Citations

AbstractObjectivesUrinary tract infection (UTI) is the most common infectious complication after kidney transplantation. We aim to determine its impact on allograft function as indicated by several measures such as iothalamate glomerular filtration rate (iGFR), estimated glomerular filtration rate (eGFR), and creatinine value.MethodsWe performed a single‐center retrospective cohort study to determine the impact ofUTIon kidney allograft outcome.ResultsThe study population consisted of 301 kidney transplant recipients; 84% were living donor transplants. One hundred and one patients (34%) developed at least one episode ofUTIand the incidence ofUTIduring the first year after transplantation was 25%. At the end of the follow‐up, theiGFRwas lower among patients who had developed at least oneUTI(p = 0.044). However,eGFRand creatinine values were not significantly different betweenUTIand non‐UTIgroups.ConclusionWhen kidney function was measured byeGFRand creatinine, there was no significant difference in allograft function between kidney recipients with or withoutUTI. However, when kidney function was measured by nuclear studies, there was a tendency toward impairment in allograft function among patients who developed atleast oneUTIafter transplantation.

AbstractRenal retransplantation after a failed prior kidney and pancreas transplant is being increasingly performed. In these complex cases, both iliac fossae have been used for prior transplants, and the placement of the new allograft can be problematic. We describe our experience with an alternative technique for renal retransplantation (RRTx) in the setting of severe bilateral aortoiliac atherosclerosis or scarring and fibrosis on the iliac vessels. Nephrectomy of the failed allograft is performed, and the renal vessels of the failed allograft (RVFA) are preserved. The new kidney is implanted on RVFA at the same operative time. This technique was attempted and successfully accomplished in a total of six patients (mean operative time = 240 ± 63 min). One postoperative complication occurred: poor arterial inflow to the allograft, being corrected reoperatively. Hospitalizations ranged from five to eight d. Five of the six patients were alive with a functioning allograft at last follow‐up (a single graft failure occurred 21 months postoperatively in the setting of post‐transplant lymphoproliferative disease that also led to patient death). Renal vessels of the failed allograft seem to be suitable alternative vascular conduits for renal retransplantation after prior kidney and pancreas transplants.

AbstractMotivationDiseases that progress slowly are often studied by observing cohorts at different stages of disease for short periods of time. The Alzheimer's Disease Neuroimaging Initiative (ADNI) follows elders with various degrees of cognitive impairment, from normal to impaired. The study includes a rich panel of novel cognitive tests, biomarkers, and brain images collected every 6 months for as long as 6 years. The relative timing of the observations with respect to disease pathology is unknown. We propose a general semiparametric model and iterative estimation procedure to estimate simultaneously the pathological timing and long‐term growth curves. The resulting estimates of long‐term progression are fine‐tuned using cognitive trajectories derived from the long‐term “Personnes Agées Quid” study.ResultsWe demonstrate with simulations that the method can recover long‐term disease trends from short‐term observations. The method also estimates temporal ordering of individuals with respect to disease pathology, providing subject‐specific prognostic estimates of the time until onset of symptoms. When the method is applied to ADNI data, the estimated growth curves are in general agreement with prevailing theories of the Alzheimer's disease cascade. Other data sets with common outcome measures can be combined using the proposed algorithm.AvailabilitySoftware to fit the model and reproduce results with the statistical software R is available as the grace package. ADNI data can be downloaded from the Laboratory of NeuroImaging.

Object Historically, surgery to the petrous apex has been addressed via craniotomy and open microscopic anterior petrosectomy (OAP). However, with the popularization of endoscopic approaches, the petrous apex can further be approached endonasally by way of an endoscopic endonasal anterior petrosectomy (EAP). Endonasal anterior petrosectomy is a relatively new procedure and has not been compared anatomically with OAP. The authors hypothesized that the EAP and OAP techniques approach different portions of the petrous apex and therefore may have different applications. Methods Four cadaveric heads were used. An OAP was performed on one side and an EAP was performed on the contralateral side; the limits of bony resection were defined. The extent of bony resection was then evaluated using predissection and postdissection thin-slice CT scans. The comparative resection was then reconstructed using 3D modeling on Brainlab workstations. Results The average resection volumes for EAP and OAP were 0.297 cm 3 and 0.649 cm 3 , respectively, representing a comparative percentage of 46% (EAP/OAP). An EAP and OAP achieved resection of 29% and 64% of the total petrous apex volume, respectively. Indeed, EAP addressed the inferior portion of the petrous apex located adjacent to the petroclival suture more completely than OAP, where 45% of the bone overlying the petroclival suture (petroclival angle to the jugular foramen) was resected with the EAP, while 0% was resected with the OAP. Conclusions In anatomically normal cadavers, OAP achieved nearly a 50% larger volumetric resection than EAP. Furthermore, while OAP appears to completely address the superior portion of the petrous apex, EAP appears to have a niche in approaches to lesions in the inferior petrous apex. Given these results, the authors propose that OAP be redefined as the “superior anterior petrosectomy,” while EAP be referred to as the “inferior anterior petrosectomy,” which more clearly defines the role of each approach in anterior petrosectomy.

Despite its nonionizing technique and exquisite soft tissue characterization, noncardiovascular, and nonmusculoskeletal magnetic resonance imaging (MRI) of the chest has been considered impractical due to various challenges such as respiratory motion, cardiac motion, vascular pulsatility, air susceptibility, and paucity of signal in the lung. With advances in MRI, it is now possible to perform diagnostically useful and good quality MRIs of the chest, but literature on subspecialized chest MRI practices is limited. The purpose of this manuscript is to describe the rationale, nuances, and logistics that went into developing such a practice in the Division of Thoracic Radiology at our institution. The topics addressed include technical and clinical considerations, support at administrative and clinical levels, protocol development, and economic considerations compared with conventional practices. Various MRI techniques are also specifically discussed to facilitate chest MRI at other sites. Although chest MRI is used in a relatively small number of patients at this point, in certain patients, chest MRI can provide additional information to optimize medical management. A few clinical cases illustrate the quality and clinical utility of chest MRI. Given recent advances in MRI techniques, it is now an opportune time to develop a chest MRI practice.

Obesity is associated with important decrements in lung volumes. Despite this, ventilation remains normally or near normally distributed at least for moderate decrements in functional residual capacity (FRC). We tested the hypothesis that this is because maximum flow increases presumably as a result of an increased lung elastic recoil. Forced expiratory flows corrected for thoracic gas compression volume, lung volumes, and forced oscillation technique at 5–11–19 Hz were measured in 133 healthy subjects with a body mass index (BMI) ranging from 18 to 50 kg/m2. Short-term temporal variability of ventilation heterogeneity was estimated from the interquartile range of the frequency distribution of the difference in inspiratory resistance between 5 and 19 Hz (R5–19_IQR). FRC % predicted negatively correlated with BMI ( r = −0.72, P < 0.001) and with an increase in slope of either maximal ( r = −0.34, P < 0.01) or partial flow-volume curves ( r = −0.30, P < 0.01). Together with a slight decrease in residual volume, this suggests an increased lung elastic recoil. Regression analysis of R5–19_IQRagainst FRC % predicted and expiratory reserve volume (ERV) yielded significantly higher correlation coefficients by nonlinear than linear fitting models ( r2= 0.40 vs. 0.30 for FRC % predicted and r2= 0.28 vs. 0.19 for ERV). In conclusion, temporal variability of ventilation heterogeneities increases in obesity only when FRC falls approximately below 65% of predicted or ERV below 0.6 liters. Above these thresholds distribution is quite well preserved presumably as a result of an increase in lung recoil.