Peripheral nerve imaging: Not only cross-sectional area

Abstract

suggest to use ultrasound (US) for nerve evaluation due to the fact that, in sever anatomical area, magnetic resonance imaging is not able to give additional in formations. US could be considered the firstchoice approach for the assessment of peripheral nerves. The relative drawback of peripheral nerve US is the long learning curve and the deep anatomic competence to evaluate even small nerves. In the recent years, the role of US in peripheral nerve evaluation has been widened. In the past, nerve US was mainly used to assess nerve cross sectional area, but now more advanced mea surements and considerations are desirable and can boost the role of peripheral nerve US. Nerve echotexture evaluation was defined in 2010: The ratio between the hypoechoic and hyperechoic areas of peripheral nerves on US was called "nerve density". For evaluation of patients who have peripheral neuropathies, the role of peripheral nerve is US wider than simple crosssectional area evaluation. Quantitative measurements describing the internal fascicular echotexture of peripheral nerves introduce the concept of considering US as a possible quantitative imaging biomarker technique. The potential of nerve US has started to be uncovered. It seems clear that only crosssectional area measurement is no more sufficient for a comprehensive US evaluation of peripheral nerves. AbstractPeripheral nerve imaging is recognized as a complement to clinical and neurophysiological assessment in the evaluation of peripheral nerves with the ability to impact patient management, even for small and difficult nerves.

Diagnostic utility of the sonographic median to ulnar nervecross-sectional area ratio in carpal tunnel syndrome

“…The best descriptive measurement was reported as the m-CSA at the level of the pisiform bone. However, the m-CSA cut-off value for the diagnosis of CTS varied from 9 mm 2 to 15 mm 2 among studies (7)(8)(9). Inconsistencies between studies might be due to the differences between selection criteria of patients and controls, the methods used in the diagnosis of CTS, electrodiagnostic methods, and measured CSA levels (4)(5)(6)(7)(8).…”

“…The most commonly used ultrasonographic measurement for the diagnosis of CTS is measurement of the median nerve cross-sectional area at different levels of the carpal tunnel. In recent years, quantitative measurements such as nerve density and fascicular ratio were added in the evaluation of peripheral nerves (6,7). Enlargement of the median nerve at the level of the proximal carpal tunnel has been accepted as the most predictive criterion for CTS.…”

Peripheral Nerves: Not Only Cross-sectional Area in the Era of Radiomics

“…In recent years, the role of US and MRI in peripheral nerve evaluation has expanded far beyond simple CSA evaluation. 4 The development of radiomics and machine and deep learning applied to peripheral nerves, as well as other parts of the body, may reveal new insights beyond the capabilities of human eyes. Thus musculoskeletal radiologists may have a pivotal role in expanding the diagnostic capabilities of US and MRI in the study of peripheral nerve pathology, especially when the CSA of the nerve is not markedly increased.…”

“…In these syndromes, US can demonstrate possible alterations in structures inside (the tendons) or adjacent to the carpal tunnel, such as anatomical variations or abnormal elements compressing the nerve. [4][5][6][7][8] The role of US in peripheral nerve evaluation prompted the European Society of Musculoskeletal Radiology (ESSR) to assign a high level of evidence and consensus among experts of nerve US in the evaluation of peripheral nerves. 9 According to the ESSR, the use of US for nerve evaluation is strongly encouraged because in several anatomical area, MRI is not able to offer additional information.…”

High-Frequency and Ultra-High Frequency Ultrasound: Musculoskeletal Imaging up to 70 MHz

“…36 UHFUS enables going beyond the simple size and cross-sectional evaluation of peripheral nerves, thereby ensuring the possibility of obtaining a precise evaluation of the normal appearance or pathologic loss of the honeycomb pattern with hypoechoic fascicles in a bright background. 37 Indeed, entrapment neuropathies are generally characterized by nerve thickening, loss of the fascicular pattern, and decreased echogenicity, mainly due to edema (in the acute phase) and fibrosis (in the chronic phase) (►Fig. 2).…”