Ultrasonography in the investigation of salivary gland disease

The applicability of ultrasound in the diagnosis of inflammatory and obstructive diseases of the major salivary glands: a scoping review

OBJECTIVES

The purpose of the present scoping review was to determine the contribution of ultrasound images in the diagnosis of inflammatory and obstructive diseases of the major salivary glands (MSGs).

METHODS

A search of studies of ultrasonographic assessments of human samples was performed in several electronic databases and grey literature up to July 2021. The extracted data were the examined MSG; the diagnostic value of ultrasound (sensibility, specificity, positive- and negative predictive value, accuracy); features of lesions, including number, echogenicity, echotexture, form, margins, size, posterior acoustic aspect, and location; and related clinical information, such as swelling, palpation, sensible to pain, salivation, lymph nodes, recurrence, duration, and causes.

RESULTS

After verifying the eligibility criteria, 90 articles focused on detecting inflammatory, and obstructive diseases of the MSG were gathered, with variable study designs and size samples. A wide variety of pathologies were assessed, including sialolitiasis (n = 45), acute sialadenitis (n = 30), chronic sialadenitis (n = 25), granulamatous diseases (n = 15), Kuttner's tumor (n = 11), juvenile recurrent parotitis (n = 9), abscess (n = 7), post-radiotherapy sialadenitis (n = 6), sialadenosis (n = 9), abscess (n = 7), IgG4-related disease sialadenitis (n = 5), HIV-sialadenitis (n = 4), obstructive sialadenitis (n = 3), iodinated contrast-induced sialadenitis (n = 2), and pneumoparotitis (n = 1). Most studies were case reports or series of cases. Few studies exhibited data about the accuracy of ultrasound in detecting MSG diseases.

CONCLUSIONS

The present scoping review concluded that ultrasound aspects of different MSG pathologies are similar but contribute to their differential diagnosis and can be considered as a valuable initial method for assessing the MSG of adults and children.

The role of colour flow Doppler in the investigation of the salivary gland tumour

AIMS

Ultrasound is a highly effective imaging technique to determine salivary gland tumours and may help to identify many benign lesions. The aim of this study is to evaluate whether colour Doppler is able to further differentiate the malignant tumour.

METHODS

Fifty-six patients with salivary gland lesions were prospectively assessed using ultrasound imaging with colour flow and power Doppler. The peak systolic velocity (PSV) was measured and the pulsatility index (PI) and resistive index (RI) calculations were performed on the pulsed wave traces. The real time ultrasound morphology and the Doppler information were correlated with the histology.

RESULTS

In 18 of the 56 patients, no internal colour flow or power Doppler changes could be detected. The real time ultrasound morphology diagnosed benign disease with sensitivity of 89.7% with specificity of 57.1%. The positive predictive value was 93.6%. There were no significant differences in the colour Doppler appearances in terms of vessel type or intratumour distribution which could separate benign from malignant conditions. However, there was statistical discrimination for PI and RI values (P = 0.0006, P = 0.0002, respectively). No malignant lesions were seen when the PI was less than 1.8 and RI was less than 0.8. The PSV was elevated in several cases (> 50 cm per s) but there was no statistical correlation with malignancy.

CONCLUSION

The risk of malignancy increases by a third when the colour Doppler demonstrates increased intratumour vascular resistance (RI > 0.8 and PI > 1.8), with positive predictive value of 97.3% (sensitivity 75.5%, specificity 85.7%).Bradley, M. J. (2000). Clinical Radiology55, 759-762.

Intra-oral ultrasound imaging of a submandibular duct calculus

A case is presented showing the first reported use of a small, digitally-guided, intra-oral ultrasound probe to image a calculus in a submandibular salivary duct. This use of intra-oral ultrasound is discussed in the context of the overall current status of intra-oral and extra-oral ultrasound imaging. It is proposed that using a combination of intra-oral and extra-oral probes, the whole of the salivary apparatus may now be examined sonographically for the presence of calculi.

Two-dimensional gray-scale clustering for texture analysis

OBJECTIVES

To develop a new quantitative method for the visual discrimination of image texture.

METHODS

Two kinds of image phantoms were prepared, one for evaluating the effects of change in size and gray values of individual pixels (primitives) on perceived coarseness and the other for evaluating changes in groups of pixels (clusters) on perceived heterogeneity. The phantom images were displayed on a CRT and presented to 11 observers who assessed heterogeneity and coarseness on a 10-point scale between -5 and +5. On the basis of the observers' results, a new texture analysis method termed two-dimensional gray-scale clustering analysis was developed and applied to measure quantitatively the texture of the phantoms. The results obtained were then compared with those of the visual evaluation.

RESULTS

The size of the primitives and the clusters greatly affected the visual evaluation of heterogeneity and coarseness. Changes in the gray value had only a slight effect. The intra-observer variation for heterogeneity was significantly larger than that for coarseness. Two-dimensional gray-scale clustering analysis could differentiate heterogeneity from coarseness. A high correlation was obtained between the visual evaluation and the quantitative data.

CONCLUSION

Quantitative two-dimensional gray-scale clustering analysis appears to be a useful means of texture analysis.

Parotid and submandibular calculi in children

Twelve pediatric patients with parotid or submandibular salivary gland calculi were successfully diagnosed following appropriately aimed imaging methods. The treatment modalities were: secretory stimulation of the gland to induce spontaneous passage, sialolithotomy or sialadenectomy. The treatment of choice was dependent on the size and location of the calculi, as well as on the affected gland and its functional secretory state.