双核素阴茎海绵体动态显像对血管性阳萎的评价

目的建立双核素阴茎海绵体动态显像的定量分析方法，用于评价血管性阳萎。方法用９９ｍＴｃＲＢＣ作阴茎海绵体动脉系统显像，１３１Ｉ邻碘马尿酸（ＯＩＨ）作阴茎海绵体静脉系统显像，并在盐酸罂粟碱负荷下连续测阴茎海绵体内放射性变化。观察１２例正常男子和４２例阳萎病人阴茎海绵体血液动力学变化。结果１２例正常男子９９ｍＴｃ阴茎动脉系统显像指数（ＴＰＩＡ）为２０７±０８４（正常值＞０６０）；１３１Ｉ阴茎静脉系统显像指数（ＩＰＩＶ）为－０３４±０１２（正常值＞－０４８）。根据ＴＰＩＡ和ＩＰＩＶ的结果，４２例阳萎病人被分为３组：１３例ＴＰＩＡ、ＩＰＩＶ正常者为非血管性阳萎组，其ＴＰＩＡ为１９０±０６９，ＩＰＩＶ为－０３６±００８；２１例ＴＰＩＡ正常、ＩＰＩＶ异常者为静脉性阳萎组，ＴＰＩＡ为１９８±０１０，ＩＰＩＶ为－０６７±０１２；８例ＴＰＩＡ异常、ＩＰＩＶ正常或异常者，其ＴＰＩＡ为０３４±０２１，ＩＰＩＶ为－０５５±０１１。结论双核素阴茎海绵体动态显像对评价血管性阳萎，特别是鉴别静脉和动脉系统方面的病理状况是一种安全、无创、客观和有价值的方法     

CT测定甲状腺体积(重量)的研究及临床应用

目的：探讨ＣＴ扫描测量甲亢患者甲状腺重量，并对其准确性进行研究，为临床＾１３１Ｉ治疗甲亢测量甲状腺重提供了一种较准确的方法。材料与方法：采用东芝ＴＣＴ－３００／ＥＺ全身ＣＴ扫描系统，（１）对１５个甲状腺模型进行扫描，利用ＣＴ机的体积计算功能计算甲状腺模型体积，甲状腺模型的实际体积通过模型排除水的容量来计算。（２）１３１例甲亢患者＾１３１Ｉ治疗前行甲状腺扫描，计算甲状腺体积（重量）。结果：（１）甲状     

胃排空动态显像中双核素标准餐的应用

目的研究１３１Ｉ小牛血清白蛋白（ＢＳＡ）和９９ｍＴｃＤＴＰＡ双核素胃排空动态显像的方法及探讨其临床应用价值。方法用前临时标记１３１ＩＢＳＡ和９９ｍＴｃＤＴＰＡ，配成１３１ＩＢＳＡ鸡蛋固体餐和９９ｍＴｃＤＴＰＡ水液体餐。固体餐经人胃液消化试验，检测标记物稳定性。检查３５例慢性胃炎病人和１０例健康志愿者的胃排空功能，其中２例在３天内进行了１３１ＩＢＳＡ鸡蛋餐和９９ｍＴｃ硫胶体（Ｓｃ）鸡肝餐两法对照，比较其相关性。结果１３１ＩＢＳＡ和９９ｍＴｃＳｃ在胃液中消化２小时，脱标率分别为３００％和５１６％；１３１ＩＢＳＡ鸡蛋餐法和９９ｍＴｃＳｃ鸡肝餐法相关性好，ｒ＝０９８９，Ｐ＜００１；对照组固相半排空时间（ＨＳＥＴ）为５８２±１７７分钟，液相半排空时间（ＨＬＥＴ）为２３５±９４分钟；病例组ＨＳＥＴ为９２５±２９６分钟，ＨＬＥＴ为３７２±１６６分钟；固相和液相两组差异均有显著性（ｔ＝３４７４和２４８５，Ｐ＜００１）。结论１３１ＩＢＳＡ鸡蛋餐、９９ｍＴｃＤＴＰＡ液体餐同时使用（双核素标准餐法）可为临床提供胃排空固体和液体食物的情况     

加碘盐饮食对甲状腺吸131I功能的影响

加碘盐饮食对甲状腺吸１３１Ｉ功能的影响苏敏杨键肖亚景刘长江吕中伟附表正常组及甲亢组在加碘盐饮食前后甲状腺吸１３１Ｉ率（ｘ±ｓ）比较组别例数甲状腺吸１３１Ｉ率（％）３ｈ２４ｈ比值甲亢诊断符合率人数符合率（％）未加碘正常组６９１８５±４７３５５±９...     

分化好的甲状腺癌功能性肺转移所致严重的甲状腺毒症

根据甲状腺功能测定和１３１　 Ｉ全身扫描所示甲状腺的低摄取及肺部多个转移灶的高摄取，对两侧分化好的甲状腺癌功能性肺转移所致严重的甲状腺毒症病人作了诊断。报告了此两例病人在甲状腺全切术和１３１　 Ｉ治疗后症状得到迅速改善的结果。例 １：女性，６９ 岁（２５ 年前曾行甲状腺部分切除术），甲状腺癌已转移并伴有严重的甲亢症状及肺功能不全引起的呼吸困难、缺氧及高碳酸血症。甲状腺功能检测各项指标均达到甲亢的诊断标准，胸片及 Ｃ Ｔ 发现双侧肺有多个巨大转移灶，１３１　 Ｉ全身扫描显示甲状腺摄取低而这些肺转移灶有强烈的摄取，９９ｍ　 Ｔｃ高锝酸盐全身扫描也显示此结果。由于该病人的一般状况差， 不能进行甲状腺全切术， 故用１２３ Ｇ Ｂｑ １３１　 Ｉ分两次（间隔 ５ 个月）治疗，治疗前服用 ４ 周丙基硫氧嘧啶和甲基强的松龙以防甲状腺危象。１３１　 Ｉ治疗后 ６ 个月，胸片、 Ｃ Ｔ 和９９ｍ　 Ｔｃ高锝酸盐全身扫描均显示肺部转移灶有明显改善，血清甲状腺球蛋白由 ４８ ６８０ｎｇ／ｍ ｌ降至 １３ ０００ｎｇ／ｍ ｌ，甲状腺激素和促甲状腺激素也恢复正常，呼吸不再困难，动脉血气测定也显示得到明显改善。例２：女性，７９ 岁，患甲状腺滤泡癌，肺功能不全伴甲     

分化型甲状腺癌患者131I治疗后全身显像的临床价值

目的：评价治疗剂量＾１３１Ｉ全身显像在分化型甲状腺癌（简称甲癌）患临床随访中的价值。方法５７例分化型甲癌患在给予１８５ＭＢｑ（诊断剂量）＾１３１Ｉ－２－３ｄ后进行前、后位全身显像;给予治疗剂量＾１３２Ｉ７－１０ｄ后,用相同的采集条件进行全身显像,同时分析所有患的血清甲状腺球蛋白水平。用配对Ｘ＾２检验对结果进行处理。结果３１例接受＾１３１Ｉ去除术后残留甲状腺组织患,治疗剂量＾１３１Ｉ显像与诊     

99mTc-MIBI甲状腺结节显像对甲状腺癌的诊断价值

９９ｍＴｃＭＩＢＩ甲状腺结节显像对甲状腺癌的诊断价值苏敏刘长江杨键肖亚景吕中伟附表１０３例甲状腺结节９９ｍＴｃＭＩＢＩ显像分析结果病理检查例数图像分析不填充部分填充填充ＲＯＩ分析＜０８７≥０８７综合判断良性恶性结节性甲状腺肿甲状腺囊腺瘤甲状腺...     

硝酸甘油酯介入~(99m)Tc-MIBI心肌断层显像与多巴酚丁胺负荷超声心动图判定存活心肌的比较

为比较硝酸甘油酯（ＮＴＧ）介入９９ｍＴｃ甲氧基异丁基异腈（ＭＩＢＩ）心肌断层显像与小剂量多巴酚丁胺负荷超声心动图（ＤＳＥ）在判断急性心肌梗塞（ＡＭＩ）后病人存活心肌中的一致性，对３６例ＡＭＩ病人分别进行了ＮＴＧ介入９９ｍＴｃＭＩＢＩ心肌断层显像和小剂量（＜１０μｇ·ｋｇ－１·ｍｉｎ－１）的ＤＳＥ检查，所有检查均在病人入院后２～３周内完成。结果：在心肌静态显像示梗塞的１０９个节段中，ＮＴＧ显像４３个为存活节段，存活心肌检出率为３９％；在基础状态下超声心动图示梗塞的９４个节段中，ＤＳＥ检查３５个为存活节段，其存活心肌检出率为３７％，两者间差异无显著性（χ２＝０１０５，Ｐ＞００５）。在两法共同检出的９２个梗塞节段中，均存活的节段为２９个，均未存活的节段为４９个，两法的一致性为８４８％（７８／９２，Κ＝０６８）。因此，ＮＴＧ介入９９ｍＴｃＭＩＢＩ心肌断层显像与ＤＳＥ检查均为判断ＡＭＩ后病人存活心肌的安全、可靠的方法，两法具有良好的一致性。     

99mTc-MIBI延迟心肌断层显像评估存活心肌的初步临床研究

目的评价４小时９９ｍＴｃ甲氧基异丁基异腈（ＭＩＢＩ）延迟显像在评估心肌活力方面的价值。方法对３０例冠心病（ＣＡＤ）病人（１８例经冠状动脉造影证实）进行常规静息和４小时延迟９９ｍＴｃＭＩＢＩ心肌断层显像。对其中１０例经冠状动脉血运重建术治疗的病人术后３５６±１９２天进行心肌断层显像随访。将左室心肌划分为９个节段。采用四点计分法对各节段核素分布进行半定量评价（摄取正常＝３，重度降低或缺损＝０）。结果３０例ＣＡＤ病人常规静息显像示１２６个（４６７％）节段核素分布异常，延迟显像示１０５个（３８９％）节段核素分布异常。常规静息显像心肌计分≤１（“无活力”）的节段有９３个；延迟显像时３６４％的０分节段和５３１％的１分节段计分改善≥１。延迟显像与冠状动脉血运重建术后显像对比，判断存活心肌的阳性预测值为８４２％，阴性预测值为９００％，预测准确率为８７２％，两者有良好的一致性（χ２＝２１５９，Ｐ＜００１）。结论９９ｍＴｃＭＩＢＩ延迟心肌显像，通过一次给药可较有效地克服静息心肌显像低估心肌活力的不足，对判定缺血心肌活力状态方面具有临床实用价值     

甲状腺锥体叶^99mTc显像的临床价值

目的：探讨甲状腺锥体叶显像的临床价值。材料和方法：常规肘静脉注射９９ｍＴｃＯ－４后３０分钟甲状腺显像,对２６０例甲状腺机能亢进症患者和２４３例非甲亢对照组患者行甲状腺显像,观察甲状腺锥体叶的出现情况。结果：２６０例甲亢患者中７８例锥体叶阳性,２４３例对照组中８例锥体叶阳性,两者差异有显著性（Ｐ＜００１）,锥体叶阳性对甲亢诊断的敏感性为３００％,特异性为９６６％。锥体叶可位于峡部或一叶上方,多呈舌状,放射性分布略低于左右叶,大小不等。甲亢术后原有锥体叶可长大。结论：甲状腺锥体叶显像有助于甲亢的临床诊断。     

Thallium-201 scintigraphy in differentiated thyroid cancer: comparison with radioiodine scintigraphy and serum thyroglobulin determinations

The role of thallium-201 (201TI) scintigraphy in the follow-up evaluation of differentiated thyroid carcinoma (DTC) is controversial. Desirable characteristics of 201TI scintigraphy including the potential for no thyroid hormone withdrawal, immediate imaging postinjection, and low radiation burden relative to iodine-131 (131I) suggests it is logistically superior to 131I scintigraphy. Fifty-two patients with DTC were evaluated with 201TI and 131I neck and chest images, and serum thyroglobulin measurements. In post-thyroidectomy and pre-131I ablation therapy patients, very little 201TI accumulation was noted within the thyroid bed, with discordantly increased 131I activity and normal serum thyroglobulin measurements. Twenty-nine percent of patients evaluated after 131I ablative therapy had elevated serum thyroglobulin levels and localized neck and chest abnormalities on 201TI scan that were not seen on 131I studies. Our data suggest that 201TI is more sensitive than 131I diagnostic (5 mCi) studies for detection of DTC, while 131I is more sensitive in detecting normal residual thyroid tissue postoperatively.     

Differentiated thyroid cancer: radioiodine following lobectomy - a clinical feasibility study

The surgical management of differentiated thyroid cancer remains controversial. Total thyroidectomy has been associated with higher rates of post-operative morbidity than more conservative surgery, but radioiodine ablation of residual thyroid tissue is considered to be particularly difficult after lobectomy. The purpose of this retrospective study was to assess the feasibility of 131I ablation after lobectomy, compared with total thyroidectomy, in patients who had undergone surgery for differentiated thyroid carcinoma. A retrospective analysis was performed of 225 post-surgical thyroid cancer patients treated with 3500 MBq 131I for the ablation of thyroid remnants. One hundred and sixty-five patients (73%) had previously undergone total thyroidectomy, whilst 60 patients (27%) had been treated by lobectomy. All patients underwent diagnostic scintigraphy, with 40 MBq 131I, 2 days prior to ablative therapy and at 3 months post-ablation. The median pre-ablative 131I neck uptake values were 3.3% and 20.1% in patients treated by total thyroidectomy and lobectomy, respectively (P < 0.001). Pre-ablation neck uptake correlated strongly with the whole-body 131I burden 2 days after 131I therapy (P < 0.001), and the biological half-life of the radioiodine was markedly longer after lobectomy than after total thyroidectomy. Ninety-eight per cent of patients treated by total thyroidectomy were successfully ablated by one 131I treatment, compared with 90% after lobectomy (P < 0.05). There were no significant differences in 131I neck uptake or serum thyroglobulin levels between the two patient groups at 3 months post-ablation. These data show that high rates of thyroid ablation can be achieved with a single fixed dose of 131I after thyroid lobectomy. The use of this surgical procedure may result in a longer period of patient isolation than that required after total thyroidectomy. However, the clear correlation between pre-ablation neck uptake and 131I burden at 2 days post-therapy enables effective treatment scheduling, so making lobectomy followed by 131I ablation a practical option for the management of differentiated thyroid cancer.     

Low levels of serum thyroglobulin after withdrawal of thyroid suppression therapy in the follow up of differentiated thyroid carcinoma

We evaluated the reliability of very low serum thyroglobulin (Tg) levels (less than 3 ng/ml) obtained after withdrawal of thyroid suppression therapy in 224 patients without anti-Tg antibodies, who had undergone total thyroidectomy (125 patients) or thyroidectomy followed by 1 or more courses of 131I therapy (99 patients), by performing whole body scans after a therapeutic course of 131I given at the same time of Tg measurement. In 79 patients (35%) a positive scan, associated with a very low level of Tg, was noted. The 131I uptake was limited to the thyroid bed in 60 patients, but metastases were demonstrated in 19 patients (8.5%). These results are mainly explained by the much improved performance of scintigraphy after administration of therapeutic doses of 131I. In the majority of patients, especially those whose 131I uptake was limited to the thyroid bed, further scans were negative. Therefore, in these cases, negative Tg values can generally be considered an early indication of satisfactory evolution. However, in 8.5% of all cases, very low Tg levels were associated with metastases. Thus the follow up of thyroid cancer should not rely only upon Tg determination, even after suppression therapy withdrawal.     

Treatment of medullary carcinoma of the thyroid. Value of calcitonin as tumour marker

Changes in immunoreactive serum calcitonin were measured in 11 patients with medullary carcinoma of the thyroid, before and after surgery, external high-voltage irradiation, 131I therapy, and chemotherapy. Measurement of serum calcitonin concentration was found to be a useful method for evaluating tumour mass and function during treatment. Contrary to previous reports, treatment with 131I resulted in a positive effect on serum calcitonin and diarrhoea, and in one patient with bone metastases these disappeared. No response was found following chemotherapeutic regimes. Calcitonin was found to be more sentitive than palpation, radiography, and scintigraphy for determining the amount of tumour tissue, but a definite correlation between this amount and the concentration of serum calcitonin was not found.     

Fixed dosage of 131I for remnant ablation in patients with differentiated thyroid carcinoma without pre-ablative diagnostic 131I scintigraphy

Differentiated thyroid cancer is treated by (near) total thyroidectomy followed by radioiodine (131I) ablation of the residual active tissue in the thyroid bed. Controversy remains concerning the use and the dose of pre-ablative diagnostic 131I scintigraphy. This study was designed to assess the efficacy of thyroid ablation by high-dose 131I without pre-ablative diagnostic 131I scintigraphy. Ninety-three patients were treated with (near) total thyroidectomy and with a high ablative dose of 131I (3700-7400 MBq). A preablative 131I diagnostic scintigram was not performed. To assess the efficacy of the treatment, all patients were studied with a diagnostic 131I scintigram and with thyroglobulin plasma assays 1 year later after withdrawal of L-thyroxine for 4-6 weeks. The main criterion for a successful ablation was the absence of thyroid bed activity. An additional criterion was a thyroglobulin value of <10 microg x l(-1). Successful ablation according to the main criterion was obtained in 88% of patients. Forty patients (43%) showed no neck uptake and had undetectable serum thyroglobulin. Twenty-two patients (25%) had serum thyroglobulin concentrations between 1 and 10 microg x l(-1). Twenty-six patients (27%) had thyroglobulin >10 microg x l(-1), 19 patients showing residual thyroid uptake or metastatic lesions. We conclude that high-dose radioiodine ablation without prior diagnostic scintigraphy results in a high rate of successful ablation, preventing repeat 131I treatment.     

Follow-up regimen of differentiated thyroid carcinoma in thyroidectomized patients after thyroid hormone withdrawal.

For differentiated, nonmedullary thyroid carcinoma, postsurgical ablation of thyroid remnants and treatment of residual tumor and metastases with 131I is a potentially curative therapy. The aim of this study was to optimize the diagnostic protocol for the follow-up of thyroidectomized patients. METHODS: Two hundred fifty-four patients (187 females, 67 males; mean age, 45 y; range, 8-83 y) were studied retrospectively for a mean follow-up period of 2.7 y (range, 1-12.5 y). An evaluation study consisted of a low-dose 131I diagnostic procedure under hyperthyroid conditions (thyroid-stimulating hormone > 30 MicroU/mL), 201TI scintigraphy, and measurement of thyroglobulin (Tg) under hypothyroid conditions. A total of 254 preablation studies (1 study per patient) and 586 follow-up studies (average number of studies, 2.3 per patient) were evaluated. RESULTS: Before ablation, low-dose 131I screening was useful to estimate the size of the thyroid remnant. Low Tg levels (<10 pmol/L) indicated the absence of metastases. After ablation, undetectable Tg levels indicated the absence of tumor recurrence. When Tg levels were high (>10 pmol/L), local recurrence or metastases were always observed, providing the basis for additional high-dose 131I therapy. In these patients, 201TI imaging did not provide a significant contribution to patient management. In the case of autoantibodies against Tg, both low-dose 131I screening and 201TI scintigraphy may be advocated to allow an aggressive diagnostic work-up. CONCLUSION: Tg plays a key role in follow-up and in making decisions to treat patients with differentiated thyroid carcinoma. The role of 201TI imaging is very limited. In patients with negative low-dose 131I screening, 201TI scintigraphy can be considered when Tg is elevated or cannot be evaluated because of autoantibodies against Tg. Under such circumstances, administration of a therapeutic 131I dose without 201TI imaging can be considered.     

Role of thallium-201 total-body scintigraphy in follow-up of thyroid carcinoma

To evaluate the reliability of total-body scintigraphy using [201Tl]chloride in postoperative follow-up of thyroid carcinoma, this procedure was performed in 326 patients after total thyroidectomy for thyroid carcinoma. The results were compared with those of 131I scintigraphy and thyroglobulin assays. 201Tl total-body scintigraphy was found to have the greatest sensitivity (94%), whereas 131I scintigraphy had the highest specificity (99%). It is shown that 201Tl total-body scintigraphy is a useful procedure in follow-up of thyroid cancer, however, the combination of parameters provides the greatest reliability. In medullary thyroid carcinoma, which is usually 131I negative, 201Tl total-body scintigraphy can be of great value for the localization of metastases which are indicated by elevated serum levels of calcitonin and carcinoembryonic antigen.     

Comparison of (18)F-FDG, (131)I-Na, and (201)Tl in diagnosis of recurrent or metastatic thyroid carcinoma.

There are several reports about the usefulness of (18)F-FDG PET in thyroid cancer. However, few studies have compared FDG PET with (131)I and (201)Tl scintigraphy. The aim of this study was to evaluate the clinical significance of whole-body FDG PET in differentiated thyroid cancer and to compare the results with those obtained from (131)I and (201)Tl scintigraphy. METHODS: Whole-body FDG PET was performed on 32 patients (10 men, 22 women; age range, 30-77 y; mean age, 54 y) with differentiated thyroid cancer (5 cases of follicular cancer and 27 of papillary cancer) after total thyroidectomy. An overall clinical evaluation was performed, including cytology, thyroglobulin level, sonography, MRI, and CT, to allow a comparison with functional imaging results for each patient. Metastatic regions were divided into five areas: neck, lung, mediastinum, bone, and other. Multiple lesions in one area were defined as one lesion. The tumor-to-background ratio (TBR) was measured for the lesions that were positive for both (201)Tl uptake and FDG PET uptake. RESULTS: The number of lesions totaled 47. Forty-one (87%) were detected by all scintigraphic methods. FDG uptake was concordant with (131)I uptake in only 18 lesions (38%). FDG uptake was concordant with (201)Tl uptake in 44 lesions (94%). Only one lesion was negative for FDG uptake and positive for (201)Tl uptake, and two lesions were positive for FDG uptake and negative for (201)Tl uptake. A significant correlation was seen between the TBR of (201)Tl and that of FDG (r = 0.69; P<0.05). CONCLUSION: These data indicate that for detecting metastatic lesions, FDG PET and (131)I scintigraphy may provide complementary information, whereas FDG PET may provide results similar to those of (201)Tl scintigraphy. Thus, the combination of (131)I scintigraphy and FDG PET (or (201)Tl scintigraphy) is the method of choice for detecting metastatic thyroid cancer after total thyroidectomy.     

Post-surgical ablation of thyroid remnants with high-dose (131)I in patients with differentiated thyroid carcinoma

The aims of this study were to evaluate the efficacy of an empirically determined "fixed" high ablative dose of radioiodine ((131)I) therapy and to determine the utility of ultrasonography (US) in dose determination. A retrospective analysis was performed of 242 thyroid cancer cases treated with "fixed" high-dose (131)I for ablation of thyroid remnants without a pre-ablative (131)I diagnostic scintigraphy or radioiodine uptake study. Treatment doses ranged from 1850 MBq (50 mCi) to 7.4 GBq (200 mCi). The selection of the treatment dose was based on the surgical and pathological findings as well as the remnant thyroid volume calculated by US. A successful ablation was defined as the absence of activity in the thyroid bed on subsequent imaging studies. Successful ablation was obtained in 218 of the 242 patients (90%). In 162 of the 218 patients (74.3%), successful ablation was achieved after a single (131)I treatment. The remnant thyroid volume calculated by US was significantly different (P=0.04) between those who were successfully ablated and those who were not. The total (131)I dose needed for successful ablation was significantly higher in males (P=0.003). Patients with higher post-operative thyroglobulin (Tgb) levels and patients with a higher stage of disease required higher doses (P=0.036 and P=0.021 respectively). Serum Tgb levels were under 10 ng.ml(-1) in 220 of the 242 patients (90%) following radioiodine ablation while not receiving L-thyroxine suppression. Nineteen patients (7.8%) showed metastases on post-therapy scan and successful treatment was achieved in 11 of 19 (57.8%). Four of the 19 patients with distant metastases (revealed on post-treatment scan) were found to have been given a treatment dose of less than 200 mCi based on the proposed empirical approach. These results indicate that "fixed" high-dose (131)I treatment is clinically feasible with an acceptable dose underestimation rate, and the utilization of US in the determination of the thyroid remnant volume provides more accurate and reproducible results.     

Low levels of serum thyroglobulin after withdrawal of thyroid suppression therapy in the follow up of differentiated thyroid carcinoma

We evaluated the reliability of very low serum thyroglobulin (Tg) levels (< 3 ng/ml) obtained after withdrawal of thyroid suppression therapy in 224 patients without anti-Tg antibodies, who had undergone total thyroidectomy (125 patients) or thyroidectomy followed by 1 or more courses of¹³¹I therapy (99 patients), by performing whole body scans after a therapeutic course of¹³¹I given at the same time of Tg measurement. In 79 patients (35%) a positive scan, associated with a very low level of Tg, was noted. The 1311 uptake was limited to the thyroid bed in 60 patients, but metastases were demonstrated in 19 patients (8.5%). These results are mainly explained by the much improved performance of scintigraphy after administration of therapeutic doses of¹³¹I. In the majority of patients, especially those whose¹³¹I uptake was limited to the thyroid bed, further scans were negative. Therefore, in these cases, negative Tg values can generally be considered an early indication of satisfactory evolution. However, in 8.5% of all cases, very low Tg levels were associated with metastases. Thus the follow up of thyroid cancer should not rely only upon Tg determination, even after suppression therapy withdrawal.Presented in part as an oral communication at the European Nuclear Medicine Congress, Budapest, Hungary, 1987