The anterior mediastinum: anatomy and imaging procedures

Abstract

The mediastinum is divided into compartments (anterior, middle, posterior) on the basis of lateral chest radiographs. Several anatomical and radiological classifications of the mediastinum are reported in the literature. Most mediastinal abnormalities are initially suspected following chest radiography; the need for further investigation and the most appropriate imaging modality are largely dictated by the tentative diagnosis made on this examination. Although routine chest radiography initiates the evaluation of mediastinal disorders, it is rarely diagnostic: notable exceptions are teeth or bones within a mass, which are diagnostic of a teratoma; air/fluid levels suggest an oesophageal origin, hernia, cyst, or abscess. Chest radiography is followed by spiral computed tomography (sCT). However, even sCT with contrast material is occasionally diagnostic (a confident diagnosis can be made of some lesions such as mature teratoma and mediastinal goiter) but is usually sufficient for preoperative evaluation before mediastinotomy or mediastinoscopy: it is instrumental in planning further diagnostic workup. In certain cases, magnetic resonance imaging (MRI) may be complementary to sCT, but its use is not considered routine. Besides, although the anterior mediastinum is suitable for sonographic examination, the diagnostic value of ultrasonography has not been fully exploited. Thyroid scanning with radioactive iodine is useful in identifying and evaluating masses of suspected thyroid origin. The role of fluorodeoxyglucose positron emission tomography (FDG-PET) in mediastinal diseases continues to be evaluated: it has potential for differentiating between benign and malignant disease and is expected to play a more extensive role in the imaging of mediastinal neoplasms in the future. In this paper, the radiological features of masses located in the anterior mediastinum are discussed, with particular reference to radiographic and CT patterns useful to the clinician's everyday practice.

Diffusion-weighted magnetic resonance imaging of thymoma: ability of the Apparent Diffusion Coefficient in predicting the World Health Organization (WHO) classification and the Masaoka-Koga staging system and its prognostic significance on disease-free survival

“…Limited data are available on quantitative assessment of thymic epithelial tumours (TETs) by using diffusionweighted magnetic resonance imaging (DW-MRI) from small cohorts of studies which considered various anterior mediastinal tumours, although those studies did not attempt to differentiate thymomas based on WHO and MasaokaKoga classifications by using the ADC [11][12][13][14][15][16][17][18]. More recently, a study involving 30 patients with TETs has demonstrated the ability of ADC in differentiating low-risk from high-risk tumours, and early from advanced disease [19]. Despite such promising results, that study is influenced by a strong correlation between Jeong and Masaoka-Koga classifications and by the inclusion of thymic carcinomas in the advanced disease group which leads to further decrease of the mean ADC value of this group compared with the early disease group [19,20].…”

“…More recently, a study involving 30 patients with TETs has demonstrated the ability of ADC in differentiating low-risk from high-risk tumours, and early from advanced disease [19]. Despite such promising results, that study is influenced by a strong correlation between Jeong and Masaoka-Koga classifications and by the inclusion of thymic carcinomas in the advanced disease group which leads to further decrease of the mean ADC value of this group compared with the early disease group [19,20]. Moreover, perfusion-sensitive ADC values have been used for analyses by including the b value of 0 sec/mm2 for ADC computation, obtaining a measured signal which reflects not only pure molecular water diffusion, but also Bpseudo-diffusion^ resulting from fast-moving water molecules from blood flow in vessels and capillaries [21][22][23][24][25].…”

The Diagnostic Utility of Cardiac-Gated Magnetic Resonance Imaging for Assessing Surgical Resectability of Mediastinal Tumors

“…With the advent of improved and faster MRI techniques, MRI may be an alternative or complementary modality in imaging of mediastinal tumors [5,[30][31][32][33]. However, due to its higher cost, increased scan time, and reduced availability compared to CT, MRI is not routinely used [5].…”

Gogus Radyograminin Degerlendirilmesinde Temel Ilkeler ve Fokal Akciger Hastaliklarinda Radyografi

“…Anterior mediasten orta mediasten ile sternum arasında kalan bölgeyi içerir. Posterior mediasten ise orta mediasten ile torasik vertebralar arasındaki kısımdır [5,6]. Radyolojik pratikte superior mediasteni ayırmadan anterior, orta ve posterior olarak üç bölümde değerlendirilebilir.…”

“…Akciğer grafisi; pnömoni, plevral effüzyon, akciğer ödemi, pnömotoraks gibi klinik olarak pulmoner emboliyi taklit eden patolojileri ekarte etmek veya saptamak için kullanılır [20]. Pulmoner embolinin başlıca akciğer grafi bulguları arasında Westermark bulgusu (bölgesel oligemi ve lüsensi artışı), Hampton hörgücü (plevra tabanlı genellikle üçgen veya kama şeklinde periferik konsolidasyon), Fleischner bulgusu (santral pulmoner arterin pulmoner hipertansiyon veya embolinin yarattığı distansiyon nedeniyle genişlemesi), boğum (knuckle) bulgusu (pulmoner arterde ani kesilme veya incelme), alt zonlarda çizgisel atelektaziler, diyaframda yükselme ve plevral effüzyon sayılabilir [5,[19][20][21][22][23].…”