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Objective: Our objectives were 3-fold: to define the correlation between automated volumetric and 2-dimensional measurements of pulmonary nodule growth and prospectively; to determine whether volumetric growth analysis represents a useful addition to 2-dimensional measurements; and to evaluate growth rates over time of biopsy-proven lung cancers using automated volumetric software., Methods: Nodule growth on consecutive 2-dimensional computed tomographic scans was measured, and a decision regarding nodule biopsy was made. Automated volumetric software was then used to determine nodule growth, growth rates obtained from the 2 techniques were correlated, and the decision to perform a biopsy was reassessed. Biopsy-proven lung cancer growth rates were then documented over time., Results: Growth rates measured using volumetric software were highly correlated with 2-dimensional measurements (r = 0.69; P < .00001). This correlation was affected by nodule type (irregular [r = .63] versus smooth [r = 0.84]; P = .02) as well as the interval between scans (<100 days [r = .5] versus >100 days [r = 0.76]; P = .02). The addition of volumetric growth analysis changed the decision to perform a biopsy after only a minority (6.2%) of scan comparisons; however, lung cancer was diagnosed in 43% of these cases. Growth curves for individual cancers were highly variable, with 45% of tumors showing at least 1 period of shrinkage., Conclusions: Automated volumetric software influences biopsy decisions in only a minority of cases in a dedicated pulmonary nodule clinic, but seems to be useful in detecting lung cancer in this minority. Radiographically determined nodule growth rates, in general, need to be questioned as the sole determinate of the need to perform a biopsy., (Copyright © 2011 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.)

Institutional review board approval and informed consent were obtained for this HIPAA-compliant study. The purpose of this study was to prospectively evaluate sensitivity and specificity of various estimated perfusion parameters at three-dimensional (3D) perfusion magnetic resonance (MR) imaging of the liver in the diagnosis of advanced liver fibrosis (stage >or= 3), with histologic analysis, liver function tests, or MR imaging as the reference standard. Whole-liver 3D perfusion MR imaging was performed in 27 patients (17 men, 10 women; mean age, 55 years) after dynamic injection of 8-10 mL of gadopentetate dimeglumine. The following estimated perfusion parameters were measured with a dual-input single-compartment model: absolute arterial blood flow (F(a)), absolute portal venous blood flow (F(p)), absolute total liver blood flow (F(t)) (F(t) = F(a) + F(p)), arterial fraction (ART), portal venous fraction (PV), distribution volume (DV), and mean transit time (MTT) of gadopentetate dimeglumine. Patients were assigned to two groups (those with fibrosis stage or= 3), and the nonparametric Mann-Whitney test was used to compare F(a), F(p), F(t), ART, PV, DV, and MTT between groups. Receiver operating characteristic curve analysis was used to assess the utility of perfusion estimates as predictors of advanced liver fibrosis. There were significant differences for all perfusion MR imaging-estimated parameters except F(p) and F(t). There was an increase in F(a), ART, DV, and MTT and a decrease in PV in patients with advanced fibrosis compared with those without advanced fibrosis. DV had the best performance, with an area under the receiver operating characteristic curve of 0.824, a sensitivity of 76.9% (95% confidence interval: 46.2%, 94.7%), and a specificity of 78.5% (95% confidence interval: 49.2%, 95.1%) in the prediction of advanced fibrosis., ((c) RSNA, 2008.)

Objective: The aim of this study was to compare the quality of images obtained with fast 3D T2-weighted turbo spin-echo (TSE) MR cholangiopancreatography (MRCP) sequences and 1-mm isotropic voxels with the quality of conventional 2D MRCP images., Subjects and Methods: Thirty consecutively registered patients (14 women, 16 men; average age, 60.2 years; age range, 32-87 years) underwent imaging at 1.5 T with a 6-element body array coil. All imaging was performed with three MRCP techniques: free-breathing 3D T2-weighted TSE (TR/TE, 1,300/680; flip angle, 180 degrees; field of view, 250-300 mm; matrix size, 256 x 256; slice thickness, 1 mm; parallel acquisition technique factor, 2); breath-hold 3D T2-weighted TSE (same parameters as the free-breathing 3D technique); breath-hold coronal and oblique coronal thick-slab 2D TSE without parallel acquisition technique (2,800/1,100; flip angle, 150-180 degrees). Quantitative measures of image signal and contrast were evaluated by analysis of variance and paired Student's t tests. A 5-point scale (1, nondiagnostic, to 5, high diagnostic confidence) was used to compare the 3D and 2D data sets for image quality and definition of biliary and pancreatic ductal anatomic features. Friedman's nonparametric and Wilcoxon's rank sum tests were performed for statistical analysis of the qualitative assessments., Results: Quantitative results showed free-breathing and breath-hold 3D TSE images had significantly higher relative signal intensity and contrast than 2D TSE images (p < 0.0001). The qualitative findings showed that both free-breathing and breath-hold 3D TSE techniques gave better delineation of biliary anatomy (p < 0.0001) than the 2D technique. The overall quality of 3D images was better than that of 2D images, and 3D imaging was better at depicting pancreatic ducts, although the difference did not reach statistical significance., Conclusion: Three-dimensional volumetric MRCP images are of superior quality and give better delineation of pancreaticobiliary anatomy than conventional 2D images and have the added advantage of multiplanar and postprocessing capabilities.

Key Concepts: 1. The lack of whole-liver explant correlation has led to an overestimation of the sensitivity of imaging tests for the diagnosis of HCC in the radiological literature. 2. Ultrasound is insensitive for the diagnosis of HCC in the cirrhotic liver and should not be used for the detection of focal liver lesions in this setting. 3. Although magnetic resonance (MR) imaging is more sensitive than multidetector 3-phase computed tomography (CT) for the diagnosis of regenerative and dysplastic nodules it is probably no better than CT for detection of HCC and has a lower false-positive rate. 4. Approximately 10-30% of nodules measuring <2 cm seen only on the hepatic arterial phase at CT or MR imaging represent small HCC and vigilant surveillance imaging is required as interval growth is the best indicator of malignancy., (Copyright 2006 AASLD.)

Purpose: To retrospectively assess the usefulness of contrast material-enhanced T1-weighted magnetic resonance (MR) imaging alone and with T2-weighted MR imaging in the diagnosis of hepatocellular carcinoma (HCC)., Materials and Methods: A waiver of informed consent and institutional review board approval for this retrospective study were granted. The study was HIPAA compliant. Twenty-eight men (mean age, 49 years; range, 23-70 years) and 10 women (mean age, 53 years; range, 42-72 years) with cirrhosis underwent T2-weighted and contrast-enhanced T1-weighted MR imaging at 1.5 T within 90 days of liver transplantation. Three readers reviewed the T1-weighted images alone and then the T2-weighted and T1-weighted images together. Lesion detection, characterization, and reader confidence levels were recorded., Results: At liver explantation, 57 lesions were present in 18 patients: 19 HCCs, 33 dysplastic nodules, and five cysts. Contrast-enhanced T1-weighted imaging depicted 13 of 19 HCCs with an overall sensitivity of 68.4% (13 of 19) and specificity of 65.7% (23 of 35). The sensitivity and specificity for detection of dysplastic nodules (sensitivity, 9%; specificity, 68.4%) and HCCs (sensitivity, 68.4%; specificity, 65.7%) were nearly identical for T1-weighted images read alone or read with T2-weighted images. The only difference was the specificity for T1-weighted images read alone (65.7%) and read with T2-weighted images (62.9%). The addition of T2-weighted images altered the diagnosis in one of 90 (1.1%) cases and provided an increase in diagnostic confidence in four of 258 (1.6%) cases for independent readers and three of 90 (3.3%) cases at consensus reading., Conclusion: Contrast-enhanced T1-weighted imaging can be used as a stand-alone sequence for the diagnosis of HCC in patients with cirrhosis prior to liver transplantation., ((c) RSNA, 2006.)

Purpose: To retrospectively assess the importance and imaging appearance of small (< or = 20 mm in diameter) hepatic arterial phase-enhancing (HAPE) lesions that are occult during portal and/or equilibrium phases and at unenhanced T1- and T2-weighted magnetic resonance (MR) imaging and to determine the gross pathologic diagnosis with whole-liver explant comparison., Materials and Methods: This retrospective study was approved by the institutional review board and compliant with HIPPA. Forty-six patients with cirrhosis who underwent MR imaging and transplantation within 90 days were evaluated with breath-hold T2-weighted and volumetric three-dimensional gadolinium-enhanced gradient-echo MR imaging in the hepatic arterial, portal venous, and equilibrium phases at 1.5 T. Three readers, who were blinded to the pathologic results, retrospectively reviewed the MR images in consensus for small HAPE nodules that were occult at T2-weighted and portal and/or equilibrium phase MR imaging. Only patients with nodules that enhanced during the arterial phase were included in the final study group, which included 16 patients (12 men and four women) aged 18-66 years (median age, 51.5 years). Explanted livers were serially sliced into 5-8-mm-thick sections to evaluate dysplastic nodules and hepatocellular carcinomas (HCCs). The Fisher exact test was performed to determine whether there was a relationship between HCC and the presence of a neoplastic HAPE-only lesion. The Mann-Whitney test was used to determine if patients with at least one neoplastic HAPE-only lesion had a larger number of non-HAPE-only lesions., Results: The 16 patients had 45 HAPE-only lesions; three (7%) of which were neoplastic, including one overt HCC, one HCC arising in a dysplastic nodule, and one dysplastic nodule. None of the remaining 42 HAPE-only lesions (93%) had correlative pathologic findings. All three neoplastic lesions seen only during the arterial phase were found in eight patients with concomitant HCC, who also had an additional 13 pathologically proved nonneoplastic HAPE-only lesions. In eight patients without HCC, none of the HAPE-only lesions were neoplastic. A concomitant non-HAPE-only neoplastic lesion was not a significant (P = .2) predictor for the presence of at least one neoplastic HAPE-only lesion. There was a preliminary but insignificant (P = .13) indication that the number of non-HAPE-only lesions tends to be higher in patients with neoplastic HAPE-only lesions., Conclusion: The majority (93%) of HAPE-only lesions that are occult at T2-weighted and portal and/or equilibrium phase MR imaging are nonneoplastic, even in patients with pathologically proved HCC., (RSNA, 2005)

Purpose: To retrospectively determine whether differential temporal changes in signal intensity of the vertebral arteries, measured at a bolus-timing examination with a test dose of a gadolinium-based contrast agent, are present in patients with subclavian steal syndrome., Materials and Methods: Institutional review board exemption was obtained, and informed consent was not required for this retrospective study. The study complied with the Health Insurance Portability and Accountability Act. Twenty-five patients with known or clinically suspected atherosclerotic disease of the aortic arch and branch vessels underwent breath-hold contrast material-enhanced magnetic resonance (MR) angiography with circulation time derived from a timing examination by using a test bolus of a gadolinium-based contrast agent. Eight patients (three men and five women aged 54-80 years; mean, 70 years) had subclavian stenosis or occlusion with retrograde vertebral artery flow confirmed with time-of-flight MR angiography, nine patients (eight men and one woman aged 31-91 years; mean, 70 years) had mild to severe ostial stenosis of a single vertebral artery, and eight patients (including four men and four women aged 53-86 years; mean, 73 years) had normal vertebral arteries. The difference in time to peak signal intensity between the right and left vertebral arteries was compared among the three groups by using Fisher exact and Cochran-Mantel-Haenszel tests., Results: The delay in peak enhancement in the ipsilateral vertebral artery ranged from 2 to 4 seconds (mean, 2.5 seconds) in all eight patients with subclavian steal syndrome. In eight of nine patients with ostial vertebral artery stenosis and eight controls, both vertebral arteries filled simultaneously. The presence of unilateral delayed vertebral artery enhancement was significantly associated with retrograde flow in patients with subclavian steal syndrome, compared with patients with normal flow (P < .01) and those with ostial vertebral artery stenosis (P < .01)., Conclusion: A bolus-timing examination performed with a test bolus of the gadolinium-based contrast agent via the neck vessels that demonstrates at least a 2-second delay in peak contrast enhancement in the right or left vertebral arteries may, in the appropriate clinical setting, indicate subclavian steal syndrome., (Copyright RSNA, 2005.)

Improved therapeutic options for hepatocellular carcinoma and metastatic disease place greater demands on diagnostic and surveillance tests for liver disease. Existing diagnostic imaging techniques provide limited evaluation of tissue characteristics beyond morphology; perfusion imaging of the liver has potential to improve this shortcoming. The ability to resolve hepatic arterial and portal venous components of blood flow on a global and regional basis constitutes the primary goal of liver perfusion imaging. Earlier detection of primary and metastatic hepatic malignancies and cirrhosis may be possible on the basis of relative increases in hepatic arterial blood flow associated with these diseases. To date, liver flow scintigraphy and flow quantification at Doppler ultrasonography have focused on characterization of global abnormalities. Computed tomography (CT) and magnetic resonance (MR) imaging can provide regional and global parameters, a critical goal for tumor surveillance. Several challenges remain: reduced radiation doses associated with CT perfusion imaging, improved spatial and temporal resolution at MR imaging, accurate quantification of tissue contrast material at MR imaging, and validation of parameters obtained from fitting enhancement curves to biokinetic models, applicable to all perfusion methods. Continued progress in this new field of liver imaging may have profound implications for large patient groups at risk for liver disease.

Purpose: To compare three-dimensional (3D) mangafodipir trisodium-enhanced T1-weighted magnetic resonance (MR) cholangiography with conventional T2-weighted MR cholangiography for depiction and definition of intrahepatic biliary anatomy in liver transplant donor candidates., Materials and Methods: One hundred eight healthy liver transplant donor candidates were examined with two MR cholangiographic methods. All candidates gave written informed consent, and the study was approved by the institutional review board. First, breath-hold transverse and coronal half-Fourier single-shot turbo spin-echo and breath-hold oblique coronal heavily T2-weighted turbo spin-echo sequences were performed. Second, mangafodipir trisodium-enhanced breath-hold fat-suppressed 3D gradient-echo sequences were performed through the ducts (oblique coronal plane) and through the entire liver (transverse plane). Interpretation of biliary anatomy findings, particularly variants affecting right liver lobe biliary drainage, and degree of interpretation confidence at both 3D mangafodipir trisodium-enhanced MR cholangiography and T2-weighted MR cholangiography were recorded and compared by using the Wilcoxon signed rank test. Then, consensus interpretations of both MR image sets together were performed. Intraoperative cholangiography was the reference-standard examination for 51 subjects who underwent right lobe hepatectomy. The McNemar test was used to compare the accuracies of the individual MR techniques with that of the consensus interpretation of both image sets together and to compare each technique with intraoperative cholangiography., Results: Biliary anatomy was visualized with mangafodipir trisodium enhancement in all patients. Mangafodipir trisodium-enhanced image findings agreed with findings seen at combined interpretations significantly more often than did T2-weighted image findings (in 107 [99%] vs 88 [82%] of 108 donor candidates, P < .001). Confidence was significantly higher with the mangafodipir trisodium-enhanced images than with the T2-weighted images (mean confidence score, 4.5 vs 3.4; P < .001). In the 51 candidates who underwent intraoperative cholangiography, mangafodipir trisodium-enhanced imaging correctly depicted the biliary anatomy more often than did T2-weighted imaging (in 47 [92%] vs 43 [84%] donor candidates, P = .14), whereas the two MR imaging techniques combined correctly depicted the anatomy in 48 (94%) candidates., Conclusion: Mangafodipir trisodium-enhanced 3D MR cholangiography depicts intrahepatic biliary anatomy, especially right duct variants, more accurately than does conventional T2-weighted MR cholangiography., ((c) RSNA, 2004.)

In the absence of genetic hemochromatosis and systemic hemosiderosis, patients with cirrhosis can accumulate focal iron within regenerative or dysplastic hepatic nodules, commonly referred to as 'siderotic nodules'. Siderotic dysplastic nodules are premalignant lesions while siderotic regenerative nodules are a marker for severe viral or alcoholic cirrhosis. The relationship of hepatic iron deposition to hepatic cirrhosis and neoplasia has not been fully clarified. This article will review the current literature regarding selective iron accumulation in siderotic nodules in chronic liver disease, followed by a discussion of current MR imaging techniques for detection and characterization of these nodules., (Copyright (c) 2004 John Wiley & Sons, Ltd.)

MR imaging is useful in differentiating and characterizing renal masses. A careful evaluation of the signal characteristics and morphology of a renal mass combined with the ancillary imaging findings and patient history should assist the radiologist in making the proper diagnosis or recommending the appropriate treatment in most cases. This pictorial essay demonstrates the typical MR imaging features of common renal masses including renal cell carcinoma (RCC), oncocytoma, angiomyolipoma, metastases, transitional cell carcinoma (TCC), lymphoma, and arteriovenous malformation (AVM), and highlights several potential diagnostic pitfalls in making the proper diagnosis.

Our objective was to investigate the coexistence of vascular and biliary anatomic variants, the latter of which are known to increase the risk of biliary complications in living liver donor transplantation. A total of 108 consecutive liver donor candidates were examined by magnetic resonance (MR) imaging that included 2 MR cholangiography methods, T2-weighted MR cholangiography and mangofodipir-enhanced T1-weighted three-dimensional (3D) MR cholangiography, as well as gadolinium-enhanced MR angiography and venography of the liver. Images were interpreted by at least 2 investigators in consensus for definition of hepatic arterial, portal venous, and biliary anatomy. A subset of 51 subjects underwent laparotomy for right hepatectomy. Of the 108 subjects examined, 50 (46%) demonstrated normal hepatic artery, portal vein, and biliary anatomy. Variants of the hepatic artery were found in 27 of 108 (25%) subjects, of the portal vein in 12 of 108 (11%) subjects, and of the bile ducts in 30 of 108 (28%) subjects. Of the 27 subjects with hepatic arterial variants, 8 (30%) also had variant biliary anatomy. The association between hepatic arterial variants and biliary variants was not statistically significant (P >.5). However, of the 12 subjects with portal vein variants, 7 (58%) had biliary variants, and in 6 of 7 cases, the right posterior hepatic duct was anomalous. By chi-square analysis, the association between portal venous and biliary variants was significant (P =.012). In conclusion, over half of subjects with portal vein variants were found to have anomalous biliary anatomy, which always involved the hepatic ducts of the right lobe. The association between portal venous and biliary variants is statistically significant, while there is no significant association between hepatic arterial and biliary variants.

Purpose: To retrospectively compare quantitative and qualitative methods of assessing magnetic resonance (MR) imaging contrast enhancement as the basis for diagnosing renal malignancy., Materials and Methods: MR imaging was performed by using a gadolinium-enhanced breath-hold fat-suppressed three-dimensional T1-weighted gradient-echo sequence in 71 patients (48 men and 23 women; mean age, 62 years; age range, 26-87 years) with 93 renal lesions for which pathologic correlation was available. For quantitative measurements of enhancement, the relative increase in signal intensity values was measured by one investigator with manually defined regions of interest, and the threshold of an increase of 15% or greater was used to distinguish malignant from benign masses. For qualitative assessment, two investigators independently reviewed the subtracted images of all lesions and subjectively determined whether enhancement was present or absent. The sensitivity, specificity, and positive and negative predictive values for each method were calculated and compared. Mean (+/- standard deviation) and median values of relative enhancement were also calculated for benign and malignant lesions., Results: At pathologic analysis, 74 (80%) of the 93 lesions were malignant, and 19 (20%)-including seven oncocytomas-were benign. For diagnosing malignancy based on enhancement alone, sensitivity and specificity, respectively, were 95% (70 of 74 lesions) and 53% (10 of 19 lesions) at quantitative analysis and 99% (73 of 74 lesions) and 58% (11 of 19 lesions) at qualitative analysis. All seven oncocytomas were considered to be malignant with both methods. When the oncocytomas were excluded, specificities increased to 83% (10 of 12 lesions) and 92% (11 of 12 lesions) for the quantitative and qualitative evaluations, respectively. Three of the four malignant lesions incorrectly characterized as benign at quantitative assessment were hyperintense on unenhanced MR images; all were diagnosed correctly at qualitative evaluation., Conclusion: Image subtraction enables accurate assessment of renal tumor enhancement, particularly in the setting of masses that are hyperintense on unenhanced MR images., (Copyright RSNA, 2004)

Objective: Our aim was to evaluate adrenal adenomas in patients who underwent both unenhanced CT and chemical shift MRI to determine if adenomas can be characterized with MRI when the findings of CT are indeterminate., Materials and Methods: Between January 1999 and June 2003, 40 patients (42 adrenal masses) underwent unenhanced CT and chemical shift MRI and were retrospectively analyzed. Hounsfield units, adrenal-to-spleen chemical shift ratio, and signal-intensity index were obtained for each adrenal mass. Qualitative analysis for loss of signal in each adrenal mass on the opposed-phase images was also performed by two reviewers and compared with the quantitative analyses. A lipid-rich adenoma was diagnosed if the mass measured equal to or less than 10 H, had an adrenal-to-spleen chemical shift ratio of less than 0.71, and had a signal-intensity index of greater than 16.5% or if the mass fulfilled two of the preceding criteria and had follow-up imaging without change., Results: The sensitivities and specificities for diagnosing a lipid-rich adenoma using the qualitative, adrenal-to-spleen chemical shift ratio, signal-intensity index, and unenhanced CT attenuation analyses were 92% (33/36) and 17% (1/6), 100% (36/36) and 100% (6/6), 100% (36/36) and 67% (4/6), and 78% (28/36) and 83% (5/6), respectively. Twenty-eight (67%) lipid-rich adenomas measured equal to or less than 10 H, had an adrenal-to-spleen chemical shift ratio of less than 0.71, and had a signal-intensity index of greater than 16.5%. Eight masses (19%) measured greater than 10 H but had an adrenal-to-spleen chemical shift ratio of less than 0.71 and a signal-intensity index greater than 16.5% and were unchanged at follow-up., Conclusion: Eight (62%) of 13 adrenal adenomas measuring greater than 10 H on unenhanced CT were definitively characterized with chemical shift MRI.

Purpose: To measure the prevalence and degree of celiac artery compression during breath-hold imaging at end inspiration and end expiration in patients referred to undergo magnetic resonance (MR) imaging of the abdomen for reasons unrelated to intestinal ischemia., Materials and Methods: A series of 100 patients underwent routine MR imaging of the upper abdomen at 1.5 T; imaging included multiple dynamic contrast-enhanced fat-suppressed transverse three-dimensional spoiled gradient-echo acquisitions (3.6-4.5/1.5-1.9 [repetition time msec/echo time msec], 12 degrees flip angle). Arterial phase acquisitions were obtained during suspended respiration at end expiration (n = 50) or at end inspiration (n = 50), and venous phase acquisitions were obtained at the opposite respiratory phase. Two radiologists, blinded to patient identity and the phase of respiration, independently assessed the degree of narrowing on reconstructed oblique sagittal images. Radiologists reached consensus in 97 patients, who formed the cohort for this study. The percentage of stenosis of the celiac artery relative to its origin and the angle formed by the proximal celiac artery and the aorta were also measured in all patients. This angle and the arcsine transformation of the percentage of stenosis were compared for the two respiratory phases by using a paired Student t test. chi2 analysis was used to evaluate whether the degree of narrowing was independent of the breath-hold protocol that was used., Results: In total, 55 (57%) of 97 patients had at least mild artery narrowing at end expiration, of whom 40 (73%) had less narrowing at end inspiration and 11 (20%) had no change. The average percentage of stenosis at end expiration (21% +/- 16) was significantly higher than that at end inspiration (11% +/- 11; P <.001). At end expiration, the average celiac artery angle was significantly lower in patients with mild to severe narrowing (41 degrees +/- 19) than in those without narrowing (50 degrees +/- 19; P <.03)., Conclusion: Accentuation of celiac artery compression at end expiration can give rise to a potential pitfall of breath-hold abdominal imaging. When compression is suspected, imaging should be performed during inspiration., (Copyright RSNA, 2003.)

Objective: Our objective was to determine the frequency and MR imaging findings of nondysplastic nodules that are hyperintense on T1-weighted gradient-echo imaging in patients with cirrhosis who undergo liver transplantation., Materials and Methods: Two observers retrospectively evaluated in-phase (4-5 msec), opposed-phase gradient-echo (2.0-2.4 msec), and turbo short tau inversion recovery (STIR) MR images in 68 patients with cirrhosis--but without dysplastic nodules or hepatocellular carcinoma--who underwent MR imaging at 1.5 T within 150 days before liver transplantation. The size, number, signal characteristics, and arterial enhancement pattern of nodules that appear hyperintense on T1-weighted gradient-echo images were evaluated as well as the presence or absence of signal loss on opposed-phase imaging. These imaging findings were correlated with pathologic findings of whole explanted livers., Results: Eleven (16%) of 68 patients had at least one nondysplastic nodule that was hyperintense on T1-weighted MR imaging. Three patients had diffuse nondysplastic hyperintense nodules (>10 nodules) measuring less than 0.5 cm, and the remaining eight patients had 22 nondysplastic hyperintense nodules ranging in size from 0.5 to 2.5 cm (mean, 1.2 cm), of which 13 were isointense and nine were hypointense on turbo STIR images. No lesion lost signal on opposed-phase imaging or enhanced during the hepatic arterial phase., Conclusion: In cirrhotic patients undergoing liver transplantation, nondysplastic nodules that are hyperintense are common findings on T1-weighted gradient-echo MR imaging and do not lose signal intensity on opposed-phase imaging or enhance during the hepatic arterial phase. These nodules may be indistinguishable from dysplastic nodules.

By performing a comprehensive MR imaging examination, it is not only possible accurately to characterize and stage cystic and solid lesions of the kidney, but also to provide important preoperative information to the surgeon. In addition, MR imaging can characterize many adrenal lesions and frequently can obviate the need to obtain biopsies. The continued development and growth of MR technology combined with the current trend toward minimally invasive surgery will expand the role of MR imaging in the future.

Objective: Our purpose was to evaluate a simple, two-station, bolus-chase, peripheral MR angiography technique that relies on manual patient translation using a plastic patient-transfer board., Subjects and Methods: Twenty patients successfully completed both lower extremity MR angiography and digital subtraction angiography within a 3-month period. For MR angiography, patients were placed on the scanner table on a standard plastic patient-transfer board. We performed unenhanced and contrast-enhanced imaging at the level of the pelvis using a three-dimensional gradient-echo sequence (TR range/TE range, 3.8-4.6/1.3-1.8; flip angle range, 25-40 degrees ). Then patients were quickly pulled 350-400 mm using the transfer-board handles, and two subsequent acquisitions were obtained at the level of the thighs. For each modality, two radiologists who were unaware of correlative imaging results retrospectively scored all vessel segments as either greater than or equal to 50% stenosis or less than 50% stenosis, and interobserver agreement was determined. Using digital subtraction angiography as the standard of reference, we used consensus data to compute MR angiography sensitivity and specificity., Results: In the 261 vessel segments considered, MR angiography had a sensitivity of 75% (12/16) and a specificity of 98% (94/96) for the detection of stenosis greater than or equal to 50% from the aorta through the common femoral arteries. For the superficial and profunda femoral arteries through the popliteal arteries, these values were 97% (31/32) and 94% (34/36), respectively. MR angiography interobserver agreement for detection of stenosis was good (kappa = 0.68) for the aorta through the common femoral arteries and excellent (kappa = 0.88) for the superficial and profunda femoral arteries through the popliteal arteries. These values were comparable to those found for digital subtraction angiography (kappa = 0.67 and kappa = 0.88, respectively)., Conclusion: Stationary-table MR angiography is a useful, simple strategy for lower extremity angiography in centers without a moving table.

The sensitivity of magnetic resonance imaging (MRI) in patients who undergo transplantation for hepatocellular carcinoma (HCC) and cirrhosis is not known. We prospectively evaluated 24 patients with known HCC who underwent MRI and subsequent transplantation within 60 days (mean, 20 days). Using a phased-array coil at 1.5T, breath-hold turbo STIR and T2-weighted MR images were performed. Dynamic gadolinium-enhanced MRI was performed using a two- or three-dimensional gradient echo pulse sequence with images obtained in the hepatic arterial, portal venous, and equilibrium phases. The prospective interpretation of the MR study was directly compared with thin-section pathology evaluation of the explanted livers. All 24 patients had at least one HCC, and MR diagnosed tumor in 21 (88%) of these patients. On a lesion-by-lesion basis, MRI depicted 39 of 118 HCC for an overall sensitivity of 33%. MRI detected five (100%) of five lesions >5 cm, 20 (100%) of 20 lesions >2 cm but not exceeding 5 cm, 11 (52%) of 21 lesions between 1 and 2 cm, and three (4%) of 72 lesions <1 cm. Of the nine patients with carcinomatosis (innumerable lesions less than 1 cm), MR detected three lesions in one patient. Of the 15 dysplastic nodules found at pathology, MRI depicted a single 1.8-cm high-grade lesion, for a sensitivity of 7%. In conclusion, MRI is sensitive for the detection of HCC measuring at least 2 cm in diameter but is insensitive for the diagnosis of small HCC (<2 cm) and carcinomatosis.

Purpose: It has been proposed that there is an increased frequency of pancreatic abnormalities in patients with primary sclerosing cholangitis (PSC). Our purpose is to compare the frequency of pancreatic abnormalities detected at MRI in patients with PSC and to compare these findings with those found in a matched cohort with other liver diseases., Method: We identified 29 patients who had either a histologic or an endoscopic retrograde cholangiopancreatography diagnosis of PSC and 29 age- and gender-matched patients with liver disease without PSC who underwent MRI at 1.5 T. The protocol included breath-hold T1-weighted gradient echo, echo train, fast spin echo, T2-weighted images and dynamic gadolinium-enhanced MRI. Two blinded readers retrospectively evaluated the MR images for abnormalities of pancreatic size and morphology, T1 and T2 signal intensity, duct size and irregularities, arterial-phase contrast enhancement, focal pancreatic masses, cystic lesions, peripancreatic fluid/edema, ascites, and capsular-like rim surrounding the pancreas., Results: The prevalence of pancreatic and peripancreatic abnormalities was 10 of 29 (35%) in PSC patients and 14 of 29 (48%) in control patients. MR findings included ascites (9 PSC, 12 controls), peripancreatic edema (7 PSC, 11 controls), atrophy (4 PSC, 3 control), increased T2 signal (3 PSC, 4 controls), cystic lesions (2 PSC, 3 controls), abnormal T1 signal (1 PSC, 2 controls), and dilated pancreatic ducts (3 PSC, 2 controls). Quantitative parameters were not significantly different between PSC patients and the control subjects with pancreatic findings., Conclusion: There is no significant difference in pancreatic abnormalities detected on MRI between patients with PSC and those with other liver diseases.

Purpose: To evaluate the accuracy of magnetic resonance (MR) imaging in the preoperative evaluation of potential living renal donors who are candidates for laparoscopic nephrectomy., Materials and Methods: Twenty-eight donor candidates who underwent subsequent laparoscopic nephrectomy were examined by using a torso phased-array coil at 1.5 T. Gadolinium-enhanced MR angiograms, MR venograms, and MR urograms were obtained in all patients by using an interpolated three-dimensional T1-weighted spoiled gradient-echo sequence (3.4-6.8/1.2-2.3 [repetition time msec/echo time msec], 25 degrees -40 degrees flip angle). Interpretation of the MR images was used to assess the arterial, venous, and ureteral anatomy, as well as parenchymal masses and scarring, and findings were compared with the surgical findings in all patients. Statistical evaluation was performed, with the surgical findings as the reference standard., Results: At MR imaging, 31 of 32 renal arteries and one of three early-branching arteries were identified correctly. The correct venous anatomy was identified in 23 of 28 patients, including a single left renal vein anterior to the aorta (n = 16), retroaortic left renal vein (n = 2), circumaortic left renal vein (n = 2), and single right renal vein (n = 3). A single collecting system in all harvested kidneys was identified correctly with MR urography. Overall, MR imaging correctly depicted vascular, ureteral, and parenchymal anatomy in 21 of 28 patients. Twenty-seven of 28 patients underwent successful laparoscopic donor nephrectomy on the basis of the MR findings. One procedure was converted to open nephrectomy on the basis of complex venous anatomy not prospectively identified on the MR images. The sensitivity and positive predictive value of MR imaging in correctly determining the combined vascular, ureteral, and parenchymal anatomy in the harvested kidney were 75% (21 of 28) and 95% (21 of 22), respectively., Conclusion: Comprehensive gadolinium-enhanced MR imaging can depict the vascular anatomy, collecting system, and renal parenchyma preoperatively in patients who are candidates for laparoscopic living-donor nephrectomy., (Copyright RSNA, 2002)

Thoracic aortic atherosclerosis has been shown to be an important cause of severe morbidity and mortality. At the present time, the case of performance, detailed information obtainable, and availability make TEE the procedure of choice for the imaging of thoracic aortic atherosclerosis; however, further technical advances in MR and CT, particularly in MR plaque characterization and the use of plaque specific contrast agents, may allow for a less invasive and more complete evaluation of thoracic aortic atherosclerosis in the near future. Gadolinium-enhanced 3DMRA is the procedure of choice for the noninvasive detection of plaque in the proximal aortic arch vessels. Furthermore, both CT and MRI are better suited to evaluate penetrating atherosclerotic ulcers and their complications such as intramural hematoma, pseudoaneurysm formation, and aortic rupture.

The authors describe two cases of penetrating ulcers of the descending thoracic aorta associated with intramural hematoma of the ascending aorta. Since neither patient had evidence of diffuse thoracic aortic atherosclerosis to limit longitudinal extent of spread, it is postulated that the intramural hematoma started at the level of the penetrating ulcer and extended into the ascending aorta in a retrograde fashion. This is a potentially lethal entity, not previously described, for which the optimal clinical management is unknown.

Objective: The objective of this study was to determine the sensitivity and specificity of sonography as an aid in detecting hepatocellular carcinomas and dysplastic nodules using explantation correlation in patients with cirrhosis and no known hepatocellular carcinomas., Materials and Methods: The sonography reports of 200 patients with cirrhosis who underwent sonography and then underwent liver transplantation within 90 days were retrospectively reviewed for focal solid liver lesions. All focal solid masses detected on sonography were considered possible hepatocellular carcinomas. The sonographic findings were compared with thin-section explanted liver pathologic results., Results: Twenty-seven patients (13.5%) had hepatocellular carcinoma at explantation, including four patients with diffuse, multifocal tumors. Eight of the 39 lesions were detected on sonography for a patient sensitivity of 29.6% and a lesion sensitivity of 20.5%. Sonography revealed three (75%) of four hepatocellular carcinomas larger than 5 cm in diameter, one (50%) of two hepatocellular carcinomas with diameters of 3.1-5.0 cm, one (20%) of five hepatocellular carcinomas with diameters of 2.1-3.0 cm, three (13.6%) of 22 hepatocellular carcinomas with diameters of 1-2 cm, and no lesions with diameters smaller than 1 cm. Forty-two patients (21%) had a total of 126 dysplastic nodules including two patients with innumerable lesions. Sonography depicted only two dysplastic nodules, for a patient sensitivity of 4.8% and a lesion sensitivity of 1.6%. The overall specificity of sonography for either hepatocellular carcinomas or dysplastic nodules was 96%., Conclusion: Sonography has low sensitivity but high specificity in revealing hepatocellular carcinomas and dysplastic nodules in patients with a cirrhotic liver requiring liver transplantation. In these patients, sonography should not be the sole imaging modality used for lesion detection before transplantation.

Using receiver-operating characteristic (ROC) methodology, the ability to diagnose acute appendicitis with computed tomography (CT) images displayed at varying levels of lossy compression was evaluated. Nine sequential images over the ileocecal region were obtained from 53 consecutive patients with right lower quadrant pain who were clinically suspected to have acute appendicitis. Thirty were proven surgically to have acute appendicitis, alternative diagnoses confirmed in 23. The image sets were subjected to a lossy wavelet-based compression algorithm "Embedded Predictive Wavelet Image Coder" (EPWIC). Compression levels were: none, 8:1, 16:1, and 24:1, resulting in 4 sets of images per patient. Image sets were randomized and evaluated separately by 4 body radiologists on a 1,024 x 768-pixel SVGA color PC monitor in 512 x 512 format. The readers were aware of the clinical suspicion of appendicitis but were unaware of the positive fraction of cases. Individual and combined reader ROC and c2 analyses of sensitivity, specificity, and accuracy were determined. For all readers, sensitivity decreases at 16:1 and 24:1 levels (P <0.01, P <0.001, respectively). Accuracy decreased at 24:1 levels (P <0.01). Specificity was unaffected. By ROC analysis there was statistically significantly decreased area under the curve at 24:1 levels (P <0.02) as compared with uncompressed images. Finite levels of lossy wavelet compression may be applied to CT images without compromising diagnostic performance.

Rationale and Objectives: The authors performed this study to determine whether, on the basis of the vascular profile, low-grade siderotic dysplastic nodules are premalignant lesions., Materials and Methods: The authors used a monoclonal antibody specific for smooth muscle actin to stain 18 siderotic low-grade dysplastic nodules (mean size, 0.7 cm) from nine patients. Two pathologists counted the number of unpaired arteries per high-power field in siderotic dysplastic nodules and background siderotic regenerative nodules by using two techniques (conventional and hot spot)., Results: The number of unpaired arteries seen with the conventional counting technique in low-grade siderotic dysplastic nodules (range, 1-14; mean, 3.8) was significantly greater (P = .004) than that seen in background siderotic regenerative nodules (range, 0-3; mean, 1.2). Similarly, the number of unpaired arteries seen with the hot spot technique in low-grade siderotic dysplastic nodules (range, 0-14; mean, 5.2) was significantly greater (P = .005) than that seen in background siderotic regenerative nodules (range, 0-6; mean, 1.9)., Conclusion: On the basis of the vascular profile, low-grade siderotic dysplastic nodules should be considered premalignant lesions. Further research is needed to help differentiate these lesions from siderotic regenerative nodules with magnetic resonance imaging.

Objective: The purpose of this study was to determine the CT findings in acute gangrenous cholecystitis., Materials and Methods: Four observers retrospectively reviewed CT scans in 75 patients (23 with acute gangrenous cholecystitis, 25 with acute non-gangrenous cholecystitis, and 27 without cholecystitis). The following findings were evaluated: distention, mural thickening, wall enhancement, irregular wall, wall striation, intraluminal membranes, pericholecystic inflammation, gallstones, pericholecystic fluid, enhancement of liver parenchyma, pericholecystic abscess, and gas in the wall or lumen. Sensitivity and specificity of CT for gangrenous cholecystitis and for each finding were calculated. Two reviewers in consensus measured gallbladder dimension and wall thickness. Logistic regression models were used to predict gangrenous versus non-gangrenous cholecystitis., Results: Sensitivity, specificity, and accuracy of CT for acute cholecystitis were 91.7%, 99.1%, and 94.3%, respectively, and for acute gangrenous cholecystitis were 29.3%, 96.0%, and 64.1%, respectively. Findings with the highest specificity for gangrenous cholecystitis were gas in the wall or lumen (100%), intraluminal membranes (99.5%), irregular or absent wall (97.6%), and abscess (96.6%). The difference between the mean gallbladder wall thickness and the short-axis dimension for the two groups with cholecystitis was statistically significant. In three patients with gangrenous cholecystitis, no mural enhancement was seen. Pericholecystic fluid also achieved statistical significance for the diagnosis of gangrene. Multivariate logistic regression analysis showed that the overall accuracy of CT for gangrenous cholecystitis was 86.7%., Conclusion: CT findings most specific for acute gangrenous cholecystitis are gas in the wall or lumen, intraluminal membranes, irregular wall, and pericholecystic abscess. Gangrenous cholecystitis is associated with a lack of mural enhancement, pericholecystic fluid, and a greater degree of gallbladder distention and wall thickening.

Objective: Our purpose was to evaluate a comprehensive MR imaging strategy for recipients of liver transplants that relies on dynamic interpolated three-dimensional (3D) MR imaging for simultaneous vascular, parenchymal, and extrahepatic imaging., Materials and Methods: Twenty-three consecutive adult patients underwent 30 MR imaging examinations between 2 days and 99 months (mean, 15 months) after transplantation using a breath-hold 3D gradient-echo sequence (TR range/TE range, 3.7-4.7/1.8-1.9; flip angle, 12-30 degrees ) with an intermittent fat-saturation pulse and interpolation in the section-select direction to enable pixel size 3 mm or less in all dimensions. Unenhanced and triphasic contrast-enhanced 3D imaging (average dose, 0.13 mmol/kg of gadopentetate dimeglumine) was performed. A subset of patients (n = 13) also underwent MR cholangiopancreatography using half-Fourier single-shot turbo spin-echo imaging. MR imaging examinations were correlated with digital subtraction angiography (n = 8), contrast-enhanced cholangiography (n = 9), sonography (n = 13), and histopathology (n = 14)., Results: MR imaging revealed abnormal findings in 27 (90%) of 30 examinations, including vascular disease in nine, biliary complications in four, and evidence of intra- or extra-hepatic hepatocellular carcinoma recurrence in six. Digital subtraction angiography confirmed seven MR angiography examinations but suggested disease overestimation in one. Contrast-enhanced cholangiography confirmed findings of MR cholangiopancreatography in seven cases but suggested disease underestimation in two., Conclusion: Dynamic interpolated 3D MR imaging combined with dedicated MR cholangiopancreatography can provide a comprehensive assessment of vascular, biliary, parenchymal, and extrahepatic complications in most recipients of liver transplants.

Recent improvements in MR technology have enabled the development of volumetric three-dimensional (3D) imaging methods for fat-suppressed T1-weighted images of the entire upper abdomen with pixel sizes of approximately 2 mm in all dimensions and with acquisition times of less than 25 seconds for breath-hold imaging. When performed with a timing scheme, dynamic contrast-enhanced volumetric imaging of the liver can be performed with selective imaging during the arterial phase and portal venous phase of enhancement. The volumetric data sets can be reconstructed in any oblique plane, enabling improved detection, localization, and characterization of small liver lesions. The combination of high-resolution isotropic pixels and accurate timing also permits angiographic reconstructions of the 3D images, producing MR angiography and venography that can be useful in therapeutic planning, such as for catheter-based interventions or surgical resections or transplantation. Additionally, with use of a hepatobiliary contrast agent such as mangafodipir, T1-weighted volumetric MR cholangiography can be performed in patients with nonobstructed systems for depiction of intrahepatic biliary anatomy.

Purpose: To develop a low-dose magnetic resonance (MR) renographic method performed with and without an angiotensin converting enzyme (ACE) inhibitor and in conjunction with gadolinium-enhanced MR angiography in patients with suspected renovascular disease., Materials and Methods: Thirty-two patients underwent MR renography (turbo fast low-angle shot sequence: repetition time, 5 msec; echo time, 2.3 msec; flip angle, 15 degrees; one coronal image acquired every 2 seconds for 4 minutes) following intravenous injection of 2 mL of gadopentetate dimeglumine, which was repeated following intravenous injection of an ACE inhibitor. Contrast material-enhanced MR angiography was also performed. On the basis of renographic findings, renal cortex and renal medulla enhancement curves and normalized enhancement ratios were analyzed., Results: The cortex and medulla showed an early transient period of enhancement within 20 seconds (vascular phase). During 1-2 minutes, a second, gradual increase in medullary enhancement, reflecting transit of filtered contrast material, was observed that was significantly greater in patients with a serum creatinine level less than 2 mg/dL (177 micromol/L) than in those with a level of 2 mg/dL or greater (P < .01). After injection of the ACE inhibitor, patients with elevated creatinine levels showed low renal medullary enhancement regardless of the presence of renal artery stenosis (RAS). However, in patients with creatinine less than 2 mg/dL, medullary enhancement ratios after injection of the ACE inhibitor were consistently lower in patients with RAS of 50% or greater than in those without stenosis (P = .02 to .08)., Conclusion: Low-dose MR renography can be performed in the clinical setting before and after injection of an ACE inhibitor, and its potential use for evaluating decreased renal function as a consequence of RAS is promising.

Acquired communication between the aorta and the pulmonary artery is a rare phenomenon. We describe two patients with a thoracic aortic aneurysm in whom the diagnosis of a communication with the pulmonary artery was first made on transthoracic echocardiography and then more completely elucidated by means of multiple imaging modalities: transesophageal echocardiography, epiaortic ultrasound, computed tomography, and magnetic resonance imaging. Representative images from these complementary studies are presented. A successful repair of the fistula was subsequently accomplished in both patients.

Transesophageal echocardiography (TEE) is the procedure of choice for identifying aortic atheromas, which may result in stroke, transient ischemic attack and peripheral embolization. However, because of anatomic constraints, the innominate artery may not be visualized. We investigated gadolinium-enhanced MR angiography (MRA) as an alternative technique for evaluation of suspected atheromas of the innominate artery. From a retrospective review of 520 examinations, we identified five patients who had innominate artery atheromas diagnosed prospectively with gadolinium-enhanced MRA who also underwent TEE within 1 month. A total of 10 innominate artery atheromas were demonstrated on MRA; none of these were visualized on TEE. One patient had three atheromas, two patients had two atheromas and three patients had one atheroma. They ranged in size from 3 mm to 1.5 cm (mean 6.5 mm). One atheroma was flat, two were filiform, and seven were protruding. Gadolinium-enhanced MRA is superior to TEE for the diagnosis of atheromas of the innominate artery. In the setting of right cerebral or right arm embolization, when no source is seen in the arch on TEE, gadolinium-enhanced MRA should be considered.

Objective: Our aim was to investigate the feasibility of MR imaging as a comprehensive preoperative imaging test for examination of liver donor candidates for adult-to-adult right lobe transplantation., Subjects and Methods: Twenty-five consecutive donor candidates were examined at 1.5 T using a torso phased array coil with breath-hold T1- and T2-weighted imaging of the abdomen, MR cholangiography using T2-weighted turbo spin-echo imaging, and MR angiography and venography of the liver using two interpolated three-dimensional spoiled gradient-echo sequences (average dose of gadolinium contrast material, 0.17 mmol/kg). Images were interpreted for liver parenchymal and extrahepatic abnormalities; measurements of right and left lobe liver volumes; definition of hepatic arterial, portal venous, and hepatic venous anatomy; and definition of the biliary branching pattern. Findings were compared with those of conventional angiography in 13 patients, 11 of whom also had surgical findings for comparison., Results: Nine patients were excluded as candidates for donation on the basis of MR imaging findings that included parenchymal or extrahepatic abnormalities in five patients, vascular anomalies in two, and biliary anomalies in three. Two patients who did not undergo surgery underwent conventional angiography that confirmed MR angiographic findings except for a small (<2 mm) accessory left hepatic artery missed on MR imaging. Of the nine patients who underwent successful right hepatectomy, all MR imaging findings were corroborated intraoperatively. In two patients, right hepatectomy was aborted at laparotomy because of intraoperative cholangiography findings; in one of them, the biliary finding was unsuspected on MR imaging., Conclusion: A comprehensive MR imaging examination has the potential to serve as the sole preoperative imaging modality for living adult-to-adult liver donor candidates provided improvements in definition of intrahepatic biliary anatomy can be achieved.

Purpose: To determine the sensitivity and specificity of magnetic resonance (MR) imaging for detection of hepatocellular carcinoma (HCC) and dysplastic nodules (DNs) by using explantation correlation in patients with cirrhosis and no known HCC., Materials and Methods: Seventy-one patients without a known history of HCC who underwent MR imaging and subsequent transplantation within 90 days were examined. Breath-hold turbo short inversion time inversion-recovery and/or T2-weighted turbo spin-echo MR images were obtained. Dynamic two- or three-dimensional gadolinium-enhanced gradient-echo MR images were obtained in the hepatic arterial, portal venous, and equilibrium phases. Prospective MR image interpretations were compared directly with explanted liver pathologic results., Results: Eleven (15%) of 71 patients had hepatic malignancies; MR imaging enabled diagnosis of tumor in six (54%) of 11 patients. On a lesion-by-lesion basis, MR imaging depicted 11 of 20 hepatic neoplasms, for an overall sensitivity of 55%. MR imaging depicted four (80%) of five lesions larger than 2 cm, six (50%) of 12 lesions 1-2 cm, and one (33%) of three lesions smaller than 1 cm. MR imaging depicted only nine (15%) of 59 DNS: The specificities of MR imaging for detection of HCC and DNs on a per patient basis were 60 (86%) of 70 patients and 53 (85%) of 62 patients, respectively., Conclusion: MR imaging is insensitive for the diagnosis of small (<2-cm) HCCs and DNS:

Purpose: To assess the accuracy of an interpolated breath-hold T1-weighted three-dimensional (3D) gradient-echo (GRE) magnetic resonance (MR) imaging sequence with near-isotropic pixel size (

Purpose: To determine the sensitivity of magnetic resonance (MR) imaging for detection of siderotic nodules in patients with cirrhosis and whether the frequency of hepatocellular carcinoma (HCC) and dysplastic nodules is greater if siderotic nodules are present., Materials and Methods: MR imaging (1.5 T) was performed within 0-117 days (mean, 30 days) before liver transplantation in 77 patients. Two readers retrospectively evaluated gradient-echo (GRE) (echo time [TE], > or = 9 and 4-5 msec) and turbo short inversion time inversion-recovery or T2-weighted images for low-signal-intensity nodules. Whole-explant pathologic correlation was available in every case., Results: At explantation, 28 (36%) of 77 patients had HCC, 25 (32%) had dysplastic nodules, and nine (12%) had both; 35 (45%) patients had siderotic nodules. The sensitivity of GRE imaging with 9-msec or longer TE for the detection of siderotic nodules was 80% (28 of 35) but decreased to 31% (11 of 35) with 4-5-msec TE. Frequency of HCC was not significantly higher (P =.27) in patients with (43% [15 of 35]) than in patients without (31% [13 of 42]) siderotic nodules. Frequency of dysplastic nodules also was not significantly higher (P =.42) in patients with (37% [13 of 35]) than in patients without (29% [12 of 42]) siderotic nodules., Conclusion: Sensitivity of MR imaging for the detection of siderotic nodules was improved with use of GRE pulse sequences with longer TEs of 9 msec or greater (80%) versus 4-5 msec (31%); however, there was no significant increased frequency of HCC or dysplastic nodules in patients with pathologically proved siderotic nodules.

Objective: To determine if iron containing "siderotic" nodules detected at magnetic resonance (MR) imaging are regenerative (RN) or dysplastic (DN) and to attempt to identify features that may distinguish them., Material and Methods: MR imaging (1.5 T) was performed on 77 cirrhotic patients who underwent orthotopic liver transplantation within 0-117 days (mean 30 days) of MR imaging. Two readers retrospectively evaluated breath-hold gradient-echo pulse sequences (echo time > or =9.0 ms, flip angle < or =45 degrees) for the presence of hypointense nodules, which were classified as micronodular (< or =3 mm), macronodular (>3 mm), or mixed. Nodule distribution was classified as focal (<5), scattered (5-20), or diffuse (>20) per slice. Thin section pathologic correlation was available in all cases, and Prussian blue iron stains were performed., Results: Of 35 patients with pathologically proven siderotic nodules, 10 (29%) had at least 2 siderotic DN. MR detected siderotic nodules in 10 of 10 (100%) patients with siderotic DN and RN, and in 18 of 25 patients (72%) with siderotic RN only., Conclusion: Siderotic RN cannot be reliably distinguished from siderotic DN with MR imaging, and therefore the widely used term "siderotic regenerative nodule" should be avoided and replaced by "siderotic nodule."

Purpose: The purpose of this work was to determine the sensitivity of hepatic digital subtraction arteriography (DSA) for the detection of hepatocellular carcinoma (HCC) and dysplastic nodules (DNs) when compared with pathological findings from whole liver explants., Method: Twenty-one patients 30-72 years old (mean 54 years) with cirrhosis and known or clinically suspected HCC (20 prior to chemoembolization) underwent hepatic DSA with subsequent transplantation within 80 days (mean 32 days). The prospective DSA report was compared with pathologic findings from explanted livers., Results: Overall, DSA detected 31 of 95 HCC lesions for a sensitivity of 33%. Of these 31 lesions, 28 were hypervascular and 3 were hypovascular. DSA detected all six HCCs measuring >5 cm, all six HCCs measuring 3-5 cm, and all five HCCs 2-3 cm, resulting in a sensitivity of 100% (17/17) for HCC >2 cm. DSA detected 7 of 18 HCCs measuring 1-2 cm (sensitivity 39%) and 7 of 60 HCCs < or =1 cm (sensitivity 12%). Overall sensitivity for DSA in detection of HCC < or =2 cm was 18% (14/78 lesions). None of 17 DNs (0.2-1.5 cm in size) was identified on DSA., Conclusion: DSA is insensitive to small HCC (< or =2 cm), carcinomatosis arising within nodules, and DN.

Purpose: To evaluate the feasibility, reproducibility, and technical quality of a dynamic contrast material-enhanced isotropic three-dimensional (3D) volumetric interpolated breath-hold hepatic magnetic resonance (MR) imaging examination., Materials and Methods: Fifty patients underwent 3D spoiled gradient-echo imaging (4.2/1.8 [repetition time msec/echo time msec]; flip angle, 12 degrees; interpolation in three directions; intermittent fat saturation; pixel size

Cirrhosis is a progressive, diffuse process of liver fibrosis that is characterized by architectural distortion and the development of a spectrum of nodules ranging from benign regenerative nodules to premalignant dysplastic nodules to overtly malignant hepatocellular carcinoma. The purpose of this essay is to demonstrate the ex vivo MR and pathology findings of these nodules as well as other masses that can be seen in the cirrhotic liver. The optimal conditions under which ex vivo imaging can be performed allow greater spatial resolution than that achieved with in vivo imaging, without artifacts that may degrade image quality. Clearly, contrast-enhanced MRI is essential for both the diagnosis and the characterization of focal lesions in the cirrhotic liver. However, the use of ex vivo imaging precludes the evaluation of these important in vivo pulse sequences.

Objective: We investigated the usefulness of phase-contrast MR imaging to measure renal artery velocity waveforms as an adjunct to renal MR angiography. We also examined whether an angiotensin-converting enzyme (ACE) inhibitor improves the diagnostic accuracy of waveform analysis., Subjects and Methods: Thirty-five patients referred for MR angiography of renal arteries underwent non-breath-hold oblique sagittal velocity-encoded phase-contrast MR imaging through both renal hila (TR/TE, 24/5; flip angle, 30 degrees; signal averages, two; encoding velocity, 75 cm/sec) before and after i.v. administration of an ACE inhibitor (enalaprilat). We analyzed velocity waveforms using established Doppler sonographic criteria. A timing examination with a test bolus of gadolinium contrast material was performed to ensure optimal arterial enhancement during breath-hold gadolinium-enhanced three-dimensional gradient-echo MR angiography., Results: MR phase-contrast waveform pattern analysis was 50% (9/18) sensitive and 78% (40/51) specific for the detection of renal artery stenosis equal to or greater than 60% as shown on MR angiography. Sensitivity (67%, 12/18) and specificity (84%, 42/50) increased slightly, but not significantly, after i.v. administration of an ACE inhibitor. Also, the accuracy of quantitative criteria such as acceleration time and acceleration index did not improve after the administration of ACE inhibitor., Conclusion: Renal hilar velocity waveforms, measured using non-breath-hold MR phase-contrast techniques with or without an ACE inhibitor, are insufficiently accurate to use in predicting renal artery stenosis.