MyMedR

Preoperative high resolution CT and MR imaging in cochlear implantation

Abdullah A, Mahmud MR, Maimunah A, Zulfiqar MA, Saim L, Mazlan R

Ann Acad Med Singap, 2003 Jul;32(4):442-5.

INTRODUCTION: Accurate preoperative imaging of the temporal bone in patients receiving cochlear implants is important. High resolution computed tomography (HRCT) and magnetic resonance (MR) imaging are the 2 preoperative imaging modalities that provide critical information on abnormalities of the otic capsule, pneumatisation of the mastoid, middle ear abnormalities, cochlear ducts patency and presence of cochlear nerve.

MATERIALS AND METHODS: The HRCT and MR imaging in 46 cochlear implant patients in our department were reviewed.

RESULTS: Majority of our patients [34 patients (73.9%)] showed normal HRCT of the temporal bone; 5 (10.9%) patients had labyrinthitis ossificans, 2 (4.3%) had Mondini's abnormality and 2 (4.3%) had middle ear effusion. One patient each had high jugular bulb, hypoplasia of the internal auditory canal and single cochlear cavity, respectively.

CONCLUSION: The above findings contribute significantly to our surgical decisions regarding candidacy for surgery, side selection and surgical technique in cochlear implantation.

Matched MeSH terms: Magnetic Resonance Imaging/methods*

MRI and CT findings of cryptococcal vaginitis

Ranganathan S, Moosa F, Kamarulzaman A, Looi LM

Br J Radiol, 2005 Apr;78(928):353-4.

PMID: 15774599

Cryptococcus neoformans is a yeast like fungus, which is commonly found in bird droppings, especially pigeons. Most cases of cryptococcal infections occur in immunocompromised patients or in those who are on long term immunosuppressant therapies. Cryptococcal infection usually presents as a meningoencephalitis or a pulmonary infection. Skin, bone and genital infections are very rare. We report the second case of vaginal cryptococcossis to be reported in English literature and the first to be imaged with CT and MRI.

Matched MeSH terms: Magnetic Resonance Imaging/methods

Fulltext Tophaceous gout causing atlanto-axial subluxation mimicking rheumatoid arthritis: a case report

Wazir NN, Moorthy V, Amalourde A, Lim HH

J Orthop Surg (Hong Kong), 2005 Aug;13(2):203-6.

PMID: 16131689 DOI: 10.1177/230949900501300220

This is a case report of an extremely rare condition of atlanto-axial subluxation secondary to gouty arthritis, which mimicked rheumatoid arthritis at presentation. Gouty arthritis involving the spine is a rare condition. We highlight a case of gouty arthritis involving the atlanto-axial joint resulting in joint instability, subluxation, and neurological deficit. A 66-year-old obese woman who had a polyarticular disease for the previous 3 years presented with neck pain and progressive neurology. A 2-stage procedure was performed: posterior decompression and occipitocervical fusion followed by further anterior trans-oral decompression. However, after an initial neurological improvement, she succumbed to aspirational pneumonia and septicaemia. Atlanto-axial subluxation caused by gouty arthritis can present in the same way as rheumatoid arthritis. Therefore, the possibility of this as a differential diagnosis should be kept in mind.

Matched MeSH terms: Magnetic Resonance Imaging/methods

Brain white and gray matter anatomy of MRI segmentation based on tissue evaluation

Salih QA, Ramli AR, Mahmud R, Wirza R

MedGenMed, 2005;7(2):1.

PMID: 16369380

Different approaches to gray and white matter measurements in magnetic resonance imaging (MRI) have been studied. For clinical use, the estimated values must be reliable and accurate when, unfortunately, many techniques fail on these criteria in an unrestricted clinical environment. A recent method for tissue clusterization in MRI analysis has the advantage of great simplicity, and it takes the account of partial volume effects. In this study, we will evaluate the intensity of MR sequences known as T1-weighted images in an axial sliced section. Intensity group clustering algorithms are proposed to achieve further diagnosis for brain MRI, which has been hardly studied. Subjective study has been suggested to evaluate the clustering group intensity in order to obtain the best diagnosis as well as better detection for the suspected cases. This technique makes use of image tissue biases of intensity value pixels to provide 2 regions of interest as techniques. Moreover, the original mathematic solution could still be used with a specific set of modern sequences. There are many advantages to generalize the solution, which give far more scope for application and greater accuracy.

Matched MeSH terms: Magnetic Resonance Imaging/methods*

Ethylmalonic encephalopathy-report of two cases

Heberle LC, Al Tawari AA, Ramadan DG, Ibrahim JK

Brain Dev, 2006 Jun;28(5):329-31.

PMID: 16376514

Ethylmalonic encephalopathy is a rare metabolic disease presenting in infancy with developmental delay, acrocyanosis, petechiae, chronic diarrhea and early death. The biochemical characteristics of this autosomal recessive disease are urinary organic acid abnormalities. Recently it has been found to be caused by mutations in the ETHE1 gene, located on Ch19q13. Only about 30 patients have been reported, and we describe two additional cases. The first patient showed a typical clinical picture and biochemical abnormalities, with additional atypical clinical features. Neuroimaging studies showed extensive changes. A new homozygous mutation in exon 3 of the ETHE1 gene was found. The second patient was not investigated genetically; however besides the typical clinical picture and biochemical profile he was found to have cytochrome C oxidase deficiency.

Matched MeSH terms: Magnetic Resonance Imaging/methods

Improving diagnostic quality of MR images through controlled lossy compression using SPIHT

Choong MK, Logeswaran R, Bister M

J Med Syst, 2006 Jun;30(3):139-43.

PMID: 16848126

This paper attempts to improve the diagnostic quality of magnetic resonance (MR) images through application of lossy compression as a noise-reducing filter. The amount of imaging noise present in MR images is compared with the amount of noise introduced by the compression, with particular attention given to the situation where the compression noise is a fraction of the imaging noise. A popular wavelet-based algorithm with good performance, Set Partitioning in Hierarchical Trees (SPIHT), was employed for the lossy compression. Tests were conducted with a number of MR patient images and corresponding phantom images. Different plausible ratios between imaging noise and compression noise (ICR) were considered, and the achievable compression gain through the controlled lossy compression was evaluated. Preliminary results show that at certain ICR's, it becomes virtually impossible to distinguish between the original and compressed-decompressed image. Radiologists presented with a blind test, in certain cases, showed preference to the compressed image rather than the original uncompressed ones, indicating that under controlled circumstances, lossy image compression can be used to improve the diagnostic quality of the MR images.

Matched MeSH terms: Magnetic Resonance Imaging/methods*

Use of non-invasive phase contrast magnetic resonance imaging for estimation of atrial septal defect size and morphology: a comparison with transesophageal echo

Piaw CS, Kiam OT, Rapaee A, Khoon LC, Bang LH, Ling CW, et al.

Cardiovasc Intervent Radiol, 2006 Mar-Apr;29(2):230-4.

PMID: 16252078

Transesophageal echocardiography (TEE) is a trusted method of sizing atrial septal defect (ASD) prior to percutaneous closure but is invasive, uncomfortable, and may carry a small risk of morbidity and mortality. Magnetic resonance imaging (MRI) may be useful non-invasive alternative in such patients who refuse or are unable to tolerate TEE and may provide additional information on the shape of the A0SD.

Matched MeSH terms: Magnetic Resonance Imaging/methods*

Assessment of global and regional left ventricular function using 64-slice multislice computed tomography and 2D echocardiography: a comparison with cardiac magnetic resonance

Annuar BR, Liew CK, Chin SP, Ong TK, Seyfarth MT, Chan WL, et al.

Eur J Radiol, 2008 Jan;65(1):112-9.

PMID: 17466480

To compare the assessment of global and regional left ventricular (LV) function using 64-slice multislice computed tomography (MSCT), 2D echocardiography (2DE) and cardiac magnetic resonance (CMR).

Matched MeSH terms: Magnetic Resonance Imaging/methods*

Magnetic resonance imaging in anterior ectopic anus

Thambidorai CR, Raghu R, Zulfiqar A

Pediatr Surg Int, 2008 Feb;24(2):161-5.

PMID: 17985137

Different criteria have been used in literature to describe the anterior ectopic anus (AEA) anomaly, resulting in uncertainty over its prevalence, association with constipation and definition of the indications for surgery. It has been recently proposed that the term AEA should be restricted to anomalies in which a normal appearing anal orifice is located in the perineum in a more anterior location than normal, with an anal canal of normal calibre that is shown by electrical stimulation to be surrounded by the voluntary external anal sphincter (EAS). We report about four infants, three females and one male, who presented with constipation and had an anteriorly located anal orifice of normal calibre. The anal position index measured clinically was less than 0.34 in all the female patients and 0.44 in the male patient. In preoperative magnetic resonance imaging (MRI), the EAS was distributed all around the circumference of the anal canal, including the ventral aspect of the anal canal, in all the patients. Preoperative MRI documentation of sphincter distribution is recommended for the diagnosis of AEA, as it would help in better definition of its association with constipation and the results of surgical management.

Matched MeSH terms: Magnetic Resonance Imaging/methods*

Fulltext Extramedullary plasmacytoma in the maxillary sinus

Megat Shiraz MA, Jong YH, Primuharsa Putra SH

Singapore Med J, 2008 Nov;49(11):e310-1.

PMID: 19037537

Extramedullary plasmacytoma is a rare malignant plasma cell tumour. We report an extremely aggressive case of extramedullary plasmacytoma of the right maxillary sinus, which had metastasised to the brain and rib. A 56-year-old man presented with recurrent epistaxis and acute anaemia. Nasendoscopy revealed a medialised medial wall of the right maxilla and a mass occupying the whole nasopharynx. Magnetic resonance imaging revealed a right maxillary tumour with extension to the ipsilateral nasal cavity, nasopharynx, right sphenoid and ethmoidal sinuses. There was an extra-axial brain metastasis. There were metastases to the right parietal region and left eighth rib. Histopathology examination of the maxillary mass revealed abundant plasma cells with kappa-chain restriction. He was planned for four cycles of chemotherapy. Unfortunately, in view of the advanced stage of disease, he succumbed to his disease during the first cycle of chemotherapy.

Matched MeSH terms: Magnetic Resonance Imaging/methods

Fulltext Paroxysmal dyskinesia as an unusual and only presentation of subcortical white matter ischaemia: a report of two cases

Norlinah MI, Shahizon AM

Med J Malaysia, 2008 Dec;63(5):410-2.

PMID: 19803303 MyJurnal

Secondary paroxysmal dyskinesias (PxD) have been previously reported in patients with multiple sclerosis, lacunar infarcts, head trauma, metabolic disorders such as hyperglycaemia, hypocalcaemia, migraine and central nervous system (CNS) infections. The causative lesions typically involve the basal ganglia structures, medulla and rarely the spinal cord. We report two patients who presented with paroxysmal dyskinesias as the only manifestation of subcortical white-matter ischaemia. Patient 1 presented with 3-year history of paroxysmal kinesigenic dyskinesia (PKD) and patient 2 with 6-month history of paroxysmal nonkinesigenic dyskinesia (PNKD). All investigations, including CSF oligoclonal bands were negative, except for a brain MRI which showed multiple, non-enhancing subcortical white matter lacunar infarcts. Therefore, subcortical white matter ischaemia should also be included in the differential diagnosis of PxD.

Matched MeSH terms: Magnetic Resonance Imaging/methods

Neurenteric cyst of the cervicothoracic junction: A rare cause of paraparesis in a paediatric patient

Sheaufung S, Taufiq A, Nawawi O, Naicker MS, Waran V

J Clin Neurosci, 2009 Apr;16(4):579-81.

PMID: 19201194 DOI: 10.1016/j.jocn.2008.04.029

Neurenteric cysts are rare congenital spinal masses that result from the dysgenesis of the endoderm tissue during development. We report a 4-year-old girl who presented with an insidious onset of lower limb paraparesis. An MRI scan revealed a cervicothoracic intradural extramedullary neurenteric cyst at the thoracic T1/T2 level, with marked spinal cord compression. No associated spinal dysraphism was noted. The patient underwent laminotomy and excision of the cyst. She recovered her neurological functions completely post-operatively, and at her six-month follow-up she was asymptomatic without any neurological deficits. We will discuss the pathogenesis, clinical presentation, and neuroradiological findings. We emphasize the value of early surgical intervention and long-term follow-up when this type of lesion is only partially excised.

Matched MeSH terms: Magnetic Resonance Imaging/methods

Fulltext Frontal mucocoele secondary to nasal polyposis: an unusual complication

Chew YK, Noorizan Y, Khir A, Brito-Mutunayagam S, Prepageran N

Singapore Med J, 2009 Nov;50(11):e374-5.

PMID: 19960147

The incidence of mucocoeles associated with a non-surgically treated nasal polyposis is rare. We report a rare case of nasal polyposis with asymptomatic frontal mucocoeles in a 28-year-old Malay man who presented with bilateral nasal obstruction with anosmia. Physical examination revealed bilateral grade III nasal polyps causing obstruction. Computed tomography revealed paranasal polyposis with a large polyp extending and expanding the posterior table of the frontal sinus causing erosion and thinning of its wall. Marsupialisation of the mucocoele and nasal polypectomy were done. Endoscopic sinus surgery and marsupialisation should be the treatment of choice for asymptomatic frontal mucocoele.

Matched MeSH terms: Magnetic Resonance Imaging/methods

Fulltext Brain herniation in a neonate

Wong CY, Azizi AB, Shareena I, Rohana J, Boo NY, Isa MR

Singapore Med J, 2010 Oct;51(10):e166-8.

PMID: 21103805

Brain herniation is generally thought to be unlikely to occur in newborns due to the presence of the patent fontanelles and cranial sutures. A review of the literature published from 1993 to 2008 via MEDLINE search revealed no reports on neonatal brain herniation from intracranial tumour. We report a preterm Malay male infant born via elective Caesarean section for antenatally diagnosed intracerebral tumour, which subsequently developed herniation. Cerebral magnetic resonance imaging showed features that were compatible with a large complex intracranial tumour causing mass effect and gross hydrocephalus. Tumour excision was scheduled when the infant was two weeks old. Unfortunately, on the morning of the surgery, he developed signs of brain herniation and had profuse tumour haemorrhage during the attempted excision. Histopathological examination revealed an embryonal tumour, possibly an atypical rhabdoid/teratoid tumour. This case illustrates that intracranial tumours in newborns can herniate and should therefore be closely monitored.

Matched MeSH terms: Magnetic Resonance Imaging/methods

Single image signal-to-noise ratio estimation for magnetic resonance images

Sim KS, Lai MA, Tso CP, Teo CC

J Med Syst, 2011 Feb;35(1):39-48.

PMID: 20703587 DOI: 10.1007/s10916-009-9339-9

A novel technique to quantify the signal-to-noise ratio (SNR) of magnetic resonance images is developed. The image SNR is quantified by estimating the amplitude of the signal spectrum using the autocorrelation function of just one single magnetic resonance image. To test the performance of the quantification, SNR measurement data are fitted to theoretically expected curves. It is shown that the technique can be implemented in a highly efficient way for the magnetic resonance imaging system.

Matched MeSH terms: Magnetic Resonance Imaging/methods*

Predicted cervical canal enlargement and effective cord decompression following expansive laminoplasty using cervical magnetic resonance imaging

Yusof MI, Hassan E, Abdullah S

Surg Radiol Anat, 2011 Mar;33(2):109-15.

PMID: 20658232 DOI: 10.1007/s00276-010-0704-7

Posterior translation of the spinal cord occurs passively following laminoplasty with the presence lordotic spine and availability of a space for the spinal cord to shift. This study is to predict the distance of posterior spinal cord migration after expansive laminoplasty at different cervical levels based on measurement of posterior translation of the spinal cord in normal cervical morphometry.

Matched MeSH terms: Magnetic Resonance Imaging/methods*

Hearing loss after noise exposure

Govindaraju R, Omar R, Rajagopalan R, Norlisah R, Kwan-Hoong N

Auris Nasus Larynx, 2011 Aug;38(4):519-22.

PMID: 21236610 DOI: 10.1016/j.anl.2010.12.006

The higher field strength magnetic resonance imaging (MRI) such as 3 Tesla (T) and above generates noise that has potential detrimental effects on the hearing. Temporary threshold shifts following MRI examination have been reported for MRI with lower field strength. Such effect, however, have not been reported so far for a 3T MRI. We report a case that exemplifies the possible detrimental effects of a 3 T MRI generated noise on the auditory system. Our patient underwent investigation of his chronic backache in a 3 T MRI unit and developed hearing loss and tinnitus post-MRI examination. Hearing assessment was done using pure tone audiogram, distortion product otoacoustic emission (DPOAE) and brainstem electrical response audiometry (BERA) which revealed a unilateral sensorineural hearing loss which recovered within 3 days. However the tinnitus persisted. This is possibly a case of temporary threshold shift following noise exposure. However a sudden sensorineural hearing loss remains the other possibility.

Matched MeSH terms: Magnetic Resonance Imaging/methods*

Fulltext Cardiac imaging in valvular heart disease

Choo WS, Steeds RP

Br J Radiol, 2011 Dec;84 Spec No 3:S245-57.

PMID: 22723532 DOI: 10.1259/bjr/54030257

The aim of this article is to provide a perspective on the relative importance and contribution of different imaging modalities in patients with valvular heart disease. Valvular heart disease is increasing in prevalence across Europe, at a time when the clinical ability of physicians to diagnose and assess severity is declining. Increasing reliance is placed on echocardiography, which is the mainstay of cardiac imaging in valvular heart disease. This article outlines the techniques used in this context and their limitations, identifying areas in which dynamic imaging with cardiovascular magnetic resonance and multislice CT are expanding.

Matched MeSH terms: Magnetic Resonance Imaging/methods

Duplicate internal auditory canals with facial and vestibulocochlear nerve dysfunction

Kew TY, Abdullah A

J Laryngol Otol, 2012 Jan;126(1):66-71.

PMID: 21867589 DOI: 10.1017/S0022215111002258

We report an extremely rare case of duplication of the internal auditory canal associated with dysfunction of both the facial and vestibulocochlear nerves. We also review the literature regarding the integrity of the facial and vestibulocochlear nerves in such cases.

Matched MeSH terms: Magnetic Resonance Imaging/methods

Automatic white matter lesion segmentation using an adaptive outlier detection method

Ong KH, Ramachandram D, Mandava R, Shuaib IL

Magn Reson Imaging, 2012 Jul;30(6):807-23.

PMID: 22578927 DOI: 10.1016/j.mri.2012.01.007

White matter (WM) lesions are diffuse WM abnormalities that appear as hyperintense (bright) regions in cranial magnetic resonance imaging (MRI). WM lesions are often observed in older populations and are important indicators of stroke, multiple sclerosis, dementia and other brain-related disorders. In this paper, a new automated method for WM lesions segmentation is presented. In the proposed method, the presence of WM lesions is detected as outliers in the intensity distribution of the fluid-attenuated inversion recovery (FLAIR) MR images using an adaptive outlier detection approach. Outliers are detected using a novel adaptive trimmed mean algorithm and box-whisker plot. In addition, pre- and postprocessing steps are implemented to reduce false positives attributed to MRI artifacts commonly observed in FLAIR sequences. The approach is validated using the cranial MRI sequences of 38 subjects. A significant correlation (R=0.9641, P value=3.12×10(-3)) is observed between the automated approach and manual segmentation by radiologist. The accuracy of the proposed approach was further validated by comparing the lesion volumes computed using the automated approach and lesions manually segmented by an expert radiologist. Finally, the proposed approach is compared against leading lesion segmentation algorithms using a benchmark dataset.

Matched MeSH terms: Magnetic Resonance Imaging/methods*

Displaying publications 1 - 20 of 116 in total