| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
1
The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns
Hopkins University School of Medicine, 600 N. Wolfe St., Baltimore, MD
21287.
2
Department of Radiology, Duke University Medical Center, Box 3808, Durham, NC
27710.
3
Department of Surgery, Johns Hopkins University School of Medicine, Baltimore,
MD 21287.
4
Department of Surgery, Duke University Medical Center, Durham, NC 27710.
Received January 11, 2000;
accepted after revision April 10, 2000.
Address correspondence to D. A. Bluemke.
Abstract
 Top Abstract IntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
SUBJECTS AND METHODS. Patients with known or suspected hepatic lesions who were eligible for surgery underwent dual-phase helical CT at 20 and 70 sec after the start of contrast material injection and phased array MR imaging using fast spin-echo T2-weighted imaging and gradient-echo T1-weighted imaging before and after ferumoxides infusion of 0.56 mg of iron per kilogram of body weight. Three observers who were unaware of the surgical findings separately reviewed the CT scans and unenhanced and enhanced MR images of 24 patients who completed the protocol. The observers' findings were compared with results obtained at surgery using intraoperative sonography and having histopathologic confirmation. Statistical analysis was performed using a segment-by-segment analysis.
RESULTS. Eighty-two lesions were found at surgery. The sensitivity of CT, unenhanced MR imaging, and enhanced MR imaging for blinded observers was 60.4%, 62.0%, and 68.2%, respectively. The specificity was 89.2%, 81.9%, and 81.6%, respectively. Five lesions in three patients were not detected preoperatively using any of the techniques. MR imaging found additional lesions not detected on CT in four patients; CT detected one additional lesion not seen on MR imaging.
CONCLUSION. Ferumoxides-enhanced MR imaging of the liver shows a trend toward increased sensitivity compared with dual-phase helical CT. Specificity of helical CT was superior to that of enhanced MR imaging for most observers.
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
Superparamagnetic iron oxides are particulate agents for MR imaging that are taken up by the Kupffer's cells of the liver. Iron oxide shows a strong susceptibility effect resulting in decreased signal in the normal liver on both T2- and T1-weighted images [10]. Metastatic tumor deposits show relatively little signal change after iron oxide administration because of altered phagocytic distribution. Several studies have shown excellent results of ferumoxides-enhanced imaging compared with unenhanced MR imaging and nonhelical or incremental CT [11, 12]. Seneterre et al. [1] compared ferumoxides-enhanced MR imaging with CT during arterial portography, showing comparable accuracy of the two methods.
Because of various techniques, contrast doses, and advances in technologic imaging, relatively little is known of the comparison of dual-phase helical CT with MR imaging after ferumoxides administration in the same patient population. The purpose of this study was to compare hepatic lesion detection of these two imaging methods in a group of patients with pathologically proven lesions.
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
Thirty-two patients were enrolled in the study. Their mean age was 62 years (range, 30-76 years); 17 (53%) were men and 15 (47%) were women. Their mean weight was 74.2 kg. Twenty-six patients completed the entire protocol and underwent surgery. The other four patients were found to have unresectable liver disease after preoperative MR imaging or CT. Of the 26 patients completing the protocol, primary tumor diagnoses were colorectal carcinoma (n = 20), soft-tissue sarcoma (n = 2), pancreatic adenocarcinoma (n = 1), cholangiocarcinoma (n = 1), breast cancer (n = 1), and adenocarcinoma with unknown primary cause (n = 1).
MR Imaging
All MR imaging was performed on 1.5-T MR scanners (Signa; General Electric
Medical Systems, Milwaukee, WI). Phased array surface coils were used in all
patients for signal reception. Before injection of the contrast agent, fast
spin-echo T2-weighted images (TR range/TE, 3500-6000/102) with an echo train
length of 16, four signal averages, a matrix of 256 x 256, chemical
shift fat suppression with manual tuning of the fat-suppression pulse, and
7-mm slice thickness with zero gap (interleaved acquisition) were obtained. In
addition, T1-weighted fast multiplanar spoiled gradient-echo images
(150-200/4.4, 80° flip angle) with one signal average, a matrix of 256
x 128, 7-mm slice thickness, and zero gap (interleaved) were obtained.
T1-weighted images were obtained during a breath-hold. Both T1-and T2-weighted
images were obtained in the axial plane. The field of view was 32-40 cm and
was adjusted for patient size. A three-quarter field of view was used in the
phase-encoding direction.
After the unenhanced (baseline) images were obtained, patients were removed from the MR scanner. For each patient, 0.56 mg (0.10 µmol) of iron (0.05 mL, Feridex I.V.; Berlex Laboratories, Wayne, NJ) per kilogram of body weight, diluted in 100 mL of a 5% dextrose solution was infused IV over 30 min. The drug was administered through a 5-µ filter, at a rate of 2-4 mL/min. After the drug administration, patients returned to the same MR scanner for contrast-enhanced imaging. Identical pulse sequences were used both before and after contrast administration. MR scanning was completed within 3 hr after the start of the Feridex I.V. infusion.
CT
Dual-phase helical CT imaging was performed on a Somatom Plus 4 scanner
(Siemens Medical Systems, Iselin, NJ) or a HiSpeed scanner (General Electric
Medical Systems). Although most patients probably had
"hypovascular" metastases (e.g., metastases caused by colon
cancer), dual-phase scanning was performed as the routine for all presurgical
patients. This was thought to potentially improve lesion characterization and
also to identify atypical lesions. Scanning parameters on the Somatom scanner
were 120 kVp, 210 mA, 5-mm collimation, table speed of 5-7.5 mm/sec (pitch of
1-1.5 adjusted on the basis of patient size and breath-hold capacity), 5-mm
reconstruction interval, and 1-sec scanning time. Scanning parameters on the
HiSpeed scanner were 140 kVp, 160-190 mA, 5-mm collimation, a table speed of
5-7.5 mm/sec (pitch of 1-1.5), and a 5-mm reconstruction interval. The
arterial phase of scanning started 20 sec after the start of injection of 150
mL of 300 mg I/mL of a nonionic contrast medium (iohexol [Omnipaque], Nycomed,
Princeton, NJ [n = 24]; or iopamidol [Isovue], Bracco, Princeton, NJ,
[n = 8]) injected at 4 mL/sec. The portal phase of scanning began 70
sec after the start of contrast injection. CT images were filmed using liver
windows with the institutional standard window and width settings.
Intraoperative Sonography and Surgery
The combination of intraoperative sonography and careful surgical palpation
and inspection of the liver together with histopathologic findings constituted
the gold standard. All surgery was performed by one experienced hepatobiliary
surgeon at each participating center. Before surgery, imaging findings on CT
and MR imaging were jointly reviewed by the radiology and surgical staff so
that a one-to-one correlation between preoperative and surgical findings was
performed. At the time of surgery, all patients underwent intraoperative
sonography of the liver by an experienced radiologist and surgeon with the
assistance of a sonographer using dedicated intraoperative sonography probes.
Lesions were recorded on standard templates indicating their size and
segmental location. In resected segments, histopathologic findings were
reviewed to determine the final diagnosis. In nonresected segments, biopsy of
lesions was performed.
The average time between the CT and MR imaging was 4 days (range, 1-17 days). The average time between surgery and the initial imaging study (CT or MR imaging) was 9 days (minimum, 2 days; maximum, 35 days).
Image Analysis
Three observers participated who were unaware of patient identification and
history and who were at institutions other than where the MR imaging, CT, and
surgery were performed. All observers were experienced in interpreting both CT
and MR images. Hard-copy images were reviewed for both CT and MR images. The
CT (combined arterial and portal phase images), unenhanced MR imaging, and
enhanced MR imaging examinations were separated and masked for any identifying
information. The three examinations were then shown in random order to the
blinded observers. A standardized template for each examination was completed
on which the interpreter indicated the segmental location of the lesion. The
lesion size was recorded and whether the lesion was benign, malignant, or
indeterminate. A diagnostic confidence in the overall interpretation was also
assigned from 1 (very low) to 5 (very high). A correctly scored lesion thus
required identification of the lesion and determination of its correct
segmental location.
Two observers performed "combined technique" interpretations using the same templates and scoring system. These observers were aware of the patient identification and history and reviewed both the CT and MR imaging findings (unenhanced and contrast-enhanced) together.
Statistical Analysis
CT, unenhanced MR imaging, and enhanced MR imaging results were evaluated
by an experienced biostatistician using SAS 6.12 software (SAS Institute,
Cary, NC) or Excel software (Microsoft, Redmond, WA). The observers'
interpretations were compared with the gold standard of intraoperative
sonography, surgery, and histopathologic examination. Analysis was on a
per-segment basis, with each segment contributing only a single data point. If
a lesion crossed segmental boundaries, the lesion was assigned to the segment
with the greatest involvement. Sensitivity, specificity, and accuracy of CT
and MR imaging were calculated for each interpreter. Values for p
were calculated from a two-tailed test of correlated proportions (the McNemar
test) and were considered statistically significant at less than 0.05; a trend
was defined as a p value between 0.05 and 0.10. Statistical
differences in accuracy between contrast-enhanced MR imaging and CT were
analyzed adjusting for clustering of data within the same patient (i.e., each
8 liver segments are clustered in the 1 patient). This was performed by
estimating an intraclass correlation among the segments within patients for
all data cells [13]. Agreement
between blinded observers was assessed using the kappa statistic and is
reported in the following text as kappa plus or minus standard error.
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
In two patients, too many lesions (>15) were found for one-to-one correlation between surgical findings and preoperative imaging. At surgery, arterial infusion pumps were placed. These patients were subsequently excluded from further data analysis.
As determined by the gold standard of surgery, intraoperative sonography, and histopathologic analysis, 82 evaluable lesions were present in 24 patients (average, 3.4 lesions per patient). Eighteen lesions (22%) were smaller than 1 cm, 47 lesions (57%) were 1-3 cm, and 17 lesions (21%) were greater than 3 cm. Seventy-one lesions were metastases (52 colon metastases, 13 pancreatic metastases, 2 cholangiocarcinoma intrahepatic metastases, 2 breast metastases, and 2 sarcoma metastases). Eleven lesions were benign (6 cysts, 4 hemangiomas, and 1 benign with indeterminate histology).
Blinded Interpretations
The sensitivity, specificity, and accuracy for CT, unenhanced MR imaging,
and enhanced MR imaging are shown in Table
1. For sensitivity, enhanced MR imaging was superior to unenhanced
MR imaging and CT (68.2% versus 62.0% and 60.4%, respectively), although this
difference was not statistically significant (p = 0.06, 0.07, and 0.6
for observers 1, 2, and 3, respectively). When the pooled estimate of
sensitivity was calculated on the basis of the majority observation (2/3
observers in agreement), there also was no significant difference between the
techniques.
|
For specificity, CT was superior to unenhanced MR imaging and enhanced MR imaging (p < 0.05) for observer 1. For observer 2, CT was statistically superior to enhanced MR imaging and unenhanced MR imaging (p < 0.05). For observer 3, CT was superior to unenhanced MR imaging (p < 0.05). Overall, a trend was seen toward increased specificity for CT compared with both enhanced MR imaging and unenhanced MR imaging that was consistent for all observers.
For all observers, no significant difference existed in overall accuracy of CT and enhanced MR imaging interpretations. Kappa values for observers for CT, unenhanced MR imaging, and enhanced MR imaging were similar for all observers (0.497 ± 0.059, 0.511 ± 0.051, 0.512 ± 0.049, respectively), indicating moderate agreement between observers.
Diagnostic confidence was rated on a scale of 1 (very low) to 5 (very high) by each observer for each case (Table 2). No statistical difference was seen between paired combinations of examinations (e.g., CT versus unenhanced MR imaging or enhanced MR imaging) among observers.
|
Interpretation of Combined Imaging Techniques
Two observers reviewed all the CT scans, enhanced MR images, unenhanced MR
images, and intraoperative sonography examinations. For these interpretations,
the clinical histories were also available. The combined technique results
paralleled those of the blinded observers, with enhanced MR imaging showing
greater sensitivity than unenhanced MR imaging and CT (Tables
3 and
4). Accuracy was similar (91.7%
for enhanced MR imaging, 90.1% for unenhanced MR imaging, and 87.5% for CT)
for all techniques.
|
|
Five lesions in three patients were not detected preoperatively by any of the techniques. In one patient with colorectal metastases, CT, enhanced MR imaging, and unenhanced MR imaging detected three lesions ranging in size from 10 to 40 mm. At surgery, two additional malignant lesions measuring 3 and 6 mm were found. These lesions could not be seen retrospectively on the presurgical images. These small lesions were contained in a resected liver segment, so the surgical plan was not altered. In a second patient with colorectal carcinoma, a single 39-mm malignant lesion was detected on CT, unenhanced MR imaging, and enhanced MR imaging. At surgery two additional wedge resections were performed for lesions that were 15 and 22 mm in size adjacent to the liver capsule. Both lesions were benign, showing areas of necrosis and chronic inflammation. A third patient with colorectal carcinoma had a 50 x 38 x 30 mm tumor in segment V on CT, unenhanced MR imaging, and enhanced MR imaging. At surgery, an additional 20-mm nodule was detected in the resected segment on intraoperative sonography. Retrospective evaluation of the pre-operative images did not reveal the lesion.
In four patients, MR images detected additional lesions not seen on CT that were confirmed at surgery (Fig. 1A,1B). In one of these four patients, the additional lesion was detected on unenhanced MR imaging only; one patient had the extra lesions detected on enhanced MR imaging only; in the other two patients, both enhanced and unenhanced MR imaging detected the additional lesion. However, in one of these four patients, a lesion was detected on both unenhanced MR imaging and enhanced MR imaging that was not confirmed at surgery, indicating a false-positive diagnosis.
|
|
In one patient, an additional lesion was seen on CT that was not detected on MR imaging. This lesion was a benign hemangioma at surgery. In the same patient, CT showed three additional lesions, but no abnormality was found on MR imaging or at surgery (Fig. 2A,2B,2C,2D). These lesions were classified as perfusion abnormalities. In one other patient, CT detected an additional lesion that was not seen on unenhanced MR imaging or enhanced MR imaging, but no lesion was found at surgery, indicating a false-positive finding.
|
|
|
|
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
We attempted to optimize both CT and MR imaging methods during the course of the study. For example, the helical CT technique used thin collimation (5 mm) with imaging during the arterial and portal phases of enhancement. The MR imaging was performed using high-field-strength magnets (1.5-T) and a 7-mm slice thickness with zero gap. Fat-suppressed fast spin-echo T2-weighted images have generally been shown to have high efficacy for lesion detection [14]. In addition, phased array surface coils were used to improve the signal-to-noise ratio. Nevertheless, advances in MR pulse sequence design and ever more rapid CT methods continue to improve the image quality of both techniques.
We are aware of one other study in which dual-phase helical CT was also compared with ferumoxides-enhanced MR imaging. Ward et al. [15] studied 31 patients who had surgically confirmed malignant lesions. The study of those researchers differed from ours in that two different types and a range of doses of iron were used (15 µmol/kg of AMI-25 [Guerbet, Aulnay-sous-Bois, France] was used for approximately two thirds of their patients; the remaining patients received 7.0-12.9 µmol/kg of SHU 555A [Schering, Berlin, Germany]).
In addition, Ward et al. [15] used 1.0-T MR scanners with conventional spin-echo T2-weighted images and a 10-30% slice gap. For CT imaging, they used 8- to 10-mm collimation. Ward et al. found higher sensitivity for ferumoxides-enhanced MR imaging than for CT. It is likely that the lower dose of ferumoxides approved for use in the United States (10 µmol/kg) combined with the improved CT technique in our study could account for our observation of a more similar performance for MR imaging and CT.
We did not use gradient-echo T2*-weighted MR imaging in this study. Gradient-echo images show more profound signal intensity loss of the normal liver signal than do spin-echo T2-weighted images and may be useful for segmental localization of liver lesions. Van Beers et al. [16] found similar lesion detection rates between T2-weighted images and gradient recalled echo images, although their study was performed at 0.5 T. Oudkerk et al. [17] described superior results for T1-weighted gradient recalled echo imaging, but they used higher doses of iron (15 µmol/kg of AMI-25) than used in the United States. The results of those researchers have not been replicated to date at lower doses. T1-weighted images are generally not useful for metastatic lesion detection with superparamagnetic iron oxides [10]. T1-weighted gradient-recalled echo images were included in this study for characterization of hemangiomas, which typically show increased signal after ferumoxides administration.
The optimum strategy for imaging patients before planned partial hepatic resection should have a high sensitivity but a low false-positive rate. At the institutions at which this study was conducted, CT during arterial portography has largely been abandoned in favor of helical CT and MR imaging. Many studies have been conducted to assess the usefulness of CT during arterial portography, both with conventional and with helical scanning [18,19,20,21]. These studies show high sensitivity for the method, but its invasiveness, occasional technical failure, and low specificity have led to its abandonment [22]. Noninvasive CT and MR imaging, coupled with the widespread use of intraoperative sonography as used in this study, are also consistent with improvements in hepatic surgical techniques. Intra-operative sonography, together with surgical inspection and palpation of the liver, is generally thought to be the most sensitive method for hepatic lesion detection [23,24,25,26,27]. When such lesions are found intraoperatively, techniques such as nonanatomic resection, radiofrequency ablation, and cryotherapy are used if traditional lobar resections are insufficient. Whereas bilobar disease was previously a contraindication to surgery, these newer surgical methods allow the surgeon to treat tumors in both lobes of the liver. In our practice, patients undergo dual-phase helical CT before surgery. After surgical options have been considered, patients who are eligible for surgery then undergo contrast-enhanced MR imaging as an aid to further surgical planning.
Our study has several limitations. First, the sensitivity values we report are lower than those reported previously for dual-phase CT and MR imaging. For the statistical evaluation, a segment-by-segment comparison was performed. Thus, an interpreter was "incorrect" not only if a lesion was "missed" but also if a lesion was assigned to an incorrect segment. The sensitivity values are low when calculated in this manner considering the overall number of lesions detected per patient. Also, the blinded observers were not asked to evaluate the additive value of each examination. For example, the additive benefit of enhanced MR imaging compared with unenhanced MR imaging was not specifically addressed, because the blinded observers reviewed each examination separately in random order. Because of our study design, we did not address the relative value of T1- versus T2-weighted MR images, or arterial versus portal phase CT images. The combination of MR imaging and CT likely improves the overall characterization of lesions (benign versus malignant). However, we did not measure this effect. Finally, the power of the statistical analysis would be improved by increasing the number of patients in the analysis.
In conclusion, ferumoxides-enhanced MR imaging of the liver shows comparable sensitivity to dual-phase helical CT. The specificity of dual-phase helical CT was superior to that of MR imaging in most (2/3) observers.
Acknowledgments
The support of Berlex Laboratories, Ginette Jacob, and Jan Mintorovitch is
greatly appreciated. We thank Robert Lehr, senior statistical scientist of
Berlex Laboratories, for statistical support and Tracy Borman for coordination
of patient studies and data.
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
1.5 cm) malignant hepatic neoplasms.
AJR
1995;164:879
-884
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
 |
|
  H. Onishi, T. Murakami, T. Kim, M. Hori, R. Iannaccone, M. Kuwabara, H. Abe, S. Nakata, K. Osuga, K. Tomoda, et al. Hepatic Metastases: Detection with Multi-Detector Row CT, SPIO-enhanced MR Imaging, and Both Techniques Combined Radiology, April 1, 2006; 239(1): 131 - 138. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. M. Lutz, J. K. Willmann, K. Goepfert, B. Marincek, and D. Weishaupt Hepatocellular Carcinoma in Cirrhosis: Enhancement Patterns at Dynamic Gadolinium- and Superparamagnetic Iron Oxide-enhanced T1-weighted MR Imaging Radiology, November 1, 2005; 237(2): 520 - 528. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. A. Bluemke, D. Sahani, M. Amendola, T. Balzer, J. Breuer, J. J. Brown, D. D. Casalino, P. L. Davis, I. R. Francis, G. Krinsky, et al. Efficacy and Safety of MR Imaging with Liver-specific Contrast Agent: U.S. Multicenter Phase III Study Radiology, October 1, 2005; 237(1): 89 - 98. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. H. Kim, D. Choi, S. H. Kim, J. H. Lim, W. J. Lee, M. J. Kim, H. K. Lim, and S. J. Lee Ferucarbotran-Enhanced MRI Versus Triple-Phase MDCT for the Preoperative Detection of Hepatocellular Carcinoma Am. J. Roentgenol., April 1, 2005; 184(4): 1069 - 1076. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Kumano, T. Murakami, T. Kim, M. Hori, A. Okada, T. Sugiura, Y. Noguchi, S. Kawata, K. Tomoda, and H. Nakamura Using Superparamagnetic Iron Oxide-Enhanced MRI to Differentiate Metastatic Hepatic Tumors and Nonsolid Benign Lesions Am. J. Roentgenol., November 1, 2003; 181(5): 1335 - 1339. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M.-J. Kim, J. H. Kim, J.-J. Chung, M. S. Park, J. S. Lim, and Y. T. Oh Focal Hepatic Lesions: Detection and Characterization with Combination Gadolinium- and Superparamagnetic Iron Oxide-enhanced MR Imaging Radiology, September 1, 2003; 228(3): 719 - 726. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. A. Bluemke, T. M. Weber, D. Rubin, E. E. de Lange, R. Semelka, R. D. Redvanly, J. Chezmar, E. Outwater, R. Carlos, S. Saini, et al. Hepatic MR Imaging with Ferumoxides: Multicenter Study of Safety and Effectiveness of Direct Injection Protocol Radiology, August 1, 2003; 228(2): 457 - 464. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. D. Frate, C. Zuiani, V. Londero, G. Como, M. Bazzocchi, K. Mortele, and P. R. Ros Comparing Levovist-Enhanced Pulse Inversion Harmonic Imaging and Ferumoxides-Enhanced MR Imaging of Hepatic Metastases Am. J. Roentgenol., May 1, 2003; 180(5): 1339 - 1346. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. K. Kang, J. H. Lim, S. H. Kim, D. Choi, H. K. Lim, W. J. Lee, and S. J. Lee Preoperative Depiction of Hepatocellular Carcinoma: Ferumoxides-enhanced MR Imaging versus Triple-Phase Helical CT Radiology, January 1, 2003; 226(1): 79 - 85. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. S. Arbab, T. Ichikawa, H. Sou, T. Araki, H. Nakajima, K. Ishigame, T. Yoshikawa, and H. Kumagai Ferumoxides-enhanced Double-Echo T2-weighted MR Imaging in Differentiating Metastases from Nonsolid Benign Lesions of the Liver Radiology, October 1, 2002; 225(1): 151 - 158. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. K. Kim, S. H. Kim, W. J. Lee, H. Kim, J. W. Seo, D. Choi, H. K. Lim, S. J. Lee, and J. H. Lim Preoperative Detection of Hepatocellular Carcinoma: Ferumoxides-Enhanced Versus Mangafodipir Trisodium--Enhanced MR Imaging Am. J. Roentgenol., September 1, 2002; 179(3): 741 - 750. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. J. V. Braga, M. A. Choti, V. S. Lee, E. K. Paulson, E. S. Siegelman, and D. A. Bluemke Liver Lesions: Manganese-enhanced MR and Dual-Phase Helical CT for Preoperative Detection and Characterization—Comparison with Receiver Operating Characteristic Analysis Radiology, May 1, 2002; 223(2): 525 - 531. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. S. Raman, D. S. K. Lu, S. C. Chen, J. Sayre, F. Eilber, and J. Economou Hepatic MR Imaging Using Ferumoxides: Prospective Evaluation with Surgical and Intraoperative Sonographic Confirmation in 25 Cases Am. J. Roentgenol., October 1, 2001; 177(4): 807 - 812. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
