The purpose of our experimental study was to assess the accuracy and precision of CT angiography (CTA), MR angiography (MRA) and rotational digital subtraction angiography (DSA) for measuring the volume of an in vitro aneurysm model. A rigid model of the anterior cerebral circulation harbouring an anterior communicating aneurysm was connected to a pulsatile circuit. It was studied using unenhanced 3D time-of-flight MRA, contrast-enhanced CTA and rotational DSA angiography. The source images were then postprocessed on dedicated workstations to calculate the volume of the aneurysm. CTA was more accurate than MRA (P=0.0019). Rotational DSA was more accurate than CTA, although the difference did not reach statistical significance (P=0.1605), and significantly more accurate than MRA (P<0.00001). CTA was more precise than MRA (P=0.12), although this did not reach statistical significance. Rotational DSA can be part of the diagnosis, treatment planning and support endovascular treatment of intracranial aneurysms. The emerging endovascular treatment techniques which consist of using liquid polymers as implants to exclude aneurysms from arterial circulation would certainly benefit from this precise measurement of the volume of aneurysms.
Here we describe an anatomic structure that takes the form of a venous channel (VC) within the two layers of the lateral wall of the cavernous sinus (CS). Colored gelatin was injected in both superficial middle cerebral veins (SMCV) of 29 human specimens. When a SMCV terminated into the CS, the latter was dissected giving particular attention to its lateral wall. The termination of the VC and its eventual communications with the CS and adjacent venous structures were studied. A VC in the lateral wall of the CS was found in 14 of 58 lateral walls (24.1%). It was in continuation with the SMCV in 13 cases, with the uncal vein in one case. The VC drained into the superior petrosal sinus (71.4%), the pterygoid plexus (21.4%), or the posterior part of the CS (7.2%). Two alternate drainage pathways for the SMCV were observed, toward the anterosuperior aspect of the CS (13.8%) or through a paracavernous sinus located along the floor of the middle cranial fossa (32.8%). These different pathways were not observed to occur concomitantly. SMCV were absent in 29.3%. Despite its close topographic relation with the CS, the VC in the lateral wall can be considered as an anatomic entity with potential clinical relevance. We propose to call it the laterocavernous sinus.
Summary: An in vitro model of the main human cerebral arteries with or without saccular arterial aneurysms is presented. A cast of the cerebral arteries was obtained in a human specimen. Three aneurysms were simulated and added to the cast. Wax copies of the cast were produced, and embedded with liquid resin solidifying into solid blocks. After evacuation of the wax, a model consisting of a hollow reproduction of the cast within the resin block was obtained. The model is reproducible and anatomically accurate. Since it is transparent to visible light, and compatible with xray, magnetic resonance and transcranial doppler techniques, it should prove useful for a wide range of haemodynamic and radiologic investigations. The reported technique may be adapted to any structure with a hollow configuration, allowing for the preparation of arterial and venous models from other vascular areas, as well as models from other anatonfic systems, such as the biliary or urinary tracts.
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