Images Anatomy For Mri Liver Contrast

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Fig. 26a-c. Arterioportal shunts. HCC following treatment by RF ablation. On the pre-contrast CT scan (a) a well-defined, slightly hypodense nodule (arrow) surrounded by a hypodense rim is demonstrated in segment VII of the right liver lobe. During the arterial phase (b) after contrast medium administration a markedly hyperdense area (arrowhead) is seen near the necrotic lesion. This area becomes isodense in the portal venous phase (c) and represents an APS post RF ablation wm

Shunt Radiopaque Density

Fig. 27a-c. Arterioportal shunts. Patient with liver cirrhosis. On the pre-contrast CT scan (a) no focal lesions are visible. During the arterial phase (b) after contrast medium administration numerous, hyperdense areas (arrowheads) of variable size are appreciable. In the portal venous phase (c) these areas demonstrate rapid contrast medium wash-out resulting in isodensity. Unlike HCC, these lesions are not hypo-dense and there is no indication of a pseudocapsule on the portal venous phase scan

Mri Venous Phase

Fig. 28a-c. Arterioportal shunts. Patient with liver cirrhosis. On the pre-contrast CT scan (a) the liver is homogeneous in density. On the dynamic study, a round, markedly hyperdense lesion (arrowhead) can be detected in the arterial phase (b). Rapid contrast medium wash-out occurs in the portal venous phase (c) but the lesion still appears slightly hyperdense compared to the surrounding liver parenchyma

Mri Contrast Consent Form 2018Arterioportal Shunt Liver

Fig. 29a-d. Arterioportal shunts. On the pre-contrast CT scan (a) no focal lesions are visible. On the arterial phase image (b) after contrast medium administration, several hyperdense lesions (arrowheads) with different shapes are visible in the left lobe of the liver. These areas appear isodense in the portal venous (c) and equilibrium (d) phases

Fig. 29a-d. Arterioportal shunts. On the pre-contrast CT scan (a) no focal lesions are visible. On the arterial phase image (b) after contrast medium administration, several hyperdense lesions (arrowheads) with different shapes are visible in the left lobe of the liver. These areas appear isodense in the portal venous (c) and equilibrium (d) phases

Hepatospecific Liver Contrast MriLiver MetastasisMri Liver Images

Fig. 30a-g. Arterioportal shunts. Same case as demonstrated in Fig. 29. On pre-con-trast T2-weighted (a) and GRE T1-weighted (b) images, diffuse ill-defined areas of signal heterogeneity (arrows) can be seen. On the arterial phase image (c) after injection of Gd-BOPTA, the lesions (arrows) located in the left lobe appear markedly hyperin-tense. Rapid wash-out of contrast agent occurs from these lesions during the portal venous (d) and equilibrium (e) phases. The liver shows homogeneous signal intensity on Tl-weighted (f) and Tl-weighted fat-suppressed (g) images acquired during the hepatobiliary phase. This appearance makes the diagnosis of focal liver lesions unlikely and favours the diagnosis of APS

Diagnostic Imaging For Liver

Fig. 31a-d. THAD, focal sparing and HCC. On the pre-contrast GRE Tl-weighted "out-of-phase" image (a) a triangular area of focal sparing (arrows) is clearly demarcated in an otherwise diffuse steatosis of the liver. Within the focal sparing a round hypointense lesion (arrowhead representing an HCC can be detected. On the arterial phase image (b) after contrast agent administration a THAD reproduces the triangular focal spared area. In the portal venous phase (c) the signal intensity in the focal spared area is similar to that observed in the pre-contrast phase, and the round lesion is not clearly visible. On the corresponding SE T2-weighted image (d) the focal spared area is not delineated, but a round hyperintense lesion (arrow) corresponding to the HCC is recognizable

Fig. 31a-d. THAD, focal sparing and HCC. On the pre-contrast GRE Tl-weighted "out-of-phase" image (a) a triangular area of focal sparing (arrows) is clearly demarcated in an otherwise diffuse steatosis of the liver. Within the focal sparing a round hypointense lesion (arrowhead representing an HCC can be detected. On the arterial phase image (b) after contrast agent administration a THAD reproduces the triangular focal spared area. In the portal venous phase (c) the signal intensity in the focal spared area is similar to that observed in the pre-contrast phase, and the round lesion is not clearly visible. On the corresponding SE T2-weighted image (d) the focal spared area is not delineated, but a round hyperintense lesion (arrow) corresponding to the HCC is recognizable

Mri Liver Dome

Fig. 32a, b. Arteriovenous malformations. On the arterial phase CT image (a), multiple, irregular and tortuous arterial vessels (arrowheads) are visible near the dome of the liver. The left portal branch (asterisk) is malformed, increased in size and shows early opacification. The portal vein is better delineated in the early portal venous phase (b) and further malformed venous vascular structures (arrowheads) are apparent surrounding the left portal branch

Fig. 32a, b. Arteriovenous malformations. On the arterial phase CT image (a), multiple, irregular and tortuous arterial vessels (arrowheads) are visible near the dome of the liver. The left portal branch (asterisk) is malformed, increased in size and shows early opacification. The portal vein is better delineated in the early portal venous phase (b) and further malformed venous vascular structures (arrowheads) are apparent surrounding the left portal branch chemia, and portal hypertension [4, 7]. Frequently, AVMs may occur between the hepatic artery and the hepatic vein, as well as between the hepatic artery and the portal venous system.

On US, AVMs can appear as a nest of tortuous, enlarged, anechoic vessels located usually in one lobe of the liver. Color Doppler US generally demonstrates significant flow with high peak shifts both in arteries and veins, a low arterial resistive index (RI), and increased pulsatility of veins. In late stages of the disease, an arterialized spectral pattern can be seen in the hepatic veins [5].

On unenhanced CT, AVMs generally appear as hypoattenuating areas within the liver. In the arterial and early portal venous phases after contrast media administration these lesions enhance intensely and homogeneously. Thereafter, contrast medium equilibration results in a similar contrast density to that observed in the surrounding vascular structures (Fig. 32).

Typical findings on dynamic MR images of the liver for singular AVMs post-biopsy or surgery include a dilatation of the draining hepatic vein and an early enhancement of the hepatic veins during the arterial phase. Shunts between the hepatic artery and the portal venous system typically lead to increased portal venous pressure and thus to the usual findings of portal hypertension.

MR imaging is a very useful tool for distinguishing AVMs from hemangiomas. Specifically, signal hypointensity on T2-weighted images and the absence of progressive enhancement during the dynamic series of acquisitions after contrast agent administration make the diagnosis of AVM most probable (Fig. 33) [5,8]. On MR angiography, AVMs are found with poor regional demarcation of the lesion, arteriovenous shunting, variable pooling of contrast material in vascular spaces, and no parenchymal blush.

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