FD-OCT and IVUS intravascular imaging modalities in peripheral vasculature.

INTRODUCTION: Intra-Vascular Ultra-Sound (IVUS) and Frequency Domain-Optical Coherence Tomography (FD-OCT), in vivo, intra-vascular, imaging modalities, widely used in the field of coronary disease, have been recently implemented in peripheral endovascular procedures, for procedural assessment, plaque characterization and determination of predictors of treatment outcomes. Their unique characteristics have also been used in order to provide additional features and improve the performance of re-entry devices and atherotomes. Areas covered: Present review focuses on available literature regarding these two promising imaging technologies in the peripheral vasculature, highlighting the added value produced by their use in endovascular therapy, their limitations and their utilization in new endovascular devices. Authors also provide their future perspective and the possible benefits in understanding vascular behavior and lesion characterization in peripheral endovascular interventions. Expert commentary: By providing both quantitative but also qualitative data on vessel and lesion morphology, intravascular imaging modalities offer a valid solution for endovascular treatment evaluation and outcome presentation homogeneity.

Optical coherence tomography provides images similar to histology and allows the performance of extensive measurements of drug-eluting metal stents in animal ureters.

Optical coherence tomography (OCT) images and histology images of metal stents (MSs) inserted in animal ureters were compared, and the reliability of an OCT-based automated method for the performance of quantitative evaluation of ureteral MSs was evaluated. A zotarolimus-eluting metal stent (ZES) and a bare metal stent (BMS) were inserted in each ureter of ten pigs and six rabbits. OCT was performed in unobstructed stented ureters. Histopathologic examination of the stented ureters embedded in glycol-methacrylate took place. Quadrants of OCT images were compared to their respective histologic images by employing two independent observers who delineated different layers in the quadrants of OCT images and correlated them to the respective histologic quadrants. Manual (integrated OCT device software) and automated measurements of the OCT images using an automated strut detection method were compared. The observers highly agreed on the delineation of urothelium from the lamina propria and the lamina propria from the muscle layer of the ureteral wall. The algorithm measurements were similar to the manual measurements, and the algorithm proved to be reliable in the evaluation of ureteral MSs. Significantly higher endothelial hyperplasia of the BMSs in comparison to the ZESs was also quantitatively demonstrated by the strut detection method. OCT proved to be a reliable method for the evaluation of ureteral MSs. OCT provided images of the stented ureteral lumen similar to light microscopy quality. Measurements of the stented ureter are reliably performed by the automated strut detection method.

Does below-the-knee placement of drug-eluting stents improve clinical outcomes?

Modern critical limb ischemia management algorithms endorse an "endovascular first" strategy of treatment. The advent of stents coated with anti-restenotic agents that are gradually eluted to the vessel wall has revolutionized modern endovascular therapies. Several single-center, non-randomized cohort series have provided compelling data about the short- to mid-term safety and effectiveness of drug-eluting stents in below-the-knee lesions and have fuelled further large-scale research. Three multicenter randomized trials (the YUKON-BTX, the DESTINY and the ACHILLES trials) are now available and have paved the way for level I-A evidence about infrapopliteal use of drug-eluting stents. Amassed evidence strongly supports the use of olimus-eluting metal stents for focal obstructive infrapopliteal lesions in order to inhibit restenosis, prolong vessel patency and thereby achieve sustained patient improvement, as reflected by the significantly improved Rutherford-Becker classification, reduced number of repeat procedures and a trend towards improved wound healing. The present overview outlines current evidence about clinical outcomes after below-the-knee drug-eluting stent placement compared to more traditional endovascular treatments like conventional old balloon angioplasty and bare metal stents. Available evidence is appraised in the context of clinically meaningful results and relevant unresolved issues are highlighted.

Is hypertension a manifestation of the nutcracker phenomenon/syndrome? Case report and brief review of the literature.

Hypertension has been rarely reported in patients with the nutcracker phenomenon/syndrome. We describe a young male adult where a computed tomography angiography provided evidence of left renal vein dilatation, probably due to its compression through the angle between the aorta and the superior mesenteric artery, during the evaluation for secondary hypertension. As there were no other signs for secondary hypertension, we proceeded with a venography of the inferior vena cava and the renal veins that revealed mild anatomical findings compatible with the so called nutcracker phenomenon/syndrome. Blood levels of renin and aldosterone and renocaval pressure gradient from these sites were between normal limits. As there were coexisting anatomical and clinical findings (hypertension), nutcracker syndrome might have been claimed. However, no causal links could be established and these findings should be considered only as a coincidence.

SU-E-I-90: Fast and Robust Algorithm Towards Vessel Lumen and Stent Strut Detection in Optical Coherence Tomography.

PURPOSE: Optical Coherence Tomography (OCT) is a catheter-based imaging method that employs near-infrared light to produce high-resolution cross-sectional intravascular images. We propose a new segmentation technique for automatic lumen area extraction and stent strut detection in intravascular OCT images for the purpose of quantitative analysis of neointimal hyperplasia (NIH). METHODS: Two clinical dataset of frequency-domainOCT scans of the human femoral artery were analyzed. First, a segmentation method based on Fuzzy C-Means (FCM) clustering and Wavelet Transform (WT) was applied towards inner luminal contour extraction. Subsequently, stent strut positions were detected by utilizing metrics derived from the local maxima of the wavelet transform into the FCM membership function. RESULTS: The inner lumen contour and the position of stent strut were extracted with very high accuracy. Compared with manual segmentation by an expert physician, the automatic segmentation had an average overlap value of 0.917 ± 0.065 for all OCT images included in the study. The strut detection procedure successfully identified 6.7 ± 0.5 struts for each OCT image. CONCLUSIONS: A new fast and robust automatic segmentation technique combining FCM and WT for lumen border extraction and strut detection in intravascular OCT images was designed and implemented. The proposed algorithm may be employed for automated quantitative morphological analysis of in-stent neointimal hyperplasia.

Does ultrasound-guided lidocaine injection improve local anaesthesia before femoral artery catheterization?

AIM: To present the results of a prospective, randomized, single-centre study investigating local anaesthesia before percutaneous common femoral artery (CFA) puncture and catheterization with the use of ultrasound-guided injection of lidocaine versus standard infiltration by manual palpation. MATERIALS AND METHODS: Patients scheduled to undergo diagnostic or therapeutic transfemoral catheter-based procedures gave informed consent and were randomized in two groups. In the first arm local anaesthesia with lidocaine hydrochloride 1% was performed under ultrasound guidance (group U/S), while in the second arm the standard method of manual artery palpation was applied (group M). In both groups, subsequent CFA catheterization was achieved under ultrasound guidance. The primary study endpoint was peri-procedural pain level evaluated with a visual-analogue scale (VAS score 0-10). RESULTS: Between January 2009 and 2010, 200 patients (161 men, mean age 63±12 years) were equally assigned to each group without any significant differences in baseline demographics. Patients in group U/S experienced significantly less pain during CFA catheterization in comparison with group M with a difference of three points in mean VAS score reported (1.6±1.6 versus 4.6±1.9, p<0.0001). In addition, significantly less volume of lidocaine was used in group U/S compared to group M (16±2.7 versus 19±0.8ml, p<0.001).Total vascular access time was similar in both groups (4.4±1.3 versus 4.5±1.3min). Overall complications included two small groin haematomas in each group. CONCLUSION: Ultrasound-guided local anaesthesia of the CFA prior to percutaneous transcatheter procedures is safe and achieves superior levels of analgesia with minimal patient pain and discomfort compared to the standard method of manual palpation.

Influence of contrast media on red blood cell deformability.

Iodinated contrast media (CM) are widely used in diagnostic imaging and therapeutic interventional procedures of everyday clinical practice and are associated with multiple hemodynamic and hemorheological effects. The purpose of our work was to investigate the red blood cell (RBC) rheological properties after in vivo administration of low-osmolar or iso-osmolar CM by measuring their membrane deformability (Index of Rigidity, IR) using a filtration method. Blood samples were taken from patients who underwent digital subtraction angiography of the peripheral arteries at various times before and after intravenous administration of CM. CM included iso-osmolar Iodixanol, low-osmolar Iopromide and low-osmolar Iopentol. In the whole patient group an IR increase of 59% was calculated 5 minutes after administration of CM followed by a normalization of elevated IR values within the following hour. The 5-min IR increase was strongest in the group treated with Iopromide, whereas administration of Iodixanol was associated with a more modest transient IR increase. Intravenous injection of CM in humans may be associated with a transient but considerable decrease of RBC membrane deformability and particularly for the iso-osmolar CM the induced changes in membrane deformability seem to be more moderate.

Clinical-oriented collaboration over the Web during interventional radiology procedures.

Multidisciplinary collaboration is a key requirement in several contemporary interventional radiology procedures (IRPs). We proposed a hybrid system (NetAngio) to enable "on the fly" heterogeneous collaboration to support IRP providing intraoperating essential services, and investigate its feasibility and effectiveness in a referral medical center. We have developed a Web-based, cost-effective structure, able to support real-time mentoring, image manipulation, and education services beyond the boundaries of the single institution and potentially allow sub specialists to participate in opinion and decision making in more complex cases. Supported services based on a Motion Joint Photographic Experts Group (MJPEG) coder/decoder (CODEC) can be easily accessible by authorized collaborators, within a user-friendly interface by using a typical Web-browser. Ten interventional radiologists, two vascular surgeons and two medical physicists participated in 33 "fully collaborative" cases during a 13-month period from January 2004 to February 2005. In addition, fifteen 90-minute open seminars and finally, 75 expert's module activations, and 255 learner's module activations were performed during the evaluation period. Collaborative procedures are able to enhance outcomes performance especially in more complex cases where the simultaneous presence of a remote expert interventionist and a medical physicist or a surgeon is required. Further research is needed to promote integration of additional data sources and services.

Ureteral injuries during gynecologic surgery: treatment with a minimally invasive approach.

PURPOSE: To report the safety and efficacy of percutaneous nephrostomy and primary antegrade recanalization for treatment of iatrogenic ureteral strictures after gynecologic surgery. PATIENTS AND METHODS: Ten women had symptoms suggestive of ureteral obstruction during the immediate postoperative period (5 days-1 week after surgery). Under analgesia and conscious sedation, standard percutaneous nephrostomy was performed, and a long 7F sheath was placed in the upper ureter. The obstructions were traversed with the aid of a 0.0035-inch Glidewire and a 5F angled Glide catheter (Terumo, Japan). Subsequently, the areas were dilated with angioplasty balloons to a maximum diameter of 7 mm. Finally, an 8F percutaneous internal/external nephroureteral drainage stent was inserted to secure ureteral patency. Follow-up was carried out by serial nephrostomography until removal of the stent and by renal ultrasonography thereafter. RESULTS: Twelve obstructions with a mean length of 1.4 cm (range 0.4-1.9 cm) were managed. The technical success rate was 100%. No major complications occurred, and normal renal function was restored. The mean follow-up was 12 months. In 60% of the patients, a patent ureter was depicted at 1 week, whereas in four patients, repeat dilation of the obstructed segment was required. The stents were removed after a mean period of 4.8 weeks. CONCLUSION: Percutaneous nephrostomy and primary antegrade ureteral balloon dilation is safe and efficacious for treating ureteral injury after pelvic surgery and obviates open surgical manipulations.

Valgus impacted proximal humeral fractures and their blood supply after transosseous suturing.

We treated 16 patients (11 women and five men, average age 45 years), all having four-part valgus impacted fractures of the proximal humerus, with transosseous suturing. All had preoperative angiography performed 6-12 h after admission. The average impaction angle was 43 degrees , and the mean lateral displacement of the humeral head was 1.4 mm. Postoperative angiography was performed 8-10 weeks after the operation followed by digital image processing using the segmentation technique. No statistically important reduction in the length and area of large (>0.5 mm) vessels was seen. Union was confirmed by the reduction in the length and area of small vessels (<0.5 mm). At a mean follow-up of 40 months, avascular necrosis was only found in one patient. The average Constant-Murley score was 87 (67-100) points, whereas the functional score in comparison with the unaffected shoulder was 94% (89-100%). Despite the small number of patients, transosseous fixation seems to preserve the remaining blood supply of the humeral head.

An experimental environment for the production, exchange and discussion of fused radiology images, for the management of patients with residual brain tumour disease.

The present work aims to display the use of groupware as a tool for better management of the available resources (human, computing and imaging) within the University Hospital of Patras, Greece for the task of managing patients with postoperative residual brain tumour. Emphasis is given to the additional information that can be revealed and taken into account from novel image processing techniques, developed by our group, and the central role of the Medical Physicist in the groupware. Fused images, produced by the combination of CT, MR and SPECT representations of the brain, contain both anatomical and functional information and comprise a new representation of reality. Medical experts, unfamiliar with this new representation, form a groupware for the task of interpreting them and providing better services to the patient. Groupware procedures, facilitated by modern network technology, bring experts' tacit knowledge to the surface and facilitate its exchange.

Coated v noncoated ureteral metal stents: an experimental model.

PURPOSE: The purpose of the present study was to compare the standard metal stents with internally and externally coated metal stents in the pig model. MATERIALS AND METHODS: In nine female pigs weighing between 25 and 30 kg, the metal stents were randomly placed in either the right or left ureter, for a total of 18 stented ureters. Six ureters were stented with a Wallstent (Schneider, Zurich, Switzerland), six with a Passager stent (Boston Scientific, Natick, MA, USA), and six with a Corvita endoluminal graft (CEG) (Boston Scientific, Natick, MA, USA). Patency was examined by nephrostotomography 24 hours and 21 days after the initial procedure. RESULTS: Free flow of urine through the stents into the bladder was revealed in all ureters with the exemption of four cases where a Passager stent migrated into the bladder, jeopardizing ureteral patency. The Wallstent generated mild inflammation with metaplasia of the urothelium; the CEG a more pronounced inflammatory response in the adjacent ureter; and the Passager stent severe inflammatory reaction with necrosis of the urothelium. The sections of the Wallstents revealed the presence of a mild polypoid reaction adherent to the internal surface of the devices. The coated stents showed no tissue ingrowth through the lining material into the ureteral lumen, and thus, the urothelium was compressed beneath the prostheses. CONCLUSIONS: Our experimental results suggest that the standard Wallstent generates less inflammation of the surrounding tissues than coated stents. The coated stents have the advantage of minimal tissue ingrowth but have a tendency to migrate toward the bladder.

Virtual endoscopy in the diagnosis of an adult double tracheal bronchi case.

We report a case of ipsilateral double tracheal bronchi supplying a tracheal lobe in a 42-year-old man, who presented with a 10-year history of recurrent respiratory infections. Diagnosis was established by chest computed tomography (CCT), virtual endoscopy and bronchoscopy. Both bronchi were surgically resected along with the right upper lobe of the lung and the associated tracheal lobe. To our knowledge, this is the first report of ipsilateral double tracheal bronchi in the adult life to be diagnosed and treated on the basis of modern radiological techniques and especially virtual endoscopy findings.

Quantification of the ionising radiation effect over angiogenesis in the chick embryo and its chorioallantoic membrane by computerised analysis of angiographic images.

PURPOSE: We evaluated, in vivo, the effect of ionising radiation on the angiogenesis process in the chick embryo and its chorioallantoic membrane (CAM) using digital subtraction angiography (DSA) in conjunction with computer-assisted image analysis. Information regarding the ionising effect on endothelial cells during radiation treatment was extracted. MATERIAL AND METHODS: Two series of fertilized eggs were irradiated with a single ionising radiation dose of 10 Gy on days 9 and 13 of embryonic development. Angiography was carried out 24 h after irradiation. The angiographic images were digitized and subsequently processed. A set of specific morphological parameters was defined to allow an analytical characterization of the vascularity status. Vessels were classified into three categories according to their diameters (> or = 200 microm, 100-200 microm and 50-100 microm). The data were normalized and statistically evaluated. RESULTS: On day 10, total vascular area and total vascular length presented a 15.6+/-1.2% and 18.4+/-2.4% reduction, respectively, while vascular diameters increased 3.3+/-0.5%. The vessel area and length of the first category > or = 200 microm) increased 9.8+/-1.1% and 8.1+/-0.9%, respectively, while these morphometric parameters for each of the remaining two categories decreased 44.3+/-2.9%, 38.7+/-4.2% and 45+/-3.8%, 30.7+/-3.4%, respectively. On day 14 insignificant changes were observed. CONCLUSION: Computerised analysis of angiographic images showed that the antiangiogenic effect of irradiation during the various phases of CAM development is larger on the 10th day than that observed on day 14 and it depends on the vessel size.

Metal stents for the management of atherosclerotic renovascular disease.

PURPOSE: We report on our experience with the use of metal stents for the treatment of atherosclerotic renovascular disease. PATIENTS AND METHODS: Since 1996, 62 patients (mean age 67 years) with ostial atherosclerotic renal artery stenosis were treated successfully by placement of metal stents. All patients presented with renovascular hypertension, and eight had additionally impaired renal function. In 12 patients, stents were placed bilaterally. In 54 patients, the introduction of stents was performed as the primary mode of treatment, and in the remaining 8 patients, the positioning of the endoprosthesis was deemed necessary because of recurrence of stenosis previously treated by renal percutaneous transluminal angioplasty (PTA). The patients were followed for a mean period of 18 months (range 9-48 months). RESULTS: Positioning of the endoprosthesis was successful in all patients. No major complications were reported. The 18-month patency rate was 77.4% (48 patients). Hypertension resolved in 39 patients and showed a trend to improvement in 15 patients. We observed no improvement of renal function in the eight patients who had impaired function prior to the procedure. CONCLUSION: Implantation of metal stents is a safe and effective method for the treatment of atherosclerotic renal artery stenosis and certainly presents an important alternative to renal PTA.

Liposome-coated metal stents: an in vitro evaluation of controlled-release modality in the ureter.

PURPOSE: In vitro preparation of liposome-covered metal stents and loading of liposomal drug formulations that will slowly release the drug in the vicinity of the stent. MATERIALS AND METHODS: Polytetrafluoroethylene-coated stents were used. Large multilamellar (MLV) liposomes (phosphatidylcholine:cholesterol 1:1 mol/mol), empty or entrapping the corticosteroid anti-inflammatory drug, dexamethasone, were prepared by the thin-film hydration method and applied to pieces of stent using a simple and mild evaporation technique. Initially, a freeze-drying method for applying liposomes to stents was also evaluated, but it failed to produce stents that efficiently retain liposomal lipid when incubated in an aqueous environment. The presence of liposomes on the stent surface was confirmed by scanning electron microscopy. RESULTS: After analyzing the release of liposomal lipid (using a phospholipid assay) and liposomal drug (by a modified dexamethasone high-pressure liquid chromatography method) in an in vitro system developed to simulate in vivo conditions, it was found that 39.11+/-6.8% of the lipid and 50.84+/-5.48% of the drug was released from the stent pieces during 48 hours of incubation in the presence of artificial urine. The amount of dexamethasone released from stents during their application procedure was found to be negligible in an in vitro dry run. CONCLUSION: The use of stent-associated liposomal drug formulations as slow-release depots could be an efficient method of treating the untoward event of ureteral stent obstruction.

Encrustation of a metal alloy urinary stent: a mechanistic investigation.

MATERIALS AND METHODS: A section of a metal stent consisting mainly of tantalum coated partially by strongly adhering calcium oxalate monohydrate (COM) crystals was immersed in supersaturated solutions prepared from calcium chloride and sodium oxalate at 37 degrees C and ionic strength 0.15 M in NaCl. Abstract OBJECTIVES: To investigate the kinetics of encrustation of a metall alloy urinary stent system in vitro by calcium oxalate and characterize the crystals forming from solutions supersaturated with respect to all calcium oxalate hydrates. RESULTS: The COM-coated stent mineralized upon immersion in the supersaturated solutions. The process was monitored with a calcium ion-selective electrode and the rates were measured at conditions of sustained solution supersaturation. COM crystals formed on the stent and the rate of COM crystal growth yielded a second-order dependence on the solution supersaturation. CONCLUSIONS: The deposition of COM crystals on the metal stents coated partially with COM crystals by adhesive forces was found to be most important for the acceleration of the encrustation process. The dependence of the rates on the solution supersaturation suggested absence of secondary nucleation and a surface-controlled process for the encrustation process.

Metallic stents in gynecologic cancer: an approach to treat extrinsic ureteral obstruction.

OBJECTIVE: We report on our experience with the use of self-expandable metal stents for the treatment of extramural ureteral obstruction in patients with gynecologic cancer to restore ureteral patency and to alleviate the ureterectasis and hydronephrosis proximal to the ureteral narrowing. METHODS: Fourteen women (mean age 48 years) with obstructive uropathy secondary to gynecologic malignancies were treated successfully by placement of Wallstent self-expandable intraureteral metallic stents. The patients were followed for a mean period of 15 (range 9-24) months. RESULTS: Obstructive uropathy was resolved in all cases. In 1 patient placement of an additional, totally coaxial, stent was considered necessary because of tumor ingrowth, occurring 6 months after the procedure. In another patient, tumor overgrowth invading the borderline area between the proximal ureteric end and the metallic prosthesis was seen 12 months after stent placement causing obstruction. Thus, an additional Wallstent was implanted overlapping the initially placed stent. Patency was achieved in all the remaining ureters, during the follow-up period, without any need for further intervention. CONCLUSION: Implantation of self-expandable metal stents is a safe and effective method for bypassing ureteral obstruction due to gynecologic malignancies.

Percutaneous treatment of large symptomatic renal cysts.

PURPOSE: To evaluate the efficacy of alcohol in combination with tetracycline for the treatment of symptomatic renal cysts. PATIENTS AND METHODS: Twenty-four patients age 45 to 77 years (mean 66 years) with a large (5-13-cm; mean 7.5-cm) symptomatic renal cyst associated with flank pain were treated by aspiration under ultrasound guidance and injection of alcohol and tetracycline. Patients were followed with ultrasonography at 1, 6, and 12 months and once a year thereafter. RESULTS: The aspirated volume ranged from 65 to 1500 mL (mean 360.5 mL). Two patients experienced mild pain during alcohol injection, but the procedure was completed successfully. One patient reported severe pain after tetracycline injection. The tetracycline was immediately aspirated, and the procedure was then aborted. The remaining patients were relieved of their symptoms after treatment, and they remained symptom free during a mean follow-up of 20 months (range 7-36 months). CONCLUSIONS: The combination of alcohol and tetracycline is safe and effective and offers a very favorable minimally invasive therapeutic alternative for the treatment of symptomatic renal cysts.

Quantitative assessment of angiogenesis in the chick embryo and its chorioallantoic membrane by computerised analysis of angiographic images.

We studied, in vivo, the angiogenesis process in the chick embryo and its chorioallantoic membrane (CAM) using digital subtraction angiography (DSA) in conjunction with computer-assisted image analysis. In a series of fertilised eggs, angiography was carried out at days 8, 10, 12 and 14 of embryonic development. The angiographic images were digitised and subsequently processed for a specific image analysis. A set of specific morphological parameters has been defined to allow an analytical characterisation of the vascularity status. Vessels were classified into three categories according to their diameter (50-100, 100-200, and > 200 microm). The data were normalised and statistically evaluated. Graphs showing the development of angiogenesis were obtained. Total vascular area revealed a continuous rise, whereas, total vascular length increased until day 12 and then it started decreasing. These morphometric parameters in the first two vessel categories progressively increased throughout the entire period of development, whereas in the third category they increased until day 10 and then they started decreasing. By applying a vascular casting technique CAM vessels were visualised and compared with those extracted from the processed angiographic image. The comparison revealed that there is exact matching for the first two vessel categories (diameters higher than 100 microm) while the matching of the third category (diameters between 50 and 100 microm) is approximate.