Differentiation of radiographically indeterminate solitary pulmonary nodules with

BACKGROUND: The purpose of this preliminary study was to evaluate the efficacy of positron emission tomography (PET) with [18F]fluoro-2-deoxyglucose (FDG) for differentiating benign from malignant solitary pulmonary nodules. METHODS: Twenty-six patients (12 females, 14 males, age 27-79 years) with radiographically indeterminate solitary pulmonary nodules underwent FDG-PET and the findings were compared with the results of pathological examination of biopsy samples. FDG activity in the lesion was expressed as the ratio of lesion-to-background counts (L/B ratio) for semiquantitative analysis. RESULTS: The mean L/B ratio of malignant lesions (8.81+/-3.71, n = 20) was not significantly higher than that of benign lesions (4.71+/-3.00, n = 6) (p = 1.00). Using a cut-off L/B ratio of 5.0 for malignancy, FDG-PET correctly detected 19 true positive and three true negative cases, but failed to detect three false positive (two abscesses and one cryptococcus) cases and one false negative (adenocarcinoma) case. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value were 95, 50, 86, 75 and 85%, respectively. CONCLUSIONS: FDG-PET is a sensitive modality for detecting malignancy, but is not specific enough. Benign lung lesion with active inflammation could demonstrate high FDG uptake, making it difficult to differentiate from malignancy. In the future, we will increase the case numbers to evaluate further the utility of FDG-PET for differentiating radiographically indeterminate solitary pulmonary nodules.     

Differential Diagnoses of Solitary Pulmonary Nodules in Patients with an Extrathoracic Malignant Tumor:CT and Parthologic Correlations

OBJECTIVE To determine the possibility of definitive diagnosis for solitary pulmonary nodules in patients with a primary extrathoracic malignant neoplasm (ETM-SPN), and to further evaluate the value of CT for differential diagnosis in ETM-SPN by a multivariate retrospective study.METHODS Eighty-three patients with pathologically and clinically proven ETM-SPN with a diameter smaller than 3 cm were included in this study.The pathological characteristics of the SPN were correlated with those of the extrathoracic neoplasm, with the patient's age, gender, smoking history, disease-free time interval between the diagnosis of the extrathoracic malignancy and that of the lung lesion. In all 83 cases, CT scans were reviewed to confirm the solitary nature, size, and nodular morphology of the lung lesion.RESULTS Of all 83 cases, the mean age was (57.43±15.34) years. There were 51 males and 32 females, with the ratio of 1.59:1. The lesions included solitary metastasis in 43 cases, pulmonary malignant lesions in 33, and benign lesions in seven. Between the primary lung cancers and solitary metastasis groups, there was no significant difference in the gender ratio (1.20:1 vs 2.31:1, x2=0.0209, P>0.05), but there was a significant difference between the mean age (62.48±11.96 years vs 54.10±16.49 years, t=3.34, P<0.05). in the primary lung cancer and metastasis patient group, the percentage of patients who had a smoking history were 39.3 %(11/17) and 35.9 %(14/39), respectively. Patients with a primary lung cancer had no significant higher frequency of smoking history than did those with a metastatic lesion (x2=0.640, P>0.05). Of 81cases who were followed-up, the mean time of the disease-free interval between extrapulmonary malignancy diagnosis and pulmonary lesion differentiation was 39.73± 6.29 months (range 0～300 months, median 20.00 months), whereas those in the primary lung cancer group and metastatic group were 65.62 ±13.45 months and 22.83 ±4.19 months respectively. This difference was significant between the two groups (Wilcoxon rank sum test, U=2.796, P<0.01). Of all 83 cases, there were ten extrapulmonary squamous carcinomas and 58 adenocarcinomas with ratio of primary lung cancer and solitary metastasis of the tumors were 7:3 and 24:34, respectively (x2 =1.781, P >0.05), without showing a statistically significant relevance between the pathologic patterns of extrapulmonary malignancy and characteristics of the lung nodules. Of all the 83 cases, the mean diameters were (2.77±1.25) cm, whereas the diameters of 33 cases of primary lung cancer and 43 cases of a solitary metastatic lesion were (2.86±1.18) cm and (2.62±1.31)cm, respectively. There was no association between the two groups (t=1.29, P>0.05). There was a statistically significant association between primary lung cancer and the metastatic group with spiculate and smooth edges of the lung lesion (x2=8.562, P<0.01; x2=15.220, P<0.001).The study showed that a lung nodule with a spiculatedmargin correlated with a primary lung carcinoma,whereas those nodules with a smooth edge may more frequently show as a metastastic pulmonary lesion. CT-pathologic correlative analyses of hilar and mediastinal adenopathy were reviewed in 37 patients who underwent Iobectomy and thoracotomy. There was no statistical significant difference between the primary lung cancer group and the metastatic group (x2=2.801,P>0.05).CONCLUSION The likelihood of a primary lung cancer versus a metastasis of ETM-SPN smaller than 3 cm mainly depends on the patient's age, free interval between the two tumors and CT morphological characteristics of the lung lesion. This study showed there was no significant relevancy to factors such as gender, smoking history, pathological patterns of the extrapulmonary neoplasm or whether there has hilar or mediastinal adenopathy.     

EGFR gene copy number in adenocarcinoma of the lung by FISH analysis: investigation of significantly related factors on CT, FDG-PET, and histopathology

It has been suggested that a high EGFR gene copy number may be an indicator of good response to EGFR tyrosine kinase inhibitor therapy and a marker of poor prognosis in NSCLC. However, imaging features related to EGFR gene copy number status in adenocarcinoma are still unknown. We therefore retrospectively analyzed CT, FDG-PET, and histopathologic slides of surgical resected lung adenocarcinoma in 132 patients. Tumor characteristics on preoperative chest-CT, such as, GGO proportions, tumor diameters, and cavitation; FDG-PET SUV(max); and histopathologically determined differentiation degrees and tumor subtypes were evaluated. EGFR gene copy number status was categorized as FISH-positive or -negative. FISH-positivity was found in 53 patients (40.2%) and was significantly more frequent in tumors with a SUV(max)>7.0 (P=0.007). Furthermore, FISH-negativity was found to be more frequent in tumors with a GGO>50% (P=0.023) and diameter <15.5mm (P=0.006) on CT, or a well-differentiated histopathology (P=0.002). Moreover, the frequency of FISH-positivity increased as SUV(max) increased (P=0.0008) and as the proportion of GGO decreased (P=0.01). SUV(max)>7.0 was an independent predictor of FISH-positive results (odds ratio, 3.941; 95% CI, 1.691-9.182; P=0.01). In conclusion, a high SUV(max) on FDG-PET was significantly related to FISH-positive results. A high proportion of GGO, small tumor diameter on CT, and a well-differentiated histopathology were more frequent in FISH-negative adenocarcinomas.     

(F-18) fluorodeoxyglucose positron emission tomography as a predictor of pathologic grade and other prognostic variables in bone and soft tissue sarcoma.

Positron emission tomography (PET) can be used to measure tumor metabolism in sarcomas by measuring the standard uptake value (SUV) of (F-18) fluorodeoxyglucose (FDG). FDG-PET SUV has been shown to correlate with histological grade. We compared FDG-PET SUV in 89 bone and soft tissue sarcomas with histopathological features, including tumor grade, as well as with markers of cell proliferation and cell cycle regulatory gene expression that may be prognostically or therapeutically important. All patients had undergone PET before biopsy. Features evaluated included grade (National Cancer Institute for soft tissue or Mayo Clinic for bone), cellularity, and the number of mitoses per 10 400x fields. Deparaffinized, formalin-fixed sections were immunostained with antibodies to Ki-67 (MIB-1), p53 (DO7), p21WAF1 (EA10), and mdm-2 (1B10). For Ki-67, results were estimated as a percentage of positive cells. For p53 and mdm-2, only cases with >20% positive cells were considered to be overexpressing these proteins. For p21WAF1, only cases with <10% positive cells were considered to have lost normal p21WAF1 expression. Tumor S-phase percentage and ploidy were determined by flow cytometry. FDG-PET SUV was associated with histopathological grade, cellularity, mitotic activity, MIB labeling index, and p53 overexpression. No association was seen with p21WAF1, mdm-2, S-phase fraction, or ploidy. Tumor metabolism data acquired by FDG-PET may help ensure accurate grading and prognostication in sarcoma by guiding biopsy toward the most biologically significant regions of large masses. Further follow-up will be necessary to determine whether FDG-PET provides independent prognostic information.     

Vinorelbine plus cisplatin versus cisplatin plus vindesine and mitomycin C in stage IIIB-IV non-small cell lung carcinoma: a prospective randomized study

This study was performed to investigate the utility of FDG-PET for: (1) initial staging, and (2) restaging of the primary and mediastinal nodal lesions 2 weeks after the completion of preoperative chemoradiotherapy in patients with stage III non-small cell lung cancer (NSCLC). Twenty-six patients with histologically confirmed stage III NSCLC were accrued to this study from April 1993 to July 1998. They included 21 with stage IIIA (N2) NSCLC who were enrolled into an institutional phase II study, and 5 patients with a highly selected subset of stage IIIB disease characterized by the presence of microscopic metastatic disease in contralateral mediastinal lymph nodes who were also treated with preoperative chemoradiotherapy; N3 lesions (n=3) and minimal T4 lesions. Demographic characteristics included median age 62 years (a range from 47 to 73) and gender ratio of male 15 to female 11. Histologic types of tumor consisted of squamous cell carcinoma 6, adenocarcinoma 11, large cell carcinoma 5, and non-small cell carcinoma 4. All patients had FDG-PET imaging of the chest before the initiation and 2 weeks after completion of preoperative therapy. The FDG-PET images were evaluated qualitatively for uptake at the primary tumor sites and mediastinal lymph nodes. Standard uptake values (SUVs) were also calculated for the primary tumors and all PET findings were correlated with surgical histopathologic data. Preoperative chemoradiotherapy resulted in complete pathologic response in 8 of 26 primary lesions. By qualitative analysis, 96% of these tumors showed level 3 or 4 uptake before preoperative chemoradiotherapy. After chemoradiotherapy, 57% (15/26) of patients showed at least a one level decrease in uptake, and the sensitivity and specificity of FDG-PET for differentiating residual tumor from pathologic complete response were 67% (12/18) and 63% (5/8). Mean SUV was 14.87+/-7.11 at baseline and decreased to 5.72+/-3.35 after chemoradiotherapy (n=21, P<0.00001). When a value of 3.0 was used as the SUV cut-off, sensitivity and specificity were 88 and 67%, respectively. The mean values of visual intensity were 3.87+/-0.35 and 3.8+/-0.51 for patients who achieved pathologic complete response (n=8) and for those who showed residual cancer after the preoperative therapy (n=18), respectively. The mean SUVs were 16.97+/-8.52 and 14.03+/-6.61 for patients who achieved pathologic complete response (n=6) and for those who showed residual cancer (n=15) after the preoperative therapy, respectively. Therefore, the degree of FDG uptake before preoperative chemoradiotherapy did not provide predictive value for subsequent tumor response. For mediastinal initial staging, the sensitivity and specificity of FDG-PET were 75 and 90.5%. The sensitivity and specificity of FDG-PET for mediastinal restaging were 58.0 and 93.0%. These results indicate that FDG-PET is useful for monitoring the therapeutic effect of neoadjuvant chemoradiotherapy in patients with stage III NSCLC. For the primary lesions, SUV based analysis has high sensitivity but limited specificity for detecting residual tumor. In contrast, for restaging of mediastinal lymph nodes, FDG-PET is highly specific, but has limited sensitivity.     

Evaluation of F18-deoxyglucose positron emission tomography (FDG-PET) to assess the nature of neurogenic tumours.

AIMS: Benign neurofibromas and malignant peripheral nerve sheath tumours (MPNST) commonly develop in patients with neurofibromatosis. Differentiation of benign from malignant tumours by conventional preoperative imaging is unreliable. FDG-PET is a non-invasive technique for biological tumour evaluation. The aim of this study was to assess the value of FDG-PET in patients with neurogenic tumours suspicious for MPNST. METHODS: Benign and malignant neurogenic soft tissue tumours were prospectively evaluated by computed tomography or magnetic resonance imaging. Three-dimensional qualitative and quantitative FDG-PET was performed. Standard uptake value (SUV) was analyzed with respect to histological diagnosis and follow-up data. RESULTS: Twenty-five neurogenic soft tissue tumours were included. FDG-PET identified all primary (n=6) and recurrent MPNST (n=7). Benign lesions (n=12) did not demonstrate high FDG uptake. The SUV was significantly higher in MPNST (median 2.9; range 1.8-12.3), than in benign tumours (median 1.1; range 0.5-1.8) (p<0.001). At a cut-off value of 1.8 SUV measured 1 h post-injection FDG-PET distinguished between MPNST and benign neurogenic tumours with 100% sensitivity and 83% specificity. CONCLUSIONS: FDG-PET allows discrimination of benign from malignant neurogenic tumours. This should be particularly useful in patients with neurofibromatosis as FDG-PET may help to avoid multiple surgical procedures for benign tumours.     

FDG PET-CT标准摄取值在预测放射性肺炎发生中的作用

目的 探讨肺癌患者放射治疗前后FDG PET-CT标准摄取值(SUV)及其变化在预测放射性肺炎发生中的作用.方法 40例未经手术的非小细胞肺癌(NSCLC)患者在放射治疗前后均行PET-CT检查,分别测量出受照≤5 Gy、5.1～15 Gy、15.1～35 Gy、35.1～60 Gy以及>60 Gy肺组织放射治疗前后的平均SUV,比较发生放射性肺炎组与未发生放射性肺炎组SUV的变化情况,以及受照肺组织的SUV与未受照射肺组织SUV值之比(L/B).结果 40例患者中,有8例在治疗后发生放射性肺炎,其中2级6例,3级2例.受照剂量35.1～60 Gy肺组织的SUV与放射性肺炎的发生明显相关,当SUV≥1时,放射性肺炎的发生率为41.7%,明显高于全组放射性肺炎的发生率(20.0%;X2=3.96,P<0.05),SUV预测放射性肺炎的敏感度和特异度分别为62.5%和78.1%.L/B≥2.5时,放射性肺炎的发生率为40.7%,亦明显高于全组放射性肺炎的发生率(20.0%;X2=4.92,P<0.05).以L/B≥2.5为标准预测放射性肺炎的敏感度和特异度分别为72.7%和90.9%.SUV≥1与L/B≥2.5在预测放射性肺炎发生率之间的差异无统计学意义(X2=0.002,P>0.05).结论 SUV和L/B的大小与放射性肺炎的发生呈正相关,临床医生可根据FDG PET-CT提供的SUV和L/B来预测放射性肺炎的发生.     

FDG-PET scanning after radiation can predict tumor regrowth three months later

PURPOSE: Positron emission tomography (PET) with 2-[(18)F]fluoro-2-deoxy-D-glucose (FDG) is well known for providing excellent clinical information regarding malignant tumors. We investigated whether dual-time FDG-PET performed immediately post radiation could predict early regrowth of malignant tumors. MATERIALS AND METHODS: Twenty patients with malignant tumors were included in this study. All patients received radiation, and each underwent FDG-PET before the initiation of therapy and within 10 days of completing their course of irradiation. PET images after irradiation were obtained at 60 min and 180 min post FDG injection. For 26 lesions in 20 patients, standardized uptake value (SUV) before and after treatment was calculated and then correlated with postradiation tumor response and outcome at 3 months status post irradiation. RESULTS: Retention index [RI = (SUV on delayed image - SUV on early image)/SUV on early image] after irradiation showed a significant difference between patients with residual tumor and those without residual tumor at 3 months status post irradiation (p < 0.0025). All 9 lesions in 6 patients with residual tumors showed more than 0.1 of RI, whereas none of the lesions with less than 0.1 of RI revealed residual tumors. CONCLUSIONS: Dual-time FDG-PET imaging just after irradiation is potentially useful for predicting early regrowth of malignant tumors.     

Differential Diagnoses of Solitary Pulmonary Nodules in Patients with an Extrcrlhoracic Malignant Tumor：CT and Pathologic Correlations

Objective To determine the possibility of definitive diagnosis for solitary pulmonary nodules in patients with a primary extrathoracic malignant neoplasm (ETM-SPN), and to further evaluate the value of CT for differential diagnosis in ETM-SPN by a multivariate retrospective study. Methods Eighty-three patients with pathologically and clinically proven ETM-SPN with a diameter smaller than 3 cm were included in this study. The pathological characteristics of the SPN were correlated with those of the extrathoracic neoplasm, with the patient’s age, gender, smoking history, disease -free time interval between the diagnosis of the extrathoracic malignancy and that of the lung lesion. In all 83 cases, CT scans were reviewed to confirm the solitary nature, size, and nodular morphology of the lung lesion. Results Of all 83 cases, the mean age was (57.43±15.34) years. There were 51 males and 32 females, with the ratio of 1.59:1. The lesions included solitary metastasis in 43 cases, pulmonary malignant lesions in 33, and benign lesions in seven. Between the primary lung cancers and solitary metastasis groups, there was no significant difference in the gender ratio (1.20:1 vs 2.31:1, x²=0.0209,P>0.05), but there was a significant difference between the mean age (62.48 ±11.96 years vs 54.10±16.49 years,t =3.34,P<0.05). In the primary lung cancer and metastasis patient group, the percentage of patients who had a smoking history were 39.3 %(11/17) and 35.9 %(14/39), respectively. Patients with a primary lung cancer had no significant higher frequency of smoking history than did those with a metastatic lesion (x²=0.640,P>0.05). Of 81 cases who were followed-up, the mean time of the disease-free interval between extrapulmonary malignancy diagnosis and pulmonary lesion differentiation was 39.73 ±6.29 months (range 0∼300 months, median 20.00 months), whereas those in the primary lung cancer group and metastatic group were 65.62 ±13.45 months and 22.83 ±4.19 months respectively. This difference was significant between the two groups (Wilcoxon rank sum test,U=2.796,P<0.01). Of all 83 cases, there were ten extrapulmonary squamous carcinomas and 58 adenocarcinomas with ratio of primary lung cancer and solitary metastasis of the tumors were 7: 3 and 24:34, respectively (Ξ² =1.781, P >0.05), without showing a statistically significant relevance between the pathologic patterns of extrapulmonary malignancy and characteristics of the lung nodules. Of all the 83 cases, the mean diameters were (2.77 ±.25) cm, whereas the diameters of 33 cases of primary lung cancer and 43 cases of a solitary metastatic lesion were (2.86±1.18) cm and (2.62±1.31) cm, respectively. There was no association between the two groups (t=1.29,P>0.05). There was a statistically significant association between primary lung cancer and the metastatic group with spiculate and smooth edges of the lung lesion (Ξ²=8.562,P<0.01; Ξ²=15.220,P<0.001). The study showed that a lung nodule with a spiculated margin correlated with a primary lung carcinoma, whereas those nodules with a smooth edge may more frequently show as a metastastic pulmonary lesion. CTpathologic correlative analyses of hilar and mediastinal adenopathy were reviewed in 37 patients who underwent lobectomy and thoracotomy. There was no statistical significant difference between the primary lung cancer group and the metastatic group (Ξ²=2.801,P>0.05). Conclusion The likelihood of a primary lung cancer versus a metastasis of ETM-SPN smaller than 3 cm mainly depends on the patient’s age, free interval between the two tumors and CT morphological characteristics of the lung lesion. This study showed there was no significant relevancy to factors such as gender, smoking history, pathological patterns of the extrapulmonary neoplasm or whether there has hilar or mediastinal adenopathy.     

Lung cancer and positron emission tomography with fluorodeoxyglucose

Over the past years, positron emission tomography (PET) with fluoro-2-deoxy-D-glucose (FDG) has emerged as an important imaging modality. In the thorax, FDG-PET has been shown to differentiate benign from malignant pulmonary lesions and stage lung cancer. Preliminary studies have shown its usefulness in assessing tumor recurrence, and assisting in radiotherapy planning. FDG-PET is often more accurate than conventional imaging studies, and has been proven to be cost-effective in evaluating lung cancer patients. This review will discuss the current applications of FDG-PET as compared with conventional imaging in diagnosing, staging, and following patients with lung cancer.     

FDG-PET for prediction of survival of patients with metastatic colorectal carcinoma.

BACKGROUND: The current study focuses on the prognostic value of pretreatment metabolic activity in metastases as measured with [(18)F]fluorodeoxyglucose positron emission tomography (FDG-PET), as an indicator of survival in colorectal cancer. PATIENTS AND METHODS: In a prospective series of 152 patients with metastatic colorectal cancer, of whom 67 were treated with resection of metastases and 85 with chemotherapy, standardized uptake values (SUV) as measured with FDG-PET, were calculated prior to treatment. Survival probabilities were estimated by Cox proportional regression analysis. For Kaplan-Meier analysis SUV was stratified by the median value. Survival differences were assessed using the log-rank test. RESULTS: SUV in metastases was a significant predictor for overall survival (hazard ratio 1.17, 95% confidence interval 1.06-1.30, P = 0.002), independent of the subsequent treatment. According to the median value of the patient population a low (SUV <4.26) and high uptake group (SUV >4.26) was defined. The median survival and the 2- and 3-year survival rates were 32 months, 59% and 45%, respectively, in the low-uptake group and 19 months, 37% and 28%, respectively, in the high-uptake group (P = 0.017). CONCLUSION: A significant survival benefit was observed in patients with low FDG uptake in metastases of colorectal cancer.     

18F]FDG positron emission tomography/computed tomography and multidetector computed tomography roles in thymic lesion treatment planning

RATIONALE: Thymic masses may represent an unsolved diagnostic problem which often require surgical procedures for an accurate staging. A non-invasive way to determine the nature of thymic lesions would help identify the patients which are true candidates for surgery. Our retrospective study aims to assess multidetector computed tomography and 2-[(18)F]fluoro-2-deoxyglucose positron emission tomography/computed tomography ([(18)F]FDG-PET/CT) capacity to distinguish benign from malignant thymic lesions. METHODS: Helical multidetector CT (MDCT) and [(18)F]FDG-PET/CT of twenty consecutive patients presenting with a thymic mass at our Institute were retrospectively analyzed. MDCT scans were focused on morphologic features and invasiveness characteristics. Qualitative and semi-quantitative analyses by maximum standardized uptake value corrected for body weight (SUVbw max) were performed on [(18)F]FDG-PET/CT. In all cases, readers were blinded to pathology findings. Both imaging techniques were correlated to final pathology. Student's t-test was performed on SUVbw max stratified for thymic epithelial tumors. RESULTS: In the group of benign lesions MDCT correctly identified well-defined margins of masses in 8 out of 8 patients whereas [(18)F]FDG-PET/CT was negative in 7 out of 8 patients. Among malignant lesions MDCT revealed mediastinum fat or infiltration of adjacent organs in 10/12 patients. On the other hand [(18)F]FDG-PET/CT showed increased radiotracer uptake in 12/12 patients. CONCLUSIONS: MDCT and [(18)F]FDG-PET/CT alone are not able to differentiate the nature of thymic lesions. However, they are two non-invasive complementary techniques which can be used to differentiate benign from high-risk malignant thymic lesions. These findings should be taken into account before surgery is performed as a diagnostic procedure.     

Delayed (18)F-fluoro-2-deoxy-D-glucose positron emission tomography scan for differentiation between malignant and benign lesions in the pancreas

BACKGROUND: Positron emission tomography (PET) using (18)F-fluoro-2-deoxy-D-glucose (FDG) has been used for the evaluation of various tumors, but accumulation in inflammatory lesions makes it a controversial modality. The aim of this study was to investigate the usefulness of delayed scanning in differentiation between malignant and benign lesions in the pancreas. METHODS: Forty-seven patients with suspected pancreatic carcinoma were studied by FDG-PET. All patients received approximately 370 megabequerels of FDG after a transmission scan, and an emission scan was performed 1 hour and 2 hours later for all patients. A subset of 19 patients was also scanned at 3 hours postinjection. The standardized uptake value (SUV) was determined, and the retention index was calculated by dividing the increase in the SUV between 1 hour and 2 hours postinjection by the SUV at 1 hour postinjection. RESULTS: Of 27 malignant lesions, the SUVs of 22 lesions increased at 2 hours postinjection, whereas the FDG uptake in 17 of 20 benign lesions decreased. The SUVs at 3 hours postinjection were higher than those at 2 hours postinjection in 9 of 14 malignant lesions and in 2 of 5 benign lesions. Malignant lesions showed a higher retention index than benign lesions (mean +/- standard deviation: 12. 36 +/- 13.37 and -7.05 +/- 17.28, respectively; P < 0.0001). Applying an SUV of 2.5 at 1 hour postinjection with the cut-off value for the differentiation between malignant and benign lesions caused one false negative result and seven false positive results, with a diagnostic accuracy of 83.0% (39 of 47 patients). However, combining the retention index with the SUV obtained at 2 hours postinjection provided a higher diagnostic accuracy (91.5%; 43 or 47 patients) than the SUV alone. The false negative rate remained constant when the retention index was taken into account. Images at 3 hours postinjection usually were unhelpful in differentiating further between malignant lesions and benign lesions. CONCLUSIONS: The current data suggest that delayed FDG-PET scanning at 2 hours postinjection may contribute to differentiation between malignant and benign lesions in the pancreas.     

核医学正电子断层显像在肾肿瘤患者术前诊断中的作用

目的探讨PET在肾肿瘤术前诊断中作用。方法回顾性分析134例肾肿瘤患者PET图像。134例肾肿瘤术前评估患者中,32例行常规氟-18脱氧葡萄糖(18F-fluorodeoxyglucose,18F-FDG)PET或PET/CT显像(以下简称FDG-PET),51例行FDG-PET双时相显像,51例1周内分别行FDG-PET及碳-11乙酸盐(11C-acetate,AC)PET或PET/CT(以下简称AC-PET)双核素检查。收集其临床资料和影像检查结果。以病理结果为金标准。结果 FDG-PET对肾原发恶性肿瘤总的诊断准确率为48.5%,阳性预测值为96.3%,对透明细胞癌诊断准确率最低,为28.6%。对肾盂癌及其他恶性肿瘤诊断准确率为92.9%和75.0%。AC-PET对透明细胞癌诊断准确率93.5%。FDG-PET双时相显像60.0%阳性病灶标准摄取值(standard uptake value,SUV)升高,2例阴性病灶变为阳性。20例PET检查前其他检查发现肾外病灶的患者,检查后排除4例,并新发现6例患者肾外转移病灶。结论 FDG-PET检查对肾盂癌及其他恶性肿瘤诊断准确性高,对肾实质肿瘤诊断能力差,对肾肿瘤患者术前分期有帮助。AC-PET可弥补FDG-PET的不足。FDG-PET双时相显像不能从根本上解决FDG-PET对肾肿瘤诊断假阴性的问题。     

Correlation of PET standard uptake value and CT window-level thresholds for target delineation in CT-based radiation treatment planning

PURPOSE: To develop standardized correlates of [18F]fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET) standard uptake value (SUV) to computed tomography (CT)-based window and levels. METHODS AND MATERIALS: Nineteen patients with non-small-cell lung cancer who underwent imaging with positron emission tomography (PET) and CT were selected. A method of standardizing SUV within CT planning software was developed. A scale factor, determined by a sensitivity calibration of the PET scanner, converts voxel counts to activity per gram in tissue, allowing SUVs to be correlated to CT window and levels. A method of limiting interobserver variations was devised to enhance "edges" of regions of interest based on SUV thresholds. The difference in gross tumor volumes (GTVs) based on CT, PET SUV >or= 2.5, and regions of 40% maximum SUV were analyzed. RESULTS: The mean SUV was 9.3. Mean GTV volumes were 253 cc for CT, 221 cc for SUV >or= 2.5, and 97 cc for SUV40%Max. Average volume difference was -259% between >or=2.5 SUV and CT and -162% between SUV40%Max and CT. Percent difference between GTV >or= 2.5 SUV and SUV40%Max remained constant beyond SUV > 7. For SUVs 4-6, best correlation among SUV thresholds occurred at volumes near 90 cc. Mean percent change from GTVs contoured according to CT (GTV CT) was -260% for GTV2.5 and -162% for GTV40%Max. Using the SUV40%Max threshold resulted in a significant alteration of volume in 98% of patients, while the SUV2.5 threshold resulted in an alteration of volume in 58% of patients. CONCLUSIONS: Our method of correlating SUV to W/L thresholds permits accurate displaying of SUV in coregistered PET/CT studies. The optimal SUV thresholds to contour GTV depend on maximum tumor SUV and volume. Best correlation occurs with SUVs >6 and small volumes <100 cc. At SUVs >7, differences between the SUV threshold filters remain constant. Because of variability in volumes obtained by using SUV40%Max, we recommend using SUV >or= 2.5 for radiotherapy planning in non-small-cell lung cancer.     

Characterization of tumor heterogeneity using dynamic contrast enhanced CT and FDG-PET in non-small cell lung cancer

Purpose

Dynamic contrast-enhanced CT (DCE-CT) quantifies vasculature properties of tumors, whereas static FDG-PET/CT defines metabolic activity. Both imaging modalities are capable of showing intra-tumor heterogeneity. We investigated differences in vasculature properties within primary non-small cell lung cancer (NSCLC) tumors measured by DCE-CT and metabolic activity from FDG-PET/CT.

Methods

Thirty three NSCLC patients were analyzed prior to treatment. FDG-PET/CT and DCE-CT were co-registered. The tumor was delineated and metabolic activity was segmented on the FDG-PET/CT in two regions: low (<50% maximum SUV) and high (?50% maximum SUV) metabolic uptake. Blood flow, blood volume and permeability were calculated using a maximum slope, deconvolution algorithm and a Patlak model. Correlations were assessed between perfusion parameters for the regions of interest.

Results

DCE-CT provided additional information on vasculature and tumor heterogeneity that was not correlated to metabolic tumor activity. There was no significant difference between low and high metabolic active regions for any of the DCE-CT parameters. Furthermore, only moderate correlations between maximum SUV and DCE-CT parameters were observed.

Conclusions

No direct correlation was observed between FDG-uptake and parameters extracted from DCE-CT. DCE-CT may provide complementary information to the characterization of primary NSCLC tumors over FDG-PET/CT imaging.     

Etiology of solitary extrapulmonary positron emission tomography and computed tomography findings in patients with lung cancer.

PURPOSE: The aim of this prospective study was to assess the incidence and the nature of solitary extrapulmonary [18F] fluorodeoxyglucose (FDG) accumulations in patients with non-small-cell lung cancer (NSCLC) staged with integrated positron emission tomography and computed tomography (PET/CT) and to evaluate the impact on management. PATIENTS AND METHODS: A total of 350 patients with NSCLC underwent whole-body PET/CT imaging. All solitary extrapulmonary FDG accumulations were evaluated by histopathology, further imaging, or clinical follow-up. RESULTS: PET/CT imaging revealed extrapulmonary lesions in 110 patients. In 72 patients (21%), solitary lesions were present. A diagnosis was obtained in 69 of these patients, including 37 (54%) with solitary metastases and 32 (46%) with lesions unrelated to the lung primary. Histopathologic examinations of these 32 lesions revealed a second clinically unsuspected malignancy or a recurrence of a previous diagnosed carcinoma in six patients (19%) and a benign tumor or inflammatory lesion in 26 patients (81%). The six malignancies consisted of carcinoma of the breast in two patients, and carcinoma of the orbit, esophagus, prostate, and non-Hodgkin's lymphoma in one patient each. Benign tumors and inflammatory lesions included eight colon adenomas, four Warthin's tumors, one granuloma of the lower jaw, one adenoma of the thyroid gland, one compensatory muscle activity due to vocal chord palsy, two occurrences of arthritis, three occurrences of reflux esophagitis, two occurrences of pancreatitis, two occurrences of diverticulitis, one hemorrhoidal inflammation, and one rib fracture. CONCLUSION: Solitary extrapulmonary FDG accumulations in patients with newly diagnosed lung cancer should be analyzed critically for correct staging and optimal therapy, given that up to half of the lesions may represent unrelated malignancies or benign disease.     

18F]5-fluoro-2-deoxyuridine-PET for imaging of malignant tumors and for measuring tissue proliferation

The nucleoside 5-fluoro-2-deoxyuridine is a pyrimidine analogue accumulating in proliferative cells. We prospectively evaluated biodistribution of the PET tracer [(18)F]5-fluoro-2-deoxyuridine (FdUrd), its value for imaging malignant tumors, and its correlation to both [(18)F]2-fluoro-2-deoxyglucose (FDG)-PET findings and histological proliferation indices. In 11 previously untreated patients (5 lung carcinoma; 3 soft tissue sarcoma; 2 gastrointestinal carcinoma; 1 non-Hodgkin lymphoma [NHL]), mean doses of 290 MBq FdUrd and 390 MBq FDG were administered intravenously on subsequent days. Static PET scans were initiated 50-70 min after administration and the mean standardized uptake values (SUV) were calculated. Dynamic emission FdUrd scans were performed in 8/11 patients. Time-activity curves of blood and tumors as well as SUV of tumor lesions and organs were calculated. Proliferative activity was evaluated by Ki-67 immunohistostaining of biopsies. Tracer accumulated physiologically in liver, kidney, and bladder. SUVs were: kidney, 4.8 +/- 0.66; liver, 4.1 +/- 0.36; vertebrae, 0.70 +/- 0.17; spleen, 0.37 +/- 0.06; lungs, 0.19 +/- 0.05; femora/humeri, 0.14 +/- 0.03. Five patients exhibited significant intratumoral FdUrd-uptake (2 sarcomas; 1 NHL; 2 lung carcinomas) with mean SUVs ranging from 0.7 to 10.5. Metastases were not detected. Time-activity curves showed a rapid initial increase of intratumoral activity followed by activity retention. FDG-PET was positive in 10/11 patients. Correlation between the SUV of FdUrd-PET and FDG-PET or the tissue proliferation index, respectively, was not significant. FdUrd was a suitable tracer for imaging malignant tumors only in exceptional cases: Sarcoma, NHL, and some lung carcinomas were detected. FdUrd-PET was less effective than FDG-PET. In this group of patients, it was not useful in measuring tissue proliferation.     

Correlation of 18-F-fluorodeoxyglucose (FDG) accumulation with glucose transporter (Glut-1) expression in esophageal squamous cell carcinoma

BACKGROUND: We previously reported that positron emission tomography (PET) with 18-F-fluorodeoxyglucose (FDG) might be a useful tool for evaluating the stage of esophageal squamous cell carcinoma (SCC), and that FDG-PET shows greater accuracy in the diagnosis of lymph node metastasis than computed tomography. Further, we elucidated the relationships among FDG-PET performance, glucose transporter (Glut)-1 expression and serum levels of the tumor markers carcinoembryonic antigen (CEA), cytokeratin 19 fragment (CYFRA) and squamous cell carcinoma antigen (SCC-Ag) in esophageal SCC. PATIENTS AND METHODS: We studied 44 patients with thoracic esophageal SCC who had undergone radical esophagectomy. Immunohistochemical analysis was used to detect the expression of Glut-1 in resected specimens and FDG accumulation was assessed by FDG-PET scan. RESULTS: FDG uptake in the primary tumor was found in 34 out of 44 (77.3%) patients. No significant correlation was observed between SUVs and the tumor markers CEA, CYFRA and SCC-Ag. The survival rate in patients with high FDG uptake (SUV > 3) was significantly lower than in cases with low FDG uptake (SUV < 3) (p < 0.01). A significant correlation was observed between SUV and Glut-1 expression (p < 0.05). The prognosis in patients with both low Glut-1 expression and low FDG uptake tended to be more favorable than in patients with high Glut-1 expression and/or high FDG uptake. CONCLUSION: Glut-1 expression was related to FDG uptake, and assessment of both FDG uptake and Glut-1 expression might be useful for providing prognostic information in patients with esophageal SCC.     

Can FDG-PET/CT predict early response to neoadjuvant chemotherapy in breast cancer?

Purpose

Neoadjuvant chemotherapy (NAC) in breast cancer is currently used not only for locally advanced tumors, but also for large operable tumors when breast preservation is considered. It also provides the opportunity to evaluate chemotherapy tumor response. Our aim was to correlate the relative change in the standardized uptake value (SUV) of ¹⁸F-2-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET/CT) with pathologic response after NAC.

Methods

We prospectively evaluated 40 patients with invasive ductal breast carcinomas from February 2010 to December 2011. FDG-PET/CT was performed at baseline and after the second cycle of NAC. All patients underwent surgery after NAC. Pathologic response was evaluated according to Residual Cancer Burden (RCB) index.

Results

The mean age was 41.9 years. Median primary tumor size was 6 cm. Pathologic complete response (pCR) was obtained in 12 (30%) patients. The tumor baseline mean maximum SUV (SUVmax), and after second cycle were: 8.97 (sd.4.3) and 4.07 (sd.3.2), respectively. The relative change (ΔSUV) after the second course of NAC was significantly higher for patients with pCR (−81.58%) when compared to the non-pCR patients (−40.18%) (p = 0.001). The optimal ΔSUV threshold that discriminates between pCR and non-pCR was −71.8% (83.3% sensitivity; 78.5% specificity). Moreover, the optimal ΔSUV threshold to discriminate between NAC responders and non-responders was −59.1% (68% sensitivity; 75.0% specificity).

Conclusions

Our data suggest that the FDG-PET/CT ΔSUV after the second course of NAC can predict pathological response in ductal breast carcinomas, and potentially identify a subgroup of non-responding patients for whom ineffective chemotherapy should be avoided.

Synopsis

Breast cancer is the most frequently diagnosed cancer in women. The indications for neoadjuvant chemotherapy are increasing. Early information on chemotherapy response is crucial and methods that predict the therapeutic effectiveness might avoid potentially ineffective chemotherapies in non-responding patients.