Role of 99mTc-hexakis-2-methoxyisobutylisonitrile for detecting marrow metastases in childhood solid tumours.

Aim: To evaluate the role of 99mTc-hexakis-2-methoxyisobutylisonitrile (99mTc-MIBI) for detecting bone marrow metastases in childhood solid tumours, including lymphomas.

Methods: Twenty-six children (18 males, eight females) were studied. They all had proven malignant solid tumours [Hodgkin's lymphoma (5), non-Hodgkin's lymphoma (3), neuroblastoma (9), Ewing's sarcoma (3), Langerhans cell histiocytosis (4), rhabdomyosarcoma (1) and germ cell tumour (1)] with suspected bone marrow metastases. All patients underwent computed tomography and/or magnetic resonance imaging, 99mTc-MIBI and Tc-methylene diphosphonate bone scans and bone marrow aspiration and/or biopsy. The scintigraphic evaluation of 99mTc-MIBI scans was performed according to the visual assessment of the extent and intensity of uptake. The scintigraphic score, which is the sum of the extent and intensity of uptake, was calculated for each patient. Scores of more than 2 were considered to be positive for bone marrow involvement.

Results: Twenty-seven 99mTc-MIBI scans were studied for 26 patients. Twenty-two 99mTc-MIBI scans were accepted as normal bone marrow. Bone scans were also normal in these patients. Five of the 27 99mTc-MIBI scans had scores of more than 2. Bone marrow cytology revealed bone marrow metastases in these patients.

Conclusion: Abnormal 99mTc-MIBI uptake correlated extremely well with bone marrow aspiration/biopsy cytology results. Non-invasive 99mTc-MIBI imaging in children with malignant solid tumours appears to be promising for the evaluation of bone marrow metastases.