Identification of Prognostic Markers in Bone Sarcomas Using Proton-Decoupled Phosphorus Magnetic Resonance Spectroscopy
Magnetic Resonance Spectroscopy
It has been hypothesized that the (31)Phosphorus ((31)P) nuclear magnetic resonance spectrum from certain tumors may provide prognostic information. The goal of the present study was to identify prognostic metabolic markers by using proton-decoupled phosphorus magnetic resonance spectroscopic imaging ((31)P MRSI). Twenty patients with bone [osteogenic (OS) and Ewing's (ES) and/or primitive neuroectodermal tumor (PNET)] sarcoma, treated with chemotherapy and surgery or with chemotherapy alone, underwent (31)P MRSI studies pre- and post-therapy. The studies were performed on a 1.5 Tesla General Electric (GE) clinical scanner equipped with a stand-alone proton decoupler and a dual (1)H/(31)P surface coil pair. The limited sensitivity of the (31)P nucleus required that a large soft tissue component of the disease be located within 10 cm (maximum distance) of the body surface and the use of a highly sensitive coil placed near the skin surface. Proton decoupling and nuclear Overhauser enhancement were used to improve the spectral resolution and signal:noise ratio. Baseline (31)P spectral features and metabolic changes with treatment were compared with treatment outcome. The patients were categorized depending on survival as event-free survivors or those who died. The pretreatment nucleoside triphosphate:inorganic phosphate (NTP:P(i)) ratio, an index of tumor bioenergetic status, was significant (P = 0.003) in differentiating event-free survivors versus those who died. The pretreatment NTP:P(i) was higher in patients who were destined to undergo a durable event-free survival compared with those who died. The results are promising, although a prospective study is necessary for confirmation. (31)P MRSI appears to be a useful tool for the prediction of survival before therapy in bone sarcomas.