18F-FDG PET/CT显像联合HRCT对孤立性原发肺浸润性黏液腺癌的诊断价值

目的探讨孤立性原发肺浸润性黏液腺癌18F-FDG PET/CT显像和HRCT征象及两者联合对该病的诊断价值。方法回顾性分析经病理证实为浸润性黏液腺癌、有18F-FDG PET/CT双时相显像及病灶层面同机HRCT扫描资料的9例患者,对PET/CT早期、延迟显像及滞留指数、HRCT征象进行综合分析。结果HRCT图像上表现为2例呈实性结节、病灶周围无类似卫星灶样影,6例实性结节周围伴小点片及磨玻璃样影,1例为单纯磨玻璃样结节;分叶征(6例)、血管集束征(6例)、支气管充气征(4例)、空泡征(2例)、毛刺征(1例);18F-FDG PET/CT融合图像上8例病灶表现为不均匀FDG代谢增高,早期显像平均SUVmax为3.2±2.5,延迟现象SUVmax增高6例、降低2例,平均SUVmax为3.5±2.4,平均滞留指数为(10.4±29.3)%,9例均未见纵隔、双侧肺门淋巴结及其他部位转移征象,其18F-FDG PET/CT融合图像上18F-FDG摄取与HRCT相匹配,18F-FDG摄取相对集中于结节的实性区域,病灶磨玻璃区18F-FDG摄取不明显;综合手术病理结果等临床资料证实,9例均为T1N0M0期,与PET/CT分期一致。结论对于影像学检查发现肺孤立性占位患者,在单一影像学检查难以明确诊断的情况下,18F-FDG PET/CT双时相显像上病灶不均匀18F-FDG摄取相对集中于其实性区域的代谢方式与HRCT相联合,可辅助孤立性原发性肺浸润性黏液腺癌的诊断。     

结核病18F-FDG PET图像表现的多样性

目的总结结核病18F-脱氧葡萄糖(FDG) PET显像的影像学特征.方法回顾性分析26例结核病患者的18F-FDG PET图像,其中21例由组织病理学检查结果证实,余5例据临床资料诊断.所有患者在注射18F-FDG 60～90 min后进行衰减校正全身PET显像.其中14例患者同时行早期(40～65 min)和延迟(1.5～2.5 h)双时相检查.图像判读包括目测法和标准摄取值(SUV)半定量分析.双时相显像计算SUV变化率[ΔSUV(%)].结果 26例结核病患者中22例可见18F-FDG摄取,肺结核摄取18F-FDG有4种基本类型:肺结节局限性18F-FDG浓聚(9例);肺内病灶同时伴有肺门或纵隔淋巴结浓聚(5例);肺伴有锁骨上和(或)腹腔淋巴结异常浓聚(3例);广泛胸膜异常浓聚(2例).平均SUVmax为3.64±2.58(1.4～7.6 ).延迟相SUV与早期相比较随时间延长而增加[(34.62±7.25)%].3例肺外结核18F-FDG PET显像呈阳性.4例陈旧性肺结核患者在CT所示结节部位未见18F-FDG摄取.结论结核病18F-FDG摄取可作为结核活动性的一个标志,其18F-FDG PET表现呈多样性.阳性18F-FDG摄取在肺部结节良恶性鉴别诊断时应慎重,特别是多发高代谢病灶背景不清晰时.背景不清晰的病灶结合结核菌素试验阳性,应考虑结核可能.     

结核病18F-FDG PET图像表现的多样性

目的总结结核病18F-脱氧葡萄糖(FDG) PET显像的影像学特征.方法回顾性分析26例结核病患者的18F-FDG PET图像,其中21例由组织病理学检查结果证实,余5例据临床资料诊断.所有患者在注射18F-FDG 60～90 min后进行衰减校正全身PET显像.其中14例患者同时行早期(40～65 min)和延迟(1.5～2.5 h)双时相检查.图像判读包括目测法和标准摄取值(SUV)半定量分析.双时相显像计算SUV变化率[ΔSUV(%)].结果 26例结核病患者中22例可见18F-FDG摄取,肺结核摄取18F-FDG有4种基本类型肺结节局限性18F-FDG浓聚(9例);肺内病灶同时伴有肺门或纵隔淋巴结浓聚(5例);肺伴有锁骨上和(或)腹腔淋巴结异常浓聚(3例);广泛胸膜异常浓聚(2例).平均SUVmax为3.64±2.58(1.4～7.6 ).延迟相SUV与早期相比较随时间延长而增加[(34.62±7.25)%].3例肺外结核18F-FDG PET显像呈阳性.4例陈旧性肺结核患者在CT所示结节部位未见18F-FDG摄取.结论结核病18F-FDG摄取可作为结核活动性的一个标志,其18F-FDG PET表现呈多样性.阳性18F-FDG摄取在肺部结节良恶性鉴别诊断时应慎重,特别是多发高代谢病灶背景不清晰时.背景不清晰的病灶结合结核菌素试验阳性,应考虑结核可能.     

18F-FDG PET和CT判断肺结核病灶活动性的比较

目的 评价18F-FDG PET和CT两种影像学方法对肺结核病灶活动性判断的差异.方法 对18F-FDG PET-CT显像中发现的3l例肺结核病例,分别用CT图像和PET图像对肺结 核病灶是否活动进行判断,然后对两种影像学方法的结果进行比较.结果 两种方法判断结果一致者26例,不一致者5例.6例CT诊断为非活动性肺结核者(愈合病灶),PET均判断为非活动性病灶;16例CT示病灶大部分钙化、伴有少许索条影(陈旧性病灶)并诊断为非活动性肺结核者中,5例PET判断为活动性病灶,其中3例病灶为结节的未钙化部分放射性轻度浓聚,2例为索条影伴有放射性轻度浓聚;9例CT诊断为活动性肺结核者,PET均判断为活动性病灶.结论 18F-FDGPET在判断愈合后的结核病灶和完全处于活动期的结核病灶时,与CT判断结果一致,但在对陈旧性结核病灶是否存在残余活动性病灶的判断上优于CT.     

^18F-FDG和^18F—FLTPET／CT诊断肺结节影响因素的多中心临床研究

目的:探讨18F-FDG和18F-FLT PET/CT诊断肺结节的影响因素,以提高PET/CT对肺结节的诊断价值.材料和方法:选择肺结节患者55例为研究对象,其中男性33例,女性22例,年龄17～82岁,28例为肺内孤立结节,其余为2～3个结节,结节大小0.6～11.0cm,所有患者均行肺部18F-FDG和18F-FLT PET/CT检查,分析18F-FDG和18F-FLT标准摄取值(SUV)与肺结节患者的性别、年龄、结节大小及病理类型等相互关系和意义.结果:55例肺结节患者,18F-FDG和18F-FLT标准摄取值与患者的性别、年龄、结节大小等均无统计学差异(P>0.05),18F-FDG标准摄取值与患者的病理类型亦无统计学差异(P>0.05),而18F-FLT标准摄取值与患者的病理类型有统计学差异(P<0.05).结论:肺结节患者结节的病理类型是影响18F-FLT标准摄取值的重要因素.18F-FLT PET/CT鉴别诊断肺结节良恶性具有重要的价值和意义.     

肺孤立性占位中CT形态特征和PET代谢特征的比较研究

目的:比较分析肺孤立性占位18F-FDG PET/CT图像中CT形态特征对PET代谢特征的影响.材料和方法:回顾性收集211例完成全身18F-FDG PET/CT显像的肺孤立性占位患者,所有患者均经病理证实或影像学随访一年以上.在CT图像中分析每个病灶的大小、分叶征、毛刺征和胸膜牵拉征等形态特征,在PET图像中获取每个病灶的平均标准摄取值(SUVave)等代谢特征.所有特征均与病理和临床随访结果相比较.结果:211例肺孤立性占位患者中恶性占位163例,良性占位48例.以SU Vave=2.5作为良恶性鉴别的定量依据18F-FDG PET对肺孤立性占位的诊断灵敏度、特异性及准确性分别为86.5%,52.1%和78.7%.163例恶性占位中,57例＞3cm的恶性占位,其SU Vave明显高于106例≤3cm的病灶(6.84±2.06比4.13±2.42,P＜0.01);116例具有分叶特征的恶性病灶SUVave明显高于47例无分叶特征的恶性病灶(5.45±2.40比4.25±2.86,P＜0.01).106例≤3cm的恶性占位(肺孤立性结节),具有分叶、毛刺征的SUVave明显高于无毛刺征的恶性占位(4.70 2.41比3.30±2.20;4.55±2.20比3.58±2.59,P均＜0.01).胸膜牵拉征对SU Vave的影响没有差异.结论:18F-FDG PET显像可以较好的鉴别诊断肺内孤立性占位.肿瘤大小、分叶对恶性肿瘤代谢特征均有明显影响;毛刺征对恶性肿瘤代谢特征的影响主要体现在肺孤立性结节中,胸膜牵拉征对代谢特征影响不明显.     

~(18)F-FDG符合线路SPECT/CT在尘肺病大阴影良恶性鉴别中的应用价值

目的探讨~(18)F-FDG SPECT/CT对尘肺病大阴影良恶性鉴别的临床应用价值。方法回顾分析50例尘肺病Ⅲ期患者肺内的94个大阴影病灶,行~(18)F-FDG SPECT/CT检查,并计算大阴影的最大标准摄取值(SUV max);通过卡方检验探讨大阴影~(18)F-FDG摄取高低、分布特点与肺癌之间的相关性。结果 50例患者单纯尘肺病大阴影直径范围为(4.35±1.17)cm,SUVmax范围为4.82±1.77;肺癌病灶直径范围为(4.98±0.67)cm,SUVmax范围为6.82±1.06。尘肺结节病灶和肺癌病灶的直径及SUVmax的差异均无统计学意义(P0.05)。尘肺病大阴影呈对称分布者比孤立性分布者良性可能性更大,且差异有统计学意义(P0.05);尘肺病大阴影孤立性分布且SUVmax摄取高者较对称性分布者或病灶孤立性分布且SUVmax摄取低者肺癌的可能性更大,且差异有统计学意义(P0.05)。结论尘肺病大阴影~(18)F-FDG摄取低或者~(18)F-FDG摄取高且呈对称分布时,多提示良性尘肺结节可能。尘肺病大阴影孤立性分布且~(18)F-FDG摄取高者较大阴影对称性分布者或病灶孤立性分布且SUVmax摄取低者肺癌的可能性更大。     

成人型肺母细胞瘤的CT及PET/CT表现

目的探讨成人型肺母细胞瘤(ATPB)的CT及PET/CT表现,提高对其诊断的准确率。方法对9例经手术或穿刺病理证实的ATPB的影像学表现进行回顾性分析。MSCT多期增强扫描检查8例,PET/CT检查4例,其中3例同时做CT及PET/CT检查。结果 9例ATPB均为周围型,均为单发,其中1例合并肺内多发转移。CT表现:8例呈边缘光滑锐利或仅有浅分叶的圆形或类圆形结节或肿块,仅1例可见典型浅分叶、毛刺及胸膜牵拉征象。5例病灶直径≥5 cm且密度不均,7例有坏死液化,增强扫描强化明显。18F-FDG PET/CT显像4例病灶呈均匀或不均匀放射性浓聚,标准摄取值最大值约3.2～4.7。结论 ATPB影像学上缺乏特征性表现,综合CT和PET/CT影像学检查能提高诊断符合率,对部分病例可做出提示性诊断。     

原发性肺黏膜相关淋巴组织淋巴瘤的18F-FDG PET/CT影像学表现

目的 分析原发性肺黏膜相关淋巴组织（MALT）淋巴瘤的18F-FDG PET/CT影像学表现,提高对原发性肺MALT淋巴瘤的认识及诊断能力。 方法 回顾性分析2006年11月至2017年4月经病理确诊的9例原发性肺MALT淋巴瘤患者（男性6例、女性3例,中位年龄59岁）的临床资料及18F-FDG PET/CT显像资料,记录病灶的部位、数量、密度、大小、形态及最大标准化摄取值（SUV_max）,以及纵隔及肺门淋巴结等情况;分析影像信息并同时进行相关文献复习。 结果 9例原发性肺MALT淋巴瘤患者18F-FDG PET/CT表现分为3型:实变型4例、肿块型3例、弥漫肺炎型2例。实变型表现为大小、受累范围不等的实变影;肿块型表现为单发或多发、边缘毛糙的实性肿块影;弥漫肺炎型表现为肺叶内或双肺弥漫的斑片、团块样软组织密度影。在9例患者中可见支气管充气征8例（部分伴有支气管扩张）、三角型灌注征3例、病灶向中心聚拢4例、钙化2例、胸腔积液2例、肺门及纵隔淋巴结肿大2例。所有病灶18F-FDG 代谢不均匀增高,中位SUV_max为6.0（2.6~8.3）;2例弥漫肺炎型纵隔及肺门淋巴结18F-FDG摄取异常增高,SUV_max分别为13.0、4.7。 结论 原发性肺MALT淋巴瘤的18F-FDG PET/CT表现常为斑片状致密影,多见实变影,内部常见支气管充气征,18F-FDG轻度摄取,结合相对缓慢的病程,可考虑为原发性肺MALT淋巴瘤。     

皮下脂膜炎样T细胞淋巴瘤18F-FDGPET/CT影像分析并文献复习(附4例报道)

目的 总结皮下脂膜炎样T细胞淋巴瘤（SPTCL）的18F-FDG PET/CT影像学特点,探讨18F-FDG PET/CT在SPTCL中的应用价值。 方法 回顾性分析4例经病理证实的SPTCL患者的影像学表现,观察病灶的形态、分布范围、代谢信息,结合其临床、病理特点复习相关文献。 结果 4例患者的18F-FDG PET/CT影像学表现:病灶形态不规则,密度增高,相应部位18F-FDG摄取增高。病变累及范围广泛,面颈（2例）、躯干（4例）、四肢（4例）、腹膜和盆腔脂肪组织（2例）均可受累。半定量分析结果:皮下脂肪病灶最大标准化摄取值为3.5~14.6。 结论 SPTCL病变分布广泛,18F-FDG摄取差异较大,但18F-FDG PET/CT显像有利于整体评估SPTCL患者病情,在疗效监测方面具有重要作用。      

11C-胆碱与18F-FDG双时相PET/CT显像结合高分辨率CT在孤立性肺结节鉴别诊断中的应用

目的比较11C-胆碱（11C-CHO）PET/CT、18F-FDG双时相PET/CT、常规18F-FDG PET/CT、11C-CHO+18F-FDG双时相PET/CT显像结合高分辨率CT（HRCT）4种方法对鉴别诊断孤立性肺结节（SPN）良恶性的价值。方法对28例SPN患者进行18F-FDG PET/CT显像（注药后l h显像,2 h行延迟显像）和11C-CHO PET/CT显像（于注药10 min后进行）。PET图像判断以SPN最大截面勾画ROI,计算SUV_max作为半定量指标,SUV_max ≥ 2.5为阳性,18F-FDG PET/CT延迟显像SUV_max上升10%为恶性病变（阳性）,下降或升高 < 10%为良性病变（阴性）。HRCT以是否有分叶征、短细毛刺、胸膜尾征、支气管充气征、血管集束征、空泡征为分析良恶性的指征。所有病例进行临床综合分析及随访,以影像诊断是否符合临床随访及病理结果作为判断标准。组间SUV_max的比较采用t检验;计数资料的比较采用χ2检验。结果 28例SPN患者中,病理或临床随访诊断发现肺癌17例,结核7例,结节病4例。常规18F-FDG PET/CT显像确诊21例,18F-FDG双时相PET/CT显像确诊24例,11C-CHO PET/CT显像确诊23例,11C-CHO +18F-FDG双时相PET/CT+HRCT确诊27例。28例患者良恶性结节的18F-FDG及11C-CHO PET/CT的SUV_max比较,差异有统计学意义（t=10.57和13.19,均P < 0.05）。良恶性结节分叶、毛刺、胸膜尾征、血管集束征之间的差异有统计学意义（χ2=9.27、10.36、14.31和17.52,均P < 0.05）。11C-CHO+18F-FDG双时相PET/CT+HRCT联合显像的灵敏度为81.8%,特异度为94.1%,准确率为96.4%,明显高于非联合显像。结论 11C-CHO+18F-FDG双时相PET/CT+HRCT能较好地鉴别SPN的良恶性,三者联合能提高对SPN的诊断率。     

Diagnostic accuracy of 18F-FDG PET/CT in characterizing ovarian lesions and staging ovarian cancer: correlation with transvaginal ultrasonography, computed tomography, and histology

AIMS: To (a) assess the accuracy of 18F-FDG PET/CT in distinguishing malignant from benign pelvic lesions, compared to transvaginal ultrasonography (TVUS) and (b) to establish the role of whole-body 18F-FDG PET/CT, compared to contrast enhanced computed tomography (CT), in staging patients with ovarian cancer. PATIENTS: Fifty consecutive patients with a pelvic lesion, already scheduled for surgery on the basis of physical examination, TVUS, and serum Ca125 levels, were enrolled in the study. Patients' age ranged between 23 and 89 years (mean 64). All patients underwent TVUS including a colour Doppler study followed by a thorax and abdominal CT scan, and whole-body 18F-FDG PET/CT within 2 weeks prior to surgery. Histological findings obtained at surgery were taken as the 'gold standard' to compare 18F-FDG PET/CT and TVUS, and 18F-FDG PET/CT vs. CT. When tissue analysis showed ovarian cancer, the accuracy of 18F-FDG PET/CT and CT were compared for the purpose of obtaining a precise staging. RESULTS: At surgery, the ovarian lesions were malignant in 32/50 patients (64%) and benign in the remaining 18/50 patients (36%). The sensitivity, specificity, NPV, PPV and accuracy of 18F-FDG PET/CT were 87%, 100%, 81%, 100% and 92%, respectively, compared with 90%, 61%, 78%, 80% and 80%, respectively, for TVUS. In staging ovarian cancer, 18F-FDG PET/CT results were concordant with final pathological staging in 22/32 (69%) patients while CT results were concordant in 17/32 (53%) patients. CT incorrectly down-staged four out of six stage IV patients by missing distant metastasis in the liver, pleura, mediastinum, and in left supraclavicular lymph nodes, which were correctly detected by 18F-FDG PET/CT. CONCLUSION: PET/CT with 18F-FDG provides additional value to TVUS for the differential diagnosis of benign from malignant pelvic lesions, and to CT for the staging of ovarian cancer patients.     

18F-FDG PET/CT结合高分辨率CT对孤立性肺结节的

 目的 探讨18F-FDG PET/CT显像结合高分辨率CT(high resolution CT,HRCT)对孤立性肺结节(solitary pulmonary nodule,SPN)的诊断价值。方法 回顾性分析124例SPN患者的18F-FDG PET/CT检查资料,其中76例加做HRCT扫描,所有病例经病理或临床随访证实。18F-FDG PET/CT通过目测法和半定量法判断病灶的代谢情况,结合CT或HRCT病灶的形态学特征判断良、恶性。结果 48例仅行18F-FDG PET/CT检查的SPN患者,正确诊断32例为恶性,8例为良性,假阳性与假阴性各4例。76例加做HRCT的患者,正确诊断62例恶性与8例良性,假阳性与假阴性分别为2例和4例。18F-FDG PET/CT 结合HRCT与单纯18F-FDG PET/CT诊断SPN的灵敏度、特异性及准确率分别为94%、80%、90%与89%、67%、83%。结论 18F-FDG PET/CT协同HRCT可提高对SPN性质判断的灵敏度、特异性及准确率。     

Impact of 18F-FDG PET/CT on therapeutic decisions in patients with colorectal cancer and liver metastases

ObjectivesSurgical resection and radio-frequency ablation (RFA) are standard therapeutic procedures for colorectal metastases confined to the liver. The presence of extrahepatic disease has a significant effect on the management of these patients. The goal of this study is to assess the value of positron emission tomography/computed tomography with 18F-fluorodeoxyglucose (18F-FDG PET/CT) in the decision making whether to perform RFA or surgical resection of liver metastases in patients with metastatic colorectal cancer.Material and methodsThirty-five consecutive patients (23 men, 12 women; age range: 46–78 years) with colorectal carcinoma and liver metastases were prospectively enrolled. Nineteen of them were considered candidates for surgical resection and 16 for RFA. All underwent 18F-FDG PET/CT, helical computed tomography of the chest and abdomen and, some of them, magnetic resonance imaging of the abdomen. The 18F-FDG PET/CT studies were performed within 4 weeks from conventional imaging, and additional findings were later confirmed or not, either by histology or follow up.ResultsIn the surgical candidate group, 18F-FDG PET/CT detected extrahepatic disease, missed by conventional imaging, in 9/19 patients (47.3%). These findings directly altered the management in 7 patients (36.8%). In the group of RFA candidates, 18F-FDG PET/CT detected additional extrahepatic disease in 4/16 patients (25%) and directly altered management in all of them. Overall, in 11/35 patients (31.4%), 18F-FDG PET/CT detected extrahepatic metastatic disease.ConclusionIn patients with colorectal cancer and liver metastases, 18F-FDG PET/CT provides relevant additional information that has significant impact on management.     

血管免疫母细胞T细胞淋巴瘤^18MF-FDGPET/CT的影像表现及其在临床分期中的价值

目的分析血管免疫母细胞T细胞淋巴瘤（angioimmunoblasticT-celllymphoma,AITL）^18F-FDGPET/CT的影像学表现及分布规律,探讨其在临床分期中的价值。方法回顾性分析22例AITL患者的^18F-FDGPET/CT显像结果,评价其在临床分期中的价值。结果（1）AITL结内侵犯的^18F-FDGPET/CT影像学表现：①全身弥漫性分布：左右对称性分布9例（40．9％）,左右不对称性分布2例（9．1％）;②多部位散在分布：与淋巴链走行有关4例（18．2％）,与淋巴链走行无关5例（22．7％）;③单部位局限性分布2例（9．1％）;（2）AITL结外侵犯的^18F-FDGPET／CT影像学表现：鼻咽部侵犯最常见有10例,其余依次为口咽8例,脾脏8例,骨骼及骨髓5例,胃肠道4例,肺、胸膜及皮肤各2例,乳腺及颅内侵犯各1例;（3）在AITL分期中的价值：PET/CT显像改变了4例（18．2％,4/22）患者的分期,均为分期上调。结论血管免疫母细胞T细胞淋巴瘤呈”F-FDG高摄取;其在病灶检测及分期方面,^18F-FDGPET/CT显像有优势。     

~(18)F-FDG符合线路SPECT/CT对肺孤立性病变的诊断价值

目的：应用^18F-脱氧葡萄糖（^18F-FDG）符合线路SPECT/CT显像半定量分析,探讨符合线路SPECT/CT对肺部孤立性病变的诊断价值。方法：回顾性分析经病理或随访证实的74例肺孤立性病变患者的^18F-FDG符合线路SPECT/CT图像,用半定量法（计算病灶组织与周围正常软组织的摄取比值,即T/NT）测量,所得数据进行统计学分析。结果：半定量分析显示恶性病变摄取^18F-FDG比值（9.57±6.13）明显高于良性病变（2.99±1.59）,差异有统计学意义（P〈0.05）。以T/NT≥3.5作为恶性病变的判定标准,74例肺孤立性病变中,真阳性49例,真阴性16例,假阳性7例,假阴性2例。敏感度、特异度、准确率、阳性预测值和阴性预测值分别为96.08%、69.57%、87.84%、87.50%和88.89%。结论：18F-FDG符合线路SPECT/CT显像对肺孤立性病变的诊断、鉴别诊断及预后评估具有重要的临床应用价值。     

Clinical significance of small pulmonary nodules with little or no 18F-FDG uptake on PET/CT images of patients with nonthoracic malignancies.

Small pulmonary nodules with little or no perceptible (18)F-FDG uptake are relatively common findings on combined PET/CT images of patients with nonthoracic malignancies. Interpreting such nodules is often a diagnostic challenge, and this study aimed to evaluate the clinical significance of the nodules. METHODS: Patients with pulmonary nodules < or =1 cm in diameter showing no (18)F-FDG uptake or uptake less than the mediastinal background were included. Nodules with clearly benign or metastatic findings on CT were excluded. One hundred twenty-one patients had either tissue confirmation or clinical follow-up with additional chest images. The subjects were studied by 3 variables: (i) solitary versus multiple nodules, (ii) presence of accompanying benign lung lesion versus absence, and (iii) imperceptible (18)F-FDG uptake versus faint (18)F-FDG uptake. The malignancy rates were calculated for each variable. RESULTS: Of the 121 patients, 24 had malignancy, with a strong possibility of pulmonary metastasis (19.8%). Six of the 44 patients with solitary nodules (13.6%) and 18 of the 77 patients with multiple nodules (23.4%) had malignancies, though there was no statistically significant difference in the incidences of malignancy between the solitary and multiple groups. On the other hand, there was a statistically significant difference (P = 0.040) between the accompanying lung lesion present (8.3%) and absent (24.7%) groups. No statistically significant difference was noted between the (18)F-FDG uptake imperceptible group and faint (18)F-FDG uptake group (20.7% vs. 17.2%). CONCLUSION: For patients with incidental lung nodules of indeterminate nature with no (18)F-FDG uptake or uptake less than that of the mediastinum on PET/CT images, >19% of the cases turned out to be malignant. The nodule was more likely to be malignant when no other benign pulmonary lesions could be identified elsewhere in the lung field. Thus, regardless of the number of nodules and (18)F-FDG uptake, tissue confirmation or close imaging follow-up is necessary when small nodules with imperceptible or faint (18)F-FDG activity are present on the PET/CT images, especially in the absence of accompanying benign lung lesions.     

Complementary roles of 18F-DOPA PET/CT and 18F-FDG PET/CT in medullary thyroid cancer

Serum calcitonin and carcinoembryonic antigen (CEA) are markers of recurrent or persistent disease in medullary thyroid cancer (MTC). However, conventional imaging often fails to localize metastatic disease. Our aim was to compare fluorine-labeled dihydroxyphenylalanine ((18)F-DOPA) and (18)F-FDG PET/CT with multidetector CT (MDCT) and MRI in recurrent or persistent MTC. METHODS: Nineteen MTC patients with increased calcitonin or CEA on follow-up (mean ± SD, 93 ± 91 mo; range, 4-300 mo) after primary therapy were prospectively imaged with 4 techniques: (18)F-DOPA PET/CT, (18)F-FDG PET/CT, MDCT, and MRI. Images were analyzed for pathologic lesions, which were surgically removed when possible. The correlation between the detection rate for each method and the calcitonin and CEA concentrations and histopathologic findings was investigated. Results: On the basis of histology and follow-up, one or more imaging methods accurately localized metastatic disease in 12 (63%) of 19 patients. The corresponding figures for (18)F-DOPA PET/CT, (18)F-FDG PET/CT, MDCT, and MRI were 11 (58%) of 19, 10 (53%) of 19, 9 (47%) of 19, and 10 (59%) of 17, respectively. Calcitonin and CEA correlated with (18)F-DOPA PET/CT (P = 0.0007 and P = 0.0263, respectively) and (18)F-FDG PET/CT findings (both P < 0.0001). In patients with an unstable calcitonin doubling time (n = 8), (18)F-DOPA and (18)F-FDG PET/CT were equally sensitive. In contrast, for patients with an unstable CEA doubling time (n = 4), (18)F-FDG PET/CT was more accurate. CONCLUSION: For most MTC patients with occult disease, (18)F-DOPA PET/CT accurately detects metastases. In patients with an unstable calcitonin level, (18)F-DOPA PET/CT and (18)F-FDG PET/CT are complementary. For patients with an unstable CEA doubling time, (18)F-FDG PET/CT may be more feasible. MRI is sensitive but has the highest rate of false-positive results.