Comparative Diagnostic Accuracy of Ultrasound, MRI, and Fine-Needle Aspiration Biopsy in the Preoperative Evaluation of Parotid Gland Tumors

Abstract

Background: The objective of this study was to compare the value of ultrasound (US), magnetic resonance imaging (MRI), and US-guided fine-needle aspiration biopsy (FNAB) in the preoperative evaluation of parotid tumors. Methods: A three-year prospective study, including 35 patients, was conducted. Preoperative ultrasound, MRI, and US-guided FNAB were performed on each patient, after which an imaging and cytological diagnosis was obtained. Each patient underwent surgical treatment. The imaging and cytological diagnoses were compared with the histopathological reports. Results: Ultrasound and MRI showed the same diagnostic performance in discriminating benign from malignant parotid tumors: sensitivity-80%, specificity-97%, and accuracy-94%. In this regard, FNAB registered a sensitivity, specificity, and accuracy of 100%, 97%, and 97%, respectively. US, MRI, and FNAB were recorded as having high diagnostic accuracy in the detection of pleomorphic adenoma and Warthin tumors. Conclusions: Ultrasound and US-guided FNAB allow for the preoperative differential diagnosis of parotid tumors located in the superficial lobe. When US and FNAB results are inconclusive, MRI becomes mandatory.

Keywords: diagnosis; fine-needle aspiration biopsy; magnetic resonance imaging; parotid gland; tumors; ultrasound.

Figure 1

Data collection and study protocol—flowchart.

Figure 2

Malignant tumor—left parotid gland. (A,B) Two-dimensional ultrasound that reveals an inhomogeneous tumor, with areas of necrosis and irregular and infiltrative contour. (C) The color Doppler examination demonstrates an irregular, anarchic distribution of the vascular signal. (D) Elastography examination—laterocervical adenopathy with areas of intranodal stiffness.

Figure 3

Warthin tumor—right parotid gland. (A,B) Two-dimensional examination revealing a hypoechoic, inhomogeneous nodule with areas of intralesional fluid degeneration, with a slightly irregular contour but well demarcated from the adjacent parotid parenchyma. (C) The color Doppler examination reveals intratumoral vascularization. (D) Elastography examination with peripheral stiffness and intralesional soft appearance.

Figure 4

Pleomorphic adenoma—left parotid gland. (A,B) Two-dimensional examination revealing a hypoechoic nodule, with an irregular contour, slightly lobulated, and well demarcated from the adjacent parotid parenchyma. (C) The color Doppler examination reveals a reduced intralesional vascular signal. (D) Elastography examination with a predominantly soft intratumoral appearance.

Figure 5

Pleomorphic adenoma—left parotid gland. Preoperative MRI. T1 sequence with a hypointense signal (A). T2 sequence with a discrete inhomogeneous hyperintense signal (B). DCE-MRI—slow and progressive contrast uptake with late washout—TIC curve type A, typical appearance of pleomorphic adenoma (C). The DWI—MRI sequences (D) demonstrate T2 appearance, “shine through”, with a hypersignal on the DWI sequence and ADC, with the ADC map (E) having a value of 1.6 × 10^–3 mm²/s.

Figure 6

Warthin tumor—left parotid tumor. Preoperative MRI. T1-weighted sequence with a hypointense signal at the level of the tumor, a well-demarcated lesion (A). T2 sequence—mixed signal at the level of the lesion and the presence of cystic areas at the level of the lesion (B). DCE-MRI—C-type TIC curve, with rapid contrast uptake and rapid washout (C). The DWI-MRI sequences (D) demonstrate intratumoral diffusion restriction, with the ADC map (E) having a value of 0.73 × 10⁻³ mm²/s.

Figure 7

Malignant tumor—right parotid gland. Preoperative MRI. T1 sequence with a hypointense signal in the tumor (A). T2 sequence—inhomogeneous signal at the level of the lesion and the presence of micro-calcifications at the level of the lesion (B). DCE—MRI—TIC curve type B, with progressive contrast uptake followed by a plateau phase and washout (C). The DWI—MRI sequences (D) demonstrate restriction at the level of the solid component of the tumor, with the ADC map (E) having a value of 1 × 10⁻³ mm²/s.

Figure 8

Ultrasound-guided FNAB for a left parotid tumor. Identification of the most representative tumor region for performing FNAB and ultrasound confirmation of the presence of the needle in the tumor (A,B). The gun-type device used to perform the puncture (C).