Molecular imaging of thyroid and parathyroid diseases.

INTRODUCTION: Molecular imaging of thyroid and parathyroid diseases has changed in recent years due to the introduction of new radiopharmaceuticals and new imaging techniques. Accordingly, we provided an clinicians-oriented overview of such techniques and their indications. AREAS COVERED: A review of the literature was performed in the PubMed, Web of Science, and Scopus without time or language restrictions through the use of one or more fitting search criteria and terms as well as through screening of references in relevant selected papers. Literature up to and including December 2023 was included. Screening of titles/abstracts and removal of duplicates was performed and the full texts of the remaining potentially relevant articles were retrieved and reviewed. EXPERT OPINION: Thyroid and parathyroid scintigraphy remains integral in patients with thyrotoxicosis, thyroid nodules, differentiated thyroid cancer and, respectively, hyperparathyroidism. In the last years positron-emission tomography with different tracers emerged as a more accurate alternative in evaluating indeterminate thyroid nodules [18F-fluorodeoxyglucose (FDG)], differentiated thyroid cancer [124I-iodide, 18F-tetrafluoroborate, 18F-FDG] and hyperparathyroidism [18F-fluorocholine]. Other PET tracers are useful in evaluating relapsing/advanced forms of medullary thyroid cancer (18F-FDOPA) and selecting patients with advanced follicular and medullary thyroid cancers for theranostic treatments (68Ga/177Ga-somatostatin analogues).

Update in imaging tests used for the localization of parathyroid pathology.

Preoperative localization of parathyroid pathology, generally a parathyroid adenoma, can be difficult in some cases due to the anatomical variants that these glands present. The objective of this review is to analyse the different imaging techniques used for preoperative localization of parathyroid pathology (scintigraphy, ultrasound, CT, MRI and PET). There is great variability between the different tests for the preoperative localization of parathyroid pathology. The importance of knowing the different diagnostic options lies in the need to choose the most suitable test at each moment and for each patient for an adequate management of primary hyperparathyroidism (PHP) with surgical criteria.

Imaging of Treated Thyroid and Parathyroid Disease.

The thyroid and parathyroid glands are endocrine structures located in the visceral space of the infrahyoid neck. Imaging plays a critical role in the evaluation of patients with thyroid cancer, both in the pre and posttreatment setting. Disorders of thyroid function, that is, hyperthyroidism and hypothyroidism, are also fairly common, although imaging utilization is less frequent with these conditions. Parathyroid dysfunction results in disordered calcium metabolism. Imaging is frequently applied in the preoperative assessment of these patients undergoing parathyroidectomy; however, routine imaging in the postoperative setting is uncommon. Parathyroid carcinoma is rare; however, imaging may be used in the pre and posttreatment setting.

Intraoperative near-infrared imaging of parathyroid glands: A comparison of first- and second-generation technologies.

BACKGROUND: Intraoperative near-infrared imaging (NIFI) of parathyroid glands (PG) by first-generation technology had limited image quality and depth penetration. Second-generation NIFI has recently been introduced. Our aim was to compare (1) capability to detect PG and (2) image quality between older and newer technologies. METHODS: Accurately detecting PG, as well as, quality of autofluorescence (AF) was compared between an older charge-coupled device (CCD) camera and a newer complementary metal-oxide semiconductor (CMOS). χ2 , t test, and analysis of variance were used for analysis. RESULTS: There were 300 patients who underwent parathyroidectomy (PTX) and/or thyroidectomy (THY) with NIFI, 200 with CCD, and 100 with CMOS. Although both NIFI technologies detected >94% of PG, CMOS was superior to CCD. Comparing AF quality, mean pixel intensity of PG compared with the background was higher with CMOS compared with CCD. When comparing PG detected by NIFI before visual identification by a surgeon, both CCD and CMOS had similar results (25% vs. 22%; p = .3). CONCLUSION: Both NIFI cameras were excellent at detecting PG. Second-generation NIFI (CMOS) displayed higher detection rates and AF intensity. Although surgeons identified majority of PG before NIFI detection, 25% of PG were identified with NIFI first, suggesting future advancements of this technology may expand its applications during parathyroid/thyroid operations.

Parathyroid 4D CT: What the Surgeon Wants to Know.

Parathyroid four-dimensional (4D) CT is an increasingly used and powerful tool for preoperative localization of abnormal parathyroid tissue in the setting of primary hyperparathyroidism. Accurate and precise localization of a single adenoma facilitates minimally invasive parathyroidectomy, and localization of multiglandular disease aids bilateral neck exploration. However, many radiologists find the interpretation of these examinations to be an intimidating challenge. The authors review parathyroid 4D CT findings of typical and atypical parathyroid lesions and provide illustrative examples. Relevant anatomy, embryology, and operative considerations with which the radiologist should be familiar to provide clinically useful image interpretations are also discussed. The most important 4D CT information to the surgeon includes the number, size, and specific location of candidate parathyroid lesions with respect to relevant surgical landmarks; the radiologist's opinion and confidence level regarding what each candidate lesion represents; and the presence or absence of ectopic or supernumerary parathyroid tissue, concurrent thyroid pathologic conditions, and arterial anomalies associated with a nonrecurrent laryngeal nerve. The authors provide the radiologist with an accessible and practical approach to performing and interpreting parathyroid 4D CT images, detail what the surgeon really wants to know from the radiologist and why, and provide an accompanying structured report outlining the key information to be addressed. By accurately reporting and concisely addressing the key information the surgeon desires from a parathyroid 4D CT examination, the radiologist substantially impacts patient care by enabling the surgeon to develop and execute the best possible operative plan for each patient. ©RSNA, 2020.

Role of ultrasound in the differentiation of parathyroid carcinoma and benign parathyroid lesions.

AIM: To identify the differences between ultrasound (US) features of parathyroid carcinoma (PC) and benign parathyroid (BP) lesions in patients with primary hyperparathyroidism (PHPT). MATERIAL AND METHODS: Twenty-one patients with PC and 64 consecutive patients with BP, whose diagnoses were confirmed at surgery, were enrolled from January 2013 to December 2018. The US features, demographic, clinical, and biochemical characteristics of the two groups were compared retrospectively. RESULTS: There are no significant differences between the patients with PC and BP regarding mean age or mean ionized calcium levels but differences were seen in sex distribution and mean parathyroid hormone (PTH) levels. On US imaging, PC significantly exhibited higher incidences of larger size and higher depth/width (D/W) ratio, heterogeneous echotexture, irregular shape, non-circumscribed margin, intra-nodular calcifications, indistinct border, cystic change, and the presence of suspicious lymph nodes compared to BP lesions. CONCLUSION: Preoperative ultrasonography is helpful to differentiate PC and BP. Patients with PC are differentiated from BP by their sex distribution, mean PTH levels, and major US characteristics: larger size, higher D/W ratio, heterogeneous echotexture, irregular shape, non-circumscribed margin, indistinct border, intra-nodular calcifications, cystic change, and the presence of suspicious lymph nodes.

Ultrasonographic size of the canine parathyroid gland may not correlate with histopathology.

Accurate ultrasonographic differentiation of normal versus abnormal parathyroid glands is important for clinical workup and presurgical screening in dogs with hypercalcemia. In previous published studies, size has been the only ultrasonographic criterion correlated with histologic diagnoses of abnormal parathyroid glands. In this retrospective, cross-sectional study, the medical records of dogs with ultrasonographic examinations of the parathyroid glands and histologic diagnoses of parathyroid gland hyperplasia, adenoma, and adenocarcinoma were evaluated. Ultrasonographic characteristics were recorded for each gland and compared among histologic diagnosis groups. A total of 49 dogs and 59 parathyroid glands were sampled and assigned to the following groups for analyses: adenoma (n = 24), hyperplastic (n = 20), and adenocarcinoma (n = 15). There were no associations with dog age, sex, weight, breed; or gland laterality, location, ultrasonographic shape, or echogenicity among histologic diagnosis groups (P > .05). Parathyroid gland adenocarcinomas were found to be less likely to have a homogeneous echotexture on ultrasonographic evaluation, with hyperplastic glands being smaller (P = .022) and adenocarcinomas being larger (P = .042). While 3 mm was the optimum cutoff for differentiating hyperplastic and neoplastic parathyroid glands in this sample of dogs, values varied widely within groups and there were overlapping values between groups. Therefore, authors caution against using ultrasonographic size as a sole criterion for differentiating hyperplasia from neoplasia and normal versus abnormal parathyroid glands.

Enhancing Parathyroid Gland Visualization Using a Near Infrared Fluorescence-Based Overlay Imaging System.

BACKGROUND: Misidentifying parathyroid glands (PGs) during thyroidectomies or parathyroidectomies could significantly increase postoperative morbidity. Imaging systems based on near infrared autofluorescence (NIRAF) detection can localize PGs with high accuracy. These devices, however, depict NIRAF images on remote display monitors, where images lack spatial context and comparability with actual surgical field of view. In this study, we designed an overlay tissue imaging system (OTIS) that detects tissue NIRAF and back-projects the collected signal as a visible image directly onto the surgical field of view instead of a display monitor, and tested its ability for enhancing parathyroid visualization. STUDY DESIGN: The OTIS was first calibrated with a fluorescent ink grid and initially tested with parathyroid, thyroid, and lymph node tissues ex vivo. For in vivo measurements, the surgeon's opinion on tissue of interest was first ascertained. After the surgeon looked away, the OTIS back-projected visible green light directly onto the tissue of interest, only if the device detected relatively high NIRAF as observed in PGs. System accuracy was determined by correlating NIRAF projection with surgeon's visual confirmation for in situ PGs or histopathology report for excised PGs. RESULTS: The OTIS yielded 100% accuracy when tested ex vivo with parathyroid, thyroid, and lymph node specimens. Subsequently, the device was evaluated in 30 patients who underwent thyroidectomy and/or parathyroidectomy. Ninety-seven percent of exposed tissue of interest was visualized correctly as PGs by the OTIS, without requiring display monitors or contrast agents. CONCLUSIONS: Although OTIS holds novel potential for enhancing label-free parathyroid visualization directly within the surgical field of view, additional device optimization is required for eventual clinical use.

MRI findings and utility of DWI in the evaluation of solid parathyroid lesions.

PURPOSE: To evaluate the MRI findings of solid parathyroid lesions and to elaborate on a possible improvement of MRI detection of parathyroid lesions by the use of additional DWI. MATERIALS AND METHODS: MRI and DWI properties of pathologically proven 20 solid parathyroid lesions were retrospectively reviewed. Mean ADC values (b50 + b400 + b800/3) of parathyroid lesions were compared with that of normal appearing thyroid parenchyma (TP), sternocleidomastoid muscle (SCM) and jugulodigastric lymph nodes (JDLN). RESULTS: Of lesions, 4 were parathyroid hyperplasia, 13 parathyroid adenoma and 3 parathyroid adenocarcinoma. All parathyroid lesions were very bright on fat-saturated T2W images. Parathyroid hyperplasia and adenoma were small sized, homogenous, well-defined and low on T1W, high on T2W and avidly enhancing. Parathyroid carcinoma was large sized, ill-defined and very heterogeneous on MRI including DWI. Means ADC values of parathyroid hyperplasia, adenoma, and adenocarcinoma, TP, SCM and JDLN were measured as 2.3 ± 0.14 × 10-3, 1.7 ± 0.45 × 10-3, 1.5 ± 1.48 × 10-3, 0.87 ± 0.40 × 10-3, 0.55 ± 0.21 × 10-3 and 0.96 ± 0.33 × 10-3 mm2/s, respectively. All parathyroid lesions had high diffusion properties comparing other soft tissue structures of head and neck region. By increasing strength (b value) of diffusion tensor on DWI, solid parathyroid lesions still kept their brightness comparing other soft tissue structures of head and neck region because of their high T2 properties. CONCLUSION: Solid parathyroid lesions had higher diffusion properties comparing other soft tissues structures of head and neck region. This feature makes them easily differentiate from nearby structures on fat-saturated T2W and DWI.

Mediastinal Remnant Thymic Tissue Misdiagnosed as Ectopic Parathyroid Hyperplasia in Secondary Hyperparathyroidism.

A 56-year-old woman with secondary hyperparathyroidism was referred for preoperative localization of hyperfunctioning parathyroid lesions. Tc-MIBI dual-phase and SPECT/CT parathyroid scan showed multiple focal activities behind the thyroid and in the anterior mediastinum, diagnosed as parathyroid hyperplasia. However, the histopathological findings proved them to be hyperplastic parathyroid glands and remnant thymic tissue after parathyroidectomy and unnecessary thoracotomy, respectively.

Are preoperative sestamibi scans useful for identifying ectopic parathyroid glands in patients with expected multigland parathyroid disease?

BACKGROUND: The role of preoperative localization studies in patients with hyperparathyroidism and expected multigland disease remains poorly defined. Our study investigates the usefulness of obtaining preoperative sestamibi scans and ultrasonography of the neck in identifying ectopic glands in this group of patients. METHODS: Under Institutional Review Board approval, we performed a retrospective review of patients who underwent operation for secondary hyperparathyroidism, tertiary hyperparathyroidism, lithium-induced hyperparathyroidism, and multiple endocrine neoplasia syndrome at a tertiary institution between 2004 and 2015. We reviewed patient demographics, laboratory, radiology, pathology, and operative reports. RESULTS: Of 2,975 parathyroidectomies performed during this period, 154 operations were performed in 149 patients who met the criteria. Of the 149 patients, 82 (55.0%) had secondary, 31 (20.8%) had tertiary, 23 (15.4%) had lithium-induced HPT, and 13 (10.1%) had multiple endocrine neoplasia syndrome; 86 ectopic glands were identified in 64 patients (43.0%). Sensitivity for identification of ectopic glands was 29% for sestamibi scan and 7% for ultrasonography, while 89% of mediastinal glands were localized by sestamibi scans and thoracotomy, thoracoscopy, or sternotomy occurred in 4.7% of patients. CONCLUSION: We found a greater rate of preoperative localization of ectopic glands than reported previously. Because the sensitivity of sestamibi for identification of ectopic glands is 23.0%, the implication of missing mediastinal glands warrants preoperative imaging.

The diagnostic value of shear wave elastography for parathyroid lesions and comparison with cervical lymph nodes.

AIMS: The aim of this study was to prospectively assess the feasibility of the Virtual Touch tissue imaging quantification (VTIQ) method of shear wave elastography (SWE) for the discrimination of parathyroid lesions and to compare the lesions' stiffness with that of cervical lymph nodes. MATERIALS AND METHODS: SWE using VTIQ was performed on 66 patients with 87 histopathologically proven parathyroid lesions (54 parathyroid adenomas and 33 parathyroid hyperplasia) and 29 patients with 31 inflammatory cervical lymph nodes. The mean SWVs of the lesions were compared and receiver operating characteristic (ROC) curve analysis was used to evaluate diagnostic performance. RESULTS: The mean SWV of parathyroid adenomas (2.16±0.33 m/s) differed significantly from those of parathyroid hyperplasia and lymph nodes (1.75±0.28 m/s and 1.86±0.37 m/s respectively, p<0.001). Selecting a cutoff value of 1.92 m/s for diagnosing adenoma led to 80% sensitivity and 82% specificity (area under the curve [AUC]: 0.832 [95% confidence interval (CI): 0.742-0.921], p< 0.001). CONCLUSIONS: The VTIQ method of SWE can contribute to the differentiation of parathyroid adenoma from parathyroid hyperplasia and cervical lymphnodes.

Intraoperative Identification of the Parathyroid Gland with a Fluorescence Detection System.

BACKGROUND: Intraoperative identification of the difficult-to-spot parathyroid gland is critical during surgery for thyroid and parathyroid disease. Recently, intrinsic fluorescence of the parathyroid gland was identified, and a new method was developed for intraoperative detection of the parathyroid with an original fluorescent detection apparatus. Here, we describe a method for intraoperative detection of the parathyroid using a ready-made photodynamic eye (PDE) system without any fluorescent dye or contrast agents. METHODS: Seventeen patients who underwent surgical treatment for thyroid or parathyroid disease at Kagoshima University Hospital were enrolled in this study. Intrinsic fluorescence of various tissues was detected with the PDE system. Intraoperative in vivo and ex vivo intrinsic fluorescence of the parathyroid, thyroid, lymph nodes and fat tissues was measured and analyzed. RESULTS: The parathyroid gland had a significantly higher fluorescence intensity than the other tissues, including the thyroid glands, lymph nodes and fat tissues, and we could identify them during surgery using the fluorescence-guided method. Our method could be applicable for two intraoperative clinical procedures: ex vivo tissue identification of parathyroid tissue and in vivo identification of the location of the parathyroid gland, including ectopic glands. CONCLUSION: The PDE system may be an easy and highly feasible method to identify the parathyroid gland during surgery.

Robotic resection of a mediastinal parathyroid cyst.

Mediastinal parathyroid cysts (PC) are rare, benign lesions, reported in fewer than 150 cases worldwide. Although most are asymptomatic and discovered incidentally on imaging, symptoms of dyspnea, dysphagia, hoarseness, palpitations, hypercalcemia, and innominate or jugular venous thrombosis have been reported. Sternotomy or thoracotomy has traditionally been the approach used to resect mediastinal PCs. We describe the first reported case of a robot-assisted resection of a mediastinal PC.

[The evaluation and surgical treatment of mass in the pretracheal space].

OBJECTIVE: To study the pathological and clinical features and the surgical results of the mass in the pretracheal space. METHODS: From 1999 to 2004, 8 females and 3 males with an average of 43 years (from 32 to 61 years) were included CT scan, nuclear imaging, ultrasound and ultrasound-guided aspiration, endoscopic and laboratory measure were used in the evaluation for the masses before operation. Complete removal of mass was carried out in all patients under general anesthesia, and continuous negative pressure draining was routinely used. RESULTS: Six masses with firm consistency could be moved easily transversely, but slightly moveable with swallowing. On contrast CT or ultrasound, all the masses had clear circumscription and showed rounded or lobular shape. No hemorrhage, chylous or lymph leakage, or recurrent laryngeal injury was encountered. Goiter was found in 6 cases, parathyroid adenoma in 2 cases, and thymoma, parathyroid cyst or lymphatic cyst was diagnosed in the rest three patients respectively. No recurrence was found with the following-up of 7 - 42 months. CONCLUSIONS: Goiter, parathyroid adenoma and thymoma were common lesions presenting as mass in the pretracheal space and surgically curable without complications.