Hyperparathyroidism is a condition caused by increased secretion of the parathyroid hormone, which plays an important role in calcium homeostasis. This condition has been diagnosed more frequently recently and can affect multiple organ systems resulting in a variety of signs and symptoms. Hyperparathyroidism can be classified as primary, secondary, or tertiary disease and can result from eutopic or ectopic parathyroid lesions. Parathyroid adenoma is the most common cause of primary hyperparathyroidism, accounting for more than 80% of cases. Parathyroid hyperplasia is the cause in about 20% of patients, while parathyroid carcinoma is rare and accounts for less than 1% of cases. Surgical removal of the abnormal gland(s) is the definite treatment for hyperparathyroidism. Bilateral neck exploration is the classical approach for parathyroidectomy. In recent years, minimally invasive parathyroidectomy is becoming more popular due to the fewer complications and shorter hospital stay. This new approach has placed a greater emphasis on the preoperative localization techniques. Multiple localization techniques have been used, including invasive techniques, anatomical, and scintigraphic imaging modalities. Thallium/pertechnetate subtraction method was introduced in 1980 and was the first method to gain widespread acceptance. It is not widely used now due to the suboptimal characteristics of thallium and the technical difficulties associated with subtraction and registration. The dual-phase method using Tc-99m sestamibi is currently the method of choice for parathyroid localization. It is based on the differential washout rate of sestamibi from the thyroid and abnormal parathyroid glands. The reported sensitivity of this method ranges from 80% to 90%. The addition of single-photon emission computed tomography (SPECT) and more recently SPECT/CT improves the anatomical localization and helps in the differentiation of the parathyroid from the thyroid lesions. Multiple factors can affect the sensitivity of the scan including the lesion size, cellularity, and the presence of P-glycoprotein. Modification of the imaging protocol may help to avoid false positive or false negative results in certain cases. Positron emission tomography has been recently investigated for possible role in parathyroid imaging and showed promising results with 11 C-methionine.

Thyroid scintigraphy plays an important role in the anatomical and functional evaluation of thyroid nodules which carry the risk of malignancy. The presence of multiple nodules carries overall smaller risk of cancer than solitary nodule. Missing nodules, whether solitary or multiple, may mean delaying detection of possible cancer. Therefore, it is important to improve the delectability of thyroid scintigraphy using most optimal imaging techniques. For pinhole thyroid imaging, there is a recent trend to omit oblique projections by some laboratories. The objective of this study was to reevaluate the impact of oblique projections in the detection of thyroid nodules. A total of 92 cases with nodular thyroid disease on routine pinhole thyroid scintigraphy was reviewed retrospectively. Two nuclear medicine physicians recorded the number of nodules based on the anterior view only and another time with adding the oblique views. A total of 192 nodules was detected using the three views. Sixty nodules (31%) were only seen on the oblique views and were missed on the anterior projections. Oblique pinhole projections are mandatory for adequate thyroid scintigraphy since 31% of nodules are missed if only anterior projection was used for interpretation. Following proper techniques will avoid missing of detection of nodule that may harbor cancer.

The aim of this study is to investigate the relationship between brown adipose tissue (BAT) activation and myocardial fluorine-18-fluorodeoxyglucose ([18F] FDG) uptake in terms of intensity and patterns. The patients were divided into two groups as follows: BAT and control groups. The BAT group consists of 34 cases that showed BAT uptake. The control group, with no BAT uptake, included 68 patients who were matched for body mass index, gender, and season. The scans were retrospectively reviewed by two nuclear medicine physicians who visually evaluated the intensity of myocardial [18F] FDG uptake. The myocardial [18F] FDG uptake was visually classified into the following three patterns: diffuse, heterogeneous, and focal. The regions of activated BAT distribution were noted. The mean myocardial [18F] FDG uptake was 2.50 ± 0.75 for the BAT group and 2.13 ± 0.88 for the control group with a statistically significant difference (P = 0.031). The myocardial [18F] FDG uptake pattern was similar in the BAT and control groups with the diffuse pattern being the most common, followed by the heterogeneous and less commonly focal. In the BAT group, the anatomical distribution of BAT was mainly in supraclavicular, paravertebral, and axillary and to a lesser extent in cervical regions. BAT group had a significantly higher intensity of [18F] FDG myocardial uptake compared to that of the control group. The presence of activated BAT did not affect the pattern of myocardial uptake. Knowledge of these findings may help in understanding the variability of myocardial [18F] FDG uptake and consequently in avoiding misinterpretation of cardiac findings in positron-emission tomography/computed tomography studies.