Exploring new frontiers in molecular imaging: Emergence of Ga PET/CT

Since US Food and Drug Administration approval of 18-fluorodeoxyglucose as a positron tracer, and the development of hybrid positron emission tomography/computed tomography machines, there has been a great increase in clinical application and progress in the field of nuclear molecular imaging. However, not underestimating the value of (18)F, there are known limitations in the use of this cyclotron-produced positron tracer. We hence turn our focus to an emerging positron tracer, (68)Ga, and examine the advantages, current clinical uses and potential future applications of this radioisotope.     

PET/CT和PET/MR在黑色素瘤中的临床应用及新进展

黑色素瘤易转移、复发率高,已经成为严重危及人民健康的恶性肿瘤之一,早期诊断和准确分期对预后及远期生存十分关键。18F-FDG PET/CT作为一项集PET与CT于一体的成像模式,被广泛地应用于包括黑色素瘤等在内的恶性肿瘤的诊断、分期及疗效的评估。随着一体化PET/MR成像系统研发的成功,多模态成像技术向前迈进了一大步,实现了真正意义上的数据同步采集。笔者就18F-FDG PET/CT及PET/MR在黑色素瘤分期、复发和疗效评价中的研究现状进行综述,介绍了多模态成像技术在黑色素瘤中的新进展。     

Evaluation of Dixon Sequence on Hybrid PET/MR Compared with Contrast-Enhanced PET/CT for PET-Positive Lesions

Purpose

Hybrid positron emission tomography and magnetic resonance (PET/MR) imaging performs a two-point Dixon MR sequence for attenuation correction. However, MR data in hybrid PET/MR should provide anatomic and morphologic information as well as an attenuation map. We evaluated the Dixon sequence of hybrid PET/MR for anatomic correlation of PET-positive lesions compared with contrast-enhanced PET/computed tomography (CT) in patients with oncologic diseases.

Methods

Twelve patients underwent a single injection, dual imaging protocol. PET/CT was performed with an intravenous contrast agent (85 ± 13 min after ¹⁸F-FDG injection of 403 ± 45 MBq) and then (125 ± 19 min after injection) PET/MR was performed. Attenuation correction and anatomic allocation of PET were performed using contrast-enhanced CT for PET/CT and Dixon MR sequence for hybrid PET/MR. The Dixon MR sequence and contrast-enhanced CT were compared for anatomic correlation of PET-positive lesions (scoring scale ranging from 0 to 3 for visual ratings). Additionally, standardized uptake values (SUVs) for the detected lesions were assessed for quantitative comparison.

Results

Both hybrid PET/MR and contrast-enhanced PET/CT identified 55 lesions with increased FDG uptake in ten patients. In total, 28 lymph nodes, 11 bone lesions, 3 dermal nodules, 3 pleural thickening lesions, 2 thyroid nodules, 1 pancreas, 1 liver, 1 ovary, 1 uterus, 1 breast, 1 soft tissue and 2 lung lesions were present. The best performance was observed for anatomic correlation of PET findings by the contrast-enhanced CT scans (contrast-enhanced CT, 2.64 ± 0.70; in-phase, 1.29 ± 1.01; opposed-phase, 1.29 ± 1.15; water-weighted, 1.71 ± 1.07; fat weighted, 0.56 ± 1.03). A significant difference was observed between the scores obtained from the contrast-enhanced CT and all four coregistered Dixon MR images. Quantitative evaluation revealed a high correlation between the SUVs measured with hybrid PET/MR (SUVmean, 2.63 ± 1.62; SUVmax, 4.30 ± 2.88) and contrast-enhanced PET/CT (SUVmean, 3.88 ± 2.30; SUVmax, 6.53 ± 4.04) in PET-positive lesions (SUVmean, ρ = 0.93; SUVmax, ρ = 0.95), although hybrid PET/MR presented a decrease of SUVs compared with contrast-enhanced PET/CT (mean reduction; SUVmean, 32.44 ± 15.64 %; SUVmax, 35.16 ± 12.59 %).

Conclusions

Despite different attenuation correction approaches, the SUV of PET-positive lesions correlated well between hybrid PET/MR and contrast-enhanced PET/CT. However Dixon MR images acquired for attenuation correction were insufficient to provide anatomic information of PET images because of low spatial resolution. Thus, additional MR sequence with fast and higher resolution may be necessary for anatomic information.     

放射性核素标记的胆碱在PET/CT肿瘤显像中的应用

18F-FDG PET/CT可明显提高恶性肿瘤诊断的准确性,指导恶性肿瘤的分期与再分期,对患者治疗方案的选择产生了重要影响。其在全身许多肿瘤中的应用价值已获得认可,但还存在一些不足。随着正电子标记药物的不断研发,放射性核素标记的胆碱逐渐应用于临床。胆碱是细胞膜的重要组成成分,恶性肿瘤的胆碱代谢增高。近年来的研究表明,胆碱PET/CT在胶质瘤、头颈部肿瘤、肺癌、肝细胞肝癌、前列腺癌、膀胱肿瘤等的诊断、分期及复发检测等方面具有很好的应用价值,特别是对颅内病变的观察、高分化肝细胞肝癌的诊断、生物靶区勾画、复发病灶的定位等,在一定程度上弥补了18F-FDG PET/CT的不足。笔者回顾了放射性核素标记的胆碱（11C-胆碱和18F-胆碱）在肿瘤显像中的应用。     

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。     

Performance evaluation of the new whole-body PET/CT scanner: Discovery ST

Characterisation of the physical performance of the new integrated PET/CT system Discovery ST (GE Medical Systems) has been performed following the NEMA NU 2-1994 (N-94) and the NEMA NU 2-2001 (N-01) standards in both 2D and 3D acquisition configuration. The Discovery ST combines a four or eight multi-slice helical CT scanner with a PET tomograph which consists of 10,080 BGO crystals arranged in 24 rings. The crystal dimensions are 6.3×6.3×30 mm³ and they are organised in blocks of 6×6 crystals, coupled to a single photomultiplier tube with four anodes. The 24 rings of the PET system allow 47 images to be obtained, spaced by 3.27 mm, and covering an axial field of view of 157 mm. The low- and high-energy thresholds are set to 375 and 650 keV, respectively. The coincidence time window is set to 11.7 ns. Using the NEMA N-94 standard, the main results were: (1) the average (radial and tangential) transverse spatial resolution (FWHM) at 1, 10 and 20 cm off axis was 6.28 mm, 7.09 mm and 7.45 mm in 2D, and 6.68 mm, 7.72 mm and 8.13 mm in 3D; (2) the sensitivity for true events was 8,567 cps/kBq/cc in 2D and 36,649 cps/kBq/cc in 3D; (3) the scatter fraction was 15% in 2D and 30% in 3D; (4) the peak true events rate, the true events rate at 50% of the system dead-time and the true events rate when equal to the random events rate were 750 kcps at 189.81 kBq/cc, 744 kcps at 186.48 kBq/cc and 686 kcps at 150.59 kBq/cc, respectively, in 2D, and 922 kcps at 44.03 kBq/cc, 834 kcps at 53.28 kBq/cc and 921 kcps at 44.03 kBq/cc in 3D; (5) the noise equivalent count (NEC) peak rate was 270 kcps at 34.38 kBq/cc in 3D, with random coincidences estimated by delayed events. Using the NEMA N-01 standards the main results were: (1) the average transverse and axial spatial resolution (FWHM) at 1 cm and 10 cm off axis was 6.28 (4.56) mm and 6.88 (6.11) mm in 2D, and 6.29 (5.68) mm and 6.82 (6.05) mm in 3D; (2) the average sensitivity for the two radial positions (r=0 cm and r=10 cm) was 1.93 cps/kBq in 2D and 9.12 cps/kBq in 3D; (3) the scatter fraction was 19% in 2D and 45% in 3D; (4) the NEC peak rate was 54 kcps at 46.99 kBq/cc in 2D and 45.5 kcps at 10.84 kBq/cc in 3D, when random coincidences were estimated by using k=2 in the NEC formula, while the NEC peak rate was 81 kcps at 64.43 kBq/cc and 66 kcps at 14.86 kBq/cc in 2D and 3D, respectively, when random coincidences were estimated by using k=1 in the NEC formula. The new integrated PET-CT system Discovery ST has good overall performances in both 2D and 3D, with in particular a high sensitivity and a very good 3D NEC response.     

Attenuation correction in cardiac PET/CT with three different CT protocols: a comparison with conventional PET

Purpose CT-based attenuation correction may influence cardiac PET owing to its higher susceptibility to misalignment compared with conventional ⁶⁸Ge transmission scans. The aims of this study were to evaluate whether CT attenuation correction leads to changes in tracer distribution compared with conventional cardiac PET and to determine a suitable CT protocol. Methods A total of 27 patients underwent PET/CT and subsequently a PET scan. Twenty patients received a low-dose CT (LDCT group; 120 kV, 26 mA, 8-s scan time), seven patients a slow CT (SCT group; 120 kV, 99 mA, 46-s scan time) and ten patients an ultra-low-dose CT (ULDCT group; 80 kV, 13 mA, 5-s scan time) as the transmission scan in PET/CT. Polar maps were divided into 17 segments and regression analysis was computed in every scan pair (CT attenuation corrected–⁶⁸Ge attenuation corrected). Correlation coefficient (r), the slope (s) and the offset (os) of the regression line were determined. Visual assessment of misalignment between the transmission and emission data was performed. The effective dose of the different transmission scans was calculated. Results Overall, there was a moderate correlation between the mean values measured in all segments on PET/CT and on PET when using LDCT (r=0.78, p<0.0001), SCT (r=0.79, p<0.0001) and ULDCT (r=0.82, p<0.0001). No differences were observed when comparing the scores assigned in the visual misalignment assessment in the three groups (p=0.12). The differences between the results from the regression analysis observed in the respective groups were not statistically significant (Kruskal-Wallis p=0.11 for r, p=0.67 for s and p=0.27 for os). The effective dose was lowest for the ULDCT. Conclusion Our study shows that CT-based attenuation correction is feasible for cardiac PET imaging. The results indicate that ultra-low-dose CT is the preferable choice for transmission scanning.     

18F-FDG PET/CT and contrast-enhanced CT findings of pulmonary cryptococcosis

PurposePulmonary cryptococcosis is an uncommon cause of pulmonary nodules in non-AIDS patients. This study reports the ¹⁸F-fluorodeoxyglucose-positron emission tomography (¹⁸F-FDG PET/CT) and contrast-enhanced CT (CE-CT) findings of 42 patients with pulmonary cryptococcosis.Materials and methodsA retrospective review of the ¹⁸F-FDG PET/CT and CE-CT findings of 42 patients with histologically proven pulmonary cryptococcosis was conducted. All patients underwent PET/CT and CE-CT in the same session. The CT diagnosis was based on the location, morphological features, and enhancement of lesions. The PET/CT findings were recorded, and clinical data and surgical and histopathological findings were collected.ResultsThe results of the PET scans revealed that 37 (88%) of 42 patients showed higher FDG uptake, and 5 (12%) patients demonstrated lower FDG uptake than the mediastinal blood pool. The maximum standardized uptake value (SUV) of pulmonary cryptococcosis ranged from 1.4 to 13.0 (average: 5.7 ± 3.3, median 4.9). A single nodular pattern was the most prevalent pattern observed and was found in 29 (69%) patients. This pattern was followed by scattered nodular (n = 4, 10%), clustered nodular (n = 3, 7%), mass-like (n = 3, 7%), and bronchopneumonic (n = 3, 7%) patterns. The most frequent pattern of immunocompetent patients was the single nodular pattern (29 of 33, 88%). Immunocompromised patients most frequently pattern exhibited mass-like (3 of 9, 33%) and bronchopneumonic (3 of 9, 33%) patterns.ConclusionPulmonary cryptococcosis most commonly appears as single nodules in immunocompetent patients. Mass-like and bronchopneumonic patterns were common in immunocompromised patients. In 88% of patients, lung lesions showed high FDG uptake, thus mimicking a possible malignant condition.     

From PET detectors to PET scanners

This review describes the properties of available and emerging radiation detector and read-out technologies and discusses how they may affect PET scanner performance. After a general introduction, there is a section in which the physical properties of several different detector scintillators are compared. This is followed by a discussion of recent advances in read-out electronics. Finally, the physical performance of the several commercial PET scanners is summarized.     

PET/CT冠状动脉血流储备测定在冠状动脉微血管性疾病中的研究进展

冠状动脉微血管性疾病（CMVD）是指在多种致病因素下,冠状动脉微血管结构和（或）功能异常所致的劳力性心绞痛或心肌缺血客观证据的临床综合征。CMVD在冠心病中仍有较高的发病率,部分CMVD预后不佳,对其进行早期诊断、预后评估和治疗干预均具有重要的临床意义。PET/CT定量分析能客观、准确地测量静息和负荷状态下冠状动脉血流灌注量,进而获得冠状动脉血流储备,有效地协助早期诊断CMVD,评估其预后和指导治疗。笔者就PET/CT血流储备测定在CMVD中的研究进展进行综述。     

PET recognition of pulmonary metastases on PET/CT imaging: impact of attenuation-corrected and non-attenuation-corrected PET images

Purpose The aims of this study were to assess the performance of FDG PET at PET/CT imaging for the detection of pulmonary metastases and to evaluate differences in lesion detectability on attenuation-corrected (AC) and non-attenuation corrected (NAC) PET images.Methods The institutional PET/CT database was searched for patients with pulmonary metastases of 3–60 mm in diameter. Ninety-two patients with 438 metastases to the lungs were included in the study. The primary tumours were 33 malignant melanomas, 12 carcinomas of unknown primary, 11 colorectal carcinomas, eight differentiated thyroid carcinomas, seven aggressive non-Hodgkins lymphomas, six head and neck cancers, three breast cancers, two prostate cancers and ten others. Lesion detectability was visually compared between PET and CT and between AC and NAC PET images using a five-point scale.Results Of the 438 pulmonary metastases, 174 were detected with FDG PET (39.7%), six of them on NAC images only (not significant). Visual scores were higher on NAC images in 41.4% and equal in 54.6% of lesions. The sensitivity of FDG PET increased significantly from 0.405 for metastases of 5–7 mm in diameter to 0.784 for lesions of 8–10 mm and to 0.935 for lesions measuring 11–29 mm in diameter. No metastases smaller than 5 mm in diameter were seen on PET images.Conclusion FDG PET/CT is useful for the assessment of pulmonary metastases. The frequency of lesion detection is similar for AC and NAC PET images. A reduced sensitivity of FDG PET has to be considered for lesions smaller than 11 mm in diameter.     

PET/CT和MRI在多发性骨髓瘤中的应用与进展

多发性骨髓瘤（MM）是一种恶性B细胞肿瘤,其主要累及骨髓,部分也可出现髓外浸润。影像学检查是全面评估MM不可或缺的手段,X射线与CT对病灶的检出率低、定量能力差。PET/CT与MRI对MM的评估具有较大的价值,特别是18F-FDG及其他新型分子探针,全身扩散加权成像、动态增强MRI及水脂分离等MRI新技术。笔者就PET/CT及MRI在MM中的应用与进展进行综述。     

自动管电流调制技术在PET/CT中的实际应用

目的探讨自动管电流调制（ATCM）技术对PET/CT受检者CT图像质量及有效剂量的影响。方法将2017年10月至2018年7月接受PET/CT检查的90例受检者按系统抽样方法分为A、B、C 3组,每组各30例。CT采用ATCM扫描。A、B两组采用的管电流区间为60~240 mA,噪声指数分别为10、15;C组管电流区间为60~180 mA,噪声指数为15。记录容积CT剂量指数（CTDIvol）和剂量长度乘积（DLP）,根据公式估算有效剂量。由两位核医学科主治及以上医师采用双盲法对受检者颈部、胸部、腹部、盆腔CT图像质量进行评分,测定图像CT值、噪声值并计算信噪比。采用方差分析比较3组的噪声值、信噪比差异,采用非参数检验中的Kruskal-Wallis检验比较3组的CTDIvol、DLP、有效剂量差异,组内两两比较采用Nemenyi检验。结果A、B、C 3组受检者所有图像质量评分均不低于3分,且差异均有统计学意义(F=3.77~14.42,均P<0.05)。A、B、C 3组受检者的噪声值[（11.90±2.83）~（26.03±3.74）]、信噪比[（2.03±0.34）~（4.35±0.71）]差异均有统计学意义（F=38.01~64.20和F=32.09~81.62,均P<0.05）,CT图像质量均能满足临床诊断要求。A、B、C 3组受检者的CTDIvol[（12.44±0.53）、（9.39±2.01）和（7.05±1.03）mGy]、DLP[（998.45±96.04）、（741.60±168.87）和（571.29±97.41） mGy·cm]、有效剂量[（14.98±1.44）、（11.12±2.53）和（8.57±1.46） mSv]的差异均有统计学意义（χ2=62.18、57.19和57.16,均P<0.05）。其中,C组比A组的有效剂量低,差异有统计学意义（χ2=56.55,P<0.05）。结论应用PET/CT ATCM技术,合理调节管电流区间及噪声指数,保证图像质量的同时可有效降低受检者的有效剂量。     

PET/CT and vascular disease: current concepts

Since its introduction in 2001, positron emission tomography associated to computed tomography (PET/CT) has been established as a standard tool in cancer evaluation. Being a multimodality imaging method, it combines in a single session the sensitivity granted by PET for detection of molecular targets within the picomolar range, with an underlying submilimetric resolution inherent to CT, that can precisely localize the PET findings.In this last decade, there have been new insights regarding the pathophysiology of atherosclerosis, particularly about plaque rupture and vascular remodeling. This has increased the interest for research on PET/CT in vascular diseases as a potential new diagnostic tool, since some PET molecular targets could identify diseases before the manifestation of gross anatomic features.In this review, we will describe the current applications of PET/CT in vascular diseases, emphasizing its usefulness in the settings of vasculitis, aneurysms, vascular graft infection, aortic dissection, and atherosclerosis/plaque vulnerability. Although not being properly peripheral vascular conditions, ischemic cardiovascular disease and cerebrovascular disease will be briefly addressed as well, due to their widespread prevalence and importance.     

皮病性淋巴结炎的FDG PET/CT表现及临床病理研究(附2例报告及文献复习)

目的 探讨皮病性淋巴结炎(DL)的临床病理及18F-FDG PET/CT表现特点,提高对本病的诊断水平.方法 搜集本院2例病理确诊为DL的患者资料,并检索国内外近10年关于DL的文献,回顾性分析DL的临床病理及PET/CT表现特点.结果 2例患者临床均表现为反复发热,全身浅表淋巴结肿大,皮肤瘙痒伴红斑,骨髓增生活跃.PET/CT检查发现2例患者全身多处淋巴结肿大伴糖代谢增高,SUVmax＞ 2.5,摄取18FDG最高的部位在腋窝,SUVmax达12,同时均伴有脾肿大伴糖代谢增高,骨髓浓聚增高.结论 DL患者在PET/CT上多表现为全身多处淋巴结肿大伴18FDG摄取增高,腋窝、腹股沟、颈部多见,呈对称性分布,无融合趋势.DL的主要临床表现为全身多发无痛性淋巴结肿大,常伴有皮肤改变.病理为非特异性淋巴结反应性增生.     

68Ga-枸橼酸PET/CT在炎症及感染疾病中的应用进展

炎症及感染的早期、准确诊断有利于及时有效地治疗。68Ga-枸橼酸是一种新型核医学正电子炎症示踪剂,能够与体内转铁蛋白结合,在病灶部位形成放射性浓集,且生产成本低、半衰期适中、辐射剂量低,在骨感染、腹腔感染、炎性肠病的诊断以及肺部病变良恶性的鉴别诊断中表现出良好的特性,尤其在骨感染早期的诊断及鉴别诊断中作用突出。就68Ga-枸橼酸PET/CT在炎症和感染显像方面的研究进展进行介绍。     

PET/CT不同评价体系在弥漫性大B细胞淋巴瘤预后评估中的应用

弥漫性大B细胞淋巴瘤（DLBCL）是发病率较高的淋巴造血系统疾病,该病进展较快、病死率较高。如何通过现有的检查技术精确地对患者进行预后评估是研究者们面临的一大难题。目前,PET/CT以其能同时提供解剖及功能图像的独特优势,广泛地应用于淋巴瘤的治疗监测及预后评估中,但采用哪种评价体系对图像进行判读的准确率更高仍存在较大争议。笔者综述了PET/CT定性、半定量及其他新的评价体系在DLBCL预后评估中的应用价值。     

双时相18F-FDG PET/CT显像在胰腺良恶性病变鉴别诊断中的应用

目的 探讨双时相18F-FDG PET/CT对胰腺良恶性病变鉴别诊断的价值.方法 回顾性分析2011年9月～2012年6月在我院行双时相18F-FDG PET/CT全身检查的胰腺病变患者41例,分别测定病灶早期及延迟标准摄取值（SUVmax）,计算18F-FDG的滞留指数（retention index,RI）;以病理及临床随访结果作为诊断标准,绘制SUVmax早期及RI的ROC曲线,寻找最佳诊断界值,分别计算SUVmax早期、RI为标准诊断胰腺癌敏感性、特异性及准确性.结果 41例胰腺病变患者中,恶性组（26例）SUVmax早期、SUVmax延迟、RI分别为8.2±2.7、10.5±4.1、（24.1±22.6）％,良性组（15例）SUVmax早期、SUVmax延迟、RI分别为4.0±3.7、4.3±3.8、（8.5±14.1）％;胰腺恶性病变SUVmax延迟较SUVmax早期明显升高（P＜0.001）,胰腺良性病灶延迟显像前后SUVmax差异无统计学意义（P=0.068）,胰腺良恶性组间RI差异有统计学意义（P=0.004）.本试验根据ROC曲线观察发现以SUV max=3.4为界值,诊断胰腺癌的敏感性、特异性及准确性分别为92.3％、66.7％、82.9％;以RI=9.1％为界值,诊断胰腺癌的敏感性、特异性及准确性分别为76.9％、73.3％及73.2％;SUVmax≥3.4结合RI≥9.1％诊断胰腺癌敏感性、特异性及准确性分别为88.5％、86.7％及87.8％.结论 应用双时相18F-FDG PET/CT显像能提高胰腺癌诊断特异性及准确性,但炎性（包括肿块型胰腺炎、自身免疫性胰腺炎、结核）延迟显像也可明显升高.     

The Prognostic Value of 18F-Fluorodeoxyglucose PET/CT in the Initial Assessment of Primary Tracheal Malignant Tumor: A Retrospective Study

ObjectiveTo investigate the potential value of ¹⁸F-fluorodeoxyglucose (FDG) PET/CT in predicting the survival of patients with primary tracheal malignant tumors.Materials and MethodsAn analysis of FDG PET/CT findings in 37 primary tracheal malignant tumor patients with a median follow-up period of 43.2 months (range, 10.8–143.2 months) was performed. Cox proportional hazards regression analyses were used to assess the associations between quantitative ¹⁸F-FDG PET/CT parameters, other clinic-pathological factors, and overall survival (OS). A risk prognosis model was established according to the independent prognostic factors identified on multivariate analysis. A survival curve determined by the Kaplan-Meier method was used to assess whether the prognosis prediction model could effectively stratify patients with different risks factors.ResultsThe median survival time of the 37 patients with tracheal tumors was 38.0 months, with a 95% confidence interval of 10.8 to 65.2 months. The 3-year, 5-year and 10-year survival rate were 54.1%, 43.2%, and 16.2%, respectively. The metabolic tumor volume (MTV), total lesion glycolysis (TLG), maximum standardized uptake value, age, pathological type, extension categories, and lymph node stage were included in multivariate analyses. Multivariate analysis showed MTV (p = 0.011), TLG (p = 0.020), pathological type (p = 0.037), and extension categories (p = 0.038) were independent prognostic factors for OS. Additionally, assessment of the survival curve using the Kaplan-Meier method showed that our prognosis prediction model can effectively stratify patients with different risks factors (p < 0.001).ConclusionThis study shows that ¹⁸F-FDG PET/CT can predict the survival of patients with primary tracheal malignant tumors. Patients with an MTV > 5.19, a TLG > 16.94 on PET/CT scans, squamous cell carcinoma, and non-E1 were more likely to have a reduced OS.     

PET/CT in oncology--a major advance

The concept of hardware fusion between positron emission tomography (PET) and computed tomography (CT) has only been introduced commercially in the last 4 years. The advantages of this combined technique over PET alone have become obvious. There is increasing evidence to suggest that PET/CT adds complementary information in staging, re-staging and follow-up in oncology patients, leading to changes in management plans. The present paper is a review of the strengths, weaknesses, current evidence and future directions of this technique.