A comparison of the performance of anatomical MRI and DTI in diagnosing carpal tunnel syndrome

Combination of morphological and multiparametric MR neurography enhances carpal tunnel syndrome diagnosis and evaluation

This study aimed to investigate the diagnostic and evaluative significance of combining median nerve (MN) morphological measurements with diffusion tensor imaging (DTI) and T2 mapping metrics for carpal tunnel syndrome (CTS). Morphological and multiparametric magnetic resonance neurography (MRN), along with clinical evaluation, were conducted on 33 CTS patients and 32 healthy controls. The MRN metrics included fractional anisotropy (FA), apparent diffusion coefficient (ADC), axial diffusivity (AD), radial diffusivity (RD), T2 value, cross-sectional area (CSA) and MN flattening ratio (MNFR) at both the pisiform bone and hamate bone levels. Differences in MRN metrics between the above two levels (Delta FA, Delta ADC, Delta AD, Delta RD and Delta T2) were calculated. T-tests, multivariable regression, and receiver operating characteristic (ROC) curve analyses were used to compare and classify patients with CTS and controls. The correlations between MRN metrics and clinical characteristics were analyzed. Comparisons were also made between MRN metrics in patients with and without significant symptom improvement after treatment. FA, AD, T2 value, and CSA at the pisiform bone level were identified as independent predictors of CTS. The combination of these metrics improved diagnostic performance (AUC 0.922, sensitivity 84.85% and specificity 90.62%). Delta ADC, Delta AD, and Delta T2 correlated with function Boston scores. The T2 value at hamate bone level, along with Delta AD and FA, correlated with visual analogue score (VAS). CSA and Delta T2 had higher AUCs for classifying patients with and without significant symptom improvement after treatment. These findings suggest that combining MN morphological and multiparametric MRN metrics can enhance the diagnostic performance of CTS and has the potential to provide an objective and quantitative basis for further study of the degree of entrapment and prognosis.

Electrodiagnostic studies and new diagnostic modalities for evaluation of peripheral nerve disorders

Electrodiagnostic studies (EDx) are frequently performed in the diagnostic evaluation of peripheral nerve disorders. There is increasing interest in the use of newer, alternative diagnostic modalities, in particular imaging, either to complement or replace established EDx protocols. However, the evidence to support this approach has not been expansively reviewed. In this paper, diagnostic performance data from studies of EDx and other diagnostic modalities in common peripheral nerve disorders have been analyzed and described, with a focus on radiculopathy, plexopathy, compressive neuropathies, and the important neuropathy subtypes of Guillain-Barré syndrome, chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), vasculitic neuropathy and diabetic neuropathy. Overall EDx retains its place as a primary diagnostic modality in the evaluated peripheral nerve disorders. Magnetic resonance imaging and ultrasound have developed important complementary diagnostic roles in compressive and traumatic neuropathies and atypical CIDP, but their value is more limited in other neuropathy subtypes. Identification of hourglass constriction in nerves of patients with neuralgic amyotrophy may have therapeutic implications. Investigation of radiculopathy is confounded by poor correlation between clinical features and imaging findings and the lack of a diagnostic gold standard. There is a need to enhance the literature on the utility of these newer diagnostic modalities.

Diffusion tensor imaging combined with the dual-echo steady-state (DESS) protocol for the evaluation of the median nerve in the carpal tunnel: A preliminary study

Background

Carpal tunnel syndrome (CTS) is diagnosed based on neurological, electrophysiology, and radiological findings. Due to the technical development of magnetic resonance imaging (MRI), the median nerve is evaluated with several MRI protocols. However, diffusion tensor imaging (DTI) combined with a dual-echo steady-state (DESS) protocol is not frequently used to evaluate the median nerve of CTS. This study aimed to evaluate the median nerve in the carpal tunnel using DTI combined with a DESS protocol.

Methods

Five healthy volunteers and seven patients with CTS were enrolled. The patients underwent MRI for CTS pre- and post-operatively. The median nerve was evaluated using a 3-T MRI scanner. The parameters of the DESS protocol were as follows: Repetition time (TR)/echo time (TE) = 10.83/3.32 ms, slice thickness = 0.45 mm, field of view (FoV) = 350 × 253 × 350 mm, and 3D voxel size = 0.5 × 0.5 ×0.4 mm. The parameters of the DTI sequence were as follows: TR/TE = 4000/86 ms, slice thickness = 3 mm, FoV = 160 × 993 × 90 mm, 3D voxel size = 1.2 × 1.2 ×3.0 mm, and b value = 0.1000 s/mm2. The apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values of the median nerve were statistically analyzed. Statistical significance was set at P< 0.05.

Results

The FA value of healthy volunteers was 0.576 ± 0.058, while those of the patients were 0.357 ± 0.094 and 0.395 ± 0.062 pre-and post-operatively, respectively. Statistically significant differences were identified between the FA values of healthy volunteers and pre-operative/post-operative patients. The ADC values of healthy volunteers and pre-operative patients were 0.931 ± 0.096 and 1.26 ± 0.282 (10-3 mm2/s), respectively (P< 0.05).

Conclusion

This MRI protocol may be useful for evaluating the median nerve in the carpal tunnel.

The Impact of Reference Standard on Diagnostic Testing Characteristics for Carpal Tunnel Syndrome: A Systematic Review

Lack of a reliable reference standard for carpal tunnel syndrome (CTS) diagnosis could impact the diagnostic test characteristics. This systematic review sought to evaluate differences in the accuracy of CTS diagnostic modalities based on the reference standard used.

Methods

A systematic review was performed following PRISMA guidelines to investigate diagnostic modalities used in CTS. A literature search of Embase, PubMed, and Cochrane Reviews was conducted for the years of 2010-2021 for primary data, and 113 studies met final inclusion criteria. Studies were stratified based on the reference standard utilized and diagnostic modality assessed, and the weighted means of the sensitivities and specificities were calculated.

Results

Thirty-five studies used clinical diagnosis alone as a reference standard, and 78 studies used electrodiagnostic study (EDS). The specificity for MRI and ultrasound (US) were substantially lower when EDS was used as the reference standard. MRI was the test most affected by the reference standard used, showing increased sensitivity when using EDS as the reference compared to clinical diagnosis (77.1% versus 60.9%) and decreased specificity (87.6% versus 99.2%). Regardless of the reference standard used, all tests had anticipated false-positive and/or false-negative rates of at least 10%.

Conclusions

Testing characteristics vary greatly based on the choice of reference standard, with the sensitivity of MRI most affected. Regardless of reference standard used, EDS, US, and MRI each had false-positive and/or false-negative rates too great to be appropriate for use as a screening examination.

Can Diffusion Tensor Imaging Apparent Diffusion Coefficient Diagnose Carpal Tunnel Syndrome? A Systematic Review and Meta-Analysis

Magnetic resonance diffusion tensor imaging (DTI) can detect microstructural changes in peripheral nerves. Studies have reported that the median nerve apparent diffusion coefficient (ADC), a quantification of water molecule diffusion direction, is sensitive in diagnosing carpal tunnel syndrome (CTS). Five databases were searched for studies using ADC to investigate CTS. Apparent diffusion coefficient (measured in mm2/s) were pooled in random-effects meta-analyses. Twenty-two studies met criteria yielding 592 patients with CTS and 414 controls. Median nerve ADC were measured at the level of the distal radioulnar joint (CTS ADC: 1.11, 95% CI: 1.07-1.15, I2 = 54%; control ADC: 1.04, 95% CI: 1.01-1.07, I2 = 57%), pisiform (CTS ADC: 1.39, 95% CI: 1.37-1.42, I2 = 0%; control ADC: 1.27, 95% CI: 1.23-1.31, I2 = 59%), hamate (CTS ADC: 1.40, 95% CI: 1.36-1.43, I2 = 58%; control ADC: 1.27, 95% CI: 1.25-1.28, I2 = 47%), and as an combination of several measurements (CTS ADC: 1.40, 95% CI: 1.37-1.47, I2 = 100%; control ADC: 1.39, 95% CI: 1.24-1.53, I2 = 100%). Median nerve ADC is decreased in individuals with CTS compared to controls at the levels of the hamate and pisiform. ADC cut-offs to diagnose CTS should be established according to these anatomic levels and can be improved through additional studies that include use of a wrist coil.

Quantitative parameters of diffusion tensor imaging in the evaluation of carpal tunnel syndrome

BACKGROUND

To explore the value of diffusion tensor imaging (DTI)-derived metrics in quantitative evaluation of carpal tunnel syndrome (CTS).

METHODS

This prospective cross-sectional study included 39 wrists from 24 symptomatic CTS patients, who underwent clinical, electrophysiological, and magnetic resonance imaging (MRI) evaluations. In addition, 10 wrists of 6 healthy participants were included as controls. Clinical and nerve conduction study (NCS) findings were evaluated and graded according to the Boston Carpal Tunnel Questionnaire (BCTQ) and the American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM), respectively. We performed MRI using a 1.5 Tesla scanner. Mean diffusivity (MD), fractional anisotropy (FA), axial diffusivity (AD), and radial diffusivity (RD) of the median nerve at the distal radioulnar joint (DRUJ) (d), the inlet of the carpal tunnel (CT) at the pisiform level (i), the middle of the CT (m) and the outlet of the CT at the level of the hook of hamate (o), cross-sectional area at the inlet of the CT (iCSA), and the difference between MD and FA of the DRUJ and the outlet of CT (Delta MD and Delta FA) were measured.

RESULTS

The CTS patients had significantly lower FA [for example, oFA: mean difference 0.09, 95% confidence interval (CI): 0.05 to 0.12] and significantly higher MD than healthy participants (for example, iMD: mean difference 0.3, 95% CI: 0.03 to 0.57). There was a negative correlation between iCSA with iFA and between mFA and oFA (-0.5

CONCLUSIONS

The DTI-derived quantitative metrics add potential value to the evaluation of CTS. Alterations in the FA of the median nerve along the CT are the most significant features of CTS and reflect the degree of median nerve compression and clinical deficit. With a cutoff value of 0.45, FA at the carpal outlet has a sensitivity and specificity of 87.5% and 85.7% in the diagnosis of CTS, respectively.

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Key Words

• Boston Carpal Tunnel Questionnaire
• Carpal tunnel syndrome (CTS)
• apparent diffusion coefficient (ADC)
• diffusion tensor imaging (DTI)
• fraction anisotropy
• magnetic resonance imaging (MRI)
• nerve conduction study (NCS)

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Affiliation(s)

Nhu Quynh Vo Department of Radiology, University of Medicine and Pharmacy, Hue University, Hue, Vietnam
Ngoc Thanh Hoang Department of Radiology, University of Medicine and Pharmacy, Hue University, Hue, Vietnam
Duy Duan Nguyen Department of Internal Medicine, University of Medicine and Pharmacy, Hue University, Hue, Vietnam
Thi Hieu Dung Nguyen Department of Physiology, University of Medicine and Pharmacy, Hue University, Hue, Vietnam
Trong Binh Le Department of Radiology, University of Medicine and Pharmacy, Hue University, Hue, Vietnam
Nghi Thanh Nhan Le Department of Surgery, University of Medicine and Pharmacy, Hue University, Hue, Vietnam
Thanh Thao Nguyen Department of Radiology, University of Medicine and Pharmacy, Hue University, Hue, Vietnam

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Meta-analysis of the normal diffusion tensor imaging values of the median nerve and how they change in carpal tunnel syndrome

Carpal tunnel syndrome (CTS) leads to distortion of axonal architecture, demyelination and fibrosis within the median nerve. Diffusion tensor imaging (DTI) characterises tissue microstructure and generates reproducible proxy measures of nerve 'health' which are sensitive to myelination, axon diameter, fiber density and organisation. This meta-analysis summarises the normal DTI values of the median nerve, and how they change in CTS. This systematic review included studies reporting DTI of the median nerve at the level of the wrist in adults. The primary outcome was to determine the normal fractional anisotropy (FA) and mean diffusivity (MD) of the median nerve. Secondarily, we show how the FA and MD differ between asymptomatic adults and patients with CTS, and how these differences are independent of the acquisition methods. We included 32 studies of 2643 wrists, belonging to 1575 asymptomatic adults and 1068 patients with CTS. The normal FA was 0.58 (95% CI 0.56, 0.59) and the normal MD was 1.138 × 10^-3 mm²/s (95% CI 1.101, 1.174). Patients with CTS had a significantly lower FA than controls (mean difference 0.12 [95% CI 0.09, 0.16]). Similarly, the median nerve of patients with CTS had a significantly higher mean diffusivity (mean difference 0.16 × 10^-3 mm²/s [95% CI 0.05, 0.27]). The differences were independent of experimental factors. We provide summary estimates of the normal FA and MD of the median nerve in asymptomatic adults. Furthermore, we show that diffusion throughout the length of the median nerve becomes more isotropic in patients with CTS.

Prediction of carpal tunnel syndrome using the thenar muscle cross-sectional area by magnetic resonance imaging

Carpal tunnel syndrome (CTS) is a common neuropathy. Although CTS progression is known to be associated with thenar muscle (TM) atrophy, the diagnostic value of TM atrophy for CTS has not been established. In this research, the thenar muscle cross-sectional area (TMCSA) was evaluated to analyze the relationship between the TMCSA and CTS. We assumed that TMCSA is a major diagnostic parameter in the CTS.Both TMCSA and thenar muscle thickness (TMT) samples were acquired from 18 CTS patients, and from 18 control subjects who underwent wrist magnetic resonance imaging with no evidence of CTS. T2-weighted transverse magnetic resonance imaging images were obtained. We measured the TMCSA and TMT at the level of first carpometacarpal joint.The average TMCSA was 296.98 ± 49.39 mm2 in the normal group and 203.36 ± 72.13 mm2 in the CTS group. The average TMT was 8.54 ± 1.45 mm in the normal group and 7.38 ± 1.14 mm in the CTS group. CTS group had significantly lower TMCSA and TMT. Receiver operator characteristics curve analysis showed that the best cutoff point for the TMCSA was 260.18 mm2, with 77.8% sensitivity, 77.8% specificity. The best cutoff point of the TMT was 7.70 mm, with 61.1% sensitivity, 66.7% specificity.Although the TMCSA and TMT were both significantly associated with CTS, the TMCSA was a much more sensitive measurement parameter. Thus, to evaluate CTS patients, the physician should more carefully inspect the TMCSA than TMT.

Magnetic Resonance Neurography: Improved Diagnosis of Peripheral Neuropathies

Peripheral neuropathies account for the most frequent disorders seen by neurologists, and causes are manifold. The traditional diagnostic gold-standard consists of clinical neurologic examinations supplemented by nerve conduction studies. Due to well-known limitations of standard diagnostics and atypical clinical presentations, establishing the correct diagnosis can be challenging but is critical for appropriate therapies. Magnetic resonance neurography (MRN) is a relatively novel technique that was developed for the high-resolution imaging of the peripheral nervous system. In focal neuropathies, whether traumatic or due to nerve entrapment, MRN has improved the diagnostic accuracy by directly visualizing underlying nerve lesions and providing information on the exact lesion localization, extension, and spatial distribution, thereby assisting surgical planning. Notably, the differentiation between distally located, complete cross-sectional nerve lesions, and more proximally located lesions involving only certain fascicles within a nerve can hold difficulties that MRN can overcome, when basic technical requirements to achieve sufficient spatial resolution are implemented. Typical MRN-specific pitfalls are essential to understand in order to prevent overdiagnosing neuropathies. Heavily T2-weighted sequences with fat saturation are the most established sequences for MRN. Newer techniques, such as T2-relaxometry, magnetization transfer contrast imaging, and diffusion tensor imaging, allow the quantification of nerve lesions and have become increasingly important, especially when evaluating diffuse, non-focal neuropathies. Innovative studies in hereditary, metabolic or inflammatory polyneuropathies, and motor neuron diseases have contributed to a better understanding of the underlying pathomechanism. New imaging biomarkers might be used for an earlier diagnosis and monitoring of structural nerve injury under causative treatments in the future.

Carpal tunnel syndrome caused by the entrapment of a bifid Lanz IIIA Type anatomical variant of median nerve: A case report and systematic literature review

Background:

Carpal tunnel syndrome (CTS) is the most common entrapment peripheral neuropathy. Median nerve may present several anatomical variations such as a high division or bifid median nerve (BMN). A thorough knowledge of the normal anatomy and variations of the median nerve at the wrist are fundamental to reduce complications during carpal tunnel release.

Case Description:

A 63-year-old man with CTS underwent preoperative ultrasound that showed the entrapment of the median nerve and disclosed a BMN Lanz IIIA Type anatomical variation at the carpal tunnel. During the surgery, the anatomical variant of a BMN at the wrist has been visualized. Both nervous rami entirely occupied the carpal canal and this may have predisposed to the development of the entrapment syndrome. Nor persistent median artery, or other associated abnormalities, have been identified. At the 6 months follow-up control, the patient referred a good surgical recovery with complete resolution of the preoperative symptoms of the median nerve entrapment.

Conclusion:

A rare case of Lanz IIIA BMN Type at the wrist has been encountered in a patient with a CTS and a systematic review and practical considerations have been presented with the aim of raising awareness to the neurosurgical community of a such rare variant that could be encountered during carpal tunnel release procedures. CTS may be caused by the entrapment of a BMN Lanz IIIA Type anatomical variant of median nerve. Preoperative US would help to identify such patients to reduce risk of iatrogenic injuries.

Radiomics of peripheral nerves MRI in mild carpal and cubital tunnel syndrome

OBJECTIVE

To assess the discriminative power of radiomics of peripheral nerves at 1.5T MRI, using common entrapment neuropathies of the upper limb as a model system of focal nerve injury.

MATERIALS AND METHODS

Radiomics was retrospectively done on peripheral nerve fascicles on T1-weighted 1.5T MRI of 40 patients with diagnosis of mild carpal (n = 25) and cubital tunnel (n = 15) syndrome and of 200 controls. Z-score normalization and Mann-Whitney U test were used to compare features of normal and pathological peripheral nerves. Receiver operating characteristic analysis was performed.

RESULTS

A total of n = 104 radiomics features were computed for each patient and control. Significant differences between normal and pathological median and ulnar nerves were found in n = 23/104 features (p < 0.001). According to features classification, n = 5/23 features were shape-based, n = 7/23 were first-order features, n = 11/23 features were classified as gray level run length matrix. Nine of the selected features showed an AUC higher that 0.7: minimum AUC of 0.74 (95% CI 0.61-0.89) for sum variance and maximum AUC of 0.90 (95% CI 0.82-0.99) for zone entropy.

CONCLUSION

Features analysis demonstrated statistically significant differences between normal and pathological nerve. The results suggested that radiomics analysis could assess the median and ulnar nerve inner structure changes due to the loss of the fascicular pattern, intraneural edema, fibrosis or fascicular alterations in mild carpal tunnel and mild cubital tunnel syndromes even when the nerve cross-sectional area does not change.

Recurrence of carpal tunnel syndrome in isolated non-syndromic macrodactyly: DTI examination of a giant median nerve

Macrodystrophia lipomatosa, a hamartomatous enlargement of soft tissues leading to gigantism of a part or a whole extremity, generally affects the territory of distribution of a single nerve. In some cases, this condition may cause an entrapment neuropathy. We report the clinical, radiological, and surgical findings of a patient with isolated non-syndromic macrodactyly and giant median nerve presenting recurrent carpal tunnel syndrome (CTS). In this case, conventional magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) supported the presence of fibrohamartomatous infiltration, determining an enlargement of the median nerve and consequently an increased susceptibility to compression damage. A 57-year-old man presenting macrodactyly of the second and third finger of the right hand showed recent onset of severe hypoesthesia of the first three fingers of the right hand. He also underwent surgery for right CTS 23 years before. The electromyography/electroneurography confirmed the diagnosis of CTS. The ultrasonography showed a massive enlargement of the median nerve within the carpal tunnel, while MRI confirmed the enlargement of the median nerve with thickened hypointense bundles and interposed tissue, with increased mean diffusivity and decreased fractional anisotropy at DTI. We discuss about the use of a relatively novel imaging technique, investigating for the first time an uncommon cause of a very common entrapment neuropathy.

Comparison of Magnetic Resonance Imaging and Ultrasonography in Diagnosing and Grading Carpal Tunnel Syndrome: A Prospective Study

OBJECTIVE

To use anatomic measurements on magnetic resonance imaging (MRI) and ultrasonography (USG) in diagnosing and grading carpal tunnel syndrome (CTS) using nerve conduction studies (NCS) as the gold standard.

MATERIAL AND METHODS

In this prospective study, 26 patients with CTS (45 wrists; 22 female and 4 male patients; mean ± SD age of 49.42 + 14.47 years) and 19 age and sex matched healthy volunteers (32 wrists; 15 female and 4 male volunteers, mean ± SD age of 42.52 + 10.85 years) underwent MRI and USG. Cross-sectional area (CA) of median nerve was measured using free hand ROI at four levels: hamate hook (H0), pisiform bone (PI0), 1 cm proximal (PI1) and 2 cm proximal to PI0 (PI2). Relative median nerve signal intensity (MNSI) was calculated as ratio of median nerve signal intensity with hypothenar muscle signal intensity. Flexor retinacular bowing was calculated at hamate hook level. Echogenicity and Power Doppler vascularity of median nerve were assessed on USG. Independent t-test, chi square test and receiver operating characteristic curve analysis were used as appropriate.

RESULTS

On USG, CA measured at PI0 (95% confidence interval of 0.872-0.987) and retinacular bowing (0.816-0.912), while, on MRI, CA at PI1 (0.874-0.997) were most useful in diagnosing CTS based on the ROC and Zombie plot analysis. Area under curves for CA measurements on USG and MRI were not significantly different. CA at PI1 on MRI (0.752-0.965) was significantly different between minimal to moderate CTS and severe to extreme CTS groups (on NCS).

CONCLUSION

CA of median nerve is the most useful parameter to diagnose and grade CTS and USG and MRI are comparable for measurements. Increased retinacular bowing on USG and hypoechogenicity of median nerve increase the diagnostic confidence while MRI helps in picking up important associated conditions.

Cross-sectional area of the median nerve at the wrist: Comparison of sonographic, MRI, and cadaveric measurements

BACKGROUND

This study compares median nerve cross-sectional area (CSA) measurements at the wrist obtained with ultrasound (US) and magnetic resonance imaging (MRI) using cadaveric measurements as the gold standard.

METHODS

Median nerve CSA was measured using US and MRI in 9 cadaveric wrists obtained from 5 subjects at 5 locations: distal forearm, proximal to tunnel inlet, at tunnel inlet, at tunnel outlet, and distal to tunnel outlet and then on identical cadaveric transverse sections obtained with a bandsaw. All US, MRI, and cadaveric measurements were repeated to determine reliability. Median nerves of 10 patients with clinical carpal tunnel syndrome (CTS) were measured with US and MRI using an identical method US.

RESULTS

Median nerve CSA MRI measurements correlated better (Pearson correlation: 0.80-0.95, P < .05) with cadaveric measurements than with US measurements (Pearson correlation: 0.61-0.79, P < .05). Median nerve CSA US measurements (8.6-12.5 mm² , P < .05) were smaller at all levels than MRI (11.3-14.7 mm² ) or cadaveric (11.0-14.9 mm² ) measurements while MRI and cadaver measurements were similar at all levels. Median nerve CSA MRI measurements in CTS patients were larger than US measurements at all levels.

CONCLUSION

Median nerve CSA measurements by MRI are larger than US measurements and correlated better with cadaveric measurements. Median nerve CSA criteria used for diagnosing CTS on US are not likely to be applicable to MRI.

Optimal parameters and location for diffusion tensor imaging in the diagnosis of carpal tunnel syndrome: a meta-analysis

AIM

To assess the diagnostic value of the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) of diffusion tensor imaging (DTI) at several anatomical locations in patients with carpal tunnel syndrome (CTS) to explore the optimal parameters and measurement location.

MATERIALS AND METHODS

A search was conducted using the PubMed, EBSCO, Ovid, Web of Science, and Cochrane databases to identify articles relevant to this study published before September 2017. Studies were selected and included according to strict eligibility criteria. Mean differences (MD) and 95% confidence intervals (CIs) were used to compare FA and ADC values between CTS patients and healthy subjects. Potential publication bias was investigated.

RESULTS

Eleven studies involving 349 CTS wrists and 278 controls were selected for the meta-analysis. A notable MD: was found for lowered FA at the level of the pisiform bone for CTS versus controls (MD: -0.11, 95% confidence interval [CI]: -1.14 to -0.07, z=5.83, p<0.001). A higher ADC was found at the pisiform bone and hamate bone levels for CTS versus controls (P: MD: 0.15, 95% CI: 0.10 to 0.20, z=5.98, p<0.001, H: MD: 0.15; 95% CI: 0.09 to 0.21, z=4.67, p<0.001).

CONCLUSIONS

The meta-analysis demonstrated a significant FA reduction and ADC increase in CTS patients. This result supports the use of DTI parameters in differentiating CTS patients from health subjects. The anatomical site for FA at the pisiform and ADC at the pisiform and hamate levels were more accessible than other sites for the diagnosis of CTS patients.

Evaluation of median nerve by shear wave elastography and diffusion tensor imaging in carpal tunnel syndrome

PURPOSE

The aim of the current study is to investigate the diagnostic role of shear-wave elastography and diffusion tensor imaging in patients with carpal tunnel syndrome.

MATERIAL AND METHODS

The study included a total of 77 wrists; 18 normal, 35 wrists with mild, 9 wrists with moderate and 15 wrists with severe carpal tunnel syndrome. Elastography of the median nerve was performed by defining the boundaries of a segment of the nerve at sagittal plane at the level of proximal carpal row. Additionally, the cross-sectional area of the median nerve was evaluated. Fractional anisotropy and apparent diffusion coefficient measurements were carried out by placing region-of-interest at three levels: at pisiform bone (carpal tunnel inlet), mid carpal tunnel, and hook of hamate (carpal tunnel outlet).

RESULTS

Patients with carpal tunnel syndrome had higher elasticity values of median nerve (53.0 kPa; IQR 40.8-77.0 kPa) compared to control subjects. (36.8 kPa; IQR 31.0-39.9 kPa) Patients with moderate-severe carpal tunnel syndrome had higher elasticity values (82 kPa; IQR 64.0-95.5 kPa) compared to patients with mild carpal tunnel syndrome. (44 kPa; IQR 32.5-59.5 kPa) Patients with carpal tunnel syndrome had lower fractional anisotropy at mid-carpal level (0.382; IQR 0.330-0.495) compared to the control group. (0.494; IQR 0.434-0.537) Patients with moderate-severe carpal tunnel syndrome had lower fractional anisotropy values (0.366; IQR 0.331-0.407) and higher apparent diffusion coefficient values (1.509 mm²/s; IQR 1.374-1.733 mm²/s) compared to patients with mild carpal tunnel syndrome. (0,423; IQR 0.324-0.526 and 1.293 mm²/s; IQR 0.967-1.514 mm²/s) CONCLUSION: Shear-wave elastography and diffusion tensor imaging are helpful imaging modalities in diagnosing carpal tunnel syndrome and assessing its severity.

Carpal tunnel syndrome assessment with diffusion tensor imaging: Value of fractional anisotropy and apparent diffusion coefficient

OBJECTIVES

To quantitatively assess carpal tunnel syndrome (CTS) with DTI by evaluating two approaches to determine cut-off values.

METHODS

In forty patients with CTS diagnosis confirmed by nerve conduction studies (NCs) and 14 healthy subjects (mean age 58.54 and 57.8 years), cross-sectional area (CSA), apparent diffusion coefficient (ADC) and fractional anisotropy (FA) at single and multiple levels with intraobserver agreement were evaluated.

RESULTS

Maximum and mean CSA and FA showed significant differences between healthy subjects and patients (12.85 mm² vs. 28.18 mm², p < 0.001, and 0.613 vs. 0.524, p=0.007, respectively) (10.12 mm² vs. 19.9 mm², p<0.001 and 0.617 vs. 0.54, p=0.003, respectively), but not maximum and mean ADC (p > 0.05). For cut-off values, mean and maximum CSA showed the same sensitivity and specificity (93.3 %). However, mean FA showed better sensitivity than maximum FA (82.6 % vs. 73.9 %), but lower specificity (66.7 % vs. 80 %), and significant correlation for maximum CSA, 97 % (p < 0.01), with good correlation for maximum ADC and FA, 84.5 % (p < 0.01) and 62 % (p=0.056), respectively.

CONCLUSIONS

CSA and FA showed significant differences between healthy subjects and patients. Single measurement at maximum CSA is suitable for FA determination. Key Points • DTI showed that FA is stronger than ADC for CTS diagnosis. • Single- and multiple-level approaches were compared to determine FA and ADC. • Single-level evaluation at the thickest MN cross-sectional area is sufficient.

Utility of MRI Diffusion Tensor Imaging in Carpal Tunnel Syndrome: A Meta-Analysis

BACKGROUND After successful utilization of diffusion tensor imaging (DTI) in detecting brain pathologies, it is now being examined for use in the detection of peripheral neuropathies. The aim of this meta-analysis was to evaluate the diagnostic potentials of DTI in carpal tunnel syndrome (CTS). MATERIAL AND METHODS The literature search was performed in multiple electronic databases using a keyword search and final selection of the studies was based on predetermined inclusion and exclusion criteria. We performed a meta-analyses of mean differences in fractional anisotropy (FA) and apparent diffusion coefficient (ADC) between CTS patient and healthy subjects. Publication bias detection was done with Begg's test and sensitivity analyses were performed to explore the source/s of higher heterogeneity and the authenticity of results. RESULTS FA was significantly lower in CTS patients in comparison with healthy subjects (mean and the difference [95% confidence interval] was -0.06 [-0.10, -0.02] (p=0.003). The ADC was significantly higher in CTS patients (mean difference [95% CI] was 0.10 [0.02, 0.18], p=0.02). Overall sensitivity of FA-based diagnosis was 82.82%, with 77.83% specificity. CONCLUSIONS DTI can be a valuable tool in diagnosing CTS.