Variants, pitfalls and asymptomatic findings in wrist and hand imaging

Role of high-resolution ultrasound and magnetic resonance neurography in the evaluation of peripheral nerves in the upper extremity

Upper extremity entrapment neuropathies are common conditions in which peripheral nerves are prone to injury at specific anatomical locations, particularly superficial regions or within fibro-osseous tunnels, resulting in pain and potential disability. Although neuropathy is primarily diagnosed clinically by physical examination and electrophysiology, imaging evaluation with ultrasound and magnetic resonance neurography are valuable complementary non-invasive and accurate tools for evaluation and can help define the site and cause of nerve dysfunction which ultimately leads to precise and timely treatment. Ultrasound, which has higher spatial resolution, can quickly and comfortably characterize the peripheral nerves in real time and can evaluate for denervation related muscle atrophy. Magnetic resonance imaging on the other hand provides excellent contrast resolution between the nerves and adjacent tissues, also between pathologic and normal segments of peripheral nerves. It can also assess the degree of muscle denervation and atrophy. As a prerequisite for nerve imaging, radiologists and sonographers should have a thorough knowledge of anatomy of the peripheral nerves and their superficial and deep branches, including variant anatomy, and the motor and sensory territories innervated by each nerve. The purpose of this illustrative article is to review the common neuropathy and nerve entrapment syndromes in the upper extremities focusing on ultrasound and magnetic resonance neurography imaging.

Nerve Imaging in the Wrist

Neuropathic symptoms involving the wrist are a common clinical presentation that can be due to a variety of causes. Imaging plays a key role in differentiating distal nerve lesions in the wrist from more proximal nerve abnormalities such as a cervical radiculopathy or brachial plexopathy. Imaging complements electrodiagnostic testing by helping define the specific lesion site and by providing anatomical information to guide surgical planning. This article reviews nerve anatomy, normal and abnormal findings on ultrasonography and magnetic resonance imaging, and common and uncommon causes of neuropathy.

Evaluation of prestyloid recess morphology and ulnar-sided contrast leakage in CT arthrography of the wrist

Background

In wrist arthrograms, aberrant contrast material is frequently seen extending into the soft tissue adjacent to the ulnar styloid process. Since the prestyloid recess can mimic contrast leakage in CT arthrography, this study aims to provide a detailed analysis of its morphologic variability, while investigating whether actual ulnar-sided leakage is associated with injuries of the triangular fibrocartilage complex (TFCC).

Methods

Eighty-six patients with positive wrist trauma history underwent multi-compartment CT arthrography (40 women, median age 44.5 years). Studies were reviewed by two board-certified radiologists, who documented the morphology of the prestyloid recess regarding size, opening type, shape and position, as well as the presence or absence of ulnar-sided contrast leakage. Correlations between leakage and the presence of TFCC injuries were assessed using the mean square contingency coefficient (r_ɸ).

Results

The most common configuration of the prestyloid recess included a narrow opening (73.26%; width 2.26 ± 1.43 mm), saccular shape (66.28%), and palmar position compared to the styloid process (55.81%). Its mean length and anterior–posterior diameter were 6.89 ± 2.36 and 5.05 ± 1.97 mm, respectively. Ulnar-sided contrast leakage was reported in 29 patients (33.72%) with a mean extent of 12.30 ± 5.31 mm. Leakage occurred more often in patients with ulnar-sided TFCC injuries (r_ɸ = 0.480; p < 0.001), whereas no association was found for lesions of the central articular disc (r_ɸ = 0.172; p = 0.111).

Conclusions

Since ulnar-sided contrast leakage is more common in patients with peripheral TFCC injuries, distinction between an atypical configuration of the prestyloid recess and actual leakage is important in CT arthrography of the wrist.

Advanced Imaging of Ulnar Wrist Pain

Ulnar-sided wrist pain can be a diagnostic challenge for clinicians and radiologists. The ulnar wrist has complex morphology and is composed of many small bone and soft tissue structures. Within these structures, a wide variety of pathologic conditions can occur. To successfully diagnose and treat these pathologic conditions, clinicians and radiologists must have a strong understanding of the advanced imaging techniques available to them. In this review, the authors present a brief review of the normal ulnar wrist anatomy, discuss the differential diagnosis of ulnar-sided wrist pain, and examine the indications for different advanced imaging modalities.

Contrast-enhanced MRI of the wrist: Intravenous application of gadolinium improves diagnosis in ulnar-sided injuries of the TFCC

PURPOSE

Although lesions of the triangular fibrocartilage complex (TFCC) frequently induce ulnar-sided wrist pain and potentially distal radioulnar joint instability, diagnosis can pose a challenge due to the intricate anatomy. This study aims to evaluate the benefits of contrast-enhanced sequences for the detection of TFCC injuries in magnetic resonance imaging of the wrist.

METHOD

94 patients underwent wrist MRI with intravenous application of gadolinium-based contrast agents. For each patient, two datasets were analysed independently by two board-certified radiologists: One set comprised only plain T1- and fat-saturated proton-density-weighted sequences, while the second dataset included contrast-enhanced T1-weighted images with fat suppression. Arthroscopy or clinical reports served as reference standard with the former being used whenever available. Diagnostic confidence and TFCC component assessability were subjectively evaluated. Contrast-to-noise ratios (CNR) were calculated serve as an objective indicator of image contrast.

RESULTS

Lesions of the articular disc, the foveal and styloid ulnar attachment were present in 24 (25.5%), 61 (64.9%) and 53 (56.4%) patients. Access to contrast-enhanced T1 images improved the diagnostic accuracy for injuries of the styloid (R1/R2, 0.68/0.73 vs. 0.86/0.88) and foveal attachment (0.68/0.72 vs. 0.90/0.89) substantially compared to plain MRI (all p < 0.001), while no benefits could be identified for lesions of the central disc (0.89/0.90 vs. 0.87/0.90). Readers' diagnostic confidence and CNR for ulnar-sided lesions improved with contrast-enhanced T1 sequences available (p < 0.001).

CONCLUSIONS

With superior CNR in lesions of the TFCC's foveal and styloid attachment, contrast-enhanced, fat-saturated T1-weighted sequences facilitate higher diagnostic accuracy and confidence than fat-saturated PD- and plain T1-weighted MRI.

Improved diagnostic accuracy for ulnar-sided TFCC lesions with radial reformation of 3D sequences in wrist MR arthrography

Objectives

Triangular fibrocartilage complex (TFCC) injuries frequently cause ulnar-sided wrist pain and can induce distal radioulnar joint instability. With its complex three-dimensional structure, diagnosis of TFCC lesions remains a challenging task even in MR arthrograms. The aim of this study was to assess the added diagnostic value of radial reformatting of isotropic 3D MRI datasets compared to standard planes after direct arthrography of the wrist.

Methods

Ninety-three patients underwent wrist MRI after fluoroscopy-guided multi-compartment arthrography. Two radiologists collectively analyzed two datasets of each MR arthrogram for TFCC injuries, with one set containing standard reconstructions of a 3D thin-slice sequence in axial, coronal and sagittal orientation, while the other set comprised an additional radial plane view with the rotating center positioned at the ulnar styloid. Surgical reports (whenever available) or radiological reports combined with clinical follow-up served as a standard of reference. In addition, diagnostic confidence and assessability of the central disc and ulnar-sided insertions were subjectively evaluated.

Results

Injuries of the articular disc, styloid and foveal ulnar attachment were present in 20 (23.7%), 10 (10.8%) and 9 (9.7%) patients. Additional radial planes increased diagnostic accuracy for lesions of the styloid (0.83 vs. 0.90; p = 0.016) and foveal (0.86 vs. 0.94; p = 0.039) insertion, whereas no improvement was identified for alterations of the central cartilage disc. Readers’ confidence (p < 0.001) and assessability of the ulnar-sided insertions (p < 0.001) were superior with ancillary radial reformatting.

Conclusions

Access to the radial plane view of isotropic 3D sequences in MR arthrography improves diagnostic accuracy and confidence for ulnar-sided TFCC lesions.

Key Points

• In multi-compartment arthrography of the wrist, ancillary radial plane view aids assessability of the foveal and styloid ulnar-sided insertions of the triangular fibrocartilage complex.

• Assessment of peripheral TFCC injuries is more accurate with access to radial multiplanar reconstructions.

• Additional radial planes provide greater diagnostic confidence.

[Osseous variations in radiological diagnostics of the wrist]

CLINICAL/METHODICAL ISSUE

The carpal joint is one of the most complex joints in the body comprising multiple bones that allow flexibility while simultaneously providing stability. Variations in osseous structures that may be either cause or result of pathological changes may make radiological reporting challenging. Only the knowledge of important osseous variations allows a reliable assessment of carpal imaging studies.

STANDARD RADIOLOGICAL METHODS

The standard imaging technique for evaluation of osseous carpal structures is conventional radiography, which is followed by computed tomography (CT) and-under special circumstances-magnetic resonance imaging (MRI). Other imaging methods such as sonography or nuclear medicine studies do not play a significant role in clinical routine.

METHODICAL INNOVATIONS

Apart from continuous reduction in effective radiation dose, there have been no significant methodical improvements in the past decade regarding imaging of osseous carpal structures in clinical routine.

PRACTICAL RECOMMENDATIONS

As the initial diagnostic procedure, conventional radiography usually allows a safe and reliable diagnosis of osseous structures. Unclear or discrepant imaging findings between clinical and imaging assessment should initiate further imaging, preferably with CT. Only for certain questions or to reduce effective radiation dose in children MRI studies should be performed in clinical routine.

Multimodality Pitfalls of Wrist Imaging With a Focus on Magnetic Resonance Imaging: What the Radiologist Needs to Know

Numerous pitfalls are frequently encountered at multimodality imaging of the wrist, which may mimic various tendinous, osseous, capsuloligamentous, muscular, and neurovascular pathologic conditions. These pitfalls may be secondary to variant anatomy, artifactual due to magnetic resonance imaging or sonographic technique, or represent varying ranges of structure-specific normal including a spectrum of findings associated with aging in asymptomatic subjects. When an imaging finding of questionable significance is encountered, it is critical that the interpreting radiologist make every attempt to review any relevant clinical information in an effort to determine whether the imaging findings in question may account for the patient's presenting symptomology. In order to accurately diagnose true pathology at wrist imaging, it is imperative that the radiologist be familiar with the pitfalls discussed throughout this manuscript that may mimic disease. This familiarity will allow the radiologist to provide a more useful report for referring providers focusing on true pathology while eliminating potentially confusing or misleading findings which are inconsistent with the patient's clinical presentation.

The importance of radial multiplanar reconstructions for assessment of triangular fibrocartilage complex injury in CT arthrography of the wrist

Background

Triangular fibrocartilage complex (TFCC) lesions commonly cause ulnar-sided wrist pain and instability of the distal radioulnar joint. Due to its triangular shape, discontinuity of the TFCC is oftentimes difficult to visualize in radiological standard planes. Radial multiplanar reconstructions (MPR) may have the potential to simplify diagnosis in CT wrist arthrography. The objective of this study was to assess diagnostic advantages provided by radial MPR over standard planes for TFCC lesions in CT arthrography.

Methods

One hundred six patients (49 women, 57 men; mean age 44.2 ± 15.8 years) underwent CT imaging after wrist arthrography. Two radiologists (R1, R2) retrospectively analyzed three randomized datasets for each CT arthrography. One set contained axial, coronal and sagittal planes (MPR_Standard), while the other two included an additional radial reconstruction with the rotating center either atop the ulnar styloid (MPR_Styloid) or in the ulnar fovea (MPR_Fovea). Readers evaluated TFCC differentiability and condition. Suspected lesions were categorized using Palmer’s and Atzei’s classification and diagnostic confidence was stated on a five-point Likert scale.

Results

Compared to standard planes, differentiability of the superficial and deep TFCC layer was superior in radial reconstructions (R1/R2; MPR_Fovea: p < 0.001; MPR_Styloid: p ≤ 0.007). Palmer and Atzei lesions were present in 86.8% (92/106) and 52.8% (56/106) of patients, respectively. Specificity, sensitivity and accuracy for central Palmer lesions did not differ in radial and standard MPR. For peripheral Atzei lesions, sensitivity (MPR_Standard 78.6%/80.4%, MPR_Styloid 94.6%/94.6%, MPR_Fovea 91.1%/89.3%) and accuracy (MPR_Standard 86.8%/86.8%, MPR_Styloid 96.2%/96.2%, MPR_Fovea 94.3%/93.4%) improved with additional styloid-centered (p = 0.004/0.008) and fovea-centered (p = 0.039/0.125) reconstructions. No substantial difference was observed between both radial MPR (p = 0.688/0.250). Interrater agreement was almost perfect for each dataset (κ_Standard = 0.876, κ_Styloid = 0.894, κ_Fovea = 0.949). Diagnostic confidence increased with addition of either radial MPR (p < 0.001).

Conclusions

Ancillary radial planes improve accuracy and diagnostic confidence for detection of peripheral TFCC lesions in CT arthrography of the wrist.

MR Imaging of the Upper Limb: Pitfalls, Tricks, and Tips

MR imaging is the modality of choice to evaluate musculoskeletal pathologies of the upper limb in most settings. However, due to the complexity in anatomy, MR imaging can give a false pathologic appearance and lead to several errors in the interpretation of MR imaging findings. Also, several artifacts can be confused with pathologic entities. This article reviews the most frequently encountered conditions in shoulder, elbow, and wrist MR imaging that can represent diagnostic pitfalls mimicking true pathology, together with some possible tips and tricks that can be useful to solve these equivocal cases and achieve a correct diagnosis.

Magnetic Resonance Imaging-Detected Features of Inflammation and Erosions in Symptom-Free Persons From the General Population

OBJECTIVE

The use of magnetic resonance imaging (MRI)-detected inflammation and joint damage in the diagnosis of rheumatoid arthritis is recommended by a European League Against Rheumatism imaging task force. This recommendation is based on the sensitivity of MRI and not on specificity. Knowledge of the prevalence of MRI-detected features in symptom-free persons, however, is pivotal when considering MRI for diagnostic purposes.

METHODS

From November 2013 to December 2014, 196 symptom-free persons of different ages were recruited from the general population. Inclusion criteria were no history of inflammatory arthritis, no joint symptoms during the previous month, and no clinically detectable arthritis on physical examination. Contrast-enhanced MRIs of the dominant metacarpophalangeal (MCP), wrist, and metatarsophalangeal (MTP) joints were obtained using a 1.5T scanner and scored by 2 readers for synovitis, bone marrow edema, tenosynovitis, and erosions. For analyses at the joint level, MRI-detected inflammation was considered present if both readers scored the image as positive.

RESULTS

Of 193 persons scanned (ages 19-89 years), only 28% had no single inflammatory feature and 22% had no erosions. Primarily low-grade features were observed. All MRI features were positively correlated with age (P < 0.001). Preferential locations for synovitis were MCP2, MCP3, the wrists, and MTP1. Bone marrow edema was frequently present in MCP3, the scaphoid, and MTP1. Tenosynovitis was infrequent, except for in the extensor carpi ulnaris. Preferential locations for erosions were MCP2, MCP3, MCP5, the distal ulna, MTP1, and MTP5. Tables with age-, location-, and inflammation type-dependent frequencies were constructed. Simultaneous colocalized presence of synovitis, bone marrow edema, tenosynovitis, or erosions occurred.

CONCLUSION

MRI-detected inflammation and erosions are prevalent in symptom-free persons from the general population, especially at older ages and at preferential locations.

Incidental signal changes in the extensor carpi ulnaris on MRI

BACKGROUND

Magnetic resonance imaging (MRI) commonly finds musculoskeletal abnormalities incidental to the reason for ordering the test. The purpose of this study was to determine if the prevalence of extensor carpi ulnaris (ECU) signal changes on MRI varies between patients undergoing upper extremity MRI for assessment of clinically suspected ECU tendinopathy and those undergoing upper extremity MRI for other indications. Our secondary null hypotheses were that the prevalence of ECU signal changes on MRI does not vary based on patient age or sex and that the prevalence of ECU signal changes on MRI does not vary among other indications for MRI.

METHODS

We searched MRI reports of all patients undergoing MRI of the hand, wrist, or arm at our institution between 2001 and 2014 for signal changes in the ECU. The medical record was reviewed to determine the indication for the MRI and the presence of clinically suspected ECU tendinopathy.

RESULTS

ECU signal changes (overall prevalence of 13 %) were more common in patients undergoing MRI for a working clinical diagnosis of ECU tendinopathy or ulnar-sided wrist pain compared to patients evaluated for nonspecific pain and other indications. Age was independently associated with ECU signal changes on MRI. MRI signal changes are uncommonly associated with symptomatic tendinopathy (low positive predictive value).

CONCLUSIONS

ECU signal changes on MRI are common and often asymptomatic.

Pitfalls in wrist and hand ultrasound

OBJECTIVE

The purpose of this article is to review a number of diagnostic pitfalls related to ultrasound evaluation of the hand and wrist. Such pitfalls relate to evaluation of ten-dons (extensor retinaculum, multiple tendon fascicles, tendon subluxation), inflammatory arthritis (incomplete evaluation, misinterpretation of erosions, failure to evaluate for enthesitis), carpal tunnel syndrome (inaccurate measurements, postoperative assessment), ulnar collateral ligament of the thumb (misinterpretation of the adductor aponeurosis and displaced tear), wrist ganglion cysts (incomplete evaluation and misdiagnosis), and muscle variants.

CONCLUSION

Although ultrasound has been shown to be an effective imaging method for assessment of many pathologic conditions of the wrist, knowledge of potential pitfalls is essential to avoid misdiagnosis and achieve high diagnostic accuracy.