Incidental findings in the cervical spine at CT for trauma evaluation.

OBJECTIVE: CT is the standard of care for assessment of traumatic injuries. Because of the detail depicted with this technique, findings incidental to the injury are easily detected. We sought to determine the frequency and types of incidental findings in the cervical spines of trauma patients undergoing CT. MATERIALS AND METHODS: The trauma registry was accessed to identify the cases of patients evaluated with cervical spine CT at a level 1 trauma center from January to July 2007. Trauma registry data, including age, sex, injury severity score, mechanism of injury, length of stay, and diagnosis were recorded, and all CT scans of the cervical spine were reviewed for incidental findings. Clinically significant incidental findings were classified according to bodily location, and the association between various patient characteristics and the likelihood of an incidental finding was assessed. RESULTS: We identified incidental CT findings in 230 of 1,256 patients (18.3%) who underwent CT of the cervical spine during an initial trauma evaluation. We stratified the incidental findings as trauma-related and not trauma-related. The likelihood of non-trauma-related incidental findings was associated with age (p < 0.0001). The likelihood of trauma-related incidental findings was associated with injury severity score (p < 0.0001). CONCLUSION: Incidental findings in the cervical spine were associated with age, injury severity score, and mechanism of injury. Awareness of the prevalence of incidental findings is important to assuring that both traumatic and nontraumatic pathologic findings are detected and appropriately managed.

Posterior tibialis tendon tears: comparison of the diagnostic efficacy of magnetic resonance imaging and ultrasonography for the detection of surgically created longitudinal tears in cadavers.

RATIONALE AND OBJECTIVES: The optimal advanced imaging method for detection and characterization of posterior tibialis tendon (PTT) tears is unclear. The purpose of this study was to investigate the utility of ultrasonography (US) and MR imaging in the detection of surgically created PTT tears in cadavers. MATERIALS AND METHODS: This was a prospective blinded study in which 16 fresh cadaveric foot and ankle specimens (3 men, 13 women; average age at death 83.9 years; age range 71-96 years) were scanned with both US and MR imaging before and after the surgical creation of 64 variable length longitudinal tears of the PTT. Ultrasonography was performed with a 12 MHz linear transducer with independent interpretations of static and dynamic studies separately by two blinded and experienced musculoskeletal radiologists. MR imaging was performed at 1.5 T with a standard transmit-receive extremity coil using axial, sagittal, coronal T1-weighted (TR 600, TE 20), and axial fast spin echo proton density and T2-weighted (TR 3000, TE 161/20, ETL 12) images. MR images were reviewed independently by two experienced musculoskeletal radiologists who were blinded to the status of the PTT. RESULTS: Sensitivity, specificity, and accuracy of MR imaging in the diagnosis of PTT tears were 73%, 69%, and 72%, respectively. Dynamic US interpretation yielded values of 69% sensitivity, 81% specificity, and 72% accuracy. Static US interpretation was less reliable than dynamic interpretation, and the only significance of static imaging was a high specificity (94%) for detection of longitudinal tears. The positive predictive value (PPV) for MR imaging and US was 88% and 92% respectively, and the negative predictive value (NPV) was 46% for both MR imaging and US. CONCLUSION: Our results suggest that US and MR imaging perform at the same level for the detection of surgically created longitudinal PTT tears in a cadaveric model. US has a higher specificity compared with MR imaging.

Pathologic conditions of the ligaments and tendons of the knee.

Excellent spatial resolution and unparalleled contrast resolution have allowed MRI to emerge as the dominant imaging modality for diagnosis of ligament and tendon pathology of the knee joint This article presents several important mechanisms of injury associated with tendon and ligament disruptions. When present, the pattern of bone contusions may reveal the vector of force. When one is aware of the mechanism of injury, it is possible to analyze systematically the structures of the knee and maximize the detection of pathology. Recognition of a knee dislocation pattern is important because the diagnosis may be unsuspected, and the clinician may have to be alerted to the possibility of vascular and neural injury.

Visualization of ankle tendons and ligaments with MR imaging: influence of passive positioning.

PURPOSE: To determine if passive positioning of the ankle influences the MR imaging appearance of ankle tendons and ligaments. METHODS: A positioning device was used during imaging of 10 volunteers. Axial and coronal T1-weighted images were acquired in six positions of the ankle, and the appearance of the tendons and lateral ligaments was subjectively evaluated. RESULTS: The peroneus longus (PL), peroneus brevis (PB), anterior tibialis (AT), extensor digitorum longus (EDL), and extensor hallucis longus (EHL) tendons were best visualized in 20 degrees of plantarflexion and 20 degrees of inversion (p < 0.0001). The anterior talofibular (ATF) and calcaneofibular (CF) ligaments were best seen in 20 degrees of plantarflexion (p < 0.0001). Ten degrees of dorsiflexion was the least useful imaging plane for all of the aforementioned structures. CONCLUSION: When there is clinical concern regarding pathology of a specific structure about the ankle, passive positioning may allow optimal evaluation.

MR patterns of involvement of humeral head osteonecrosis.

PURPOSE: To characterize osteonecrosis of the humeral head on coronal and axial MR images. METHODS: We retrospectively reviewed MR examinations in patients with humeral head osteonecrosis. The angle of the entire affected articular surface at three levels was measured and an angle subtended by the margins of osteonecrosis was also measured. RESULTS: The appearance of osteonecrosis is identical to that in the femoral head with signal abnormality (13/13), double-line sign (7/13), and subchondral fractures (3/13). The superior aspect of the humeral head was the most common location of osteonecrosis. The MR staging resulted as follows: stage II (6/13), stage IIIA (1/13), stage IIIB (1/13), and stage IV (5/13). The maximum percentage of involvement of the articular surface demonstrated the following distribution: 0% to 25%, 0/11; 25% to 50%, 1/13; 50% to 75%, 5/13; and 75% to 100%, 7/13. CONCLUSIONS: Quantitative analysis of the percentage of involvement of the humeral head was performed and indicates that in most cases, 75% to 100% of the articular surface at the levels measured was involved.

In vivo high-resolution MR imaging of the carpal tunnel at 8.0 tesla.

OBJECTIVE: To determine the feasibility of acquiring in vivo images of the human carpal tunnel at 8 tesla (T). DESIGN: The wrist of an asymptomatic volunteer was imaged with an 8 T /80 cm magnet. The subject was imaged prone with the arm over the head and the wrist placed in neutral position in a custom-built dedicated shielded wrist coil. Axial two-dimensional gradient-echo (GRE) images of the wrist were acquired. RESULTS: Image contrast and resolution at 8 T are excellent. The infrastructure of the median nerve, particularly the interfascicular epineurium and individual fascicles, is better visualized at 8 T than at 1.5 T. The flexor tendons are well delineated from each other and the surrounding soft tissues, and tertiary tendon fiber bundles are resolved. The boundaries of the carpal tunnel are better defined at 8 T. CONCLUSION: We have obtained the first high-quality in vivo images of the human carpal tunnel at 8 T. The 8 T images demonstrated better contrast and resolution than those obtained at 1.5 T.

In vivo high resolution coronal MRI of the wrist at 8.0 tesla.

The wrists of asymptomatic volunteers were imaged at 8 and 1.5 T. The signal-to-noise ratio, spatial resolution, and soft tissue contrast of the 8 T images were much greater. The increased signal-to-noise ratio available at 8 T allows acquisition of high quality, high resolution images and visualization of intricate anatomy at scan times acceptable for clinical imaging.