Combining anatomical and functional imaging can improve sensitivity and accuracy of
tumor diagnosis and surveillance of pediatric
malignancies. MRI is the state-of-the-art modality for demonstrating the anatomical location of
brain tumors with contrast enhancement adding additional information regarding whether the
tumor is neuronal or glial. Addition of SPECT imaging using a
peptide that targets the
somatostatin receptor (
Octreoscan) can now differentiate
medulloblastoma from a cerebellar
pilocytic astrocytoma. Combined MRI and
Octreoscan is now the most sensitive and accurate imaging modality for differentiating recurrent
medulloblastoma from
scar tissue. CT is the most common imaging modality for demonstrating the anatomical location of
tumors in the chest and abdomen. Addition of SPECT imaging with either
MIBG or
Octreoscan has been shown to add important diagnostic information on the nature of
tumors in chest and abdomen and is often more sensitive than CT for identification of metastatic lesions in bone or liver. Combined anatomical and functional imaging is particularly helpful in
neuroblastoma and in
neuroendocrine tumors such as
gastrinoma and
carcinoid. Functional imaging with
MIBG and
Octreoscan is predictive of response to molecularly targeted
therapy with 131I-MIBG and 90Y-DOTA-tyr3-Octreotide. Dosimetry using combined anatomical and functional imaging is being developed for patient-specific dosing of
targeted radiotherapy and as an extremely sensitive monitor of response to
therapy. Both
MIBG and
Octreotide are now being adapted to PET imaging which will greatly improve the utility of PET in
medulloblastoma as well as increase the sensitivity for detection of metastatic lesions in
neuroblastoma and
neuroendocrine tumors.