Design and evaluation of a modular multimodality imaging phantom to simulate heterogeneous uptake and enhancement patterns for radiomic quantification in hybrid imaging: A feasibility study.

BACKGROUND: Accuracy and precision assessment in radiomic features is important for the determination of their potential to characterize cancer lesions. In this regard, simulation of different imaging conditions using specialized phantoms is increasingly being investigated. In this study, the design and evaluation of a modular multimodality imaging phantom to simulate heterogeneous uptake and enhancement patterns for radiomics quantification in hybrid imaging is presented. METHODS: A modular multimodality imaging phantom was constructed that could simulate different patterns of heterogeneous uptake and enhancement patterns in positron emission tomography (PET), single-photon emission computed tomography (SPECT), computed tomography (CT), and magnetic resonance (MR) imaging. The phantom was designed to be used as an insert in the standard NEMA-NU2 IEC body phantom casing. The entire phantom insert is composed of three segments, each containing three separately fillable compartments. The fillable compartments between segments had different sizes in order to simulate heterogeneous patterns at different spatial scales. The compartments were separately filled with different ratios of 99m Tc-pertechnetate, 18 F-fluorodeoxyglucose ([18 F]FDG), iodine- and gadolinium-based contrast agents for SPECT, PET, CT, and T1 -weighted MR imaging respectively. Image acquisition was performed using standard oncological protocols on all modalities and repeated five times for repeatability assessment. A total of 93 radiomic features were calculated. Variability was assessed by determining the coefficient of quartile variation (CQV) of the features. Comparison of feature repeatability at different modalities and spatial scales was performed using Kruskal-Wallis-, Mann-Whitney U-, one-way ANOVA- and independent t-tests. RESULTS: Heterogeneous uptake and enhancement could be simulated on all four imaging modalities. Radiomic features in SPECT were significantly less stable than in all other modalities. Features in PET were significantly less stable than in MR and CT. A total of 20 features, particularly in the gray-level co-occurrence matrix (GLCM) and gray-level run-length matrix (GLRLM) class, were found to be relatively stable in all four modalities for all three spatial scales of heterogeneous patterns (with CQV < 10%). CONCLUSION: The phantom was suitable for simulating heterogeneous uptake and enhancement patterns in [18 F]FDG-PET, 99m Tc-SPECT, CT, and T1 -weighted MR images. The results of this work indicate that the phantom might be useful for the further development and optimization of imaging protocols for radiomic quantification in hybrid imaging modalities.

Minimum 24-month followup of the sling for the treatment of stress urinary incontinence.

PURPOSE: The SPARC procedure is a retropubic approach for the placement of a synthetic polypropylene sling for stress urinary incontinence. Although the approach appears to be efficacious, there still exist limited long-term data. We report our experience with SPARC at a minimum followup of 24 months. MATERIALS AND METHODS: Patients with stress urinary incontinence undergoing a SPARC sling procedure were entered into a prospective, institutional review board approved database. Postoperatively patients were asked to complete quality of life questionnaires at 6 months and annually thereafter. Success was defined by questionnaire response of 1 or fewer stress urinary incontinence episode per week or greater than 70% subjective improvement in those with greater than 1 stress urinary incontinence episodes per week. RESULTS: A total of 307 patients were identified during a 5-year period, of whom 280 were more than 24 months from surgery. Of the patients 154 (55%) had questionnaire followup at 24 months or greater from surgery (mean 36, median 36, range 24 to 49). Mean Valsalva leak point pressure in this subset of patients was 66 cm H(2)O (median 63, range 15 to 175). Of the patients 106 (68.8%) reported 1 or greater stress urinary incontinence episodes per week and 11 (7.1%) reported greater than 70% subjective improvement despite greater than 1 stress urinary incontinence episodes per week. Based on these definitions 75.9% of the cases were considered successful. CONCLUSIONS: The antegrade polypropylene mid urethral sling appears effective and most patients are satisfied with the outcome. The ease and minimally invasive nature of this technique does not preclude significant complications. Nevertheless, results in this series are competitive with those of other available surgical options.

Initial experience with rectocele repair using nonfrozen cadaveric fascia lata interposition.

OBJECTIVES: To describe a rectocele repair reinforced with solvent-dehydrated, gamma-irradiated, human fascia lata and report our early results with a technique we are confident will have a greater, more durable success rate, with a lower incidence of dyspareunia, than the classic repair. METHODS: A total of 73 patients, aged 31 to 86 years, with symptomatic (stool trapping and/or vaginal/perineal splinting or postural modifications to facilitate stool evacuation) rectoceles underwent a site-specific repair reinforced with cadaveric fascia. Perioperative questionnaires, retrospective chart review, and telephone interview by a blinded third-party reviewer and physical examination was conducted. Issues thought to be relevant to the rectocele repair were assessed. RESULTS: Of the 73 patients, 62 responded to the postoperative questionnaire and 50 underwent physical examination. The mean follow-up was 13.7 months (range 6 to 23). Of the 62 patients, 52 (93.6%) denied postoperative stool trapping requiring vaginal/perineal splinting. Of the 39 sexually active patients, 4 (10.3%) experienced de novo dyspareunia. Minor complications were seen in 15 patients (24%). One developed a symptomatic enterocele. CONCLUSIONS: Interposition of cadaveric fascia lata avoids dependence on weakened native rectovaginal support to facilitate the rectocele repair. Our technique uses fascial interposition, rather than obliteration of the defect, preventing vaginal narrowing, and should thereby decrease the incidence of dyspareunia. Patient symptom improvement and satisfaction rates were competitive with those after traditional rectocele repair. Follow-up is ongoing with the hope that the fascial reinforcement will translate into more durable results.

Incidence and management of abdominal sacrocolpopexy mesh erosions.

OBJECTIVE: This study was undertaken to evaluate the occurrence and management of mesh erosions in patients undergoing abdominal sacrocolpopexy. STUDY DESIGN: A retrospective chart review of the abdominal sacrocolpopexy procedure (n = 92) between 1997 and 2003 was performed. Patients with mesh erosion were identified. Incidence by graft type and treatment required for erosion resolution was analyzed with chi 2 and Fisher exact test. RESULTS: Erosions occurred in 7.6 % (7/92). Erosions were identified only in patients with Gore-Tex (3/33, 9%) or silicone-coated mesh (4/21, 19%) compared with none of 38 patients with polypropylene mesh (n = 24) or fascia (n = 14) grafts ( P = .068.). Partial excision of exposed graft resolved all 3 Gore-Tex erosions, compared with none of the silicone-coated mesh erosions ( P = .03). Complete graft removal was required to resolve silicone-coated mesh erosions. CONCLUSION: We observed a high rate of erosion with Gore-Tex and silicone-coated mesh. Partial graft excision was adequate for Gore-Tex erosions, but complete graft removal was necessary to resolve erosions associated with silicone-coated mesh.

High complication rate identified in sacrocolpopexy patients attributed to silicone mesh.

OBJECTIVES: To report on our experience using a preconfigured Y-shaped silicone-coated polyester mesh and polypropylene mesh for vaginal vault suspension. A variety of materials have been used for both open and laparoscopic sacrocolpopexy in the management of vaginal vault prolapse. Recently, a preconfigured Y-shaped silicone-coated polyester mesh was introduced to facilitate the vaginal cuff suspension to the sacrum. METHODS: We reviewed the data of 45 consecutive patients who underwent abdominal (n = 28) or laparoscopic (n = 17) sacrocolpopexy. Of the 45 patients, 21 underwent silicone mesh suspension of the vaginal cuff to the anterior sacrum, with a mean follow-up of 23 months (range 16 to 41). A comparative analysis was performed of 24 patients who underwent the same procedure with polypropylene mesh. RESULTS: Of the 21 patients in the silicone group, 5 (23.8%) have had a major complication (four vaginal mesh erosions and one mesh infection) after a median follow-up of 9.5 months (range 4 to 20). The presenting symptoms were persistent or new vaginal discharge and/or nonspecific pelvic pain. One patient underwent successful removal of the mesh transvaginally, but the rest required abdominal exploration. To date, the 24 patients who underwent vaginal cuff suspension with polypropylene mesh have had no vaginal mesh extrusions or infections, with a mean follow-up of 12 months (range 1 to 38). CONCLUSIONS: Silicone-coated polyester mesh has recently been associated with a high rate of vaginal erosion when used as a transvaginal suburethral sling. Our experience specifically with vaginal vault suspension corroborates this. We have abandoned the use of silicone mesh because of the unacceptably high extrusion rate and presently use polypropylene mesh.

Nephrolithiasis and nephrocalcinosis in rats with small bowel resection.

Intestinal resection (IR) may lead to hyperoxaluria and nephrolithiasis. A rat model of IR was developed, in which kidney stones form. We describe the urine chemistries and histopathologic features. Rats underwent resection of 40-45 cm of distal ileum (n=16) or sham resection (SR) (n=8), and were then fed a 1% Na oxalate, 0.02% Ca diet. After 1 week on the diet, 24 h urine samples were obtained for stone chemistries. At 4-7 months after surgery, kidneys were examined grossly and by light microscopy. The extent and location of crystallization was assessed by polarized light. Histochemistry and infrared spectroscopy were used to determine crystal composition. IR rats had higher urine oxalate excretion (P<0.01) and concentration (P<0.001) than SR rats, and lower urine citrate excretion; only IR rats formed kidney stones (12/15 surviving rats). Tissue calcification was found only in kidneys from IR rats, located in the cortex (83% of kidneys), medulla (73%) and papillary tip (47%). Crystals, composed of CaOx, apatite, and calcium carbonate, filled collecting duct lumens, and were associated with tubular obstruction, and interstitial inflammation. Crystals in the papillary interstitium incited inflammation with tubular destruction and development of progressive papillary erosion. This new rat model of nephrolithiasis and nephrocalcinosis resembles the pattern of urinary abnormalities and tissue calcification that may be seen in humans with small bowel resection. The model allows further studies of the mechanisms of renal crystal formation, and possible therapeutic interventions.

Urethral substitution using an intestinal free flap: a novel approach.

PURPOSE: Patients who have extensive stricture disease, those in whom hypospadias repair fails and those who sustain significant urethral trauma pose a reconstructive challenge for genitourinary surgeons. We developed an additional reconstructive option for men with a severely diseased urethra when grafting procedures and local tissue flaps have failed or are otherwise contraindicated. MATERIALS AND METHODS: A genitourinary reconstructive team performed novel intestinal free flap substitution urethroplasty in 2 patients. A segment of jejunum is harvested on a vascular pedicle and plicated into an appropriate size urethral substitute. Microvascular anastomoses allow this segment to remain viable and functional. The technical aspects of repair and surgical considerations are detailed. RESULTS: The 2 patients have a satisfactory functional and cosmetic outcome. At short followup the urethral lumen remained patent and the intestinal urethra remained viable and intact. Both patients have good urinary streams and are able to void in the standing position. CONCLUSIONS: This initial experience in 2 patients indicates that intestinal segment urethral substitution may be considered within the reconstructive armamentarium of genitourinary surgeons when more conventional options have failed or are contraindicated. Continued vigilant followup is necessary to detail any secondary complications. In addition, further experience with this technique by other surgeons would help determine its overall usefulness.

Prospective evaluation of ureteral stent durability in patients with chronic ureteral obstruction.

OBJECTIVES: To prospectively evaluate the durability of ureteral stents in patients with chronic ureteral obstruction. METHODS: Twenty-nine renal units from 22 patients with known chronic ureteral obstruction treated with indwelling ureteral stents were studied at 3, 6, 9, and 12 months after initial stent placement (7 to 8F Percuflex) by abdominal x-ray, serum creatinine, and renal and bladder ultrasonography. Renal ultrasound scans were performed by a single senior radiologist with specific attention paid to any increase in hydronephrosis and to the presence of ureteral jets. The stent was changed when calcifications were seen along the stent on abdominal x-ray, if an increase in serum creatinine occurred, or if any increase in hydronephrosis or absence of ureteral jets was seen on ultrasonography. In addition, the stents were changed if new-onset flank pain and/or pyelonephritis developed. If none of the above occurred, the stents were changed after 12 months. RESULTS: Two patients died of metastatic cancer, leaving 25 renal units available for follow-up. The mean and median time to stent change were 6 months. At 3, 6, 9, and 12 months, the number of renal units that did not meet the criteria warranting stent change was 18 (72%), 12 (48%), 6 (24%), and 2 (8%), respectively. Only 2 (8%) of 25 renal units did not meet any exclusion criteria at 12 months. The most common reasons for requiring the stent to be changed were new-onset flank pain in 8 (35%), an increase in serum creatinine in 7 (30%), and new-onset or increased hydronephrosis in 7 (30%). No criteria were useful in predicting how long stents could be maintained in an individual patient. CONCLUSIONS: The stents were maintained for more than 6 months in 12 (48%) of 25 renal units. However, very few patients were able to maintain chronic ureteral stents for 12 months without requiring stent change based on our criteria.

Artificial urinary sphincter placement in men after cystectomy with orthotopic ileal neobladder: continence, complications, and quality of life.

OBJECTIVES: To review our experience regarding the overall efficacy and safety of an artificial urinary sphincter (AUS) in men with stress urinary incontinence (SUI) after cystoprostatectomy with an orthotopic ileal neobladder. METHODS: We performed a retrospective review of 5 men who underwent placement of an AUS (AMS 800) for severe SUI after radical cystectomy with an orthotopic ileal neobladder. Incontinence symptoms and quality of life were quantified using two validated continence questionnaires (Urogenital Distress Inventory Short Form and Incontinence Impact Questionnaire Short Form) and a brief addendum questionnaire. The degree of continence, perioperative and postoperative complications and infections, symptom distress, quality of life, and patient satisfaction were compared before and after AUS placement. RESULTS: Complete (0 pads per day) or social (1 pad or less per day) continence was reported in 5 of 5 patients after AUS placement. The average pad usage significantly decreased from 6.2 to 0.6 per day (P <0.001). No significant perioperative or postoperative complications or infections were noted. Symptom distress, quality of life, and patient satisfaction were significantly improved after AUS placement (P < 0.01, < 0.0001, and < 0.001, respectively). CONCLUSIONS: With short-term follow-up and a limited number of patients, the placement of an AUS for treatment of SUI after bladder substitution is well tolerated and reliable and has a positive impact on patients' quality of life.