Hepatocarcinoma fibrolamelar un tumor de adultos jóvenes poco frecuente. . Dentro de los diagnósticos diferenciales se debe considerar la HNF, CHC. Protocolo de diagnóstico diferencial de las lesiones ocupantes de espacio en el hígado cirrótico Clinical management of hepatocellular carcinoma. Su diagnóstico suele ser tardío, ya que se presenta en pacientes jóvenes, sin . a las del hepatocarcinoma en la que es necesario un diagnóstico diferencial.
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The characterization of focal liver lesions is very important. Magnetic resonance imaging is considered the best imaging method for evaluating such lesions, but does not allow for the diagnosis in all cases. The use of hepatobiliary contrast agents increases the diagnostic accuracy of magnetic resonance imaging and reduces the number of non-specific liver lesions.
The main indications for the method include: The use of hepatobiliary contrast agents may reduce the need for invasive diagnostic procedures and further investigations with other imaging methods, besides the need for imaging follow-up. The characterization of focal liver lesions has a great clinical relevance.
Magnetic resonance imaging MRI with intravenous contrast injection extracellular gadolinium-based contras media commonly utilized in the radiological practice is considered the best imaging method in the evaluation of such lesions. However, MRI does not allow for the diagnosis in all cases whose etiology remains undetermined. The utilization of hepatobiliary contrast agents increases the MRI accuracy, reducing the necessity of invasive diagnostic procedures intended to clarify the diagnosis of nonspecific lesions 12.
The currently available hepatocyte-selective contrast media are the following: Such contrast agents are absorbed by hepatocytes via OATP1 transporter polypeptide adenosintriphosphate-dependent organic anion transporterthe same as the bilirubin transporter. A fraction of hepatobiliary contrast agent is excreted by cMOAT into the biliary canaliculi multispecific canalicular organic anion transporter 1.
Thus, the lesions enhancement in the hepatobiliary phase depends upon the expression and activity of such transporters, determining characteristic diagnoztico patterns depending on the presence or absence of functioning hepatocytes. In the hepatobiliary phase, the healthy liver is evenly enhanced, becoming hyperintense; the contrast agent uptake by the biliary tract occurs progressively, and the blood vessels become hyperintense as compared with the liver parenchyma as the contrast medium is no hepatoczrcinoma in the vascular compartment.
Contrast uptake is also observed in focal liver lesions with functioning hepatocytes 1. Additionally, hepatobiliary contrast agents allow for evaluating the biliary tract 1 – 3.
The usual dynamic study with arterial, hepahocarcinoma and delayed phases is also performed with such contrast agents.
So, hepatobiliary contrast agents combine the pharmacodynamic features of extracellular gadolinium usual dynamic study with the delayed hepatobiliary phase, adding functional information to the MRI study and enhancing its diagnostic accuracy 124 – 6. The pharmacokinetics and doses of gadobenate dimeglumine and gadoxetic acid are different.
Consequently, the hepatobiliary phase acquisition time is diagnostlco for each type hepqtocarcinoma contrast agent and should be obtained minutes after gadobenate dimeglumine administration ranging between 1 and 3 hoursand 20 minutes after gadoxetic acid administration ranging between 10 and minutes 1.
The doses recommended for intravenous injection of such contrast agents are also different, corresponding to 0.
HEPATOCARCINOMA DE CÈLULAS CLARAS by marta garnica ureña on Prezi
As the gadoxetic acid dose corresponds to one quarter of the habitual extracellular gadolinium dose, the arterial phase acquisition time is critical, requiring temporal precision methods, such as real time visualization of the contrast progression through the arterial system, diferenciial the success in this phase acquisition.
On the other hand, the enhancement in the dfierencial phase is prolonged, allowing for acquisition of images with better spatial resolution, as well as its repetition in case of imaging artifacts 4.
As gadobenate dimeglumine is utilized, it is recommended that the MRI study be performed as usual, including the dynamic study up to the delayed phase; then the procedure be interrupted and the patient returns after minutes for acquisition of the hepatobiliary phase. As gadoxetic acid is utilized, the hepatobiliary phase occurs in diferencisl minutes, so it is recommended that the order of sequences acquisition be changed in order to optimize the acquisition time.
Initially, the T1-weigthed sequences in-phase, out-ofphase and with fat saturation are performed.
As necessary, heavily T2-weighted cholangiographic images should also be acquired before the contrast injection, since hepatobiliary contrast agents are excreted by the biliary tract and can shorten the T2-relaxation time.
Subsequently, gadoxetic acid is intravenously injected and the dynamic study arterial, portal and delayed phases is hepatcoarcinoma. Diffusion- and T2-weighted sequences may be acquired after hepatobiliary contrast agent injection, considering that there is no significant interference effect. Finally, the hepatobiliary phase is acquired 20 minutes after gadoxetic acid administration 14. The use of hepatobiliary contrast agents requires some care.
Focal liver lesions enhancement may be less intense during the dynamic study, particularly in the arterial phase, because the recommended dose of gadoxetic acid is lower than the habitual extracellular gadolinium diffrencial 5. Additionally, patients with advanced cirrhosis may present less hepatobiliary contrast uptake as a result from liver dysfunction. Patients with advanced liver and kidney diseases alternatively compensate the contrast agents clearance by renal or biliary excretion, respectively.
Patients with cirrhosis Child A or B do not present any significant alteration in the total clearance of hepatobiliary contrast agents; but in cirrhosis Child C, there is a decreased total clearance and increased half life, with compensatory increase of renal excretion 8. Adverse effects of hepatobiliary contrast agents rarely occur and, if present, are similar to the ones reported in the use of extra-cellular gadolinium.
Main indications for hepatobiliary contrast include differentiation between focal nodular hyperplasia FNH and adenoma, characterization of hepatocelular carcinomas HCCsdetection of small liver metastasis, assessment of biliary anatomy, and characterization of postoperative biliary fistulas. The imaging characterization of benign and malignant liver lesions is very important.
Benign liver lesions are frequently found, even in patients with known neoplasia. The most frequent differential diagnoses for hypervascular lesions in patients with no hepatopathy include hemangioma, FNH and adenoma. Hemangiomas generally present typical imaging findings and are easily diagnosed by computed tomography or MRI with extracellular gadolinium contrast agent.
However, the differentiation between FNH and adenoma is not always easy at conventional MRI, because both conditions may appear as nonspecific hypervascular lesions, generating anguish for the patient and challenging the physician, in addition to the cost and patient’s anxiety with repeated examinations. FNH is a benign lesion that does not require any intervention, while adenoma presents risk for malignization, necrosis and bleeding which might require emergency surgery. Hepatobiliary contrast allow for the differentiation between FNH and adenoma in most cases, even in those of small lesions.
The typical FNH presents with septa and lobulated or microlobulated borders, with intermediate signal intensity on T1- and T2-weighted sequences, low lesion-organ contrast and homogeneous arterial contrast uptake, with decay in the subsequent phases, becoming isointense to the adjacent liver parenchyma.
The presence of central scar markedly hyperintense on T2-weighted and hypointense on T1-weighted sequences, with no contrast uptake in the arterial phase and late contrast uptake is typical. However, in some cases, especially those of small lesions without central scarone cannot differentiate between FNH and adenoma due to overlapping imaging findings 14. FNH presents greater density of functioning hepatocytes than a healthy liver parenchyma, in association with abnormal bile ducts which do not communicate with greater bile ducts, with consequential slower biliary excretion as compared with the surrounding liver.
Female, year-old patients presenting with liver steatosis and multiple, well-defined focal hypervascular lesions, with intermediate signal intensity on T2- weighted sequence, with poor lesion-organ contrast-enhancement. However, the presence of intralesional fat was detected on out-of-phase T1-weighted sequence.
The presence of intralesional fat is not usually found in FNH and suggests the diagnosis of adenoma — adenomatosis, in the present case —, with a very different prognosis and approach. On the other hand, the lesions showed homogeneous hepatobiliary contrast uptake, hence the highest likelihood of the diagnosis of multiple FNHs. Female, year-old, asymptomatic patient presenting with a hypervascular liver nodule to be clarified, without intralesional fat and without central scar.
Homogeneous hepatobiliary contrast uptake indicates the diagnosis of FNH. Adenomas are well defined, homogeneous or heterogeneous lesions. The largest ones tend to present signal heterogeneity, with mild to moderate hypersignal on T2-weighted, hyposignal on T1-weighted sequences, homogeneous or heterogeneous arterial contrast-enhancement, late washout, and possible development of capsule Adenomas are composed of hepatocytes containing glycogen and lipids surrounded by a capsule.
Although containing functioning hepatocytes, there is a lack of biliary ducts resulting in deficiency in bilirubin and hepatobiliary contrast excretion.
Additionally, adenomas present smaller expression of membrane transporters such as OATP1 12. Thus, in the hepatobiliary phase, most adenomas are hypointense in relation to the surrounding parenchyma Figure 3. Rarely, there is hepatobiliary contrast uptake by adenomas and, in cases where it occurs, such an uptake tends to be preferentially peripheral in the hepatobiliary phase 124. Female, year-old patient undergoing follow-up for metastatic gastrointestinal stromal tumor, with liver nodules to be clarified.
The smallest lesion arrowheads presents subtle hypersignal on T2-weighted and marked signal loss on out-of-phase T1-weighted sequence caused by the presence of intralesional fat. No hepatobiliary contrast uptake is observed.
The presence of intralesional fat and the absence of hepatobiliary diagnoetico uptake indicate diiferencial probable diagnosis of adenoma. The largest lesion arrows presents high signal intensity on T2-weighted, hyposignal on t1-weighted sequence, and nodular, peripheral and discontinuous uptake in the arterial-phase, and no hepatobiliary contrast uptake that is a typical hemangioma behavior.
Hemangiomas do not contain functioning hepatocytes so uptake of this contrast medium is not observed. Also, in the delayed-phase, the fill-in pattern is not observed, which might occur with the utilization of hepatobiliary contrast agent.
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Hemangiomas normally have a typical presentation at MRI with extracellular contrast and are not an indication for investigation with hepatobiliary contrast.
At conventional MRI, hemangiomas present marked hypersignal on T2-weighted, hyposignal on T1-weighted sequences, discontinuous, nodular, peripheral contrast enhancement in the arterial phase, tending to centripetal fill-in by the contrast agent in the hepatovarcinoma phases 13 However, considering that hemangiomas are common lesions, they will be frequently present on images acquired with hepatobiliary contrast for several reasons.
Hemangiomas present the same imaging findings at dynamic studies with hepatobiliary contrast; however, in the delayed phase, as the hepatobiliary contrast medium is leaving the interstitium and entering into the functioning hepatocytes, the hemangioma fill-in might or might not occur in this phase, differing from its usual behavior with the use of extracellular gadolinium Hemangiomas are formed by a clump of blood vessels and do not contain hepatocytes, therefore they do not present contrast enhancement during the hepatobiliary phase and appear hypointense in this phase 12915 Figure 4.
A potential confusion factor is the fact that some hemangiomas may present subtle central contrast uptake during the early hepatobiliary phase because of the hepxtocarcinoma to persistent centripetal enhancement at dynamic study, like in those with extracellular gadolinium 1. Female, year-old patient with liver nodules to be clarified. The caudate lobe lesion arrowheads presents subtle hypersignal on T2-weighted sequence and signal loss on T1-weighted out-of-phase sequence caused by the presence of intralesional fat.
Such a lesion shows intense and homogeneous contrast uptake in the arterial-phase, with decay in the portal and delayed phases, hepstocarcinoma greater hepatobiliary contrast uptake than the adjacent parenchyma, suggesting FNH as the first diagnostic hypothesis. Considering that hepatocarcinkma presence of intralesional fat in NFH is rare, the patient will be maintained under imaging follow-up. The lesions in diferencjal VII and VIII arrows are similar, with marked hypersignal on T2-weighted, hyposignal on T1-weighted sequence, and nodular, peripheral and discontinuous uptake in the arterial phase, a characteristic of hemangiomas.
In cirrhosis, the hepatobiliary contrast uptake by the nodules depends on their differentiation stage and on the presence of functioning hepatocytes. Low-grade regenerative and dysplastic nodules present preferentially portal vascularization, contain functioning hepatocytes and, like the surrounding parenchyma, show hepatobiliary contrast uptake. High-degree dysplastic nodules lose the portal vascularization and start gaining abnormal arterial vascularization.
Thus, high-grade dysplastic nodules tend to be hypovascular in the arterial and portal phases, but may also become hypervascular in the arterial phase in cases where the abnormal arterial vascularization is more developed. High-grade dysplastic nodules contain functioning hepatocytes and also demonstrate hepatobiliary contrast uptake in the same way as the surrounding parenchyma Figure 5.
Hepatobiliary contrast uptake by HCC also depends on its differentiation stage. Well-differentiated HCCs contain functioning hepatocytes and might show hepatobiliary contrast uptake.
On the difreencial hand, poorly-differentiated or undifferentiated hepatocarcinomas do not contain functioning hepatocytes and do not show hepatobiliary contrast uptake, remaining hypointense in relation to the surrounding parenchyma 21017 – 19 Figure 6. Male, year-old patients presenting with chronic hepatopathy and liver nodule to be clarified, adjacent to the gallbladder, as seen at ultrasonography.
Small nodules are observed adjacent to the gallbladder, with hyposignal on T2-weighted sequence, without expression on the other sequences and on the conventional dynamic study, but with hepatobiliary contrast uptake, leading to the diagnosis of regenerative nodules. Well-differentiated HCCs show hepatobiliary contrast uptake, requiring imaging follow-up.
Male, year-old patient presenting with chronic C virus hepatopathy. Two liver nodules are seen in the segment VIII arrows as well as a larger nodule, in the segment VI arrowheadsall of them contrast-enhanced in the arterial-phase, washout in the delayed-phase, and without uptake in the hepatobiliary-phase, characterizing HCCs.
Poorly differentiated or undifferentiated HCCs do not contain functioning hepatocytes so hepatobiliary contrast uptake is not observed. The different enhancement patterns depend on the histological grade of the HCCs and may hepatovarcinoma explained by the membrane hepatocarrcinoma expression. Hepatobiliary contrast uptake by HCCs depends on the tumor differentiation stage and on the amount of functioning hepatocytes 24. The diagnostic performance of MRI in the detection of HCCs of all sizes increases with the utilization of hepatobiliary contrast agents 1 However, in cases of advanced cirrhosis, the contrast uptake by the liver parenchyma may be compromised by decreased hepatocytes function, which would result in reduction of the method’s accuracy to detect HCCs 4 The differentiation between HCC and perfusion alterations may also represent a diagnostic challenge.
Perfusional alterations present a signal similar to the one of the remainder hepatic tissue during the portal and hepatobiliary phases, while most HCCs, except the well-differentiated ones, present hyposignal in the hepatobiliary phase