[en] Published in summary form only

[en] Published in summary form only

No abstract available

[en] The aim of this study was to investigate the possible role of technetium-99m 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 US, and s-Tg measurements during suppressive hormonal therapy (SHT) were obtained in all patients. Neck and chest CT or 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. Moreover, the combined MIBI scan/neck US/s-Tg protocol appears to be highly sensitive in identifying patients with metastatic disease after total thyroidectomy. (orig/MG) sensitive in identifying patients with metastatic disease after total thyroidectomy and prior to ¹³¹I 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. (orig.)

[en] Complete text of publication follows: Distant metastases are found at diagnosis or during follow-up in 10%-15% of patients with differentiated thyroid cancer. Bone is the second most commonly involved site. Patients with bone metastases, whether isolated or associated with lung metastases, have a markedly poor prognosis. Ten-year survival rates range from 13% to 21%. Given such poor prognosis, the use of ¹³¹I therapy has been questioned. However, it might well be that poor prognosis of bone metastases can be overcome if ¹³¹I therapy is delivered at an early stage, when tumor burden is small, as previously demonstrated for pulmonary metastases. A review of a large series of patients showed that only rarely were bone metastases diagnosed at an early stage. Among 109 patients with bone metastases reported by Bernier et al., only 4 had both radioiodine uptake and a negative standard radiography examination. Similarly, Durante et al. reported that only 8 of 115 patients had negative radiography findings at presentation. Prognosis may improve if bone metastases are detected earlier. In a recent study, bone metastases were first detected by ¹³¹I scanning in 8 of 16 patients, when complementary radiologic studies were negative. Six of these patients showed an excellent response to ¹³¹I therapy. Today, the nuclear medicine community is well armed for this challenge toward earlier diagnosis. Postsurgery thyroid remnant ablation is more widely used. The ¹³¹I whole body scan associated with thyroid remnant ablation after thyroidectomy has a major role in early diagnosis of functioning distant metastases at a time when complementary imaging techniques (CT, MRI, bone scanning) are often still showing negative findings. Early diagnosis of specific ¹³¹I-avid bone foci will be improved with the advent and generalization of SPECT/CT. When early diagnosis is achieved, repeated ¹³¹I therapy can be effective by targeting not only visible metastases but also those still too small to be imaged. In our practice, we administer 3.7 GBq of ¹³¹I every 6 mo until the whole-body therapy scan shows negative findings. Verification of a second negative post-therapy scan a year later could be useful, especially in cases of residual serum thyroglobulin levels. When bone metastases are visible on radiologic examination, we give activities of 5.5 GBq every 6 mo and as frequently as every 4 mo to those with more advanced disease. Optimal management should include an ¹⁸F-FDG PET scan, to potentially detect poorly differentiated disease. Given the poor prognosis of large bone metastases, an aggressive surgical approach would seem warranted. However, not all bone lesions are amenable to surgical excision, and additional therapy such as radiotherapy or alternative treatments by arterial embolization, percutaneous radiofrequency ablation, cementoplasty, or alcoholisation can be offered. Most patients with bone macro-metastases will die from disease. Therefore, in our opinion, ¹³¹I should not be interrupted as long as metastases are still ¹³¹I-avid, whatever the cumulative activity reached. In these patients, ¹³¹I is the only opportunity to slow progression and to prolong survival. The low statistical risk of developing a late second malignancy should not restrain physicians from effectively treating the present cancer. High cumulative activities of radioiodine (≥22 GBq [600 mCi]) are associated with an increased risk of leukemia. Rubino et al. measured an excess absolute risk of 0.8 leukemia cases per giga-becquerel of ¹³¹I and 105 person-years of follow-up. On this basis, of 100 patients with a cumulated activity of 22 GBq and followed up for 10 y, 0.2 cases of leukemia are expected. These authors also reported a link between ¹³¹I therapy and excess colorectal cancer (and also salivary glands and bone and soft tissue sarcomas), which was not confirmed by other studies. On the basis of current knowledge, it would seem unjustified to withhold ¹³¹I therapy. It should be remembered that ¹³¹I therapy is well tolerated and relatively inexpensive. Very aggressive therapies are sometimes given in other types of cancers to prolong survival only a few months. To date, there are no effective therapies for patients with disseminated poorly differentiated carcinomas, without ¹³¹I uptake, or in whom disease progresses rapidly despite ¹³¹I therapy. In these patients, new molecular targeted treatments may provide hope. Several trials are currently ongoing worldwide, but none of these molecules has yet entered clinical practice. In conclusion, early ¹³¹I-based diagnosis and aggressive case-tailored ¹³¹I therapy is what nuclear physicians can best offer to patients with bone metastases of thyroid cancer

[en] Differentiated thyroid cancer, when adequately treated, has an overall good prognosis. However, 10-15% of patients develop distant metastases. The presence of metastases is an important prognostic factor that negatively affects survival. For ¹³¹I-avid distant metastases, ¹³¹I therapy is a very effective treatment modality that induces complete remission in about a third of patients. These figures may be even higher in case of early diagnosis, when tumor burden is still limited. Additional measures may include surgery and/or external beam radiation therapy. Cytotoxic chemotherapy is largely ineffective in patients with progressive, poorly differentiated cancer. These patients should be candidates for trials with new molecularly targeted therapeutic agents. In this paper, a review of diagnostic modalities, prognostic factors and therapeutic options for patients with distant metastases is proposed. In particular, the prognostic value of the early discovery of metastatic disease will be underlined. (authors)

[en] 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. (orig.)

[en] 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. (orig.)

[en] Asymptomatic chronic thyroiditis (ACT) is a variant of the autoimmune thyroiditis characterized by the presence of circulating anti-thyroid antibodies and the absence of palpable goiter. Thyroid function can be normal but a considerable percentage of ACT patients tend to develop subclinical hypothyroidism over time and thus periodical controls of thyroid hormones and TSH levels are needed. At present, useful parameters for predicting the functional out-came of ACT patients are lacking. To investigate this aspect, the authors evaluated 57 consecutive ACT patients (51 females, 6 males, aged 22-56 years) by means of thyroid ^99mTc-pertechnetate scintigraphy and echography, and by measuring the serum level of anti-peroxidase antibodies (TPOAbs), FT4, T3 and TSH. At first observation, 30 patients were euthyroid whereas 27 had subclinical hypothyroidism. No patient had been previously treated with thyroid hormones. Thyroid scan showed a normal pattern or a diffuse and mild irregular uptake, without differences between euthyroid and subclinical hypothyroid patients. TPOAb levels tend to be higher in patients with subclinical hypothyroidism in comparison to the euthyroid patients (5893±1423 and 3943±912 UI/mL, respectively) but the difference was not statistically significant by using Student's ^t-test. Echography showed a normal pattern in 14 patients, while a diffuse hypoechoic pattern in the other cases, mild in 12, moderate in 19 and marked in 12, as found. A significantly higher prevalence of subclinical hypothyroidism was observed in the group of patients with a moderate or marked hypoechoic pattern in comparison to the group with a normo-echoic or mild hypoechoic pattern (70.4% versus 23.0%, Fisher's exact test p=0.00003). Furthermore, the 3 patients who developed thyroid failure during a one-year follow-up also presented a moderate or marked hypoechoic pattern. Our data suggest that the echo-pattern can be a useful predictor of thyroid failure in ACT patients and thus the echographic evaluation should be included in the diagnostic protocol of these patients

[en] The use of recombinant human thyroid-stimulating hormone (rhTSH) in differentiated thyroid cancer (DTC) is widely discussed in the literature with regard to the diagnostic and therapeutic aspects of the management of DTC patients. However, some controversy about the appropriate indications, advantages and potential disadvantages of the use of rhTSH may still exist within the community of nuclear medicine physicians. In our opinion, the clinical benefits of rhTSH in avoiding hypothyroidism outweigh its somewhat lesser diagnostic accuracy. However, we disagree on designating rhTSH as the 'golden standard' to obtain TSH stimulation, as suggested by some authors. Thus, the first follow-up examination after ablation, which is determinant for patients' prognostic classification, can be either done under rhTSH stimulation or after hormone withdrawal. In our practice, and for higher risk patients, we still favour performing the initial follow-up after thyroid hormone withdrawal. rhTSH also shows the ability to enhance radioiodine concentration into thyroid cells. This characteristic is obviously of great interest among the nuclear medicine community. In clinical practice, it seems preferable to perform ¹³¹I treatment for metastatic disease during hypothyroidism. rhTSH may find its utility for the treatment of specific populations of patients, i.e. those in whom hormone withdrawal is medically contraindicated or in whom adequate endogenous TSH levels cannot be obtained due to reduced pituitary reserve or continued thyroxine production by metastatic tissue. In conclusion, rhTSH has demonstrated to be a reliable alternative to hypothyroidism for the stimulation of Tg in the follow-up of thyroid cancer patients. However, its use must be more carefully chosen in the therapeutic setting. Our feeling is that rhTSH should no tbe used for remnant ablation in high-risk patients and for the treatment of metastatic disease, except for specific populations of patients. (O.M.)