Hepatocellular carcinoma is commonly a problem of two diseases, the malignancy itself and cirrhosis. This renders treatment rarely curative, even when surgical resection can be applied in a technically successful sense. Liver transplantation could be a definitive treatment but this is plagued by limited donor resources.

Hepatocarcinogenesis in the cirrhotic liver has recently become a subject of intense investigation. The development of hepatocellular nodules demonstrating varying degrees of cellular and architectural atypia suggests that these nodular lesions represent a pathway of carcinogenesis in cirrhosis of different etiologies. This pathway involves processes, such as capillarization and neoangiogenesis, leading to a gradual change in blood supply from portal to arterial, as a dysplastic nodule becomes hepatocellular carcinoma. These changes in intranodular blood supply create different enhancement patterns in the two phases of liver circulation after an intravenous contrast injection on multi-phase helical CT or dynamic gadolinium-enhanced MRI. This article reviews the current concepts regarding the vascular changes occurring in dysplastic nodules in the multistep process of hepatocarcinogenesis, along with the associated imaging manifestations. Some practical issues and dilemmas regarding the follow-up and biopsy of these lesions are also discussed.

VUS HI and a second-generation contrast agent improved the identification of reflux in children. Our data reveal a higher sensitivity of the method compared to VCUG. Thus it can be used as an alternative radiation-free imaging method.

Our study shows that MRI provides a credible preoperative differentiation of seminomatous from nonseminomatous testicular tumors, with excellent interobserver agreement.

Thirty-seven patients with beta-thalassemia major, including 14 adolescents (15.2 +/- 3.0 years) and 23 adults (26.4 +/- 6.9 years), were studied. T2 relaxation time (T2) of the liver, bone marrow, pancreas and pituitary gland was measured in a 1.5-Tesla magnetic resonance (MR) imager, using a multiecho spin-echo sequence (TR/TE 2,000/20, 40, 60, 80, 100, 120, 140, 160 ms). Pituitary gland height was evaluated in a midline sagittal scan of a spin-echo sequence (TR/TE, 500/20 ms). The T2 of the pituitary gland was higher in adolescents (59.4 +/- 15 ms) than in adults (45.3 +/- 10.4 ms), P < 0.05. The T2 of the pancreas was lower in adolescents (43.6 +/- 10.3 ms) than in adults (54.4 +/- 10.4 ms). No difference among groups was found in the T2 of the liver and bone marrow. There was no significant correlation of the T2 among the liver, pancreas, pituitary gland and bone marrow. There was no significant correlation between serum ferritin and T2 of the liver, pancreas and bone marrow. Pituitary T2 showed a significant correlation with pituitary gland height (adolescents: R = 0.63, adults: R = 0.62, P < 0.05) and serum ferritin (adolescents: R = -0.60, adults: R = -0.50, P < 0.05). In conclusion, iron overload evaluated by T2 is organ specific. After adolescence, age-related T2 changes are predominantly associated with pituitary siderosis and fatty degeneration of the pancreas. Pituitary size decreases with progressing siderosis.

Our purpose was to measure the size of the pons and cerebellum in preterm babies with periventricular leukomalacia (PVL), and to study their relationship with the severity of PVL and with perinatal risk factors. We examined 33 premature children, mean gestational age 31 weeks, range 26-36 weeks with PVL on MRI, and 27 full-term controls. On MRI at 0.4-5.5 years (mean 1.4 years) we measured the area of the corpus callosum and vermis, the anteroposterior diameter of the pons and the volume of the cerebellum. The area of the corpus callosum was used as a marker of white matter loss and PVL severity. All regional brain measurements except that of the vermis were significantly lower in patients than controls: corpus callosum (mm(2)): 239.6+/-92.5 vs 434.8+/-126.8, P <0.01; pons (mm): 14.8+/-3.0 vs 17.9+/-1.4, P <0.01]; cerebellum (cm(3)): 68.2+/-31.6 vs 100.6+/-28.3, P <0.01; vermis (mm(2)): 808.1+/-292.2 vs 942.2+/-246.2, NS. Significant reduction in the area of the vermis: 411.3+/-203.3 vs 935+/-252.6 mm(2); cerebellar volume: 16.3+/-12.5 vs 96.6+/-20.2 mm(3); and the diameter of the pons: 10.1+/-2.2 vs 17.5+/-1.3 mm ( P<0.01) were observed in seven children with gestational age < or =28 weeks, severe hypotension and large patent ductus arteriosus (PDA). There was a significant correlation between the duration of mechanical ventilation and the size of the vermis, pons and cerebellum (R=-0.65, -0.57 and -0.73, respectively, P <0.01).

Recent pathologic studies of hepatic resection and transplantation specimens have elucidated the morphologic features of the precancerous lesions and small hepatocellular carcinomas (HCCs) arising in cirrhotic livers. Small HCCs measuring less than 2 cm in diameter are of two types: vaguely nodular, well-differentiated tumors, also known as "early" HCCs, and distinctly nodular tumors, with histologic features of "classic" HCC. The precancerous lesions include dysplastic foci and dysplastic nodules. "Classic" small HCCs are supplied by nontriadal arteries, whereas early HCCs and dysplastic nodules may receive blood supply from both portal tracts and nontriadal arteries. The similarities in blood supply of these three types of nodular lesions result in significant overlap of findings on dynamic imaging. Nevertheless, small HCCs sometimes display characteristic radiologic features, such as "nodule-in-nodule" configuration and "corona enhancement" pattern. Moreover, various histologic features of these nodular lesions may also be related to a variety of signal intensities and attenuation coefficients, while the presence of cirrhosis is known to limit the sensitivity and specificity of any imaging modality, due to liver inhomogeneity. Because of these reasons, imaging findings of nodular lesions in cirrhotic livers are often inconclusive, emphasizing the need for a better understanding of these imaging features.

The biophysical properties of the aortic wall seems to play a significant role in the pathogenesis of cardiovascular disease such as atherosclerosis, hypertension, aneurysm formation, Marfan's syndrome, and in normal aging. The presence and the proportion of smooth muscle, collagen, and elastin proteins contribute to the compliance of the vessel wall with the latter being the most extensible component. However, elastin fibers fracture at low stresses contributing to a decrease of the aortic compliance and consequently to an elevation of the pulse pressure, which is a risk factor of cardiovascular disease. Early detection of a decrease in the aortic compliance could help to identify early cardiovascular disease in asymptomatic patients and monitor the results of the therapeutic interventions. Therefore, estimation of the aortic compliance can be used for both screening as well as long-term follow-up. Magnetic resonance imaging which is a noninvasive, accurate, and reproducible method can estimate the compliance of the aortic wall either by measuring the relative change in cross sectional area of a chosen segment using ECG-triggered spin echo or gradient echo sequences or by measuring the pulse wave velocity through the aorta using the phase contrast-magnetic resonance imaging (PC-MRI) technique. Both techniques have been validated and many sudies suggest MRI as a valuable tool for evaluating aortic wall function. However, large prospective studies are mandatory for the method to be established as a screening tool.