Does I-131-MIBG underestimate skeletal disease burden in neuroblastoma?

BACKGROUND: Controversy persists as to the need for both MIBG and bone scanning in routine evaluation of neuroblastoma. AIM: To compare the efficacy of I-131- metaiodobenzylguanidine (MIBG) scan against that of conventional Tc99m- methylene diphosphonate (MDP) bone scan for the detection of skeletal deposition of neuroblastoma. METHODS AND MATERIAL: The study included 57 patients (36 boys, 21 girls: age range 1-14 years) of neuroblastoma who underwent both bone scan with Tc99m-MDP and I-131-MIBG scan within 15 days of each other at presentation and during follow-up. RESULTS: At presentation 11(19.2%) patients had evidence of skeletal metastases on MDP scan against 7 patients who showed bony secondaries on MIBG scan. Of the 7 patients, with positive MIBG and MDP scans, MDP scan detected 11 sites whereas MIBG scan detected 7 sites. On follow-up study, 3 patients with initial abnormal MDP scan but normal MIBG scan, developed skeletal metastases detectable on MIBG scan, whereas 3 of the 46 patients who had normal MDP and MIBG scan at presentation; developed skeletal metastases detectable on MDP scan. MIBG scan was concordant in 2 of them but was normal in the third patient. CONCLUSION: I-131-MIBG underestimates skeletal disease burden in neuroblastoma. Therefore, Tc99m-MDP bone scan should remain a part of routine assessment of patients with neuroblastoma.

Role of skeletal scintigraphy in soft tissue sarcoma: Improving the diagnostic yield.

BACKGROUND: The presence of skeletal metastases significantly influences the therapeutic strategy adopted for soft tissue sarcoma. However, literature on the prevalence of skeletal metastases in soft tissue sarcoma is limited and none of the available data is based on the Indian patient population. AIM: To determine the prevalence of skeletal metastases at presentation in patients of soft tissue sarcoma and to rationalise the use of preoperative skeletal scintigraphy in such patients. METHODS AND MATERIAL: Preoperative bone scans were evaluated in 122 patients with soft tissue sarcoma (median age, 34 years; range, 4-83). The scans were classified into 3 grades: Grade 1: metastases very likely; Grade 2: equivocal; Grade 3: normal or benign lesion. In all the patients studied, the ability of the patient to localize the site or sites of pain was recorded and that was correlated with the site of metastases in scintigraphy. RESULT: Seventeen (13.9%) patients had Grade 1 scan; 16 of them had bony pain that was not readily explainable by trauma or other local factors. Ten ( 8.1%) patients had Grade 2 scan, five of them had bony pain which was not readily explainable by trauma or other local factors. Ninety-five patients (77.8%) had Grade 3 scan. Of these, 9 had localised bone pain which could be definitely associated with trauma or joint degeneration. CONCLUSION: The prevalence of skeletal metastases at presentation in patients with soft tissue sarcoma is low (13.9%). The low rates of skeletal metastases in bone pain-free patients (0.9%) versus the high rate in symptomatic patients (76.1%) supports the use of bone scanning in symptomatic patients only.

Bone scans in neuroblastoma.

Eighty-Six patients of neuroblastoma ranging in age from four months to 15 years were studied with 99m Tc-MDP for total skeletal survey over a period of seven years (1983-1990). The diagnosis of neuroblastoma was based on bone marrow examination, FNAC, lymph node biopsy, histopathology. Bone imaging was performed three hrs. after intravenous administration of 99m Tc-MDP. Out of 86 patients, 45 patients had positive bone scan showing osseous concentration in 122 sites and extraosseous concentration in 34 sites. Seven patients had liver metastases. None of these liver metastases showed concentration of MDP. Fourteen patients underwent surgery for the primary tumour at the time of bone scanning. Ten patients were studied at the time of follow up, of which four patients showed good response as bony metastases were not demonstrated on bone scintigraphy and X-rays. In conclusion, bone scan is an useful test in neuroblastoma in delineating the bony metastases and also in assessing the efficacy of chemotherapy in these patients.

Pulmonary metastases on bone scan in a patient with osteogenic sarcoma.

This paper describes a young man who was treated with amputation for osteogenic sarcoma of the lower end of the right tibia. Pre-operative whole body bone scan with 99 mTc did not reveal abnormal tracer concentration in the lungs. A similar follow-up bone scan six months post-operatively demonstrated an area of abnormal tracer concentration in the lower lobe of each lung.