Difference of Clinical and Radiological Characteristics According to Radioiodine Avidity in Pulmonary Metastases of Differentiated Thyroid Cancer

Purpose

To evaluate differences in clinical, radiological and laboratory findings between pulmonary metastasis with and without radioiodine avidity in thyroidectomized differentiated thyroid cancer (DTC) patients with pulmonary metastasis who underwent high-dose I-131 treatment.

Methods

A total of 105 DTC patients with pulmonary metastasis (age, 48.7 ± 16.8 years; women/men, 78/27) were included. Clinical characteristics, chest computed tomography (CT), F-18 fluorodeoxyglucose positron emission tomography (F-18 FDG PET)/CT and thyroid-stimulating hormone (TSH)-stimulated serum thyroglobulin (s-Tg) level were compared between patients with and without radioiodine uptake in metastatic lung lesions. The response to I-131 treatment was evaluated with follow-up study.

Results

Eighty-nine patients (84.8 %, whole-body scan positive [WBSP] group) showed radioiodine uptake at pulmonary metastasis on post I-131 treatment whole-body scan (WBS) and 16 patients (15.2 %, WBS negative [WBSN] group) did not show uptake at pulmonary lesions on the WBS. Ninety percent and 87 % of the WBSP group had visible metastatic lesions on CT and F-18 FDG PET/CT; however, all of the patients in the WBSN group showed lesions on CT and F-18 FDG PET/CT. In seven (6.7 %) of 105 patients, CT and F-18 FDG PET/CT could not detect pulmonary lesions, which were diagnosed by post I-131 treatment WBS. Complete disease remission was achieved in six (5.7 %) patients and all of them were in the WBSP group.

Conclusions

Metastatic lesion was not visualized on chest CT or F-18 FDG PET/CT in 6.7 % of DTC patients with pulmonary metastasis and the lesion was visualized only on post I-131 treatment WBS. Complete remission was achieved in 5.7 % of DTC patients with pulmonary metastasis and the cured metastases were non-visualizing or micronodular lesions on chest CT and demonstrated radioiodine avidity on post I-131 treatment WBS.     

131I whole body scintigraphy in thyroid cancer patients.

Iodine-131 is the most specific radionuclide to follow up patients with differentiated thyroid cancer (DTC). However there are some aspects that should be considered if 131I whole body scintigraphy (131I WBS) is performed. 1) Several prior conditions, including a bTSH above 30 mU/l and an urinary iodine excretion below 100-150 micrograms/g Crea, should be fulfilled. 2) Only about two thirds of metastases from DTC accumulate iodine. Therefore, in addition to 131I WBS, there is a need for other nonspecific tracers such as 99mTc Tetrofosmin WBS, 99mTc Sestamibi WBS or F-18 FDG PET to detect also iodine negative recurrences or metastases. There new tracers, especially F-18 FDG PET have demonstrated a very high detection rate of iodine negative metastases with mostly low differentiation. 3) The sensitivity of 131I WBS depends on the administered dose. Whereas the sensitivity of a diagnostic 131I WBS (up to 185 MBq) is below 60%, the value for a post-therapeutic 131I WBS (after 3700-7400 MBq) increases up to 75%. This means that in case of elevated serum thyroglobulin, iodine positive metastases cannot be excluded until WBS after 131I therapy is performed. 4) In patients with elevated serum thyroglobulin and/or known metastases, who are scheduled for 131I treatment, the question arises whether a diagnostic 131I WBS should be performed and if so, which dose should be administered to avoid thyroid stunning. There is evidence in the literature that the dose for a pre-therapeutic diagnostic 131I WBS should not exceed 74 MBq. 5) Despite the high specificity of 131I WBS, several pitfalls of iodine accumulation in non-malignant diseases and malignancies of other origin than thyroid cancer should be taken into account.     

Fluorine-18 fluorodeoxyglucose dual-head positron emission tomography in the detection of recurrent differentiated thyroid cancer: preliminary results

In the follow-up of patients with thyroid cancer, it may be very difficult to identify the site of recurrence in the presence of persistently elevated or rising thyroglobulin (Tg) levels and negative iodine-131 whole-body scintigraphy (WBS). The aim of this study was to assess the feasibility of employing fluorine-18 fluorodeoxyglucose and a dual-head positron emission tomography (PET) camera to detect recurrent thyroid cancer in patients with elevated Tg levels and negative 131I WBS. Eleven patients suspect of having recurrent thyroid cancer (five males, six females; mean age 47 years; range 26-73 years) were studied with both 131I WBS and FDG using a dual-head PET camera. The suspicion that these patients had recurrent thyroid cancer was based on elevated Tg levels. Thyroid stimulating hormone (TSH) and Tg levels as well as antibodies to Tg were measured 3 weeks after the withdrawal of tri-iodothyronine. In patients in whom pathological uptake was seen on the PET images but who had no signs of recurrent thyroid cancer on WBS, ultrasonography and/or computed tomography or magnetic resonance imaging was performed followed by fine-needle aspiration cytology. The mean Tg and TSH levels after discontinuation of L-thyroxine were 156 ng/ml (range 4-815 ng/ml) and 84 mU/l (range 43-159 mU/l), respectively. None of the patients had antibodies to thyroglobulin. In seven out of ten patients with negative 131I WBS, FDG PET showed focally increased uptake in the head and neck region. In one patient, the site of increased uptake on the PET images corresponded with the site of increased 131I uptake. Malignancies with a diameter less than 1 cm (n = 3) were not depicted by either CT or US. It is concluded that detection of recurrent thyroid cancer by means of FDG dual-head PET is feasible in patients with elevated Tg concentrations and negative 131I WBS. The results justify a prolongation of the study.     

Fluorine-18 fluorodeoxyglucose positron emission tomography and iodine-131 whole-body scintigraphy in the follow-up of differentiated thyroid cancer

Metastases of differentiated thyroid cancer may show different uptake patterns for fluorine-18 fluorodeoxyglucose and [¹³¹I]NaI. FDG positron emission tomography (PET), iodine-131 whole-body scintigraphy (¹³¹I WBS) and magnetic resonance imaging were performed in 58 unselected patients, and spiral computed tomography (CT) of the lung in 25 patients. Thirty-eight patients presented with papillary carcinomas, 15 patients with follicular carcinomas and five patients with variants of follicular carcinoma. Primary tumour stage (pT) was pT1 in 3, pT2 in 19, pT3 in 11 and pT4 in 25 cases. For the detection of metastases, FDG PET was found to have a sensitivity of 50%, ¹³¹I WBS a sensitivity of 61%, and the two methods combined a sensitivity of 86%. When FDG PET was limited to patients with elevated thyroglobulin (Tg) levels and negative ¹³¹I WBS, the sensitivity of this algorithm was 82%. Of the 21 patients with lymph node metastases, seven presented with FDG uptake but no iodine uptake. In four of them, a second FDG hot spot appeared in a lymph node metastasis of normal size. Five of the seven patients underwent surgery. None of the eight patients with pulmonary metastases smaller than 1 cm exhibited FDG uptake, while five of them had iodine uptake. All had positive results on spiral CT. In conclusion, FDG PET cannot be substituted for ¹³¹I WBS. If the Tg level is elevated and ¹³¹I WBS is negative, FDG PET can be used to detect lymph node metastases and complements anatomical imaging. A spiral CT of the lung is useful to exclude pulmonary metastases before planning a dissection of iodine-negative lymph node metastases. Received 2 May and in revised form 8 July 1997     

F-18 FDG PET/CT in the management of thyroid cancer

PURPOSE: There are approximately 32,000 new cases of thyroid carcinoma annually in the United States. F-18 FDG PET/CT has an established role in cancer management, including thyroid cancer, usually in patients who are thyroglobulin (Tg) positive/iodine negative. We reviewed our experience with F-18 FDG PET/CT in thyroid cancer, with an emphasis on correlation with Tg, and maximum standardized uptake values (SUV). We also analyzed the role of thyroid stimulating hormone (TSH) on PET/CT results. MATERIALS AND METHODS: This is a retrospective study (January 2003 to December 2006) of 76 patients with differentiated thyroid cancer, who had F-18 FDG PET/CT scans. There were 44 women and 32 men, with age range of 20 to 81 years (average, 51.1 +/- 18.1). The administered doses of F-18 FDG ranged from 396 to 717 MBq (15.8-19.4 mCi) (average, 566 +/- 74.8) (15.3 +/- 2). Reinterpretation of the imaging studies for accuracy and data analysis from medical records were performed. RESULTS: A total of 98 PET/CT scans were analyzed (59 patients had 1 scan, 12 patients had 2, and 5 patients had 3). PET/CT was 88.6% sensitive (95% CI: 78.-94.3) and 89.3% specific (95% CI: 71.9-97.1). Mean Tg level was 1203 ng/mL (range, 0.5-28,357) in patients with positive PET/CT and 9.72 ng/mL (range, 0.5-123.0) in patients with negative PET/CT scans (P = 0.0389). Mean SUV max was 10.8 (range, 2.5-32) in the thyroid bed recurrence/residual disease and 7.53 (range, 2.5-26.2) in metastatic lesions (P = 0.0114). Mean SUV max in recurrent/residual disease in patients with TSH 30 mIU/L was 8.1 (range, 2.6-32) (P = 0.2994). CONCLUSION: F-18 FDG PET/CT had excellent sensitivity (88.6%) and specificity (89.3%) in this patient population. Metastatic lesions were reliably identified, but were less F-18 FDG avid than recurrence/residual disease in the thyroid bed. TSH levels at the time of PET/CT did not appear to impact the FDG uptake in the lesions or the ability to detect disease. In the setting of high or rising levels of Tg, our study confirms that it is indicated to include PET/CT in the management of patients with differentiated thyroid cancer.     

分化型甲状腺癌转移灶18FDG符合线路联合131I显像的研究

目的探讨联合^18F-脱氧葡萄糖（FDG）符合线路SPECT（DHCI）与^131I全身扫描（whole body scans,WBS）显像检测甲状腺癌转移灶的价值。方法对45例手术＋131I治疗后DTC患者,行^131I WBS和^18FDG DHCI,并观察和记录病灶的数目和位置。结果45例甲状腺癌患者临床证实的148个病灶中,^18FDG符合线路共检出129个肿瘤转移灶,^131I WBS检出105个肿瘤转移灶,^18FDG DHCI和^131I WBS共同阳性的病灶为91个,两者联合检测出病灶143个。结论^18FDG DHCI和^131I WBS两种显像方法具有一定的互补性,并且两者联合检测较两者任一种方法具有更高的阳性率,两者联合检测具有扩大检测阳性病灶的作用。     

Clinical implication of F-18 FDG PET/CT for differentiated thyroid cancer in patients with negative diagnostic iodine-123 scan and elevated thyroglobulin

This study aims to investigate the usefulness of F-18 FDG PET/CT in differentiated thyroid cancer (DTC) with elevated serum thyroglobulin (Tg) but negative iodine-123 (I-123) scan.     

Comparison of 131I whole-body imaging, 131I SPECT/CT, and 18F-FDG PET/CT in the detection of metastatic thyroid cancer

Purpose

The aim of this study was to compare ¹³¹I whole-body scintigraphy (WBS), WBS with ¹³¹I single photon emission computed tomography/computed tomography (SPECT/CT), and ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT in the detection of distant metastases of differentiated thyroid cancer (DTC).

Methods

A total of 140 patients with 258 foci of suspected distant metastases were evaluated. ¹³¹I WBS, ¹³¹I SPECT/CT, and ¹⁸F-FDG PET/CT images were interpreted separately. The final diagnosis was obtained from histopathologic study, serum thyroglobulin level, other imaging modalities, and/or clinical follow-up.

Results

Of the 140 patients with 258 foci, 46 patients with 166 foci were diagnosed as positive for distant metastasis. The sensitivity, specificity, and diagnostic accuracy of each imaging modality were 65, 55, and 59%, respectively, for ¹³¹I WBS; 65, 95, and 85% for ¹³¹I SPECT/CT, respectively; and 61, 98, and 86%, respectively, for ¹⁸F-FDG PET/CT in patient-based analyses. Lesion-based analyses demonstrated that both SPECT/CT and PET/CT were superior to WBS (p<0.001) in all patient groups. SPECT/CT was superior to WBS and PET/CT (p<0.001) in patients who received a single challenge of radioiodine therapy, whereas PET/CT was superior to WBS (p=0.005) and SPECT/CT (p=0.013) in patients who received multiple challenges.

Conclusion

Both SPECT/CT and PET/CT demonstrated high diagnostic performance in detecting metastatic thyroid cancer. SPECT/CT was highly accurate in patients who underwent a single challenge of radioiodine therapy. In contrast, ¹⁸F-FDG PET/CT presented the highest diagnostic performance in patients who underwent multiple challenges of radioiodine therapy.     

Fluorine-18 fluorodeoxyglucose dual-head positron emission tomography in the detection of recurrent differentiated thyroid cancer: preliminary results

In the follow-up of patients with thyroid cancer, it may be very difficult to identify the site of recurrence in the presence of persistently elevated or rising thyroglobulin (Tg) levels and negative iodine-131 whole-body scintigraphy (WBS). The aim of this study was to assess the feasibility of employing fluorine-18 fluorodeoxyglucose and a dual-head positron emission tomography (PET) camera to detect recurrent thyroid cancer in patients with elevated Tg levels and negative ¹³¹I WBS. Eleven patients suspect of having recurrent thyroid cancer (five males, six females; mean age 47 years; range 26–73 years) were studied with both ¹³¹I WBS and FDG using a dual-head PET camera. The suspicion that these patients had recurrent thyroid cancer was based on elevated Tg levels. Thyroid stimulating hormone (TSH) and Tg levels as well as antibodies to Tg were measured 3 weeks after the withdrawal of tri-iodothyronine. In patients in whom pathological uptake was seen on the PET images but who had no signs of recurrent thyroid cancer on WBS, ultrasonography and/or computed tomography or magnetic resonance imaging was performed followed by fine-needle aspiration cytology. The mean Tg and TSH levels after discontinuation of l-thyroxine were 156 ng/ml (range 4–815 ng/ml) and 84 mU/l (range 43–159 mU/l), respectively. None of the patients had antibodies to thyroglobulin. In seven out of ten patients with negative ¹³¹I WBS, FDG PET showed focally increased uptake in the head and neck region. In one patient, the site of increased uptake on the PET images corresponded with the site of increased ¹³¹I uptake. Malignancies with a diameter less than 1 cm (n=3) were not depicted by either CT or US. It is concluded that detection of recurrent thyroid cancer by means of FDG dual-head PET is feasible in patients with elevated Tg concentrations and negative ¹³¹I WBS. The results justify a prolongation of the study. Received 1 May and in revised form 11 June 1999     

Value of 124I-PET/CT in staging of patients with differentiated thyroid cancer

The aim of this study is to evaluate the clinical significance of ¹²⁴I positron emission tomography (PET) using a combined PET/CT tomograph in patients with differentiated thyroid carcinoma and to compare the PET/CT results with ¹³¹I whole-body scintigraphy (WBS), dedicated PET and CT alone. Twelve thyroid cancer patients were referred for diagnostic workup and entered complete clinical evaluation, including histology, cytology, thyroglobulin level, ultrasonography, fluorine-18 fluorodeoxyglucose (FDG)-PET, FDG-PET/CT and CT. Lesion-based evaluation showed a lesion delectability of 56, 87 and 100% for CT, ¹²⁴I-PET, and combined ¹²⁴I-PET/CT imaging, respectively. Lesion delectability of ¹³¹I-WBS was 83%. We conclude that ¹²⁴I-PET/CT imaging is a promising technique to improve treatment planning in thyroid cancer. It is particularly valuable in patients suffering from advanced differentiated thyroid cancer prior to radio-iodine therapy and in patients with suspected recurrence and potential metastatic disease.     

~(131)I SPECT/CT断层融合显像在分化型甲状腺癌中的临床价值

目的：探讨131^I SPECT/CT断层融合显像在分化型甲状腺癌诊治检测中的临床价值。材料和方法：选择术后病理证实并接受131^I治疗的分化型甲状腺癌（DTC）患者97例,行131^I全身扫描（131^I-WBS）和病灶部位的SPECT断层加同机CT融合显像。将131^I-WBS与断层融合图像进行对比分析,探讨断层融合显像的特点与临床价值。结果：97例分化型甲癌患者共进行131^I-WBS251次,断层融合显像102次,每例患者至少行一次断层融合显像。与131^I-WBS比较,断层融合显像有如下特点：能够获得直观的断层融合显像和三维立体图像;②发现更多的病灶;③更准确地判断病变部位;④定位CT可以发现无摄碘功能的病灶;⑤鉴别病灶和生理显影或污染。结论：131^I SPECT/CT断层融合显像可以直观病变立体形态、大小、摄取程度和毗邻关系,在鉴别病灶与生理显像或污染、确定病灶是否有摄碘功能方面有重要价值,是131^I-WBS的重要补充。     

Comparison of 11C-methionine PET and 18F-fluorodeoxyglucose PET in differentiated thyroid cancer

BACKGROUND: The purpose of this prospective study is to evaluate the possibility of 11C-methionine (Met) PET compared with 18F-fluorodeoxyglucose (FDG) PET for the detection of recurrent or metastatic disease in patients with differentiated thyroid cancer (DTC). MATERIALS AND METHODS: Twenty patients with clinical suspicion of recurrent DTC but negative posttreatment 131I-whole body scans were included in the study. Both 11C-Met PET and 18F-FDG PET were performed within 1 week. PET images were analyzed by two independent and blinded physicians using visual and standardized uptake value analysis. PET results were also correlated with radiologic and/or cytological investigations. RESULTS: Thirteen patients showed concordant findings on both PET scans: six patients showed uptake and in seven no uptake was observed. In six of the seven patients without Met and FDG uptake, additional MRI and ultrasound-guided fine needle aspiration cytology of the lymph nodes revealed inconclusive or negative results. Six patients showed discordant findings on the PET scans: in three patients uptake was only observed on the Met PET, confirmed by MRI in one. In three patients lesions were seen on the FDG PET, confirmed by computed tomography or ultrasound-guided fine needle aspiration cytology. However, those lesions were not compatible with the lesions seen on the Met PET. In general, FDG uptake appeared to be higher than Met uptake, but was not significant (P=0.075). CONCLUSION: This study shows that imaging using radiolabeled amino acids is feasible in DTC. For now, 11C-Met PET has not proven to be superior to 18F-FDG PET in the detection of recurrent disease in DTC. Complementary uptake of Met and FDG has, however, been observed, which has to be further clarified and long-term follow-up is needed to define the true clinical value of the 11C-Met PET, and possible other amino acids tracers.     

The influence of thyroglobulin on functional imaging in differentiated thyroid cancer

AIM: Recombinant human thyroid stimulating hormone (rhTSH) for an exogenous stimulation of TSH and consequent thyroglobulin (hTG) synthesis has reinitiated a discussion about the usefulness of diagnostic procedures for the follow-up of differentiated thyroid cancer (DTC). METHOD: Fifty consecutive patients with DTC who received whole-body iodine scintigraphy (WBS) and positron emission tomography (PET) were evaluated. RESULTS: The work-up was normal in 18/50. In 32 patients, functional imaging detected DTC. In 44% exogenous TSH stimulation with rhTSH was used and thyroxin was withdrawn in the others. The hTG under stimulation ranged from 0.8 to 5.004 ng x ml(-1). It was below 2 ng x ml(-1) in four (12.5%) patients. In total, 91 tumour sites were identified by positron emission tomography (PET) and 47 sites by WBS. PET and WBS showed corresponding uptake in 38% of lymph node, 48% of parenchymal and 43% of bone metastases. PET detected additional 53% of lymph node (WBS 9%), 38% of parenchymal (WBS 14%) and 28.5% of bone metastases. CONCLUSION: It is concluded that PET is more sensitive than WBS for the detection of DTC. The follow-up of DTC patients with hTG levels alone misses a significant number of true positive cases. Its use should therefore be restricted to selected low risk patients only.     

Diagnostic values of F-18 FDG PET or PET/CT,CT, and US for Preoperative Lymph Node Staging in Thyroid Cancer: A Network Meta-Analysis

ObjectiveThis study compared the diagnostic performance of three different imaging modalities for preoperative lymph node (LN) staging in thyroid cancer patients, using a network meta-analysis (NMA).MethodsPubMed and Embase were searched to identify studies evaluating the performance of F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET or PET/CT), computed tomography (CT), and ultrasonography (US) for preoperative LN staging in thyroid cancer patients. The NMA included both patient- and lesion-based analyses. The surface under the cumulative ranking curve (SUCRA) values was used to decide on the most effective diagnostic method.ResultsA total of 3,571 patients from 19 direct comparison studies using three different imaging modalities for preoperative LN staging in thyroid cancer patients were included. US showed the highest SUCRA values for positive predictive values (PPV), negative predictive values (NPV), and accuracy in detection of all cervical LN metastasis. F-18 FDG PET or PET/CT and US showed the highest SUCRA values for PPV and sensitivity, respectively, for central LN, and the highest SUCRA value of specificity and sensitivity, respectively, for lateral LN.ConclusionThe results from this NMA indicate that F-18 FDG PET or PET/CT, CT, and US have complementary diagnostic roles for preoperative staging in thyroid cancer patients.Advances in knowledgeUsing NMA, we comprehensively compared the different diagnostic values and limitations of F-18 FDG PET or PET/CT, CT, and US for the preoperative LN staging in thyroid cancer patients.     

PET in the follow-up of differentiated thyroid cancer

Fluorine-18-fluorodeoxyglucose (FDG) PET has become an increasingly important functional imaging modality in clinical oncology. This article will focus primarily on the role of FDG PET during treatment and follow-up of thyroid cancer. The major role of FDG PET is in patients with elevated thyroglobulin (Tg) levels where thyroid cancer tissue does not concentrate radioiodine rendering false-negative results on I-131 scanning. FDG PET imaging takes advantage of the increased uptake of FDG in cancer cells and is sensitive (60-94%) to the detection of recurrent or metastatic cancer in patients who have negative radioiodine scans. The specificity (25-90%) of PET imaging is relatively less than its sensitivity because some inflammatory processes avidly accumulate FDG. PET can fail to localize the tumour sites in some patients with well-differentiated thyroid cancer that retain good iodine ability. This can result the well recognized phenomenon of "flip-flop" depending on the differentiation of the thyroid cancer. Several studies have documented the higher accuracy of PET, compared with other imaging modalities in the evaluation of patients with recurrent or metastatic differentiated thyroid cancer. The value of thyroid stimulating hormone stimulation for FDG PET has recently been reported. Therefore, if available, this method should be considered in all patients of differentiated thyroid cancer with suspected recurrence and/or metastasis.     

Diagnostic utility of PETCT in thyroid malignancies: an update

The primary clinical application of ¹⁸F FDG PET/CT (¹⁸Fluorine labeled flurodeoxyglucose positron emission tomography/computed tomography) in differentiated thyroid carcinoma is in the identification of active disease in thyroglobulin (Tg) positive (>10 ng/ml), whole body iodine scan negative patients. The impact of FDG PET/CT in diagnosis, surveillance, cure, and progression-free survival of differentiated thyroid carcinoma patients remains to be seen. Five main indications of FDG PET/CT in thyroid cancer have been recommended by revised American thyroid association guidelines 2009. This review aims to provide a complete picture of PET imaging in thyroid malignancies and enumerates each indication with literature review. This review also highlights recent advances in targeted molecular imaging. Currently differentiated thyroid cancer is best imaged using conventional single photon emission computed tomography-based radioiodine tracers (¹²³I/¹³¹I). Although the utility of FDG PET in well differentiated thyroid cancer patients who are iodine negative but with raised Tg is well established, evidence is emerging on the advantages of FDG PET/CT in other histological types of thyroid malignancy, such as Hurthle cell, medullary, and the anaplastic malignancies. Novel PET radiotracers, such as ¹²⁴Iodine (¹²⁴I), ¹⁸F-DOPA (3,4-dihydroxy-l-phenylalanine), and ⁶⁸Ga-DOTA peptides are revolutionizing the way thyroid malignancies are imaged. Newer concepts on targeted molecular imaging and theranostics are ushering in new possibilities for imaging and treating thyroid cancer.     

分化型甲状腺癌~(18)F-FDG PET显像的临床应用

低分化型甲状腺癌细胞摄取碘能力的下降或丧失导致 1 31 　 I WBS(全身显像 )假阴性 (约 2 0 % ) ,高水平的血清 Tg(甲状腺球蛋白 )只能说明有分化型甲状腺癌 (DTC)的复发或转移 ,不能确定 DTC复发或转移的具体位置 ,而低分化型甲状腺癌正是 DTC病人死亡的主要类型。本文主要探讨 1 8F- FDG(1 8F-氟代脱氧葡萄糖 ) PET显像在1 31　 I的 WBS阴性而血清 Tg水平增高的 DTC病人中鉴别复发和转移的应用以及评价 DTC病人预后的价值 ,当嗜1 8F- FDG肿瘤显示的体积大于 12 5 m L 或 FDG标准摄取值大于 10 g/ m L 时 ,病人的预后不良。     

Detection of bone metastases in thyroid cancer patients: bone scintigraphy or 18F-FDG PET?

BACKGROUND: Similar to the situation in other tumour types, it is currently unclear whether fluorodeoxyglucose (FDG) positron emission tomography (PET) is adequate in the detection of bone metastases of thyroid cancer. The purpose of this retrospective study was to evaluate the performance of bone scans in comparison with FDG PET in the detection of bone metastases in patients with differentiated thyroid cancer (DTC). MATERIALS AND METHODS: Twenty-four patients had undergone both FDG PET and bone scans within 6 months because of suspected bone metastases. All scans were re-evaluated using all available additional imaging and clinical data for verification. Scan findings were scored as positive, negative or doubtful. RESULTS: Bone metastases were present in eight of 24 (33%) patients. Only bone scintigraphy but not FDG PET suggested the presence of bone metastases in three patients, all confirmed with magnetic resonance imaging (MRI)/X-ray. Five patients were identified with bone metastases on both bone scan and FDG PET, which was confirmed by computed tomography (CT)/MRI/X-ray in four. Five patients had doubtful findings on bone scans whereas FDG PET scans were negative. MRI showed degenerative disorders in two of five and was normal in two. Eleven patients had both a negative bone scan and FDG PET scan. CONCLUSION: In three of eight (38%) thyroid cancer patients bone metastases were only identified on bone scans. Therefore, bone scans are still valuable in detecting bone metastases in patients with DTC and can not be replaced by FDG PET.     

Fluorine-18 fluorodeoxyglucose positron emission tomography in the follow-up of differentiated thyroid cancer

Whole-body fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging was performed during the follow-up of 33 patients suffering from differentiated thyroid cancer. Among them there were 26 patients with papillary and seven with follicular tumours. Primary tumour stage (pT) was pT1 in six cases, pT2 in eight cases, pT3 in three cases and pT4 in 14 cases. FDG PET was normal in 18 patients. In three patients a slightly increased metabolism was observed in the thyroid bed, assumed to be related to remnant tissue. In one case local recurrence, in ten cases lymph node metastases (one false-positive, caused by sarcoidosis) and in three cases distant metastases were found with FDG PET. In comparison with whole-body scintigraphy using iodine-131 (WBS) there were a lot of discrepancies in imaging results. Whereas three patients had distant metastases (proven with¹³¹I) and a negative FDG PET, in four cases¹³¹I-negative lymph node metastases were detectable with PET. Even in the patients with concordant staging, differences between¹³¹I and FDG were observed as to the exact lesion localization. Therefore, a coexistence of¹³¹I-positive/FDG-negative,¹³¹I-negative/FDG-positive and¹³¹I-positive/FDG-positive malignant tissue can be assumed in these patients. A higher correlation of FDG PET was observed with hexakis (2-methoxyisobutylisonitrile) technetium-99m (I) (MIBI) scintigraphy (performed in 20 cases) than with WBS. In highly differentiated tumours¹³¹I scintigraphy had a high sensitivity, whereas in poorly differentiated carcinomas FDG PET was superior. The clinical use of FDG PET can be recommended in all cases of suspected or proven recurrence and/or metastases of differentiated thyroid cancer and is particularly useful in cases with elevated serum thyroglobulin levels and negative WBS.     

分化型甲状腺癌胸部131I显像假阳性分析

分化型甲状腺癌（DTC）131I-全身显像（WBS）时除在功能性甲状腺组织显影外,非甲状腺组织假阳性病变也常有不同程度131I摄取而显影。笔者就DTC患者胸部131I显像假阳性的原因及其机制进行分析,以期为临床DTC患者的诊疗提供必要帮助。