Role of SPECT/CT in the preoperative assessment of hyperparathyroid patients

An Approach to a Patient With Primary Hyperparathyroidism and a Suspected Ectopic Parathyroid Adenoma

Primary hyperparathyroidism (PHPT) is characterized by hypercalcemia driven by excess parathyroid hormone (PTH) secretion. PHPT is a common endocrine condition with a prevalence of 1 to 7 cases per 1000 adults. PHPT typically presents in the fifth or sixth decade and shows significant female preponderance. Solitary hyperfunctioning parathyroid adenomas account for 85% to 90% of PHPT cases. The remaining 10% to 15% include cases of multiglandular disease (multiple adenomas or hyperplasia) and, rarely, parathyroid carcinoma (1%). Ectopic parathyroid adenomas may arise due to abnormal embryological migration of the parathyroid glands and can be difficult to localize preoperatively, making surgical cure challenging on the first attempt. The potential existence of multiglandular disease should be considered in all patients in whom preoperative localization fails to identify a target adenoma or following unsuccessful parathyroidectomy. Risk factors for multiglandular disease include underlying genetic syndromes (eg, MEN1/2A), lithium therapy, or previous radiotherapy. In addition to multifocal disease, the possibility of an ectopic parathyroid gland should also be considered in patients requiring repeat parathyroid surgery. In this article, we use illustrative clinical vignettes to discuss the approach to a patient with primary hyperparathyroidism (PHPT) and a suspected ectopic parathyroid adenoma.

Incremental Value of Sestamibi SPECT/CT Over Dual-Phase Planar Scintigraphy in Patients With Primary Hyperparathyroidism and Inconclusive Ultrasound

Background: We evaluated the incremental value of [^99mTc]sestamibi single photon-emission computed tomography (SPECT)/computed tomography (CT) over planar imaging for localization of abnormal parathyroid tissue in patients with primary hyperparathyroidism.

Methods: Forty-six patients with biochemical evidence of hyperparathyroidism and inconclusive ultrasound underwent sestamibi dual-phase planar scintigraphy and SPECT/CT for preoperative localization of parathyroid adenoma. Imaging findings were compared with histopathological data. Decision tree analysis was performed to evaluate the value of SPECT/CT over planar scintigraphy for classifying patients with or without hyperfunctioning parathyroid tissue. The added value of SPECT/CT was also evaluated by decision curve analysis.

Results: Planar scintigraphy was positive for presence of hyperfunctioning parathyroid in 52% of patients, with sensitivity of 63% and specificity of 100%. SPECT/CT was positive in 80% of patients with sensitivity of 97% and specificity of 100%. At decision tree analysis, after an initial split on planar imaging results, no further split was performed in patients with positive results, while those with negative results were further stratified by SPECT/CT. At decision curve analysis, the model including SPECT/CT was associated with the highest net benefit compared to the model including only planar technique and to a strategy considering that all patients should be treated.

Conclusion: Sestamibi SPECT/CT provides incremental value over dual-phase scintigraphy in preoperative localization of hyperfunctioning parathyroid tissue in subjects with inconclusive ultrasound. Hybrid technique allows a better identification of pathological lesion to perform minimally invasive surgery and showed the highest net benefit, improving selection of surgical approach.

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.

99m-Technetium Sestamibi Uptake in a Gastric Schwannoma

We report the case of a 74-year-old woman with primary hyperparathyroidism who underwent 99m-technetium-sestamibi single photon emission computed tomography-computed tomography for preoperative localization of parathyroid adenoma. Unexpected focal sestamibi uptake was observed at a 5 cm submucosal tumor arising from the greater curve of the stomach. The patient underwent partial gastrectomy and the histological and immunohistochemical findings were consistent with the diagnosis of gastric schwannoma.

Hybrid-fusion SPECT/CT systems in parathyroid adenoma: Technological improvements and added clinical diagnostic value

Nuclear medicine traditionally employs planar and single photon emission computed tomography (SPECT) imaging techniques to depict the biodistribution of radiotracers for the diagnostic investigation of a range of disorders of endocrine gland function. The usefulness of combining functional information with anatomy derived from computed tomography (CT), magnetic resonance imaging (MRI), and high resolution ultrasound (US), has long been appreciated, either using visual side-by-side correlation, or software-based co-registration. The emergence of hybrid SPECT/CT camera technology now allows the simultaneous acquisition of combined multi-modality imaging, with seamless fusion of 3D volume datasets. Thus, it is not surprising that there is growing literature describing the many advantages that contemporary SPECT/CT technology brings to radionuclide investigation of endocrine disorders, showing potential advantages for the pre-operative locating of the parathyroid adenoma using a minimally invasive surgical approach, especially in the presence of ectopic glands and in multiglandular disease. In conclusion, hybrid SPECT/CT imaging has become an essential tool to ensure the most accurate diagnostic in the management of patients with hyperparathyroidism.

Endocrine radionuclide scintigraphy with fusion single photon emission computed tomography/computed tomography

AIM: To review the benefits of single photon emission computed tomography (SPECT)/computed tomography (CT) hybrid imaging for diagnosis of various endocrine disorders.

METHODS: We performed MEDLINE and PubMed searches using the terms: “SPECT/CT”; “functional anatomic mapping”; “transmission emission tomography”; “parathyroid adenoma”; “thyroid cancer”; “neuroendocrine tumor”; “adrenal”; “pheochromocytoma”; “paraganglioma”; in order to identify relevant articles published in English during the years 2003 to 2015. Reference lists from the articles were reviewed to identify additional pertinent articles. Retrieved manuscripts (case reports, reviews, meta-analyses and abstracts) concerning the application of SPECT/CT to endocrine imaging were analyzed to provide a descriptive synthesis of the utility of this technology.

RESULTS: The emergence of hybrid SPECT/CT camera technology now allows simultaneous acquisition of combined multi-modality imaging, with seamless fusion of three-dimensional volume datasets. The usefulness of combining functional information to depict the bio-distribution of radiotracers that map cellular processes of the endocrine system and tumors of endocrine origin, with anatomy derived from CT, has improved the diagnostic capability of scintigraphy for a range of disorders of endocrine gland function. The literature describes benefits of SPECT/CT for ^99mTc-sestamibi parathyroid scintigraphy and ^99mTc-pertechnetate thyroid scintigraphy, ¹²³I- or ¹³¹I-radioiodine for staging of differentiated thyroid carcinoma, ¹¹¹In- and ^99mTc- labeled somatostatin receptor analogues for detection of neuroendocrine tumors, ¹³¹I-norcholesterol (NP-59) scans for assessment of adrenal cortical hyperfunction, and ¹²³I- or ¹³¹I-metaiodobenzylguanidine imaging for evaluation of pheochromocytoma and paraganglioma.

CONCLUSION: SPECT/CT exploits the synergism between the functional information from radiopharmaceutical imaging and anatomy from CT, translating to improved diagnostic accuracy and meaningful impact on patient care.

Contribution of early SPECT/CT to 99mTc-MIBI double phase scintigraphy in primary hyperparathyroidism: Diagnostic value and correlation between uptake and biological parameters

AIM

To evaluate the value of ^99mTc-MIBI double-phase scintigraphy (DPS) and early SPECT/CT in the pre-surgical assessment of patients with primary hyperparathyroidism (PHPT). Also, to calculate the correlation between uptake and some biological parameters.

MATERIAL AND METHODS

Forty patients with PHPT were included: 37 solitary adenomas, 1 hyperplasia, and 2 double adenomas. Fifteen patients had ectopic glands. DPS and early SPECT/CT were acquired in all patients. Ultrasound was performed in 31/40. All patients underwent surgery, intra-operative iPTH measurements, and histopathological examinations. Qualitative DPS uptake was assessed and correlated to pre-surgical calcium, iPTH levels, gland weight, and maximum diameter.

RESULTS

In the planar study, there were 23 positive cases, 8 doubtful, and 9 negatives. With the SPECT/CT, 8/9 negatives cases were located. All doubtful cases were confirmed as positives. Gland location improved in 16 cases (12 ectopic). DPS+SPECT/CT failed to detect a solitary adenoma and at least one gland in three cases of multiglandular disease (MGD). The sensitivity by patient was: DPS 72.5%, DPS+SPECT/CT 90%, and ultrasound 42%. Ultrasound and scintigraphy (DPS+SPECT/CT) were concordant in 16/31 patients. For the rest of them, scintigraphy proved correct in 14/15, and both techniques failed in one case. There was a significant correlation between level of uptake and iPTH level, gland weight, and maximum diameter.

CONCLUSION

Early SPECT/CT improves sensitivity and the locating of parathyroid pathological glands and increases diagnostic confidence. iPTH level, glandular size, and weight are related to the qualitative assessment of ^99mTc-MIBI uptake in early DPS.

Comparison of single photon emission CT (SPECT) with SPECT/CT imaging in preoperative localization of parathyroid adenomas: A cost-effectiveness analysis

BACKGROUND

Controversy exists regarding the superiority of single photon emission CT (SPECT)/CT over SPECT for preoperative localization of parathyroid adenomas in primary hyperparathyroidism (PHPT), as well as the cost-effectiveness.

METHODS

A retrospective review was undertaken of patients undergoing surgery for PHPT from January 2009 to August 2014. Ultrasound and SPECT (ultrasound-SPECT) or SPECT/CT (ultrasound-SPECT/CT) were performed for each patient. Sensitivity and positive predictive value (PPV) of each modality were calculated. Cost-effectiveness was determined by an incremental cost-effectiveness ratio (ICER) analysis.

RESULTS

Two hundred fifty-nine patients with 266 parathyroid adenomas were included in the study. Lateralization sensitivity and PPV of ultrasound-SPECT were 85.1% and 98.2%, respectively. The lateralization sensitivity and PPV of ultrasound-SPECT/CT were 86.9% and 99.4%, respectively. A cost of $2499.22 (CAD) per additional parathyroid adenoma detection by ultrasound-SPECT/CT was determined from the ICER analysis.

CONCLUSION

Similar sensitivities and PPVs were observed between ultrasound-SPECT and ultrasound-SPECT/CT in preoperatively lateralizing parathyroid adenomas, with relatively equivalent cost-effectiveness. © 2016 Wiley Periodicals, Inc. Head Neck 38: E2062-E2065, 2016.

Parathyroid adenoma localization with 99mTc-sestamibi SPECT/CT: a meta-analysis

PURPOSE

The aim of the study was to determine the diagnostic utility of parathyroid scintigraphy with technetium-99m (99mTc)-sestamibi single-photon emission computed tomography/computed tomography (SPECT/CT) for localization of parathyroid adenoma.

MATERIALS AND METHODS

We performed a systematic search of medical databases PubMed and Medline/OVID for literature on 99mTc-sestamibi SPECT/CT parathyroid scintigraphy, using the search terms hyperparathyroidism, parathyroid adenoma/hyperplasia, SPECT/CT, and SPECT-CT. Citations for 981 articles and 128 abstracts of full articles were reviewed by two coauthors for relevance. Twenty-four peer-reviewed studies on SPECT/CT parathyroid scintigraphy qualified for inclusion. The Quality Assessment of Diagnostic Accuracy Studies-2 tool was used to assess study quality. Meta-analytical techniques were used to obtain pooled estimates of the parathyroid adenoma localization rate using a random-effects model.

RESULTS

A total of 24 studies published between January 2003 and March 2014 with 1276 patients (334 men, 762 women, and 180 of unspecified sex) met the inclusion criteria. Data on the test performance of dual-phase 99mTc-sestamibi SPECT/CT showed an estimated pooled sensitivity (per-patient analysis) of 0.86 [confidence interval (CI) 0.81-0.90]. Sensitivity of SPECT/CT was superior to that of SPECT (0.74; CI 0.66-0.82) and planar (0.70; CI 0.61-0.80) techniques. Heterogeneity was present in the reported literature (I2=80.3%). The rate of ectopic parathyroid adenomas ranged between 4 and 20% and SPECT/CT was superior to SPECT and planar imaging for localization of ectopic sites.

CONCLUSION

Utilization of SPECT/CT fusion imaging for 99mTc-sestamibi parathyroid scintigraphy improves the test performance compared with planar and SPECT imaging; it assists preoperative planning for a minimally invasive surgical approach for the neck and is of value in subgroups with ectopic glands or coexisting nodular thyroid disease.

Endocrine scintigraphy with hybrid SPECT/CT

Nuclear medicine imaging of endocrine disorders takes advantage of unique cellular properties of endocrine organs and tissues that can be depicted by targeted radiopharmaceuticals. Detailed functional maps of biodistributions of radiopharmaceutical uptake can be displayed in three-dimensional tomographic formats, using single photon emission computed tomography (CT) that can now be directly combined with simultaneously acquired cross-sectional anatomic maps derived from CT. The integration of function depicted by scintigraphy and anatomy with CT has synergistically improved the efficacy of nuclear medicine imaging across a broad spectrum of clinical applications, which include some of the oldest imaging studies of endocrine dysfunction.

Strategy of operative treatment of hyperparathyroidism using US scan and (99m)Tc-MIBI SPECT/CT

We evaluated the efficacy of technetium-sestamibi ((99m) Tc-MIBI) SPECT/CT for planning parathyroidectomy in cases with primary hyperparathyroidism (pHPT), comparing with planar scintigraphy and ultrasound (US), in an aim to establish the proper surgical strategy according to the preoperative imaging studies. A retrospective review of consecutive 75 pHPT patients who had been operated on was conducted. The results of preoperative imaging modalities and the operative finding were analyzed. Seven cases were found to have multiple hyperplastic glands, and no responsible gland was found in three cases. Four cases underwent only US scan for preoperative imaging. Remaining 61 cases were found to have single adenoma, and were included in the evaluation of localization imaging. US scan, (99m) Tc-MIBI planar scan and (99m) Tc-MIBI SPECT/CT showed accurate localization in 77.0% (47/61), 75.4% (46/61) and 88.5% (46/52) of the evaluable cases, respectively. US and (99m) Tc-MIBI planar scan demonstrated consistent result in 42 cases (68.9%), and those cases showed accurate localization in 90.5% (38/42). When both US and (99m) Tc-MIBI SPECT/CT was consistent, all 37 lesions had been correctly indicated. No clinico-pathological features were suggested to influence in demonstrating the localization, other than only (99m) Tc-MIBI SPECT/CT exhibited 100% sensitivity in ectopic glands. Combination of US and (99m) Tc-MIBI SPECT/CT certainly contributes to the planning of minimally invasive operation in cases with pHPT by indicating correct localization of single adenoma.

A spectrum of SPECT/CT image fusion applications in daily clinical practice

Direct multimodality image correlation optimizes interpretation and diagnostic confidence, thereby enriching the radiologist's role in guiding clinical management. The primary advantages of SPECT/CT image fusion are more accurate identification and localization of disease and improved specificity. As illustrated here, software-based SPECT/CT image fusion enhances diagnosis for a variety of clinical presentations using the armamentarium of common radiopharmaceuticals, but without the costs of hybrid systems.

Comparison of five parathyroid scintigraphic protocols

Objectives. We compared five parathyroid scintigraphy protocols in patients with primary (pHPT) and secondary hyperparathyroidism (sHPT) and studied the interobserver agreement. The dual-tracer method ((99m)Tc-sestamibi/(123)I) was used with three acquisition techniques (parallel-hole planar, pinhole planar, and SPECT/CT). The single-tracer method ((99m)Tc-sestamibi) was used with two acquisition techniques (double-phase parallel-hole planar, and SPECT/CT). Thus five protocols were used, resulting in five sets of images. Materials and Methods. Image sets of 51 patients were retrospectively graded by four experienced nuclear medicine physicians. The final study group consisted of 24 patients (21 pHPT, 3 sHPT) who had been operated upon. Surgical and histopathologic findings were used as the standard of comparison. Results. Thirty abnormal parathyroid glands were found in 24 patients. The sensitivities of the dual-tracer method (76.7-80.0%) were similar (P = 1.0). The sensitivities of the single-tracer method (13.3-31.6%) were similar (P = 0.625). All differences in sensitivity between these two methods were statistically significant (P < 0.012). The interobserver agreement was good. Conclusion. This study indicates that any dual-tracer protocol with (99m)Tc-sestamibi and (123)I is superior for enlarged parathyroid gland localization when compared with single-tracer protocols using (99m)Tc-sestamibi alone. The parathyroid scintigraphy was found to be independent of the reporter.

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.

Role of SPECT and SPECT/CT in the Surgical Treatment of Primary Hyperparathyroidism

Primary hyperparathyroidism is the most common cause of hypercalcemia in the outpatient population. This condition is usually the result of a single hyperfunctioning parathyroid gland. Targeted parathyroidectomy guided by intraoperative parathyroid hormone monitoring (IPM) through a small cervical incision has replaced traditional bilateral neck exploration (BNE) as the initial approach in the surgical treatment of primary hyperparathyroidism at many medical centers worldwide. Preoperative sestamibi-technetium 99m scintigraphy serves as an important prerequisite for successful targeted parathyroidectomy. Single-photon emission computed tomography (SPECT) and CT fusion, however, is a recent imaging technique that provides a three-dimensional functional image with advanced contrast resolution to greatly improve preoperative localization of parathyroid tumors.

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.

[Ectopic parathyroid adenoma: Scintigraphic detection and radioguided surgery]

AIM

The aim of this study was to evaluate the role of (99m)Tc-MIBI parathyroid scintigraphy and radioguided parathyroidectomy on the diagnosis and treatment of primary hyperparathyroidism (PHP) due to ectopic adenomas.

METHODS

We reviewed 105 consecutive patients who underwent radioguided parathyroidectomy due to adenomas between March 2004 and December 2008. Of this group we studied 20 patients (19%) with ectopic adenomas. All patients had biochemical evidence of PHP, a positive parathyroid scintigraphy, radioguided detection with histolopathological confirmation of adenoma and at least 1 year-follow up. The parathyroid scintigraphy consisted on dual-phase planar and tomographic images (SPECT or SPECT/CT). During the parathyroidectomy, intraoperative PTH determinations (0, 7, 15 and 30 min after the parathyroidectomy) were done. The follow up consisted on blood examinations of PTH, calcium, phosphorus and vitamin D and assessment of renal function.

RESULTS

Parathyroid scintigraphy detected all adenomas. Scintigraphic and surgical findings were coincident in 18 cases (90%). The final adenoma localization was paraesophagic in 9 patients, cervicothymic in 5, posterior cervicomediastinal in 4, anterior mediastinal in 1 and parathymic in 1. The parathyroidectomy consisted on 12 minimally invasive surgeries, 2 unilateral cervicotomies, 4 bilateral cervicotomies and 2 sternotomies. No case of persistent or recurrent PHP was observed during the follow up.

CONCLUSIONS

Parathyroid scintigraphy (SPECT/CT) and radioguided surgery are effective methods on the localization and treatment of PHP due to ectopic adenomas. In our study the radioguided parathyroidectomy was successful in all cases and there was no evidence of persistent or recurrent hyperparathyroidism on the follow up.

Clinical appraisal of 99m technetium-sestamibi SPECT/CT compared to conventional SPECT in patients with primary hyperparathyroidism and concomitant nodular goiter

BACKGROUND

Although 99m Technetium-sestamibi scintigraphy with single-photon emission computed tomography (SPECT) and, recently, hybrid SPECT/computed tomography (CT) have been claimed to be the preoperative methods of choice for parathyroid localization in patients with primary hyperparathyroidism (PHPT) and concomitant nodular goiter (NG), they have never been compared in this setting. We aimed at testing the hypothesis that SPECT/CT may be superior to SPECT for parathyroid localization in patients with PHPT and NG.

METHODS

Thirty-three patients with PHPT and NG (one or more nodular lesions based on cervical ultrasound) who underwent open parathyroidectomy during 2004-2009 were reviewed. All patients had preoperative 99m Tc-sestamibi planar scintigraphy and SPECT (18 patients) or SPECT/CT (15 patients) after cervical ultrasound. Sensitivity, specificity, and positive predictive value (PPV) (for both correct neck side and quadrant identification) were calculated for the two procedures through comparison with intraoperative findings. In addition, operative times were assessed if the surgery was only for PHPT and not for the six patients who also had thyroidectomy.

RESULTS

The sensitivity of SPECT/CT for correctly identifying the neck side containing an abnormal parathyroid was 93.7% versus 80% for SPECT (p = 0.21, not significant [ns]). The specificity and PPV for this attribute were 92.9% and 93.7%, respectively, for SPECT/CT versus 87.5% and 88.9%, respectively, for SPECT (p = 0.75 and 0.8, ns). SPECT/CT showed higher sensitivity than SPECT (87.5% vs. 55.6%; p = 0.0001) and higher PPV (87.5% vs. 62.5%; p = 0.0022) for correctly identifying the neck quadrant affected by PHPT. The specificity for this was 95.5% for SPECT/CT versus 88.5% for SPECT (p = 0.26, ns). Mean operative time was shorter after SPECT/CT than after SPECT (38 vs. 56 minutes; p = 0.034). One of the patients having SPECT/CT had double adenomas, and two had ectopic parathyroid glands, all of which were recognized preoperatively by this technique. Two of the patients having SPECT had double adenomas, and two had ectopic glands, none of which were recognized preoperatively. No patient had persistent or recurrent PHPT.

CONCLUSIONS

SPECT/CT is superior to SPECT for preoperative imaging of patients with PHPT and NG. We recommend the routine use of SPECT/CT for work-up of all such patients, particularly if minimally invasive parathyroid surgery is planned.

Imaging of parathyroid glands

Preoperative imaging studies have an important role in facilitating successful localization of adenomas for surgeons. Their use has increased and parallels the recent growth of minimally invasive parathyroidectomy. Based on findings that scintigraphy is reported to have the highest accuracy for localization of adenomas when compared with anatomic imaging techniques, this article discusses the current role and limitations of imaging, with a focus on scintigraphy, in the evaluation of patients before surgery for hyperparathyroidism.

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.

Hybrid SPECT/CT imaging for primary hyperparathyroidism: case reports and pictorial review

The utility of hybrid single photon emission computed tomography/computed tomography imaging for primary hyperparathyroidism is both intuitive and becoming increasingly apparent clinically, particularly for patients with prior failed surgery and for those with suspected ectopic adenomas. Second generation imaging equipment, capable of superimposing functional information on highly detailed anatomic images is proving useful in surgical planning, permitting the successful application of minimally invasive techniques. The clinical background and hybrid imaging modality are discussed, together with a selection of illustrative case images. Special emphasis is placed on the use of the technique for imaging ectopic parathyroid adenomas.

Hybrid imaging (SPECT/CT and PET/CT): improving therapeutic decisions

The incremental diagnostic value of integrated positron emission tomography-computed tomography (PET/CT) or single-photon emission computed tomography (SPECT)/CT images compared with PET or SPECT alone, or PET or SPECT correlated with a CT obtained at a different time includes the following: (1) improvement in lesion detection on both CT and PET or SPECT images, (2) improvement in the localization of foci of uptake resulting in better differentiation of physiological from pathologic uptake, (3) precise localization of the malignant foci, for example, in the skeleton vs soft tissue or liver vs adjacent bowel or node (4) characterization of serendipitous lesions, and (5) confirmation of small, subtle, or unusual lesions. The use of these techniques can occur at the time of initial diagnosis, in assessing the early response of disease to treatment, at the conclusion of treatment, and in continuing follow-up of patients. PET/CT and SPECT/CT fusion images affect the clinical management in a significant proportion of patients with a wide range of diseases by (1) guiding further procedures, (2) excluding the need of further procedures, (3) changing both inter- and intramodality therapy, including soon after treatment has been initiated, and (4) by providing prognostic information. PET/CT fusion images have the potential to provide important information to guide the biopsy of a mass to active regions of the tumor and to provide better maps than CT alone to modulate field and dose of radiation therapy. It is expected that the role of PET/CT and SPECT/CT in changing management will continue to evolve in the future and that these tools will be fundamental components of the truly "personalized medicine" we are striving to deliver.

SPECT/CT in localization of parathyroid adenoma or hyperplasia in patients with previous neck surgery

PURPOSE

Single photon emission computed tomography/computed tomography (SPECT/CT) now makes it possible to use combined morphologic CT and functional scintigraphy information. It has proved useful for localization of abnormal parathyroid glands, especially in the case of an ectopic gland. We experienced that it was also beneficial for patients with a history of previous neck surgery, and we report 4 cases in this entity.

MATERIALS AND METHODS

Four patients with prior neck surgery and hyperparathyroidism underwent parathyroid Tc-99m MIBI scintigraphy with SPECT/CT. Two patients had undergone surgery for hyperparathyroidism and 2 had undergone thyroidectomy, 1 for thyroid cancer and 1 for multinodular goiter. Parathyroid hormone levels were assessed during surgery, and patients were followed several months after treatment.

RESULTS

SPECT/CT successfully localized the abnormal gland, including an uncommon anterior situation for which previous surgery guided by planar imagery failed to cure the hyperparathyroidism. It allowed efficient surgical treatment, as confirmed by parathyroid hormone level normalization, without complications and with a relatively short operation time in those challenging cases.

CONCLUSIONS

SPECT/CT seems to be a useful tool for presurgical assessment in hyperparathyroidism, not only for ectopic glands but also for patients with previous neck surgery.