False-positive uptake of I-131 in a laryngocele mimicking thyroid remnant after thyroidectomy for papillary thyroid carcinoma

A 66-year-old woman underwent total thyroidectomy for papillary thyroid carcinoma stage pT4 followed by radioiodine therapy with 3.7 GBq (100 mCi) iodine-131. Radioiodine therapy revealed intense radioiodine uptake of the neck, which was interpreted as thyroid remnant tissue. Follow-up whole-body scans with iodine-131 in hypothyroidism 3 months and 1 year after radioiodine therapy revealed focal uptake in the neck. Computed tomography and gadolinium-enhanced MRI of the neck demonstrated an ovoid lesion in the larynx without gadolinium enhancement. Neither thyroid remnant tissue nor enlarged cervical lymph nodes could be demonstrated either on CT or on MRI. Further examination of the patient in the ear, nose and throat department confirmed the finding of a laryngocele and biopsies demonstrated benign tissue. Follow-up whole-body scans with iodine-131 in hypothyroidism 3 years and after injection of rhTSH 5 years after radioiodine therapy reproduced the focal uptake in the neck. After initial radioiodine therapy thyroglobulin levels were never measurable, not at any of the whole-body scans in hypothyroidism, after rhTSH, or at intermediate follow-up examinations under TSH-suppressive levothyroxine therapy. The patient declined definitive operative revision of the laryngocele and is in good health 8 years after the diagnosis of papillary thyroid carcinoma.     

Cystic lymph node metastases in papillary thyroid carcinoma

OBJECTIVE: The aim of this study was to illustrate and discuss the sonographic spectrum of surgically proven cystic nodal metastases from papillary thyroid carcinoma. By correlative evaluation of the sonographic imaging findings to gross pathology and histology, our purpose was to provide useful hints to differentiate cystic lymph node metastases from other benign cystic neck lesions such as branchial cysts. MATERIALS AND METHODS: Sonographic examinations of 74 patients (47 women, 27 men; mean age, 49 years) with 97 histologically confirmed cystic lymph nodes metastases from papillary thyroid carcinoma were included in the study. The anatomic relationship of the nodes relative to the primary tumor was recorded, and all cystic nodes were qualitatively categorized as either simple (purely cystic) or complex (thickened outer wall, internal nodules, internal septations, and calcifications). All imaging findings were compared with gross pathologic specimens. RESULTS: Most of the cystic metastases were ipsilateral to the primary tumor (87.8%) and located in the mid or lower jugular chain (73.2%). In 14.9% of all patients, cystic lymph node metastases were the initial manifestation of disease. Only 6.2% of all lymph node metastases were purely cystic (all of these occurred in patients less than 35 years old). Of the 91 complex metastases, a thickened outer wall was present in 35.2% of patients, internal nodules in 42.9%, and internal septations in 57.1%. No calcifications were seen in the 91 complex metastases, and two or more findings were seen in 23.1%. All sonographic findings were verified by surgery. CONCLUSION: In most of the patients, cystic lymph node metastases are characterized sonographically by the presence of a thickened outer wall, internal echoes, internal nodularity, and septations. However, in younger patients, the lymph nodes might appear purely cystic, thereby mimicking branchial cysts and thus requiring biopsy for final diagnosis and therapy planning.     

Technetium-99m tetrofosmin single photon emission computed tomography to detect metastatic papillary thyroid carcinoma in patients with elevated human serum thyroglobulin levels but negative I-131 whole body scan

AIM: The aim of this study was to evaluate the effectiveness of technetium-99m tetrofosmin (Tc-99m TF) single photon emission computed tomography (SPECT) of the neck and chest to detect metastatic lesions in papillary thyroid carcinoma (PTC) after near total thyroidectomy and radioiodine (I-131) treatment in patients who present with elevated serum human thyroglobulin (hTg) levels but negative I-131 whole body scan (WBS). MATERIALS AND METHODS: Twenty patients with PTC treated by near total thyroidectomy and I-131 treatments were included in this study. All 20 patients had negative I-131 WBS results and elevated hTg levels (hTg 2.0 microIU/ml) under thyroid-stimulating hormone (TSH) stimulation (TSH 30 microIU/ml). Nineteen of the 20 cases were confirmed to have metastases by operation/biopsy histopathological findings or clinical follow-up longer than 1 year by additional morphological imaging techniques. The remaining patient has been followed up closely and has been disease free for 10 months. Tc-99m TF SPECT was performed to detect metastatic lesions. RESULTS: Tc-99m TF SPECT demonstrated lesions in 11/19 patients; a sensitivity of 57.9%. Tc-99m TF SPECT failed to demonstrate lesions in eight patients including smaller lymph nodes and miliary lung metastases. CONCLUSIONS: We conclude that Tc-99m TF SPECT is a useful additional tool to detect metastatic lesions in PTC with elevated hTg but negative I-131 WBS. However, smaller lymph nodes and miliary lung metastases may be missed.     

Gamma probe-guided lymph node dissection ('gamma picking') in differentiated thyroid carcinoma

The prognostic significance and the optimal management of regional lymph node metastases in patients with well-differentiated thyroid carcinoma continue to be controversial. The current surgical approach for nodal metastases is removal of grossly involved lymph nodes ("berry picking"). In patients with papillary thyroid cancer, this intraoperative sampling technique reveals tumor in only 15% to 60% of excised nodes. However, if a more extensive nodal dissection is undertaken, at least 70% of patients are found to have nodal disease. The authors have successfully used a gamma probe-guided lymph node dissection technique ("gamma picking") to identify visually undetectable micrometastatic lymph nodes at the time of surgical exploration. The authors used this technique in a 52-year-old man with papillary carcinoma of the thyroid that was diagnosed by fine-needle aspiration. Eighteen hours before the planned total thyroidectomy, the patient was given 1 mCi I-123 orally. Operative exploration revealed multiple tumor nodules in both lobes but no palpable lymph nodes in the neck. Total thyroidectomy was performed with complete extracapsular removal of both lobes and isthmus. The thyroid bed and the central and lateral nodal basins were scanned using a gamma probe (Neoprobe). Hot spots were identified, and these counts were compared with that of the background activity in the strap muscles. The gamma probe revealed four distinct foci of increased activity (10 times more than the background). These were resected and labeled separately for histopathologic study. Histologic analysis revealed bilateral, multifocal well-differentiated papillary carcinoma, with the largest tumor focus measuring 0.6 cm. Two of the four hot spots proved to be metastatic foci in small lymph nodes measuring less than 0.5 cm. The other two hot spots were thyroid remnants with no associated nodal tissue.     

Value of FDG PET in papillary thyroid carcinoma with negative 131I whole-body scan.

The management of metastatic thyroid carcinoma patients with a negative 131I scan presents considerable problems. Fifty-four athyrotic papillary thyroid carcinoma patients whose 1311 whole-body scans were negative underwent 18F-fluorodeoxyglucose (FDG) PET; the purpose was to determine whether this procedure could localize metastatic sites. We also assessed its usefulness in the management of these patients. METHODS: Whole-body emission scan was performed 60 min after the injection of 370-555 MBq 18F-FDG, and additional regional attenuation-corrected scans were obtained. Metastasis was pathologically confirmed in 12 patients and was confirmed in other patients by overall clinical evaluation of the findings of other imaging studies and of the subsequent clinical course. RESULTS: In 33 patients, tumor had metastasized, whereas 21 patients were in remission. FDG PET revealed metastases in 31 patients (sensitivity 93.9%), whereas thyroglobulin levels were elevated in 18 patients (sensitivity 54.5%). FDG PET was positive in 14 of 15 metastatic cancer patients with normal thyroglobulin levels. In 20 of 21 patients in remission, FDG PET was negative (specificity 95.2%), whereas thyroglobulin levels were normal in 16 patients (specificity 76.1%). The sensitivity and specificity of FDG PET were significantly higher than those of serum thyroglobulin. In patients with negative 1311 scans, FDG PET detected cervical lymph node metastasis in 87.9%, lung metastasis in 27.3%, mediastinal metastasis in 33.3% and bone metastasis in 9.1%. In contrast, among 117 patients with 131I scan-positive functional metastases, 131I scan detected cervical lymph node metastasis in 61.5%, lung metastasis in 56.4%, mediastinal metastasis in 22.2% and bone metastasis in 16.2%. In all 5 patients in whom thyroglobulin was false-negative with negative antithyroglobulin antibody, PET showed increased 18F-FDG uptake in cervical lymph nodes, mediastinal lymph nodes, or both. Among patients with increased 18F-FDG uptake only in the cervical lymph nodes, the nodes were dissected in 11. Metastasis was confirmed in all, even in normal-sized lymph nodes. CONCLUSION: FDG PET scan localized metastatic sites in 131I scan-negative thyroid carcinoma patients with high accuracy. In particular, it was superior to 131I whole-body scan and serum thyroglobulin measurement for detecting metastases to cervical lymph nodes. FDG PET was helpful for determining the surgical management of these patients.     

The use of technetium-99m pertechnetate in postoperative thyroid carcinoma. A comparative study with iodine-131

Over 3 years, a prospective comparison was made between Tc-99m pertechnetate and I-131 for the detection of residual and metastatic tissue in the follow-up of patients with cancer of the thyroid. All patients stopped thyroid medication for a minimum of 4 weeks. All patients had imaging done first with Tc-99m pertechnetate followed within a maximum of 2 weeks by I-131. The study included 66 patients in whom 81 studies were done with both Tc-99m and I-131. The results showed that 27 studies were positive with both Tc-99m and I-131 (true positive): 19 in the thyroid bed, four lymph nodes, two bony metastases, and two pulmonary metastases. Five patients had negative results with Tc-99m and positive results with I-131 (false negative): three in the thyroid bed, one lymph node metastasis, and one pulmonary metastasis. Only one case was positive with Tc-99m in the neck but negative with I-131 (false positive). The remaining 48 studies were negative both with Tc-99m and I-131 (true negative). Considering I-131 imaging as the standard procedure, Tc-99m had a sensitivity of 87%, specificity of 97%, and accuracy of 92.5% for the detection of residual or metastatic functioning thyroid tissue.     

Value of the first serum thyroglobulin level after total thyroidectomy for the diagnosis of metastases from differentiated thyroid carcinoma.

The aim of this study was to evaluate the diagnostic significance of the first serum thyroglobulin (Tg) measurement, performed 40 days after total thyroidectomy for differentiated thyroid carcinoma and prior to the ablation of residual thyroid tissue by means of iodine-131 therapy. In a retrospective study we examined 334 consecutive patients followed up for 4-16 years by means of regular Tg measurements, (131)I whole-body scans (WBS) and other diagnostic techniques, if necessary. In 79 patients metastases were discovered (32 lymph node and 47 distant metastases) within 18 months following thyroidectomy. Mean values of first Tg were significantly higher in patients with than in patients without metastases (258.9+/-310.6 vs 15.9+/-19.6 ng/ml; P<0.0001). Receiver operating characteristic (ROC) curve analysis of data revealed that for first Tg values higher than 69.7 ng/ml, the positive predictive value for the presence of metastases exceeded 90%. No statistically significant correlation was found between first Tg value and either thyroid-stimulating hormone (TSH) value or percentage of (131)I uptake by residual thyroid tissue. No other parameter (age, histological type, site of metastases, (131)I uptake by metastases) was significantly related to the first Tg value. We conclude that the first Tg measurement after total thyroidectomy provides a useful early diagnostic indication of metastatic disease in spite of the presence of a post-surgical thyroid remnant, and that this holds true regardless of the TSH value and WBS result. This early information is of clinical relevance for patient follow-up.     

Seven cases of brain metastasis from papillary thyroid carcinoma

Brain metastases from differentiated thyroid carcinoma are extremely rare and carry a poor prognosis. We describe here clinical details of 7 cases of brain metastases from papillary thyroid carcinoma. Of 153 patients with metastases from differentiated thyroid carcinoma (papillary in 123, follicular in 30) treated at our institution between 1981 and 1999, 7 patients (4.6%) had brain metastases. Histologically, the primary tumor was papillary carcinoma in all 7 cases. Four were males and 3 were females. The median age at first diagnosis of distant metastases was 63 yr (range, 47-76 yr). Of these patients, one had brain metastases only and six had metastases to the lungs as well. Five of these patients were treated with 131I. Three of these 5 patients had marked uptake in the metastases (131I positive) on post-therapy 131I scans and another 2 patients had no significant activity (131I negative) in both pulmonary and brain metastatic lesions. One of 3 patients with 131I positive lesions had intense activity in the brain tumor, but no uptake in multiple pulmonary metastatic tumors. In a patient with 131I positive brain metastases, the tumors progressed rapidly after 131I therapy. In another one patient, acute hemorrhage of the tumor occurred four days after 131I therapy, requiring surgical removal. Loner case of 131I negative 2 patients was treated with radiosurgery (gamma-knife) and complete reduction in tumor volume was observed. On the other hand, one of 2 patients receiving no 131I therapy had radiosurgery (x-knife) and remaining one received conventional external radiation and chemotherapy for small solitary brain and pulmonary metastatic tumors. These therapeutic interventions were useful in both cases. The mean length of survival after the development of brain metastases in the five patients who died of the disease was 30 months. One patient treated with x-knife has been alive at 21 months and another one who has 131I uptake in the brain tumor without uptake in lung lesions has been alive 15 months after diagnosis of brain metastasis. These results indicate that it is important to detect brain metastasis by imaging techniques and Tg measurements and give treatment as early as possible since the brain is the third most common distant metastatic site and the prognosis is poor.     

Thallium-201 imaging in the follow-up of differentiated thyroid carcinoma

Since thallium-201 imaging has been reported as a potential means of follow-up of patients with differentiated thyroid carcinoma (DTC) during ongoing thyroid suppression therapy, the authors evaluated the diagnostic sensitivity of this procedure in 31 patients known to have metastases or local recurrence. Among 51 tumor sites 201TI imaging had a detection rate of 45% whereas 84% was noted for imaging with 131I administered in therapeutic doses. Thus, even though the effectiveness of the two radionuclides is not strictly comparable due to the difference in the administered doses, Thallium imaging cannot be recommended as the only modality for the follow-up of patients with DTC. Six of the eight tumor sites negative with 131I were positive with 201TI (especially metastatic cervico-mediastinal lymph nodes). So 201TI imaging may particularly be helpful in localizing metastases or recurrences in patients with a negative 131I scan and abnormal levels of serum thyroglobulin.     

Results of radioiodine therapy in patients with pulmonary metastases of differentiated thyroid cancer

Factors affecting the effect of 131I treatment and survival after pulmonary metastases in patients with differentiated thyroid cancer, were studied. Between 1984-1999, pulmonary metastases was observed in 51 out of 153 patients with differentiated thyroid cancer at our institution. Of these 41 patients had papillary and 10 follicular thyroid cancer. There were 37 females and 14 males with mean age (+/- S.D.) of 50.5 +/- 19.0 years. These 51 patients were subjected to 131I therapy. The effect of 131I treatment and the prognostic values of the following variables were examined: sex, age at the time of 131I treatment, histologic type of cancer, size of pulmonary metastases on CT, total-body scintigraphy with 201Tl and 131I, serum thyroglobulin levels and presence of metastases in distant sites other than lung. The effect of 131I treatment was evaluated by means of changes in the number and size of metastatic shadows on chest CT and by serum thyroglobulin levels. The minimum duration of follow-up was 12 months. Therapeutic 131I dose scans revealed detectable uptake in 25 of 51 patients. Therapeutic 131I dose uptake was achieved more frequently in patients under 40 years of age and in those with follicular cancers. Of the 51 patients, 13 were evaluated to be treated successfully. Those under 40 years of age, with 131I uptake in the lung and presence of other metastases showed a good response to treatment than others. Follicular cancer showed a more significant association with coarse type of lung metastases (> 5 mm in diameter on chest CT) and good 131I uptake than papillary cancer. Of all the variables studied, the best prognosis for survival was demonstrated by increased 131I uptake in pulmonary metastases. These results indicate that age, 131I uptake and presence of other metastases are important factors in predicting the effect of 131I treatment for pulmonary metastases of differentiated thyroid cancer.     

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.     

Preoperative US-guided hook-needle insertion in recurrent lymph nodes of papillary thyroid cancer: A help for the surgeon

Objective

The objective of this study is to investigate whether preoperative ultrasound guided insertion of a hook-needle is useful in reoperations for cervical recurrent lymph node metastases of papillary thyroid cancer.

Patients and methods

8 patients with operated papillary thyroid cancer were included in this study. They all had suspicious nonpalpable cervical lymph nodes discovered during follow-up. These lymph nodes were identified by ultrasound imaging and their metastatic nature was confirmed by fine needle aspiration cytology and measurement of in situ thyroglobulin. In all cases, surgical excision of these lymph nodes was decided. All 8 patients had a hook-needle inserted in the suspicious lymph node(s) preoperatively and under ultrasound guidance.

Results and conclusion

In all 8 patients, the suspicious lymph nodes were removed and their metastatic nature was confirmed by the final pathological examination. This localization technique is very helpful for the surgeon during the excision of small and nonpalpable lymph nodes, especially in previously operated area.     

Value of the first serum thyroglobulin level after total thyroidectomy for the diagnosis of metastases from differentiated thyroid carcinoma

The aim of this study was to evaluate the diagnostic significance of the first serum thyroglobulin (Tg) measurement, performed 40 days after total thyroidectomy for differentiated thyroid carcinoma and prior to the ablation of residual thyroid tissue by means of iodine-131 therapy. In a retrospective study we examined 334 consecutive patients followed up for 4–16 years by means of regular Tg measurements, ¹³¹I whole-body scans (WBS) and other diagnostic techniques, if necessary. In 79 patients metastases were discovered (32 lymph node and 47 distant metastases) within 18 months following thyroidectomy. Mean values of first Tg were significantly higher in patients with than in patients without metastases (258.9±310.6 vs 15.9±19.6 ng/ml; P<0.0001). Receiver operating characteristic (ROC) curve analysis of data revealed that for first Tg values higher than 69.7 ng/ml, the positive predictive value for the presence of metastases exceeded 90%. No statistically significant correlation was found between first Tg value and either thyroid-stimulating hormone (TSH) value or percentage of ¹³¹I uptake by residual thyroid tissue. No other parameter (age, histological type, site of metastases, ¹³¹I uptake by metastases) was significantly related to the first Tg value. We conclude that the first Tg measurement after total thyroidectomy provides a useful early diagnostic indication of metastatic disease in spite of the presence of a post-surgical thyroid remnant, and that this holds true regardless of the TSH value and WBS result. This early information is of clinical relevance for patient follow-up. Received 26 October 1998 and in revised form 12 June 1999     

Papillary thyroid carcinoma: MR diagnosis of lymph node metastasis.

PURPOSEThe purpose of this study was to ascertain the usefulness of MR imaging in the diagnosis of nodal metastasis of papillary thyroid carcinoma and to establish the most indicative MR criteria of metastasis.METHODSPathologic records and MR images in 50 patients with papillary thyroid carcinoma were reviewed. Each neck was divided into four nodal levels, so that 200 nodal levels were assessed in all. The maximum of the minimum transverse diameters of the lymph nodes on each nodal level measured on MR images and the certainty of metastasis as determined by a head and neck radiologist on the basis of morphologic aspects were compared with the pathologic findings by using receiver operating characteristic curves. The presence or absence of cystic nodes on each nodal level was also evaluated.RESULTSMetastasis was found on 87 (44%) of the nodal levels in 34 (68%) of the patients. A cystic node was identified on 33 (17%) of the nodal levels in 13 (26%) of the patients and was seen only on positive nodal levels. Morphologic diagnosis by the radiologist was better than that obtained by measurement. With the combined criteria of a cystic node or a node of 13 mm or more for the maximum of the minimum transverse diameters, specificity was 100% with an 82% accuracy and always indicated metastasis (100% positive predictive value). However, 41% of the metastatic nodes were missed with this criterion (59% sensitivity).CONCLUSIONMR imaging was useful for diagnosing metastatic nodes; a nodal diameter threshold of 13 mm or the presence of a cystic node strongly indicated metastasis from papillary thyroid carcinoma.     

Incidental multifocal papillary microcarcinomas of the thyroid: is subtotal thyroidectomy combined with radioiodine ablation enough?

BACKGROUND: The extent of thyroid resection and the necessity of lymph node dissection has become an issue of controversy in patients with incidental multifocal papillary microcarcinoma. METHOD: Between 1993 and 2001 a total of 4120 patients underwent surgery for thyroid diseases: 142 patients showed papillary thyroid cancer of < or = 1 cm, multifocal microcarcinomas were found in 22 patients (15.5%). Twenty patients (17 women, three men, aged 26-71 years) met the inclusion criterion of having pre- and intraoperatively no indication of malignancy (incidentaloma). A limited surgical procedure ranging from bilateral subtotal (n=15), ipsilateral total, contralateral subtotal (n=4) to bilateral total (n=1) thyroidectomy without lymph node dissection was performed. The mean volume of thyroid remnants was 4.3 ml. RESULTS: In 16/20 (80%) patients, the thyroid remnant was ablated by the first dose of 131I, using 3.7 GBq 131I in 15 patients and 1.85 GBq 131I in one patient. Three patients received a second, and one patient a third radioiodine ablation. All 20 patients remained free from relapse or metastasis, documented by negative 131I whole-body scintigraphy and unmeasurable thyroglobulin levels after thyroid hormone withdrawal in hypothyroidism. One patient died 7 years after the diagnosis of thyroid cancer from primary lung cancer. Median follow-up was 65 months (range, 24-120 months). CONCLUSION: Subtotal thyroidectomy followed by radioiodine therapy without completion thyroidectomy and lymphadenectomy is a possible option in incidental multifocal microcarcinomas.     

Evaluation of suspected recurrent papillary thyroid carcinoma with [18F]fluorodeoxyglucose positron emission tomography

We evaluated 10 patients with suspected recurrent papillary thyroid cancer using [18F]fluorodeoxyglucose positron emission tomography (FDG PET). Prior therapy included total (n = 8) or subtotal (n = 2) thyroidectomy, radiation therapy (n = 2) and radioiodine ablation (n = 2). All patients had an 131I scan and one or more of the following imaging studies: 99Tcm-sestamibi scan. 111In-octreotide scan, sonography (US), computed tomography (CT) and magnetic resonance imaging (MRI). Both the PET and 131I scans were negative in four patients. The PET and 131I scan results were discordant in six patients. Of the six discordant cases, five had true-positive PET scans and false-negative 131I studies. Three of these patients underwent neck lymph node dissection that showed positive histology for metastatic papillary carcinoma. Another patient had fine-needle aspiration (FNA) of a parapharyngeal mass that was also positive for papillary carcinoma. One patient was treated with radiation to the thyroid surgical bed based on an elevated serum thyroglobulin and a positive PET finding. Tumour response with a decrease in the size of the lesion was documented by a follow-up MRI scan. The remaining patient had a presumed false-positive PET scan, since a difficult hypocellular FNA of a small palpable lymph node was negative for tumour. We conclude that FDG PET is useful in the evaluation of patients with suspected recurrent papillary thyroid cancer when the 131I scan is negative.     

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 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. Received 21 October and in revised form 20 December 1999     

The clinical impact of18F-FDG PET in papillary thyroid carcinoma with a negative131I whole body scan: A single-center study of 108 patients

OBJECTIVE: To assess whether FDG PET could localize the recurrent or metastatic lesions in papillary thyroid cancer patients with negative radioiodine scan. METHODS: Whole body PET was performed after injecting 370-555 MBq of 18F-FDG in 108 patients, who were suspected of having recurrence or metastasis and whose 131I whole body scans were negative. Recurrence or metastasis occurred in 63 patients by pathology or clinical assessment, whereas 45 patients remained in remission. RESULTS: FDG PET revealed recurrence or metastases in 59 patients (sensitivity 93.7%), whereas thyroglobulin (Tg) levels were elevated in 41 (sensitivity 65.1%). In 35 of 45 patients in remission, FDG PET was negative (specificity 77.8%). When patients positive for antithyroglobulin antibody were excluded, the sensitivity and specificity of serum Tg became 84.8% and 46.9%, respectively. Compared to Tg measurement, FDG PET detected more metastatic lesions in cervical lymph nodes. Of 40 patients with a negative radioiodine scan showing diffuse hepatic uptake, metastases occurred in 23 patients and remission in 17. FDG PET showed 100% sensitivity and 76.5% specificity in the detection of recurrence in these 40 patients. CONCLUSION: FDG PET is useful for localizing recurrent or metastatic lesions in 131I scan-negative thyroid cancer patients. In particular, it is superior to serum Tg measurement for identifying metastases to cervical lymph nodes. We recommend its use in cases of negative radioiodine scan with diffuse hepatic uptake.     

Preliminary studies of monoclonal antibody lymphoscintigraphy in malignant melanoma

Lymphoscintigraphy was performed at 3 and 20 hr following subcutaneous injection of 131I anti-melanoma antibody (Fab) in 11 patients who had surgical resection of lymph nodes (neck, axilla, groin) at 24 hr for suspected metastatic melanoma. Comparable amounts of 125I nonspecific control antibody (Fab) were co-administered. Six patients had nodal metastases and three showed positive images at both time periods. Five patients had no metastases though one was image positive. Four other nondiseased inguinal node groups were image negative. A total of 28 tumored nodes and 110 normal nodes were removed, counted and histologically examined. All metastatic tumors expressed antigen against which the specific Fab was directed. The concentrations of both specific and nonspecific Fab were similar in tumored nodes and both were significantly greater than in normal nodes showed essentially identical intranodal spatial distribution of the specific and control Fab in areas containing tumor. These preliminary results suggest the increased concentration of murine immunoglobulin (Fab) retained in diseased nodes was a nonspecific phenomenon.     

Brain metastases with exceptional features from papillary thyroid carcinoma: report of three cases

We present three papillary thyroid carcinoma PTC patients with brain metastases who are unusual in many aspects. The first case is a unique 3mm papillary thyroid microcarcinoma (PTMC) patient with metastases to the cerebrum and lung. The solitary cerebral lesion was identified by iodine-131 whole- body scan ((131)I-WBS) and (131)I single photon emission tomography/computed tomography (SPET/CT). Almost complete response achieved after radiosurgery. The second case is a unique PTC patient with coexistent (131)I-negative cerebrum, adrenal gland and ilium metastases, which were identified by (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography/computed tomography (PET/CT) and magnetic resonance imaging (MRI). Partial response achieved after radiosurgery. The third case is a patient with an incident solitary cystic cerebellar mass as a primary presentation of follicular variant of PTC and absent other distant metastases. In conclusion, widespread metastases from small PTMC may occur. Concomitant brain and adrenal metastases may occur in a same PTC patient. Brain metastasis may present as a cystic lesion.