E 71 Examination

,<u Abdominal Vessels n Scan planes:

• Upper abdominal transverse scan (see p. 22)

• Upper abdominal longitudinal scan (see p. 29)

• Supplementary scan planes n Sonographic anatomy and normal findings:

- The aorta runs anterior and slightly to the left of the vertebral column, appearing as a smooth, throbbing, largely anechoic vascular band. It gives off parietal and visceral branches before dividing into the common iliac arteries just below the umbilicus.

- The aortic wall presents a three-layered structure: two echogenic zones separated by a hypoechoic zone (the two inner layers represent the thickness of the intima and media, respectively).

• Inferior vena cava (see Fig. 35), p. 28; Fig. 476, p. 324): The inferior vena cava ascends to the right of and parallel to the aorta, its parietal and visceral tributaries (renal veins) corresponding to the aortic branches. It has a "soft" consis-

Branches The Celiac Trunk

188 Fig. 247 Parietal and visceral branches of the aorta Schmidt, Ultrasound © 2007 Thieme

All rights reserved. Usage subject to terms and conditions of license.

Celiac Trunk

Fig. 248a, b Upper abdominal longitudinal scan of the celiac trunk. CT = celiac trunk, SMA = superior mesenteric artery, AO = aorta, L = liver

b

1 \

CT/iJ f:

ÉH

M

Fig. 248a, b Upper abdominal longitudinal scan of the celiac trunk. CT = celiac trunk, SMA = superior mesenteric artery, AO = aorta, L = liver

Cl ^

a

AO ^r b

1 |\WI 1 i t

[§l 1

af s« RA Y'

HA SA

AO' ,

c c

Fig. 249a-d a, b Upper abdominal longitudinal scan of the aorta (AO), the celiac trunk (TR), and the superior mesenteric artery (SMA) with the first jejunal branch (arrow). Horizontal arrows: lower esophagus. D = shank of the muscular diaphragm c, d Upper abdominal transverse scan of the celiac trank (TR), the common hepatic artery (HA) and the splenic artery (SA), and the branch of the renal arteries (RA). AO = aorta, LRV = left renal vein, crossing the aorta tency, and its caliber can be seen to fluctuate with respirations. It contains no internal echoes and shows typical double pulsations.

• Portal vein (Figs. 250 and 251 ): The portal vein is formed by the confluence of the visceral veins. It passes behind the head of the pancreas to the porta hepa-tis, where it divides into a right and left main branch that undergo further arborization in a capillary system.

• Venous confluence (Figs. 250 and 252): The venous confluence is located behind the head of the pancreas, appearing sonographically as an elliptical expansion of the vena cava. It is formed by the superior mesenteric vein, the inferior

Ultrasound Left Liver

Fig. 251a, b Course of the portal vein. a Longitudinal scan: the portal vein in its longitudinal axis (red) behind the common bile duct (CBD) and the hepatic artery (red spot). VC = vena cava b Oblique scan: T-shaped division of the portal vein (VP) into the right and left main branches. A = hepatic artery, VC = caval vein

Fig. 251a, b Course of the portal vein. a Longitudinal scan: the portal vein in its longitudinal axis (red) behind the common bile duct (CBD) and the hepatic artery (red spot). VC = vena cava b Oblique scan: T-shaped division of the portal vein (VP) into the right and left main branches. A = hepatic artery, VC = caval vein mesenteric vein (which usually empties into the splenic vein), the left gastric vein, and the splenic vein. n Scanning tips:

• Look for respiration-dependent volume changes in the venous system (inspiratory collapse of the vena cava; end-inspiratory expansion of the portal vein >2 mm or 50-100%).

190 • Compress and push aside overlying gas-filled loops of bowel.

Spot The Liver Sonographic

Fig. 252a, b Venous vessels in the upper abdomen. a Upper transverse scan. AO = aorta, P = pancreas, SV = splenic vein, L = liver, VC = vena cava, LRV = left renal vein, crossing the aorta b Upper abdominal oblique scan: right (R), middle (M), and left (L) hepatic veins confluenting into the inferior caval vein (VC)

Fig. 252a, b Venous vessels in the upper abdomen. a Upper transverse scan. AO = aorta, P = pancreas, SV = splenic vein, L = liver, VC = vena cava, LRV = left renal vein, crossing the aorta b Upper abdominal oblique scan: right (R), middle (M), and left (L) hepatic veins confluenting into the inferior caval vein (VC)

n Scan planes: The scan planes should conform to the anatomical course of the imaged vessels. n Sonographic anatomy and normal findings:

• As in the abdomen, typical differences are noted between the arteries and veins of the peripheral vascular system (pulsations, caliber changes with respirations)

• The anatomical relationships of the principal lower-extremity vessels are shown in Fig. 253 and in Figs 286 and 287 on p. 210.

• The veins of the lower extremity generally run posterior to the arteries.

• Arteries are almost incompressible, whereas veins are highly compressible in response to transducer pressure.

n Scanning protocol:

• Supine position: The lower leg veins are scanned with the leg hanging over the edge of the table. The popliteal vessels are scanned in the prone position (where the popliteal vein is closer to the transducer and the artery is farther away).

• Begin the examination with transverse survey scans, then scan longitudinally in planes that conform to the course of the vessels.

• Standard scans may be supplemented by CDS (p. 7) to detect peripheral flow (floating thrombi?), collateral channels, recanalization processes, or pelvic venous thrombi.

n Scanning tips:

• Carefully controlled transducer pressure will reduce scattering artifacts.

• Gentle transducer movements make it easier to detect arterial pulsations.

• Slipping of the transducer under pressure leads to errors of interpretation; the incompressible artery should therefore be defined along with the vein whenever possible.

• The probe should be applied very carefully in the popliteal fossa because the popliteal vein is subcutaneous and easily compressible, and cannot be visualized when in a normal state.

• The vessels at the pelvic level are easier to define when the bladder is slightly distended.

Lower Leg Veins Anatomy
Fig. 253 Vascular topography of the right upper leg

n Aorta and arteries: The intra- and retroperitoneal vessels provide important landmarks for localization and anatomical orientation (just as the neck vessels aid in examination of the thyroid gland and lymph nodes).

• Changes due to atherosclerosis: Diseases of the aorta and arteries most commonly result from atherosclerosis, which leads to expansion, narrowing, and occlusion of the affected vessel (see p. 197).

• Hemodynamic changes:

- Detectable only by Doppler scanning or CDS (see p. 7). The B-mode image reflects only morphological changes.

- Detection of stenoses: Stenotic lesions can be described morphologically by spectral analysis and analyzed semiquantitatively by the measurement of flow velocities (see Table 30 and Fig. 254).

Table 30 ■ Normal values for flow velocities and Doppler indices

Vessel

PI

RI

Vmax (cm/s)

Vmin (cm/s)

Abdominal aorta

2-6

50-120

Common femoral artery

5-10

100

Popliteal artery

6-12

Renal artery

0.6-0.8

60-180

30

Celiac trunk

0.6-0.8

100-240

Superior mesenteric artery

0.75-0.9

120-220

Inferior mesenteric artery

0.8-0.9

100-150

PI = pulsatility index (for peripheral arteries), RI = resistance index (for parenchymal arteries, e.g., the renal arteries)

PI = pulsatility index (for peripheral arteries), RI = resistance index (for parenchymal arteries, e.g., the renal arteries)

Peripheral Arterial Stenosis Waveforms

Fig. 254 Pulsatility index (PI) and velocity waveform versus degree of stenosis in normal and abnormal extremity waveforms. The PI is calculated by dividing the difference between the maximum forward and reverse flow velocities (h) by the mean value of the flow velocity (Vm) (from Neuerburg-Heusler D, Hennerici M. Gefässdiagnostik mit Ultraschall. Thieme, 1995)

Fig. 254 Pulsatility index (PI) and velocity waveform versus degree of stenosis in normal and abnormal extremity waveforms. The PI is calculated by dividing the difference between the maximum forward and reverse flow velocities (h) by the mean value of the flow velocity (Vm) (from Neuerburg-Heusler D, Hennerici M. Gefässdiagnostik mit Ultraschall. Thieme, 1995)

• Classification of findings:

- By location: see Table 32, p. 201. n Vena cava and peripheral veins:

• Veins are important sonographically both as landmarks for anatomical orientation and as potential sites of pathologic change. Thrombosis has the greatest clinical significance.

• Classification of findings: see Table 34, p. 208.

Was this article helpful?

0 -1
Supplements For Diabetics

Supplements For Diabetics

All you need is a proper diet of fresh fruits and vegetables and get plenty of exercise and you'll be fine. Ever heard those words from your doctor? If that's all heshe recommends then you're missing out an important ingredient for health that he's not telling you. Fact is that you can adhere to the strictest diet, watch everything you eat and get the exercise of amarathon runner and still come down with diabetic complications. Diet, exercise and standard drug treatments simply aren't enough to help keep your diabetes under control.

Get My Free Ebook


Post a comment