Abstract 5883: Estimation of blood volume collected on plasma-separating dried blood spots using gravimetric and imaging analysis

Abstract Background: Analysis of plasma-separating dried blood spots (psDBS) holds promise for circulating tumor DNA (ctDNA) measurement, enabling at-home sample collection, room temperature storage, and easy shipment. However, unlike collection in a blood tube, it is not feasible to directly measure blood volume collected from a fingerstick using psDBS. Here, we evaluate whether analysis of psDBS mass, color, and area can infer blood volume and enable downstream measurement of DNA concentration. Methods: Whole blood from patients with head and neck, breast, gynecologic, genitourinary, and gastrointestinal malignancies was collected on psDBS devices by the University of Wisconsin-Madison Carbone Cancer Center BioBank. In addition, whole blood from healthy individuals was commercially obtained and between five and nine psDBS were prepared with volumes ranging from 50 to 250 μL. All samples underwent analysis for mass, area, and color. psDBS were imaged using a flatbed scanner. Total area of erythrocytes and mean grey value of center erythrocytes were measured using image segmentation. Using mass of the psDBS membrane, erythrocyte area, erythrocyte mean grey value, and sex as predictors, a linear regression model was developed to predict whole blood volume. Mean absolute percent error (MAPE) was used to assess model accuracy. Results: One hundred ninety psDBS samples from 30 healthy individuals and 100 psDBS from 100 patients with cancer were analyzed. Using 132 samples from 20 healthy individuals (training set), a linear regression model was fit to the data, showing a very strong correlation between actual and predicted blood volume (MAPE = 7.6, Pearson r = 0.97). The model was then tested using 58 samples from 10 different healthy individuals (independent validation set), as well as psDBS from patients with cancer, and predicted blood volume collected on psDBS with high accuracy (MAPE = 6.8 and 9.3, respectively). Conclusion: Our results suggest estimating blood volume from psDBS is feasible using gravimetric and imaging analysis. By establishing a linear regression model that incorporates weight, area, and color, we can infer blood volume collected on psDBS samples for healthy individuals and patients with cancer. Ongoing work will incorporate this approach to enable measurement of plasma DNA concentration in blood spots. Citation Format: Elise C. Dietmann, Michelle D. Stephens, Olivia Krebs, Everlyne N. Nkadori, Pallavi Tiwari, Stephanie M. McGregor, Muhammed Murtaza. Estimation of blood volume collected on plasma-separating dried blood spots using gravimetric and imaging analysis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5883.