Dual-time-point FDG-PET for evaluation of lymph node metastasis in patients with non-small-cell lung cancer

Is Delayed Image of 18F-FDG PET/CT Necessary for Mediastinal Lymph Node Staging in Non-Small Cell Lung Cancer Patients?

PURPOSE

The purpose of this study was to evaluate the diagnostic accuracies of dual-time-point (DTP) 18F-FDG PET/CT for detection of mediastinal lymph node (LN) metastasis in non-small cell lung cancer (NSCLC) patients through a systematic review and meta-analysis.

PATIENTS AND METHODS

The PubMed, Cochrane database, and EMBASE database, from the earliest available date of indexing through October 31, 2021, were searched for studies evaluating diagnostic performance of DTP 18F-FDG PET/CT for detection of metastatic mediastinal LN in NSCLC patients. We determined the sensitivities and specificities across studies, calculated positive and negative likelihood ratios (LR+ and LR-), and constructed summary receiver operating characteristic curves.

RESULTS

Ten studies (758 patients) were included in the current study. In patient-based analysis, early image showed a sensitivity of 0.76 and a specificity of 0.75. Delayed image revealed a sensitivity of 0.84 and a specificity of 0.71. In LN-based analysis, early image showed a sensitivity of 0.80 and a specificity of 0.83. Delayed image revealed a sensitivity of 0.84 and a specificity of 0.87. Retention index or %ΔSUVmax is superior to early or delayed images of DTP 18F-FDG PET/CT for detection of mediastinal LN metastasis.

CONCLUSIONS

Dual-time-point 18F-FDG PET/CT showed a good diagnostic performances for detection of metastatic mediastinal LNs in NSCLC patients. Early and delayed images of DTP 18F-FDG PET/CT revealed similar diagnostic accuracies for LN metastasis. However, retention index or %ΔSUVmax is superior to early or delayed images of DTP 18F-FDG PET/CT for detection of mediastinal LN metastasis in NSCLC patients. Further large multicenter studies would be necessary to substantiate the diagnostic accuracy of DTP 18F-FDG PET/CT for mediastinal LN staging in NSCLC patients.

Preliminary clinical assessment of dynamic 18F-fluorodeoxyglucose positron emission tomography/computed tomography for evaluating lymph node metastasis in patients with lung cancer: a prospective study

OBJECTIVE

We assessed the diagnostic capacity of dynamic fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) and dual-time-point (DTP) PET/CT to explore the optimal scan timing for nodal staging in lung cancer.

METHODS

Thirty-four patients with lung cancer underwent dynamic and consecutive DTP PET/CT scans. Two readers visually evaluated FDG uptake within each lymph node (LN) and pulmonary artery (metastatic LN: n = 10; nonmetastatic LN: n = 121). For each dynamic and DTP scan, we compared the maximum standardized uptake value (SUVmax) and the retention index of the SUVmax (RI-SUVmax) between metastatic and nonmetastatic LNs. We compared the diagnostic capacity of the dynamic and DTP scans using receiver operating characteristic (ROC) analyses.

RESULTS

In the visual analyses of LN metastases, a sensitivity of 20.0-60.0% and specificity of 97.5-100.0% were identified for the first to third dynamic scans. The sensitivity of the 1-h early and 2-h delayed scans was 80.0% and 90.0%, respectively, whereas the specificity was 66.9% and 47.9%, respectively. The visual analysis of the dynamic second phase had the highest accuracy. Semiquantitative analyses revealed that the SUVmax was significantly higher for metastatic LNs than for nonmetastatic LNs in the dynamic second and third phases and the 1-h early and 2-h delayed phases (p < 0.05 for all). The RI-SUVmax was higher in metastatic LNs than in nonmetastatic LNs for the dynamic scan (p = 0.004) and the DTP scan (p = 0.002). The ROC analyses showed that SUV2 and SUV3 had higher performances with high specificity, high negative predictive value, and high accuracy than the other parameters. The area under the ROC curve of the RI-SUV-dual-time-point had the highest value (0.794) without any significant differences between the area under the ROC curves for all parameters (p > 0.05 for all).

CONCLUSIONS

Based on the visual and semiquantitative analyses, ¹⁸F-FDG dynamic PET/CT exhibited excellent performance with extremely high specificity in the dynamic second phase.

Dual-time point 18F-FDG-PET and PET/CT for Differentiating Benign From Malignant Musculoskeletal Lesions: Opportunities and Limitations

In this review, we summarize the false-positive and false-negative results of standard ¹⁸F-FDG-PET/CT in characterizing musculoskeletal lesions and discussed the added value and limitations of dual-time point imaging (DTPI) and delayed imaging in differentiating malignant from benign musculoskeletal lesions, based on review of the peer-reviewed literature. The quantitative and semiquantitative parameters adopted for DTPI are standardized uptake value (mainly maximum standardized uptake value [SUVmax]) and retention index (RI), calculated as RI (%) = 100% × (SUV [maxD-Delayed] - SUV [maxE-Early])/SUV [maxE-Early], although the criteria and cutoff for diagnosing malignancy in studies have varied considerably. Also, there has been considerable heterogeneity in protocol (time point of delayed imaging), interpretation, and results in dual-time point (DTP) ¹⁸F-FDG-PET for differentiating malignant from benign musculoskeletal lesions in various research studies. The specificity of DTPI is a function of many factors such as the nature of the musculoskeletal lesion or malignancy in question, the prevalence of false-positive etiologies in the patient population, and the cutoff values (either SUVmax or RI) employed to define a malignancy. Despite the apparent conflicting reports on the performance, there have been certain common points of agreement regarding DTPI: (1) DTP PET increases the sensitivity of ¹⁸F-FDG-PET/CT due to continued clearance of background activity and increasing ¹⁸F-FDG accumulation in malignant lesions, when the same diagnostic criteria (as in the initial standard single-time point imaging) are used. Increased sensitivity for lesion detection can be viewed as a strong point of DTP and delayed-time point imaging. (2) The causes for false positives (such as active infectious or inflammatory lesions and locally aggressive benign tumors) and false negatives (eg, low-grade sarcomas) are the major hurdles accounting for reduced diagnostic value of the technique, with overlap of ¹⁸F-FDG uptake patterns between benign and malignant musculoskeletal lesions on DTPI. (3) DTPI, however, could still be potentially useful in increasing the confidence of interpretation such as differentiating malignancy from sites of inactive or chronic inflammation, post-treatment viable residue vs necrosis, and certain other benign lesions. (4) Consideration of diagnostic CT component of PET/CT and the patient's clinical picture can lead to increase in specificity of interpretation in a given case scenario. Further systematic research, adoption of uniform protocol, and interpretation criterion could evolve the specific indications and interpretation criteria of DTPI for improved diagnostic accuracy in musculoskeletal lesions and its clinical applications.

Kikuchi-Fujimoto Disease with 18F-Fludeoxyglucose Uptake in Cervical Lymph Nodes on Dual-time-point Imaging Positron Emission Tomography/Computed Tomography Mimicking Malignant Disease

Kikuchi-Fujimoto disease (KFD) is a benign but self-limiting disorder. However, KFD is often misdiagnosed as a malignant disease. Although 18F-fludeoxyglucose (FDG) uptake on dual-time-point imaging (DTPI) positron emission tomography (PET)/computed tomography (CT) is useful in distinguishing malignant from benign disease, the latter sometimes mimics malignancy on DTPI PET/CT, resulting in a misdiagnosis. Here, we describe the case of a 30-year-old woman who complained of cervical lymphadenopathy. PET showed increased FDG uptake in multiple lymph nodes, with a maximum standardized uptake value (SUVmax) of 19.0 in the early phase to 21.8 in the late phase. A biopsy was performed, and pathological examination revealed KFD. KFD with FDG uptake in lymph nodes on DTPI PET/CT is rare and difficult to be distinguished from a malignant disease.

Clinical significance of dual-time-point 18F-FDG PET imaging in resectable non-small cell lung cancer

OBJECTIVE

The maximal standardized uptake value (SUVmax) of pulmonary lesions on dual-time-point (DTP) fluorodeoxyglucose positron emission tomography (FDG-PET) has been shown to be useful for differentiation between malignant and non-malignant pulmonary lesions, and also to be of value for intrathoracic nodal staging of non-small cell lung cancer (NSCLC). However, a few NSCLC lesions have been found to show decreased FDG uptake on delayed images, and the significance of this finding remains unknown.

PATIENTS AND METHODS

We conducted a retrospective review of the data of 284 patients with NSCLC who underwent DTP FDG-PET before surgery. Cases of adenocarcinoma in situ and minimally invasive adenocarcinoma were excluded, because these lesions show little FDG uptake. Each patient was scanned at 60 min (early acquisition; SUV-E) and 115 min (delayed acquisition; SUV-D) after the radiopharmaceutical injection. The intratumoral retention index (RI) of 18F-FDG was measured for each examination by the DTP method. Recurrence-free survival (RFS) was determined by the Kaplan-Meier method and compared in relation to the SUV-E, SUV-D, and RI by univariate and multivariate analysis using models including the clinico-pathological prognostic factors.

RESULTS

Of the 284 cases, the RI ≤ 0 was in 49 cases (17.3%). This group of patients showed lower values of SUV-E and SUV-D, a smaller tumor size, and a lower rate of lymphatic invasion or vascular invasion. It was particularly noteworthy that lymph node metastasis was not histopathologically confirmed in any of these patients. Univariate analysis identified the RI, SUV-E and SUV-D, besides age, tumor size, lymph node metastasis, and tumor differentiation grade as predictors of the RFS. On the other hand, multivariate analysis identified the RI and lymph node metastasis, but not the SUV-E and SUV-D, as independent predictors of the RFS.

CONCLUSIONS

This study demonstrated that DTP FDG-PET of the primary tumor in NSCLC can be useful to predict the RFS of the patients. In addition, this method may also be useful to predict the presence/absence of intrathoracic lymph node metastasis in these patients.

Diagnostic value of dual time-point 18 F-FDG PET/CT versus single time-point imaging for detection of mediastinal nodal metastasis in non-small cell lung cancer patients: a meta-analysis

BACKGROUND

Lymph node staging in non-small cell lung cancer (NSCLC) is challenging and important for determining treatment policy. Conflicting results have been presented to date.

PURPOSE

To evaluate the diagnostic performance of dual time-point (DTP) 18 F-FDG PET/CT compared with single time-point (STP) imaging for detecting mediastinal nodal metastases in patients with NSCLC.

MATERIAL AND METHODS

The PubMed, EMBASE, EBSCO, and Web of Knowledge databases were searched for relevant articles. The pooled sensitivity, specificity, diagnostic odds ratio (DOR), positive likelihood ratio (PLR), and negative likelihood ratio (NLR) were calculated using Meta-Disc software. Summary receiver-operating characteristic (SROC) curves were also constructed. The potential for between-study heterogeneity was explored using subgroup analyses.

RESULTS

A total of eight studies involving 654 patients fulfilled the inclusion criteria. On a per-patient analysis, the pooled sensitivity and specificity with a 95% confidence interval (CI) for DTP PET/CT were 0.85 (0.78-0.91), 0.75 (0.68-0.82), and for STP imaging, they were 0.79 (0.70-0.85), 0.73 (0.65-0.79), respectively. On a per-lesion basis, the corresponding values for DTP imaging were 0.84 (0.81-0.86), 0.89 (0.87-0.91), and for STP imaging, they were 0.84 (0.80-0.86), 0.83 (0.81-0.85), respectively.

CONCLUSION

DTP PET/CT performed better than STP imaging in evaluating the lymph node status of NSCLC patients and had the potential to be broadly applied in clinical practice. However, due to the small sample size and large heterogeneity, current evidence does not justify the implementation of DTP imaging in routine PET protocols for mediastinal lymph node staging of NSCLC.

Potential role of (18)F-2-fluoro-2-deoxy-glucose positron emission tomography/computed tomography imaging in patients presenting with generalized lymphadenopathy

Generalized lymphadenopathy is a common and often vexing clinical problem caused by various inflammatory, infective and malignant diseases. We aimed to review briefly and highlight the potential role of ¹⁸F-2-fluoro-2-deoxy-glucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) in such patients. ¹⁸F-FDG PET/CT can play an important role in the management of generalized lymphadenopathy. It can help in making an etiological diagnosis; can detect extranodal sites of involvement and employed for monitoring response to therapy.

Serial changes of FDG uptake and diagnosis of suspected lung malignancy: a lesion-based analysis

OBJECTIVE

This study prospectively evaluates the serial change of FDG uptake and its diagnostic value in malignant versus benign lung lesions in patients with suspected lung cancer.

PATIENTS AND METHODS

Patients with suspected lung malignancy underwent whole-body FDG PET/CT at 1, 2, and 3 hours after an IV injection of F-FDG. The SUVs of FDG in lung nodules and hilar/mediastinal nodes at each time point were correlated with biopsy/surgical pathologic findings.

RESULTS

There were a total of 45 malignant lesions and 80 benign lesions from 43 patients with pathologic diagnosis that were included for analysis. The SUVmax had an average of 25.5% increase in all tumor-positive lesions from 1 to 2 hours (vs 1.6% decrease in all tumor-negative lesions, P < 0.0001) and an average of 39.1% increase from 1 to 3 hours (vs 4.5% increase in all tumor-negative lesions, P < 0.0001). The receiver operating characteristic analysis showed that the 2-hour and 3-hour SUVmax had similar area under the curve and outperformed the SUVmax on the 1-hour initial imaging or retention index (RI). The optimal cutoff values to differentiate malignancy from benign lesions were 3.24 for 1-hour SUVmax, 3.67 for 2-hour SUVmax, and 4.21 for 3-hour SUVmax, with 11.6% for 1- to 2-hour RI and 23.9% for 1- to 3-hour RI. The 3-hour delayed SUVmax of 4.21 provided the best overall performance (accuracy of 88.8%). The analysis of the lesion-to-background ratio revealed that delayed imaging improved the image quality significantly, leading to much easier detection of either malignant or benign lesions.

CONCLUSIONS

Multiple time point FDG PET/CT imaging moderately improves the diagnostic accuracy of lung cancer and significantly improves the image quality.

18F-FDG PET/CT oncologic imaging at extended injection-to-scan acquisition time intervals derived from a single-institution 18F-FDG-directed surgery experience: feasibility and quantification of 18F-FDG accumulation within 18F-FDG-avid lesions and background tissues

Background

¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) is a well-established imaging modality for a wide variety of solid malignancies. Currently, only limited data exists regarding the utility of PET/CT imaging at very extended injection-to-scan acquisition times. The current retrospective data analysis assessed the feasibility and quantification of diagnostic ¹⁸F-FDG PET/CT oncologic imaging at extended injection-to-scan acquisition time intervals.

Methods

¹⁸F-FDG-avid lesions (not surgically manipulated or altered during ¹⁸F-FDG-directed surgery, and visualized both on preoperative and postoperative ¹⁸F-FDG PET/CT imaging) and corresponding background tissues were assessed for ¹⁸F-FDG accumulation on same-day preoperative and postoperative ¹⁸F-FDG PET/CT imaging. Multiple patient variables and ¹⁸F-FDG-avid lesion variables were examined.

Results

For the 32 ¹⁸F-FDG-avid lesions making up the final ¹⁸F-FDG-avid lesion data set (from among 7 patients), the mean injection-to-scan times of the preoperative and postoperative ¹⁸F-FDG PET/CT scans were 73 (±3, 70-78) and 530 (±79, 413-739) minutes, respectively (P < 0.001). The preoperative and postoperative mean ¹⁸F-FDG-avid lesion SUV_max values were 7.7 (±4.0, 3.6-19.5) and 11.3 (±6.0, 4.1-29.2), respectively (P < 0.001). The preoperative and postoperative mean background SUV_max values were 2.3 (±0.6, 1.0-3.2) and 2.1 (±0.6, 1.0-3.3), respectively (P = 0.017). The preoperative and postoperative mean lesion-to-background SUV_max ratios were 3.7 (±2.3, 1.5-9.8) and 5.8 (±3.6, 1.6-16.2), respectively, (P < 0.001).

Conclusions

¹⁸F-FDG PET/CT oncologic imaging can be successfully performed at extended injection-to-scan acquisition time intervals of up to approximately 5 half-lives for ¹⁸F-FDG while maintaining good/adequate diagnostic image quality. The resultant increase in the ¹⁸F-FDG-avid lesion SUV_max values, decreased background SUV_max values, and increased lesion-to-background SUV_max ratios seen from preoperative to postoperative ¹⁸F-FDG PET/CT imaging have great potential for allowing for the integrated, real-time use of ¹⁸F-FDG PET/CT imaging in conjunction with ¹⁸F-FDG-directed interventional radiology biopsy and ablation procedures and ¹⁸F-FDG-directed surgical procedures, as well as have far-reaching impact on potentially re-shaping future thinking regarding the “most optimal” injection-to-scan acquisition time interval for all routine diagnostic ¹⁸F-FDG PET/CT oncologic imaging.

Routine use of dual time ¹⁸F-FDG PET for staging of preoperative lung cancer: does it affect clinical management?

OBJECTIVE

The objective of this study was to compare the diagnostic accuracy of dual-time-point 18F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET) to single-time-point (18)F-FDG PET for staging of preoperative lung cancer.

METHODS

Between November 2008 and December 2009, 107 patients who were diagnosed as having lung cancer or strongly suspected of having lung cancer were enrolled. They underwent dual-time-point (18)F-FDG PET following conventional imaging. Dual-time-point (18)F-FDG PET imaging (whole body) was performed at 1-h (early) post-FDG injection and repeated (2 h delayed) after injection. The diagnostic accuracy of pre-PET staging and post-PET staging was retrospectively evaluated, and the diagnostic accuracy of dual-time-point (18)F-FDG PET was compared to that of single-time-point (18)F-FDG PET.

RESULTS

In 100 patients, the early (18)F-FDG PET scan resulted in upstaging of the tumor in ten (10 %) and down-staging of the tumor in five (5 %) compared to the conventional scan. The delayed phase of (18)F-FDG PET provided no additional information on staging for lung cancer patients. The remaining seven patients were diagnosed as not having lung cancer.

CONCLUSION

This study confirmed that dual-time-point (18)F-FDG PET is useful for differential diagnosis between benign and malignant lesions, but has no major impact on staging and therapeutic management of patients with pathologically proven lung cancer.

When should we recommend use of dual time-point and delayed time-point imaging techniques in FDG PET?

FDG PET and PET/CT are now widely used in oncological imaging for tumor characterization, staging, restaging, and response evaluation. However, numerous benign etiologies may cause increased FDG uptake indistinguishable from that of malignancy. Multiple studies have shown that dual time-point imaging (DTPI) of FDG PET may be helpful in differentiating malignancy from benign processes. However, exceptions exist, and some studies have demonstrated significant overlap of FDG uptake patterns between benign and malignant lesions on delayed time-point images. In this review, we summarize our experience and opinions on the value of DTPI and delayed time-point imaging in oncology, with a review of the relevant literature. We believe that the major value of DTPI and delayed time-point imaging is the increased sensitivity due to continued clearance of background activity and continued FDG accumulation in malignant lesions, if the same diagnostic criteria (as in the initial standard single time-point imaging) are used. The specificity of DTPI and delayed time-point imaging depends on multiple factors, including the prevalence of malignancies, the patient population, and the cut-off values (either SUV or retention index) used to define a malignancy. Thus, DTPI and delayed time-point imaging would be more useful if performed for evaluation of lesions in regions with significant background activity clearance over time (such as the liver, the spleen, the mediastinum), and if used in the evaluation of the extent of tumor involvement rather than in the characterization of the nature of any specific lesion. Acute infectious and non-infectious inflammatory lesions remain as the major culprit for diminished diagnostic performance of these approaches (especially in tuberculosis-endemic regions). Tumor heterogeneity may also contribute to inconsistent performance of DTPI. The authors believe that selective use of DTPI and delayed time-point imaging will improve diagnostic accuracy and interpretation confidence in FDG PET imaging.

Dual-time-point FDG PET/CT: Is It Useful for Lymph Node Staging in Patients with Non-Small-Cell Lung Cancer?

PURPOSE

Dual-time-point (DTP) FDG PET/CT has been shown to be useful for lymph node (LN) staging in patients with non-small-cell lung cancer (NSCLC). The aim of this study was to evaluate the LN staging ability of DTP FDG PET/CT in the predominant area of pulmonary tuberculosis.

METHODS

Sixty-nine NSCLC patients underwent DTP PET/CT. Regions of interest were placed on each LN of each station, and the maximum SUVs were measured. Three variables were obtained: (1) the SUV on the early scan (SUVearly), (2) the SUV on the delayed scan (SUVdelayed), and (3) the retention index of the SUV (RI). Each patient had one final LN stage and three other LN stages according to the cutoff values of SUVearly, SUVdelayed, and RI.

RESULTS

In the LN-based analysis, the area under the ROC curve of SUVdelayed (0.884) was significantly larger (P < 0.01) than those of SUVearly (0.868) and RI (0.717). Among the three variables, SUVdelayed was more accurate (P < 0.01) for detecting the mediastinal LN metastasis than SUVearly and RI. In the patient-based analysis, SUVdelayed had correctly determined LN stages in 55 of 69 patients (sensitivity, specificity, and accuracy = 88.7 %, 50.0 %, and 79.7 %), whereas SUVearly and RI correctly determined LN stages in 53 and 52 patients, respectively.

CONCLUSIONS

In this study, comparing the diagnostic efficacy of SUVearly, SUVdelayed, and RI for LN staging in patients with NSCLC, SUVdelayed was the most accurate variable for LN staging. DTP PET/CT could provide improved diagnostic accuracy for the LN staging of NSCLC.

Relationship Between Dual-Time Point FDG PET and Immunohistochemical Parameters in Preoperative Colorectal Cancer: Preliminary Study

PURPOSE

The clinical availability of 2-deoxy-2-[18F] fluoro-D-glucose (FDG) dual-time point positron emission tomography/computerized tomography (DTPP) has been investigated in diverse oncologic fields. The aim of this preliminary study was to evaluate the relationship between various immunohistopathologic markers reflecting disease progression of colorectal cancer and parameters extracted from FDG DTPP in colorectal cancer patients.

MATERIALS AND METHODS

Forty-seven patients with histologically confirmed colorectal cancer were analyzed in this preliminary study. FDG DTPP consisted of an early scan 1 h after FDG injection and a delayed scan 1.5 h after the early scan. Based on an analysis of FDG DTPP, we estimated the maximum standardized uptake value (SUV) of tumors on the early and delayed scans (SUVearly and SUVdelayed, respectively). The retention index (RI) was calculated as follows: (SUVdelayed - SUVearly) × 100/ SUVearly. The clinicopathological findings (size and T and N stages) and immunohistochemical factors [glucose transporter 1 (GLUT-1), hexokinase 2 (HK-2), p53, P504S, and β-catenin] were analyzed by visual analysis.

RESULTS

The RIs calculated from the SUVs ranged from -1.8 to 73.4 (31.8 ± 15.5). The RIs were significantly higher in patients with high T stages (T3 and T4) than with low T stages (T1 and T2; p < 0.05). Among the immunohistochemical analytic markers, GLUT-1 had the highest positive staining rate (93.6%) compared to other markers. Based on univariable analysis, it was shown that the RI of high-level GLUT-1 expression was significantly higher than low-level GLUT-1 expression (p = 0.01), and the RI of high-level p53 expression was slightly higher than low-level p53 expression (p = 0.08). Multivariate analysis to investigate a link between RI and clinicopathologic parameters of colorectal carcinoma showed that GLUT-1, p53, and T staging were independently connected with increased RIs (p < 0.05, total) using backward selection methods. There was no significant statistical relationship between SUVearly and SUVdelayed and clinicopathologic parameters in this study.

CONCLUSION

The RIs obtained from preoperative colorectal cancers had a significant relationship to tumor size, T staging, GLUT-1, and p53, in contrast to SUVearly or SUVdelayed. Compared with previous reports, our results showed that RI can better predict GLUT-1 expression than HK-2 and other immunohistochemical markers. This study demonstrated that the RI might have the potential to be applied as a prognostic marker in preoperative colorectal cancer.

Radiation pneumonitis in patients with lung and mediastinal tumours: a retrospective study of risk factors focused on pulmonary emphysema

OBJECTIVES

To evaluate the impact of pulmonary emphysema (PE) on the incidence and severity of radiation pneumonitis (RP) in patients with lung and mediastinal tumours.

METHODS

92 patients were enrolled. Involved-field radiation therapy (non-small cell carcinoma or mediastinal tumours in 69 patients; median 70 Gy) and accelerated hyperfractionation (limited disease small cell carcinoma in 23 patients; median 45 Gy) were performed. Common Terminology Criteria for Adverse Events v.3.0 was used to evaluate RP and the relationship with the percentage of pulmonary volume irradiated to >20 Gy (V20) and PE. PE was diagnosed by the presence of low-attenuation areas (LAAs) on CT scans and was classified into Grades 0-4 according to the extent of the LAAs.

RESULTS

The median follow-up time was 16 months. The 6-month cumulative incidence of RP at Grade 3 or greater was 7.7% and 34.1% in patients with a V20 of <25% and ≥25%, respectively (p=0.017). In patients with PE Grades 0, 1, 2 and 3 or greater, the incidence of RP was 16.5%, 9.1%, 8.6% and 54.0%, respectively. As the PE Grade increased, the incidence of RP also increased significantly.

CONCLUSION

The incidence and severity of RP are significantly higher in patients with a high V20 value as well as in those with severe PE.

Diagnostic value of EBUS-TBNA for lung cancer with non-enlarged lymph nodes: a study in a tuberculosis-endemic country

BACKGROUND

In tuberculosis (TB)-endemic areas, contrast-enhanced computed tomography (CT) and positron emission tomography (PET) findings of lung cancer patients with non-enlarged lymph nodes are frequently discrepant. Endobronchial ultrasound-guided transbronchial aspiration (EBUS-TBNA) enables real-time nodal sampling, and thereby improves nodal diagnosis accuracy. This study aimed to compare the accuracy of nodal diagnosis by using EBUS-TBNA, and PET.

METHODS

We studied 43 lung cancer patients with CT-defined non-enlarged mediastinal and hilar lymph nodes and examined 78 lymph nodes using EBUS-TBNA.

RESULTS

The sensitivity, specificity, positive predictive value, and negative predictive value of EBUS-TBNA were 80.6%, 100%, 100%, and 85.7%, respectively. PET had low specificity (18.9%) and a low positive predictive value (44.4%). The diagnostic accuracy of EBUS-TBNA was higher than that of PET (91% vs. 47.4%; p<0.001). Compared to CT-based nodal assessment, PET yielded a positive diagnostic impact in 36.9% nodes, a negative diagnostic impact in 46.2% nodes, and no diagnostic impact in 16.9% nodes. Patients with lymph nodes showing negative PET diagnostic impact had a high incidence of previous pulmonary TB. Multivariate analysis indicated that detection of hilar nodes on PET was an independent predictor of negative diagnostic impact of PET.

CONCLUSION

In a TB-endemic area with a condition of CT-defined non-enlarged lymph node, the negative diagnostic impact of PET limits its clinical usefulness for nodal staging; therefore, EBUS-TBNA, which facilitates direct diagnosis, is preferred.

Experience of Dual Time Point Brain F-18 FDG PET/CT Imaging in Patients with Infectious Disease

Dual time point FDG PET imaging (DTPI) has been considered helpful for discrimination of benign and malignant disease, and staging lymph node status in patients with pulmonary malignancy. However, DTPI for benign disease has been rarely reported, and it may show a better description of metabolic status and extent of benign infectious disease than early imaging only. The authors report on the use F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) imaging with additional delayed imaging on a 52-year-old man with sparganosis and a 70-year-old man with tuberculous meningitis. To the best of our knowledge, this is the first report on dual time point PET/CT imaging in patients with cerebral sparganosis and tuberculous meningitis.

Impact of incidental irradiation on clinically uninvolved nodal regions in patients with advanced non-small-cell lung cancer treated with involved-field radiation therapy: does incidental irradiation contribute to the low incidence of elective nodal failure?

PURPOSE

To evaluate the incidental irradiation dose to elective nodal regions in the treatment of advanced non-small-cell lung cancer with involved-field radiation therapy (IF-RT) and the pattern of elective nodal failure (ENF).

METHODS AND MATERIALS

Fifty patients with advanced non-small-cell lung cancer, who received IF-RT at Kagawa University were enrolled. To evaluate the dose of incidental irradiation, we delineated nodal regions with a Japanese map and the American Thoracic Society map (levels 1-11) in each patient retrospectively and calculated the dose parameters such as mean dose, D95, and V95 (40 Gy as the prescribed dose of elective nodal irradiation).

RESULTS

Using the Japanese map, the median mean dose was more than 40 Gy in most of the nodal regions, except at levels 1, 3, and 7. In particular, each dosimetric parameter of level 1 was significantly lower than those at other levels, and each dosimetric parameter of levels 10 to 11 ipsilateral (11I) was significantly higher than those in other nodal regions. Using the American Thoracic Society map, basically, the results were similar to those of the Japanese map. ENF was observed in 4 patients (8%), five nodal regions, and no mean dose to the nodal region exceeded 40 Gy. On the Japanese map, each parameter of these five nodal region was significantly lower than those of the other nodal regions.

CONCLUSIONS

These results show that a high dose of incidental irradiation may contribute to the low incidence of ENF in patients who have received IF-RT.

Differential diagnosis between (18)F-FDG-avid metastatic lymph nodes in non-small cell lung cancer and benign nodes on dual-time point PET/CT scan

OBJECTIVE

To clarify the difference of (18)F-FDG uptake kinetics between FDG-avid metastatic lymph nodes (LNs) in patients with non-small-cell lung cancer (NSCLC) and FDG-avid benign LNs associated with various etiologies on dual-time point PET/CT scan, and to determine the optimal parameter for differentiation.

METHODS

The subjects were 134 FDG-avid metastatic LNs in 67 patients with NSCLC and 62 FDG-avid benign LNs in 61 patients with various lung disorders including NSCLC. PET/CT scan was performed at 2 time points (at 60 min and at 120 min) after intravenous injection of 4.4 MBq/kg (18)F-FDG. The maximum standardized uptake value (SUVmax) on early and delayed scans and the percent change of SUVmax (%DeltaSUVmax) were measured at each FDG-avid LN. The optimal parameter for differentiation was determined by the receiver-operating characteristic analysis.

RESULTS

Delayed SUVmax was increased compared with early SUVmax in 114 (85.0%) FDG-avid metastatic LNs and 42 (67.7%) FDG-avid benign LNs, with significant higher delayed SUVmax than early values (7.0 +/- 5.0 vs. 5.9 +/- 3.4; P < 0.0001, and 3.0 +/- 1.3 vs. 2.8 +/- 1.0; P < 0.05, respectively). Early and delayed SUVmax and %DeltaSUVmax in metastatic LNs were significantly higher than those in benign LNs (P < 0.0001). The optimal parameter for the differentiation was the combined use of early SUVmax > 3.0 or delayed SUVmax > 4.0, yielding sensitivity of 88.8%, specificity of 80.6%, accuracy of 86.2%, negative predictive value of 76.9%, and positive predictive value of 90.6%. It provided better results than the use of early SUVmax > 3.0 alone (P = 0.019) or the optimal parameter for %DeltaSUVmax (>5%) (P = 0.012). However, 12 (19.3%) benign LNs were indistinguishable from metastatic LNs.

CONCLUSIONS

Although dual-time point PET/CT scan enhances the difference of FDG uptake between FDG-avid metastatic and benign LNs and improves the differentiation when compared with a single scan, biopsy procedure may be still required for accurate assessment of LN status in patients with NSCLC and possible etiologies showing intensive FDG uptake in benign LNs.

Dual-time point PET/CT with F-18 FDG for the differentiation of malignant and benign bone lesions

PURPOSE

The purpose of the present study was to evaluate whether 2-fluoro[fluorine-18]-2-deoxy-D: -glucose (F-18 FDG) positron emission tomography (PET) could differentiate malignant and benign bone lesions and whether obtaining delayed F-18 FDG PET images could improve the accuracy of the technique.

METHODS

In a prospective study, 67 patients with bone lesions detected by computed tomography (CT) or magnetic resonance imaging were included. Whole body PET/CT imaging was performed at 1 h (early) after the F-18 FDG injection and delayed imaging at 2 h post injection was performed only in the abnormal region. Semiquantitative analysis was performed using maximum standardized uptake value (SUV(max)), obtained from early and delayed images (SUV(maxE) and SUV(maxD), respectively). The retention index (RI) was calculated according to the equation: RI = (SUV(maxD) - SUV(maxE)) x 100/SUV(maxE.) Histopathology of surgical specimens and follow-up data were used as reference criteria. The SUV(maxE) and RI were compared between benign and malignant lesions.

RESULTS

The final diagnoses revealed 53 malignant bone lesions in 37 patients and 45 benign lesions in 30 patients. There were statistically significant differences in the SUV(maxE) between the malignant and benign lesions (P = 0.03). The mean SUV(maxE) was 6.8 +/- 4.7 for malignant lesions and 4.5 +/- 3.3 for benign lesions. However, a considerable overlap in the SUV(maxE) was observed between some benign and malignant tumors. With a cutoff value of 2.5 for the SUV(maxE), the sensitivity, specificity, and accuracy were 96.0%, 44.0%, and 72.4%, respectively. The positive predictive value (PPV) and negative predictive value (NPV) were 67.1% and 90.9%, respectively. There were significant differences in the RI between the malignant and benign lesions (P = 0.004). But there was overlap between the two groups. The mean RI was 7 +/- 11 for the benign lesions and 18 +/- 11 for the malignant lesions. When an RI of 10 was used as the cutoff point, the sensitivity, specificity, and accuracy were 90.6%, 76.0%, and 83.7.0%, respectively. The PPV and NPV were 81.4% and 87.1%, respectively.

CONCLUSIONS

The results of this study indicate that dual-time point F-18 FDG PET may provide more help in the differentiation of malignant tumors from benign ones.