220 lines
21 KiB
Markdown
220 lines
21 KiB
Markdown
---
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title: "Mesenteric Vessels"
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docid: "79a4117f-773a-40b3-bdb5-b0195f84e087"
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authors:
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- key: "738b847a-9cda-4cbd-ad90-2d1fdaecd4ca"
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value: "Eric Turner, MD"
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- key: "3c685430-58b7-4676-a18e-dd1c1de70f1a"
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value: "Mark E. Lockhart, MD, MPH"
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- key: "0817f9c9-9bce-42a9-aacc-5d18a3cd66be"
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value: "Daniel Childers, MD"
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breadcrumbs:
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-
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name: "Ultrasound"
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slug: "ultrasound"
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treeNodeId: "e7cdfeb1-bb55-4cca-9854-46cadee515d2"
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-
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name: "Anatomy"
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slug: "anatomy"
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treeNodeId: "d4765014-54f9-4477-8c9c-4b2ae0b82f24"
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-
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name: "Abdomen"
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slug: "abdomen"
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treeNodeId: "1e981810-ddca-4af9-82b9-38d5fdecad76"
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-
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name: "Mesenteric Vessels"
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slug: "mesenteric-vessels"
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treeNodeId: null
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category: "Ultrasound"
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documentVersionId: "c7579afe-f64d-44b5-9ef0-902d777084f6"
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imageCount: 22
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lastUpdated: "05/13/24"
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pageDescription: "Mesenteric Vessels"
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pageKeywords: "Ultrasound, Anatomy, Abdomen, Mesenteric Vessels"
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pageTitle: "Mesenteric Vessels | STATdx"
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enhancedTitle: "Mesenteric Vessels"
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type: "ANATOMY"
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breadcrumbs:
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- "Ultrasound"
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- "Anatomy"
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- "Abdomen"
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- "Mesenteric Vessels"
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---
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# IMAGING ANATOMY
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- ## Internal Contents
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- **Abdominal aorta**
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- Anatomy
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- Continuation of thoracic aorta beginning at diaphragmatic hiatus posterior to diaphragm at approximately level of T12 and coursing slightly left of midline, ultimately terminating in right and left common iliac arteries
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- Ultimately supplies all anatomic structures below level of diaphragm
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- Normal caliber: 15-25 mm
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- Upper (above renal arteries): 22 mm
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- Middle (below renal arteries): 18 mm
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- Lower (immediately above bifurcation): 15 mm
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- Imaging characteristics
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- Best visualized with 5-MHz curved transducer after patient fasting at least 6 hours
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- Best US imaging plane
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- Both transverse and longitudinal
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- Normal peak systolic velocity (PSV)
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- 60-110 cm/s
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- Spectral Doppler waveform
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- Upper: Narrow, well-defined systolic complex with forward flow during diastole
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- Mid: Reduced diastolic flow
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- Distal: Absent diastolic flow, similar to lower limb arteries
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- **Celiac axis**
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- Anatomy
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- Typically arises from abdominal aorta at T12-L1 and courses inferior to median arcuate ligament of diaphragmatic crura, which can compress celiac and cause median arcuate ligament syndrome
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- Normal caliber
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- 7-8 mm
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- ~ 1.25 cm length before bifurcating into left gastric artery and hepatosplenic common origin
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- Extensive variant anatomy can arise from celiac axis
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- Conventional anatomy is 3 branches: Proper hepatic artery, left gastric artery, and splenic artery
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- Supplies foregut
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- Imaging characteristics
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- Best visualized with 5-MHz curved transducer after patient fasting at least 6 hours
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- Best US imaging plane
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- Longitudinal midline: Best for evaluation of celiac axis blood flow
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- Transverse: Best for evaluation of anatomy and detecting branch vessels
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- Normal PSV
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- 92-176 cm/s
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- Spectral Doppler demonstrates low-resistance flow with relatively high diastolic velocities due to constant metabolic activity of liver
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- **Superior mesenteric artery (SMA)**
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- Anatomy
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- Typically arises from abdominal aorta at L1 immediately below origin of celiac axis and courses to left of superior mesenteric vein
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- Left renal vein and 3rd portion of duodenum course posterior to superior mesenteric artery, which can compress and cause Nutcracker syndrome and SMA syndrome, respectively
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- Normal caliber
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- 5-8 mm
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- Main SMA branches
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- Superior pancreaticoduodenal, right colic, middle colic, and ileocolic arteries
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- Hepatic arteries can also arise from SMA, known as either replaced right or replaced left hepatic artery
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- Left-sided ileal and jejunal branches typically present
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- Supplies midgut
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- Imaging characteristics
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- Best visualized with 5-MHz curved transducer after patient fasting at least 6 hours
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- Best US imaging plane
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- Longitudinal midline: Best for evaluation of SMA blood flow
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- Transverse: Useful for identifying short anteriorly directed stump; SMA shows dot-like appearance surrounded by distinctive triangular mantle of fat
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- Normal PSV
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- 97-142 cm/s
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- End-diastolic velocity increases ~ 30-90 min after meal due to vasodilation of mesenteric branches
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- High-resistance flow with low diastolic velocities during fasting due to vasoconstriction
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- Low-resistance flow in postprandial period due to vasodilation from midgut becoming metabolically active
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- If replaced hepatic artery arises from SMA rather than celiac axis, spectral Doppler will demonstrate persistent low-resistance waveform due to constant metabolic activity of liver
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- **Inferior mesenteric artery**
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- Anatomy
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- Typically arises from abdominal aorta at L3 level below renal arteries and courses to left of midline
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- Normal caliber
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- 1-5 mm
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- Main branches
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- Left colic artery, sigmoid arteries, and superior rectal artery
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- Supplies hindgut
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- Imaging characteristics
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- Best visualized with 5-MHz curved transducer after patient fasting at least 6 hours
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- Best imaging plane
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- Transverse following line of aorta; may be difficult to visualize given proximity of surrounding bowel gas
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- Normal PSV
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- 93-189 cm/s
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- End-diastolic velocity increases after meal due to vasodilation of mesenteric branches
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- High-resistance flow with low diastolic velocities during fasting due to vasoconstriction
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a2d778bc-07c9-491b-84ee-954c508bf31d
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## Images
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### Small Intestine, Colon, Rectum, and Anus
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*Graphic shows the vascular supply of the entire small intestine from the superior mesenteric artery (SMA). The small bowel segments are displaced inferiorly. The SMA arises from the anterior abdominal aorta and gives off the inferior pancreaticoduodenal branch that supplies the duodenum and pancreas. Arising from the left side of the SMA are numerous branches to the jejunum and ileum. Jejunal arteries are generally larger and longer than those of the ileum. After a straight course, the arteries form multiple intercommunicating, curvilinear arcades.*
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*Graphic shows the vascular supply of the entire small intestine from the superior mesenteric artery (SMA). The small bowel segments are displaced inferiorly. The SMA arises from the anterior abdominal aorta and gives off the inferior pancreaticoduodenal branch that supplies the duodenum and pancreas. Arising from the left side of the SMA are numerous branches to the jejunum and ileum. Jejunal arteries are generally larger and longer than those of the ileum. After a straight course, the arteries form multiple intercommunicating, curvilinear arcades.*
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*Graphic shows the colon in situ. The transverse colon has been retracted upward to demonstrate the arterial supply of the colon from the superior and inferior mesenteric arteries. The SMA supplies the colon from the appendix through the splenic flexure, and the inferior mesenteric artery (IMA) supplies the descending colon through the rectum. Note the band of smooth muscle (taenia coli) running along the length of the intestine, which terminates in the vermiform appendix; these result in sacculations/haustrations along the colon, giving it a segmented appearance.*
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### Aorta
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*Graphic shows the major mesenteric vessels labeled with overlying bowel and many organs removed for better anatomic visualization. The origins of the major arterial branches from the aorta are well depicted. Many of the arterial origins in this region are in close approximation.*
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*Longitudinal US shows the abdominal aorta. Note the close proximity of the SMA and left renal vein.*
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*Longitudinal spectral Doppler US of the aorta shows a normal aortic triphasic waveform. Rapid systolic acceleration is followed by transient reversal of flow and subsequent anterior diastolic flow.*
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*Transverse US at the level of the aortic bifurcation shows the right and left common iliac arteries, which are usually symmetric in size. Asymmetric size should prompt measurement to detect aneurysmal dilatation.*
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### Peritoneal Cavity
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*Graphic shows the relationship of many of the major intraabdominal organs relative to the vasculature. The deep location of the aortic branches and presence of overlying bowel loops depicts why fasting is important for mesenteric vascular Doppler imaging.*
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### Celiac Axis
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*Transverse US shows the celiac axis. This view depicts the most common appearance of the celiac artery branching pattern to form the common hepatic artery and splenic artery. The lateral hepatic segment can serve as a sonographic window to allow better visualization of the midline vascular structures.*
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*Transverse color Doppler US shows the celiac axis and branch vessels. Normal arterial flow should have nonturbulent laminar flow without aliasing.*
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*Midline sagittal spectral Doppler US shows a normal, low-resistance waveform of the celiac axis due to the liver's constant metabolic activity. In sagittal plane, the celiac artery may have a mildly curved course but should not demonstrate severe angulation, which may be seen in median arcuate ligament syndrome. Occasionally, the celiac axis and SMA may share a common trunk. Note the origin of the left gastric artery from the cranial aspect of the celiac axis.*
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### SMA
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*Transverse US shows the SMA surrounded by a cuff of echogenic fat and lying immediately posterior to the splenic vein, coursing to the portal venous confluence.*
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*Midline sagittal color Doppler US shows the celiac axis and SMA arising from the aorta. Note the homogeneous flow pattern without turbulence or aliasing. The splenic artery courses leftward from the celiac axis but may be partly seen in the sagittal plane, showing the celiac origin due to the severe tortuosity of the splenic artery.*
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*Midline sagittal spectral Doppler US of the SMA depicts high-resistance waveform in a patient who is fasting. Note the transient cessation of flow at end systole.*
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### IMA
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*Midline sagittal US shows the IMA arising from the aorta. The IMA may be difficult to visualize due to overlying bowel gas and its small caliber.*
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*Midline sagittal color Doppler US shows the IMA arising from the aorta. The Doppler flow is initially red toward the transducer, but as the artery dives deeper, the flow turns away from the transducer and is represented by blue color encoding. This finding is common and should not be mistaken for stenosis.*
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*Midline sagittal spectral Doppler US of the IMA shows a normal, high-resistance waveform in a patient who is fasting. Note the relative lack of diastolic flow in the spectral waveform.*
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### Replaced Right Hepatic Artery from SMA
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*Transverse US shows the right hepatic artery arising from the SMA. This is the most common variant hepatic artery supply.*
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*Midline sagittal color Doppler US shows the right hepatic artery arising from the SMA. In this variant, the celiac artery branching usually has a normal pattern at the bifurcation.*
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*Midline sagittal spectral Doppler US shows the persistent diastolic flow in the SMA. This is resulting from the SMA supplying the right hepatic artery, which supplies liver parenchyma. The liver is continuously metabolically active, so there is a lower resistance waveform and persistent diastolic flow.*
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### Postprandial
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*Midline sagittal spectral Doppler postprandial US shows the persistent low-resistance waveform in the celiac axis due to constant metabolic activity from the liver.*
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*Midline sagittal spectral Doppler postprandial US of the SMA shows a low-resistance waveform as the foregut becomes metabolically active. Compare this appearance to the high-resistance fasting SMA waveform seen previously.*
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*Transverse spectral Doppler postprandial US shows the persistent high-resistance waveform in the IMA. The IMA supplies the colon, so early postprandial images remain high resistance.*
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