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To provide a major review on the applications of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in evaluating orbital lesions. This review also outlines selected scenarios where DCE-MRI may be helpful. A comprehensive retrospective literature review of all English language publications on PubMed, EMBASE, and Google Scholar between 1994 and 2022. This literature review examined the specific applications and clinical scenarios surrounding the utility of DCE-MRI in orbital lesions and various findings that have been presented in the current literature. DCE-MRI provides information on tissue physiology and permeability, beyond the anatomical features displayed on static imaging. Various measured parameters (qualitative, semi-quantitative, and quantitative) obtained by DCE-MRI have been used to differentiate between benign and malignant lesions, specific orbital lymphoproliferative diseases (OLPD), lacrimal gland lesions, and various rare orbital tumours. DCE-MRI has a limited role as an initial diagnostic imaging modality. However, DCE-MRI may prove to have benefit in predicting and monitoring treatment response in orbital lymphoma as a critical imaging study, but literature specific to orbital malignancies remains limited. The value of DCE-MRI may be in situations of diagnostic uncertainty, where it may be an additional imaging aid following conventional imaging techniques. It may also act as a critical imaging modality for monitoring of orbital tumour treatment response, but the literature remains limited. Standardisation of imaging protocol, measured parameters, and statistical analysis remain limitations of this imaging technique. [ABSTRACT FROM AUTHOR]

Purpose: Bacterial orbital cellulitis (OC) and diffuse non-specific orbital inflammation (DNSOI) may be challenging to differentiate clinically. This study investigates the utility of systemic inflammatory markers, namely white cell count (WCC) and C-reactive protein (CRP), in differentiating between OC and DNSOI. Methods: A single-centre retrospective study of patients diagnosed with OC or DNSOI, between 2003 to 2021, who had WCC and/or CRP obtained at presentation. The mean levels of these factors and the proportion of positivity were compared between OC and DNSOI. A receiver operating characteristic (ROC) analysis was conducted to calculate the specificity and sensitivity of WCC or CRP in each group. Results: 49 patients were included in this study. The mean age was 56 ± 20 years, and 21 patients were females. 26 (53.1%) patients had OC, and 23 (46.9%) patients had DNSOI. Mean WCC for OC and DNSOI were 14.5 × 103/µL and 9.27 × 103/µL, respectively (P = 0.001). Mean CRP for OC and DNSOI were 104.4 mg/L and 10.0 mg/L, respectively (P < 0.001). The optimal CRP cut-off value of 20.2 mg/L demonstrated 90.9% sensitivity and 90.5% specificity (AUC = 0.946, P < 0.001) for differentiating between OC and DNSOI. CRP was more predictive of OC than WCC (P = 0.017). 7/26 (26.9%) OC patients with fever also had an elevated CRP, while 1/23 (4.3%) of DNSOI with fever had a normal CRP. Conclusions: An elevated WCC is suggestive of OC. However, a normal WCC can neither exclude nor differentiate between OC and DNSOI. CRP may be a more accurate predictor of OC compared to WCC. [ABSTRACT FROM AUTHOR]

To report the normative dimensions of the lacrimal gland on fat-suppressed contrast-enhanced magnetic resonance imaging (MRI) in an Australian cohort. Retrospective review of patients who underwent 3 T orbital MRI is presented. Two hundred eleven orbits were used to conduct lacrimal gland measurements. Orbits were excluded if there was ipsilateral orbital or lacrimal gland disease, prior surgery, or poor image quality. The length and width of the lacrimal gland were measured in axial and coronal sections using the largest image. The mean lacrimal gland axial length was 14.6 mm in the right orbit and 14.3 mm in the left orbit. The mean axial width was 4.9 mm in both orbits. Coronal lengths averaged 16.2 mm in the right orbit and 16.4 mm in the left orbit. The coronal width averaged 4.8 mm in both orbits. A significant negative correlation was found between age and the right axial length (r = −0.26, p <.01) and the left axial length (r = −0.26, p <.01) of the lacrimal gland. No statistically significant difference was found between genders or laterality. This study presents the normal lacrimal gland dimensions on fat-suppressed contrast-enhanced MRI in an Australian cohort. An inverse relationship exists between age and the axial length of the lacrimal gland. These data may be used to help diagnose enlargement of the lacrimal gland. [ABSTRACT FROM AUTHOR]

Optic nerve infiltration secondary to systemic non-Hodgkin lymphoma (NHL) is a rare phenomenon. We present a 55-year-old man with low-grade systemic NHL who initially presented with an isolated optic neuropathy and non-specific neurological symptoms. We further present a literature review of systemic NHL with radiological evidence of optic nerve infiltration. On magnetic resonance imaging, the characteristic features include optic nerve enhancement and enlargement, while leptomeningeal enhancement is uncommon. Cerebrospinal fluid analysis and optic nerve sheath biopsy can return false negative results, and when such investigations are inconclusive, biopsy of the optic nerve substance has a high diagnostic yield. Although rare, lymphomatous optic nerve infiltration must be considered in the differential diagnosis of a pale swollen optic disc. [ABSTRACT FROM AUTHOR]

To determine the normal diameters of the extraocular muscles (EOMs) and optic nerve sheath complex (ONSD) and correlate with patient demographics in an Australian cohort. Consecutive patients who underwent contrast enhanced computed tomography (CT) orbits between December 2017 and March 2021 were included. Patients with bilateral disease, previous orbital surgery, or poor scan quality were excluded. Normal orbit was used in patients with unilateral orbital disease. Two hundred one orbits from 201 patients were included. Normal measurements (mean ± SD) were as follows: medial rectus (MR) 4.22 ± 0.56 mm; inferior rectus (IR) 4.20 ± 0.70 mm; lateral rectus (LR) 3.40 ± 0.56 mm; superior muscle group (SMG) 4.13 ± 0.72 mm; superior oblique (SO) 2.60 ± 0.43 mm; inferior oblique (IO) on quasi-sagittal plane 2.19 ± 0.42 mm, and the ONSD 5.62 ± 0.82 mm. The mean diameters of the LR, SMG, IR, SO, and ONSD were significantly larger in male than female patients (p <.05). Statistically significant correlation was found between age and the diameters of the LR (r = 0.29, p <.01), SMG (r = 0.22, p <.01), IO on a coronal plane (r = −0.18, p <.01), and ONSD (r = 0.16, p =.02). This normative data may be used to diagnose pathological enlargement of the optic nerve and extraocular muscles, including involvement of the oblique muscles. [ABSTRACT FROM AUTHOR]

To characterise the radiological features of orbital lymphoma subtypes This was a multicentre, retrospective study to analyse radiological and clinical characteristics of orbital lymphoma by histological subtype across two sites within Australia and the United States. A total of eighty-eight patients were included. The most common subtypes were extranodal marginal zone lymphoma [EMZL] (48, 54.5%), follicular lymphoma [FL] (16, 18.2%), and diffuse large B-cell lymphoma [DLBCL] (15, 17.0%). Clinically, significant associations were found between DLBCL and vision change (p <.01), pain (p <.01), extraocular movement limitation (p =.01), and optic neuropathy (p =.01). Radiologically, there was no significant difference between the individual histopathological sub-groups with respect to bone destruction (p =.30), optic nerve involvement (p =.30) and diffuse appearance (p =.84). However, if categorised as either aggressive or indolent, aggressive lymphoma subtypes were significantly more likely to demonstrate globe indentation radiologically than indolent subtypes (Odds Ratio = 5.5, 95% CI: 1.3, 23.3; p =.02). DLBCL was significantly associated with vision change, pain, extraocular movement limitation and optic neuropathy clinically. Aggressive lymphoma subtypes were significantly more likely to demonstrate globe indentation radiologically. Otherwise, there were no significant differences between lymphoma subtypes and radiological findings on MRI and CT. [ABSTRACT FROM AUTHOR]