Thallium-201 scintigraphy and chemotherapeutic response in rhabdomyosarcoma.

Thallium-201 scintigraphy was used to evaluate chemotherapeutic response in a case of rhabdomyosarcoma treated with epirubicin. A scintigraphic semiquantitative index of tumor viability was correlated with MRI and clinical assessment. Both imaging studies were performed before therapy and after treatment involving a cumulative dose of 640 mg/m2 of epirubicin. A very good inverse correlation was observed between Tl-201 uptake and tumor necrosis evaluated by MRI, leading to the conclusion that sequential Tl-201 scintigraphy may have a role not only in delineating the extent of the tumor, but in objectively assessing tumor response to therapeutic interventions. The proposed scintigraphic method is much simpler to perform and less expensive than MRI-derived semiquantitative measurement of tumor necrosis.