MR Imaging of Chest Wall Tumors

Carbon-Assisted Minimally Invasive Transtubular Approach for Intercostal Nerve Schwannoma

BACKGROUND AND OBJECTIVES

The intraoperative localization of an intercostal nerve schwannoma (INS) is extremely difficult because the lesion is generally not palpable, and the fluoroscopic visualization of anatomic landmarks in the ribs is unsatisfactory. Using activated carbon suspension to mark the soft-tissue approach could improve INS localization. We present a novel, simple, reproducible carbon-assisted minimally invasive transtubular approach for an INS.

METHODS

The patient was a 57-year-old man with a painful 12th left INS arising below the floating rib. A computed tomography image-guided, tumor-to-skin marking with aqueous carbon suspension was performed 48 hours before surgery. A minimally invasive transtubular approach following the carbon path allowed a precise tumor location.

RESULTS

The INS was completely removed. The patient's thoracic radicular pain was immediately relieved after surgery. He was discharged the following day with residual numbness on the left thoracic side. At the 5-year follow-up, no tumor recurrence was noted in the control MRI.

CONCLUSION

This article presents an alternative novel technique for resecting an intercostal schwannoma. Using a transtubular approach with carbon-marking assistance allowed a tumor gross total resection with immediate pain relief and a successful outcome.

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.

Evaluation of Clinical Performance of TiNi-Based Implants Used in Chest Wall Repair after Resection for Malignant Tumors

In this study, we assessed the outcomes after surgical treatment of thoracic post-excision defects in 15 patients, using TiNi knitted surgical meshes and customized artificial TiNi-based ribs. Methods: Eight patients were diagnosed with advanced non-small cell lung cancer (NSCLC) invading the chest wall, of which five patients were T₃N₀M₀, two were T₃N₁M₀, and one was T₃N₂M₀. Squamous cell carcinoma was identified in three of these patients and adenocarcinoma in five. In two cases, chest wall resection and repair were performed for metastases of kidney cancer after radical nephrectomy. Three-dimensional CT reconstruction and X-ray scans were used to plan the surgery and customize the reinforcing TiNi-based implants. All patients received TiNi-based devices and were prospectively followed for a few years. Results: So far, there have been no lethal outcomes, and all implanted devices were consistent in follow-up examinations. Immediate complications were noted in three cases (ejection of air through the pleural drains, paroxysm of atrial fibrillation, and pleuritis), which were conservatively managed. In the long term, no complications, aftereffects, or instability of the thoracic cage were observed. Conclusion: TiNi-based devices used for extensive thoracic lesion repair in this context are promising and reliable biomaterials that demonstrate good functional, clinical, and cosmetic outcomes.

Can MRI differentiate surrounding vertebral invasion from reactive inflammatory changes in superior sulcus tumor?

OBJECTIVES

Vertebral invasion is a key prognostic factor and a critical aspect of surgical planning for superior sulcus tumors. This study aims to further evaluate MRI features of vertebral invasion in order to distinguish it from reactive inflammatory changes.

METHODS

Between 2000 and 2016, a retrospective study was performed at a single institution. All patients with superior sulcus tumors undergoing surgery, including at least two partial vertebrectomies, were included. An expert radiologist evaluated qualitative and quantitative MRI signal intensity characteristics (contrast-to-noise ratio [CNR]) of suspected involved and non-involved vertebrae. A comparison of CNR of invaded and sane vertebrae was performed using non-parametric tests. Imaging data were correlated with pathological findings.

RESULTS

A total of 92 surgical samples of vertebrectomy were analyzed. The most specific sequences for invasion were T1 and T2 weighted (92% and 97%, respectively). The most sensitive sequences were contrast enhanced T1 weighted fat suppressed and T2 weighted fat suppressed (100% and 80%). Loss of extrapleural paravertebral fat on the T1-weighted sequence was highly sensitive (100%) but not specific (63%). Using quantitative analysis, the optimum cut-off (p < 0.05) to distinguish invasion from reactive inflammatory changes was CNR > 11 for the T2-weighted fat-sat sequence (sensitivity 100%), CNR > 9 for contrast-enhanced T1-weighted fat-suppressed sequence (sensitivity 100%), and CNR < - 30 for the T1-weighted sequence (specificity 97%). Combining these criteria, 23 partial vertebrectomies could have been avoided in our cohort.

CONCLUSION

Qualitative and quantitative MRI analyses are useful to discriminate vertebral invasion from reactive inflammatory changes.

KEY POINTS

• Abnormal signal intensity in a vertebral body adjacent to a superior sulcus tumor may be secondary to direct invasion or reactive inflammatory changes. • Accurate differentiation between invasion and reactive inflammatory changes significantly impacts surgical planning. T1w and T2w are the best sequences to differentiate malignant versus benign bone marrow changes. The use of quantitative analysis improves MRI specificity. • Using contrast media improves the sensitivity for the detection of tumor invasion.

Sternal cavernous hemangioma and reconstruction of the anterior chest wall: a case report

Background

The sternum is considered an unusual tumor site, corresponding to 15% of all thoracic wall tumors. Primary sternal tumors are even rarer and most commonly malignant. We present the case of a young man who consulted with a painful sternal mass, which after its resection is confirmed to be a cavernous hemangioma.

Case presentation

A 39-year-old man, with unremarkable medical history besides a 2-year-long sternal pain, non-irradiated, which worsens over the last few months and is accompanied by the appearance of a sternal palpable mass. On physical exam, there was a bulging of the sternal manubrium, with no inflammatory changes. Thoracic CT scan shows an expansive and lytic lesion of the sternum, compromising the manubrium and extending to the third sternocostal joint, without intrathoracic compromise nor cleavage plane with mediastinal vascular structures. The patient is taken to resection of the mass and sternal reconstruction using prosthetic material and pectoral and fasciocutaneous muscular flaps. Histopathological findings: cavernous hemangioma with negative borders and no other malignant findings.

Conclusions

Sternal hemangiomas can cause defects in the bone structure and show an expansive growth, challenging the differentiation between a benign or malignant lesion. Therefore, they should be considered malignant until shown otherwise. Management involves radical surgery with curative purposes and posterior reconstruction to improve quality of life, as shown with our patient.

MR Imaging of Primary Chest Wall Neoplasms

Primary chest wall neoplasms are uncommon and comprise a heterogeneous group of lesions that may be challenging to classify and diagnose. These tumors may be primary or secondary, malignant or benign, and arise from cartilaginous/osseous structures or soft tissues. The role of magnetic resonance (MR) imaging in the evaluation of chest wall tumors continues to expand given its superior soft tissue contrast relative to computed tomography. MR imaging can facilitate differentiation of neoplasms from normal chest wall structures and other disease processes due to infection and inflammation, and can fully characterize abnormalities by demonstrating the various internal components of complex lesions. It is important that radiologists be able to identify key features of primary chest wall neoplasms on MR imaging to provide focused differential diagnoses and guide patient management.

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.

Magnetic resonance imaging of the mediastinum, chest wall and pleura in children

The acceptance of applications for the use of chest MRI in children has been somewhat slow and selective. The use of MRI to image chest wall lesions is likely the most common and widely used indication, aside from the widespread and somewhat sophisticated use of MRI in imaging the cardiovascular structures of the chest. In this respect, fairly standard variations of T1-W, T2-W and contrast-enhanced imaging can be used, similar to the sequences used for musculoskeletal lesions elsewhere in the body. Imaging of the anterior mediastinal masses should be performed in conjunction with a detailed pre-test clinical examination to determine potential cardiovascular compromise. MRI in the setting of middle mediastinal adenopathy, congenital mediastinal cysts or posterior mediastinal masses, however, has been shown to be more effective and more comprehensive than multidetector CT. Although sonographic imaging is the initial modality of choice for pleural abnormalities, MR imaging is extremely effective and clinically useful in the setting of a potentially ambiguous sonographic examination. Faster imaging protocols are likely to increase the acceptance of MRI to replace multidetector CT for many pediatric chest lesions.