Segmental staining on hepatic arteriography as a sign of intrahepatic portal vein obstruction

Peripheral obstruction of intrahepatic portal vein branches was detected by dynamic sequential computed tomography during arterial portography and subsequently confirmed surgically in 9 patients with hepatic neoplasm (7 hepatocellular carcinomas, 1 cholangiocarcinoma, and 1 metastatic lymphadenopathy from gastric carcinoma). In 1 patient, 2 obstructed segments were seen. Eight of these 10 segments showed more dense staining than other regions of the liver during infusion hepatic angiography. Retrograde opacification of the peripheral venules of the obstructed portion was seen in 2 of these 8 segments. This pattern was attributed to trans-sinusoidal or peripheral arterioportal shunting. In 5 cases, the segmental staining obscured the tumor stain, making the tumor appear larger than it actually was or causing it to be missed altogether.     

Lobar intensity differences of the liver on MR imaging

Differences in signal intensity involving lobes of the liver were noted in seven cases of liver tumor. The clinical significance and possible cause of these differences in lobar intensity are discussed.     

Increased signal intensity in the pulvinar on T1-weighted images: a pathognomonic MR imaging sign of Fabry disease

BACKGROUND AND PURPOSE: Fabry disease is a multisystem X-linked disorder characterized clinically by angiokeratoma, corneal and lenticular abnormalities, acroparesthesia, and renal and cardiac dysfunction and stroke. We sought to describe novel neuroimaging characteristics of Fabry disease. METHODS: Neuroradiologic records of 104 hemizygous patients with Fabry disease evaluated between 1994 and 2002 were reviewed. In total, 94 MR studies consisting of T1- and T2-weighted images were examined for the presence of hyperintensity on the T1-weighted images. Additional CT, gradient-echo (T2*-weighted), and fat-suppression MR studies were reviewed to characterize further the T1 abnormality in selected patients. In some patients, cerebral blood flow (CBF) was quantified by using arterial spin tagging (AST). RESULTS: Overall, 22 patients ( approximately 23%) demonstrated pulvinar hyperintensity on T1-weighted images; the frequency increased with age to over 30% by age 50 years. Susceptibility-weighted T2* studies demonstrated a low-signal-intensity abnormality in the pulvinar in the more severe cases, whereas CT demonstrated the pulvinar to be mineralized. CT attenuation corresponded with an increasing signal intensity on T1-weighted images. Posterior circulation CBF was found to be elevated on individual AST studies, especially in the thalamus. CONCLUSION: Hyperintensity in the pulvinar on T1-weighted images is a common finding in Fabry disease, likely reflecting the presence of calcification. Although other minreralizing abnormalities may result in calcification of deep gray nuclei, exclusive involvement of the pulvinar may be distinctively characteristic to Fabry disease. Increased CBF in the posterior circulation, particularly the thalamus, suggests that the dystrophic calcification is secondary to cerebral hyperperfusion and selective vulnerability of the pulvinar and adjacent thalamic nuclei. The finding of isolated pulvinar hyperintensity on T1-weighted images should suggest Fabry disease, particularly when seen in conjunction with other nonspecific neuroradiologic manifestations of the disease.     

High signal intensity halo around the carotid artery on maximum intensity projection images of time-of-flight MR angiography: a new sign for intraplaque hemorrhage

PURPOSE: To evaluate the value of the high signal intensity halo sign as a new marker of a fresh or recent intraplaque hemorrhage on the maximum intensity projection (MIP) images of time-of-flight (TOF) MR angiography. MATERIALS AND METHODS: A total of 135 consecutive patients were included in this study. High-resolution MRI using 3-inch surface coils was performed on a 1.5T scanner before the carotid endarterectomy. TOF MR angiograms and T2-weighted, T1-weighted pre- and postcontrast fast spin echo images were obtained. The surgical and pathological findings of the carotid artery were analyzed and correlated with the MRI findings. RESULTS: A total of 42 atheromas (31.1%) had a fresh or recent intraplaque hemorrhage on the surgicopathological findings. A total of 38 (90.5%) of these patients showed high signal intensity halo around the carotid artery on the MIP images of TOF MR angiography. The high signal intensity halo sign, compared with the surgical and histopathological findings, demonstrated a sensitivity, specificity, positive predictive value, and negative predictive value of 91%, 83%, 72%, and 95%, respectively, with a 95% confidence interval (CI) in the detection of an intraplaque hemorrhage. The multisequence approach suggested the presence of an intraplaque hemorrhage with a sensitivity, specificity, positive predictive value, and negative predictive value of 93%, 85%, 74%, and 96%, respectively, with a 95% CI. CONCLUSION: High signal intensity halo around the carotid artery on the MIP images of TOF MR angiography is useful in the noninvasive detection of a fresh or recent carotid intraplaque hemorrhage.     

Malignant lesions of the liver with high signal intensity on T1-Weighted MR images

Our purpose was to identify the histologic types of malignant liver lesions with high signal intensity (SI) on T1-weighted images and to describe the MR imaging features. Thirteen patients with malignant liver lesions high in SI on T1-weighted images were studied with a 1.5-T MR imager using pre- and serial postcontrast spoiled gradient-echo (SGE) sequences (all patients), T2-weighted fat-suppressed spin-echo sequences (all patients), precontrast T1-weighted fat-suppressed spin-echo sequences (five studies in five patients), and precontrast out-of-phase SGE sequences (seven studies in six patients). Images were reviewed retrospectively to determine number of lesions; lesion size; SI of lesions on T1-weighted, T2-weighted, and fat-attenuated T1-weighted images; distribution of high SI in lesions on T1-weighted images; and tumor enhancement pattern. Seven patients had multiple tumors high in SI on T1-weighted images and six patients had solitary tumors. Seventy-two lesions were less than 1.5 cm in diameter and 35 lesions were more than 1.5 cm in diameter. Nine patients had solid malignant lesions and four patients had cystic malignant lesions. All tumors more than 1.5 cm in diameter were heterogeneously high in SI on T1-weighted images, and all tumors less than 1.5 cm were completely homogeneous or homogeneous with a small central hypointense focus. All tumors were more conspicuous on T1-weighted fat-attenuated images, both on excitation spoiled fat-suppressed spin-echo or on out-of-phase SGE images with the exception of one fat-containing hepatocellular carcinoma (HCC). In one patient with melanoma metastases and one patient with multiple myeloma nodules, appreciably more lesions were detected on out-of-phase SGE images. Causes of hyperintensity were considered to be either fat, melanin, central hemorrhage, or high protein content, all of which may be seen in a variety of tumors. Fat-attenuation techniques are helpful in the detection of these lesions.     

Segmental enhancement on breast MR images: differential diagnosis and diagnostic strategy

The histopathological variations of segmental enhancement on breast magnetic resonance imaging (MRI) were investigated, with the aim of identifying imaging characteristic clues to their differential diagnosis. We reviewed 70 breast MRI examinations demonstrating segmental enhancement, classified them based on their histopathology, and assessed their MRI findings as follows: (1) confluent or not confluent, (2) late enhancement pattern, and the absence or presence of (3) clustered ring enhancements and (4) surrounding high signal intensity (SI) on T2-weighted imaging. Thirteen lesions (18.5%) were benign, eight (11.5%) were high risk, 25 (36%) were ductal carcinoma in situ (DCIS) and 24 (34%) were infiltrating mammary carcinomas (IMC). Clustered ring enhancements were demonstrated in 74% of malignancies (high risk, DCIS and IMC) but no benign lesions (P = 0.0001). The surrounding high SI on T2-weighted imaging was seen in four of five IMC with marked lymphatic involvement. Clustered ring enhancement was not demonstrated in six of seven IMC of tubular and/or lobular types. Segmental enhancement was seen in not only DCIS but also IMC, high-risk and benign lesions. Clustered ring enhancement and surrounding high SI on T2-weighted imaging were clues to their differential diagnosis and helpful to decide their diagnostic strategy.     

乳腺MRI上的节段性强化:鉴别诊断与诊断策略

探讨乳腺MRI上节段性强化病灶的各种组织病理学变化,明确提示鉴别诊断的影像学特征。回顾性分析70例表现有节段性强化的乳腺MRI资料,根据组织病理学进     

Spontaneous intermittent reversal of blood flow in intrahepatic portal vein branches in cirrhosis of the liver

The intrahepatic portal venous flow in cirrhosis of the liver was evaluated by percutaneous transhepatic portography and hepatic arteriography. Spontaneous reversal of flow in segmental portal vein branches was documented. Changes in hepatic arterial inflow and portal venous pressure may result in intermittent changes in the direction of flow in segmental portal venous branches within the cirrhotic liver. Segmental reversal of blood flow seems to be the precursor of total hepatofugal portal flow.     

Relative intensity of abdominal organs in MR images

Knowledge of the normal relative intensity of organs and tissues is a valuable aid to clinical interpretation of magnetic resonance images. In this study the in vivo spin echo image intensities of normal parenchymal organs and other structures in the upper abdomen were evaluated for eight parameter combinations. The examinations of 40 patients were used. Image intensity and calculated T1, T2, and spin density values were obtained for liver, spleen, pancreas, renal cortex, renal medulla, bone marrow, skeletal muscle, and fat. Repetition times (TR) of 500, 1,000, 1,500, and 2,000 ms and echo times of 28 and 56 ms were used. The T1 and T2 values and relative spin density were calculated using a new algorithm. Liver had the smallest relative standard deviation of T1 of all the tissues studied. For comparison purposes, relative image intensities were calculated by normalizing them to the intensity of liver in the same image. The resulting compiled data show the normal ranks and ranges for relative intensity for the tissues in each of eight types of spin echo images. Although images with short TR and echo time (TE) are known to display the greatest T1 contrast, the mean relative intensities of all tissues except muscle and fat in the TR = 500 and TE = 28 ms images were within 20% of liver. A much larger spread in the normal relative intensities was observed with longer TE and TR.     

Pulsatile portal vein flow: a sign of tricuspid regurgitation on duplex Doppler sonography

Sonography and duplex Doppler frequently fail to identify a cause for right upper quadrant pain, liver dysfunction, or ascites. The aim of our study was to describe and analyze the pulsatile portal venous waveform in which minimum velocity dropped to or below zero on duplex Doppler sonography and to investigate its possible association with tricuspid regurgitation, one of the causes of liver dysfunction. We correlated the findings in 15 patients in whom this duplex Doppler waveform was seen with the findings on Doppler echocardiography (n = 14) or ultrafast CT (n = 1). All patients had biochemical liver abnormalities or sudden onset of ascites, rapid weight gain, increased abdominal girth, and hepatomegaly. They were referred for sonography to rule out liver metastases, biliary disease, portal vein thrombosis, or Budd-Chiari syndrome. All examinations were done with a 3-MHz phased-array sector transducer with duplex Doppler capability. Seventeen volunteers with no known liver or heart disease served as a control group. We correlated maximum and minimum flow velocities on the portal venous Doppler waveform with the portal vein diameters of the study and control groups. Thirteen patients were later proved to have tricuspid regurgitation, one patient had an aortic-right atrial fistula owing to rupture of an aneurysm of the sinus of Valsalva, and one patient was proved to be normal. In none of the 17 control subjects was this pulsatile portal venous waveform seen. Our study shows that detection of a pulsatile portal venous waveform on duplex Doppler sonography in patients with liver dysfunction should raise the possibility of tricuspid regurgitation.     

Leptomeningeal high signal intensity (ivy sign) on fluid-attenuated inversion-recovery (FLAIR) MR images in moyamoya disease

PURPOSE: There are a few reports on leptomeningeal high signal intensity (LMHI: ivy sign) on fluid-attenuated inversion-recovery (FLAIR) images in moyamoya disease, but the feature of this finding has not been completely understood. The purpose of this study was to characterize LMHI on FLAIR images in moyamoya disease and to assess usefulness of this finding in the diagnosis of moyamoya disease in conventional MR imaging. MATERIAL AND METHODS: MR imaging of 28 patients with moyamoya disease was retrospectively reviewed. The grade of LMHI on FLAIR images was classified as "absent," "minimal," "moderate" and "marked." Fifty-four hemispheres of 28 patients (2 patients had unilateral disease) were assessed for the frequency of visualization and distribution of LMHI. The correlations between LMHI on FLAIR images, moyamoya vessels on T1- and T2-weighted images and MR angiography findings were also analyzed. RESULTS: Moderate and marked LMHI was seen in 31 out of 54 hemispheres (57%). LMHI was seen more prominently in the frontal and parietal lobes than in the temporal and occipital lobes. Although there was a tendency for LMHI on FLAIR images to be prominent in groups with moderate and marked moyamoya vessels on T1- and T2-weighted images, there was no significant correlation. More prominent LMHI was observed in the hemispheres in which cortical branches of the middle cerebral arteries were poorly visualized on MR angiography. CONCLUSION: Leptomeningeal high signal intensity (ivy sign) on FLAIR images is predominantly seen in the frontal and parietal lobes. Because this sign can be seen in patients with unremarkable moyamoya vessels, LMHI is a useful sign in conventional MR imaging for the diagnosis of moyamoya disease.     

Segmental assessment on ordinary scintigrams and SPECT images of the liver

By examining the area of defect elucidated on the scintigrams and SPECT (single photon emission computed tomography) images, the extension of the tumor into segments was assessed in cases where the SOL (space-occupying lesion) was determined by other methods. In this study, we followed the Couinaud's segmentation. As a result, it was found that the segment with a SOL could be diagnosed fairly well on radionuclide images. Some incorrect assumptions were also found about the segments on ordinary scintigrams in previously published articles. These incorrect assumptions have been accepted for a long time. Although we do not deny that TCT (transmission X-ray computed tomography), echography, angiography, etc. are necessary for a precise judgment on liver segment and also that there are some cases in which the segmental assessment of these radionuclide images is impossible, we do believe that this kind of effort will improve the diagnostic capability of the radionuclide images.