Role of respiratory-triggered diffusion-weighted MRI in the assessment of pleural disease.

Abstract

To evaluate the correlation between apparent diffusion coefficient (ADC) values and histopathological features in a cohort of patients with suspected malignant pleural disease. We evaluated 56 consecutive patients undergoing a chest MRI examination for clinical suspicion of malignant pleural disease; all patients underwent thoracoscopic biopsy for histological assessment. All MRI examinations were performed with a 1.5-T scanner using a dedicated protocol, including a respiratory-triggered diffusion-weighted sequence with three b-values (0, 100 and 750). The ADC values were calculated, and a statistical analysis was performed. The average ADC value in non-neoplastic pleural disease (NNPD) resulted in 1.84 ± 0.37 × 10-3 mm2 s-1, whereas we obtained an average value of 0.96 ± 0.19 × 10-3 mm2 s-1 in epitheliod, of 0.76 ± 0.33 × 10-3 mm2 s-1 in biphasic and of 0.67 ± 0.2 × 10-3 mm2 s-1 in sarcomatoid pleural mesotheliomas. Histology revealed the presence of malignant pleural mesothelioma (MPM) in 44 patients, chronic pleuritis in 8 patients and atypical mesothelial hyperplasia in 4 patients. Statistical analysis showed a significant difference between NNPD and MPM (p < 0.001) and between epithelioid and sarcomatoid MPM subtypes (p = 0.0004), whereas biphasic MPMs showed a wide range of overlapping with the other groups. We observed a statistically significant difference between NNPD, epitheliod and sarcomatoid subtypes of MPM regarding ADC values. Our study confirmed previous data regarding distribution of ADC values in pleural disease using a respiratory-triggered diffusion-weighted technique that allowed us to minimize motion artefacts and to reduct acquisition time.