Combined use of positron emission tomography and volume doubling time in lung cancer screening with low-dose CT scanning

Computer-assisted solid lung nodule 3D volumetry on CT: influence of scan mode and iterative reconstruction: a CT phantom study

OBJECTIVE

To evaluate the effect of high-resolution scan mode and iterative reconstruction on lung nodule 3D volumetry.

METHODS

Solid nodules with various sizes (5, 8, 10 and 12 mm) were placed inside a chest phantom. CT images were obtained with various tube currents, scan modes (conventional mode, high-resolution mode) and iterative reconstructions [0, 50 and 100 % blending of adaptive statistical iterative reconstruction (ASiR) and filtered back projection]. The nodule volumes were calculated using semiautomatic software and compared with the assumed volume from the nodules.

RESULTS

The mean absolute and relative percentage error improved when using iterative reconstruction especially when using the conventional scan mode; however, this effect was not significant. Significant reduction in volume overestimation was observed when using high-resolution scan mode (P = 0.011).

CONCLUSION

The high-resolution mode significantly reduces the volume overestimation of 3D volumetry. Iterative reconstruction shows a reduction in volume overestimation and error margin especially with the conventional scan mode; however, this effect was not significant.

Measurement methods and algorithms for the management of solid nodules

The increased detection of incidental small pulmonary nodules on multidetector computed tomography has driven attempts to refine the characterization and management of such nodules. A variety of methods have been developed to measure the size and biological activity of nodules to help define their nature, but these have limitations. Several clinical trials have assessed the efficacy of low-dose computed tomography screening for lung cancer and offer some insights into these limitations; however, they also provide evidence that refines existing nodule management strategies. This article reviews the size-based and functional measurement methods that can be used to predict the likelihood of malignancy in noncalcified solid pulmonary nodules and discusses their incorporation into existing algorithms for nodule management. The issue of multiple nodules and the optimum frequency and duration of follow-up are explored.

Lung cancer screening and video-assisted thoracic surgery

INTRODUCTION

The objective of this study is to report the impact of computed tomography (CT) screening on the use of Video-Assisted Thoracic Surgery (VATS) in a randomized screening trial.

METHODS

The Danish Lung Cancer Screening Trial is a randomized clinically controlled trial of 4104 smokers and previous smokers who were randomized to either screening with five annual low-dose CT scans or no screening in Copenhagen from 2004 to 2006. The major end point is the effect of CT screening on lung cancer mortality and treatment options. All diagnostic and treatment interventions in both groups were monitored prospectively until 1 to 3 years after the last screening round.

RESULTS

By February 1, 2011 68 cases of lung cancer were detected in the screening group. Furthermore, seven patients with a benign nodule underwent surgical treatment because of suspicion of malignancy (12%). Fifty-one of the 68 lung cancer patients were eligible for surgical treatment. Eight patients had open thoracotomy. Of the operations for lung cancer, 84% were performed by VATS in the CT-screened arm, significantly higher than the control arm (p < 0.05). Thirty-six patients had a VATS lobectomy. One patient had a VATS segmentectomy, and four patients had a VATS wedge resection. The seven benign nodules were all treated with VATS.

CONCLUSIONS

CT screening seems to facilitate the use of VATS in the treatment of lung cancer with an 84% rate in our data. Furthermore, all benign nodules could be removed by VATS. In our view, a basic requirement for a surgical institution to be involved in lung cancer CT screening is a dedicated VATS program.

Dose exposure in the ITALUNG trial of lung cancer screening with low-dose CT

Few data are available on the effective dose received by participants in lung cancer screening programmes with low-dose CT (LDCT). We report the collective effective dose delivered to 1406 current or former smokers enrolled in the ITALUNG trial who completed 4 annual LDCT examinations and related further investigations including follow-up LDCT, 2-[(18)F]flu-2-deoxy-d-glucose positron emission tomography (FDG-PET) or CT-guided fine needle aspiration biopsy (FNAB). Using the air CT dose index and Monte Carlo simulations on an anthropomorphic phantom, the whole-body effective dose associated with LDCT was determined for the eight CT scanners used in the trial. A value of 7 mSv was assigned to FDG-PET while the measured mean effective dose of CT-guided FNAB was 1.5 mSv. The mean collective effective dose in the 1406 subjects ranged between 8.75 and 9.36 Sv and the mean effective dose to the single subject over 4 years was between 6.2 and 6.8 mSv (range 1.7-21.5 mSv) according to the cranial-caudal length of the LDCT volume. 77.4% of the dose was owing to annual LDCT and 22.6% to further investigations. Considering the nominal risk coefficients for stochastic effects after exposure to low-dose radiation according to the National Radiological Protection Board, International Commission on Radiological Protection (ICRP) 60, ICRP103 and Biological Effects of Ionizing Radiation VII, the mean number of radiation-induced cancers ranged between 0.12 and 0.33 per 1000 subjects. The individual effective dose to participants in a 4-year lung cancer screening programme with annual LDCT is very low and about one-third of the effective dose that is associated with natural background radiation and diagnostic radiology in the same time period.

The use and misuse of positron emission tomography in lung cancer evaluation

This article discusses the potential benefits and limitations of positron emission tomography (PET) for characterizing lung nodules, staging the mediastinum, identifying occult distant metastasis, determining prognosis and treatment response, guiding plans for radiation therapy, restaging during and after treatment, and selecting targets for tissue sampling. The key findings from the medical literature are presented regarding the capabilities and fallibilities of PET in lung cancer evaluation, including characterization of pulmonary nodules and staging in patients with known or suspected non-small-cell lung cancer. The discussion is limited to PET imaging with fluorodeoxyglucose.

The value of positron emission tomography in early detection of lung cancer in high-risk population: a systematic review

BACKGROUND

Early detection trials with chest radiography and sputum cytology were ineffective in decreasing lung cancer mortality. The advent of low-dose spiral chest computed tomography (LDCT) provided clinicians with a new tool that could be with early diagnosis; however, this also raised significant concerns regarding the systematic use of LDCT with its high false-positive rate for benign nodules. At this time, there is limited information about the true role of PET (positron emission tomography) for early detection of lung cancer.

METHODS

We used systematic methods, including Preferred Reporting Items for Systematic reviews and Meta-Analyses statement, to identify relevant studies, assess study eligibility, evaluate study methodological quality, and summarize findings regarding diagnostic accuracy and outcome.

RESULTS

In total, only seven eligible studies were selected from 82 potentially relevant studies. The sensitivity of 18F-FDG-PET for the detection of T1 lung cancers ranged between 68% and 95%. The rate of detection tended to be lower for carcinoid tumors, adenocarcinoma and bronchoalveolar cell carcinomas. FDG-PET using SUV (standardized uptake value) level can predict the outcome of the screening detected lung cancer. A combination of FDG-PET and LDCT may improve screening for lung cancer in high-risk patients.

CONCLUSIONS

PET or PET/CT may be used as a useful tool for early detection of lung cancer in high-risk population based on the existing information. However, there is still limited information with regards to evidence of survival benefits from PET screening in high-risk patients.

Growth of a solitary pulmonary nodule after 6years diagnosed as oncocytic carcinoid tumour with a high 18-fluorodeoxyglucose (18F-FDG) uptake in positron emission tomography-computed tomography (PET-CT)

INTRODUCTION

Pulmonary carcinoid tumour is low-grade neuroendocrine malignancy that is seen 1%-2% of all lung neoplasms. Oncocytic carcinoid type is a rarely seen variant of pulmonary carcinoids. As carcinoid tumours have hypometabolic activity, they usually have lower 18-fluorodeoxyglucose (18F-FDG) uptake than expected for lung carcinoma on positron emission tomography (PET).

CASE REPORT

A 45-year-old non-smoking man had a stable solitary pulmonary nodule followed for 6years; the tumour remained the same size (1.5×2.4cm) during this period. The patient was admitted to the hospital with complaints of repetitive sneezing and rhinorrhoea. He also experienced flushing and bronchospasm. His chest X-ray revealed a minimal increase in the size of the solitary pulmonary nodule (2.0×2.8cm). In PET-computed tomography (CT), the parenchymal nodule in the anterior segment of the right lung had a standard uptake value of 38.0mg/mL, which was interpreted as a malignant nodule. He underwent fibre-optic bronchoscopy, but cytology showed no evidence of malignancy. Right upper and middle bilobectomy was performed, and a pulmonary carcinoid tumour with an oncocytic subgroup was diagnosed. The diagnosis of carcinoid syndrome was further confirmed by an elevated 24-h urinary excretion of 5-hydroxyindoleacetic acid.

CONCLUSION

We present a rare case of an oncocytic carcinoid tumour with an increase in the size of a solitary pulmonary nodule after 6years' follow-up. In addition, PET-CT showed a very high 18F-FDG uptake in this patient, which is an unexpected finding with a pulmonary carcinoid tumour.