MR IMAGING OF THE PLEURA AND CHEST WALL

Diagnostic and Imaging Approaches to Chest Wall Lesions

Chest wall lesions are relatively uncommon and may be challenging once they are encountered on images. Radiologists may detect these lesions incidentally at examinations performed for other indications, or they may be asked specifically to evaluate a suspicious lesion. While many chest wall lesions have characteristic imaging findings that can result in an accurate diagnosis with use of imaging alone, other entities are difficult to distinguish at imaging because there is significant overlap among them. The interpreting radiologist should be familiar with the imaging features of both "do not touch" benign entities (which can be confidently diagnosed with imaging only, with no need for biopsy or resection unless the patient is symptomatic) and lesions that cannot be confidently characterized and thus require further workup. CT and MRI are the main imaging modalities used to assess the chest wall, with each having different benefits and drawbacks. Chest wall lesions can be classified according to their predominant composition: fat, calcification and ossification, soft tissue, or fluid. The identification or predominance of signal intensities or attenuation for these findings, along with the patient age, clinical history, and lesion location, can help establish the appropriate differential diagnosis. In addition, imaging findings in other organs, such as the lungs or upper abdomen, can at times provide clues to the underlying diagnosis. The authors review different chest wall lesions classified on the basis of their composition and highlight the imaging findings that can assist the radiologist in narrowing the differential diagnosis and guiding management. ^©RSNA, 2022.

Imaging Evaluation of Malignant Chest Wall Neoplasms

Neoplasms of the chest wall are uncommon lesions that represent approximately 5% of all thoracic malignancies. These tumors comprise a heterogeneous group of neoplasms that may arise from osseous structures or soft tissues, and they may be malignant or benign. More than 50% of chest wall neoplasms are malignancies and include tumors that may arise as primary malignancies or secondarily involve the chest wall by way of direct invasion or metastasis from intrathoracic or extrathoracic neoplasms. Although 20% of chest wall tumors may be detected at chest radiography, chest wall malignancies are best evaluated with cross-sectional imaging, principally multidetector computed tomography (CT) and magnetic resonance (MR) imaging, each of which has distinct strengths and limitations. Multidetector CT is optimal for depicting bone, muscle, and vascular structures, whereas MR imaging renders superior soft-tissue contrast and spatial resolution and is better for delineating the full extent of disease. Fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT is not routinely performed to evaluate chest wall malignancies. The primary functions of PET/CT in this setting include staging of disease, evaluation of treatment response, and detection of recurrent disease. Ultrasonography has a limited role in the evaluation and characterization of superficial chest wall lesions; however, it can be used to guide biopsy and has been shown to depict chest wall invasion by lung cancer more accurately than CT. It is important that radiologists be able to identify the key multidetector CT and MR imaging features that can be used to differentiate malignant from benign chest lesions, suggest specific histologic tumor types, and ultimately guide patient treatment. (©)RSNA, 2016.

The imaging spectrum of pulmonary tuberculosis

Tuberculosis has still an important impact on public health because it is an important cause of death, particularly in developing countries. On the other hand recent studies have shown that tuberculosis is again becoming concentrated in big cities of Western Europe, especially among immigrants, drug addicts, poor people, and the homeless, despite progress in reducing national rates of the disease. Diagnostic imaging is challenging for radiologists because signs of tuberculosis may easily mimic other diseases such as neoplasms or sarcoidosis. Clinical signs and symptoms in affected adults can be non-specific and a high level of pre-test clinical suspicion based on history is fundamental in the diagnostic work-up. Impact of tuberculosis in the world is extremely important considering the high incidence estimated during 2011 that was 8.7 million cases. This article gives a review of imaging patterns of chest tuberculosis as may be detected on conventional radiography and computerized tomography (CT). The main aim is to improve radiologist's familiarity with the spectrum of imaging features of this disease and facilitate timely diagnosis. Furthermore, we consider the emerging role of alternative methods of imaging, such as magnetic resonance imaging (MRI), that can be helpful and highly accurate for a better definition of some signs of tuberculosis.

Multimodality imaging of cardiothoracic lymphoma

Lymphoma is the most common hematologic malignancy and represents approximately 5.3% of all cancers. The World Health Organization published a revised classification scheme in 2008 that groups lymphomas by cell type and molecular, cytogenetic, and phenotypic characteristics. Most lymphomas affect the thorax at some stage during the course of the disease. Affected structures within the chest may include the lungs, mediastinum, pleura, and chest wall, and lymphomas may originate from these sites as primary malignancies or secondarily involve these structures after arising from other intrathoracic or extrathoracic sources. Pulmonary lymphomas are classified into one of four types: primary pulmonary lymphoma, secondary pulmonary lymphoma, acquired immunodeficiency syndrome-related lymphoma, and post-transplantation lymphoproliferative disorders. Although pulmonary lymphomas may produce a myriad of diverse findings within the lungs, specific individual features or combinations of features can be used, in combination with secondary manifestations of the disease such as involvement of the mediastinum, pleura, and chest wall, to narrow the differential diagnosis. While findings of thoracic lymphoma may be evident on chest radiography, computed tomography has traditionally been the imaging modality used to evaluate the disease and effectively demonstrates the extent of intrathoracic involvement and the presence and extent of extrathoracic spread. However, additional modalities such as magnetic resonance imaging of the thorax and (18)F-FDG PET/CT have emerged in recent years and are complementary to CT in the evaluation of patients with lymphoma. Thoracic MRI is useful in assessing vascular, cardiac, and chest wall involvement, and PET/CT is more accurate in the overall staging of lymphoma than CT and can be used to evaluate treatment response.

The role of imaging for the surgeon in primary malignant bone tumors of the chest wall

Primary malignant chest wall tumors are rare. The most frequent primary malignant tumor of the chest wall is chondrosarcoma, less common are primary bone tumors belonging to the Ewing Family Bone Tumors (EFBT), or even rarer are osteosarcomas. They represent a challenging clinical entities for surgeons as the treatment of choice for these neoplasms is surgical resection, excluding EFBT which are normally treated by a multidisciplinary approach. Positive margins after surgical procedure are the principal risk factor of local recurrence, therefore to perform adequate surgery a correct preoperative staging is mandatory. Imaging techniques are used for diagnosis, to determine anatomic site and extension, to perform a guided biopsy, for local and general staging, to evaluate chemotherapy response, to detect the presence of a recurrence. This article will focus on the role of imaging in guiding this often difficult surgery and the different technical possibilities adopted in our department to restore the mechanics of the thoracic cage after wide resections.

Detection of Pulmonary tuberculosis: comparing MR imaging with HRCT

BACKGROUND

Computer Tomography (CT) is considered the gold standard for assessing the morphological changes of lung parenchyma. Although novel CT techniques have substantially decreased the radiation dose, radiation exposure is still high. Magnetic Resonance Imaging (MRI) has been established as a radiation- free alternative to CT for several lung diseases, but its role in infectious diseases still needs to be explored further. Therefore, the purpose of our study was to compare MRI with high resolution CT (HRCT) for assessing pulmonary tuberculosis.

METHODS

50 patients with culture-proven pulmonary tuberculosis underwent chest HRCT as the standard of reference and were evaluated by MRI within 24 h after HRCT. Altogether we performed 60 CT and MRI examinations, because 10 patients were also examined by CT and MRI at follow- up. Pulmonary abnormalities, their characteristics, location and distribution were analyzed by two readers who were blinded to the HRCT results.

RESULTS

Artifacts did not interfere with the diagnostic value of MRI. Both HRCT and MRI correctly diagnosed pulmonary tuberculosis and identified pulmonary abnormalities in all patients. There were no significant differences between the two techniques in terms of identifying the location and distribution of the lung lesions, though the higher resolution of MRI did allow for better identification of parenchymal dishomogeneity, caseosis, and pleural or nodal involvement.

CONCLUSION

Technical developments and the refinement of pulse sequences have improved the quality and speed of MRI. Our data indicate that in terms of identifying lung lesions in non-AIDS patients with non- miliary pulmonary tuberculosis, MRI achieves diagnostic performances comparable to those obtained by HRCT but with better and more rapid identification of pulmonary tissue abnormalities due to the excellent contrast resolution.

Ultrasonography is superior to computed tomography and magnetic resonance imaging in determining superficial resection margins of malignant chest wall tumors

OBJECTIVE

The purpose of this study was to retrospectively analyze results obtained in 22 patients affected by malignant high-grade chest wall tumors evaluated preoperatively by ultrasonography as well as other imaging techniques.

METHODS

Twenty-two patients with chest wall high-grade sarcomas routinely underwent computed tomography, magnetic resonance imaging, total body scintigraphy, and ultrasonography. Ultrasonography was always performed by the same person using an ultrasonography system with a 5- to 13-MHz probe and with color Doppler evaluation of the lesion. Scans were done with the patient positioned as during surgery. Tumor lateral margins were identified, and a line was marked at 4 cm. In 8 patients with local recurrence, the presence of micronodules was also studied. Results of computed tomography, magnetic resonance imaging, and ultrasonography were compared with the surgical specimens.

RESULTS

Histologically, all surgical specimens excised according to ultrasonographic margins showed wide margins. Ultrasonography showed micronodules in 6 of 8 patients with local recurrence; histologically, they were all identified as sarcoma nodules. Ultrasonography failed in particular with cervical-mediastinal vessels.

CONCLUSIONS

Our results confirm that ultrasonography is feasible and reliable in the study of superficial margins and for detection of micronodules of less than 0.5 cm in diameter.

[Inflammation and pleural fibrosis]

Pleural effusions are frequent. There are many etiologies of inflammatory pleural effusions and of pleural fibrosis. Imaging (standard radiography, ultrasound, scanner, MRI) is important for visualization, localization, and assessment of abundance. Exsudative (inflammatory) effusion can sometimes be distinguished from hydrothorax. Imaging signs generally remain nonspecific but can contribute to the etiological diagnosis. In particular, a CT scan of the chest, without and with contrast injection (tissue impregnation) can, in addition to the study of pleural space, enable an visual assessment of the visceral and parietal pleura, the adjacent chest wall, and the adjacent pulmonary parenchyma or vessels, which may provide diagnostic clues. Imaging can also contribute to therapeutic guidance.

Radiology in pleural disease: State of the art

Diseases of the pleura and pleural space are common and present a significant contribution to the workload of the chest radiologist. The radiology department plays a crucial role in the imaging and management of pleural disease. This review aims to describe and illustrate the appearances of common pleural pathologies on various radiological modalities including plain film, ultrasound, CT, magnetic resonance imaging and positron emission tomography. The review will also address the state-of-the-art techniques used to image pleural disease and discuss image-guided intervention in the management of pleural disease.

Plain film / MR imaging correlation in heart disease

This article reviews common cardiovascular pathologies that can be noted first on plain film when previously unsuspected, and then illustrates how cross-sectional imaging can provide the follow-up information needed to make a diagnosis. First reviewed are the normal cardiac structures and contours as seen on the plain film of the chest, followed by specific types of pathologies as seen in older adults; patients with lung cancer invading the heart, pericardium, or large vessels; and postsurgical and posttraumatic findings. Also provided is a review of non-cardiac-related areas of plain film and cross-sectional imaging correlation. It is hoped that the reader gains a better understanding and appreciation for the great value of cross-sectional imaging, and the power of the plain film in helping detect and recognize thoracic pathology.