Magnetic resonance imaging to detect bone marrow metastases in the initialstaging of small cell lung carcinoma and breast carcinoma

BACKGROUND. Bone marrow is a common site of metastases in patients with sma ll cell lung carcinoma (SCLC) and female breast carcinoma (FBC). Metastatic bone marrow involvement is found in approximately 50% of SCLC patients and up to 85% of FBC patients at autopsy. initial staging procedures detect ma lignant bone marrow lesions in only 2-30% of patients with these tumors. Th is study was performed to assess whether MRI can improve the detection rate of bone marrow metastases in tumors with a high incidence of skeletal invo lvement. METHODS, Fifty-two patients with histologically verified SCLC (25 with limi ted stage disease and 27 with extensive stage disease) and 33 women with FB C were entered into a prospective study. The MRI protocol was comprised of coronal slices in the pelvic region and sagittal slices of the whole spine utilizing a T1-weighted spin echo sequence with a held of view of 50 cm. Al l patients underwent initial routine diagnostic staging procedures includin g bone scintigraphy, unilateral crest biopsy, and plain film radiography of suspicious skeletal areas. RESULTS. Only in two SCLC patients, MRI was positive in 25 cases. All SCLC patients with bone marrow lesions histologically verified, diagnosed by cre st biopsy (six patients) or by bone scan (seven patients) had the correct d iagnosis of metastases by MRI. In addition MRI revealed hypointense bone ma rrow foci in 14 cases. In contrast, 28 of 33 FBC patients examined during t he initial staging procedure showed no evidence of bone marrow involvement. MRI was not superior compared with bone scintigraphy in FBC patients. CONCLUSIONS. The staging results obtained in SCLC and FBC patients are diff erent, although both tumors have a high incidence of bone marrow metastases . It may be assumed that the biologic behavior of these tumors is reflected by the initial bone marrow involvement. Because of its superiority compare d with biopsy and bone scan, the authors believe MRI should become an integ ral part of the initial staging procedures in patients with SCLC. When stag ing patients with FBC, MRI should be applied only in clinically indicated c ases. (C) 1999 American Cancer Society.