Update in PET imaging of nonsmall cell lung cancer

Diagnostic value of 18F-FDG-PET/CT in benign lung diseases

Introduction

There are many diseases which, despite not being malignant, show high metabolic activity and cause false-positive results.

Aim

To evaluate the results of positron emission tomography (PET) in patients who underwent resection after preliminary diagnosis of malignancy based on fluorodeoxyglucose (FDG) uptake value, in whom the lesions were later classified as pathologically benign.

Material and methods

The analysis included the records of 106 (12.3%) patients out of 862 patients who underwent surgery between January 2012 and December 2015 after being initially diagnosed with malignant lung lesions based on PETCT results, in whom the lesions were later classified as pathologically benign. Diagnoses, PET findings, types of surgery, and demographic data of the patients were recorded.

Results

The mean age of the patients was 55.5 (26-79) years. The mean diameter and SUVmax of the lesions were 2 ±2.14 (0.5-13) and 3.55 ±4.35 (0-22.2) cm, respectively. The pathology results were analyzed in five different groups. The SUVmax in the hamartoma group was significantly lower than in the other groups (p < 0.001), while the SUVmax in the granulomatous disease group was significantly higher than in the other groups (p < 0.001).

Conclusions

The possibility of false positive PET results must be kept in mind when diagnosing and treating lung cancer. In particular, in the case of suspected granulomatous disease, all available pre- and intraoperative diagnostic procedures must be used.

Changes in Glucose Metabolism during and after Radiotherapy in Non-Small Cell Lung Cancer

Aims and background

Evaluation of the metabolic response to radiotherapy in non-small cell lung cancer patients is commonly performed about three months after the end of radiotherapy. The aim of the present study was to assess with positron emission tomography/computed tomography (PET/CT) and [18F]fluorodeoxyglucose changes in glucose metabolism during and after radiotherapy in non-small cell lung cancer patients.

Methods and study design

In 6 patients, PET/CT scans with [18F]fluorodeoxyglucose were performed before (PET0), during (PET1; at a median of 14 days before the end of radiotherapy) and after the end of radiotherapy (PET2 and PET3, at a median of 28 and 93 days, respectively). The metabolic response was scored according to visual and semiquantitative criteria.

Results

Standardize maximum uptake at PET1 (7.9 ± 4.8), PET2 (5.1 ± 4.1) and PET3 (2.7 ± 3.1) were all significantly (P <0.05; ANOVA repeated measures) lower than at PET0 (16.1 ± 10.1). Standardized maximum uptake at PET1 was significantly higher than at both PET2 and PET3. There were no significant differences in SUVmax between PET2 and PET3. PET3 identified 4 complete and 2 partial metabolic responses, whereas PET1 identified 6 partial metabolic responses. Radiotherapy-induced increased [18F]fluorodeoxyglucose uptake could be visually distinguished from tumor uptake based on PET/CT integration and was less frequent at PET1 (n = 2) than at PET3 (n = 6).

Conclusions

In non-small cell lung cancer, radiotherapy induces a progressive decrease in glucose metabolism that is greater 3 months after the end of treatment but can be detected during the treatment itself. Glucose avid, radiotherapy-induced inflammation is more evident after the end of radiotherapy than during radiotherapy and does not preclude the interpretation of [18F]fluorodeoxyglucose images, particularly when using PET/CT.

Review of Physiologic and Pathophysiologic Sources of Fluorodeoxyglucose Uptake in the Chest Wall on PET

The chest wall can be defined as the osseous and soft tissue structures that form the outer framework of the thorax and move during breathing. Topics discussed in this article include physiologic uptake of fluorodeoxyglucose, benign diseases of the chest wall, and malignant tumors of the chest wall.

18F-FDG PET/CT imaging in oncology

Accurate diagnosis and staging are essential for the optimal management of cancer patients. Positron emission tomography with 2-deoxy-2-[fluorine-18]fluoro-D-glucose integrated with computed tomography (18F-FDG PET/CT) has emerged as a powerful imaging tool for the detection of various cancers. The combined acquisition of PET and CT has synergistic advantages over PET or CT alone and minimizes their individual limitations. It is a valuable tool for staging and restaging of some tumors and has an important role in the detection of recurrence in asymptomatic patients with rising tumor marker levels and patients with negative or equivocal findings on conventional imaging techniques. It also allows for monitoring response to therapy and permitting timely modification of therapeutic regimens. In about 27% of the patients, the course of management is changed. This review provides guidance for oncologists/radiotherapists and clinical and surgical specialists on the use of 18F-FDG PET/CT in oncology.

Clinical results of stereotactic body frame based fractionated radiation therapy for primary or metastatic thoracic tumors

The aim of this study was to evaluate the treatment outcomes of stereotactic body radiation therapy for treating primary or metastatic thoracic tumors using a stereotactic body frame. Between January 1998 and February 2004, 101 lesions from 91 patients with thoracic tumors were prospectively reviewed. A dose of 10-12 Gy per fraction was given three to four times over consecutive days to a total dose of 30-48 Gy (median 40 Gy). The overall response rate was 82%, with 20 (22%) complete responses and 55 (60%) partial responses. The one- and two-year local progression free survival rates were 90% and 81%, respectively. The patients who received 48 Gy showed a better local tumor control than those who received less than 48 Gy (Fisher exact test; p = 0.004). No pulmonary complications greater than a RTOG toxicity criteria grade 2 were observed. The experience of stereotactic body frame based radiation therapy appears to be a safe and promising treatment modality for the local management of primary or metastatic lung tumors. The optimal total dose, fractionation schedule and treatment volume need to be determined after a further follow-up of these results.

Positron Emission Tomography (PET) radiotracers in oncology--utility of 18F-Fluoro-deoxy-glucose (FDG)-PET in the management of patients with non-small-cell lung cancer (NSCLC)

PET (Positron Emission Tomography) is a nuclear medicine imaging method, frequently used in oncology during the last years. It is a non-invasive technique that provides quantitative in vivo assessment of physiological and biological phenomena. PET has found its application in common practice for the management of various cancers.Lung cancer is the most common cause of death for cancer in western countries.This review focuses on radiotracers used for PET scan with particular attention to Non Small Cell Lung Cancer diagnosis, staging, response to treatment and follow-up.

Standardized uptake value-based evaluations of solitary pulmonary nodules using F-18 fluorodeoxyglucose-PET/computed tomography

OBJECTIVE

Combined positron emission tomography and computed tomography (PET/CT) might improve the accuracy of PET tracer quantification by providing the exact tumour contour from coregistered CT images. We compared various semiquantitative approaches for the characterization of solitary pulmonary nodules (SPNs) using F-18 fluorodeoxyglucose PET/CT.

METHODS

The final diagnosis of 49 SPNs (46 patients) was based on histopathology (n=33) or patient follow-up (n=16). The regions of interest (ROIs) were drawn around lesions based on the CT tumour contour and mirrored to the coregistered PET images. Quantification of F-18 fluorodeoxyglucose uptake was accomplished by calculating the standardized uptake value (SUV) using three different methods based on: activity from the maximum-valued pixel within the tumour (SUV-max); the mean ROI activity within the transaxial slice containing the maximum-valued pixel (SUV-mean); and the mean activity over the full tumour volume (SUV-vol). SUVs were corrected for partial volume effects and normalized by body surface area, lean body weight, and blood glucose. Recovery coefficients for partial-volume correction were derived from phantom studies. The ability of various SUVs to differentiate between benign and malignant SPNs was determined by calculating the area under the receiver operating characteristic (ROC) curves.

RESULTS

Twenty-six SPNs were malignant and 23 were benign. The area under the ROC curve was 0.78 for SUV-mean, 0.83 for SUV-max, and 0.78 for SUV-vol. SUV-max and its normalizations yielded the highest area under the ROC curve (0.83-0.85); SUV-mean-partial volume corrected-lean body weight resulted in the lowest area under the ROC curve (0.76). At a specificity of 80%, SUV-max-body surface area provided the highest sensitivity (81%) and accuracy (80%) to detect malignant SPN. Using SUV-max with a cutoff of 2.4 at a specificity of 80% resulted in a sensitivity of 62% (accuracy 71%).

CONCLUSION

Various normalizations applied to SUV-max provided the highest diagnostic accuracy for characterization of SPNs. Quantification methods using the exact tumour contour derived from CT in combined PET/CT imaging (ROI mean activity within a single transaxial slice and mean tumour volume activity) did not result in improved differentiation between benign and malignant SPN. Obtaining SUV-max might be sufficient in the clinical setting.

Valor do FDG[18F]-PET/TC como preditor de câncer em nódulo pulmonar solitário

OBJETIVO: Determinar a acurácia diagnóstica da positron emission tomography (tomografia por emissão de pósitrons)/tomografia computadorizada (PET/TC) com deoxiglicose marcada com flúor-18, conhecida como fluorodeoxiglicose (FDG[18F]), na avaliação de nódulo pulmonar solitário (NPS). MÉTODOS: Análise prospectiva de 53 pacientes consecutivos que realizaram PET/TC para avaliação de NPS, entre março de 2005 e maio de 2007. Destes 32 preencheram os critérios de inclusão. As lesões foram avaliadas quanto a sua localização e tamanho, grau de captação do radiofármaco e o standardized uptake value (SUV, valor padronizado de captação) máximo das lesões. Os achados dos estudos de FDG-PET/TC foram correlacionados com outros preditores de malignidade (idade, sexo, tabagismo, tamanho e localização do nódulo). O diagnóstico definitivo foi estabelecido por confirmação histopatológica ou acompanhamento clínico-radiológico por um período mínimo de um ano. RESULTADOS: Encontrados 14 NPS malignos. Após análise da curva ROC, o SUV de 2,5 foi considerado o melhor ponto de corte que identificou corretamente 13 dos 14 NPS malignos. Os resultados abaixo deste ponto de corte mostraram um exame falso positivo para neoplasia num total de 14. O método semiquantitativo apresentou sensibilidade de 92,9%, especificidade de 72,2%, valor preditivo positivo de 72,2%, valor preditivo negativo de 92,9% e acurácia de 81,2%. Na análise multivariada, apenas a localização do nódulo nos lobos superiores (p = 0,048) e o SUV (p = 0,007) demonstraram significância estatística para malignidade no NPS. CONCLUSÕES: Os dados do estudo mostram que o SUV da FDG[18F] é um bom preditor de neoplasia em nódulos pulmonares e com alto valor preditivo negativo, o que oferece grande segurança em afastar presença de malignidade, indicando sua importância na abordagem diagnóstica do nódulo pulmonar.

Predictive and prognostic value of FDG-PET in nonsmall-cell lung cancer: a systematic review

For several years, molecular imaging with (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) has become part of the standard of care in presurgical staging of patients with nonsmall-cell lung cancer (NSCLC), focusing on the detection of malignant lesions at early stages, early detection of recurrence, and metastatic spread. Currently, there is an increasing interest in the role of FDG-PET beyond staging, such as the evaluation of biological characteristics of the tumor and prediction of prognosis in the context of treatment stratification and the early assessment of tumor response to therapy. In this systematic review, the literature on the value of the evolving applications of FDG-PET as a marker for prediction (ie, therapy response monitoring) and prognosis in NSCLC is addressed, divided in sections on the predictive value of FDG-PET in locally advanced and advanced disease, the prognostic value of FDG-PET at diagnosis, after induction treatment, and in recurrent disease. Furthermore, the background and recommendations for the application of FDG-PET for these indications will be discussed.

Role of positron emission tomography in decisions on treatment strategies for pancreatic cancer

BACKGROUND/PURPOSE

The purpose of this study was to estimate the usefulness of positron emission tomography (PET) in deciding on strategies for the treatment of pancreatic cancer. The following two parameters were evaluated: the ability of PET to provide an estimation of the progression of pancreatic cancer, and the ability of PET to predict survival and the effect of chemoradiotherapy.

METHODS

Forty-two patients underwent PET as part of the procedure for making a diagnosis of pancreatic tumors. The maximum standardized uptake value (SUVmax) levels were compared with clinicopathological factors and analyzed.

RESULTS

PET provided a sensitivity of 87%, a specificity of 67%, and an overall accuracy of 85% for the diagnosis of pancreatic malignancy. Tumors with distant metastases showed significantly higher SUV levels than tumors without metastasis. In the patients who received chemoradiotherapy, the overall survival of the group in which SUVmax was less than 7.0 was better than that of the group in which SUVmax was more than 7.0.

CONCLUSIONS

We conclude that PET is a useful tool for determining pathological status and distant metastasis in pancreatic cancer, and for predicting the prognosis of patients receiving chemoradiotherapy.

[Contribution of PET in the follow-up of cerebral metastases in non-small cell lung cancer. A clinical case valuation]

We report a clinical case of a male 44 years old with lung adenocarcinoma with a single brain metastases treated with surgery and radiotherapy. The different PET studies performed during the evolution of the disease were very useful and crucial, firstly in the detection of radiation necrosis and after that when cerebral metastases recurrent appeared twice. The radiographic technique (Brain MRI) and the histopathology after the surgical removal confirmed the PET results. PET imaging is helpful in selected patients with brain metastases in lung cancer.