MR imaging of scaphoid fractures. Fat-saturated T2-weighted and Short tau inversion recovery images.

Objective: Traumatic injuries of os scaphoideum are serious, and might lead to two main grades of consequences (i.e. osteoarthrosis or avascular necrosis), if a fracture remains undiagnosed. Bone bruise may be the only pathological sign of pain which can last for week or month. Articles describe the importance of early MRI and hereby predict bone bruise with the help of fat suppression sequence; however, only a limited selection articles compares various fat suppression techniques. The purpose of this prospective study was to compare the short tau inversion recovery (STIR) and T2 fat saturation (FAT SAT) sequences, sectional directed along the scaphoid bone axis. In relation to background fat intensity suppression, this study sought the sequence that best evaluated posttraumatic bone marrow edema (bone bruise) on scaphoid injury musculoskeletal magnetic resonance imaging (MRI, 1.5 T extremity scanner). Materials and methods: Two hundred and fifty-one patients with relevant trauma and positive clinical test for scaphoid bone fractures, exceeding no more than 14 days, underwent MRI examinations. A fast STIR and T2 FAT SAT fast spin echo sequence (FSE) were obtained using a comparable parameter setting (scan time ca. 3 minutes). Three experienced readers (one radiographer and two radiologists) carried out the evaluation blinded to each other’s, based on a quantitative assessment of size (area) and image quality (image contrast, IC and contrast-to-noise ratio, CNR). The study period lasted March 2014-April 2015. Sixty patients met the inclusion criteria and were enrolled. This prospective study was ethically approved by the institutional review board. Results: There were no significant difference between the bone bruise areas (P=0.45, P=0.44 and P=0.83) or CNR (P=0.31, P=0.38 and P=0.17). However, image contrast showed significant difference in favour of T2 FAT SAT in all three readers’ reports (P<0.05, P<0.05 and P<0.05). Conclusions: The two sequences appear almost identical. An interchangeable usage of the two sequences was found being acceptable for the diagnosis if the protocol is composed appropriately (1.5T). However, the T2 FAT SAT provided a higher image contrast by specific settings (e.g. short TI = 125 ms) compared to STIR

MR imaging of scaphoid fractures. Fat-saturated T2-weighted and Short tau inversion recovery images.

Objective: Traumatic injuries of os scaphoideum are serious, and might lead to two main grades of consequences (i.e. osteoarthrosis or avascular necrosis), if a fracture remains undiagnosed. Bone bruise may be the only pathological sign of pain which can last for week or month. Articles describe the importance of early MRI and hereby predict bone bruise with the help of fat suppression sequence; however, only a limited selection articles compares various fat suppression techniques. The purpose of this prospective study was to compare the short tau inversion recovery (STIR) and T2 fat saturation (FAT SAT) sequences, sectional directed along the scaphoid bone axis. In relation to background fat intensity suppression, this study sought the sequence that best evaluated posttraumatic bone marrow edema (bone bruise) on scaphoid injury musculoskeletal magnetic resonance imaging (MRI, 1.5 T extremity scanner).Materials and methods: Two hundred and fifty-one patients with relevant trauma and positive clinical test for scaphoid bone fractures, exceeding no more than 14 days, underwent MRI examinations. A fast STIR and T2 FAT SAT fast spin echo sequence (FSE) were obtained using a comparable parameter setting (scan time ca. 3 minutes). Three experienced readers (one radiographer and two radiologists) carried out the evaluation blinded to each other’s, based on a quantitative assessment of size (area) and image quality (image contrast, IC and contrast-to-noise ratio, CNR). The study period lasted March 2014-April 2015. Sixty patients met the inclusion criteria and were enrolled. This prospective study was ethically approved by the institutional review board.Results: There were no significant difference between the bone bruise areas (P=0.45, P=0.44 and P=0.83) or CNR (P=0.31, P=0.38 and P=0.17). However, image contrast showed significant difference in favour of T2 FAT SAT in all three readers’ reports (P&lt;0.05, P&lt;0.05 and P&lt;0.05).Conclusions: The two sequences appear almost identical. An interchangeable usage of the two sequences was found being acceptable for the diagnosis if the protocol is composed appropriately (1.5T). However, the T2 FAT SAT provided a higher image contrast by specific settings (e.g. short TI = 125 ms) compared to STIR

Cortical representation of auricular muscles in humans: A robot-controlled TMS mapping and fMRI study.

BACKGROUND:Most humans have the ability to activate the auricular muscles. Although (intentional) control suggests an involvement of higher cortical centers underlying posterior auricular muscle (PAM) activation, the cortical representation of the auricular muscles is still unknown. METHODS:With the purpose of identifying a possible cortical representation area we performed automated robotic and image-guided transcranial magnetic stimulation (TMS) mapping (n = 8) and functional magnetic resonance imaging (fMRI) (n = 13). For topographical comparison, a similar experimental protocol was applied for the first dorsal interosseus muscle (FDI) of the hand. RESULTS:The calculated centers of gravity (COGs) of both muscles were located on the precentral gyrus with the PAM COGs located more laterally compared to the FDI. The distance between the mean PAM and mean FDI COG was 26.3 mm. The TMS mapping results were confirmed by fMRI, which showed a dominance of cortical activation within the precentral gyrus during the corresponding motor tasks. The correspondence of TMS and fMRI results was high. CONCLUSION:The involvement of the primary motor cortex in PAM activation might point to an evolved function of the auricular muscles in humans and/or the ability of intentional (and selective) muscle activation

Positions of individual COGs of FDI and PAM on the MNI152 T1 template.

<p>Colors indicate different subjects. The average distance between the individual PAM and FDI COGs is 23.8 mm (SD: 5.1 mm). The individual TMS PAM coordinates were [-57, 9, 39] in subject 1; [-48, 4, 52] in subject 2; [-50, -1, 53] in subject 3; [-50, 7, 48] in subject 4; [-50, 0, 53] in subject 5; [-49, -10, 60] in subject 6; [-49, 6, 53] in subject 7 and [-47, 2, 51] in subject 8.</p

Human auricular muscles.

<p>Extrinsic (a—c) and intrinsic (1–6) auricular muscles. a = anterior auricular muscle, b = superior auricular muscle, c = posterior auricular muscle; 1 = helicis major, 2 = helicis minor, 3 = tragicus, 4 = antitragicus, 5 = oblique, 6 = transverse; the 5 and 6 are located on the back of the pinna.</p

Cortical fMRI activation during PAM and FDI activation.

<p>Series of coronar fMRI images at Talairach Y = 10, 0, -10, -20, -30, -40, -50 with cortical activation during index finger movement (red), movement of the pinna (blue) and overlapping areas (purple) (P < 0.001; t(12) > 4.32).</p

Placement of fine-wire electrodes.

<p>Fine-wire electrode with a total length of about 10 cm and a diameter of 50μm. Insulation was removed at both ends and along 1cm in the middle of the electrode (a). The electrode positioned within the injection needle (b). After piercing the skin twice, the electrode is retained and the needle is pulled back. The position of the electrode can be easily adjusted by pulling at either side. The stripped middle part of the electrode is located under the skin (c). Both electrodes in situ with the active electrode within the PAM (left) and the reference electrode in the middle of the pinna (right) (d).</p

Positions of the individual fMRI and TMS COGs of PAM and FDI registered to the MNI152 T1 template.

<p>The TMS PAM COGs (yellow) are located on the precentral gyrus lateral to the TMS FDI COGs (green). The fMRI PAM (blue) and FDI (red) COGs are located more posterior on the precentral gyrus in comparison to the TMS COGs.</p

Distances between PAM and FDI COGs.

<p>Distances (in mm) between mean and individual PAM and FDI COGs calculated from TMS mapping. Error bars indicate standard deviation.</p