Dimitrios Karnabatidis

CT angiography with three-dimensional techniques for the early diagnosis of intracranial aneurysms. Comparison with intra-arterial DSA and the surgical findings

INTRODUCTION Cerebral CT angiography (CTA) is an established method applied to both the detection and treatment planning of intracranial aneurysms. The aim of our study was to compare CTA and digital subtraction angiography (DSA) findings with the surgical results mainly in patients with acute SAH and to evaluate the clinical usefulness of CTA. MATERIALS AND METHODS During the last 2 years, 82 consecutive patients were admitted under clinical symptoms and signs suggestive of harboring an intracranial aneurysm. CT angiography performed immediately afterwards the plain CT, while DSA was performed within the first 48 h of admission. All aneurysms detected were confirmed during surgery or endovascular embolization. Repeat DSA was performed in all patients having both the initial CTA and the DSA 15 days after the onset of symptoms negative. CT angiograms and conventional angiographies were studied by a consensus of two radiologists for each technique, who performed aneurysm detection, morphological features characterization and evaluation of the technique. RESULTS Surgical or/and endovascular treatment was performed in 45 patients and 53 aneurysms were confirmed. Using 3D-CT angiography, we detected 47 aneurysms in 42 patients. Conventional angiography depicted 43 aneurysms in 39 patients. The sensitivity of CTA for the detection of all aneurysms versus surgery was 88.7%, the specificity 100%, the positive predictive value (PPV) 100%, the negative predictive value (NPV) 80.7% and the accuracy 92.3%. Accordingly, the sensitivity of DSA was 87.8%, the specificity 98%, the PPV 97.7%, the NPV 89.1% and the accuracy 92.9%. Considering aneurysms > or =3 mm, CTA showed a sensitivity ranging from 93.3 to 100%, equal to that of DSA. CONCLUSION Cerebral CT angiography has an equal sensitivity to DSA in the detection of intracranial aneurysms >3 mm. It has also 100% detection rate in AcoA and MCA bifurcation aneurysms, while some locations, like posterior communicating artery aneurysms, remain problematic. The delineating features of each aneurysm are better depicted with CTA due to 3D visualization. The use of digital subtraction angiography as a diagnostic tool can be limited in equivocal cases.

Ureteral Obstruction: Is the Full Metallic Double-Pigtail Stent the Way to Go?

BACKGROUND The Resonance metallic ureteral stent (Cook Medical, Bloomington, Indiana, USA) has been introduced for the management of extrinsic-etiology ureteral obstruction for time periods up to 12 mo. OBJECTIVE The current study aims to determine short- and medium-term effectiveness of the Resonance stent in malignant and benign ureteral obstruction. DESIGN, SETTING, AND PARTICIPANTS In total, 50 patients with extrinsic malignant obstruction (n=25), benign ureteral obstruction (n=18), and previously obstructed mesh metal stents (n=7) were prospectively evaluated. INTERVENTION All patients were treated by Resonance stent insertion. Twenty stents were inserted in antegrade fashion, and the remaining stents were inserted in a retrograde approach. No patient dropped out of the study. The follow-up evaluation included biochemical and imaging modalities. MEASUREMENTS We evaluated the technical success rate, stricture patency rate, complications, and the presence and type of encrustation. RESULTS AND LIMITATIONS The technical success rate of transversal and stenting of the strictures was 100%. In 19 patients, balloon dilatation was performed prior to stenting. The mean follow-up period was 8.5 mo. The stricture patency rate in patients with extrinsic malignant ureteral obstruction was 100% and in patients with benign ureteral obstruction 44%. Failure of Resonance stents in all cases of obstructed metal stents was observed shortly after the procedure (2-12 d). In nine cases, stent exchange was demanding. Encrustation was present in 12 out of 54 stents. CONCLUSIONS The Resonance stent provides safe and sufficient management of malignant extrinsic ureteral obstruction. Resonance stent use in benign disease needs further evaluation, considering the untoward results of the present study.

Metal Stents: A New Treatment of Malignant Ureteral Obstruction

PURPOSE We report our experience with the use of metallic self-expandable and balloon expandable stents for the treatment of malignant ureteral obstruction. MATERIALS AND METHODS We treated 12 consecutive patients with malignant ureteral obstruction, for a total of 14 ureters with stents placed. We placed metallic balloon expandable stents in 6 patients and self-expandable metallic stents in the remaining 6. Mean patient age was 65 years and mean followup was 9 months (range 8 to 16). RESULTS Of the ureters 11 were patent without any additional manipulations during followup of 8 to 16 months. Secondary interventions were needed in 3 cases because of obstructive urothelial hyperplastic reaction, tumor ingrowth and local recurrence of the primary cancer invading the upper end of the stent. Two patients died 2 and 10 months after placement of the stent. CONCLUSIONS Both types of metal stents have advantages and disadvantages that must be balanced against each other when choosing the ideal device for the treatment of obstruction. Implantation of a metal self-expanding or balloon expanding stent is safe and effective for the palliative treatment of malignant ureteral obstruction in late stage cancer patients.

Ureteral Metal Stents: 10-Year Experience With Malignant Ureteral Obstruction Treatment

PURPOSE Ureteral patency in malignant ureteral obstruction cases is a therapeutic challenge. We report our long-term experience with palliative treatment for extrinsic malignant ureteral obstruction with percutaneous placement of metal mesh stents. MATERIALS AND METHODS From January 1996 to December 2005, 90 patients with a mean age of 59 years (range 35 to 80) with ureteral obstruction due to extrinsic ureteral compression and/or encasement by primary or metastatic tumors, or retroperitoneal lymphadenopathy underwent implantation of self-expandable metal mesh stents. A total of 119 ureters were managed. Followup included urinalysis, blood biochemistry tests and transabdominal ultrasound or intravenous urography. RESULTS The technical success rate of percutaneous antegrade insertion of ureteral self-expandable metal mesh stents was 100%. Renal biochemistry normalized and hydronephrosis gradually resolved 1 to 2 weeks after stent insertion. Median followup was 15 months (range 8 to 38). Hyperplastic reaction and/or encrustation, or tumor ingrowth developed in 45 stents. Secondary intervention, such as repeat balloon dilation and coaxial stenting, was done to improve patency. Migration was observed in 13 metal stents. The primary and secondary patency rates during followup were 51.2% and 62.1%, respectively. A double pigtail or external-internal stent was inserted in 45 cases in which secondary interventions did not ensure patency. CONCLUSIONS Internal drainage of extrinsic malignant ureteral obstruction with metal mesh stents provides long-term decompression of the upper urinary tract in select cases. Certain problems limit the application of metal mesh stents in the ureter. Further studies are warranted to identify independent predictors of ureteral patency after the application of metal stents for malignant obstruction.

Externally coated ureteral metallic stents: an unfavorable clinical experience.

Abstract Objective: The purpose of the present study was to evaluate the use of externally coated stents in patients with malignant ureteral obstruction. Materials and Methods: We have prospectively evaluated 16 patients, 10 men and 6 women, with malignant ureteral obstruction treated successfully by placement of Passager metal stents (Boston Scientific, Natick, MA, USA) bypassing the stricture. Mean patient age was 65.6 years (range 62–78 years). Ureteral patency was confirmed 24 and 48 hours by injection of contrast material through the nephrostomy tube, and after patency confirmation the nephrostomy catheter was removed. Results: All stents were positioned successfully, and the postoperative course was uneventful. In 13 cases (81.2%) the prostheses finally migrated into the bladder hindering overall ureteral patency (mean time of migration: 1.5 months). Patency was achieved in the remaining ureters ( n =3), during the follow-up period (mean: 8 months, range 6–16 months), without any need for further intervention. Conclusion: The inappropriate anchorage and the increased ureteral peristalsis are the main causes of migration towards the bladder, thus, minimizing the usefulness of this stent for the treatment of ureteral strictures.

URETEROILEAL ANASTOMOTIC STRICTURES: AN INNOVATIVE APPROACH WITH METALLIC STENTS

PURPOSE We report our experience with the use of self-expandable metallic stents to bypass anastomotic strictures after ureteroileal urinary diversion. MATERIALS AND METHODS We evaluated 3 men and 1 woman with invasive bladder carcinoma who underwent radical cystectomy and ileal conduit urinary diversion. Ureteroenteric anastomotic strictures developed after a mean of 16 months. Self-expandable metallic stents were successfully placed (bilaterally in 2) comprising 6 stented ureters that bypassed strictures. Mean patient age was 64 years and mean followup was 12 months. RESULTS No restenosis was observed in 3 patients during followup. The stricture recurred 1 month after stent placement in the remaining patient and additional intervention was necessary, consisting of placement of a totally coaxial overlapping metal stent. No sepsis or other complication was observed. One patient died of metastatic disease 12 months after stent placement. CONCLUSIONS We propose the use of metal stents as an adequate, safe and effective alternative treatment for anastomotic strictures after ureteroileal diversion.

Ureteral stents: new ideas, new designs:

Ureteral stents represent a minimally invasive alternative to preserve urinary drainage whenever ureteral patency is deteriorated or is under a significant risk to be occluded due to extrinsic or intrinsic etiologies. The ideal stent that would combine perfect long-term efficacy with no stent-related morbidity is still lacking and stent usage is associated with several adverse effects that limit its value as a tool for long-term urinary drainage. Several new ideas on stent design, composition material and stent coating currently under evaluation, foreseen to eliminate the aforementioned drawbacks of ureteral stent usage. In this article we review the currently applied novel ideas and new designs of ureteral stents. Moreover, we evaluate potential future prospects of ureteral stent development adopted mostly by the pioneering cardiovascular stent industry, focusing, however, on the differences between ureteral and endothelial tissue.

Percutaneous minimally invasive management of iatrogenic ureteral injuries.

PURPOSE To present experience with the percutaneous management of iatrogenic ureteral injuries. PATIENTS AND METHODS Eighteen women and six men with a mean age of 59.3 years (range 33-80 years) received a diagnosis of ureteral injury sustained during gynecologic, urologic, and general surgical procedures. In a total of 25 injured ureters, 12 had interruption of continuity of their lumen, 10 were associated with contrast extravasation, and 3 were related to both. A standard percutaneous nephrostomy tract was established on the side of the afflicted kidney. Combined use of hydrophilic guidewires and balloon dilations were performed to achieve antegrade recanalization of the ureteral lesion. Then, a ureteral stent was inserted to assure patency. RESULTS Average stricture length was 1.21 (range 0.5-1.9 cm). Success of the aforementioned technique was possible in 18 ureters. Successful management in one session took place in 14 ureters. Average hospitalization time was 1.8 days (range 0-5 d). The follow-up period ranged between 12 and 18 months, with mean follow-up time of 12.9 months. Ureteral patency was evident at 1 week follow-up in six patients with obstructed ureters. In the remaining patients, balloon dilation of the stricture was repeated, and another stent was placed. Extravasation of contrast was observed in two patients with extravasating ureters in the same period. Nephrostomy tubes were removed after a mean indwelling period of 5.9 weeks (range 1-12 wks). Two patients treated by the described method died during their hospitalization in the intensive care unit because of sepsis from peritonitis that was related to colon injury and multiple concomitant injuries. Major complications were not observed in the remaining 22 patients during the follow-up period. CONCLUSION The minimally invasive management of ureteral injuries is a safe and efficient method for both ureteral obstruction and/or laceration in a wide range of iatrogenic ureteral injuries.

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.

Ureteral stents: past, present and future.

For three decades, intraureteral tubular devices have been used to maintain ureteral patency. The contribution of stents to modern urology is invaluable, since these devices are closely associated with everyday urologic practice. Polymeric stents represent the most commonly used type of stent, while metal stents are indicated in selected cases. Nevertheless, several problems have been observed related to the use of stents. Constant development of new biomaterials, together with improvements in design, attempts to overcome any stent-related adverse events.