Imaging Evaluation Of The Intravitreous Wooden Foreign Body In Rabbits

Backgroud and purposeIntraocular foreign body is a special eye trauma and common emergency of ophathalmology. Intraocular wooden foreign body is seldom, but it is greatly harmful to eyeball, easier to misdiagnose and missed diagnosis and lead to more complication, While the imaging examination plays an important role in the diagnosis of intraocular foreign body. It is very important to diagnose and remedy early. The research is devoted to discuss the diagnosed value of MRI, CT and ultrasonography in wooden foreign body in rabbit’s vitreous body, discussing the evolution rule of wooden foreign body in rabbit’s vitreous body.Material and Methods240Japanse big-ear healthy rabbits were provided by Henan kangda experimental animal Co.,LTD, weight2.0-2.5kg, either sex, their eyes were normal. Foreign bodies were surgically implanted into the vitreous body of the experimental animals’right eye. Wooden foreign bodies consist of poplar wood, Paulownia, pine wood and China rose. The average diameter of foreign body was0.2mm, the length were2mm, lmm,0.5mm and0.2mm. In accordance with the length of foreign body to group, experimental group contained192rabbits, divided into A, B, C and D group, every group had48rabitts, A, B, C and D group respectively standed for the length of foreign body were2mm, lmm,0.5mm,0.2mm. The experimental groups were divided into16sub-groups according to the sort of foreign body, every sub-group contained12rabbits.The group of A1, B1, C1and D1standed for poplar wood. The group of A2, B2, C2and D2standed for firmiana wood. The group of A3, B3, C3and D3standed for pine. The group of A4, B4, C4and D4standed for China rose. Each sub-group of sixteen sub-groups was divided into32sub-groups according to dry and wet of foreign bodies, every sub-group had6babbits, respectively divided into Ala, Bla, Cla, Dla, A2a, B2, C2a, D2a, A3a, B3a, C3a, D3a, A4a, B4a, C4a and D4a standed for dry foreign bodies, A1b, B1b, Cb, D1b, A2b, B2b, C2b, D2b, A3b, B3b, C3b, D3b, A4b, B4b, C4b and D4b standed for wet foreign bodies. Ala, Alb, A2a, A2b, A3a, A3b, A4a and A4b of the experimental A group did examine MRI, CT and ultrasonography2hours after operation, after examination,2experimental animals were selected from every group of the8above groups were executed immediately, removed their right eyeballs and made pathology examination. The remaining A group experimental animals raised2weeks after operation were examined by MRI, CT and ultrasonography, after examination,2experimental animals were selected from every group were executed immediately, removed their right eyeballs and made pathology examination. The remaining experimental animals rasied4weeks after operation were examined by MRI, CT and ultrasonography, after examination, they were executed immediately, removed their right eyeballs and made pathology examination. According to CT detecting or not A group foreign bodies to decide B, C, D group whether do CT scan, if CT do not detect foreign bodies in group A, the remaining groups only do MRI and ultrasonography examination.Group E was control group, had48rabitts.To puncture right eyeball lead to the same vulnus, but didn’t implant foreign body. Control group was divided into3groups of El, E2and E3. Every group contained16rabitts.The experimental animals of group El were executed2hours after operation to make pathology examination. The experimental animals of group E2were executed2weeks after operation to make pathology examination. The experimental animals of group E3were executed4weeks after operation to make pathology examination.MRI used Siemens3.0T Verio scanner and a dedicated coil of the Shanghai dawn Medical Devices Co., Ltd. Making rabbit eye axial, oblique sagittal and coronal scan. MR imaging of the rabbit’s eye was performed with T1WI (T1-weighted imaging, T1WI), T2WI (T2-weighted imaging, T2WI), PDWI (proton-weighted imaging, PDWI) and SWI (susceptibility-weighted imaging, SWI) axial, oblique sagittal and coronal scan. Recorded of the detected foreign bodies’s pieces and the number of complications on T1WI, T2WI, PDWI, and SWI, and measured diameter of the foreign bodies. At the same time, measured Mag value, Pha value, mIP value and SWI value of the foreign body on Mag (Magnitude image, Mag) map, Pha (Phase image) map, mIP(Minimal intensity projection, mIP) map, SWI(susceptibility weighted imaging, SWI) map.CT examination with High-definition Discovery CT750HD. GE Healthcare, tube voltage was80kv, tube current was200As, speed0.8seconds/rev, pitch0.984:1, slice thickness was1.25mm, the interlayer spacing of1.25mm. Made rabbit eye axial scan, the scan mode was spectrum scanning. Recorded of the detected foreign bodies’s pieces and the number of complications on CT, and measured diameter of the foreign bodies.Ultrasonography examination of GE the login S6, color doppler ultrasonography, high-frequency linear array probe frequency7.0MHz. Using the the eyelids direct contact method of inspection, rotating probe, which fully demonstrates each position of SPECT images. Recorded of the detected foreign bodies’s pieces and the number of complications on Ultrasonography, and measured diameter of the foreign bodies.Put to death in experimental animals, picking out the right eye, fixed, paraffin embedded,5μm serial sections, HE staining was observed by light microscop.SPSS16.0was adopted to analyse all the dataes.Results1. Wooden foreign bodies were punctate or linear low signal on T1WI, T2WI and PDWI. They were punctate or linear low signal on magnitude image, minimum intensity projection and susceptibility weighted imaging on SWI. They are punctate or linear low signal (67), mixed singnal (23) and high singnal(39) on Phase image.2. On CT, the length of2mm wooden foreign bodies were not detected.3. On sonogram, foreign body showed a strong echo of the light spot.4. To192foreign bodies, the detection rate of MRI (T2WI) was49.5%and the detection rate of the ultrasonography was71.4%. To48length of2mm foreign bodies, CT was not clearly demonstrated the foreign bodies, the sensitivity of detection was lower. The minimum length of wooden foreign bodies detected by MRI (T2WI) and ultrasonography was0.5mm. Detection rate of MRI and ultrasonography for foreign bodies tended to increase with the increase of the foreign bodies’s length, MRI (T2WI) and ultrasonography for foreign bodies’s detection rate of dry pine wood and China rose differences were statistically significant (p<0.05), the detection rate of ultrasonography for dry pine wood and China Rose foreign bodies exceeded MRI. The detection rate of MRI (T2WI) and ultrasonography of dry poplar wood and paulownia, wet poplar wood, paulownia, pine wood and China Rose foreign bodies had no statistically significant differences (p>0.05). The main factor affecting detection rate of MRI (T2WI) was the length of the foreign bodies, it had no relevant with texture, dry and wet condition of foreign bodies. Texture, length, dry and wet condition of foreign bodies did not influence the detection rate of ultrasonography.5.To192foreign bodies, the detection rate of T1WI was4.1%, the detection rate of T2WI was49.5%, the detection rate of PDWI was15.6%, the detection rate of SWI(SWI map) was67.2%. All sequences were not detected the length of0.2mm of foreign bodies. T2WI and SWI(SWI map) could detect foreign bodies with the length of0.5mm, lmm and2mm. T1WI only could detect the length of2mm of foreign bodies. PDWI could detect the length of lmm and2mm of foreign bodies. Sensitivity of T2WI and SWI was over Tl WI and PDWI. The difference of the detection rate of dry poplar wood foreign bodies with T2WI and SWI was only statistically significant(P<0.05). The differences of the detection rate of wet poplar wood, the wet and dry paulownia, pine wood, China rose foreign bodies were not statistically significant (p>0.05). 6. Mag map, Pha map, mIP map and SWI map could detect foreign bodies with the length of0.5mm,1mm,2mm. The Mag map, Pha map and SWI map was consistent with the result of detection, all the detection rate of them was67.2%, the detection rate of mIP map was63.5%.7. The differences among of the Mag value, Pha value, mIP value and SWI value were statistically significant(p<0.05). Pha Value was274.5, Mag value was198.6, swi value was145.3, mIP value was105.7.The length of foreign body had an influence with Mag value(P<0.001), the longer foreign body, the higher Mag value. Texture of foreign body had an influence with Mag value(P<0.05), the highest was poplar wood, next was pine wood, Mag value of China Rose and Paulownia were similar. Dry and wet conditions of foreign body had no influence with Mag value (p>0.05).The length, texture, dry and wet conditions of foreign body had no influence with Pha value (p>0.05).The length of the foreign body influenced mIP value(P<0.001), the longer of the foreign body, the higher of the mIP value. Texture of foreign body affected mIP value (P<0.05), The mIP value of paulownia was lower than the other three kinds of the foreign bodies. Dry and wet conditions of foreign body had no influence with mIP value (p>0.05).The length of the foreign body affected the SWI values (p<0.001), the longer of the foreign body, the higher of the SWI value. The material of foreign body had no effect with SWI value (p>0.05). The dry and wet conditions of the foreign body affected the SWI value, the SWI value of moist foreign body was higher than that of dry foreign body (p<0.05).8. The difference among of the diameter of the foreign body measured by MRI (T2WI) and ultrasonography, overall0.2mm were statistically significant (p<0.001). The measured diameter on MRI and ultrasonography was respectively0.227±0.045and0.250±0.050mm. The difference among of the diameter of the foreign body measured by T1WI, T2WI, PDWI and SWI, overall0.2mm was statistically significant(p<0.001). The measured diameter on MRI and ultrasonography was respectively0.100±0.000,0.227±0.045,0.147±0.051,0.530±0.057mm. 9. Three methods of detecting the length of2mm wooden foreign body implanted in2hours, and breeded2weeks and4weeks of the detection rate of complications differences were not statistically significant(p>0.05).10. The wall of eyeball from16experimental animals implanted foreign body2hours had no inflammatory cells. Foreign bodies of2weeks in16experimental animals in the eyeball’s wall, a small amount inflammatory cells of9, moderate of7. Foreign bodies of4weeks in16experimental animals in the eye ball’s wall, a small amount inflammatory cells of1, moderate of7, a large number of8. The wall of the control group eye have no inflammatory cells after operation2hours,2weeks and4weeks.Conclusion1. MRI and ultrasonography are the effective methods of diagnosing wooden foreign body in vitreous body. For the foreign body whose diameter is2mm, the length is the main factor to affect the MRI detection.2. Among MRI sequences, T2WI and SWI are the preferred sequences in diagnosing wooden foreign body in vitreous body. The Mag value, Pha value, mIP value and SWI value of the wooden foreign bodies are different.3. T1WI and PDWI underestimate the diameter of the foreign body, while T2WI, SWI and ultrasonography overestimate the diameter of the foreign body, SWI has a effect of significantly enlarged.4. Wooden foreign body retained in the vitreous body can lead to inflammatory changes.