Abstract
4099
Introduction: Background: Somatostatin receptor scintigraphy using indium-111 (111In)-pentetreotide is a standard technique for the diagnosis of neuroendocrine tumors. Because most of the tracer is excreted in urine, the effect of radiation-absorbed dose on kidneys is significant. However, the degree of accumulation or residence time in the kidneys may differ depending on the renal function. Purpose: The purposes of this study were evaluation of standard uptake value (: SUV) and washout rate (: WOR) compared to renal function in 111In-pentetreotide single-photon emission tomography/ computed tomography (SPECT/CT).
Methods: Methods: Forty-seven patients who were undergone abdominal SPECT/CT at both four and twenty-four hours after 111In-pentetreotide injection were retrospectively enrolled. Mean SUV and WOR were calculated on liver, kidney and spleen. The correlation between SPECT parameters and related renal function obtained within a month before or after examination were analyzed. eGFR was calculated by the following formula. eGFR[male] = 194 × Scr-1.094 × age, eGFR[female] = eGFR[male] × 0.739. (Scr: serum creatinine) In order to calculate precise administered dose, radioactivity of pre and post injection were measured by dose calibrator. All patients urinated and measured body weight before each acquisition. Acquisition parameters were follows; matrix size: 128×128, pixel size: 4.8 mm, slice thickness: 4.8 mm, scan duration: 50sec/view×36 views, acquisition angle: 5 degree. Energy windows of photo peak were set to 171 keV±20% and 245 keV±20%. SPECT images was reconstructed using iterative reconstruction method with resolution recovery correction (iteration = 10, subsets = 9) with a 12-mm Gaussian filter. For scatter and attenuation correction, the multiple energy window method and a CT-based method were employed.
Results: Results: SUVs of kidney were 5.03 ± 1.37 (eGFR ≧ 60) and 7.69 ± 3.82 (eGFR < 60) at twenty-four hours, respectively. WORs of kidney were 0.24 ± 0.10 (eGFR ≧ 60) and 0.08 ± 0.22 (eGFR < 60), respectively. Results of other organs were shown Figure 1 and 2.
Conclusions: Conclusion: Impairment of renal function was found to increase SUV at twenty-four hours post injection and decrease WOR for 111In-pentetreotide. Further studies are warranted to evaluate whether increased residence time by reduced GFR can be used to estimate the kidney uptake in the 177Lu-DOTATATE therapy.
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