Assessment of the optic nerve using strain and shear-wave elastography in patients with pseudotumour cerebri

Study of the optic nerve in patients with type 2 diabetic retinopathy by shear-wave elastography

AIM

To investigate the clinical value of two-dimensional shear-wave elastography (2D-SWE) in detecting optic nerve elasticity and in-frame adipose tissue elasticity in patients with type 2 diabetic retinopathy (DR).

MATERIALS AND METHODS

2D-SWE was used to detect SWE values of the optic nerve and adipose tissue in adjacent optic nerve frames in 30 healthy participants, 30 patients with diabetic non-retinopathy (NDR), 35 patients with non-proliferative diabetic retinopathy (NPDR), and 30 patients with proliferative diabetic retinopathy (PDR). The correlation between SWE values and blood glucose, blood lipid, age, body mass index (BMI) was analysed. Receiver operating characteristic (ROC) curve analysis was performed for SWE values.

RESULTS

The SWE values of the optic nerve and in-frame adipose tissue increased with the progression of DR, and analysis of variance was compared with groups: the SWE values of the optic nerve and in-frame adipose tissue in each group were significantly different (all p<0.001). The SWE values of the optic nerve and in-frame adipose tissue correlated positively with BMI, age, triglyceride, and fasting blood glucose, and correlated negatively with high-density lipoprotein. The SWE values of the optic nerve and in-frame adipose tissue had higher diagnostic efficacy. The combination of the two had higher diagnostic accuracy.

CONCLUSION

The elastic modulus of optic nerve and in-frame adipose tissue can effectively predict and grade of DR, that is, 2D-SWE can be used as a non-invasive imaging diagnostic method for DR. The combined diagnostic efficacy of optic nerve SWE value and in-frame adipose tissue SWE value is significantly better than that of single use. This study found that increased BMI, age, triglyceride, and fasting blood glucose, and decreased high-density lipoprotein are risk factors for DR.

Utilizing shear wave elastography for the evaluation of optical nerve involvement in Behçet's disease

In this study, we investigated the elasticity of the optic nerve using shear wave elastography (SWE) in patients with Behçet's Disease (BD) and compare findings with a healthy control group. Optic nerve measurements of 40 eyes in the BD group and 38 eyes in the control group were performed by SWE (SWE-right and SWE-left). The mean age of the individuals in the BD group was higher than controls (p = 0.022). The SWE measurement results in the right eye were significantly higher in the BD group (p = 0.005), while SWE-left values were similar in the two groups (p = 0.206). There was a moderate positive correlation between age and SWE-right (r = 0.347, p = 0.031), there was no correlation between SWE-left and age (p = 0.756). It was found that SWE-right had significant value in distinguishing between BD and healthy controls (sensitivity: 75%, specificity: 78.9%; p = 0.005); whereas, SWE-left did not (p = 0.206). In the multiple logistic regression analysis, after adjusting for age and sex, the performance of SWE-right to distinguish BD patients from controls was found to remain significant (OR: 15.045, 95% CI: 2.33-97.120, p = 0.004). Due to the fact that only SWE-right values appear to have significant discriminatory performance for BD, it is feasible to suggest that the frequency and severity of BD involvement are associated with SWE-related changes in the optic nerve. This finding indicates the need for more comprehensive studies evaluating optic nerve SWE values in this context.

Non-invasive intracranial pressure assessment using shear-wave elastography in neuro-critical care patients

OBJECTIVE

To determine if Young's modulus of the optic nerve (ON) structure as measured by shear-wave elastography can suggest changes in intracranial pressure (ICP) in neuro-critical care patients.

MATERIALS AND METHODS

Thirty-one healthy volunteers and twenty-two neuro-critical care patients were enrolled. ON sheath (ONS) diameter (ONSD) values and Young's modulus measurements of volunteers were collected in a calm state and during a Valsalva maneuver (VM). Ultrasound measurements and ICP values of patients were collected on operation day and at 24 and 48 h after the operation; measurements were thereafter assigned to three groups: severely elevated (ICP greater than 22 mmHg), mildly elevated (ICP = 14-22 mmHg), and normal (ICP ≤ 13 mmHg).

RESULTS

ONSD and Young's modulus for the ON and ONS of volunteers during VM were higher than those in the calm state (all P < 0.001). In contrast to ONSD, Young's modulus for ON and ONS did not correlate with age, body mass index, or sex. The best cutoff values of Young's modulus for ON for predicting elevated and severely elevated ICP were 16.67 kPa and 22.74 kPa, respectively. Accordingly, the sensitivity values were 96.7% and 88.9%, and the specificity values were 86.1% and 73.7%, which had the same diagnostic performance as ONSD.

CONCLUSION

Young's modulus of the ON accurately reflects changes in ICP. It is not confounded by age, sex, or body mass index compared to ONSD.

Effect of changes in optic nerve elasticity on central retinal artery blood flow in patients with idiopathic intracranial hypertension

PURPOSE

To assess changes in central retinal artery (CRA) blood flow by orbital color-coded Doppler ultrasonography in patients with idiopathic intracranial hypertension (IIH) and their relation with optic nerve (ON) elasticity assessed by shear wave elastography (SWE).

METHODS

This study was carried out on 68 eyes of patients diagnosed with IIH and 32 eyes of healthy controls. The severity of papilledema in IIH patients was sub-classified into mild and moderate/severe groups. Color-coded Doppler was used to measure peak systolic velocity (PSV), end diastolic velocity (EDV), mean velocity (V_mean) and pulsatility index (PI) of the CRA.

RESULTS

PSV, V_mean, and SWE were significantly higher in patients with IIH than in controls (p = 0.001). The optimal cut-off values of PSV and V_mean for differentiating IIH patients from controls were 11.25 and 6.75 cm/s with AUC 0.81 and 0.785 respectively. AUC was 0.92 and accuracy 91% for combined PSV, V_mean and SWE differentiation between IIH patients and controls. PSV, V_mean and SWE were significantly different between mild versus moderate/severe papilledema (p = 0.001). PSV and V_mean were correlated with papilledema (r = 0.790 and 0.722 respectively) and SWE (r = 0.818 and 0.761 respectively).

CONCLUSION

IIH is associated with decreased ON elasticity and reduced CRA blood flow. Individual and combined color-coded Doppler of the CRA and SWE help in diagnosis of IIH. CRA hemodynamic changes are correlated with papilledema severity and with the extent of biomechanical changes in the ON represented by SWE.

Combined accuracy of optic nerve sheath diameter, strain ratio, and shear wave elastography of the optic nerve in patients with idiopathic intracranial hypertension

PURPOSE

This study assessed the combined accuracy of optic nerve sheath diameter (ONSD), strain ratio (SR), and shear wave elastography (SWE) of the optic nerve (ON) in patients with idiopathic intracranial hypertension (IIH).

METHODS

This prospective study was carried out on both ONs of 34 consecutive patients diagnosed with IIH and 16 age- and sex-matched healthy volunteers. All of the study participants were women. The ONSD, SR, and SWE of the ON were measured. The severity of papilledema of IIH patients was sub-classified into mild papilledema and moderate/severe papilledema.

RESULTS

The mean ONSD (5.6±1.1 mm), SR (0.7±0.1), and SWE (30.1±16.7 kPa) of the IIH patients were significantly different (P=0.001) from the ONSD (4.1±0.5 mm), SR (0.9±0.1), and SWE (8.2±3.4 kPa) of controls. The cutoff values of ONSD, SR, and SWE of the ON for differentiating IIH patients from controls were 5.45 mm, 0.8, and 10.3 kPa with areas under the curve (AUCs) of 0.91, 0.86, and 0.96 and accuracy values of 91%, 81%, and 93%, respectively. Combined SWE and ONSD and combined SWE, ONSD, and SR for differentiating IIH patients from controls revealed AUCs of 0.98 and 0.99 and accuracy values of 96% and 96%, respectively. ONSD, SR, and SWE showed significant differences between mild and moderate/severe papilledema (P=0.001). Papilledema was correlated with SWE (r=0.8, P=0.001), ONSD (r=0.4, P=0.001), and SR (r=-0.4, P=0.001).

CONCLUSION

The combination of ONSD, SR, and SWE may be helpful for diagnosing IIH, and a good indicator of the degree of papilledema.

Evaluating the optic nerve stiffness and optic nerve sheath diameter in idiopathic intracranial hypertension patients after the resolution of papilledema

PURPOSE

The objective of this study was to investigate the optic nerve's elastic properties and optic nerve sheath diameter (ONSD) using shear-wave elastography (SWE) in patients with idiopathic intracranial hypertension (IIH) compared to healthy individuals.

METHODS

The study included 22 IIH patients and 15 healthy subjects. SWEs were performed on the optic nerve and ONSD, and optic nerve stiffness were measured.

RESULTS

The patients with IIH demonstrated higher stiffness of the optic nerve compared with that of healthy volunteers (P < 0.001). The optic nerve sheath diameter of the optic nerve in the IIH group was significantly larger than that in the control group (P < 0.001). There was no correlation between the disease duration and SWE values in the Spearman correlation test.

CONCLUSION

These findings suggest that ONSD can be used as a follow-up method in the treatment of IIH. However, there was not any correlation between the disease duration and SWE-based stiffness measurement of the optic nerve.