A comprehensive non‐invasive framework for automated evaluation of acute renal transplant rejection using DCE‐MRI

The objective was to develop a novel and automated comprehensive framework for the non‐invasive identification and classification of kidney non‐rejection and acute rejection transplants using 2D dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI). The proposed approach consists of four steps. First, kidney objects are segmented from the surrounding structures with a geometric deformable model. Second, a non‐rigid registration approach is employed to account for any local kidney deformation. In the third step, the cortex of the kidney is extracted in order to determine dynamic agent delivery, since it is the cortex that is primarily affected by the perfusion deficits that underlie the pathophysiology of acute rejection. Finally, we use an analytical function‐based model to fit the dynamic contrast agent kinetic curves in order to determine possible rejection candidates. Five features that map the data from the original data space to the feature space are chosen with a k‐nearest‐neighbor (KNN) classifier to distinguish between acute rejection and non‐rejection transplants. Our study includes 50 transplant patients divided into two groups: 27 patients with stable kidney function and the remainder with impaired kidney function. All of the patients underwent DCE‐MRI, while the patients in the impaired group also underwent ultrasound‐guided fine needle biopsy. We extracted the kidney objects and the renal cortex from DCE‐MRI for accurate medical evaluation with an accuracy of 0.97 ± 0.02 and 0.90 ± 0.03, respectively, using the Dice similarity metric. In a cohort of 50 participants, our framework classified all cases correctly (100%) as rejection or non‐rejection transplant candidates, which is comparable to the gold standard of biopsy but without the associated deleterious side‐effects. Both the 95% confidence interval (CI) statistic and the receiver operating characteristic (ROC) analysis document the ability to separate rejection and non‐rejection groups. The average plateau (AP) signal magnitude and the gamma‐variate model functional parameter α have the best individual discriminating characteristics. Copyright © 2013 John Wiley & Sons, Ltd.     

Stromal‐derived factor‐1 gene variations in pediatric patients with primary immune thrombocytopenia

Primary immune thrombocytopenia (ITP) of childhood is an autoimmune disease characterized by abnormally increased destruction of platelets and decreased megakaryopoiesis. Stromal‐derived factor‐1 (SDF‐1) plays a role in megakaryopoiesis and may be involved in the pathogenesis of ITP. Five single nucleotide polymorphisms (SNPs) of the SDF‐1 gene, including rs1801157, rs2839693, rs2297630, rs1065297, and rs266085, were assessed in 100 children with ITP and 126 healthy controls. The genotypes were analyzed by tetra ARMS polymerase chain reaction and confirmed by direct sequencing. Compared with controls, the rs2839693 A/A and rs266085 C/T genotypes were decreased in ITP patients (P = 0.004 and 0.007, respectively). The odds ratios of the latter genotypes were 0.48, 95% CI 0.28–0.82. Further analysis of the relationship between SDF‐1 polymorphisms and clinical features showed that rs2297630 A/G was associated with protection from chronicity (P = 0.002; OR, 0.07; 95% CI, 0.01–0.61) and steroid dependence (P = 0.007; OR, 0.10; 95% CI, 0.01–0.84) in ITP patients. However, rs266085 genotype C/C was associated with risk of steroid dependence (P = 0.012, OR 3.87, 95% CI 1.27–11.77). The findings of this study suggest that SDF‐1 gene variations may be associated with the occurrence and prognosis of childhood ITP.     

Clinico‐genetic aspects of a pediatric non‐neurofibromatosis type 1 malignant triton tumor with loss of chromosome X

Malignant triton tumor (MTT) is an aggressive peripheral nerve sheath tumor with rhabdomyoblastic differentiation. Less than 100 cases have been described, being mostly male children with type 1 neurofibromatosis. We report a 6‐year‐old female with MTT and no diagnostic criteria for neurofibromatosis type 1. Cytogenetic analysis showed a 46,X,‐X[4]/46,XX[16] karyotype. She underwent a transfemoral amputation and chemotherapy and is free of disease 15 months after diagnosis. The few cytogenetic studies of MTT described in the literature have been inconclusive. Further cytogenetic analyses are needed to understand the role of chromosome X monosomy in the pathogenesis of this rare tumor. Pediatr Blood Cancer 2012; 59: 1320–1323. © 2012 Wiley Periodicals, Inc.