1.Intracranial aneurysm detection with 3T magnetic resonance angiography.
Phua-Hwee TANG ; Francis HUI ; Yih-Yian SITOH
Annals of the Academy of Medicine, Singapore 2007;36(6):388-393
INTRODUCTIONThe new 3 Tesla (T) magnetic resonance (MR) scanners yield improved signal-to-noise ratio and spatial resolution with superior background suppression compared to lower field strength systems. This is advantageous for MR angiograms. The purpose of our study was to compare unenhanced three-dimensional time-of-flight magnetic resonance angiography (3D TOF MRA) at 3T with catheter digital subtraction angiography (DSA) in detecting unruptured intracranial aneurysms.
MATERIALS AND METHODSOut of 1375 consecutive patients who underwent unenhanced 3D TOF MRA at 3T, 15 patients with unruptured intracranial aneurysms were retrospectively identified. Nine of these 15 patients had DSA as the reference standard for comparison. Aneurysm size, location and morphology were independently assessed on both MRA and DSA by 2 radiologists.
RESULTSSeventeen aneurysms ranging in size from 1 mm to 24 mm were identified in 15 patients on MRA. DSA confirmed the aneurysms in 9 patients with good anatomical correlation compared with the MRA findings.
CONCLUSIONS3D TOF MRA at 3T has good correlation with DSA and aneurysms as small as 1 mm in size can be detected. This can be a promising, non-invasive method for aneurysm surveillance.
Adult ; Aged ; Angiography, Digital Subtraction ; Female ; Humans ; Image Processing, Computer-Assisted ; methods ; Intracranial Aneurysm ; diagnosis ; Magnetic Resonance Angiography ; methods ; Male ; Middle Aged ; Retrospective Studies ; Singapore
2.Imaging findings of chronic subluxation of the os odontoideum and cervical myelopathy in a child with Beare-Stevenson cutis gyrata syndrome after surgery to the head and neck.
Annals of the Academy of Medicine, Singapore 2009;38(9):832-834
INTRODUCTIONAlthough uncommon, fractures of the os odontoideum are known to occur in children under 7 years old, following acute trauma.
CLINICAL PICTUREWe report a case of chronic subluxation of the os odontoideum resulting in cervical myelopathy in a child with Beare-Stevenson cutis gyrata syndrome after surgery to the head and neck.
TREATMENT AND OUTCOMEThe patient was initially put in a Halo vest, following which occipital cervical fusion was performed.
CONCLUSIONSubluxations and fractures at the odontoid synchondrosis are rare but should be anticipated in young children with risk factors for instability of the cervical spine.
Abnormalities, Multiple ; diagnostic imaging ; Acanthosis Nigricans ; congenital ; Cervical Vertebrae ; diagnostic imaging ; Child ; Craniofacial Abnormalities ; diagnostic imaging ; Female ; Fractures, Bone ; surgery ; Humans ; Neck ; surgery ; Occipital Bone ; surgery ; Odontoid Process ; diagnostic imaging ; pathology ; Skin Abnormalities ; diagnostic imaging ; Surgical Procedures, Operative ; Syndrome ; Tomography, X-Ray Computed ; Uvula ; abnormalities
4.Superior sagittal sinus thrombosis: subtle signs on neuroimaging.
Phua Hwee TANG ; Josiah CHAI ; Yiong Huak CHAN ; Soke Miang CHNG ; C C Tchoyoson LIM
Annals of the Academy of Medicine, Singapore 2008;37(5):397-401
INTRODUCTIONThe aim of this study was to review the clinical, computed tomography (CT) and magnetic resonance imaging (MRI) diagnosis and the frequency of positive neuroimaging findings in patients with cerebral venous thrombosis (CVT) involving the superior sagittal sinus.
MATERIALS AND METHODSA clinical and radiological database of patients with final diagnosis of CVT was compiled from the inpatient hospital information service of a tertiary neurological hospital over 5 years. CT and MRI studies in 22 patients were retrospectively examined for direct signs of venous sinus thrombosis and for complications of CVT. The diagnosis of CVT before and after CT and MRI was reviewed.
RESULTSClinical diagnosis of possible CVT was suspected in only 1 patient. When the diagnosis was not suspected, CT diagnosis was difficult and there was a high false negative rate of 52.6%. MRI fared better, but the false negative rate was still 11%. Directs signs of venous sinus thrombosis such as the triangle sign, empty delta sign on CT and loss of the normal flow voids on MRI, could be retrospectively detected in 57.9%, 100% and 100% of patients respectively. Although 4 patients presented with subarachnoid haemorrhage, these direct signs were present in 3 patients.
CONCLUSIONClinical diagnosis of CVT is rarely suspected before CT and MRI, and although subtle positive signs are often present, these may not be appreciated unless there is a high index of suspicion or image review at multidisciplinary team meetings.
Adult ; Aged ; Aged, 80 and over ; False Negative Reactions ; Female ; Humans ; Magnetic Resonance Imaging ; Male ; Middle Aged ; Retrospective Studies ; Sagittal Sinus Thrombosis ; diagnosis ; diagnostic imaging ; Tomography, X-Ray Computed
5.Magnetic resonance imaging of the fetal central nervous system in Singapore.
Phua Hwee TANG ; Chiou Li ONG ; David STRINGER ; June V K TAN ; George S H YEO
Annals of the Academy of Medicine, Singapore 2009;38(9):774-781
INTRODUCTIONFetal imaging has improved with the development of faster magnetic resonance imaging (MRI) sequences, obviating the requirement for sedation. It is useful in characterising abnormality of the central nervous system in fetuses with abnormal or equivocal antenatal ultrasound findings. We reviewed all cases of fetal brain and spine MRI performed in our institution.
MATERIALS AND METHODSAll cases of fetal central nervous system MRI imaging from May 2006 to December 2008 were retrospectively reviewed, including fetal MRI, postnatal MRI and autopsy findings.
RESULTSThirty-one fetuses were imaged with MRI for evaluation of the central nervous system of which 3 were specifically for spinal evaluation. On fetal MRI, there were 11 normal fetuses (2 with minor ventricular asymmetry), 4 fetuses with minor ventriculomegaly and 16 fetuses with significant abnormalities. Twenty-three fetuses were delivered and 8 were terminated. Fifteen of 23 babies underwent postnatal imaging, 21 had clinical follow-up and 2 were lost to clinical follow-up. Of the 11 fetuses reported as normal on fetal MRI, 3 had additional postnatal findings. A fetus with a megacisterna magna on fetal MRI was diagnosed with a posterior fossa arachnoid cyst on postnatal MRI. One, who had fetal MRI to assess suspected absent inferior cerebellar vermis, had intracranial calcifications from rubella infection. One was diagnosed with cerebro-occular-facio-skeletal (COFS) syndrome postnatally, 1 was lost to follow-up and the rest were discharged well. Seven out of 16 fetuses with significantly abnormal fetal MRI findings had confirmation of the findings on postnatal imaging. Postnatal MRI detected 2 cases of polymicrogyria which were not seen on fetal MRI. Autopsy was available in 1 abortus confirming intrauterine diagnosis of Dandy Walker malformation. A myelomeningocele was clinically obvious in 1 abortus.
CONCLUSIONFetal MRI is a good method of assessing brain and spine abnormalities in utero. However, disorders of neuronal migration remain a challenging diagnostic problem in fetal imaging.
Central Nervous System ; abnormalities ; Fetus ; Humans ; Infant, Newborn ; Magnetic Resonance Imaging ; Malformations of Cortical Development ; diagnosis ; epidemiology ; physiopathology ; Medical Audit ; Retrospective Studies ; Singapore ; epidemiology
6.Improving children's cooperativeness during magnetic resonance imaging using interactive educational animated videos: a prospective, randomised, non-inferiority trial.
Evelyn Gabriela UTAMA ; Seyed Ehsan SAFFARI ; Phua Hwee TANG
Singapore medical journal 2024;65(1):9-15
INTRODUCTION:
A previous prospective, randomised controlled trial showed that animated videos shown to children before magnetic resonance imaging (MRI) scan reduced the proportion of children needing repeated MRI sequences and improved confidence of the children staying still for at least 30 min. Children preferred the interactive video. We hypothesised that the interactive video is non-inferior to showing two videos (regular and interactive) in improving children's cooperativeness during MRI scans.
METHODS:
In this Institutional Review Board-approved prospective, randomised, non-inferiority trial, 558 children aged 3-20 years scheduled for elective MRI scan from June 2017 to March 2019 were randomised into the interactive video only group and combined (regular and interactive) videos group. Children were shown the videos before their scan. Repeated MRI sequences, general anaesthesia (GA) requirement and improvement in confidence of staying still for at least 30 min were assessed.
RESULTS:
In the interactive video group ( n = 277), 86 (31.0%) children needed repeated MRI sequences, two (0.7%) needed GA and the proportion of children who had confidence in staying still for more than 30 min increased by 22.1% after the video. In the combined videos group ( n = 281), 102 (36.3%) children needed repeated MRI sequences, six (2.1%) needed GA and the proportion of children who had confidence in staying still for more than 30 min increased by 23.2% after the videos; the results were not significantly different between the two groups.
CONCLUSION
The interactive video group demonstrated non-inferiority to the combined videos group.
Child
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Humans
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Anesthesia, General
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Magnetic Resonance Imaging
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Prospective Studies
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Simulation Training
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Child, Preschool
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Adolescent
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Young Adult
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Video Recording