MR characteristics of benign lymph node enlargement in sarcoidosis and Castleman's disease.

The magnetic resonance characteristics of mediastinal and hilar lymphadenopathy were reviewed in five patients with sarcoidosis and one with Castleman's disease. Although the T1 values of 26 nodes measured in patients with sarcoidosis ranged from 390 to 786 msec (mean 549 msec; SD 88 msec), the mean values recorded for each patient were quite similar (range 501-616 msec). T2 values ranged from 40 to 68 msec (mean 49 msec; SD 7 msec). In the patient with Castleman's disease T1 and T2 values measured 838 msec and 45 msec respectively. In comparison to T1 and T2 values we have recently measured in patients with proven mediastinal lymph node metastases from bronchogenic carcinoma, lymph nodes in the patients with sarcoidosis have significantly lower T1 (p less than .001) and T2 (p less than .05) values. However, because of significant overlap between the values recorded in these two groups, their differentiation may be difficult in individual cases.