Tc-99m DTPA used as reference imaging to evaluate the distribution of other tumor-seeking tracers in tumors associated with neurofibromatosis.

Two patients with multiple benign and malignant tumors associated with neurofibromatosis underwent radionuclide imaging with Tc-99m DTPA, Tl-201, and Ga-67. In these patients, Tc-99m DTPA accumulated intensively in both the benign and malignant tumors and localized and defined the extent of every tumor. In contrast, Ga-67 and Tl-201 uptake was seen only in focal areas of tumor where there was malignant transformation or at sites that showed progressive tumor growth. Tc-99m DTPA imaging accurately demonstrated areas of neoplastic involvement and identified the areas that would be seen with the other two tracers in individual tumors. Tc-99m DTPA may not always be used for the differential diagnosis of malignant and benign tumors of neurofibromatosis, but it can provide a reference pattern for imaging to evaluate accurately the distribution of Tl-201 and Ga-67 by mapping out the anatomic extent of these tumors.