Multimodal Imaging of Globe Compression Caused by a Displaced Orbital Fracture.

To quantify the degree of dural compression and assess the association between site and direction of compression and articular process (AP) size and degree of dural compression with CT myelography. 26 client-oriented horses with ataxia. Spinal cord-to-dura and AP-to-cross-sectional area of the C6 body ratios (APBRs) were calculated for each noncompressive site and site that had > 50% compression of the subarachnoid space. Site of maximum compression had the largest spinal cord-to-dura ratio. Fisher exact test and linear regression analyses were used to assess the association between site and direction of compression and mean or maximum APBR and spinal cord-todura ratio, respectively. Mean ± SD spinal cord-to-dura ratio was 0.31 ± 0.044 (range, 0.20 to 0.41) for noncompressive sites and 0.44 ± 0.078 (0.29 to 0.60) for sites of maximum compression. Sites of maximum compression were intervertebral and extra-dural, most frequently at C6 through 7 (n = 10), followed by C3 through 4 (6). Thirteen horses had dorsolateral and lateral compression at the AP joints, secondary to AP (n = 7) or soft tissue proliferation (6). Site significantly affected direction of compression, and directions of compression from occiput through C4 were primarily ventral and lateral, whereas from C6 through T1 were primarily dorsal and dorsolateral. No linear relationship was identified between mean or maximum APBR and spinal cord-to-dura ratio. CT myelography may be useful for examination of horses with suspected cervical compressive myelopathy. Degree of compression can be assessed quantitatively, and site of compression significantly affected direction of compression.

A 64-year-old man presented with painless, progressive proptosis of the OS that lasted for several years. Clinical examination revealed severe downward deviation of the eyeball and a firm palpable mass above the eyeball (Fig. 1A). Visual acuity was “hand motion,” and the fundus could not be observed because of hypermature cataract. B-scan ultrasound revealed severe compression of the upper eyeball by the orbital mass (Fig. 1B), and MRI revealed a 3.5 cm-sized well-defined round mass above the eyeball (Fig. 1C,D).FIG. 1.: Preoperative findings of the patient and surgical specimen of the removed orbital mass. A, External photograph shows severe downward deviation of the left eye. B, B-scan ultrasound shows compression of the upper eyeball by the orbital mass. C, D, Magnetic resonance imaging (MRI) shows a 3.5-cm, well-defined, relatively homogeneous enhanced mass in the left superior orbit with severe inferior displacement of the eyeball. E, Gross specimen photograph of the well-encapsulated firm mass after complete excisional biopsy.Complete excisional biopsy of the mass was performed and diagnosed as pleomorphic adenoma of the lacrimal gland (Fig. 1E). Cataract surgery was performed after 2 months, and a degenerative retinal change was observed in the superior retina at the site of previous tumor compression (Fig. 2A). The optic disc showed no sign of optic atrophy (Fig. 2B). Optical coherence tomography (OCT) revealed dense sub-retinal pigment epithelium (RPE) material (red asterisk) and choroidal thinning (arrow heads) which were more prominent on the affected superior side (red dashed arrow) than inferior area (green dashed arrow, Fig. 2C). Choroidal thickness in the opposite eye was normal (Fig. 2D).FIG. 2.: Fundus photography and OCT images taken 8 months after orbital mass removal and 6 months after cataract surgery. A, Fundus photography shows well-demarcated retinal degeneration in the superior retina, previously compressed by the tumor (white dashed arrow: OCT scan location shown in Figure 2C). B, OCT evaluation of retinal nerve fiber layer shows retinal nerve fiber layer thickness within normal range. C, Vertical OCT scan of the left eye shows diffuse sub-RPE deposit in the superior retina (red asterisk); Choroidal thinning (arrow heads) is observed more than the opposite eye (D, arrow heads); Choroidal thinning seen prominently in the superior area (red dashed arrow) as compared to the inferior area (green dashed arrow). G, general; INT, inferior; N, nasal; NAS, nasal; NI, nasal inferior; NS, nasal superior; RNFLT, retinal nerve fiber layer thickness; SUP, superior; T, temporal; TI, temporal inferior; TMP, temporal; TS;temporal superior.The possibility of retinal degeneration by other etiologies cannot be completely ruled out. However, given the fact that degenerative retinal changes have been observed at previous tumor compression sites, the possibility of retinal degeneration by long-term compression can also be assumed. The possible pathophysiology is that the large orbital tumor mainly compresses the posterior ciliary arteries and affects choroidal circulation, while relatively conserving the central retinal artery traversing inside the optic nerve. Choroidal blood flow compromised over a long period can cause choroidal thinning and induce outer retinal and RPE degeneration. The diffuse sub-RPE deposits could be due to the outer retinal metabolite clearance failure caused by RPE dysfunction.

OBJECT The purpose of this study was to explore the use of super-resolution tract density images derived from probabilistic diffusion tensor imaging (DTI) tractography of the spinal cord as an imaging surrogate for microstructural integrity and functional impairment in patients with cervical spondylosis. METHODS Structural MRI and DTI images were collected for 27 patients with cervical spondylosis with (n= 21) and without (n= 6) functional impairment as defined by the modified Japanese Orthopaedic Association Scale (mJOA). DTI was performed axially through the site of compression in a total of 20 directions with 10 averages. Probabilistic tractography was performed at 0.5-mm isotropic spatial resolution using the streamline technique combined with constrained spherical deconvolution. The following measurements were calculated for each patient: maximum tract density at the site of compression, average tract density in rostral normal-appearing spinal cord, and the ratio of maximum density to normal density. RESULTS Compared with normal tissue, the site of compression exhibited elevated fiber tract density in all patients, and a higher fiber tract density was also noted in focal areas at the site of compression in patients with functional impairment. There was a strong negative correlation between maximum tract density and mJOA score (R(2)= 0.6324, p < 0.0001) and the ratio of maximum tract density to normal tract density (R(2)= 0.6647, p < 0.0001). When grouped according to severity of neurological impairment (asymptomatic, mJOA score of 18; mild, mJOA score of 15-17; moderate, mJOA score of 11-14; and severe, mJOA score < 11), the results showed a significant difference in the ratio between severe and both no impairment (p= 0.0009) and any impairment (p= 0.036). A ratio of maximum fiber tract density at the site of compression to fiber tract density at C-2 greater than 1.45 had 82% sensitivity and 70% specificity for identifying patients with moderate to severe impairment (ROC AUC= 0.8882, p= 0.0009). CONCLUSIONS These results support the use of DTI as a surrogate for determining spinal cord integrity in patients with cervical spondylosis. Probabilistic tractography provides spinal cord microstructural information that can help discern clinical status in cervical spondylosis patients with varying degrees of neurological impairment.

Desmoplastic trichoepithelioma (DTE) is a rare benign adnexal tumor with follicular differentiation that appears most frequently on the face of young women. It can clinically mimic a variety of skin tumors such as intradermal nevus, sebaceous hyperplasia, and basal cell carcinoma (BCC).1 Because of its overlapping clinical features, the diagnosis of DTE is usually established on histopathology. However, given the predilection of DTE on cosmetically sensitive areas on the face, the indication for biopsy should be as accurate as possible. Several noninvasive imaging techniques have emerged in recent years, aiming for higher accuracy of in vivo diagnosis. These include dermoscopy, reflectance confocal microscopy (RCM), and conventional optical coherence tomography (OCT). High-definition (HD) OCT (Skintell; Agfa HealthCare, Brussels, Belgium) is a recently introduced technique based on the same principles of conventional OCT but differing on its ability to give optical imaging up to 570 μm deep within the skin, with high resolution of 3 μm both in axial and lateral directions. The field of view is 1.8 × 1.5 mm, and the total light power at the tissue is less than 3.5 mW. The system works in direct contact with the skin. The interference signal detected by the 2-dimensional imaging sensor is digitized, subsequently transferred to a computer, and displayed through a grayscale or color palette resulting in an OCT image. High-definition OCT is capable of capturing not only slice but also en face images in real time and fast 3-dimensional acquisition. Therefore, HD-OCT allows in vivo examination of the skin, enabling visualization of individual cells with a greater depth than RCM. It also provides cross-sectional imaging like the conventional OCT. Additional technical details are discussed elsewhere. View on Journal Site Related Articles Imaging of Desmoplastic Trichoepithelioma by High-Definition Optical Coherence Tomography Dermatologic Surgery 2015; 41(4): 522–525. MULTIMODALITY IMAGING OF TORPEDO MACULOPATHY WITH SWEPT-SOURCE, EN FACE OPTICAL COHERENCE TOMOGRAPHY AND OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY Retinal Cases & Brief Reports 2018; 12(2): 153–157. Optical Coherence Tomography: Future Applications in Cerebrovascular Imaging Stroke 2018; 49(4): 1044–1050.

3 T magnetic resonance diffusion tensor imaging and fibre tracking in cervical myelopathy

High-resolution three-dimensional (3D) magnetic resonance imaging (MRI) has demonstrated its ability to predict fine trigeminal neurovascular anatomy. To address the predictive value of 3-Tesla (3T) MRI in detecting and assessing features of neurovascular compression (NVC), particularly regarding the degree of compression exerted on the root, in patients who underwent microvascular decompression (MVD) for classic primary trigeminal neuralgia. This prospective study includes 40 consecutive patients who underwent MVD for classic primary trigeminal neuralgia. All patients underwent a preoperative 3T MRI with 3D T2-weighted driven equilibrium (DRIVE), 3D time-of-flight (TOF) magnetic resonance angiography (MRA), and 3D T1-weighted gadolinium-enhanced sequences in combination. Evaluations were performed by 2 independent observers and compared with the operative findings. For prediction of NVC, image analysis corresponded with surgical findings in 39 cases. Of the 3 patients in whom image analysis did not show NVC, 2 did not have NVC at the time of intraoperative observation. MRI sensitivity was 97.4% (37/38), and specificity was 100% (2/2). The kappa coefficients (κ) for predicting the offending vessel, its location, and the site of compression were 0.882, 0.813, and 0.942, respectively. Image analysis correctly defined the severity of the compression in 31 of the 37 cases. The κ coefficients predicting the degree of compression were 0.813, 0.833, and 0.852, respectively, for Grades 1 (simple contact), 2 (distortion), and 3 (marked indentation). 3T MRI using 3D T2-weighted DRIVE in combination with 3D TOF-MRA and 3D T1-weighted gadolinium-enhanced sequences proved to be reliable in detecting NVC and in predicting the degree of root compression, the outcome being correlated with the latter.

Objective To explore the consistency of neurovascular relationships between multimodal image fusion 3D reconstruction and intraoperative findings in microvascular decompression (MVD) for primary trigeminal neuralgia (PTN). Methods A retrospective analysis was conducted on the clinical data of 50 PTN patients treated with MVD at Department of Neurosurgery, Qingdao University Hospital from January to November 2018. All subjects underwent three-dimensional time-flying magnetic resonance angiography (3D-TOF-MRA) and three-dimensional cyclic phase steady-state acquisition rapid imaging (3D-FIESTA) sequences. Then, the 3D-slicer software was used to reconstruct the multimodal fusion 3D image. Multimodal image fusion 3D reconstruction images and surgical video were analyzed to determine the offending vessels responsible for trigeminal neuralgia. At the same time, the direction of compression, compression site and compression degree of the trigeminal nerve were analyzed. Kappa consistency test method was used to judge the consistency of the two approaches above. Results With MVD set as the standard, the accuracies of multimodal image fusion 3D reconstruction images in determining the offending vessels, direction of compression, compression site and the degree of compression were 92.0% (46/50), 92.0% (46/50), 96.0% (48/50) and 58.0% (29/50), respectively. Multimodal image fusion 3D reconstruction images and MVD showed high consistency in judging offending vessels, compression direction and compression position (Kappa values: 0.729, 0.903 and 0.955 respectively, all P<0.001). However, the consistency was poor in judging the degree of compression of offending vessels to the trigeminal nerve (Kappa value=0.227, P=0.002). The degree of compression was higher in intraoperative findings of MVD than that revealed by multimodal image fusion three-dimensional reconstruction (mean values: 2.57 and 1.58 respectively, Z=-4.499, P<0.001). Conclusions Preoperative multi-modal image fusion 3D reconstruction could help accurately determine the offending vessel, compression direction and compression position of PTN, which seems highly consistent with intraoperative findings of MVD. Preliminary speculation could be used as one of the methods facilitating preoperative diagnosis. Key words: Trigeminal neuralgia; Multimodal image fusion; Microvascular decompression; Neurovascular relationship; Computer-aided diagnosis

Resident Perspectives

Objective To analyze the MRI characteristics of vestibulocochlea neurovascular compression in patients with vestibular paroxysmia (VP) and to investigate the effect of the compression, its site and degree, on the occurrence of VP. Methods Twenty-eight cases of VP (VP group) and 28 cases of vertiginous patients other than VP (control group) were retrospectively reviewed.Three dimensional magnetic resonance angiography (3D-MRA) was performed and the data were used for neurovascular cross-compression (NVCC) analysis.The frequency and type of NVCC, the origin of the offending vessel and the distance between compression site and brainstem were compared between the two groups. Results The frequency of NVCC was 96.4%（27/28） in VP group, with a significant difference compared with control group (13/28，46.4%；χ2=17.15，P<0.01).The most common NVCC type was vascular loop compression at vestibulocochlear nerve(15/35, 42.9%).Anterior inferior cerebellar artery was the most common offending vessel (25/35, 71.4%) in VP group.There were no significant differences between the two groups in the type of NVCC or the origin of the offending vessel.The frequency on the distortion and (or) displacement of vestibulocochlear nerve which was severely compressed by vessel in VP group (7/56, 12.5%) was significantly higher than that in control group (0; P=0.013).The distance between compression site and brainstem was (8.57±5.08) mm in VP group, and (8.93±4.64) mm in control group, showing no significant difference. The ratio that the distance was less than 15 mm between compression site and brainstem in unilateral NVCC of VP group (100%) was significantly higher than unilateral NVCC of control group (7/10, P=0.033). Conclusions The VP patients have higher NVCC incidence and the most common NVCC type is vascular loop compression at vestibulocochlear nerve which is mainly caused by anterior inferior cerebellar artery.NVCC in VP patients mostly occurs in the central myelin portion of vestibulocochlear nerve.The site and degree of neurovascular compression may relate to the occurrence of VP. Key words: Vertigo; Vestibular diseases; Vestibulocochlear nerve; Nerve compression syndromes; Vascular diseases; Magnetic resonance imaging

Background:Iliac vein compression syndrome (IVCS) is an important cause of deep vein thrombosis, but the incidence of IVCS is still unclear. The purpose of this prospective study was to determine the incidence of IVCS in an asymptomatic patient population and to evaluate the risk factors in patients with and without IVCS.Methods:From October 2011 to November 2012, a total of 500 patients (228 women and 272 men; mean age of 55.4 ± 14.7 years) with no vascular-related symptoms were enrolled in this study. Computed tomography was performed to evaluate all patients. The degree of venous compression was calculated as the diameter of the common iliac vein at the site of maximal compression divided by the mean diameter of the uncompressed proximal and caudal left common iliac vein (LCIV). We compared the stenosis rate of the common iliac vein in women and men according to age and followed up patients to evaluate outcomes.Results:The mean compression degree of the LCIV was 16% (4%, 36%); 37.8% of patients had a compression degree ≥25% and 9.8% had a compression degree ≥50%. There was a significant difference between men and women in the LCIV compression degree (9% [3%, 30%] vs. 24% [8%, 42%]; U = 4.66, P < 0.01). In addition, the LCIV compression degree among younger women (≤40 years) was significantly different compared with that in older women (>40 years) (42% [31%, 50%] vs. 19% [5%, 39%]; U = 5.14, P < 0.001). Follow-up was completed in 367 patients with a mean follow-up of 39.5 months (range, 6–56 months). The incidence of IVCS in the follow-up period was 1.6%. Stenosis rate and the diameter of the site of maximal compression correlated with the incidence of IVCS. Multivariable Cox regression analysis showed that the stenosis rate was an independent risk factor of IVCS (Wald χ2 = 8.84, hazard ratio = 1.13, P < 0.001).Conclusions:The incidence of IVCS was low and correlated with the stenosis rate of iliac vein. Preventative therapy may be warranted for common iliac vein compression in patients at an increased risk of venous thromboembolism, especially patients with a higher iliac vein compression degree.

A 22-year-old male presented to the outpatient department (OPD) with the complaint of photophobia. His best-corrected visual acuity (BCVA) was 20/20 in the right eye (oculus dextrus) and 20/40 in the left eye (oculus sinister). On ocular examination, OD was normal and OS revealed posterior embryotoxon with mild corectopia [Fig. 1a]. Ultrasound biomicroscopy [Fig. 2a], gonioscopy [Fig. 2b], and anterior segment optical coherence tomography (AS-OCT) [Fig. 1b] revealed thick bands of iris tissue adherent to the posterior embryotoxon. His intraocular pressures (IOPs) were 18 mmHg OD and 25 mmHg OS. Fundus examination [Fig. 3], B-scan [Fig. 4a and b], and optical coherence tomography (OCT) [Fig. 4c and d] of optic nerve head revealed optic disc coloboma, with visual fields showing the corresponding enlargement of blind spot [Fig. 5a]. Specular microscopy revealed polymegathism and decreased cell density in OS [Fig. 5b]. Craniofacial dysmorphism, dental anomalies, excess umbilical skin, and cardiac abnormalities were ruled out.Figure 1: (a) Slit-lamp image showing posterior embryotoxon, (i.e.)thickened prominent anteriorly displaced Schwalbe’s line (red arrow) extending from 3 o’clock to 7 o’clock position and corectopia in the left eye (OS). (b) Anterior segment optical coherence tomography (AS-OCT) revealing the iris strands adherent (red arrow) to posterior embryotoxon in OSFigure 2: (a and b) Ultrasound biomicroscopy image and gonioscopic image revealing iris strands adherent (red arrows) with the posterior embryotoxon in OSFigure 3: Fundus photograph showing (a) normal study in OD and (b) optic nerve head coloboma with peripapillary atrophy in OS. Same fundus in zoomed view showing (c) the normal optic disc in OD and (d) colobomatous optic disc with peripapillary atrophy in OSFigure 4: (a) B-scan examination of OS showing a mild posterior excavation of the optic nerve head (red arrow) suggestive of an optic disc coloboma. (b) Zoomed image of the same. (c and d) Optical coherence tomography (OCT) optic nerve head of OS showing poorly differentiated retinal tissue with multiple schitic cavities (red asterisks) suggesting an optic nerve head coloboma and herniated retina adjacent to the colobomatous areaFigure 5: (a) Perimetry report showing functional enlargement of blind spot corresponding to the structural optic nerve head coloboma in OS. (b) Specular microscopy showing normal endothelial cell morphology and cell density (2933 cells/mm2) in OD and decreased cell density (2571 cells/mm2) (red circle) and increased polymegathism in OSDiscussion Neural crest-derived mesenchymal cells, neuroectoderm of the optic cup, and surface ectoderm, all contribute to development of the tissues of anterior segment. Axenfeld–Rieger anomaly (ARA) is an iridocorneal anomaly which is congenital, bilateral, and may include ocular features such as limbal dermoid, megalocornea, microcornea, cataracts, chorioretinal colobomas, macular degeneration, and optic nerve hypoplasia.[123] But in this case, ARA was unilateral and associated with optic disc coloboma. Increased IOP is a common association of ARA, and was seen in this case, which was managed with anti-glaucoma medications. Though the angles were predominantly open, glaucoma occurs in approximately 50% of patients during childhood or adulthood due to incomplete development of the trabecular meshwork during gestation.[456] Testing for PITX2 and FOXC1 genes was carried out and mutation in FOXC1 was documented. Though rare, this manuscript reports a unilateral presentation of ARA associated with glaucoma, optic disc coloboma, and mutation in FOXC1 gene, which, according to our knowledge has never been reported in the literature before. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Morphology of the injured posterior wall causing spinal canal encroachment in osteoporotic vertebral fractures

Latest advancements in intracoronary imaging have enabled the insertion of miniaturized catheters with imaging probes in coronary arteries in order to provide detailed imaging information in a cross-sectional image format after an automated pullback. Cross-sectional images can then be also used for longitudinal reconstructions for the vessel segment imaged. There are two main broadly available intracoronary imaging modalities, namely intravascular ultrasound (IVUS) and optical coherence tomography (OCT), which provide information on (1) the lumen and wall morphology as well as the anatomic and tissue characteristics of atherosclerotic plaques, and (2) endovascular implants 1, 2. The main imaging features that are visualized during IVUS or OCT imaging in everyday clinical practice in the catheterization laboratory will be presented using intravascular images from routine cases. Intravascular ultrasound imaging enables the visualization of both the lumen and the arterial wall. The lumen is not void of echo signal due to blood speckling. In coronary arteries, three layers of the arterial wall are frequently visible moving outward: the intima, media (less echogenic), and adventitia (Figure 1A). Due to echogenic properties of these layers, the lumen and media–adventitia (corresponding to the external elastic membrane [EEM]) borders can be readily identified and can be used for quantitative measurements of the lumen area, atheroma/plaque area (i.e., area between the lumen border and the media–adventitia border), and consequently, the plaque burden (plaque area divided by EEM area). It should be noted that because the internal elastic membrane cannot be well delineated in IVUS images, IVUS measurements cannot determine true histological atheroma area (i.e., the area bounded by the internal elastic membrane), and thus the area bounded on the outer side by the EEM and the inner side by the lumen border (i.e., intima plus media) is used as a surrogate of the atheroma area. Online measurements (Figure 1B) on cross-sectional images can be easily performed during IVUS interrogation at different locations along the length of the artery which can be easily identified using the longitudinal view of the IVUS pullback (Figure 1B, bottom). During IVUS imaging, most branches (Br) can be easily detected (Figure 2). The guidewire causing a characteristic artifact is denoted with an asterisk. IVUS provides deep penetration into the arterial wall, and thus branches may also appear within the arterial wall as they approach the main vessel (Figure 2C, 8 o’ clock). High lipid content results in low echogenicity, whereas calcific plaques are highly echogenic. Fibrous plaques have an intermediate echogenicity between echolucent (i.e., “soft”) atheromas and calcified regions. Atherosclerotic regions usually contain more than one plaque subtype; these mixed plaques are described as fibrofatty/fibrolipidic and fibrocalcific plaques. Figure 3A portrays a primarily fibrous plaque spanning from 7 to 1 o'clock. A fibrolipidic plaque is shown in Figure 3B with an echolucent area (arrow) probably corresponding to a lipid pool and a fibrous cap inward. Figure 3C demonstrates a fibrocalcific plaque with calcified regions at 3 and 8–9 o'clock which obstruct the penetration of ultrasound and cause “acoustic shadowing.” Extensive calcification is easily identified in IVUS images and can be quantified by measuring the arc of calcium (in degrees); a cross-sectional image with a ~230° arc of calcium is shown in Figure 3D. Metallic stent struts (Figure 4A, asterisks) appear as small echogenic arcs along the circumference of the vessel (due to strong reflection of ultrasound). Intimal hyperplasia is usually visualized as tissue of intermediate echogenicity within the area bounded by the stent struts (Figure 4A, arrow). Figure 4B portrays an area with stent malapposition as there is a distance between some stent struts (asterisks) and the wall, and thus, there is blood flow between those struts and the underlying wall. Optical coherence tomography provides images of high resolution (10–15 microns) enabling the detailed morphology of the lumen and lesions (Figure 5); a highly irregular lumen cross-section due to heavy atherosclerotic disease in the arterial wall is visible in this cross-sectional image. During OCT imaging, branches (Br) of any size and variable take-off angle are easily detected (Figure 6). The guidewire causing a characteristic shadow is denoted with an asterisk. Fibrous plaques have high backscattering and a relatively homogeneous signal (Figure 7, white arrows). Calcified regions have poor signal and are rather heterogeneous with sharply delineated border (Figure 7, red arrows). Lesions with lipid pools (i.e., necrotic core) appear as signal-poor regions with poorly defined or diffuse borders (Figure 8, asterisks). The high resolution of OCT enables the measurement of fibrous cap thickness (arrows) over the necrotic core, and thus is suitable for identifying thin-cap fibroatheromas, which are considered as the primary precursor for acute coronary events. OCT images show thrombotic material inside a stent (Figure 9, arrows denote thrombus). An intimal flap (red arrow) is portrayed within 5 mm proximal to a stent as shown in the longitudinal view of the OCT images (Figure 10, top). The OCT consecutive cross-sectional images (distal to proximal) show frame-by-frame the intimal flap spanning a length of more than 6 mm (Figure 10, bottom, white arrows denote the distal edge of the dissection). In-stent restenosis demonstrating a homogeneous, high-backscattering neointima is shown in Figure 11A; stent struts with their shadow are visible both in the cross-sectional and longitudinal OCT images. In Figure 11B, in-stent restenosis with a focal calcified region (arrow) beneath the neointima is shown. Stent malapposition becomes evident when stent struts (asterisks) are distant from the luminal surface of the arterial wall (Figure 12). Dr. Papafaklis has nothing to disclose.

67 - Optical Coherence Tomography

A prospective radiographical trial. To elucidate effects of loading associated with spinal canal encroachment (SCE) in patients with insufficient bone union after vertebral fractures in the elderly, using computed tomography-myelography in 2 different positions. In elderly patients with vertebral fractures, influence of loading would be involved in SCE, but the details are not well understood. Seventeen patients (mean age, 77.4 ± 8 yr; range, 62-91 yr) with various degrees of neurological deficit due to insufficient bone union at both vertebral body and posterior vertebral wall were included in this study. Computed tomography-myelography was performed in both semisitting and supine positions. Kyphotic angle, rate of dural compression, ratio of occupation by bony fragments, and posterior vertebral body height ratio were measured and compared between positions. Mean ratio of occupation by bony fragments was significantly higher in the semisitting position (47.9 ± 9.2%) than in the supine position (33.9 ± 10.0%, P, 0.001). Similarly, mean posterior vertebral body height ratio was significantly lower in the semisitting position (67.8 ± 10.8%) than in the supine position (76.3 ± 13.3%), indicating a significant loss of vertebral height in the semisitting position (P, 0.001). Mean rate of dural compression was likewise significantly higher in the semisitting position (48.6 ± 13.3%) than in the supine position (33.3 ± 16.5%; P, 0.001). Mean change in ratio of occupation by bony fragments, change in posterior vertebral body height ratio, and angular instability between positions were 13.9 ± 8.6%, 8.5 ± 6.7%, and 13° ± 5.7°, respectively. A significant correlation was identified between change in ratio of occupation by bony fragments and change in posterior vertebral body height ratio (P = 0.001). Our study demonstrated that collapse of the nonunited posterior vertebral wall and intracanal protrusion of vertebral fragments would occur simultaneously with axial loading, causing SCE. Computed tomographic scan obtained in semisitting position seems quite useful to evaluate the amount of SCE by an unstable posterior wall.