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Congenital absence of the portal vein is a very rare anomaly. The intestinal and splenic venous drainage bypasses the liver and drain into the inferior vena cava (IVC). Two cases of such anomaly are described. Both cases were investigated by US coupled with echo-colour Doppler examination, CT and MR imaging, followed by digital subtraction angiography (DSA) and liver biopsy. In the first case the splenic and superior mesenteric vein formed a venous trunk which emptied directly into the IVC; in the second case, the splanchnic blood flowed into a dilated hepatofugal inferior mesenteric vein which connected to the left internal iliac vein. In both cases nodular regenerative hyperplasia of the liver was present, presumably due to an abnormal hepatic cell response to the absent portal flow. The particular contribution of MR imaging to the diagnosis of both vascular abnormalities and liver parenchyma derangement and its advantages over the other diagnostic techniques is emphasized. The clinical and radiological features of 17 previously reported cases are reviewed.

Nodular hepatocellular carcinoma (HCC) is characterized by the presence of a pseudocapsule (constructed usually from connective fibrous tissue) that appears hypointense on T1- and T2-weighted spin-echo (SE) and gradient-echo (GE) MR imaging sequences without a contrast medium. The presence of vascular structures inside the tumor, which are verified by histological exam, affects enhancement of the PC after administrating the contrast medium: The impregnation is more evident in the dynamic study but also persists on the delayed T1-weighted SE images. The accuracy of MR in detecting the pseudocapsule of HCC and contrast enhancement of the pseudocapsule during dynamic studies were evaluated and related to pathological findings. Thirty-seven HCC were examined in 33 patients and afterwards resected. In capsulated nodules, besides usual hematoxylin, eosin, and trichrome stainings, histochemical and immunohistochemical methods were performed. On a 1.5-T MR unit, T1- and T2-weighted SE and GE FLASH 2D sequences after intravenous injection of Gd-DTPA (dynamic study) were used. In a later phase, T1-weighted SE sequences were repeated. Histologically, the pseudocapsule (thickness 0.2–6 mm) was present in 26 of 37 nodules (70 %). The dynamic study was the most suitable technique to show the pseudocapsule, which was recognized in 80.7 % (21 of 26 nodules). In 5 of 26 cases, the pseudocapsule, not demonstrated by MR, was thinner than 0.4 mm. In 16 of 21 cases, in the early portal phase (30–60 s), the pseudocapsule had an early enhancement, which was more evident later; in 5 of 21 cases the enhancement was observed only in the late portal phase (1–2 min). At histological examination, 14 of 16 pseudocapsules with early enhancement showed a more prominent vasculature than those with enhancement in the equilibrium phase. Magnetic resonance was a reliable tool in demonstrating the pseudocapsule of HCC. The histological examination demonstrated a good correlation between the enhancement behavior and the vessel number of the pseudocapsule.

In order to compare the advantages and failings of the current imaging procedures used for the staging of parotid masses, 121 patients were investigated: 30 with ultrasound (US) and CT, 55 with US and MRI, and 36 with US, CT and MRI. The accuracy of the three imaging modalities was evaluated in detecting parotid lesions; in assessing their location (intra- or extraglandular) and nature (benign or malignant); and in defining their intraglandular extent (superficial or deep lobe) as well as their relationship with surrounding structures. The imaging findings were related to the cytohistological data from US-guided biopsy or from surgical resection. In the 36 patients studied with all three modalities the diagnostic accuracy (excluding double errors in the same patient) was 77.7% for US, 86.1% for CT and 94.4% for MRI. US was thus shown to be less accurate than CT or MRI, and MRI not significantly superior to CT. US with fine-needle aspiration cytology should be the first-line imaging technique; CT and MRI have to be- considered for lesions more than 3 cm in diameter or for masses arising in the deep lobe of the gland. The results of this series show that MRI provides better results than CT in displaying the relationship of the mass with contiguous structures.

This was a prospective, multicenter study designed to evaluate the utility of MDCT in the diagnosis of coronary artery disease (CAD) in patients scheduled for elective coronary angiography (CA) using different MDCT systems from different manufacturers. Twenty national sites prospectively enrolled 367 patients between July 2004 and June 2006. Computed tomography (CT) was performed using a standardized/optimized scan protocol for each type of MDCT system (> or =16 slices) and compared with quantitative CA performed within 2 weeks of MDCT. A total of 284 patients (81%) were studied by 16-slice MDCT systems, while 66 patients (19%) by 64-slice MDCT scanners. The primary analysis was on-site/off-site evaluation of the negative predictive value (NPV) on a per-patient basis. Secondary analyses included on-site evaluation on a per-artery and per-segment basis. On-site evaluation included 327 patients (CAD prevalence 58%). NPV, positive predictive value (PPV), sensitivity, specificity, and diagnostic accuracy (DA) were 0.91 (95% CI 0.85-0.95), 0.91 (95% CI 0.86-0.95), 0.94 (95% CI 0.89-0.97), 0.88 (95% CI 0.81-0.93), and 0.91 (95% CI 0.88-0.94), respectively. Off-site analysis included 295 patients (CAD prevalence 56%). NPV, PPV, sensitivity, specificity, and DA were 0.73 (95% CI 0.65-0.79), 0.93 (95% CI 0.87-0.97), 0.73 (95% CI 0.65-0.79), 0.93 (95% CI 0.87-0.97), and 0.82 (95% CI 0.77-0.86), respectively. The results of this study demonstrate the utility of MDCT in excluding significant CAD even when conducted by centers with varying degrees of expertise and using different MDCT machines.