Quantitative analysis in parathyroid adenoma scintigraphy.

Abstract

OBJECTIVE\nSurgery is the only curative treatment for primary hyperparathyroidism. Parathyroid scintigraphy is one method used to preoperatively localize the lesion. We examined time-related changes in radiopharmaceutical uptake in parathyroid adenomas (PTAs) and thyroid gland by quantitative single-photon-emission computed tomography (SPECT) imaging to assess differences between rapid and delayed washout patterns.\n\n\nPATIENTS AND METHODS\nThe study group consisted of 35 histologically verified PTAs after radio-guided surgery extirpation in 33 patients with primary hyperparathyroidism. Patients underwent a three-phase SPECT/CT study of the neck and upper thorax post 99mTc-methoxyisobutylisonitrile (MIBI) injection. Images were reconstructed using a proprietary ordered-subset-conjugate-gradient-maximization algorithm (Siemens xSPECT Quant). PTAs were divided into those with a rapid (group A) and those with a slow (group B) washout pattern. SUVmax values of PTAs and thyroid gland tissue at 10, 90 and 180\u2009min post 99mTc-MIBI injection were recorded and statistically assessed. Retention indexes related to the early examination were calculated for PTA and thyroid gland (RI-PTA and RI-TG).\n\n\nRESULTS\nThere were 11 PTAs in group A and 24 in group B. Significant between-group differences in PTA SUVmax and PTA/thyroid gland ratios were observed only at 180\u2009min postinjection (P\u2009=\u20090.0297, P\u2009=\u20090.0222, respectively). RI-PTAs differed significantly at 90 and 180\u2009min postinjection (P\u2009=\u20090.0298, P\u2009=\u20090.0431). No differences in PTA volumes, thyroid gland SUVmax values or RI-TG were observed between the groups.\n\n\nCONCLUSION\nPTAs with rapid and slow washout patterns have different characteristics on quantitative analysis in later phases. No significant differences in directly measurable quantitative values (SUVmax, PTA/thyroid gland ratio) at the early stages of multi-phase examination were observed.