Localized form of bronchioloalveolar carcinoma: FDG PET findings

[18F]FDG PET/CT is useful in discriminating invasive adenocarcinomas among pure ground-glass nodules: comparison with CT findings-a bicenter retrospective study

PURPOSE

Predicting the malignancy of pure ground-glass nodules (GGNs) using CT is challenging. The optimal role of [18F]FDG PET/CT in this context has not been clarified. We compared the performance of [18F]FDG PET/CT in evaluating GGNs for predicting invasive adenocarcinomas (IACs) with CT.

METHODS

From June 2012 to December 2020, we retrospectively enrolled patients with pure GGNs on CT who underwent [18F]FDG PET/CT within 90 days. Overall, 38 patients with 40 ≥ 1-cm GGNs were pathologically confirmed. CT images were analyzed for size, attenuation, uniformity, shape, margin, tumor-lung interface, and internal/surrounding characteristics. Visual [18F]FDG positivity, maximum standardized uptake value (SUVmax), and tissue fraction-corrected SUVmax (SUVmaxTF) were evaluated on PET/CT.

RESULTS

The histopathology of the 40 GGNs were: 25 IACs (62.5%), 9 minimally invasive adenocarcinomas (MIA, 22.5%), and 6 adenocarcinomas in situ (AIS, 15.0%). No significant differences were found in CT findings according to histopathology, whereas visual [18F]FDG positivity, SUVmax, and SUVmaxTF were significantly different (P=0.001, 0.033, and 0.018, respectively). The size, visual [18F]FDG positivity, SUVmax, and SUVmaxTF showed significant diagnostic performance to predict IACs (area under the curve=0.693, 0.773, 0.717, and 0.723, respectively; P=0.029, 0.001, 0.018, and 0.013, respectively). In the multivariate logistic regression analysis, visual [18F]FDG positivity discriminated IACs among GGNs among various CT and PET findings (P=0.008).

CONCLUSIONS

[18F]FDG PET/CT demonstrated superior diagnostic performance compared to CT in differentiating IAC from AIS/MIA among pure GGNs, thus it has the potential to guide the proper management of patients with pure GGNs.

Radio-Guided Lung Surgery: A Feasible Approach for a Cancer Precision Medicine

BACKGROUND

Radio-guided surgery is a reliable approach used for localizing ground-glass opacities, lung nodules, and metastatic lymph nodes. Lung nodules, lymph node metastatic involvement, and ground-glass opacities often represent a challenge for surgical management and clinical work-up.

METHODS

PubMed research was conducted from January 1997 to June 2023 using the keywords "radioguided surgery and lung cancer".

RESULTS

Different studies were conducted with different tracers: technetium-99m-albumin macroaggregates, cyanoacrylate combined to technetium-99m-sulfur colloid, indium-111-pentetreotide, and fluorine-18-deoxyglucose. A study proposed naphthalocyanine radio-labeled with copper-64. Radio-guided surgery has been demonstrated to be a reliable approach in localizing a lesion, and has a low radiological burden for personnel exposure and low morbidity. The lack of necessity to conduct radio-guided surgery under fluoroscopy or echography makes this radio-guided surgery an easy way of performing precise surgical procedures.

CONCLUSIONS

Radio-guided surgery is a feasible approach useful for the intraoperative localization of ground-glass opacities, lung nodules, and metastatic lymph nodes. It is a valid alternative to the existing approaches due to its low cost, associated low morbidity, the possibility to perform the procedure after several hours, the low radiation dose applied, and the small amount of time that is required to perform it.

Cocaine-induced pulmonary complications: A diagnosis of waiting and watching

Pulmonary complications of cocaine among users are common. Manifestations include lung congestion, intra-alveolar edema, and diffuse alveolar hemorrhage (DAH). Direct cellular toxicity, eosinophilia, barotrauma, and vasoactive effects of cocaine are believed to induce DAH. We present a rare case of cocaine-associated focal alveolar hemorrhage mimicking malignancy on imaging. Initially contemplated biopsy was avoided based on rapid growth of concerning lung lesion, with subsequent near resolution on follow-up. This case illustrates the importance of epidemiologic and temporal multimodality correlation when evaluating indeterminate lung lesions.

FDG-PET/CT imaging findings of hepatic tumors and tumor-like lesions based on molecular background

The usefulness of whole-body 18-fluoro-2-deoxyglucose (FDG)-fluorodeoxyglucose positron emission (PET)/computed tomography (CT) is established for assessment of disease staging, detection of early disease recurrence, therapeutic evaluation, and predicting prognosis in various malignancies; and for evaluating the spread of inflammation. However, the role of FDG-PET/CT for the liver is limited because CT and magnetic resonance imaging (MRI) can provide an accurate diagnosis of most tumors. In addition, in other potentially useful roles there are several pitfalls in the interpretation of FDG uptake in PET/CT imaging. Accurate evaluation demands knowledge of the FDG uptake of each lesion, including potential negative and positive uptakes, and requires an understanding of the underlying background of the molecular mechanisms. The degree of FDG uptake is dependent on cellular metabolic rate and the expression of glucose transporter, hexokinase, and glucose-6-phosphatase, which in turn are closely affected by biological characteristics such as pathological category (e.g., adenocarcinoma, squamous cell carcinoma, small cell cancer, transitional cell cancer, neuroendocrine tumor, sarcoma, lymphoma), tumor differentiation, histological behavior (e.g., solid, cystic, mucinous), and intratumoral alterations (e.g., necrosis, degeneration, hemorrhage). Correlation with the CT and MRI findings, which also precisely depict the pathological findings, is important to avoid misdiagnosis.

Solitary Pulmonary Nodule: Morphological Effects on Metabolic Activity Assessment

Objectives

We aimed to evaluate the effects of morphological characteristics of the solitary pulmonary nodules (SPN) on metabolic activity assessment. To the best of our knowledge, this is the first study to compare the volumetric metabolic activity parameters according to the morphologic parameters of the nodules.

Methods

In this retrospective study, ¹⁸F-FDG positron emission tomography and computed tomography scans performed between 2011 and 2018 were evaluated by a nuclear and diagnostic radiologist. One hundred thirteen patients with SPNs with biopsy-proven diagnosis were included. SPNs were classified as solid, partially solid (PS), and ground glass opacity (GGO).

Results

SPN diameter, SUV_max, metabolic tumor volume (MTV), total lesion glycolysis (TLG), and density were significantly higher in the malignant group. SUV_max, MTV, TLG increased in direct proportion to the diameter. There was no a significant difference between GGO, PS, and solid nodules in terms of SUV_max values. MTV and TLG values increased in parallel with the density of the nodules, but this increase was only significant in the malignant group. There was a significant difference between SPNs <2 cm and SPNs ≥2 cm in terms of MTV, while there was no difference in terms of SUV_max. The cut-off value determined by the ROC curve was found to be 4.39 for SUV_max, 7.33 mL for MTV and 31.88 g for TLG. The cut-off values for SUV_max of solid and subsolid nodules were close to each other, but cut-off values for MTV and TLG were higher in solid nodules.

Conclusion

SUV_max, MTV, and TLG are affected by diameter and attenuation. We suggest using different MTV and TLG cut-off values for solid and subsolid nodules, but we suggest using same SUV_max values. MTV can be a more reliable parameter than SUV_max in prediction of malignancy in smaller nodules.

Can the Efficacy of [18F]FDG-PET/CT in Clinical Oncology Be Enhanced by Screening Biomolecular Profiles?

Positron Emission Tomography (PET) is a functional imaging modality widely used in clinical oncology. Over the years the sensitivity and specificity of PET has improved with the advent of specific radiotracers, increased technical accuracy of PET scanners and incremental experience of Radiologists. However, significant limitations exist—most notably false positives and false negatives. Additionally, the accuracy of PET varies between cancer types and in some cancers, is no longer considered a standard imaging modality. This review considers the relative influence of macroscopic tumour features such as size and morphology on 2-Deoxy-2-[¹⁸F]fluoroglucose ([¹⁸F]FDG) uptake by tumours which, though well described in the literature, lacks a comprehensive assessment of biomolecular features which may influence [¹⁸F]FDG uptake. The review aims to discuss the potential influence of individual molecular markers of glucose transport, glycolysis, hypoxia and angiogenesis in addition to the relationships between these key cellular processes and their influence on [¹⁸F]FDG uptake. Finally, the potential role for biomolecular profiling of individual tumours to predict positivity on PET imaging is discussed to enhance accuracy and clinical utility.

Nuclear Imaging Study of the Pharmacodynamic Effects of Debio 1143, an Antagonist of Multiple Inhibitor of Apoptosis Proteins (IAPs), in a Triple-Negative Breast Cancer Model

Background

Debio 1143, a potent orally available SMAC mimetic, targets inhibitors of apoptosis proteins (IAPs) members and is currently in clinical trials. In this study, nuclear imaging evaluated the effects of Debio 1143 on tumor cell death and metabolism in a triple-negative breast cancer (TNBC) cell line (MDA-MB-231)-based animal model.

Methods

Apoptosis induced by Debio 1143 was assessed by FACS (caspase-3, annexin 5 (A5)), binding of ^99mTc-HYNIC-Annexin V, and a cell proliferation assay. ^99mTc-HYNIC-Annexin V SPECT and [¹⁸F]-FDG PET were also performed in mice xenografted with MDA-MB-231 cells.

Results

Debio 1143 induced early apoptosis both in vitro and in vivo 6 h after treatment. Debio 1143 inhibited tumor growth, which was associated with a decreased tumor [¹⁸F]-FDG uptake when measured during treatment.

Conclusions

This imaging study combining SPECT and PET showed the early proapoptotic effects of Debio 1143 resulting in a robust antitumor activity in a preclinical TNBC model. These imaging biomarkers represent valuable noninvasive tools for translational and clinical research in TNBC.

The maximum standardized uptake value of preoperative positron emission tomography/computed tomography in lung adenocarcinoma with a ground-glass opacity component of less than 30 mm

BACKGROUND AND OBJECTIVES

This study evaluated the relationship between the maximum standardized uptake value (SUVmax) of preoperative positron emission tomography/computed tomography (PET/CT) and the characteristics of lung adenocarcinoma featuring ground-glass opacity nodules (GGN).

METHODS

The association of the SUVmax of preoperative PET/CT with ground-glass opacity (GGO) proportion on CT, subtypes of adenocarcinoma (minimally invasive adenocarcinoma, invasive adenocarcinoma), predominant types of invasive adenocarcinoma, and size of the total and invasive components of pathology were evaluated in 190 patients who underwent resection for lung adenocarcinoma featuring GGN.

RESULTS

The mean SUVmax of non-solid GGN and partly solid GGN were 0.53 and 1.32, respectively (P = 0.029). The mean SUVmax of the main masses in 38 patients with MIA and 152 with invasive adenocarcinoma were 0.86 and 1.36, respectively (P = 0.029). The mean SUVmax of acinar, lepidic, papillary, and solid tumors were 1.61, 0.87, 0.98, and 1.60, respectively. The mean SUVmax of invasive components measuring ≤10 mm, 11-20 mm, and >20 mm were 0.84, 1.66, and 2.09, respectively (P < 0.001).

CONCLUSIONS

The SUVmax of lung adenocarcinoma featuring GGN can vary depending on the GGO proportion. A higher SUVmax can be expected in invasive adenocarcinoma than in MIA, and solid and acinar-predominant invasive adenocarcinoma showed a higher SUVmax.

Clinical PET-MR Imaging in Breast Cancer and Lung Cancer

Hybrid imaging systems have dramatically improved thoracic oncology patient care over the past 2 decades. PET-MR imaging systems have the potential to further improve imaging of thoracic neoplasms, resulting in diagnostic and therapeutic advantages compared with current MR imaging and PET-computed tomography systems. Increasing soft tissue contrast and lesion sensitivity, improved image registration, reduced radiation exposure, and improved patient convenience are immediate clinical advantages. Multiparametric quantitative imaging capabilities of PET-MR imaging have the potential to improve understanding of the molecular mechanisms of cancer and treatment effects, potentially guiding improvements in diagnosis and therapy.

Challenges in Interpretation of Staging PET/CT in Thoracic Malignancies

¹⁸F-fluorodeoxryglucose (¹⁸F-FDG) PET/CT imaging is routinely performed in the evaluation of patients with known or suspected thoracic malignancy. Indications for its use include staging of malignancy, assessment of response to therapy, evaluation of suspected disease recurrence, and evaluation of a solitary pulmonary nodule. In this article, we will discuss specific technical artifacts and also review potential pitfalls in the interpretation of PET/CT in thoracic malignancies including normal variations in physiologic uptake of FDG, benign conditions (such as infection, inflammation, posttreatment changes, and iatrogenic factors) that can result in increased FDG uptake, and malignancies that demonstrate scarce to no FDG uptake.

Primary tumour standardised uptake value is prognostic in nonsmall cell lung cancer: a multivariate pooled analysis of individual data

(18)F-fluoro-2-deoxy-d-glucose positron emission tomography (PET) complements conventional imaging for diagnosing and staging lung cancer. Two literature-based meta-analyses suggest that maximum standardised uptake value (SUVmax) on PET has univariate prognostic value in nonsmall cell lung cancer (NSCLC). We analysed individual data pooled from 12 studies to assess the independent prognostic value of binary SUVmax for overall survival.After searching the published literature and identifying unpublished data, study coordinators were contacted and requested to provide data on individual patients. Cox regression models stratified for study were used.Data were collected for 1526 patients (median age 64 years, 60% male, 34% squamous cell carcinoma, 47% adenocarcinoma, 58% stage I-II). The combined univariate hazard ratio for SUVmax was 1.43 (95% CI 1.22-1.66) and nearly identical if the SUV threshold was calculated stratifying for histology. Multivariate analysis of patients with stage I-III disease identified age, stage, tumour size and receipt of surgery as independent prognostic factors; adding SUV (HR 1.58, 95% CI 1.27-1.96) improved the model significantly. The only detected interaction was between SUV and stage IV disease.SUV seems to have independent prognostic value in stage I-III NSCLC, for squamous cell carcinoma and for adenocarcinoma.

Perceived misinterpretation rates in oncologic 18F-FDG PET/CT studies: a survey of referring physicians

Because only pathologic examination can confirm the presence or absence of malignant disease in cancer patients, a certain rate of misinterpretation in any kind of imaging study is inevitable. For the accuracy of interpretation to be improved, determination of the nature, causes, and magnitude of this problem is needed. This study was designed to collect pertinent information from physicians referring patients for oncologic (18)F-FDG PET/CT.

METHODS

A total of 662 referring physicians completed an 11-question survey focused on their experience with the interpretation of oncologic (18)F-FDG PET/CT studies. The participants were oncologists (36.1%; n = 239), hematologists (14.5%; n = 96), radiation oncologists (7.4%; n = 49), surgeons (33.8%; n = 224), and other physicians (8.2%; n = 54). Questions were aimed at determining the frequency, nature, and causes of scan misinterpretations as well as potential solutions to reduce the frequency of misinterpretations.

RESULTS

Perceived misinterpretation rates ranged from 5% to 20%, according to most (59.3%) of the participants; 20.8% of respondents reported rates of less than 5%. Overinterpretation rather than underinterpretation was more frequently encountered (68.9% vs. 8.7%, respectively). Limited availability of a patient's history and limited experience of interpreters were the major contributors to this phenomenon, according to 46.8% and 26.7% of the participants, respectively. The actions most commonly suggested to reduce misinterpretation rates (multiple suggestions were possible) were the institution of multidisciplinary meetings (59.8%), the provision of adequate history when ordering an examination (37.4%), and a discussion with imaging specialists when receiving the results of the examination (38.4%).

CONCLUSION

Overinterpretation rather than underinterpretation of oncologic (18)F-FDG PET/CT studies prevails in clinical practice, according to referring physicians. Closer collaboration of imaging specialists with referring physicians through more multidisciplinary meetings, improved communication, and targeted training of interpreting physicians are actions suggested to reduce the rates of misinterpretation of oncologic (18)F-FDG PET/CT studies.

Positron emission tomography/computerized tomography in lung cancer

Positron emission tomography (PET) using 2-(18F)-flouro-2-deoxy-D-glucose (FDG) has emerged as a useful tool in the clinical work-up of lung cancer. This review article provides an overview of applications of PET in diagnosis, staging, treatment response evaluation, radiotherapy planning, recurrence assessment and prognostication of lung cancer.

Risk factors of postoperative recurrences in patients with clinical stage I NSCLC

Background

Despite advances in radiation therapy, chemotherapy, and newly developed molecular targeting therapies, long-term survival after resection for patients with NSCLC remains less than 50%. We investigated factors predicting postoperative locoregional recurrences and distant metastases in patients with clinical stage I non-small-cell lung cancer (NSCLC) after surgical resection.

Methods

All patients with clinical stage I NSCLC, who underwent surgical resection between January 2002 and June 2006, were reviewed retrospectively. Multiple logistic regression analyses were used to identify independent risk factors for patients with locoregional recurrences and distant metastases.

Results

A total of 261 patients were eligible. Overall survival was significant related to locoregional recurrences (P = 0.03) and distant metastases (P <0.001). There were significant differences of locoregional recurrence in tumor differentiation (P = 0.032) and advanced pathological stage (P = 0.002). In the group of distant metastases, there were significant differences in tumor differentiation (P = 0.035), lymphovascular space invasion (P = 0.031). Among the relationship between pattern of distant metastasis and clinicopathologic variables in patients with clinical stage I NSCLC, SUVmax (P = 0.02) and tumor size (P = 0.001) had significant differences. According to multiple logistic regression analysis, tumor differentiation is the only risk factor of postoperative outcome for locoregional recurrence and serum CEA (>3.5 ng/mL) is the predictor of distant metastasis.

Conclusions

Tumor differentiation and serum CEA were predictors of postoperative relapse for clinical stage I NSCLC after surgical resection. Risk factors of postoperative recurrence in patients with clinical stage I NSCLC may enable us to optimize the patient selection for postoperative adjuvant therapies or neoadjuvant treatment before surgery.

Positron emission tomography: clinical applications in oncology. Part 1

Positron emission tomography is a functional diagnostic imaging technique, which can accurately measure in vivo distribution of a radiopharmaceutical with high resolution. The ability of positron emission tomography to study various biologic processes opens up new possibilities for both research and day-to-day clinical use. Positron emission tomography has progressed rapidly from being a research technique in laboratories to a routine clinical imaging modality becoming part of armamentarium for the medical profession. The most widely used radiotracer in positron emission tomography is 18F-fluoro-2-deoxy-D-glucose (FDG), which is an analog of glucose. FDG uptake in cells is directly proportional to glucose metabolism of cells. Since glucose metabolism is increased many fold in malignant tumors, positron emission tomography has a high sensitivity and high negative predictive value. Positron emission tomography with FDG is now the standard of care in initial staging, monitoring the response to therapy and management of lung cancer, colorectal cancer, lymphoma, melanoma, esophageal cancer, head and neck cancer and breast cancer. The aim of this article is to review the clinical applications of positron emission tomography in oncology.

The maximum standardized FDG uptake on PET-CT in patients with non-small cell lung cancer

Background

Non-small cell lung cancer (NSCLC) accounts for approximately 80% of new diagnoses of pulmonary carcinoma. This study investigated the correlation between 18 F-fluorodeoxyglucose uptake in computerized tomography integrated positron emission tomography and tumor size, lymph node metastasis, and distant metastasis in patients with NSCLC.

Methods

The records of 151 NSCLC patients (139 male, 12 female; mean age 59.60 years) were evaluated retrospectively.

Results

Forty-one cases were adenocarcinomas; 45 squamous cell carcinomas; and 65 unspecified NSCLC. When the cases were categorized according to tumor size (group 1, ≤ 3 cm; group 2, > 3 and ≤ 5 cm; group 3, > 5 cm), the maximum standardized uptake value (SUVmax) was significantly lower in groups 1 and 2 compared with group 3 (p = 0.006 for each). Considering all cases, tumor SUVmax was not correlated with age, gender, or histopathological type. Lymph node metastases were pathologically proven in 24 cases: 24% of these were adenocarcinomas, 6% squamous cell carcinomas, and 16% unspecified NSCLC. Neither lymph node involvement nor distant metastases were correlated with tumor SUVmax, although lymph node size was positively correlated with lymph node SUVmax (r = 0.775; p < 0.001).

Conclusions

SUVmax was significantly associated with tumor size, but not with distant metastases or lymph node involvement. Therefore, SUVmax on positron emission tomography is not predictive of the presence of metastases.

Methods for staging non-small cell lung cancer: Diagnosis and management of lung cancer, 3rd ed: American College of Chest Physicians evidence-based clinical practice guidelines

BACKGROUND

Correctly staging lung cancer is important because the treatment options and prognosis differ significantly by stage. Several noninvasive imaging studies and invasive tests are available. Understanding the accuracy, advantages, and disadvantages of the available methods for staging non-small cell lung cancer is critical to decision-making.

METHODS

Test accuracies for the available staging studies were updated from the second iteration of the American College of Chest Physicians Lung Cancer Guidelines. Systematic searches of the MEDLINE database were performed up to June 2012 with the inclusion of selected meta-analyses, practice guidelines, and reviews. Study designs and results are summarized in evidence tables.

RESULTS

The sensitivity and specificity of CT scanning for identifying mediastinal lymph node metastasis were approximately 55% and 81%, respectively, confirming that CT scanning has limited ability either to rule in or exclude mediastinal metastasis. For PET scanning, estimates of sensitivity and specificity for identifying mediastinal metastasis were approximately 77% and 86%, respectively. These findings demonstrate that PET scanning is more accurate than CT scanning, but tissue biopsy is still required to confirm PET scan findings. The needle techniques endobronchial ultrasound-needle aspiration, endoscopic ultrasound-needle aspiration, and combined endobronchial ultrasound/endoscopic ultrasound-needle aspiration have sensitivities of approximately 89%, 89%, and 91%, respectively. In direct comparison with surgical staging, needle techniques have emerged as the best first diagnostic tools to obtain tissue. Based on randomized controlled trials, PET or PET-CT scanning is recommended for staging and to detect unsuspected metastatic disease and avoid noncurative resections.

CONCLUSIONS

Since the last iteration of the staging guidelines, PET scanning has assumed a more prominent role both in its use prior to surgery and when evaluating for metastatic disease. Minimally invasive needle techniques to stage the mediastinum have become increasingly accepted and are the tests of first choice to confirm mediastinal disease in accessible lymph node stations. If negative, these needle techniques should be followed by surgical biopsy. All abnormal scans should be confirmed by tissue biopsy (by whatever method is available) to ensure accurate staging. Evidence suggests that more complete staging improves patient outcomes.

Clinical importance of [18F]fluorodeoxyglucose positron emission tomography/computed tomography in the management of patients with bronchoalveolar carcinoma: Role in the detection of recurrence

[¹⁸F]fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) has been reported to have a low sensitivity in the initial diagnosis of bronchoalveolar carcinoma (BAC) due to BAC’s low metabolic activity. The aim of this study was to assess the value of [¹⁸F]FDG-PET/CT in the detection of BAC recurrence. Between February 2007 and September 2011, the [¹⁸F]FDG-PET/CT scans that were performed on patients with known, histologically proven BAC were studied. A total of 24 [¹⁸F]FDG-PET/CT scans were performed in 22 patients, including 16 males and 6 females, with a mean age of 65±9 years. Among the scans, 15 were performed to assess for possible recurrence with equivocal findings in conventional imaging methods and 9 for restaging post-therapy. In all cases conventional imaging studies (CT and MRI) were performed 5–30 days prior to PET/CT. Among the 24 [¹⁸F]FDG-PET/CT scans, 18 were positive and 6 negative. Among the 15 [¹⁸F]FDG-PET/CT scans performed for suspected recurrence, 34 lesions were detected and the mean maximum standardized uptake value (SUVmax) was 6.8±3.26. In nine scans, upstaging was observed, while two were in agreement with the findings of the conventional modalities. A greater number of lesions were detected in two scans and fewer lesions were detected in one, with no change in staging. Only one scan was negative. By contrast, in patients examined for restaging, there were only five lesions with a mean SUVmax of 4.86±3.18. Agreement between the findings of [¹⁸F]FDG-PET/CT and the conventional modalities was observed in 8 out of 9 cases. Although [¹⁸F]FDG-PET/CT has been reported to have a low sensitivity in the initial diagnosis of BAC, the present results indicate that when there is recurrence, the lesions become [¹⁸F]FDG avid. [¹⁸F]FDG-PET/CT may provide further information in patients evaluated for recurrence and thus improve patient management.

Low-dose CT: technique, reading methods and image interpretation

The National Lung Cancer Screening Trial has recently demonstrated that screening of high-risk populations with the use of low-dose computed tomography (LDCT) reduces lung cancer mortality^[1]. Based on this encouraging result, the National Comprehensive Cancer Network guidelines recommended LDCT for selected patients at high risk of lung cancer^[2]. This suggests that an increasing number of CT screening examinations will be performed. The LDCT technique is relatively simple but some CT parameters are important and should be accurately defined in order to achieve good diagnostic quality and minimize the delivered dose. In addition, LDCT examinations are not as easy to read as they may initially appear; different approaches and tools are available for nodule detection and measurement. Moreover, the management of positive results can be a complex process and can differ significantly from routine clinical practice. Therefore this paper deals with the LDCT technique, reading methods and interpretation in lung cancer screening, particularly for those radiologists who have little experience of the technique.

Stereotactic body radiation therapy for the treatment of early-stage minimally invasive adenocarcinoma or adenocarcnioma in situ (formerly bronchioloalveolar carcinoma): a patterns of failure analysis

Introduction

Ongoing prospective trials exploring stereotactic body radiation therapy (SBRT) for early stage non-small cell lung cancer (NSCLC) often exclude minimally invasive adenocarcinoma or adenocarcnioma in situ, formerly bronchioloalveolar carcinoma (BAC), due to concerns for accurate target delineation on CT. We performed a patterns of failure analysis to compare outcomes between BAC and other NSCLC subtypes.

Methods

One hundred twenty patients with early stage NSCLC were treated with SBRT from 2004–2009. Pathologic confirmation of NSCLC was obtained in 97 patients. Radiotherapy was delivered according to RTOG guidelines. The log-rank test was used to compare outcomes between BAC and other NSCLC.

Results

Median follow-up was 29 months. The median SBRT dose was 5400 cGy. Thirteen patients had radiographically diagnosed BAC and five patients had biopsy confirmed BAC, of which two had both. The three-year local control was 100% for biopsy-proven or radiographically diagnosed BAC (n = 18) and 86% for all other NSCLC subtypes (n = 102) (p = 0.13). Likewise, no significant difference was detected between BAC and other NSCLC for 3-year regional failure (12% vs. 20%, p = 0.45), progression-free survival (57.6% vs. 53.5%, p = 0.84) or overall survival (35% vs. 47%, p = 0.66). There was a trend towards lower three-year rates of freedom from distant failure in patients with any diagnosis of BAC compared to those without (26% vs. 38%, p = 0.053).

Conclusions

Compared to other NSCLC subtypes, BAC appears to have similar patterns of failure and survival after treatment with SBRT, however there may be an increased risk of distant metastases with BAC. RTOG guideline-based target delineation provides encouraging local control rates for patients with BAC.

Imaging features of colorectal liver metastasis in FDG PET-CT: a retrospective correlative analysis between CT attenuation and FDG uptake

OBJECTIVES

Increasing scientific evidence supports the use of fluorodeoxyglucose positron emission tomography/ computed tomography (FDG-PET/CT) in the staging of colorectal carcinoma. A detailed and accurate characterization of tumor biology and imaging characteristics is therefore of paramount importance. The aim of our study was to determine whether CT attenuation, in Hounsfield units, was correlated with FDG uptake in colorectal liver metastasis.

METHODS

The clinical and imaging data of patients from our institution with histologically proven colorectal carcinoma who were referred for PET/CT staging were reviewed. For the purpose of our study, we included only those patients who had undergone dual-time-point imaging. A total of 20 patients with 62 hepatic secondaries were identified. The perlesional CT attenuation (in Hounsfield units), FDG uptake (in standardized uptake values SUV 60 and SUV 120), and size (in cm) were determined. Correlation analysis using the Spearman rank correlation coefficient was carried out.

RESULTS

A statistically significant positive relationship was observed between perlesional CT attenuation and SUV 60 (r=0.433, P=0.0004). A similar significant positive relationship was shown between perlesional CT attenuation and SUV 120 (r=0.414, P=0.0008).

CONCLUSION

Our study suggested that, in colorectal liver metastasis, FDG uptake was positively correlated with CT attenuation. If a lesion appeared to be indeterminate because of apparently low FDG avidity, internal content must be taken into consideration to minimize misdiagnosis and false negatives. We proposed that such a relationship may be due to the mucinous contents of colorectal liver metastasis or degree of tumor necrosis. Further research, particularly on quantification of the extent of mucin production and tumor necrosis, may allow a more precise relationship to be drawn between CT attenuation and FDG uptake.

Stereotactic body radiotherapy (SBRT) for solitary pulmonary nodules clinically diagnosed as lung cancer with no pathological confirmation: comparison with non-small-cell lung cancer

INTRODUCTION

In non-surgical candidates with solitary pulmonary nodules (SPNs) and no histological confirmation, optimal management remains uncertain.

METHODS

Between February 2005 and February 2011 we treated 298 lung cancers with stereotactic body radiotherapy (SBRT), including SPNs clinically diagnosed as lung cancer (CDLC). Among them, we extracted patients treated with a total dose of 40-50 Gy per 5 fractions and followed up more than 6 months. Patients who had a history of previously treated lung cancer, or were diagnosed pathologically, or suspected as having small-cell lung cancer or large cell neuroendcrine cancer were excluded from this study. The remaining patients were divided into two groups; CDLC and non-small-cell lung cancer (NSCLC) patients and their outcomes were assessed and compared.

RESULTS

Fifty-eight CDLC and 115 NSCLC patients were included in this study. The proportions of female and inoperable cases were significantly higher in the CDLC group. Other characteristics, including T stage and standard uptake value, were well balanced. Median follow-up durations were 20.2 (range, 6.0-58.8) and 21.2 (range, 6-63.7) months, respectively. The 3-year local control, regional-free, metastasis-free, progression-free, cause-specific survival, and overall survival rates were 80% and 87% (p = 0.73), 88% and 91% (p = 0.72), 70% and 74% (p = 0.57), 64% and 67% (p = 0.45), 74% and 71% (p = 0.17), 54% and 57% (p = 0.48), respectively.

CONCLUSION

These results indicate that the treatment outcome of CDLC group was almost identical to that of NSCLC and that few benign lesions seemed to be included. We advocate that SBRT can be legitimately applied to CDLC, provided that they are carefully diagnosed by integrating various clinical findings.

Histological subtypes of lung adenocarcinoma have differential ¹⁸F-fluorodeoxyglucose uptakes on the positron emission tomography/computed tomography scan

INTRODUCTION

Previous studies have shown that lung squamous cell carcinoma has higher ¹⁸F-fluorodeoxyglucose (FDG) uptake on positron emission tomography (PET) than adenocarcinoma. We hypothesized that histological subtypes of lung adenocarcinoma were also different in ¹⁸F-FDG uptake.

METHODS

Patients who had preoperative PET/computed tomography (CT) scan and had undergone complete resection for lung adenocarcinoma between April 2007 and December 2009 were enrolled in this study. Because of the limitation of spatial resolution on PET/CT, tumors less than 1 cm were excluded for analysis. Two independent classification systems were used to categorize histological subtypes of adenocarcinoma; one was modified from the current World Health Organization classification and the other used the morphological features of the terminal respiratory unit (TRU). The maximal standardized uptake value (SUVmax) on PET/CT and the glucose transporter type 1 (GLUT-1) expression of the tumors were measured and correlated to the histology of lung adenocarcinoma.

RESULTS

One hundred fifty-two patients with 153 primary lung adenocarcinomas were included. There was a significant difference in SUVmax among different histological subtypes. Namely, solid predominant adenocarcinomas had significantly higher SUVmax than those with other predominant histology (p < 0.001), and TRU-type adenocarcinomas had significantly lower SUVmax than non-TRU-type adenocarcinomas (p < 0.001). Consistently, GLUT-1 expression was higher in tumors with a solid growth pattern than those without (p < 0.001) and in tumors with non-TRU type than TRU type (p < 0.001).

CONCLUSIONS

The histological subtypes of lung adenocarcinomas differ in GLUT-1 expression and ¹⁸F-FDG uptake on the PET/CT scan, suggesting that histological subtyping not only has morphological but also biological implications.

Standard uptake value of positron emission tomography in clinical stage I lung cancer: clinical application and pathological correlation

OBJECTIVES

The aim of this study was to assess the standard uptake value in clinical stage I non-small cell lung cancer (NSCLC) and its correlation with pathological status and prognosis.

METHODS

We retrospectively reviewed 674 patients diagnosed with NSCLC between January 2002 and June 2005. Patients with clinical stage I diseases undergone a preoperative positron emission tomography-computed tomography scan followed by anatomic resection. We reviewed the clinical features of 152 patients with an average follow-up of 87 months.

RESULTS

We analysed the clinical features of 108 patients with stage I NSCLC and 44 patients with non-stage I NSCLC. There were no statistical differences in age, histological type, location or tumour differentiation between the two groups. In the Stage I group, the patients had lower maximum standard uptake value (SUVmax; 3.80 ± 3.17 vs 5.73 ± 3.65, P = 0.001), lower carcinoembryonic antigen (CEA) levels (2.86 ± 4.80 vs 9.11 ± 17.21 ng/ml, P = 0.027) and smaller tumour size (2.39 ± 0.98 vs 3.73 ± 2.04 cm, P < 0.001). The patients with higher SUVmax had a more advanced pathological stage, poorer tumour differentiation and larger tumour size. A higher SUVmax was an independent factor predicting an advanced pathological stage (SUVmax ≥ 3.3, odds ratio 3.246). The median survival of patients with SUVmax ≥ 3.3 and SUVmax <3.3 were 64.32 and 53.08 months, respectively (P = 0.654).

CONCLUSIONS

Higher preoperative 18-fluorodeoxyglucose uptake by a tumour was significantly associated with an advanced pathological stage but not correlated with a poorer prognosis. An aggressive preoperative work-up for occult N2 disease should be emphasized, avoiding inappropriate thoracotomy.

Causes and imaging features of false positives and false negatives on F-PET/CT in oncologic imaging

BACKGROUND: 18F-FDG is a glucose analogue that is taken up by a wide range of malignancies. 18F-FDG PET-CT is now firmly established as an accurate method for the staging and restaging of various cancers. However, 18F-FDG also accumulates in normal tissue and other non-malignant conditions, and some malignancies do not take up F18-FDG or have a low affinity for the tracer, leading to false-positive and false-negative interpretations. METHODS: PET-CT allows for the correlation of two separate imaging modalities, combining both morphological and metabolic information. We should use the CT to help interpret the PET findings. In this article we will highlight specific false-negative and false-positive findings that one should be aware of when interpreting oncology scans. RESULTS: We aim to highlight post-treatment conditions that are encountered routinely on restaging scans that can lead to false-positive interpretations. We will emphasise the importance of using the CT component to help recognise these entities to allow improved diagnostic accuracy. CONCLUSION: In light of the increased use of PET-CT, it is important that nuclear medicine physicians and radiologists be aware of these conditions and correlate the PET and CT components to avoid misdiagnosis, over staging of disease and unnecessary biopsies.

Ground-glass nodules on chest CT as imaging biomarkers in the management of lung adenocarcinoma

OBJECTIVE

The purpose of this article is to review the clinical significance of ground-glass nodules (GGNs) in the management of lung adenocarcinoma.

CONCLUSION

GGNs can serve as imaging biomarkers that represent the bronchioloalveolar carcinoma component in adenocarcinoma on histology and indicate a better prognosis in patients with lung adenocarcinoma. The evolution of GGNs reflects the multistep progression of adenocarcinoma. Despite the high probability of malignancy of GGNs, the possibility of overdiagnosis should be considered in the management of GGNs.

The utility of the nonattenuation corrected 18F-FDG PET images in the characterization of solitary pulmonary lesions

OBJECTIVE

To determine the accuracy of nonattenuation corrected (NAC) F-fluorodeoxyglucose positron emission tomography (F-FDG PET) images in the evaluation of solitary pulmonary lesion as compared with more established methods.

METHODS

Fifty-six patients received F-FDG PET/CT for diagnosing solitary pulmonary nodules or mass lesions based on histopathology (n=39) and clinical follow-up (n=17). Visual pulmonary lesion FDG uptake was graded by consensus of two nuclear medicine physicians on both attenuation corrected (AC) [absent, less than mediastinal blood pool (MBP), equal to MBP, greater than MBP] and NAC (absent, less than skin, equal to skin, greater than skin) images. Standardized uptake values (SUV) were also measured from AC images. SUV, visual AC, and visual NAC methods' diagnostic performances were compared, distinguishing benign from malignant pulmonary nodules.

RESULTS

There were 34 malignant and 22 benign lesions. Lesion diameter varied from 5 to 100 mm (mean ± SD, 24.0 ± 17.9 mm). The NAC, AC, and SUV method sensitivities and specificities were 100/64%, 91/59%, and 79/77%, respectively. For lesions less than 3 cm, NAC, AC, and SUV methods yielded accuracies of 85%, 78%, and 73%, respectively. The NAC method was the most sensitive and accurate especially for small nodules.

CONCLUSION

Visual assessment of NAC F-FDG PET images alone may provide a more accurate characterization of solitary pulmonary lesions.

Quantitative assessment of diffusion-weighted MR imaging in patients with primary rectal cancer: correlation with FDG-PET/CT

PURPOSE

The aim of the study was to assess correlations between parameters on diffusion-weighted imaging and 2-deoxy-2-[(18)F]fluoro-D-glucose-positron emission tomography/computed tomography (FDG-PET/CT) in rectal cancer.

PROCEDURES

Thirty-three consecutive patients with pathologically confirmed rectal adenocarcinoma were included in this study. Apparent diffusion coefficient (ADC) maps were generated to calculate ADC(mean) (average ADC), ADC(min) (lowest ADC), tumor volume, and total diffusivity index (TDI). PET/CT exams were performed within 1 week of magnetic resonance imaging. Standardized uptake values (SUVs) were normalized to the injected FDG dose and body weight. SUV(max) (maximum SUV), SUV(mean) (average SUV), tumor volume, and total lesion glycolysis (TLG) were calculated using a 50% threshold.

RESULTS

Significant negative correlations were found between ADC(min) and SUV(max) (r = -0.450, p = 0.009), and between ADC(mean) and SUV(mean) (r = -0.402, p = 0.020). A significant positive correlation was found between TDI and TLG (r = 0.634, p < 0.001).

CONCLUSION

The significant negative correlations between ADC and SUV suggest an association between tumor cellularity and metabolic activity in primary rectal adenocarcinoma.

A clinicopathological study of resected non-small cell lung cancers 2 cm or less in diameter: a prognostic assessment

The detection and diagnosis of small-sized (2 cm or less) non-small cell lung cancer (NSCLC) has increased with the development of computed tomography (CT). Over 80% of 5-year survival rate has been reported in surgically treated peripheral lung cancer. There are systematic mediastinal and hilar lymph node involvement pleural invasion and intrapulmonary metastasis even with tumor diameter less than 2 cm. The appropriate surgical procedure for such kinds of lung cancer is lobectomy with mediastinal lymph node dissection. To evaluate the prognostic factors and establish the optimal surgical strategy, we analyzed the clinicopathologic features and survival benefit in different tumor size of peripheral small-sized NSCLC. Among the resected lung cancer cases between January 1999 and July 2001, 185 patients were retrospectively analyzed in surgical methods, lymph node involvement, CT scan findings and survival rates. Survival was analyzed by Kaplan-Meier method and log-rank test. Lymph node involvement was recognized in 26(14.05%) patients. There was no statistically significant difference in the incidence of lymph node involvement between tumors 1.6-2.0 cm (17.82%) in diameter than in those 1.0-1.5 cm (11.94%). There was no lymph node metastasis in tumors less than 1.0 cm in diameter. The 5-year survival rates with or without lymph node involvement were 89.98 and 46.15%, respectively, showing significant difference (P=0.000). The overall 5-year survival rate was 83.78%. The 5-year survival rate in tumors 1.6-2.0 cm, 1.0-1.5 cm and less than 1.0 cm in diameter was 80.20, 85.07 and 100%, respectively, and showing significant difference (P=0.035). The 5-year survival rate of 19 patients showing ground-glass opacity (GGO) on CT scan was 94.74% without any metastasis and recurrence after operation. There are systematic mediastinal and hilar lymph node involvement even with tumor diameter less than 2 cm. The results of the present study suggested that systematic lymph node dissection is necessary even for cases with tumor diameter less than 2 cm. However, if the tumor is within 1.0 cm in diameter with obvious GGO showing on chest CT scan, these are good candidates for partial resection without mediastinal lymph node dissection.

[PET-CT for evaluation of the solitary pulmonary nodule: an update]

INTRODUCTION

Positron emission tomography (PET) with 18F-FDG has become an important tool for the characterization of solitary pulmonary nodules (SPN).

BACKGROUND

The results of the main meta-analyses show that the sensitivity and specificity of 18F-FDG PET for determining malignancy of SPN are close to 95% and 80% respectively. The limits of the technology are now well known. False negative results are mainly due to certain histological types with low metabolic activity (such as bronchiolo-alveolar carcinoma and typical carcinoid), or small size (nodules less than 8 mm). False positives are mainly represented by granulomatous and infectious processes.

VIEWPOINTS

A gain in accuracy occurred with the advent of hybrid PET/CT machines that combine the functional data from 18FDG-PET and the morphological data of computed tomography. Improved imaging protocols (eg. injection of iodinated contrast media) could further enhance the performance of PET-CT. Further improvements will rely on respiratory synchronization protocols and on the advent of new PET tracers.

CONCLUSION

18F-FDG PET-CT should be performed for any nodule over 8 mm in size when the pre-test probability of malignancy is not deemed negligible.

Stepwise evolution from a focal pure pulmonary ground-glass opacity nodule into an invasive lung adenocarcinoma: an observation for more than 10 years

The natural chronologic evolution of a lung cancer manifesting as a pure ground-glass opacity (GGO) nodule on CT scans still remains to be elucidated. Therefore, it is sometimes difficult to determine proper follow-up examinations, particularly in case of GGO nodule growing slowly on serial CT scans. In the current case, we demonstrate serial morphologic (CT) and metabolic ((18)F-FDG PET) imaging findings in a case of adenocarcinoma, where stepwise progression from a focal pure GGO nodule (presumed atypical adenomatous hyperplasia [AAH] or bronchioloalveolar carcinoma [BAC]) eventually to an invasive adenocarcinoma was clearly depicted for more than 10-year follow-up period. This case seems to be useful for the prediction of tumor growth pattern and aggressiveness of malignant pure GGO nodules. In addition, the evolving process of this case may suggest a guideline for planning an appropriate follow-up examination and management in such cases.

FDG-PET/CT imaging in assessing mucin-producing non-small cell lung cancer with pathologic correlation

OBJECTIVE

The objective of this study was to describe the PET/CT findings of mucin-producing non-small cell lung cancer (NSCLC) and how those findings are associated with pathology.

METHODS

A review of all patients with FDG-PET/CT identified 11 patients with histopathologically confirmed mucin-producing NSCLC; 3 mucinous bronchioloalveolar carcinoma (mBAC), 5 mixed-type adenocarcinoma with prominent mucinous BAC pattern (ADENO + mBAC), and 3 mixed-type adenocarcinoma with mucin production (ADENO + MUCIN) in our institute.

RESULTS

Among 11 patients, only 2 lesions (18%) evidenced positive PET results for standardized uptake value (SUV) of 3.5 (by ROC analysis) whereas all cases were detected correctly at CT. The mean SUV was 2.0 in the 9 lesions not detected and 2.5 in all cases. The mean SUV of pure mBAC was 1.93, that of mucin-producing adenocarcinoma was 2.69 without a significant difference (p = 0.279). No significant correlations between tumor size or stage and SUV were determined.

CONCLUSIONS

PET/CT for SUV is limited in the detection of mucin-producing NSCLC. Therefore, the CT component of PET/CT may allow for significantly improved sensitivity and help to reduce delayed diagnose. The SUV in mBACs were lower than the other types of mucin-producing adenocarcinoma; however, we determined no significant difference to exist between the SUVs of two groups of lung cancer.

Clinical usefulness of the fluorodeoxyglucose (FDG)-PET maximal standardized uptake value (SUV) in combination with CT features for the differentiation of adenocarcinoma with a bronchioloalveolar carcinoma from other subtypes of non-small cell lung cancers

PURPOSE

To evaluate the clinical usefulness of fluorodeoxyglucose (FDG)-PET maximal SUV in combination with CT features for differentiation of adenocarcinoma with bronchioloalveolar carcinoma (BAC) from other subtypes of non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

This retrospective study included 125 patients (104 men and 21 women; mean age, 64 years) who underwent CT and subsequent FDG-PET examinations for preoperative evaluation and underwent curative intent operation with the final diagnoses of NSCLC made by surgical histopathology. We categorized NSCLC into adenocarcinoma with BAC feature and other subtypes. Finally, there were 16 cases of adenocarcinoma with BAC and 109 cases of other NSCLC subtypes included in the study. Several CT features of lung cancer were analyzed, including tumor size, presence of spiculation, margin (irregular or smooth), pattern of the mass (pure solid, pure ground glass opacity and mixed), associated pleural effusion and location (center, mid and periphery). Maximal SUV and visual scores of FDG uptakes of primary NSCLC were evaluated. The diagnostic performances of CT alone, PET alone, and combination of two modalities to predict adenocarcinoma with BAC from other subtypes of NSCLC were calculated.

RESULTS

A nodule with a mixed pattern with partly solid and ground glass opacity was significantly more frequent CT feature of an adenocarcinoma with BAC (8/16, 50%) as compared with the other subtypes (2/109, 1.8%) (p<0.0001). Maximal SUV of adenocarcinoma with BAC (mean=7.2) was significantly lower than that of other subtypes of NSCLC (mean=13.33) (p<0.0001). Sensitivity, specificity, PPV, and NPV of CT for differentiating adenocarcinoma with BAC from other subtypes was 50% (8/16), 98.2% (107/109), 80% (8/10), and 93% (107/115), respectively. Sensitivity, specificity, PPV, and NPV of FDG-PET was 68.8% (11/16), 86.2% (94/109), 42.3% (11/26), and 94.9% (94/99), respectively. Sensitivity, specificity, PPV, and NPV of combination of two modalities was 81.3% (13/16), 85.3% (93/109), 44.8% (13/29), 96.9% (93/96), respectively.

CONCLUSION

Careful combined assessment of the FDG-PET maximal SUV and CT findings have the potential to differentiate an adenocarcinoma with BAC from other NSCLC subtypes, such as a pure BAC. These findings might be useful for imaging interpretations and will help initial planning of NSCLC management.

Differentiation between malignancy and inflammation in pulmonary ground-glass nodules: The feasibility of integrated (18)F-FDG PET/CT

BACKGROUND

(18)F-FDG PET/CT has been used to differentiate malignant solid lung nodules from benign nodules. We assess the feasibility of integrated (18)F-FDG PET/CT for the differentiation of malignancy from inflammation manifested as ground-glass nodules (GGNs) on chest CT.

METHODS

A total of 68 GGNs in 45 patients (M:F=24:21; mean age, 61) fulfilled the following criteria: (a) nodules composed of >/=50% ground-glass opacity, (b) patients who underwent integrated PET/CT within 1 week following dedicated chest CT, (c) definitive diagnosis determined by pathological specimen or at least 9 months of follow-up, and (d) lesions >/=10mm in diameter. 36 malignant GGNs were pathologically proved as adenocarcinoma (n=20), bronchioloalveolar carcinoma (n=11), low-grade lymphoma (n=3), metastatic mucinous adenocarcinoma (n=1) and unknown low-grade malignancy (n=1). 32 inflammatory GGNs were confirmed as pneumonic infiltration as they had disappeared on follow-up CT and were associated with compatible clinical features (n=26) or as chronic inflammation with fibrosis by VATS biopsy (n=6). Using CT density histogram analysis, 14 were classified as pure GGNs and 54 as part-solid nodules. Integrated PET/CT was evaluated by measuring the maximum standardized uptake value (SUV) at the region of interest located at each lesion. The Mann-Whitney U test was performed to compare the SUV of malignancy and inflammation. The optimal cut-off value of SUV to differentiate malignancy from inflammation was determined using a receiver operating characteristic-based positive test. Sensitivity, specificity, accuracy, and positive predictive values (PPV) and negative predictive values (NPV) were calculated at the level of the optimal cut-off value. SUV showing 100% PPV for inflammatory GGNs was evaluated.

RESULTS

In part-solid nodules, the maximum SUV was significantly higher in inflammation (2.00+/-1.18; range, 0.48-5.60) than in malignancy (1.26+/-0.71; range, 0.32-2.6) (P=0.018). On the other hand, in pure GGNs, the maximum SUV of malignancy (0.64+/-0.19; range, 0.43-0.96) and inflammation (0.74+/-0.28; range, 0.32-1.00) showed no difference (P=0.37). Using the optimal cut-off value of SUV as 1.2 (P=0.01) sensitivity, specificity, accuracy, PPV and NPV in part-solid nodules were 62.1%, 80.0%, 70.4%, 78.3% and 64.5%, respectively. Six part-solid nodules, which showed a maximum SUV of higher than 2.6, were all inflammations.

CONCLUSION

The part-solid nodules with positive FDG-PET could be inflammatory nodules rather than malignant nodules. This is a quite paradoxical result when considering the basic knowledge that malignant pulmonary nodules have higher glucose metabolism.