Volume-rendered multidetector CT angiography: noninvasive follow-up of patients treated with renal artery stents

Peripheral arterial disease--what do we need to know?

Peripheral artery disease (PAD) results from progressive narrowing of arteries secondary to atherosclerosis and is defined as an Ankle Brachial Index of <0.9. PAD is highly prevalent and is an increasing burden on both the economy and the patient, especially given the rapid shift in demographics in the United States. Despite its prevalence and association with cardiovascular disease, PAD is still underdiagnosed and undertreated. This may, in part, be related to lack of recognition from the physician's side or paucity of evidence from clinical trials. It has been shown that medical therapy approved for cardiovascular disease is effective in the treatment of PAD and decreases cardiovascular events. Various revascularization strategies are also available for improving symptoms and quality of life in these patients, yet they are underutilized. In an attempt to increase its recognition, PAD has been considered a coronary artery disease equivalent. This article reviews the diagnosis and management of PAD. © 2011 Wiley Periodicals, Inc. The authors have no funding, financial relationships, or conflicts of interest to disclose.

CT angiography of the renal circulation

Although catheter angiography remains the accepted gold standard for imaging of the renal vascular system, rapid progress in cross-sectional imaging techniques has caused a paradigm shift in many diagnostic algorithms toward noninvasive techniques such as computed tomographic angiography (CTA). CTA's cross-sectional imaging techniques provide an opportunity for comprehensive renal investigation that would be impossible with angiography alone. While other competing noninvasive technologies such as ultrasound and magnetic resonance angiography can be used successfully in renal imaging, the benefits of CTA are substantial, including high spatial and temporal resolution, widespread availability, implantable device compatibility, and easy technical reproducibility. This article describes the technical considerations relevant to CTA of the renal vascular system, postprocessing algorithms for volumetric data, and numerous specific applications.

Comprehensive evaluation and medical management of infrainguinal peripheral artery disease: "when to treat, when not to treat"

Peripheral artery disease (PAD) is a highly prevalent atherosclerotic syndrome associated with significant morbidity and mortality. PAD is defined by atherosclerotic obstruction of the arteries to the legs that reduce arterial flow during exercise or at rest, and is associated with systemic atherosclerosis. The clinical presentation of PAD is quite varied, including patients with atypical leg symptoms, classic intermittent claudication, and critical limb ischemia. Clinical assessment of these patients includes a comprehensive history, physical examination, and noninvasive and invasive vascular studies. The major risk factors for PAD include diabetes mellitus, tobacco abuse, hyperlipidemia, hypertension, and advanced age. Because of the presence of these risk factors, the systemic nature of atherosclerosis, and the high risk of ischemic events, patients with PAD should be candidates for comprehensive secondary prevention strategies, including aggressive glycemic control, all attempts at tobacco cessation, lipid lowering and antihypertensive treatment, antiplatelet therapy, and thorough foot care. This article reviews the comprehensive diagnostic algorithm and medical treatment strategies for patients with infrainguinal PAD.

Atherosclerotic Peripheral Vascular Disease Symposium II: vascular magnetic resonance and computed tomographic imaging

Over the past 10 years, there has been a rapid adoption of new technology that has allowed us to image the vascular system in a noninvasive manner with greater speed and improved resolution. The “gold standard,” catheter-based angiography, is now more often used with therapeutic interventions rather than purely diagnostic studies. Catheter-based angiography is being replaced by computerized tomographic angiography (CTA) and magnetic resonance angiography (MRA) for carotid, renal, and peripheral vascular diagnostic examinations. The goal of this writing group is to review the evidence-based approach to selection of imaging modalities; however, regional availability and expertise are recognized as important factors in the selection of imaging modalities.

Impact of multislice CT angiography on planning of radiological catheter placement for hepatic arterial infusion chemotherapy

The objective of this study was to assess prospectively the role of multislice CT angiography (MSCTA) on planning of radiological catheter placement for hepatic arterial infusion chemotherapy (HAIC). Forty-six patients with malignant liver tumors planned for HAIC were included. In each patient, both MSCTA and intra-arterial digital subtraction angiography (DSA) were performed, except one patient who did not undergo DSA. Comparison of MSCTA and DSA images was performed for the remaining 45 patients. Detectability of anatomical variants of the hepatic artery, course of the celiac trunk, visualization scores of arterial branches and interobserver agreement, presence of arterial stenosis, and technical outcome were evaluated. Anatomical variations of the hepatic artery were detected in 19 of 45 patients (42%) on both modalities. The course of the celiac trunk was different in 12 patients. The visualization scores of celiac arterial branches on MSCTA/DSA were 3.0 +/- 0/2.9 +/- 0.2 in the celiac trunk, 3.0 +/- 0/2.9 +/- 0.3 in the common hepatic artery, 2.9 +/- 0.2/2.9 +/- 0.3 in the proper hepatic artery, 2.9 +/- 0.3/2.9 +/- 0.4 in the right hepatic artery, 2.8 +/- 0.4/2.9 +/- 0.4 in the left hepatic artery, 2.9 +/- 0.2/2.9 +/- 0.3 in the gastroduodenal artery, 2.1 +/- 0.8/2.2 +/- 0.9 in the right gastric artery, and 2.7 +/- 0.8/2.6 +/- 0.8 in the left gastric artery. No statistically significant differences exist between the two modalities. Interobserver agreement for MSCTA was equivalent to that for DSA. Two patients showed stenosis of the celiac trunk on both modalities. Based on these imaging findings, technical success was accomplished in all patients. In conclusion, MSCTA is accurate in assessing arterial anatomy and abnormalities. MSCTA can provide adequate information for planning of radiological catheter placement for HAIC.

Techniques in interventional radiology: renal CT angiography

Multidetector row CT angiography has become an important tool in the evaluation of patients with suspected renovascular hypertension. The following article presents a review of the published data on accuracy of this method of evaluation as well as a comparison to other diagnostic strategies, in particular, renal MR angiography.

Multidetector CT Angiography in the Follow-Up of Patients Treated with Renal Artery Stents: Value of Different Reformation Techniques Compared with Axial Source Images

PURPOSE

To evaluate the role of 4 different reformation techniques in comparison with axial images from multidetector computed tomographic angiography (MDCTA) in the follow-up of renal artery stents.

METHODS

Data on 40 patients (20 men; mean age 65 years) who underwent MDCTA as part of their routine follow-up after successful primary stenting of a main renal artery were retrospectively analyzed. Multiplanar reformation (MPR), curved planar reformation (CPR), volume rendering threshold (VRT), and virtual angioscopy (VA) were reviewed by 2 independent observers who were blinded to the results of the axial source images, which served as the gold standard. The stenosis degree was scored as I = 0%, II <50%, III = 51%-75%, IV = 76%-99%, or V = occlusion; a stenosis >50% was considered hemodynamically significant.

RESULTS

Five hemodynamically significant stenoses were identified on axial images. The correlation with axial images was perfect for both observers using MPR and CPR (kappa = 1 for each observer); corresponding results were kappa = 0.69 and kappa = 0.64 for VRT and kappa = 0.88 and kappa = 0.83 for VA, respectively. The interobserver correlations were excellent for all reformation techniques (kappa = 0.95 to 1).

CONCLUSION

Compared to axial images, MPR and CPR correlated perfectly with axial images; VA performed surprisingly well, while VRT was affected by artifacts and consequently showed inferior results.

Multislice computed tomographic angiography versus digital subtraction angiography in the follow-up of nitinol stents in the superficial femoral artery

PURPOSE

To compare quantitative and qualitative parameters obtained from digital subtraction angiography (DSA) with multislice computed tomographic angiography (MSCTA) in the follow-up of superficial femoral artery (SFA) stents.

METHODS

Thirteen patients who had SMART stents implanted in the SFA were examined systematically with DSA and MSCTA (16-row scanner) at 6 months. Quantitative analysis and morphological assessment were performed on DSA images by an independent core laboratory, while the MSCTA images were analyzed by 2 radiologists in consensus. DSA measurements included stent length, minimal lumen diameter and reference diameter at mid stent and 5 mm either side of the stent, and percentage of stenosis. For MSCTA images, lumen area and the minimum, maximum, and mean diameters were also recorded. The images were analyzed qualitatively for diameter stenosis (<50%, 50% to 70%, 71% to 99%, and occlusion), bends, fractures, and calcifications.

RESULTS

There were no statistical differences between lengths of stented segments, diameter measurements, or percentages of stenosis from DSA and MSCTA images. The Bland-Altman method showed good agreement between the 2 methods of measurement. MSCTA detected in-stent proliferation with a diameter stenosis <50% in all 13 cases diagnosed on DSA (there was no stenosis >50%). There were no bends or stent fractures on either set of images. The agreement between DSA and MSCTA for the presence and grading of calcifications was moderate (kappa=0.5).

CONCLUSION

MSCTA provided quantitative and qualitative data comparable with DSA in the analysis of SFA nitinol stents.

Clinical insights into the diagnosis and management of atherosclerotic renal artery disease

Atherosclerotic renovascular disease (ARVD) is an increasingly common contributor to hypertension and renal failure. However, not all patients with an identified obstructive atherosclerotic renal artery stenosis will have clinical improvement, even after successful percutaneous intervention. As such, there remains extensive controversy regarding optimal diagnostic and treatment strategies. Part of this controversy is the result of a paucity of well-designed prospective, randomized clinical trials, but the complex nature of the disorder and the heterogeneity of patients presenting with possible ARVD make simple diagnostic and treatment paradigms difficult to develop. This narrative review describes the latest observations concerning the prevalence, pathogenesis, natural history, diagnostic studies, and treatment options for suspected ARVD. Hopefully, this knowledge will improve the ability of clinicians to weigh risks and benefits and determine the best strategy in individual patients.

Traumatic arterial injuries of the extremities: initial evaluation with MDCT angiography

OBJECTIVE

The purpose of this study was to retrospectively assess the accuracy of MDCT angiography as the initial diagnostic technique to depict arterial injury in patients with extremity trauma.

MATERIALS AND METHODS

Over 36 months, 87 patients (16 females and 71 males; age range, 16-87 years) with clinically suspected arterial injury after extremity trauma underwent 4-MDCT angiography and 67 ultimately underwent surgery. Eighty patients had blunt injuries, and seven had penetrating injuries. The presence of arterial involvement was investigated prospectively by the radiologist in charge and retrospectively by two independent radiologists. Each detected arterial lesion was then characterized as a spasm, stenosis, occlusion, or rupture. The standard of reference was surgery in 67 patients, angiography in two patients, and clinical and radiologic follow-up findings in 18 patients. MDCT angiography was assessed by means of receiver operating characteristic (ROC) curve analysis for lesion detection and Spearman's rank correlation test for lesion characterization. Image quality, lesion depiction, and artifacts were subjectively assessed.

RESULTS

Sixty-two traumatic arterial lesions were confirmed at surgery in 55 patients. MDCT angiography yielded high accuracy in detection (area under the ROC curve [Az] = 0.96; p < 0.001) and characterization (r = 0.94; p < 0.001) of traumatic arterial injuries and in recognizing an underlying dissection (Az= 0.82; p < 0.001). Prospective sensitivity and specificity were 95% and 87%, respectively, and retrospective sensitivity and specificity were 99% and 87%, respectively. MDCT angiography was considered to be sufficient for a reliable diagnosis in 83 patients (p < 0.001). Image quality and lesion depiction on MDCT angiograms were considered to be good and artifacts were considered mild with substantial interobserver agreement (kappa, 0.62-0.69).

CONCLUSION

MDCT angiography provides significant and reproducible technique for the detection and characterization of arterial injuries to the extremities with high image quality and vascular delineation.

IV Contrast Selection for MDCT: Current Thoughts and Practice

OBJECTIVE

The purpose of this article is to review studies evaluating how contrast concentration affects MDCT of the body and to report IV contrast infusion protocols from MDCT angiography and MDCT of abdominal tumors.

CONCLUSION

Higher concentrations (350 mg I/mL or greater) may improve visualization of small abdominal arteries. However, preliminary data comparing 300 mg I/mL to higher concentrations for MDCT of hypervascular hepatocellular carcinoma and pancreatic cancer have shown that higher concentrations may not increase tumor conspicuity.

Computed Tomography Angiography of Carotid Stent. Comparison of Various Self-expandable Stent in a Phantom Model

SUMMARY

We evaluated Computed Tomography Angiography (CTA) of four different self-expandable stents in phantom model. Three stents ware made of nitinol and one was made of cobaltbased alloy. Each stent placed in plastic injector, filled with diluted iodinated contrast material, and placed on a plastic case filled with saline. CTA was performed on a four-detector CT scanner (detector collimation, 0.5mm: helical pitch 3.5). Axial and longitudinal reconstructions of CT imaging were compared with the instent attenuation. Three nitinol stents showed few artifact, and cobalt-based alloy stent was appeared artificial narrowing. In conclusion, CTA is useful for follow-up examination after carotid artery stenting (CAS) as a less invasive evaluation method.

Accuracy of Automated CT Angiography Measurement of Vascular Diameter in Phantoms: Effect of Size of Display Field of View, Density of Contrast Medium, and Wall Thickness

OBJECTIVE

The objective of this study was to assess the effect of wall thickness, density of intravascular contrast material, and size of the display field of view on the accuracy of measurements of vascular diameter in phantoms yielded by automated software for CT angiography.

MATERIALS AND METHODS

Vascular models with three wall thicknesses (1.0, 0.8, and 0.5 mm) and an inner diameter of approximately 4 mm were filled with contrast material of three different densities (198, 270, and 350 H) and scanned with helical CT. Three sizes of display field of view (10, 15, and 20 cm) were used. We evaluated the measurement error of the automated software, which was defined as the difference between the diameter measurement of the automated software and the true inner diameter of the vascular model. Statistical analysis involved three-way analysis of variance with repeated measures.

RESULTS

There were significant differences in the measurement errors among the three wall thicknesses of the vascular model, three densities of intravascular contrast material, and three sizes of display field of view. The overall measurement errors progressively increased with larger sizes of display field of view (p < 0.01) and with lower densities of intravascular contrast material (p < 0.001). The measurement errors tended to progressively increase as the thickness of the wall of the vascular models increased.

CONCLUSION

The accuracy of the diameter measurements by automated software for CT angiography was affected by the size of the display field of view, intravascular density of the contrast material, and wall thickness of the vessel. It is necessary to consider the effects of these factors on the diameter measurements of small arteries.

Observations from multidetector CT imaging of different types of renal artery stents

PURPOSE

To present an optimized protocol for acquisition and reconstruction of multidetector computed tomographic angiographic (CTA) images of the stents most commonly used in renal arteries.

TECHNIQUE

CTA was performed on a 16-detector row CT scanner using 0.75-mm collimation. Multiplanar reformatted images perpendicular to the stents and 2-dimensional curved reformatted images were displayed. Two different view windows ("vascular" and "stent") were used, each adapted to the stent density, the vascular wall density, and the aortic enhancement. Five different types of stainless steel balloon-expandable stents were examined; all caused discernable artifacts. These artifacts became more prominent as the stent density increased, becoming most significant when 2 stents were positioned one inside the other. The "stent" window allowed better appreciation of the stent shape and its position compared to the aortic wall and ostial calcifications. The "vascular" window afforded a better view of the vascular lumen, in addition to visualizing the stent in several planes.

CONCLUSIONS

Multidetector CTA using dedicated acquisition and reconstruction protocols is capable of visualizing the vascular lumen of different types of renal stents while avoiding metallic artifacts.

Update on the management of unruptured intracranial aneurysms

Over the past decade, several factors have led to a dramatic change in the manner in which patients with unruptured intracranial aneurysms are diagnosed and treated. These factors include the increased use of noninvasive imaging modalities for the diagnosis of intracranial aneurysms, publication of new natural history data detailing the hemorrhage risks associated with unruptured intracranial aneurysms, and the broad application of endovascular therapy for their treatment. With these new technologies and new natural history data has come considerable uncertainty about the optimal treatment strategy for patients with unruptured intracranial aneurysms. In this light, it seems prudent to review periodically and examine critically all recent data pertaining to the natural history and treatment of unruptured intracranial aneurysms, in an effort to provide a scientific update on which management recommendations can be based. This review article represents the authors' attempt at such an update, and it is their hope that members of the community of neurovascular surgeons might find this information helpful during their continuing efforts to provide optimal care for their patients with unruptured intracranial aneurysms.

Sonographic follow-up after visceral artery stenting

OBJECTIVE

The aim of this study was to evaluate the sonographic features of stents and the flow parameters of the visceral arteries after stent implantation.

METHODS

Since 1996, 34 stenoses of the visceral arteries (2 mesenteric, 4 celiac trunk, and 28 renal arteries) in 28 patients have been treated with metallic stent implantation in the Department of Radiology of Szeged Medical University. All these patients were regularly followed sonographically. For the diagnosis of restenosis, previously published criteria were used.

RESULTS

All the mesenteric and celiac stents could be visualized, but none of the renal stents were clearly seen sonographically. The flow parameters could be established in all cases. Sonographic examination revealed 1 occlusion, 2 restenoses, and 1 stent displacement. All these abnormalities were confirmed by other imaging modalities.

CONCLUSIONS

Sonography is a useful tool in the follow-up of patients after visceral artery stenting. Despite the fact that none of the renal artery stents were visualized directly, the flow parameters could be evaluated, and the pathologic changes were found.

Multidetector CT angiography with perfusion analysis in the surveillance of renal artery stents

PURPOSE

To evaluate 4 perfusion parameters obtained by multidetector computed tomographic angiography (CTA) in the follow-up of patients after renal artery stenting.

METHODS

Thirty-three consecutive patients (20 women; mean age 64.3+/-10.7 years) with renal artery stents were included in this prospective pilot trial. CTA was performed in 21 patients on a 4-row scanner and in 12 patients on a 16-row scanner. Volume maximum intensity projections and curved planar reconstructions were used for morphological analysis. The initial contrast test bolus was used for perfusion imaging by placing 2 additional regions of interest in the cortex of each kidney. The maximum relative attenuation values (Hounsfield units [HU max]), the time-to-peak values, an attenuation ratio, and a time-to-peak ratio for each side were calculated.

RESULTS

Over a mean follow-up of 3.4+/-1.7 years, restenosis was detected in 4 (12.1%) of the 33 stents; in all 66 main renal arteries, 5 (7.5%) significant flow obstructions were detected. Interobserver agreement for all morphological parameters was excellent (kappa>0.8). Mean relative HU max for the cortical region of stented arteries was 63.7+/-29.7 (mean HU ratio 0.37+/-0.12); the mean TTP max was 32.9+/-7.4 seconds (mean ratio 0.76+/-0.10). None of the perfusion parameters differed significantly between patients with and without significant flow obstructions (p>0.05).

CONCLUSIONS

Despite the excellent morphological information provided by multidetector CTA in the follow-up of renal stents, this modality does not provide hemodynamic information. Unfortunately, none of the evaluated perfusion parameters added any useful information in the follow-up after renal artery stenting.

Basics of computed tomography angiography of the lower extremity vessels

Complete noninvasive, angiographic evaluation of the abdominal aorta and lower extremity vessels using the latest generation of multidetector row computed tomography (CT) scanners can now be accomplished in a single scan lasting less than a minute. The high spatial resolution of these new scanners and their more efficient use of contrast permit accurate depiction of disease in the smaller tibial and pedal vessels, as well as the larger diameter iliac and femoral arteries; nevertheless, many challenges and obstacles remain to its more widespread acceptance. Foremost among these, is the difficulty in accurately reconstructing the smaller leg and pedal vessels from individual CT slices, a process that must to a very great extent be done manually, and the potential nephrotoxicity of iodinated contrast material. Future advances in imaging software that could more fully automate accurate three-dimensional reconstructions of the lower extremity vasculature, and detector technology to allow for even finer resolution of the vasculature will further enhance an already powerful and clinically useful tool.

Quand, comment et pourquoi réaliser une exploration des artères rénales ?

The objectives of this course are both: to describe acquisition, injection and reconstruction parameters of volumic images for renal arteries examination and specific signs; to discuss the role of the different images in the diagnosis and in the therapeutic management. Ultrasound is one of the best imaging for the analysis of renal arteries in the detection of stenosis even if the sensitivity is less (around 85%)compared to CT Angiography (95%) and MR Angiography (90%). Because of this advantage and of 3D evaluation, CTA and MRA are sometimes in the first line for renal artery evaluation and can assess morphology before angioplasty. Renal scintigraphy with Captopril test and renin dosage are only used for small kidney evaluation. Arteriogram is systematically followed by angioplasty if possible. With the new endovascular materials, complications decrease (less than 5% with a major reduction in cholesterol emboli) and indications of endoprosthesis increase (71% of stenting with half of it in direct stenting technique). This course will give practical tools for imaging acquisition, specifically 3D imaging, for indications and management of lesion in accordance to symptoms and morphology.

Measurement of Vascular Diameter In Vitro by Automated Software for CT Angiography:Effects of Inner Diameter, Density of Contrast Medium, and Convolution Kernel

OBJECTIVE

This investigation was performed to evaluate the accuracy of diameter measurement of vessels in vitro by automated software for CT angiography.

MATERIALS AND METHODS

Vascular models with three inner diameters ( approximately 3, 4, and 6 mm) filled with contrast medium of three different densities ( approximately 460, 350, and 210 H) were scanned with helical CT. Five convolution kernels (soft, standard, detail, bone, and lung) were used. We evaluated the measurement error, defined as the difference between the diameter measured by the automated software and the true inner diameter of the vascular model. Statistical analysis involved three-way analysis of variance with repeated measures.

RESULTS

Significant differences occurred in measurement error among the three vascular model inner diameters, among the three densities of intravascular contrast medium, and among the five convolution kernels (p < 0.01). In all the convolution kernels except lung, measurement errors progressively decreased with higher densities of intravascular contrast medium (p < 0.01). In vascular models filled with contrast medium of 350 H, measurement errors were significantly smaller in soft (mean +/- standard deviation [SD], 0.29 +/- 0.16 mm) and bone (0.23 +/- 0.05 mm) than in other convolution kernels (p < 0.01).

CONCLUSION

The accuracy of diameter measurement was affected by the vascular model inner diameter, the density of contrast medium, and the convolution kernel. A higher density of intravascular contrast medium and selection of the proper convolution kernel will improve accuracy.

MDCT-imaging of peripheral arterial disease

With the design and development of advanced computed tomography (CT) techniques and applications, like the newest generation of 16-detector-row CTs, CT angiography of the lower limb becomes a feasible tool for imaging peripheral vascular disease. Due to several advantages, compared with conventional digital subtraction angiography (DSA), including minimal invasiveness, CT angiography competes against diagnostic DSA in several clinical situations. 16-DCT offers the possibility to acquire thin slices from the diaphragm to the ankle in less than 40 sec. Easily, a data set of 800 to 1200 transverse slices may be created. To use transverse reconstructions alone to read these volumetric data sets is not appropriate. Powerful post-processing tools for volumetric analysis are required so that routine interpretation can be performed as efficiently and accurately as transverse section review. Because of its widespread availability and applicability, CT angiography of the lower extremities may be applied to patients in a pre- or post-procedural situation and also serves as a first line modality in patients with acute onset of clinical symptoms. Although multidetector CT arteriography is rapidly achieving clinical acceptance, further studies need to be performed to fully evaluate the clinical value of this method of peripheral arterial imaging. This article reviews the current status of multidetector CT peripheral arteriography, including indications, technical details, image post-processing, radiation exposure, and clinical results.

Multi-detector row CT of the kidneys and urinary tract: techniques and applications in the diagnosis of benign diseases

Multi-detector row helical computed tomography (CT) offers considerable advantages in evaluation of the urinary tract. It has the potential to become the single imaging modality used for comprehensive evaluation and treatment planning of most conditions affecting the kidneys and urinary tract, making conventional diagnostic techniques such as intravenous urography and angiography nearly obsolete. This article illustrates important selected applications of multidetector CT in the evaluation of benign conditions of the kidneys and upper urinary tract, including evaluation of the renal arterial and venous anatomy in preparation for surgery, diagnosis of renal artery stenosis and aneurysms, assessment of the renal veins, imaging of inflammatory and infectious renal diseases and evaluation of selected benign pathologic processes of the urinary tract.

Long-term follow-up after renal artery stenting

BACKGROUND

Renal artery stenosis may cause secondary arterial hypertension and lead to end-stage renal disease. Percutaneous transluminal angioplasty with stent implantation (PTRAS) allows effective and consistent treatment with a high technical success rate. The present trial focuses on the morphological and clinical results as assessed at a long-term follow-up (FU) visit. The main goals were assessment of the restenosis rate and evaluation of arterial hypertension and renal function.

PATIENTS AND METHODS

40 patients who had undergone successful stenting of a main renal artery were prospectively enrolled. At the FU visit, all patients underwent a risk-factor assessment, evaluation of arterial blood pressure and serum creatinine, and multi-detector computed tomography angiography (CTA).

RESULTS

Median FU was 3.3 years. Hyperlipidemia was present in 67.5% of the patients, current cigarette smoking in 35% and diabetes mellitus in 15%. All patients still suffered from arterial hypertension but, compared with the pre-interventional situation, arterial hypertension was improved in 37.5%. Serum creatinine was increased in 25% of patients, mean creatinine level was 1.3 +/- 0.4 mg/dl. Hemodynamically relevant restenosis was detected by observer 1 in five patients and by observer 2 in six patients, giving restenosis rates of 12.5% and 15%, respectively, after the median FU period. Both observers detected three additional relevant stenoses in the contralateral main renal arteries.

CONCLUSIONS

PTRAS gives excellent morphological long-term results. However, the clinical long-term outcome regarding arterial hypertension and renal function is only moderate.

Three-dimensional volume rendering of multidetector-row CT data: applicable for emergency radiology

Multidetector-row computed tomography (MD-CT) not only creates new opportunities but also challenges for medical imaging. Isotropic imaging allows in-depth views into anatomy and disease but the concomitant dramatic increase of image data requires new approaches to visualize, analyze and store CT data. The common diagnostic reviewing process slice by slice becomes more and more time consuming as the number of slice increases, while on the other hand CT volume data sets could be used for three-dimensional visualization. These techniques allow for comprehensive interpretation of extent of fracture, amount of dislocation and fragmentation in a three-dimensional highly detailed setting. Further more, using minimal invasive techniques like CT angiography, new opportunities for fast emergency room patient's work up arise. But the most common application is still trauma of the musculoskeletal system as well as face and head. The following is a brief review of recent literature on volume rendering technique and some exemplary applications for the emergency room.