Elastographic and contrast-enhanced ultrasound features of a benign schwannoma of the common fibular nerve

Imaging of Peripheral Intraneural Tumors: A Comprehensive Review for Radiologists

BACKGROUND/OBJECTIVES

Intraneural tumors (INTs) pose a diagnostic challenge, owing to their varied origins within nerve fascicles and their wide spectrum, which includes both benign and malignant forms. Accurate diagnosis and management of these tumors depends upon the skills of the radiologist in identifying key imaging features and correlating them with the patient's clinical symptoms and examination findings.

METHODS

This comprehensive review systematically analyzes the various imaging features in the diagnosis of intraneural tumors, ranging from basic MR to advanced MR imaging techniques such as MR neurography (MRN), diffusion tensor imaging (DTI), and dynamic contrast-enhanced (DCE) MRI.

RESULTS

The article emphasizes the differentiation of benign from malignant lesions using characteristic MRI features, such as the "target sign" and "split-fat sign" for tumor characterization. The role of advanced multiparametric MRI in improving biopsy planning, guiding surgical mapping, and enhancing post-treatment monitoring is also highlighted. The review also underlines the importance of common diagnostic pitfalls and highlights the need for a multi-disciplinary approach to achieve an accurate diagnosis, appropriate treatment strategy, and post-therapy surveillance planning.

CONCLUSIONS

In this review, we illustrate the main imaging findings of intraneural tumors, focusing on specific MR imaging features that are crucial for an accurate diagnosis and the differentiation between benign and malignant lesions.

Contrast-enhanced ultrasonography for evaluation of the blood perfusion of sciatic nerves in healthy dogs

Blood supply to the peripheral nerves is essential for fulfilling their structural and functional requirements. This prospective, experimental, exploratory study aimed to assess the feasibility of contrast-enhanced ultrasonography (CEUS) for evaluating blood perfusion of the sciatic nerve in normal dogs. Contrast-enhanced ultrasonography examinations were performed on the bilateral sciatic nerves after bolus injection of Sonazoid™ (0.015 mL/kg) in 12 healthy Beagles for 150 s. Then, qualitative assessment of the wash-in timing, degree and enhancement patterns, and quantitative measurement of the peak intensity and time to peak intensity were performed from the sciatic nerve. The results were compared to those obtained from the adductor muscle around the nerve and caudal gluteal artery. After contrast agent injection, the sciatic nerve was enhanced at approximately 13-14 s, immediately after wash-in of the caudal gluteal artery. The peak intensity of the sciatic nerve was significantly lower than that of the caudal gluteal artery and higher than that of the adductor muscle. The time to peak intensity was significantly slower than that of the caudal gluteal artery; but was not significantly different from that of the adductor muscle. There were no significant differences in the peak intensity and time to peak intensity between the left and right sciatic nerves. These results demonstrate the feasibility of CEUS to assess blood perfusion of the sciatic nerve in healthy dogs qualitatively and quantitatively. This result from healthy dogs could serve as a reference for further studies that evaluate the sciatic nerve under pathological conditions.

Ultrasound and MR imaging of peripheral nerve tumors: the state of the art

Peripheral nerve sheath tumors are a heterogeneous subgroup of soft tissue tumors that either arise from a peripheral nerve or show nerve sheath differentiation. On imaging, direct continuity with a neural structure or location along a typical nerve distribution represents the most important signs to suggest the diagnosis. Ultrasound and magnetic resonance imaging are the best modalities to evaluate these lesions. First, it is necessary to differentiate between a true tumor and a non-neoplastic nerve condition such as a neuroma, peripheral nerve ganglion, intraneural venous malformation, lipomatosis of nerve, or nerve focal hypertrophy. Then, with a combination of clinical features, conventional and advanced imaging appearances, it is usually possible to characterize neurogenic tumors confidently. This article reviews the features of benign and malignant peripheral nerve sheath tumors, including the rare and recently described tumor types. Furthermore, other malignant neoplasms of peripheral nerves as well as non-neoplastic conditions than can mimick neurogenic tumor are herein discussed.

Shear wave elastography of the common fibular nerve at the fibular head

ABSTRACT

The aim of this work is to study the sonoelastographic features of the common fibular nerve in healthy adult subjects.This is an observational cross-sectional study. Shear wave elastography was used to evaluate the common fibular nerve. Crosssectional area and stiffness were measured in kilopascal (kPa) and meters/second (m/s).The study included 82 common fibular nerves in 41 healthy adult subjects. The mean cross-sectional area of the common fibular nerve at the fibular head was 8.7 mm2. Positive correlation was noted between stiffness measurements between short and long axes by both methods. The mean stiffness of the common fibular nerve in the short axis was 22.5 kPa, and in the long axis (LA) was 35.4 kPa. Positive correlation was noted between height and stiffness measured by both methods in both axes by kPa. In m/s, the mean stiffness of the common fibular in the short axis was 2.6 m/s, and while in the LA was 3.4 m/s. Height showed positive correlation with both axes for stiff measurements in m\s. Weight showed positive correlation with stiffness measurements by m/s in the LA.The results obtained in our study could be a reference point for evaluating stiffness of the common fibular nerve in research involving different pathologies.

Multimodal ultrasound imaging of primary thyroid schwannoma: A case report

RATIONALE

Primary schwannoma of the thyroid gland is very rare, and its preoperative diagnosis is difficult.

PATIENT CONCERNS

We report the case of a thyroid nodule in an 18-year-old woman, who presented with a mass in her left neck with stiffness and normal thyroid function. However, the patient complained of numbness in her left upper extremity, and ultrasound (US) features were suspicious of malignancy.

DIAGNOSES

Multimodal US imaging was performed using B-mode, color doppler, ultrasonic elastography (UE), and contrast-enhanced ultrasound (CEUS). CEUS revealed heterogeneous enhancement and "target sign" within the tumor. The nodule was suspicious for malignancy and classified as TI-RADS 4b, while the elasticity values measured by UE indicated a benign lesion. Fine needle aspiration (FNA) was subsequently performed in the markedly contrast-enhanced area for biopsy. Cytological results revealed a benign schwannoma.

INTERVENTION

The patient underwent left lobe resection. Postoperative pathology confirmed it to be a primary benign schwannoma of the thyroid.

OUTCOMES

After thyroidectomy, the patient was followed-up with US. At present, all laboratory tests and thyroid imaging are normal, and the numbness of the left upper limb has disappeared.

LESSONS

The combination of different US modalities is useful for the diagnosis of thyroid lesions. FNA performed under CEUS guidance improves the accuracy of biopsy sampling.

High-resolution ultrasonography and shear-wave sonoelastography of a cystic radial nerve Schwannoma

Peripheral nerve tumors are often evaluated with magnetic resonance imaging (MRI), although there are many advantages offered with high-resolution ultrasonography (HRUS). This case report emphasizes the value of HRUS in the diagnosis and management of a patient with a cystic radial nerve Schwannoma. In addition, information on tumor stiffness, obtained with shear-wave sonoelastography (SWE), is presented.