MRI changes in visceral fat in Crohn’s Disease

Crohn’s Disease (CD) is a chronic inflammatory disease of the gastrointestinal tract affecting 115,000 people in the UK alone. As a chronic illness, CD management requires a stepwise escalation of treatment measures tethered with constant monitoring of the disease activity levels and progression. Hence, non-invasive disease activity assessment methods form an essential part of the treatment process. Endoscopy is considered to be the traditional method for CD diagnosis and disease activity assessment which is invasive and may be uncomfortable for patients. As traditional MRI-based disease assessment methods rely on intravenous gadolinium for contrast enhancement, CD patients typically undergo repeated exposure to gadolinium administration which adds cost and carries the risk of nephrogenic systemic fibrosis, allergic reaction, and long-term brain deposition following repeated use. Hence, the development of contrast-free MRI-based disease activity metrics eliminates the risks associated with gadolinium and allows for a more frequent assessment of the disease progression. However, all developed cross-sectional CD activity metrics so far rely on a visual assessment by radiologists which can be subjective and time-consuming. The aim of this thesis is to examine established radiological hallmarks of CD and employ MRI imaging sequences along with image processing techniques to generate objective and quantitative disease activity measurements. The first part of this thesis investigates visceral fat hypertrophy also known as fat wrapping which refers to an abnormal growth of the mesenteric fat to partially cover the small or large intestine. While fat wrapping has been established as a characteristic of CD, the complex nature of visceral fat hinders detailed analysis of the effect of fat wrapping. Hence, an automated abdominal fat segmentation algorithm was developed to generate an objective measure of abdominal fat volumes which was used to study the differences in visceral fat revealing significant differences between CD patients and healthy volunteers. The second part of the thesis examines mesenteric blood flow in CD patients. CD is known to be associated with hypervascularity of the mesentery, including vascular dilation and wide spacing of the vasa recta. The arteries supply the small bowel branch to a series of intestinal arteries within the mesentery. A second algorithm was developed to automatically trace abdominal vessels on a time-of-flight MRA scans and measure the number of vessels’ branching points which also revealed significant differences between CD patients and HVs. This research has demonstrated the potential for MRI and image processing techniques to provide objective and quantitative measurements of disease activity in CD. The development of automated algorithms for abdominal fat segmentation and vessel tracing allows for a more accurate and efficient assessment of key radiological hallmarks of CD which are often overlooked. These techniques have the potential to improve the management of CD by providing non-invasive and more frequent assessments of disease activity and progression, without the risks associated with traditional contrast-enhanced methods

MRI changes in visceral fat in Crohn’s Disease

Crohn’s Disease (CD) is a chronic inflammatory disease of the gastrointestinal tract affecting 115,000 people in the UK alone. As a chronic illness, CD management requires a stepwise escalation of treatment measures tethered with constant monitoring of the disease activity levels and progression. Hence, non-invasive disease activity assessment methods form an essential part of the treatment process. Endoscopy is considered to be the traditional method for CD diagnosis and disease activity assessment which is invasive and may be uncomfortable for patients. As traditional MRI-based disease assessment methods rely on intravenous gadolinium for contrast enhancement, CD patients typically undergo repeated exposure to gadolinium administration which adds cost and carries the risk of nephrogenic systemic fibrosis, allergic reaction, and long-term brain deposition following repeated use. Hence, the development of contrast-free MRI-based disease activity metrics eliminates the risks associated with gadolinium and allows for a more frequent assessment of the disease progression. However, all developed cross-sectional CD activity metrics so far rely on a visual assessment by radiologists which can be subjective and time-consuming. The aim of this thesis is to examine established radiological hallmarks of CD and employ MRI imaging sequences along with image processing techniques to generate objective and quantitative disease activity measurements. The first part of this thesis investigates visceral fat hypertrophy also known as fat wrapping which refers to an abnormal growth of the mesenteric fat to partially cover the small or large intestine. While fat wrapping has been established as a characteristic of CD, the complex nature of visceral fat hinders detailed analysis of the effect of fat wrapping. Hence, an automated abdominal fat segmentation algorithm was developed to generate an objective measure of abdominal fat volumes which was used to study the differences in visceral fat revealing significant differences between CD patients and healthy volunteers. The second part of the thesis examines mesenteric blood flow in CD patients. CD is known to be associated with hypervascularity of the mesentery, including vascular dilation and wide spacing of the vasa recta. The arteries supply the small bowel branch to a series of intestinal arteries within the mesentery. A second algorithm was developed to automatically trace abdominal vessels on a time-of-flight MRA scans and measure the number of vessels’ branching points which also revealed significant differences between CD patients and HVs. This research has demonstrated the potential for MRI and image processing techniques to provide objective and quantitative measurements of disease activity in CD. The development of automated algorithms for abdominal fat segmentation and vessel tracing allows for a more accurate and efficient assessment of key radiological hallmarks of CD which are often overlooked. These techniques have the potential to improve the management of CD by providing non-invasive and more frequent assessments of disease activity and progression, without the risks associated with traditional contrast-enhanced methods