TY - JOUR T1 - A Prospective Study of Quantitative SPECT/CT for Evaluation of Lung Shunt Fraction Before SIRT of Liver Tumors JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 1366 LP - 1372 DO - 10.2967/jnumed.117.205203 VL - 59 IS - 9 AU - Helmut Dittmann AU - Daniel Kopp AU - Juergen Kupferschlaeger AU - Diana Feil AU - Gerd Groezinger AU - Roland Syha AU - Matthias Weissinger AU - Christian la Fougère Y1 - 2018/09/01 UR - http://jnm.snmjournals.org/content/59/9/1366.abstract N2 - The lung shunt fraction (LSF) is estimated using 99mTc-macroaggregated albumin (99mTc-MAA) imaging before selective internal radiotherapy (SIRT) of the liver to reduce the risk of pulmonary irradiation. Generally, planar scans are acquired after injection of 99mTc-MAA into the hepatic artery. However, the validity of this approach is limited by differences in attenuation between liver and lung tissue as well as inaccurate segmentation of the organs. The aim of this study was to evaluate quantitative SPECT/CT for LSF assessment in a prospective clinical cohort. Methods: Fifty consecutive patients intended to undergo SIRT were imaged within 1 h after injection of 99mTc-MAA using a SPECT/CT γ-camera. Planar scans of the lung and liver region were acquired in anterior and posterior views, followed by SPECT/CT scans of the thorax and abdomen. Emission data were corrected for scatter, attenuation, and resolution recovery using dedicated software. To quantify the radioactivity concentration in the lung, liver, urinary bladder and remainder of the thoracoabdominal body, volumes of interest were defined on the SPECT/CT images. 99mTc-MAA concentrations were calculated as percentage injected dose (%ID). Results: Mean 99mTc-MAA uptake in liver and lung accounted for only 79 %ID, whereas 13.1 %ID was present in the remainder of the body. In all patients, LSF as calculated from planar scans accounted for a median of 6.8% (range, 3.4%–32.3%), whereas the SPECT/CT quantitation revealed significantly lower LSF estimates, at a median of 1.9% (range, 0.8%–15.7%) (P < 0.0001, Wilcoxon test). On the basis of planar imaging, dose reduction or even contraindications to SIRT had to be considered in 10 of 50 patients, as their LSF was calculated at 10% or more. In contrast, SPECT/CT quantitation showed substantial shunting in only 2 of the 50 patients. Conclusion: Quantitative SPECT/CT reveals that the LSF is considerably lower than shown on planar imaging. Thus, the resulting dose to the lung parenchyma may be less than conventionally assumed. However, the safety of the SPECT/CT-derived dose range will have to be evaluated. ER -