18F-FDG PET/CT is Useful for Pretreatment Assessment of the Histopathologic Type of Thymic Epithelial Tumors

Purpose

This study was performed to assess the usefulness of ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) or PET/computed tomography (CT) for distinguishing thymic epithelial tumors according to World Health Organization (WHO) classifications.

Methods

We analyzed a total of 45 patients (range, 29–75 years of age; mean, 55 years) with pathologically confirmed thymic epithelial tumors who underwent pretreatment ¹⁸F-FDG PET or PET/CT between November 2003 and October 2009. The size, visual grading of uptake value, peak standardized uptake value (SUVpeak), uptake pattern, and contour of each tumor, and associated findings on PET or PET/CT, were analyzed relative to the three simplified WHO subgroups: less-invasive thymomas (types A and AB), more-invasive thymomas (types B1, B2, and B3) and thymic carcinomas. We statistically assessed the relationship of ¹⁸F-FDG PET or PET/CT findings with these simplified subgroups.

Results

Of the 45 patients, ten had less-invasive thymomas, 23 had more-invasive thymomas, and 12 had thymic carcinomas. The SUVpeak of the less- and more-invasive thymomas were significantly lower than those of thymic carcinomas (p < 0.000), but there was no difference in SUVpeak between less- and more-invasive thymomas. The visual grading scale (p < 0.000), uptake pattern (p = 0.001), and contour (p < 0.000) of the tumors differed significantly among the three simplified subgroups.

Conclusion

The image findings of ¹⁸F-FDG PET or PET/CT differed significantly by histologic subgroups. Pre-treatment evaluation with ¹⁸F-FDG PET or PET/CT might be helpful in differentiating subgroups of thymic epithelial tumors.     

胸腺上皮性肿瘤18F-FDG PET/CT显像最大标准化摄取值与WHO病理分型及Masaoka分期的关系

目的 探讨胸腺上皮性肿瘤（TET）术前18F-FDG PET/CT显像最大标准化摄取值（SUV_max）与世界卫生组织（WHO）病理分型及Masaoka分期的关系。 方法 回顾性分析2007年9月至2019年3月于南京医科大学第一附属医院经手术病理学结果证实的40例TET患者的临床资料，其中男性14例、女性26例，年龄32~79岁。分析所有患者的术前18F-FDG PET/CT显像资料，测定病灶的SUV_max。参照WHO(2015) TET病理分型将TET患者分为低危型胸腺瘤（A、AB、B1型）、高危型胸腺瘤（B2、B3型）和胸腺癌（C型）3组；采用Masaoka分期标准将TET患者分为Ⅰ期、Ⅱ期和Ⅲ期 3组；将TET患者分为胸腺瘤（包括低危型胸腺瘤和高危型胸腺瘤）和胸腺癌2组，采用受试者工作特征（ROC）曲线计算SUV_max和曲线下面积（AUC）。3组间的比较采用Kruskal-Wallis秩和检验，2组间的比较采用 Mann-Whitney U检验。 结果 低危型胸腺瘤11例（A型1例、AB型4例、B1型6例），高危型胸腺瘤15例（B2型10例、B3型5例），胸腺癌14例。Masaoka分期:Ⅰ期8例，Ⅱ期17例，Ⅲ期15例。低危型胸腺瘤、高危型胸腺瘤和胸腺癌的中位SUV_max分别为3.78、5.21和10.44，3组间SUV_max的差异有统计学意义（χ2=26.716，P<0.01）；组间的两两比较差异均有统计学意义（Z=3.088、?3.928、4.106，均P<0.01）。Ⅰ期、Ⅱ期、Ⅲ期的中位SUV_max分别为3.74、5.14、10.08，3组间SUV_max的差异有统计学意义（χ2=22.295，P<0.01），组间的两两比较差异均有统计学意义（Z=2.680、3.679、?3.644，均P<0.01）。ROC曲线分析结果:AUC为0.953（95%可变区间:0.891~1.000，P<0.01）；SUV_max=6.81是鉴别诊断胸腺瘤与胸腺癌的最佳临界值。 结论 18F-FDG PET/CT 的参数SUV_max与TET的WHO病理分型及Masaoka分期具有较好的相关性，可为临床制定治疗计划提供参考。     

Does CT of thymic epithelial tumors enable us to differentiate histologic subtypes and predict prognosis?

OBJECTIVE: The aims of our study were to describe the CT findings of thymic epithelial tumors and to correlate these findings with the histopathologic subtypes and prognosis. MATERIALS AND METHODS: The CT findings of thymic epithelial tumors were analyzed in 91 patients who had undergone surgery between May 1995 and June 2002. Two observers, who were unaware of the histopathologic classification made in accordance with World Health Organization (WHO) recommendations and the prognosis of the tumors, retrospectively reviewed the initial CT findings in terms of the contours and shapes of the tumors and the presence of necrosis, calcification, mediastinal fat or great vessel invasion, pleural seeding, contrast enhancement, and lymph node enlargement. These findings were compared with the simplified subgroups of WHO histologic classification (low-risk thymomas [types A, AB, and B1], high-risk thymomas [types B2 and B3], and thymic carcinomas [type C]) and with postoperative recurrence. RESULTS: The study found 31 low-risk thymomas (eight type A, 16 type AB, and seven type B1 tumors), 45 high-risk thymomas (25 type B2 and 20 type B3), and 15 thymic carcinomas (type C). Lobulated contour was more often seen in high-risk thymomas (26/45, 58%; p = 0.0456) and thymic carcinomas (10/15, 67%; p = 0.033) than in low-risk thymomas (9/31, 29%). Mediastinal fat invasion was more often seen in thymic carcinomas (5/15, 33%; p = 0.0133) than in low-risk thymomas (1/31, 3%). Great vessel invasion was seen only in thymic carcinomas (2/15, 13%; p = 0.0244). Tumors with a lobulated or irregular contour, an oval shape, mediastinal fat or great vessel invasion, and pleural seeding showed significantly more frequent recurrence and metastasis (all, p < 0.05). CONCLUSION: Although CT is of limited value in differentiating histologic subtypes according to the WHO classification, CT findings may serve as predictors of postoperative recurrence or metastasis for the thymic epithelial tumors.     

Thymic epithelial tumors: comparison of CT and MR imaging findings of low-risk thymomas, high-risk thymomas, and thymic carcinomas

OBJECTIVE: To assess the CT and magnetic resonance (MR) imaging findings of thymic epithelial tumors classified according to the current World Health Organization (WHO) histologic classification and to determine useful findings in differentiating the main subtypes. MATERIALS AND METHODS: Sixty patients with thymic epithelial tumor who underwent both CT and MR imaging were reviewed retrospectively. All cases were classified according to the 2004 WHO classification. The following findings were assessed in each case on both CT and MRI: size of tumor, contour, perimeter of capsule; homogeneity, presence of septum, hemorrhage, necrotic or cystic component within tumor; presence of mediastinal lymphadenopathy, pleural effusion, and great vessel invasion. These imaging characteristics of 30 low-risk thymomas (4 type A, 12 type AB, and 14 type B1), 18 high-risk thymomas (11 type B2 and seven type B3), and 12 thymic carcinomas on CT and MR imaging were compared using the chi-square test. Comparison between CT and MR findings was performed by using McNemar test. RESULTS: On both CT and MR imaging, thymic carcinomas were more likely to have irregular contours (P < .001), necrotic or cystic component (P < .05), heterogeneous contrast-enhancement (P < .05), lymphadenopathy (P < .0001), and great vessel invasion (P < .001) than low-risk and high-risk thymomas. On MR imaging, the findings of almost complete capsule, septum, and homogenous enhancement were more commonly seen in low-risk thymomas than high-risk thymomas and thymic carcinomas (P < .05). MR imaging was superior to CT in the depiction of capsule, septum, or hemorrhage within tumor (all comparison, P < .05). CONCLUSION: The presence of irregular contour, necrotic or cystic component, heterogeneous enhancement, lymphadenopathy, and great vessel invasion on CT or MR imaging are strongly suggestive of thymic carcinomas. On MR imaging, the findings of contour, capsule, septum, and homogenous enhancement are helpful in distinguishing low-risk thymomas from high-risk thymomas and thymic carcinomas.     

18F-FDG PET/CT Evaluation of Thymomas: a Pictorial Review

The World Health Organization classification divides thymomas according to morphology, epithelial component, and cell atypia. They are grouped into 3 large subgroups: low-risk thymomas (types A, AB, and B1), high-risk thymomas (types B2 and B3), and thymic carcinomas. Tumor subtype represents an independent prognostic factor, which determines therapeutic decision. All thymomas show some degree of ¹⁸F-FDG uptake, which tends to increase with the grade of malignancy; this is related to glucose transporter 1 (GLUT1) expression. This review collects all types of thymomas with illustrative images and provides a guide to get familiar with histological characteristics of the lesions and have them in mind because, even imaging findings can overlap among subtypes, certain characteristics can be combined to make an accurate diagnosis based on ¹⁸F-FDG PET-CT findings.     

MSCT在鉴别≤3cm的低、高风险胸腺瘤及胸腺癌中的价值

目的 探讨多层螺旋CT(MSCT)对最大径≤3 cm的胸腺上皮肿瘤(TET)诊断价值.方法 回顾性分析56例经病理证实的最大径≤3 cm的TET病例的病理、影像学资料,根据WHO 2004标准进行组织学分型,将病例分为低风险胸腺瘤组(A/AB/B1型)、高风险胸腺瘤组(B2/B3型)、胸腺癌组(C型),分析各组TET的CT征象,包括病灶的形状、边缘是否光滑、是否伴有棘状突起、是否伴有瘤周小结节、强化程度、胸膜侵犯征象、周围脂肪间隙等.各类型间比较采用χ2检验,样本量过小时,采用Fisher精确试验.结果 低风险胸腺瘤(27例)较高风险胸腺瘤(23例)及胸腺癌(6例)更常表现为规则的类圆形的形态(χ2=73,P<0.001;χ2=116,P<0.001),纵隔-肺界面更易呈膨隆状(χ2=3.41,P=0.046;χ2=7.39,P=0.01);高风险胸腺瘤、胸腺癌较低风险胸腺瘤更常见边缘模糊、棘状突起、胸膜侵犯等征象(P<0.001);胸腺癌较高风险胸腺瘤更常见边缘模糊、棘状突起、胸膜侵犯等征象(χ2=11.5,P=0.009);B2型胸腺瘤与胸腺癌之间的差异有显著性意义(χ2=31.52,P<0.001),然而B3型胸腺瘤与胸腺癌之间无统计学差异(χ2=6.96,P=0.07).结论 MSCT可准确显示病灶的形态、边缘、瘤周情况、强化程度及胸膜侵犯情况,在一定程度上可预测胸腺瘤的组织学分型,可为术前诊断及预后评估提供依据.     

MSCT对胸腺上皮肿瘤WHO简化病理分型的鉴别诊断价值

目的探讨多层螺旋CT(MSCT)对低危型、高危型胸腺瘤及胸腺癌的鉴别诊断价值。方法回顾性分析经病理(穿刺或手术)证实的67例胸腺上皮肿瘤,基于WHO病理分型简化为低危型胸腺瘤、高危型胸腺瘤及胸腺癌三组,并对其CT征象进行统计分析。结果67例TETs中,低危型胸腺瘤30例(A型3例、AB型20例、B1型7例),高危型胸腺瘤22例(B2型11例、B3型11例),胸腺癌15例。高危型胸腺瘤、胸腺癌较低危型胸腺瘤易表现为边缘分叶或不规则(P均<0.05)及易出现对心包侵犯(P均<0.05);胸腺癌较低危型胸腺瘤易出现增强后密度不均、囊变坏死及胸膜转移(P均≤0.003);胸腺癌较低危型、高危型胸腺瘤易出现纵隔淋巴结肿大(P均≤0.002);纵隔大血管侵犯在三组间两两比较均有统计学差异(P均<0.05)。结论MSCT对TETs的WHO简化病理分型鉴别诊断具有重要价值。     

Integrated PET/CT of salivary gland type carcinoma of the lung in 12 patients

OBJECTIVE: The purpose of our study was to show the integrated 18F-FDG PET/CT findings of salivary gland type carcinomas of the lung. CONCLUSION: Salivary gland type carcinomas of the lung appear as airway tumors with variable CT morphologies and show different patterns and extents of FDG uptake on PET images according to their grades of differentiation.     

^18F-FDG符合线路显像在胸腺上皮肿瘤诊断中的应用价值

目的探讨^18F-脱氧葡萄糖（FDG）符合线路显像在胸腺上皮肿瘤（TET）诊断中的价值。方法回顾性分析37例TET患者的^18F—FDG符合线路显像结果,图像分析采用视觉分析及半定量方法[肿瘤／正常肺组织放射性比值（TLR）]。按WHO TET病理学分类结果将患者分成3组（高生存率组,包括A、AB、B1型;中生存率组,包括B2、B3型;低生存率组,包括胸腺癌）;同时将^18F—FDG显像结果与增强CT影像进行对比,TLR与免疫组织化学检查所测Ki67标记指数（细胞增殖指标）进行相关性分析。组间TLR比较采用方差分析。结果（1）^18F—FDG符合线路显像阳性率91．9％（34／37）;（2）3个不同生存率组TLR间差异有统计学意义（高、中、低生存率组TLR依次为：1．42±0．27,2．13±0．74,3．00±1．19,F=9．99,P〈0．05）;（3）TLR与Ki67标记指数有明显相关性（r=0．613,P=0．002）;（4）^18F-FDG显像发现2例增强CT未发现的病灶,病灶分别位于前胸壁和右锁骨上淋巴结;（5）共有4例伴发重症肌无力。结论^18F—FDG符合线路显像有助于WHO TET病理学分类和发现更多的TET侵犯、转移灶;可以用^18F—FDG在TET的浓聚程度反映细胞的增殖活力。     

18F-FDG PET for the evaluation of thymic epithelial tumors: Correlation with the World Health Organization classification in addition to dual-time-point imaging

Purpose  Our aim was to determine dual-phase ¹⁸F-FDG PET imaging features for various subtypes of thymic epithelial tumors based on the World Health Organization classification. Methods  Forty-six patients with histologically verified thymic epithelial tumors [23 with low-risk tumors (4 with type A, 16 with AB, and 3 with B1) and 23 with high-risk tumors (7 with B2, 5 with B3, and 11 with thymic carcinoma] were enrolled in this study. All patients were injected with ¹⁸F-FDG.; after 1 h, they underwent scanning; after 3 h, 23 patients underwent an additional scanning. The maximum standard uptake value (SUV_max) and the retention index (RI%) of the lesions were determined. Results  The early and delayed SUV_max values in the patients with high-risk tumors [early SUV_max (mean: 6.0) and delayed SUV_max (mean: 7.4)] were both significantly larger than those in patients with low-risk tumors [early SUV_max (mean: 3.2) and delayed SUV_max (mean: 3.4)] (P < 0.05). Early SUV_max values of greater than 7.1 differentiated thymic carcinomas from other types of tumors. For the histological differentiation between high-risk tumors and low-risk tumors, an early SUV_max value of 4.5 was used as the cutoff. The sensitivity, specificity, and accuracy were 78.3, 91.3, and 84.8%, respectively. Conclusion  High SUV values (early SUV > 4.5) suggest the presence of high-risk tumors. A very high SUV value (early SUV > 7.1) is useful for the differentiation of thymic carcinomas from other types of tumors. The delayed SUV values were higher than the early SUV values in all types of tumors.     

18F-FET PET compared with 18F-FDG PET and CT in patients with head and neck cancer.

Recent studies suggest a somewhat selective uptake of O-(2-[18F]fluoroethyl)-L-tyrosine (FET) in cerebral gliomas and in squamous cell carcinoma (SCC) and a good distinction between tumor and inflammation. The aim of this study was to investigate the diagnostic potential of 18F-FET PET in patients with SCC of the head and neck region by comparing that tracer with 18F-FDG PET and CT. METHODS: Twenty-one patients with suspected head and neck tumors underwent 18F-FET PET, 18F-FDG PET, and CT within 1 wk before operation. After coregistration, the images were evaluated by 3 independent observers and an ROC analysis was performed, with the histopathologic result used as a reference. Furthermore, the maximum standardized uptake values (SUVs) in the lesions were determined. RESULTS: In 18 of 21 patients, histologic examination revealed SCC, and in 2 of these patients, a second SCC tumor was found at a different anatomic site. In 3 of 21 patients, inflammatory tissue and no tumor were identified. Eighteen of 20 SCC tumors were positive for both 18F-FDG uptake and 18F-FET uptake, one 0.3-cm SCC tumor was detected neither with 18F-FDG PET nor with 18F-FET PET, and one 0.7-cm SCC tumor in a 4.3-cm ulcer was overestimated as a 4-cm tumor on 18F-FDG PET and missed on 18F-FET PET. Inflammatory tissue was positive for 18F-FDG uptake (SUV, 3.7-4.7) but negative for 18F-FET uptake (SUV, 1.3-1.6). The SUVs of 18F-FDG in SCC were significantly higher (13.0 +/- 9.3) than those of 18F-FET (4.4 +/- 2.2). The ROC analysis showed significantly superior detection of SCC with (18)F-FET PET or 18F-FDG PET than with CT. No significant difference (P = 0.71) was found between 18F-FDG PET and 18F-FET PET. The sensitivity of 18F-FDG PET was 93%, specificity was 79%, and accuracy was 83%. 18F-FET PET yielded a lower sensitivity of 75% but a substantially higher specificity of 95% (accuracy, 90%). CONCLUSION: 18F-FET may not replace 18F-FDG in the PET diagnostics of head and neck cancer but may be a helpful additional tool in selected patients, because 18F-FET PET might better differentiate tumor tissue from inflammatory tissue. The sensitivity of 18F-FET PET in SCC, however, was inferior to that of 18F-FDG PET because of lower SUVs.     

<Superscript>18</Superscript>F-FDG PET/CT findings of sinonasal inverted papilloma with or without coexistent malignancy: comparison with MR imaging findings in eight patients

Introduction  Sinonasal inverted papilloma (IP) is known for high rate of associated malignancy. The purpose of this study was to identify ¹⁸F-FDG PET/CT findings of sinonasal IPs. We also tried to compare the PET/CT findings with the MR imaging findings. Methods  We retrospectively reviewed PET/CT and MR images of eight patients with sinonasal IP with (n = 6) or without (n = 2) coexistent squamous cell carcinoma (SCC). Particular attention was paid to correlate the PET/CT findings with the MR imaging findings in terms of area distribution of standard uptake values (SUVs) and a convoluted cerebriform pattern (CCP). Results  In two benign IPs, the maximum SUVs measured 8.2 and 7.8, respectively (mean, 8.0). In both tumors, MR images demonstrated a diffuse CCP. In six IPs with coexistent SCC, the maximum SUVs ranged from 13.3 to 31.9 (mean ± SD, 20.2 ± 6.6). In these tumors, MR images demonstrated a diffuse CCP in two, a partial CCP in three, and no CCP in one. A wide discrepancy was noted between MR imaging and PET/CT in terms of area distribution of a CCP and SUVs. Conclusion  In sinonasal lesions with MR imaging features of IP, ¹⁸F-FDG PET/CT demonstrating avid FDG uptake does not necessarily imply the presence of coexistent malignancy. In our small series, although IPs containing foci of SCC had consistently higher SUVs than IPs without SCC, the limited literature on this subject suggests that PET cannot be used reliably to make the distinction.     

18F-FLT PET for visualization of laryngeal cancer: comparison with 18F-FDG PET.

The feasibility of (18)F-3'-fluoro-3'-deoxy-L-thymidine PET (FLT PET) for detecting laryngeal cancer was investigated and compared with (18)F-FDG PET. METHODS: Eleven patients diagnosed with or strongly suspected of having recurrent laryngeal cancer and 10 patients with histologically proven primary laryngeal cancer underwent attenuation-corrected (18)F-FLT PET imaging 60 min after injection of a median of 213 MBq (range, 175-400 MBq) (18)F-FLT and attenuation-corrected (18)F-FDG PET imaging 90 min after injection of a median of 340 MBq (range, 165-650 MBq) (18)F-FDG. All patients were staged by endoscopy and CT according to the Union Internationale Contre la Cancer TNM staging system. All patients underwent biopsy of the laryngeal area after imaging. Lesions seen on (18)F-FDG PET and (18)F-FLT PET were compared with histopathologic results. Mean SUVs, maximum SUVs, and tumor-to-nontumor (TNT) ratios were calculated for (18)F-FLT and (18)F-FDG. Wilcoxon nonparametric testing was used for comparison of (18)F-FDG with (18)F-FLT uptake. The Spearman correlation coefficient was used to correlate mean SUVs, maximum SUVs, and TNT ratios of (18)F-FDG PET and (18)F-FLT PET. Two-tailed P values < 0.05 were considered significant. RESULTS: (18)F-FDG PET and (18)F-FLT PET detected laryngeal cancer correctly in 15 of 17 patients. One lesion judged as positive on (18)F-FDG PET turned out to be normal tissue. Of 2 lesions judged as positive on (18)F-FLT PET, 1 turned out to be inflammation and the other to be normal tissue. Maximum SUVs were 3.3 (range, 1.9-8.5) for (18)F-FDG and 1.6 (range, 1.0-5.7) for (18)F-FLT (P < 0.001). Mean SUVs were 2.7 (range, 1.5-6.5) for (18)F-FDG and 1.2 (range, 0.8-3.8) for (18)F-FLT (P < 0.001). TNT was 1.9 (range, 1.3-4.7) for (18)F-FDG and 1.5 (range, 1.1-3.5) for (18)F-FLT (P < 0.05). CONCLUSION: The numbers of laryngeal cancers detected with (18)F-FLT PET and (18)F-FDG PET were equal. In laryngeal cancer, the uptake of (18)F-FDG is higher than that of (18)F-FLT.     

Need for standardization of 18F-FDG PET/CT for treatment response assessments

Many factors affect standardized uptake values (SUVs) in (18)F-FDG PET/CT. The use of the SUV from a single PET scan in multicenter studies requires the standardization of (18)F-FDG PET/CT procedures. In the context of treatment response assessments (repeated PET scans), many factors may seem to have minor effects on percentage changes in SUVs, provided that imaging procedures are executed in a consistent manner for each subject. However, the use of (18)F-FDG PET/CT in a nonstandardized manner will result in unknown biases and reproducibilities of SUVs and SUV-based response measures. This article provides an overview of the need for standardization in relation to the specific use of SUVs and SUV changes in studies of treatment response assessments.     

18F-FDG PET/CT与增强CT在成人原发前纵隔恶性肿瘤中的诊断价值

目的 探讨18F-氟脱氧葡萄糖（FDG） PET/CT与增强CT在成人原发前纵隔恶性肿瘤中的诊断价值,以提高对该部位病变的诊断水平。 方法 回顾性分析2016年6月至2019年5月在湖北文理学院附属医院（襄阳市中心医院）经病理证实的成人原发前纵隔肿瘤患者80例（恶性肿瘤35例、良性肿瘤45例）,其中,男性46例、女性34例,年龄20~80（45.5±10.2）岁。所有患者均行全身18F-FDG PET/CT及胸部CT平扫+增强扫描,2种检查的间隔时间在2周内。分别计算并采用χ2检验比较18F-FDG PET/CT与增强CT扫描的诊断灵敏度、特异度和准确率,采用χ2检验比较2种检查方法对不同类型恶性肿瘤的诊断效能。 结果 35例恶性肿瘤中胸腺癌15例,淋巴瘤10例,恶性生殖细胞瘤7例,神经内分泌癌、恶性黑色素瘤及滑膜肉瘤各1例。18F-FDG PET/CT诊断成人原发前纵隔恶性肿瘤的灵敏度[97.1%（34/35）]、特异度[93.3%（42/45）]及准确率[95.0%（76/80）]均高于增强CT[71.4%（25/35）、77.8%（35/45）、75.0%（60/80）],且差异有统计学意义（χ2=8.612、4.357、12.471,均P<0.05）;18F-FDG PET/CT对胸腺癌、淋巴瘤及恶性生殖细胞瘤诊断的准确率[93.3%（14/15）、100.0%（10/10）、85.7%（6/7）]均高于增强CT[60.0%（9/15）、50.0%（5/10）、28.6%（2/7）],且差异有统计学意义（χ2=4.503、6.333、4.333,均P<0.05）。 结论 18F-FDG PET/CT对成人原发前纵隔恶性肿瘤具有重要的诊断价值,其诊断效能优于增强CT,可作为该病主要的检查方法。     

Deep-inspiration breath-hold PET/CT: clinical findings with a new technique for detection and characterization of thoracic lesions.

Respiratory motion during PET/CT acquisition can cause misregistration and inaccuracies in calculation of standardized uptake values (SUVs). Our aim was to compare the detection and characterization of thoracic lesions on PET/CT with and without a deep-inspiration protocol. METHODS: We studied 15 patients with suspected pulmonary lesions who underwent clinical PET/CT, followed by deep-inspiration breath-hold (BH) PET/CT. In BH CT, the whole chest of the patient was scanned in 15 s at the end of deep inspiration. For BH PET, patients were asked to hold their breath 9 times for 20-s intervals. One radiologist reviewed images, aiming to detect and characterize pulmonary, nodal, and skeletal abnormalities. Clinical CT and BH CT were compared for number, size, and location of lesions. Lesion SUVs were compared between clinical PET and BH PET. Images were also visually assessed for accuracy of fusion and registration. RESULTS: All patients had lesions on clinical CT and BH CT. Pulmonary BH CT detected more lesions than clinical CT in 13 of 15 patients (86.7%). The total number of lung lesions detected increased from 53 with clinical CT to 82 with BH CT (P<0.001). Eleven patients showed a total of 31 lesions with abnormal (18)F-FDG uptake. BH PET/CT had the advantage of reducing misregistration and permitted a better localization of sites with (18)F-FDG uptake. A higher SUV was noted in 22 of 31 lesions on BH PET compared with clinical PET, with an average increase in SUV of 14%. CONCLUSION: BH PET/CT enabled an increased detection and better characterization of thoracic lesions compared with a standard PET/CT protocol, in addition to more precise localization and quantification of the findings. The technique is easy to implement in clinical practice and requires only a minor increase in the examination time.     

18氟-脱氧葡萄糖和11碳-乙酸PET/CT显像在原发性肝癌及肝脏肿瘤样病变诊断中的初步研究

目的探讨18氟-脱氧葡萄糖(18 F-fluorodexyoxyglucose,18F-FDG)和11碳-乙酸(11 C-acetate,11 C-ACT)PET/CT显像在原发性肝癌及肝脏肿瘤样病变诊断中的作用。方法回顾性分析9例患者资料,其中男性7例,女性2例,平均年龄70.2岁,所有患者均为肝内单发病灶。治疗前均先行18 F-FDG PET/CT,后行11 C-ACT PET/CT检查,两次检查间隔时间不超过1周。其中有7例肝细胞肝癌(hepatocelluar carcinoma,HCC)、1例胆管细胞癌(cholangiocarcinoma,CCC)、1例肝内感染性病灶,均经病理学或临床随访证实。结果 7例HCC患者18 F-FDG PET/CT显像均为阴性,11 C-ACT PET/CT显像有6例为阳性。18F-FDG PET/CT和11 C-ACT PET/CT显像均未发现1例高分化胆管细胞癌。对于1例肝内炎性病灶,18F-FDG PET/CT显像为阳性,而11 C-ACT PET/CT显像为阴性。结论①11 C-ACT PET/CT显像可以用来探测那些呈18 F-FDG等或低摄取的HCC病灶;②对于高分化的CCC,18 F-FDG PET/CT显像有可能会表现为假阴性结果;③11 C-ACT PET/CT显像可以用来诊断肝内感染性病灶。     

Imaging proliferation in lung tumors with PET: 18F-FLT versus 18F-FDG.

Recently, the thymidine analog 3'-deoxy-3'-(18)F-fluorothymidine (FLT) was suggested for imaging tumoral proliferation. In this prospective study, we examined whether (18)F-FLT better determines proliferative activity in newly diagnosed lung nodules than does (18)F-FDG. METHODS: Twenty-six patients with pulmonary nodules on chest CT were examined with PET and the tracers (18)F-FDG and (18)F-FLT. Tumoral uptake was determined by calculation of standardized uptake value (SUV). Within 2 wk, patients underwent resective surgery or had core biopsy. Proliferative activity was estimated by counting nuclei stained with the Ki-67-specific monoclonal antibody MIB-1 per total number of nuclei in representative tissue specimens. The correlation between the percentage of proliferating cells and the SUVs for (18)F-FLT and (18)F-FDG was determined using linear regression analysis. RESULTS: Eighteen patients had malignant tumors (13 with non-small cell lung cancer [NSCLC], 1 with small cell lung cancer, and 4 with pulmonary metastases from extrapulmonary tumors); 8 had benign lesions. In all visible lesions, mean (18)F-FDG uptake was 4.1 (median, 4.4; SD, 3.0; range, 1.0-10.6), and mean (18)F-FLT uptake was 1.8 (median, 1.2; SD, 2.0; range, 0.8-6.4). Statistical analysis revealed a significantly higher uptake of (18)F-FDG than of (18)F-FLT (Mann-Whitney U test, P < 0.05). (18)F-FLT SUV correlated better with proliferation index (P < 0.0001; r = 0.92) than did (18)F-FDG SUV (P < 0.001; r = 0.59). With the exception of 1 carcinoma in situ, all malignant tumors showed increased (18)F-FDG PET uptake. (18)F-FLT PET was false-negative in the carcinoma in situ, in another NSCLC with a low proliferation index, and in a patient with lung metastases from colorectal cancer. Increased (18)F-FLT uptake was related exclusively to malignant tumors. By contrast, (18)F-FDG PET was false-positive in 4 of 8 patients with benign lesions. CONCLUSION: (18)F-FLT uptake correlates better with proliferation of lung tumors than does uptake of (18)F-FDG and might be more useful as a selective biomarker for tumor proliferation.     

胸腺上皮肿瘤WHO病理分型与CT特征的相关性

目的：探讨胸腺上皮性肿瘤（TETs）的WHO病理分型与CT表现的相关性,以提高其CT诊断及临床诊疗水平。方法：回顾性分析经穿刺活检或手术病理证实的66例TETs患者的CT影像学表现。所有患者均行胸部CT平扫及增强扫描,均经组织病理学及细胞免疫组化检查并进行WHO组织病理分型,分析TETs各种组织学类型的CT特征。结果：66例TETs中男39例,女27例,年龄6～77岁。病理分型：A型5例（7．6％）,AB型15例（22．7％）,B1型13例（19．7％）,B2型10例（15．2％）,B3型10例（15．2％）及胸腺癌13例（19．7％）。A、AB、B1型胸腺瘤均呈圆形或类圆形,而80．0％的B3型胸腺瘤及92．3％的胸腺癌呈不规则形;大部分（92．4％）胸腺肿瘤呈中度强化。80．0％B3型胸腺瘤及100％胸腺癌有包膜破坏并侵犯邻近结构;40．0％的B3型胸腺瘤及61．5％的胸腺癌出现心包和（或）胸膜腔积液;随着肿瘤病理分级的增加,周围结构受侵的发生率亦随之升高,分别为15．4％（B1）、40．0％（B2）、80．0％（B3）及100％（胸腺癌）。TETs组织学分类与侵袭危险度CT分级之间存在显著相关性（rs=0．736,P〈0．01）。结论：不同WHO病理分型的TETs的cT表现具有一定特征性,TETs的CT特征反映了其侵袭危险性及组织病理学分型。     

Clinical utility of 18F-FDG PET for patients with salivary gland malignancies.

The clinical utility of 18F-FDG PET in evaluating salivary gland malignancies has not been well defined. We therefore evaluated the utility of 18F-FDG PET in management for patients with salivary gland cancers. METHODS: Thirty-four patients with newly diagnosed salivary gland cancers underwent CT and 18F-FDG PET before surgical resection with radiotherapy. The diagnostic accuracies of CT and 18F-FDG PET for detecting primary tumors and neck metastases were compared with a histopathologic reference. We determined the relationship between the maximum standardized uptake value (SUV) of the tumor and clinicopathologic parameters such as sex, age, local tumor invasion, T and N categories, TNM stage, and histologic grade, as well as their associations with disease-free survival (DFS). RESULTS: 18F-FDG PET was more sensitive than CT for the detection of primary tumors (91.2% vs. 79.4%; P < 0.05), cervical metastases (80.5% vs. 56.1%; P < 0.05), and distant metastases in 2 patients at initial staging. High-grade malignancies had higher mean maximum SUVs than did low- and intermediate-grade malignancies (4.6 vs. 2.8; P = 0.011). T and N categories were independent determinants of DFS (P < 0.05), but the maximum SUV (4.0) was not. During a mean follow-up of 25.1 mo, 18F-FDG PET correctly diagnosed local-regional recurrences in 6 patients and new distant metastases in 9 patients. CONCLUSION: Our findings indicate that, in patients with salivary gland malignancies, 18F-FDG PET is clinically useful in initial staging, histologic grading, and monitoring after treatment but not in predicting patient survival.