Daniella Braz Parente

MR Imaging of Hypervascular Lesions in the Cirrhotic Liver: A Diagnostic Dilemma

Cirrhosis is characterized by a spectrum of hepatocellular nodules that mark the progression from regenerative nodules to low- and high-grade dysplastic nodules, followed by small and large hepatocellular carcinomas (HCCs). Characterization of small nodules on the basis of imaging and histopathologic findings is complicated by an overlap in findings associated with each type of nodule, a reflection of their multistep transitions. Vascularity patterns change gradually as the nodules evolve, with an increasing shift from predominantly venous to predominantly arterial perfusion. Regenerative and low-grade dysplastic nodules demonstrate predominantly portal perfusion and contrast enhancement similar to that of surrounding parenchyma. Differentiation of high-grade dysplastic nodules and well-differentiated HCCs on the basis of dynamic imaging and histologic findings is challenging, with a high rate of false-negative results. Some small nodules that lack hypervascularity may be early HCCs. Progressed small and large HCCs usually present no diagnostic difficulty because of their characteristic findings. Although characterization of hypervascular lesions in the cirrhotic liver is difficult, it is a key step in disease management and is the radiologists responsibility.

Intravoxel Incoherent Motion Diffusion Weighted MR Imaging at 3.0 T: Assessment of Steatohepatitis and Fibrosis Compared with Liver Biopsy in Type 2 Diabetic Patients.

Objective To evaluate the capability of intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) to assess steatohepatitis and fibrosis determined by histopathology in type 2 diabetic patients. Methods Fifty-nine type 2 diabetic patients (49 women, 10 men; mean age, 54 ± 9 years) were submitted to liver biopsy for the evaluation of non-alcoholic fatty liver disease (NAFLD) and underwent DWI on a 3.0T MR system using 10 b values. Institutional approval and patient consent were obtained. Pure molecular-based (D), perfusion-related (D*), and vascular fraction (f) were calculated using a double exponential model and least squares curve fitting. D, D*, and f were compared between patients with and without steatohepatitis and between patients with and without fibrosis. The variables were compared by using the Ranksum test and Student t-test. Results Steatohepatitis was observed in 22 patients and fibrosis in 16 patients. A lower D median (0.70 s/mm2 vs. 0.83 s/mm2, p<0.05) and a lower D* median (34.39 s/mm2 vs. 45.23 s/mm2, p<0.05) were observed among those with steatohepatitis. A lower D median (0.70 s/mm2 vs. 0.82 s/mm2, p<0.05) and a lower D* median (35.01 s/mm2 vs. 44.76 s/mm2, p=0.05) were also observed among those with fibrosis. Conclusion IVIM-DWI has the potential to aid in the characterization of steatohepatitis and fibrosis.

Contraste hepatobiliar: diagnóstico diferencial das lesões hepáticas focais, armadilhas e outras indicações

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: differentiation between focal nodular hyperplasia and adenoma; characterization of hepatocellular carcinomas in cirrhotic patients; detection of small liver metastases; evaluation of biliary anatomy; and characterization of postoperative biliary fistulas. 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 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: differentiation between focal nodular hyperplasia and adenoma; characterization of hepatocellular carcinomas in cirrhotic patients; detection of small liver metastases; evaluation of biliary anatomy; and characterization of postoperative biliary fistulas. 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.

Is MR Spectroscopy Really the Best MR-Based Method for the Evaluation of Fatty Liver in Diabetic Patients in Clinical Practice?

Objective To investigate if magnetic resonance spectroscopy (MRS) is the best Magnetic Resonance (MR)-based method when compared to gradient-echo magnetic resonance imaging (MRI) for the detection and quantification of liver steatosis in diabetic patients in the clinical practice using liver biopsy as the reference standard, and to assess the influence of steatohepatitis and fibrosis on liver fat quantification. Methods Institutional approval and patient consent were obtained for this prospective study. Seventy-three patients with type 2 diabetes (60 women and 13 men; mean age, 54±9 years) underwent MRI and MRS at 3.0 T. The liver fat fraction was calculated from triple- and multi-echo gradient-echo sequences, and MRS data. Liver specimens were obtained in all patients. The accuracy for liver fat detection was estimated by receiver operator characteristic (ROC) analysis, and the correlation between fat quantification by imaging and histolopathology was analyzed by Spearmans correlation coefficients. Results The prevalence of hepatic steatosis was 92%. All gradient-echo MRI and MRS findings strongly correlated with biopsy findings (triple-echo, rho = 0.819; multi-echo, rho = 0.773; MRS, rho = 0.767). Areas under the ROC curves to detect mild, moderate, and severe steatosis were: triple-echo sequences, 0.961, 0.975, and 0.962; multi-echo sequences, 0.878, 0.979, and 0.961; and MRS, 0.981, 0.980, and 0.954. The thresholds for mild, moderate, and severe steatosis were: triple-echo sequences, 4.09, 9.34, and 12.34, multi-echo sequences, 7.53, 11.75, and 15.08, and MRS, 1.71, 11.69, and 14.91. Quantification was not significantly influenced by steatohepatitis or fibrosis. Conclusions Liver fat quantification by MR methods strongly correlates with histopathology. Due to the wide availability and easier post-processing, gradient-echo sequences may represent the best imaging method for the detection and quantification of liver fat fraction in diabetic patients in the clinical practice.

Pulmonary arterial hypertension: an imaging review comparing MR pulmonary angiography and perfusion with multidetector CT angiography.

Pulmonary hypertension (PH) is a progressive disease that leads to substantial morbidity and eventual death. Pulmonary multidetector CT angiography (MDCTA), pulmonary MR angiography (MRA) and MR-derived pulmonary perfusion (MRPP) imaging are non-invasive imaging techniques for the differential diagnosis of PH. MDCTA is considered the gold standard for the diagnosis of pulmonary embolism, one of the most common causes of PH. MRA and MRPP are promising techniques that do not require the use of ionising radiation or iodinated contrast material, and can be useful for patients for whom such material cannot be used. This review compares the imaging aspects of pulmonary MRA and 64-row MDCTA in patients with chronic thromboembolic or idiopathic PH.

Modern Imaging Evaluation of the Liver: Emerging MR Imaging Techniques and Indications

Modern MR imaging evaluation of the liver allows for a comprehensive morphologic and functional assessment of the liver parenchyma, hepatic vessels, and biliary tree, thus aiding in the diagnosis of both focal and diffuse liver diseases.

Computed tomography and magnetic resonance enterography findings in Crohn's disease: what does the clinician need to know from the radiologist?

The purpose of this pictorial essay was to discuss and illustrate computed tomography and magnetic resonance enterography findings in patients with Crohns disease. These noninvasive and easily performed methods for the evaluation of Crohns disease are useful for differentiating between active and fibrotic bowel disease, and can help to guide treatment (medical vs surgical). Although inflammatory and fibrostenotic findings of Crohns disease may overlap, computed tomography and magnetic resonance enterography can help to identify the presence, extent, and severity of active inflammation that may respond to medical therapy, and the existence of fistulas and fibrostenosis that may benefit from surgical management.

Linfoma de colo de útero: achados na ressonância magnética

Lymphoma of the cervix is a rare disease. About 1.0% to 1.5% of extranodal lymphomas originates in the female genital tract. The clinical presentation of this condition is nonspecific and magnetic resonance imaging is important for diagnostic elucidation. The present report describes the case of a 80-year-old patient with lumbar pain, whose magnetic resonance imaging showed a large uterine mass. The final diagnosis was lymphoma.

Epidural cavernous hemangioma of the spine: magnetic resonance imaging findings

Congenital abnormalities not related to the fusion site are observed in 10% to 20% of cases of conjoined twins. Diaphragmatic hernia such as the one observed in the present case is one of the described findings. Upper eyelid coloboma that was also identified in the present case is considered to be a rare abnormality. Thus, the correct determination of the type of imperfect twinning as well as of the fusion extent may be useful in the evaluation of the condition severity and in the postnatal surgical planning. Determining the severity of the condition is of paramount importance considering that the Brazilian laws allows for gestation termination in cases where the extrauterine life is not possible.

Pheochromocytoma of the urinary bladder

Dear Editor,A 44-year-old female presented with a 7-year history of par-oxysmal episodes of dyspnea, headache, palpitation, tremors, andhypertension. In each episode, there had been a sudden onset ofsymptoms, with no triggering factors, and spontaneous improve-ment after approximately 15 min. On physical examination, shepresented no relevant findings or comorbidities. At hospital ad-mission, she reported having had episodes of palpitation, tachy-cardia, and profuse post-micturition sweating, remaining asymp-tomatic between episodes. She was submitted to computed to-mography (CT) and magnetic resonance imaging (MRI), asshown in Figures 1A and 1B, respectively. The CT scan, withintravenous administration of contrast medium, revealed a nodu-lar lesion, measuring 3.5 × 3.0 cm, with lobulated contours andincreased density in its soft parts, showing intense, heterogeneousenhancement, in the anteroinferior wall of the bladder. On MRI,the lesion presented a lobular pattern, with a heterogeneous sig-nal on T2-weighted sequences, a predominance of isointense sig-nals, and foci of hyperintense signals in its center. Surgical resec-tion of the lesion (partial cystectomy) was performed. Examina-tion of the surgical specimen, retrieved from the right anteriorwall of the bladder, showed a yellowish tumor measuring 3.0 ×3.0 cm, with a macroscopic appearance similar to that of adrenaltissue (Figure 1C). The pathological examination of the speci-men revealed extra-adrenal paraganglioma and tumor-free mar-gins (Figure 1D). In the postoperative period and during the re-mainder of the hospital stay, the patient did not present any of theadrenergic symptoms previously reported.Pheochromocytomas are tumors of the sympathetic nervoussystem and can be functioning or nonfunctioning, sometimessecreting catecholamines, thus causing paroxysmal hypertension,palpitations, headache, and syncope