# Multispectral optoacoustic tomography of salivary glands in patients with clinically suspected Sjögren’s disease: A pilot study

## TL;DR

This pilot study explores using multispectral optoacoustic tomography (MSOT) as a non-invasive imaging method to diagnose Sjögren’s disease by analyzing salivary gland hemoglobin signals.

## Contribution

The study introduces a novel MSOT scoring system based on hemoglobin signals for non-invasive SjD classification.

## Key findings

- MSOT achieved 92% sensitivity and 100% specificity for SjD classification using predefined cut-off values.
- SjD patients showed significantly higher hemoglobin-related signals compared to non-SjD patients.
- MSOT outperformed established ultrasound scoring systems and other diagnostic tests in this pilot study.

## Abstract

Sjögren’s disease (SjD) is a systemic auto-immune disease characterized by salivary gland inflammation and glandular dysfunction. Diagnosis is challenging due to its heterogeneity and currently relies on a variety of tests that are present in the ACR-EULAR classification criteria. These include invasive and resource-intensive tests, highlighting the unmet need for a single, accurate, non-invasive diagnostic modality. Multispectral optoacoustic tomography (MSOT), enabling functional imaging of hemoglobin-related parameters, may address this gap. This pilot study evaluates MSOT's potential for salivary gland imaging in patients suspected of SjD. This study included 20 patients clinically suspected of SjD. Which underwent MSOT imaging of the major salivary glands, alongside the full ACR-EULAR diagnostic workup, including serology, salivary gland biopsy, and sialometry, alongside salivary gland ultrasound. MSOT parameters were compared to standard of care diagnostic modalities and ultrasound scoring systems. A novel MSOT scoring system based on 800 nm hemoglobin signals was developed to evaluate diagnostic performance. Patients classified as SjD (n = 13) show significantly higher hemoglobin-related signals compared to non-SjD patients (n = 7). When ≥ 2 salivary glands, either submandibular or parotid, exceeded their predefined MSOT cut-off values of 371.6 a.u. and 374.2 a.u., respectively, MSOT achieved 92 % sensitivity and 100 % specificity for SjD classification, outperforming other diagnostic tests and established ultrasound scoring systems. MSOT shows promise as non-invasive imaging modality for SjD classification, and may offer higher sensitivity compared to established ultrasound scoring systems and other diagnostic tests. These explorative findings support further investigation of MSOT as non-invasive diagnostic tool in SjD.