CT, MR, and PET imaging in staging of non-small-cell lung cancer

Beyond whole-body imaging: advanced imaging techniques of PET/MRI

PET/MRI is a hybrid imaging modality that is gaining clinical interest with the first Food and Drug Administration-approved simultaneous imaging system recently added to the clinical armamentarium. Several advanced PET/MRI applications, such as high-resolution anatomic imaging, diffusion-weighted imaging, motion correction, and cardiac imaging, show great potential for clinical use. The purpose of this article is to highlight several advanced PET/MRI applications through case examples and review of the current literature.

[Role of imaging techniques in the TNM classification of non-small cell bronchogenic carcinoma]

The Seventh Edition of the TNM Classification for non-small cell bronchogenic carcinomas include a series of changes in the T and M descriptor, in particular a re-classification of malignant pleural and pericardial effusions and of separated tumour nodes, new tumour size cut-off values and sub-divisions of the T1-T2 and M1 categories. We review these corrections that led to the changes in the staging system that affects stages II-III. Furthermore, we describe and illustrate the role of the different imaging techniques in tumour staging (CT, PET, PET-CT and MRI), highlighting their respective indications, advantages and disadvantages, as well their complementary function.

[Conventional and CT diagnostics of bronchial carcinoma]

A number of important technical advances made in recent years in the area of both digital radiography as well as multidetector computed tomography (MDCT) have improved detection and staging of bronchial carcinoma. The aim of elaborate processing such as temporal subtraction, rib suppression, dual energy subtraction or CAD is to aid the radiologist in detecting lung tumors at the earliest stage possible. For both CT and radiography techniques the differentiation between true and false positive lesions seems to be the biggest challenge. MDCT with multiplanar projections is the imaging method of choice for staging of the extent of local tumor spread (T staging), while N staging and M staging are the domain of positron emission tomography (PET) or even better of integrated PET/CT. Management rules for follow-up of solid and semi-solid lesions seen in CT consider the risks of the patient and are summarized in international guidelines. In 2009 a new 7th edition of the TNM classification was published, which, among other aspects, sub-classifies tumor size more specifically and the presence of a satellite nodule in the tumor lobe is down-staged to T3 and no longer determines tumor resectability. The N staging was not modified. One of the most important new features is the fact that the new classification no longer applies only to non-small cell lung cancer (NSCLC) but also to SCLC and carcinoid tumors.

Functional imaging: CT and MRI

Numerous imaging techniques permit evaluation of regional pulmonary function. Contrast-enhanced CT methods now allow assessment of vasculature and lung perfusion. Techniques using spirometric controlled multi-detector row CT allow for quantification of presence and distribution of parenchymal and airway pathology; xenon gas can be employed to assess regional ventilation of the lungs, and rapid bolus injections of iodinated contrast agent can provide a quantitative measure of regional parenchymal perfusion. Advances in MRI of the lung include gadolinium-enhanced perfusion imaging and hyperpolarized gas imaging, which allow functional assessment, including ventilation/perfusion, microscopic air space measurements, and gas flow and transport dynamics.

CT and MRI of Lung Cancer

Computed tomography (CT) is still the cornerstone of imaging studies in the preoperative staging and post- therapeutic evaluation of lung cancer. The most recent developments in multidetector technology have dramatically improved the temporal and spatial resolution of CT. In the mean time, magnetic resonance imaging (MRI) has not become a routine examination in lung imaging and is today only used as a problem-solving tool in patients in whom CT remains equivocal. This article will describe the current tools developed in the multidetector CT era for evaluating the lung, and state-of-the-art MR examination of the chest. Then, the role of CT and MRI in nodule detection, the distinction between benign and malignant nodules, and the benefit of CT and MRI in the staging and post-therapeutic evaluation of lung cancer will be covered.