Discordant pair analysis for sample efficient model evaluation.

We present a new technique for assessing the effectiveness of a classification algorithm using discordant pair analysis. This method utilizes a known performance baseline algorithm and a large unlabeled dataset with an assumed class distribution to obtain overall performance estimates by only assessing the subset of examples that the algorithms classify discordantly. Our approach offers an efficient way to evaluate the performance of an algorithm that minimizes the human adjudications needed while also maintaining precision in the evaluation and in some cases improving the evaluation quality by reducing human adjudication errors. This approach is a computationally efficient alternative to the traditional exhaustive method of performance evaluation and has the potential to improve the accuracy of performance estimates. Simulation studies show that the discordant pair method reduces the number of adjudications by over 90%, while maintaining the same level of sensitivity and specificity.

Ten-Year Review of Perioperative Complications After Transurethral Resection of Bladder Tumors: Analysis of Monopolar and Plasmakinetic Bipolar Cases.

OBJECTIVES: To evaluate the rate of perioperative complications after plasmakinetic bipolar and monopolar transurethral resection of bladder tumor (BTURB and MTURB). In addition, the study identifies patient and procedure characteristics associated with early complications. PATIENTS AND METHODS: Retrospective review was conducted on patients undergoing transurethral resection of bladder tumor procedures at a single institution from 2003 to 2013 to assess the 30-day complication rates associated with BTURB and MTURB. RESULTS: Four hundred twenty-seven patients met inclusion criteria and underwent 586 procedures (379 BTURB and 207 MTURB). Baseline patient demographics, tumor stage, and tumor grade were similar in BTURB and MTURB cohorts. The overall complication rate was 34.3% for MTURB and 26.7% for BTURB. The most frequent complications were acute urinary retention (AUR) 11%, hematuria 8%, and urinary tract infection (UTI) 7%. There was no statistical difference in rates of AUR, hematuria, UTI, or readmission for continuous bladder irrigation or hemostasis procedures between BTURB and MTURB cohorts. There was a trend toward lower perforation rate during BTURB (2.6% vs 5.8%). In multivariate logistic regression analysis, MTURB, male gender, and large resections were predictive of overall complications. Male gender was associated with hematuria and AUR. Large bladder tumor resection size was also associated with increased risk of overall complications and AUR. CONCLUSION: BTURB was associated with a lower risk of overall complications, but there was no difference in the rate of hematuria in the two cohorts. Male gender and large tumor size are associated with higher risk of early complications.

Percutaneous Nephrolithotomy in Patients With BMI >50: Single Surgeon Outcomes and Feasibility.

OBJECTIVE: To evaluate the use of percutaneous nephrolithotomy (PNL) and technical approach in the super obese population (body mass index [BMI] ≥ 50). MATERIALS AND METHODS: We performed a retrospective review of 31 consecutive PNL cases with a BMI > 50 from a single surgeon (SYN) from 1995 to 2013. Procedures were performed in the prone position, and upper pole access was used. Operative time, length of hospital stay, stone burden, complication rates, and stone-free rates were measured. RESULTS: Of the 31 patients who underwent PNL (age 51.2 ± 12; 71% female), the mean BMI was 59.1 ± 6 kg/m(2) (range 50.4-71.7 kg/m(2)). Mean stone burden was 3.8 cm ± 2. The majority of patients (90.3%) had an upper pole puncture site for access with an operative time of 122.1 ± 75 minutes. The technique was similar to non-obese patients; however, there was a need for extra-long instrumentation. The overall stone-free rate was 71%, with utilization of a second-look PNL in 11 cases. The complication rate, Clavien grade 3 or higher, was 9.7% (3 of 31). CONCLUSION: PNL is technically feasible, safe, and effective in patients with a BMI ≥ 50. The complication rate, length of hospital stay, and stone-free rate with use of second-look PNL in super obese patients are comparable to severely obese patients. Intervention should not be automatically ruled out or delayed based on the patient's BMI alone.

Usage of fMRI for pre-surgical planning in brain tumor and vascular lesion patients: task and statistical threshold effects on language lateralization.

BACKGROUND AND PURPOSE: Functional magnetic resonance imaging (fMRI) is a non-invasive pre-surgical tool used to assess localization and lateralization of language function in brain tumor and vascular lesion patients in order to guide neurosurgeons as they devise a surgical approach to treat these lesions. We investigated the effect of varying the statistical thresholds as well as the type of language tasks on functional activation patterns and language lateralization. We hypothesized that language lateralization indices (LIs) would be threshold- and task-dependent. MATERIALS AND METHODS: Imaging data were collected from brain tumor patients (n = 67, average age 48 years) and vascular lesion patients (n = 25, average age 43 years) who received pre-operative fMRI scanning. Both patient groups performed expressive (antonym and/or letter-word generation) and receptive (tumor patients performed text-reading; vascular lesion patients performed text-listening) language tasks. A control group (n = 25, average age 45 years) performed the letter-word generation task. RESULTS: Brain tumor patients showed left-lateralization during the antonym-word generation and text-reading tasks at high threshold values and bilateral activation during the letter-word generation task, irrespective of the threshold values. Vascular lesion patients showed left-lateralization during the antonym and letter-word generation, and text-listening tasks at high threshold values. CONCLUSION: Our results suggest that the type of task and the applied statistical threshold influence LI and that the threshold effects on LI may be task-specific. Thus identifying critical functional regions and computing LIs should be conducted on an individual subject basis, using a continuum of threshold values with different tasks to provide the most accurate information for surgical planning to minimize post-operative language deficits.

Complexity in the diagnosis and management of 45,X Turner Syndrome mosaicism.

Diagnosis, decision making, and counseling for patients with disorders of sexual development pose challenges for physicians and families. Accurate antenatal evaluation combined with effective communication between the family and multidisciplinary team is important to provide the best patient outcome. We reviewed 2 cases from our institution that illustrate the complexity of antenatal and postnatal management in Turner Syndrome patients who have 45,X mosaicism. We concluded that because of the complexity involved in providing appropriate care to these individuals, it is critical that accurate and universally accessible counseling materials are available to providers and families at the time of diagnosis and management decision making.

Characterizing the relationship between functional MRI-derived measures and clinical outcomes in patients with vascular lesions.

OBJECT: Functional MRI (fMRI) has proven to be an effective component of pretreatment planning in patients harboring a variety of different brain lesions. The authors have recently reported significant relationships concerning distances between brain tumor borders and areas of functional activation (lesion-to-activation distance; LAD) with regard to patient morbidity and mortality. This study further examines the relationship between LAD, focusing on a host of vascular lesions and pre- and posttreatment morbidity. METHODS: This study included a sample population of patients with vascular lesions (n = 106), primarily arteriovenous malformations (AVMs) and cavernomas. These patients underwent pretreatment fMRI-based motor mapping (n = 72) or language mapping (n = 84). The impact of LAD and other variables derived from the patient medical record were analyzed with respect to functional deficits in terms of morbidity (weakness and/or aphasia). RESULTS: In patients with no pretreatment deficits, there was trend for a significant relationship between the Wernicke area LAD and posttreatment language deficits. In patients with or without pretreatment deficits, a trend toward significance was observed between sensorimotor LAD and posttreatment motor deficits. Additionally, lesion type (AVMs or cavernomas) affected posttreatment deficits, with more patients with cavernomas showing posttreatment language deficits than patients with AVMs. However, this difference was not observed for posttreatment motor deficits. CONCLUSIONS: These findings suggest that the proximity of a vascular lesion to sensorimotor and language areas is a relevant parameter in estimating patient prognosis in the perioperative period. Additionally, vascular lesion type and existence of pretreatment deficits play a significant role in outcomes.