Table 2.
Advantages of large animal models for neurointerventional research.
| Small animal | Large animal | Human | References | ||
|---|---|---|---|---|---|
| Brain | Size | Small | Large | Large | 10,14,113 |
| Encephalization quotient (EQ) | 0.4 (rat), 0.5 (mouse) | 0.8 (sheep), 1.2 (dog) and 2.1 (rhesus monkey) | 6.56 | 113,114 | |
| Anatomy | Lissencephalic Mouse: GM/WM: 90%/10% Rat: GM/WM: 88%/12% Soft tentorium cerebelli | Gyrencephalic Dog: GM/WM: 63%/37% Sheep: GM/WM: 70%/30% rhesus monkey: GM/WM: 68%/32% Rigid tentorium cerebelli | Gyrencephalic Gray matter: 55% White matter: 45% Rigid tentorium cerebelli | 14,10,115–117,112 | |
| Vascular supply | Similar to humans | Dog, rabbit, NHP: similar to humans tortuosity of canine ICA Sheep, pig, cat: rete mirabile (sheep, cat: ICA, pig: ascending pharyngeal artery) | Internal carotid artery (ICA), basiliary artery | 40,46,42,72,118,119 | |
| Vessel | Size | Rat: MCA diameter 0.35–0.58 mm Diameter often too small for endovascular approaches | Similar to humans e.g. dog: MCA diameter 2–3.5 mm Diameter large enough for endovascular access | MCA diameter 2.7–3.5 mm | 89,95,10,12,120–124 |
| physiology | Similar to humans | Similar to humans, e.g.: degree of vasospasm (dog) fibrinolytic response (rabbit) platelet response (NHP) | 89,121,42 | ||
| Circle of Willis (CW) | Rat, mouse: similar to humans, except missing anterior communicating artery | Dog, rabbit, monkey: similar to humans, except missing anterior communicating artery and single median anterior cerebral artery (ACA) Sheep and swine: different to humans: internal carotid artery forms large part of CW, irregular anterior communicating artery | Main arteries: internal carotid artery, vertebral artery contributing arteries: anterior cerebral artery, anterior communicating artery, posterior cerebral artery, posterior communicating artery, basilar artery Incidence of complete circle of Willis: 37.1% (overalls); 43.8% (females); 31.2% (male) Most frequent of 28 variations of CW: absent posterior communicating artery (right side: 15.3%; left side: 10.9%; bilaterally: 17.1%) | 125–129 | |
| Imaging | Dedicated small animal scanners required | Clinical systems applicable | Clinical systems available | ||
| X-ray-based | Possible (angiography, CT) | Possible (angiography, fluoroscopy, CT) | Standard routine | 130,77,12,131,132 | |
| Radionuclide | Possible (PET, SPECT) | Possible (PET, SPECT) | Standard routine | 133,134 | |
| Nuclear magnetic resonance | Possible (NMR, MRI) | Possible (NMR, MRI) | Standard routine | 135,77 | |
| Ultrasound | Possible, but rarely performed | Possible | Standard routine | 136 | |
| Physiological parameter assessment | Recording | More challenging | Easy | Standard routine | 76,137,9,138 |
| Instrumentation | Requires specialized device configuration | Human appliances can be used | Standard routine | 76,137,9,138 | |
| Simultaneous recording | Restricted | Possible, multiple parameters | Standard routine | 76,137,9,138 |
ICA: internal carotid artery; NHP: non-human-primate; ACA: anterior cerebral artery; CT: computed tomography; PET: positron emission tomography; SPECT: single photon emission computed tomography; MRI: magnetic resonance imaging; NMR: nuclear magnetic resonance; GM: grey matter; WM: white matter.