Diffusivity of intraorbital lymphoma vs. inflammation: comparison of single shot turbo spin echo and multishot echo planar imaging techniques.

PURPOSE: To compare the abilities of turbo spin-echo diffusion-weighted imaging (TSE DWI) and multi-shot echo planar DWI (MSh DWI) to discriminate orbital lymphoma from inflammatory lesions.

MATERIALS AND METHODS: Twenty-nine patients with pathologically confirmed lymphomas and 39 patients with inflammation were imaged with a 3.0-T system. The apparent diffusion coefficient (ADC) of each lesion was measured. Signal intensities compared to normal grey matter on conventional imaging were also measured.

RESULTS: The ADCs derived from the TSE DWI of the lymphomas (0.68 ± 0.14 × 10-3 mm2 /s) were significantly lower than those of the inflammation cases (1.04 ± 0.39 × 10-3 mm2 /s; p < 0.001). The ADCs derived from MSh DWI could not be used to separate the lymphomas from the inflammation (1.16 ± 0.43 × 10-3 mm2 /s vs. 1.36 ± 0.48 × 10-3 mm2 /s; p = 0.06). Conventional sequences also could not separate the lymphomas from the inflammation (p > 0.05). The ROC analysis showed the best diagnostic performance with ADCs derived from TSE DWI (the area under the curve: AUC = 0.831) followed by ADC derived from MSh DWI (AUC = 0.633).

CONCLUSION: The ADCs derived from TSE DWI might help to differentiate orbital lymphomas from inflammation.

KEY POINTS: • ADC of lymphoma was significantly lower than that of inflammation. • ADC derived from TSE DWI showed the best diagnostic performance. • This study was conducted by a 3-T MR scanner.