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Aim: The aim of the study was to evaluate the clinical role or [(99m)Tc]MIBI SPECT in selecting primary hyperparathyroid (PHPT) patients for minimally invasive radioguided surgery (MIRS)., Methods: One hundred and forty-one consecutive PHPT patients were studied by a single-session [(99m)Tc]Percethnetate/[(99m)Tc]MIBI subtraction scintigraphy, followed by [(99m)Tc]MIBI SPECT in order to localize hyperfunctioning parathyroid adenoma (PA) and plan the surgical approach., Results: A solitary PA was depicted at preoperative scintigraphy in 135 of 141 patients (95.7%), two or more PA in 5 patients, and was negative in 6 patients (4.3%). In 27 patients, the PA was located deep in the paraesophageal/paratracheal space. One hundred and twenty-four patients (in 18 of them the PA was located deeply in the neck) underwent successful MIRS using the low 37 MBq (1 mCi) [(99m)Tc]MIBI dose protocol. Intraoperative quick parathyroid hormone (QPTH) assay demonstrated a fall >50% in respect to the baseline value in all patients, confirming successful parathyroidectomy. After a follow-up of 6 to 37 months (median 18 months), no case of persistent/recurrent PHPT was recorded. When comparing the parathyroid to background (P/B) ratio measured at planar and SPECT preoperative scintigraphy with that measured intraoperatively with the gamma probe, a significant linear correlation was found between the SPECT and intraoperative gamma probe measurements (r = 0.91; P <0.01) while no correlation was found with planar scintigraphic data., Conclusions: Our data suggest that the P/B ratio calculated by means of [(99m)Tc]MIBI SPECT is more accurate in predicting the intraoperative measurements with the intraoperative gamma probe. Thus, a preoperative [(99m)Tc]MIBI SPECT acquisition should be recommended for a better selection of PHPT patients to offer MIRS.

In the last 10 to 15 years surgery of primary hyperparathyroidism (PHPT) moved from the wide bilateral neck exploration to various types of limited neck exploration ranging from unilateral neck surgery to minimally invasive approaches as the minimally invasive radioguided parathyroidectomy. In contrast with the bilateral neck exploration, an accurate preoperative localizing imaging, which is mainly based on (99m)TC-sestamibi scintigraphy, is mandatory when planning a concise parathyroidectomy. Following imaging criteria, only a fraction of PHPT patients accounting for approximately 60% to 70% of all PHPT patients can be eligible for a minimally invasive parathyroidectomy. Only PHPT patients with a high probability to be affected by a solitary parathyroid adenoma showing a high (99m)TC-sestamibi uptake and with a normal thyroid gland should be offer a minimally invasive radioguided parathyroidectomy. The (99m)TC-sestamibi SPECT technique and the double-tracer 123-iodine or (99m)TC-pertecnetate/(99m)TC-sestamibi scintigraphic technique are the most sensitive and accurate preoperative imaging modalities and their utilization is recommended when considering a minimally invasive radioguided parathyroidectomy. Two main intraoperative procedures for the minimally invasive radioguided surgery have been described: the single-day protocol and the different-day protocol. In the single-day protocol a 740 MBq dose of (99m)TC-sestamibi is injected to the patient, scintigraphic imaging is obtained by dual-phase technique and then the patient is operated on within approximately 3 hours from radio-tracer injection. In the different-day protocol, a double-tracer parathyroid scintigraphy is obtained some days before surgery with the aim of better planning the type and extension of intervention. The day of intervention, for the purpose of radioguided surgery only, a low 37 MBq dose of (99m)TC-sestamibi is injected to the patient in the operating theatre a few minutes before the start of intervention. The main advantages of minimally invasive radioguided parathyroidectomy over the traditional wide bilateral neck exploration can be resumed as follows: a shortening in the operating and recovery time, possibility of local anesthesia, possibility of ambulatory surgery or same-day discharge, less postsurgical hypocalcemia, less postsurgical pain, favourable cosmetic results, benefits from a cost-analysis point of view.

Purpose: The prevalence of ectopic parathyroid adenoma (PA) is relatively low, despite some studies in which it has been reported to be as high as 20%. Ectopic PA is a frequent cause of surgical failure, and therefore some authors recommend preoperative imaging to localize the condition in patients with primary hyperparathyroid (HPT) disease before initial surgery., Methods: Two unusual cases of primary HPT caused by an ectopic PA located at the carotid bifurcation are reported. The patients were examined before operation using Tc-99m MIBI scintigraphy and then underwent radioguided surgery using the intraoperative gamma probe technique with injection of a low dose (37 MBq; 1 mCi) of Tc-99m MIBI., Results: The first patient had a history of primary HPT and coexisting multinodular goiter. She had undergone total thyroidectomy in another center, but no enlarged parathyroid gland was found at bilateral neck exploration and serum calcium and parathyroid hormone levels remained elevated after intervention. The patient was referred to our center. A Tc-99m MIBI scan showed a focus of abnormal tracer uptake in the superior left laterocervical region that was thought to be a PA. The next day she underwent radioguided surgery and an 18-mm PA located at the left carotid bifurcation was easily removed through a 2.5-cm skin incision. The second patient was examined in our center before surgery. A neck ultrasound showed a multinodular goiter but no enlarged parathyroid glands. A pertechnectate-MIBI subtraction scan revealed a focus of abnormal Tc-99m MIBI uptake in the right superior laterocervical region that was thought to be a PA. One week later, at radioguided surgery, a 25-mm PA was identified at the right carotid bifurcation and removed successfully., Conclusions: These data strongly support the utility of preoperative imaging with Tc-99m MIBI in patients with primary HPT before initial neck exploration with the aim of avoiding surgical failure. Furthermore, the intraoperative gamma probe technique seems to be useful to reduce surgical trauma and, possibly, complications in patients with ectopic PA.

Background: The contribution of nuclear-medical mapping using 99mTc-MIBI (MIBI) and the use of an intraoperative probe in primary hyperparathyroidism (I degrees HPT) surgery was evaluated prospectively in a series of patients undergoing parathyroidectomy., Methods: Fifty-four patients, who were operated between May 1999 and July 2000, under-went a systematic preoperative evaluation using scintigraphy with a dual tracer 99Tc04/MIBI and image subtraction, and high-resolution neck ecotomography. Surgery was performed using a mini-invasive technique through an incision measuring 2-2.5 cm at the base of the neck in 46 patients; the other 8 patients underwent open surgery with bilateral exploration of the neck. MIBI was injected intravenously in the operating theatre following the induction of anesthesia and after 32 minutes on average, radioactivity was measured using a manual gamma probe. Radioactivity was also counted intraoperatively at the tip of the lung contralateral to the pathological gland, a parameter used as the base activity (B), in the presumed seat of the hyperfunctioning parathyroid (P), in correspondence with healthy thyroid tissue (T) and any associated thyroid nodes (N). Radioactivity was also recorded at the level of the empty parathyroid compartment after removal of the corresponding gland, and on the parathyroid removed ex vivo ., Results: The ratio between the three main parameters, T/B, P/B and P/T was respectively 1.6 (range=1.5 - 1.8), 2.7 (range=1.6-4.0) and 1.6 (range=1.1-2.8). In 4 cases (7.4%), the small size of the parathyroids, adjacent to thyroid nodes, meant that the parathyroid measurement of MIBI was smaller than the thyroid measurement. The histological finding was consistent with: single parathyroid adenoma in 49 cases, multiple adenomas in 3 cases, parathyroid carcinoma in 2 cases. Rapid intraoperative PTH normalised in all patients., Conclusions: The significant difference in radioactivity levels recorded in the patients, showed that the technique is useful to the surgeon as a means of intraoperative assay for hyperfunctioning parathyroids, even if it cannot obviously replace experience or the value of preoperative scientigraphic and ecotomographic imaging.

The authors report three cases of primary hyperparathyroidism (HPT) in patients with differentiated thyroid carcinoma (DTC) developed a few years after initial surgical and radiometabolic treatment of DTC. The early diagnosis of HPT in these patients was made possible because of laboratory tests performed during follow-up, including the assay of serum calcium and serum phosphorus levels. Scinti-graphy using 99mTc-MIBI enabled the correct preoperative localisation of a single parathyroid adenoma in two of these patients and multiglandular pathology in the third.

Two cases of papillary thyroid carcinoma coexisting with a parathyroid adenoma are reported. A double-tracer pertechnetate-MIBI subtraction scan combined with neck ultrasound correctly visualized the site of the parathyroid adenoma despite the presence of thyroid nodule(s) located in the opposite thyroid lobe in one case and in both thyroid lobes in the other case. In both patients, the papillary thyroid carcinoma was cold with Tc-99m pertechnetate and hot with MIBI. Total thyroidectomy and parathyroidectomy of a solitary parathyroid adenoma were performed in both patients. Pertechnetate-MIBI subtraction scanning associated with neck ultrasound appears to be a useful imaging technique to detect parathyroid adenoma before operation in patients with concomitant thyroid nodular disease. A MIBI-hot and Tc-99m pertechnetate-cold thyroid nodule can indicate the possible presence of a malignant lesion.

We report the preliminary results obtained with the intraoperative MIBI-guided gamma probe in a group of 9 patients with primary hyperparathyroidism (pHPT). These patients were selected for limited invasive parathyroid surgery on the basis of a preoperative imaging protocol consisting of a pertechnetate & perchlorate/MIBI scan combined with neck ultrasonography (US). In the operating room 50-70 MBq MIBI was injected 30 to 45 min before parathyroidectomy. The radioactivity was measured intraoperatively at three sites: parathyroid (P), thyroid (T), and background (B). The P/B, P/T, and T/B ratios were calculated. The T/B ratio was relatively constant (range, 1.5-1.8; mean, 1.6), while a wide variability was observed both for P/T ratio (range, 1.2-2.3; mean, 1.7) and P/B ratio (range, 2.1-4.0; mean, 2.9). At surgery single enlarged parathyroid glands were easily identified by means of intraoperative MIBI-guided gamma probe. Moreover, the gamma probe allowed us to perform a limited 2-2.5 cm neck incision in eight patients affected by parathyroid adenoma. In the remaining patient a parathyroid carcinoma was diagnosed and a bilateral neck exploration was performed. The intraoperative MIBI gamma probe seems to be a useful aid when limited invasive parathyroid surgery is performed.

We have compared prospectively the sensitivity, specificity and accuracy of CT and MRI in a series of 27 consecutive patients (age 23-76 yrs, 17 females, 10 males) with clinically suspected primary aldosteronism. We found 13 patients with a unilateral aldosterone-producing adenoma (11 on the left and 2 on the right side), 6 with idiopathic hyper-aldosteronism and 8 with primary hypertension, which in two cases was associated with a nonfunctioning adrenal adenoma. The diagnosis of aldosterone-producing adenoma was confirmed at surgery and pathology in all cases. Idiopathic hyper-aldosteronism was diagnosed on the basis of the results of dexamethasone-suppressed adrenal scintigraphy and/or selective adrenal vein sampling. MRI correctly identified all cases of aldosterone-producing adenoma, but gave false positive results in five cases: one had idiopathic hyper-aldosteronism with bilateral nodular hyperplasia and four primary hypertension, which in two patients was associated with a nonfunctioning adrenal adenoma. Therefore, the sensitivity of MRI was 100%, its specificity 64% and overall diagnostic accuracy 81%. In comparison, CT correctly recognized only eight of the 13 patients with aldosterone-producing adenoma and gave false positive results in three primary hypertensives, including the two patients with a nonfunctioning adrenal adenoma. Therefore, its sensitivity, specificity and accuracy were 62, 77 and 69%, respectively. Based on these results, it could be anticipated that about four of every ten patients with aldosterone-producing adenoma would not be correctly diagnosed by CT.(ABSTRACT TRUNCATED AT 250 WORDS)

Surgical thyroid sections from 30 papillary carcinomas (PC), six medullary carcinomas (MC), three anaplastic carcinomas (AC), two follicular carcinomas (FC), and 16 adenomas (AD) were examined with an indirect immunofluorescence technique employing different monoclonal antibodies to evaluate the expression of human leukocyte antigen (HLA)-A, B, C (Class I) and DR, DP, DQ (Class II) by thyrocytes, together with the phenotype and distribution of inflammatory cells. Ten PC and four FC were also investigated for the presence of intercellular adhesion molecule-1 (ICAM-1). In situ deposits of immunocomplexes and circulating thyroid autoantibodies were also evaluated. An increased expression of Class I antigens was found in all PC and FC, in 33% of MC and AC, and in 31% of AD. An anomalous expression of Class II antigens was observed in 70% of PC, in 50% of FC, in 33% of AC, in 19% of AD, and in none of the MC. Expression of DP or DQ was revealed only in a portion of the DR-positive glands. A reduction of microsomal autoantigen expression was found. No ICAM-1-positive thyrocytes were detected. A moderate T-lymphocytic infiltrate was noticed only in PC, where it was correlated with DR and DP and/or DQ coexpression. B-cells and natural killer cells were virtually absent. The authors speculate that the weak Class II antigens expression, together with the partial or complete loss in microsomal autoantigen and the absence of ICAM-1 by thyrocytes, may account for the limited engagement of immunocompetent cells observed in thyroid tumors.