MR angiography at 3 Tesla to assess proximal internal carotid artery stenoses: contrast-enhanced or 3D time-of-flight MR angiography?

PURPOSE: The aim of this study was to compare the diagnostic accuracy of 3D time-of-flight (TOF-MRA) and contrast-enhanced (CE-MRA) magnetic resonance angiography at 3 T for detection and quantification of proximal high-grade stenosis using multidetector computed tomography angiography (MDCTA) as reference standard. METHODS: The institutional ethics committee approved this prospective study. A total of 41 patients suspected of having internal carotid artery (ICA) stenosis underwent both MDCTA and MRA. CE-MRA and TOF-MRA were performed using a 3.0-T imager with a dedicated eight-element cervical coil. ICA stenoses were measured according to the North American Symptomatic Carotid Endarterectomy Trial criteria and categorized as 0-25 % (minimal), 25-50 % (mild), 50-69 % (moderate), 70-99 % (high grade), and 100 % (occlusion). Sensitivity and specificity for the detection of high-grade ICA stenoses (70-99 %) and ICA occlusions were determined. In addition, intermodality agreement was assessed with κ-statistics for detection of high-grade ICA stenoses (70-99 %) and ICA occlusions. RESULTS: A total of 80 carotid arteries of 41 patients were reviewed. Two previously stented ICAs were excluded from analysis. On MDCTA, 7 ICAs were occluded, 12 ICAs presented with and 63 without a high-grade ICA stenosis (70-99 %). For detecting 70-99 % stenosis, both 3D TOF-MRA and CE-MRA were 91.7 % sensitive and 98.5 % specific, respectively. Both MRA techniques were highly sensitive (100 %), and specific (CE-MRA, 100 %; TOF-MRA, 98.7 %) for the detection of ICA occlusion. However, TOF-MRA misclassified one high-grade stenosis as occlusion. Intermodality agreement for detection of 70-99 % ICA stenoses was excellent between TOF-MRA and CE-MRA [κ = 0.902, 95 % confidence interval (CI) = 0.769-1.000], TOF-MRA and MDCTA (κ = 0.902, 95 % CI = 0.769-1.000), and CE-MRA and MDCTA (κ = 0.902, 95 % CI = 0.769-1.000). CONCLUSION: Both 3D TOF-MRA and CE-MRA at 3 T are reliable tools for detecting high-grade proximal ICA stenoses (70-99 %). 3D TOF-MRA might misclassify pseudo-occlusions as complete occlusions. If there are no contraindications for CE-MRA, CE-MRA is recommended as primary MR imaging modality.

Anterior spinal artery syndrome in a 13-year-old boy 8 days after taekwondo-fight: vascular obliteration due to vessel lesion or thrombophilia?

BACKGROUND: Spinal cord infarction from anterior spinal cord syndrome (ASAS) in children is a rare pathology and comprises the following clinical symptoms: sudden onset of pain and flaccid para- or tetraparesis, bladder dysfunction, and dissociated sensory loss with impairment of pain and temperature perception. Deep sensibility is not affected. PATIENT: A 13-year-old male patient presented to our emergency department with a bilateral leg weakness. 1 week before, he had suffered a leg strain in a Taekwondo-fight from which he recovered completely. On physical examination our patient's legs were in flaccid paralysis, tone was decreased and he had dissociated sensory loss and acute retention of urine. Blood count, ESR, electrolytes, serologic tests for various pathogens and CSF examination all were normal. However, tests for values of an acute endothelial lesion were increased and he was a homozygous carrier of MTHFR-polymorphism. MRI performed on the day of admission was normal but showed dramatic changes 2 days later with increased signal intensity in the ventral aspect of the spinal cord, characteristic for an ASAS. Treatment included highdose methylprednisolone, a suprapubic bladder catheter, sufficient anticoagulation and a rapid transfer to a rehabilitation centre. DISCUSSION: We assume that a combination of the patient's prothrombotic risk factor (MTHFR-polymorphism with elevated homocysteine levels) and his trauma in the taekwondo-fight with consecutive vessel injury caused an occlusion of the artery by late emboli or a growing thrombus.