Scintigraphic techniques in primary hyperparathyroidism: from pre-operative localisation to intra-operative imaging

The added value of non-contrast 3-Tesla MRI for the pre-operative localization of hyperparathyroidism

OBJECTIVE

We investigated the efficacy of non-contrast 3-Tesla MR imaging added to the combination of sestamibi with^99mTc (MIBI) scintigraphy and Ultrasonography (US) for the pre-operative localization of Primary Hyperparathyroidism (PHPT) lesions.

METHODS

A total of 34 parathyroid glands, including nine normal glands, were examined with MIBI, US, and non-contrast 3-Tesla MRI. MRI was performed with the acquisition of T1- and T2-weighted images and fat-suppressed T2-weighted images. We calculated the sensitivities of MIBI, US, and the 'additional' MRI, with knowledge of the former two modalities' results.

RESULTS

For the diagnosis of PHPT lesions, the sensitivity values of MIBI, US, and additional MRI were 88.0% (22/25), 84.0% (21/25), and 92.0% (23/25), respectively. Normal glands were not visualized with any modality (0/9). One lesion was detected neither with US nor MRI, but only with MIBI, with the limitation that MIBI represented no more than laterality. The two glands not identified in MRI were 4 mm and 6 mm in their size, which are within the range of normal gland's size. Two lesions were not detected with US or MIBI but were visualized with the additional MRI, which indicated that the MRI contributed an 8.0% (2/25) improvement of sensitivity, compared from that of US. Fat-suppressed T2-weighted images were useful in the identification of parathyroid lesions, as these images helped to differentiate between the lesion and the adjacent tissue.

CONCLUSION

Additional non-contrast 3-Tesla MRI was a useful adjunctive tool for localization of PHPT, which improved the sensitivity of the pre-operative localization of PHPT lesions. Fat-suppressed T2-weighted images contributed to their identification.

LEVEL VI

Evidence from a single descriptive or qualitative study.

Multiglandular Parathyroid Disease

Introduction: Multiglandular parathyroid disease (MGD) is an uncommon cause of primary hyperparathyroidism (pHPT) and has been reported in the literature in 8–33% of patients with pHPT. The aim of our study was to review the clinical characteristics and management of MGD and evaluation of surgical treatment failures. Methods: We performed a retrospective study of 163 patients with pHPT undergoing parathyroidectomy (PTX) at the Department of General and Endocrine Surgery between 1983 and 2018. All these patients were diagnosed with MGD. This group of patients was compared with a group of 856 patients with solitary disease operated for pHPT in the same period. Results: Among 163 patients—127 (79%) of them had two lesions, 28 (16%) had three, and 8 (5%) four. They were prevalently women over the age of 50. The diagnosis was based on PTH and ionized calcium studies and used sestamibi technetium-99m scintigraphy (MIBI) as well for us. Treatment was surgical. Conclusions: Parathyroidectomy (PTX) for multiglandular parathyroid disease (MGD) is associated with a higher operative risk of failure compared to solitary disease. Preoperative diagnosis and localization of the parathyroid glands is an extremely important element of treatment. Diagnosis is based on PTH and calcium levels. Ultrasonography (USG), MRI, and scintigraphy are very helpful in diagnosis. Mediastinal multiglandular parathyroid disease (MGD) is associated with increased surgical treatment failures. The treatment is surgical and consists of the removal of the masses or complete parathyroidectomy. Based on this study, we support the existence of multiple adenomas and advocate the removal of only macroscopically enlarged parathyroid glands in patients with primary hyperparathyroidism.

Detecting Synchronous Thyroid Adenoma and False-Positive Findings on Technetium-99m MIBI Single Photon-Emission Computed Tomography/Computed Tomography

Technetium (Tc)-99m-methoxyisobutylisonitrile (MIBI) single photon-emission computed tomography/computed tomography (SPECT/CT) is now being used increasingly for preoperative localization of parathyroid adenomas. Tc-99m-MIBI scintigraphy in a 52-year-old man with a diagnosis of primary hyperparathyroidism revealed two focal areas with retention of radioactivity in the left lobe of the thyroid gland on the delayed phase of MIBI SPECT/CT but no significant focal radioactive uptake on MIBI planar images. The patient subsequently underwent left partial parathyroidectomy. Histological analysis identified one lesion to be thyroid hyperplasia and the other to be parathyroid adenoma. This case demonstrates the value of MIBI SPECT/CT for localization of a parathyroid lesion when compared with planar images and that false-positive findings can lead to misdiagnosis in a patient with coexisting thyroid disease. An appropriate diagnostic work-up that includes Tc-99m MIBI SPECT/CT in addition to ultrasonography is helpful for an accurate diagnosis in patients with concomitant thyroid disease.

Sporadic multiple parathyroid gland disease--a consensus report of the European Society of Endocrine Surgeons (ESES)

BACKGROUND

Sporadic multiglandular disease (MGD) has been reported in literature in 8-33 % of patients with primary hyperparathyroidism (pHPT). This paper aimed to review controversies in the pathogenesis and management of sporadic MGD.

METHODS

A literature search and review was made to evaluate the level of evidence concerning diagnosis and management of sporadic MGD according to criteria proposed by Sackett, with recommendation grading by Heinrich et al. and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system. Results were discussed at the 6th Workshop of the European Society of Endocrine Surgeons entitled 'Hyperparathyroidism due to multiple gland disease: An evidence-based perspective'.

RESULTS

Literature reports no prospective randomised studies; thus, a relatively low level of evidence was achieved. Appropriate surgical therapy of sporadic MGD should consist of a bilateral approach in most patients. Unilateral neck exploration guided by preoperative imaging should be reserved for selected patients, performed by an experienced endocrine surgeon and monitored by intraoperative parathormone assay (levels of evidence III-V, grade C recommendation). There is conflicting or equally weighted levels IV-V evidence supporting that cure rates can be similar or worse for sporadic MGD than for single adenomas (no recommendation). Best outcomes can be expected if surgery is performed by an experienced parathyroid surgeon working in a high-volume centre (grade C recommendation). Levels IV-V evidence supports that recurrent/persistence pHPT occurs more frequently in patients with double adenomas hence in situations where a double adenoma has been identified, the surgeon should have a high index of suspicion during surgery and postoperatively for the possibility of a four-gland disease (grade C recommendation).

CONCLUSIONS

Identifying preoperatively patients at risk for MGD remains challenging, intraoperative decisions are important for achieving acceptable cure rates and long-term follow-up is mandatory in such patients.

Use of (99m)Tc 2-methoxyisobutyl isonitrile in minimally invasive radioguided surgery in patients with primary hyperparathyroidism: A narrative review of the current literature

The use of technetium-99m 2-methoxyisobutyl isonitrile (^99mTc MIBI) for assistance in minimally invasive radioguided surgery (MIRS) is growing in popularity as a safe, effective, and proficient technique used for parathyroidectomy in primary hyperparathyroidism (PHPT) treatment. Previously, the preferred treatment for PHPT was bilateral neck exploration (BNE), a very invasive, costly, and lengthy procedure. However, as a large majority (80–85% of cases of PHPT) are attributed to a single parathyroid adenoma (PA), a simpler more direct technique such as MIRS is a far better option. The following article is an exploration of the current literature concerning varied protocols utilizing ^99mTc MIBI for assistance in MIRS for patients undergoing treatment of PHPT. This technique boasts many advantageous outcomes for patients suffering from PHPT. These include a reduction in cost, operating time, and patient recovery; less evidence of post-surgical hypocalcaemia, less pain, and complications; superior cosmetic results; same-day discharge; and the possibility of local anaesthesia which is particularly beneficial in elderly patients. Better outcomes for patients with deep or ectopic PAs, reduced intra-operative complications, and improved cosmetic outcomes for patients who have previously undergone thyroid and/or parathyroid surgery are also advantageous. Of the literature reviewed it was also found that no patients suffered any major surgical complications such as laryngeal nerve palsy or permanent hypoparathyroidism using ^99mTc MIBI for assistance in MIRS.

The relationship between technetium-99m-methoxyisobutyl isonitrile parathyroid scintigraphy and hormonal and biochemical markers in suspicion of primary hyperparathyroidism

OBJECTIVE

Technetium-99m-methoxyisobutyl isonitrile (Tc-99m MIBI) has been widely used to evaluate hyperfunctioning autonomous parathyroid glands in patients with elevated intact parathyroid hormone (iPTH) and/or calcium (Ca) level. The aim of this study was to evaluate the relationship between Tc-99m MIBI parathyroid scintigraphy and hormonal and biochemical markers in suspicion of primary hyperparathyroidism (PHPT).

MATERIAL AND METHODS

Dual-phase Tc-99m MIBI parathyroid scintigraphy and total serum iPTH, Ca, phosphorus (P) and albumin measurements were performed in 60 patients (52 females, 8 males; mean age, 59.38±12.51 years; range, 34 to 86 years) with suspicion of PHPT.

RESULTS

The iPTH median level was 160.3 pg/mL (47.8 to 782.6). Thirty-five of the patients had surgical resection of hyperfunctioning parathyroid glands. Of the 35 patients, parathyroid gland pathology was detected in 30 patients using scintigraphic examination. Tc-99m MIBI parathyroid scintigraphy was negative in 30 patients. The iPTH, Ca and P levels were significantly different between in the Tc-99m MIBI positive group and the negative group, respectively: For iPTH, 202.1 (47.8-782.6) pg/mL versus 111.6 (80.1-373) pg/mL; p<0.001. For Ca, 11.7±1.15 mg/dL versus 10.3±1.05 mg/dL; p<0.001 and for P levels, 2.46±0.62 mg/dL versus 3.40±0.70 mg/dL; p<0.001). There was no significant difference in serum albumin levels between the MIBI positive and MIBI negative groups (4.25±0.27 g/dL versus 4.25±0.41 g/dL; p>0.05). Tc-99m MIBI parathyroid scintigraphy showed good correlation with iPTH level and histopathological diagnosis. Sensitivity and specificity was found 83.3% and 76.7%, respectively at the level of iPTH>147.7pg/mL.

CONCLUSION

Tc-99m MIBI parathyroid scintigraphy is most likely to produce identification and localization of a parathyroid adenoma when both iPTH and Ca are elevated as well as decreased P levels.

CONFLICT OF INTEREST

None declared.

Efficacy of ⁹⁹mTc-sestamibi SPECT/CT for minimally invasive parathyroidectomy: comparative study with ⁹⁹mTc-sestamibi scintigraphy, SPECT, US and CT

PURPOSE

We evaluated the efficacy of (99m)Tc-sestamibi SPECT/CT for planning minimally invasive parathyroidectomy (MIP), comparing with dual phase (99m)Tc-sestamibi scintigraphy, (99m)Tc-sestamibi SPECT and conventional imaging (US and CT).

METHODS

Thirty-one patients (M:F = 10:21, range 35-78 years old) who showed high serum parathyroid hormone (intact PTH) level were included. (99m)Tc-sestamibi scintigraphy was performed 15 and 150 min after injection of (99m)Tc-sestamibi (555 MBq), and (99m)Tc-sestamibi SPECT/CT was obtained just after the delayed scan. Comparison study between imaging modalities was done by patient-based and lesion location-based analysis. The location of the lesion was confirmed by the operative finding. An operation was performed in 24 patients. Seven patients had normal (99m)Tc-sestamibi SPECT/CT, and followed for more than 6 months after SPECT/CT.

RESULTS

Among 24 patients, parathyroid adenoma was detected in 19 patients and the other 5 had parathyroid hyperplasia (total 35 lesions). (99m)Tc-sestamibi scintigraphy detected abnormal uptake in 15 patients with 24 lesions. Conventional imaging identified abnormal findings in 17 patients with 27 lesions. SPECT detected abnormal findings in 18 patients with 27 lesions. SPECT/CT identified abnormal findings in 24 patients with 35 lesions. SPECT/CT demonstrated 100 % sensitivity in a patient-based analysis. SPECT/CT exhibited significantly better sensitivity than (99m)Tc-sestamibi scintigraphy, SPECT and conventional imaging (p < 0.05). All lesion location was correctly identified to perform MIP. The final clinical diagnosis of 7 normal SPECT/CT patients was secondary hyperparathyroidism on 6 months follow-up.

CONCLUSIONS

We correctly identified the precise location of parathyroid adenomas or hyperplasia by (99m)Tc-sestamibi SPECT/CT which was helpful to perform MIP.

Dual-phase 99mTc-MIBI scintigraphy to assess calcimimetic effect in patients on haemodialysis with secondary hyperparathyroidism

OBJECTIVE

To evaluate the effect of calcimimetics with 99mTc-methoxy-isobutyl-isonitrile (MIBI) parathyroid scintigraphy in secondary hyperparathyroidism.

METHODS

This prospective study included 30 consecutive haemodialysis patients with inadequately controlled secondary hyperparathyroidism despite standard medical treatment. Patients were given a single daily oral dose of 30 mg of cinacalcet. A baseline and 1-year follow-up dual-phase 99mTc-MIBI scintigraphy were performed. 99mTc-MIBI uptake in each parathyroid gland was graded on a semiquantitative scale (scoring 0-3).

RESULTS

Twenty-one of the 30 patients responded to cinacalcet (70%). Abnormal positive glands were identified by 99mTc-MIBI scintigraphy in 27 out of 30 patients (53 glands). The sensitivity and specificity of 99mTc-MIBI in detecting cinacalcet response were 90 and 89%, respectively. The mean baseline and posttreatment grades of 99mTc-MIBI uptake were 2.9 ± 1.8 and 1.1 ± 1.2 (P < 0.0001) in the responder group and 3.1 ± 2.1 and 3.9 ± 2.2 (P = ns) in the nonresponder group.

CONCLUSION

99mTc-MIBI scintigraphy is useful in monitoring the response to calcimimetics in secondary hyperparathyroidism.

Validity of dual tracer 99mTc-tetrofosmin and 99mTc-pertechnetate subtraction parathyroid scintigraphy in patients with primary and secondary hyperparathyroidism

BACKGROUND/AIM

Primary hyperparathyroidism (pHPT) is an endocrine disease with the third highest incidence of all endocrine disorders after diabetes mellitus and hyperthyroidism. pHPT is typically caused by a solitary parathyroid adenoma, less frequently by multiple parathyroid gland disease (MGD) and rarely by parathyroid carcinoma. Secondary hyperparatyroidism (sHPT) is a common complication in patients with chronic renal failure. The aim of this study was to estimate sensitivity of dual tracer 99mTc-tetrofosmin and 99mTc-pertechnetate subtraction scintigraphy in detection of abnormal parathyroid glands in patients with pHPT and sHPT confirmed by histopathology.

METHODS

In 46 patients, (77 abnormal parathyroid glands), 30 with pHPT and 16 with sHPT parathyroid scintigraphy was done preoperatively. All the patients had histopathological confirmation of diagnosis. Abnormal parathyroid glands weighted from 0.1 to 7 g. After iv injection dynamic scintigraphy during 25 minutes (one frame-one minute) using 555 MBq of 99mTc-tetrofosmin, and three hours latter using 111 MBq of 99mTc/pertechnetate was performed. 99mTc-tetrofosmin dynamic study was followed by static scintigraphy of the neck and chest 30 minutes, 1, 2 and 3 hours after iv injection.

RESULTS

An abnormal scintigraphic finding was found in 44 of 46 patients with sensitivity of 96%. In pHPT sensitivity was 93% (28 of 30 patients, and 28 of 30 glands). In sHPT scintigraphy was abnormal in all the patients (sensitivity 100%). In the patients with sHPT scintigraphy detected 30 of 47 abnormal parathyroid glands (sensitivity 64%). An overall sensitivity of scintigraphy per gland, for pHPT and sHPT in detecting 58 of 77 abnormal parathyroid glands was 75%.

CONCLUSION

An abnormal scintigraphic result per patient was found in 44 patients (sensitivity 96%) and 58 of 77 abnormal parathyroid glands were detected (sensitivity 750/0). A high sensitivity of dual tracer subtraction 99mTc-tetrofosmin/99mTc-pertechnetate parathyroid scintigraphy in detecting abnormal parathyroid glands in primary and secondary hyperparathyroidism was achieved.

A review on the clinical uses of SPECT/CT

In the era when positron emission tomography (PET) seems to constitute the most advanced application of nuclear medicine imaging, still the conventional procedure of single photon emission computed tomography (SPECT) is far from being obsolete, especially if combined with computed tomography (CT). In fact, this dual modality imaging technique (SPECT/CT) lends itself to a wide variety of useful diagnostic applications whose clinical impact is in most instances already well established, while the evidence is growing for newer applications. The increasing availability of new hybrid SPECT/CT devices with advanced technology offers the opportunity to shorten acquisition time and to provide accurate attenuation correction and fusion imaging. In this review we analyse and discuss the capabilities of SPECT/CT for improving sensitivity and specificity in the imaging of both oncological and non-oncological diseases. The main advantages of SPECT/CT are represented by better attenuation correction, increased specificity, and accurate depiction of the localization of disease and of possible involvement of adjacent tissues. Endocrine and neuroendocrine tumours are accurately localized and characterized by SPECT/CT, as also are solitary pulmonary nodules and lung cancers, brain tumours, lymphoma, prostate cancer, malignant and benign bone lesions, and infection. Furthermore, hybrid SPECT/CT imaging is especially suited to support the increasing applications of minimally invasive surgery, as well as to precisely define the diagnostic and prognostic profile of cardiovascular patients. Finally, the applications of SPECT/CT to other clinical disorders or malignant tumours is currently under extensive investigation, with encouraging results in terms of diagnostic accuracy.

PET and PET/CT in endocrine tumours

Functional information provided by PET tracers together with the superior image quality and the better data quantification by PET technology had a changing effect on the significance of nuclear medicine in medical issues. Recently introduced hybrid PET/CT systems together with the introduction of novel PET radiopharmaceuticals have contributed to the fact that nuclear medicine has become a growing diagnostic impact on endocrinology. In this review imaging strategies, different radiopharmaceuticals including the basic mechanism of their cell uptake, and the diagnostic value of PET and PET/CT in endocrine tumours except differentiated thyroid carcinomas will be discussed.

Tc-99m sestamibi parathyroid imaging in a rare case of parathyroid lipoadenoma

Parathyroid lipoadenoma is an unusual cause of primary hyperparathyroidism. Only a few earlier reports have documented parathyroid imaging in diagnostic studies of parathyroid lipoadenoma. Our case was a 27-year-old man, who was originally diagnosed with primary hyperparathyroidism. He underwent a Tc-99m sestamibi dual-phase parathyroid imaging study, which revealed a right-inferior parathyroid hyperfunctional lesion. The first operation removed a lesion of 1.5 cm in diameter in the area, and parathyroid lipoadenoma was diagnosed by pathology. However, hypercalcemia persisted. One week later, a Tc-99m sestamibi whole-body scan and another dual-phase imagining were performed, which demonstrated a residual lesion in the inferior part of the right thyroid region, while no ectopic lesion was found. A second surgery was performed and pathological diagnosis was confirmed as parathyroid lipoadenoma again. Our case demonstrated that although hyperfunctional parathyroid lipoadenoma is rare, Tc-99m sestamibi parathyroid imaging is reliable in locating the lesion for surgical purposes. And Tc-99m sestamibi imaging is useful in reoperative and persistent hyperparathyroidism situations as well.

Recent advances in neuroendocrine imaging

PURPOSE OF REVIEW

Imaging is a critical component of both neuroendocrine lesion identification and anatomic delineation for treatment planning. Cross-sectional and isotopic-based physiologic imaging techniques have, to date, been the radiological modalities of choice. This review focuses on recent advances in imaging that are related to the evaluation of neuroendocrine abnormalities, in particular advances in MRI.

RECENT FINDINGS

Magnetic-resonance perfusion examination of tissue characteristics in the pituitary, adrenal and thyroid glands indicates that, in many cases, adenomas of these glands have distinguishable hemodynamic characteristics relative to the parenchyma of the gland as a whole and to other lesions. Moreover, perfusion metrics might provide a basis for evaluating response to therapy (in the pituitary) and delineation of lesions in the adrenal and thyroid glands. Anisotropy-based imaging techniques show promise in providing direct, relevant information about pituitary tumor involvement of the adjacent cavernous sinuses.

SUMMARY

The most recent methodological advances in the imaging of neuroendocrine disorder involves the continued development and application of MRI, in particular using pulse sequences, which provide a greater insight into the internal structure and physiology of the tissues interrogated, relative to standard sequences.

99mTc-MIBI pinhole SPECT in primary hyperparathyroidism: comparison with conventional SPECT, planar scintigraphy and ultrasonography

PURPOSE

A pinhole collimator is routinely used to increase the resolution of scintigraphy. This prospective study was conducted to determine the interest of (99m)Tc-MIBI pinhole single-photon emission computed tomography (SPECT) for the preoperative localisation of parathyroid lesions in primary hyperparathyroidism.

METHODS

All patients underwent a neck ultrasonography (US), (99m)TcO4- and (99m)Tc-MIBI planar images and two consecutive SPECT with a parallel (C-SPECT) and a pinhole collimator (P-SPECT). P-SPECT was performed with a tilted detector equipped with a pinhole collimator and reconstructed with a dedicated OSEM algorithm. A diagnostic confidence score (CS) was assigned to each procedure considering intensity and extra-thyroidal location of suspected lesions: 0 = negative, 1 = doubtful, 2 = moderately positive, 3 = positive. The results of these preoperative localisation studies were compared with surgical, pathological and 6-month biological findings.

RESULTS

Fifty-one patients cured after surgery were included. Surgery revealed 55 lesions (median weight 0.5 g, 11 in ectopy). Sensitivities of US, planar imaging, C-SPECT and P-SPECT were, respectively, 51, 76, 82 and 87%. Nine glands were only detected by tomography and five glands only by P-SPECT. 99mTc-MIBI/99mTcO4- planar scans and P-SPECT were complementary and, when combined together, showed the highest sensitivity (93%). Compared with planar imaging and C-SPECT, P-SPECT increased CS for 42 and 53% of lesions, respectively, and contributed to markedly reduce the number of uncertain results.

CONCLUSIONS

A combination of planar 99mTc-MIBI/99mTcO4- scintigraphy and P-SPECT appears to be a highly accurate preoperative imaging procedure in primary hyperparathyroidism.