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.

Different features of pulmonary metastases in differentiated thyroid cancer: natural history and multivariate statistical analysis of prognostic variables

We studied 134 patients with differentiated thyroid cancer and pulmonary metastases. All were treated with total or near total thyroidectomy, radioiodine and L-thyroxine. The prognostic value of the following variables in three groups of patients were evaluated by univariate and multivariate analysis: age at diagnosis, sex, histologic type, tumor extension, cervical lymph node metastases, mediastinic metastases, presence of metastases in distant sites other than lungs (multiple distant metastases) and morphological (chest x-rays) and functional (131I uptake) features of lung metastases. Univariate analysis identified patient age (p < 0.0001), morphological and functional features of lung metastases (p < 0.0001), presence of multiple distant metastases (p < 0.0001) and histologic type (p = 0.04) as significant prognostic factors. Multivariate analysis showed only morphological (p = 0.0014) and functional (p < 0.0001) features of lung metastases and the presence of multiple distant metastases (p = 0.01) as significant and independent variables. The data show that early (pre-radiological) scintigraphic diagnosis and 131I therapy of lung metastases appear to be the most important elements in obtaining both a significant improvement in survival rate and a prolonged disease-free time interval in these patients.

Venous Air Embolism Identified by 18F-Fluorocholine Dual-Phase PET/CT

ABSTRACT

A 60-year-old woman with primary hyperparathyroidism with previous nonconclusive imaging studies was referred for 18F-fluorocholine (18F-FCH) PET/CT as part of the preoperative diagnostic imaging workup to localize the adenoma before minimally invasive surgery. 18F-FCH PET/CT with dual time point was performed, acquiring immediately and 60 minutes after 18F-FCH administration. The early images demonstrated possible hyperfunctioning parathyroid tissue in the mediastinum, located in the right upper paratracheal space (region 2R), with an incidental iatrogenic subclavian venous air bubble embolism presenting as high uptake in the early images that disappeared in the late images. No symptomatology was reported during the examination.

[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.

PET imaging in neuroendocrine tumors: current status and future prospects

Neuroendocrine tumors (NET) are relatively rare diverse group of tumors that possess several unique characteristics and occur most commonly in the gastrointestinal tract. An important feature of these tumors is that they express somatostatin (SST) receptors, and thus can be successfully targeted with specific radiolabeled SST receptor related compounds. This has led to the introduction of multitude of single photon emission computed tomography (SPECT) and positron emission tomography (PET) tracers, which have significantly improved the ability for imaging these neoplastic lesions with high spatial resolution in the abdomen and elsewhere in the body. The introduction of Gallium-68 labeled radiopharmaceuticals as viable PET agents have added a new dimension to the management of patients with NET by providing high quality images compared with planar or SPECT with single photon emitting preparations. (18)F-labeled DOPA has demonstrated impressive results in differentiating between focal and diffuse disease in hyperinsulinism of the newborn which appears to be of crucial clinical benefit and has altered the management of these patients significantly. With regard to other types of NET, the current experience with such agents is relatively limited and therefore prospective studies are required to further define the role of PET in this complicated group of patients.

Clinical applications of 68Ga-DOTANOC in neuroendocrine tumours

Neuroendocrine tumours (NET) are relatively rare neoplasms affecting principally the gastroenteropancreatic tract, but with potential ubiquitary location, as the neural crest cells, origin of this group of tumours, are dispersed in various organs and tissues. After the discovery of somatostatin receptors (SSTR) over-expression in this group of neoplasms, NET management has significantly improved. This is witnessed by the development of new tracers in positron emission tomography (PET) imaging of NETs belonging to the family of radio-labelled somatostatin analogues, that significantly improved the accuracy of diagnosis and, more recently, opened the way to the innovative targeted radionuclide therapies. First introduced in clinical application in 2005, 68Ga-DOTANOC (one of the most used radio-labelled somatostatin analog for PET imaging) has revealed promising results in preliminary studies for the main clinical indications: staging NET; suspected NET of unknown primary; follow-up, restaging and, finally, for pre- and post-treatment evaluation of receptor radionuclide therapies. Due to its technically simple production, favourable biodistribution, biokinetics, dosimetry and high affinity for SSTR and thanks to the possibility of hybrid scans PET/computed tomography (CT) with better spatial resolution and localisation of the lesions, 68Ga-DOTANOC can advance as the new gold standard for imaging in neuroendocrine tumours.

Detection of bilateral, multifocal breast cancer and assessment of tumour response to neoadjuvant chemotherapy by Tc-99m sestamibi imaging - a case report

In breast cancer, neoadjuvant chemotherapy needs early indication for responsiveness. Tc-99m sestamibi scintimammography provides comprehensive information about the extent of disease including multiple foci in one or both breasts and possible involvement of nodes. In the present case, X-mammography was positive for a suspicious mass in the upper quadrant of the left breast only. On the other hand,Tc-99m Sestamibi scintimammography was able to depict the full extent of the disease, including its spread to the axillary lymph node, and gave useful information on the effectiveness of neoadjuvant chemotherapy. The case reported here demonstrates that Tc-99m sestamibi scintimammography was useful in detecting bilateral breast cancer and could provide additional information on possible axillary lymph node involvement. Furthermore, Tc-99m sestamibi scintimammography was effective in monitoring response to chemotherapy in the studied case.

11C-methionine vs. 18F-FDG PET in soft tissue sarcoma patients treated with neoadjuvant therapy: preliminary results

OBJECTIVE

In patients with soft tissue sarcoma (STS) the histological response (tumour grade regression: TGR) to neoadjuvant chemoradiotherapy (CRT) may influence the outcome. The main aim of the study was to evaluate the predictive value of 11C-methionine (MET) and 18F-FDG PET/CT in patients with STS treated with neoadjuvant CRT, correlating TGR with SUVmax (standardized uptake value) percentage variation before and after CRT.

PATIENTS AND METHODS

Nine patients with STS already scheduled for a neoadjuvant CRT and surgery were enrolled. They underwent MET and FDG PET/CT in a one-day procedure before and after the CRT. Pre-therapy SUVmax and the percentage variation of SUVmax for MET and FDG were correlated with TGR according to the Huvos grade. Grades I-II were considered as partial responders (PR) and grades III-IV as complete responders (CR).

RESULTS

FDG pre-treatment mean SUVmax in PR patients was 7.1, while in CR patients it was 13.2. Pre-treatment mean MET SUVmax in PR patients was 75, while in CR patients it was 4.9. The mean percentage variation in FDG SUVmax, was -21.2% in PR patients and -745% in CR patients while that for MET SUVmax was 48% in PR patients and -53.9% in CR patients.

CONCLUSION

According to this preliminary study, the percentage variation in FDG before and after CRT seems to discriminate between PR and CR better than MET.

New simple and low-cost methods for periodic checks of Cyclone® Plus Storage Phosphor System

The recent large use of the Cyclone® Plus Storage Phosphor System, especially in European countries, as imaging system for quantification of radiochemical purity of radiopharmaceuticals raised the problem of setting the periodic controls as required by European Legislation. We described simple, low-cost methods for Cyclone® Plus quality controls, which can be useful to evaluate the performance measurement of this imaging system.

Pitfalls in adrenal surgery. Report of two cases

Pitfalls in diagnosis and treatment of adrenal diseases are frequent and not properly reported in literature. Among more than 51 adrenalectomies for incidentaloma performed during a l0 years period, we present 2 cases of diagnostic errors that a very formative opportunity in the approach to adrenal diseases. A precise and careful preoperative diagnosis is of utmost importance in the management of adrenal disease to avoid therapeutic pitfalls.

[Radiometabolic therapy for metastatic thyroid carcinoma: overview of the literature and rational bases for the use of recombinant human TSH]

The established treatment for differentiated thyroid carcinoma (DTC) is founded on total thyroidectomy and subsequent administration of radioiodine (131I) to ablate the thyroid remnant and to treat the metastatic disease. In the case of metastatic or recurrent disease, further cycles of 131I therapy are often necessary. The condition for maximizing the effectiveness of the treatment is to have an adequate stimulation from TSH, which must be >25-30 mIU/L. This elevation is achieved either discontinuing the hormone suppression therapy for an appropriate period, or administering recombinant human TSH (rhTSH). The latter has shown good clinical efficacy in patients with residual thyroid gland and is nowadays commonly employed since it is easy to use and allows to avoid the side effects of hypothyroidism. It thus represents a good alternative to thyroid hormone withdrawal for the remnant ablation, while is still open the question if its efficacy on the management of metastatic disease is superimposable to thyroid hormone withdrawal. To this purpose, a Panel of expert reviewed the literature, assessing the advantages and disadvantages for the patient, as well as the impact in terms of cost and benefit to the National Health Service. The work of the Panel concluded with a proposal for the use of rhTSH in selected patients with metastatic DTC, in which is considered the efficacy and safety of the product and is examined its use in terms of costs; this proposal was accepted by the Italian Drug Agency resulting in an update of the indications for rhTSH.

Minimally invasive (99m)Tc-sestamibi radioguided surgery of parathyroid adenomas

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.

Aliskiren improves blood pressure control and prevents cardiac damage in high-risk hypertensive subjects

AIM

Longitudinal study aimed to evaluate the antihypertensive efficacy, safety and the effect on cardiac damage of Aliskiren, administered to a group of high-risk hypertensive patients with mild impairment of renal function and uncontrolled blood pressure (BP) despite a two-drug antihypertensive treatment.

METHODS

One hundred and six patients (56 men and 50 females) aged 61.9±12.7 years, were assigned to receive Aliskiren 150-300 mg once-daily for 12 months. Clinic BP measurements were taken at every follow-up visit (1st, 6th and 12th month), while biochemical tests, estimated glomerular filtration rate (eGFR), 24-hours ambulatory BP measurements (ABMP) and echocardiography were evaluated at baseline and at the end of follow-up. Analysis of variance for repeated measures compared BP, left ventricular mass index (LVMI) and eGFR values changes.

RESULTS

A significant reduction (all P<0.0001) of clinic systolic (-28.6 mmHg) and diastolic (-12.8 mmHg) BP values, mean 24h-systolic (-12.3 mmHg) and 24h-diastolic (-6.5 mmHg), day-time systolic (-11.5 mmHg) and diastolic (-6.4 mmHg), night-time systolic (-11.9 mmHg) and diastolic (-7 mmHg) ABPM values and in the use of antihypertensive drugs was observed (3.0±0.9 vs. 2.0±0.7, p=0.01). LVMI was significantly reduced (130.2±36.1 vs. 115.9±33.4 g/m2, P<0.0001); eGFR was steady (75.3±17.3 vs. 73.1±21.5 ml/min/1.73m2, P>0.05). Putative adverse events caused withdrawal of 7 subjects (6 for gastrointestinal disturbances, 1 for alopecia).

CONCLUSION

Aliskiren was effective in decreasing both clinical and ABPM values and in reducing LVMI in both genders without any influence on eGFR. The treatment resulted safe, even in combination with ACE-inhibitors and angiotensin II receptor blockers. A significant reduction in the use of concomitant antihypertensive drugs was observed.

Clinical meaning of circulating antithyroglobulin antibodies in differentiated thyroid cancer: a prospective study

In recent studies of patients with differentiated thyroid cancer (DTC), an association between the persistence of tumor and the presence of circulating anti-thyroglobulin antibodies (TgAbs) have been described. The aim of the present study was to evaluate TgAb variations before and after total thyroid ablation and to correlate TgAb levels to the outcome of disease. Forty-three patients with DTC were studied (35 female, 8 male; 33 patients had papillary cancer and 10 follicular cancer). Tumor was intrathyroid in 20 cases, had spread to the lymph nodes in 19 and to the lungs in 4. All patients underwent total thyroidectomy and 131I therapy, and were then treated by suppressive doses of L-thyroxine. After a mean follow-up of 3.55 yr, TgAbs became undetectable in 24 patients (all were considered tumor-free), whereas TgAbs remained elevated in 19 cases. In 5 of these 19 patients, disease progression or persistence was documented (to the lymph nodes in three and to the lungs in two). TgAb levels were higher in patients with persistent disease in comparison with those tumor-free. Serum thyroglobulin (S-Tg) results were only elevated in the two patients with persistent disease in the lungs. Our data suggest that TgAbs determination may give some additional information to the follow-up of patients with DTC: the disappearance of TgAbs after therapy seems to represent a favorable prognostic factor, while the persistence of circulating TgAbs, particularly at high levels and in the absence of detectable S-Tg, may be representative of disease.

Clinical approach in patients with metastatic differentiated thyroid carcinoma and negative 131I whole body scintigraphy: importance of 99mTc MIBI scan combined with high resolution neck ultrasonography

AIMS AND BACKGROUND

The aim of this study was to define the clinical impact of MIBI scan combined with neck ultrasonography on the detection of metastates in differentiated thyroid carcinoma (DTC) patients with elevated serum Tg levels but negative 131I scan (non-functioning DTC).

METHODS AND STUDY DESIGN

Eighty-two patients with non-functioning DTC, 19 patients with 131I-positive metastases (functioning DTC), and 24 DTC patients who were disease free after therapy (no cancer patients) were enrolled. 131I scan was performed after administration of low diagnostic and high therapeutic tracer doses. Early and delayed images were obtained after MIBI injection. Neck-chest CT scan and/or MRI were also performed in patients with non-functioning DTC.

RESULTS

In the group of non-functioning DTC patients, metastatic foci were detected in 71/82 cases: in the cervical lymph nodes in 51 cases (sensitivity 94.1% with MIBI, 90.2% with US, 35.3% with CT/MRI), mediastinal lymph nodes in 31 cases (sensitivity 100% with MIBI, 58% with CT/MRI), lungs in 8 cases (sensitivity 100% with both MIBI and CT/MRI), and bone in 2 cases (sensitivity 50% with MIBI, 100% with MDP bone scan). Among the 19 patients with functioning DTC a close relationship between MIBI and 131I findings was observed. As regards the 24 tumor-free patients, MIBI was correctly negative in all cases, while US visualized enlarged cervical lymph nodes that were suspected to be neoplastic but proved to be inflammatory lesions at cytology in three patients.

CONCLUSIONS

On the basis of these data, MIBI scan combined with neck US could be proposed as a first-line diagnostic imaging modality in the follow-up of DTC patients with elevated serum Tg levels and negative 131I scan.

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.

Sentinel lymph node (SLN) procedure with patent V blue dye in 153 patients with papillary thyroid carcinoma (PTC): is it an accurate staging method?

The present study aims to evaluate the accuracy of sentinel lymph node (SLN) mapping performed by intratumoral injection of blue dye in a large series of patients with papillary thyroid cancer (PTC). 153 consecutive patients were enrolled in the study. All patients had a preoperative cytological diagnosis of PTC, and none had clinical or ultrasonographic (US) evidence of nodal involvement. At surgery, vital patent V blue dye was injected into the malignant thyroid nodule. Subsequently, total thyroidectomy, central compartment (CC) node dissection, and median inferior jugulocarotid node dissection of laterocervical compartment, ipsilateral to the primary tumour, were performed. The excised thyroid, the blue-positive SLN and blue-negative lymph nodes were sent for frozen section and definitive histophatologic analysis. At surgery, blue-positive SLN were found in 107/153 patients (69.9%), of whom 36 (33.6%) had micrometastasis in SLN; moreover, in 13 of these 36 patients (36.1%), other nodes were found to be metastatic. In the remaining 71/107 blue-positive SLN patients, both the SLN itself and the other removed nodes were found negative for the presence of metastatic disease. In 4 cases, a normal parathyroid gland and in 3 cases fibro-adipous tissue were blue-stained and mistakenly removed as SLN (7 false positive results). On the other hand, SLN was blue-negative in 46/153 patients (30.1%), of whom 7 patients (15.2%) had micrometastases in blue-negative lymph nodes. On the basis of these data, the blue dye procedure for SLN detection appears inappropriate as a standard of care in PTC due to a relatively high number of false negative and false positive results.

Somatostatin receptor PET imaging with Gallium-68 labeled peptides

Imaging somatostatin receptor status with 68Ga labeled peptides has progressed rapidly over the last several years. It has generated great interest, and stimulated further research into the development of DOTA-derivative peptides. It has expanded our knowledge of receptor imaging and enhanced our appreciation of the difference between receptor-based and metabolic imaging, as well as more in-depth evaluation of tumor biology. The availability of the 68Ge/68Ga generator provides an attractive alternative to cyclotron-based positron-emitters, especially if kit-based radiopharmaceutical formulations based upon 68Ga are developed in the future.