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The usefulness of a highly targeted pencil beam (PB) label was compared with the commonly used slab label for direct visualization of pancreaticobiliary reflux using the time-spatial labeling inversion pulse (time-SLIP) technique. Signal profiles of flow phantom images obtained with a 1.5T MRI were analyzed. Both labels had similar labeling capabilities, but the edge characteristics of the PB label were blunt. Next, sixty-eight patients were classified into two groups according to the angle of the pancreaticobiliary ducts, and the displacement of the pancreatic ducts in respiratory fluctuation was measured. The results were approximately 7 mm in both groups. The blunt edge characteristics of the PB label suggest that it is robust to respiratory fluctuations. The overall labeling ability of the PB is comparable to that of the slab. In the larger angle of pancreaticobiliary ducts, the PB label may be able to label the pancreatic duct more selectively.

This study evaluated the dependence of the signal characteristics of time-spatial labeling inversion pulse (time-SLIP) on flow velocity and tag thickness to depict the pancreatic juice flow by analyzing signal profile using a tube phantom study. The tag edge property was evaluated by edge rise distance (ERD). For various slow flow velocities and tag thicknesses, the signal profile characteristics were evaluated using two indices: the tag center value (R TCV ) reduction rate and the total signal value along the tube (T SVT ). ERD, which was about 10% of the tag thickness, was higher for thicker tags, making slow flow detection difficult. T SVT was proportional to the thickness of the tag and was preserved irrespective of the flow velocity. R TCV became lower with higher flow velocity and decreased significantly with thinner tags. These results suggest that the visualization of pancreatic juice flow might improve stability by considering the appropriate tag thickness.

Objective: To evaluate the multiphase contrast-enhanced magnetic resonance (MR) imaging features of Bacillus Calmette-Guérin (BCG)-induced granulomatous prostatitis (GP)., Materials and Methods: Magnetic resonance images obtained from five patients with histopathologically proven BCG-induced GP were retrospectively analyzed for tumor location, size, signal intensity on T2-weighted images (T2WI) and diffusion-weighted images (DWI), apparent diffusion coefficient (ADC) value, and appearance on gadolinium-enhanced multiphase images. MR imaging findings were compared with histopathological findings., Results: Bacillus Calmette-Guérin-induced GP (size range, 9-40 mm; mean, 21.2 mm) were identified in the peripheral zone in all patients. The T2WI showed lower signal intensity compared with the normal peripheral zone. The DWIs demonstrated high signal intensity and low ADC values (range, 0.44-0.68 × 10(-3) mm(2)/sec; mean, 0.56 × 10(-3) mm(2)/sec), which corresponded to GP. Gadolinium-enhanced multiphase MR imaging performed in five patients showed early and prolonged ring enhancement in all cases of GP. Granulomatous tissues with central caseation necrosis were identified histologically, which corresponded to ring enhancement and a central low intensity area on gadolinium-enhanced MR imaging. The findings on T2WI, DWI, and gadolinium-enhanced images became gradually obscured with time., Conclusion: Bacillus Calmette-Guérin-induced GP demonstrates early and prolonged ring enhancement on gadolinium-enhanced MR imaging which might be a key finding to differentiate it from prostate cancer.

The purpose of this study was to retrospectively evaluate radiologist performance in detection of lacunar infarcts on T1- and T2-weighted images, without and with the use of a computer-aided diagnosis (CAD) scheme. Thirty T1-weighted and 30 T2-weighted MR images obtained from 30 patients were used for assessing observer performance. These images were acquired using the fast spin-echo sequence with a 1.5-T MR imaging scanner. The group included 15 patients (age range, 48-83 years; mean age, 67.2 years; 10 men and five women) with a lacunar infarct and 15 patients (age range, 39-76 years; mean age, 64.0 years; eight men and seven women) without lacunar infarcts. Nine radiologists participated in the study. The radiologists initially interpreted the T1- and T2-weighted images without and then with the use of CAD, which indicated their confidence levels regarding the presence (or absence) of lacunar infarcts and the most likely position of a lesion on each MR scan. The observers' performance without and with the computer output was evaluated by performing receiver operating characteristic analysis. For the nine radiologists, the mean area under the best-fit binormal receiver operating characteristic curve plotted for unit square values of radiologists who interpreted the images without and with the scheme were 0.891 and 0.937, respectively. The performance of the radiologists improved significantly when they used the computer output (p=0.032). The CAD scheme has potential to improve the accuracy of radiologists' performance in detection of lacunar infarcts.

Purpose: The purpose of this study was to describe the MR imaging findings of cervical lymphadenopathy in patients with Kikuchi disease (histiocytic necrotizing lymphadenitis)., Materials and Methods: Nine patients with Kikuchi disease underwent MR imaging with a 1.5 T unit including diffusion-weighted (DW) imaging and five of nine underwent gadolinium-enhanced MR imaging. MR images were reviewed for numbers, sizes, locations, focal hypointense areas on T2-weighted images, focal non-enhancing areas on gadolinium-enhanced MR images, and apparent diffusion coefficients (ADCs) of enlarged lymph nodes., Results: 52 enlarged nodes (range, 2-11 nodes; mean, 5.8 nodes per patients) were identified. Lymphadenopathy was unilateral in 7 patients (78%) and bilateral in 2 (22%). Enlarged nodes were located at level IIA in 7 nodes, IIB in 23, III in 8, IV in 4, VA in 2, and VB in 8. Focal hypointense areas on T2-weighted images were found in 7 patients (78%) and 21 nodes (40%), and had a peripheral distribution in 19 nodes (90%) and had clear margins in 16 nodes (76%). Focal non-enhancing areas were seen in 3 patients (60%) and 6 nodes (23%). ADCs were variable (range, 0.69-1.78 [×10(-3) mm2/s]; mean, 1.01±0.28)., Conclusion: Cervical lymphadenopathy in Kikuchi disease showed predominantly a unilateral distribution at levels II-V. Furthermore, Kikuchi disease should be considered when T2-weighted images demonstrate hypointensity areas at the peripheries of enlarged cervical nodes, which corresponded to histopathological findings of coagulative necrosis in paracortical areas., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Purpose: To compare (11)C-choline positron emission tomography (C-PET), (18)F-fluorodeoxyglucose PET (FDG-PET), and MR imaging in the preoperative detection of prostate cancer., Materials and Methods: C-PET, FDG-PET, and MR images were obtained in 43 consecutive patients with suspected prostate cancer, and prostate cancers were histopathologically confirmed in 26 patients. Unenhanced T1-weighted, T2-weighted, and gadolinium-enhanced MR images were obtained. C-PET and FDG-PET were conducted 1.5 and 60 minutes after injection of 5.5 and 5.0 MBq/kg tracers, respectively. A nuclear and a genitourinary radiologist retrospectively reviewed PET and MR images at random, respectively, and assigned a confidence level for the presence of prostate cancer using a four-point scale. Diagnostic performance was tested using the McNemar test and receiver operating characteristic curve analysis., Results: The sensitivity was greater (P < 0.05) with MR (88%) and C-PET (73%) images than with FDG-PET images (31%). The accuracy was greater (P < 0.05) with MR images (88%) than with C-PET (67%) and FDG-PET (53%) images. The area-under-curve value with MR (0.90) was greater than those with C-PET (0.53) and FDG-PET (0.54) images (P < 0.01)., Conclusion: MR imaging should be primarily performed in the preoperative detection of prostate cancer. C-PET and FDG-PET did not improve the detection., (Copyright 2010 Wiley-Liss, Inc.)

The differentiation of focal liver lesions in magnetic resonance (MR) imaging is primarily based on the intensity and homogeneity of lesions with different imaging sequences. However, these imaging findings are falsely interpreted in some patients because of the complexities involved. Our aim is to establish a computer-aided diagnosis system named LiverANN for classifying the pathologies of focal liver lesions into five categories using the artificial neural network (ANN) technique. On each MR image, a region of interest (ROI) in the focal liver lesion was delineated by a radiologist. The intensity and homogeneity within the ROI were calculated automatically, producing numerical data that were analyzed by feeding them into the LiverANN as inputs. Outputs were the following five pathologic categories of hepatic disease: hepatic cyst, hepatocellular carcinoma, dysplasia in cirrhosis, cavernous hemangioma, and metastasis. Of the 320 MR images obtained from 80 patients (four images per patient) with liver lesions, our LiverANN classified 50 cases of a training set into five types of liver lesions with a training accuracy of 100% and 30 test cases with a testing accuracy of 93%. The experiment demonstrated that our LiverANN, which functions as a computer-aided differentiation tool, can provide radiologists with a second opinion during the radiologic diagnostic procedure.

The detection of asymptomatic lacunar infarcts on magnetic resonance (MR) images is important because their presence indicates an increased risk of severe cerebral infarction. However, accurate identification of lacunar infarcts on MR images is often hard for radiologists because of the difficulty in distinguishing lacunar infarcts and enlarged Virchow-Robin spaces. Therefore, we developed a computer-aided diagnosis (CAD) scheme for the classification of lacunar infarcts and enlarged Virchow-Robin spaces. Our database consisted of T1- and T2- weighted images obtained from 109 patients. The locations of lacunar infarcts and enlarged Virchow-Robin spaces were determined by an experienced neuroradiologist. It included 89 lacunar infarcts and 20 enlarged Virchow-Robin spaces. We first enhanced the lesions in T2-weighted image by using the white top-hat transformation. A gray-level thresholding was then applied to the enhanced image for the segmentation of lesions. From the segmented lesions, we determined image features, such as size, shape, location, and signal intensities in T1- and T2- weighted images. A neural network was then employed for distinguishing between lacunar infarcts and enlarged Virchow-Robin spaces. Our computerized method was evaluated by using a leave-one-out method. The result indicated that the area under the ROC curve was 0.945. Therefore, our CAD scheme would be useful in assisting radiologists for diagnosis of silent cerebral infarctions in MR images.

Rationale and Objectives: The detection and management of asymptomatic lacunar infarcts on magnetic resonance (MR) images are important tasks for radiologists to ensure the prevention of severe cerebral infarctions. However, accurate identification of the lacunar infarcts on MR images is a difficult task for the radiologists. Therefore the purpose of this study was to develop a computer-aided diagnosis scheme for the detection of lacunar infarcts to assist radiologists' interpretation as a "second opinion.", Materials and Methods: Our database comprised 1,143 T1- and 1,143 T2-weighted images obtained from 132 patients. The locations of the lacunar infarcts were determined by experienced neuroradiologists. We first segmented the cerebral region in a T1-weighted image by using a region growing technique for restricting the search area of lacunar infarcts. For identifying the initial lacunar infarcts candidates, a top-hat transform and multiple-phase binarization were then applied to the T2-weighted image within the segmented cerebral region. For eliminating the false positives (FPs), we determined 12 features--the locations x and y, signal intensity differences in the T1- and T2-weighted images, nodular components from a scale of 1 to 4, and nodular and linear components from a scale of 1 to 4. The nodular components and the linear components were obtained using a filter bank technique. The rule-based schemes and a support vector machine with 12 features were applied to the regions of the initial candidates for distinguishing between lacunar infarcts and FPs., Results: Our computerized scheme was evaluated by using a holdout method. The sensitivity of the detection of lacunar infarcts was 96.8% (90/93) with 0.76 FP per image., Conclusions: Our computerized scheme would be useful in assisting radiologists for identifying lacunar infarcts in MR images.

Purpose: To investigate the time course of prostatic edema and the effect on the dose-volume histograms of the prostate for patients treated with brachytherapy., Methods and Materials: A total of 74 patients with prostate cancer were enrolled in this prospective study. A transrectal ultrasound-based preplan was performed 4 weeks before implantation and computed tomography/magnetic resonance imaging fusion-based postimplant dosimetry was performed on the day after implantation (Day 1) and 30 days after implantation (Day 30). The prostate volume, prostate volume covered by 100% of the prescription dose (V100), and dose covering 90% of the prostate (D90) were evaluated with prostatic edema over time., Results: Prostatic edema was greatest on Day 1, with the mean prostate volume 36% greater than the preplan transrectal ultrasound-based volume; it thereafter decreased over time. It was 9% greater than preplan volume on Day 30. The V(100) increased 5.7% from Day 1 to Day 30, and the D90 increased 13.1% from Day 1 to Day 30. The edema ratio (postplan/preplan) on Day 1 of low-quality implants with a V(100) of <80% was significantly greater than that of intermediate- to high-quality implants (>80% V100; p = 0.0272). The lower V100 on Day 1 showed a greater increase from Day 1 to Day 30. A V100 on Day 1 of >92% is unlikely to increase >0% during the interval studied., Conclusion: Low-quality implants on Day 1 were highly associated with edema; however, such a low-quality implant on Day 1, with significant edema, tended to improve by Day 30. If a high-quality implant (V100 >92%) can be obtained on Day 1, a re-examination is no longer necessary.

Objective: We attempt to clarify specific imaging findings useful for differential diagnosis between endometrioid cancer and clear cell cancer., Methods: We examined magnetic resonance imaging features on 11 endometrioid cancer and 9 clear cell cancer patients. We compared them, focusing on the locularity, characteristic and growth pattern of solid components, and association with endometrial diseases., Results: Endometrioid cancer had a predominantly multilocular appearance, but clear cell cancer showed almost equally multilocular and unilocular appearances. For the growth pattern, endometrioid cancer in 6 patients demonstrated a "centric pattern" and an "eccentric pattern" in 4, whereas clear cell cancer showed predominantly an eccentric pattern. An internal slit in the solid component was seen in 4 endometrioid cancer patients but not seen in any of the patients with clear cell cancer., Conclusions: The magnetic resonance imaging appearance of the internal slit in solid components and the presence of endometrial disease are key factors in differentiating endometrioid cancer from clear cell cancer, although lesion locularity and growth pattern are not specific in both.

The detection of asymptomatic lacunar infarcts on magnetic resonance (MR) images are important tasks for radiologists to ensure the prevention of sever cerebral infarction. However, their accurate identification is often difficult task. Therefore, the purpose of this study is to develop a computer-aided diagnosis scheme for the detection of lacunar infarcts. Our database consisted of 1,143 T1- and 1,143 T2-weighted images obtained from 132 patients. We first segmented the cerebral region in the T1- weighted image by using a region growing technique. For identifying the initial lacunar infarcts candidates, white top-hat transform and multiple-phase binarization were then applied to the T2- weighted image. For eliminating false positives (FPs), we determined 12 features, i.e., the locations x and y, density differences in the T1- and T2- weighted images, nodular components (NC), and nodular & linear components (NLC) from a scale 1 to 4. The NCs and NLCs were obtained using filter bank technique. The rule-based scheme and a neural network with 12 features were employed as the first step for eliminating FPs. The modular classifier was then used for eliminating three typical sources of FPs. As a result, the sensitivity of the detection of lacunar infarcts was 96.8% with 0.30 FP per image. Our computerized scheme would assist radiologists in identifying lacunar infarcts on MR images.

Background and Purpose: To compare the CT-based and CT/MRI fusion-based postimplant dosimetry after permanent prostate brachytherapy and to evaluate the improvement in CT-based dosimetry by physicians with or without experience in using the CT/MRI fusion method., Patients and Methods: Thirty-eight consecutive patients agreed to participate in a prospective study. The prostate contours from CT/MRI fusion are the gold standard for determining the prostate volume and dose volume histogram (DVH). CT-based postimplant dosimetries were performed by two physicians. Observer 1 was a radiologist who had never used CT/MRI fusion method for postimplant dosimetric analysis. Observer 2 was a radiation oncologist experienced in postimplant analysis using the CT/MRI fusion method. The prostate dosimetry was evaluated by prostate D90 and V100., Results: No significant difference was observed in the mean prostate volumes between the two observers and the CT/MRI fusion data. However, the correlation coefficient value for observer 2 (R(2)=0.932) was greater than that for observer 1 (R(2)=0.793). The D90 and V100 values as evaluated by the two observers were significantly underestimated in comparison to those evaluated using the CT/MRI fusion methods. The DVH related parameters were underestimated more frequently by observer 1 than by observer 2: (prostate D90: 99.56% for observer 1, 102.97% for observer 2, 109.37% for CT/MRI fusion. Prostate V100: 88.12% for observer 1, 90.14% for observer 2, 91.91% for CT/MRI fusion)., Conclusions: The difference in the mean value in D90 and V100 by observer 1 was significantly greater than that for observer 2. These findings suggest that the CT/MRI fusion method provides accurate feedback which thereby improves CT-based postimplant dosimetry for prostate brachytherapy.

Purpose: The aim of this study was to compare the outcomes between magnetic resonance imaging (MRI)-based and computed tomography (CT)/MRI fusion-based postimplant dosimetry methods in permanent prostate brachytherapy., Methods and Materials: Between October 2004 and March 2006, a total of 52 consecutive patients with prostate cancer were treated by brachytherapy, and postimplant dosimetry was performed using CT/MRI fusion. The accuracy and reproducibility were prospectively compared between MRI-based dosimetry and CT/MRI fusion-based dosimetry based on the dose-volume histogram (DVH) related parameters as recommended by the American Brachytherapy Society., Results: The prostate volume was 15.97+/-6.17 cc (mean+/-SD) in MRI-based dosimetry, and 15.97+/-6.02 cc in CT/MRI fusion-based dosimetry without statistical difference. The prostate V100 was 94.5% and 93.0% in MRI-based and CT/MRI fusion-based dosimetry, respectively, and the difference was statistically significant (p=0.002). The prostate D90 was 119.4% and 114.4% in MRI-based and CT/MRI fusion-based dosimetry, respectively, and the difference was statistically significant (p=0.004)., Conclusion: Our current results suggested that, as with fusion images, MR images allowed accurate contouring of the organs, but they tended to overestimate the analysis of postimplant dosimetry in comparison to CT/MRI fusion images. Although this MRI-based dosimetric discrepancy was negligible, MRI-based dosimetry was acceptable and reproducible in comparison to CT-based dosimetry, because the difference between MRI-based and CT/MRI fusion-based results was smaller than that between CT-based and CT/MRI fusion-based results as previously reported.

Objective: The purpose of our study was to evaluate the clinical feasibility and usefulness of a 2D spoiled gradient-recalled echo MR sequence with serial switching of reversed centric and centric k-space reordering for high-spatial-resolution gadolinium-enhanced double hepatic arterial phase (HAP) MRI of the liver., Subjects and Methods: MR images (frequency, 512; phase encoding without interpolation, 224; 6-mm thickness with 1-mm gap; 30 slices per 18 seconds) were obtained with multiphase imaging in which central k-space line data were filled 10, 21, 49, and 181 seconds after arrival of contrast medium in the abdominal aorta for the early HAP (reversed centric reordering, center of k-space lines acquired at end of acquisition), late HAP (centric reordering, center of k-space lines at beginning of acquisition), portal venous phase (centric reordering), and equilibrium phase (centric reordering), respectively, in 102 consecutive patients with suspected liver disease, including 48 untreated hepatocellular carcinomas (HCCs) in 35 patients. Images were quantitatively assessed for degree of contrast enhancement in the abdominal aorta, spleen, portal trunk, liver parenchyma, hepatic veins, and HCCs. Images were qualitatively assessed for the effectiveness of contrast enhancement in each phase and for degree of image degradation due to artifacts., Results: Enhancement of the abdominal aorta peaked in the early HAP, of the portal trunk in the late HAP, and of the hepatic parenchyma and veins in the portal venous phase. Mean HCC-to-liver contrast peaked in the early HAP and turned to a negative value in the portal venous and equilibrium phases. Sufficient image quality was achieved in 99 (97%) of the patients. One of the other three patients had motion artifacts due to body motion, and the other two had unsatisfactory respiratory suspension. Scan timing for early and late HAP was optimal in 74 (73%) of the patients, for late HAP lagged in 20 (20%), for early HAP was premature in six (6%), and for early HAP lagged in five (5%) of the patients., Conclusion: We confirmed the feasibility and usefulness of a 2D gadolinium-enhanced double HAP spoiled gradient-recalled echo sequence incorporating serial switching of reversed centric and centric k-space reordering. This method has the potential for use in high-spatial-resolution double HAP MRI for the diagnosis of hypervascular HCC.

Castleman's disease is an usually benign lymphoid tumor of uncertain etiology that generally appears as a solitary mediastinal mass. We present a case of Castleman's disease in the right chest wall of a 60-year-old woman. Magnetic resonance imaging showed a well-defined, oval mass that was early enhanced on T1-weighted images. The mass was diagnosed by percutaneous core needle biopsy with computed tomography guidance. The patient has remained well for 5 years without an increase in tumor size. We also summarize the international literature.

Various histologic types of neurogenic tumors may originate in the mediastinum and chest wall. It is possible to make accurate diagnosis of these tumors by using the multiplanar capability and high contrast resolution of MR imaging because of these characteristic imaging findings. MR and histologic features of these tumors are illustrated and described in this essay.

Objective: The purpose of our study was to assess the correlation between the quantitative and qualitative imaging findings on unenhanced and gadolinium-enhanced MR images and the intensity of vascular endothelial growth factor (VEGF) expression in hepatocellular carcinomas and in the surrounding nontumorous liver., Materials and Methods: The intensities of VEGF expression in hepatocellular carcinoma and in the surrounding liver by Western blot analysis were converted to VEGF expression indexes (VEGF(IND)) in 22 surgical specimens ranging in size from 14 to 126 mm (mean, 47.6 +/- 29.5 mm) that were resected in 22 patients (17 men and five women; age range, 41-85 years [mean, 64 years]) between April 2000 and October 2002. MR images were retrospectively evaluated to determine contrast-to-noise ratios (CNRs), signal intensity SD ratios, and phase-shift indexes. Signal intensity characteristics of hepatocellular carcinomas were reviewed independently by two experienced radiologists who were unaware of the pathologic diagnosis or the results of immunoblotting. CNRs, SD ratios, and phase-shift indexes were correlated with VEGF(IND) using a simple regression test, and signal intensity characteristics were correlated with VEGF(IND) using the Spearman's rank correlation test., Results: On opposed-phase T1-weighted spoiled gradient-recalled echo (GRE) images, CNRs correlated inversely with the VEGF(IND) of hepatocellular carcinomas (r = -0.46, p = 0.038). CNRs on T2-weighted fast spin-echo images correlated directly with the VEGF(IND) of hepatocellular carcinomas (r = 0.49, p = 0.025), and on gadolinium-enhanced hepatic arterial phase GRE images marginally and inversely correlated with VEGF(IND) (r = -0.39, p = 0.081). On T2-weighted fast spin-echo images, SD ratios correlated directly with the VEGF(IND) of hepatocellular carcinomas (r = 0.44, p = 0.044). No correlation was found between phase-shift indexes and VEGF expression. The qualitatively assessed signal intensity heterogeneities of hepatocellular carcinomas correlated directly with the VEGF(IND) of hepatocellular carcinomas on opposed-phase T1-weighted GRE, T2-weighted fast spin-echo, hepatic arterial phase GRE, and equilibrium phase GRE images., Conclusion: Our results indicate that the signal intensity and heterogeneity of hepatocellular carcinomas on MR images correlate with the degree of VEGF expression in hepatocellular carcinomas.

The purpose of our study was to determine whether or not the addition of T2-weighted fast spin-echo (SE) imaging to gadolinium-enhanced spoiled gradient-recalled-echo (GRE) imaging improves the observer performance in the preoperative detection of malignant hepatic tumors. Gadolinium-enhanced GRE and fat-suppressed T2-weighted fast SE images obtained in 49 patients with 82 surgically confirmed malignant hepatic tumors (40 hepatocellular carcinomas and 42 metastases) were retrospectively reviewed by three independent off-site observers. In the random review of images, gadolinium-enhanced GRE images were reviewed first; thereafter, T2-weighted fast SE images were added for combined review. Observer performance was evaluated with the McNemar's test and receiver operating characteristic curve analysis. For gadolinium-enhanced GRE images alone vs. combined images, sensitivities for detection were 78% vs. 79% for hepatocellular carcinomas (P>.05), 67% vs. 71% for metastases (P<.05) and 72% vs. 75% for tumors overall (P<.05), respectively. The Az values were 0.892 vs. 0.889 in hepatocellular carcinomas (P>.05), 0.797 vs. 0.828 in metastases (P<.05) and 0.839 vs. 0.846 in tumors overall (P>.05), respectively. Our results showed that the addition of T2-weighted fast SE imaging to gadolinium-enhanced GRE imaging improved the observer performance in the detection of metastases.

A 65-year-old man with multiple hepatocellular carcinomas in the liver with type C viral hepatitis had a solitary mediastinal lymph node metastasis in the right paratracheal to tracheobronchial region. Surgical resection for the mediastinal metastasis was undertaken based on magnetic resonance (MR) imaging findings, suggesting its radicality. We assess the MR imaging findings and presumable pathways of lymphatic metastasis from the liver to mediastinal lymph nodes in this report.

We examined a 70-year-old male patient with an inflammatory pseudotumor of the liver mimicking a peripheral-type cholangiocellular carcinoma. Ferumoxide-enhanced magnetic resonance (MR) imaging revealed residual Kupffer cell function in liver parenchyma in and surrounding the inflammatory pseudotumor involvement, which suggested the diagnosis of inflammatory pseudotumor of the liver. We correlate the MR imaging and pathologic findings in this report., (Copyright 2004 Wiley-Liss, Inc.)

Objective: The purpose of this study was to try to delineate the esophageal passage under dynamic conditions and to determine optimum settings for esophageal magnetic resonance (MR) imaging., Methods: Ten healthy volunteers underwent MR fluoroscopy with two T1-weighted sequences: turbo field echo (TFE) and T1-weighted fast field echo (T1-FFE). These sequences were compared for signal-to-noise ratios (SNRs) and image quality. To determine the optimum slice thickness, an additional 10 healthy volunteers underwent MR fluoroscopy. Results obtained for slice thicknesses of 25, 35, 45, and 55 mm were compared for delineated length of the esophagus and image quality., Results: The T1-FFE sequences provided higher SNRs and better image quality than the TFE sequences (T1-FFE: 89.4 +/- 28.0, TFE: 52.4 +/- 16.7; P < 0.001). Artifacts were less prominent and delineation of the esophageal wall was better on the T1-FFE images. The delineation of the esophageal wall was best with a 35-mm slice thickness, although delineated length was the longest with a 55-mm slice thickness., Conclusion: This study showed T1-FFE to be a more suitable sequence than TFE and that the 35-mm slice thickness was the optimum slice thickness for esophageal MR fluoroscopy.

Purpose: To perform comparison of gadolinium-enhanced and ferumoxides-enhanced magnetic resonance imaging (MRI) in the detection of nodule-in-nodule appearance of hepatocellular carcinomas (HCCs)., Materials and Methods: During a recent 45-month period, we had eight patients (five men and three women; age range, 63-84 years; mean, 71 years) with HCCs with nodule-in-nodule appearance who underwent gadolinium-enhanced MRI, ferumoxides-enhanced MRI, and computed tomography during arterial portography (CTAP) and computed tomography during hepatic arteriography (CTHA), combined and separately, within an interval of two weeks. Two blinded radiologists in consensus retrospectively evaluated three sets of sequences: unenhanced T1- and T2-weighted MR, gadolinium-enhanced MR, and ferumoxides-enhanced MR images in random order of patients and imaging sequences. The depiction degree of nodule-in-nodule appearance of HCC was evaluated in a semiquantitative fashion. The sensitivities of unenhanced T1- and T2-weighted, gadolinium-enhanced, and ferumoxides-enhanced MR images were compared with McNemar's test., Results: The eight HCCs with nodule-in-nodule appearance ranged in size from 16-26 mm (mean, 20.0 +/- 4.0 mm), and there existed nine internal HCC foci ranging in size from 5-14 mm (mean, 7.9 +/- 3.5 mm). On gadolinium-enhanced MR images, the nodule-in-nodule appearance of HCC was typically seen as hypervascular foci in an iso- or hypovascular area: the depiction degree of nodule-in-nodule appearance was distinct in two lesions, equivocal in three, and absent in three. On ferumoxides-enhanced MR images, it was typically seen as hyperintense foci in a hypointense area: the depiction degree was distinct in four, moderate in one, and absent in three. The sensitivities for detection of nodule-in-nodule appearance were 25%, 25%, and 63% on T1- and T2-weighted, gadolinium-enhanced, and ferumoxides-enhanced MR images, respectively, but there was no significant difference in sensitivity., Conclusion: Nodule-in-nodule appearance of HCCs can be seen on ferumoxides-enhanced MR images, in some cases more clearly than on gadolinium-enhanced MR images, particularly when the background nodule shows hyperintensity on precontrast T1-weighted images. Ferumoxides-enhanced MRI may be considered when development of malignant foci is suspected during routine examinations., (Copyright 2004 Wiley-Liss, Inc.)

Purpose: To assess the frequency, imaging findings, and significance of early-enhancing nonneoplastic (EN) lesions with gadolinium-enhanced magnetic resonance imaging (MRI) of the liver following partial hepatectomy., Materials and Methods: We retrospectively reviewed MR images after partial hepatectomy in 30 patients. Postoperative MRI was performed in 1-12 months (mean, 3.7 months) after partial hepatectomy. We defined the EN lesion as a lesion that was ill defined; irregular, wedge shaped, or serpiginous; located along the liver edge; not visible on unenhanced MR images; did not appear hypointense on portal venous- or equilibrium-phase images; or a combination of those imaging findings., Results: A total of 39 EN lesions (size range, 5-60 mm; mean, 25.2 mm) in 19 patients and 17 recurrent tumors (size range, 5-50 mm; mean, 16.8 mm) in 10 patients newly appeared after partial hepatectomy. The EN lesions were diagnosed as pseudolesions by the second postoperative follow-up MRI in 17 patients or contrast-enhanced computed tomography (CT) in two. A total of 13 EN lesions (33%) were located along the liver edge and 20 (51%) were adjacent to the resected area. The shape was circular in 11 (28%), oval in three (8%), irregular in 11 (28%), wedge shaped in five (13%), and serpiginous in nine (23%). No EN lesion showed hypointensity on gadolinium-enhanced portal venous-phase or equilibrium-phase images. A total of 14 EN lesions (36%) showed slight hyperintensity on T2-weighted images. The confidence levels for malignancy probability assigned by blinded radiologists were lower with EN lesions than with recurrent tumors (P < 0.001)., Conclusion: EN lesions are frequently seen in MRI following partial hepatectomy, and occasionally are slightly hyperintense on T2-weighted images, mimicking malignant tumors. However, most EN lesions can be correctly diagnosed with MRI findings., (Copyright 2004 Wiley-Liss, Inc.)

Purpose: To determine whether chemical-shift-selective (CSS) fat suppression is necessary for ferumoxide-enhanced T2-weighted fast spin-echo (FSE) imaging in the detection of malignant hepatic tumors., Materials and Methods: Ferumoxide-enhanced magnetic resonance (MR) images obtained in 38 patients with surgically confirmed 61 malignant hepatic tumors (36 hepatocellular carcinomas (HCCs), 25 metastases) were retrospectively reviewed by three independent readers. Three sequences of MR images with CSS fat-suppressed T2-weighted FSE, non-fat-suppressed T2-weighted FSE, and T2*-weighted gradient-recalled-echo (GRE) sequences were randomly reviewed on a segment-by-segment basis in a blind fashion. Observer performance was tested using the McNemar's test and receiver-operating-characteristic (ROC) analysis for the clustered data. Lesion-to-liver contrast-to-noise ratio (C/N) was also assessed., Results: The mean C/N with the CSS fat-suppressed FSE sequence was highest in HCCs, metastases, and tumors overall. Sensitivity was highest with the CSS fat-suppressed FSE sequence in HCC, was highest with the non-fat-suppressed FSE sequence in metastases, and was comparable in tumors overall. Specificity was comparable between the sequences. The area under ROC curve (Az) value was greatest with the CSS fat-suppressed FSE sequence in HCCs, was greatest with the non-fat- suppressed FSE sequence in metastases, and was comparable in tumors overall. The sensitivities and Az values were lower with the GRE sequence than the FSE sequence., Conclusion: The CSS fat-suppressed FSE sequence was superior to the GRE sequence in the detection of HCCs, but the non-fat-suppressed FSE sequence was comparable to the GRE sequence. The non-fat-suppressed FSE sequence was superior to the CSS fat-suppressed FSE and GRE sequences in the detection of metastases. Optimal FSE imaging with CSS fat suppression or without aiming for the detection of HCCs or metastases, respectively, outperforms GRE imaging in ferumoxide-enhanced MRI., (Copyright 2004 Wiley-Liss, Inc.)

The purpose of our study was to assess whether respiratory-triggered multishot fast spin echo (MS-FSE) and breath-hold half-Fourier single-shot fast spin echo (SS-FSE) images, in addition to breath-hold T(2)*-weighted gradient recalled echo (GRE) images, increase observer performance in the detection of malignant hepatic tumors with ferumoxide-enhanced magnetic resonance (MR) imaging. Ferumoxide-enhanced MR images obtained from 48 patients with 83 malignant hepatic tumors were retrospectively reviewed by three independent off-site readers. In the first image review, GRE images alone were reviewed. Then, MS-FSE images were added for the first combination review. Finally, SS-FSE images were added for the second combination review. Observer performances were tested by McNemar's test and receiver-operating-characteristic analysis for the clustered data. Sensitivity for hepatocellular carcinomas, metastases, and malignant hepatic tumors overall was significantly (p < 0.05) higher with GRE and MS-FSE combined and GRE, MS-FSE and SS-FSE combined than with GRE alone. For metastases, the Az value was significantly (p < 0.05) higher with GRE and MS-FSE combined, and GRE, MS-FSE and SS-FSE combined than with GRE alone. We confirmed the incremental value of ferumoxide-enhanced MR imaging by obtaining MS-FSE and SS-FSE images in addition to GRE images in the detection of malignant hepatic tumors.

Purpose: To evaluate ferumoxide-enhanced MR imaging findings of hepatocellular carcinomas (HCCs) in correlation with the histologic tumor grades and the tumor vascularity evaluated by CT hepatic arteriography (CTHA) and CT during arterial portography (CTAP) combined., Materials and Methods: By searching the radiologic, surgical, and pathologic reports of our institution between January 1999 and February 2001, we identified 43 patients with 51 pathologically confirmed HCCs who underwent ferumoxide-enhanced MR imaging and combination CTHA and CTAP within two weeks. The HCCs consisted of 17 well-differentiated, 28 moderately differentiated, and six poorly differentiated tumors. The MR and CT were retrospectively reviewed by two radiologists in consensus for signal intensity on MR images and vascularity on CT. The Spearman's rank correlation coefficient was calculated to correlate the frequency of tumors with ferumoxide uptake with the histologic tumor grades and the tumor vascularity on CTHA and CTAP., Results: A total of 45 tumors (88%) did not take up ferumoxide, and thus showed distinct, homogeneous hyperintensity. Six tumors (12%) ranging 5-16 mm in size (mean, 11 mm) took up ferumoxide, and thus showed isointensity, mixed intensity, or hypointensity, including five of 17 (29%) well-differentiated tumors and one of 28 (4%) moderately differentiated tumors. Five of the six tumors (83%) showed hyper- or hypovascularity on CTHA or hypovascularity on CTAP. The frequency of tumors with ferumoxide uptake showed weak correlation with tumor grades (coefficient = 0.26, P < 0.01) and vascularity on CTHA (-0.35, P < 0.05) and CTAP (0.39, P < 0.01)., Conclusion: Although a small number of well-differentiated HCC take up ferumoxide and show iso-, mixed, or hypointensity, most such tumors show increased hepatic arterial or decreased portal venous perfusion. The present results suggest the limitation of reticuloendothelial contrast imaging, particularly in the diagnosis of small, well-differentiated HCC., (Copyright 2003 Wiley-Liss, Inc.)

Aim: To assess the frequency, cause, and significance of early-enhancing, non-neoplastic (EN) lesions on gadolinium-enhanced magnetic resonance imaging (MRI) of the liver performed for the detection of malignant hepatic tumours., Materials and Methods: From September 1997 to September 2000, we reviewed the images of 125 patients, suspected of having hepatic tumours, in whom (1) gadolinium-enhanced triphasic dynamic gradient-recalled-echo (GRE) imaging in addition to unenhanced T1- and T2-weighted MRI was performed, (2) conventional angiography and combination computed tomography (CT) hepatic arteriography and CT during arterial portography were performed within 2 weeks of the MRI, and (3) definitive surgery within 2 weeks of the MRI or follow-up study by means of intravenously contrast-enhanced CT or MRI in 10 months or more was performed. Angiographic studies were correlated to determine the underlying causes of the EN lesions., Results: We found 78 EN lesions in 36 patients (29%), ranging in size from 4 and 50 mm (mean, 12.2 mm). From the MR reports, our radiologists had prospectively diagnosed EN lesions as probable malignant tumours in eight (10%), possible malignant tumours in 36 (46%), and probable non-neoplastic lesion in 34 (44%). EN lesions were found in 27 of 81 (33%) cirrhotic patients and in nine of 44 (20%) non-cirrhotic patients. Fifty-one EN lesions (65%) were located along the liver edge. The shape was circular in 42 (54%), oval in 14 (18%), irregular in 12 (15%), wedge-shaped in seven (9%), and fan-shaped in three (4%). Twenty EN lesions (26%) appeared slightly hyperintense on T2-weighted images. The causes were non-neoplastic arterio-portal shunting in 48 (62%), cystic venous drainage in four (5%), rib compression in four (5%), aberrant right gastric venous drainage in two (3%), and unknown in 20 (26%)., Conclusion: Over half the number of EN lesions were caused by non-neoplastic arterio-portal shunting, occasionally showing slight hyperintensity on T2-weighted images. On MR images the non-neoplastic nature of the EN lesion was often ascertained. Radiologists should not overcall EN lesions as malignant as the patients involved would be inappropriately considered inoperable. In problematic cases, further investigation with angiographic CT or follow-up imaging studies should be performed.

Purpose: To correlate the perilesional hyperintense rim of malignant hepatic tumors seen on ferumoxide-enhanced T1-weighted gradient-echo (GE) MR images with histopathologic findings., Materials and Methods: In 13 tumors in 12 patients, T1-weighted GE images (TE of 1.4 msec, flip angle of 90 degrees) obtained after IV administration of ferumoxide were evaluated. MR imaging was initiated within one hour of the completion of ferumoxide administration. Surgical resection for tumors was performed within an interval of two weeks of the MR imaging. Resected specimens were histopathologically examined for peritumoral sinusoidal congestion, desmoplastic reaction, compressed hepatic parenchyma, lymphocytic infiltration, and vascular proliferation., Results: In twelve tumors (92%), prominently (N = 2), moderately (N = 5), and mildly to minimally (N = 5), a perilesional hyperintense rim was observed. Among histopathologic findings, the degree of peritumoral sinusoidal congestion correlated (R =.75, P <.04) with the degree of perilesional hyperintense rim. The thickness of the perilesional hyperintense rim showed a moderate positive correlation (R =.65, P <.02) with the thickness of peritumoral area with sinusoidal congestion., Conclusion: Perilesional hyperintense rim of malignant hepatic tumors on ferumoxide-enhanced T1-weighted GE images may correlate with sinusoidal congestion surrounding malignant hepatic tumors., (Copyright 2003 Wiley-Liss, Inc.)

Objective: The purpose of our study was to evaluate the value of gadolinium-enhanced MR imaging of the liver in the detection and grading of esophageal varices in patients with chronic liver damage., Materials and Methods: Three independent off-site radiologists retrospectively reviewed MR images of the liver obtained in 72 patients with chronic liver damage, including 49 patients with untreated esophageal varices. All patients had undergone gastrointestinal endoscopy within 2 weeks of MR imaging. Both MR and endoscopic images were reviewed to determine whether esophageal varices were present and, if so, to determine the grade of the varices. Observer performances were tested with receiver operating characteristic curve analysis using the jackknife dispersion test. Correlations between the grades of the varices determined using MR images and those determined using endoscopic images were tested., Results: Sensitivity for detection of esophageal varices was significantly (p < 0.01) higher for the combination of unenhanced and gadolinium-enhanced MR images (81%) than for the unenhanced MR images alone (51%). The receiver operating characteristic curve analysis (area under the curve, [A(z)]) showed that performance using the combination of the unenhanced and gadolinium-enhanced MR images (A(z) = 0.641) was superior to that using unenhanced MR images alone (A(z) = 0.586). A statistically significant positive correlation (p < 0.05) was found between the grades determined using MR imaging and the grades determined using endoscopy., Conclusion: Our results suggest the potential value of diagnosing the presence and grade of esophageal varices on MR imaging of the liver for patients with chronic liver damage. Gadolinium-enhanced MR imaging may increase the potential value.

We describe the magnetic resonance (MR) imaging findings of a small scirrhous hepatocellular carcinoma in a 74-year-old man. The initial MR imaging findings indicated that the tumor had a small central scar, which suggested the differential diagnoses of hepatocellular carcinoma, intrahepatic cholangiocarcinoma, and metastasis. A small scirrhous hepatocellular carcinoma may have a central scar and should be included in the differential diagnoses for small hepatic masses with a central scar., (Copyright 2002 Wiley-Liss, Inc.)

We report and assess the imaging findings in a patient with multiple arterioportal shunting mimicking multiple hypervascular tumors that showed multiple areas of hyperintensity with gadolinium-enhanced gradient-recalled-echo images obtained in the hepatic arterial phase and corresponding areas of slight hyperintensity with T2-weighted images.

The purpose of this study is to develop a technique to detect lacunar infarct regions automatically in brain MR images. Our detection method is based on the definition of lacunar infarcts. After inputted images were binarized, we used feature values such as area, circularities and the center of gravity of candidate regions to extract isolated lacunar infarct regions. We also developed and used a new filter to enhance the signals of lacunar infarcts adjacent to some high intensity regions. 10 cases involving 81 sectional images were applied to our experiment. As a result, the sensitivity was 100% with approximately 1.77 false-positives per image. Our results are promising on the first stage, although it remains to improve on problems that to eliminate false-positives and automatically establish threshold value.

Objective: Our purpose was to investigate the effects of i.v. administration of gadolinium chelate on thick-section MR cholangiopancreatography performed with half-Fourier rapid acquisition with relaxation enhancement sequence., Subjects and Methods: Unenhanced and enhanced MR cholangiopancreatograms obtained in 50 consecutive patients were quantitatively analyzed with region-of-interest measurements and were qualitatively evaluated by three independent radiologists unaware the patient information. A phantom study was performed to verify the effects., Results: The mean contrast-to-noise ratios of the gallbladder, common bile duct, and main pancreatic duct significantly increased after gadolinium chelate administration (p < 0.005). The mean depiction score of the main pancreatic duct increased significantly with one radiologist (p < 0.05) and marginally with another (p < 0.06), and the mean depiction scores of the background structures and renal pelvis significantly decreased with all three radiologists (p < 0.001). The phantom study showed the results, indicating that T2- and T2(*)-shortening effects of gadolinium chelate caused the effects in vivo., Conclusion: i.v. administration of gadolinium chelate improves the depiction of pancreaticobiliary ducts in some selected patients, while decreasing the depiction in others with less frequency. There may be a value of enhanced MR cholangiopancreatography when unenhanced MR cholangiopancreatography is not sufficient.

MR imaging, which is able to evaluate T1- and T2-relaxation time, fat, hemorrhage, metal deposition, blood flow, perfusion, diffusion, and so on, has offered more information for the diagnosis of diffuse and focal hepatic diseases than CT. The spoiled-GRE sequence with high contrast resolution and ease of the aimed contrast capture derived from the k-space property, with the use of a phased-array multicoil, have remarkably increased the value of gadolinium-enhanced dynamic MR diagnosis of the liver. In recent years, the clinical use of ferumoxide has begun, and issues concerning the superiority or inferiority and combination of contrast media are being debated. This paper describes the value, role, and clinical practice of unenhanced, gadolinium-enhanced, and ferumoxide-enhanced MR imaging of the liver based on knowledge obtained in our institution, with some reference to the literature.

We encountered a case of left hepatic duct cancer that developed 7 years after surgical resection of early-stage adenocarcinoma of the gallbladder. A 65-year-old woman was hospitalized with high fever and general fatigue. She also had elevated serum levels of alkaline phosphatase, gamma-glutamyltranspeptidase, and carbohydrate antigen 19-9. Seven years earlier, she had undergone extended cholecystectomy and resection of the extrahepatic bile duct for early-stage mucinous adenocarcinoma of the gallbladder. Conventional examinations did not reveal any responsible lesions. Magnetic resonance (MR) cholangiography, however, showed a tumor obstructing the left hepatic duct, and dynamic MR images revealed multiple foci of bacterial abscess in the liver. Surgically resected tissue again revealed mucinous adenocarcinoma. The present case is rare in that metachronous mucinous adenocarcinoma of the biliary system occurred after a long interval. This case suggests the usefulness of MR imaging in the postsurgical monitoring of patients with gallbladder carcinoma.

Purpose: Because of the recent innovative growth in computer technology, digital imaging, and the Internet, we can take advantage of these facilities for education and clinical work in nuclear medicine. We developed a tele-nuclear medicine conference system with electronic mail (e-mail) on the Internet., Methods: Twenty-one physicians (20 radiologists, 1 neurologist), 6 technologists and 2 medical students in six university hospitals (Japan 5, Canada 1), 5 local hospitals in Japan participated in this project. We used digital still cameras (330 k pixels) equipped with a floppy disk drive and 10 x optical zoom to digitize images with JPEG compression (640 x 480 matrix). The images were attached to e-mail messages (containing a brief description of each case). The mail was sent simultaneously to all members on the mailing list. Scintigram and SPECT images as well as other radiological images were sent by e-mail. Reply mails about each case were sent to all members via the mailing list., Results: During a period of 6 months, 18 cases (tumor/infection: 7, bone: 6, cardiovascular: 1, neurology; 3, endocrine: 1) with 144 e-mails (average 5.6/case) were submitted to the conference. The average period of discussion was 15.6 days. The number of attached images was 1 to 9 (average, 4.2/e-mails). JPEG compression rate was 1/10 to 1/20. The quality of the images was good enough for discussion. Some cases required additional images for further discussion., Conclusion: Our tele-nuclear medicine conference with an electronic mailing list and digital camera was simple and low-cost. The conference system was useful for education and clinical work.

Objective: The purpose of our study was to compare how well gadolinium-enhanced and ferumoxide-enhanced MR imaging reveal malignant hepatic tumors., Subjects and Methods: Both gadolinium-enhanced and ferumoxide-enhanced MR imaging were separately performed in 53 patients with a total of 87 malignant hepatic tumors (57 hepatocellular carcinomas, 28 metastases, two cholangiocarcinomas). Thirty-one of the 53 patients had hepatic cirrhosis. Images were reviewed by three independent off-site observers. Observer performance was evaluated by means of sensitivity, specificity, and receiver operating characteristic curve analyses., Results: Gadolinium-enhanced MR imaging outperformed ferumoxide-enhanced MR imaging in sensitivity (81% versus 62%, p < 0.01) for malignant-tumor detection. Specificity was comparable (94%) between the two types of MR imaging. Area under receiver operating characteristic curve (A(z)) value was significantly higher with gadolinium-enhanced MR imaging than with ferumoxide-enhanced MR imaging in patients overall (A(z) = 0.896 versus 0.805, p < 0.001), in patients with cirrhosis (A(z) = 0.907 versus 0.807, p < 0.001), and in patients without cirrhosis (A(z) = 0.899 versus 0.834, p < 0.01). The superiority was enhanced in the subset of patients with cirrhosis., Conclusion: Gadolinium-enhanced MR imaging outperforms ferumoxide-enhanced MR imaging in revealing malignant hepatic tumors. Gadolinium-enhanced MR imaging is recommended, particularly for patients with cirrhosis.

Objective: The purpose of our study was to compare observer performances for the diagnosis of choledocholithiasis using MR cholangiography with volume-rendered, maximum-intensity-projection, and thick-section half-Fourier rapid acquisition with relaxation enhancement sequences., Materials and Methods: The images from three types of MR cholangiography performed on 43 patients with biliary calculi were retrospectively analyzed. Image review was conducted for two anatomic compartments (upper biliary tract and common bile duct). A total of 86 compartments, including 19 with bile duct calculi, were reviewed by three independent off-site gastrointestinal radiologists. Observer performance was determined by receiver operating characteristic curve analysis. Image quality was subjectively judged by three radiologists., Results: Sensitivity was higher with volume-rendered MR cholangiography (58%) than with thick-section (54%, not significant) and maximum-intensity-projection MR cholangiography (47%, p < 0.07). Specificity was higher with volume-rendered MR cholangiography (92%) than with thick-section (86%, p < 0.03) and maximum-intensity-projection MR cholangiography (88%, not significant). Accuracy was higher with volume-rendered MR cholangiography (84%) than with thick-section and maximum-intensity-projection MR cholangiography (79% for both, not significant). Observer performance with volume-rendered MR cholangiography (A(z) = 0.791--0.952) was better than that with thick-section (A(z) = 0.722--0.834) and maximum-intensity-projection MR cholangiography (A(z) = 0.771--0.887). Image quality was better with maximum-intensity-projection MR cholangiography and thick-section MR cholangiography than with volume-rendered MR cholangiography (p < 0.0001)., Conclusion: Observer performance with volume-rendered MR cholangiography was better than that with maximum-intensity-projection and thick-section MR cholangiography for the diagnosis of choledocholithiasis. Volume rendering may be an efficient technique for the reconstruction of MR cholangiography.

We describe ferumoxides-enhanced magnetic resonance imaging findings in a 60-year-old man with confluent hepatic fibrosis in advanced cirrhosis. The extension and internal structure of confluent fibrosis were well demonstrated with ferumoxides-enhanced proton-density spin-echo magnetic resonance images, showing a wedge-shaped area of high signal intensity corresponding to the extension of fibrosis and internal focal areas of low signal intensity, presumably corresponding to residual functioning liver parenchyma. This case suggests a potential utility of ferumoxides-enhanced magnetic resonance imaging for characterizing this tumor-mimicking disorder.

The purpose of our study was to compare observer performance in the detection of malignant hepatic tumors with ferumoxides-enhanced magnetic resonance (MR) images obtained with proton density-weighted spin-echo (SE), T2-weighted fast SE, T2*-weighted gradient-recalled-echo (GRE), and proton density-weighted echo-planar (EP) sequences. Ferumoxides-enhanced MR images obtained with the four sequences in 50 patients with 92 solid malignant and 64 nonsolid benign lesions were retrospectively analyzed. Image review was conducted on a segment-by-segment basis; a total of 397 liver segments was reviewed separately for solid and nonsolid lesions by three independent readers. Observer performance was evaluated with receiver operating characteristic analysis. Lesion-to-liver contrast-to-noise ratio was higher with SE and EP than with GRE and fast SE images for solid lesions (P < 0.05), and higher with fast SE and SE than with GRE images for nonsolid lesions (P < 0.01). Proton density-weighted SE and T2-weighted fast-SE images were superior to T2*-weighted GRE and proton density-weighted EP images for detection of malignant hepatic tumors. T2-weighted fast SE images were the best for detection of nonsolid lesions. T2-weighted fast SE images that were comparable to proton density-weighted SE images for solid tumor detection, that were the best for nonsolid lesion detection, and that had an acquisition time of one third to half of that of SE imaging may be able to replace SE images for ferumoxides-enhanced liver imaging.

A retrospective study was performed to evaluate whether dynamic MR imaging is useful for the diagnosis of axillary lymph node metastases from breast cancer. Thirty-five patients with breast cancer were scanned and 147 lymph nodes were detected and compared with pathological nodal status. The parameters were the long axis dimension, the short axis dimension, the long-to-short axis (L/S) ratio, the shape, the contrast enhancement ratio (CER), the CER of lymph node-to-primary tumor (L/P) ratio. All parameters had significant differences between metastatic and normal nodes and there was a positive correlation between the CER of primary breast tumors and metastatic nodes. Multivariate analysis identified three parameters: the shape, the CER (1st phase), the L/P ratio (1st phase). ROC analysis revealed the shape and CER are superior in diagnostic performance to L/P ratio. If the shape and CER (1st phase) 60% and above are employed as criteria, the sensitivity, the specificity, the accuracy and the positive and negative predictive value were 86.0%, 78.4%, 81.0%, 67.2% and 91.6%, respectively. This method gives us useful information about the evaluation of axillary lymph node status preoperatively.

Objective: The objective of our study was to evaluate the efficacy of single breath-hold T2-weighted MR imaging for detection of focal hepatic lesions., Materials and Methods: T2-weighted MR images were retrospectively reviewed from 51 patients with 85 solid and 59 nonsolid lesions using the following four sequences: conventional spin-echo, respiratory-triggered fast spin-echo, single-shot fast spin-echo, and multishot spin-echo echoplanar imaging. Images were reviewed on a hepatic segment-by-segment basis; T2-weighted images of a total of 408 hepatic segments were reviewed separately and independently for solid and nonsolid lesions by four radiologists. Quantitative, qualitative, and receiver operating characteristic analyses were performed., Results: For solid lesions, no significant differences were seen among the lesion-to-liver contrast-to-noise ratios with the four sequences. In terms of solid lesion detection, no significant difference was seen between the diagnostic accuracy of multishot spin-echo echoplanar (Az = 0.90) and respiratory-triggered fast spin-echo (Az = 0.91) imaging, which showed the best performance of the four sequences. For nonsolid lesion detection, respiratory-triggered fast spin-echo and single-shot fast spin-echo imaging were judged the best (Az = 0.94)., Conclusion: Breath-hold single-shot fast spin-echo and multishot spin-echo echoplanar sequences can be substituted for conventional spin-echo and respiratory-triggered fast spin-echo T2-weighted sequences.

Objective: We compared radiologists' performance on combined unenhanced, gadolinium-enhanced, and ferumoxides-enhanced MR imaging with their performance on helical CT during arterial portography (CTAP) and biphasic CT during hepatic arteriography (CTHA) for the preoperative detection of malignant hepatic tumors., Subjects and Methods: MR images and CT scans obtained in 33 patients were retrospectively analyzed. Images of the liver were reviewed on a segment-by-segment basis; a total of 261 segments with 39 hepatocellular carcinomas and 21 metastases were independently reviewed by three radiologists who were invited from outside institutions. Unenhanced and gadolinium-enhanced MR images were reviewed first, then ferumoxides-enhanced MR images were added for combined review. CTAP images and biphasic CTHA images were reviewed together., Results: Sensitivity for the detection of hepatic tumors was analogous for combined unenhanced, gadolinium-enhanced, and ferumoxides-enhanced MR images (86%) and for combined CTAP images and biphasic CTHA images (87%). Specificity was higher with MR images (95%, p < 0.01) than with CT images (91%). Radiologists' performances were improved (Az = 0.962, p = 0.0502) by combining ferumoxides-enhanced MR images with unenhanced and gadolinium-enhanced MR images (Az = 0.950), and were analogous for combined unenhanced, gadolinium-enhanced, and ferumoxides-enhanced MR images and for combined CTAP images and biphasic CTHA images (Az = 0.959)., Conclusion: Radiologists' performances on combined unenhanced, gadolinium-enhanced, and ferumoxides-enhanced MR imaging compared with their performances on combined helical CTAP and biphasic CTHA are analogous for the preoperative detection of malignant hepatic tumors. Such a dedicated combination of MR imaging may obviate the need for more invasive angiographically assisted helical CT for the preoperative detection of malignant hepatic tumors.

Purpose: To investigate the effect of imaging delay on gadolinium enhancement of the pancreas and peripancreatic vessels at dynamic gradient-recalled-echo magnetic resonance (MR) imaging of the pancreas., Materials and Methods: Dynamic MR images were obtained after intravenous bolus injection of gadopentetate dimeglumine in 75 patients with no pancreatic malignancies. Test-bolus imaging was performed to determine aortic transit time in individual patients. Patients were randomly assigned so that the middle of k space was acquired at 5, 15, 25, 35, or 45 seconds after arrival of contrast material in the abdominal aorta. Mean signal intensities of pancreas, liver, and peripancreatic vessels were measured, and images were qualitatively assessed by two radiologists., Results: The best pancreatic enhancement occurred at a delay of 15 seconds (P <.05). The best enhancement of the liver and peripancreatic vessels occurred at 25 seconds or later (P <.05). Qualitatively, the best images of the pancreas were obtained at 15 seconds, and the best images of the liver and peripancreatic vessels were obtained at 25 seconds or later., Conclusion: Biphasic imaging at 15 and 45 seconds or later after arrival of contrast material in the abdominal aorta is a practical method for acquisition of high-quality dynamic gradient-recalled-echo MR images of the pancreas.

Background: To compare the diagnostic accuracy of magnetic resonance (MR) images obtained with three different pulse sequences for lymph-node metastases in patients with gastric cancer., Methods: T1-weighted spin-echo (SE), breath-hold T2-weighted fast SE, and triphasic gadolinium-enhanced dynamic gradient-recall-echo (GRE) MR images obtained in 16 patients with gastric carcinoma were retrospectively reviewed. Regional lymph nodes were assigned to four different groups, and image review was conducted on a lymph-node group-by-group basis; 64 lymph-node groups were reviewed by two radiologists. Relative sensitivity, specificity, and accuracy were determined based on the findings with definitive surgery and follow-up imaging. Diagnostic accuracy was determined by means of receiver-operating-characteristic (ROC) analysis., Results: Relative sensitivities for lymph-node metastases with T1-weighted SE, breath-hold T2-weighted fast SE, and dynamic GRE images were 61%, 94%, and 59%, respectively. Relative sensitivity with breath-hold T2-weighted fast SE images was significantly greater than that with T1-weighted SE (p < 0.05) and dynamic GRE (p < 0.05) images. Diagnostic accuracy determined by ROC analysis was marginally higher with breath-hold T2-weighted fast SE (area under ROC curve [Az] = 0.87) than with T1-weighted SE (Az = 0.78, p = 0.08) and dynamic GRE (Az = 0.79, p = 0.12) images., Conclusion: Breath-hold T2-weighted fast SE sequence is useful in the detection of regional lymph-node metastases in patients with gastric carcinoma.

Objective: The purpose of our study was to compare the diagnostic performance of low- and high-spatial-resolution gadolinium chelate-enhanced triphasic dynamic gradient-recalled echo (GRE) MR images in the detection of hepatocellular carcinoma., Materials and Methods: Triphasic dynamic MR images obtained with low (256 x 128) and high (512 x 224) image matrices in 28 patients with 65 hepatocellular carcinomas (HCCs) were retrospectively analyzed. Image review was conducted on a segment-by-segment basis; a total of 215 liver segments, including 56 segments with tumor burden, were reviewed for the presence of HCC by three independent radiologists. Detectability was evaluated with relative sensitivity, specificity, and receiver operating characteristic (ROC) analysis. Image quality was evaluated with rank order analysis., Results: Relative sensitivity was statistically significantly better with high-spatial-resolution images than with low-spatial-resolution images (p < .005). Relative specificity was statistically significantly better with low-spatial-resolution images than with high-spatial-resolution images (p < .001). Diagnostic accuracy determined by ROC curve analysis was marginally higher with high-spatial-resolution (area under ROC curve [Az] = .97) than with low-spatial-resolution (Az = .94, p < .09) images. Image quality was statistically significantly better with high-spatial-resolution images (p < .005)., Conclusion: High-spatial-resolution dynamic GRE images were superior to low-spatial-resolution images in sensitivity of detecting HCC and in image quality. Triphasic dynamic GRE imaging in the screening and follow-up programs of patients with suspected HCC should be performed using high image matrices.