Dual-energy CT for the evaluation of urinary calculi: image interpretation, pitfalls and stone mimics

Urolithiasis is a common disease with a reported prevalence between 4% and 20% in developed countries. Determination of urinary calculi composition is a key factor in preoperative evaluation, treatment, and stone recurrence prevention. Prior to the introduction of dual-energy computed tomography (DECT), available methods for determining urinary stone composition were only available after stone extraction, and thereby unable to aid in optimized stone management prior to intervention. DECT utilizes the attenuation difference produced by two different x-ray energy spectra to quantify urinary calculi composition as uric acid or non-uric acid (with likely further classification in the future) while still providing the information attained with a conventional CT. Knowledge of DECT imaging pitfalls and stone mimics is important, as the added benefit of dual-energy analysis is the determination of stone composition, which in turn affects all aspects of stone management. This review briefly describes DECT principles, scanner types and acquisition protocols for the evaluation of urinary calculi as they relate to imaging pitfalls (inconsistent characterization of small stones, small dual-energy field of view, and mischaracterization from surrounding material) and stone mimics (drainage devices) that may adversely impact clinical decisions. We utilize our clinical experience from scanning over 1200 patients with this new imaging technique to present clinically relevant examples of imaging pitfalls and possible mechanisms for resolution.

Update on contemporary management of clinically localized renal cell carcinoma

Renal cell carcinoma (RCC) continues to increase in incidence with the largest increase manifesting in small, organ-confined tumors. This review outlines the epidemiology and current data pertaining to the management of clinically-localized RCC. In this manuscript, the current data outlining the benefit of nephron sparing to the overall survival of the patient is described. The data pertaining to minimally invasive nephron sparing is also explained in detail. From laparoscopic and robotic partial nephrectomy to watchful waiting and percutaneous ablation, the urologist is continually assaulted with new data for the management of clinically-localized RCC. The data can be confusing, and much of it is conflicting. The addition of new scoring systems or nomograms may aid in predicting which therapy would be most beneficial in certain patient groups. New scoring systems may also predict the difficulty of surgical resection and predict surgical complications. The limitations of the data pertaining to the management of clinically-localized RCC are also outlined.

Robotic assisted laparoscopic pyeloplasty

Dismembered pyeloplasty is the gold standard treatment for adult ureteropelvic junction obstruction with published success rates consistently over 90%. The morbidity of the open flank incision required for dismembered pyeloplasty led to experimentation with other less invasive modalities such as endopyelotomy and laparoscopic techniques. Modern laparoscopic pyeloplasty series demonstrate success rates equivalent to those of their open counterparts with improved postoperative convalescence. The requirement of complex intracorporeal reconstruction has limited widespread application of laparoscopic pyeloplasty. The daVinci surgical robotic platform offers features that improve intracorporeal reconstruction and suturing thereby flattening the learning curve of laparoscopic pyeloplasty for residents, fellows, and novice laparoscopists. Multiple variations in robotic technique exist but short term outcomes and convalescence appear equivalent to open and laparoscopic pyeloplasty. Complications related to robotic assisted laparoscopic pyeloplasty are minimal and usually self-limiting. The indications for robotic pyeloplasty have expanded to include difficult cases such as those who have failed previous therapy for ureteropelvic junction obstruction including failed endopyelotomy or previous pyeloplasty. The appeal of robotic technology is tempered somewhat by its high cost compared to standard laparoscopic techniques but it is hoped that overall costs will decrease with time.

Inclusion cyst and graft contraction in Tutoplast human cadeveric pericardium following Peyronie's grafting: a previously unreported complication

Tutoplast human cadaveric pericardium has been utilized safely and successfully in numerous series of tunica albuginea grafting for Peyronie's curvature without reported rejection, cyst formation, or foreign body reaction. We describe a previously unreported complication of inclusion cyst formation and graft contraction in a 40-year-old white male following Tutoplast human cadaveric pericardial graft surgical correction of Peyronie's curvature. The complication was successfully treated with surgical graft excision and replacement with autologous temporalis fascia.

Utility of magnetic resonance imaging in evaluating inflatable penile prosthesis malfunction and complaints

The introduction of oral pharmacotherapy dramatically changed practice patterns in erectile dysfunction. The direct effect was to decrease the numbers of patients seeking penile implants; an indirect effect has been the changing ratio of new, to re-do operations. Patients seeking replacement inflatable penile prosthesis (IPP) surgery pose challenges both in diagnosis and management; in very select cases preoperative MRI can be useful in the evaluation of the patient's complaint and in planning operative management. Imaging can supplement the physical exam; in certain cases imaging will reveal: crural herniation, corporal distortion, corporal fibrosis, and hardware migration. Inflatable penile prosthesis has a high rate of satisfaction for patients (89%) and partners (70%). The principal reasons for dissatisfaction are penile shortening, pain and frustration with reoperation. If pain is not due to infection, it may be secondary to malpositioning, improper sizing, cylinder cross-overs, or herniation. After one or more reoperations, penile distortion may occur secondary to tunica albugenia thinning or fibrosis. A series of cases will be presented to highlight the utility of MRI for IPP problems, define normal appearance and abnormal appearance of penile hardware. Careful collaboration between the Urologist and Radiologist in the review and final dictation of these cases is warranted to properly document problems and to plan device replacement/penile reconstruction.