Visualization of Stent Lumen in MR Imaging: Relationship with Stent Design and RF Direction

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Magnus Sparks
5 years ago
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1 Visuliztion of Stent Lumen in MR Imging: Reltionship with Stent Design nd RF Direction,*,c d e f f c d e

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Stent 6: Two connections comprising lternting upper nd lower joints (on the right nd left), similr to Moeius pttern (-connection pttern).

3 June 0 Visuliztion of Stent Lumen in MR Imging Stent Stent 7 0 Stent 6 Stent Fig. Conﬁgurtion of the design digrms of stent models. Stent : One connection (etween the upper nd lower levels of zigzg ptterns) in the center (-connection pttern). Stent 6: Two connections comprising lternting upper nd lower joints (on the right nd left), similr to Moeius pttern (-connection pttern). Stent 7: A ring-shped connection etween the upper nd lower lyers (one-turn pttern). Stent : Similr to Stent 7 (one-turn pttern) ut with one cut (one-turn with cut pttern). Stent models re mde y rolling the illustrted conﬁgurtions of etched copper foil nd joining red dotted lines -ʼ to -ʼ. A B Fig. Cylindricl stents mde y rolling the illustrted shpes in Figs. or. (A) is Stent (mesh); (B) is Stent 6 (-connection). ｵ crrgeenn (60g),.7 mol/kg GdCl (0.00g),.ｵ grose (.6g), 0.77ｵ NCl (.g), 0.0ｵ NN (0.6g), nd.g of wter. The produced phntom hd T vlue of 67ms, T vlue of 7ms, electricl conductivity of 0.6S/m, nd reltive permittivity of 7. The ingredients were mixed in n enmel-coted porcelin continer (columnr shpe; dimeter: 60mm; cpcity: liters) nd dissolved in n oil th. While the phntom ws in liquid form, one ech of the types of stents ws inserted into the phntom with the xes of the stents prllel to the xis of the phntom continer, nd then the phntom ws gelled t room temperture. Plcement of the stents in the phntom ws done rndomly. The shpe of the gelled columnr phntom ws 60mm in dimeter nd 0mm high. A.-T MRI system (Achiev. T, Philips Medicl Systems, The Netherlnds) ws used, nd MRI ws performed t room temperture of ±. A ody coil instlled in the MRI system ws used s trnsmitter coil, nd n -chnnel SENSE hed coil ws used s receiver coil. Stent xes were oriented in one of directions y turning the gel phntom, ligning the stents xes either perpendiculr or prllel to the sttic mgnetic

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June 0 Visuliztion of Stent Lumen in MR Imging (solenoid) lumen hd mildly low signl intensity when the stent xis ws prllel to, ut it hd the sme intensity s the re outside the lumen when the stent xis

B nd C show the distriutions of RF mgnetic ﬂux density on the z-x plne t y 0 when the direction of rottes on the x-y plne. The rrow indictes the direction of mgnetic ﬂux density t certin instnt.

7 June 0 Visuliztion of Stent Lumen in MR Imging (solenoid) lumen hd mildly low signl intensity when the stent xis ws prllel to, ut it hd the sme intensity s the re outside the lumen when the stent xis ws perpendiculr to. The Stent (Moeius) lumen showed the sme signl intensity s the re outside the lumen, regrdless of the direction. Computed illustrtions of Stents,, nd re shown in Fig. A. Figs. B nd C show the distriutions of RF mgnetic ﬂux density on the z-x plne t y 0 when the direction of rottes on the x-y plne. The rrow indictes the direction of mgnetic ﬂux density t certin instnt. The centrl xis of the stent in Fig. B coincides with the x-xis; tht in Fig. C coincides with the z-xis. The rrows in the ﬁgures represent the vectors of the mgnetic ﬂux density t the moment tht the direction of turns to x-xis. As shown in Figs. B nd C, the lumen of the mesh pttern stent exhiits reduced mgnetic ﬂux density irrespective of the direction of. The solenoid pttern stent lumen shows reduced mgnetic ﬂux density when the stent xis is prllel to, ut no such reduction when the stent xis is perpendiculr to. The lumen of the Moeius pttern stent exhiits no reduction of mgnetic ﬂux density regrdless of the direction of. Stent Axis Stent Axis Mesh pttern stent 0 Solenoid pttern stent Moeius pttern stent A B C Fig. Computed mgnetic ﬂux density distriution in mesh, solenoid, nd Moeius pttern stents. A, Illustrtions showing the schem of the mesh pttern stent (top left), solenoid pttern stent (middle left), nd Moeius pttern stent (ottom left); B, Mgnetic ﬂux distriutions with the stent xes prllel to.; C, Mgnetic ﬂux distriutions with the stent xes perpendiculr to.

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Severe Gummy Smile with Class II Malocclusion Treated with LeFort I Osteotomy Combined with Horseshoe Osteotomy and Intraoral Vertical Ramus

Severe Gummy Smile with Class II Malocclusion Treated with LeFort I Osteotomy Combined with Horseshoe Osteotomy and Intraoral Vertical Ramus 2013 67 1 5560 Severe Gummy Smile with Clss II Mlocclusion Treted with LeFort I Osteotomy Comined with Horseshoe Osteotomy nd Introrl Verticl Rmus Osteotomy * 56 Shimo et l. Act Med. Okym Vol. 67, No.