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Purpose Preoperative determination of uric acid stones from computerized tomography imaging would be of tremendous clinical use. We sought to design a software algorithm that could apply data from noncontrast computerized tomography to predict the presence of uric acid stones. Materials and Methods Patients with pure uric acid and calcium oxalate stones were identified from our stone registry. Only stones greater than 4 mm which were clearly traceable from initial computerized tomography to final composition were included in analysis. A semiautomated computer algorithm was used to process image data. Average and maximum HU, eccentricity (deviation from a circle) and kurtosis (peakedness vs flatness) were automatically generated. These parameters were examined in several mathematical models to predict the presence of uric acid stones. Results A total of 100 patients, of whom 52 had calcium oxalate and 48 had uric acid stones, were included in the final analysis. Uric acid stones were significantly larger (12.2 vs 9.0 mm, p = 0.03) but calcium oxalate stones had higher mean attenuation (457 vs 315 HU, p = 0.001) and maximum attenuation (918 vs 553 HU, p <0.001). Kurtosis was significantly higher in each axis for calcium oxalate stones (each p <0.001). A composite algorithm using attenuation distribution pattern, average attenuation and stone size had overall 89% sensitivity, 91% specificity, 91% positive predictive value and 89% negative predictive value to predict uric acid stones. Conclusions A combination of stone size, attenuation intensity and attenuation pattern from conventional computerized tomography can distinguish uric acid stones from calcium oxalate stones with high sensitivity and specificity. [ABSTRACT FROM AUTHOR]

Background Accurate diagnosis of Crohn's disease or ulcerative colitis is essential for surgical planning. This study compared the accuracy, safety, and utility of small bowel follow-through (SBFT) and magnetic resonance enterography (MRE) for detecting small bowel (SB) involvement preoperatively. Methods A retrospective review of children who underwent colectomy for inflammatory bowel disease (2000–2014) was performed. Preoperative SBFT and MRE were independently reviewed by two radiologists blinded to clinical data. Gold standard for diagnosis was surgical pathology. Results 68 patients (36 female) were included. 45 patients had SBFT prior to colectomy, 17 patients had MRE, and 6 both. Interrater reliability for radiologic interpretation was 90% (SBFT) and 91% (MRE). Mean study durations were 190 min (SBFT) and 59 min (MRE). Median effective dose for SBFT was 1.5 mSv, while MRE involved no ionizing radiation. Specificities for diagnosing SB involvement were 87.5% (SBFT) and 94% (MRE). 54 patients underwent subtotal colectomy and ileostomy, 12 restorative proctocolectomy, and 2 colectomy with ileorectal anastomosis. Preoperative imaging correlated with surgical pathology in 83% (SBFT) and 90% (MRE). Conclusion MRE is at least as effective as SBFT for assessing SB disease in children with colitis prior to colectomy. MRE requires less time and does not expose children to ionizing radiation. Retrospective Case Series, Level 4 Evidence. [ABSTRACT FROM AUTHOR]

The electron-energy structure of the structure of monosulfides of 3 d metals is calculated using a modified LAPW + lo technique that allows for the antiferromagnetic ordering in different crystallographic layers. It is shown that the splitting of d-states of the transition metal with regard to the antiferromagnetic ordering in layers leads to a transition of VS, MnS, CoS, NiS, and FeS monosulfides in the troilite structure from metallic to semiconducting state. [ABSTRACT FROM AUTHOR]

Rationale and Objectives: The aim of this study was to assess the performance of a newly developed dual-energy (DE) chest radiographic system in comparison to digital radiographic (DR) imaging in the detection and characterization of lung nodules. Materials and Methods: An experimental prototype was developed for high-performance DE chest imaging, with total dose equivalent to a single posterior-anterior DR image. Projections at low and high peak kilovoltage were used to decompose DE soft tissue and bone images. A cohort of 55 patients (31 men, 24 women; mean age, 65.6 years) was drawn from an ongoing trial involving patients referred for percutaneous computed tomography–guided biopsy of suspicious lung nodules. DE and DR images were acquired of each patient prior to biopsy. Image quality was assessed by means of human observer tests involving five radiologists independently rating the detection and characterization of lung nodules on a nine-point scale. Results were analyzed in terms of the fraction of cases at or above a given rating, and statistical significance was evaluated using Wilcoxon''s signed-rank test. Performance was analyzed for all cases pooled as well as by stratification of nodule size, density, lung region, and chest thickness. Results: The studies demonstrated a significant performance advantage for DE imaging compared to DR imaging (P < .001) in the detection and characterization of lung nodules. DE imaging improved the detection of both small and large nodules and exhibited the most significant improvement in regions of the upper lobes, where overlying anatomic noise (ribs and clavicles) are believed to reduce nodule conspicuity on DR imaging. Conclusions: DE imaging outperformed DR imaging overall, particularly in the detection of small, solid nodules. DE imaging also performed better in regions dominated by anatomic noise, such as the lung apices. The potential for improved nodule detection and characterization at radiation doses equivalent to DR imaging is encouraging and could augment the broader use of DE imaging. Future studies will extend the initial cohort and rating scale tests to a larger cohort evaluated by receiver-operating characteristic analysis and will evaluate DE imaging in comparison and as an adjuvant to low-dose computed tomography. [Copyright &y& Elsevier]

Continence enemas for the purpose of bowel management may be delivered via trans-anal retrograde irrigations, and via antegrade conduits including surgical appendicostomy or placement of cecostomy tube (CT). An appreciation of the relative advantages and disadvantages of each antegrade continence enema (ACE) procedure allows clinicians, parents and children to make an informed decision regarding which procedure is most appropriate in individual cases. The objective of this study was to evaluate the differences in in-hospital resource utilization, surgical outcomes and radiation exposure between children undergoing appendicostomy creation and CT placement at our institution. We conducted a retrospective chart review of children undergoing these procedures at our institution over a 10-year period. All patients 0–18 years of age undergoing either procedure for any indication were included. Data on demographics, length of stay (LOS), radiation exposure events (REE), and surgical outcomes were collected. One hundred fifteen (63 appendicostomy/52 CT) patients were included. Those undergoing CT placement had significantly increased post-procedural LOS, catheter exchanges and REE compared to those undergoing appendicostomy (see Table). Reported rates of bowel control were similar between the two groups, and there was no significant difference in rates of surgical complications, although each group had unique, procedure-specific complications. In our study, appendicostomy holds a clear advantage over CT in terms of post-procedural LOS, as well as REE. In general, children with CTs require more planned and unplanned device maintenance procedures than those with appendicostomy. These findings aside, the rates of success for bowel control between the two groups are similar, and the incidence of complications does not differ significantly between the two groups. CT remains a safe and effective conduit for delivery of ACEs, and is a particularly good option in patients whose appendix has been lost or used for another conduit. However, patients wishing to avoid repeated procedures and radiation exposure may find the option of appendicostomy more attractive. Summary Table 1 Length of stay, catheter exchanges and radiation exposure metrics. Summary Table 1 Appendicostomy n = 63 (%) Cecostomy n = 52 (%) p -value Post-operative LOS (days) All patients 2.8 ± 3 5 ± 5 <0.01 Isolated ACE-procedure (n = 38/44) a 2.1 ± 1 4.7 ± 4 <0.0001 Outlier excluded (n = 63/44) a 2.8 ± 3 4.9 ± 4 <0.0001 Duration of antibiotic therapy Intravenous (all patients) 1.2 ± 1.3 4 ± 13 0.02 Total (all patients) 2.7 ± 5 5 ± 13 0.16 Intravenous(isolated-ACE a) 0.9 ± 0.9 2 ± 3 0.28 Total (isolated-ACE a) 1.7 ± 3.5 2.6 ± 4 0.46 Intravenous (outlier excluded a) 1.2 ± 1.3 2.2 ± 3 0.26 Total (outlier excluded a) 2.7 ± 5 2.8 ± 4 0.58 Catheter Exchanges No. catheter exchanges per patient per year of follow-up 0.3 1.1 Total no. patients requiring unplanned catheter exchanges (entire group) 6 (10) 21 (40) <0.01 Radiation Exposure Total REE (whole group) 71 407 Total number of patients with REE 17 (27) 51 (98) <0.01 Average REE per patient 1.1 c 7.8 <0.01 Radiation exposure metrics b Total number of REE 50 136 Mean DAP d per event (mGy.cm2) 1003 488 <0.01 Median DAP per event (mGy.cm2) 396 185 <0.01 Mean reference air kerma e per event (mGy) 5.0 3.0 0.0013 Median reference air kerma per event (mGy) 2.8 1.2 0.0013 a Outlier who had 95 days of antibiotics related to cecal detachment and cardiac lesion excluded. b Radiation exposure metrics for REE with complete radiation data (50 events out of 71 events in the appendicostomy group and 136 events out of 407 events in the cecostomy group). c Represents average REE for all appendicostomy patients: average REE in appendicostomy patients with any event at all (17/63) was 4.1. d DAP refers to 'Dose Area Product' and assesses radiation risk using the absorbed radiation dose and the area irradiated during the procedure. e Air kerma is the sum of the initial kinetic energies of all the charged particles liberated by uncharged ionizing radiation (i.e: indirectly ionizing radiation such as photons and neutrons) in a sample of matter. It represents the absorbed dose or gray (Gy). Unlike DAP it is not related to the area radiated, only the dose of radiation. [ABSTRACT FROM AUTHOR]