Meckel diverticulum scintigraphy: technique, findings and diagnostic pitfalls.

Meckel diverticulum, the most common congenital anomaly of the gastrointestinal tract, results from the aberrant involution of the omphalomesenteric duct and accounts for more than 50% of unexplained lower gastrointestinal bleeding in the pediatric population. The most accurate imaging tool to identify a Meckel diverticulum containing ectopic gastric mucosa is the Technetium-99m pertechnetate Meckel scan, a scintigraphic study with a reported accuracy of 90% in the pediatric population. In addition to depicting a Meckel diverticulum with ectopic gastric mucosa, careful attention to the normal biodistribution of the radiotracer can lead to the identification of unexpected pathology with implications for patient management. This article serves to review the embryological origin and anatomical features of Meckel diverticulum, highlight the role of scintigraphy in evaluating Meckel diverticulum, and discuss the proper imaging technique when performing this test. We will focus on pitfalls that can lead to an erroneous diagnosis as well as incidental findings that can affect patient management.

Pediatric rib pathologies: clinicoimaging scenarios and approach to diagnosis.

Pathologies involving the ribs are diverse in nature, including entities specific to the pediatric population as well as shared pathologies with adults. These can be either localized within or adjacent to the rib, but may also cause rib alteration as a component of a systemic process. To better understand these disorders, we discuss several common rib pathologies in the context of their clinical presentation and pertinent imaging findings. In addition, we review the imaging modalities that may be used to evaluate the ribs. Encompassing both the clinical and imaging aspects of pediatric rib pathologies, this review aims to increase pediatric and musculoskeletal radiologists' awareness of the spectrum of disease and how to leverage a pattern-based approach.

Objective sonographic measurements of renal pelvic diameter and renal parenchymal thickness can identify renal hypofunction and poor drainage in patients with antenatally detected unilateral ureteropelvic junction obstruction.

INTRODUCTION: Hydronephrosis grading systems risk stratify patients with potential ureteropelvic junction obstruction, but only some criteria are measured objectively. Most notably, there is no consensus definition of renal parenchymal thinning. OBJECTIVES: The objective of this study was to assess the association between sonographic measures of renal length, renal pelvic diameter, and renal parenchymal thickness and the outcomes of a)renal hypofunction(differential renal function{DRF} <40%) and b)high-risk renal drainage(T1/2 > 40 min). STUDY DESIGN: An institutional database of patients who had diuretic renograms(DR) for unilateral hydronephrosis was reviewed. Only infants with Society for Fetal Urology(SFU) grades 3/4 hydronephrosis without hydroureter on postnatal sonogram and had a DR within 120 days were included. The following measurement variables were analyzed: anterior posterior renal pelvic diameter(APRPD), renal length(RL), renal parenchymal thickness(PT), minimal renal parenchymal thickness(MPT = shortest distance from mid-pole calyx to parenchymal edge), and renal pyramidal thickness(PyrT). RL, PT, MPT, PyrT measurements were expressed as ratios (hydronephrotic kidney/contralateral kidney). Multivariate logistic regression was performed for each outcome by comparing three separate renal measurement models. Model 1: RLR, APRPD, MPTR; Model 2: RLR, APRPD, PTR, Model 3: RLR, APRPD, PyrTR. Individual performance of variables from the best performing model were assessed via ROC curve analysis. RESULTS: 196 patients were included (107 with SFU grade 3, 89 with SFU grade 4) hydronephrosis. Median patient age was 29[IQR 16,47.2] days. 10% had hypofunction, and 20% had T1/2 > 40 min 90% with hypofunction and 87% with high-risk drainage had SFU4 hydronephrosis. Model 1 exhibited the best performance, but on multivariate analysis, only APRPD and MPTR were independently associated with both outcomes. No other measure of parenchymal thickness reached statistical significance. The odds of hypofunction and high-risk drainage increase 10% per 1 mm increase in APRPD(aOR 1.1 [CI 1.03-1.2], p = 0.005; aOR 1.1 [CI 1.03-1.2], p = 0.003). For every 0.1unit increase in MPTR the odds of hypofunction decrease by 40%(aOR 0.6 [CI 0.4-0.9], p = 0.019); and the odds of high-risk drainage decrease by 30%(aOR 0.7 [CI 0.5-0.9], p = 0.011). Optimal statistical cut-points of APRPD >16 mm and/or MPTR <0.36 identified patients at risk for obstructive parameters on DR. DISCUSSION AND CONCLUSION: Of the sonographic hydronephrosis measurement variables analyzed, only APRPD and MPTR were independently associated with objective definitions of obstruction based on renal function and drainage categories. Patients who maintain APRPD <16 mm and/or MPTR >0.36 can potentially be monitored with renal sonograms as there is >90% chance that they will not have DRF<40% or T1/2 > 40 min.