Diffusion-weighted MRI findings in Sjögren's syndrome: a preliminary study

Advanced imaging of head and neck infections

When head and neck infection is suspected, appropriate imaging contributes to treatment decisions and prognosis. While contrast-enhanced CT is the standard imaging modality for evaluating head and neck infections, MRI can better characterize the skull base, intracranial involvement, and osteomyelitis, implying that these are complementary techniques for a comprehensive assessment. Both CT and MRI are useful in the evaluation of abscesses and thrombophlebitis, while MRI is especially useful in the evaluation of intracranial inflammatory spread/abscess formation, differentiation of abscess from other conditions, evaluation of the presence and activity of inflammation and osteomyelitis, evaluation of mastoid extension in middle ear cholesteatoma, and evaluation of facial neuritis and labyrinthitis. Apparent diffusion coefficient derived from diffusion-weighted imaging is useful for differential diagnosis and treatment response of head and neck infections in various anatomical sites. Dynamic contrast-enhanced MRI perfusion may be useful in assessing the activity of skull base osteomyelitis. MR bone imaging may be of additional value in evaluating bony structures of the skull base and jaw. Dual-energy CT is helpful in reducing metal artifacts, evaluating deep neck abscess, and detecting salivary stones. Subtraction CT techniques are used to detect progressive bone-destructive changes and to reduce dental amalgam artifacts. This article provides a region-based approach to the imaging evaluation of head and neck infections, using both conventional and advanced imaging techniques.

Value of magnetic resonance imaging and sialography of the parotid gland for diagnosis of primary Sjögren syndrome

AIM

To evaluate the utility of magnetic resonance imaging (MRI) and magnetic resonance sialography (MRS) for diagnosis of primary Sjögren syndrome (pSS) singly or integrated with 2016 American College of Rheumatology (ACR)/European League Against Rheumatic Diseases (EULAR) classification criteria.

METHODS

The diagnostic efficiencies of MRI, MRS, and labial salivary gland biopsy (LSGB) were evaluated. The prediction model was established by multivariate analysis. Finally, performance of the ACR/EULAR criteria was evaluated after addition of MRI + MRS or replacement of original items by MRI + MRS.

RESULTS

The combined use of LSGB + MRI + MRS provided the greatest diagnostic value. MRI and MRS grade had positive correlations with disease duration and pathological grade of the labial gland (both P < 0.001). MRI and MRS grade had positive correlations with xerostomia severity and negative correlations with unstimulated salivary flow rate (both P < 0.001). The consistency of MRI grade and MRS grade in the diagnosis of parotid gland lesions was poor (κ = 0.253, P < 0.001). The diagnostic efficiency of our prediction model (AUC 0.906) was similar to that of criteria from the ACR/EULAR (AUC 0.930). Adding MRI + MRS to the ACR/EULAR criteria improved the sensitivity (92.3% vs 90.8%), whereas the specificity remained the same (88.9% vs 89.1%). Replacing LSGB by MRI + MRS in the ACR/EULAR criteria decreased both sensitivity and specificity (88.1% vs 90.8% and 86.4% vs 89.1%, respectively).

CONCLUSION

The combined application of MRI and MRS has ideal clinical application value in the diagnosis of early-stage pSS. Validity of the ACR/EULAR criteria remains high after incorporation of MRI + MRS.

Diffusion-Weighted Imaging of the Head and Neck (Including Temporal Bone)

Diffusion techniques provide valuable information when performing head and neck imaging. This information can be used to detect the presence or absence of pathology, refine differential diagnosis, determine the location for biopsy, assess response to treatment, and prognosticate outcomes. For example, when certain technical factors are taken into consideration, diffusion techniques prove indispensable in assessing for residual cholesteatoma following middle ear surgery. In other scenarios, pretreatment apparent diffusion coefficient values may assist in prognosticating outcomes in laryngeal cancer and likelihood of response to radiation therapy. As diffusion techniques continue to advance, so too will its clinical utility.

Evaluation of salivary gland fat fraction values in patients with primary Sjögren's syndrome by mDIXON quant imaging: Initial findings

PURPOSE

To explore the role of salivary fat fraction (FF) values in evaluating patients with primary Sjögren's syndrome (pSS).

MATERIAL AND METHOD

A total of 28 patients with pSS, ten patients with suspected pSS, and 28 volunteers were enrolled. The FF values of the parotid and submandibular glands were generated from mDIXON Quant. A one-way analysis of variance was used to compare the FF values among the groups. A receiver-operating characteristic analysis was applied to assess the diagnostic performance of the parotid and submandibular FF values in distinguishing patients with pSS from non-pSS subjects. In particular, we focused on distinguishing patients with grade 0 pSS from those with suspected pSS.

RESULTS

The parotid and submandibular mean FF value of patients with pSS was significantly higher than that of healthy volunteers. The submandibular mean FF value of patients with pSS was higher than those suspected ones. Submandibular FF value performed better than parotid FF value in differentiating patients with pSS from those non-pSS subjects (area under the curve [AUC] = 0.927 vs. 0.734), patients with pSS from patients with suspected pSS (AUC = 0.907 vs. 0.725). This value also performed better at distinguishing patients with grade 0 pSS from those patients with suspected pSS (AUC = 0.925 vs. 0.783).

CONCLUSIONS

The salivary gland FF value, especially the submandibular gland FF value, distinguished patients with pSS from those patients with suspected pSS and healthy volunteers.

Whole-Volume ADC Histogram Analysis in Parotid Glands to Identify Patients with Sjögren's Syndrome

At present, no gold standard for diagnosing Sjögren’s syndrome (SS) is available in clinical practice. The 2002 American–European Consensus Group classification criteria are used to diagnose SS. Clinically, it is challenging to distinguish patients with SS from suspected patients undergoing different therapies. A total of 52 patients with SS and 24 patients suspected of having the disease prospectively underwent 3.0-T magnetic resonance (MR) scanning, including diffusion-weighted imaging (b = 0 and 1000 s/mm²). The whole-volume apparent diffusion coefficient (ADC) histogram analysis generated ADC_mean, skewness, kurtosis, and entropy values from bilateral parotid glands. Continuous variables were compared using an independent two-sample t test, and categorical variable compared using the Fisher’s test between the two groups. Receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic performance of the indexes. Fisher’s tests demonstrated that some clinical indexes and MR morphology grades differed significantly between patients with SS and patients suspected of having the disease (all P ≤ 0.001). The parotid entropy value of patients with SS was significantly higher than that of patients suspected of having the disease (P < 0.001). Among MR parameters, entropy combined with kurtosis performed the best in differentiating patients with SS from those suspected of having SS (area under the ROC curve = 0.955). A whole-volume ADC histogram analysis might provide a series of parameters that reflect tissue characteristics.

Whole-volume ADC Histogram and Texture Analyses of Parotid Glands as an Image Biomarker in Evaluating Disease Activity of Primary Sjögren's Syndrome

Diffusion weighted imaging (DWI) has proven to be sensitive for detecting early injury to the parotid gland in pSS (primary Sjögren’s syndrome). Here, we explored the application of ADC histogram and texture analyses for evaluating the disease activity of pSS. A total of 55 patients with pSS who met the classification criteria of the 2002 AECG criteria prospectively underwent 3.0-T magnetic resonance imaging (MRI) including DWI (b = 0 and 1000 s/mm²). According to the ESSDAI score, 35 patients were categorized into the low-activity group (ESSDAI < 5) and 20 into the moderate-high-activity group (ESSDAI ≥ 5). Via analysis of the whole-volume ADC histogram, the ADC_mean, skewness, kurtosis, and entropy values of the bilateral parotid glands were determined. Multivariate analysis was used to identify independent risk factors for predicting disease activity. The diagnostic performance of the indexes was evaluated via receiver operating characteristic (ROC) analysis. ROC analysis showed that the anti-SSB, lip biopsy, MRI morphology, ADC, ADC_mean, and entropy values were able to categorize the disease into two groups, particularly the entropy values. The multivariate model, which included anti-SSB, MRI morphology and entropy, had an area under the ROC curve of 0.923 (P < 0.001). The parotid entropy value distinguished disease activity in patients with pSS, especially combined with anti-SSB and MRI morphology.

Routine and Advanced Diffusion Imaging Modules of the Salivary Glands

This article reviews the role of routine and advanced diffusion imaging modules of the salivary glands. Routine and advanced diffusion imaging modules have a role in differentiation of malignant from benign salivary gland tumors, characterization of some benign salivary gland tumors, and staging of salivary gland cancer. The role of advanced diffusion modules in patients with salivary gland cancer after surgery, radiation therapy, or radioiodine therapy is discussed. Advanced diffusion imaging modules can help in diagnosis and staging of Sjögren syndrome.

Diffusional kurtosis imaging of parotid glands in Sjögren's syndrome: Initial findings

PURPOSE

To explore the role of diffusion kurtosis imaging (DKI) of parotid glands in diagnosing Sjögren's syndrome (SS).

MATERIALS AND METHODS

A total of 40 patients with SS and 40 healthy volunteers underwent 3.0T magnetic resonance imaging (MRI) including DKI, which generated the apparent diffusion coefficient (ADC), corrected diffusion (D), and diffusional kurtosis (K) values. The MR nodular grade was determined on the basis of MR morphological findings.

RESULTS

The parotid ADC, D, and K values in patients with SS were significantly higher than those of healthy volunteers (P = 0.011, < 0.001, 0.022, respectively). The parotid ADC and D values in patients with SS of MR nodular grade 0 were significantly higher than those of healthy volunteers (all P < 0.001). The parotid D value showed an accuracy of 75.0% and 87.9% in diagnosing patients with SS and MR nodular grade 0, respectively. The parotid ADC and D values correlated negatively, while the K values correlated positively with the MR nodular grade significantly in patients with SS (r = -0.741, -0.605, 0.424, all P < 0.001). All parotid DKI parameters differed significantly among patients with SS at different MR nodular grades (all P < 0.001).

CONCLUSION

Parotid DKI parameters hold great potential in diagnosing SS, especially in early-stage SS without MR morphological changes.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1409-1417.

Imaging of sialadenitis

Sialadenitis is an inflammation or infection of the salivary glands that may affect the parotid, submandibular and small salivary glands. Imaging findings vary among unilateral or bilateral salivary gland enlargement, atrophy, abscess, ductal dilation, cysts, stones and calcification. Imaging can detect abscess in acute bacterial suppurative sialadenitis, ductal changes with cysts in chronic adult and juvenile recurrent parotitis. Imaging is sensitive for detection of salivary stones and stricture in obstructive sialadenitis. Immunoglobulin G4-sialadenitis appears as bilateral submandibular gland enlargement. Imaging is helpful in staging and surveillance of patients with Sjögren’s syndrome. Correlation of imaging findings with clinical presentation can aid diagnosis of granulomatous sialadenitis. Post-treatment sialadenitis can occur after radiotherapy, radioactive iodine or surgery.

Imaging of sialadenitis

Sialadenitis is an inflammation or infection of the salivary glands that may affect the parotid, submandibular and small salivary glands. Imaging findings vary among unilateral or bilateral salivary gland enlargement, atrophy, abscess, ductal dilation, cysts, stones and calcification. Imaging can detect abscess in acute bacterial suppurative sialadenitis, ductal changes with cysts in chronic adult and juvenile recurrent parotitis. Imaging is sensitive for detection of salivary stones and stricture in obstructive sialadenitis. Immunoglobulin G4-sialadenitis appears as bilateral submandibular gland enlargement. Imaging is helpful in staging and surveillance of patients with Sjögren's syndrome. Correlation of imaging findings with clinical presentation can aid diagnosis of granulomatous sialadenitis. Post-treatment sialadenitis can occur after radiotherapy, radioactive iodine or surgery.

Imaging of sialadenitis

Sialadenitis is an inflammation or infection of the salivary glands that may affect the parotid, submandibular and small salivary glands. Imaging findings vary among unilateral or bilateral salivary gland enlargement, atrophy, abscess, ductal dilation, cysts, stones and calcification. Imaging can detect abscess in acute bacterial suppurative sialadenitis, ductal changes with cysts in chronic adult and juvenile recurrent parotitis. Imaging is sensitive for detection of salivary stones and stricture in obstructive sialadenitis. Immunoglobulin G4-sialadenitis appears as bilateral submandibular gland enlargement. Imaging is helpful in staging and surveillance of patients with Sjögren’s syndrome. Correlation of imaging findings with clinical presentation can aid diagnosis of granulomatous sialadenitis. Post-treatment sialadenitis can occur after radiotherapy, radioactive iodine or surgery.

Use of T1ρMR imaging in Sjögren's syndrome with normal appearing parotid glands: Initial findings

PURPOSE

To explore the feasibility of parotid spin-lattice relaxation time in the rotating frame (T1ρ) MR imaging in the diagnosis of Sjögren's syndrome (SS) without morphological changes of the parotid glands.

MATERIALS AND METHODS

The study enrolled 32 consecutive SS patients without morphological changes of parotid glands and 32 age- and gender-matched healthy volunteers who underwent parotid 3.0 Tesla MR imaging, including T1ρ sequences. Follow-up imaging was performed at 3 months. T1 signal intensities and T1ρ values of bilateral parotid glands were compared using paired samples t-test. Parotid T1 signal intensities and T1ρ values were compared using two independent samples t-test. Diagnostic performance of the parotid T1ρ values was evaluated by receiver operating characteristic analysis. The intraclass correlation coefficient (ICC) was calculated to evaluate the reproducibility of parotid T1ρ measurements.

RESULTS

There were no significant differences of T1 signal intensities and T1ρ values between bilateral parotid glands in SS patients and healthy volunteers (P = 0.170, 0.886 and 0.942, 0.229). The parotid T1ρ values of SS patients (96.47 ± 15.38 ms) were significantly higher than those of healthy volunteers (84.25 ± 6.11 ms) (P < 0.001), while there were no significant differences of T1 signal intensities between SS patients and healthy volunteers (P = 0.655). With a cutoff value of 88.02 ms, the sensitivity and specificity of the parotid T1ρ value was 75.0% and 100.0% in the diagnosis of SS. The reproducibility of parotid T1ρ measurement was excellent (ICC: 0.934-0.995).

CONCLUSION

Parotid T1ρ MR imaging held a potential role in diagnosing SS without morphological changes of parotid glands.

LEVEL OF EVIDENCE

2 J. Magn. Reson. Imaging 2017;45:1005-1012.