Apparent diffusion coefficient values of mediastinal masses in children

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Abstract

Objective

Compare apparent diffusion coefficient (ADC) values between benign and malignant mass lesions in a cohort of children referred for imaging of a mediastinal mass.

Material and methods

Prospective study including 24 consecutive children (11 boys, 13 girls aged 5 months to 16 years). All underwent echo planar diffusion weighted MR imaging of the mediastinum with b-factors of 0 and 600 s/mm2. Apparent diffusion coefficient (ADC) values were calculated and correlated with the surgical finding or biopsy.

Results

The mean ADC value of malignant mediastinal tumors was 0.91 (S.D., 0.17) ×10−3 mm2/s and of benign lesions 1.8 (S.D., 0.33) ×10−3 mm2/s. There was significant different in the ADC value between malignant tumors and benign mediastinal tumors (P < 0.001). Selection of 1.2 × 10−3 mm2/s as a threshold value for differentiating malignant from benign mediastinal masses has an accuracy of 93%, sensitivity of 92%, specificity of 94%, positive predictive value of 94%, negative predictive value of 92% and area under the curve of 0.962.

Conclusion

Apparent diffusion coefficient value is a promising non-invasive parameter for assessment of mediastinal mass in children.

Introduction

Mediastinal masses in children include a spectrum of malignant tumors and benign lesions. Differentiation of malignant mediastinal tumors from benign lesions is essential for treatment planning as well as for prediction of prognosis. CT and MR imaging are commonly used for assessment, but cannot accurately differentiate benign from malignant masses [1], [2]. Ultrasound has a role in evaluation of cystic lesions but it cannot determine the nature of solid mediastinal masses, and it is operator dependent [3]. Biopsy is the gold standard but, it is invasive and may be associated with sampling error [4].

Diffusion weighted MR imaging is a non invasive technique that reflect tissue cell density. Diffusion weighed MR imaging has been used in characterization of abdominal, skeletal, head and neck tumors and neuroblastoma in children and for assessment of mediastinal masses and lymph nodes in adults [5], [6], [7], [8], [9], [10], [11], [12], [13].

The aim of this work was to compare apparent diffusion coefficient (ADC) values between benign and malignant mass lesions in a cohort of children referred for imaging of a mediastinal mass.

Section snippets

Material and methods

A prospective study was carried out in 31 consecutive children with mediastinal masses who were referred from a pediatric university hospital and a pediatric department at a university oncology center to a radiology and imaging department of a main university hospital after thorough clinical examination. The inclusion criterion was a mediastinal mass at plain X-ray or CT scan that had not undergone surgery, radiotherapy or chemotherapy before MR imaging. Patients presented with cough [n = 26],

Results

The mean ADC value of malignant mediastinal tumors [n = 14] was 0.91 (S.D., 0.17) ×10−3 mm2/s and of benign lesions [n = 10] was 1.8 (S.D., 0.33) ×10−3 mm2/s. Table 1 shows the ADC value of malignant and benign mediastinal masses. There was a significant difference in the ADC values of malignant and benign masses [P < 0.001]. When an apparent diffusion coefficient value of 1.2 × 10−3 mm2/s was used as a threshold value for differentiating malignant from benign mediastinal masses, the best results were

Discussion

There have been a few limited studies on the role of diffusion weighted MR imaging of mediastinal masses [9] and lymph nodes in adults [10], [11], [12]. The mean ADC value of adult malignant mediastinal tumors has been reported significantly lower corresponds to benign tumors. Selection of 1.56 × 10−3 mm2/s as a cutoff for differentiating malignant from benign mediastinal mass had an accuracy of 95%, sensitivity of 96%, and specificity of 94% [9].

In our study, the mean ADC value of malignant

Conclusion

Apparent diffusion coefficient value is a promising non-invasive parameter for assessment of mediastinal mass in children and offer useful information for grading of mediastinal malignancy.

References (18)

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Presented at Assembly and Annual Meeting of Radiological Society of North America as oral presentation.

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