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Radiopharmaceuticals for Diagnostics
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
Jim Ballinger, Jacek Koziorowski
The parathyroid glands, located adjacent to the thyroid, regulate the body’s use of calcium. Parathyroid adenoma is a benign condition causing hyperparathyroidism, usually resulting in elevated blood calcium levels, which is best treated by minimally invasive surgery. Imaging plays an important role in guiding surgery. Most commonly used now is the myocardial perfusion agent, 99mTc-sestamibi, which accumulates in both the thyroid and parathyroid glands but is only retained in the parathyroid glands. The mechanism of accumulation of 99mTc-sestamibi is not fully understood but is believed to be related to high mitochondrial activity. Two imaging approaches are taken. One uses early and late imaging (15 min and 2 h) following injection of 99mTc-sestamibi. Relative focal increase in the parathyroid glands (as the tracer washes out of the thyroid) is indicative of adenoma. An alternative approach uses a second, thyroid-specific tracer, such as 99mTc-pertechnetate or 123I-iodide, to allow subtraction of thyroid activity for better definition of the parathyroid glands. In either case, SPECT or SPECT/CT imaging is useful to provide the surgeon with a roadmap [29].
Endocrine system
Published in David A Lisle, Imaging for Students, 2012
Imaging is indicated in hyperparathyroidism to localize the causative lesion prior to surgery; this is relevant where minimally invasive surgery is intended. In centres where bilateral neck exploration is the standard procedure, preoperative imaging for localization of parathyroid adenoma is not always performed. Where preoperative localization is required, US is the investigation of first choice. US with high-resolution equipment has a high sensitivity (80–90 per cent) for the detection of parathyroid adenoma. US appearance of parathyroid adenoma is a well-defined hypoechoic mass usually of around 1.0–1.5 cm in diameter (Fig. 12.5). Most parathyroid adenomas lie behind or immediately below the thyroid gland. The principal cause of a false-negative US is ectopic adenoma, which may be present in up to 10 per cent of cases; ectopic sites include mediastinum and carotid sheath.
Recent advances in nuclear and hybrid detection modalities for image-guided surgery
Published in Expert Review of Medical Devices, 2019
Matthias N. Van Oosterom, Daphne D.D. Rietbergen, Mick M. Welling, Henk G. Van Der Poel, Tobias Maurer, Fijs W.B. Van Leeuwen
18F-FDG PET/CT navigation of a laparoscope was demonstrated during lymph node salvage surgery for breast cancer and recurrent lymphoma [174]. SPECT/CT navigation has been applied more often, with navigation of a γ probe during open surgery SN procedures using (ICG-)99mTc-nanocolloid (e.g. penile cancer, melanoma, breast cancer, thyroid cancer and prostate cancer [101,175–177]), the resection of neuroendocrine tumors using 123I-MIBG (e.g. paraganglioma [101]) and parathyroid adenoma using 99mTc-MIBI [178]. All intraoperative studies so far were based on the same underlying technology: an intraoperative navigation system with near-infrared optical tracking and optical tracking fiducials attached to both the patient and the navigated instruments (see Figure 3(e)). This tracking setup allowed for a registration between the preoperative PET- or SPECT-based patient maps and the intraoperative instruments. During surgery, this allowed for more accurate positioning of the surgical instruments (see Figure 3(f–g)). However, these studies also indicated that navigation to soft tissues based on preoperative images can suffer from inaccuracies due to tissue deformations. By navigating a γ probe or fluorescence camera, the real-time feedback provided could partially correct for such inaccuracies [175,176,179–181].