A Pilot Comparison of 18F-fluorocholine PET/CT,Ultrasonography and 123I/99mTc-sestaMIBI Dual-Phase Dual-Isotope Scintigraphy in the Preoperative Localization of Hyperfunctioning Parathyroid Glands in Primary or Secondary Hyperparathyroidism: Influence of Thyroid Anomalies

We compared ¹⁸F-fluorocholine hybrid positron emission tomography/X-ray computed tomography (FCH-PET/CT) with ultrasonography (US) and scintigraphy in patients with hyperparathyroidism and discordant, or equivocal results of US and ¹²³I/^99mTc-sesta-methoxyisobutylisonitrile (sestaMIBI) dual-phase parathyroid scintigraphy. FCH-PET/CT was performed in 17 patients with primary (n = 11) lithium induced (n = 1) or secondary hyperparathyroidism (1 dialyzed, 4 renal-transplanted).The reference standard was based on results of surgical exploration and histopathological examination. The results of imaging modalities were evaluated, on site and by masked reading, on per-patient and per-lesion bases.In a first approach, equivocal images/foci were considered as negative. On a per-patient level, the sensitivity was for US 38%, for scintigraphy 69% by open and 94% by masked reading, and for FCH-PET/CT 88% by open and 94% by masked reading. On a per-lesion level, sensitivity was for US 42%, for scintigraphy 58% by open and 83% by masked reading, and for FCH-PET/CT 88% by open and 96% by masked reading. One ectopic adenoma was missed by the 3 imaging modalities. Considering equivocal images/foci as positive increased the accuracy of the open reading of scintigraphy or of FCH-PET/CT, but not of US. FCH-PET/CT was significantly superior to US in all approaches, whereas it was more sensitive than scintigraphy only for open reading considering equivocal images/foci as negative (P = 0.04). FCH uptake was more intense in adenomas than in hyperplastic parathyroid glands. Thyroid lesions were suspected in 9 patients. They may induce false-positive results as in one case of oncocytic thyroid adenoma, or false-negative results as in one case of intrathyroidal parathyroid adenoma. Thyroid cancer (4 cases) can be visualized with FCH as with ^99mTc-sestaMIBI, but the intensity of uptake was moderate, similar to that of parathyroid hyperplasia.This pilot study confirmed that FCH-PET/CT is an adequate imaging tool in patients with primary or secondary hyperparathyroidism, since both adenomas and hyperplastic parathyroid glands can be detected. The sensitivity of FCH-PET/CT was better than that of US and was not inferior to that of dual-phase dual-isotope ¹²³I/^99mTc-scintigraphy. Further studies should evaluate whether FCH could replace ^99mTc-sestaMIBI as the functional agent for parathyroid imaging, but US would still be useful to identify thyroid lesions.     

Multimodality imaging of the parathyroid glands in primary hyperparathyroidism

Primary hyperparathyroidism is a common endocrine disorder, affecting approximately 1 in 500 women and 1 in 2,000 men. Surgical removal of the hyperfunctioning parathyroid gland is the primary curative treatment. The last decade has witnessed the development of minimally invasive parathyroidectomy, which is based on the fact that the vast majority of cases are caused by single adenomas. However, the success of this technique relies on accurate preoperative localisation of the parathyroid lesions. The imaging modalities used vary at different institutions according to local expertise and availability, but include high resolution ultrasound, radionuclide studies, computed tomography (CT) and magnetic resonance imaging (MRI). Ultrasound and 99mTc sestamibi scintigraphy, particularly when complemented by single photon emission computed tomography (SPECT), are currently the imaging techniques of choice for preoperative localisation of parathyroid adenomas; a combination of the two methods further improves the sensitivity and accuracy of detection. CT is less commonly used for preoperative localisation and usually reserved for cases of failed parathyroidectomy, for the detection of suspected ectopic glands. MRI appears to be useful in patients with persistent or recurrent hyperparathyroidism, who have previously undergone surgery. Cross-sectional imaging is also useful in cases where the findings at sonography and scintigraphy are discordant. SPECT/CT appears promising, but further studies are needed to evaluate its role in preoperative localisation.     

Utility of 99mTc-sestamibi scintigraphy as a first-line imaging procedure in the preoperative evaluation of hyperparathyroidism

OBJECTIVE The use of preoperative imaging in patients with hyperparathyroidism remains controversial. Many of the available techniques are insufficiently sensitive and specific to justify their routine use. We have evaluated the Sensitivity and specificity of ^99mTc-sestamibi scintigraphy in the management of patients with different forms of hyperparathyroidism. DESIGN Preoperative imaging evaluation was carried out by sclntigraphic detection of pathological parathyroid glands using ^99mTc-sestamibi as a radiotracer; confirmation of scan findings was obtained surgically. PATIENTS A group of 25 patients with primary (n= 21) or secondary (n=4) hyperparathyroidism were studied. All were considered for surgical treatment. MEASUREMENTS In all cases parathyroid imaging was carried out by ^99mTc-sestamibi scintigraphy together with at least one other imaging technique which included CT-scan, ultrasonography, MRI or ²⁰¹TI/^99mTc subtraction scintigraphy. Blood tests included measurements of total calcium and PTH. RESULTS ^99mTc-sestamibi scintigraphy correctly localized 20 out of 21 adenomas, giving a sensitivity of 95.2%, markedly higher than that obtained with the other imaging techniques (ultrasonography 75%, ²⁰¹TI/^99mTc subtraction scintigraphy 57.1%, CT-scan 41.7% and MRI 33%). Of a total of 17 glands identified surgically as hyperplastic and confirmed by pathological examination, ^99mTc-sestamibi scintigraphy showed a positive image in 10, corresponding always to the larger abnormal glands (sensitivity 58.8%, higher than that observed with the other techniques). No false positive images were obtained with ^99mTc-sestamibi. All the ectopic adenomas (n= 3) were identified preoperatively, which contributed significantly to the surgical approach. CONCLUSION In patients with hyperparathyroidism, ^99mTc-sestamibi scintigraphy may be used as the single imaging technique as it shows a very high sensitivity and specificity in the preoperative localization of pathological parathyroid glands; the benefit of localizing parathyroid tissue prior to surgery in cases of ectopic adenomas clearly indicates that when an imaging procedure is required, this technique may be of great help in the management of hyperparathyroidism.     

Video-assisted thoracoscopic surgery as a first-line treatment for mediastinal parathyroid adenomas: strategic value of imaging

OBJECTIVE: To present first-line thoracic surgery made possible by localization studies in three patients with ectopic parathyroid adenomas. DESIGN AND METHODS: Three patients with ectopic parathyroid tissue in the mediastinum were examined by ultrasound, technetium-99m sestamibi scintigraphy, computed tomography (CT), and venous catheterization with measurement of parathyroid hormone. Without previous cervical exploration, video-assisted thoracic surgery (VATS) was used in all cases to avoid the need for thoracic open surgical procedures. RESULTS AND CONCLUSIONS: The mediastinal parathyroid glands were all detected at scintigraphy, and CT and venous catheterization were helpful in anatomic and functioning characterization. All pathologic glands were successfully resected, with only one minor complication. VATS can safely remove a deep mediastinal parathyroid adenoma and avoid more aggressive open approaches. In an experienced referral center, systematic and sophisticated imaging studies may accurately identify and localize rare ectopic parathyroid adenomas, and avoid cervical surgery.     

Is Brown Adipose Tissue Visualization Reliable on 99mTc-Methoxyisobutylisonitrile Diagnostic SPECT Scintigraphy?

The ^99mTc-MIBI has been used with great value as a diagnostic technique in patients with primary hyperparathyroidism. False-positive scans may occur due to misinterpretation of the physiologic distribution of the ^99mTc-MIBI. Reviewing consecutive SPECT scans, we evaluated this possibility and assessed how frequently brown adipose tissue (BAT) is seen on ^99mTc-MIBI scintigraphy.Here, we retrospectively reviewed scans of consecutive patients who were evaluated for parathyroid adenomas from March 2015 to June 2015, using dual-phase (early and delayed) planar imaging and SPECT. We identified 60 patients (48 female and 12 male; mean age, 52.25 ± 15.20 years; range, 22–86 years).We detected the presence of ^99mTc-MIBI uptake in BAT in 20 of 60 patients (33.33%) in the neck. Although the patients with ^99mTc-MIBI uptake in BAT were younger (mean age, 48.85 ± 15.27 years, range, 26–73 years) than the patients with no ^99mTc-MIBI uptake (mean age, 53.95 ± 15.07 years, range, 22–86 years), this difference was not statistically significant (P = 0.224). The percentage of female patients with BAT detection was higher (17/48 patients; 37.5%) than that of the male population (3/12 patients; 25%), this difference was not also statistically significant (P = 0.85).In patient population referred to ^99mTc MIBI scintigraphy of the parathyroid glands, uptake of ^99mTc-MIBI in BAT should not be misinterpreted with ^99mTc-MIBI-avid-tumors. Fused SPECT/CT images (not SPECT-only) are necessary to distinguish BAT from bone, muscle, thyroid, myocardium, parathyroids, and other structures in the neck and chest.     

Comparison of perfusion 18F-FP-CIT PET and 99mTc-ECD SPECT in parkinsonian disorders

Early and accurate identification of various conditions that can cause parkinsonian symptoms is important for determining treatment policies. Currently dopamine transporter (DAT) imaging using FP-CIT, glucose metabolism imaging using fluorodeoxyglucose, cerebral blood flow image using ethyl cysteinate dimer (ECD), and others are used for differentiation. However, the use of multiple modalities is inconvenient and costly. In the present retrospective study, we evaluated the correlation between regional brain uptake ratios (URs) in perfusion FP-CIT PET and ECD SPECT images.Twenty patients with Parkinson''s symptoms underwent perfusion DAT positron emission tomography (¹⁸F-FP-CIT PET/CT) and cerebral blood flow tomography (^99mTc-ECD SPECT) within a 2-week period. Perfusion ¹⁸F-FP-CIT PET/CT and ^99mTc-ECD SPECT URs of 19 brain regions (bilateral frontal, temporal, parietal and occipital lobes, bilateral caudate nucleus, bilateral putamen, bilateral insula, bilateral cingulate gyrus, bilateral thalamus, and brainstem) were directly compared and correlations were analyzed.Average ¹⁸F-FP-CIT PET/CT regional perfusion URs were higher than ^99mTc-ECD SPECT URs. Uptake ratios were well correlated in all 19 regions (except right putamen), and especially in dopamine poor regions (cerebral cortex). In left putamen, URs were significantly correlated, but the correlation coefficient was lower than those of other regions.A single tracer dual phase N-3-fluoropropyl-2-beta-carboxymethoxy-3-beta-(4-iodophenyl) nortropane test seems to be helpful for differential diagnosis of parkinsonian disorders. Large-scale, longitudinal studies on complementary diseases with parkinsonian patterns are required to investigate differences in correlations between perfusion ¹⁸F-FP-CIT PET/CT and ^99mTc-ECD SPECT over time.     

Technetium-99m tetrofosmin parathyroid imaging in patients with primary hyperparathyroidism

OBJECTIVE: To confirm the clinical significance of 99mTc-tetrofosmin imaging for the localization of hyperfunctioning parathyroid glands in patients with primary hyperparathyroidism. METHODS: All patients were imaged with 99mTc-tetrofosmin at 10 minutes and 2 hours after radiotracer injection, and with ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI). The parathyroid/thyroid uptake ratio of 99mTc-tetrofosmin (P/T uptake ratio) was calculated. PATIENTS: Twenty patients with primary hyperparathyroidism were referred to our clinic, underwent surgical neck exploration or mediastinotomy and were diagnosed as having parathyroid adenoma. These patients were investigated for the preoperative localization by 99mTc-tetrofosmin scintigraphy. RESULTS: 99mTc-tetrofosmin imaging demonstrated focal uptake in 19 out of 20 patients with parathyroid adenoma. Two of the lesions were ectopic. US identified 17 parathyroid glands. CT and MRI initially detected 17 parathyroid glands. However, two additional parathyroid glands were localized on repeated CT and MRI in tandem with the results of the 99mTc-tetrofosmin imaging. Thus, the sensitivity and specificity of tetrofosmin imaging were 95% (19/20) and 95% (19/20); US, 85% (17/20) and 94% (16/17); initial CT, 85% (17/20) and 94% (16/17); and initial MRI, 88% (17/20) and 94% (16/17), respectively. The P/T uptake ratio at 2 hours after tetrofosmin injection was correlated with the serum concentration of intact PTH (rs=0.47, p<0.05) and the resected tumor weight (rs=0.53, p<0.05). CONCLUSION: 99mTc-tetrofosmin scintigraphy is useful for localization of parathyroid adenoma. Tetrofosmin uptake depends on the tumor weight and serum intact PTH levels.     

Acute pancreatitis caused by an ectopic mediastinal parathyroid adenoma

A 22-year-old man was admitted to our hospital because of epigastric pain. Blood tests showed leukocytosis (8940?cells/mm³) and increased serum amylase levels (787?IU/L); an abdominal computed tomography (CT) scan revealed an enlarged pancreas and peripancreatic fluid collection. On the basis of these findings, he was diagnosed with acute pancreatitis. Hypercalcemia (13.5?mg/dL) and increased levels of parathormone (>3200?pg/dL) were also detected using a high-sensitivity assay; we therefore considered hypercalcemia and primary hyperparathyroidism to be the possible causes of the acute pancreatitis. A ^99mTc-sestamibi scan showed accumulation of parathyroid tissue in the left mediastinum, and a tumor was noted on the left side of the aortic arch on a thoracic CT scan. Our final diagnosis was acute pancreatitis due to hypercalcemia induced by an ectopic mediastinal parathyroid adenoma. Ectopic parathyroid tumors can thus cause acute pancreatitis, and ^99mTc-sestamibi and CT scans are useful for their diagnosis and localization.     

Abnormal regional cerebral blood flow on 99mTc ECD brain SPECT in patients with primary Sjögren's syndrome and normal findings on brain magnetic resonance imaging

Objective: Technetium-99m ethyl cysteinate dimer (^99mTc ECD) single photon emission computed tomography (SPECT) of the brain was used to detect abnormal regional cerebral blood flow (rCBF) in patients with primary Sjögren''s syndrome (pSS) and normal findings on brain magnetic resonance imaging (MRI). Methods: ^99mTc ECD brain SPECT was performed to detect brain lesions showing hypoperfusion in 32 female patients with pSS and definite neuropsychiatric symptoms or signs. Seventeen female patients with pSS without neuropsychiatric symptoms and signs were included as a control group for comparison. All of the 49 patients with pSS had normal findings on brain MRI. Results: ^99mTc ECD brain SPECT showed brain regions with hypoperfusion in 18 (56.3%) of the 32 patients, and parietal lobes were the most common areas with such lesions. By contrast, ^99mTc ECD brain SPECT showed brain regions with hypoperfusion in only three (17.6%) of the 17 patients with pSS without neuropsychiatric symptoms or signs. Conclusion: This study suggests that ^99mTc ECD SPECT is a sensitive tool for detecting regions of hypoperfusion in the brains of patients with pSS and neuropsychiatric symptoms or signs and normal findings on brain MRI. However, a review of the literature showed that the ^99mTc ECD SPECT findings in patients with pSS were non-specific.     

Can SPECT change the surgical strategy in patients with primary hyperparathyroidism?

Primary hyperparathyroidism (PHPT) is the most common cause of hypercalcemia in outpatients. It is more common in females, after menopause, and the prevalence is 1 to 4:1000 in the general population. Patients with PHPT have abnormal regulation of PTH secretion, resulting in elevated serum calcium and inappropriately high or normal PTH in relation to the calcium value. Sporadic PTH-secreting adenoma alone accounts for 90% of cases of PHPT, while multiglandular hyperplasia is more common in familial hyperparathyroidism syndromes (5%) and parathyroid carcinomas represent less than 1% of cases. Only after making sure there is functional autonomy of one or more parathyroid glands, localization imaging tests should be performed to guide a possible surgical procedure. It is important to highlight that these tests have limitations and can yield false-positive and false-negative results. There are cases in which the parathyroid gland is difficult to be located, requiring a combination of imaging methods for pre-operative localization, such as (99m)Tc-pertechnetate, SPECT, SPECT/CT, and US. We describe the case of a 50-year-old female patient diagnosed with PHPT, who underwent a surgical procedure without success, with maintenance of hypercalcemia and hyperparathyroidism. In this case, the hyperfunctioning parathyroid was located in the retrotracheal region only after scintigraphy combined with SPECT/CT were used.     

Ultrasonographic features of intrathyroidal parathyroid adenoma causing primary hyperparathyroidism

Preoperative localization study is difficult in patients with primary hyperparathyroidism (PHPT) caused by intrathyroidal parathyroid adenoma. The objective of this study was to evaluate the usefulness of ultrasonography (US) in the diagnosis of intrathyroidal parathyroid adenoma. Between January 2004 and December 2009, seven of 373 patients who underwent parathyroidectomy because of PHPT in our hospital were found to have intrathyroidal parathyroid adenoma. The ultrasonographic features of intrathyroidal parathyroid adenoma were examined retrospectively. The most characteristic feature of intrathyroidal parathyroid adenoma was a hyperechoic line on the ventral surface of the parathyroid gland. A hyperechoic line was clearly detected even in small adenomas in which feeding vessels could not be detected on color Doppler sonography. In comparison with feeding vessels, a hyperechoic line was frequently detected in normally located parathyroid adenoma. (99m)Tc-sestamibi (MIBI) scintigraphy and computed tomography (CT) could show parathyroid adenoma in the intrathyroidal position in only three of five and in only one of three patients examined, respectively. Since a hyperechoic line is characteristic of parathyroid adenoma, an intrathyroidal parathyroid adenoma could be suspected by only non-invasive US.     

Measurement of porto‐systemic shunting in mice by novel three‐dimensional micro‐single photon emission computed tomography imaging enabling longitudinal follow‐up

Background and aims: The reference method for diagnosing porto‐systemic shunting (PSS) in experimental portal hypertension involves measuring ⁵¹Chrome (⁵¹Cr)‐labelled microspheres. Unfortunately, this technique necessitates the sacrifice of animals. Alternatively, ^99mtechnetium‐macroaggregated albumin (^99mTc‐MAA) has been used; however, planar scintigraphy imaging techniques are not quantitatively accurate and adequate spatial information is not attained. Here, we describe a reliable, minimally invasive and rapid in vivo imaging technique, using three‐dimensional single photon emission computed tomography (3D SPECT) modus, that allows more accurate quantification, serial measurements and spatial discrimination. Methodology: Partial portal vein ligation, common bile duct ligation and sham were induced in male mice. A mixture of ⁵¹Cr microspheres and ^99mTc‐macroaggregated albumin particles was injected into the splenic pulpa. All mice were scanned in vivo with μSPECT (1 mm spatial resolution) and, when mandatory for localisation, a μSPECT‐CT was acquired. A relative quantitative analysis was performed based on the 3D reconstructed datasets. Additionally, ⁵¹Cr was measured in the same animals to calculate the correlation coefficient between the ^99mTc detection and the gold standard ⁵¹Cr. In each measuring modality, the PSS fraction was calculated using the formula: [(lung counts)/(lung counts+liver counts)] × 100. Results: A significant correlation between the ^99mTc detection and ⁵¹Cr was demonstrated in partial portal vein ligation, common bile duct ligation and sham mice and there was a good agreement between the two modalities. μSPECT scanning delivers high spatial resolution and 3D image reconstructions. Conclusion: We have demonstrated that quantitative high‐resolution μSPECT imaging with ^99mTc‐MAA is useful for detecting the extent of PSS in a non‐sacrificing set‐up. This technology permits serial measurements and high‐throughput screening to detect baseline PSS, which is especially important in pharmacological studies.     

Importance of Heparin Provocation and SPECT/CT in Detecting Obscure Gastrointestinal Bleeding on 99mTc-RBC Scintigraphy: A Case Report

We presented a pediatric case with a history of intermittent melena for 3 years because of angiodyplasia of small intestine. The results of frequent upper gastrointestinal endoscopies and colonoscopies as well as both ^99mTc-red blood cell (RBC) and Meckel''s scintigraphies for several times were negative in detection of bleeding site. However, ^99mTc-RBC scintigraphy with single-photon emission computed tomography (SPECT)/computed tomography (CT) after heparin augmentation detected a site of bleeding in the distal ileum which later was confirmed during surgery with final diagnosis of angiodysplasia.It could be stated that heparin provocation of bleeding before ^99mTc-RBC scintigraphy accompanied by fused SPECT/CT images should be kept in mind for management of intestinal bleeding especially in difficult cases.     

Abnormal regional cerebral blood flow found by technetium-99m ethyl cysteinate dimer brain single photon emission computed tomography in systemic lupus erythematosus patients with normal brain MRI findings

In this study, technetium-^99m ethyl cysteinate dimer (^99mTc ECD) brain single photon emission computed tomography (SPECT) was used to detect regional cerebral blood flow (rCBF) of the brain in SLE patients with normal brain magnetic resonance imaging (MRI) findings. Twenty female SLE patients were enrolled in this study, divided into two groups. Group 1 consisted of 10 patients with neuropsychiatric manifestations. Group 2 consisted of 10 patients without neuropsychiatric manifestations. All patients had normal brain MRI findings. Another 10 SLE patients with abnormal MRI findings were included as group 3 for comparison. Meanwhile, 10 healthy female volunteers also underwent brain MRI and ^99mTc ECD brain SPECT for comparison. The scans revealed hypoperfusion lesions in 9/20 (45%) SLE patients, including 7/10 (70%) cases in group 1 and 2/10 (20%) cases in group 2. In contrast, all 10 patients (100%) in group 3 had abnormal ^99mTc ECD brain SPECT findings. The parietal lobes were the most commonly involved areas. We conclude that ^99mTc ECD brain SPECT is more sensitive for detecting rCBF changes than is brain MRI in detecting the brain anatomic changes, and may have a diagnostic value in lupus cerebral involvement. However, ^99mTc ECD brain SPECT may not be indicated for SLE patients with normal MRI and mild neuropsychiatric symptoms/signs, such headaches and dizziness. Received: 16 January 2002 / Accepted: 2 July 2002 Correspondence and offprint requests to: Dr Albert Kao, Departments of Nuclear Medicine and Medical Research, China Medical College Hospital, No. 2, Yuh-Der Road, Taichung 404, Taiwan. Tel: 886-4-22052121, ext. 3475; Fax: 886-4-22023442; E-mail: albertkaotw@yahoo.com.tw     

Usefulness of [99mTC]MIBI and [18F]fluorodeoxyglucose for imaging recurrent medullary thyroid cancer and hyperparathyroidism in MEN 2a syndrome

We report the case of a MEN 2a patient with a history of medullary thyroid cancer (MTC) treated by total thyroidectomy, who presented an increasing calcitonin level, suggesting tumor recurrence. Conventional radiographic and radionuclide imaging failed to localize the responsible lesions. A planar and tomographic (SPECT) [99mTc]MIBI scan, performed in order to investigate a recent hyperparathyroidism localized a parathyroid adenoma and revealed an abnormal uptake in the left lateral neck region, corresponding to apparently banal lymph nodes on MRI. This abnormal uptake was also observed on a [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) study and was proven to be an uptake in MTC lymph nodes metastases as confirmed by histopathologic analysis. We conclude that, using an adequate acquisition protocol (i.e. SPECT), [99mTc]MIBI scan is potentially able to localize both parathyroid adenoma and recurrent MTC at one and the same time, particularly in case of non-diagnostic conventional imaging techniques. In this setting, the potential usefulness of FDG-PET is also discussed.     

Attenuation-corrected 99mTc-tetrofosmin single-photon emission computed tomography in the detection of viable myocardium: comparison with positron emission tomography using 18F-fluorodeoxyglucose

Objectives. The purpose of this study was to assess the efficacy of attenuation-corrected (AC) technetium-99m (^99mTc)-tetrofosmin single-photon emission computed tomography (SPECT) in detecting viable myocardium compared to ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET).Background. The role of ^99mTc-labeled perfusion tracers in the assessment of myocardial viability remains controversial. Attenuation artifacts affect the diagnostic accuracy of SPECT images.Methods. Twenty-four patients with coronary artery disease (mean left ventricular ejection fraction 30%) underwent resting ^99mTc-tetrofosmin SPECT and FDG PET imaging. Both AC and non–attenuation-corrected (NC) SPECT images were generated.Results. Using a 50% threshold for viability by FDG PET, the percentage of concordant segments of viability between ^99mTc-tetrofosmin and FDG on the patient basis increased from 79.8% ± 14.0% (mean ± SD) on the NC images to 90.8% ± 10.6% on the AC images (p = 0.002). The percentage of ^99mTc-tetrofosmin defect segments within PET-viable segments, an estimate for the degree of underestimation of viability, decreased from 19.8% ± 15.2% on the NC images to 9.7% ± 12.6% on the AC images (p = 0.01). Similar results were obtained when a 60% threshold was used to define viability by FDG PET. When the anterior-lateral and inferior-septal regions were separately analyzed, the effect of attenuation correction was significant only in the inferior-septal region.Conclusions. The results indicate that AC ^99mTc-tetrofosmin SPECT improves the detection of viable myocardium mainly by decreasing the underestimation of viability particularly in the inferior-septal region, although some underestimation/overestimation of viability may still occur even with attenuation correction.     

Mediastinal Cystic Parathyroid Adenoma Diagnosed by Somatostatin Receptor Scintigraphy

A 71-year-old man complained of nausea and loss of appetite for eight months prior to admission. He was transported to a hospital with disorientation and diagnosed with primary hyperparathyroidism by laboratory examinations. However, ultrasonography, computed tomography, and technetium-99m labeled methoxyisobutyl isonitrile (^99mTc-MIBI) with single-photon emission computed tomography did not yield definite results. In contrast, somatostatin receptor scintigraphy successfully identified the lesion responsible for the over-secretion of parathyroid hormone within the middle mediastinum. The tumor was successfully resected by surgery, and a histopathological analysis confirmed the parathyroid adenoma nature of the tumor.     

Localising imaging in secondary hyperparathyroidism

Preoperative imaging has proved its use successful in the localization of solitary parathyroid adenomas in patients with suspected primary hyperparathyroidism. However, due to multiglandular disease at presentation patients with renal hyperparathyroidism need to be analyzed separately, making the usefulness of imaging techniques controversial. Recently, improved methods of functional imaging like parathyroid scan with 99mTc-sestamibi or positron emission tomography, especially when combined with computed tomography, can provide additional quantitative and qualitative information that has yet to be assessed. Nuclear medicine procedures could prove useful not only in preoperative diagnosis, but also in the selection of medical or surgical therapeutic alternatives in secondary hyperparathyroidism patients. There is evidence that 99mTc-sestamibi uptake in parathyroid hyperplasia or adenoma is related to biochemical markers of parathyroid function. We are only beginning to identify the factors involved in radiotracer uptake by parathyroid cells and how it can be modulated to obtain more accurate results. This review analyzes the current use of non-invasive imaging modalities in patients with secondary hyperparathyroidism, taking into account the latest trends in the field combining anatomic and functional modalities and the relevant factors linked to radiotracer uptake in abnormal hyperfunctioning parathyroid glands.     

Localization of parathyroid tumors using endoscopic ultrasonography in primary hyperparathyroidism

Parathyroid adenomas responsible for primary hyperparathyroidism may be difficult to detect preoperatively. Furthermore parathyroid adenomas may arise behind the (nodular) thyroid gland, in a deep cervical location, and plans should be plane. The purpose of the present prospective study was to evaluate echoendoscopy, and to compare its accuracy to that of non invasive tests. Fourteen consecutive patients with primary hyperparathyroidism were prospectively studied. All patients underwent echoendoscopy, ultrasonography (US), CT scanning or magnetic resonance imaging (MRI) and Tc 99m sestamibi scanning before undergoing initial neck exploration. The parathyroid pathology was a solitary adenoma in 13 patients and a 4 glands hyperplasia in one. All tests were corroborating in 5 cases. Four adenomas were localized to the correc tside (33%), and no test accurately localized all hyperplastic glands. EUS, sestamibi and CT scanning or MRI correctly identified 10 parathyroid tumors in 14 cases (71%). US correctly localized only 5 adenomas (sensitivity 36%). The sensitivity of EUS to detect parathyroid adenomas is superior to US (p<0.05) and comparable to that of other non invasive tests. We conclude that EUS may be an useful tool to localize parathyroid lesions. This method may replace US prior to initial neck exploration with further miniaturization of probes, or find an intermediate place among invasive and noninvasive preoperative localization procedures in patients with persistent or recurrent PHPT.     

原发性甲状旁腺功能亢进的核素定位诊断

应了~（99m）Tc-MIBI进行了甲状旁腺显像,并对方法学进行了探讨。10例患者经临床、生化确诊为原发甲旁亢,但均未触及增大的甲状旁腺或甲状腺。其中7例在应用~（99m）Tc-MIBI和~（99m）Tc两种示踪剂分别进行甲状旁腺显像和甲状腺显像,3例仅用~（99m）Tc-MIBI,但在显像过程中给予了过氯酸盐。在静泳注射~（99m）Tc-MIBI后不同时间采集图象并选用产P/T值（甲状旁腺计数/甲状腺计数）做参数,以了解示踪剂的代谢及确定最佳显像时间。10例患者经手术共摘除12枚肿大的甲状旁腺,病理证实10枚为甲状旁腺腺瘤,2枝为甲状旁腺增生,B超检查9例中发现2枚腺瘤,CT检查8例共发现3枚腺瘤,核素显像10例患者各发现腺瘤一个,其阳性部位与手术所见完全吻合。尽管例数较少,但初步看,此方法简便、准确,对于原发甲旁亢的定位诊断确有临床价值。