Computed Tomographic Angiography in Evaluation of Superficial Temporal to Middle Cerebral Artery Bypass:

Comparison of IMD and ICG videoangiography in combined bypass surgery: a single-center study

BACKGROUND

Superficial temporal artery-middle cerebral artery (STA-MCA) bypass combined with an encephaloduromyosynangiosis (EDMS) had gained significant role in treating chronic cerebral ischemia. Invasiveness and costs of intraoperative digital subtraction angiography (DSA) limited its application in operations.

OBJECTIVE

To find the reliable parameters for determining bypass patency with intraoperative micro-Doppler (IMD) sonography and compare the diagnostic accuracy of indocyanine green (ICG) videoangiography with IMD in combined bypass.

METHOD

One hundred fifty bypass procedures were included and divided into patent and non-patent groups according to postoperative computed tomography angiography (CTA) within 72 h. The surgical process was divided into four phases in the following order: preparation phase (phase 1), anastomosis phase (phase 2), the temporalis muscle closure phase (phase 3), and the bone flap closure phase (phase 4). The IMD parameters were compared between patent and non-patent groups, and then compared with the patency on CTA by statistical analyses. IMD with CTA, ICG videoangiography with CTA, IMD with ICG videoangiography were performed to assess bypass patency. The agreement between methods was evaluated using kappa statistics.

RESULTS

No significant differences of baseline characteristics were found between patent and non-patent group. Parameters in the STA were different between patent and non-patent groups in phases 2, 3, and 4. In patent group, Vm was apparently higher and PI was lower in phases 2, 3, and 4 compared with phase 1 (P < .001). In non-patent group, no differences of Vm and PI were found within inter-group. The best cutoff value of IMD in the STA to distinguish patent from non-patent bypasses was Vm in phase 4 > 17.5 cm/s (sensitivity 94.2%, specificity 100%). In addition, the agreement for accessing bypass patency was moderate between ICG videoangiography and CTA (kappa = 0.67), IMD and ICG videoangiography (kappa = 0.73), and good between IMD and CTA (kappa = 0.86).

CONCLUSION

ICG videoangiography could directly display morphology changes of bypass. IMD could be used for providing half-quantitative parameters to assess bypass patency. Vm in phase 4 > 17.5 cm/s suggesting the patency of bypass on CTA would be good. Also, compared with ICG videoangiography, IMD had more accuracy.

Assessment of bypass patency using transcranial Doppler sonography: correlations with computerized tomography angiography findings in patients with moyamoya disease

To explore the utility of transcranial Doppler (TCD) findings when assessing bypass patency in patients with Moyamoya disease (MMD). Computed tomography angiography (CTA) and TCD sonography (TCDS) were performed before and after surgery to evaluate bypass patency. The peak systolic flow velocity (PSV) of the superficial temporal artery (STA) and the pulsatility index (PI) were compared between the groups that achieved patency and not, and receiver operating characteristic (ROC) curve analyses were used to define the TCDS criteria revealing patency. This study included 35 hemispheres (15 women; mean age 47 years) with Moyamoya disease who underwent STA-middle carotid artery bypass in our institution between January 2022 and October 2022. The PSV first increased on postoperative days 4-5 and then decreased on postoperative days 6-7 and 7-8. Patients with transient neurological diseases (TNDs), compared to those without, evidenced a significantly lower PSV value (P < 0.05). Compared with the non-patency group, the PSV was higher (P < 0.001) in the patency group. The cutoff values reflecting patency with good sensitivity and specificity were PSV > 49.00; PSV ratio (postoperative/preoperative) > 1.218; PSV ratio (operation side/contralateral side) > 1.082; and PSV ratio (adjusted) > 1.202. In the patency group, the PSV and PI significantly increased (P < 0.001) and decreased (P < 0.001) respectively. Bypass patency can be noninvasively and accurately evaluated via TCDS, affording an objective basis for assessment of the effect of revascularization surgery on patients with MMD.

Visualization of extracranial-intracranial bypass in moyamoya patients using intraoperative three-dimensional digital subtraction angiography with intravenous contrast injection and robotic C-arm: patient series

BACKGROUND

The authors describe a noninvasive intraoperative imaging strategy of three-dimensional (3D) digital subtraction angiography (DSA) with intravenous (IV) contrast injection, using indocyanine green (ICG) as a test bolus, during extracranial-intracranial (EC-IC) bypass surgery for moyamoya disease.

OBSERVATIONS

Four patients underwent EC-IC bypass surgery in a hybrid operating room. During the surgery, bypass patency was verified using ICG videoangiography and Doppler ultrasonography. After skin closure, the patients under anesthesia underwent IV 3D-DSA with a robotic C-arm in which the scan delay time for the 3D-DSA scan was estimated from the arrival time of ICG during the ICG videoangiography. One day after the surgery, the patients underwent magnetic resonance angiography (MRA). The IV 3D-DSA images were retrospectively compared with those obtained with other modalities. Good bypass patency was confirmed on IV 3D-DSA, ICG videoangiography, Doppler ultrasonography, and postoperative MRA in all cases. The delay time determined using ICG videoangiography as a test bolus resulted in IV 3D-DSA with adequate image quality, allowing assessment of the spatial relationships between the vessels and anastomoses from all directions.

LESSONS

To evaluate bypass patency and anatomical relationships immediately after EC-IC bypass surgery, IV 3D-DSA may be a useful modality. ICG videoangiography can be used to determine the scan delay time.

The evaluation of intracranial bypass patency in neurosurgical practice

BACKGROUND

The patency of cranial bypasses must be carefully evaluated during and after the microsurgical procedure. Although, several imaging techniques are used to evaluate the patency of bypasses, their findings are sometimes difficult to interpret.

PURPOSE

The goal of this study was to assess the consistency of different diagnostic modalities for evaluating intracranial bypass patency.

PATIENTS AND METHOD

This prospective study included 19 consecutive patients treated with EC-IC or IC-IC bypass for MoyaMoya disease (MMD) or complex/giant aneurysms between June 2016 and June 2018. In the early postoperative period (<7 days), all patients had transcranial Doppler (TCD), CT angiography (CTA) and MRA to demonstrate patency of anastomoses and to confirm exclusion of the aneurysm. When findings of anastomosis patency differed between these techniques, conventional angiography was performed.

RESULTS

All anastomoses were patent on indocyanine green videoangiography at the end of microsurgical procedure. The results of noninvasive postoperative exams were consistent to demonstrate the patency of anastomoses in 13 patients. In 4 patients, a discrepancy in patency of anastomoses arose between TCD, CTA and MRI in the early postoperative period. In 2 other patients, the interpretation of bypass patency remained inconclusive before the decision to occlude the aneurysm. In these 6 patients, a significant edema was noted in 2 cases, a postoperative subdural hematoma in 1 case, a low flow in the anastomosis in 1 case and vasospasm in 2 cases. The anastomosis was patent on the conventional angiography in five patients.

CONCLUSION

Noninvasive imaging techniques provide useful data about the patency but their findings should be carefully interpreted due to local anatomical, physiological, and pathological factors. In case of discrepant findings, conventional angiography including supraselective catheterization of the donor vessel is suggested.