Magnetic resonance cinematography of the fingers: a 3.0 Tesla feasibility study with comparison of incremental and continuous dynamic protocols

Assessment and comparison of image quality between two real-time sequences for dynamic MRI of distal joints at 3.0 Tesla

BACKGROUND

Real-time sequences allow functional evaluation of various joint structures during a continuous motion and help understand the pathomechanics of underlying musculoskeletal diseases.

PURPOSE

To assess and compare the image quality of the two most frequently used real-time sequences for joint dynamic magnetic resonance imaging (MRI), acquired during finger and ankle joint motion.

MATERIAL AND METHODS

A real-time dynamic acquisition protocol, including radiofrequency (RF)-spoiled and balanced steady-state free precession (bSSFP) sequences, optimized for temporal resolution with similar spatial resolution, was performed using a 3.0-T MRI scanner on 10 fingers and 12 ankles from healthy individuals during active motion. Image quality criteria were evaluated on each time frame and compared between these two sequences. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were determined and compared from regions of interest placed on cortical bone, tendon, fat, and muscle. Visualization of anatomical structures and overall image quality appreciation were rated by two radiologists using a 0-10 grading scale.

RESULTS

Mean CNR was significantly higher with bSSFP sequence compared to RF-spoiled sequence. The grading score was in the range of 5-9.3 and was significantly higher with RF-spoiled sequence for bone and joint evaluation and overall image appreciation on the two joints. The standard deviation for SNR, CNR, and grading score during motion was smaller with RF-spoiled sequence for both the joints. The inter-reader reliability was excellent (>0.75) for evaluating anatomical structures in both sequences.

CONCLUSION

A RF-spoiled real-time sequence is recommended for the in vivo clinical evaluation of distal joints on a 3.0-T MRI scanner.

Dynamic study of the finger interphalangeal joint volar plate-motion analysis with magnetic resonance cinematography and histologic comparison

OBJECTIVE

We aimed to further improve knowledge about volar plate (VP) motion of the finger proximal interphalangeal joint (PIP), by analyzing the dynamic VP shape during a full range of finger flexion using magnetic resonance cinematography of the fingers (MRCF), and to compare the results with anatomical cross sections from cadaver specimens.

MATERIALS AND METHODS

The dynamic sagittal VP shape was visualized with MRCF in a total number of 23 healthy volunteers. The length, angle, and thickness as well as the contact length of the VP to the PIP joint base were measured. Statistical analysis included t-test or rank-sum testing. Anatomical cross sections with differing degrees of PIP joint flexion were obtained from 12 cadaver specimens (fingers) for comparison.

RESULTS

Significant positive correlations between PIP joint flexion angle and VP area, length, depth and the VP contact length were found. This matched histologically to fiber rearrangements especially within the loose third VP layer.

CONCLUSION

Our study analyzed the full range of motion dynamic VP shape of the PIP joint using MRCF. This contributes to a more precise understanding of the complex interaction of the VP with the PIP joint and may facilitate evaluation of clinical cases such as VP avulsion or pulley rupture.

[Finger injuries with a focus on ligamentous structures]

BACKGROUND

Ligamentous lesions of the fingers are common everyday injuries and usually the result of distortion or overloading. Numerous examination methods are available for dedicated radiological diagnosis of sometimes complex injury patterns.

OBJECTIVES

To review radiological diagnosis of the ligamentous structures of the finger joints including the presentation of anatomical, biomechanical and therapeutic aspects.

MATERIALS AND METHODS

Presentation of the anatomy and biomechanics as well as the most common trauma mechanisms of the ligamentous structures. Review of the literature, discussion of recent work and diagnostic expert recommendations.

RESULTS

The most relevant ligamentous structures are collateral ligaments, pulley ligaments, volar plates and tendons. The goal of radiologic diagnosis is to accurately define the injury pattern and to differentiate between simple and complicated ligamentous lesions. In unclear cases, magnetic resonance imaging (MRI) has become standard for further diagnostics, which may allow depiction of ligamentous structures in submillimetre resolution.

CONCLUSIONS

Today, differential diagnosis includes all radiological modalities, which ensures the determination of an adequate therapy and prevention of sequel at a high standard.

Dynamic MRI for articulating joint evaluation on 1.5 T and 3.0 T scanners: setup, protocols, and real-time sequences

Dynamic magnetic resonance imaging (MRI) is a non-invasive method that can be used to increase the understanding of the pathomechanics of joints. Various types of real-time gradient echo sequences used for dynamic MRI acquisition of joints include balanced steady-state free precession sequence, radiofrequency-spoiled sequence, and ultra-fast gradient echo sequence. Due to their short repetition time and echo time, these sequences provide high temporal resolution, a good signal-to-noise ratio and spatial resolution, and soft tissue contrast. The prerequisites of the evaluation of joints with dynamic MRI include suitable patient installation and optimal positioning of the joint in the coil to allow joint movement, sometimes with dedicated coil support. There are currently few recommendations in the literature regarding appropriate protocol, sequence standardizations, and diagnostic criteria for the use of real-time dynamic MRI to evaluate joints. This article summarizes the technical parameters of these sequences from various manufacturers on 1.5 T and 3.0 T MRI scanners. We have reviewed pertinent details of the patient and coil positioning for dynamic MRI of various joints. The indications and limitations of dynamic MRI of joints are discussed.

Assessment of vocal fold mobility using dynamic magnetic resonance imaging and ultrasound in healthy volunteers

PURPOSE

To verify the value of dynamic magnetic resonance imaging (MRI) sequences, fast field echo (FFE), and balanced gradient echo (true fast imaging with steady-state free precession - TRUFI) in the evaluation of vocal fold mobility in healthy volunteers, against ultrasound examination (US) as the reference test.

MATERIAL AND METHODS

Vocal fold mobility in 35 healthy volunteers (age 20-59 years, 20 women and 15 men) with no history of laryngeal disorders and neck surgeries was determined by means of US and MRI during normal breathing and phonation of the "hiiii" sound. US images were used to determine the glottic angles. During MRI two dynamic sequences, fast field echo and balanced gradient echo, were applied to determine the minimum and maximum values of the glottic angles, along with the rima glottidis area, separately for the right and left compartments. Due to differences in larynx anatomy, the abovementioned parameters were analysed separately for women and men.

RESULTS

No significant differences were observed between the glottic angle values obtained during US and dynamic MRI (FFE and TRUFI sequences). Regardless of the dynamic MRI sequence used, a positive correlation was found between the maximum values of glottic angle and the rima glottidis area. This correlation was strong and statistically significant among men, but not in women.

CONCLUSIONS

Dynamic MRI of vocal folds using FFE and TRUFI sequence is an accurate method for the objective evaluation of rima glottidis width.