Assessment of image quality in soft tissue and bone visualization tasks for a dedicated extremity cone-beam CT system.

OBJECTIVE: To assess visualization tasks using cone-beam CT (CBCT) compared to multi-detector CT (MDCT) for musculoskeletal extremity imaging. METHODS: Ten cadaveric hands and ten knees were examined using a dedicated CBCT prototype and a clinical multi-detector CT using nominal protocols (80 kVp-108mAs for CBCT; 120 kVp- 300 mAs for MDCT). Soft tissue and bone visualization tasks were assessed by four radiologists using five-point satisfaction (for CBCT and MDCT individually) and five-point preference (side-by-side CBCT versus MDCT image quality comparison) rating tests. Ratings were analyzed using Kruskal-Wallis and Wilcoxon signed-rank tests, and observer agreement was assessed using the Kappa-statistic. RESULTS: Knee CBCT images were rated "excellent" or "good" (median scores 5 and 4) for "bone" and "soft tissue" visualization tasks. Hand CBCT images were rated "excellent" or "adequate" (median scores 5 and 3) for "bone" and "soft tissue" visualization tasks. Preference tests rated CBCT equivalent or superior to MDCT for bone visualization and favoured the MDCT for soft tissue visualization tasks. Intraobserver agreement for CBCT satisfaction tests was fair to almost perfect (κ ~ 0.26-0.92), and interobserver agreement was fair to moderate (κ ~ 0.27-0.54). CONCLUSION: CBCT provided excellent image quality for bone visualization and adequate image quality for soft tissue visualization tasks. KEY POINTS: • CBCT provided adequate image quality for diagnostic tasks in extremity imaging. • CBCT images were "excellent" for "bone" and "good/adequate" for "soft tissue" visualization tasks. • CBCT image quality was equivalent/superior to MDCT for bone visualization tasks.

High-resolution 3T MR neurography of the brachial plexus and its branches, with emphasis on 3D imaging.

With advancement in 3D imaging, better fat-suppression techniques, and superior coil designs for MR imaging and the increasing availability and use of 3T magnets, the visualization of the complexity of the brachial plexus has become facile. The relevant imaging findings are described for normal and pathologic conditions of the brachial plexus. These radiologic findings are supported by clinical and/or EMG/surgical data, and corresponding high-resolution MR neurography images are illustrated. Because the brachial plexus can be affected by a plethora of pathologies, resulting in often serious and disabling complications, a better radiologic insight has great potential in aiding physicians in rendering superior services to patients.

Anatomic MR imaging and functional diffusion tensor imaging of peripheral nerve tumors and tumorlike conditions.

BACKGROUND AND PURPOSE: A number of benign and malignant peripheral nerve tumor and tumorlike conditions produce similar imaging features on conventional anatomic MR imaging. Functional MR imaging using DTI can increment the diagnostic performance in differentiation of these lesions. Our aim was to evaluate the role of 3T anatomic MR imaging and DTI in the characterization of peripheral nerve tumor and tumorlike conditions. MATERIALS AND METHODS: Twenty-nine patients (13 men, 16 women; mean age, 41±18 years; range, 11-83 years) with a nerve tumor or tumorlike condition (25 benign, 5 malignant) underwent 3T MR imaging by using anatomic (n=29), functional diffusion, DWI (n=21), and DTI (n=24) techniques. Images were evaluated for image quality (3-point scale), ADC of the lesion, tractography, and fractional anisotropy of nerves with interobserver reliability in ADC and FA measurements. RESULTS: No significant differences were observed in age (benign, 40±18 versus malignant, 45±19 years) and sex (benign, male/female=12:12 versus malignant, male/female=3:2) (P>.05). All anatomic (29/29, 100%) MR imaging studies received "good" quality; 20/21 (95%) DWI and 21/24 (79%) DTI studies received "good" quality. ADC of benign lesions (1.848±0.40×10(-3) mm2/s) differed from that of malignant lesions (0.900±0.25×10(-3) mm2/s, P<.001) with excellent interobserver reliability (ICC=0.988 [95% CI, 0.976-0.994]). There were no FA or ADC differences between men and women (P>.05). FA of involved nerves was lower than that in contralateral healthy nerves (P<.001) with excellent interobserver reliability (ICC=0.970 [95% CI, 0.946-0.991]). ADC on DTI and DWI was not statistically different (P>.05), with excellent intermethod reliability (ICC=0.943 [95% CI, 0.836-0.980]). Tractography differences were observed in benign and malignant lesions. CONCLUSIONS: 3T MR imaging and DTI are valuable methods for anatomic and functional evaluation of peripheral nerve lesions with excellent interobserver reliability. While tractography and low FA provide insight into neural integrity, low diffusivity values indicate malignancy in neural masses.

Peripheral nerve surgery: the role of high-resolution MR neurography.

High-resolution MRN is becoming increasingly available due to recent technical advancements, including higher magnetic field strengths (eg, 3T), 3D image acquisition, evolution of novel fat-suppression methods, and improved coil design. This review describes the MRN techniques for obtaining high-quality images of the peripheral nerves and their small branches and imaging findings in normal as well as injured nerves with relevant intraoperative correlations. Various microsurgical techniques in peripheral nerves, such as neurolysis, nerve repairs by using nerve grafts, and conduits are discussed, and MRN findings of surgically treated nerves are demonstrated.

High-resolution MR neurography of diffuse peripheral nerve lesions.

High-resolution MR imaging of peripheral nerves is becoming more common and practical with the increasing availability of 3T magnets. There are multiple reports of MR imaging of peripheral nerves in compression and entrapment neuropathies. However, there is a relative paucity of literature on MRN appearance of diffuse peripheral nerve lesions. We attempted to highlight the salient imaging features of myriad diffuse peripheral nerve disorders and imaging techniques for MRN. Using clinical and pathologically proved relevant examples, we present the MRN appearance of various types of diffuse peripheral nerve lesions, such as traumatic, inflammatory, infectious, hereditary, radiation-induced, neoplastic, and tumor variants.