Feasibility of rapid magnetic resonance imaging (rMRI) for the emergency evaluation of suspected pediatric orbital cellulitis

Orbital Fat Density as a Diagnostic Tool in Pre-Septal and Orbital Cellulitis

PURPOSE

To evaluate the usefulness of measuring orbital fat density in identifying post-septal involvement when initial differential diagnosis between orbital and periorbital cellulitis (OC and POC) is unclear.

MATERIALS AND METHODS

Retrospective study of patients with clinical diagnosis of OC or POC who underwent contrast-enhanced computerized tomographic scans over a span of 10 years. Intraconal orbital fat density was measured with Hounsfield units (HU) in six areas on axial scans consisting of nasal and temporal intraconal sites. These measurements correlated with the initial and final diagnoses. Main outcome measures were HU values at the initial and final diagnoses.

RESULTS

Fifty-seven patients were included. Mean HU measurement was -52 ± 18 HU for the involved side vs. -63 ± 13 for the uninvolved side (P < .001). The values were higher in cases of a final diagnosis of OC in the involved side (P < .001). The HU values were significantly higher in the nasal vs. the temporal locations of each orbit bilaterally (P < .001). The initial POC diagnosis of 20 patients (35%) was revised to OC.

CONCLUSION

Intraconal fat density measurements can assist in the primary assessment of orbital involvement in patients with an uncertain initial diagnosis, with a HU value higher than -50 is suggestive of orbital involvement.

Tailored magnetic resonance fingerprinting of post-operative pediatric brain tumor patients

PURPOSE

Brain and spinal cord tumors are the second most common cancer in children and account for one out of four cancers diagnosed. However, the long acquisition times associated with acquiring both data types prohibit using quantitative MR (qMR) in pediatric imaging protocols. This study aims to demonstrate the tailored magnetic resonance fingerprinting's (TMRF) ability to simultaneously provide quantitative maps (T1, T2) and multi-contrast qualitative images (T1 weighted, T1 FLAIR, T2 weighted) rapidly in pediatric brain tumor patients.

METHODS

In this work, we imaged five pediatric patients with brain tumors (resected/residual) using TMRF at 3 T. We compared the TMRF-derived T2 weighted images with those from the vendor-supplied sequence (as the gold standard, GS) for healthy and pathological tissue signal intensities. The relaxometric maps from TMRF were subjected to a region of interest (ROI) analysis to differentiate between healthy and pathological tissues. We performed the Wilcoxon rank sum test to check for significant differences between the two tissue types.

RESULTS

We found significant differences (p < 0.05) in both T1 and T2 ROI values between the two tissue types. A strong correlation was found between the TMRF-based T2 weighted and GS signal intensities for the healthy (correlation coefficient, r = 0.99) and pathological tissues (r = 0.88).

CONCLUSION

The TMRF implementation provides the two relaxometric maps and can potentially save ~2 min if it replaces the T2-weighted imaging in the current protocol.

Evaluation and Medical Management of the Pediatric Patient With Orbital Cellulitis/Abscess: A Systematic Review

BACKGROUND AND OBJECTIVES

Pediatric orbital cellulitis/abscess (OCA) can lead to vision loss, intracranial extension of infection, or cavernous thrombosis if not treated promptly. No widely recognized guidelines exist for the medical management of OCA. The objective of this review was to summarize existing evidence regarding the role of inflammatory markers in distinguishing disease severity and need for surgery; the role of imaging in OCA evaluation; and the microbiology of OCA over the past 2 decades.

METHODS

This review was reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Searches were performed in MEDLINE (Ovid), Web of Science Core Collection, Scopus, CINAHL (EBSCO), and Cochrane Central Register of Controlled Trials (CENTRAL), most recently on February 9, 2021.

RESULTS

A total of 63 studies were included. Most were descriptive and assessed to have poor quality with high risk of bias. The existing publications evaluating inflammatory markers in the diagnosis of OCA have inconsistent results. Computed tomography imaging remains the modality of choice for evaluating orbital infection. The most common organisms recovered from intraoperative cultures are Streptococcus species (Streptococcus anginosus group, group A Streptococcus, and pneumococcus) and Staphylococcus aureus. Methicillin-resistant S aureus in culture-positive cases had a median prevalence of 3% (interquartile range, 0%-13%).

CONCLUSION

This systematic review summarizes existing literature concerning inflammatory markers, imaging, and microbiology for OCA evaluation and management. High-quality evidence is still needed to define the optimal medical management of OCA.