Improved Quantification of MicroPET/CT Imaging Using CT-derived Scaling Factors.

Purpose: Combined micro-PET/CT scanners are widely employed to investigate models of brain disorders in rodents using PET-based coregistration. We examined if CT-based coregistration could improve estimates of brain dimensions and consequently estimates of nondisplaceable binding potential (BPND) in rodent PET studies. Procedures: PET and CT scans were acquired on 5 female and 5 male CD-1 mice with PET and CT scans were acquired on 5 female and 5 male CD-1 mice with 3-[18F]fluoro-5-(2-pyridinylethynyl)benzonitrile ([18F]FPEB), a radiotracer for the metabotropic glutamate receptor subtype 5 (mGluR5). In the proposed PET/CT (PTCT) approach, the tracer-specific standard volume was dimension-customized to each animal using the scaling factors from CT-to-standard CT coregistration to simplify PET-to-standard PET coregistration (i.e., 3 CT- and 6 PET-derived parameters). For comparison, conventional PET-based coregistration was performed with 9 (PT9) or 12 (PT12) parameters. PET frames were transferred to the standard space by the three approaches (PTCT, PT9, and PT12) to obtain regional time-activity curves (TACs) and BPND in 14 standard volumes of interest (VOIs). Lastly, CT images of the animals were transferred to the standard space by CT-based parameters from PTCT and with the scaling factors replaced with those from PET-based PT9 to evaluate agreement of the skull to the standard CT. Results: The PET-based approaches showed various degrees of underestimations of scaling factors in the posterior-anterior-direction compared to PTCT, which resulted in negatively proportional overestimation of radioactivity in the cerebellum (reference region) up to 20%, and proportional, more prominent underestimation of BPND in target regions down to -50%. The skulls of individual animals agreed with the standard skull for scaling factors from PTCT but not for the scaling factors from PT9, which suggested inaccuracy of the latter. Conclusions: The results indicated that conventional PET-based coregistration approaches could yield biased estimates of BPND due to erroneous estimates of brain dimensions when applied to tracers for which the cerebellum serves as reference region. The proposed PTCT provides evidence of a quantitative improvement over PET-based approaches for brain studies using micro-PET/CT scanners.

Reduced Expression of Cerebral Metabotropic Glutamate Receptor Subtype 5 in Men with Fragile X Syndrome.

Glutamatergic receptor expression is mostly unknown in adults with fragile X syndrome (FXS). Favorable behavioral effects of negative allosteric modulators (NAMs) of the metabotropic glutamate receptor subtype 5 (mGluR5) in fmr1 knockout (KO) mouse models have not been confirmed in humans with FXS. Measurement of cerebral mGluR5 expression in humans with FXS exposed to NAMs might help in that effort. We used positron emission tomography (PET) to measure the mGluR5 density as a proxy of mGluR5 expression in cortical and subcortical brain regions to confirm target engagement of NAMs for mGluR5s. The density and the distribution of mGluR5 were measured in two independent samples of men with FXS (N = 9) and typical development (TD) (N = 8). We showed the feasibility of this complex study including MRI and PET, meaning that this challenging protocol can be accomplished in men with FXS with an adequate preparation. Analysis of variance of estimated mGluR5 expression showed that mGluR5 expression was significantly reduced in cortical and subcortical regions of men with FXS in contrast to age-matched men with TD.

Early learners as health coaches for older adults preparing for surgery.

BACKGROUND: Few opportunities exist for early learners to engage in authentic roles on health care teams. In a geriatric optimization clinic for frail high-risk surgical patients, first-year medical and nurse practitioner students were integrated into an interprofessional team as health coaches. MATERIALS AND METHODS: Frail surgical patients with planned operations were referred to a new preoperative optimization clinic to see a geriatrician, occupational, and physical therapists and a nutritionist. A curriculum for health coaching by early learners was developed, implemented, and evaluated in this clinic. Students attended the clinic visit with their patient, reviewed the interdisciplinary care plan, and called patients twice weekly preoperatively and weekly in the first month after discharge. Students logged all calls, completed patient satisfaction surveys 1 wk before surgery and participated in feedback sessions with team members and medical school faculty. Call success rate was calculated, and team communications were recorded and analyzed. RESULTS: Median call success rate was 69.2% and was lowest among medical students (P = 0.004). Students and research assistants contacted or facilitated patient contact with their medical team 84 times. Overall, patients were extremely satisfied with the health coach experience, felt better prepared for surgery, and would recommend the program to others. CONCLUSIONS: Early medical and nurse practitioner students can serve the important function of health coaches for frail patients preparing for surgery. Motivated students benefited from a unique longitudinal experience and gained skills in communication and care coordination. Not all students demonstrated capacity to engage in health coaching this early in their education.

Postoperative Functional Outcomes in Older Adults.

As the world's aging population grows, the surgical population is increasingly made up of older adults. Due to changes in physiologic function and increasing comorbidity burden, older adults are at increased risk of morbidity, mortality, and functional decline after surgery. In addition, decision to undergo surgery for the older adult may be based on the postoperative functional outcome rather than survival. Although few studies have evaluated an older adult's function as a postoperative outcome, surgeons are becoming increasingly aware of the importance of maintaining or regaining function in an older patient. Interventions to improve postoperative functional outcomes are being developed and show promising results. This review discusses existing literature on postoperative functional outcomes in older adults and recently developed interventions.