Parathyroid Imaging Clinical Practice Guidelines (EANM, 2021)

Clinical guidelines on parathyroid imaging were published in April 2021 by the European Association of Nuclear Medicine (EANM) in the European Journal of Nuclear Medicine and Molecular Imaging.^[1]

Imaging during breastfeeding

It is recommended that in the case of breastfeeding women, clinicians consult International Commission on Radiological Protection (ICRP) Publication 128: Radiation Dose to Patients from Radiopharmaceuticals: A Compendium of Current Information Related to Frequently Used Substances.

SPECT scanning and scintigraphy

When combining single-photon emission computed tomography (SPECT) scanning with CT imaging, use the lowest CT dose that can successfully be employed.

If a rapid parathyroid washout should occur with [^99mTc]Tc-hexakis-(2-methoxy-2-isobutyl isonitrile) ([^99mTc]Tc-MIBI), commonly used in parathyroid scintigraphy, then carrying out additional scintigraphy between acquisition of the standard early and late-phase images is reasonable. Dynamic imaging, however, may be used as an alternative. Should a slow washout occur, subtraction imaging may prove beneficial.

With SPECT/CT scanning that employs [^99mTc]Tc-MIBI being superior to planar or stand-alone SPECT imaging studies and with dual-phase acquisition demonstrating greater accuracy than single-phase acquisition, at least one SPECT/CT imaging study should be performed encompassing the region between the skull base and the heart base.

PET scanning

With its higher resolution, positron emission tomography (PET)/CT scanning could better detect the smallest pathologic glands, those that escape visualization with SPECT/CT scanning. Utilization of the scanner with the highest system sensitivity and with reconstruction protocols optimized for small lesion detection (block sequential regularized expectation maximization [BSREM] instead of ordered subset expectation maximization [OSEM]) is recommended. In combining PET and CT scanning, be sure to use the lowest CT dose that can successfully be employed.

In case of thyroid anomalies, PET/CT scans should be analyzed with reference to thyroid scintigraphy (with Na[¹²³I]I if available). This will demonstrate how well the PET/CT-scan foci correspond to the location and iodine metabolism of thyroid nodules.

Cervical ultrasonography

Acquire cross-sectional and longitudinal scans of the anterior neck region, between the common carotid arteries, with the images encompassing the region between the carotid bifurcation and the superior mediastinum. Particular attention should be paid to the posterior surface of the thyroid and the area below it.

For various reasons, such as its reduced sensitivity in detecting small glands or multiglandular disease, as well as its operator dependence, cervical ultrasonography (cUS) should be combined with parathyroid scintigraphy.

Fine-needle aspiration

For various reasons, including possible complications and increased surgery time, fine-needle aspiration (FNA) cytology should be used only in highly selected cases, such as those involving atypical cUS findings or inconclusive scintigraphy.

FNA is not a recommended means of detecting parathyroid carcinoma, owing to the inaccuracy of cytology in distinguishing malignant from benign lesions and because of the risk that cancer cells will be seeded.

For more information, please go to Parathyroid Carcinoma.

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Cite this: Parathyroid Imaging Clinical Practice Guidelines (EANM, 2021) - Medscape - Apr 29, 2021.