Characteristics of Metastatic Mediastinal Lymph Nodes of Non-Small Cell Lung Cancer on Preoperative F-18 FDG PET/CT

Purpose

The aim of this study was to evaluate the characteristics of PET and CT features of mediastinal metastatic lymph nodes on F-18 FDG PET/CT and to determine the diagnostic criteria in nodal staging of non-small cell lung cancer.

Methods

One hundred four non-small cell lung cancer patients who had preoperative F-18 FDG PET/CT were included. For quantitative analysis, the maximum SUV of the primary tumor, maximum SUV of the lymph nodes (SUVmax), size of the lymph nodes, and average Hounsfield units (aHUs) and maximum Hounsfield units (mHUs) of the lymph nodes were measured. The SUVmax, SUV ratio of the lymph node to blood pool (LN SUV/blood pool SUV), SUV ratio of the lymph node to primary tumor (LN SUV/primary tumor SUV), size, aHU, and mHU were compared between the benign and malignant lymph nodes.

Results

Among 372 dissected lymph node stations that were pathologically diagnosed after surgery, 49 node stations were malignant and 323 node stations benign. SUVmax, LN SUV/blood pool SUV, and size were significantly different between the malignant and benign lymph node stations (P < 0.0001). However, there was no significant difference in LN SUV/primary tumor SUV (P = 0.18), mHU (P = 0.42), and aHU (P = 0.98). Using receiver-operating characteristic curve analyses, there was no significant difference among these three variables (SUVmax, LN SUV/blood pool SUV, and size). The optimal cutoff values were 2.9 for SUVmax, 1.4 for LN SUV/blood pool SUV, and 5 mm for size. When the cutoff value of SUVmax ≥2.9 and size ≥5 mm were used in combination, the positive predictive value was 44.2 %, and the negative predictive value was 90.9 %. When we evaluated the results based on the histology of the primary tumor, the negative predictive value was 92.3 % in adenocarcinoma (cutoff values of SUVmax ≥2.3 and size ≥5 mm) and 97.2 % in squamous cell carcinoma (cutoff values of SUVmax ≥3.6 and size ≥8 mm), separately.

Conclusions

In the lymph node staging of non-small cell lung cancer, SUVmax, LN SUV/blood pool SUV, and size show statistically significant differences between malignant and benign lymph nodes. These variables can be used to differentiate malignant from benign lymph nodes. The combination of the SUVmax and size of lymph node might have a good negative predictive value.     

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。     

Benign Schwannoma Mimicking Metastatic Lesion on F-18 FDG PET/CT in Differentiated Thyroid Cancer

We report a case of benign schwannoma mimicking metastatic carcinoma. A 55-year-old female with papillary thyroid carcinoma underwent total thyroidectomy. F-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) demonstrated a focal hypermetabolic lesion with maximum standardized uptake value (SUVmax) 5.3 at the right chest wall. Conventional chest CT demonstrated a 5.4 cm ovoid mass lesion between the intercostal muscles and liver. Pathology revealed a schwannoma by tumor excision. This case demonstrates that benign schwannoma may demonstrate FDG uptake mimicking metastatic carcinoma.     

The Diagnostic Value of 18F-FDG PET/CT Imaging in Preoperative Staging of Colorectal Cancer

目的 探讨18F-FDG PET/CT在结直肠癌术前TNM分期中的应用价值.资料与方法 33例疑结直肠肿瘤患者均于手术治疗前行全身PET/CT扫描,将患者PET/CT检查结果与手术病理学检查结果进行比较分析.结果 PET/CT诊断结直肠癌原发灶的敏感性、准确性分别为100％和96.97％;PET/CT对术前结直肠癌侵犯局部浆膜、淋巴结转移、远处转移及TNM分期的准确性分别为75.00％、78.12％、96.87％和71.87％,经Kappa一致性检验,PET/CT 上述诊断结果与手术病理学检查结果具有较好的一致性(0.429,0.559,0.920,0.619,P均＜0.05).结论 结直肠癌18F-FDG PET/CT术前检查,是结盲肠癌的术前临床分期中有效的影像学评价手段.     

Follicular Lymphoma mimicking Metastatic Nodes on the F-18 FDG PET/CT and MRI for Staging of Endometrial Cancer

A 53-year-old woman was diagnosed with endometrial carcinoma by vaginal bleeding. F-18 fluorodeoxy glucose positron emission tomography PET/CT (F-18 FDG PET/CT) scan for staging showed intense focal FDG uptake in the endometrium suggesting endometrial malignancy. PET/CT showed multiple node uptakes in the pericaval region, paraaortic region, common iliac, and both internal iliac and external iliac regions suggesting multiple pelvic and retroperitoneal node metastases. MRI showed multiple metastatic lymphadenopathy in the retroperitoneum and pelvic cavity. Pathologic diagnosis performed with dissected pelvic and paraaortic nodes was confirmed as a follicular malignant lymphoma positive for B–cell lymphoma-2(Bcl-2) stain, not the metastatic node of primary endometrioid carcinoma.     

F-18 FDG PET/CT in relapsing polychondritis

We report a case of relapsing polychondritis for which fluorodeoxyglucose (FDG) positron-emission tomography/computed tomography (PET/CT) showed increased FDG accumulation in all rib cartilages, as well as in the larynx, trachea, and major bronchi. Contrast-enhanced CT during PET/CT showed smooth tracheal and bronchial wall thickening with calcification and airway narrowing. After steroid therapy, clinical symptoms and laboratory data were improved and cartilaginous FDG accumulation had completely disappeared. FDG PET/CT is considered to be a powerful radiological tool to assess the disease activity of relapsing polychondritis.     

A unique presentation of appendicitis: F-18 FDG PET/CT

A 27-year-old white man was diagnosed with a testicular, metastatic germ cell tumor. The patient was evaluated with F-18 fluorodeoxyglucose positron emission tomography and coregistered computed tomography (FDG PET/CT) as well as a contrast-enhanced CT (CECT) of the abdomen and pelvis. Serologic tests were performed. At laparoscopic appendectomy, findings were consistent with acute suppurative appendicitis. This case exemplifies the relevance of incidental findings detected on FDG PET/CT.     

Retroperitoneal Pleomorphic Liposarcoma Mimicking Adrenal Cancer in F-18 FDG PET/CT

Liposarcoma is the second most common type of soft tissue sarcoma, but pleomorphic liposarcoma is the least common subtype. We present the case of a 42-year-old man who had experienced intermittent left flank pain for a month. A large soft-tissue mass was detected by ultrasonography in a local clinic, and he was referred for further evaluation. Positron emission tomography/computed tomography (PET/CT) with F-18 fluoro-2-deoxy-D-glucose (F-18 FDG) showed intense uptake in the retroperitoneal mass, which mimicked an adrenal cancer. The patient underwent left radical nephroadrenalectomy, and the tumor was revealed to be a pleomorphic liposarcoma upon pathological examination. When there is a large retroperitoneal mass with intense F-18 FDG activity, the possibility of a pleomorphic liposarcoma should be considered.     

Evaluation of Adrenal Masses in Lung Cancer Patients Using F-18 FDG PET/CT

Purpose

The aim of this study was to assess the diagnostic efficacy of PET/CT using various parameters for the characterization of adrenal nodules in lung cancer patients.

Methods

Sixty-one adrenal nodules in 51 lung cancer patients were evaluated. The final diagnosis was based on histology (n = 2) or imaging follow-up (n = 59, range of follow-up: 7–57 months, median 27 months). Each adrenal nodule was analyzed using four parameters of PET/CT: the maximum standardized uptake value (SUV_max), the adrenal nodule/liver ratio of the SUV (SUV ratio), Hounsfield units (HU) and size. The optimal cutoff of each parameter for the identification of metastatic nodule was determined by ROC analysis and then the diagnostic efficacy was compared among the parameters.

Results

Of the 61 adrenal nodules, 45 (73%) were considered metastasis. The optimal cutoff values of the parameters were SUV_max >2.7, SUV ratio >1.3, HU >18 and size >20 mm, respectively. The sensitivity, specificity and accuracy by SUV_max >2.7 were 88.9%, 87.5% and 88.5%, and those by SUV ratio >1.3 were 84.4%, 100% and 88.5%, respectively. The combination of SUV ratio >1.3 and HU >18 had sensitivity of 97.7%, specificity of 81.2% and accuracy of 93.4% to predict adrenal metastasis in patients with lung cancer.

Conclusion

SUV ratio from F-18 FDG PET/CT could identify the adrenal metastasis in lung cancer patients. The combination of SUV ratio and HU can improve the accuracy of differentiating benign and metastatic adrenal lesions in lung cancer patients.     

Pretreatment F-18 FDG PET/CT Parameters to Evaluate Progression-Free Survival in Gastric Cancer

Purpose

We performed this study to evaluate the predictive value of pretreatment F-18 FDG PET/CT for progression-free survival (PFS) in patients with gastric cancer.

Methods

Of 321 patients with a diagnosis of gastric cancer, we retrospectively enrolled 97 patients (men:women = 61:36, age 59.8 ± 13.2 years), who underwent pretreatment F-18 fluoro-2-deoxyglucose positron emission tomography/computed tomography (F-18 FDG PET/CT) from January 2009 to December 2009. Maximum standardized uptake value (SUVmax) was measured for each case with detectable primary lesions. In the remaining non-detectable cases, SUVmax was measured from the corresponding site seen on gastroduodenoscopy for analysis. In subgroup analysis, metabolic tumor volume (MTV) was measured in 50 patients with clearly distinguishable primary lesions. SUVmax, stage, depth of tumor invasion and presence of lymph node metastasis were analyzed in terms of PFS. Receiver operating characteristic (ROC) curves were used to find optimal cutoff values of SUVmax and MTV for disease progression. The relationship between SUVmax, MTV and PFS was analyzed using the Kaplan-Meier with log-rank test and Cox’s proportional hazard regression methods.

Results

Of 97 patients, 15 (15.5 %) had disease progression. The mean follow-up duration was 29.6 ± 10.2 months. The mean PFS of low SUVmax group (≤5.74) was significantly longer than that of the high SUVmax group (>5.74) (30.9 ± 8.0 vs 24.3 ± 13.6 months, p = 0.008). In univariate analysis, stage (I vs II, III, IV), depth of tumor invasion (T1 vs T2, T3, T4), presence of lymph node metastasis and SUVmax (>5.74 vs ≤5.74) were significantly associated with recurrence. In multivariate analysis, high SUVmax (>5.74) was the only poor prognostic factor for PFS (p = 0.002, HR 11.03, 95 % CI 2.48–49.05). Subgroup multivariate analysis revealed that high MTV (>16.42) was the only poor prognostic factor for PFS (p = 0.034, HR 3.59, 95 % CI 1.10–11.71).

Conclusion

In gastric cancer, SUVmax measured by pretreatment F-18 FDG PET/CT has a significant predictive value for PFS. In addition, if MTV is measurable, high MTV is an independent factor for disease progression.