Practical Differential Diagnosis for CT and MRI

In winkelwagen Op verlanglijstje. Gratis verzending 30 dagen bedenktijd en gratis retourneren Ophalen bij een bol. Bekijk en vergelijk alle verkopers. Euclid Seeram Computed Tomography 76, Bekijk de hele lijst. Marcel Hakkert Computertomografie 80, Liefhebbers van Michael L Grey bekeken ook. Observation in a year-old man with HCV-related cirrhosis on the bottom.

The nodule was reclassified the same day as a LR-5us, as it was visible at ultrasound examination. The hypointense triangular area arrowhead has to be correlated to previous treatments. C, D mm nodule arrow in a old-woman with hepatitis C cirrhosis. The final category is LR WO appearance is defined as a nonperipheral, visually-assessed, temporal reduction in enhancement in whole or in part compared to the surrounding liver parenchyma from the earlier to later phase, resulting in hypoenhancement in the extracellular phase Figs.

Magnetic resonance images showing a mm nodule arrow in a year-old man with hepatitis C-related cirrhosis on the bottom. However, the observation was hypointense in the hepatobiliary phase C and slightly hyperintense in T2W images D. The patient underwent a biopsy which confirmed the diagnosis. Indeed, this major feature has shown itself to be an important predictor of HCC, permitting definitive diagnosis of HCC when associated with APHE and an observation size of 2 cm or larger, regardless of the presence of WO appearance.

The definition of HCC growth is an object of debate because growth has been variably defined in the various studies that have contributed to consensus criteria. Interestingly, new lesions measuring at least 1 cm are also given credit for threshold growth if they were not visible at a CT or MRI that had been performed less than 1 year before.

Because the difficulty in differentiating nodules from surrounding peritumoral enhancement can lead to overestimation of tumor size, LI-RADS recommends measurement on phases that are relatively constant over time e. The first group comprises those signs favoring malignancy, but which are not specific of HCC. The second group includes those markers that characterize HCC especially. Below, we discuss some of the main ancillary features favoring malignancy and HCC in particular. Hepatocellular adenomas HCAs are paramagnetic gadolinium chelates, determining shortening of the T1 relaxation time, that, compared to conventional extracellular gadolinium-based contrast agents, are able to provide similar arterial and portal venous phases, but because of their hepatocyte specific uptake they also enable an HBP.

Later, the agents are excreted into bile canaliculi via the multidrug resistance-associated protein also known as the canalicular multispecific organic anion transporter; cMOAT. Robust evidence have shown that OATP expression declines during hepatocarcinogenesis, so the evaluation of signal intensity in the hepatobiliary phase can help to identify and characterize hepatocellular nodules in the cirrhotic liver.

What pathological data suggest is that, in cirrhotic liver, OATP expression is still preserved in dysplastic nodules which in HBP typically have similar signal intensity to surrounding liver parenchyma ; it starts to decline just after malignant transformation, before the arterialization of the nodule is realized. Mild-moderate T2 hyperintensity is defined as an intensity on T2-weighted images that is mildly or moderately higher than liver and similar to or less than noniron-overloaded spleen, 20 but also less than bile ducts or other simple fluid-filled structures Figs.

Some authors have suggested that hyperintensity on T2-weighted imaging is consistent with the alterations of vascular profile occurring during hepatocarcinogenesis, such as sinusoid dilation 50 or increased intratumoral arterial supply corresponding to decreased intratumoral portal blood supply. Usually, in T2-weighted imaging, regenerative nodules are indistinct, dysplastic nodules, appearing as iso- or hypointense, whereas early HCC is typically isointense or mildly hyperintense. Recently, a consensus report statement confirmed the importance of mild-moderate T2 hyperintensity, recommending its use in the diagnosis and staging of HCC.

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DWI is an MRI spin-echo planar imaging sequence, sensitized to the driven random motion of water molecules water diffusion by the application of gradient pulses, the entity of which is indicated by a factor known as the b-value; the higher the b-value, the more sensitive the sequence is to water diffusion.

DWI A and T2-weighted image B demonstrate the presence of a mildly hyperintense nodule, both with the characteristics of ancillary features favoring malignancy, but not HCC in particular. The dynamic phases show a targetoid appearance either in the arterial phase note the rim hyperenhancement C , in the portal venous phase D and in the hepatobiliary phase E , meeting the criteria for LR-M.

The patient underwent a colonoscopy which found an ulcerative lesion in the left colon. A following liver biopsy confirmed that the lesion was a colon cancer metastasis. In , Zech et al. The main limitation of the use of DWI solely for assessing hepatic lesions is that there is a considerable overlap between benign and malignant lesions and normal liver tissue.

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Iron sparing refers to the lack of iron deposition in a solid mass relative to an iron-overloaded liver or inside an inner nodule relative to siderotic outer nodule. On CT, the iron-sparing mass is less hyperdense than the background iron-overloaded liver, which is characterized by greater attenuation values than normal usually more than 75 HU on unenhanced images. The main limitation of this feature is that it can be applied only to iron-overloaded livers with solid nodules that unequivocally have lower fractional iron content than background parenchyma.

LI-RADS defines corona enhancement as a periobservational enhancement in the late arterial or early portal venous phase, with fading to isoenhancement at subsequent phases.

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Corona enhancement is not specific for HCC, as it may be present in hypervascular metastasis as well, 9 and therefore it is included in the LI-RADS ancillary features for malignancy. Intralesional fat consists of excess lipid within a mass, in whole or in part, relative to the background liver.

Histologically, fatty metamorphosis seems to occur late during hepatocarcinogenesis, when an early-stage HCC gradually changes its blood supply from portal to arterial. Besides HCC, fatty changes can also occur in other pathologic conditions, such as high-grade dysplastic nodule and, occasionally, in low-grade dysplastic nodules.

The LI-RADS defines mosaic architecture as the presence of randomly distributed internal nodules or compartments, usually with different imaging features Figs. Interestingly, a recent retrospective study conducted on nonmetastatic HCC larger than 5 cm, suggested that the mosaic pattern may represent a prognostic factor as well, being associated with limited liver resection efficacy.

Nodule-in-nodule architecture is defined as the presence of a smaller inner nodule within a larger outer nodule, with different imaging features Figs. If the quality of the exam is not sufficient to allow an interpretation, the observation should be defined as LR-non-categorizable. Indeed, it should be noted that the LI-RADS does not assign a category to the entire liver, but it contemplates the coexistence in the same organ of multiple observations that can be classified differently.

The first step is to verify whether the observation meets the criteria of benignity. The LI-RADS defines benign entities as solid nodules with a distinctive imaging appearance compared to background cirrhotic nodules, with no major features of HCC or any other ancillary features of malignancy. Importantly, if the diameter is more than 20 mm, the observation should be categorized as LR The rationale is that these are supposed to be diagnoses of exclusion in high-risk patients.

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Namely, the radiologist should assess if an APHE, with the fore-mentioned features i. This should be the first step since, as it is shown in Fig. In all the other instances, the observation must be classified as LR In addition, the use of ancillary features cannot allow a change of category by more than one level, regardless of the number of features. Eventually, if there are conflicting ancillary features some of them favoring benignity and some of them favoring malignancy , the label should not be adjusted.

When the findings suggest malignancy, but they are not specific for HCC, the advisable category should be LRm.

Quiz questions

When an unequivocal enhancing soft tissue is present in the vein, the report should be categorized as LR-TIV and the etiology must be indicated as shown in Fig. Importantly, the assignment of this category does not necessarily require the visualization of a parenchymal mass. Cirrhotic year-old patient on the bottom. The axial A , the coronal B, C and the sagittal D computed tomography images show an infiltrating lesion of the left lobe invading the portal vein at the bifurcation, with involvement of both the left and right portal branches.

The lesion was biopsied and resulted in a diagnosis of HCC. The patient underwent sorafenib therapy. The LI-RADS provides a diagnostic algorithm aimed at standardizing the interpretations and reports of liver observations in a high-risk population for HCC, in order to optimize patient management. This system was conceived to reduce the indeterminacy, classifying the observations in five categories corresponding to increasing probability of HCC on the basis of the unequivocal presence of major and ancillary features.

Thus, radiologists and clinicians must be aware that not-benign categories less than LR-5 do not exclude the diagnosis of HCC, and that the LR-4 observation namely, just like the LR-5, may deserve a multidisciplinary discussion for consensus management. National Center for Biotechnology Information , U.

This lack of a normal endothelium readily allows leakage of blood elements. Not all CCM are associated with symptoms, but once they become symptomatic 40 to 50 percent present with seizures, 20 percent with focal neurological deficit, and percent with hemorrhage [1,2]. The risk of hemorrhage has been estimated between 0.

These number may be higher for patients with brain stem CCM [4] and the symptoms may worse when it occurs. Most of the lesions are supratentorial in location. According to the MRI study of autopsied cases, cavernoma exists in 0. Familial form is inheritated as an autosomal dominant trait with variable expression. The developmental venous anomaly DVA so called venous angioma are sometimes noted in association with cavernomas [6].

In CCM, angiography is usually normal,although prolonged injection may demonstrate an abnormal capillary blush [7]. The lesion shows no mass effect or surrounding edema except when recent hemorrhage or enlargement has occurred. Usually CCM shows no mas effect except rapid growth or intratumoral hemorrhage in our study because it is a kind of benign vascular hamartoma histologically. The T1WI high intensity foci was occasionally observed. It was thought to reflect the extremely slow flow or stagnation or thrombosis of varying stage mainly subacute phase.

Encapsulated hematoma or resolving hematoma were also mimicking lesions on MRI images. The hemorrhage are ongoing in repetitive processes. The type II lesions demonstrate loculated areas of hemorrhage of varying age and thrombus surrounded by gliosis and hemosiderin. On T1 and T2WI a reticulated core with high and low signal intensities Figure2 was surrounded by a hypointense ring.

Clinically these lesions are active, and thrombosis and hemorrhage are ongoing in a repetitive process, The type III lesions represent chronic mostly inactive lesions with residual hemosiderin in and around the lesions creating hypointensity on T1 and T2WI. The type IV lesions are poorly visualized on T1 and T2 and are best seen with gradient echo sequences as small punctuate hypointense foci. Subacute hemorrhage associated with a microarteriovenous malformations or brain tumor may mimic a type I lesions, and follow-up MRI and angiography is indicated under such circumstances.

The type II lesions were thought to be pathognomonic for cavernoma, but thrombosed AVM and hemorrhagic metastases may have a similar appearance [12] , type III and IV lesions may be mimicked by radiation-induced telangiectasis [13]. Susceptibility weighted imaging SWI is derived from the paramagnetic susceptibility effect in order to visualize venous structures and iron in the brain and to study diverse various conditions.

However, structures with higher susceptibility effect appear significantly larger than their actual size. Thus,diffusion weighted MRI signal is helpful in predicting intratumoral bleeding acute-subacute hemorrhage which occur mostly within the core area as we often observed in the patients of the cerebral hemorrhage Table 3. And the low intense signal area on T2WI assumed to reflect the hemosiderin leakage to the brain parenchyma. T2 shortening can also be produced by hemoglobin concentration and clot retraction.

Therefore, the differential diagnosis of CCM from the viewpoint of MRI signal are as follows;chronic hemorrhage, thrombosed AVM,developmental venous anomaly,hemorrhagic brain meta renal cell carcinoma,lung cancer,melanoma etc. The low intense signal area on DWI assumed to represent the hemosiderin or susceptibility effect and blood oxygen level dependent BOLD effect by the deoxyhemoglobin of hematoma Moreover there are some characteristics of its local extension; no apparent mass effect peri-focal edema or no apparent interval growth except hemorrhagic events.

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On DWI they usually showed high signal due to the highly viscosity due to change of the concentration of hemoglobin or diminishment of the extra celluar space by the regression of thrombus [8]. However, excessive deoxyhemoglobin and methhemoglobin evoke the susceptibility effect like hemosiderin. The GRE images showed marked low signal by the susceptibility and blood oxygen level dependent BOLD effect by the deoxyhemoglobin [16].