Radiology - Research Publications
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ItemGlutamate weighted imaging contrast in gliomas with 7 Tesla magnetic resonance imaging(ELSEVIER SCI LTD, 2019-01-01)INTRODUCTION: Diffuse gliomas are incurable malignancies, which undergo inevitable progression and are associated with seizure in 50-90% of cases. Glutamate has the potential to be an important glioma biomarker of survival and local epileptogenicity if it can be accurately quantified noninvasively. METHODS: We applied the glutamate-weighted imaging method GluCEST (glutamate chemical exchange saturation transfer) and single voxel MRS (magnetic resonance spectroscopy) at 7 Telsa (7 T) to patients with gliomas. GluCEST contrast and MRS metabolite concentrations were quantified within the tumour region and peritumoural rim. Clinical variables of tumour aggressiveness (prior adjuvant therapy and previous radiological progression) and epilepsy (any prior seizures, seizure in last month and drug refractory epilepsy) were correlated with respective glutamate concentrations. Images were separated into post-hoc determined patterns and clinical variables were compared across patterns. RESULTS: Ten adult patients with a histo-molecular (n = 9) or radiological (n = 1) diagnosis of grade II-III diffuse glioma were recruited, 40.3 +/- 12.3 years. Increased tumour GluCEST contrast was associated with prior adjuvant therapy (p = .001), and increased peritumoural GluCEST contrast was associated with both recent seizures (p = .038) and drug refractory epilepsy (p = .029). We distinguished two unique GluCEST contrast patterns with distinct clinical and radiological features. MRS glutamate correlated with GluCEST contrast within the peritumoural voxel (R = 0.89, p = .003) and a positive trend existed in the tumour voxel (R = 0.65, p = .113). CONCLUSION: This study supports the role of glutamate in diffuse glioma biology. It further implicates elevated peritumoural glutamate in epileptogenesis and altered tumour glutamate homeostasis in glioma aggressiveness. Given the ability to non-invasively visualise and quantify glutamate, our findings raise the prospect of 7 T GluCEST selecting patients for individualised therapies directed at the glutamate pathway. Larger studies with prospective follow-up are required.
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ItemPatient with ALS with a novel TBK1 mutation, widespread brain involvement, behaviour changes and metabolic dysfunction(BMJ PUBLISHING GROUP, 2019-08-01)
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ItemSignificance of subcentimetre F-FDG PET/CT pulmonary abnormality in patients with known extrapulmonary malignancy.(Department of Biomedical Imaging, University of Malaya, Malaysia, 2010)
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ItemAn intense F-FDG pulmonary microfocus on PET without detectable abnormality on CT: A manifestation of an iatrogenic FDG pulmonary embolus.(Department of Biomedical Imaging, University of Malaya, Malaysia, 2010)An incidental finding of an intense focus of (18)F-Fluorodeoxyglucose (FDG) pulmonary uptake on positron emission tomography (PET) without detectable lesions on computed tomography (CT) is highly suggestive of FDG microembolus. Its microscopic nature means it is undetectable on CT. It is an artefact attributable to (18)F-FDG-tracer contamination at the injection site. This paper reports a case of a 61 year-old lady with a past history of breast carcinoma, in whom follow-up PET/CT images demonstrated an incidental intense FDG pulmonary abnormality. A follow-up PET/CT seven months later demonstrated complete resolution of the abnormality.
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ItemTwo decades of percutaneous transjejunal biliary intervention for benign biliary disease: a review of the intervention nature and complications.(Springer Science and Business Media LLC, 2011-10)OBJECTIVE: To assess outcomes of percutaneous transjejunal biliary intervention (PTJBI) in terms of success and effectiveness in patients with a Roux-en-Y hepaticojejunostomy for benign biliary strictures and stones. METHODS: Clinical and radiographic records of 63 patients with a Roux-en-Y choledochojejunostomy or hepaticojejunostomy for benign disease who underwent at least one PTJBI between 1986 and 2007 were reviewed. Effectiveness was determined by successful access rate, rates of stricture dilatation and/or stone extraction, morbidity, complications and hospitalisation. RESULTS: PTJBI was attempted 494 times. Successful access to the Roux-en-Y was accomplished in 93% of interventions. After access to the Roux-en-Y was granted, all strictures were effectively dilated. Ninety-seven percent of extraction attempts of intrahepatic calculi were successful. The median number of interventions per patient was five. The median interval between interventions was 51.5 weeks (range 2.7-1,279.6 weeks). The early complication rate was 3%. Morbidity, measured in terms of cholangitis episodes was 14%, in 25 out of 63 patients. Mean hospitalisation was 4.1 nights per year. CONCLUSION: PTJBI is safe and effective in treating benign biliary strictures and/or calculi. High success rates and short hospitalisation periods, together with few complications make it a well-accepted and integral part of managing complex biliary problems.
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ItemHip pathology: the diagnostic accuracy of magnetic resonance imaging(BIOMED CENTRAL LTD, 2018-05-29)BACKGROUND: Hip arthroscopy has led to a greater understanding of intra-articular hip pathology. Non-contrast magnetic resonance imaging (MRI) is currently the gold standard in non-invasive imaging diagnosis, with high sensitivity in identifying labral pathology but equivocal results for ligamentum teres damage and chondral defects. The aim of this study is to determine the accuracy of non-contrast MRI for diagnosis of intra-articular hip derangements and identify radiological features that could increase the accuracy of the diagnosis. METHODS: A prospective study of 71 hips on 68 patients undergoing hip arthroscopy was conducted comparing pre-operative analysis of MRI imaging versus an arthroscopic examination. Two musculoskeletal radiologists reported the data independently. All hip arthroscopies were performed by a single surgeon. Patients with MRIs performed within 6 months before hip arthroscopy were included. Outcome measures included observer accuracy identifying ligamentum teres tears, labral lesions, and chondral rim damage. Secondary outcome measures included inter-observer variability and correctly staged ligamentum teres tears. RESULTS: The accuracy of radiology reporting for ligamentum teres tears, labral damage, and chondral rim lesions was 85.92% for each instance. The MRI findings most consistent with labral tears include the presence of linear high signal traversing the articular surface into the labrum, presence of intra-labral fluid signal, and loss of homogenous low signal triangular morphology. Chondral rim damage was difficult to diagnose, but abnormal signal at the chondrolabral junction with partial thickness defects would suggest damage. Ligamentum teres tears are commonly found but poorly graded. Thickening and increased signal suggests synovitis while discontinuity and fraying suggests partial tearing. CONCLUSION: Conventional non-arthrographic MRI offers an accurate non-invasive method to screen patients with symptoms referable to the hip by revealing the presence of labral tears, chondral defects, and ligamentum teres tears/synovitis. This study demonstrates that tears and synovitis of the ligamentum teres as potential sources of hip pain can be accurately identified on conventional non-arthrographic MRI. However, MRI has poor specificity and negative predictive value, and thus, a negative MRI result may warrant further investigation.
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ItemImaging characteristics of nodal metastases in paraganglioma, ameloblastoma and olfactory neuroblastoma: case reports and literature review(BRITISH INST RADIOLOGY, 2016-01-01)Paraganglioma, ameloblastoma and olfactory neuroblastoma are uncommon primary head and neck tumours. When nodal metastases from these tumours occur, they may present later than and with different imaging characteristics compared with squamous cell carcinoma (SCC), demonstrating appearances similar to the primary tumour type rather than features typical of metastatic nodal SCC. We present three cases in which imaging characteristics of nodal metastases in paraganglioma, ameloblastoma and olfactory neuroblastoma mimicked the primary tumour and discuss their implications for clinicoradiological follow-up.
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ItemPlasma Macrophage Migration Inhibitor Factor Is Elevated in Response to Myocardial Ischemia(WILEY-BLACKWELL, 2016-07-01)BACKGROUND: Macrophage migration inhibitory factor (MIF) is a key regulator of inflammatory responses, including in the heart. Plasma MIF is elevated early in the course of acute myocardial infarction. In this study, we hypothesized that plasma MIF may also be increased in acute myocardial ischemia. METHODS AND RESULTS: Patients undergoing cardiac stress test (stress nuclear myocardial perfusion scan or stress echocardiography) were recruited. Twenty-two patients had a stress test indicative of myocardial ischemia and were compared with 62 patients who had a negative stress test. Plasma MIF was measured by ELISA before and after the stress test. MIF was also measured in patients with peripheral arterial occlusive disease before and after exercise causing claudication. Gene and protein expression of MIF was measured in mouse cardiac and skeletal muscle tissue by real-time polymerase chain reaction and western blot, respectively. Plasma MIF was elevated at 5 and 15 minutes after stress (relative to before stress) in patients with a positive test, compared with those with a negative test. In contrast, high-sensitivity troponin T and C-reactive protein were not altered after stress in either group. MIF was not altered after exercise in PAOD patients, despite the occurrence of claudication, suggesting that plasma MIF is not a marker for skeletal muscle ischemia. This may be explained by a lower gene and protein expression of MIF in skeletal muscle than the heart. CONCLUSIONS: Our results suggest that plasma MIF is an early marker for acute myocardial ischemia.
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ItemCauses of hepatic capsular retraction: a pictorial essay(SPRINGER HEIDELBERG, 2016-12-01)UNLABELLED: Hepatic capsular retraction refers to the loss of the normal convex hepatic contour, with the formation of an area of flattening or concavity. This can result from myriad causes, including intrinsic hepatic conditions such as cirrhosis, biliary obstruction, benign tumours, malignancy and infections, as well as extrahepatic causes such as trauma. This article aims to provide familiarity with this wide spectrum of conditions, including mimics of hepatic capsular retraction, by highlighting the anatomic, pathologic and imaging features that help distinguish these entities from one another. TEACHING POINTS: • Hepatic capsular retraction can occur due to various intrinsic or extrinsic hepatic causes. • Hepatic capsular retraction is observed in both benign and malignant conditions. • Recognising associated imaging features can help elicit causes of hepatic capsular retraction.
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ItemRadiological diagnosis of perinephric pathology: pictorial essay 2015(SPRINGEROPEN, 2017-02-01)UNLABELLED: The perinephric space, shaped as an inverted cone, sits between the anterior and posterior renal fasciae. It can play host to a variety of clinical conditions encountered daily in the reporting schedule for a radiologist. Lesions may be classified and diagnosed based on their imaging characteristics, location and distribution. A broad range of differential diagnoses can be attributed to pathology sitting within this space, often without clinical signs or symptoms. An understanding of commonly encountered conditions affecting the perinephric space, along with characteristic imaging findings, can illustrate and often narrow the likely diagnosis. The aim of this essay is to describe commonly encountered neoplastic and non-neoplastic entities involving the perinephric space and to describe their key imaging characteristics. TEACHING POINT: • Despite often a bulky disease, perinephric lymphoma does not produce obstruction or stenosis. • In primarily fatty masses, defects within the renal capsule likely represent angiomyolipoma. • Consider paraganglioma if biopsy is planned; biopsy may lead to catecholamine crisis.