PaperlayerView exact revision on arXiv

Source-linked AI summary

Ultrasound and Magnetic Resonance Elastography of the Neck: Biomechanical Basis, Clinical Applications and Methodological Challenges

Rashedul Hasan, Anna Yang, Kishani Kandasamy, Hossein Bahreinizad, Md Ashikuzzaman, Suman K. Chowdhury, Shahed Mohammed

arXiv:2610.12584v1eess.IV

TL;DR

Neck disorders alter tissue mechanics, yet clinical assessment still relies on morphology, palpation and symptoms. This review brings together neck biomechanics, clinical conditions and ultrasound elastography and MRE; ultrasound is more established, while MRE remains an emerging but feasible approach.

  • Problem

    Neck disorders can alter tissue mechanics, but assessment relies on morphology, palpation and symptoms rather than quantitative in vivo measurement.

    Source: §1 · p. 1

  • Method

    The narrative review synthesizes neck biomechanics, clinical evidence, and the principles and applications of ultrasound elastography and MRE.

    Source: §1 · p. 2

  • Results

    Ultrasound elastography is more established and has diagnostic value for thyroid nodules and cervical lymph nodes, whereas neck MRE is feasible but remains at an early stage.

    Source: §6.3 · p. 15, §7.1.2 · p. 17, §7.2.3 · p. 19

  • Takeaways & Limitations

    Neck elastography measurements require standardized, reported acquisition and processing conditions, and in vivo tissue measurements could inform cervical computational models.

    Source: §9 · p. 28

    Thyroid SWE stiffness is sensitive to probe pressure, and nodal SWE values vary with orientation and stretching, with no universal cutoff established.

    Source: §7.2.2 · p. 19, §7.2.3 · p. 19

Abstract

from arXiv · show

Many neck disorders, from chronic neck pain and headache to thyroid and nodal malignancy and radiation-induced fibrosis, both arise from and alter the mechanical properties of neck tissues, yet clinical assessment still relies on morphology, palpation and symptoms. Ultrasound and magnetic resonance elastography (MRE) now allow these properties to be measured in vivo, but the neck literature differs widely in methodology and remains dispersed across modalities and tissues. This review brings together the biomechanical basis of neck tissue behavior, the clinical conditions that alter it, and the principles and applications of ultrasound elastography and MRE in the neck. We show that ultrasound elastography has demonstrated diagnostic value for thyroid nodules and cervical lymph nodes, while neck MRE has been shown to be feasible but remains at an early stage. Across both modalities, reported values depend strongly on fiber orientation, posture, muscle activation and acquisition conditions. We therefore propose reporting recommendations and discuss how measurements beyond stiffness, including anisotropy, viscosity and nonlinearity, could improve disease management and inform computational models of the neck.

1. Introduction

Neck disorders can alter tissue mechanics, but routine assessment relies on morphology, palpation and symptoms rather than measuring those mechanics. This review connects neck biomechanics and disease with ultrasound elastography and MRE, while emphasizing the methodological factors that shape their measurements.

1. Introduction

  • Neck disorders are associated with altered tissue mechanics, yet diagnosis still relies on morphology, palpation and self-reported symptoms.The review argues that in vivo measurement could support objective diagnosis and understanding of disease pathogenesis.Source: §1 · p. 1
  • Neck elastography values depend on fiber orientation, posture, muscle activation and acquisition conditions, making control and reporting necessary for comparison.Relevant acquisition factors include probe pressure, excitation frequency, inversion algorithm and imaging system.Source: §1 · pp. 1–2
  • The narrative review links neck biomechanics, conditions that alter tissue properties, and elastography principles and applications across ultrasound and MRE.It also considers measurements beyond stiffness and how in vivo data could inform cervical computational models.Source: §1 · p. 2

2. Information sources and search strategy

The review searched PubMed and supplemented it with Google Scholar and reference-list hand searches. Search terms and eligibility differed by section and modality, with no publication-date or article-type filters.

2. Information sources and search strategy

  • The literature search used PubMed, supplemented by Google Scholar and hand searches of bibliographies; the last search was dated 6 October 2026.Source: §2 · p. 2
  • Searches combined disease, method or biomarker terms with elastography, and neck MRE and ultrasound application studies were kept in separate modality sections.Source: §2 · pp. 2–3
  • The review applied no publication-date or article-type filters, excluded non-cervical head application studies, and selected background literature by the authors.Other-organ studies were retained when they described elastography methods or biomarkers.Source: §2 · p. 3

3. Musculoskeletal Biomechanics of the Neck

Neck mechanics emerge from interactions among distinct tissues, their geometry, loading and muscle activation. The section explains how those factors produce coupled motion, tissue resistance and direction-, time- and location-dependent behavior.

3.1 The Neck as a Coupled Mechanical System

  • Cervical motion is distributed across linked spinal units: C0–C2 orients the head, while subaxial levels share motion and help control head position relative to the trunk.Facet joints and ligaments constrain motion, and behavior also depends on posture, joint position and muscle activation.Source: §3.1 · pp. 3–4

3.2 Load Transmission and Head Support

  • Head loads pass through anterior vertebral bodies and discs and posterior facet joints, while ligaments and capsules restrain translation and rotation.Disc and cartilage mechanics depend on fluid redistribution; collagen organization contributes to directional and nonlinear behavior.Source: §3.2 · pp. 4–5

3.3 Passive Stiffness and Active Muscle Tone

  • Whole-neck structural stiffness combines tissue properties, geometry, joint configuration and muscle activation, unlike the regional shear modulus estimated by MRE.Muscle activation or passive tension can raise measured shear modulus without a structural tissue change, so scanning state should be standardized.Source: §3.3 · p. 5

3.4 Passive Mechanical Contributions

  • Passive resistance varies with hydration and loading history: fluid redistribution changes disc stiffness, while stretched collagen fibers progressively recruit and stiffen ligaments, capsules and muscle.Higher strain rates increase stiffness in ligaments and capsules.Source: §3.4 · p. 6

3.5 Active Mechanical Contributions of Cervical Muscles

  • Muscle activation increases resistance as myosin cross-bridges engage, and the active contribution depends on which muscles are recruited and coordinated.Neck extensor and sternocleidomastoid shear modulus increased with active contraction.Source: §3.5 · p. 6

3.6 Viscoelasticity, Anisotropy, and Heterogeneity

  • Neck tissues exhibit viscoelasticity, anisotropy and heterogeneity rather than one uniform stiffness, reflecting loading duration, fiber direction and regional composition.These variations occur within structures such as discs and among individual neck muscles; composition-changing disease can also alter mechanics.Source: §3.6 · pp. 6–7

4 Clinical Significance of Neck Elastography

Neck conditions alter mechanics through changes in muscle activation and control or in tissue composition. These changes matter clinically, while assessment remains largely subjective, motivating objective measurement of neck tissue mechanics.

4.1 Chronic Neck Pain

  • Chronic non-specific neck pain is linked to muscle stiffening through sustained contraction and inflammation, postural loading, and impaired deep-flexor control with compensatory superficial-muscle activity.The section describes both active and passive muscle mechanisms.Source: §4.1 · p. 7

4.2 Headache Disorder

  • Cervicogenic headache involves referred neck-to-head pain and muscle changes, including altered activation, spasm, fat infiltration and atrophy that affect active and passive mechanics.The trigeminocervical complex connects upper cervical and trigeminal afferents.Source: §4.2 · p. 8

4.3 Occupational and Postural Loading

  • Resting muscle stiffness did not differ across sonographer disability groups, whereas office-work trapezius stiffness varied with chair recline, head-and-neck position and sex.The review suggests occupational loading may affect muscle behavior during work more than resting properties; posture at one moment does not predict chronic pain reliably.Source: §4.3 · p. 8

4.4 Malignant Remodeling of Thyroid gland and cervical lymph node

  • Thyroid nodule stiffness is associated with fibrosis-related features, but elastography performance varies across tumor types; lymph node stiffness also varies with underlying pathology.Lymphomatous nodes may be soft, whereas infectious nodes with scarring, calcification or necrosis may be stiffer or heterogeneous.Source: §4.4 · p. 9

4.5 Salivary Gland Disease

  • Sjögren's disease can stiffen salivary glands through lymphocytic infiltration and fibrosis, while conventional imaging and palpation struggle to distinguish focal tumors from healthy or benign tissue.Source: §4.5 · p. 9

4.6 Radiation-Induced Fibrosis after Head and Neck cancer Treatment

  • Radiation-induced fibrosis deposits collagen and contracts affected tissues, contributes to dysphagia and pain, and remains assessed subjectively in clinical practice.It is observed in more than half of patients between one and eight years after radiotherapy.Source: §4.6 · pp. 9–10

5. Current Approaches for Measuring Neck Biomechanics

Clinical tests characterize neck function, while computational models estimate internal loads and tissue deformation; neither directly measures individual tissues’ mechanical properties. Elastography offers a noninvasive way to measure those properties in living subjects.

5.1 Clinical Examination of Neck Biomechanics

  • Clinical examinations assess cervical mobility, muscle performance, and sensorimotor control, but they do not directly measure individual-tissue stiffness.Range-of-motion testing alone cannot establish structural stiffness; quantifying stiffness requires both applied force or moment and resulting displacement or rotation.Source: §5.1 · pp. 10–11

5.2 Computational Assessment of Neck Biomechanics

  • Finite element models estimate internal loads and tissue deformation by assigning material properties, interactions, and boundary conditions to anatomical elements.Depending on represented structures, they can estimate intervertebral motion, disc deformation, ligament forces, and tissue stress and strain.Source: §5.2 · p. 11
  • Models distinguish passive tissue resistance from active muscle forces, but prescribed forces do not predict recruitment; simulating recruitment or reflexes requires activation formulations or feedback control.Predictions also depend on geometry, material properties, contacts, and loading assumptions; verification and validation bound interpretation to evaluated conditions.Source: §5.2 · p. 11
  • Elastography can measure tissue mechanics noninvasively in living subjects, addressing gaps in clinical tests and models based largely on ex vivo cadaveric properties.Cadaveric testing cannot capture muscle activation, in vivo hydration, or differences between individuals.Source: §5.2 · p. 11

6 Magnetic Resonance Elastography for the neck

MRE images externally induced shear waves to estimate tissue mechanics throughout a volume, including at depths inaccessible to ultrasound. Neck applications adapt excitation, acquisition, and inversion methods to small targets and differing scanner capabilities.

6 Magnetic Resonance Elastography for the neck

  • MRE uses three-dimensional wave-field imaging to estimate tissue mechanics at any depth and can measure viscosity and anisotropy as well as stiffness.Neck applications are reviewed alongside candidate biomarkers, most of which have not yet been measured in the neck.Source: §6 · p. 11

6.1 Basic Principal of MRE

  • An MRE examination generates shear waves through external vibration, encodes tissue displacement in MR signal phase, then recovers mechanical properties from displacement maps.These are the excitation, acquisition, and inversion stages.Source: §6.1 · pp. 11–12

6.1.1 Excitation Methods

  • Neck drivers adapt to small, superficial targets near bone, while excitation frequency must balance spatial resolution against attenuation and penetration depth.Higher frequencies produce shorter wavelengths that resolve smaller structures but penetrate less deeply; the frequency must match target size and depth.Source: §6.1.1 · p. 12

6.1.2 Acquisition Methods

  • Neck MRE acquisition ranges from full 3D vector spin-echo methods to more available single-component 2D GRE, which generally overestimates stiffness relative to 3D reconstruction.Conventional multi-echo sequences can enable MRE without dedicated motion-encoding gradients, while compressed-sensing methods have been proposed to accelerate acquisition.Source: §6.1.2 · p. 12

6.1.3 Inversion Methods

  • Direct inversion estimates stiffness from displacement-field derivatives but can amplify noise; multifrequency data improve stability, and heterogeneous inversion incorporates stiffness gradients.Iterative finite-element methods avoid differentiating measured data and are less noise-sensitive, while physics-informed neural networks have proved more robust to noise than conventional numerical methods.Source: §6.1.3 · p. 13

6.2 Candidate MRE Biomarkers

MRE can characterize tissue behavior beyond elasticity, with candidate biomarkers reflecting distinct mechanical features. Most of these measures have not yet been measured in the neck.

6.2 Candidate MRE Biomarkers

  • Elasticity, usually reported as shear modulus μ or storage modulus G′, describes tissue resistance to shear deformation and is the primary clinical elastography biomarker.MRE can also estimate viscosity, anisotropy, nonlinearity, porosity, and hydrostatic pressure.Source: §6.2 · p. 13

6.2.1 Viscosity

  • Viscosity captures energy dissipation during shear loading, represented by loss modulus G″ or loss angle φ, and reflects fluid content and coupling between tissue compartments.Multifrequency MRE separated elastic and viscous behavior in excised liver and kidney; in chronic viral hepatitis, the viscous parameter graded inflammatory activity.Source: §6.2.1 · p. 13

6.2.2 Anisotropy

  • Anisotropy describes direction-dependent stiffness from aligned fibers; lower-leg muscle shear modulus parallel to fibers exceeded the perpendicular modulus by approximately 1.2–1.3-fold.MRE-derived anisotropy ratios in phantoms and bovine muscle agreed with rheometry and distinguished fiber-content levels.Source: §6.2.2 · p. 13

6.2.3 Nonlinearity

  • Nonlinearity measures how stiffness changes with deformation or background stress, and can be assessed through higher harmonics or acoustoelasticity.Physiological loading can bias apparent stiffness by up to twofold; incorporating rheology and loading state into reconstruction removes this bias and recovers intrinsic unloaded stiffness.Source: §6.2.3 · p. 14

6.2.4 Porosity

  • Poroelastic models represent coupled solid and fluid compartments, enabling estimates of hydraulic permeability, solid-matrix stiffness, and pore pressure.A single-phase elastic model can over- or underestimate solid-matrix stiffness where pore-pressure gradients develop.Source: §6.2.4 · p. 14

6.3 Current works on Neck MRE

Neck MRE has been demonstrated across several principal tissues, with drivers and frequencies adapted to target size, depth, and location. Early clinical comparisons show differing stiffness patterns across lesions, with overlap in parotid tumor values.

6.3 Current works on Neck MRE

  • Neck MRE has been applied to upper trapezius, parotid and thyroid glands, cervical lymph nodes, and parotid tumors, from feasibility studies to early lesion comparisons.Targets differ in size, depth, and proximity to bone, prompting study-specific driver and frequency adaptations.Source: §6.3 · pp. 14–15
  • At 50 Hz for thyroid, Yeung et al. reported storage moduli of 0.17 kPa for one papillary thyroid carcinoma versus 0.58 kPa for normal thyroid; the metastatic node measured 0.66 kPa.The normal parotid value was 1.12 kPa at 80 Hz, so the node was lower than parotid but higher than normal thyroid.Source: §6.3 · pp. 14–15
  • Muscle stiffness measurements varied with fiber direction and frequency; fiber-parallel excitation at 60 Hz produced mean upper-trapezius stiffness of approximately 4.2 kPa on both sides.At 75 Hz, trapezius stiffness was 7.26 ± 2.13 kPa versus 4.16 ± 0.50 kPa for supraspinatus.Source: §6.3 · p. 14
  • MRE driver designs include a shoulder pad for supraspinatus and trapezius, bilateral stethoscope-shaped drivers for parotids, and a headrest-mould driver for thyroid and cervical lymph nodes.These designs illustrate hardware adaptation to different neck targets.Source: Figure 4 · p. 15
  • Parotid tumors were stiffer than healthy gland tissue, but values overlapped between tumor types; metastatic cervical lymph nodes had higher mean elasticity than benign nodes.Pleomorphic adenomas measured 3.72 ± 1.42 kPa and Warthin tumors 2.54 ± 0.70 kPa; metastatic and benign nodes measured 6.86 ± 0.82 and 5.68 ± 0.94 kPa, respectively.Source: §6.3 · p. 15

7.1 Strain Elastography

Strain elastography estimates relative tissue stiffness from deformation under compression and has been applied to neck muscles, thyroid nodules, cervical lymph nodes, and superficial lesions. Findings range from muscle deformation differences to diagnostic performance that varies across lesion types and cohorts.

7.1 Strain Elastography

  • Strain elastography maps tissue displacement during compression to relative elasticity, supporting assessment across neck tissues.Softer tissue deforms more than stiffer tissue under equivalent stress.Source: §7.1 · p. 17

7.1.1 Neck Muscle Biomechanics

  • Women with chronic whiplash-associated disorders showed greater trapezius and multifidus shortening than controls, while self-stretching reduced upper-trapezius strain-ratio only in adults in their 20s.The group difference was not found in three intermediate-depth extensors.Source: §7.1.1 · p. 17

7.1.2 Thyroid Nodules

  • AUC 0.918 vs. 0.686 for strain ratio versus conventional ultrasound scoring in Thy-3 nodules, but a broader 657-nodule study reported 58% sensitivity and 78% specificity.At cutoff 2.09, strain ratio had 90.6% sensitivity and 93% specificity; the broader study used cutoff 2.66.Source: §7.1.2 · p. 17
  • Neck-muscle-referenced strain ratio yielded 92% negative predictive value, rising to 100% with conventional ultrasound risk factors; hard strain elastography independently predicted malignancy.Hard strain elastography was present in 79.3% of malignant versus 7.7% of benign nodules.Source: §7.1.2 · p. 17

7.1.3 Cervical Lymph Nodes and Other Soft Tissues

  • For cervical nodes, reported performance included 93.3% sensitivity and 75% specificity at strain-ratio cutoff ≥1.62, and 95.3% accuracy with muscle-referenced cutoff 1.465.An AREA% cutoff of 45.23% yielded 84.3% sensitivity and 70.6% specificity.Source: §7.1.3 · p. 18
  • In tuberculous lymphadenitis, strain ratio identified caseous-necrosis lesions with 85.0% sensitivity and 76.3% specificity, rising to 95.0% sensitivity with contrast-enhanced ultrasound; it also predicted poor six-month response.In cutaneous lesions, strain ratios separated malignant lesions (3.9–32.2) from benign ones (≤3.0); both findings were from single cohorts needing validation.Source: §7.1.3 · p. 18

7.2 Shear Wave Elastography

This section reviews shear wave elastography for quantitative neck-tissue stiffness assessment, including thyroid nodules, cervical lymph nodes and radiation-induced cervical fibrosis, as well as normal-tissue values. It also addresses measurement variability related to posture, muscle activation, probe pressure and acquisition orientation, and compares VTIQ with strain elastography.

7.2 Shear Wave Elastography

  • SWE generates shear waves with an acoustic push beam and tracks their propagation using ultrafast ultrasound to estimate speed and calculate shear modulus,.Unlike strain-based methods, SWE provides quantitative stiffness measures with reduced dependence on operator-applied compression.Source: §7.2 · p. 18

7.2.1 Neck Muscle Biomechanics

  • Neck-muscle stiffness varies with depth, activation and posture: extensors ranged from 7.7 kPa in trapezius to 14.9 kPa in multifidus at rest, while posterior and anterior muscles responded differently to neck position,,.Semispinalis cervicis stiffened most during isometric head lift; nuchal fascia was stiffer in forward-head than neutral posture, and posterior muscles were stiffest in flexion and softest in extension,,.Source: §7.2.1 · p. 18
  • In chronic nonspecific neck pain, SWE findings conflict: one study found higher speeds in three muscles, while other studies found no stiffness differences or diagnostic discrimination,,.Neither of the studies reporting muscle stiffness differences found associations with pain or disability; the largest study found fatty infiltration, rather than SWE measures, distinguished patients from controls.Source: §7.2.1 · p. 18, §7.2.3 · p. 23
  • SWE distinguished cervicogenic headache, myofascial pain and somatic dysfunction; post-irradiation muscle and fascial stiffness was roughly doubled without reduced cervical range [172].Semispinalis cervicis had AUC 1.000 for cervicogenic headache; trapezius AUC rose from 0.578 in mild to 0.983 in severe myofascial pain, and trapezius speed fell from 1.96 to 1.58 m/s after treatment,,.Source: §7.2.1 · pp. 18–19

7.2.2 Thyroid Nodules

  • A cutoff of ≥26 kPa distinguished malignant from benign thyroid nodule cytology with AUC 0.876, 80% sensitivity and 81% specificity; stiffness did not independently predict histopathology.In a six-nodule pilot, SWE classified all nodules correctly and revealed some microcalcification-associated stiff foci not visible on B-mode imaging.Source: §7.2.2 · p. 19
  • Thyroid SWE stiffness rose nonlinearly with probe pressure, potentially moving benign nodules into malignant-range values; acquisition pressure therefore requires standardization,.In healthy volunteers, stiffness increased from 16.7 kPa at 2 N to 29.9 kPa at 10 N; carcinomas also stiffened more than benign nodules and normal tissue as precompression increased,.Source: §7.2.2 · p. 19

7.2.3 Cervical Lymph Nodes

  • Malignant cervical nodes were stiffer, but SWE’s advantage over strain elastography varied across studies; an ARFI area ratio also predicted nodal spread from papillary thyroid carcinoma,,,.In one comparison, SWE had AUC 0.84 versus 0.74 for strain elastography; another found strain ratio slightly higher (0.956 vs. 0.940), while SWE reached 100% sensitivity at 2.195 m/s,. Combining the primary-tumor ARFI area ratio with conventional ultrasound raised AUC from 0.784 to 0.803.Source: §7.2.3 · p. 19
  • Cervical-node SWE values depend on probe orientation and neck stretch, and reported cutoffs of 2.195–3.14 m/s show that no universal threshold is established,,.Values were higher with the probe parallel rather than perpendicular to overlying sternocleidomastoid fibers; stretching increased stiffness only in the parallel orientation.Source: §7.2.3 · pp. 19, 23
  • Radiation-induced cervical fibrosis was associated with about 2× higher muscle and fascia stiffness and 1.4–1.6× higher subcutaneous stiffness than controls.Muscle: left 46.98 vs. 28.10 kPa, right 46.75 vs. 21.52 kPa; fascia: left 46.41 vs. 25.47 kPa, right 44.28 vs. 22.69 kPa. Subcutaneous tissue: left 34.16 vs. 23.89 kPa, right 34.31 vs. 20.92 kPa.Source: §7.2.3 · p. 24
  • Normal neck-tissue stiffness clustered around 9–11 kPa, with no sex effect and only a small age-related decrease [173].Reported means were 9.89 kPa for sternocleidomastoid, 9.5 ± 3.6 kPa for thyroid, and 9.64 kPa for lymph nodes; the age decrease in sternocleidomastoid was significant on the left but not the right.Source: §7.2.3 · p. 24
  • Thyroid stiffness increased non-linearly with probe preload, reaching 29.9 kPa at 10 N [21].The reported values were 19.3 kPa at 4 N, 22.3 kPa at 6 N, 25.9 kPa at 8 N, and 29.9 kPa at 10 N.Source: §7.2.3 · p. 24
  • Precompression increased stiffness across normal thyroid parenchyma, benign hyperplastic nodules, and papillary carcinomas; among these tissues, papillary carcinomas showed the greatest strain hardening [175].Source: §7.2.3 · p. 24
  • VTIQ had a higher AUC than strain elastography (0.84 vs. 0.74, p = 0.005).The supplied passages report confirmed cases but do not specify the condition or cohort for this comparison.Source: §7.2.3 · p. 25

8. Technical & Methodological Challenges

Neck elastography is limited by linked dependencies across wave generation, tissue physics, processing and clinical validation. The section proposes reporting recommendations to make measurements interpretable and comparable.

Wave generation and coupling

  • Small, curved, layered neck anatomy complicates actuator and probe coupling, while muscle structure and motion further disrupt wave propagation and strain imaging.MRE may require target-specific moulds, pads and drivers; additional encoding directions or diffusion imaging for anisotropy lengthen acquisition.Source: §8 · p. 26

Tissue physics: orientation, posture, muscle state and preload

  • Muscle anisotropy makes measured stiffness orientation-dependent, while posture and muscle state also alter measurements across neck tissues.Shear wave speed was higher with scanning parallel rather than perpendicular to fibers in pericranial muscles, trapezius MRE and lymph-node SWE; head position, contraction, and computer-work posture also change stiffness.Source: §8 · pp. 26–27
  • Within the clinical force range of 2–10 N, thyroid stiffness nearly doubled, and papillary carcinomas stiffened more under precompression than benign or normal tissue.Uncontrolled preload could therefore move a benign nodule into the malignant range.Source: §8 · p. 27

Processing and reported quantities

  • MRE values vary with excitation frequency, acquisition dimensionality and inversion choices, while SWE-to-modulus conversion assumes homogeneous, isotropic, purely elastic tissue.Young’s modulus and shear modulus, storage modulus or |G*| are different reported quantities; kilopascal values cannot be compared across modalities without conversion.Source: §8 · p. 27

Reliability and clinical validation

  • Strain elastography remains semi-quantitative, with no consensus on the optimal strain-ratio cutoff.Source: §8 · p. 27
  • SWE reliability is good to excellent for superficial muscles but lower for deep muscles (mean ICC 0.82 vs. 0.68, falling to 0.47 for the semispinalis capitis).Inter-examiner reliability is generally lower than intra-examiner reliability.Source: §8 · p. 27
  • No accepted normative ranges exist for cervical muscle stiffness, and findings in chronic nonspecific neck pain are inconsistent.Cervical fascia stiffness had excellent reliability (ICC ≥ 0.90) but did not differ between healthy participants and those with neck and low back pain; discrepancies may reflect participant, muscle, posture, contraction and protocol differences.Source: §8 · p. 28

Reporting recommendations

  • Neck elastography values are interpretable only when relevant acquisition factors are specified; Table 5 lists minimum reporting information for cross-center comparison.Source: Table 5 · p. 27, §8 · p. 28

9. Conclusion

Neck tissue mechanics reflect interactions among passive tissues, active muscle, posture and loading, and elastography measures regional rather than whole-neck properties. Ultrasound is more established clinically than MRE, while both require standardized acquisition and further validation.

9. Conclusion

  • The neck is a coupled mechanical system whose tissues are viscoelastic, anisotropic, nonlinear and heterogeneous, so elastography measures regional properties rather than a single whole-neck stiffness.Posture, muscle activation, excitation frequency and fiber orientation affect the measured property.Source: §9 · p. 28
  • Ultrasound elastography is more established for thyroid nodules, cervical lymph nodes and neck muscles; MRE is feasible across several neck tissues but remains early-stage, with encouraging results from small cohorts.DWI-based virtual MRE should not be treated as equivalent to mechanical MRE.Source: §9 · p. 28
  • Reported values depend on acquisition and processing factors, so studies are comparable only when these factors are standardized and reported.Future work should establish neck-specific protocols and normative values, validate stiffness against clinical outcomes in larger cohorts, compare ultrasound and MRE in the same subjects, and extend measurements beyond stiffness.Source: §9 · p. 28
  • In vivo neck tissue measurements could inform cervical computational models that currently rely largely on cadaveric and animal data.Source: §9 · p. 28
Loading 2610.12584v1…