Radiologic Features of Well-circumscribed Orbital Tumors With Histopathologic Correlation: A Multi-center Study.

PURPOSE: To delineate specific imaging characteristics of solitary fibrous tumors, schwannomas, cavernous venous malformations, and well-circumscribed orbital lymphoma. METHODS: Patients undergoing excisional biopsy of solitary fibrous tumor, schwannomas, cavernous venous malformations, or well-circumscribed orbital lymphoma with preoperative MRIs available for review were identified at 3 academic centers in the United States and Australia. An exploratory statistical analysis was performed to identify important radiologic features, which were subsequently included in a random forest model. Histopathologic correlates were evaluated in representative cases. RESULTS: A total of 91 cases were included with a mean age of 52.9 ± 17.2 years. Nearly all solitary fibrous tumors were located in the anterior or mid orbit (87.5%) and they more commonly demonstrated intralesional heterogeneity on T2-weighted imaging (45.5%) ( p < 0.01). Compared with the other tumors, schwannomas tended to be intraconal (66.7%) and were often in the mid or posterior orbit (83.4%) ( p < 0.01). Cavernous venous malformations characteristically demonstrated progressive contrast enhancement (93.9%; p < 0.01). Most lesions in all 4 groups were hypointense on T1-weighted imaging (80%-100%; p = 0.14) and only well-circumscribed orbital lymphoma tended to also be hypointense on T2 (81.8%) ( p < 0.01). Finally, cases of lymphoma had significantly lower apparent diffusion coefficient ratios (0.9 ± 0.2) ( p < 0.001), while the other 3 groups were not significantly different from one another (cavernous venous malformations: 1.8 ± 0.4; schwannomas: 1.8 ± 0.5; and solitary fibrous tumor: 1.6 ± 0.6) ( p = 0.739). CONCLUSIONS: Key features that aid in the differentiation of these 4 tumors from one another include T2 intensity and homogeneity, early contrast-enhancement pattern, and ADC ratio.

Orbital Artifacts on MRI.

PURPOSE: To describe artifacts on orbital MRI, which led to an incorrect radiology report. METHODS: Retrospective chart review of patients identified from the orbital databases at the Royal Adelaide Hospital and University of Wisconsin Hospital. Patients who had artifacts on orbital MRI that led to an incorrect radiology report were included. Records were evaluated for age at imaging, gender, MRI sequence, laterality, and location of artifact, radiological characteristics and misdiagnosis, and cause of artifact. RESULTS: Data were collected from 7 patients (3 male) who had a median age of 61 years at the time of imaging. Five artifacts resulted from fat-suppression failure with 4 of these cases misdiagnosed as inflammatory changes and 1 misdiagnosed as neoplastic infiltration. The OD was involved in 4 cases. Six cases were in the inferior orbit region. CONCLUSIONS: Fat-suppression failure artifacts may arise in the inferior orbit region and can be mistaken for inflammatory or neoplastic orbital disease. This may prompt additional investigations such as orbital biopsy. Clinicians should be aware of artifacts which can affect orbital MRI and lead to potential misdiagnosis.

Histopathological Characteristics of Lacrimal Gland Prolapse.

PURPOSE: Lacrimal gland prolapse is an acquired clinical condition that can present as an upper eyelid mass. Patients may undergo lacrimal gland biopsy when there is diagnostic uncertainty. We aim to describe the histopathological features of this patient group. METHODS: Retrospective case series involving 11 patients. RESULTS: The mean age at presentation was 52.3 ± 16.2 years (range: 31-77 years) with 8 patients (72.3%) being female. The most common presenting symptom was a palpable mass (9; 81.8%) followed by dermatochalasis (4; 36.4%). Three cases (27.3%) were bilateral. Common imaging findings include lacrimal gland enlargement and visualization of the prolapse. All biopsies demonstrated features of mild chronic inflammation with preserved glandular structures. Ten patients (90.9%) underwent surgical intervention involving lacrimal gland pexy and 1 patient (9.1%) was elected for observation only. One patient required repeat surgery after 4 years due to recurrence of symptoms. At the last follow-up, all patients had stable disease or complete resolution of symptoms. CONCLUSION: We present a case series of patients diagnosed with lacrimal gland prolapse who underwent a biopsy during their workup. All biopsies demonstrated features of mild chronic inflammation (dacryoadenitis). All patients had stable disease or complete resolution of symptoms. This case series suggests that chronic inflammation is a common finding in patients with lacrimal gland prolapse but bears minimal clinical consequence.

Systemic inflammatory markers differentiate between orbital cellulitis and non-specific orbital inflammation.

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.

Normative lacrimal gland dimensions by magnetic resonance imaging in an Australian cohort.

PURPOSE: To report the normative dimensions of the lacrimal gland on fat-suppressed contrast-enhanced magnetic resonance imaging (MRI) in an Australian cohort. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Normative orbital measurements in an Australian cohort on computed tomography.

PURPOSE: 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. METHODS: 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. RESULTS: 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). CONCLUSION: This normative data may be used to diagnose pathological enlargement of the optic nerve and extraocular muscles, including involvement of the oblique muscles.

Optic nerve infiltration in systemic non Hodgkin lymphoma.

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.

Radiological analysis of orbital lymphoma histological subtypes.

PURPOSE: To characterise the radiological features of orbital lymphoma subtypes. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.

Dilated superior ophthalmic vein: systemic associations.

PURPOSE: To review systemic associations of patients with dilated superior ophthalmic veins (SOV) in the absence of orbital, cavernous sinus, or neurological disease. METHODS: Retrospective review of patients who had dilated SOVs with a diameter of ≥ 5.0 mm. Patients with a dilated SOV secondary to orbital, cavernous sinus or neurological disease were excluded. Patient demographics, past medical history, and SOV diameters on initial and follow up scans were collected. The maximum diameter of the SOV was taken perpendicular to the long axis of the SOV. RESULTS: Nine cases were identified. Patients ranged in age from 58 to 89 years and six out of nine were female. The dilated SOV involved both eyes in two cases, left eye in five cases and right eye in two cases. Three patients had dilated SOV likely secondary to raised venous pressures from decompensated right heart failure (n = 1), pericardial effusion (n = 1) and left ventricle dysfunction secondary to a myocardial infarction (n = 1). Five patients had a significant history of previous ischaemic heart or peripheral vascular disease. Two patients had risk factors for venous clotting disease whilst one patient had a history of giant cell arteritis and vertebral artery dissection. CONCLUSION: A dilated SOV may raise concern for life threatening conditions such as a carotid cavernous fistula and may prompt additional investigations. A dilated SOV may be reversible and secondary to raised venous pressures due to cardiac failure. Other cases may be seen in patients with significant cardiovascular risk factors, possibly due to changes in vasculature.

Syringing has limited reliability in differentiating nasolacrimal duct stenosis from functional delay.

PURPOSE: To elucidate the role of syringing in assessing nasolacrimal duct (NLD) stenosis and non-anatomical functional NLD delay. METHODS: Consecutive adult patients with epiphora attending a tertiary lacrimal clinic from June 2011 to March 2021 were reviewed. Cases with evidence of canalicular stenosis or other identifiable causes of epiphora were excluded. Following syringing, patients were investigated with dacryocystography (DCG) and dacryoscintigraphy (DSG). The sensitivity and specificity of syringing were evaluated using the combined findings on DCG and DSG. RESULTS: A total of 289 symptomatic lacrimal systems (197 patients; mean age 65.5 ± 14.9 years, 66% females) were included. More than one-third of cases with both normal DCG and DSG were noted to have some degree of reflux on syringing (specificity = 65.1%, 95% CI 50.2-77.6%). The sensitivities were considerably low for NLD stenosis (i.e., stenosis on DCG and delay on DSG) and for functional NLD delay (i.e., normal DCG and delay on DSG), of which 43.7% (95% CI 32.2-55.9%) and 54.3% (95% CI 45.7-62.7%) had full patency on syringing, respectively (p = 0.17). CONCLUSIONS: Full patency on syringing was unreliable for ruling out NLD stenosis and functional delay. Furthermore, a positive syringing may be associated with functional NLD delay and cannot reliably differentiate it from stenosis.

Extraocular muscle enlargement.

Extraocular muscle enlargement can occur secondary to a range of orbital and systemic diseases. Although the most common cause of extraocular muscle enlargement is thyroid eye disease, a range of other inflammatory, infective, neoplastic, and vascular conditions can alter the size and shape of the extraocular muscles. Imaging with computed tomography and magnetic resonance imaging plays an essential role in the workup of these conditions. This article provides an image-rich review of the wide range of pathology that can cause enlargement of the extraocular muscles.

Diagnostic Utility of Diffusion-Weighted Imaging and Apparent Diffusion Coefficient for Common Orbital Lesions: A Review.

PURPOSE: To review and summarize the existing literature surrounding the clinical use of diffusion-weighted imaging and apparent diffusion coefficient (ADC) as diagnostic tools in differentiating common orbital lesions. METHODS: A systematic literature review on the use of ADC and diffusion-weighted imaging sequences for orbital imaging was performed. Only original research articles that reported ADC values for benign or malignant lesions were included. RESULTS: Malignant orbital tumors have an overall lower mean ADC value than benign masses. Orbital lymphoma is characterized by consistently lower ADC values compared with other malignant orbital masses; a threshold value less than 0.775 × 10 -3 mm 2 /s has been proposed to distinguish orbital lymphoma from other neoplastic and non-neoplastic orbital masses. To differentiate orbital inflammatory disease from lymphoma, an ADC threshold greater than 0.92 × 10 -3 mm 2 /s has been proposed. CONCLUSIONS: Orbital masses encompass a host of benign and malignant etiologies and can present a diagnostic challenge on both clinical and radiological assessment. Recent advanced MRI techniques such as diffusion-weighted imaging and ADC can improve the diagnostic specificity for orbital disease, particularly in differentiating benign from malignant lesions and lymphoma from orbital inflammatory disease.

Clinical and Radiological Features of Intramuscular Orbital Amyloidosis: A Case Series and Literature Review.

PURPOSE: Orbital amyloidosis of the extraocular muscles (EOMs) is a rare condition, and its clinicoradiological features are not well elucidated. This study describes the characteristic clinical signs, MRI features, and potential treatment options. METHODS: Retrospective multicenter case series and literature review of EOM amyloidosis. RESULTS: Five cases were identified for inclusion. Common clinical findings were diplopia, ophthalmoplegia, and proptosis. Systemic amyloidosis was more likely to present with multiple muscle involvement, but no particular pattern was observed with localized disease. On MRI, amyloid deposition was characterized as a heterogeneous intramuscular mass with T2 hypointensity and post contrast enhancement. Management is dependent on the extent of disease and functional impairment; options include surgical debulking and radiation therapy. CONCLUSION: EOM amyloidosis is uncommon. The combination of clinical and radiologic findings described in this study should lead to its clinical suspicion.

Normative measurements of the superior oblique and inferior oblique muscles by magnetic resonance imaging.

PURPOSE: Normative oblique muscle data may help to diagnose pathological enlargement of the oblique muscles. We aim to describe the normative values of the superior and inferior oblique muscles in an Australian cohort on T1-weighted MRI and fat suppressed contrast enhanced T1-weighted MRI. METHODS: A retrospective review of patients who underwent 3 T orbital MRI. The healthy orbits were used to conduct measurements in patients with a unilateral orbital lesion. The maximum diameters of the superior and inferior oblique muscles were measured on coronal planes. The diameter was measured perpendicular to the long axis of the muscles. RESULTS: The normal measurements (mean ± SD) on fat suppressed contrast enhanced T1-weighted MRI: superior oblique, 3.0 ± 0.5 mm and inferior oblique, 2.7 ± 0.5 mm. On T1-weighted MRI: superior oblique, 2.8 ± 0.5 mm and inferior oblique, 2.5 ± 0.4 mm. In patients who had both sequences performed, the superior and inferior oblique diameters were significantly higher on the fat suppressed contrast-enhanced T1-weighted MRI than the T1-weighted MRI sequence (p < 0.01). CONCLUSION: Oblique muscle enlargement may be seen in a range of orbital diseases. These data may help in diagnosing oblique muscle enlargement. In addition, variations in the measured muscle diameters can be seen according to the scan sequence that is used.

Evaluation of orbital lesions with DCE-MRI: a literature review.

PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Intraorbital and intracranial extension of adenoid cystic carcinoma without clinical or radiological lacrimal gland involvement.

Adenoid cystic carcinoma (AdCC) is a rare epithelial neoplasm of the head and neck, most commonly found in the salivary glands. Orbital AdCC is an uncommon clinical entity arising from the lacrimal glands, however primary orbital AdCC has been previously described in a small number of case reports. The exact origin of the neoplasm with uninvolved lacrimal gland in the orbit is unknown, however it may arise from ectopic lacrimal or salivary gland tissue, or extension from nearby epithelial structures. We describe the clinical characteristics, investigations and management of a 55-year-old man presenting with vertical diplopia, found to have left posterior orbital AdCC invading the skull base with intracranial extension involving the inferotemporal fossa, pterygopalatine fossa, left carotid artery, cavernous sinus and temporal lobe dura, without clinical or radiological lacrimal gland involvement or systemic metastases.

Recurrent odontogenic keratocyst with orbital invasion.

Odontogenic keratocysts (OKCs) are aggressive lesions that have been variously classified as neoplasms or cysts according to the World Health Organisation (WHO). They can be challenging to surgically remove and the cysts can exhibit locally aggressive behaviour if incompletely excised. We describe a case of recurrent OKC invading the orbit requiring multidisciplinary approach for extended surgical excision, and review the current literature regarding this condition.

Idiopathic Lipogranulomatous Orbital Inflammation: A Case Report and Literature Review.

A 57-year old woman presented with a 6-month history of a left red eye associated with diplopia. Examination was remarkable for 2 mm left-sided axial proptosis and restriction on left upgaze and abduction associated with diplopia. She had no previous history of trauma or surgery to the face. Magnetic resonance imaging revealed an enhancing infiltrative mass in the left intraconal space. Biopsy of the anterior orbital fat revealed extensive lipogranulomatous inflammation with no abnormalities noted on flow cytometry, culture, or special stains. The patient was managed with a tapering course of oral prednisolone and two 40 mg intraorbital triamcinolone injections resulting in complete resolution of her presenting symptoms. This represents a rare case of idiopathic lipogranulomatous orbital inflammation.

Hughes flap in the management of lower lid retraction.

PURPOSE: We present a retrospective case series on the use of Hughes flap in managing acquired cicatricial lower lid retraction. METHODS: This was a multicentre, retrospective case series. Data was collected from medical records across different sites within Australia (Adelaide, Melbourne, and Sydney) and New Zealand (Hamilton). RESULTS: Fourteen patients were identified. The aetiology of cicatricial lower lid retraction included previous lid lesion excision and reconstruction, eyelid trauma, orbital fracture repair, orbital radiotherapy, and lateral canthal dystopia from previous lid surgeries. 4/14 (29%) cases had undergone other surgery to correct the retraction prior to the Hughes flap. Pre-operative lagophthalmos due to lower lid retraction was noted in 11/14 (79%) cases with a median 2 mm (range: 1-5 mm). Exposure keratopathy was present in 7/14 (50%) cases. There were no peri-operative complications during Hughes flap reconstruction. One patient had post-operative upper eyelid retraction that did not require any further intervention. One patient had persistent lagophthalmos and exposure keratopathy that is being managed conservatively. One patient had wound dehiscence and further lid retraction following flap division, which required further surgery. Median length of follow-up was 15 months (range: 0.5-84 months). At final review, improvement or resolution of symptoms was seen in 13/14 (93%) cases. CONCLUSIONS: A Hughes flap is an effective surgical technique for the management of cicatricial lower lid retraction.

Normative measurements of orbital structures by magnetic resonance imaging.

PURPOSE: We describe and compare the normative values of orbital structures in an Australian cohort on T1-weighted MRI and fat-suppressed contrast-enhanced T1-weighted MRI. METHODS: Retrospective review of patients who underwent 3T orbital MRI. The maximum extraocular muscle (EOM) and superior ophthalmic vein (SOV) diameters on normal orbits were recorded. The extraocular muscle diameters were summed to produce the sum of all muscles. RESULTS: The normal measurements (mean ± SD) from 141 orbits that had fat-suppressed contrast-enhanced MRI: medial rectus, 4.1 ± 0.5 mm; lateral rectus (LR), 3.9 ± 0.7 mm; superior muscle group (SMG), 4.5 ± 0.7 mm; inferior rectus (IR), 4.6 ± 0.7 mm; and SOV, 1.8 ± 0.7 mm. The normal measurement from 84 orbits that had T1-weighted MRI: MR, 4.1 ± 0.5 mm; LR, 3.4 ± 0.6 mm; SMG, 4.3 ± 0.7 mm; IR, 4.6 ± 0.7 mm; SOV, 2.0 ± 0.7 mm. Eighty-four orbits had both MRI sequences performed. The LR, SMG and the sum of all muscles were significantly larger on fat-suppressed contrast-enhanced T1-weighted MRI sequence than the T1-weighted sequence (P < 0.01), whereas the SOV was significantly larger on the T1-weighted sequence (P < 0.01). CONCLUSION: These data may aid in diagnosing pathological enlargement of the EOMs and SOV on different scan sequences.