RESUMEN
BACKGROUND: Thin cerebral aneurysm wall thickness (AWT) is connected to high aneurysm rupture risk. MR imaging of AWT leads to overestimations. The aim of the present study was to quantify MR inaccuracy by comparison with accurate light microscopic measurements. METHODS: In 13 experimental microsurgical bifurcation aneurysms in rabbits, 3 Tesla (3 T)-MR imaging using contrast-enhanced T1 Flash sequences (resolution: 0.4 × 0.4 × 1.5 mm³) was performed. The aneurysms were retrieved immediately after MR acquisition, cut longitudinally, and calibrated photographs were obtained. AWT (dome, neck) and parent vessel thickness (PVT) were measured on the MR images and microscopic photographs by independent investigators. All parameters were statistically compared (Wilcoxon test, Spearman correlation). RESULTS: AWT and PVT could be imaged and measured in all aneurysms with good quality. Comparison with the "real" light microscopic measurements showed a progressive tendency of MR AWT overestimation with smaller AWT: AWT at the dome (0.24 ± 0.06 mm vs. MR 0.30 ± 0.08 mm; p = 0.0078; R = 0.6125), AWT at the neck (0.25 ± 0.07 mm vs. MR 0.29 ± 0.07 mm; p = 0.0469; R = 0.7451), and PVT (0.46 ± 0.06 mm vs. MR 0.48 ± 0.06 mm; p = 0.5; R = 0.8568). CONCLUSION: In this experimental setting, 3 T-MR imaging of cerebral AWT showed unacceptable inaccuracies only below the image resolution threshold. Theoretically, AWT for clinical usage could be classified in ranges, defined by the maximum image resolution.
Asunto(s)
Aneurisma Roto/patología , Arterias Cerebrales/patología , Aneurisma Intracraneal/patología , Angiografía por Resonancia Magnética/métodos , Microscopía/métodos , Animales , Angiografía Cerebral/métodos , Modelos Animales de Enfermedad , Imagenología Tridimensional/métodos , Conejos , Sensibilidad y EspecificidadRESUMEN
BACKGROUND: Thin aneurysm wall thickness (AWT) is thought to portend an elevated risk of intracranial aneurysm rupture. Magnetic resonance imaging (MRI) is biased by AWT overestimations. Previously, this suspected bias has been qualitatively described but never quantified. We aimed to quantify the overestimation of AWT by MRI when compared to the gold standard of AWT as measured by light microscopy of fresh aneurysm specimens (without any embedding procedure). This analysis should help to define the clinical potential of MRI estimates of AWT. METHODS: 3-Tesla (3T) MRI (contrast-enhanced T1 Flash sequences; resolution: 0.4 x 0.4 x 1.5 mm(3)) was performed in 13 experimental aneurysms. After MR acquisition, the aneurysms were retrieved, longitudinally sectioned and calibrated micrographs were obtained immediately. AWT at the dome, AWT at the neck and parent vessel wall thickness (PVT) were measured on precisely correlated MR-images and histologic micrographs by blinded independent investigators. Parameters were statistically compared (Wilcoxon test, Spearman's correlation). RESULTS: AWT was assessed and reliably measured using MRI. Interobserver variability was not significant for either method. MR overestimation was only significant below the image resolution threshold: AWT at the dome (0.24 ± 0.06 mm vs. MR 0.30 ± 0.08 mm; p = 0.0078; R = 0.6125), AWT at the neck (0.25 ± 0.07 mm vs. MR 0.29 ± 0.07 mm; p = 0.0469; R = 0.7451), PVT (0.46 ± 0.06 mm vs. MR 0.48 ± 0.06 mm; p = 0.5; R = 0.8568). CONCLUSION: In this experimental setting, MR overestimations were minimal (mean 0.02 mm) above the image resolution threshold. When AWT is classified in ranges defined by the MR resolution threshold, clinical usage may be beneficial. Further quantitative and comparative experimental and human studies are warranted to confirm these findings.
Asunto(s)
Aneurisma Intracraneal/patología , Angiografía por Resonancia Magnética , Vasos Sanguíneos/patología , Humanos , Imagenología Tridimensional/métodos , Aneurisma Intracraneal/diagnóstico por imagen , Aneurisma Intracraneal/cirugía , Angiografía por Resonancia Magnética/métodos , Microscopía/métodos , Radiografía , Procedimientos Quirúrgicos VascularesRESUMEN
OBJECTIVE: Spontaneous spinal epidural hematoma (SEH) has not been reported under anti-thrombotic therapy with acetyl-salicylic acid (ASA) in a dosage of 50 mg/d. METHODS: Spinal MRI, emergency laminectomy. RESULTS: A 77-yo, HIV-negative female under longterm treatment over three years with ASA 50 mg/d for varicositas, prescribed by her general practitioner, experienced sudden onset back pain with radiation towards both knees after getting up in the morning. One-and-a-half hours later she also developed ascending hypesthesia and weakness originating from both distal lower limbs. Three hours after onset, hypesthesia had reached the T10-level bilaterally and she had become paraplegic. There was reduced intestinal motility, stool incontinence, and urinary hesitancy. MRI of the thoraco-lumbar spine demonstrated a SEH T9-L1 indenting the dural sack and compressing the myelon. Immediately after emergency laminectomy T10-12 with micro-surgical evacuation of the clot, 12 h after onset, she could move both legs again and was able to walk with support 7 days after surgery. CONCLUSIONS: This case shows that SEH occurs under a minimal dose of ASA and that such patients rapidly recover upon immediate surgical decompression and evacuation of the hematoma.