Accuracy of 18F-FDG PET/CT in detection and restaging of recurrent ovarian cancer

Purpose

To estimate the accuracy of 18FDG PET/CT in detection of recurrent cancer ovary and to describe the localization of metastases for restaging.

Prospective assessment of 18F-FDG PET/CT in detection of recurrent ovarian cancer

Objective

To assess the use of positron emission tomography (PET)/computed tomography (CT) in patients with suspected ovarian cancer recurrence and describe the distribution of metastasis.

Patients and methods

This study included (39) patients suspected to have recurrent ovarian malignancy. This suspicion was either clinically, radiologically or due to raised CA-125 levels. All patients underwent 18F-FDG PET/CT, surgery was performed within 8 weeks of imaging studies. Surgical and/or histopathological examinations were available in 31 patients, and clinical, radiological and CA 125 serum level follow up in 8 patients.

Results

The overall lesion-based sensitivity, specificity, and accuracy of PET/CT for revealing recurrent ovarian carcinoma were 90%, 98% and 97%, respectively. The patient – based sensitivity, specificity, and accuracy of PET/CT were 97%, 75% and 95%, respectively.

Conclusion

18F-FDG PET/CT is a useful tool for evaluating the recurrence of ovarian cancer after first-line therapy in patients with a high risk of relapse, equivocal radiologic findings, increased or normal levels of serum CA-125. It can more accurately diagnose and localize recurrence, hence decreasing the rate of second look surgery and changing treatment plan.     

PET/CT evaluation of the physiologic accumulation of 18F-FDG within the gallbladder vesicle

The aim of this study was to investigate physiological fluorine 18-labeled fluourodeoxyglucose accumulation in the gallbladder (GB) during clinical positron emission tomography (PET) examinations.

Three patient groups were included. In Group 1, nine patients with higher fluourodeoxyglucose (FDG) accumulation in the GB than in the liver were examined, followed up and finally diagnosed. In Group 2, the correlations between FDG GB accumulation and various parameters in 286 patients were investigated. In Group 3, changes in FDG GB accumulation between early and delayed PET scans were analyzed in 12 patients.

In Group 1, all nine patients who exhibited a high FDG GB accumulation had no evidence of GB disease. In Group 2, FDG GB accumulation was significantly correlated with the injection–scan time interval and inversely correlated with the GB size index. Group 3 showed a significant increase in FDG accumulation in the GB on delayed PET scans, compared with that seen on early scans.

In clinical PET studies, FDG accumulation within the GB is infrequently observed but may be due to FDG excretion into the bile. Recognition of this phenomenon may be important to avoid misdiagnosing physiological GB FDG accumulation as indicating a pathologic status and preventing unnecessary examinations.     

多发性骨髓瘤的18F-FDGPET/CT诊断

目的:多发性骨髓瘤是一种浆细胞恶性增殖性疾病,大约有80％的患者存在骨骼侵犯.本文探讨多发性骨髓瘤的18F-fluorodexoxyglucose(18F-FDG)PET/CT表现特点,提高对多发性骨髓瘤的认识.方法:26例按2001年WHO诊断标准确诊为多发性骨髓瘤的患者,均在治疗前行18F-FDG PET/CT显像.所有患者均依赖骨髓穿刺或活检取得明确病理学诊断.结果:26名患者均出现不同程度的骨质疏松.25例患者出现多发性骨质破坏,占总数的96.2％;其中11例患者出现颅骨破坏,占42.3％;25例出现脊柱骨质破坏,占96.2％;15例出现胸骨骨质破坏,占57.7％;21例出现肋骨骨质破坏,占80.8％;21例出现骨盆骨质破坏,占80.8％.部分骨破坏病灶呈18F-FDG高代谢灶.结论:多发性骨髓瘤的18F-FDG PET/CT表现具有一定特征,结合临床、影像、实验室和病理学检查能提高本病的诊断率.     

Value of Surveillance 18F-FDG PET/CT in Colorectal Cancer: Comparison with Conventional Imaging Studies

Purpose

To assess the value of PET/CT for detecting local or distant recurrence in patients who undergo surgery for colorectal cancer (CRC) and to compare the accuracy of PET/CT to that of conventional imaging studies (CIS).

Methods

Tumor surveillance PET/CT scans done between March 2005 and December 2009 of disease-free patients after surgery with or without adjuvant chemotherapy for CRC were retrospectively studied. CIS (serial enhanced CT from lung base to pelvis and plain chest radiograph) were performed within 1 month of PET/CT. We excluded patients with distant metastasis on initial staging, a known recurrent tumor, and a lack of follow-up imaging. The final diagnosis was based on at least 6 months of follow-up with colonoscopy, biopsy, and serial imaging studies in combination with carcinoembryonic antigen levels.

Results

A total of 262 PET/CT scans of 245 patients were included. Local and distant recurrences were detected in 27 cases (10.3%). On case-based analysis, the overall sensitivity, specificity, and accuracy were 100, 97.0, and 97.3% for PET/CT and 85.1, 97.0, and 95.8% for CIS, respectively. On lesion-based analysis, PET/CT detected more lesions compared to CIS in local recurrence and lung metastasis. PET/CT and CIS detected the same number of lesions in abdominal lymph nodes, hepatic metastasis, and peritoneal carcinomatosis. PET/CT detected two more metachronous tumors than did CIS in the lung and thyroid gland.

Conclusion

PET/CT detected more recurrences in patients who underwent surgery for CRC than did CIS and had the additional advantage of evaluating the entire body during a single scan.     

18F-FDG PET-CT显像在预测肺癌淋巴结分期中的价值

目的:探究18F-FDG PET-CT显像在肺癌患者淋巴结分期中的预测价值。方法:以35例经手术病理证实为肺癌患者的PET-CT资料及临床资料为研究对象。在PET-CT原发灶及纵隔淋巴结各区最浓聚的部位勾画感兴趣区,得出SUVmax.以淋巴结转移进行分组,采用t检验、Wilcoxon rank-sum检验及四格表资料的Fisher确切概率法分析组间淋巴结SUVmax、淋巴结与原发灶SUVmax的比值(SUVratio)及临床特征的差异。用ROC曲线对PET/CT的预测价值进行分析。结果:患者年龄、性别、吸烟史、组织类型与肺门、纵隔淋巴结转移无显著相关(P>0.05)。转移淋巴结的SUVmax较非转移淋巴结显著升高,差异有统计学意义(P<0.05),而淋巴结的SUVratio与淋巴结转移无明显相关(P>0.05)。取淋巴结SUVmax的最佳阈值,假阴性患者中的肺癌原发灶SUVmax偏低,假阳性患者比假阴性患者中的吸烟率高,但不具有显著统计学意义(P>0.05)。结论:淋巴结SUVmax可以为临床判断淋巴结转移提供定量指标。结合患者的临床病理特征判断淋巴结的转移可能从--定程度上减少假阳性率及假阴性率。     

(18)F-FDG PET versus (18)F-FDG PET/CT for adrenal gland lesion characterization: a comparison of diagnostic efficacy in lung cancer patients.

OBJECTIVE: The aim of this study was to assess the diagnostic efficacy of integrated PET/CT using fluorodeoxyglucose (FDG) for the differentiation of benign and metastatic adrenal gland lesions in patients with lung cancer and to compare the diagnostic efficacy with the use of PET alone. MATERIALS AND METHODS: Sixty-one adrenal lesions (size range, 5-104 mm; mean size, 16 mm) were evaluated retrospectively in 42 lung cancer patients. Both PET images alone and integrated PET/CT images were assessed, respectively, at two-month intervals. PET findings were interpreted as positive if the FDG uptake of adrenal lesions was greater than or equal to that of the liver, and the PET/CT findings were interpreted as positive if an adrenal lesion show attenuation > 10 HU and showed increased FDG uptake. Final diagnoses of adrenal gland lesions were made at clinical follow-up (n = 52) or by a biopsy (n = 9) when available. The diagnostic accuracies of PET and PET/CT for the characterization of adrenal lesions were compared using the McNemar test. RESULTS: Thirty-five (57%) of the 61 adrenal lesions were metastatic and the remaining 26 lesions were benign. For the depiction of adrenal gland metastasis, the sensitivity, specificity, and accuracy of PET were 74%, 73%, and 74%, respectively, whereas those of integrated PET/CT were 80%, 89%, and 84%, respectively (p values; 0.5, 0.125, and 0.031, respectively). CONCLUSION: The use of integrated PET/CT is more accurate than the use of PET alone for differentiating benign and metastatic adrenal gland lesions in lung cancer patients.     

18F-FDG PET or PET/CT for detection of metastatic lymph nodes in patients with endometrial cancer: A systematic review and meta-analysis

The present study assessed the diagnostic performances of 18F-FDG PET or PET/CT in detecting pelvic and/or paraaortic lymph node metastasis in patients with endometrial cancer. METHODS: Through a search of MEDLINE (January 1998 to March 2011), an overall weighted average for sensitivity and specificity as well as pooled estimates of positive and negative likelihood ratios were calculated. A summary receiver-operating-characteristics (sROC) curve was constructed and the area under the sROC curve (AUC) was calculated. I-square was calculated to explore heterogeneity. RESULTS: The present study included 243 patients from seven studies. Results indicated a lack of significant heterogeneity for sensitivity and specificity (I(2)<50% and p>0.05). The overall pooled estimates for sensitivity and specificity of FDG-PET or PET/CT scans in the detection of pelvic and/or paraaortic metastasis were 63.0% (95% CI, 48.7-75.7%) and 94.7% (95% CI, 90.4-97.4%), respectively. The positive likelihood ratio was 10.465 (95% CI, 5.646-19.396) and the negative likelihood ratio 0.399 (95% CI, 0.284-0.560). The AUC was 0.9533. The overall diagnostic accuracy (Q* index) was 89.5%. Conclusion The high positive likelihood value confirms the reliability of a positive FDG-PET or PET/CT to detect pelvic and/or paraaortic lymph nodes metastasis in patients with untreated endometrial cancer. FDG-PET or PET/CT may prove beneficial to surgeons when selecting appropriate patients on whom to perform lymphadenectomy.     

Integrated PET/CT in the preoperative staging of lung cancer: A prospective comparison of CT,PET and integrated PET/CT

Purpose

The purpose of this study was to evaluate the role of integrated PET/CT in the staging of lung cancer compared with CT alone or PET alone.

Materials and methods

Thirty-three patients underwent integrated PET/CT for the staging of lung cancer. The tumor, node and metastasis (TNM) stages were assessed with CT, PET and integrated PET–CT and compared with the surgical and pathological staging.

Results

CT correctly evaluated the (T) status in (64%) of the patients, PET in (59%) and PET/CT in (86%). CT correctly evaluated the (N) status in (73%) of the patients, PET in (76%), and PET/CT (88%) with accuracy, sensitivity, specificity, PPV and NPV were 73%, 78%, 71%, 50% and 94% for CT, 76%, 67%, 79%, 55% and 95% for PET and 88%, 89%, 88%, 73% and 100% for PET/CT respectively, and for (M) status were 91%, 86%, 92%, 75% and 96% for CT, 88%, 71%, 92%, 71% and 92% for PET and 97%, 100%, 96%, 88% and 100% for PET/CT respectively. Regarding the overall TNM staging CT correctly staged 24 patients. PET correctly staged 23 cases while PET/CT correctly staged 30 cases. A significant difference in the accuracy of overall tumor staging between PET/CT and CT (P = 0.0412) or PET (P = 0.0233).

Conclusion

The integrated PET/CT is superior to either CT or PET in the staging of lung cancer which has an important impact on selection of the appropriate treatment regimen.     

Brown fat in breast cancer patients: analysis of serial 18F-FDG PET/CT scans

Purpose It has recently been suggested that FDG accumulation in the brown adipose tissue varies as a function of age, sex and outdoor temperature. The aim of this study was to assess changes in FDG uptake in brown fat in patients based on serial PET/CT scans and to compare our results with previous findings. Methods Early response to neoadjuvant chemotherapy in 33 female breast cancer patients was assessed by FDG PET. Five PET/CT scans were performed for each patient. PET/CT images were analysed retrospectively. PET scans were considered positive when diffuse, symmetrical, abnormal “USA” (uptake in supraclavicular area) fat was detected. Results A total of 163 PET images were analysed. Seventy-four PET scans (45%) revealed abnormal FDG uptake in the supraclavicular area. These foci were present on uncorrected and attenuation-corrected images. FDG uptake was identical on all five scans in only five patients. No significant relationship was found between abnormal FDG uptake and outdoor temperature, age or time interval between chemotherapy and PET. Abnormal FDG uptake in the neck seemed to predominantly occur in patients with a low body mass index (p<0.05). Most significant changes in the PET/CT scan results were observed during chemotherapy with docetaxel (p<0.05). When observed, bilateral uptake in the neck was more intense than background uptake (p<0.00001). Conclusion This study shows that FDG uptake in the neck varies as a function of time, that it is unrelated to age or outdoor temperature, and that bilateral uptake is generally intense.     

The role of 18F-FDG PET/CT in evaluation of early response to neoadjuvant chemotherapy in patients with locally advanced breast cancer

We evaluated the role of 18F-FDG PET/CT for the assessment of response after two cycles of neo-adjuvant chemotherapy (NACT) for breast cancer. Twenty-three women with locally advanced breast cancer were included in this study. Early response to NACT was evaluated after two cycles using clinical examination, CT, and 18F-FDG PET/CT. Final histopathology following surgery after six cycles of NACT served as reference. Baseline PET/CT demonstrated a total of 26 lesions in 23 patients. The size of the primary tumor ranged from 1.90 cm to 11.60 cm, and the maximum value of the standardized uptake value of FDG (SUVmax) ranged from 3.6 to 38.6 (mean, 11.7). Post-chemotherapy PET/CT examinations were done after two cycles of NACT. The size of the primary tumor on follow-up PET/CT examinations ranged from 0.0 cm to 7.6 cm, and SUVmax ranged from 0.0 to 12.0 (mean, 3.96). On clinical, CT, and PET/CT examinations, 50% reduction in the parameters was taken as the cutoff value to differentiate between responders and non-responders. Post-NACT PET/CT demonstrated that 16 patients were responders and 7 non-responders. Among 16 responders on PET/CT scan, 14 were true positive and 2 were false positive when compared with histopathology. Among seven non-responder patients, six were true negative, and one was false negative. The sensitivity, specificity, and accuracy of PET/CT in detecting responders were 93%, 75%, and 87%, respectively. In conclusion, 18F-FDG PET/CT can differentiate responders from non-responders with high accuracy after two cycles of NACT in patients with LABC.     

18F-FDOPA与18F-FDG PET/CT诊断脑肿瘤的系统评价

目的 系统评价18F-FDOPA与18F-FDG PET/CT显像在脑肿瘤诊断中的临床价值.方法 采用Meta分析与直接比较方法.使用计算机检索中国期刊全文数据库、中文科技期刊数据库、万方数据库、中国生物医学文献数据库、PubMed、Embase、The Cochrane Library,从建库至2016年10月,搜索直接比较18F-FDOPA与18F-FDG PET/CT诊断脑肿瘤的诊断性试验.用Meta-Disc 1.4软件进行分析,计算两种不同显像剂的合并敏感度(sensitivity,SEN)、合并特异度(specificity,SPE)、合并阳性似然比(positive likelihood ratio,+LR)、合并阴性似然比(negative likelihood ratio,-LR)、诊断优势比(diagnostic odds ratio,DOR),并绘制综合受试者工作特征曲线计算曲线下面积(area under curve,AUC)与Q*值.结果 最终共纳入4篇文章,Meta 分析结果显示,18F-FDOPA PET/CT对脑肿瘤诊断的合并SEN为0.97(95％ CI =0.90 ～ 1.00),SPE为0.67(95％ CI =0.45 ～0.84),+LR为2.31 (95％ CI=1.40 ～3.81),-LR为0.07 (95％ CI =0.02～ 0.24),DOR为39.72(95％ CI=8.94～176.48),AUC为0.9725,Q*为0.9239.18F-FDG PET/CT对脑肿瘤诊断的合并SEN为0.51(95％CI=0.39～0.63),SPE为0.75(95％ CI=0.53 ～0.90,+LR为l.59(95％ CI=0.70 ～ 3.61),-LR为0.63(95％ CI =0.47 ～0.86),DOR为2.55(95％ CI =0.82 ～7.92),AUC为0.5848,Q*为0.5638.结论 18F-FDOPA PET/CT显像诊断脑肿瘤的敏感性比18F-FDG高,对脑肿瘤具有良好的诊断价值,可作为脑肿瘤诊断的方法之一.     

Evaluation of gross tumor size using CT, 18F-FDG PET, integrated 18F-FDG PET/CT and pathological analysis in non-small cell lung cancer

Purpose

The correlation of gross tumor sizes between combined ¹⁸F-FDG PET/CT images and macroscopic surgical samples has not yet been studied in detail. In the present study, we compared CT, ¹⁸F-FDG PET and combined ¹⁸F-FDG PET/CT for the delineation of gross tumor volume (GTV) and validated the results through examination of the macroscopic surgical specimen.

Methods

Fifty-two operable non-small cell lung cancer (NSCLC) patients had integrated ¹⁸F-FDG PET/CT scans preoperatively and pathological examination post-operation. Four separate maximal tumor sizes at X (lateral direction), Y (ventro-dorsal direction) and Z (cranio-caudal direction) axis were measured on ¹⁸F-FDG PET, CT, combined ¹⁸F-FDG PET/CT and surgical specimen, respectively. Linear regression was calculated for each of the three imaging measurements versus pathological measurement.

Results

No significant differences were observed among the tumor sizes measured by three images and pathological method. Compared with pathological measurement, CT size at X, Y, Z axis was larger, whereas combined ¹⁸F-FDG PET/CT and ¹⁸F-FDG PET size were smaller. Combined ¹⁸F-FDG PET/CT size was more similar to the pathological size than that of ¹⁸F-FDG PET or CT. Results of linear regressions showed that integrated ¹⁸F-FDG PET/CT was the most accurate modality in measuring the size of cancer.

Conclusions

¹⁸F-FDG PET/CT correlates more faithfully with pathological findings than ¹⁸F-FDG PET or CT. Integrated ¹⁸F-FDG PET/CT is an effective tool to define the target of GTV in radiotherapy.     

Combined pre-treatment MRI and 18F-FDG PET/CT parameters as prognostic biomarkers in patients with cervical cancer

Objective

To determine the associations of quantitative parameters derived from multiphase contrast-enhanced magnetic resonance imaging (CE-MRI), diffusion-weighted (DW) MRI and 18F-fluorodeoxyglucose (18F-FDG) positron-emission tomography/computed tomography (PET/CT) with clinico-histopathological prognostic factors, disease-free survival (DFS) and overall survival (OS) in patients with cervical cancer.

Methods and materials

Our institutional review board approved this retrospective study of 49 patients (median age, 45 years) with histopathologically proven IB-IVB International Federation of Gynecology and Obstetrics (FIGO) cervical cancer who underwent pre-treatment pelvic MRI and whole-body 18F-FDG PET/CT between February 2009 and May 2012. Maximum diameter (_maxTD), percentage enhancement (PE) and mean apparent diffusion coefficient (ADC_mean) of the primary tumor were measured on MRI. Maximum standardized uptake value (SUV_max), metabolic tumor volume (MTV), total lesion glycolysis (TLG) were measured on 18F-FDG PET/CT. Correlations between imaging metrics and clinico-histopathological parameters including revised 2009 FIGO stage, tumor histology, grade and lymph node (LN) metastasis at diagnosis were evaluated using the Wilcoxon rank sum test. Cox modeling was used to determine associations with DFS and OS.

Results

Median follow-up was 17 months. 41 patients (83.6%) were alive. 8 patients (16.3%) died of disease. Progression/recurrence occurred in 17 patients (34.6%). Significant differences were observed in ADC_mean, SUV_max, MTV and TLG according to FIGO stage (p < 0.001–0.025). There were significant correlations between ADC_mean, MTV, TLG and LN metastasis (p = 0.017–0.032). SUV_max was not associated with LN metastasis. FIGO stage (p = 0.017/0.033), LN metastases (p = 0.001/0.020), ADC_mean (p = 0.007/0.020) and MTV (p = 0.014/0.026) were adverse predictors of both DFS/OS. _maxTD (p = 0.005) and TLG (p = 0.024) were adverse predictors of DFS. PE and SUV_max did not correlate with DFS or OS (p = 0.18–0.72).

Conclusions

Quantitative parameters derived from pre-treatment DW-MRI (ADC_mean) and from 18F-FDG PET/CT (MTV and TLG) were associated with high-risk features and may serve as prognostic biomarkers of survival in patients with cervical cancer.     

The diagnostic efficacy of whole body 18F-FDG PET CT in detection of unexpected second primary malignancy in cancer patients

Purpose

to assess the efficacy of FDG PET/CT in detecting unexpected additional primary malignant neoplasms in patients being evaluated by PET/CT for known malignancies compared to conventional staging work-up (CSW).

Prognostic significance of novel F-FDG PET/CT defined tumour variables in patients with oesophageal cancer

Purpose

¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) combined with computed tomography (PET/CT) is now established as a routine staging investigation of oesophageal cancer (OC). The aim of the study was to determine the prognostic significance of PET/CT defined tumour variables including maximum standardised uptake value (SUVmax), tumour length (TL), metastatic length of disease (MLoD), metabolic tumour volume (MTV), total lesion glycolysis (TLG) and total local nodal metastasis count (PET/CT LNMC).

Materials and methods

103 pre-treatment OC patients (76 adenocarcinoma, 25 squamous cell carcinoma, 1 poorly differentiated and 1 neuroendocrine tumour) were staged using PET/CT. The prognostic value of the measured tumour variables were tested using log-rank analysis of the Kaplan–Meier method and Cox's proportional hazards method. Primary outcome measure was survival from diagnosis.

Results

Univariate analysis showed all variables to have strong statistical significance in relation to survival. Multivariate analysis demonstrated three variables that were significantly and independently associated with survival; MLoD (HR 1.035, 95% CI 1.008–1.064, p = 0.011), TLG (HR 1.002, 95% CI 1.000–1.003, p = 0.018) and PET/CT LNMC (HR 0.048–0.633, 95% CI 0.005–2.725, p = 0.015).

Conclusion

MLoD, TLG, and PET/CT LNMC are important prognostic indicators in OC. This is the first study to demonstrate an independent statistical association between TLG, MLoD and survival by multivariable analysis, and highlights the value of staging OC patients with PET/CT using functional tumour variables.     

^18F-FDG PET／CT在鼻咽癌临床分期和疗效监测中的应用

目的探讨^18F-FDGPET／CT显像在鼻咽癌首次分期、再分期及疗效监测中的临床应用价值。方法通过分析86例鼻咽癌患者^18F-FDGPET／CT扫描结果,结合其他临床资料和随访结果,计算^18F-FDGPET／CT显像的准确性、特异性、灵敏度、阳性预测值与阴性预测值,并与CT、MRI进行比较。结果^18F-FDGPET／CT与CT、MRI诊断鼻咽癌的准确率、敏感性、特异性、阳性预测值与阴性预测值的差异均有统计学意义（P〈0．05）。依据^18F-FDGPET／CT结果,改变了4例首次分期、14例再分期的临床诊断和22例患者的治疗方案。结论与CT、MRI相比,^18F-FDGPET／CT显像对鼻咽癌的临床分期及疗效监测具有更重要价值。     

胆管癌的18F-FDG PET/CT诊断价值

目的 总结胆管癌18F-FDG PET/CT显像表现,提高胆管癌的诊断准确性.方法 回顾经病理或临床综合手段证实的53例胆道疾病的18F-FDG PET/CT表现,分析PET/CT诊断胆管癌的敏感性、特异性和准确性.结果 肝内胆管癌14例、近段胆管癌18例、中远段胆总管癌15例、胆管炎性病变或伴结石6例.肝内转移9例,腹腔及腹膜后淋巴结转移15例,椎体等远处转移3例.PET/CT诊断胆管癌的敏感性为95.7％、特异性为83.3％、准确性为94.3％.结论 18F-FDG PET/CT在胆管癌的诊断与鉴别诊断、分期、检测疗效及预后等具有独特的应用价值.     

Non-enhanced CT versus contrast-enhanced CT in integrated PET/CT studies for nodal staging of rectal cancer

Purpose The purpose of the present study was to determine the diagnostic accuracy of non-enhanced CT and contrast-enhanced CT in integrated PET/CT studies for preoperative nodal staging of rectal cancer. Methods Retrospective analysis was performed in 53 patients with pathologically proven rectal cancer who had been referred for preoperative staging. All patients underwent integrated PET/CT consisting of non-enhanced and contrast-enhanced CT followed by whole-body fluorine-18-fluorodeoxyglucose ([¹⁸F]FDG) PET. Both non-enhanced and contrast-enhanced PET/CT images were evaluated separately by two observers in consensus. The reference standard was histopathologic results. For nodal staging of rectal cancer, we compared diagnostic accuracy on a per-patient basis between the two modalities. Results Nodal staging was correctly determined with non-enhanced studies in 37 patients (70%) and with contrast-enhanced studies in 42 patients (79%). On a per-patient basis, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of regional lymph node staging were 85%, 68%, 83%, 72%, and 79%, respectively, with contrast-enhanced studies, and 85%, 42%, 73%, 62%, and 70%, respectively, with non-enhanced studies. The difference in the accuracy of nodal staging between the two modalities was not significant (p = 0.063). Compared with non-enhanced studies, contrast-enhanced studies determined more correctly the status of pararectal lymph nodes (p = 0.002), internal iliac lymph nodes (p = 0.004), and obturator lymph nodes (p < 0.0001). Conclusion Contrast-enhanced PET/CT is superior to non-enhanced PET/CT for precise definition of regional nodal status in rectal cancer.     

Differentiating adrenal adenomas from nonadenomas using (18)F-FDG PET/CT: quantitative and qualitative evaluation

RATIONALE AND OBJECTIVES: We sought to assess the ability of (18)F-fluoro-2-deoxy-d-glucose (FDG) PET/CT to distinguish adrenal adenomas from nonadenomas in patients with suspected malignancy. METHODS: Fifty-nine adrenal masses were evaluated with coregistered (18)F-FDG PET (PET/CT). Two reviewers independently graded uptake of (18)F-FDG by visual inspection of the adrenal mass in comparison to liver and background. CT attenuation value of the adrenal mass and the standardized uptake value (SUV) of the mass, liver, background, and primary neoplasm (when visible) were measured. Mean SUVs of the adrenal mass, liver, and background and ratios of the SUVs were calculated. RESULTS: Of 47 adenomas, 43 measured <10 HU on unenhanced CT. Of 12, 12 nonadenomas measured >10 HU on unenhanced CT. Using qualitative assessment of FDG activity in the adrenal mass compared with liver, adenomas were less than, equal to, or more active than the liver in 51%, 38%, and 10%, respectively. Nonadenomas were less than, equal to, or more active than liver in 0%, 25%, and 75%, respectively. The mean SUV of adenomas (4.2) was significantly lower (P = .002) than that of their primary malignancies (9.2) but not that of liver (4.3). The mean SUV of adenomas was not significantly different than that of nonadenomas (5.2), but the mean adrenal/liver ratio (1.0) for the adenomas was significantly lower (P = .006) than that of the nonadenomas (2.1). CONCLUSION: Adrenal adenomas were better differentiated from nonadenomas using unenhanced CT measurements in combination with ratios of the SUVs. Adrenal mass activity, which was visibly less than liver, was more specific for adenoma, whereas adrenal mass activity visibly greater than liver was more specific for malignancy.