Dynamic gadolinium uptake in thermally treated canine brain tissue and experimental cerebral tumors

RATIONALE AND OBJECTIVES. Thermal coagulation of cerebral tumors induces reactive changes within adjacent brain tissue, which appear as Gd-DTPA enhancement in MR images. This makes assessment of therapeutic success difficult to establish radiographically because the reactive changes can mimic residual tumor. Dynamic Gd-DTPA uptake curves in reactive tissue and tumor were investigated to assess the utility of contrast enhanced (CE)-dynamic MRI to distinguish reactive changes from residual tumor in a canine model. MATERIALS AND METHODS. Cerebral thermal necrosis was induced using a 980 nm laser in 11 dogs with intracerebral transmissible venereal tumors (TVTs). A fast spin-echo T1-weighted imaging sequence was used for CE-dynamic MRI. Gd-DTPA uptake data were acquired with 10-second temporal resolution and for untreated TVTs for reactive tissue using a sigmoidal-exponential model. RESULTS. Characteristic gadolinium uptake curves were measured and characterized for reactive brain tissue, and untreated and treated TVTs. Both early and delayed dynamic responses were significantly different in reactive brain tissue compared with TVT. CONCLUSION. Reactive thermal changes in otherwise normal brain tissue can be distinguished from residual tumor after cerebral thermal therapy using CE-dynamic MRI.