Accuracy of Neck Ultrasonography in Predicting the Size and Location of Parathyroid Adenomas

Retrospective analysis of the role of intra-operative parathyroid hormone monitoring during parathyroidectomy for primary hyperparathyroidism: a single center experience over 2 decades

PURPOSE

Role of intra-operative parathyroid hormone (IOPTH) monitoring during parathyroidectomy for primary hyperparathyroidism (PHPT) has long been debated. Our main goal was to investigate the cure rates of parathyroidectomy for primary hyperparathyroidism with and without IOPTH monitoring. Our secondary goal was to investigate if operating room time can be saved when IOPTH monitoring is not used.

METHODS

A retrospective analysis of patients who underwent parathyroidectomy for PHPT due to a single adenoma between 2004 and 2019 was performed. Cure rates and operating room time were compared.

RESULTS

423 patients were included. IOPTH was used in 248 patients (59%). Four patients were not cured, two from each group, with no significant difference between the groups (98.8% vs. 99.1%, p = 0.725). Surgery time was significantly longer in the IOPTH group, p < 0.001.

CONCLUSIONS

There is no advantage for using IOPTH during parathyroidectomy in suitable clinical settings. The procedure may be safely performed without IOPTH while achieving non-inferior success rates and reducing operative time.

ACR Appropriateness Criteria® Parathyroid Adenoma

Hyperparathyroidism is defined as excessive parathyroid hormone production. The diagnosis is made through biochemical testing, in which imaging has no role. However, imaging is appropriate for preoperative parathyroid gland localization with the intent of surgical cure. Imaging is particularly useful in the setting of primary hyperparathyroidism whereby accurate localization of a single parathyroid adenoma can facilitate minimally invasive parathyroidectomy. Imaging can also be useful to localize ectopic or supernumerary parathyroid glands and detail anatomy, which may impact surgery. This document summarizes the literature and provides imaging recommendations for hyperparathyroidism including primary hyperparathyroidism, recurrent or persistent primary hyperparathyroidism after parathyroid surgery, secondary hyperparathyroidism, and tertiary hyperparathyroidism. Recommendations include ultrasound, CT neck without and with contrast, and nuclear medicine parathyroid scans. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Improving the detectability of overactive glands in dual-phase parathyroid SPECT/CT: a Monte Carlo simulation study

Objective. SPECT-CT is a standard procedure conducted before minimally invasive surgery for the treatment of primary hyperthyroidism. In order to improve image quality, it is important to know how defect detectability is influenced by acquisition and processing parameters. The objective of this study is to continue prior physical phantom optimization studies by performing Monte Carlo simulations for the dual phase parathyroid SPECT-CT protocol using a digital anthropomorphic phantom.Methods. The dual phase parathyroid SPECT-CT imaging procedure with 99mTc-Sestamibi was simulated using the previously extensively validated SIMIND software for the first time. An anthropomorphic ZUBAL based phantom was built to represent an adenoma. Its diameter was set to 0.76 cm which corresponded to more than three times the pixel size and the target-to-background ratio was set to 16:1 based on previous studies. Four different collimators were tested. Contrast-to-noise (CNR) values were determined for different scatter correction options and processing parameter values. The OSEM algorithm was used for image reconstruction.Results. CNR values were improved from about zero (LEGP collimator, 16 iterations, attenuation correction: on, scatter correction: off) up to 3.7 (LEUHR collimator, 16 iterations, attenuation correction: on, scatter correction: off). The subjective visual assessment of detectability on simulated images agreed with the quantitative CNR values.Conclusion. Higher resolution collimators gave better CNR as confirmed by similar studies. The effect of scatter correction was found beneficial only if both the resolution and sensitivity of the collimator were relatively high. This is a significant finding since there is a shortage of definitive guideline on the use of scatter correction for parathyroid SPECT imaging.

Application of carbon nanoparticles in localization of parathyroid glands during total parathyroidectomy for secondary hyperparathyroidism

BACKGROUND

Intraoperative imaging is used to address the challenges of parathyroidectomy, but no standard modality has been established. This study aimed to assess whether carbon nanoparticle injection is useful in localizing parathyroid glands (PGs) during parathyroidectomy.

METHODS

Patients who underwent total parathyroidectomy (TPTX) between September 2015 and November 2018 were included. The operative duration and intact parathyroid hormones (iPTH) were analyzed.

RESULTS

A total of 61 patients were included; of these, 32 with carbon nanoparticle injection (TPTX + CN group) and 29 without (TPTX group). The operative duration in the TPTX + CN group was significantly shorter (90.6 ± 21.2 vs 101.4 ± 19.4 min, P = 0.042), which is more apparent in those with normal sized PGs. For those with four enlarged PGs, iPTH levels on 1 day and 1 year postoperatively were significantly lower in the TPTX + CN group (P = 0.032 and P = 0.036, respectively).

CONCLUSION

Carbon nanoparticles are useful in the identification normal sized PGs and complete resection of enlarged PGs.

Update of the role of Nuclear Medicine techniques in the pre-surgical localization of primary hyperparathyroidism

Primary hyperparathyroidism is one of the most frequent endocrine disorders. Its diagnosis is biochemical. Imaging techniques are not useful for the diagnosis of this pathology; they are just tools for pre-surgical localization. In this continuing education, we will analyze the different imaging modalities used in this indication, focusing on Nuclear Medicine. The most commonly used imaging technique in this context is the parathyroid scintigraphy, nowadays double phase protocol with ^99mTc-MIBI and the double tracer with ^99mTc-MIBI/^99mTc-pertechnetate, associated in the first case to SPECT or SPECT/CT, in an early or late phase. The PET/CT with different tracers is showing good results, especially applied to cases of failure in the pre-surgical scintigraphic localization. We expose the results of the morphological imaging techniques as well as the usefulness of combining techniques.

Feasibility of Hyperfunctioning Parathyroid Gland Localization Using [18F]fluciclovine PET/CT

PURPOSE

To evaluate the ability of anti-1-amino-3-anti-1-amino-3-[¹⁸F]fluorocyclobutane-1-carboxylic acid ([¹⁸F]fluciclovine) positron emission tomography/X-ray computed tomography (PET/CT) in comparison to Technetium-99m 2-methoxy isobutyl isonitrile ([^99mTc]sestamibi) single-photon emission computed tomography/CT (SPECT/CT) for the localization of hyperfunctioning parathyroid glands in patients with hyperparathyroidism.

PROCEDURES

Four patients with hyperparathyroidism underwent 60-minutes sequential neck and thorax PET/CT after [¹⁸F]fluciclovine (352 ± 28 MBq) injection. Lesion uptake and target-to-background ratios (TBR) were compared with [^99mTc]sestamibi (798 ± 27 MBq) SPECT/CT in the same patient.

RESULTS

Both techniques detected 4/5 hyperfunctioning parathyroid glands identified at surgery. The highest [¹⁸F]fluciclovine uptake and TBRs were at 5-9 min with rapid washout. [^99mTc]sestamibi had significantly higher TBRs compared with [¹⁸F]fluciclovine (5-9 min) for blood pool (10.9 ± 4.7 vs 1.3 ± 0.6; p < 0.01) and reference muscle backgrounds (5.8 ± 3.0 vs 1.7 ± 0.6; p < 0.01), with non-significant trend for thyroid tissue background (1.3 ± 0.5 vs 1.1 ± 0.5; p = 0.73).

CONCLUSION

Hyperfunctioning parathyroid glands can be detected on [¹⁸F]fluciclovine PET/CT at early imaging, but conspicuity (TBR) is better with [^99mTc]sestamibi. [¹⁸F]fluciclovine PET/CT does not seem promising in the detection of hyperfunctioning parathyroid glands.