Emily McCracken

Initial In Vivo Quantification of Tc-99m Sestamibi Uptake as a Function of Tissue Type in Healthy Breasts Using Dedicated Breast SPECT-CT

A pilot study is underway to quantify in vivo the uptake and distribution of Tc-99m Sestamibi in subjects without previous history of breast cancer using a dedicated SPECT-CT breast imaging system. Subjects undergoing diagnostic parathyroid imaging studies were consented and imaged as part of this IRB-approved breast imaging study. For each of the seven subjects, one randomly selected breast was imaged prone-pendant using the dedicated, compact breast SPECT-CT system underneath the shielded patient support. Iteratively reconstructed and attenuation and/or scatter corrected images were coregistered; CT images were segmented into glandular and fatty tissue by three different methods; the average concentration of Sestamibi was determined from the SPECT data using the CT-based segmentation and previously established quantification techniques. Very minor differences between the segmentation methods were observed, and the results indicate an average image-based in vivo Sestamibi concentration of 0.10 ± 0.16 μCi/mL with no preferential uptake by glandular or fatty tissues.

Quantification of tc-99m sestamibi distribution in normal breast tissue using dedicated breast SPECT-CT

The use of Tc-99m-Sestamibi in molecular breast imaging is common due to its preferential uptake in malignant tissue. However, quantification of the baseline uptake in normal, healthy breast tissue is not possible using planar-imaging devices. Using our dedicated breast SPECT-CT system, an IRB approved pilot study is underway to quantify mean activity in normal breast tissue, and to differentiate uptake between adipose and glandular tissues. A cohort of patients at normal breast cancer risk undergoing another diagnostic Sestamibi study was imaged using the breast SPECT-CT system. SPECT images were corrected and quantitatively reconstructed using previously developed methods, and registered with the CT images. The CT images were segmented, and the average activity concentration was measured for glandular, adipose, and total breast tissue. Results indicate no preferential uptake between tissues and low average uptake, which may be used to determine a universal threshold for cancer detection.

Severe anemia after Roux-en-Y gastric bypass: a cause for concern

BACKGROUND The current popularity of metabolic surgery has led to increasing attention to long-term nutritional complications. OBJECTIVE The purpose of this retrospective study is to accurately define the long-term incidence of clinically significant anemia after Roux-en-Y gastric bypass (RYGB) and to identify factors that contribute to increased risk. METHODS The study cohort consisted of 2116 patients who underwent RYGB with necessary laboratory information available, and with longitudinal follow-up available (mean 5.3 ± 3.3 yr). A concurrent cohort of nonoperated patients matched for age, sex, body mass index, and baseline hemoglobin was identified (N = 1126). The RYGB and control cohorts were followed longitudinally to estimate the percent that develop mild, moderate, or severe anemia using Kaplan-Meier analysis. Predictors of severe anemia within the RYGB cohort were identified using Cox regression. RESULTS The percent developing postRYGB mild, moderate, and severe anemia was 27%, 9%, and 2% at 1 year postRYGB and increased to 68%, 33%, and 11% at 5 years postRYGB. As compared with the nonoperated control cohort, the RYGB cohort was more likely to develop mild anemia (hazard ratio [HR] = 1.36, P<.001), moderate anemia (HR = 1.75, P<.001), and severe anemia (HR = 1.87, P<.001). Severity of anemia was associated with an increasing percentage of microcytosis (P<.0001). Clinical factors independently associated with an increased risk of severe anemia within the RYGB cohort included females and males>40 years of age (HR = 2.97, 95% confidence interval [CI] = 1.14, 7.75, P = .026), preoperative anemia (HR = 1.65, 95% CI = 1.19, 2.29, P = .0029), preoperative low ferritin level (HR = 2.28, 95% CI = 1.39, 3.74, P = .0029), and a rapid 6-month weight loss trajectory (HR = 1.71, 95% CI = 1.22, 2.38, P = .0018). CONCLUSIONS The long-term incidence of clinically significant anemia after RYGB is alarmingly high and warrants more detailed study.