Review of functional/anatomical imaging in oncology.

Patient management in oncology increasingly relies on imaging for diagnosis, response assessment, and follow-up. The clinical availability of combined functional/anatomical imaging modalities, which integrate the benefits of visualizing tumor biology with those of high-resolution structural imaging, revolutionized clinical management of oncologic patients. Conventional high-resolution anatomical imaging modalities such as computed tomography (CT) and MRI excel at providing details on lesion location, size, morphology, and structural changes to adjacent tissues; however, these modalities provide little insight into tumor physiology. With the increasing focus on molecularly targeted therapies, imaging radiolabeled compounds with PET and single-photon emission tomography (SPECT) is often carried out to provide insight into a tumor's biological functions and its surrounding microenvironment. Despite their high sensitivity and specificity, PET and SPECT alone are substantially limited by low spatial resolution and inability to provide anatomical detail. Integrating SPECT or PET with a modality capable of providing these (i.e. CT or MR) maximizes their separate strengths and provides anatomical localization of physiological processes with detailed visualization of a tumor's structure. The availability of multimodality (hybrid) imaging with PET/CT, SPECT/CT, and PET/MR improves our ability to characterize lesions and affect treatment decisions and patient management. We have just begun to exploit the truly synergistic capabilities of multimodality imaging. Continued advances in the development of instrumentation and imaging agents will improve our ability to noninvasively characterize disease processes. This review will discuss the evolution of hybrid imaging technology and provide examples of its current and potential future clinical uses.

Aging attenuates the pituitary response to gonadotropin-releasing hormone.

CONTEXT: Complex changes in GnRH secretion occur with aging in women, but little is known about the effect of aging on the pituitary per se. OBJECTIVE: The aim of the study was to determine whether pituitary responsiveness to GnRH is attenuated with aging. DESIGN AND SETTING: A GnRH antagonist and graded doses of GnRH were used to isolate pituitary responsiveness in Clinical Research Center studies at an academic medical center. SUBJECTS: Subjects were healthy postmenopausal women (PMW) aged 48-57 yr (n = 10) or 70-77 yr (n= 9). INTERVENTIONS: A suppressive dose of the NAL-GLU GnRH antagonist (150 microg/kg sc) was administered and was followed by GnRH doses of 25, 75, 250, or 750 ng/kg iv every 4 h. RESULTS: The LH response to GnRH was attenuated with aging (P = 0.05) with an interaction between age and dose (P = 0.01) such that the LH amplitude was less in older PMW at the higher doses (250 ng/kg, 50 +/- 9 vs. 29 +/- 4.9 IU/liter, for young and old PMW, respectively, P = 0.02; and 750 ng/kg, 97.7 +/- 11 vs. 70.2 +/- 9.3 IU/liter, P = 0.002), but not the lower doses of GnRH. The FSH response to GnRH was also attenuated with aging in PMW (P = 0.005). CONCLUSIONS: In studies that isolated the pituitary from endogenous GnRH stimulation, aging attenuated the LH and FSH responses to exogenous GnRH in PMW. These studies indicate that the pituitary plays a role in the decline in gonadotropin levels with aging, further supporting the potential contribution of age-associated changes in both hypothalamic and pituitary function to reproductive senescence.