Assessment of liver tissue after radiofrequency ablation: findings with different imaging procedures.

Our goal was to assess the typical appearance of normal liver tissue immediately after radiofrequency ablation (RF-ablation) when imaged with contrast-enhanced ultrasound, CT, MRI, 18F-FDG PET, and PET/CT. METHODS: Nineteen RF-ablation sessions were performed on nontumorous liver tissue of 10 G?ttingen Mini Pigs. CT, ultrasound, MRI, 18F-FDG PET, and PET/CT were performed immediately after the intervention. All imaging procedures were evaluated qualitatively for areas of increased contrast enhancement (morphologic imaging) and regions of elevated tracer uptake (functional imaging). Images were assessed quantitatively by determination of ratios (r(p/p)) comparing contrast enhancement/tracer uptake in the periphery of the necrosis with contrast enhancement/tracer uptake of normal liver parenchyma. RESULTS: On morphologic imaging, an increase in contrast enhancement surrounding the ablative necrosis was detected in all lesions. Quantification of this area of increased contrast enhancement revealed ratios of r(p/p) = 1.57 +/- 0.2 for CT and r(p/p) = 1.57 +/- 0.19 for MRI. On PET and PET/CT, homogeneous tracer utilization was found surrounding all lesions. There were no areas of a focal or rim-like increase in glucose metabolism. The ratio r(p/p) was found to be 1.05 +/- 0.08 for functional data. Histologic examination revealed pooling of blood in the sinusoids of the lesion's periphery that was caused by outflow obstruction due to the central necrosis. CONCLUSION: On morphologic imaging, a rim-like increase of contrast enhancement was found immediately after RF-ablation resembling peripheral hyperperfusion. This area of contrast enhancement may hamper detection of residual tumor. On the basis of homogeneous tracer distribution surrounding the area of necrosis, PET and PET/CT may serve for early assessment of patients after RF-ablation.     

正常犬肝脏射频消融后CT、正电子发射计算机体层成像-CT与病理表现的比较

目的 比较正常犬肝脏射频消融(RFA)后不同时期的病理、CT及PET-CT表现,为肝脏肿瘤RFA后随访方案的制定提供指导及参考依据.方法 成年健康杂种犬15只,随机数字表法分为5组(RFA后即刻组、1周组、2周组、4周组和8周组),每组3只.对每只犬肝脏行2次RFA治疗,消融后的实验犬于所在组对应的时间点行CT和PET-CT检查,完成检查后,静脉注射氯化钾溶液牺牲后,腹部切口取肝脏标本行病理检查.以消融灶周围环形反应带与正常肝实质强化/摄取率(r_(p/p))变化对图像进行评估,并将影像表现与病理改变进行对比分析.结果 RFA术后即刻组,病理检查显示,消融灶中央凝固坏死,周围肝窦扩张充血;增强CT消融灶周围出现明显的环形强化带;PET-CT表现为低代谢消融灶被等代谢肝组织环绕.1～4周组,病理检查显示,消融灶坏死程度逐渐加重,周围肝组织表现为炎症细胞浸润、肉芽组织形成并逐渐成熟;CT动脉期和PET-CT消融灶周围均呈环形强化和高代谢,尤以1～2周组明显.8周组,病理检查显示,消融灶周围纤维组织增生明显;PET-CT显示上述强化和高代谢征象消失.增强CT动态变化曲线为术后即刻组明显强化(r_(p/p)=1.34±0.21),1周组达峰值(r_(p/p)=1.39±0.20),之后逐渐回落;PET-CT代谢变化为单峰曲线,1周组为代谢峰值(r_(p/p)=1.19±0.09),即刻组及8周组分别趋于等代谢.结论 CT和PET-CT均可较准确的反映肝脏RFA后的病理改变.为规避RFA术后炎症反应对评价肿瘤残余的干扰,影像检查应在术后即刻和8周后进行.术后即刻PET-CT扫描可能优于CT,1周后两者的诊断效能可能相似.     

Evaluation of liver metastases after radiofrequency ablation: utility of 18F-FDG PET and PET/CT

OBJECTIVE: Our objective was to review the CT appearance of liver metastases after radiofrequency ablation and to describe the imaging findings of and utility of (18)F-FDG PET and PET/CT in assessing tumor recurrence after ablation. CONCLUSION: (18)F-FDG PET and PET/CT can provide added diagnostic information compared with conventional imaging in patients after radiofrequency ablation of liver metastases and can be useful in guiding repeat ablation procedures.     

Focal parenchymal lung lesions showing a potential of false-positive and false-negative interpretations on integrated PET/CT

OBJECTIVE: We describe a number of benign focal lung lesions with increased 18F-FDG uptake that simulate lung cancer and malignant lesions that lead to false-negatives due to little 18F-FDG uptake on integrated PET/CT images. CONCLUSION: The integration of clinical history, morphologic findings of lung parenchymal lesions on the CT component, and metabolic activities on the PET component of integrated PET/CT can help reduce false interpretation of the study. A lung biopsy may be needed for lesions showing increased 18F-FDG uptake on PET for tissue confirmation irrespective of their morphology on CT.     

骨上皮样血管内皮瘤的CT、MRI及18 F-FDG PET/CT表现(附2例报道)

目的探讨骨上皮样血管内皮瘤(EHE)的CT、MRI及18 F-FDG PET/CT表现,以提高对该病的影像学认识。方法回顾性分析2例经病理证实的骨上皮样血管内皮瘤患者的CT、MRI及18 F-FDG PET/CT检查图像资料,总结其影像特点。结果2例骨EHE中,1例为全身多发骨骼病变,1例仅为胸11椎体病变。CT表现病灶为边缘清晰,轻度硬化并呈分叶状改变的膨胀性溶骨性骨质破坏,病灶内见散在斑点状高密度影,周边软组织及椎间盘未见明显受累。MRI病灶呈稍长T 1、长T 2信号,其内可见散在斑点状低信号影,增强扫描病灶呈明显不均匀强化。病灶外周可见增强无强化的低信号环。18 F-FDG PET/CT主要表现为病灶部位的溶骨性骨质破坏伴SUV摄取值的升高。结论CT、MRI及18 F-FDG PET/CT检查能帮助评估骨上皮样血管内皮瘤的病灶性质及范围,协助下一步诊疗方案的确定。     

Predictive Value of Pattern Classification 24 Hours after Radiofrequency Ablation of Liver Metastases on CT and Positron Emission Tomography/CT

PurposeTo assess a classification scheme for predicting local tumor progression (LTP) after radiofrequency (RF) ablation of liver metastases, using predefined patterns on contrast-enhanced computed tomography (CT) and positron emission tomography (PET) combined with CT (PET/CT) acquired 24 hours after RF ablation.Materials and MethodsThere were 45 metastases in 20 patients treated. After 24 hours, imaging of the ablation zones was performed with contrast-enhanced PET/CT. Three independent radiologists prospectively assessed contrast-enhanced CT and combined PET/CT images to identify three patterns: pattern I, no tissue enhancement or fluorodeoxyglucose uptake between the ablation zone and the liver parenchyma; pattern II, a rimlike pattern; and pattern III, a peripheral nodule. PET/CT images obtained after 8–10 weeks were evaluated for LTP. The patterns were analyzed for their sensitivity, specificity, positive predictive value, and negative predictive value for predicting LTP.ResultsPattern I was most frequently observed (81% for contrast-enhanced CT and 61% for PET/CT) as well as for ablation zones that showed LTP (52% and 37%, respectively). Conversely, pattern II was observed for tumors that were completely ablated (6% and 29%, respectively). Patterns II and III together had the highest sensitivity for predicting LTP (48% and 63%, respectively); pattern III had the highest specificity (94% and 95%, respectively). For nodular patterns, test characteristics were better for PET/CT compared with contrast-enhanced CT, but the difference was not significant. Nodular patterns > 1 cm achieved high positive predictive value (both 100%).ConclusionsInflammation and hyperemia can hinder interpretation on imaging 24 hours after RF ablation, especially on PET/CT. Nodular patterns around the ablation zone on early contrast-enhanced CT and PET/CT have a high predictive value for LTP and should be taken into account for disease management.     

18F-FDG PET/CT in patients with suspected recurrent or metastatic well-differentiated thyroid cancer.

PET using 18F-FDG has been shown to effectively detect various types of cancer by their increased glucose metabolism. The aim of this study was to evaluate the use of coregistered PET and CT (PET/CT) in patients with suspected thyroid cancer recurrence. METHODS: After total thyroidectomy followed by radioiodine ablation, 61 consecutive patients with elevated thyroglobulin levels or a clinical suspicion of recurrent disease underwent 18F-FDG PET/CT. Of these, 59 patients had negative findings on radioiodine (131I) whole-body scintigraphy (WBS). Fifty-three of the 61 patients had both negative 131I WBS findings and elevated thyroglobulin levels. PET/CT images were acquired 60 min after intravenous injection of 400-610 MBq of 18F-FDG using a combined PET/CT scanner. Any increased 18F-FDG uptake was compared with the coregistered CT image to differentiate physiologic from pathologic tracer uptake. 18F-FDG PET/CT findings were correlated with the findings of histology, postradioiodine WBS, ultrasound, or clinical follow-up serving as a reference. The diagnostic accuracy of 18F-FDG PET/CT was evaluated for the entire patient group and for those patients with serum thyroglobulin levels of less than 5, 5-10, and more than 10 ng/mL. RESULTS: Thirty patients had positive findings on 18F-FDG PET/CT; 26 were true-positive and 4 were false-positive. In 2 patients, increased 18F-FDG uptake identified a second primary malignancy. 18F-FDG PET/CT results were true-negative in 19 patients and false-negative in 12 patients. The overall sensitivity, specificity, and accuracy of 18F-FDG PET/CT were 68.4%, 82.4%, and 73.8%, respectively. The sensitivities of 18F-FDG PET/CT at serum thyroglobulin levels of less than 5, 5-10, and more than 10 ng/mL were 60%, 63%, and 72%, respectively. Clinical management changed for 27 (44%) of 61 patients, including surgery, radiation therapy, or chemotherapy. CONCLUSION: Coregistered 18F-FDG PET/CT can provide precise anatomic localization of recurrent or metastatic thyroid carcinoma, leading to improved diagnostic accuracy, and can guide therapeutic management. In addition, the findings of this study suggest that further assessment of 131I WBS-negative, thyroglobulin-positive patients by 18F-FDG PET/CT may aid in the clinical management of selected cases regardless of the thyroglobulin level.     

^18F-FDG PET／CT在诊断转移性肝肿瘤中的应用

目的：探讨^18F-FDG PEF／CT在诊断转移性肝肿瘤中的应用。方法：回顾性分析49例转移性肝肿瘤患者的PET／CT影像资料,探讨^18F-FDG PET／CT诊断转移性肝肿瘤的影像表现及应用价值。结果：49例转移性肝肿瘤患者中45例^18F-FDG PET／CT表现为病灶^18F-FDG摄取明显高于周围正常肝组织;其中25例进行了延迟显像,22例表现为SUVmax及T／N值明显升高;发现肝转移同时伴有肝外转移患者38例。结论：^18F-FDG PET／CT诊断转移性肝肿瘤灵敏度高,准确,并可以同时对全身情况加以评价,对肿瘤患者肝转移的评价及治疗具有重要指导作用。     

Intraoperative radiation therapy in liver tissue in a pig model: monitoring with dual-modality PET/CT

PURPOSE: To assess, in a pig model, the value of dual-modality positron emission tomography (PET)/computed tomography (CT) for monitoring radiation therapy. MATERIALS AND METHODS: Central bile duct resection followed by creation of a biliodigestive anastomosis was performed in nine pigs. Six of these pigs were also treated with intraoperative radiation therapy (IORT) (20 Gy) in the area of the anastomosis. Two, 4, and 8 weeks postoperatively, contrast material-enhanced fluorine 18 fluorodeoxyglucose (FDG) PET/CT of the liver was performed in all of the animals. The radioactive tracer concentration in the region of the anastomosis was quantified, and the values were compared intraindividually with the values at the liver periphery. Histologic evaluation of the liver was performed 8 weeks postoperatively. The PET/CT images were assessed for changes in liver volume and bile duct diameter over time. RESULTS: In all nine pigs, the region of the anastomosis could be clearly defined on the fused PET/CT images. PET/CT revealed a decreased concentration of FDG in the irradiated field 2 and 4 weeks after IORT. At 8 weeks, however, the distribution of the tracer in the irradiated pigs did not differ from that in the nonirradiated pigs. Homogeneous tracer uptake in all liver regions was observed in the nonirradiated animals. The CT images showed an increase in liver volume in all pigs and bile duct dilatation that increased over time in the irradiated pigs. CONCLUSION: The morphologic and functional changes due to IORT in liver tissue can be accurately monitored with dual-modality PET/CT. By enabling the integration of functional and morphologic data, PET/CT may have an important role in monitoring radiation treatment.     

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.     

18F-FDG PET/CT in the evaluation of adrenal masses.

Our purpose was to evaluate the performance of (18)F-FDG PET/CT, using data from both the PET and the unenhanced CT portions of the study, in characterizing adrenal masses in oncology patients. METHODS: One hundred seventy-five adrenal masses in 150 patients referred for (18)F-FDG PET/CT were assessed. Final diagnosis was based on histology (n = 6), imaging follow-up (n = 118) of 6-29 mo (mean, 14 mo), or morphologic imaging criteria (n = 51). Each adrenal mass was characterized by its size; its attenuation on CT, expressed by Hounsfield units (HU); and the intensity of (18)F-FDG uptake, expressed as standardized uptake value (SUV). Receiver operating characteristic curves were drawn to determine the optimal cutoff values of HU and SUV that would best discriminate between benign and malignant masses. RESULTS: When malignant lesions were compared with adenomas, PET data alone using an SUV cutoff of 3.1 yielded a sensitivity, specificity, positive predictive value, and negative predictive value of 98.5%, 92%, 89.3%, 98.9%, respectively. For combined PET/CT data, the sensitivity, specificity, positive predictive value, and negative predictive value were 100%, 98%, 97%, 100%, respectively. Specificity was significantly higher for PET/CT (P < 0.01). Fifty-one of the 175 masses were 1.5 cm or less in diameter. When a cutoff SUV of 3.1 was used for this group, (18)F-FDG PET/CT correctly classified all lesions. CONCLUSION: (18)F-FDG PET/CT improves the performance of (18)F-FDG PET alone in discriminating benign from malignant adrenal lesions in oncology patients.     

Synchronous Bronchioloalveolar and Squamous Cell Lung Cancer With Different 18F-FDG Avidity on PET/CT

ABSTRACT: We report a case of synchronous multiple primary lung cancer diagnosed by F-FDG PET/CT. A 78-year-old man underwent staging FDG PET/CT that demonstrated intense tracer uptake in the primary, and a second lesion with low uptake. Histopathologic evaluation revealed synchronous squamous cell and bronchioloalveolar carcinoma, representing 2 distinct primaries. FDG PET/CT may identify and diagnose synchronous multiple primary lung cancer on the basis of different morphologic and metabolic features of distinct tumor entities. Moreover, pulmonary lesions with low FDG avidity may still represent malignant disease, even in the context of biopsy-proven FDG-avid lung cancer.     

Chemokine receptor-4 targeted PET/CT with 68 Ga-Pentixafor in assessment of newly diagnosed multiple myeloma: comparison to 18 F-FDG PET/CT

18F-FDG PET/CT has some limitations in the evaluation of multiple myeloma (MM). Since chemokine receptor-4 is overexpressed in MM, we perform a prospective cohort study to compare the performance of 68Ga-Pentixafor and 18F-FDG PET/CT in newly diagnosed MM. Thirty patients with newly diagnosed MM were recruited. All patients underwent 68Ga-Pentixafor and18F-FDG PET/CT within 1 week after enrollment. A positive PET/CT was defined as the presence of focal PET-positive lesions in bone marrow or diffuse bone marrow patterns (uptake > liver). Bone marrow uptake values in 68Ga-Pentixafor and18F-FDG PET/CT (total bone marrow glycolysis [TBmGFDG], total bone marrow uptake with 68Ga-Pentixafor [TBmUCXCR4], total bone marrow volume [TBmV], SUVmean, and SUVmax) were obtained by drawing total bone marrow volume of interest on PET/CT. The positive rates of the PET/CT scans were statistically compared, and the correlation between quantitative bone marrow uptake values and clinical characteristics, laboratory findings, and staging was analyzed. 68Ga-Pentixafor PET/CT had a higher positive rate than 18F-FDG PET/CT in recruited patients (93.3 vs. 53.3%, p = 0.0005). In quantitative analysis, bone marrow uptake values in 68Ga-Pentixafor (TBmUCXCR4, SUVmax, and SUVmean) were positively correlated with end organ damage, staging, and laboratory biomarkers related to tumor burden including serum β2-microglobulin, serum free light chain, and 24-h urine light chain (p < 0.05). In 18F-FDG PET/CT, only the SUVmean of total bone marrow was positively correlated with serum free light chain and 24-h urine light chain (p < 0.05). 68Ga-Pentixafor PET/CT is promising in assessment of newly diagnosed MM. NCT 03436342     

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。     

Comparison of 18F-DOPA, 18F-FDG and 68Ga-somatostatin analogue PET/CT in patients with recurrent medullary thyroid carcinoma

Purpose

To retrospectively evaluate and compare ¹⁸F-FDG, ¹⁸F-DOPA and ⁶⁸Ga-somatostatin analogues for PET/CT in patients with residual/recurrent medullary thyroid carcinoma (MTC) suspected on the basis of elevated serum calcitonin levels.

Methods

Included in the study were 18 patients with recurrent MTC in whom functional imaging with the three tracers was performed. The PET/CT results were compared on a per-patient basis and on a per-lesion-basis.

Results

At least one focus of abnormal uptake was observed on PET/CT in 13 patients with ¹⁸F-DOPA (72.2% sensitivity), in 6 patients with ⁶⁸Ga-somatostatin analogues (33.3%) and in 3 patients with ¹⁸F-FDG (16.7%) (p?18F-DOPA and ¹⁸F-FDG PET/CT (p?18F-DOPA and ⁶⁸Ga-somatostatin analogue PET/CT (p?=?0.04). Overall, 72 lesions were identified on PET/CT with the three tracers. ¹⁸F-DOPA PET/CT detected 85% of lesions (61 of 72), ⁶⁸Ga-somatostatin analogue PET/CT 20% (14 of 72) and ¹⁸F-FDG PET/CT 28% (20 of 72). There was a statistically significant difference in the number of lymph node, liver and bone lesions detected with the three tracers (p?18F-DOPA PET/CT and ¹⁸F-FDG PET/CT (p?18F-DOPA PET/CT and ⁶⁸Ga-somatostatin analogue PET/CT (p?Conclusion ¹⁸F-DOPA PET/CT seems to be the most useful imaging method for detecting recurrent MTC lesions in patients with elevated serum calcitonin levels, performing better than ¹⁸F-FDG and ⁶⁸Ga-somatostatin analogue PET/CT. ¹⁸F-FDG may complement ¹⁸F-DOPA in patients with an aggressive tumour.     

18F-FDGPET／CT对继发性周围神经恶性病变的诊断价值

目的 总结继发性周围神经恶性病变18F-脱氧葡萄糖（FDG）PET／CT影像特征,探讨18F—FDGPET／CT在继发性周围神经恶性病变中的应用价值。方法回顾性分析经病理检查或长期随访证实的8例周围神经恶性病变患者18F-FDGPET／CT影像学资料,比较继发性周围神经恶性病变与健侧周围神经PET／CT表现的异同,利用SPSS10．0软件对受累的周围神经及健侧对应部位周围神经的最大标准摄取值（SUVmax）行配对t检验。结果8例继发性周围神经恶性病变患者共发现病灶12个,PET示病灶均沿神经束或椎间孔走行,且表现为束条形、根块状或结节状FDG代谢异常增高,SUVmax为6．86±3．87,同机CT病灶表现为沿神经束或神经根管走行之束条形、根块状或结节状软组织密度影,病灶均与周围软组织及邻近脂肪间隙分界不清;健侧对应部位周围神经在18F—FDGPET及同机CT上均未见明确显影,其SUVmax为1．10±0．46;继发性周围神经恶性病变与健侧周围神经SUVmax比较,差异有统计学意义（t=9．231,P〈0．001）。结论18F—FDGPET／CT可以准确反映肿瘤对周围神经的侵犯及转移,显示病灶的大小、形态、分布及肿瘤活性,对继发性周围神经恶性病变的诊断具有重要价值。     

18F-FDG PET/CT in evaluation of radiofrequency ablation of liver metastasis

Image-guided radiofrequency ablation (RFA) is a minimally invasive therapy option in the treatment of primary and secondary hepatic malignancies, which are not suitable for surgery/chemotherapy, and more recently, for tumors with limited hepatic involvement and solitary liver metastasis. Accurate assessment of treatment response after RFA remains a concern. Conventional imaging modalities have limitations of differentiation between residual/recurrence from post-RFA changes. We illustrate images of 3 patients in whom (18)F-FDG PET/CT was used for response assessment and restaging after RFA in liver tumors.     

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.     

喉癌18F-FDG PET/CT显像的临床应用价值

目的探讨18F-脱氧葡萄糖(FDG)PET/CT显像相对于单独的18F-FDG PET显像在喉癌诊断中的临床价值以及评价平均标准化摄取值(SUVmean)在喉癌和喉生理性显像鉴别中的作用。方法疑似喉癌患者23例。男19例,女4例,年龄30～70岁。空腹6H以上,静脉注射7.4MBq/kg 18F-FDG后40min后仰卧位行头颈部或全身扫描。分别评价18F-FDG PET和18F-FDG PET/CT显像对病灶诊断的灵敏度和特异性。19例病理为鳞癌的喉癌患者与15例喉生理性显像患者作为对照,测定显像部位的SUVmean,试用受试者工作曲线特征(Receivrer Operation Characteristic,ROC)及阳性似然比(positive likelihood ratio,+LR)确定SUVmean阈值。结果 23例喉癌患者,108处病灶。18 F-FDGPET显像和18F-FDG PET/CT显像对病灶诊断的灵敏度分别为85.1%(40/47)和89.4%(42/47),差异无统计学意义(P>0.05),特异性分别为和72.1%(44/61)和91.8%(56/61),差异有统计学意义(P<0.05)。19例病理为鳞癌的喉癌患者SUVmean均数为7.3±2.9,15例喉生理性显像SUVmean均数为4.9±1.1,差异有统计学意义(P<0.05)。SU-Vmean阈值选定为6.1,18 F-FDG PET/CT显像喉癌诊断的灵敏性为63.2%,特异性为86.7%。结论 18 F-FDG PET/CT显像明显改善18F-FDG PET显像的特异性。SUVmean阈值选定为6.1,有利于喉癌和喉生理性显像的鉴别。     

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。