MRI and MR Arthrography Imaging of the Pathologies of the Wrist: A Pictorial Essay

1. Senior Resident, Department of Radiology, Vardhman Mahavir Medical College and Safdarjung Hospital, New Delhi, India. 2. Associate Professor, Department of Radiology, Vardhman Mahavir Medical College and Safdarjung Hospital, New Delhi, India. 3. Senior Resident, Department of Radiology, Vardhman Mahavir Medical College and Safdarjung Hospital, New Delhi, India. 4. Postgraduate Resident, Department of Radiology, Vardhman Mahavir Medical College and Safdarjung Hospital, New Delhi, India. 5. Senior Resident, Department of Radiology, Vardhman Mahavir Medical College and Safdarjung Hospital, New Delhi, India. 6. Senior Resident, Department of Radiology, Vardhman Mahavir Medical College and Safdarjung Hospital, New Delhi, India.

Abstract

Magnetic Resonance Imaging (MRI) has a special advantage over radiographs and Computed Tomography (CT) in evaluating an anatomically complex structure like wrist, owing to its excellent soft-tissue resolution and multiplanar imaging functionality. MR arthrography further improves the diagnostic value of MRI by virtue of its meticulous depiction of even small tears involving the Triangular Fibrocartilage Complex (TFCC), intrinsic and extrinsic ligaments of the wrist. This article focuses on the MRI and MR arthrography illustration of various traumatic as well as non traumatic pathologies affecting the wrist region and is mainly intended to educate the residents by comprehensively reviewing the imaging features of the major afflictions of this complex joint in a systematic fashion using checklists.

Computed tomography, Multiplanar imaging, Triangular fibrocartilage complex

The MRI is pivotal in the assessment of internal derangement of joints and is the investigation of choice in the evaluation of soft tissue pathologies of the wrist (1). The most common indication for wrist MRI is acute, subacute, or chronic wrist pain (2). The major stabilising structure at the radiocarpal joint is TFCC (Table/Fig 1). MR arthrography is more effective in evaluating TFCC, intrinsic and extrinsic ligaments of the wrist, relative to conventional MRI (3). Information provided from MRI decides further management and the surgical approach (2). While intra-articular soft-tissue pathologies are mostly managed with arthroscopic surgery, osseous pathologies may necessitate treatment with open surgery (2).

The MRI of the wrist requires optimising imaging parameters, and the usage of a pain marker is highly recommended. A higher magnetic field strength (ideally 3T) allows for better contrast and spatial resolution to assess internal joint derangement (4). MR arthrography may be performed in two ways: direct, in which contrast cocktail is percutaneously injected into the target joints (radiocarpal, midcarpal, distal radioulnar joints), and indirect, in which standard gadolinium dose is injected intravenously and recruited to a specific joint via exercise-induced hyperemia (4). Dallaudière B et al., observed that axial traction in wrist arthrography using finger traps and a pulley system was advantageous to study intrinsic and extrinsic ligaments and cartilage but added no benefit in evaluating tendons or nerve disorders (3).

ANATOMY OF THE WRIST

A brief review of the anatomy of the wrist joint along with the illustration of TFCC and main ligaments on MRI (Table/Fig 1),(Table/Fig 2) and the significant pathologies afflicting the joint is enumerated in (Table/Fig 3) (2),(4),(5).

PATHOLOGIES OF THE WRIST

This pictorial review aims to cover some of the common pathologies involving the wrist.

TFCC injuries: Perforation of TFCC is a chronic process seen in the elderly population, where discontinuity is present, but the edges are regular, and there is an absence of marrow oedema and adjacent fluid. A tear is an acute traumatic condition where there is a discontinuity in TFCC with reactive synovitis, edge irregularity, and adjacent marrow changes (Table/Fig 4). However, there are no specific imaging characteristics to differentiate between traumatic and degenerative tears. Hyperintense signal within the TFCC disk proper without extension to the articular surface is considered mucoid degeneration (1). Palmer’s classification distinguishes TFCC tears into traumatic and degenerative (2) (Table/Fig 5),(Table/Fig 6).

Carpal instability: Mayo’s classification categorises carpal instability into four types. Type I results from intrinsic ligament injury (carpal instability dissociative), whereas Type II is due to extrinsic or radiocarpal ligament injury (carpal instability non dissociative). Type III is a combination of the first two (carpal instability complex), while Type IV is due to pathology outside the carpals or wrist (carpal instability adaptive) (5) (Table/Fig 7).

Distal Radioulnar Joint (DRUJ) instability: Dorsal dislocation of DRUJ is commoner than volar.The epicentre method is the most explicit and preferred method for evaluating DRUJ instability as it considers the normal translational movement of DRUJ (6) (Table/Fig 8).

Ligament tear: Dorsal Intercalated Segment Instability (DISI) deformity occurs due to a tear of the dorsal component of the scapholunate ligament, causing flexion of the scaphoid and extension of the lunate and triquetrum (7). However, injury to portions of the volar extrinsic ligaments or dorsal intercarpal ligaments may also lead to DISI. Volar Intercalated Segment Instability (VISI) occurs from tears of the volar component of the lunotriquetral ligament or tears of the dorsal radiocarpal ligaments (8). In both DISI and VISI, the capitolunate angle is >30°. In DISI, the scapholunate angle is >80°, whereas, in VISI, it is <30°.

Carpal dislocation: Perilunate dislocation is the most common carpal dislocation and may be associated with purely ligamentous injuries or carpal fractures. Both perilunate and lunate dislocations are a part of a spectrum of carpal instability, from least severe to most severe being scapholunate dissociation, perilunate dislocation, mid-carpal dislocation, and lunate dislocation. In perilunate dislocation, the relationship of lunate with radius is maintained, while the ligamentous attachments of lunate with scaphoid, capitate and triquetrum are affected (Table/Fig 9). Lunate dislocation occurs with dorsal radiolunate ligament injury. The lunate dislocates volarly, and the remaining carpal bones maintain their normal relationships with each other and with the radius (9).

Carpal fracture and osteonecrosis: The most common carpal bone to be fractured is the scaphoid. A single intraosseous artery enters the scaphoid at the waist and supplies the proximal pole in a retrograde manner. Proximal pole fractures can lead to osteonecrosis, which shows hypointense T1/T2 signal, fragmentation, and collapse (Table/Fig 10). There is a traditional 4-stage classification scheme of Scapholunate Advanced Collapse (SLAC) and Scaphoid Non union Advanced Collapse (SNAC) wrists (Table/Fig 11). Kienböck disease is the osteonecrosis of the lunate bone and has an association with negative ulnar variance (Table/Fig 12). According to Lichtman’s classification, the disease progresses in four stages (Table/Fig 13) (8).

Synovial pathologies: Inflammatory arthritis, infective synovitis, and pigmented villonodular synovitis (Table/Fig 14) are the most frequent synovial pathologies involving the wrist. Inflammatory arthritis commonly presents with synovial thickening and marrow oedema, and the most common site of involvement is the attachment site of the intrinsic ligaments. Typical imaging features in Rheumatoid Arthritis (RA) (Table/Fig 15) include active tenosynovitis (fluid in tendon sheath with enhancement), tendinopathy (thickening with heterogeneous high signal intensity on fluid sensitive sequences), ulnar styloid erosion and rice bodies in palmar bursa. Extensor tendon involvement is seen in 50-64%, with the Extensor Carpi Ulnaris (ECU) being the most frequently affected tendon in early disease (4). MRI can also detect the most crucial predictor of an aggressive disease course, inflammation within the bones (osteitis) (10).

The characteristic features of tuberculous infection of the wrist (Table/Fig 16) include synovial thickening and T2W hyperintensity around the joints and tendons, tenosynovitis, rice bodies which appear as small low-signal and non enhanced foci in the synovial fluid, bone erosion, osteomyelitis, and occasionally encasement of the median nerve. The imaging features are often indistinguishable from RA. However, unilaterality of wrist involvement points towards infective aetiology compared to the bilateral presentation in inflammatory arthritis like RA (11).

Soft tissue and bony pathologies: The common soft tissue tumours at the wrist are ganglion cysts, lipoma, haemangiomas, peripheral nerve sheath tumours (Table/Fig 17), neuromas (Table/Fig 18), Giant Cell Tumour (GCT) of tendon sheath (Table/Fig 19), synovial chondromatosis, undifferentiated pleomorphic sarcoma, and liposarcoma (12). Ganglion cysts are the most prevalent benign soft tissues of the wrist. Ganglia may be found in both the volar and dorsal periarticular region, associated with injured ligaments, or reveal intraosseous connection. They are typically T1 hypointense and hyperintense on fluid-sensitive sequences, and may be complex, with debris, loculations or septations (13). Complex Regional Pain Syndrome (CRPS) (Table/Fig 20), Brodie’s abscess (Table/Fig 21) and hypertrophic osteoarthropathy are often seen around wrist. CRPS has been classified into types 1 and 2 based on the absence or presence of an underlying nerve lesion, respectively. Among bony tumours, GCT (Table/Fig 22), aneurysmal bone cyst, parosteal osteosarcoma, epitheloid haemangioma of bone are typically seen in the wrist region (12).

Intersection syndromes: Distal intersection syndrome occurs at the crossing point of the third extensor compartment with the second (8) (Table/Fig 23). The involved tendons may be thickened, with or without altered intratendinous signal intensity, particularly at their intersection (8). The surrounding subcutaneous tissues, muscles, and bones may show oedema. Proximal intersection syndrome, which is more common than the distal syndrome, occurs nearly 4–8 cm proximal to the Lister tubercle, where the first extensor compartment crosses the second compartment. The MRI findings are comparable to those of distal intersection syndrome and comprise thickening, tendinosis and adjacent T2 signal hyperintensity due to tenosynovitis, with surrounding soft tissue oedema. Contrast-enhanced sequences may depict peritendinous enhancement (8).

Entrapment syndromes: MRI features in patients with Carpal Tunnel Syndrome (CTS) are T2 hyperintensity in the median nerve, nerve enlargement at the level of pisiform as compared to the level of DRUJ, and flattening at the level of the hamate (Table/Fig 23). Ng A et al., found that a nerve Circumferential Surface Area (CSA) of 15 mm² proximal or distal to the tunnel could be used as a diagnostic criterion for CTS and 19 mm² proximal to the tunnel as a marker of severe disease (14). CTS is commonly seen in patients with compressive tumours in the carpal tunnel, diabetes, hypothyroidism, and amyloidosis. Enhancement of the median nerve due to oedema may occur as well as thenar muscle atrophy in chronic cases (14).

Entrapment and enlargement of the ulnar nerve as it passes through Guyon’s canal (formed by the pisiform and the hamate) is called Guyon’s canal/ulnar tunnel syndrome. It is typically caused by handlebars and hence is also known as “handlebar palsy”. Fracture of the hook of hamate, compression from adjacent masses, ganglion cysts, anomalous muscles and tendons, fibrous palmar arch, ulnar artery aneurysm, repetitive trauma, osteoarthritis of the pisotriquetral joint, os hamuli proprium, and dislocation of the pisiform bone are the usual causes of this condition (15).

Discussion

The wrist is a highly complex anatomical region with various stabilising structures holding the carpal bones, metacarpals, distal radius, and ulna. Although high soft tissue spatial resolution MRI of the wrist at a 3T scanner obviates the necessity of MR arthrography in most situations, it is worthwhile to perform this invasive study in indeterminate cases to attain accurate interpretation. Disruption of either scapholunate or lunotriquetral ligaments will result in the communication of the radiocarpal compartment proximally with the midcarpal compartment distally (4). Hence, midcarpal contrast injection is done first in suspected injury to these ligaments. Contrast material seen in the DRUJ indicates disruption to the triangular fibrocartilage complex or distal radioulnar ligaments (4). Hence, contrast imbibtion in the DRUJ following a radiocarpal injection strongly suggests a TFCC tear or perforation in the appropriate clinical setting. Appreciating the location of pathology as intra-articular versus extra-articular and further narrowing down the origin of pain to soft tissue or osseous aetiology on MRI facilitates the surgical management approach. MRI and MR arthrography also helps in determining the extent and severity of the pathology and incorporation of the relevant surgical classification systems in the report aids in appropriate communication with the referring clinician.

However, judicious use of MRI is recommended for evaluation of wrist pain as observed in a retrospective review on patients aged 20–60 years, where MRI affected treatment recommendation of ligamentous injury in only 28% of patients (16). Another study on the clinical significance of wrist and hand MRI in 316 patients found that diagnosis remained unsolved in 24% of cases, although MRI played a role in reassuring the patient, obviating further follow-up in 70% of case (17). A study evaluating 307 wrists MRIs in a tertiary care paediatric hospital revealed that unexplained wrist pain was a common presentation in children and MRI helped in the delineation of a mass/cyst and detection of infection/ arthropathy (18). Advances in wrist imaging include quantitative assessment with T2 and T1 rho mapping, compresses sensing, and isotropic 3D imaging using driven equilibrium sequences, and parallel imaging, which promise better outcomes with patient management (19).

This pictorial review highlights the common wrist pathologies presenting to a tertiary hospital occupied with 3T MRI scanner and facility for fluoroscopic guided MR arthrography. In the author’s experience, the most common indication for MRI of the wrist is ulnar-sided wrist pain, which mostly results from TFCC tear. MR arthrography is reserved for cases with equivocal/suspicious findings in cases of trauma and it was observed that it provides optimal recognition of the location of TFCC or ligament tears. In authors experience, abnormalities afflicting the wrist on MRI may be predominantly classified as osseous, soft-tissue, and joint pathologies. Trauma was observed as the most common aetiology affecting this anatomical region, with soft-tissue injuries involving TFCC tendons, and ligaments recording the highest incidence. Other common soft tissue pathologies at this site were ganglion cysts, carpal tunnel syndrome, tenosynovitis, and tendinopathy. Fractures and avascular necrosis of scaphoid/lunate were more common osseous pathologies with respect to impingement/impaction syndromes or bony tumors. As far as joint pathologies were concerned, post-traumatic carpal and DRUJ dislocation were found to be more frequent than inflammatory/infective synovial conditions.

Conclusion

The MRI is a valuable modality to diagnostically assess the wrist with high-resolution and multiplanar imaging without employing ionising radiation. MR arthrography is particularly advantageous in the evaluation of TFCC and ligaments of the wrist. Knowledge of the intrinsic anatomy of the wrist and the MR appearances of common pathologies enables prompt detection and management of wrist pathologies.

DOI and Others

DOI: 10.7860/JCDR/2022/59277.17323

Date of Submission: Jul 24, 2022
Date of Peer Review: Aug 28, 2022
Date of Acceptance: Oct 19, 2022
Date of Publishing: Dec 01, 2022

AUTHOR DECLARATION:
• Financial or Other Competing Interests: None
• Was informed consent obtained from the subjects involved in the study? Yes
• For any images presented appropriate consent has been obtained from the subjects. Yes

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