Feasibility of low-dose digital subtraction angiography protocols for the endovascular treatment of intracranial dural arteriovenous fistulas

Minimizing eye lens radiation exposure using lens tracking in neurointerventional procedures: retrospective clinical and phantom study

BACKGROUND

The eye lens is particularly vulnerable to radiation during endovascular treatments for intracranial aneurysms due to prolonged exposure under high magnification. This study presents a lens tracking method to monitor lens positions during procedures and estimate radiation doses using a phantom.

METHODS

A consecutive series of patients treated between January and March 2023 were retrospectively reviewed. A lens tracking method was used to mark lenses on three-dimensional source images to track their positions on two-dimensional working views. An anthropomorphic head phantom and photoluminescent glass dosimeters were used to estimate lens exposure under simulated conditions. We also evaluated potential radiation reduction with collimation based on the lens position.

RESULTS

Among 42 patients, 20 (48%) had their eye lens in the field of view (FOV). In 10 of these cases, collimation could have prevented direct exposure. The phantom study showed a median lens dose of 7.32 (5.02-9.59) mGy. Lenses within the anterior-posterior (AP) plane FOV received higher doses compared with those outside it (4.32 mGy vs 1.76 mGy, P<0.001). In the lateral plane, lenses outside the FOV showed significant dose differences (left lens: 5.02 mGy vs right lens: 2.45 mGy, P<0.001). Collimation reduced lens doses by 60% in the AP plane and 52% in the lateral plane (P<0.001 and P=0.001, respectively) with greater reductions for lenses initially in the FOV.

CONCLUSION

In this study, lenses were often included in the FOV, thereby receiving higher radiation doses. This underscores the importance of tracking and excluding lenses from the FOV to reduce radiation exposure during procedures.

Effectiveness of wedge filter application in reducing lens radiation dose during diagnostic cerebral angiography: a phantom and prospective study

OBJECTIVE

Diagnostic cerebral angiography poses a risk of direct radiation exposure to the eye lens. This study aimed to evaluate the effectiveness of using a wedge filter to reduce lens exposure during examination.

METHODS

A phantom study was initially conducted to evaluate the efficacy and determine the optimal depth of the wedge filter. Twenty patients with intracranial aneurysms scheduled for diagnostic cerebral angiography were prospectively enrolled. For each patient, the lens dose reduction protocol (involving a wedge filter) was used on one internal carotid artery (ICA), whereas the standard protocol was applied to the other ICA. Photoluminescent glass dosimeters were used to measure the lens dose. Quantitative noise measurements and qualitative analysis were performed to assess image quality.

RESULTS

The phantom study demonstrated that the wedge filter reduced the radiation dose to the eye lens in anteroposterior (25.5% reduction at 4 cm depth) and lateral projections (28.8% reduction at 3 cm depth). In the patient study (20 patients, 60% female, mean age 57.5 years), the lens dose reduction protocol reduced the dose by 47.2% compared with the standard protocol (median 1.06 mGy vs 0.56 mGy, p < 0.001). In both protocols, the left lens dose was significantly higher than the right (standard: 1.37 mGy vs 0.70 mGy, p < 0.001; reduction: 0.75 mGy vs 0.36 mGy, p < 0.001). No significant differences were observed in image noise or quality.

CONCLUSION

The wedge filter significantly reduced the lens radiation dose during cerebral angiography without affecting image quality.

KEY POINTS

Question The radiation dose to the eye lens during cerebral angiography remains unclear; a targeted method is needed to selectively reduce exposure to this radiosensitive organ. Findings This study directly measured eye lens radiation dose and found that using a wedge filter reduces exposure by nearly half while maintaining diagnostic image quality. Clinical relevance Using a wedge filter during routine neuroangiography effectively reduces eye lens radiation exposure with a simple operation, preserving image quality and potentially lowering the risk of radiation-induced cataracts.

Reduction of Radiation Dose to Eye Lens in Cerebral 3D Rotational Angiography Using Head Off-Centering by Table Height Adjustment: A Prospective Study

OBJECTIVE

Three-dimensional rotational angiography (3D-RA) is increasingly used for the evaluation of intracranial aneurysms (IAs); however, radiation exposure to the lens is a concern. We investigated the effect of head off-centering by adjusting table height on the lens dose during 3D-RA and its feasibility in patient examination.

MATERIALS AND METHODS

The effect of head off-centering during 3D-RA on the lens radiation dose at various table heights was investigated using a RANDO head phantom (Alderson Research Labs). We prospectively enrolled 20 patients (58.0 ± 9.4 years) with IAs who were scheduled to undergo bilateral 3D-RA. In all patients' 3D-RA, the lens dose-reduction protocol involving elevation of the examination table was applied to one internal carotid artery, and the conventional protocol was applied to the other. The lens dose was measured using photoluminescent glass dosimeters (GD-352M, AGC Techno Glass Co., LTD), and radiation dose metrics were compared between the two protocols. Image quality was quantitatively analyzed using source images for image noise, signal-to-noise ratio, and contrast-to-noise ratio. Additionally, three reviewers qualitatively assessed the image quality using a five-point Likert scale.

RESULTS

The phantom study showed that the lens dose was reduced by an average of 38% per 1 cm increase in table height. In the patient study, the dose-reduction protocol (elevating the table height by an average of 2.3 cm) led to an 83% reduction in the median dose from 4.65 mGy to 0.79 mGy (P < 0.001). There were no significant differences between dose-reduction and conventional protocols in the kerma area product (7.34 vs. 7.40 Gy·cm², P = 0.892), air kerma (75.7 vs. 75.1 mGy, P = 0.872), and image quality.

CONCLUSION

The lens radiation dose was significantly affected by table height adjustment during 3D-RA. Intentional head off-centering by elevation of the table is a simple and effective way to reduce the lens dose in clinical practice.

Cerebral venous sinus thrombosis and dural arteriovenous fistula associated with protein S deficiency: a case series study

OBJECTIVE

To describe the characteristics of patients with cerebral venous sinus thrombosis (CVST) and dural arteriovenous fistula (AVF) associated with protein S (PS) deficiency.

METHODS

We conducted a search of medical records in Hainan General Hospital from January 2000 to December 2020 for coexistence of CVST and dural AVF associated with PS deficiency and searched PubMed、Embase and Chinese biomedical databases (CBM) for all literature describing CVST and dural AVF with PS. We analyzed clinical characteristics, location, sequence of CVST and dural AVF, level of PS, therapeutic methods and prognosis.

RESULTS

We presented 1 patient in our hospital's database combined CVST and dural AVF associated with PS, plus 5 cases reported in literature. The most common symptoms were headache, generalized seizure, disturbance of consciousness. The most frequent location of CVST was at internal cerebral vein, while transverse sinus, sigmoid sinus, parietal region in dural AVF. Two patients developed dural AVF several months or years after CVST. Clinical characteristics and level of PS were summarized.

CONCLUSION

These findings alert physicians to consider PS deficiency in patients who suffer from CVST, especially those combined with dural AVF.