Imaging in lung cancer: positron emission tomography scan

Diagnostic success of transthoracic needle biopsy and PET-CT for 1 to 2 cm solid indeterminate pulmonary nodules

OBJECTIVES

Among the nodule types, the most controversial group are indeterminate solid nodules from 1 to 2 cm in size with the first choice being transthoracic needle biopsy (TTNB) or positron emission tomography (PET-CT) or both methods together. However, no single diagnostic algorithm could be applied to all cases. This research discusses the diagnostic success of PET-CT and TTNB.

MATERIALS AND METHODS

407 Patients who referred to our hospital for any reason, with solid nodules with the size from 1 to 2 cmincidentally identified on the thoracic CT tests were investigated. Among the patients who underwent biopsy, 312 cases had PET-CT, and maximum SUV (SUVmax) values of the nodules were examined. Values of ≥2.5 were accepted as hypermetabolic.

RESULTS

The mean age of the patients was 61 ± 10.8 years. 84 patients were female (20.6%) and 323 were male (79.4%). For TTNB; sensitivity, specificity and accuracy rates of all cases, who were correctly diagnosed, were 76.9%, 83.3% and 78.9%, respectively (P < .001). The 2.5 SUVmax cutoff value had sensitivity of 91%, specificity of 35.6%, accuracy of 75% (P = .034). The cutoff value of 49 years of age, nodule size of 16.4 mm, gender and 2.5 SUVmax value had high accuracy for benign-malignant differentiation. No statistically significant difference was found in the upper lobe localization of nodule.

CONCLUSION

A positive result from TTNB is a reliable finding; however, a negative result is not definitive. The high negative predictive value of PET-CT is effective in preventing the unnecessary biopsies and surgical procedures.

Prediction of pleural invasion using different imaging tools in non-small cell lung cancer

Clinical staging of non-small cell lung cancer (NSCLC) is used for planning therapeutic strategies. In particular, pleural invasion is regarded as an indicator for upstaging to T2 or T3 in the current 8th TNM staging system; patients with pleural invasion should be indicated for lobectomy rather than sublobar resection. Therefore, accurate preoperative prediction of pleural invasion is important for surgical planning. In recent years, different radiological investigations for patients with NSCLC have been widely used, and methods for more precise detection have been developed in the current medical imaging studies. Therefore, several radiological investigation tools have been used for the prediction of pleural invasion. In this article, to identify the imaging modalities for accurate prediction of pleural invasion, we reviewed the different methods used for this purpose and discussed their advantages and limitations.

The role of positron emission tomography in the diagnosis, staging and response assessment of non-small cell lung cancer

Lung cancer is a common disease and the leading cause of cancer-related mortality, with non-small cell lung cancer (NSCLC) accounting for the majority of cases. Following diagnosis of lung cancer, accurate staging is essential to guide clinical management and inform prognosis. Positron emission tomography (PET) in conjunction with computed tomography (CT)-as PET-CT has developed as an important tool in the multi-disciplinary management of lung cancer. This article will review the current evidence for the role of ¹⁸F-fluorodeoxyglucose (FDG) PET-CT in NSCLC diagnosis, staging, response assessment and follow up.

Monitoring and management of lung cancer patients following curative-intent treatment: clinical utility of 2-deoxy-2-[fluorine-18]fluoro-d-glucose positron emission tomography/computed tomography

A large number of studies have demonstrated that 2-deoxy-2-[fluorine-18]fluoro-d-glucose positron emission tomography/computed tomography (FDG-PET/CT) is superior to conventional modalities for the diagnosis of lung cancer and the evaluation of the extent of the disease. However, the efficacy of PET/CT in a follow-up surveillance setting following curative-intent treatments for lung cancer has not yet been established. We reviewed previous papers and evaluated the potential efficacy of PET-CT in the setting of follow-up surveillance. The following are our findings: 1) PET/CT is considered to be superior or equivalent to conventional modalities for the detection of local recurrence. However, inflammatory changes and fibrosis after treatments in local areas often result in false-positive findings; 2) the detection of asymptomatic distant metastasis is considered to be an advantage of PET/CT in a follow-up setting. However, it should be noted that detection of brain metastasis with PET/CT has some limitation, similar to its use in pretreatment staging; 3) additional radiation exposure and higher medical cost arising from the use of PET/CT should be taken into consideration, particularly in patients who might not have cancer after curative-intent treatment and are expected to have a long lifespan. The absence of any data regarding survival benefits and/or improvements in quality of life is another critical issue. In summary, PET/CT is considered to be more accurate and sensitive than conventional modalities for the detection of asymptomatic recurrence after curative-intent treatments. These advantages could modify subsequent management in patients with suspected recurrence and might contribute to the selection of appropriate treatments for recurrence. Therefore, PET/CT may be an alternative to conventional follow-up modalities. However, several important issues remain to be solved. PET/CT in a follow-up surveillance setting is generally not recommended in clinical practice at the moment.

Non-invasive molecular imaging for preclinical cancer therapeutic development

Molecular and non-invasive imaging are rapidly emerging fields in preclinical cancer drug discovery. This is driven by the need to develop more efficacious and safer treatments, the advent of molecular-targeted therapeutics, and the requirements to reduce and refine current preclinical in vivo models. Such bioimaging strategies include MRI, PET, single positron emission computed tomography, ultrasound, and optical approaches such as bioluminescence and fluorescence imaging. These molecular imaging modalities have several advantages over traditional screening methods, not least the ability to quantitatively monitor pharmacodynamic changes at the cellular and molecular level in living animals non-invasively in real time. This review aims to provide an overview of non-invasive molecular imaging techniques, highlighting the strengths, limitations and versatility of these approaches in preclinical cancer drug discovery and development.

Approach to a solid solitary pulmonary nodule in two different settings-"Common is common, rare is rare"

A new solid solitary pulmonary nodule (SPN) is a common feature in the daily practice of physicians, pulmonologists and thoracic surgeons. The etiology and consequently the diagnostic approach is very different in various parts of the world. Identification of malignant nodules is the universal goal to proceed to a potential curable therapy. In countries with a low incidence of inflammatory disease and a high incidence of lung cancer the diagnostic work up includes a positron emission tomography (PET) scan or PET-computer tomography (CT) as a main pillar. In countries with a high incidence of inflammatory and infectious disease and a low incidence in lung cancer this diagnostic work up needs to be adapted. In these settings a PET scan has a limited role and tissue diagnosis, whether with a trans-thoracic, trans-bronchial biopsy or a video-assisted wedge resection is the most targeted approach to determine or exclude malignancy. The evaluation of a solid SPN in the two different situations is outlined in our algorithm. Recommendations stress the value of clinical judgement in different settings, determination of probabilities of malignancy, cost-effective use of diagnostic tools and evaluation of various management alternatives according to the risk profile and the patients preferences.

Use of CT to evaluate pleural invasion in non-small cell lung cancer: measurement of the ratio of the interface between tumor and neighboring structures to maximum tumor diameter

PURPOSE

To develop a simple noninvasive technique for evaluating pleural invasion by using routine preoperative computed tomography (CT).

MATERIALS AND METHODS

The institutional review board approved this retrospective study, and written informed consent was obtained for performing the initial and follow-up CT studies. Preoperative CT findings (169 patients with possible pleural invasion) and pathologic diagnoses after surgical resection were evaluated. The length of the interface between the primary tumor and neighboring structures (arch distance) and the maximum tumor diameter were measured on CT images, after which arch distance-to-maximum tumor diameter ratios were calculated. Receiver operating characteristic (ROC) curves were used to analyze the ratios.

RESULTS

Median arch distance-to-maximum tumor diameter ratios for pleural invasion categories (pl1, pl2, pl3) assessed by using the Union Internationale Contre le Cancer TNM staging system were as follows: pl1, 0.206 (25th-75th percentile, 0-0.486); pl2, 0.638 (25th-75th percentile, 0.385-0.830); and pl3, 1.092 (25th-75th percentile, 1.045-1.214) (P < .001 between groups). On the basis of the ROC curves, the cut-off value for invasion was an arch distance-to-maximum tumor diameter ratio of 0.9. When the ratio was greater than 0.9, the sensitivity and specificity for thoracic invasion and area under the ROC curve were 89.7%, 96.0%, and 0.976, respectively, which represents an improvement over values obtained by using conventional criteria (radiologists A and B: 46.7% and 74.2% and 91.3% and 84.8%, respectively).

CONCLUSION

When diagnosing T3 or T4 lung cancer based on arch distance-to-maximum tumor diameter ratios, a higher performance level was achieved than that with use of conventional criteria. Measurement of the ratios is a simple noninvasive technique for evaluating pleural invasion at CT.

Correlation of tissue biopsy and fine needle aspiration cytology with positron emission tomography results

F-18-fluorodeoxyglucose (FDG) Positron Emission Tomography (PET) scans are positive in any condition which increases metabolism in a mass or tissue and are therefore not specific for neoplastic conditions. The use of an SUV cutoff value of 2.5 may not always help discriminate between benign and malignant cases. For a practicing cytopathologist doing adequacy checks during an image-guided procedure, it may be of value to be aware that elevated SUV values are not always indicative of a malignant process, and vice versa.

Bone single photon emission computed tomography (SPECT) in a patient with Pancoast tumor: a case report

CONTEXT

Non-small cell lung carcinomas (NSCLCs) of the superior sulcus are considered to be the most challenging type of malignant thoracic disease. In this disease, neoplasms originating mostly from the extreme apex of the lung expand to the chest wall and thoracic inlet structures. Multiple imaging procedures have been applied to identify tumors and to stage and predict tumor resectability in surgical operations. Clinical examinations to localize pain complaints in shoulders and down the arms, and to screen for Horner's syndrome and abnormalities seen in paraclinical assessments, have been applied extensively for differential diagnosis of superior sulcus tumors. Although several types of imaging have been utilized for diagnosing and staging Pancoast tumors, there have been almost no reports on the efficiency of whole-body bone scans (WBBS) for detecting the level of abnormality in cases of superior sulcus tumors.

CASE REPORT

We describe a case of Pancoast tumor in which technetium-99m methylene diphosphonate (Tc-99m MDP) bone single-photon emission-computed tomography (SPECT) was able to accurately detect multiple areas of abnormality in the vertebrae and ribs. In describing this case, we stress the clinical and diagnostic points, in the hope of stimulating a higher degree of suspicion and thereby facilitating appropriate diagnosis and treatment. From the results of this study, further clinical trials to evaluate the potential of SPECT as an efficient imaging tool for the work-up on cases of Pancoast tumor are recommended.

Contribution of positron emission tomography in pleural disease

INTRODUCTION

Positron emission tomography (PET) now plays a clear role in oncology, especially in chest tumours. We discuss the value of metabolic imaging in characterising pleural pathology in the light of our own experience and review the literature.

BACKGROUND

PET is particularly useful in characterising malignant pleural pathologies and is a factor of prognosis in mesothelioma. Metabolic imaging also provides clinical information for staging lung cancer, in researching the primary tumour in metastatic pleurisy and in monitoring chronic or recurrent pleural pathologies.

CONCLUSIONS

PET should therefore be considered as a useful tool in the diagnosis of liquid or solid pleural pathologies.

Non-invasive molecular imaging of prostate cancer lymph node metastasis

Imaging in medicine has been classically based on the anatomical description of organs. In the past 15 years, new imaging techniques based on gene expression that characterize a pathological process have been developed. Molecular imaging is the use of such molecules to image cell-specific characteristics. Here, we review recent advances in molecular imaging, taking as our prime example lymph node (LN) metastasis in prostate cancer. We describe the new techniques and compare their accuracy in detecting LN metastasis in prostate cancer. We also present new molecular strategies for improving tumor detection using adenoviruses, molecular promoters and amplification systems. Finally, we present the concept of 'in vivo pathology', which envisages using molecular imaging to accurately localize metastatic lesions based on the molecular signature of the disease.

[Usefulness of positron emission tomography-computed tomography in respiratory medicine]

The introduction of positron emission tomography (PET) into the management of neoplastic disease in respiratory patients signified an important change from classic algorithms based exclusively on anatomic information obtained through computed tomography (CT). Non-small cell lung cancer and solitary pulmonary nodule were the 2 diseases in which metabolic PET imaging offered the highest diagnostic yield, as has been evident since the inclusion of this technology among the services available within the Spanish national health service. However, a number of limitations were encountered in relation to the lack of anatomic definition in PET imaging, as had been described in the literature. The appearance in 2001 of hybrid PET-CT devices has not only helped remedy those defects, but has also made it possible to combine anatomic and metabolic information in a single image, making this hybrid technology the most valuable tool in the current diagnostic arsenal.

[Interventional oncology for lung tumors]

Lung tumors and pulmonary metastases together are the most common cause of cancer-related death in men and the second most frequent in women. Up to now, surgical resection has remained the gold standard in the treatment of pulmonary tumors, being the only treatment option that was potentially curative and offered the possibility of a significant increase in life expectancy after successful therapy. Over the past decade, percutaneous radiofrequency ablation (RFA) has gained worldwide acceptance in the treatment of primary and secondary tumors of the liver with curative intent, so that indications for RFA have been extended to embrace tumors in other organs, e.g. the lung. Since the first case results were described, the number of publications dealing with the treatment of lung tumors using thermal ablative therapies has increased significantly. The aims of the present article are to give a short overview of emerging therapies such as cyberknife surgery and also, especially, to describe the indications for and technique of RFA, to discuss the ideal method of follow-up, and to highlight possible complications of the therapy and the current results of RFA of primary and secondary lung tumors. In addition, the value of combining RFA with other therapy modes (especially chemotherapy and radiation therapy)is briefly treated.

Interobserver and Intraobserver Variability of Standardized Uptake Value Measurements in Non–small-cell Lung Cancer

OBJECTIVES

To assess interobserver and intraobserver variabilities in measuring the maximal standardized uptake value (SUV) of non-small-cell lung cancer.

METHODS

Positron emission tomography-computed tomography examinations of 20 consecutive patients referred for initial evaluation of newly diagnosed non-small-cell lung cancer were retrospectively reviewed by 5 experienced positron emission tomography-computed tomography readers, who independently measured the maximal SUV/body weight of the primary tumors. Interobserver and intraobserver variabilities were assessed by using 4 statistical methods: correlation, regression analysis, Bland-Altman analysis, and analysis of variance. The SUV measurements derived in the study were compared with the SUV measurements documented in the original reports using correlation and regression analysis. The percentages of tumors whose retrospective SUV measurements were more than 20% different and more than 25% different from those in the original report were assessed.

RESULTS

Both interobserver and intraobserver SUV measurements were highly reproducible. Pearson correlation coefficients were greater than 0.95 and 0.94, respectively. Good interobserver and intraobserver agreement was shown with regression analysis (F test P value >0.05), the Bland-Altman analysis, and analysis of variance (F test P value >0.95). The mean original SUV was much less than the mean study SUV (P<0.05). The study SUV differed from the SUV of the original report by more than 20% in 50% of the tumors, and by more than 25% in 45% of the tumors.

CONCLUSIONS

There was excellent interobserver and intraobserver agreement in SUVs measured in the study environment but poor agreement between study SUVs and those documented in original reports, which can affect treatment decisions substantially.

Value of FDG PET in the management of NSCLC

Metabolic imaging with positron emission tomography (PET) using 18F-fluoro-2-deoxy-glucose (FDG) has been accepted as an important imaging modality in lung cancer. FDG PET may have important impacts on the management of lung-cancer patients, for instance by improvement of locoregional (mediastinal) and extrathoracic staging (unexpected metastases). Interesting findings have now been reported in the response assessment to induction therapy providing results of greater prognostic significance than that obtained by conventional imaging methods. In the field of thoracic irradiation, FDG PET may provide advantages in terms of reduced toxicity, treatment intensification, better local tumour control and increased survival.

Radiologic appearance and complications of percutaneous computed tomography-guided radiofrequency-ablated pulmonary metastases from colorectal carcinoma

OBJECTIVES

To describe the morphologic appearance over time of percutaneously radiofrequency-ablated pulmonary metastases from colorectal cancer and to focus on the occurrence of the most common complications.

METHODS

Twenty patients have been treated with computed tomography (CT)-guided radiofrequency ablation (RFA) for 41 pulmonary metastases using the expandable 14-gauge StarBurst XL RF electrode along with the 1500 generator (RITA Medical Systems, Mountain View, CA). The average number of lesions per patient was 2.05, ranging from 1 to 4 lesions.

RESULTS

The typical feature of the radiofrequency-ablated site immediately after the procedure was a light bulb-shaped opacification surrounding the probe. This became a more spherically shaped feature over time and steadily decreased in size. At 3 months after RFA, the lesion was approximately the same size as at baseline. The lesion subsequently shrank within the following 3 months, usually with a small scar remaining. Pneumothorax occurred in 50% of the patients, and a chest tube was required in 50% of the patients affected. Cavitation occurred in 24% of the lesions. Intraparenchymal hemorrhage was observed in 7.5% of the cases.

CONCLUSIONS

Image-guided pulmonary RFA is a safe minimally invasive therapy modality with acceptable morbidity. Ablated lesion size usually exceeds the dimensions of the initial tumor for the first 3 months after ablation and continuously shrinks thereafter.

Bronchoscopy and surgical staging procedures and their correlation with imaging

Bronchoscopy, computed tomography (CT) and surgical staging procedures are complimentary methods of investigating patients with lung cancer. CT has been shown to be of value prior to bronchoscopy in the investigation of haemoptysis and malignancy, with excellent correlation between the detection of disease within the large airways on CT and direct visualisation at bronchoscopy. The utility of CT has been further increased by the development of multislice scanners with the generation of volumetric data enabling multiplanar image acquisition. Additionally the advent of CT co-registered with positron emission tomography will play an important role in guiding the choice of surgical staging procedures The increasing use of multidisciplinary medical care requires radiologists to have a greater understanding of the abilities and limitations of both bronchoscopy and surgical staging procedures in evaluating disease demonstrated on imaging.