TY - JOUR T1 - A model for quantification of arm lymphedema in women following treatment for breast cancer JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 1300 LP - 1300 VL - 58 IS - supplement 1 AU - Jane Simonsen AU - Poul Flemming Hoilund-Carlsen AU - Navid Toyserkani AU - Jens Sorensen AU - Svend Hvidsten Y1 - 2017/05/01 UR - http://jnm.snmjournals.org/content/58/supplement_1/1300.abstract N2 - 1300Objectives: To develop a method for quantification of lymphatic function in women with unilateral lymphedema following breast cancer treatment. This novel approach should differ from previous models based on removal rate from the injection site and correlating poorly with lymphedema, or uptake in axillary lymph nodes, which markedly reduced their clinical usefulness.Methods: Bilateral 99mTc-HSA lymphoscintigraphy with planar imaging of the entire upper limbs was obtained in 11 supine women (aged 34-68 years) with unilateral arm lymphedema following surgical treatment of breast cancer. A dynamic acquisition with 30 1-min frames was performed immediately after injection followed by 5-min scans every 30-45 min for the next 4½ hours. In between imaging, subjects were allowed to sit or walk around. Scans were used for reading of arm time activity curves (TACs), each of which was thought to be a product of the input to the arm and the transit through the arm with lymphedema resulting from a slow transit. Regions of interest covering the injection sites, the entire arms and adjacent background correction areas were drawn manually. TACs from injection sites were approximated by a simple function termed Inj(t), in that the first phase within the first 30 min was assumed to be constant while the second phase beyond 60 min was fitted with an exponential function, exp(-𝞴;t). In between these two phases, the TAC was approximated by a linear curve. The removal rate was calculated as 100% 𝞴;. Assuming that all activity cleared from the injection site entered the lymphatic system of the arm, the input function was the time derivative (minus) of the injection TAC, I(t) = -d/dt Inj(t). The retention of lymph in the arm, R(t), was modelled by a two-component model consisting of a Fermi function to describe a slow transit and a Dirac delta function corresponding to a fast transit through the region: R(t) = k((1+e-α/β)/(1+e(t-α)/β))/(1-k)δ(t). Measured arm TAC was modelled by convolution of the input function and the retention function: Arm(t) ≍ R(t) [asterisk] I(t), and the integral of this function in relation to the activity injected was defined as the mean transit time, MTT. This expression could be reduced to the integral of the retention function, which was found by fitting the k, α, and β parameters to the measured arm TAC.Results: Injection TACs generally showed a lag phase corresponding to sparse drainage for the first 30 min. In the second phase beyond 60 min activity fell exponentially. Removal rates did not differ between lymphedema and normal arms, being 0.127% min-1 and 0.132% min-1, respectively, p=0.81. Arm TACs generally showed sparse activity for the first 30 min and increases thereafter. All but two demonstrated a summit followed by a decrease. Good fits were obtained for all (Figure 1). Mean MTT was significantly longer in lymphedema arms than normal arms, 60.1±27.7 min vs. 5.4±2.5 min, p<0.0001. The difference varied by a factor of 3-50, on average 15. From the curves it was clear that mere reading of uptake as a percentage of injected doses did not identify differences in MTT.Conclusion: This novel quantification of tracer transportation through the lymphatic system is objective and could be useful for diagnosing of lymphedema and for evaluation of treatment response. It is independent of the injected tracer dose and exempt from variations in injection site and technique. Moreover, it can be applied after lymphadenectomy and does not require a healthy control arm. A special perspective might be post-operative application to predict the risk of lymphedema development. Research Support: Navid M. Toyserkani is a PhD candidate and received PhD scolarships from The PhD Research Fund at Odense University Hospital and The PhD Research Fund at University of Southern Denmark, Odense, Denmark. ER -