Quantitative analysis for modified Schall's classification by stimulation test with dynamic scintigraphy in Sjögren's syndrome

Abstract

Objectives To update Schall's classification for Sjögren's syndrome (SS) by the new quantitative stimulation test with dynamic salivary glands scintigraphy (qsDSGS) and to standardize quantitative salivary gland scintigraphy. Methods The histopathology, oral, ocular, serological examination and qsDSGS of 268 consecutive patients with suggestive SS were evaluated in this retrospective cohort study. The serological examination included 15 autoantibodies, antinuclear antibodies (ANA) and so on. The diagnostic thresholds of the functional parameters were set by the quantitative method, and the modified Schall's classification is well established and verified. Results Based on the quantitative analysis of qsDSGS, the peak uptake level (PUL) and stimulation excretion fraction (sEF) of each parotid gland were determined as the key imaging features, which had good diagnostic performance for SS. By the modified Schall's classification, all patients were classified into: Class 1 (normal; n = 44), Class 2 (mild to moderate involvement; n = 130), Class 3 (severe involvement; n = 56) and Class 4 (very severe involvement, non‐function; n = 38). Using the threshold PUL ≤ 10 counts per sec/pixel as positivity, the modified Schall's classification could provide better diagnostic performance with 88.4% specificity, 71.3% sensitivity, 96.14% positive predictive value and 43.20% negative predictive value for SS (likelihood ratio 6.15). The trends of serologically positive frequencies against SSA/Ro, anti‐SSB/La and ANA were significantly increased with the new classification. Conclusion The modified Schall's classification by the new stimulation test with dynamic scintigraphy is eligible to standardize quantitative salivary gland scintigraphy for SS, and may be more convenient and suitable in daily practice for clinical research and management of SS.

New‐onset primary Sjögren's syndrome following exposure to severe acute respiratory syndrome coronavirus 2: A retrospective cohort study

“…This facilitates the identification of specific anatomical changes, and it is more cost-effective and convenient for patients. [44][45][46] However, the ability to detect early or small lesions might be overlooked. 47 This study has several limitations.…”

“…This was because conventional parotid imaging has better resolution and generates clearer images of the parotid structures. This facilitates the identification of specific anatomical changes, and it is more cost‐effective and convenient for patients 44–46 . However, the ability to detect early or small lesions might be overlooked 47 …”

Recent Advances in Salivary Scintigraphic Evaluation of Salivary Gland Function

“…The categorical classification pattern proposed by Schall et al [ 25 ] in 1971, which is based on the degree of glandular uptake and isotope excretion into the oral cavity, is likely the most widely used method for interpreting sialoscintigraphic images [ 26 ], and abnormal results were adopted in the American–European Consensus Group (AECG) criteria for diagnosing Sjögren’s syndrome (SS) [ 27 ]. However, the visual assessment tends to be observer dependent [ 28 ] and limited in detecting borderline glandular dysfunction in early SS [ 29 ], and the activity in the oral cavity may be interfered with glandular spontaneous excretion and saliva swallowing during the acquisition period [ 30 ].…”

“…In past decades, although a quite variety of studies verifying the utility of quantitative methods in interpreting salivary scintigraphy in patients with sicca have been published and been concisely listed [ 30 , 38 ], the use of quantitative indices remains insufficiently supported. Two studies have directly compared the diagnostic performance of visual and semiquantitative sialoscintigraphic analyses when doctors had a clinical suspicion that a patient had SS [ 39 , 40 ].…”