Thiru Sudarshan | University of Dundee (original) (raw)
Papers by Thiru Sudarshan
Radiographics, Apr 17, 2015
The celiac axis (CA) and its branches are critically important arteries that supply blood to the ... more The celiac axis (CA) and its branches are critically important arteries that supply blood to the vital solid and hollow abdominal viscera of the foregut. There are many potential anatomic configurations, with up to half the population having a variation from the classic pattern of the CA bifurcating into the hepatosplenic trunk and left gastric artery. These configurations result from permutations in the fusion of the paired dorsal aortas during the first trimester. Despite the short length of the CA, it is affected by a wide range of pathologic conditions, including mesenteric ischemia due to intrinsic occlusion (secondary to causes such as atherosclerosis or thromboembolic events) and extrinsic compression from masses or the median arcuate ligament. Symptoms of mesenteric ischemia are nonspecific and include postprandial abdominal pain and weight loss; thus, the underlying pathologic condition may be found only when being sought specifically. More unusual pathologic conditions include dissection, aneurysms, and vascular malformations. Awareness of the pathologic conditions that affect the CA is important for both diagnostic and interventional radiologists. Early recognition and treatment of CA disease may prevent catastrophic hemorrhage and bowel infarction. Both endovascular and surgical approaches to treatment are greatly enhanced by correct identification of arterial anatomic variants; catheter angiography, computed tomographic angiography, and magnetic resonance angiography can facilitate detection of these variants. Knowledge of the different anatomic permutations is essential to guide endovascular procedures, such as hemorrhage control, transarterial interventional oncologic therapy, and treatment of visceral artery aneurysms. Online supplemental material is available for this article. (©)RSNA, 2015.
Radiographics : a review publication of the Radiological Society of North America, Inc
High-resolution magnetic resonance (MR) imaging performed with a microscopy coil is a robust radi... more High-resolution magnetic resonance (MR) imaging performed with a microscopy coil is a robust radiologic tool for the evaluation of skin lesions. Microscopy-coil MR imaging uses a small surface coil and a 1.5-T or higher MR imaging system. Simple T1- and T2-weighted imaging protocols can be implemented to yield high-quality, high-spatial-resolution images that provide an excellent depiction of dermal anatomy. The primary application of microscopy-coil MR imaging is to delineate the deep margins of skin tumors, thereby providing a preoperative road map for dermatologic surgeons. This information is particularly useful for surgeons who perform Mohs micrographic surgery and in cases of nasofacial neoplasms, where the underlying anatomy is complex. Basal cell carcinoma is the most common nonmelanocytic skin tumor and has a predilection to manifest on the face, where it can be challenging to achieve complete surgical excision while preserving the cosmetic dignity of the patient. Microscop...
PURPOSE/AIM This educational exhibit demonstrates and describes the important imaging characteris... more PURPOSE/AIM This educational exhibit demonstrates and describes the important imaging characteristics of glomus tumors on different imaging modalities . Different subtypes of glomus tumors arising in the head and neck region are discussed, as are their clinical presentation, complications, imaging characteristics and diagnostic pitfalls. CONTENT ORGANIZATION Retrospective 5 year review of CT and MRI database for glomus tumors with best example of each subtype illustrated. Also discussed are the findings of Glomus tympanicum, Glomus jugulare, Glomus caroticum and Glomus vagale on CT, MRI, Ultrasound and angiography. Differential diagnosis for each location and associated pitfalls are also discussed. Associated anatomy, pathology and complications are also highlighted. SUMMARY This educational exhibit will hopefully enable the viewer to increase their knowledge and understanding of this uncommon neoplasm. This will also help understand the different subtypes, their clinical presentati...
PURPOSE/AIM To provide an overview of the radiological anatomy of the mandible and surrounding st... more PURPOSE/AIM To provide an overview of the radiological anatomy of the mandible and surrounding structures To demonstrate the imaging characteristics of benign and malignant mandibular pathologies across different modalities, with pathological correlation CONTENT ORGANIZATION Reports of 1117 patients who had imaging of the mandible between June 2004 and December 2008 were analysed. Imaging of 69 patients with mandibular masses was reviewed with histopathology, revealing a spectrum of pathologies such as complex odontoma, Giant cell tumour, osteoradionecrosis, non-Hodgkins lymphoma, odontogenic keratocyst, ceruminous carcinoma of the temporomandibular joint capsule and ameloblastoma. Imaging findings are presented here with corresponding pathological appearances SUMMARY A sound knowledge of mandibular and perimandibular anatomy and the imaging characteristics of different pathologies is essential in the accurate radiological evaluation of mandibular masses. Establishing a particular d...
Radiographics : a review publication of the Radiological Society of North America, Inc, Jan 17, 2015
The celiac axis (CA) and its branches are critically important arteries that supply blood to the ... more The celiac axis (CA) and its branches are critically important arteries that supply blood to the vital solid and hollow abdominal viscera of the foregut. There are many potential anatomic configurations, with up to half the population having a variation from the classic pattern of the CA bifurcating into the hepatosplenic trunk and left gastric artery. These configurations result from permutations in the fusion of the paired dorsal aortas during the first trimester. Despite the short length of the CA, it is affected by a wide range of pathologic conditions, including mesenteric ischemia due to intrinsic occlusion (secondary to causes such as atherosclerosis or thromboembolic events) and extrinsic compression from masses or the median arcuate ligament. Symptoms of mesenteric ischemia are nonspecific and include postprandial abdominal pain and weight loss; thus, the underlying pathologic condition may be found only when being sought specifically. More unusual pathologic conditions inc...
Clinical radiology, 2014
Chronic lower limb lymphoedema is a debilitating condition that may occur as a primary disorder o... more Chronic lower limb lymphoedema is a debilitating condition that may occur as a primary disorder or secondary to other conditions. Satisfactory visualization of the lymphatic vessels to aid diagnosis and surgical planning has been problematic. Historically, direct lymphography was used to visualize lymphatic vessels, although the significant surgical risks involved led to this being largely abandoned as a technique. Technetium-99m lymphoscintigraphy has been the mainstay of diagnosis for over two decades, but is hampered by inherently poor temporal and spatial resolution and limited anatomical detail. Contrast-enhanced magnetic resonance lymphography (MRL) is a relatively new technique that shows early promise in the evaluation of chronic lymphoedema. This article provides the procedural technique for lower limb MRL at both 1.5 and 3 T, discusses pathophysiology and classifications of lymphoedema, provides an overview of relevant lower limb lymphatic anatomy using MRL imaging, compar...
Otolaryngology - Head and Neck Surgery, 2009
of the CPA, with symptoms mimicking those of acoustic neuromas but with unique MRI findings. Tran... more of the CPA, with symptoms mimicking those of acoustic neuromas but with unique MRI findings. Transtemporal surgical approaches for epidermoid cysts of the CPA allowed for total resection in 17/17 patients, with long-term disease-free incidence of 15/17 or 88.2%.
The Journal of Laryngology & Otology, 2012
To report a case of first branchial arch abnormality and the problems associated with misdiagnosi... more To report a case of first branchial arch abnormality and the problems associated with misdiagnosis. A succinct literature review is included. Teaching hospital in Scotland. A 10-year-old girl presented with localised erythema and swelling in the left parotid region. This was treated with antibiotics and incision and drainage. She re-presented four years later with a history of recurrent discharge. A first branchial arch abnormality was suspected and a magnetic resonance imaging scan arranged. Imaging showed a fluid-filled sinus tract originating adjacent to the anterior wall of the cartilaginous left external auditory canal. The sinus tract was seen to extend anteriorly and inferiorly through the superficial lobe of the left parotid, and to open onto the left cheek lateral to the left masseter. The tract was explored and excised under general anaesthesia, via two separate incisions, with preservation of the facial nerve. The diagnosis of a first branchial arch abnormality is generally based on a high index of clinical suspicion, when a neck swelling is noted in a child. Magnetic resonance imaging is a useful modality for investigation, and helps to delineate the position of the tract and its relationship to the facial nerve.
Clinical Radiology, 2014
A range of disease entities can affect the nasal cavity, often presenting with variable and non-s... more A range of disease entities can affect the nasal cavity, often presenting with variable and non-specific symptoms. There is considerable overlap between the clinical and radiological features of neoplastic and non-neoplastic entities. The nasal cavity is often included in routine imaging of the brain, middle ear, skull base, and paranasal sinuses and should be included as a critical review area. The definitive diagnosis is in most cases confirmed by histopathological analysis. However, this review highlights the role of imaging in identifying nasal cavity disease, eliciting features of aggressive or indolent behaviour, and helping to narrow the differential diagnosis, thus facilitating a systematic approach when reviewing the nasal cavity.
Clinical Radiology, 2012
A wide spectrum of disease entities can affect the external auditory canal (EAC). This review des... more A wide spectrum of disease entities can affect the external auditory canal (EAC). This review describes the normal anatomy of the EAC. Congenital abnormalities, infections, neoplasms, and miscellaneous conditions, such as cholesteatoma and acquired stenosis, are shown with reference to clinical relevance and management. Cases have been histologically confirmed, where relevant. The EAC is frequently imaged d for example, on cross-sectional imaging of the brain d and this review should stimulate radiologists to include it as an important area for review.
Journal of magnetic resonance imaging : JMRI, 2003
To evaluate differences in the magnitude and time course of renal cortical contrast uptake in pat... more To evaluate differences in the magnitude and time course of renal cortical contrast uptake in patients with minimal, moderate, and severe renal artery stenosis (RAS) using contrast-enhanced magnetic resonance renography (CE-MRR). CE-MRR was performed on 56 patients with renovascular disease using a three-dimensional volume interpolated breath-hold examination (VIBE) perfusion sequence. After administration of 2 mL of contrast, nine sequential axial VIBE datasets were acquired: at baseline, 7, 14, 21, 45, 60, 120, 180, and 240 seconds. Aortic peak signal enhancement and cortical peak signal enhancement through the mid portion of each kidney was recorded, along with the time delay between each peak. Each renal artery was subsequently examined using three-dimensional contrast-enhanced MR angiography, and graded as being minimally (0%-30%), moderately (31%-70%), or severely (71%-100%) stenotic. When the data were subdivided by RAS category, the cortical to aortic peak enhancement ratio ...
PURPOSE Previously, lack of aortic spiral flow as determined by MRI has been associated with the ... more PURPOSE Previously, lack of aortic spiral flow as determined by MRI has been associated with the presence and increased severity of renal artery stenosis. The aim of this study was to determine the relationship between the lack of spiral flow in the aorta and progression of renal arterial disease on MR. METHOD AND MATERIALS Prospective study of 40 patients (23 male, 17 female, 34 � 81 years) with clinically suspected renal arterial disease. Baseline and follow up studies (9-12 months, mean-10.2 months) comprising phase contrast flow quantification of the abdominal aorta for spiral flow and standard 3D contrast enhanced renal MRA were performed on at 1.5T system (Siemens Symphony). Renal artery stenosis (RAS) was graded as minimal (61%) stenosis. RESULTS Spiral flow in the aorta was seen in 21 patients(52.5%). 41 renal arteries in the spiral group and 32 renal arteries in the non-spiral group were evaluated. The mean RAS at the baseline and follow up studies was 15% and 17% for spira...
Trials, 2012
Rapid access chest pain clinics have facilitated the early diagnosis and treatment of patients wi... more Rapid access chest pain clinics have facilitated the early diagnosis and treatment of patients with coronary heart disease and angina. Despite this important service provision, coronary heart disease continues to be under-diagnosed and many patients are left untreated and at risk. Recent advances in imaging technology have now led to the widespread use of noninvasive computed tomography, which can be used to measure coronary artery calcium scores and perform coronary angiography in one examination. However, this technology has not been robustly evaluated in its application to the clinic.
Journal of Magnetic Resonance Imaging, 2003
To evaluate differences in the magnitude and time course of renal cortical contrast uptake in pat... more To evaluate differences in the magnitude and time course of renal cortical contrast uptake in patients with minimal, moderate, and severe renal artery stenosis (RAS) using contrast-enhanced magnetic resonance renography (CE-MRR). CE-MRR was performed on 56 patients with renovascular disease using a three-dimensional volume interpolated breath-hold examination (VIBE) perfusion sequence. After administration of 2 mL of contrast, nine sequential axial VIBE datasets were acquired: at baseline, 7, 14, 21, 45, 60, 120, 180, and 240 seconds. Aortic peak signal enhancement and cortical peak signal enhancement through the mid portion of each kidney was recorded, along with the time delay between each peak. Each renal artery was subsequently examined using three-dimensional contrast-enhanced MR angiography, and graded as being minimally (0%-30%), moderately (31%-70%), or severely (71%-100%) stenotic. When the data were subdivided by RAS category, the cortical to aortic peak enhancement ratio (CAPR) reduced with increasing RAS. Further, the cortical to aortic time delay (CATD) increased with increasing RAS. These measurements were statistically significant between patients with minimal and moderate RAS compared to severe RAS CONCLUSION: CE-MRR can assist in the differentiation of patients with minimal or moderate RAS from those with severe RAS.
Clinical Endocrinology, 2013
The significant role of corticosteroids in hypertension and cardiovascular disease highlights the... more The significant role of corticosteroids in hypertension and cardiovascular disease highlights the importance of the adrenal gland in these disorders. The ability to correlate corticosteroid production with adrenal volume offers a novel research tool and intermediate phenotype in cardiovascular disease. The aim of this study was to develop and validate the use of magnetic resonance imaging (MRI) in adrenal volume assessment and investigate whether this associates with corticosteroid production. Twenty normotensive men underwent noncontrast 1·5T MRI scanning of adrenals, measurement of blood pressure and plasma corticosteroids. Left adrenal volume was calculated twice using standard segmentation software by four independent observers with differing levels of clinical expertise and segmentation experience. To optimize this process, adrenal 'phantoms' with known fixed volumes underwent MRI scanning and analysis by two observers. Intra-observer coefficients of repeatability (CoRs) in phantoms ranged from 0·23 to 0·43 ml (interobserver CoR 0·48 ml). In the subject group, mean adrenal volumes were 3·99-5·82 ml with intra-observer CoRs 0·27-1·94 ml. Interobserver variability was 2·73 ml. Segmentation expertise was the main factor affecting variability, with experienced observers having the lowest CoRs; clinical knowledge was a factor when combined with segmentation experience. Mean adrenal volume correlated with plasma glucocorticoids (r = 0·523, P < 0·05) and aldosterone (r = 0·515, P < 0·05) for the most experienced observer only. Measurement of adrenal volume using MRI is challenging; most accurate volumes are achieved using a single observer with both segmentation experience and anatomical knowledge. The data also provide novel preliminary evidence that adrenal gland volume may be associated with plasma corticosteroid concentrations supporting further study of adrenal volume and steroid production across a range of blood pressures.
PURPOSE/AIM To illustrate artefacts that occur in clinical practice, emphasising on those uncommo... more PURPOSE/AIM To illustrate artefacts that occur in clinical practice, emphasising on those uncommon artefacts arising from advanced imaging techniques used on modern scanners. Discuss the underlying physics, reasons for occurrence and the ways of minimising or avoiding artefacts. The diagnostic difficulties that can arise due to artefacts are discussed. CONTENT ORGANIZATION Common artefacts shown include motion, flow, susceptibility, zipper, Gibbs, chemical shift, wrap around, metallic artefacts etc. Uncommon artefacts shown include artefacts due to resonance offset in cardiac SSFP sequences, localised incomplete fat saturation and single phased-array coil element failure. The physical principles involved in the production of artefacts are discussed. The methods of minimising or avoiding the artefacts are discussed. SUMMARY This exhibit shows the various common and uncommon artefacts that appear in MRI and discusses the physics, appearances and ways to avoid them. The examples that a...
Radiographics, Apr 17, 2015
The celiac axis (CA) and its branches are critically important arteries that supply blood to the ... more The celiac axis (CA) and its branches are critically important arteries that supply blood to the vital solid and hollow abdominal viscera of the foregut. There are many potential anatomic configurations, with up to half the population having a variation from the classic pattern of the CA bifurcating into the hepatosplenic trunk and left gastric artery. These configurations result from permutations in the fusion of the paired dorsal aortas during the first trimester. Despite the short length of the CA, it is affected by a wide range of pathologic conditions, including mesenteric ischemia due to intrinsic occlusion (secondary to causes such as atherosclerosis or thromboembolic events) and extrinsic compression from masses or the median arcuate ligament. Symptoms of mesenteric ischemia are nonspecific and include postprandial abdominal pain and weight loss; thus, the underlying pathologic condition may be found only when being sought specifically. More unusual pathologic conditions include dissection, aneurysms, and vascular malformations. Awareness of the pathologic conditions that affect the CA is important for both diagnostic and interventional radiologists. Early recognition and treatment of CA disease may prevent catastrophic hemorrhage and bowel infarction. Both endovascular and surgical approaches to treatment are greatly enhanced by correct identification of arterial anatomic variants; catheter angiography, computed tomographic angiography, and magnetic resonance angiography can facilitate detection of these variants. Knowledge of the different anatomic permutations is essential to guide endovascular procedures, such as hemorrhage control, transarterial interventional oncologic therapy, and treatment of visceral artery aneurysms. Online supplemental material is available for this article. (©)RSNA, 2015.
Radiographics : a review publication of the Radiological Society of North America, Inc
High-resolution magnetic resonance (MR) imaging performed with a microscopy coil is a robust radi... more High-resolution magnetic resonance (MR) imaging performed with a microscopy coil is a robust radiologic tool for the evaluation of skin lesions. Microscopy-coil MR imaging uses a small surface coil and a 1.5-T or higher MR imaging system. Simple T1- and T2-weighted imaging protocols can be implemented to yield high-quality, high-spatial-resolution images that provide an excellent depiction of dermal anatomy. The primary application of microscopy-coil MR imaging is to delineate the deep margins of skin tumors, thereby providing a preoperative road map for dermatologic surgeons. This information is particularly useful for surgeons who perform Mohs micrographic surgery and in cases of nasofacial neoplasms, where the underlying anatomy is complex. Basal cell carcinoma is the most common nonmelanocytic skin tumor and has a predilection to manifest on the face, where it can be challenging to achieve complete surgical excision while preserving the cosmetic dignity of the patient. Microscop...
PURPOSE/AIM This educational exhibit demonstrates and describes the important imaging characteris... more PURPOSE/AIM This educational exhibit demonstrates and describes the important imaging characteristics of glomus tumors on different imaging modalities . Different subtypes of glomus tumors arising in the head and neck region are discussed, as are their clinical presentation, complications, imaging characteristics and diagnostic pitfalls. CONTENT ORGANIZATION Retrospective 5 year review of CT and MRI database for glomus tumors with best example of each subtype illustrated. Also discussed are the findings of Glomus tympanicum, Glomus jugulare, Glomus caroticum and Glomus vagale on CT, MRI, Ultrasound and angiography. Differential diagnosis for each location and associated pitfalls are also discussed. Associated anatomy, pathology and complications are also highlighted. SUMMARY This educational exhibit will hopefully enable the viewer to increase their knowledge and understanding of this uncommon neoplasm. This will also help understand the different subtypes, their clinical presentati...
PURPOSE/AIM To provide an overview of the radiological anatomy of the mandible and surrounding st... more PURPOSE/AIM To provide an overview of the radiological anatomy of the mandible and surrounding structures To demonstrate the imaging characteristics of benign and malignant mandibular pathologies across different modalities, with pathological correlation CONTENT ORGANIZATION Reports of 1117 patients who had imaging of the mandible between June 2004 and December 2008 were analysed. Imaging of 69 patients with mandibular masses was reviewed with histopathology, revealing a spectrum of pathologies such as complex odontoma, Giant cell tumour, osteoradionecrosis, non-Hodgkins lymphoma, odontogenic keratocyst, ceruminous carcinoma of the temporomandibular joint capsule and ameloblastoma. Imaging findings are presented here with corresponding pathological appearances SUMMARY A sound knowledge of mandibular and perimandibular anatomy and the imaging characteristics of different pathologies is essential in the accurate radiological evaluation of mandibular masses. Establishing a particular d...
Radiographics : a review publication of the Radiological Society of North America, Inc, Jan 17, 2015
The celiac axis (CA) and its branches are critically important arteries that supply blood to the ... more The celiac axis (CA) and its branches are critically important arteries that supply blood to the vital solid and hollow abdominal viscera of the foregut. There are many potential anatomic configurations, with up to half the population having a variation from the classic pattern of the CA bifurcating into the hepatosplenic trunk and left gastric artery. These configurations result from permutations in the fusion of the paired dorsal aortas during the first trimester. Despite the short length of the CA, it is affected by a wide range of pathologic conditions, including mesenteric ischemia due to intrinsic occlusion (secondary to causes such as atherosclerosis or thromboembolic events) and extrinsic compression from masses or the median arcuate ligament. Symptoms of mesenteric ischemia are nonspecific and include postprandial abdominal pain and weight loss; thus, the underlying pathologic condition may be found only when being sought specifically. More unusual pathologic conditions inc...
Clinical radiology, 2014
Chronic lower limb lymphoedema is a debilitating condition that may occur as a primary disorder o... more Chronic lower limb lymphoedema is a debilitating condition that may occur as a primary disorder or secondary to other conditions. Satisfactory visualization of the lymphatic vessels to aid diagnosis and surgical planning has been problematic. Historically, direct lymphography was used to visualize lymphatic vessels, although the significant surgical risks involved led to this being largely abandoned as a technique. Technetium-99m lymphoscintigraphy has been the mainstay of diagnosis for over two decades, but is hampered by inherently poor temporal and spatial resolution and limited anatomical detail. Contrast-enhanced magnetic resonance lymphography (MRL) is a relatively new technique that shows early promise in the evaluation of chronic lymphoedema. This article provides the procedural technique for lower limb MRL at both 1.5 and 3 T, discusses pathophysiology and classifications of lymphoedema, provides an overview of relevant lower limb lymphatic anatomy using MRL imaging, compar...
Otolaryngology - Head and Neck Surgery, 2009
of the CPA, with symptoms mimicking those of acoustic neuromas but with unique MRI findings. Tran... more of the CPA, with symptoms mimicking those of acoustic neuromas but with unique MRI findings. Transtemporal surgical approaches for epidermoid cysts of the CPA allowed for total resection in 17/17 patients, with long-term disease-free incidence of 15/17 or 88.2%.
The Journal of Laryngology & Otology, 2012
To report a case of first branchial arch abnormality and the problems associated with misdiagnosi... more To report a case of first branchial arch abnormality and the problems associated with misdiagnosis. A succinct literature review is included. Teaching hospital in Scotland. A 10-year-old girl presented with localised erythema and swelling in the left parotid region. This was treated with antibiotics and incision and drainage. She re-presented four years later with a history of recurrent discharge. A first branchial arch abnormality was suspected and a magnetic resonance imaging scan arranged. Imaging showed a fluid-filled sinus tract originating adjacent to the anterior wall of the cartilaginous left external auditory canal. The sinus tract was seen to extend anteriorly and inferiorly through the superficial lobe of the left parotid, and to open onto the left cheek lateral to the left masseter. The tract was explored and excised under general anaesthesia, via two separate incisions, with preservation of the facial nerve. The diagnosis of a first branchial arch abnormality is generally based on a high index of clinical suspicion, when a neck swelling is noted in a child. Magnetic resonance imaging is a useful modality for investigation, and helps to delineate the position of the tract and its relationship to the facial nerve.
Clinical Radiology, 2014
A range of disease entities can affect the nasal cavity, often presenting with variable and non-s... more A range of disease entities can affect the nasal cavity, often presenting with variable and non-specific symptoms. There is considerable overlap between the clinical and radiological features of neoplastic and non-neoplastic entities. The nasal cavity is often included in routine imaging of the brain, middle ear, skull base, and paranasal sinuses and should be included as a critical review area. The definitive diagnosis is in most cases confirmed by histopathological analysis. However, this review highlights the role of imaging in identifying nasal cavity disease, eliciting features of aggressive or indolent behaviour, and helping to narrow the differential diagnosis, thus facilitating a systematic approach when reviewing the nasal cavity.
Clinical Radiology, 2012
A wide spectrum of disease entities can affect the external auditory canal (EAC). This review des... more A wide spectrum of disease entities can affect the external auditory canal (EAC). This review describes the normal anatomy of the EAC. Congenital abnormalities, infections, neoplasms, and miscellaneous conditions, such as cholesteatoma and acquired stenosis, are shown with reference to clinical relevance and management. Cases have been histologically confirmed, where relevant. The EAC is frequently imaged d for example, on cross-sectional imaging of the brain d and this review should stimulate radiologists to include it as an important area for review.
Journal of magnetic resonance imaging : JMRI, 2003
To evaluate differences in the magnitude and time course of renal cortical contrast uptake in pat... more To evaluate differences in the magnitude and time course of renal cortical contrast uptake in patients with minimal, moderate, and severe renal artery stenosis (RAS) using contrast-enhanced magnetic resonance renography (CE-MRR). CE-MRR was performed on 56 patients with renovascular disease using a three-dimensional volume interpolated breath-hold examination (VIBE) perfusion sequence. After administration of 2 mL of contrast, nine sequential axial VIBE datasets were acquired: at baseline, 7, 14, 21, 45, 60, 120, 180, and 240 seconds. Aortic peak signal enhancement and cortical peak signal enhancement through the mid portion of each kidney was recorded, along with the time delay between each peak. Each renal artery was subsequently examined using three-dimensional contrast-enhanced MR angiography, and graded as being minimally (0%-30%), moderately (31%-70%), or severely (71%-100%) stenotic. When the data were subdivided by RAS category, the cortical to aortic peak enhancement ratio ...
PURPOSE Previously, lack of aortic spiral flow as determined by MRI has been associated with the ... more PURPOSE Previously, lack of aortic spiral flow as determined by MRI has been associated with the presence and increased severity of renal artery stenosis. The aim of this study was to determine the relationship between the lack of spiral flow in the aorta and progression of renal arterial disease on MR. METHOD AND MATERIALS Prospective study of 40 patients (23 male, 17 female, 34 � 81 years) with clinically suspected renal arterial disease. Baseline and follow up studies (9-12 months, mean-10.2 months) comprising phase contrast flow quantification of the abdominal aorta for spiral flow and standard 3D contrast enhanced renal MRA were performed on at 1.5T system (Siemens Symphony). Renal artery stenosis (RAS) was graded as minimal (61%) stenosis. RESULTS Spiral flow in the aorta was seen in 21 patients(52.5%). 41 renal arteries in the spiral group and 32 renal arteries in the non-spiral group were evaluated. The mean RAS at the baseline and follow up studies was 15% and 17% for spira...
Trials, 2012
Rapid access chest pain clinics have facilitated the early diagnosis and treatment of patients wi... more Rapid access chest pain clinics have facilitated the early diagnosis and treatment of patients with coronary heart disease and angina. Despite this important service provision, coronary heart disease continues to be under-diagnosed and many patients are left untreated and at risk. Recent advances in imaging technology have now led to the widespread use of noninvasive computed tomography, which can be used to measure coronary artery calcium scores and perform coronary angiography in one examination. However, this technology has not been robustly evaluated in its application to the clinic.
Journal of Magnetic Resonance Imaging, 2003
To evaluate differences in the magnitude and time course of renal cortical contrast uptake in pat... more To evaluate differences in the magnitude and time course of renal cortical contrast uptake in patients with minimal, moderate, and severe renal artery stenosis (RAS) using contrast-enhanced magnetic resonance renography (CE-MRR). CE-MRR was performed on 56 patients with renovascular disease using a three-dimensional volume interpolated breath-hold examination (VIBE) perfusion sequence. After administration of 2 mL of contrast, nine sequential axial VIBE datasets were acquired: at baseline, 7, 14, 21, 45, 60, 120, 180, and 240 seconds. Aortic peak signal enhancement and cortical peak signal enhancement through the mid portion of each kidney was recorded, along with the time delay between each peak. Each renal artery was subsequently examined using three-dimensional contrast-enhanced MR angiography, and graded as being minimally (0%-30%), moderately (31%-70%), or severely (71%-100%) stenotic. When the data were subdivided by RAS category, the cortical to aortic peak enhancement ratio (CAPR) reduced with increasing RAS. Further, the cortical to aortic time delay (CATD) increased with increasing RAS. These measurements were statistically significant between patients with minimal and moderate RAS compared to severe RAS CONCLUSION: CE-MRR can assist in the differentiation of patients with minimal or moderate RAS from those with severe RAS.
Clinical Endocrinology, 2013
The significant role of corticosteroids in hypertension and cardiovascular disease highlights the... more The significant role of corticosteroids in hypertension and cardiovascular disease highlights the importance of the adrenal gland in these disorders. The ability to correlate corticosteroid production with adrenal volume offers a novel research tool and intermediate phenotype in cardiovascular disease. The aim of this study was to develop and validate the use of magnetic resonance imaging (MRI) in adrenal volume assessment and investigate whether this associates with corticosteroid production. Twenty normotensive men underwent noncontrast 1·5T MRI scanning of adrenals, measurement of blood pressure and plasma corticosteroids. Left adrenal volume was calculated twice using standard segmentation software by four independent observers with differing levels of clinical expertise and segmentation experience. To optimize this process, adrenal 'phantoms' with known fixed volumes underwent MRI scanning and analysis by two observers. Intra-observer coefficients of repeatability (CoRs) in phantoms ranged from 0·23 to 0·43 ml (interobserver CoR 0·48 ml). In the subject group, mean adrenal volumes were 3·99-5·82 ml with intra-observer CoRs 0·27-1·94 ml. Interobserver variability was 2·73 ml. Segmentation expertise was the main factor affecting variability, with experienced observers having the lowest CoRs; clinical knowledge was a factor when combined with segmentation experience. Mean adrenal volume correlated with plasma glucocorticoids (r = 0·523, P < 0·05) and aldosterone (r = 0·515, P < 0·05) for the most experienced observer only. Measurement of adrenal volume using MRI is challenging; most accurate volumes are achieved using a single observer with both segmentation experience and anatomical knowledge. The data also provide novel preliminary evidence that adrenal gland volume may be associated with plasma corticosteroid concentrations supporting further study of adrenal volume and steroid production across a range of blood pressures.
PURPOSE/AIM To illustrate artefacts that occur in clinical practice, emphasising on those uncommo... more PURPOSE/AIM To illustrate artefacts that occur in clinical practice, emphasising on those uncommon artefacts arising from advanced imaging techniques used on modern scanners. Discuss the underlying physics, reasons for occurrence and the ways of minimising or avoiding artefacts. The diagnostic difficulties that can arise due to artefacts are discussed. CONTENT ORGANIZATION Common artefacts shown include motion, flow, susceptibility, zipper, Gibbs, chemical shift, wrap around, metallic artefacts etc. Uncommon artefacts shown include artefacts due to resonance offset in cardiac SSFP sequences, localised incomplete fat saturation and single phased-array coil element failure. The physical principles involved in the production of artefacts are discussed. The methods of minimising or avoiding the artefacts are discussed. SUMMARY This exhibit shows the various common and uncommon artefacts that appear in MRI and discusses the physics, appearances and ways to avoid them. The examples that a...