Differentiation of benign and malignant pathology in the head and neck using 3T apparent diffusion coefficient values: early experience

Abstract

Background and purpose: The purpose of this work was to study differences in apparent diffusion coefficient (ADC) values between benign and malignant head and neck lesions at 3T field strength imaging.

Materials and methods: Our study population in this retrospective study was derived from the patient population who had undergone routine neck 3T MR imaging (for clinical indications) from December 2005 to December 2006. There were 33 patients identified: 17 with benign and 16 with malignant pathologies. In all of the subjects, conventional MR imaging sequences were performed apart from diffusion-weighted sequences. The mean ADC values in the benign and malignant groups were compared using an unpaired t test with unequal variance with a P < 0.05 considered statistically significant.

Results: There was a statistically significant difference (P = .004) between the mean ADC values (in 10(-3) mm(2)/s) in the benign and malignant lesions (1.505 +/- 0.487; 95% confidence interval, 1.305-1.706, and 1.071 +/- 0.293; 95% confidence interval, 0.864-1.277, respectively). There were 2 malignant lesions with ADC values higher than 1.3 x 10(-3) mm(2)/s and 5 benign lesions with ADC values less than 1.3 x 10(-3) mm(2)/s. The lack of overlap of ADC values within 95% confidence limits suggests that a 3T ADC value of 1.3 x 10(-3) mm(2)/s may be the threshold value for differentiation between benign and malignant head and neck lesions.

Conclusion: ADC values of benign and malignant neck pathologies are significantly different at 3T imaging, though larger studies are required to establish threshold ADC values that can applied in daily clinical practice.

Fig 1.

Scatter plot of ADC values in benign and malignant head and neck lesions at 3T strength.

Fig 2.

A, T2-weighted axial image in a 35-year-old male patient with pathologically proved sinonasal undifferentiated carcinoma reveals a mass lesion in the left ethmoidal region (black arrows) with resultant sphenoidal mucocele (white arrows). B, The mass demonstrates heterogeneous enhancement (black arrows) on the post-gadolinium axial T1 image with no enhancement within the mucocele (white arrows). C, The ADC in the lesion averaged 1.042 × 10⁻³ mm²/s.

Fig 3.

Axial T2-weighted (A) and postcontrast T1-weighted (B) images in a 22-year-old female patient demonstrate a T2 hyperintense lesion with intense contrast enhancement within the right masseter (black arrows), which was a biopsy-proven hemangioma. C, The ADC within the lesion measured 1.842 × 10⁻³ mm²/s.

Fig 4.

Axial T2-weighted (A) and postcontrast T1-weighted (B) images in a 40-year-old female patient demonstrate a destructive left skull base pathology with heterogenous hyperintensity and cystic areas on T2-weighted images (black arrows) and nonenhancing portions on the postcontrast images (black arrows). This was a biopsy-proven adenosquamous cell carcinoma with an increased ADC value averaging 1.649 × 10⁻³ mm²/s, probably due to the necrotic areas within the tumor.

Fig 5.

Axial MR images in a 29-year-old woman reveal a left jugular foramen mass that is hypointense on T2-weighted (A) images and enhances with contrast (B). This was a biopsy-proven meningioma with a decreased ADC value of 0.669 × 10⁻³ mm²/s, which may be due to hypercellularity within the benign tumor.