Objective To investigate the relationship between asymmetric prominent hypointense vessels (prominent vessel sign, PVS) on susceptibility-weighted imaging (SWI) and leptomeningeal collateralization in patients with acute ischemic stroke due to large vessel occlusion. Methods We retrospectively enrolled patients with M1 segment occlusion of the middle cerebral artery who underwent emergency magnetic resonance imaging and digital subtraction angiography within 24 hours from stroke onset. The extent of PVS on SWI was assessed using the Alberta Stroke Program Early CT Score (ASPECTS). Leptomeningeal collateralization on digital subtraction angiography images was assessed using the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology (ASITN/SIR) scale. Spearman’s rank correlation test was performed to explore the correlation of ASITN/SIR scores with SWI-ASPECTS and SWI-diffusion-weighted imaging (DWI) mismatch scores. Results Thirty-five patients were enrolled. There was no significant correlation between SWI-ASPECTS and ASITN/SIR scores. However, SWI-DWI mismatch scores were positively correlated with ASITN/SIR scores. Conclusion The range of PVS on SWI did not closely reflect the collateral status, while the range of SWI-DWI mismatch was significantly correlated with the leptomeningeal collateralization. In patients with acute anterior circulation stroke due to large vessel occlusion, larger SWI-DWI mismatch was associated with better leptomeningeal collaterals.
Background and Purpose— To investigate the effect of chronic hyperglycemia on cerebral microvascular remodeling using perfusion computed tomography. Methods— We retrospectively identified 26 patients from our registry of 2453 patients who underwent a perfusion computed tomographic study and had their hemoglobin A 1c (HbA 1c ) measured. These 26 patients were divided into 2 groups: those with HbA 1c >6.5% (n=15) and those with HbA 1c ≤6.5% (n=11). Perfusion computed tomographic studies were processed using a delay-corrected, deconvolution-based software. Perfusion computed tomographic values were compared between the 2 patient groups, including mean transit time, which relates to the cerebral capillary architecture and length. Results— Mean transit time values in the nonischemic cerebral hemisphere were significantly longer in the patients with HbA 1c >6.5% ( P =0.033), especially in the white matter ( P =0.005). Significant correlation ( R =0.469; P =0.016) between mean transit time and HbA 1c level was observed. Conclusions— Our results from a small sample suggest that chronic hyperglycemia may be associated with cerebral microvascular remodeling in humans. Additional prospective studies with larger sample size are required to confirm this observation.
We report two patients with unilateral vertical retraction syndrome. Magnetic resonance imaging (MRI) of the orbits of the two cases showed similar size and location of the orbital structure, but with dramatically different strabismus type. MRI sagittal reconstruction of the orbits suggested that abnormal muscle tissue arised from the inferior rectus, which might be associated with retraction and narrowing of the palpebral fissure and atypical strabismus as well.
Objective To investigate the MRI anatomy of the optic chiasm and its adjacent structures in normal adults.Methods The study included 65 adults, 31 males and 34 females, 18 to 72 years, and averaging 42.3 years.All 65 patients were studied using T_1WI at axial, coronal, and sagittal sections and T_2WI at sagittal sections, 20 adults were also scanned with T_2WI at axial section, and 20 at coronal sections.The transverse diameter, the height, the anteroposterior diameter, chiasm-tuberculum distance, the angle between the optic chiasm and anteroposterior diameter of foramen magnum, and the angle between bilateral intracranial optic nerves were measured, respectively.The shape in the sections and its anatomic relationship were also investigated.Results (1) In axial sections, the transverse diameter was (13.0±1.7) mm and (13.5±1.7) mm in coronal sections.The height was (3.1±0.55) mm.The anteroposterior diameter was (8.6±0.93) mm.The chiasm-tuberculum distance was (3.1±1.7) mm.The angle between the optic chiasm and the anteroposterior diameter of the foramen magnum was (38.3±8.4)°.The angle between bilateral intracranial optic nerves was (65.6±8.5)°.All the results divided by sex did not yield any significant differences.(2) The adjacent structures: The third ventricle located superiorly, the internal carotid arteries were on each side, the anterior cerebral arteries passed anterosuperiorly, the gyrus rectus of frontal gyrus was in the front, the pituitary stalk, the tuber cinereum, and mammillary bodies located posteriorly, and the pituitary gland and sphenoidal sinus located inferiorly.Conclusion The shape and its anatomic relationship of the optic chiasm can be well shown on MR images, the size can be measured accurately with MRI.
Lymphoma is the most common primary orbital malignant neoplasm in adults, accounting for 8–15% of extranodal non-Hodgkin's lymphomas and 2% of all lymphomas.[1] Most of these tumors involve the conjunctiva, orbit, lacrimal gland, or eyelid. It is uncommon for lymphoma to originate from the extraocular muscles. The prevalence of intramuscular lymphoma is between 0.1% and 8.7% of all extranodal lymphomas. Fewer than 60 cases have been reported in the last 30 years,[2] mostly as case reports with scant or no radiology information.[2] The study was approved by the Institutional Review Board of Beijing Tongren Hospital. We reviewed 98 cases involving patients who underwent surgical or needle aspiration biopsy treated in Beijing Tongren Hospital between September 2007 and April 2014. The inclusion criteria were as follows: (1) patients who were treatment naïve before hospitalization; (2) patients who underwent magnetic resonance imaging (MRI) examination before treatment; and (3) patients with lesions originating from the extraocular muscles. Five patients were finally enrolled in the study. They had all undergone orbital MRI, dynamic contrast-enhanced (DCE) imaging, and additional delayed (contrast-enhanced) acquisitions. Their MRI and pathology were primarily analyzed. For DCE data analysis, based on parameters, such as time, maximal enhancement intensity (SImax), and final enhancement intensity (SIfinal),[3] the time-intensity curve (TIC) was assigned into three patterns: Type I, a persistent pattern with a continuous curved line in the entire dynamic period; Type II, a plateau pattern with a prominent increase in slope with SIfinal = 90–100% of SImax; and Type III, a washout pattern with a rapid increase in slope with the SIfinal <90% of SImax. Five patients were male with a median age of 50.6 ± 11.8 years (range, 33–64 years). Four cases were unilateral (three on the left side and one on the right side) and one case was bilateral. The disease affected six muscles in five patients, including the inferior oblique muscle in two patients, and the levator palpebrae superioris muscle and the superior ocular muscle group in one patient each. In addition, both superior ocular muscle group and inferior rectus were affected in one patient. All tumors presented enlargements in the tendons and belly of the muscle and had well-defined margins. Four enlarged muscles were fusiform, and two were irregularly shaped [Figure 1a–1c]. All cases displayed homogeneous isointensity to gray matter on T1-weighted image (WI) and T2-WI. After injection of the gadopentetate dimeglumine, mildly and moderately homogeneous enhancement appeared in one and four cases, respectively [Figure 1d]. In the DCE-MRI phase, three patients had Type III TIC patterns and two had Type II [Figure 1e]. The optic nerve sheaths, posterior fascia, orbital nerve canal, and contralateral intraconal compartment were involved in one patient. In another patient, the homolateral orbital apex and posterior sheaths of the optic nerve were involved. The orbit was displaced superiorly, inferiorly, or anteriorly in three of the patients. All patients were pathologically identified as having mucosa associated lymphoid tissue lymphoma [Figure 1f–1h].Figure 1: Magnetic resonance imaging features and pathology results. (a and b) Axial T1-WI and T2-WI showing the enlargement of the left inferior oblique muscle with homogeneous isointensity. (c)Coronal T1-WI revealing that both the right (arrow) and the left inferior oblique muscles are enlarged. (d and e) After injection of contrast, the lesions undergo slight isointense homogeneous enhancement (arrow on d) and were Type II in DCE-MRI. (f) Hematoxylin and eosin stained section showing some hyperplasia in the lymphoid tissue with consistent form (original magnification, ×400), there are hundreds of uniform hyperplasia cells with mild atypia and monocyte B-cell differentiation. (g and h) The immunohistochemistry indicates that the tissue is positive for both CD20 and CD79, respectively (original magnification, ×400). WI: Weighted image; DCE-MRI: Dynamic contrast-enhanced magnetic resonance imaging.In previously reported cases, the origin of extraocular muscle lymphoma has varied. Fukuhara et al.[4] and Surov et al.[5] described one and three intramuscular lymphomas, respectively; they were located in the rectus (one in the superior rectus muscle, two in the lateral rectus muscle, and one in the medial rectus muscle). After reviewing local data and the previous literature, Watkins et al.[2] also concluded that the lesions were more frequently involved with the rectus muscles (73%) than the oblique or the levator palpebrae superioris muscle (11%). Moreover, the majority of cases consisted of single muscle involvement.[2] Orbital lymphoma tumors have been reported to be most frequently located in the superior rectus, followed by the inferior rectus, lateral rectus, and medial rectus. However, in our study, lesions were found in the inferior oblique muscle (2/5 patients), levator palpebrae superioris muscle (1/5 patient), superior ocular muscle group (1/5 patient), and superior ocular muscle group and inferior rectus (1/5 patients). These differences may be the result of statistical errors caused by the small patient population. The extraocular muscle lymphomas involved thickening of both muscle tendon and belly. The majority of muscle enlargements was fusiform on axial MRI, similar to the results of previous case studies.[2] In addition, the lesions tended to be unilateral with no side bias. Only 9% of the reported cases have involved both eyes.[2] MRI features of extraocular muscle lymphomas were nonspecific, with most of them having homogeneous isointensity on T1-WI and T2-WI, making it difficult to differentiate them from other lesions. In this situation, DCE may provide helpful information. Yuan et al.[3] found that orbital lymphomas usually presented as Type II or Type III in DCE-MRI, corresponding to higher cell density in the lymphoma. In the present study, two and three cases of extraocular muscle lymphoma presented as Type II and Type III, respectively. In conclusion, extraocular muscle lymphoma frequently presents as a painless swelling, often with a single muscle affected. On MRI, the lesions demonstrate isointensity on T1-WI and T2-WI with Type II or Type III enhancement on TIC. Financial support and sponsorship The study was supported by grants from the Beijing Training Project for the Leading Talents in S & T (No. Z141107001514002), and the Beijing Scholar 2015, and Beijing Municipal Administration of Hospitals’ Mission Plan (No. SML 20150101), and the Beijing Natural Science Foundation (No.7112030). Conflicts of interest There are no conflicts of interest.
Brown syndrome is characterized by limitation of elevation in adduction, with complex mechanisms involving muscle, tendon, and trochlea. Here, we investigated mechanisms of Brown syndrome by magnetic resonance (MR) imaging.It was a retrospective case series study. Fourteen patients with unilateral Brown syndrome between 3 and 54 years of age (10 cases of congenital and 4 cases with acquired disease) were included in the study. All patients underwent complete ophthalmic and orthoptic evaluation. Imaging of the ocular motor nerves at the brainstem was performed on 3D-FIESTA sequence, the orbits were imaged with FSE T1, T2WI using surface coils.Nine of 10 with congenital Brown syndrome demonstrated hypoplasia of the superior oblique (SO) of the affected side. Abnormal low signal intensity in the trochlea area was found in one patient. Three of 4 acquired patients had a history of trauma and were demonstrated fracture of the trochlea, extensive scarring, and superior orbital fracture. One acquired case was demonstrated scarring of anterior part of the SO and hypoplasia of the posterior part.Brown syndrome consists of a series of diseases. Their clinical features are quite similar while their anatomical mechanism varies in numerous ways. Therefore, based on patient's individual pathophysiology, the management in Brown syndrome should be personalized.
Purpose: To study the neuroanatomic characteristics of patients with Duane's retraction syndrome with high-resolution magnetic resonance imaging. Methods: The study included 11 consecutive cases, including five patients with type I, one patient with type II, four patients with type III, and one patient with inverse Duane's retraction syndrome. The patients underwent magnetic resonance imaging of the brain, brain stem, cavernous sinus, and orbits. Results: In 10 patients, the abducens nerve (cranial nerve VI) was absent or showed hypoplasia in the brain stem, cavernous sinus, and orbit. However, these findings were not seen in the patient who had inverse Duane's retraction syndrome. In two children, magnetic resonance imaging showed that the cavernous sinuses were smaller on the affected side. The inferior division of the oculomotor nerve (cranial nerve III) was traced to enter the lateral rectus muscle or had intimate continuity with the lateral rectus muscle in nine patients with type I and type III Duane's retraction syndrome. In one patient with type III Duane's retraction syndrome, the oculomotor foramen was significantly larger on the affected side than on the sound side. In the patient with type II Duane's retraction syndrome, the superior division of cranial nerve III was enlarged and had three branches. In the patient with inverse Duane's retraction syndrome, the inferior division of cranial nerve III sent two branches to the medial rectus muscle, and the patient had superior oblique muscle hypoplasia. Conclusion: Neuroimaging findings showed that the absence of cranial nerve VI, hypoplasia in the brain stem, and an extra branch of the inferior division of cranial nerve III to the lateral rectus muscle is the most common presentation of Duane's retraction syndrome, but not the only one. The aberrant branches likely correspond to the abnormal eye movement seen in patients with this disorder. [J Pediatr Ophthalmol Strabismus 2009;46:278–285.]
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