Diagnostic value of FDG PET and salivary gland scintigraphy for parotid tumors

PURPOSE: The purpose of this study was to examine the diagnostic value of the combination of F-18 fluorodeoxyglucose (FDG) PET and Tc-99m pertechnetate salivary gland scintigraphy in parotid tumors. MATERIALS AND METHODS: Seventy-two patients with benign parotid gland tumors (n = 52), malignant parotid tumors (n = 12), and inflammation (n = 8) underwent both FDG PET and salivary gland scintigraphy within 1 week, and 66 of the patients also underwent gallium scintigraphy. All patients were negative on their first fine-needle aspiration (FNA). RESULTS: Malignant parotid tumors showed significantly higher FDG uptake (standard uptake values [SUVs]) than both benign tumors and inflammation, except in Warthin's tumor (5.82 +/- 3.95 vs. 2.07 +/- 1.33; P <0.01). Although the SUV values of Warthin's tumor and malignant parotid tumors overlapped somewhat, Warthin's tumor did demonstrate increased radiotracer uptake, and it was reliably distinguished from other parotid gland tumors by the use of salivary gland scintigraphy. Considering a SUV value >3 as being positive for malignancy and excluding Warthin's tumor on the basis of salivary gland scintigraphy, sensitivity and specificity of FDG PET were 75% and 80%, respectively. These results were superior to those of gallium scintigraphy (58% and 72%, respectively). CONCLUSIONS: Although the diagnostic value of FDG PET in the differentiation of malignant from benign parotid gland tumors was limited because of the high FDG uptake in some benign tumors, and particularly pleomorphic adenomas, combining salivary gland scintigraphy with FDG PET may help to negate this drawback, and this combination may be a more promising approach for differentiation of various parotid gland tumors in patients compared with nondiagnostic needle aspiration.     

Warthin's tumor of parotid gland on Tc-99m pertechnetate scintigraphy with lemon juice stimulation: Tc-99m uptake, size, and pathologic correlation

The aim of this study was to evaluate the usefulness of technetium-99m (Tc-99m) pertechnetate scintigraphy with lemon juice stimulation in the diagnosis of Warthin's tumor and its correlation with Tc-99m uptake, tumor size, and histologic subtype. Tc-99m pertechnetate scintigraphy before and after lemon juice stimulation and pathologic specimens of 34 Warthin's tumors and 47 non-Warthin's lesions were retrospectively evaluated. Tc-99m uptake of Warthin's tumors before and after stimulation was visually graded as follows: absent; indeterminate; low grade; definite; and strong. Tumor size was defined as maximum diameter of the tumor measured from the surgical specimen. Warthin's tumors were classified into three histologic subtypes according to the ratio of epithelial and lymphoid stromal components: predominant epithelial; intermediate; and low-grade epithelial types. Eighteen of 34 (53%) Warthin's tumors and one benign lymphoepithelial cyst showed higher uptake than that of the normal parotid gland on Tc-99m scintigraphy before lemon juice stimulation. Thirty-two of the 34 (94%) Warthin's tumors, one benign lymphoepithelial cyst, one pleomorphic adenoma, and one oncocytoma revealed higher uptake than that of the normal parotid gland on Tc-99m scintigraphy after lemon juice stimulation. The mean size was 37 mm in strong uptake Warthin's tumors, 24 mm in definite uptake tumors, 19 mm in low-grade uptake tumors, and 12 mm in low-grade uptake tumors excluding those tumors with large cystic component. There was a significant correlation between tumor size and degree of Tc-99m uptake after lemon juice stimulation. However, there was no correlation between histologic subtype and Tc-99m uptake, and histologic subtype and tumor size in Warthin's tumors. Our study concludes that Tc-99m pertechnetate scintigraphy with lemon juice stimulation is useful for the detection and diagnosis of Warthin's tumor. The degree of uptake in Warthin's tumor on Tc-99m scintigraphy with lemon juice stimulation depends mainly on tumor size and the presence of large cystic component in it.     

Comparison of 18F-fluoride PET/CT, 18F-FDG PET/CT and bone scintigraphy (planar and SPECT) in detection of bone metastases of differentiated thyroid cancer: a pilot study

Objective:

We compared the efficacies of ¹⁸F-fluoride positron emission tomography (¹⁸F-fluoride PET)/CT, ¹⁸F-fludeoxyglucose PET (¹⁸F-FDG PET)/CT, and ^99mTc bone scintigraphy [planar and single photon emission CT (SPECT)] for the detection of bone metastases in patients with differentiated thyroid carcinoma (DTC).

Methods:

We examined 11 patients (8 females and 3 males; mean age ± standard deviation, 61.9 ± 8.7 years) with DTC who had been suspected of having bone metastases after total thyroidectomy and were hospitalized to be given ¹³¹I therapy. Bone metastases were verified either when positive findings were obtained on both ¹³¹I scintigraphy and CT or when MRI findings were positive if MRI was performed.

Results:

Metastases were confirmed in 24 (13.6%) of 176 bone segments in 9 (81.8%) of the 11 patients. The sensitivities of ¹⁸F-fluoride PET/CT and ^99mTc bone scintigraphy (SPECT) were significantly higher than those of ¹⁸F-FDG PET/CT and ^99mTc bone scintigraphy (planar) (p < 0.05). The accuracies of ¹⁸F-fluoride PET/CT and ^99mTc bone scintigraphy (SPECT) were significantly higher than that of ^99mTc bone scintigraphy (planar) (p < 0.05).

Conclusion:

The sensitivity and accuracy of ¹⁸F-fluoride PET/CT for the detection of bone metastases of DTC are significantly higher than those of ^99mTc bone scintigraphy (planar). However, the sensitivity and accuracy of ^99mTc bone scintigraphy (planar) are improved near to those of ¹⁸F-fluoride PET/CT when SPECT is added to a planar scan. The sensitivity of ¹⁸F-FDG PET/CT is significantly lower than that of ¹⁸F-fluoride PET/CT or ^99mTc bone scintigraphy (SPECT).

Advances in knowledge:

This article has demonstrated first the high efficacy of ¹⁸F-fluoride PET/CT for the detection of bone metastases of DTC.Differentiated thyroid carcinoma (DTC) shows a relatively good prognosis compared with carcinomas of other organs, and the 10-year survival rate of DTC is >80% because of treatments such as total thyroidectomy and ablation of remnants with radioiodine.¹ However, metastases of DTC develop in 7–23% of patients; the distant metastases occur commonly in the lungs, bones and brain, and the bones are the second most common site of metastases of DTC.² Bone scintigraphy using ^99mTc-labelled phosphate compounds [^99mTc-methylene diphosphonate (^99mTc-MDP) or ^99mTc-hydroxymethylene diphosphonate (^99mTc-HMDP)] has been widely used for detecting and evaluating bone metastases of various kinds of carcinomas because of its overall high sensitivity and the easy evaluation of the entire skeleton.³ However, there were often false-positive cases in ^99mTc bone scintigraphy, because degenerative or inflammatory foci were often confused with metastatic lesions. The addition of single photon emission CT (SPECT) to planar acquisition of ^99mTc bone scintigraphy has been shown to exhibit a beneficial effect on the detection and evaluation of bone metastases.^4–6 Skeletal imaging by ¹⁸F-fludeoxyglucose positron emission tomography (¹⁸F-FDG PET)/CT has been shown to be useful in the detection of bone metastases of various carcinomas including DTC.⁷Previously, we compared the efficacies of ¹⁸F-FDG PET and planar ^99mTc bone scintigraphy for the detection of bone metastases in patients with DTC.⁸ We found that the specificity and the overall accuracy of ¹⁸F-FDG PET for the detection of bone metastases in patients with DTC were higher than those of planar ^99mTc bone scintigraphy, whereas the difference in the sensitivity of both examinations was not statistically significant, and concluded that ¹⁸F-FDG PET is superior to planar ^99mTc bone scintigraphy because of its lower incidence of false-positive results in the detection of bone metastases of DTC.⁸¹⁸F-fluoride is a positron-emitting bone-seeking radiotracer, which has a similar uptake mechanism to ^99mTc-MDP and ^99mTc-HMDP. As the availability of PET systems was increasing, ¹⁸F-fluoride has been used for skeletal PET imaging since 1990s. PET or PET/CT with ¹⁸F-fluoride have been shown to be more sensitive than planar ^99mTc bone scintigraphy for the detection of bone metastases of lung,⁹ breast,^10,11 hepatocellular,¹² prostate,^11,13,14 colon and bladder¹¹ cancers. However, to the best of our knowledge, there have been no systematic comparative studies on the efficacies of ¹⁸F-fluoride PET/CT, ¹⁸F-FDG PET/CT and ^99mTc bone scintigraphy (planar and SPECT) for the detection of bone metastases of DTC. This study was conducted to compare ¹⁸F-fluoride PET/CT, ¹⁸F-FDG PET/CT and ^99mTc bone scintigraphy (planar and SPECT) in the detection of bone metastases of DTC.     

Solitary muscular sarcoidosis: CT,MRI, and scintigraphic characteristics

Scintigraphy using gallium-67 (⁶⁷Ga) citrate and penvaralent technetium-99m dimercaptosuccinic acid {[^99mTc(V)]DMSA} and other radiological examinations were performed in three patients with solitary muscular sarcoidosis who had tumor-like muscular lesions. Although distinction from other invasive soft tissue tumors was difficult using plain and enhanced computed tomography and magnetic resonance imaging, marked uptake of⁶⁷Ga and moderate uptake of [^99mTc(V)]DMSA were shown at the sites of granulomatous inflammatory lesions of sarcoidosis. Both⁶⁷Ga and [^99mTc(V)]DMSA scintigraphy could be of value in the diagnosis and detection of distribution of granulomas of sarcoidosis in the soft tissue and in determining the appropriate region for biopsy.     

Prospective comparison of 18F-FDG PET with conventional imaging modalities (MRI, CT, and 67Ga scintigraphy) in assessment of combined intraarterial chemotherapy and radiotherapy for head and neck carcinoma.

To preserve the oral organs and functions in patients with head and neck carcinoma, accurate determination of the appropriate treatment after neoadjuvant chemotherapy and radiotherapy is of critical importance. We evaluated the diagnostic accuracy of (18)F-FDG PET relative to that of other conventional imaging modalities in the assessment of therapeutic response after combined intraarterial chemotherapy and radiotherapy as an organ preservation protocol. METHODS: The study was prospectively performed on 23 consecutive patients with head and neck squamous cell carcinoma who completed the treatment regimen and underwent 2 (18)F-FDG PET studies before and after neoadjuvant chemoradiotherapy. (67)Ga scintigraphy (only before therapy) as well as MRI and CT (both before and after therapy) were also performed. All images were blindly and independently interpreted without knowledge of histologic findings. The level of confidence in image interpretation was graded by means of a 5-point rating system (0 = definitely no tumor to 4 = definite tumor). RESULTS: Before treatment, (18)F-FDG PET detected primary tumors in all 23 patients and was more sensitive (100%) than MRI (18/23; 78.3%), CT (15/22; 68.2%), and (67)Ga scintigraphy (8/20; 40%), with a confidence level of 3 or 4 as a positive tumor finding. After chemoradiotherapy, residual tumors were histologically confirmed in 4 patients (pathologic complete response rate, 19/23; 82.6%). Although posttreatment (18)F-FDG PET showed almost equal sensitivity (4/4; 100%) compared with MRI (3/3; 100%) or CT (3/4; 75%), its specificity (17/19; 89.5%) was superior to MRI (7/17, 41.2%) and to CT (10/17; 58.8%) for primary lesions. Regarding metastases to neck lymph nodes, only specificity for posttreatment images was calculated because no metastasis was confirmed in any patients after treatment. Six subjects had (18)F-FDG PET-positive lymph nodes, which had pathologically no tumor cells and suggested an inflammatory reactive change after therapy. Therefore, the specificity of posttreatment (18)F-FDG PET (17/23; 73.9%) was almost identical to that of MRI (17/20; 85%) and CT (16/21; 76.2%) for neck metastasis. With combined chemoradiotherapy monitored with (18)F-FDG PET, 8 patients avoided surgery and the remaining 15 patients underwent a reduced form of surgery. CONCLUSION: (18)F-FDG PET facilitates differentiation of residual tumors from treatment-related changes after chemoradiotherapy, which may be occasionally difficult to characterize by anatomic images. (18)F-FDG PET has a clinical impact for the management of patients with head and neck cancers after neoadjuvant chemoradiotherapy by optimizing surgical treatment for each patient and contributes to the improvement of the patient's quality of life.     

Usefulness of fasting 18F-FDG PET in identification of cardiac sarcoidosis.

Cardiac PET using (18)F-FDG under fasting conditions (fasting (18)F-FDG PET) is a promising technique for identification of cardiac sarcoidosis and assessment of disease activity. The aim of this study was to investigate the usefulness of fasting (18)F-FDG PET in detecting inflammatory lesions of cardiac sarcoidosis from a pathophysiologic standpoint. METHODS: Twenty-two patients with systemic sarcoidosis were classified into 2 groups of 11 each according to the presence or absence of sarcoid heart disease. Cardiac sarcoidosis was diagnosed according to the Japanese Ministry of Health and Welfare guidelines for diagnosing cardiac sarcoidosis with the exception of scintigraphic criteria. Nuclear cardiac imaging with fasting (18)F-FDG PET, (99m)Tc-methoxyisobutylisonitrile ((99m)Tc-MIBI) SPECT, and (67)Ga scintigraphy were performed in all patients. PET and SPECT images were divided into 13 myocardial segments and the standardized uptake value (SUV) of (18)F-FDG was calculated and defect scores (DS) for (99m)Tc-MIBI uptake were assessed for each segment. The total SUV (T-SUV) and total DS (TDS) were calculated as the sum of measurements for all 13 segments, and the diagnostic accuracy of fasting (18)F-FDG PET was compared with that of the other nuclear imaging modalities. In addition, pathophysiologic relationships between inflammatory activity and myocardial damage were examined by segmental comparative study using the SUV and DS. RESULTS: In patients with cardiac sarcoidosis, fasting (18)F-FDG PET revealed a higher frequency of abnormal myocardial segments than (99m)Tc-MIBI SPECT (mean number of abnormal segments per patient: 6.6 +/- 3.0 vs. 3.0 +/- 3.2 [mean +/- SD], P < 0.05). The sensitivity of fasting (18)F-FDG PET in detecting cardiac sarcoidosis was 100%, significantly higher than that of (99m)Tc-MIBI SPECT (63.6%) or (67)Ga scintigraphy (36.3%). The accuracy of fasting (18)F-FDG PET was significantly higher than (67)Ga scintigraphy. The T-SUV demonstrated a good linear correlation with serum angiotensin-converting enzyme levels (r = 0.83, P < 0.01), and the TDS showed a significant negative correlation with the left ventricular ejection fraction (r = -0.82, P < 0.01). In abnormal myocardial segments on the nuclear scan, the SUV showed a significant negative correlation with the DS (r = -0.63, P < 0.0001). CONCLUSION: This study suggests that fasting (18)F-FDG PET can detect the early stage of cardiac sarcoidosis, in which fewer perfusion abnormalities and high inflammatory activity are noted, before advanced myocardial impairment.     

不同能量放射性核素在PET/CT及SPECT采集中的相互影响

目的 利用模型探讨99TcmO4-与18F-氟脱氧葡萄糖(FDG)在图像采集中的相互影响,讨论同一患者是否可以同日分别采用PET/CT及SPECT两种仪器行高低两种能量放射性核素显像.材料与方法 利用统一规格、相同容积( 500ml)的5个塑料瓶(编号A、B、C、D、E),其内均注入500ml蒸馏水制作成模型.A瓶注入0.5mCi 18F-FDG行PET/CT显像;B瓶注入1mCi99TcmO4-行SPECT显像;C瓶内同时注入混合好的0.5mCi18F-FDG和1mCi99TcmO4-;D瓶内先注入1mCi99TcmO4-后再注入0.5mCi18F-FDG;E瓶先注入0.5mCi18F-FDG后再注入1mCi99TcmO4-.然后对C、D、E瓶分别行PET/CT显像和SPECT显像,并判断图像效果.结果 A瓶PET/CT显像和B瓶SPECT显像图像效果为1级;C、D瓶SPECT及PET/CT显像图像均为2级;E瓶SPECT显像图像为3级,PET/CT显像图像为1级.结论 同时加入18F-FDG和99TcmO4-对PET/CT和SPECT图像质量均有影响.先加入18F-FDG后加入99TcmO4-对PET/CT图像质量影响小,但SPECT图像不能分辨.先加入99TcmO4-后加入18F-FDG对PET/CT和SPECT图像质量均有影响.     

Efficacy of <Superscript>99m</Superscript>Tc pertechnetate and <Superscript>131</Superscript>I radioisotope therapy in sodium/iodide symporter (NIS)-expressing neuroendocrine tumors in vivo

Purpose There is growing interest in the human sodium/iodide symporter (NIS) gene both as a molecular imaging reporter gene and as a therapeutic gene. Here, we show the feasibility of radioisotope therapy of neuroendocrine tumors. As a separate application of NIS gene transfer, we image NIS-expressing tumors with pinhole SPECT in living subjects. Methods Biodistribution studies and in vivo therapy experiments were performed in nude mice carrying stably NIS-expressing neuroendocrine tumor xenografts following i.v. injection of ¹³¹I and ^99mTc pertechnetate. To show the usefulness of NIS as an imaging reporter gene, ^99mTc pertechnetate uptake was imaged in vivo using a clinical gamma camera in combination with a custom-made single pinhole collimator, followed by SPECT/small animal MRI data coregistration. Results NIS-expressing neuroendocrine tumors strongly accumulated ¹³¹I and ^99mTc pertechnetate, as did thyroid, stomach, and salivary gland. The volume of NIS-expressing neuroendocrine tumors decreased significantly after therapeutic administration of ¹³¹I or ^99mTc pertechnetate, whereas control tumors continued to grow. NIS-mediated uptake of ^99mTc pertechnetate could be imaged in vivo at high resolution with a clinical gamma camera equipped with a custom-made single pinhole collimator. High-resolution functional and morphologic information could be combined in a single three-dimensional data set by coregistration of SPECT and small animal MRI data. Lastly, we demonstrated a therapeutic effect of ^99mTc pertechnetate on NIS-expressing neuroendocrine tumors in cell culture and, for the first time, in vivo, thought to be due to emitted Auger and conversion electrons. Conclusions NIS-expressing neuroendocrine tumors efficiently concentrate radioisotopes, allowing for in vivo high-resolution small animal SPECT imaging as well as rendering possible successful radioisotope therapy of neuroendocrine tumors.     

Pictorial review of <Superscript>18</Superscript>F-FDG PET/CT findings in musculoskeletal lesions

We herein reviewed ¹⁸F-fluoro-2-deoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/computed tomography (CT) findings in a number of musculoskeletal lesions including malignant tumors, benign tumors, and tumor-like lesions with correlations to other radiographic imaging modalities, and described the diversity of the ¹⁸F-FDG PET/CT findings of this entity. Malignant primary musculoskeletal tumors are typically ¹⁸F-FDG avid, whereas low-grade malignant tumors show mild uptake. Benign musculoskeletal tumors generally show a faint uptake of ¹⁸F-FDG, and tumor-like conditions also display various uptake patterns of ¹⁸F-FDG. Although musculoskeletal tumors show various uptakes of ¹⁸F-FDG on PET/CT, its addition to morphological imaging modalities such as CT and MRI is useful for the characterization and differentiation of musculoskeletal lesions.     

<Superscript>18</Superscript>p-FDG PET is superior to<Superscript>67</Superscript>Ga SPECT in the staging of non-Hodgkin’s lymphoma

OBJECTIVE: Our study aims to compare diagnostic accuracy between 18F-FDG PET and 67Ga SPECT in the staging of non-Hodgkin's lymphoma. METHODS: Twenty-eight patients with non-Hodgkin's lymphoma, underwent 18F-FDG PET, 67Ga SPECT and CT for the pretreatment staging of malignant lymphoma between August 1999 and March 2002. 18F-FDG PET imaging was obtained 60 minutes after the intravenous administration of 185 MBq of 18F-FDG. 67Ga SPECT imaging was obtained 2 days after the intravenous administration of 148 MBq of 67Ga. 18F-FDG PET and 67Ga SPECT were performed within one month. Both imagings were performed on the area from the neck to the pelvis. The 18F-FDG PET and 67Ga SPECT findings were compared with the CT findings and the clinical course. RESULTS: Sixty-six nodal lesions were clinically confirmed. Of these, 32 were identified by both 18F-FDG PET and 67Ga SPECT. The remaining 34 lesions were identified only by 18F-FDG PET. The mean (+/- SD) sizes' of the nodes were 34.7 +/- 32.4 mm for 18F-FDG-positive and 67Ga-positive lesions and 15.7 +/- 8.3 mm for 18F-FDG-positive and 67Ga-negative lesions (p < 0.001). Of the 23 extranodal lesions, 12 were identified by both 18F-FDG PET and 67Ga SPECT, whereas 6 lesions were identified by only 18F-FDG PET. Five lesions were not identified by either technique. No 18F-FDG-negative but 67Ga-positive nodal or extranodal lesions were observed. The difference in findings between the two studies is related to the difference in the size but not in the histology or site of the lesions. CONCLUSION: 18F-FDG PET detected significantly more lesions particularly small lesions than 67Ga SPECT. Thus, 18F-FDG PET is considered to be superior to 67Ga SPECT in the staging of non-Hodgkin' s lymphoma.     

Comparison of magnetic resonance imaging and 67gallium scintigraphy in the evaluation of posttherapeutic residual mediastinal mass in the patients with Hodgkin's lymphoma

IntroductionDetection of residual disease following the completion of primary treatment in Hodgkin's lymphoma (HL) patients diagnosed with mediastinal tumor mass has an exceptional importance in the assessment of therapeutic response. Magnetic resonance imaging (MRI) and ⁶⁷gallium (⁶⁷Ga) scintigraphy can be used to identify active tumor tissue in the mediastinal residuum.AimsTo evaluate: the accuracy of MRI and ⁶⁷Ga scintigraphy in the prediction of clinical HL relapse/progression; congruence of findings and the probability of mediastinal disease relapse/progression regarding to the detection of active/inactive tissue by both imaging methods.Materials and methodsThirty HL patients with abnormal mediastinal tissue following the completion of primary treatment were examined by MRI and ⁶⁷Ga scintigraphy. Positive findings were: high signal intensity on unenhanced T2-weighted images on MRI and the abnormal accumulation of gallium on scintigraphy or SPECT. These findings were compared with the clinical follow-up.ResultsSensitivity, specificity, accuracy, positive and negative predictive values were: 75.0%, 96.2%, 93.3%, 75.0%, 96.2% in MRI and 50.0%, 88.5%, 83.3%, 40.0%, 92.0% in ⁶⁷Ga scintigraphy. Discrepant results concerning the mediastinal tissue activity were found in 3 of 30 patients (10%). No statistically significant differences were found between both imaging methods in sensitivity, specificity and accuracy. Estimated 2-years progression free survival (PFS) for patients without and with active residual mediastinal tissue by MRI was 96% and 25% (p = 0.0001), respectively. The probability of 2-years PFS in the cases with negative and positive findings on ⁶⁷Ga scintigraphy was 92% and 60% (p = 0.026), respectively.ConclusionAlthough MRI showed better results than ⁶⁷Ga scintigraphy in the assessment of residual mediastinal tissue activity in HL patients after primary treatment, the difference between these methods was not statistically significant. Both methods could be included in the standard restaging protocol.     

Comparison of 18F-FDG PET and bone scintigraphy in detection of bone metastases of thyroid cancer.

We compared the efficacies of (18)F-FDG PET and (99m)Tc-bone scintigraphy for the detection of bone metastases in patients with differentiated thyroid carcinoma (DTC). METHODS: We examined 47 patients (32 women, 15 men; mean age +/- SD, 57.0 +/- 10.7 y) with DTC who had undergone total thyroidectomy and were hospitalized to be given (131)I therapy. All patients underwent both whole-body (18)F-FDG PET and (99m)Tc-bone scintigraphy. The skeletal system was classified into 11 anatomic segments and assessed for the presence of bone metastases. Bone metastases were verified either when positive findings were obtained on >2 imaging modalities--(201)Tl scintigraphy, (131)I scintigraphy, and CT--or when MRI findings were positive if vertebral MRI was performed. RESULTS: Bone metastases were confirmed in 59 of 517 (11%) segments in 18 (38%) of the 47 study patients. The sensitivities (visualization rate) for bone metastases on a segment basis using (18)F-FDG PET and (99m)Tc-bone scintigraphy were 50 of 59 (84.7%) and 46 of 59 (78.0%), respectively; the difference between these values was not statistically significant. There were only 2 (0.4%) false-positive cases in a total of 451 bone segments without bone metastases when examined by (18)F-FDG PET, whereas 39 (8.6%) were false-positive when examined by (99m)Tc-bone scintigraphy. Therefore, the specificities of (18)F-FDG PET and (99m)Tc-bone scintigraphy were 449 of 451 (99.6%) and 412 of 451 (91.4%), respectively; the difference between these values was statistically significant (P < 0.001). The overall accuracies of (18)F-FDG PET and (99m)Tc-bone scintigraphy were 499 of 510 (97.8%) and 458 of 510 (89.8%), respectively; the difference between these was also statistically significant (P < 0.001). CONCLUSION: The specificity and the overall accuracy of (18)F-FDG PET for the diagnosis of bone metastases in patients with DTC are higher than those of (99m)Tc-bone scintigraphy, whereas the difference in the sensitivities of both modalities is not statistically significant. In comparison with (99m)Tc-bone scintigraphy, (18)F-FDG PET is superior because of its lower incidence of false-positive results in the detection of bone metastases of DTC.     

Identification of Warthin's tumor with technetium-99m pertechnetate

Salivary gland imaging with Tc-99m pertechnetate is a useful procedure for evaluating the functional status of salivary glands. The only neoplasms of salivary glands known to consistently concentrate Tc-99m pertechnetate are Warthin's tumor and oncocytoma. In the five cases presented, increased concentration of Tc-99m pertechnetate was seen in these tumors of the parotid glands. This finding was useful for preoperative identification of Warthin's tumor. During this investigation, the concentration of Tc-99m pertechnetate in Warthin's tumor varied by histologic type. Thus, a dynamic study may be helpful in evaluating the accumulation rate of Tc-99m pertechnetate into this tumor type. Because the retention of Tc-99m pertechnetate in tumor following stimulation is useful for the diagnosis of Warthin's tumor, a washout image is of importance in establishing this diagnosis.     

Comparative evaluation of 18F-FDG PET and 67Ga scintigraphy in patients with sarcoidosis.

67Ga scintigraphy has been used for years in sarcoidosis for diagnosis and the extent of the disease. However, little information is available on the comparison of 18F-FDG PET and 67Ga scintigraphy in the assessment of sarcoidosis. The purpose of this study was to compare the uptake of 18F-FDG and 67Ga in the evaluation of pulmonary and extrapulmonary involvement in patients with sarcoidosis. METHODS: Eighteen patients with sarcoidosis were examined. 18F-FDG PET was performed at 1 h after injection of 185-200 MBq 18F-FDG. 67Ga whole-body planar and thoracic SPECT images were acquired 72 h after injection of 111 MBq 67Ga. We evaluated 18F-FDG and 67Ga uptake visually and semiquantitatively using standardized uptake values (SUVs) and the ratio of lesion to normal lumbar spine (L/N ratio), respectively. The presence of pulmonary and extrapulmonary lesions was evaluated histopathologically or by the radiologic findings. RESULTS: Five patients had only pulmonary lesions, 12 patients had both pulmonary and extrapulmonary lesions, and 1 patient had only an extrapulmonary lesion. Both 67Ga planar and SPECT images detected 17 of 21 (81%) clinically observed pulmonary sites. The mean +/- SD of the L/N ratio was 1.97 +/- 1.09. 67Ga planar images detected 15 of 31 (48%) clinically observed extrapulmonary sites. The mean +/- SD of the L/N ratio was 1.17 +/- 0.33. 18F-FDG PET detected all 21 (100%) clinically observed pulmonary sites. The mean +/- SD of the SUV was 7.40 +/- 2.48. 18F-FDG PET detected 28 of 31 (90%) clinically observed extrapulmonary sites. The mean +/- SD of the SUV was 5.90 +/- 2.75. CONCLUSION: The results of this clinical study suggest that 18F-FDG PET can detect pulmonary lesions to a similar degree as 67Ga scintigraphy. However, 18F-FDG PET appears to be more accurate and contributes to a better evaluation of extrapulmonary involvement in sarcoidosis patients.     

Nuclear medicine imaging in tuberculosis using commercially available radiopharmaceuticals

In this paper, data available on nuclear medicine imaging using commercially available radiopharmaceuticals for the differentiation, staging, and prediction or assessment of the response to treatment in tuberculosis (TB) are reviewed. Limited available studies suggest that single photon emission computed tomography (SPECT) using either 201Tl, 99mTc-sestamibi, or 99mTc-tetrofosmin is accurate (≥85%) and has a high negative predictive value (≥90%) for the differentiation of TB from carcinoma in patients presenting with a solitary pulmonary nodule (SPN). The criteria for detection of TB on 201Tl SPECT are nondepiction of the suspicious lesion in the delayed image or a negative retention index [washout on the delayed images (3–4 h postinjection) vs. the early image (5–15 min postinjection)] and a comparable-to-background uptake on 99mTc-sestamibi or 99mTc-tetrofosmin SPECT. Another SPECT tracer of potential interest for the differentiation of TB from malignant SPN that warrants further exploration, is N-isopropyl-p-[123I]iodoamphetamine (123I-IMP). In contrast, 18F-fluorodeoxyglucose (18F-FDG) PET is unable to differentiate malignancy from TB and thus cannot be used as a tool to reduce futile biopsy/thoracotomy in these patients. A limited number of studies have reported on the potential of nuclear medicine imaging in assessment of the extent of disease in patients with extrapulmonary TB using 67Ga-citrate SPECT and 18F-FDG PET, respectively. 67Ga-citrate SPECT was shown to be as sensitive as bone scintigraphy for the detection of bone infection and was found to be complementary to computed tomography (CT) imaging. 18F-FDG PET was found to be significantly more efficient when compared with CT, respectively, in over half of patients for the identification of sites of lymph node involvement that were missed by CT and often the only sites of extrapulmonary TB identified. Unfortunately, 18F-FDG PET findings did not lead to alterations in treatment planning in any of the patients under study. Additional studies confirming these findings are urgently required. Similar to the setting of SPN, 18F-FDG PET cannot differentiate malignant lymph node involvement from lymph node involvement by TB. These results and the recent findings of Demura and colleagues using 18F-FDG PET further suggest that nuclear medicine imaging techniques could be used for the evaluation of therapeutic response. Prospective studies, focusing on specific subgroups of patients in whom such an imaging approach might be clinically relevant, for example in multidrug-resistant TB patients, are warranted. In acquired immunodeficiency syndrome patients, 67Ga scintigraphy proved to be a reliable and sensitive method for the primary detection and follow-up of opportunistic pneumonias, including TB. Combining 201Tl scintigraphy with 67Ga scintigraphy was shown to increase the specificity for both pulmonary and extrapulmonary TB, which is a 67Ga(+) and 201Tl(-) mismatch pattern in acquired immunodeficiency syndrome patients that is specific for mycobacterial infections. Finally, the results obtained using both SPECT and PET indicate that nuclear medicine could be an important noninvasive method for the determination of disease activity, detection of extrapulmonary TB, and determination of response to therapy.     

Various imaging modalities for the detection of salivary gland lesions: the advantages of 201Tl SPET

The aim of this study was to compare dual-isotope (99Tc(m) and 201Tl) SPET imaging with computed tomography (CT) and magnetic resonance imaging (MRI) in the differentiation of various lesions of the major salivary glands. Twenty-two patients underwent dual-isotope SPET imaging, of whom 12 also had CT and 15 also had an MRI study. The uptake ratio and retention index for 99Tc(m) and 201Tl were calculated by drawing regions of interest on the involved and normal glands. Both CT and MRI were interpreted by two radiologists. All malignant tumours were detected by all three modalities. Warthin's tumours were detected by dual-isotope SPET imaging; however, MRI failed to differentiate Warthin's tumour from pleomorphic adenoma. Of 13 other benign tumours, dual-isotope SPET correctly diagnosed 12. Of 16 tumours showing a cold defect on the 99Tc(m) images, parametric analysis with 201Tl gave an accuracy of 94%, whereas CT gave an accuracy of 70-90%. MRI was 73-91% accurate in differentiating between benign (Warthin's) and malignant tumours. We believe that dual-isotope SPET imaging (99Tc(m) and 201Tl), together with semi-quantitative analysis, is the method of choice for differentiating between various lesions of the major salivary glands.     

18F-氟脱氧葡萄糖PET在恶性淋巴瘤中的应用

CT是诊断恶性淋巴瘤常规影像学手段,核医学显像也是非常重要的检查方法,如67Ga显像.18F-氟脱氧葡萄糖(18SF-FDG)PET以其在淋巴瘤中应用的显著优势逐步替代了67Ga显像.18F-FDG PET在淋巴瘤的早期诊断、准确分期、疗效的评价、复发和预后的估计等方面显示出了非常重要的价值.随着PET-CT的广泛应用使得敏感性和特异性都有了进一步的提高.主要综述了18F-FDG PET在淋巴瘤诊断、分期、疗效评价中的应用.     

Limited value of fluorine-18 fluorodeoxyglucose positron emission tomography for the imaging of neuroendocrine tumours

Scintigraphy using [¹¹¹In-DTPA-d-Phe¹]-pentetreotide or pentavalent technetium-99m-dimercaptosuccinic acid [^99mTc(V)-DMSA] has been shown to localize well-differentiated and slowly growing neuroendocrine tumours, whereas increased fluorodeoxyglucose (FDG) uptake is associated with malignancy. The aim of this study was to compare the value of fluorine-18 FDG positron emission tomography (PET) with that of somatostatin receptor scintigraphy (SS-R) and dual-radionuclide scintigraphy [SS-R and ^99mTc(V)-DMSA = DNS] in detecting malignant neuroendocrine tumours. Fifteen patients with metastasizing gastroenteropancreatic tumours (GEP tumours; n = 7), medullary thyroid carcinomas (MTCs; n = 8) and elevated tumour markers [GEP tumours: 5-hydroxyindoleacetic acid, insulin; MTCs: calcitonin, carcinoembryonic antigen (CEA)] were studied. Prior to PET, all patients with GEP tumours underwent SS-R. DNS was performed in all patients with MTC. Patients had been fasting for at least 12 h and normal glucose plasma levels were confirmed. Sixty minutes after intravenous administration of ¹⁸F-FDG (mean: 374 MBq) whole-body PET and regional scans were performed. In addition, the resected tissues were prepared for immunocytochemistry examination (cell cycle-associated Ki-67 antigen). In two patients with less-differentiated GEP tumours associated with high proliferative activity and increased FDG uptake, SS-R failed to detect any lesion. In comparison, in four patients with well-differentiated GEP tumours showing low proliferative acitivity, SS-R localized four primary tumours, 22 lymph node metastases and 18 malignant liver lesions, whereas ¹⁸F-FDG PET demonstrated normal distribution. In one patient with a metastasizing carcinoid (medium proliferative activity) SS-R localized multiple metastases, whereas PET demonstrated low FDG uptake in all known metastases. In patients with recurrent MTC and rapidly increasing CEA levels DNS detected only three lesions in two patients, whereas PET demonstrated one pulmonary, three osseous, 20 mediastinal, ten locoregional, and four liver metastases in seven patients. Twenty-nine malignant lesions were confirmed by follow-up and nine lymph node metastases could be surgically removed. In conclusion, PET imaging of gastroenteropancreatic tumours revealed increased glucose metabolism only in less-differentiated GEP tumours with high proliferative activity and metastasizing MTC associated with rapidly increasing CEA levels. Therefore, additional ¹⁸F-FDG PET should be performed only if SS-R or DNS is negative. Received 8 July and in revised form 19 September 1997     

Clinical relevance of gallium-67 scintigraphy in lymphoma before and after therapy

The clinical impact of gallium-67 scintigraphy before and after therapy for lymphoma remains controversial. The aims of this study were: (1) to compare the staging of lymphoma by ⁶⁷Ga scintigraphy only with staging by clinical examination and conventional imaging (CI), and (2) to analyse the clinical relevance of both ⁶⁷Ga imaging and CI after treatment. From March 1995 to November 1998, 86 ⁶⁷Ga scintigraphy studies were performed in 62 patients with Hodgkin’s disease (n=52) or non-Hodgkin’s lymphoma (n=10). ⁶⁷Ga scintigraphy was performed at diagnosis (n=44) or after therapy (n=42) using 185–220 MBq ⁶⁷Ga citrate and planar and single-photon emission tomography (SPET) studies. Treatment comprised radiotherapy, chemotherapy or combined modalities. CI included plain chest radiography, computed tomography (CT) of the chest and abdomen/pelvis, ultrasound of the abdomen, lymphography, bone marrow biopsy and, when necessary, magnetic resonance imaging (MRI) and bone scintigraphy. For individual suspected sites of disease before treatment, complete agreement between clinical examination and CI on the one hand and ⁶⁷Ga scintigraphy on the other hand was observed in 25/44 patients (57%; 95% confidence interval 41%–72%). Clinical examination and CI showed more sites than did ⁶⁷Ga scintigraphy in 12/44 patients (27%) and ⁶⁷Ga imaging demonstrated more sites than CI in 6/44 patients (11%). The clinical stage of the disease as assessed using ⁶⁷Ga scintigraphy only was in agreement with that using all diagnostic procedures in 34/44 patients (77%; 95% confidence interval 62%–89%). Compared with CI staging, ⁶⁷Ga scintigraphy downstaged seven patients (16%) and upstaged three (7%). ⁶⁷Ga scintigraphy downstaged mainly because of the limited value of the technique below the diaphragm and upstaged owing to the good sensitivity in the lung. After therapy, both CI and ⁶⁷Ga scintigraphy were normal in 11 patients. All but one of these patients were in complete remission after a median follow-up of 31 months. In contrast, radiological residual mass was observed in 31/42 patients. ⁶⁷Ga imaging was normal in 22/31 (71%); 17 of these 22 patients, including nine with a large residual mass (≥2 cm), were in complete remission after a median follow-up of 32 months, while four suffered relapses 8–45 months later. The cause of death remained unknown in one patient. ⁶⁷Ga scintigraphy showed abnormal uptake in 9 of the 31 patients with a large residual mass. Active disease was demonstrated in eight patients and one patient was in complete remission 30 months thereafter. Our data show that ⁶⁷Ga imaging cannot replace CI in initial staging but can demonstrate additional individual sites of disease in more than 10% of patients and can lead to clinical upstaging with potential prognostic and therapeutic consequences. After therapy, ⁶⁷Ga scintigraphy has a clinical impact when radiological abnormalities persist because it can either avoid unnecessary complementary treatment or confirm the need to change treatment modalities. Received 5 July and in revised form 9 September 1999     

核医学影像诊断多发性骨髓瘤的临床价值

核医学影像检查,包括18F-FDG(18F-氟代脱氧葡萄糖)、99Tcm-MIBl(99cm-甲氧基异丁基异腈)、201Tl、标记抗体和其他多种显像剂,对诊断多发性骨髓瘤有一定价值,是X线摄片、CT和MRI等其他影像学检查有益的补充。核医学影像检查可以了解全身骨骼的状况,用于疾病的分期和判断疗效,但仍需结合其他检查提高诊断的准确率。