BREAST-TUMOR IMAGING WITH ULTRA-LOW FIELD MRI

Ultra low field MRI was evaluated for breast tumor imaging. Twenty-sev en patients with a known or suspected breast malignancy were imaged pr eoperatively with a T-2-weighted gradient-echo sequence. Additional IR - and gradient-echo sequences were used for measurements of T-1 and T- 2 relaxation times. Seventeen resected specimens were also imaged with in four hours after removal. Nineteen of 23 carcinomas detected at mam mography were also detected with MRI (sensitivity 83%), and one of fou r benign cases was evaluated as pathologic (specificity 75%). Most of the tumors had T-1 and T-2 relaxation times longer than those of norma l breast parenchyma. The T-1 values of the tumors were significantly d ifferent from the T-1 values of fat (p =.0002) and breast parenchyma ( p =.0151). The tumor T-2 values differed significantly from the T-2 of breast parenchyma (p =.0223) but not from that of fat (p =.1475). In vitro tumor measurements were similar to the in vivo measurements. Des pite these statistically significant findings, the calculated relaxati on times were not considered sufficiently reliable for the clinical ev aluation of breast tumors.