Do Hemodynamic Studies of Stage T1 Lung Cancer Enable the Prediction of Hilar or Mediastinal Nodal Metastasis?

Undetected lymph node metastases in presumed early stage NSCLC SABR patients

INTRODUCTION

Stereotactic body radiation therapy (SBRT, also called stereotactic ablative body radiation SABR) is the treatment of choice for many patients with early-stage non-small cell lung cancer (NSCLC), including those who are unfit for surgery or refuse surgery.

AREAS COVERED

In an effort to develop optimal staging for the evaluation of SBRT candidates, we review the performance of available lymph node staging methods, as well as risk factors for lymph node involvement. Pubmed was searched to identify relevant literature. Current staging methods for NSCLC, including Positron Emission Tomography/Computed Tomography(PET/CT) and endobronchial ultra sound (EBUS), have limited sensitivities. Expert commentary: There are several factors, including primary tumor location, tumor size, and histology that are possibly associated with the sensitivity of PET/CT to detect mediastinal lymph node metastasis. Small lymph node metastases typically remain undetected by PET/CT. Therefore invasive nodal staging procedures are indicated for most presumed early-stage NSCLC patients, but these also have limited sensitivity. Occult lymph node metastasis is associated with adverse outcome in NSCLC. Moreover, there is overwhelming evidence that certain patients who have lymph node metastases detected at the time of surgery derive an overall survival benefit from adjuvant therapies. It remains to be determined if improved detection of lymph node metastases in SABR candidates can indeed improve prognosis.

A practical algorithmic approach to the diagnosis and management of solitary pulmonary nodules: part 1: radiologic characteristics and imaging modalities

The solitary pulmonary nodule (SPN) is frequently encountered on chest imaging and poses an important diagnostic challenge to clinicians. The differential diagnosis is broad, ranging from benign granulomata and infectious processes to malignancy. Important concepts in the evaluation of SPNs include the definition, morphologic characteristics via appropriate imaging modalities, and the calculation of pretest probability of malignancy. Morphologic differentiation of SPN into solid or subsolid types is important in the choice of follow-up and further management. In this first part of a two-part series, we describe the morphologic characteristics and various imaging modalities available to further characterize SPN. In Part 2, we will describe the determination of pretest probability of malignancy and an algorithmic approach to the diagnosis of SPN.

Clinical imaging of tumor angiogenesis

Angiogenesis is an integral part of tumor growth and invasion. This has led to the emergence of several antiangiogenic therapies and stimulated efforts to accurately evaluate the extent of angiogenesis before and in response to anticancer treatment. The most commonly used approach has been the assessment of new vessel formation in histological samples. However, it is becoming apparent that this is insufficient for a full understanding of tumor physiology and for in vivo guidance of cancer management. Imaging has the potential to provide noninvasive and repeatable assessment of the angiogenic process. Imaging approaches use a variety of modalities and are aimed at either assessment of the functional integrity of tumor vasculature or assessment of its molecular status. This review summarizes the aims and methods of clinical tumor angiogenesis imaging, including present technologies and ones that will be developed within the next 5-10 years.

Correlation between dynamic CT findings and pathological prognostic factors of small lung adenocarcinoma

PURPOSE

To compare pathological prognostic factors of small lung adenocarcinomas with findings of contrast-enhanced dynamic computed tomography (CT) scans.

MATERIALS AND METHODS

We evaluated 108 patients with lung adenocarcinomas ≤ 30 mm in diameter who underwent dynamic CT scans (80-96 ml of contrast material, 2.5-3 ml/s injection) and tumor resections. Attenuation values of both the early phase (20-36 s after injection) and delayed phase (91-95 s) of enhanced CT minus baseline plain CT attenuation were defined as ΔEarly and ΔDelay. The early enhancement ratio was defined as ΔEarly/ΔDelay×100 (%). We statistically compared the early enhancement ratios between the presence and absence of each pathological finding (lymph node metastasis, lymphatic permeation, vascular invasion, and pleural involvement). Patients were divided into 2 groups based on early enhancement ratios: ratio ≥50% (n = 41) and ratio <50% (n = 67) and we statistically compared these 2 groups.

RESULTS

The early enhancement ratios in the group with lymph node metastasis, lymphatic permeation, and vascular invasion were significantly lower than in the group without these findings (24.9% vs 48.6%; P < 0.001, 30.0% vs 47.5%; P = 0.002, and 26.5% vs 47.0%; P = 0.002, respectively). Lymph node metastasis, lymphatic permeation, and vascular invasion were significantly more frequent in tumors with a ratio <50% than in tumors with ratio ≥50% (P < 0.001, P = 0.008, and P = 0.005, respectively).

CONCLUSIONS

There was a significant correlation between the early enhancement ratio of enhanced dynamic CT and the pathological prognostic factors in small lung adenocarcinomas.

Molecular imaging with dynamic contrast-enhanced computed tomography

Dynamic contrast-enhanced computed tomography (DCE-CT) is a quantitative technique that employs rapid sequences of CT images after bolus administration of intravenous contrast material to measure a range of physiological processes related to the microvasculature of tissues. By combining knowledge of the molecular processes underlying changes in vascular physiology with an understanding of the relationship between vascular physiology and CT contrast enhancement, DCE-CT can be redefined as a molecular imaging technique. Some DCE-CT derived parameters reflect tissue hypoxia and can, therefore, provide information about the cellular microenvironment. DCE-CT can also depict physiological processes, such as vasodilatation, that represent the physiological consequences of molecular responses to tissue hypoxia. To date the main applications have been in stroke and oncology. Unlike some other molecular imaging approaches, DCE-CT benefits from wide availability and ease of application along with the use of contrast materials and software packages that have achieved full regulatory approval. Hence, DCE-CT represents a molecular imaging technique that is applicable in clinical practice today.

Staging of non-small cell lung cancer (NSCLC): a review

Lung cancer remains the most common cause of cancer-related mortality in Scotland, accounting for 28.9% of all cancer deaths in 2007. (1) Current guidelines recommend assessment of patient fitness and operability by a multi-disciplinary team when selecting management options. (2-6) Two of the most important prognostic markers are the stage of disease and ECOG performance status. The most commonly used cancer staging system is the tumour, node, metastasis (TNM) staging system, which is maintained by the American Joint Committee on Cancer (AJCC) and the International Union Against Cancer (UICC). In 1998, the International Association for the Study of Lung Cancer (IASLC) established The Lung Cancer Staging Project, collecting data on over 100,000 patients diagnosed with lung cancer between 1990-2000 worldwide, in order to revise the 6th edition TNM staging system for non-small cell lung cancer (NSCLC).(7) The 7th edition was published in late 2009. This review of staging in NSCLC, includes a summary of the different staging techniques currently available and the 7th edition TNM staging system for NSCLC.(8).

Mediastinal nodal staging of nonsmall cell lung cancer using integrated 18F-FDG PET/CT in a tuberculosis-endemic country: diagnostic efficacy in 674 patients

BACKGROUND

Integrated (18)fluorine fluorodeoxyglucose ((18)F-FDG) positron emission tomography/computed tomography (PET/CT) has shown somewhat variable sensitivity and specificity for mediastinal nodal staging in granulomatous disease endemic areas. The purpose of the study was to prospectively evaluate the efficacy of PET/CT for mediastinal nodal staging in nonsmall cell lung cancer (NSCLC) patients in a tuberculosis-endemic country.

METHODS

Prospective assessment of the diagnostic efficacy of integrated PET/CT for detecting mediastinal nodal metastasis was performed in 674 patients (M:F ratio = 502:172; mean age, 61 years) with NSCLC. Patients underwent an integrated PET/CT examination and subsequent surgical nodal staging (by mediastinoscopy only in 121 patients and by thoracotomy in 553). Nodes showing greater (18)F-FDG uptake than mediastinum at PET without benign calcification or high attenuation >70 household unit (HU) at unenhanced CT were regarded as being positive for malignancy. The histologic nodal assessment results were used as reference standards.

RESULTS

Of 2477 mediastinal nodal stations evaluated in 674 patients, 275 (11%) stations in 180 (27%) patients proved to be malignant. On a per-person basis, the overall sensitivity, specificity, and accuracy of PET/CT for mediastinal nodal staging were 61% (110 of 180), 96% (473 of 494), and 86% (583 of 674), respectively. On a per-nodal station basis, they were 46% (126 of 275), 98% (2154 of 2202), and 92% (2280 of 2477).

CONCLUSIONS

Integrated PET/CT provides high specificity and reasonably high accuracy, but somewhat low sensitivity for mediastinal nodal staging of NSCLCs. The high specificity is achieved at the expense of sensitivity by interpreting calcified nodes or nodes with high attenuation at CT, even with high FDG uptake at PET, as benign in a tuberculosis-endemic region.

Efficacy of Helical Dynamic CT Versus Integrated PET/CT for Detection of Mediastinal Nodal Metastasis in Non-Small Cell Lung Cancer

OBJECTIVE

The purpose of our study was to compare the diagnostic efficacies of helical dynamic CT and integrated PET/CT for the prediction of mediastinal nodal metastasis in stage T1 non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

One hundred forty-three patients with stage T1 NSCLC underwent both helical dynamic CT and integrated PET/CT followed by surgical nodal staging. In helical dynamic CT, patients were regarded to have stage N2 disease when a nodule showed a peak enhancement > or = 110 H or a net enhancement > or = 60 H. In integrated PET/CT, nodes were regarded as positive for malignancy when they showed > or = 3.5 in maximum standardized uptake value with a discrete margin and more 18F-FDG uptake than mediastinal structures. Sensitivities, specificities, and accuracies for mediastinal nodal metastasis detection were compared for helical dynamic CT and integrated PET/CT using the McNemar test.

RESULTS

Of the 143 patients, 34 (24%) had positive mediastinal nodes. The sensitivity, specificity, and accuracy for mediastinal nodal metastasis prediction on helical dynamic CT were 65% (22 of 34 patients), 89% (97 of 109), and 83% (119 of 143), respectively, whereas those on integrated PET/CT were 56% (19 of 34), 100% (109 of 109), and 90% (128 of 143). The p values were 0.664, < 0.001, and 0.015.

CONCLUSION

In stage T1 NSCLC, contrast-enhanced helical dynamic CT better predicts, but not significantly so, mediastinal nodal metastasis than PET/CT, whereas PET/CT shows perfect specificity and higher accuracy than helical dynamic CT.

Solitary Pulmonary Nodules: Detection, Characterization, and Guidance for Further Diagnostic Workup and Treatment

OBJECTIVE

The purpose of our study is to improve radiologists' understanding of the clinical issues involved in making a diagnosis and to guide further diagnostic workup and treatment of solitary pulmonary nodules (SPNs).

CONCLUSION

Information on the morphologic and hemodynamic characteristics of SPNs provided by dynamic helical CT, with high specificity and reasonably high accuracy, can be used for initial assessment. PET/CT is more sensitive at detecting malignancy than dynamic helical CT, and all malignant nodules may be potentially diagnosed as malignant by both techniques. Therefore, PET/CT may be selectively performed to characterize SPNs that show indeterminate results at dynamic helical CT.

Stage T1 non-small cell lung cancer: preoperative mediastinal nodal staging with integrated FDG PET/CT--a prospective study

PURPOSE

To prospectively evaluate the sensitivity and specificity of integrated fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) and computed tomography (CT) (PET/CT) for the preoperative diagnosis of mediastinal nodal metastasis in stage T1 non-small cell lung cancer (NSCLC), with surgical and histologic results as reference standards.

MATERIALS AND METHODS

Institutional review board approval and informed consent were obtained. From June 2003 to February 2005, 150 patients (89 men and 61 women; mean age, 59 years) with stage T1 NSCLC at stand-alone CT underwent integrated PET/CT and surgical staging. Two observers (one radiologist and one nuclear medicine physician) evaluated prospectively and in consensus the mediastinal nodes by analyzing both PET (functional) and CT (anatomic) images. Nodal stages were determined by using the American Joint Committee on Cancer staging system and surgical and histologic findings as the reference standard. Statistical evaluation of malignant lymph nodes was performed on per-nodal-station and per-person bases.

RESULTS

A total of 568 mediastinal nodal stations were evaluated. Nodes were positive for malignancy in 34 (23%) of 150 patients and 55 (10%) of 568 nodal stations. For depiction of malignant nodes, the respective sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of integrated PET/CT were 42% (23 of 55), 100% (513 of 513), 100% (23 of 23), 94% (513 of 545), and 94% (536 of 568) on per-nodal-station basis and 47% (16 of 34), 100% (116 of 116), 100% (16 of 16), 87% (116 of 134), and 88% (132 of 150) on a per-patient basis.

CONCLUSION

Integrated FDG PET/CT provides high specificity and positive predictive value of mediastinal nodal staging in stage T1 NSCLC, although the sensitivity is low.