Role of bowel suspension technique to prevent early intestinal obstruction after radical cystectomy with ileal orthotopic neobladder: A retrospective cohort study.

OBJECTIVE: We investigate the impact of the bowel suspension technique (BST) on paralytic ileus and early intestinal obstruction (≤60days) after radical cystectomy (RC) with ileal orthotopic neobladder (IONB). METHODS: We retrospectively reviewed 310 patients who underwent RC with IONB for bladder cancer between 2001 and 2017. After forming the Studer IONB, ileal continuity was restored by side-to-side stapled anastomosis. Then, we suspended stapled anastomotic portion of bowel on the posterior peritoneum not to fall into the pelvic cavity. The clinicopathologic characteristics of patients were examined and the onset of paralytic ileus and early intestinal obstruction were identified. Logistic regression analysis was used to identify predictors associated with paralytic ileus and early intestinal obstruction. RESULTS: Of the 310 total patients, paralytic ileus and early intestinal obstruction were identified in 100 (32.3%) and 15 (4.8%), respectively. When patients were divided into two groups (BST [-] vs. BST [+]), the rates of paralytic ileus were not significantly different (64/205[31.2%] vs. 36/105[34.3%], P = 0.585). However, early intestinal obstruction that required surgical treatment was significantly decreased (14/205[6.8%] vs. 1/105[1.0%], P = 0.024). On multivariate analysis, older age was commonly associated with paralytic ileus and early intestinal obstruction (P = 0.008 and P = 0.016). BST was inversely associated with early intestinal obstruction (95% CI: 0.01-0.85, P = 0.034), but not related to paralytic ileus. CONCLUSION: BST significantly reduced early intestinal obstruction without increasing paralytic ileus after RC with IONB. BST could be used as useful technique to reduce severe bowel complications.

Cluster analysis identifies three urodynamic patterns in patients with orthotopic neobladder reconstruction.

PURPOSE: To classify patients with orthotopic neobladder based on urodynamic parameters using cluster analysis and to characterize the voiding function of each group. MATERIALS AND METHODS: From January 2012 to November 2015, 142 patients with bladder cancer underwent radical cystectomy and Studer neobladder reconstruction at our institute. Of the 142 patients, 103 with complete urodynamic data and information on urinary functional outcomes were included in this study. K-means clustering was performed with urodynamic parameters which included maximal cystometric capacity, residual volume, maximal flow rate, compliance, and detrusor pressure at maximum flow rate. Three groups emerged by cluster analysis. Urodynamic parameters and urinary function outcomes were compared between three groups. RESULTS: Group 1 (n = 44) had ideal urodynamic parameters with a mean maximal bladder capacity of 513.3 ml and mean residual urine volume of 33.1 ml. Group 2 (n = 42) was characterized by small bladder capacity with low compliance. Patients in group 2 had higher rates of daytime incontinence and nighttime incontinence than patients in group 1. Group 3 (n = 17) was characterized by large residual urine volume with high compliance. When we examined gender differences in urodynamics and functional outcomes, residual urine volume and the rate of daytime incontinence were only marginally significant. However, females were significantly more likely to belong to group 2 or 3 (P = 0.003). In multivariate analysis to identify factors associated with group 1 which has the most ideal urodynamic pattern, age (OR 0.95, P = 0.017) and male gender (OR 7.57, P = 0.003) were identified as significant factors. CONCLUSIONS: While patients with ileal neobladder present with various voiding symptoms, three urodynamic patterns were identified by cluster analysis. Approximately half of patients had ideal urodynamic parameters. The other two groups were characterized by large residual urine and small capacity bladder with low compliance. Young age and male gender appear to have a favorable impact on urodynamic and voiding outcomes in patients undergoing orthotopic neobladder reconstruction.

Proof-of-concept prototype time-of-flight PET system based on high-quantum-efficiency multianode PMTs.

PURPOSE: Time-of-flight (TOF) information in positron emission tomography (PET) scanners enhances the diagnostic power of PET scans owing to the increased signal-to-noise ratio of reconstructed images. There are numerous additional benefits of TOF reconstruction, including the simultaneous estimation of activity and attenuation distributions from emission data only. Exploring further TOF gains by using TOF PET scanners is important because it can broaden the applications of PET scans and expand our understanding of TOF techniques. Herein, we present a prototype TOF PET scanner with fine-time performance that can experimentally demonstrate the benefits of TOF information. METHODS: A single-ring PET system with a coincidence resolving time of 360 ps and a spatial resolution of 3.1/2.2 mm (filtered backprojection/ordered-subset expectation maximization) was developed. The scanner was based on advanced high-quantum-efficiency (high-QE) multianode photomultiplier tubes (PMTs). The impact of its fine-time performance was demonstrated by evaluating body phantom images reconstructed with and without TOF information. Moreover, the feasibility of the scanner as an experimental validator of TOF gains was verified by investigating the improvement of images under various conditions, such as the use of joint estimation algorithms of activity and attenuation, erroneous data correction factors (e.g., without normalization correction), and incompletely sampled data. RESULTS: The prototype scanner showed excellent performance, producing improved phantom images, when TOF information was employed in the reconstruction process. In addition, investigation of the TOF benefits using the phantom data in different conditions verified the usefulness of the developed system for demonstrating the practical effects of TOF reconstruction. CONCLUSIONS: We developed a prototype TOF PET scanner with good performance and a fine-timing resolution based on advanced high-QE multianode PMTs and demonstrated its feasibility as an experimental validator of TOF gains, suggesting its usefulness for investigating new applications of PET scans and clarifying TOF techniques in detail.

Risk Factors for Developing Metabolic Acidosis after Radical Cystectomy and Ileal Neobladder.

PURPOSE: To investigate the serial changes of metabolic acidosis and identify associated risk factors in patients who underwent radical cystectomy and ileal neobladder. MATERIAL AND METHODS: From January 2010 to August 2014, 123 patients who underwent radical cystectomy and ileal neobladder reconstruction for bladder cancer were included in this study. Metabolic acidosis was defined as a serum bicarbonate level less than 22 mEq/L and impaired renal function was defined as a GFR <50ml/min. The presence of metabolic acidosis was evaluated at 1 month, 1 year, and 2 years after surgery. Multivariate logistic regression analysis was conducted to identify risk factors associated with development of metabolic acidosis. RESULTS: Metabolic acidosis was observed in 52%, 19.5%, and 7.3% of patients at 1 month, 1 year, and 2 years after surgery, respectively. At 1 month after surgery, impaired renal function was the only independent risk factor associated with metabolic acidosis (OR 3.87, P = 0.046). At 1 year after surgery, diabetes was the only independent risk factor associated with metabolic acidosis (OR 5.68, P = 0.002). At 2 years post-surgery, both age and diabetes were significant risk factors associated with metabolic acidosis. CONCLUSION: Approximately, half of patients experienced metabolic acidosis one month after ileal neobladder reconstruction. Preoperative impaired renal function was the most significant risk factor for developing metabolic acidosis in the early postoperative period. However, the incidence of metabolic acidosis decreased to less than 20% 1 year after surgery, and diabetes was an independent risk factor during this period.

Febrile Urinary Tract Infection after Radical Cystectomy and Ileal Neobladder in Patients with Bladder Cancer.

Urinary tract infection (UTI) is one of the most common complications after radical cystectomy and orthotopic neobladder reconstruction. This study investigated the incidence and implicated pathogen of febrile UTI after ileal neobladder reconstruction and identify clinical and urodynamic parameters associated with febrile UTI. From January 2001 to May 2015, 236 patients who underwent radical cystectomy and ileal neobladder were included in this study. Fifty-five episodes of febrile UTI were identified in 46 patients (19.4%). The probability of febrile UTI was 17.6% and 19.8% at 6 months and 24 months after surgery, respectively. While, Escherichia coli was the most common implicated pathogen (22/55, 40.0%), Enterococcus spp. were the most common pathogen during the first month after surgery (18/33, 54.5%). In multivariate logistic regression analysis, ureteral stricture was an independent risk factor associated with febrile UTI (OR 5.93, P = 0.023). However, ureteral stricture accounted for only 6 episodes (10.9%, 6/55) of febrile UTI. Most episodes of febrile UTI occurred within 6 months after surgery. Thus, to identify risk factors associated with febrile UTI in the initial postoperative period, we assessed videourodynamics within 6 months after surgery in 38 patients. On videourodyamic examination, vesicoureteral reflux (VUR) was identified in 16 patients (42.1%). The rate of VUR presence in patients who had febrile UTI was not significantly different from those in patients without febrile UTI (50% vs. 39.3%, P = 0.556). Patients with febrile UTI had significantly larger residual urine volume (212.0 ± 193.7 vs. 90.5 ± 148.2, P = 0.048) than those without. E. coli and Enterococcus spp. are common pathogens and ureteral stricture and residual urine are risk factors for UTI after ileal neobladder reconstruction.

Simultaneous Multiparametric PET/MRI with Silicon Photomultiplier PET and Ultra-High-Field MRI for Small-Animal Imaging.

UNLABELLED: Visualization of biologic processes at molecular and cellular levels has revolutionized the understanding and treatment of human diseases. However, no single biomedical imaging modality provides complete information, resulting in the emergence of multimodal approaches. Combining state-of-the-art PET and MRI technologies without loss of system performance and overall image quality can provide opportunities for new scientific and clinical innovations. Here, we present a multiparametric PET/MR imager based on a small-animal dedicated, high-performance, silicon photomultiplier (SiPM) PET system and a 7-T MR scanner. METHODS: A SiPM-based PET insert that has the peak sensitivity of 3.4% and center volumetric resolution of 1.92/0.53 mm(3) (filtered backprojection/ordered-subset expectation maximization) was developed. The SiPM PET insert was placed between the mouse body transceiver coil and gradient coil of a 7-T small-animal MRI scanner for simultaneous PET/MRI. Mutual interference between the MRI and SiPM PET systems was evaluated using various MR pulse sequences. A cylindric corn oil phantom was scanned to assess the effects of the SiPM PET on the MR image acquisition. To assess the influence of MRI on the PET imaging functions, several PET performance indicators including scintillation pulse shape, flood image quality, energy spectrum, counting rate, and phantom image quality were evaluated with and without the application of MR pulse sequences. Simultaneous mouse PET/MRI studies were also performed to demonstrate the potential and usefulness of the multiparametric PET/MRI in preclinical applications. RESULTS: Excellent performance and stability of the PET system were demonstrated, and the PET/MRI combination did not result in significant image quality degradation of either modality. Finally, simultaneous PET/MRI studies in mice demonstrated the feasibility of the developed system for evaluating the biochemical and cellular changes in a brain tumor model and facilitating the development of new multimodal imaging probes. CONCLUSION: We developed a multiparametric imager with high physical performance and good system stability and demonstrated its feasibility for small-animal experiments, suggesting its usefulness for investigating in vivo molecular interactions of metabolites, and cross-validation studies of both PET and MRI.

Evaluation of a silicon photomultiplier PET insert for simultaneous PET and MR imaging.

PURPOSE: In this study, the authors present a silicon photomultiplier (SiPM)-based positron emission tomography (PET) insert dedicated to small animal imaging with high system performance and robustness to temperature change. METHODS: The insert consists of 64 LYSO-SiPM detector blocks arranged in 4 rings of 16 detector blocks to yield a ring diameter of 64 mm and axial field of view of 55 mm. Each detector block consists of a 9 × 9 array of LYSO crystals (1.2 × 1.2 × 10 mm(3)) and a monolithic 4 × 4 SiPM array. The temperature of each monolithic SiPM is monitored, and the proper bias voltage is applied according to the temperature reading in real time to maintain uniform performance. The performance of this PET insert was characterized using National Electrical Manufacturers Association NU 4-2008 standards, and its feasibility was evaluated through in vivo mouse imaging studies. RESULTS: The PET insert had a peak sensitivity of 3.4% and volumetric spatial resolutions of 1.92 (filtered back projection) and 0.53 (ordered subset expectation maximization) mm(3) at center. The peak noise equivalent count rate and scatter fraction were 42.4 kcps at 15.08 MBq and 16.5%, respectively. By applying the real-time bias voltage adjustment, an energy resolution of 14.2% ± 0.3% was maintained and the count rate varied ≤1.2%, despite severe temperature changes (10-30 °C). The mouse imaging studies demonstrate that this PET insert can produce high-quality images useful for imaging studies on the small animals. CONCLUSIONS: The developed MR-compatible PET insert is designed for insertion into a narrow-bore magnetic resonance imaging scanner, and it provides excellent imaging performance for PET/MR preclinical studies.

Effect of Tamsulosin in Lower Urinary Tract Symptom Patients With Metabolic Syndrome.

OBJECTIVE: To investigate the efficacy of tamsulosin, a selective alpha-1 blocker, in lower urinary tract symptoms (LUTS) patients with metabolic syndrome (MS). PATIENTS AND METHODS: This prospective, multicenter clinical trial included men and women (20-75 years old) with LUTS, with or without MS. Patients were categorized as MS+ or MS-, respectively, and all of them were administered tamsulosin 0.2 mg per oral once daily for 24 weeks. Patients were assessed based on the International Prostate Symptom Score, King's Health Questionnaire (KHQ), Overactive Bladder Questionnaire, uroflowmetry with postvoid residuals, and MS factors (blood pressure, waist-to-hip ratio, and serum levels of fasting blood glucose, triglyceride, and high-density lipoprotein cholesterol) at baseline and at 4, 12, and 24 weeks of treatment. RESULTS: Ninety-two patients were enrolled in this study (53/92 were MS- [57.6%]; 39/92 were MS+ [42.4%]). After 24 weeks of tamsulosin treatment, fasting blood glucose (P = .02) and triglyceride (P < .001) levels of changes were significantly greater in the MS+ group than in the MS- group. Total International Prostate Symptom Score, total Overactive Bladder Questionnaire score, and the scores of each question on the KHQ showed significant improvement after treatment without intergroup differences. In KHQ, although improvements in emotional status, sleep quality, fatigue, and personal distress were greater in the MS+ group (P = .05), the difference between the groups did not reach statistical significance. CONCLUSION: Tamsulosin was effective in both LUTS patients with and without MS. Furthermore, tamsulosin had beneficial effects on some of the factors associated with MS.

Dual-Phase Tapped-Delay-Line Time-to-Digital Converter With On-the-Fly Calibration Implemented in 40 nm FPGA.

This paper describes two novel time-to-digital converter (TDC) architectures. The first is a dual-phase tapped-delay-line (TDL) TDC architecture that allows us to minimize the clock skew problem that causes the highly nonlinear characteristics of the TDC. The second is a pipelined on-the-fly calibration architecture that continuously compensates the nonlinearity and calibrates the fine times using the most up-to-date bin widths without additional dead time. The two architectures were combined and implemented in a single Virtex-6 device (ML605, Xilinx) for time interval measurement. The standard uncertainty for the time intervals from 0 to 20 ns was less than 12.83 ps-RMS (root mean square). The resolution (i.e., the least significant bit, LSB) of the TDC was approximately 10 ps at room temperature. The differential nonlinearity (DNL) values were [-1.0, 1.91] and [-1.0, 1.88] LSB and the integral nonlinearity (INL) values were [-2.20, 2.60] and [-1.63, 3.93] LSB for the two different TDLs that constitute one TDC channel. During temperature drift from 10 to 50(°)C, the TDC with on-the-fly calibration maintained the standard uncertainty of 11.03 ps-RMS.

Bipolar analog signal multiplexing for position-sensitive PET block detectors.

This paper describes a block detector multiplexing technique that simplifies the extension of axial length or ring radius without employing extra data acquisition channels. The proposed multiplexing circuit (bipolar multiplexing) multiplexes block detectors by encoding the position-related signal outputs with different combinations of polarity. Accordingly, it is possible to distinguish the detectors using a shared readout channel. This method was evaluated by assessing one to 16 block detectors using four data acquisition channels and one trigger input at different count rates. The experimental results showed that the multiplexing of block detectors did not significantly degrade timing, energy or spatial performance at low count rates, while reducing the required number of data acquisition channels and wire routing density. On the other hand, the degradation was seen as total count rates of all blocks increased.

Initial results of simultaneous PET/MRI experiments with an MRI-compatible silicon photomultiplier PET scanner.

UNLABELLED: The most investigated semiconductor photosensor for MRI-compatible PET detectors is the avalanche photodiode (APD). However, the silicon photomultiplier (SiPM), also called the Geiger-mode APD, is gaining attention in the development of the next generation of PET/MRI systems because the SiPM has much better performance than the APD. We have developed an MRI-compatible PET system based on multichannel SiPM arrays to allow simultaneous PET/MRI. METHODS: The SiPM PET scanner consists of 12 detector modules with a ring diameter of 13.6 cm and an axial extent of 3.2 cm. In each detector module, 4 multichannel SiPM arrays (with 4 × 4 channels arranged in a 2 × 2 array to yield 8 × 8 channels) were coupled with 20 × 18 Lu(1.9)Gd(0.1)SiO(5):Ce crystals (each crystal is 1.5 × 1.5 × 7 mm) and mounted on a charge division network for multiplexing 64 signals into 4 position signals. Each detector module was enclosed in a shielding box to reduce interference between the PET and MRI scanners, and the temperature inside the box was monitored for correction of the temperature-dependent gain variation of the SiPM. The PET detector signal was routed to the outside of the MRI room and processed with a field programmable gate array-based data acquisition system. MRI compatibility tests and simultaneous PET/MRI acquisitions were performed inside a 3-T clinical MRI system with 4-cm loop receiver coils that were built into the SiPM PET scanner. Interference between the imaging systems was investigated, and phantom and mouse experiments were performed. RESULTS: No radiofrequency interference on the PET signal or degradation in the energy spectrum and flood map was shown during simultaneous PET/MRI. The quality of the MRI scans acquired with and without the operating PET showed only slight degradation. The results of phantom and mouse experiments confirmed the feasibility of this system for simultaneous PET/MRI. CONCLUSION: Simultaneous PET/MRI was possible with a multichannel SiPM-based PET scanner, with no radiofrequency interference on PET signals or images and only slight degradation of the MRI scans.

A novel compensation method for the anode gain non-uniformity of multi-anode photomultiplier tubes.

The position-sensitive multi-anode photomultiplier tube (MA-PMT) is widely used in high-resolution scintillation detectors. However, the anode gain nonuniformity of this device is a limiting factor that degrades the intrinsic performance of the detector module. The aim of this work was to develop a gain compensation method for the MA-PMT and evaluate the resulting enhancement in the performance of the detector. The method employs a circuit that is composed only of resistors and is placed between the MA-PMT and a resistive charge division network (RCN) used for position encoding. The goal of the circuit is to divide the output current from each anode, so the same current flows into the RCN regardless of the anode gain. The current division is controlled by the combination of a fixed-value series resistor with an output impedance that is much larger than the input impedance of the RCN, and a parallel resistor, which detours part of the current to ground. PSpice simulations of the compensation circuit and the RCN were performed to determine optimal values for the compensation resistors when used with Hamamatsu H8500 MAPMTs. The intrinsic characteristics of a detector module consisting of this MA-PMT and a lutetium-gadolinium-oxyorthosilicate (LGSO) crystal array were tested with and without the gain compensation method. In simulation, the average coefficient of variation and max/min ratio decreased from 15.7% to 2.7% and 2.0 to 1.2, respectively. In the flood map of the LGSO-H8500 detector, the uniformity of the photopeak position for individual crystals and the energy resolution were much improved. The feasibility of the method was shown by applying it to an octagonal prototype positron emission tomography scanner.

Development of small-animal PET prototype using silicon photomultiplier (SiPM): initial results of phantom and animal imaging studies.

UNLABELLED: Silicon photomultiplier (SiPM; also called a Geiger-mode avalanche photodiode) is a promising semiconductor photosensor in PET and PET/MRI because it is intrinsically MRI-compatible and has internal gain and timing properties comparable to those of a photomultiplier tube. In this study, we have developed a small-animal PET system using SiPMs and lutetium gadolinium oxyorthosilicate (LGSO) crystals and performed physical evaluation and animal imaging studies to show the feasibility of this system. METHODS: The SiPM PET system consists of 8 detectors, each of which comprises 2 × 6 SiPMs and 4 × 13 LGSO crystals. Each crystal has dimensions of 1.5 × 1.5 × 7 mm. The crystal face-to-face diameter and axial field of view are 6.0 cm and 6.5 mm, respectively. Bias voltage is applied to each SiPM using a finely controlled voltage supply because the gain of the SiPM strongly depends on the supply voltage. The physical characteristics were studied by measuring energy resolution, sensitivity, and spatial resolution. Various mouse and rat images were obtained to study the feasibility of the SiPM PET system in in vivo animal studies. Reconstructed PET images using a maximum-likelihood expectation maximization algorithm were coregistered with animal CT images. RESULTS: All individual LGSO crystals within the detectors were clearly distinguishable in flood images obtained by irradiating the detector using a (22)Na point source. The energy resolution for individual crystals was 25.8% ± 2.6% on average for 511-keV photopeaks. The spatial resolution measured with the (22)Na point source in a warm background was 1.0 mm (2 mm off-center) and 1.4 mm (16 mm off-center) when the maximum-likelihood expectation maximization algorithm was applied. A myocardial (18)F-FDG study in mice and a skeletal (18)F study in rats demonstrated the fine spatial resolution of the scanner. The feasibility of the SiPM PET system was also confirmed in the tumor images of mice using (18)F-FDG and (68)Ga-RGD and in the brain images of rats using (18)F-FDG. CONCLUSION: These results indicate that it is possible to develop a PET system using a promising semiconductor photosensor, which yielded reasonable PET performance in phantom and animal studies.

Correlations of interstitial cystitis/painful bladder syndrome with female sexual activity.

PURPOSE: We investigated how the symptoms of interstitial cystitis/painful bladder syndrome (IC/PBS) are correlated with the sexual activity of these patients. MATERIALS AND METHODS: A total of 87 patients were included in this study; 18 patients were diagnosed with IC and the other 69 had PBS. The diagnosis was made on the basis of the concept of IC/PBS proposed by the ICS in 2002. Patients were asked to fill in a Bristol female lower urinary tract symptom questionnaire, and symptoms were rated on a scale of from 1 to 4 or 5. Pearson's correlation coefficient was used to analyze the correlation of pain and urinary symptoms with quality of life and sexual activity. RESULTS: The average age of the patients was 51+/-14.7 years (range, 28-74 years). Age and vulvodynia were positively correlated with one another (r=0.232), and there was a negative correlation between age and dyspareunia (r=-0.302). Among the items regarding IC/PBS and sexual activity, frequency showed a positive correlation with vulvodynia (r=0.258) in addition to an inhibited sex life (r=0.403). Urgency showed a positive correlation with an inhibited sex life (r=0.346). Vulvodynia showed a positive correlation with an inhibited sex life (r=0.259) and dyspareunia (r=0.401). The main symptoms of IC/PBS (frequency, urgency, and pelvic pain) showed a positive correlation with almost all items related to quality of life (p<0.05). CONCLUSIONS: Frequency, urgency, and various types of pain are negatively correlated with the sexual activity of patients. This suggests that physicians should consider sexual function in the management of patients with IC/PBS.

[Relationship between job stress contents, psychosocial factors and mental health status among university hospital nurses in Korea].

OBJECTIVES: The present study was intended to assess the mental health of nurses working for university hospitals and to establish which factors determine their mental health. METHODS: Self-administered questionnaires were given to 1,486 nurses employed in six participating hospitals located in Daejeon City and Chungnam Province between July 1st and August 31st, 2006. The questionnaire items included sociodemographic, job-related, and psychosocial factors, with job stress factors (JCQ) as independent variables and indices of mental health status (PWI, SDS and MFS) as dependent variables. For statistical analysis, the Chi-square test was used for categorical variables, with hierarchical multiple regression used for determining the factors effecting mental health. The influence of psychosocial and job-related factors on mental health status was assessed by covariance structure analysis. The statistical significance was set at p<0.05. RESULTS: The factors influencing mental health status among subject nurses included sociodemographic characteristics such as age, number of hours of sleep, number of hours of leisure, and subjective health status; job-related characteristics such as status, job satisfaction, job suitability, stresses such as demands of the job, autonomy, and coworker support; and psychosocial factors such as self-esteem, locus of control and type A behavior patterns. Psychosocial factors had the greatest impact on mental health. Covariance structure analysis determined that psychosocial factors affected job stress levels and mental health status, and that the lower job stress levels were associated with better mental health. CONCLUSIONS: Based on the study results, improvement of mental health status among nurses requires the development and application of programs to manage job stress factors and/or psychosocial factors as well as sociodemographic and job-related characteristics.