# Comparative analysis of F-18 FDG PET/CT images between scrub typhus and systemic lupus erythematosus

## TL;DR

This study compares FDG PET/CT imaging features in scrub typhus and systemic lupus erythematosus to help distinguish between the two diseases.

## Contribution

This is the first study to compare FDG PET/CT images between scrub typhus and systemic lupus erythematosus for diagnostic differentiation.

## Key findings

- Scrub typhus patients had significantly longer Dmax values, indicating more generalized lymphadenopathy.
- SUVmax values for lymph nodes, spleen, and liver were higher in scrub typhus patients.
- SUVmean values of the liver and spleen were similar between the two groups.

## Abstract

This study evaluated the use of F-18 fluorodeoxyglucose (FDG) PET/CT imaging to differentiate between scrub typhus and systemic lupus erythematosus (SLE) in patients presenting with lymphadenopathy. We carried out a retrospective analysis of 18 scrub typhus patients and seven SLE patients, using various imaging parameters, including lymph node size, spleen and liver lengths, the distance between the two farthest lesions (Dmax), and assessments of glucose metabolism. On FDG PET images, we measured the maximum standardized uptake value (SUVmax) of the lymph nodes, spleen, and liver and the mean standardized uptake value (SUVmean) of the liver and spleen. The Dmax values of scrub typhus patients were significantly longer than those of SLE patients, indicating that lymphadenopathy is more generalized in the patients with scrub typhus. The SUVmax values for the lymph node, spleen, and liver were also higher in patients with scrub typhus, while the SUVmean of the liver and spleen did not differ between the two groups. This study is the first to compare FDG PET/CT images between these two conditions, suggesting the potential of this imaging modality to provide critical diagnostic distinctions.