ENHANCED BOLD RESPONSE IN BREAST TUMORS INDUCED BY BREATH HOLDING

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Current protocols for tumor imaging, specifically applied with breast cancer candidates, call for the use of pharmaceutical contrast agents. These agents require intravenous injection causing additional discomfort to the patient while also requiring qualified personnel to start the IV. An alternative that allows for a totally non-invasive procedure, by simply exploiting the innate physiology of tumors, is ideal. A defining property of tumors is their high affinity for oxygen, causing regionally altered perfusion characteristics. BOLD imaging, most commonly used in fMRI studies, measures the hemodynamic variation in a given region resulting from a stimulating task. Simple breath holding, which induces hypoxia, shows an increased BOLD response in fMRI studies due to variation of the oxygen levels in the bloodstream. This study demonstrates the BOLD response in the breast resulting from periodic hypoxia, and its promise in differentiating tumors from other breast tissue. The scan protocol used a 3D ¿stack of spirals¿ imaging sequence with a spectral-spatial pulse for fat suppression. Two healthy volunteers (both age 24) and one breast tumor patient (age 36) participated in the study. The healthy volunteers were scanned on a 1.5T Signa GE scanner, while the patient was scanned on a 1.5T Twin GE scanner. Each participant held their breath for 15 s intervals followed by 15 s of regular breathing, for 7 cycles. Data analysis of BOLD results applied a time course correlation method established by Adrian Lee et al. The method correlates the breath holding cycle to sinusoidal functions. Malignant regions present in Gd enhanced images paralleled regions observed in early response BOLD images stimulated by hypoxia. As expected, carcinogenic regions responded earlier than healthy regions under hypoxic conditions, with results indicating a 7.5 s time delay between the malignant verses healthy tissue. This study demonstrates how BOLD images can identify tumor regions without contrast agents, with the potential of providing additional diagnostic information.