Is there a future for adrenal scintigraphy?
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Adrenal Gland Diseases↗
Biomedical subjects
D Rubello
Publications and source records attributed to D Rubello.
Recent advances in preoperative and intraoperative nuclear medicine procedures in patients with primary hyperparathyroidism.
Although bilateral neck exploration is traditionally considered as the treatment of choice in patients with primary hyperparathyroidism (HPT), several surgical techniques of limited neck exploration have been proposed over the last 10 years in primary HPT patients with a high probability to be affected by a solitary parathyroid adenoma. The availability in recent years of highly sensitive and accurate preoperative imaging modalities, particularly the parathyroid scintigraphy with 99mTc-MIBI and high resolution neck ultrasonography, allowed to increase the rate of primary HPT patients as candidates to a selective parathyroidectomy. One of the most innovative techniques for limited surgery is the minimally invasive radio-guided parathyroidectomy that is based on the intraoperative detection of the parathyroid adenoma under the guidance of a gamma probe allowing the removal of the parathyroid adenoma through a small 2-cm skin incision. However, if a minimally invasive parathyroidectomy is taken into consideration, accurate preoperative imaging is mandatory not only to distinguish patients with a solitary parathyroid adenoma from those with multi-glandular disease but also to diagnose patients with concomitant thyroid nodule(s) that can cause false-positive results at radio-guided surgery. In the present study the most recent advances reached with preoperative localizing imaging of parathyroid adenomas are reviewed and the techniques proposed to perform a minimally invasive radio-guided surgery are discussed with particular regard to the therapeutic efficacy and cost-effectiveness analysis.
Humans↗
Clinical role of positron emission tomography (PET) in endocrine tumours.
Positron emission tomography (PET) is considered one of the most effective nuclear medicine imaging modality in oncology. In many types of malignant tumours PET has proven to be high sensitive in detecting both primary neoplasm and metastatic disease both before therapy for staging purposes and after surgery, radiotherapy and chemotherapy during follow-up. In particular, PET showed high accuracy in differentiating post-treatment scar from viable tumoural tissue and high sensitivity in visualising very small metastatic foci as those in normal-sized (less than 1 cm in diameter) lymph nodes. A large variety of positron emitter tracers have been produced for PET imaging: the most widely used tracer in clinical oncology is 18F-fluoro-2-deoxy-D-glucose (18F-FDG). Deoxy-glucose (DG) is a glucose analog that enters the cell using specific transmenbrane carrier proteins (especially GLUT-1). Once within the cytoplasm, DG is phosphorylated to FG-6-phosphate but does not appear to be further metabolised. In most malignant tumours there is an increase of the glycolityc metabolism which accounts for an increase of the FDG uptake. However, the metabolic cellular activity can be only slightly increased or even normal in well differentiated and slow growing tumours as some endocrine neoplasms. In the present review, the clinical usefulness and limits of PET imaging are discussed in the management of patients with endocrine tumors.
Adrenal Gland Neoplasms↗
New trends in parathyroid scintigraphy.
The paper focusses on the recent advances in parathyroid imaging in both diagnostic and surgical fields which justify the present favourable trend towards a considerable expansion of nuclear medicine applications in this area. The main methodological advances in parathyroid scintigraphy are the rebirth of the dual-tracer (subtraction) technique with technetium-99m sestamibi, the possibility of also using 99mTc-tetrofosmin within a dual-tracer (subtraction) methodology and the more extensive use of single-photon emission tomography, which the authors believe will become the standard methodology. The indications for parathyroid scintigraphy have been affected by advances in hyperparathyroidism surgery, including wider use of unilateral neck exploration and of minimally invasive radioguided surgery. As these techniques can only be performed in hyperparathyroid patients with a single adenoma, careful pre-operative assessment is required, and parathyroid scintigraphy undoubtedly is the most accurate localisation method. To date, the majority of papers have also demonstrated the cost-effectiveness of scintigraphically guided limited neck surgery. The authors conclude that: (1) parathyroid scintigraphy can be recommended not only in persistent or recurrent hyperparathyroidism but also in hyperparathyroid patients prior to first surgery; (2) scintigraphy should always be performed by applying the most accurate technique available because reliable scintigraphy gains or reinforces the surgeon's trust, reliably guides cost-effective operative strategies and justifies the recognition of new potential diagnostic indications.
Adenoma↗
Ectopic parathyroid adenomas located at the carotid bifurcation: the role of preoperative Tc-99m MIBI scintigraphy and the intraoperative gamma probe procedure in surgical treatment planning.
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.
Adenoma↗
[The role of scintigraphy with dual tracer and potassium perchlorate (99mTcO4 & KClO4/ MIBI) in primary hyperparathyroidism].
BACKGROUND: The diagnostic value of scintigraphy using a dual tracer and high-resolution neck ecotomography in the preoperative localisation of parathyroid enlargements was evaluated in a group of consecutive patients suffering from primary hyperparathyroidism (HPT) who were uniformly studied and subsequently operated by the same surgical team. METHODS: Scintigraphic imaging and high-resolution neck ecotomography were carried out in a single session on 143 patients. Scintigraphic imaging was performed using a dual tracer, 99mTc-pertechnetate/99mTc-MIBI), modified by the addition of potassium perchlorate (KCL04) to achieve a rapid washout of 99mTc04 from the thyroid and, consequently, to achieve good quality and rapid MIBI images. In a limited number of patients (21 cases) SPECT was also performed. Limited surgery was planned in patients with evidence of single parathyroid lesions and with normal thyroid parameters, in the form of either unilateral or with mini-invasive surgery (91 cases). Patients with eco-scintigraphic evidence of multiglandular parathyroid pathology or the coexistence of a nodular thyroid goitre, or in patients suffering from MEN or familial HPT, or lastly those with negative eco-scintigraphic results under-went more extensive surgery with bilateral exploration of the neck (52 cases). A single parathyroid lesion was diagnosed during surgery in 90 out of 91 patients undergoing planned unilateral or mini-invasive exploration of the neck. Therefore, in our experience, the predictive value of preoperative imaging as a mean of identifying single parathyroid lesions was 98.9% with a clear impact on the choice of conservative surgery. After the removal of the parathyroid to which preoperative imaging referred, it was only necessary in one patient to extend surgical exploration to the other side of the neck to remove another enlarged parathyroid owing to persistent high PTH. RESULTS: The sensitivity of scintigraphy and high-resolution neck ecotomography in pa-tients with a single adenoma was 94% and 83.7% respectively, whereas it was 76.9% and 64.5% respectively in the group of patients with multiglandular pathology. It is worth underlining that in all 31 patients with associated nodular thyroid pathology, the evaluation of thyroid scintigraphic imaging using 99mTc04 and high-resolution neck ecotomography enabled the preoperative diagnosis of thyroid pathology, therefore guiding the surgeon towards more extensive surgery. SPECT enabled the parathyroid adenoma to be correctly localised in a deep site in 5 patients, in the neck in 3 cases and at the mediastinum in 2 patients, providing additional data that helped the surgeon to plan surgery. CONCLUSIONS: In conclusion, in our experience: a) an integrated diagnostic approach based on scintigraphy 99mTc04 & KCLO4/MIBI and high-resolution neck ecotomography was an extremely accurate mean of identifying patients with single parathyroid lesions before surgery, enabling them to undergo limited surgery, b) scintigraphy with a dual tracer might be the elective methods for studying patients with HPT because it allows the contemporary diagnosis of possible thyroid diseases. This aspect is extremely important in geographical areas with a high predominance of nodular thyroid pathology, c) SPECT scintigraphic analysis may be useful in some patients with suspected parathyroid adenoma localised in a deep seat, allowing a more precise identification of the latter and better surgical planning.
Adenoma↗
[Parathyroid carcinoma. Therapeutic strategies derived from 20 years of experience].
BACKGROUND: Carcinoma of the parathyroid is a rare endocrine tumour which can be difficult to diagnose even for expert anatomopathologists. METHODS: A retrospective study was carried out on all the cases of parathyroid pathology observed between January 1980 and October 2000: parathyroid carcinoma was diagnosed in 17 (3.59%) out of 478 patients treated for hyperparathyroidism. We describe their clinical presentation, treatment and results obtained. The patients included 9 women and 8 men, with a male/female ratio of 1.14 and a mean age at diagnosis of 56.9 years (range 30-83). All the patients, except one, the only non-secreting case, presented hypercalcemia, and 10 patients presented serum calcium levels above 3 mmol/L. The symptoms at onset included: nephrolithiasis in 10 cases, osteoporosis in 4 (3 of which presented uremic syndromes), gastrointestinal symptoms (gastritis) in 1 case, a palpable cervical mass in 1 patient and recurrent nerve palsy in one case suffering from familial IPT. A variety of imaging techniques were used for the preoperative localisation: high-resolution ultrasonography of the neck was carried out in all 17 patients and was positive in 15 cases; scintigraphy (99mTcO4/201Tl or 99mO4/MIBI) was carried out in 16 patients and was positive in 14; CAT was positive in 6 out of 17 patients. Three patients underwent the first operation in another hospital and were referred to our department for resistance or recidive. Initial surgery was restricted to simple parathyroidectomy in 4 cases; parathyroidectomy was extended to the entire gland in 3 patients with uremic syndrome and to the ipsilateral thyroid lobe in 7 cases. Three patients underwent parathyroidectomy extended en bloc to the adjacent structures, and recurrent lymph node dissection was also performed in 2 of these patients. Lymph node involvement was never demonstrated during the first operation. The dimensions of the tumour varied from 1 to 6.7 cm; we found signs of invasion of the neighbouring structures in 3 patients. RESULTS: Parathyroid carcinoma was correctly diagnosed during the first operation in 14 cases (this diagnosis was suspected in 10 cases following intraoperative frozen session), whereas the first diagnosis was of benign disease in 3 patients. Blood levels of calcium, phosphorus and PTH returned to normal after the first operation in 13 patients. These values diminished, but did not return to normal in 2 cases. Two patients relapsed, respectively 5 and 175 months after the first operation. A total of 10 reoperations were performed in 4 patients with persistent/recurrent symptoms (from a minimum of 1 to a maximum of 4). Recidive presented characteristics of local invasiveness in one case and the persistence was supported by micro-insemination of the pre-thyroid compartment and muscles in another two cases. At reoperation, lymph node metastasis was associated with local recidive only in one case. Two patients underwent radiotherapy after surgery and one received chemotherapy. At the last check-up (October 2000), 14 patients were alive and disease-free (82.25%). Two presented slight persistent hypercalcemia (with values ranging between 2.65 and 2.80 mmol/L), but without any macroscopic localisation of disease (11.76%). Only 1 patient died (5.88%) (one year after the first operation and 7 months after the last one). Death was caused by uncontrollable hypercalcemia supported by widespread metastasis to the bones and lungs. The 5 and 10-year survival rates were calculated as 94.12%. CONCLUSIONS: In conclusion, high blood levels of calcium and PTH, a palpable mass at the neck, with recurrent nerve paralysis, aspects of local invasiveness should alert the surgeon and guide him towards surgery that includes resection of the parathyroid en bloc with the adjacent structures, although there is no proof that a more extensive surgery is correlated with a more favourable prognosis. Being the majority of recidive functional, monitoring serum calcium and PTH levels offers a useful market which precedes their macroscopic demonstration.
Adult↗
[Primary hyperparathyroidism in patients treated for non-medullary thyroid carcinoma].
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.
Adenocarcinoma, Follicular↗
[Radio-guided parathyroidectomy. A prospective study in 54 patients with primary hyperparathyroidism].
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.
Adenoma↗
Parathyroid carcinoma. A concise review.
Parathyroid carcinoma is a very rare malignancy and the least common among endocrine malignat tumors. Its etiology is still unclear and some hypotheses have been suggested: previous external radiation to the neck, pregression from benign to malignant lesion, familial hyperparathyroidism. An early accurate diagnosis is very important since surgery is the most effective therapeutic approach to parathyroid carcinoma. Prognosis is quite variable and stress is laid on the early diagnosis and radical surgery which seem to be most favorable prognostic factors. An accurate follow-up should include frequent measurements of serum calcium and PTH levels to promptly detect recurrence or metastases which are usually associated with severe hyeprcalcemia.
Carcinoma↗
Clinical role of 99mTcO4/MIBI scan, ultrasound and intra-operative gamma probe in the performance of unilateral and minimally invasive surgery in primary hyperparathyroidism.
The main purposes of this study were: (a) to investigate the efficacy of an imaging protocol based on the combination of 99mTcO4/MIBI scintigraphy and neck ultrasound (US) in selecting patients with primary hyperparathyroidism (HPT) for unilateral neck exploration, and (b) to help define the role of the intraoperative MIBI gamma probe (IMGP) technique in the performance of minimally invasive radio-guided surgery (MIRS). One hundred and forty-three consecutive patients with primary HPT were enrolled in the study. We used a modified 99mTcO4/MIBI scintigraphic procedure which included the oral administration of potassium perchlorate to cause rapid 99mTcO4 washout from the thyroid tissue, thereby permitting the acquisition of high-quality early MIBI images. A single-photon emission tomography (SPET) acquisition was also obtained in 21 patients, of whom seven had an enlarged parathyroid gland (EPG) in the mediastinum at planar scintigraphy and 14 had discordant scan/US findings for the presence of a cervical EPG. Neck US was performed in the same session as scintigraphy using a small-parts, high-resolution 10-MHz transducer. All patients were then operated on by the same surgical team. Quick PTH assay (QPTH) was used to measure PTH intraoperatively to confirm successful parathyroidectomy. In patients with scan/US evidence of a solitary EPG and with a normal thyroid gland, limited, unilateral neck surgery or, more recently, MIRS was planned (n=91). In patients with scan/US evidence of multiglandular disease (MGD) (n=21) or concomitant nodular goitre (n=24) or in patients with a negative scan/US evaluation (n=7), extensive bilateral neck exploration was planned (n=52). In 87 of the 91 patients (95.6%) in whom preoperative imaging indicated the presence of a solitary EPG and a normal thyroid gland, a single parathyroid adenoma was found at surgery, and these patients were treated by unilateral neck exploration or MIRS. In the remaining four patients of this group, conversion to bilateral neck exploration was required because parathyroid carcinoma (n=3) or MGD (n=1) was diagnosed at operation. In some cases SPET was helpful in better localising the EPG. In particular, in 5 of the 21 patients evaluated, SPET localised an EPG deep in the neck or mediastinum and at surgery a parathyroid adenoma was found in the paratracheal or para-oesophageal space. In 43 of the 46 patients (93.5%) who were candidates for MIRS, the IMGP technique allowed parathyroidectomy to be performed through a small, 2- to 2.5-cm skin incision with a short duration of intervention (mean 34 min). We conclude that: (a) The integrated scan/US imaging protocol that we used appears to be accurate in selecting patients with primary HPT for unilateral neck exploration. (b) In our series the most prevalent cause of bilateral neck exploration was the co-existence of a nodular goitre; thus accurate preoperative evaluation of the thyroid gland by dual-tracer scintigraphy and US imaging is strongly recommended in all patients with HPT. (c) SPET can provide the surgeon with useful information when an EPG is located deep in the neck or mediastinum. (d) IMGP appears to be a useful intraoperative device in HPT patients with solitary parathyroid adenomas and a normal thyroid gland, since it permits minimally invasive and time-saving surgery.
Adenoma↗
99mTc-MIBI radio-guided minimally invasive parathyroid surgery planned on the basis of a preoperative combined 99mTc-pertechnetate/99mTc-MIBI and ultrasound imaging protocol.
The aims of this study were: (a) to define the accuracy of a preoperative parathyroid imaging protocol based on the combination of technetium-99m pertechnetate/technetium-99m methoxyisobutylisonitrile (99mTcO4/ 99mTc-MIBI) scan and neck ultrasound (US) in selecting patients with primary hyperparathyroidism (pHPT) eligible for a limited neck exploration, and (b) to investigate the potential role of the intraoperative gamma probe (IGP) in radio-guided minimally invasive surgery. 99mTcO4/99mTc-MIBI subtraction scan was performed by means of potassium perchlorate administration with the aim of effecting rapid 99mTcO4 wash-out from the thyroid. Minimally invasive surgery using an IGP was commenced some minutes following the injection of a low, 70 MBq, 99mTc-MIBI dose. Intraoperative PTH (i-PTH) was measured. On the basis of preoperative imaging, 21 pHPT consecutive patients were selected for a limited neck dissection. In 18 of them, a single parathyroid adenoma was found at surgery and IGP allowed performance of parathyroidectomy through a small, 2-2.5 cm, skin incision with a relatively short surgical duration (mean 38 min). i-PTH rapidly normalised in all cases. In two patients, a parathyroid carcinoma was diagnosed at surgery; consequently, a wide neck exploration associated with a near-total thyroidectomy was performed. No loco-regional metastatic lesions were found and i-PTH rapidly normalised after carcinoma excision. In one patient, i-PTH remained elevated after removal of the enlarged parathyroid gland which was localised by 99mTcO4/99mTc-MIBI scan and US. A bilateral exploration was needed to remove a contralateral enlarged parathyroid gland. Combined, 99mTcO4/99mTc-MIBI scan and US imaging correctly localised a single parathyroid gland in 20/21 patients (95.2%); thus, this protocol appears to be accurate enough for the preoperative selection of pHPT patients eligible for limited neck surgery. Moreover, in these selected patients the IGP seems to be helpful in performing radio-guided minimally invasive surgery.
Adult↗
The role of technetium-99m methoxyisobutylisonitrile scintigraphy in the planning of therapy and follow-up of patients with differentiated thyroid carcinoma after surgery.
The aim of this study was to investigate the possible role of technetium-99m methoxyisobutylisonitrile (MIBI) scan in planning post-surgical therapy and follow-up in patients with differentiated thyroid carcinoma (DTC). Four groups of DTC patients were considered: Group 1 comprised 122 patients with high serum thyroglobulin (s-Tg) levels and negative high-dose iodine-131 scan during follow-up who had previously undergone total thyroidectomy and 131I treatment. Group 2 consisted of 27 patients who had previously undergone total thyroidectomy and 131I treatment but were now considered disease-free; this group was considered as controls. Group 3 comprised 49 patients studied after total thyroidectomy but prior to 131I scan. Finally, group 4 consisted of 21 patients who had previously undergone partial thyroidectomy alone. MIBI scan, neck ultrasonography (US), and s-Tg measurements during suppressive hormonal therapy (SHT) were obtained in all patients. Neck and chest computed tomography (CT) or magnetic resonance imaging (MRI) was also performed in group 1 patients. In group 1, MIBI scan and US were very sensitive in detecting cervical lymph node metastases (93.54% and 89.24%, respectively). Furthermore, MIBI scan and US played a complementary role in several patients, yielding a global sensitivity of 97.84%. In contrast, CT/MRI sensitivity for cervical lymph node metastases was very low (43.01%). MIBI scan also showed a higher sensitivity than CT/MRI in detecting mediastinal lymph node metastases (100% vs 57.89%). Regarding distant metastases, MIBI scan provided results similar to those of conventional imaging (CT, MRI, 99mTc-methylene diphosphonate bone scan). In group 2, no false-positive cases were observed with MIBI scan (100% specificity). In group 3, MIBI scan correctly identified all the 131I-positive metastatic foci, except in two patients with micronodular pulmonary metastases that were visualised with 131I scan. In contrast, both MIBI scan and US showed low sensitivity (46.15% and 61.53%, respectively) compared with 131I scan in detecting thyroid remnants. s-Tg was increased in all patients with distant metastases but only in 56% of those with lymph node metastases. Furthermore, s-Tg was increased in 21.42% of patients with thyroid remnants alone (false-positive results). In group 4, MIBI scan was the only examination capable of detecting at an early stage a mediastinal lymph node metastasis in one patient. We conclude that the integrated MIBI scan/neck US protocol: (a) can be proposed as a first-line diagnostic procedure in the follow-up of DTC patients with high s-Tg levels and negative high-dose 131I scan, and (b) may be helpful in the follow-up of DTC patients who undergo partial thyroidectomy alone. Moreover, the combined MIBI scan/neck US/s-Tg protocol appears to be highly sensitive in identifying patients with metastatic disease after total thyroidectomy and prior to 1311 scan; consequently, it may play a prognostic role in distinguishing high-risk from low-risk DTC patients. However, due to the low sensitivity of MIBI scan and neck US in detecting thyroid remnants, this diagnostic approach cannot be used as a predictor of 131I scan results. Lastly, because of the high sensitivity of MIBI scan and neck US in revealing both functioning and non-functioning metastases, this integrated protocol might be helpful in the follow-up of high-risk DTC patients, particularly for the early detection of lymph node metastases in patients with undetectable s-Tg during SHT.
Aged↗
Role of scintigraphy with tumor-seeking agents in the diagnosis and preoperative staging of malignant thyroid nodules.
The commonly used procedure for the diagnosis of thyroid nodule malignancy is based on high resolution thyroid ultrasonography (US) combined with US-guided fine needle aspiration cytology (FNAC). The other imaging procedures have a limited role in malignancy diagnosis. However, nuclear medicine procedures, particularly scintigraphy with tumor-seeking agents such as 201-thallium (201-TI), 99mTc-methoxy-isobutyl-isonitrile (99mTc-MIBI) and 99mTc-tetrofosmin may play an important role in the differential diagnosis between benign and malignant thyroid nodules in cases of non-diagnostic or inadequate FNAC. This type of scintigraphy can also be used in the follow-up of patients with cytologically 'high'-risk thyroid nodules such as Hurtle cell adenomas and follicular adenomas. Furthermore, scans with tumor-seeking agents can be helpful in determining the preoperative staging of thyroid carcinoma patients with locally advanced disease, and in accurately evaluating the extent, and consequently, the surgical management of the disease.
Humans↗
Nuclear medicine imaging procedures in differentiated thyroid carcinoma patients with negative iodine scan.
Radioiodine treatment following surgery is an effective therapy in differentiated thyroid carcinoma (DTC) patients. However, in DTC patients with metastases characterized by very low or absent iodine uptake, total thyroidectomy and radical loco-regional lymphoadenectomy is the only effective therapeutic approach. In the present article, we have discussed the most recently available nuclear medicine techniques utilized for the detection of DTC metastases that have lost the capacity to trap radioiodine. A review of the data published in the literature has been presented, and a comparative analysis made of the results obtained by other imaging modalities such as high resolution neck ultrasonography (US), computed tomography (CT) and magnetic resonance imaging (MRI). In our experience, the most sensitive and accurate imaging procedure is represented by the combination of neck US and whole body 99mTc-methoxy-isobutylisonitrile (99mTc-MIBI) scintigraphy; this combination might be proposed as a first-line diagnostic approach in DTC patients with increased serum thyroglobulin (Tg) levels and negative high dose 131I scans.
Fluorodeoxyglucose F18↗
The role of external beam radiotherapy in the management of differentiated thyroid cancer.
Well differentiated thyroid cancers (DTC), usually having an indolent course, are generally treated by surgery, i.e., total or near total thyroidectomy, followed by radioiodine and TSH suppressive therapy with thyroid hormone. The beneficial effect of external beam radiotherapy (EBRT) in the treatment of selected metastatic sites (i.e., brain and bone) or for palliation in cases of locally advanced inoperable disease is widely accepted. In contrast, its efficacy in improving postoperative locoregional disease control is still controversial. A better definition of subgroups of patients at high risk of local failure is mandatory. At present, patients older than 40-45 years affected by papillary cancers with macro- or microscopic postoperative residual disease and with extensive extrathyroid invasion appear to benefit from EBRT performed in addition to surgery and radioiodine. The role of EBRT in patients with radioiodine non-responsive progressive disease will also be discussed.
Bone Neoplasms↗
Parathyroid imaging with pertechnetate plus perchlorate/MIBI subtraction scintigraphy: a fast and effective technique.
We set up a modified technetium-99m (Tc-99m) pertechnetate/Tc-99m MIBI (Tc-MIBI) subtraction scintigraphy for parathyroid imaging by introducing the use of potassium perchlorate (KCLO4). Initially, the effect of KCLO4 on technetium thyroid wash-out was evaluated in five healthy volunteers: 40-minute dynamic studies of the thyroid were obtained 20 minutes after the injection of technetium 150 MBq (4 mCi), both in baseline conditions and after the oral administration of 400 mg KCLO4. After an average latency time of 10.5 minutes, KCLO4 administration resulted in fast and relevant technetium thyroid wash-out with a mean half-time of 16.2 minutes (the half-time was 142.8 minutes in baseline conditions), and a 40-minute reduction of thyroid activity of 78% (it was 14% in baseline conditions). Based on these findings, a new Tc-MIBI subtraction procedure was established as follows: 1) 150 MBq technetium (4 mCi) injection; 2) 400 mg KCLO4 administered orally; 3) patient neck immobilization; 4) acquisition of a 5-minute technetium thyroid scan; 5) 500 MBq MIBI (13.5 mCi) injection; 6) acquisition of a sequence of seven MIBI images, each lasting 5 minutes; and 7) processing (image realignment when necessary, background subtraction, normalization of MIBI images to the maximum pixel count of the technetium image, and subtraction of the technetium image from the MIBI images). In addition, high-resolution neck ultrasound (US) was performed in all cases on the same day as the scintigraphic evaluation. Eighteen consecutive patients with primary hyperparathyroidism were enrolled in the study. Tc-MIBI scintigraphy revealed a single adenoma in all cases and US showed this finding in 15 of 18 cases (83.3%). Furthermore, in three patients, a thyroid nodule associated with hyperparathyroidism was detected by technetium thyroid scans and neck US. In all patients, the parathyroid adenoma was easily identified on both the 20- to 40-minute MIBI and subtracted (MIBI-Tc) images. Regarding the scintigraphic parameters, no difference was found between parathyroid adenomas located in the region of the thyroid bed or in ectopic sites and in parathyroid adenomas with a retrothyroid location. Surgical findings confirmed the presence of a single parathyroid adenoma in all cases. In the three patients with a concomitant thyroid nodule, thyroid lobectomy was performed. These preliminary data suggest that 1) double-tracer subtraction scintigraphy, combined with neck US, appears to be the preferable preoperative imaging procedure in hyperparathyroidism patients with concomitant thyroid nodular disease, 2) in the Tc-MIBI parathyroid scan, the use of KCLO4 results in a rapid and relevant technetium thyroid clearance, improving the quality of MIBI images and making the visualization of parathyroid adenomas, particularly those located behind the thyroid gland, easier.
Adenoma↗
Papillary thyroid carcinoma associated with parathyroid adenoma detected by pertechnetate-MIBI subtraction scintigraphy.
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.
Adenoma↗