The Effect of Price on Surgeons' Choice of Implants: A Randomized Controlled Survey

PURPOSE

Surgical costs are under scrutiny and surgeons are being held increasingly responsible for cost containment. In some instances, implants are the largest component of total procedure cost, yet previous studies reveal that surgeons' knowledge of implant prices is poor. Our study aims to (1) understand drivers behind implant selection and (2) assess whether educating surgeons about implant costs affects implant selection.

METHODS

We surveyed 226 orthopedic surgeons across 6 continents. The survey presented 8 clinical cases of upper extremity fractures with history, radiographs, and implant options. Surgeons were randomized to receive either a version with each implant's average selling price ("price-aware" group), or a version without prices ("price-naïve" group). Surgeons selected a surgical implant and ranked factors affecting implant choice. Descriptive statistics and univariate, multivariable, and subgroup analyses were performed.

RESULTS

For cases offering implants within the same class (eg, volar locking plates), price-awareness reduced implant cost by 9% to 11%. When offered different models of distal radius volar locking plates, 25% of price-naïve surgeons selected the most expensive plate compared with only 7% of price-aware surgeons. For cases offering different classes of implants (eg, plate vs external fixator), there was no difference in implant choice between price-aware and price-naïve surgeons. Familiarity with the implant was the most common reason for choosing an implant in both groups (35% vs 46%). Price-aware surgeons were more likely to rank cost as a factor (29% vs 21%).

CONCLUSIONS

Price awareness significantly influences surgeons' choice of a specific model within the same implant class. Merely including prices with a list of implants leads surgeons to select less expensive implants. This implies that an untapped opportunity exists to reduce surgical expenditures simply by enhancing surgeons' cost awareness.

TYPE OF STUDY/LEVEL OF EVIDENCE

Economic/Decision Analyses I.

Interpretation of Post-operative Distal Humerus Radiographs After Internal Fixation: Prediction of Later Loss of Fixation

PURPOSE

Stable fixation of distal humerus fracture fragments is necessary for adequate healing and maintenance of reduction. The purpose of this study was to measure the reliability and accuracy of interpretation of postoperative radiographs to predict which implants will loosen or break after operative treatment of bicolumnar distal humerus fractures. We also addressed agreement among surgeons regarding which fracture fixation will loosen or break and the influence of years in independent practice, location of practice, and so forth.

METHODS

A total of 232 orthopedic residents and surgeons from around the world evaluated 24 anteroposterior and lateral radiographs of distal humerus fractures on a Web-based platform to predict which implants would loosen or break. Agreement among observers was measured using the multi-rater kappa measure.

RESULTS

The sensitivity of prediction of failure of fixation of distal humerus fracture on radiographs was 63%, specificity was 53%, positive predictive value was 36%, the negative predictive value was 78%, and accuracy was 56%. There was fair interobserver agreement (κ = 0.27) regarding predictions of failure of fixation of distal humerus fracture on radiographs. Interobserver variability did not change when assessed for the various subgroups.

CONCLUSIONS

When experienced and skilled surgeons perform fixation of type C distal humerus fracture, the immediate postoperative radiograph is not predictive of fixation failure. Reoperation based on the probability of failure might not be advisable.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic III.

Pain in femoral arteriography: A double-blind, randomized, clinical study comparing safety and efficacy of the iso-osmolar iodixanol 270mgI/ml and the low-osmolar iomeprol 300 mgI/ml in 9 European centers

Purpose: To compare the injection-associated pain and heat sensation after administration of the iso-osmolar contrast medium (IOCM) iodixanol (Visipaque™ 270 mg I/ml) and the low osmolar contrast medium (LOCM) iomeprol (Iomeron™ 300 mg I/ml) in femoral arteriography.

Material and Methods: 352 patients received iodixanol or iomeprol in a prospective, double-blind, randomized, parallel-group clinical trial. The first injection during femoral arteriography (DSA with automated stepping) was standardized. Injection-associated pain and heat sensation, efficacy and safety up to 72 h were evaluated.

Results: The iodixanol group reported significant less injection-associated pain than the iomeprol group after the first injection (7.4% vs. 17.6%; p = 0.007), and after all injections (11% vs. 19.4%; p = 0.045). Iodixanol caused less heat sensation after the first injection ( p = 0.007) and after all injections ( p = 0.029). Heat sensations in the iodixanol group were less intense after all injections ( p < 0.0001). No difference was found between the groups regarding the frequency of patients having adverse reactions (5.1% vs. 4%).

Conclusion: The IOCM iodixanol caused significantly less frequent injection-associated pain and heat sensation than the LOCM iomeprol during femoral arteriography.

Selective intraarterial fibrinolysis of acute central retinal artery occlusion

Purpose: To evaluate the outcome of our patients with central retinal artery occlusion after local fibrinolysis and to compare these data with results reported in the literature.

Material and Methods: Over a period of 7 years, 22 patients (11 male, 11 female, mean age 64.6 ± 12.1 years) were treated with super-selective local fibrinolysis. In 1 case, treatment was carried out via the maxillary-ophthalmic anastomoses due to preexisting occlusion of the ipsilateral internal carotid artery. The latency period from the onset of symptoms to the beginning of therapy was 7.6 ± 1.8 h. Urokinase was used in 7 cases (300,000–1.1 million units) and recombinant tissue plasminogen activator (20–40 mg) was applied in 15 patients. Visual acuity and fundus were examined before and after treatment.

Results: One patient (1/22 = 4.6%) recovered completely and regained a visual acuity of 20/20. Six patients (6/22 = 27.3%) showed a marked improvement with a range of visual outcome from 20/800 to 20/320. In 2 cases (2/22 = 9.1%) only a slight improvement was observed, with a visual outcome allowing detection of hand movements. In 13 cases (13/22 = 59.1%) no change in visual acuity as a result of treatment was observed. In 2/22 cases (9.2%) reversible neurological side-effects occurred, in 1 case suffered a stroke, and in another case intracerebral bleeding was observed.

Conclusion: In our study, the recovery of visual acuity and the complication rate were not as positive as reported in the literature.

Trigger finger: assessment of surgeon and patient preferences and priorities for decision making

PURPOSE

To test the null hypothesis that there are no differences in the priorities and preferences of patients with idiopathic trigger finger (TF) and hand surgeons.

METHODS

One hundred five hand surgeons of the Science of Variation Group and 84 patients with TF completed a survey about their priorities and preferences in decision making regarding the management of TF. The questionnaire was structured according the Ottawa Decision Support Framework for the development of a decision aid.

RESULTS

Patients desired orthotics more and surgery less than physicians. Patients and physicians disagreed on the main advantage of several treatment options for TFs and on disadvantages of the treatment options. Patients preferred to decide for themselves after receiving advice, whereas physicians preferred a shared decision. Patients preferred booklets, and physicians opted for Internet and video decision aids.

CONCLUSIONS

Comparing patients and hand surgeons, there were some differences in treatment preferences and perceived advantages and disadvantages regarding idiopathic TF-differences that might be addressed by a decision aid.

CLINICAL RELEVANCE

Information that helps inform patients of their options based on current best evidence might help them understand their own preferences and values, reduce decisional conflict, limit surgeon-to-surgeon variations, and improve health.

Primary percutaneous aspiration and thrombolysis for the treatment of acute embolic superior mesenteric artery occlusion

OBJECTIVES

To evaluate technical success rate and clinical outcome of patients with acute embolic superior mesenteric artery (SMA) occlusion who were treated with primary percutaneous revascularization.

METHODS

At three medical centers the radiological information system databases were used to identify all patients in whom primary percutaneous revascularization for the treatment of acute embolic SMA occlusion was attempted between 2001 and 2010. Percutaneous treatment was performed in 15 patients (median age 80 years, range 49-88 years). These patients represent the study population. Eleven patients reported abdominal pain. Five patients exhibited peritoneal signs. Revascularization was defined as complete technical success if (1) patency of the SMA with residual stenosis of not more than 30% in diameter and (2) sufficient perfusion of the entire bowel were obtained.

RESULTS

Complete technical success was achieved in eleven patients. After percutaneous revascularization laparotomy was performed in six patients and in three of them bowel resection was carried out (length of resected segments 20-80 cm). The 30-day mortality was 33% (five of 15 patients). None of the surviving patients exhibited short-bowel syndrome.

CONCLUSIONS

Primary percutaneous aspiration and thrombolysis constitutes a promising alternative to surgical revascularization in selected patients with acute embolic SMA occlusion.

[Pulmonary embolism caused by PMMA in percutaneous vertebroplasty. Case report and review of the literature]

We report on an 80-year-old female patient with osteoporotic collapse of the L1 vertebra who developed absolute stenosis of the spinal canal. During preoperative vertebra augmentation with PMMA (polymethylmethacrylate), pulmonary embolism developed due to perivertebral leakage of acrylic cement. According to the literature, leakage of PMMA during (percutaneous) vertebroplasty is a more frequent complication than assumed so far. In view of the favorable prognosis of osteoporotic vertebral compression fractures with noninvasive management, we emphasize the need for clear and individual indications and adequate technical settings.

Selective intraarterial fibrinolysis of acute central retinal artery occlusion

PURPOSE

To evaluate the outcome of our patients with central retinal artery occlusion after local fibrinolysis and to compare these data with results reported in the literature.

MATERIAL AND METHODS

Over a period of 7 years, 22 patients (11 male, 11 female, mean age 64.6 +/- 12.1 years) were treated with super-selective local fibrinolysis. In 1 case, treatment was carried out via the maxillary-ophthalmic anastomoses due to preexisting occlusion of the ipsilateral internal carotid artery. The latency period from the onset of symptoms to the beginning of therapy was 7.6 +/- 1.8 h. Urokinase was used in 7 cases (300,000-1.1 million units) and recombinant tissue plasminogen activator (20-40 mg) was applied in 15 patients. Visual acuity and fundus were examined before and after treatment.

RESULTS

One patient (1/22 = 4.6%) recovered completely and regained a visual acuity of 20/20. Six patients (6/22 = 27.3%) showed a marked improvement with a range of visual outcome from 20/800 to 20/320. In 2 cases (2/22 = 9.1%) only a slight improvement was observed, with a visual outcome allowing detection of hand movements. In 13 cases (13/22 = 59.1%) no change in visual acuity as a result of treatment was observed. In 2/22 cases (9.2%) reversible neurological side-effects occurred, in 1 case suffered a stroke, and in another case intracerebral bleeding was observed.

CONCLUSION

In our study, the recovery of visual acuity and the complication rate were not as positive as reported in the literature.

Pain in femoral arteriography. A double-blind, randomized, clinical study comparing safety and efficacy of the iso-osmolar iodixanol 270 mgI/ml and the low-osmolar iomeprol 300 mgI/ml in 9 European centers

PURPOSE

To compare the injection-associated pain and heat sensation after administration of the iso-osmolar contrast medium (IOCM) iodixanol (Visipaque trade mark 270 mg I/ml) and the low osmolar contrast medium (LOCM) iomeprol (Iomeron trade mark 300 mg I/ml) in femoral arteriography.

MATERIAL AND METHODS

352 patients received iodixanol or iomeprol in a prospective, double-blind, randomized, parallel-group clinical trial. The first injection during femoral arteriography (DSA with automated stepping) was standardized. Injection-associated pain and heat sensation, efficacy and safety up to 72 h were evaluated.

RESULTS

The iodixanol group reported significant less injection-associated pain than the iomeprol group after the first injection (7.4% vs. 17.6%; p = 0.007), and after all injections (11% vs. 19.4%; p = 0.045). Iodixanol caused less heat sensation after the first injection (p = 0.007) and after all injections (p = 0.029). Heat sensations in the iodixanol group were less intense after all injections (p < 0.0001). No difference was found between the groups regarding the frequency of patients having adverse reactions (5.1% vs. 4%).

CONCLUSION

The IOCM iodixanol caused significantly less frequent injection-associated pain and heat sensation than the LOCM iomeprol during femoral arteriography.

[Evaluation of a hemostatic device with percutaneous collagen application (VasoSeal) compared to a mechanical compression system (Compressar) after transfemoral catheterization of patients suffering from arterial occlusive disease]

PURPOSE

Comparison of the efficacy of VasoSeal and a mechanical compression system (Compressar) for percutaneous hemostasis after femoral arterial catheterization of patients with arterial occlusive disease.

MATERIALS AND METHODS

60 patients underwent either diagnostic angiography or interventional procedures. The level of anticoagulation, blood pressure, and activation clotting time were recorded, and the time to hemostasis after sheath removal was measured. VasoSeal application was considered "successful" if the compression time was less than two minutes. On the subsequent day as well as 4 months later, color coded Doppler ultrasound was performed to register treatment success and potential (late) complications.

RESULTS

57 patients qualified for inclusion in this study. In 21 of the 26 patients who underwent the procedure with the VasoSeal, immediate hemostasis was achieved within 1.75 minutes. In all 31 patients who had the Compressar applied, hemostasis was successful with a mean compression time of 17.4 minutes. Thus, VasoSeal significantly reduced hemostasis time irrespective of anticoagulation status, but it had a much higher incidence of minor local complications (bleeding, hematoma) compared to the control group (34.6 % vs. 5.8 %). The technical success was lower with VasoSeal than with Compressar (81 % vs. 100 %). Both groups had no severe or late complications.

CONCLUSION

According to our results, VasoSeal does not provide a suitable alternative compared to the effective, safe and cheap application of Compressar as a hemostatic device.

Appearance of vascular stents in computed tomographic angiography: in vitro examination of 14 different stent types

RATIONALE AND OBJECTIVES

To evaluate the appearance of the vessel lumen after implantation of different vascular stents with the use of a computed tomographic (CT) angiography model.

METHODS

A vascular phantom was studied with helical CT and different slice thicknesses (2 and 3 mm) and pitch values (1.0, 1.5, and 2.0). Original transverse CT images and coronal reformations were evaluated. Fourteen different stents were analyzed with regard to changes in the stent lumen (attenuation values, noise, and artificial lumen narrowing).

RESULTS

Some stents caused artifacts resulting in potential errors during evaluation of their patency. Assessment of the lumen was impaired in two stents (Strecker tantalum and Passager). Increased attenuation values were measured in all stents (increase of 8%-145%). The degree of artificial lumen narrowing was 4.4% to 77.8%.

CONCLUSIONS

In most stents, reliable evaluation of the stent lumen seems possible. However, knowledge of the artifacts caused by different stent types is useful for the assessment of stent patency with CT angiography.

[The endoleak problem in endoluminal therapy]

Endovascular treatment of aortic aneurysms with stent grafts was performed increasingly in recent years. The most frequent complication after endovascular therapy of aortic aneurysms is an endoleak. In case of a persistent endoleak, diameter of the aneurysm is increasing with a high risk of aneurysm ruptur. Diagnostic tools are spiral computed tomography and angiography. Spiral computed tomography is the most sensitive method for the diagnosis of an endoleak ad should be performed with a biphasic acquisition. In- and outflow of sidebranches can be identified correctly with selective angiography in 86%. Perigraft endoleaks should be treated in any case. Patent side branches generally are observed over a period of 6 months. After 6 months approximately half of these endoleaks are thrombosed. Is there an increasing of the diameter of the aneurysm or any changing in the morphology of the aneurysm there is an indication for embolisation of these sidebranches of the aneurysmal sac. Preinterventional embolisation of patent sidebranches is under discussion. Type I endoleaks can be managed by additional stent-graft implantation or coil embolisation. In case of type II endoleaks in- ad outflow vessels should be embolised with coils. Therapy of type III endoleak is performed mostly by additional stent-graft placement. The total incidence of secondary interventions in the Eurostar-study was nearly 10% per year.

[The problem with endoleakage in endoluminal therapy]

Endovascular treatment of aortic aneurysms with stent grafts was performed increasingly in recent years. The most frequent complication after endovascular therapy of aortic aneurysms is an endoleak. In case of a persistent endoleak, diameter of the aneurysm is increasing with a high risk of aneurysm rupture. Diagnostic tools are spiral computed tomography and angiography. Spiral computed tomography is the most sensitive method for the diagnosis of an endoleak ad should be performed with a biphasic acquisition. In- and outflow of sidebranches can be identified correctly with selective angiography in 86%. Perigraft endoleaks should be treated in any case. Patent side branches generally are observed over a period of 6 months. After 6 months approximately half of these endoleaks are thrombosed. Is there an increasing of the diameter of the aneurysm or any changing in the morphology of the aneurysm there is an indication for embolisation of these sidebranches of the aneurysmal sac. Preinterventional embolisation of patent sidebranches is under discussion. Type I endoleaks can be managed by additional stent-graft implantation or coil embolisation. In case of type II endoleaks in- ad outflow vessles should be embolised with coils. Therapy of type III endoleak is performed mostly by additional stent-graft placement. The total incidence of secondary interventions in the Eurostar-study was nearly 10% per year.

Renal time-resolved MR angiography: quantitative comparison of gadobenate dimeglumine and gadopentetate dimeglumine with different doses

PURPOSE

Results with different doses of gadobenate dimeglumine and gadopentetate dimeglumine were compared at magnetic resonance (MR) angiography of the renal arteries. The signal-to-noise ratio (SNR) was evaluated as a quantitative measure of image quality.

MATERIALS AND METHODS

Sixty consecutive patients (age range, 24-81 years; mean age, 65 years) underwent intraarterial digital subtraction angiography (DSA) and contrast material-enhanced time-resolved MR angiography. DSA was the standard of reference. Fifteen patients received gadopentetate dimeglumine at doses of 0.2 or 0.1 mmol per kilogram of body weight. Fifteen patients received gadobenate dimeglumine at doses of 0.05 or 0.1 mmol/kg. The SNR was calculated in the aorta and both main renal arteries. The number and degree of stenoses of the renal arteries and accessory vessels were evaluated by four observers.

RESULTS

SNRs with gadobenate dimeglumine at a dose of 0.1 mmol/kg were significantly superior to those with gadopentetate dimeglumine at a dose of 0.1 mmol/kg. Differences were not statistically significant between the SNRs in the other groups. Eleven (85%) of 13 hemodynamically significant renal artery stenoses were detected correctly with MR angiography as were 22 (85%) of 26 accessory renal arteries.

CONCLUSION

SNRs with gadobenate dimeglumine were higher than those with gadopentetate dimeglumine, but in most cases the differences in SNRs were not statistically significant.

[Treatment of para-ostium renal artery stenoses with a new, solidly premounted balloon expandable stent]

PURPOSE

Evaluation of the handling, technical success rate, and six-months patency rate of a new, premounted balloon-expandable stent in ostial renal artery stenoses.

MATERIAL AND METHODS

In a prospective study, 27 ostial renal artery stenoses in 20 patients were primarily treated with the new "Renal Bridge Stent" (Medtronic AVE, Düsseldorf). All patients had a history of hypertension and 8 patients had renal dysfunction. The handling and visibility of the stent was scored on a three grade scale by the operators. Follow-up angiography including intra-arterial trans-stenotic pressure measurements was performed in 23 out of 27 stenoses (17 patients).

RESULTS

Handling and visibility were scored as good by all operators. 26 of 27 stenoses were treated with technical success by implantation of 28 stents. The mean degree of stenosis was reduced from 74.2% to less than 5%. At 6 months, 8 stents out of 23 (35%) showed a significant in-stent stenosis (stenosis degree > 50% and intra-arterial pressure gradient > 10 mmHg). The stenosis rates were 63% using 5-mm stents, 30% using 6-mm stents, and 0% using 7-mm stents.

CONCLUSION

Endovascular treatment of ostial renal artery stenosis with the used stent is safe and effective. The new stent shows a good handling and visibility. The high rate of in-stent stenoses might be explained by the rigid follow-up protocol including angiography, trans-stenotic pressure measurements, and the high number of 5-mm vessels in our study.

[Percutaneous transfemoral implantation of a new, flexible thoracic aorta endoprosthesis using a percutaneous suture system for vascular suture--initial experiences]

PURPOSE

To evaluate the transfemoral placement of a new, flexible stent-graft into the thoracic aorta and the suture-mediated closure of the femoral access.

PATIENTS AND METHODS

Five patients were treated endovascularly with a stent-graft for an aneurysm (n = 3) or acute dissection (n = 2) of the thoracic aorta via a femoral 24 F sheath. The femoral access site was closed with two suture-mediated closure devices after placement of the stent-graft.

RESULTS

The aneurysm or the false lumen was excluded from perfusion by the placement of the stent-graft in all patients. Hemostasis at the femoral access site was successful in all patients with the percutaneous suture device. A minor stenosis of the femoral artery was found angiographically in four patients after suture-mediated closure. Besides a reversible renal failure due to the medically induced hypotension for the treatment of an acutely ruptured aneurysm, no complications resulted from the stent-graft placement or the percutaneous suture.

CONCLUSION

The percutaneous transfemoral placement of stent-grafts in the thoracic aorta using a suture-mediated closure of the access site is technically feasible. Long-term results of the technique have to be awaited.

Spinal metastases from renal cell carcinoma: effect of preoperative particle embolization on intraoperative blood loss

BACKGROUND AND PURPOSE

Surgical repair of spinal metastases from renal origin is often complicated by excessive bleeding. The purpose of this study was to assess the effect of preoperative particulate embolization on intraoperative blood loss.

METHODS

Twenty spinal metastases from renal origin (17 patients) treated by preoperative embolization with polyvinyl alcohol particles were analyzed retrospectively. Surgical decompression was performed within 2 days after embolization. A control group of 10 patients with 11 spinal metastases of renal origin underwent surgery without embolization. The effect of preoperative embolization, of completeness of embolization, and of particle size on the estimated intraoperative blood loss was analyzed using nonparametric statistical tests.

RESULTS

Complete embolization was achieved in 10 cases and partial embolization in the other 10. The estimated blood loss of 19 embolized and 11 control cases was available from the surgical report. Median intraoperative blood loss in 19 embolized lesions was 1500 mL (range, 300-8000 mL), compared with 5000 mL (range, 1440-15000 mL) in the control group. Even after partial embolization, blood loss (median, 2000 mL) was significantly lower than in the control group. No significant differences in estimated blood loss were noted between the use of particles smaller than 250 microm and those larger than 250 microm. No embolization-related permanent neurologic deficit or skin or muscle necrosis occurred.

CONCLUSION

Preoperative embolization of spinal metastases of renal origin with polyvinyl alcohol particles is safe and might reduce intraoperative blood loss significantly. Even partial embolization seems to be effective.

MR imaging-guided stent placement in iliac arterial stenoses: a feasibility study

PURPOSE

To assess the feasibility of magnetic resonance (MR) imaging-guided stent placement in iliac arterial stenoses.

MATERIALS AND METHODS

Thirteen patients with 14 iliac arterial stenoses were examined prospectively. Angioplasty was performed through a femoral sheath by using a conventional 1.5-T MR imaging system. Stents and catheters were visualized on the basis of their artifacts. Nitinol stents were placed with gradient-echo MR imaging guidance. Angioplasty balloons were inflated with gadolinium-based contrast material. Results were evaluated clinically and with both digital subtraction angiography (DSA) and contrast material-enhanced MR angiography.

RESULTS

Ten of 13 patients were treated with technical success by using MR imaging-guided intervention alone. Three patients were treated with additional fluoroscopic guidance, because complications (ie, panic attack, subintimal recanalization, and stent misplacement) occurred with MR guidance. The quality of the postinterventional contrast-enhanced MR angiograms of three of 12 lesions with stents was limited owing to stent-induced signal loss of the lumen. The mean stenosis degree after stent placement was significantly higher at contrast-enhanced MR angiography than at DSA (24.6% vs 6.2%). The mean MR imaging-guided procedure time was 74 minutes.

CONCLUSION

MR imaging-guided stent placement in iliac arteries is feasible in select patients. The presented technique has limitations-that is, long procedure times, lack of real-time monitoring, and stent artifacts-that necessitate further modifications before it can be recommended for clinical use.

[Results after placement of Memotherm stents in iliac and femoral arteries]

PURPOSE

To evaluate the effectivity, safety and midterm patency rates of iliac and femoral stent placement with the Memotherm stent (Bard-Angiomed, Karlsruhe).

MATERIAL AND METHODS

In 41 patients (11 female, 30 male, mean age 63.9 years) 49 lesions were treated with 50 stents. Mean lesion length was 4.8 cm for 5 occlusions and 3.1 cm for 44 stenoses. Lesions were located in the common iliac (n = 31), the external iliac (n = 15), and the common femoral artery (n = 3). Patients were followed-up clinically, with ankle-brachial indices (ABI), and angiography. Angiographic patency rates (< or = 50% restenosis) were calculated using the Kaplan-Meier method, ABIs were compared before and after therapy with the Wilcoxon test.

RESULTS

An immediate technical success was achieved in 48/49 lesions (98%, intention-to-treat). Visibility of the stent was poor. Four stent placement procedures were complicated by an advancement of the stent, which could not be corrected. A thrombosis of one stent during deployment had to be treated surgically. After a mean of 10.4 months (6-24) 33 lesions were followed-up with angiography. The primary angiographic patency rate was determined to be 89.9% after 9 months. An improvement of at least one Fontaine stage was observed in 85.4%. The mean ABI increased significantly from 0.64 to 0.84 after therapy.

CONCLUSIONS

The patency rate of the Memotherm stent is comparable to that of other stent systems. The poor visibility and the advancement of the stent during deployment requires further modifications.

[Percutaneous transpapillary extraction of biliary calculi for symptomatic choledocholithiasisafter unsuccessful endoscopic treatment]

PURPOSE

Evaluation of a percutaneous transhepatic treatment of symptomatic choledocholithiasis in bile ducts that cannot be reached with the endoscope.

METHODS

From January 1996 to August 2000 a transhepatic extraction of biliary calculus was performed in four patients. Endoscopic retrograde cholangiography (ERC) was not successful in any of the cases. Clinical symptoms were icterus in four cases, additional cholangitis or colics in two cases. First, a balloon dilation of the papilla was performed by a percutaneous transhepatic approach. For removal of bile duct stones, occlusion catheters and Dormia baskets were used. Technical success was defined as complete removal of bile duct stones. Clinical success was defined as normalization of cholestasis and inflammation parameters. In the follow-up an ultrasound examination was performed and blood samples were taken for control of cholestasis parameters.

RESULTS

In all four cases treatment was technically and clinically successful. For complete removal of biliary calculus a second intervention was necessary in two cases. In each case an internal to external drainage was left over a mean of 7 days (3-13 days). In the mean follow-up of 30.5 months (6-50 months) all patients had persistent relief of symptoms. No further interventions were necessary. No complications were present.

CONCLUSION

Percutaneous transpapillary extraction of biliary calculus is an effective alternative to surgery in patients with bile ducts, that cannot be reached with the endoscope.

On the heating of linear conductive structures as guide wires and catheters in interventional MRI

The interest in performing vascular interventions under magnetic resonance (MR) guidance has initiated the evaluation of the potential hazard of long conductive wires and catheters. The objective of this work is to present a simple analytical approach to address this concern and to demonstrate the agreement with experimental results. The first hypothesis is that a long conductive structure couples with the electric field of the radio frequency (RF) transmit coil. The second hypothesis is that this coupling induces high voltages near the wire ends. These voltages can cause tissue heating due to induced currents. The experimental results show an increase in coupling when moving a guide wire toward the wall of an RF transmit coil, documented with a temperature increase of a saline solution in close proximity to the tip of the guide wire. The coupling of the wire not only presents a potential hazard to the patient, but also interferes with the visualization of the wire. A safe alternative would be the use of nonconducting guide wires. J. Magn. Reson. Imaging 2001;13:105-114.

[Contrast media-enhanced MR angiography of the lower extremity arteries using a dedicated peripheral vascular coil system. First clinical results]

PURPOSE

To evaluate contrast enhanced magnetic resonance angiography (ceMRA) of the pelvic and peripheral arteries with a dedicated peripheral vascular coil system and automated table-feed technique in patients with arterial occlusive disease.

METHODS

Three-dimensional gadolinium-enhanced MR angiography in a two-step automatic table feed technique was performed in 45 patients using a 1.5 Tesla imager (Magnetom Symphony, Siemens). The pelvic arteries were imaged with a single injection of contrast material. The upper and the lower leg were imaged with a second injection of contrast material in an automated table feed technique using a dedicated vascular coil system. In 20 patients ceMRA was compared with digital subtraction angiography (DSA) as the standard of reference and in 25 patients ceMRA was performed solely.

RESULTS

Sensitivity and specificity for grading significant stenoses > or = 50% and occlusions (in parenthesis) were in the pelvic arteries 94.7%, 96.8%, (100%, 100%), in the arteries of the upper leg 92.3%, 93.3% (87.5%, 100%) and in the arteries of the lower leg 96.5%, 95.8%, (95.2%, 96.8%), respectively. Depiction of the runoff vessels of the lower leg was excellent in ceMRA. CeMRA was of diagnostic quality in all the patients.

CONCLUSION

Contrast-enhanced MRA using a dedicated peripheral vascular coil system increases the diagnostic quality of the lower leg. The runoff vessels can be evaluated. Thus, ceMRA in the presented technique is a diagnostic alternative to arterial angiography.

Morphology and hemodynamics in dissection of the descending aorta. Assessment with MR imaging

PURPOSE

To obtain morphologic and functional information in patients with dissection of the descending aorta using contrast-enhanced MR angiography (MRA) and MR blood flow quantification of the true and false lumina.

MATERIAL AND METHODS

Fourteen patients were studied prospectively using a 1.5 T unit. MRA was performed with a 3D FISP sequence (TR/TE/flip angle 4.7/1.9 ms/30 degrees) after injection of 0.2 mmol Gd-DTPA per kg b.w. Flow quantification with phase velocity mapping was done at the level of the diaphragm using a 2D FLASH technique (TR/TE/flip angle 28/6.5 ms/30 degrees) with an average temporal resolution of 23 frames per cardiac cycle (34 ms). A spectral broadening index was applied to quantify the amount of flow irregularity within both channels of the aorta. Extension of the dissection and involvement of the major branch vessels were analyzed.

RESULTS

The mean flow volume per minute was 1,982 ml (SD 1,083 ml) in the true and 1,052 ml (SD 763 ml) in the false lumen. Average peak-velocities were 98 cm/s (SD 33 cm/s) in the true channel and 47 cm/s (SD 26 cm/s) in the false channel. Ten patients had bidirectional flow in the false lumen with a reflux volume ranging between 6.8% and 98%. Only 1 patient presented with bidirectional flow in the true lumen (reflux volume 15%). A significantly higher degree of flow irregularity was found in the false lumen compared with the true channel.

CONCLUSION

Different hemodynamic patterns were found in aortic dissection. Their prognostic value and the impact on therapy, specifically percutaneous interventional procedures, have to be further studied.

[Therapy of iliac artery lesions with a new premounted balloon-expandable stent ("Flexible Iliac Bridge Stent")]

PURPOSE

Evaluation of the handling, technical success rate and six month patency rate of a new, premounted balloon-expandable stent in iliac artery lesions.

MATERIALS AND METHODS

In a prospective study 26 stenoses and 3 occlusions of the iliac arteries were primary treated in 24 patients (Fontaine IIa-III, mean age 60.4 year) with the "Flexible Iliac Bridge Stent" (Medtronic AVE, Düsseldorf). Five patients had bilateral stenoses. The ankle-brachial index (ABI) in rest and after exercise was determined before the intervention as well as 1-3 days, 1 and 6 months after the Intervention. The handling and visibility of the stent was scored on a three grade scale by the operators. Follow-up angiography including intraarterial pressure measurement was performed in 17 out of 24 patients (21 out of 29 lesions) after 6 months.

RESULTS

All 29 lesions were treated with technical success by implantation of 36 stents. The mean degree of the stenoses before intervention was 72.7 +/- 13.8% (+/- 1 standard deviation) and less than 5% in all cases postinterventionally. The mean pressure gradient before and after stent placement was 21 +/- 13.1 mm Hg and 0.8 +/- 2.3 mm Hg, respectively. The Fontaine stage improved by at least one in all patients. The mean ABI at rest improved from 0.63 +/- 0.15 to 0.89 +/- 0.16, and after exercise from 0.46 +/- 0.17 to 0.8 +/- 0.2, respectively. At 6 months 2 lesions out of 21 (9.5%) showed a restenosis of 55% and 70% with an intraarterial pressure gradient of 16 mm Hg and 27 mm Hg, respectively. After 6 months the mean ABI at rest decreased to 0.83 +/- 0.13, and to 0.72 +/- 0.14 after exercise. Handling and visibility was scored as good by all operators.

CONCLUSION

Endoluminal therapy of iliac artery lesions with the used stent is safe and effective. The six month patency rate is comparable to the published data of other stents.

Stent appearance at contrast-enhanced MR angiography: in vitro examination with 14 stents

PURPOSE

To evaluate signal intensity changes influencing assessment of stent patency at contrast material-enhanced magnetic resonance (MR) angiography.

MATERIALS AND METHODS

By using an in vitro model, 14 stents-nine nitinol, one tantalum, two stainless steel, and two cobalt alloy-were investigated regarding their appearance at MR imaging. A vascular phantom consisting of tubes filled with 2.00 mmol/L gadopentetate dimeglumine in saline solution was studied in different orientations within the magnetic field. Imaging was performed with a fast three-dimensional gradient-echo sequence (4. 70/1.89 [repetition time msec/echo time msec]). Relative signal intensity reduction within the stents and the degree of artificial narrowing of the stent lumen were calculated.

RESULTS

The stent lumen was visible within 13 stents. A total signal void inside the stent lumen appeared in only one cobalt alloy stent. Artificial narrowing of the diameter was less than 33% in 10 of 14 stents. The tantalum stent and four nitinol stents seemed best suited for contrast-enhanced MR angiography. A bandlike artifact occurred at the ends of the stents when positioned along the readout direction.

CONCLUSION

To differentiate between artifacts and stenoses, knowledge of the degree of signal intensity reduction and artificial lumen narrowing within vascular stents is essential. Stent geometry, relative orientation to the magnetic field, and alloy composition influence signal intensity alteration within the stent lumen.

[Carotid endarterectomy and carotid stenting. A pilot study of a prospective, randomized and controlled comparison]

INTRODUCTION

A prospective, randomized and controlled trial is conducted to compare carotid endarterectomy and carotid stenting in high grade symptomatic carotid artery stenoses.

METHODS

According to the study design symptomatic patients with a angiographically high-grade (> or = 70%) internal carotid artery stenosis are included. Pre- and postinterventional diagnostics during the hospitalization period includes neurological assessment, duplex sonography of the cervical and cerebral arteries and magnetic resonance imaging of the brain. Follow-up examinations are scheduled after 1, 6 and 12 months and consist of a neurological assessment and duplex sonography. After 12 months selective angiography and magnetic resonance imaging of the brain will be performed additionally. During a period of 9 months up to now 23/137 patients treated for a carotid artery stenosis were included in the study, 11 patients underwent surgery and 12 patients carotid stenting.

RESULTS

Carotid stenting and endarterectomy was primarily successful without residual stenosis > 30% in each patient without the occurrence of stroke or death. In 18 follow-up examinations (neurological assessment including duplex sonography) of 13 patients (13 follow-up examinations after 30 days, 5 after 6 months) no relevant restenosis and no stroke occurred.

CONCLUSION

As of yet, carotid stenting was a safe procedure. Due to the small number of patients a definitive conclusion can not be drawn.

Digital radiography of the skeleton using a large-area detector based on amorphous silicon technology: image quality and potential for dose reduction in comparison with screen-film radiography

AIM

The purpose of this study was to evaluate a large-area, flat-panel X-ray detector (FD), based on caesium-iodide (CsI) and amorphous silicon (a-Si) with respect to skeletal radiography. Conventional images were compared with digital radiographs using identical and reduced radiation doses.

MATERIALS AND METHODS

Thirty consecutive patients were studied prospectively using conventional screen-film radiography (SFR; detector dose 2.5 microGy). Digital images were taken from the same patients with detector doses of 2.5, 1.25 and 0.625 microGy, respectively. The active-matrix detector had a panel size of 43 x 43 cm, a matrix of 3 x 3K, and a pixel size of 143 microm. All hard copies were presented in a random order to eight independent observers, who rated image quality according to subjective quality criteria. Results were assessed for significance using the Student's t -test (confidence level 95%).

RESULTS

A statistically significant preference for digital over conventional images was revealed for all quality criteria, except for over-exposure (detector dose 2.5 microGy). Digital images with a 50% dose showed a small, statistically not significant, inferiority compared with SFR. The FD-technique was significantly inferior to SFR at 75% dose reduction regarding bone cortex and trabecula, contrast and overall impression. No statistically significant differences were found with regard to over- and under-exposure and soft tissue presentation.

CONCLUSION

Amorphous silicon-based digital radiography yields good image quality. The potential for dose reduction depends on the clinical query.

Chest radiography with a large-area detector based on cesium-iodide/amorphous-silicon technology: image quality and dose requirement in comparison with an asymmetric screen-film system

The purpose of this study was to evaluate a large-area, flat-panel X-ray detector, which uses cesium-iodide (CsI) and amorphous silicon (a-Si). Conventional images were compared with digital images acquired with equal dose (2.5 microGy) and with 50% dose reduction. Fifteen consecutive patients were studied prospectively using an asymmetric screen-film system (detector dose, 2.5 microGy). Digital images were taken from the same patients in a posteroanterior view with detector doses of 2.5 and 1.25 microGy, respectively. The CsI/a-Si active-matrix imager had a panel-size of 43 x 43 cm, a matrix of 3 x 3k, and a pixel-pitch of 143 microm. Hard copies were presented in a random order to eight independent observers, who rated image quality according to six subjective quality criteria. Statistical significance of differences was evaluated with Student's t test for paired samples (confidence level, 95%). Digital radiographs with 2.5 and 1.25 microGy were superior to conventional images regarding all quality criteria. Statistically significant differences were observed for five of six criteria at a detector dose of 2.5 microGy and for only one quality feature at 1.25 microGy. Flat-panel digital imagers based on CsI/a-Si technique have the potential to replace conventional systems and might allow a reduction of radiation dose by 50% without loss of image quality.

Magnetic resonance monitoring of stent deployment: in vitro evaluation of different stent designs and stent delivery systems

RATIONALE AND OBJECTIVES

To evaluate MR imaging features of commercially available stents before, during, and after in vitro deployment as a step toward MR-guided stent deployment.

METHODS

Fourteen stents were deployed in a phantom under MR monitoring at 1.5 T by using a gradient-echo sequence. Device visibility was rated on a four-point scale (excellent, fair, poor, not visible).

RESULTS

The Memotherm stent and the rolling membrane (RM) Wallstent showed excellent stent visibility and at least fair scores for artifact-induced narrowing of the stent lumen. Three stents (Palmaz, AVE, Easy Wallstent) showed excellent visibility of the stent but no visible lumen. Five stents (Strecker, Accuflex, Hemobahn, Passager, Sinus) displayed fair visibility. The delivery catheters of four stent systems (Smart, Vascucoil, Symphony, ZA) displayed severe black hole artifacts.

CONCLUSIONS

The imaging features of several stent systems might be suitable for MR-guided intervention. The Memotherm and the Wallstent RM combine good visibility of the stent and the lumen.

Time-resolved contrast-enhanced MR angiography of renal artery stenosis: diagnostic accuracy and interobserver variability

OBJECTIVE

The purpose of this study was to evaluate diagnostic accuracy and interobserver variability of time-resolved three-dimensional gadolinium-enhanced MR angiography in the detection of renal artery stenosis in comparison with intraarterial digital subtraction angiography as the standard of reference.

SUBJECTS AND METHODS

Forty consecutive patients (age range, 25-81 years; mean, 62.9 +/- 11.9 years) with suspected renal artery stenosis underwent intraarterial digital subtraction angiography and gadolinium-enhanced MR angiography, performed on a 1.5-T system with fast low-angle shot three-dimensional imaging (3.8/1.49 [TR/TE], 25 degrees flip angle, 10-sec acquisition time, and 1.5-mm partition thickness). Three time-resolved phases were obtained in a single breath-hold. Digital subtraction angiography and gadolinium-enhanced MR angiography were evaluated by four observers who studied 80 main renal arteries and 19 accessory vessels to evaluate the degree of stenosis. A stenosis reducing the intraarterial diameter by more than 50% was regarded as hemodynamically significant. Interobserver variability was calculated.

RESULTS

Only one gadolinium-enhanced MR angiography study was not of diagnostic quality, as a result of failure of the power injector. All main branches were of diagnostic quality in 38 (97.4%) of the remaining 39 gadolinium-enhanced MR angiography studies. Seventeen (89.5%) of 19 accessory renal arteries were depicted with gadolinium-enhanced MR angiography. The overall sensitivity for significant stenoses was 92.9%. The overall specificity was 83.4%, and the overall accuracy was 85.9%. Interobserver variability of gadolinium-enhanced MR angiography exceeded that of digital subtraction angiography.

CONCLUSION

Time-resolved three-dimensional gadolinium-enhanced MR angiography is a useful noninvasive method of screening suspected renal artery stenosis because of its easy application, short examination time, and high sensitivity despite of its higher interobserver variability.

[Stent angioplasty of pelvic artery stenosis with MRI control: initial clinical results]

PURPOSE

To investigate the feasibility of MR-guided stent angioplasty of iliac artery stenoses under passive visualization.

MATERIAL AND METHODS

Three patients with short, concentric stenoses of the iliac arteries were enrolled. The vascular interventions were performed on a 1.5 T MR scanner (Magnetom Symphony, Siemens, Erlangen, Germany). Stents, guidewires, and balloon catheters were visualized on the basis of susceptibility artifacts. Contrast-enhanced MR angiography (ceMRA) was used to localized the stenosis prior to stent deployment. Nitinol stents were placed under MR-guidance using a fast 2D gradient echo technique. Balloon dilatiation was performed with an angioplasty catheter inflated with diluted gadolinium-DTPA. Postinterventional results were evaluated by ceMRA, DSA, and Doppler indices.

RESULTS

Position of the stent, stent deployment, and balloon dilatation were depicted by MR. All stents were correctly placed within the stenosis. Stent positions as monitored by MRI were identical to those seen on DSA images. All patients were treated successfully by the MR-guided intervention.

CONCLUSION

An MR-guided stent angioplasty of simple iliac artery stenosis is feasible under passive visualization.

[Contrast medium-enhanced MR angiography of the pelvic and leg vessels with an automated table-feed technique]

PURPOSE

To evaluate contrast enhanced magnetic resonance angiography (ceMRA) with an automated table-feed technique in patients with arterio-occlusive disease for imaging of the pelvic and peripheral arteries.

METHODS

Twenty-two patients underwent three-dimensional gadolinium-enhanced MR angiography in a three-step automatic table-feed technique on a Magnetom Symphony operating at 1.5 Tesla. Maximum intensity projection images (MIP) were generated from the subtracted and original studies. Image quality and venous contrast were evaluated by two groups of observers. 304 vessels (17 patients) were compared with DSA as the standard of reference.

RESULTS

All examinations were performed without any technical problems. Diagnostic quality of the MIP of subtracted data sets was superior to that of the unsubtracted images. Venous overlay was 61% in the lower leg. In a total of 599 observations, a sensitivity of 96% (95%, 82%) and a specificity of 87% (88%, 99%) were high compared to DSA in the detection of significant stenoses > or = 50% (> or = 75%, occlusions). Interobserver correlation was good (linear correlation 0.9).

CONCLUSION

Stepping-table digital subtraction contrast enhanced MRA is a promising technique in the diagnosis of peripheral arterio-occlusive disease.

Post-traumatic pseudocyst of the spleen: sclerotherapy with ethanol

We report a case of successful percutaneous treatment of a chronic post-traumatic splenic pseudocyst using alcohol as the sclerosing agent. A 26-year-old man presented with a symptomatic cystic mass located in the spleen. Aspiration of 300 ml of fluid was only temporarily effective, and therefore a drainage catheter was placed 3 days later. After histopathologic and microbiologic exclusion of a malignant or infectious origin, local sclerotherapy with alcohol was performed because of recurrence after percutaneous drainage. This therapy was repeated six times within 2 weeks. Two weeks later, the remaining volume was determined to be 16 ml. Six months after treatment the cyst was no longer visible. To our knowledge this is the first case of a chronic post-traumatic splenic cyst treated with alcohol. Percutaneous sclerotherapy of a symptomatic post-traumatic splenic pseudocyst may be an alternative to surgical treatment.

[Transfemoral pelvic vein angiography with CO2: experiences with pressure- and volume-controlled injections]

PURPOSE

To evaluate the efficacy of CO2 in aortobifemoral DSA with a pressure- and volume-controlled injector.

MATERIALS AND METHODS

In an intraindividual prospective study, 42 patients with arterial occlusive disease underwent stepwise aortobifemoral DSA with CO2 and with iopromid 300.

RESULTS

With Co2, diagnostic images were obtained in 74% of the iliac, 98% of the femoral, 89% of the popliteal arteries, but in only 36% of the arteries of the lower leg. 73% of the stenoses were correctly identified. With therapeutic relevance 8% of the stenoses were overestimated. The length of 1 of 53 occlusions was overestimated and 3 occlusions were simulated. No stenoses or occlusion was missed. There were no severe side-effects. The injector proved to be safe and easy to handle. Fragmentation of the CO2 bolus could be compensated by postprocessing with a minimum opacification summation mode.

CONCLUSIONS

With the equipment used, CO2 was a safe alternative to iodinated CM in routine stepwise aortobifemoral DSA of the iliac, femoral, and popliteal arteries. Because of the risk of overestimation, occlusions and high grade stenoses should be verified with selective injections or iodinated CM before PTA or operations.

Temporary Strecker stent for management of acute dissection in popliteal and crural arteries

Stent placement is a widely used bail-out treatment for dissection of peripheral arteries. Below the level of the superficial femoral artery permanent stenting is complicated by a high incidence of subacute thrombosis and restenosis. We present two cases of arterial occlusion due to acute iatrogenic dissection of the popliteal and distal fibular arteries. Successful treatment was achieved with a new bail-out procedure. Strecker stents were implanted to seal off the dissection flap. Stents were retrieved easily after 24 hr using a myocardial biopsy forceps. After stent retrieval the temporarily stented segments were patent and showed a larger lumen compared with segments treated by balloon dilatation alone. Temporary stenting is a simple and safe procedure and offers the advantage of tacking up dissection membranes and preventing recoil. Persistent presence of a metallic implant as a source of continued injury and stimulus for intimal proliferation is avoided.

[Ischemic complications in aortic dissection--percutaneous treatment with balloon fenestration and stent implantation]

PURPOSE

To describe principles and results of percutaneous treatment of ischemic complications of aortic dissection.

MATERIALS AND METHODS

In five cases (four patients) aortic dissection was clinically complicated by renal (n = 4), iliofemoral (n = 2) or mesenterial ischemia (n = 1). After evaluation by means of computed tomography, angiography, and manometry, treatment consisted of balloon fenestration of the intimal flap, stent placement or both.

RESULTS

Eleven of 25 vascular beds were classified as ischemic. Treatment consisted of 11 balloon fenestration procedures in 3 patients, in one case supported by stent placement across the dissection membrane. Stents were placed in five renal arteries, one stent was placed in the true lumen of the aorta. One iliac artery was treated with balloon dilatation. One renal artery dissection became symptomatic after balloon fenestration and was treated successfully by stent placement. In all cases ischemia was resolved by endovascular treatment. All patients had persistent relief of symptoms. Mean follow-up time is 5.8 months.

CONCLUSION

Ischemic complications of aortic dissection can be effectively and safely treated with stent placement and balloon fenestration.

[Percutaneous abscess drainage in Crohn disease]

PURPOSE

To evaluate the success of percutaneous, CT-guided abscess drainage (PAD) in patients with Crohn's disease.

METHODS

Within the last 5 years 8 patients with Crohn's disease were treated by PAD for intra-abdominal abscesses. A fistula was determined to be the cause in 4 patients. The abscesses arose spontaneously in 7 patients while one patient had a postoperative abscess. We used single lumen 10 F- and double lumen 12 F- and 14 F-catheters for drainage (duration of drainage 8-20 days).

RESULTS

In all cases the abscess was successfully drained by PAD. However, an operation-free interval of at least three months was achieved in only two patients. A healing of the fistula was not attained in any of the 4 patients with a proven fistula. No enterocutaneous fistulas arose within the course of PAD.

CONCLUSIONS

PAD is also useful for patients with Crohn's disease since it improves the starting situation for the necessary operative interventions. In most cases (especially with enterogenic fistulas), however, a long-lasting therapeutic result cannot be expected.

Ischiogluteal bursitis mimicking soft-tissue metastasis from a renal cell carcinoma

We report a case of ischiogluteal bursitis mimicking a soft-tissue metastasis from a renal cell carcinoma. A 66-year-old woman suffered from pain over the left buttock 6 months after she was operated on for renal cell carcinoma of the left kidney. CT of the abdomen and pelvis revealed a tumor-like lesion adjacent to the left os ischii, which was suspected to be a soft-tissue metastasis. Percutaneous biopsy revealed no evidence of malignancy, but the histopathological diagnosis of chronic bursitis.

[Radiologic implantation of central venous portal systems in the forearm]

PURPOSE

To assess the safety and effectiveness of fluoroscopic guided brachial implanted central-venous miniport systems.

PATIENTS AND METHODS

In 32 oncological patients a central-venous miniport system (Vital-Port, CPC-Cook) was implanted in the forearm. The group included 15 women and 17 men (range 33-78, mean 56 years).

RESULTS

Technical success was 100%, in 6 patients vasospasm produced difficulties in catheter placement. In a total of 2878 patients days (range 3-445, mean 90 days) 5 complications occurred (15.6%, 1.7 on 1,000 catheterdays): In one patient (3.13%, 0.35/ 1000 d) the system was changed due to leakage of the catheter near the chamber. Four patients had minor complications: in one case excision of a suture line granuloma was necessary, one haematoma at the site of the chamber was treated with dressing, one patient had a wound dehiscence and one occluded catheter returned to patency by flushing the system with contrast material. Venous thrombosis, phlebitis, catheter dislocation, paravasation or system-related infection did not occur.

CONCLUSION

Fluoroscopic guided peripheral central-venous port implantation is a safe and easy procedure with a high success rate and a low complication rate which can be performed in an outpatient setting.

Clinical application of a flat-panel X-ray detector based on amorphous silicon technology: image quality and potential for radiation dose reduction in skeletal radiography

OBJECTIVE

The purpose of this study was to compare images obtained with a self-scanning, flat-panel X-ray detector based on amorphous silicon technology with conventional screen-film radiographs and to evaluate the possibility of radiation dose reduction in skeletal radiography.

SUBJECTS AND METHODS

One hundred twenty patients were examined prospectively using a conventional screen-film system (speed, 400; detector dose, 2.5 microGy) and a prototype digital amorphous silicon detector (simulated speed, 400 and 800, n = 120; simulated speed, 1600, n = 40). The resulting 400 images were evaluated independently by six radiologists using a subjective five-point preference scale that rated overexposure, underexposure, contrast resolution, spatial resolution, and soft-tissue presentation. Image quality was ranked on a scale from 0 to 10 according to subjective criteria. Statistical significance of differences was determined using Student's t test and confidence intervals (95% confidence level).

RESULTS

Comparison of conventional radiographs with digital images revealed a statistically significant preference for the digital system for soft-tissue presentation (speed 400 and 800) and visualization of osteoarthrotic changes (speed 400). A small but statistically significant preference for conventional images was found with respect to contrast and spatial resolution when digital speed was 800 or 1600; and the visibility of arthrosis at digital speed 1600, osteolysis at digital speed 800 and 1600, and fractures at digital speed 1600.

CONCLUSION

The amorphous silicon-based system with a simulated speed of 400 provided images equivalent to screen-film radiographs. For clinical tasks such as routine follow-up studies, assessment of instability, or orthopedic measurements, a radiation dose reduction of up to 75% may be possible.

[Computer tomography-guided gastrostomy, jejunostomy and gastrojejunostomy. A reliable non-surgical method also for contraindications and failure of percutaneous endoscopic gastrostomy]

OBJECTIVE

To analyse retrospectively the results of CT (computed tomography)-guided gastrostomy or gastroenterostomy where an endoscopic procedure was not possible or had failed.

PATIENTS AND METHODS

Between August 1993 and March 1997, CT-guided gastrostomy (n = 50) or gastroenterostomy (n = 8) was performed in 58 patients (mean age 56 +/- 6 years; 51 males, 7 females). An endoscopic or fluoroscopic method had been contraindicated in 52 and had failed in 6 patients.

RESULTS

Technical success was achieved in all patients. Three patients needed intravenous sedation. There were no procedure related complications requiring treatment. Three patients had a mild infection at the site of the skin puncture.

CONCLUSION

CT-guided gastrostomy or gastroenterostomy is a safe and simple procedure which provides a minimally invasive alternative also in patients with contraindications to the established percutaneous method.

Flat-panel x-ray detector using amorphous silicon technology. Reduced radiation dose for the detection of foreign bodies

RATIONALE AND OBJECTIVES

The authors evaluate a new flat-panel x-ray detector (FD) with respect to foreign body detection and reduction of radiation dose compared with screen-film radiography.

METHODS

Flat-panel x-ray detector is based on amorphous silicon technology and uses a 1 k x 1 k photo-detector matrix with a pixel size of 143 x 143 microns and 12-bit digital output. A thallium-dotted cesium iodide scintillation layer converts x-rays into light. An ex vivo experimental model was used to determine the detectability of foreign bodies. Foreign bodies with varying sizes were examined: glass with and without addition of lead, bone, aluminium, iron, copper, gravel fragments, and graphite. Four hundred observation fields were examined using conventional radiography (speed, 400; system dose: 2.5 microGy) as well as FD with a simulated speed of 400, 800, 1200, and 1600, corresponding to a detector dose of 2.5 microGy, 1.25 microGy, 0.87 microGy, and 0.625 microGy, respectively. Four independent radiologists performed receiver operating characteristic analysis of 8000 observations.

RESULTS

Flat-panel x-ray detector with a simulated speed of 400 was significantly superior (P = 0.012) to screen-film radiography (speed, 400). At a simulated speed of 800 and 1200 FD yielded results equivalent to screen-film radiography. Flat-panel x-ray detector was significantly inferior to screen-film radiography at a simulated speed of 1600 (P = 0.012).

CONCLUSIONS

Flat-panel x-ray detector technology allows significant reduction in radiation dose compared with screen-film radiography without loss of diagnostic accuracy.

Identification of the valine 408 to methionine mutation in the LDL receptor in a Greek patient with homozygous familial hypercholesterolemia

We have identified the cytosine to thymine change in the codon for amino acid 408 which causes valine to be replaced by methionine in exon 9 of the LDL receptor gene in a 12-year-old Greek boy living in Germany, with homozygous familial hypercholesterolemia, by using polymerase chain reaction-amplified genomic DNA and subsequent restriction digestion. Homozygosity was confirmed by direct DNA sequencing. The mutation was present in both his parents, and his brother, grandmother, uncle and cousin. Six restriction fragment length polymorphisms of the LDL receptor gene were used to determine the haplotype of the defective allele. The haplotype was different from the one reported earlier in African Afrikaners and from Holland. We conclude that the mutation in the Greek boy probably occurred as an independent mutation. Because the parents are from different areas in Greece, this mutation may be common in Greeks.

The effect of the apolipoprotein E polymorphism on lipid levels in patients with familial defective apolipoprotein B-100

Serum lipid concentrations of patients with familial defective apolipoprotein B-100 (FDB) show a high interindividual variability although the underlying defect is caused by a single point mutation. On the other hand, several genetic factors modulating serum cholesterol levels are known, such as DNA polymorphisms of the apolipoprotein B or the apolipoprotein E (apo E) gene. To assess the effect of the apo E polymorphism on serum cholesterol, lipid levels of FDB patients (n = 36) were compared with those of a normolipidemic control group (n = 272) according to their apo E genotype. For the FDB group mean values of low-density lipoprotein (LDL) cholesterol (mg/dl) were 225.7 +/- 53.7 for E3/2 genotype (n = 3), 234.2 +/- 48.3 for E3/3 genotype (n = 20), and 252.4 +/- 73.8 for E4/3 genotype (n = 13). Means of triglycerides (mg/dl) were 121.0 +/- 21.2, 114.8 +/- 60.7, and 110.0 +/- 62.8 for the respective apo E genotypes. The calculated average effect of the apo E alleles on LDL cholesterol levels was -6.0% for allele e2 and +3.7% for e4 relative to the whole FDB group. The effect on triglyceride levels was +7.5% for e2 and -3.6% for e4. The control group showed a similar variation in LDL cholesterol depending on the different apo E genotypes. About 6% of the total variation in LDL cholesterol can be accounted for by the apo E locus in normolipidemic and hypercholesterolemic individuals alike.