a reduction in costs compared with other surveillance programs. In patients treated for intermittent claudication, the evidence supporting duplex scan surveillance is less firm, but if duplex scan can avoid six major amputations per 1000 patients examined, the incremental costs are justified.

Color Doppler measurement of blood flow in the inferior thyroid artery in patients with autoimmune thyroid diseases

PURPOSE

The aim of the study is to find out whether the measurement of peak systolic velocity in the inferior thyroid artery (ITA) is a valuable parameter to differentiate autoimmune thyroid diseases (hyper-, normo- or hypofunctional) and to evaluate the efficacy of medical treatment.

MATERIAL AND METHODS

The ITA of 31 patients (eight with Graves' disease, 23 with subclinical hypothyroidism) was examined with color Doppler and pulsed Doppler. The final diagnosis was obtained by cytology and by hormonal and antibodies assays. The patients were monitorized by ultrasound for a period of 8 months.

RESULTS

In all the patients with Graves' disease the peak systolic velocity was always over 150 cm/s, while in other autoimmune thyroiditis the peak systolic velocity was within the normal range, and never exceeding 65 cm/s. In the first group, the measurement taken in the ITA showed also the efficacy of the pharmacological treatment earlier and more reliably than the color Doppler pattern obtained in the parenchyma.

CONCLUSIONS

The color Doppler measurement of the ITA seems to be a promising technique with low-cost and easy approach. In our experience, the color Doppler of the ITA could have a clinical role in the differential diagnosis of diffuse thyroid diseases and in the follow-up of the Graves' disease during medical treatment.

Power Doppler imaging: initial evaluation as a screening examination for carotid artery stenosis

PURPOSE

To evaluate power Doppler imaging as a possible screening examination for carotid artery stenosis.

MATERIALS AND METHODS

In the principal pilot study, a prospective, blinded comparison of power Doppler imaging with duplex Doppler imaging, the reference-standard method, was conducted in 100 consecutive patients routinely referred for carotid artery imaging at a large, private multispecialty clinic. In the validation pilot study, a prospective, blinded comparison of power Doppler imaging with digital subtraction angiography, the reference-standard method, was conducted in 20 consecutive patients routinely referred at a teaching hospital. Using conservative assumptions, the authors performed cost-effectiveness analysis.

RESULTS

Power Doppler imaging produced diagnostic-quality images in 89% of patients. When the images of the patients with nondiagnostic examinations were regarded as positive, power Doppler imaging had an area under the receiver operating characteristic curve, A(z), of 0.87, sensitivity of 70%, and specificity of 91%. The validation study results were very similar. The cost-effectiveness of screening and, as indicated, duplex Doppler imaging as the definitive diagnostic examination and endarterectomy was $47,000 per quality-adjusted life-year.

CONCLUSION

The A(z) value for power Doppler imaging compares well with that for mammography, a generally accepted screening examination, and with most other imaging examinations. Power Doppler imaging is likely to be a reasonably accurate and cost-effective screening examination for carotid artery stenosis in asymptomatic populations.

A new accurate, rapid and cost-effective protocol for stroke-prevention screening

The three immediate causes of stroke are cervical carotid artery disease, atrial fibrillation and hypertension. Recognition and appropriate management of these causes can prevent the majority of strokes they would have caused. The purpose of this study was to develop a new protocol for screening for these causes that is more accurate, rapid and cost effective than existing protocols. In this protocol, rather than relying on auscultation with a stethoscope, the carotid artery was screened with a newly developed and more accurate quick color image scan ultrasound technique and a lead 2 EKG rhythm strip was used to find atrial fibrillation. The focus in this protocol was on the rapid detection of the three immediate causes of stroke and did not include a lengthy questionnaire or long counseling. A cholesterol determination was not included and there was little or no cost to the participants. In stroke screening trials of the new protocol at two institutions, 176 participants were screened at a rate of one every 2.7 minutes. There were 26 with > 50% carotid stenosis, 16 with previously unknown cardiac arrhythmias and 104 had hypertension. It was concluded that this protocol provides an accurate, rapid and cost-effective means of screening for the three immediate causes of stroke and can on broad application result in significant stroke reduction.

Color Doppler imaging of the eye and orbit

Since the development of A- and B-scan ultrasound technique in the 1950s, significant progress in ophthalmic ultrasound has appeared. As the technology advances and ultrasound systems improve their ability to acquire and detect ultrasonic signals and to analyze them in terms of a spatial resolution and frequency distribution, there is no doubt that the extent of clinical applications will expand accordingly. Nevertheless, the fundamental physical restrictions of ultrasonography and Doppler will always remain the same. For ophthalmology, we hope that less expensive color Doppler systems with specifically designed probes, improved two-dimensional resolution, and Doppler spectrum acquisition will become more widely available. Because CDI allows for the first time a noninvasive assessment of the retrobulbar vasculature, we feel that many applications of this technology will develop for ophthalmology.

Preoperative evaluation of patients with primary hyperparathyroidism: role of high-resolution ultrasound

Unilateral parathyroid exploration with adenoma removal and identification of a normal parathyroid gland is an accepted surgical approach for the treatment of patients with primary hyperparathyroidism. This study prospectively evaluated the ability of high-resolution sonography to localize adenomas preoperatively and the effect of this localization on operative time and cost in 37 previously untreated patients undergoing surgical treatment for primary hyperparathyroidism. The sensitivity and positive predictive value of the sonographic examination were 84% and 90%, respectively. A true positive sonographic examination decreased surgical time by an average of 40 minutes and reduced operative charges by $564, including the cost of the test ($156). In experienced hands high-resolution sonography can be a cost-effective means of localizing parathyroid adenomas where unilateral exploration is considered an accepted surgical approach.

Cost-effectiveness of colour duplex sonography compared with angiography of the pelvis and lower limb

The present investigation was performed to assess the clinical consequences, utility and efficacy of colour duplex sonography (CDS) compared with angiography as a preoperative examination in aorta, pelvis and lower limb, and thus to estimate the cost-effectiveness of CDS. CDS was additionally performed in 53 consecutive patients referred for preoperative angiography of the lower limb. The results for 49 patients were reviewed and compared to assess the technique's clinical utility. The costs of the two methods and the consequences of inappropriate treatment were assessed. In 15 patients inadequate diagnoses were obtained at CDS. If surgery had been performed solely on the basis of the ultrasonographic diagnosis, repeat surgery would have been necessary in 9 patients. In a further 3 patients necessary surgery would not have been performed. Two patients would have been overtreated (unnecessary surgery instead of percutaneous transluminal balloon angioplasty). To correct the initial incorrect diagnosis the estimated yearly cost would be approximately 1.3 million Swedish crowns. In addition, complications and discomfort could be anticipated for the patients. Because of its low sensitivity CDS ist not cost-effective as a preoperative investigation of arteries of the pelvis and lower limb.

[Liver transplantation and diagnostic radiology: socioeconomic aspects]

PURPOSE

For calculating cost-effectiveness in the context of diagnosis related groups (DRG) we analysed all radiological examinations for 56 consecutive liver transplantations during the primary stay in the surgical department (1052 chest x-rays, 296 ultrasonographies, 216 colour coded duplex sonographies, 72 cholangiographies, 35 CT, 23 angiographies, one MRI and one embolisation).

METHODS

For calculation we used the reimbursement that the surgical wards received per patient day and the special fee for liver transplantation. We compared this with the refunds received by the department of radiology.

RESULTS

The hospital was reimbursed a total of 143785.80 DM per patient. The diagnostic and interventional procedures that were requested for the 56 patients amounted to a total of 225118.63 DM and 4019.96 DM per patient, respectively.

CONCLUSIONS

This means that only 2.8% of all the costs during and after liver transplantation were caused by the radiological examinations. This represents only a small portion of the expenses during the time in hospital, taking into account especially that patients after liver transplantation are at high risk for developing complications.

Imaging of carotid artery stenosis: clinical efficacy and cost-effectiveness

PURPOSE

To determine the most accurate, safe, and cost-effective imaging protocol for selecting patients for carotid endarterectomy.

METHODS

The actual costs of carotid angiography, ultrasound, and MR angiography were calculated. The diagnostic accuracy with different confidence levels was assessed for carotid ultrasound and MR angiography in 45 patients. The cost-effectiveness and theoretical impact on patient outcome of hypothetical screening models were compared.

RESULTS

Ultrasound before angiography is more effective and considerably cheaper than performing angiography in all patients presenting with transient ischemic attacks ($25 216 versus $48 708 imaging costs per one prevented stroke). When the more costly MR angiography was used to select patients for angiography the slightly higher diagnostic accuracy did not result in a greater number of prevented strokes. As the only preoperative scrutiny, the combination of ultrasound and MR angiography would have resulted in a greater number of prevented strokes than invasive angiography (27.9 versus 23.3) but at the expense of unnecessary surgery (6.6% of all surgeries).

CONCLUSIONS

Ultrasound followed by confirmatory angiography is a cost-effective way to image patients suspected of carotid artery stenosis. MR angiography may become cost effective and lead to a better final patient outcome only when it can reliably replace invasive angiography as the preoperative examination.

Ultrasound of focal hepatic lesions

Hepatic sonography is useful in characterizing many focal liver lesions (Tables 2-6). It is safe, portable, and relatively inexpensive. With the development of color Doppler imaging, power Doppler imaging, and intravenous-ultrasound contrast agents, the ability to detect and precisely diagnose a focal hepatic lesion may be improved.

[Cost saving after-care in infra-inguinal vascular reconstruction]

To assess the indications for routine colour flow duplex surveillance, 43 infrainguinal autogenous vein grafts were prospectively entered into a surveillance protocol. Screening consisted of measurements of ankle brachial indices (ABI) and colour flow duplex imaging of the entire graft length. All grafts at risk had a serial fall in resting ABI of more than 0.1. This study suggests that resting ABI measurements are a very sensitive and non-expensive primary screening procedure, provided that all grafts with ABI changes of more than 0.1 are further evaluated. About 60% of ABI-screened grafts needed further evaluation because of ABI changes of greater than 0.1, incompressibility of arteries or extension of the graft to the ankle or pedal arteries. Colour flow duplex scanning was very useful in excluding of identifying and localising graft problems and deciding on further invasive diagnostic and therapeutic procedures.