[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.

Treatment of infrapopliteal occlusive disease by high-speed rotational atherectomy: initial and mid-term results

PURPOSE

To assess the effectiveness and patency rates of high-speed rotational atherectomy (HSRA) for the treatment of infrapopliteal arterial occlusive disease.

MATERIAL AND METHODS

During an 18-month period, a total of 19 infrapopliteal lesions in 15 consecutive patients were treated primarily by HSRA with use of the Rotablator device. Patients were followed up with documentation of clinical symptoms, standardized treadmill exercise, and Doppler sonography at 1, 3, and 6 months. Control angiography was performed 6 months after primary treatment.

RESULTS

HSRA was initially successful in 14 of 15 patients, yielding an initial technical success rate of 94%. Percutaneous treatment induced an improvement of the ankle-brachial index (ABI) from 0.6 +/- 0.09 to 0.86 +/- 0.2 after intervention (P < .0001). Doppler analysis showed a mean ABI of 0.85 +/- 0.2 (P < .001) at 1 month, 0.72 +/- 0.2 (P = .012) at 3 months, and 0.7 +/- 0.2 (P = .08) at 6 months after initial therapy. Although six patients were lost to follow-up at various times, control angiography at 6 months was carried out in nine of 15 patients, allowing direct assessment of 12 of 19 treated lesions. Among six high-grade restenoses and five total occlusions in the treated vascular segments, only one arterial lumen (of 12) remained patent without presenting a hemodynamically relevant restenosis. These results led to termination of the study.

CONCLUSION

Although HSRA for the treatment of infrapopliteal occlusive disease yields a very high initial technical success rate, mid-term results are extremely poor. Therefore, HSRA cannot be recommended for primary treatment of this type of lesion.

[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.

Aspartyl beta -hydroxylase (Asph) and an evolutionarily conserved isoform of Asph missing the catalytic domain share exons with junctin

The mouse aspartyl beta-hydroxylase gene (Asph, BAH) has been cloned and characterized. The mouse BAH gene spans 200 kilobase pairs of genomic DNA and contains 24 exons. Of three major BAH-related transcripts, the two largest (6,629 and 4,419 base pairs) encode full-length protein and differ only in the use of alternative polyadenylation signals. The smallest BAH-related transcript (2,789 base pairs) uses an alternative 3' terminal exon, resulting in a protein lacking a catalytic domain. Evolutionary conservation of this noncatalytic isoform of BAH (humbug) is demonstrated in mouse, man, and Drosophila. Monoclonal antibody reagents were generated, epitope-mapped, and used to definitively correlate RNA bands on Northern blots with protein species on Western blots. The gene for mouse junctin, a calsequestrin-binding protein, was cloned and characterized and shown to be encoded from the same locus. When expressed in heart tissue, BAH/humbug preferably use the first exon and often the fourth exon of junctin while preserving the reading frame. Thus, three individual genes share common exons and open reading frames and use separate promoters to achieve differential expression, splicing, and function in a variety of tissues. This unusual form of exon sharing suggests that the functions of junctin, BAH, and humbug may be linked.

[Contrast media-enhanced 3D MR angiography before endovascular treatment of aneurysm in the abdominal aorta, iliac artery and peripheral vessels]

PURPOSE

The value of DSA for the measurement of aortic and peripheral arterial aneurysm dimensions before endovascular treatment is limited by projection effects. It was evaluated if additional gadolinium-enhanced three-dimensional MR angiography (3D-CEMRA) could compensate for the disadvantages of DSA.

MATERIALS AND METHODS

21 patients with 35 aneurysms in the abdominal aorta (14), iliac (9) and femoropopliteal vessels (12) were assessed with DSA (7 with calibrated catheter, 14 with yardstick) and 3D-CEMRA (TR/TE 7.8/2.1 ms, flip-angle 40 degrees, Matrix 512 x 224, FOV 500 mm, eff. slice 1.8 mm). We measured and compared aneurysm dimensions on both modalities. 3D-CEMRA was regarded as the reference method to evaluate the dimension of DSA-projection effects.

RESULTS

Diameter and length of aneurysms were underestimated on DSA with the yardstick as reference. The deviation ranged from 15% (+/- 5%) in the aorta to 21% (+/- 10%) in the iliac vessels. Only with calibrated catheters as reference (7/21 DSA), were the distances on DSA correlated well with MRA. In 2/35 aneurysms 3D-CEMRA detected thrombosis with difference between length of inner lumen dilatation on DSA and whole aneurysm length. 2/5 accessory renal arteries found on DSA were not detected on 3D-CEMRA.

CONCLUSIONS

3D-CEMRA is a valuable adjunct to DSA for pre-interventional diagnostics of aortic and peripheral arterial aneurysms. It provides exact evaluation of aneurysm dimensions and information about partial thrombosis.

[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.

[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.

Assembly of U7 small nuclear ribonucleoprotein particle and histone RNA 3' processing in Xenopus egg extracts

In animals, replication-dependent histone genes are expressed in dividing somatic cells during S phase to maintain chromatin condensation. Histone mRNA 3'-end formation is an essential regulatory step producing an mRNA with a hairpin structure at the 3'-end. This requires the interaction of the U7 small nuclear ribonucleoprotein particle (snRNP) with a purine-rich spacer element and of the hairpin-binding protein with the hairpin element, respectively, in the 3'-untranslated region of histone RNA. Here, we demonstrate that bona fide histone RNA 3' processing takes place in Xenopus egg extracts in a reaction dependent on the addition of synthetic U7 RNA that is assembled into a ribonucleoprotein particle by protein components available in the extract. In addition to reconstituted U7 snRNP, Xenopus hairpin-binding protein SLBP1 is necessary for efficient processing. Histone RNA 3' processing is not affected by addition of non-destructible cyclin B, which drives the egg extract into M phase, but SLBP1 is phosphorylated in this extract. SPH-1, the Xenopus homologue of human p80-coilin found in coiled bodies, is associated with U7 snRNPs. However, this does not depend on the U7 RNA being able to process histone RNA and also occurs with U1 snRNPs; therefore, association of SPH1 cannot be considered as a hallmark of a functional U7 snRNP.

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.

[Digital subtraction angiography of the extremities using step-translation technique]

PURPOSE

To evaluate, how routine application of i.a. DSA with the step-translation technique using a single contrast bolus can effectively reduce radiation exposure and the amount of contrast media in comparison to standard peripheral DSA.

METHOD/MATERIALS

100 patients with peripheral arterial occlusive disease were assessed with step-translation DSA, 100 with standard DSA using the same equipment. Imaging quality was rated two observers, judgement by consensus. Comparison of the technical data (radiation dose, contrast media) was based on pairs of patients with similar constellations of stenoses to reduce selection bias.

RESULTS

Step-translation DSA was of high imaging quality from the iliac vessels to the popliteal artery. In the distal leg, imaging was often impaired by effects like unilaterally delayed contrast flow due to high grade stenosis or motion artifacts. 53% of the step translation DSA required 1 or 2, 29% more than two additional DSA runs. Including the additional runs, the average radiation exposure and the amount of contrast media (2434 cGycm2/128 ml) were comparable to those of standard DSA (2461 cGycm2/144 ml).

CONCLUSIONS

Step-translation DSA provides high quality images. In routine application realization of the advantages over standard DSA such as reduction of examination times, radiation exposure and amounts of contrast media may be impaired by poorly collateralized stenoses or motion artifacts demanding additional series.

[Volume-artifact reduction technique by spiral CT in the anterior, middle and posterior cranial fossae. Comparison with conventional cranial CT]

PURPOSE

The object of this study was to determine the extent to which a new volume-artifact reduction (VAR) modality using helical CT was able to reduce artifacts in the anterior, middle and posterior fossae in comparison with conventional CT (sequential mode).

METHODS

In a prospective, randomized trial, 50 patients underwent helical CT (VAR) and 50 underwent sequential CT. The results were evaluated by three radiologists; influences on image quality where scaled between 1 (no artifact) and 4 (not assessable). Eight regions of the anterior, middle and posterior fossae were evaluated.

RESULTS

On average, artifacts were scaled at 2.5 in helical CT (VAR) and 3.1 in conventional CT. Significant differences were seen at the eyeball, anterior to the petrosal bone, at the internal occipital crest, and at the level of the transverse sinus (p < 0.005).

CONCLUSIONS

Helical CT with the VAR modality is superior to conventional, sequential CT in the area of the anterior, middle and posterior fossae.

[CT-guided biopsies, drainage and and percutaneous gastrostomies: comparison of punctures with and without CT fluoroscopy]

PURPOSE

The purpose of this prospective and randomized study was to compare two CT guidance techniques (CT-fluoroscopy/conventional CT) on percutaneous biopsies, drainages and gastrostomies.

MATERIAL AND METHODS

78 CT-guided interventions (29 biopsies, 38 drainages, 8 gastrostomies) were recorded and the Mann-Whitney U-test was applied. In 3 cases both guidance techniques were used. Procedure times, yields and radiation doses were analyzed.

RESULTS

All 38 drainages and all 8 gastrostomies were successfully applied. 13 biopsies with conventional CT guidance (n = 15) and 13 biopsies with CT-fluoroscopy (n = 14) showed a representative histopathologic result. The procedure times were not significantly different (drainages: p = 0.658, biopsies: p = 0.431, gastrostomies: p > 0.06). The radiation doses (CTID1) of the biopsies and drainages showed significantly higher values (drainages p < 0.001, biopsies p < 0.001) with CT-fluoroscopy than with conventional CT. There were no significant differences in gastrostomy procedures (p > 0.06).

CONCLUSION

Procedure times and yields were not improved by using CT-fluoroscopy. Radiation doses showed significantly higher values with CT-fluoroscopy than with conventional CT guidance. CT-fluoroscopy was advantageous in non-compliant patients over conventional CT guidance.

[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.

[Rotational digital subtraction angiography of carotid bifurcation stenosis]

PURPOSE

A prospective study was designed to evaluate, whether multiplanar imaging with rotational digital subtraction angiography (R-DSA) could improve assessment of carotid artery bifurcation stenosis.

PATIENTS AND METHODS

45 patients with suspected stenosis of the ICA were examined with DSA in standard projections (0 degree-(45 degrees)-90 degrees) and additional R-DSA of each ICA from 0-90 degrees in 10 degrees steps. We compared imaging quality and degree of stenosis as well as exposure of the patients to radiation and contrast media.

RESULTS

79/82 R-DSA (96%) were suitable for evaluation of stenosis, 58/82 (70%) matched the quality standard of single projection DSA. Specificity and sensitivity of the R-DSA to diagnose high grade ACI stenosis were 100% and 94%, respectively. 7/79 R-DSA revealed a higher and 3/79 a lower degree of stenosis than the corresponding DSA. Regarding the degree of stenosis there was no significant difference between the two modalities (p > 0.05), but R-DSA detected 4 stenoses greater than 60% that were estimated to be lower than 60% by DSA. Radiation dose for R-DSA was equivalent to one DSA run (170 cGycm2). The average amount of contrast media (25 ml) was slightly higher than for 2-3 single-projection DSA (19.8 ml).

CONCLUSIONS

R-DSA provides high quality imaging of the carotid bifurcation with multiplanar projections facilitating exact grading of vessel stenosis. The number of cases (n = 2) is to small to judge the value of R-DSA as to (tandem-) stenosis of the distal ICA. Still, diagnostic value and low radiation exposure justify the use of R-DSA as additional series to standard protocols.

Iliofemoral arterial occlusive disease: contrast-enhanced MR angiography for preinterventional evaluation and follow-up after stent placement

PURPOSE

To evaluate the efficacy of contrast material-enhanced magnetic resonance (MR) angiography for the diagnosis of peripheral arterial occlusion and follow-up after stent placement.

MATERIALS AND METHODS

Sixty-seven patients (21 women, 46 men; mean age, 64.6 years) were examined. Digital subtraction angiography and contrast-enhanced MR angiography were performed in 28 patients for preinterventional evaluation of iliofemoral arterial occlusion and in 39 patients for follow-up after stent placement in the iliac or femoral arteries, which had been performed several months before.

RESULTS

All 24 occlusions were correctly diagnosed with contrast-enhanced MR angiography. Of the 59 stenoses, 36 were greater than 50% and 23 were 50% or less. Sensitivity and specificity for the detection of stenoses greater than 50% were 100% and 83%, respectively. Patency of the different stents was determined correctly with contrast-enhanced MR angiography. Some stents caused signal intensity dropout, which made MR evaluation of stents difficult. Generally, these signal intensity artifacts were most severe in stainless steel stents and mild in some nitinol stents.

CONCLUSION

Contrast-enhanced MR angiography is comparable to digital subtraction angiography for the detection of stenosis greater than 50% and occlusion in the iliofemoral arteries. Stent patency can be determined, but contrast-enhanced MR angiography is not suitable for stent evaluation owing to signal intensity dropout; however, it provides information about the vascular anatomic areas proximal and distal to the stent.

[Digital 3D rotational angiography for the preoperative and preinterventional clarification of cerebral arterial aneurysms]

OBJECTIVE

Does the recently introduced 3D angiography provide additional information beyond standard angiography (DSA) for the diagnosis of cerebral aneurysms?

METHODS

During a 3-months period DSA and 3D-angiography were performed in 40 patients harbouring a total of 49 aneurysms. Vascular regions that presented an aneurysm diagnosed by DSA were reevaluated by 3D-angiography.

RESULTS

In two patients, vessel-loops previously described as aneurysms by DSA could be identified by 3D-angiography. In one patient, an aneurysm was diagnosed that could not be detected by DSA. In another case, the definitive diagnosis of an aneurysm was obtained only with 3D-angiography. In one patient, an aneurysm was diagnosed that could not be detected by DSA. In another case, the diagnosis of an aneurysm was obtained only with 3D-angiography. In two cases, aneurysms could be definitively excluded by 3D-angiography, whereas in another aneurysm a vessel originating from this lesion was identified. The size of the aneurysms measured by both methods was identical.

CONCLUSIONS

Multiple projections of 3D-angiography provide a better evaluation of the anatomic situation regarding the base of the aneurysm as well as the relationship of an aneurysm to neighbouring vessels. Further, an exact differentiation between a vessel loop and an aneurysm can be made. Therefore, 3D-angiography is a valuable tool when used in conjunction with DSA.