Hepatic lesion detection and characterization: value of nonenhanced MR imaging, superparamagnetic iron oxide-enhanced MR imaging, and spiral CT-ROC analysis

PURPOSE: To determine the accuracy for detection and characterization of focal hepatic lesions of nonenhanced, superparamagnetic iron oxide (SPIO)-enhanced, or a combination of nonenhanced and SPIO-enhanced MR imaging and contrast-enhanced spiral computed tomography (CT). MATERIALS AND METHODS: Spiral CT and T2-weighted SPIO-enhanced (ferucarbotran-enhanced) MR imaging were performed in 35 patients within 2 weeks before surgery for malignant hepatic lesions. Only malignant lesions with histopathologic proof were considered. A total of 875 images with and 800 images without focal lesions were presented to five readers, who were asked to assess the presence and characterization of lesions by using a five-point confidence scale. Receiver operating characteristic analysis was performed. RESULTS: Nonenhanced and SPIO-enhanced images together and SPIO-enhanced images alone yielded the best performance for lesion detection. No differences were found among all imaging techniques with regard to lesion characterization (benign vs malignant). The combined approach resulted in larger area under the ROC curve (A(z) = 0.9062) and accuracy (85.3%) (P < 0.02), as compared with SPIO-enhanced MR imaging (A(z) = 0.8667; accuracy, 73.1%). CONCLUSION: SPIO-enhanced T2-weighted MR imaging was more accurate than nonenhanced T1-weighted and T2-weighted MR imaging and contrast-enhanced spiral CT for the detection of focal hepatic lesions. The combined analysis of nonenhanced and SPIO-enhanced images was more accurate in the characterization of focal hepatic lesions than was review of SPIO-enhanced images alone.     

Hepatocellular carcinoma in patients with chronic liver disease: comparison of SPIO-enhanced MR imaging and 16-detector row CT

PURPOSE: To compare the sensitivity, positive predictive value, and diagnostic accuracy of superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) imaging with those of 16-detector row computed tomography (CT) for the detection of hepatocellular carcinoma (HCC) in patients with hepatitis B-induced cirrhosis. MATERIALS AND METHODS: Institutional Review Board approval was obtained for this study, and informed consent was obtained from all patients. A total of 44 patients (36 men, eight women; age range, 35-67 years) with 59 HCCs and mild liver cirrhosis (Child-Pugh score A or B) underwent multiphasic CT and SPIO-enhanced MR imaging. The diagnosis of HCC was established at surgical resection (n = 31) and percutaneous biopsy (n = 28). SPIO-enhanced MR imaging was composed of T2-weighted turbo spin-echo and T2*-weighted gradient-echo sequences. Multiphasic CT consisted of four phases (ie, early arterial, late arterial, portal venous, and equilibrium). Three observers independently analyzed each image in random order. Sensitivity, positive predictive value, and diagnostic accuracy were calculated by using the alternative free-response receiver operating characteristic analysis for multi-detector row CT and SPIO-enhanced MR imaging. RESULTS: Although not significant (P > .05), the area under the receiver operating characteristic curve for SPIO-enhanced MR imaging (mean, 0.90) was higher than that for multi-detector row CT (mean, 0.82) for all observers. Also, although no significant difference was demonstrated by any of the three observers (P > .05), there was a trend toward increased sensitivity on both a per-lesion and a per-patient basis for SPIO-enhanced MR imaging (mean, 84.7% and 94.7%, respectively) compared with multi-detector row CT (mean, 76.9% and 88.6%, respectively). No significant difference in positive predictive value was observed between modalities. CONCLUSION: SPIO-enhanced MR imaging and multiphasic CT show similar diagnostic accuracy, sensitivity, and positive predictive value for the detection of HCC in patients with relatively mild hepatitis B-induced cirrhosis.     

Three-dimensional dynamic liver MR imaging using sensitivity encoding for detection of hepatocellular carcinomas: comparison with superparamagnetic iron oxide-enhanced mr imaging

PURPOSE: To assess the diagnostic performance of three-dimensional dynamic liver imaging with sensitivity encoding (SENSE), including double arterial phase images and increased resolution, by comparing it to superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) imaging for the detection of hypervascular hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Twenty-seven consecutive patients with 50 HCCs underwent Gd-BOPTA-enhanced dynamic imaging using SENSE and SPIO-enhanced MR imaging with at least a 24-hour interval between examinations. Using a three-dimensional gradient-echo technique applying SENSE, dynamic imaging consisting of double arterial phase-, portal phase- and delayed phase-images, was obtained. Using T2-weighted turbo spin-echo and T2*-weighted fast imaging with steady-state precession sequence, SPIO-enhanced MR imaging was obtained. For qualitative analysis, the diagnostic accuracy of both MR examinations for detecting the 50 HCCs was evaluated using the alternative free-response receiver operating characteristic method. Sensitivity and positive predictive value were also evaluated. RESULTS: The mean sensitivity and positive predictive value of three-dimensional dynamic imaging with SENSE were 91.3% and 89.2%, respectively, and those of SPIO-enhanced imaging were 77.3% and 92.6 %, respectively. There was a significant difference in sensitivity between the two images (P <0.05). The mean Az value of three-dimensional dynamic imaging with SENSE (0.97 +/- 0.01) was significantly higher than that of SPIO-enhanced imaging (0.90 +/- 0.02) (P=0.00). CONCLUSION: Three-dimensional dynamic liver MR imaging using SENSE for acquiring double arterial phase images is more efficient than SPIO-enhanced MR imaging for detecting HCCs.     

Superparamagnetic iron oxide-enhanced MR imaging of head and neck lymph nodes.

PURPOSE: To compare findings on superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) images of the head and neck with those from resected lymph node specimens and to determine the effect of such imaging on surgical planning in patients with histopathologically proved squamous cell carcinoma of the head and neck. MATERIALS AND METHODS: Thirty patients underwent MR imaging with nonenhanced and SPIO-enhanced (2.6 mg Fe/kg intravenously) T1-weighted (500/15 [repetition time msec/echo time msec]) and T2-weighted (1,900/80) spin-echo and T2-weighted gradient-echo (GRE) (500/15, 15 degrees flip angle) sequences. Signal intensity decrease was measured, and visual analysis was performed. Surgical plans were modified, if necessary, according to MR findings. Histopathologic and MR findings were compared. RESULTS: Histopathologic evaluation of 1,029 lymph nodes revealed 69 were metastatic. MR imaging enabled detection of 59 metastases. Regarding lymph node levels, MR diagnosis was correct in 26 of 27 patients who underwent surgery: Only one metastasis was localized in level II with MR imaging, whereas histopathologic evaluation placed it at level III. Extent of surgery was changed in seven patients. SPIO-enhanced T2-weighted GRE was the best sequence for differentiating between benign and malignant lymph nodes. CONCLUSION: SPIO-enhanced MR imaging has an important effect on planning the extent of surgery. On a patient basis, SPIO-enhanced MR images compared well with resected specimens.     

Hepatic lesion detection: comparison of MR imaging after the administration of superparamagnetic iron oxide with dual-phase CT by using alternative-free response receiver operating characteristic analysis

PURPOSE: To compare the performance of magnetic resonance (MR) imaging after the administration of superparamagnetic iron oxide (SPIO) and dual-phase computed tomography (CT) in the depiction of liver metastases. MATERIALS AND METHODS: Fifty-one hepatic resection candidates with known colorectal metastases were examined. MR imaging comprised fast spin-echo (SE) T2-weighted imaging, T1-weighted gradient-echo (GRE) fast low-angle shot imaging before SPIO enhancement, dual-echo SE imaging, T2-weighted fast low-angle shot imaging, and T1-weighted GRE imaging after SPIO enhancement. CT was performed with 8-mm collimation and 1:1 pitch; imaging commenced 20 seconds and 65-70 seconds after injection of 150 mL of contrast medium. All images were reviewed independently by four blinded observers. The alternative-free response receiver operating characteristic (ROC) method was used to analyze the results, which were correlated with findings from surgery, intraoperative ultrasonography, and histopathologic studies in 31 patients and with consensus review together with all other imaging and clinical follow-up in 20 patients. Sensitivities were also calculated. RESULTS: The mean sensitivity of MR was significantly higher than that of CT (p < .02): 79.8% for MR and 75.3% for CT for all lesions, and 80.6% for MR and 73.5% for CT for malignant lesions. The mean areas under the alternative-free response ROC curves were 0.83 for MR and 0.78 for CT (difference not significant). CONCLUSION: SPIO-enhanced MR imaging was more sensitive than dual-phase CT in the depiction of colorectal metastases.     

Detection of liver metastases: gadobenate dimeglumine-enhanced three-dimensional dynamic phases and one-hour delayed phase MR imaging versus superparamagnetic iron oxide-enhanced MR imaging

The aim of this study was to compare the diagnostic performance of gadobenate dimeglumine (Gd-BOPTA)-enhanced MR imaging, including dynamic phases and one-hour delayed phase, versus superparamagnetic iron oxide (SPIO)-enhanced imaging for detection of liver metastases. Twenty-three patients with 59 liver metastases underwent Gd-BOPTA-enhanced MR imaging (unenhanced, arterial, portal, equilibrium and one-hour delayed phase) using three-dimensional volumetric interpolated imaging and SPIO-enhanced T2-weighted turbo spin–echo and T2*-weighted gradient-echo sequences on a 1.5-T unit. Three observers independently interpreted the three sets of images, i.e. Gd-BOPTA-enhanced dynamic MRI (set 1), delayed phase imaging (set 2) and SPIO-enhanced MRI (set 3). Diagnostic accuracy was evaluated using the alternative-free response receiver operating chracteristic (ROC) analysis. Sensitivity and positive predictive value were also evaluated. The mean accuracy (Az values) and sensitivity of Gd-BOPTA-enhanced delayed phase imaging (0.982, 95.5%) were comparable to those of SPIO-enhanced imaging (0.984, 97.2%). In addition, Az values and sensitivities of both imaging sets were significantly higher than those of Gd-BOPTA-enhanced dynamic images (0.826, 77.4%: p<0.05). There was no significant difference in the positive predictive value among the three image sets. Gd-BOPTA-enhanced delayed phase imaging showed comparable diagnostic performance to SPIO-enhanced imaging for the detection of liver metastases, and had a better diagnostic performance than Gd-BOPTA-enhanced dynamic images.     

Hepatic metastases: diffusion-weighted sensitivity-encoding versus SPIO-enhanced MR imaging

PURPOSE: To retrospectively compare accuracy of diffusion-weighted (DW) single-shot echo-planar imaging with sensitivity encoding (SENSE) with that of superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) imaging in the evaluation of hepatic metastases due to extrahepatic malignancies. MATERIALS AND METHODS: Patients provided informed consent; ethics committee approval was not required. The data of 24 patients (16 men, eight women; age range, 41-68 years; mean age, 61.9 years) with 40 resected hepatic metastases were retrospectively reviewed. Before SPIO administration, DW SENSE imaging and T2-weighted fast spin-echo (SE) and T1-weighted dual-echo fast field-echo (FFE) MR imaging were performed. After SPIO administration, T2-weighted fast SE, T1-weighted dual-echo, and T2*-weighted FFE MR examinations were performed. Images were divided into two sets: The SPIO-enhanced MR image set consisted of pre- and postcontrast T2-weighted fast SE and dual-echo T1-weighted FFE images and postcontrast T2*-weighted FFE images. The DW SENSE image set included DW SENSE images and precontrast T2-weighted fast SE and dual-echo T1-weighted FFE images. Three radiologists individually interpreted these images and sorted the confidence levels for presence of hepatic metastasis in each section into five grades. Area under the receiver operating characteristic (ROC) curve (A(z)) was calculated for each image set. RESULTS: Hepatic metastases showed higher signal intensity on DW SENSE images than on T2-weighted fast SE images. Conversely, signals from vessels and cysts were suppressed with DW SENSE imaging. ROC analysis showed higher A(z) values when the DW SENSE image set was interpreted (0.90) than when the SPIO-enhanced MR image set was interpreted (0.81). The sensitivity and specificity, respectively, of total cases were 0.66 and 0.90, for the SPIO-enhanced MR image set and 0.82 and 0.94 for the DW SENSE image set. During SPIO-enhanced MR image interpretation, lesions 1 cm in diameter or smaller showed significantly lower sensitivity than lesions larger than 1 cm in diameter. During both interpretation sessions, left lobe lesions showed significantly lower sensitivity than right lobe lesions. CONCLUSION: Combined reading of DW SENSE images and T2-weighted fast SE and dual-echo T1-weighted FFE MR images showed higher accuracy in the detection of hepatic metastases than did reading of SPIO-enhanced MR images.     

Comparison of superparamagnetic iron oxide-enhanced and gadobenate dimeglumine-enhanced dynamic MRI for detection of small hepatocellular carcinomas

OBJECTIVE: The purpose of this study was to compare superparamagnetic iron oxide (SPIO)-enhanced MRI with gadobenate dimeglumine-enhanced MRI for the detection of hepatocellular carcinoma using receiver operating characteristic (ROC) analysis. MATERIALS AND METHODS: Twenty-nine consecutive patients with 35 hepatocellular carcinomas underwent gadobenate dimeglumine-enhanced MRI (unenhanced, arterial, portal, and equilibrium phases) using 3D fat-saturated volumetric interpolated imaging and SPIO-enhanced MRI on a 1.5-T unit. SPIO-enhanced T2-weighted turbo spin-echo and T2*-weighted gradient-echo sequences were performed 48 hr after completion of the dynamic study. Three observers independently interpreted the images in random order, separately, and without patient identifiers. Diagnostic accuracy was evaluated using the alternative free response receiver operating characteristic method. Sensitivity and positive predictive value were also evaluated. RESULTS: The mean sensitivity and positive predictive value of SPIO-enhanced imaging were 81.0% and 85.0%, respectively, and those of gadobenate dimeglumine-enhanced MRI were 91.4% and 88.1%, respectively. A significant difference was seen in the sensitivity of the two MRI examinations (p < 0.05). The mean value of the area under the ROC curve (A(z)) for gadobenate dimeglumine-enhanced imaging (A(z) = 0.97 +/- 0.01) was significantly higher than that for SPIO-enhanced imaging (A(z) = 0.90 +/- 0.02) (p = 0.004). CONCLUSION: Gadobenate dimeglumine-enhanced 3D dynamic imaging showed better diagnostic performance than SPIO-enhanced imaging for the detection of hepatocellular carcinomas.     

Detection of hypervascular hepatocellular carcinoma: comparison of SPIO-enhanced MRI with dynamic helical CT

PURPOSE: The purpose of this study was to compare the diagnostic performance of superparamagnetic iron oxide (SPIO)-enhanced MRI for the detection of hypervascular hepatocellular carcinoma (HCC) with dynamic helical CT. METHODS: SPIO-enhanced MR and dynamic helical CT images obtained from 41 patients with 52 hypervascular HCCs (5-130 mm; mean, 27 mm) were retrospectively analyzed. MRI were obtained with 1.5 T scanners using T2-weighted and proton density-weighted spin-echo (or fast spin-echo) sequences for all cases and a T2*-weighted gradient echo sequence for 36 cases. Four blinded observers reviewed images independently. Diagnostic accuracy was evaluated using alternative-free response receiver operating characteristic (AFROC) method. Sensitivities and positive predictive values (PPV) were also evaluated. RESULTS: The areas under the AFROC curves for each observer were greater for MR than for CT (means, 0.81 and 0.76; p < 0.05). The mean sensitivities for MR and CT were 0.75 and 0.71, respectively (p = 0.13). The mean PPVs were 0.83 and 0.79 (p = 0.21). CONCLUSION: SPIO-enhanced MRI showed slightly better diagnostic performance than dynamic helical CT for the detection of hypervascular HCCs.     

Hepatic metastases: detection with multi-detector row CT, SPIO-enhanced MR imaging, and both techniques combined

PURPOSE: To retrospectively compare the accuracy in detection of hepatic metastases among contrast material-enhanced multi-detector row computed tomography (CT) alone, superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) imaging alone, and a combination of contrast-enhanced CT and SPIO-enhanced MR imaging. MATERIALS AND METHODS: The ethics committee did not require its approval or informed consent for this retrospective study, which was compliant with Declaration of Helsinki principles. Data in 38 patients (22 men, 16 women; mean age, 64.5 years; range, 35-78 years) suspected of having hepatic metastases who underwent both contrast-enhanced CT and SPIO-enhanced MR imaging were retrospectively analyzed. Twenty-one of the 38 patients had 61 metastases. Seventeen of the 61 metastases were confirmed histologically; the remaining 44 metastases were defined with imaging follow-up. At MR imaging, SPIO-enhanced heavily T1-weighted images, T2*-weighted gradient echo images, and T2-weighted fast spin-echo images were evaluated. Contrast-enhanced multi-detector row CT images obtained in the portal phase were evaluated. Four blinded observers independently reviewed CT images, MR images, and the combination of CT and MR images. Diagnostic accuracy was evaluated by using the alternative free-response receiver operating characteristic (AFROC) method. Sensitivities and positive predictive values were also analyzed with the Fisher protected least significant difference test and generalized estimating equations. RESULTS: The mean area under the AFROC curve for the combined approach (0.70) was significantly higher than that for SPIO-enhanced MR imaging alone (0.58, P < .05, Fisher protected least significant difference test), and there was no significant difference between each of them and that for contrast-enhanced CT alone (0.66). For all lesions, the mean sensitivity of combined imaging (0.59) was significantly higher than that of CT (0.48) or MR imaging (0.43) alone (P < .05, Fisher protected least significant difference test and generalized estimating equations). For all lesions, the mean positive predictive values were 0.82, 0.89, and 0.81, for combined MR and CT, CT alone, and MR alone, respectively. CONCLUSION: The addition of SPIO-enhanced MR imaging to contrast-enhanced multi-detector row CT (ie, combined analysis of SPIO-enhanced MR images and contrast-enhanced CT images) can improve sensitivity in the detection of hepatic metastases, although this improvement in sensitivity was not significant at AFROC analysis.     

Benign versus malignant hepatic nodules: MR imaging findings with pathologic correlation.

According to the currently used nomenclature, there are only two types of hepatocellular nodular lesions: regenerative lesions and dysplastic or neoplastic lesions. Regenerative nodules include monoacinar regenerative nodules, multiacinar regenerative nodules, cirrhotic nodules, segmental or lobar hyperplasia, and focal nodular hyperplasia. Dysplastic or neoplastic nodules include hepatocellular adenoma, dysplastic foci, dysplastic nodules, and hepatocellular carcinoma (HCC). Many of these types of hepatic nodules play a role in the de novo and stepwise carcinogenesis of HCC, which comprises the following steps: regenerative nodule, low-grade dysplastic nodule, high-grade dysplastic nodule, small HCC, and large HCC. State-of-the-art magnetic resonance (MR) imaging facilitates detection and characterization in most cases of hepatic nodules. State-of-the-art MR imaging includes single-shot fast spin-echo imaging, in-phase and opposed-phase T1-weighted gradient-echo imaging, T2-weighted fast spin-echo imaging with fat saturation, and two-dimensional or three-dimensional dynamic multiphase contrast material-enhanced imaging.     

Colorectal hepatic metastases: detection with SPIO-enhanced breath-hold MR imaging--comparison of optimized sequences

PURPOSE: To compare the accuracy of four breath-hold magnetic resonance (MR) imaging sequences to establish the most effective superparamagnetic iron oxide (SPIO)-enhanced sequence for detection of colorectal hepatic metastases. MATERIALS AND METHODS: Thirty-one patients with colorectal hepatic metastases underwent T1-weighted gradient-echo (GRE) and T2-weighted fast spin-echo (FSE) MR imaging before and after SPIO enhancement. Four sequences were optimized for lesion detection: T2-weighted FSE, multiecho data image combination (MEDIC), T2-weighted GRE with an 11-msec echo time (TE), and T2-weighted GRE with a 15-msec TE. Images were reviewed independently by three blinded observers. The accuracy of each sequence was measured by using alternative free-response receiver operating characteristic analysis. All results were correlated with findings at surgery, intraoperative ultrasonography, or histopathologic examination. Differences between the mean results of the three observers were measured by using the Student t test. RESULTS: Postcontrast T2-weighted GRE sequences were the most accurate and were significantly superior to postcontrast T2-weighted FSE and unenhanced sequences alone (P <.05). For all lesions that were malignant or smaller than 1 cm, respectively, mean accuracies of postcontrast sequences were 0.082 and 0.64 for T2-weighted FSE, 0.90 and 0.78 for MEDIC, 0.92 and 0.80 for GRE with an 11-msec TE, 0.93 and 0.82 for GRE with a 15-msec TE, and 0.81 and 0.62 for unenhanced sequences. CONCLUSION: Optimized SPIO-enhanced T2-weighted GRE combined with unenhanced T2-weighted FSE MR sequences were the most sensitive. Breath-hold FSE postcontrast sequences offer no improvement in sensitivity compared with unenhanced sequences alone.     

Retrograde cortical and deep venous drainage in patients with intracranial dural arteriovenous fistulas: comparison of MR imaging and angiographic findings

BACKGROUND AND PURPOSE: We assessed MR imaging, specifically contrast-enhanced three-dimensional (3D) magnetization-prepared rapid gradient-echo (MP-RAGE), in evaluating retrograde venous drainage in patients with intracranial dural arteriovenous fistulas (dAVFs) that may result in catastrophic venous infarction or hemorrhage. METHODS: Twenty-one patients with angiographically proved dAVFs underwent nonenhanced spin-echo (SE) and fast SE imaging, 3D fast imaging with steady-state precession, and enhanced SE and 3D MP-RAGE imaging. Retrograde venous drainage was categorized as cerebral cortical, deep cerebral, posterior fossa medullary, ophthalmic, or spinal venous. We assessed retrograde venous drainage and graded its severity. MR imaging and angiographic severities were correlated. Sensitivity, specificity, and accuracy were calculated to evaluate the diagnostic utility of each technique compared with conventional angiography. We retrospectively correlated angiograms and MR images. RESULTS: Enhanced 3D MP-RAGE and T1-weighted SE images had higher diagnostic accuracy higher than nonenhanced images, especially when retrograde drainage involved cerebral cortical, posterior fossa, and spinal veins. Correlation of severity for enhanced MP-RAGE images and enhanced T1-weighted images with angiograms was good to excellent and better than that with nonenhanced images. All sequences had low diagnostic accuracy when drainage was via deep cerebral veins. On retrospective review, 3D MP-RAGE images showed two thrombotic inferior petrosal sinuses. CONCLUSION: Enhanced MR images were superior to nonenhanced images in assessing retrograde venous drainage in intracranial dAVFs. Enhanced 3D MP-RAGE is superior to enhanced T1-weighted SE imaging for determining the route and severity of venous reflux because of its increased spatial resolution and ability to contiguously delineate the venous system.     

Nondysplastic nodules that are hyperintense on T1-weighted gradient-echo MR imaging: frequency in cirrhotic patients undergoing transplantation

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

Detection of hepatic metastases by superparamagnetic iron oxide-enhanced MR imaging: prospective comparison between 1.5-T and 3.0-T images in the same patients

Objective:

To prospectively compare the diagnostic performance of superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) imaging at 3.0 T and 1.5 T for detection of hepatic metastases.

Methods:

A total of 28 patients (18 men, 10 women; mean age, 61 years) with 80 hepatic metastases were prospectively examined by SPIO-enhanced MR imaging at 3.0 T and 1.5 T. T1-weighted gradient-recalled-echo (GRE) images, T2*-weighted GRE images and T2-weighted fast spin-echo (SE) images were acquired. The tumour-to-liver contrast-to-noise ratio (CNR) of the lesions was calculated. Three observers independently reviewed each image. Image artefacts and overall image quality were analysed, sensitivity and positive predictive value for the detection of hepatic metastases were calculated, and diagnostic accuracy using the receiver-operating characteristics (ROC) method was evaluated.

Results:

The tumour-to-liver CNRs were significantly higher at 3.0 T. Chemical shift and motion artefact were more severe, and overall image quality was worse on T2-weighted fast SE images at 3.0 T. Overall image quality of the two systems was similar on T1-weighted GRE images and T2*-weighted GRE images. Sensitivity and area under the ROC curve for the 3.0-T image sets were significantly higher.

Conclusion:

SPIO-enhanced MR imaging at 3.0 T provided better diagnostic performance for detection of hepatic metastases than 1.5 T.     

Hepatocellular carcinoma: detection with gadolinium- and ferumoxides-enhanced MR imaging of the liver.

PURPOSE: To test the hypothesis that the accuracy of gadolinium- and ferumoxides-enhanced magnetic resonance (MR) imaging is different in small (< or =1.5-cm) and large (>1.5-cm) hepatocellular carcinomas (HCCs). MATERIALS AND METHODS: Forty-three consecutive patients with chronic liver disease were enrolled in this study. The imaging protocol included unenhanced breath-hold T1-weighted fast field-echo sequences, unenhanced respiratory-triggered T2-weighted turbo spin-echo (SE) sequences, dynamic gadolinium-enhanced T1-weighted three-dimensional turbo field-echo sequences, and ferumoxides-enhanced T2-weighted turbo SE sequences. Images of each sequence and two sets of sequences (ferumoxides set and gadolinium set) were reviewed by four observers. The ferumoxides set included unenhanced T1- and T2-weighted images and ferumoxides-enhanced T2-weighted turbo SE MR images. The gadolinium set included unenhanced T1- and T2-weighted images and dynamic gadolinium-enhanced three-dimensional turbo field-echo MR images. In receiver operating characteristic (ROC) curve analysis, the sensitivity and accuracy of the sequences were compared in regard to the detection of all, small, and large HCCs. RESULTS: Imaging performance was different with gadolinium- and ferumoxides-enhanced images in the detection of small and large HCCs. For detection of small HCCs, the sensitivity and accuracy with unenhanced and gadolinium-enhanced imaging (gadolinium set) were significantly (P =.017) superior to those with unenhanced and ferumoxides-enhanced imaging (ferumoxides set). The area under the composite ROC curves, or A(z), for the gadolinium set and the ferumoxides set was 0.97 and 0.81, respectively. For large HCC, the ferumoxides set was superior compared with the gadolinium set, but this difference was not statistically significant. Analysis of all HCCs demonstrated no significant differences for gadolinium- and ferumoxides-enhanced imaging. CONCLUSION: For the detection of early HCC, gadolinium-enhanced MR imaging is preferred to ferumoxides-enhanced MR imaging because the former demonstrated significantly greater accuracy in the detection of small HCCs.     

Detection of Small Hypervascular Hepatocellular Carcinomas in Cirrhotic Patients: Comparison of Superparamagnetic Iron Oxide-Enhanced MR Imaging with Dual-Phase Spiral CT

Objective

To compare the performance of superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) imaging at 1.5T and dual-phase spiral computed tomography (CT) for the depiction of small hypervascular hepatocellular carcinomas (HCCs).

Materials and Methods

Forty-three patients with 70 small nodular HCCs (5-20 mm; mean, 13.7 mm) were examined. Diagnosis was based on the results of surgical biopsy in 22 patients and by the combined assessment of MR imaging, lipiodol CT, alpha feto-protein levels, and angiographic findings in 21. MR imaging consisted of respiratory-triggered turbo spin-echo T2-weighted imaging, T1-weighted fast low-angle shot, and T2*-weighted fast imaging with steady-state precession imaging before and after SPIO enhancement. CT imaging was performed with 5-mm collimation and 1:1.4 pitch, and began 30 and 65 secs after the injection of 150 mL of contrast medium at a rate of 3 mL/sec. Two blinded observers reviewed all images independently on a segment-by-segment basis. Diagnostic accuracy was evaluated using receiver operating characteristics (ROC) analysis.

Results

The mean areas (Az) under the ROC curves were 0.85 for SPIO-enhanced MR imaging and 0.79 for dual-phase spiral CT (p < .05). The mean sensitivity of SPIO-enhanced MR imaging was significantly higher than that of CT (p < .05), i.e. 70.6% for MR imaging and 58.1% for CT. MR imaging had higher false-positive rates than dual-phase spiral CT, but the difference was not statistically significant (3.7% vs 3.3%) (p > .05).

Conclusion

SPIO-enhanced MR imaging is more sensitive than dual-phase spiral CT for the depiction of small hypervascular hepatocellular carcinomas.     

Liver metastases in candidates for hepatic resection: comparison of helical CT and gadolinium- and SPIO-enhanced MR imaging

PURPOSE: To prospectively compare accuracy of dynamic contrast material-enhanced thin-section multi-detector row helical computed tomography (CT), high-spatial-resolution three-dimensional (3D) dynamic gadolinium-enhanced magnetic resonance (MR) imaging, and superparamagnetic iron oxide (SPIO)-enhanced MR imaging with optimized gradient-echo (GRE) sequence for depiction of hepatic lesions; surgery and histologic analysis were the reference standard. MATERIALS AND METHODS: Local ethics committee approval was granted, and written informed consent was obtained. Fifty-eight patients (45 men, 13 women; age range, 47-82 years) with hepatic metastases were imaged with multi-detector row CT (3.2-mm section thickness), 3D dynamic gadolinium-enhanced MR imaging (2.5-mm effective section thickness), and SPIO-enhanced MR by using an optimized T2-weighted GRE sequence. Images were reviewed independently by two blinded observers who identified and localized lesions with a four-point confidence scale. Accuracy of each technique was measured with alternative free-response receiver operating characteristic analysis. Results were correlated with findings at surgery with intraoperative ultrasonography or histopathologic examination. Statistical differences among techniques for each observer were measured. RESULTS: Accuracy values for each observer for all metastases (n = 215) and 1.0-cm or smaller metastases (n = 80), respectively, follow: For CT, those for reader 1 were 0.82 and 0.65; for reader 2, 0.81 and 0.68. For gadolinium-enhanced MR imaging, those for reader 1 were 0.92 and 0.79; for reader 2, 0.90 and 0.76. For SPIO-enhanced MR imaging, those for reader 1 were 0.92 and 0.83; for reader 2, 0.92 and 0.81. For all metastases for both observers, there was no significant difference between MR techniques, but both were significantly more accurate than CT (P < .01). For metastases 1.0 cm or smaller and one observer, there was no significant difference between MR techniques, but both were more accurate than CT (P < .01); for the other observer, SPIO-enhanced MR imaging was more accurate than gadolinium-enhanced MR imaging (P < .05) and CT (P < .02), but there was no significant difference between gadolinium-enhanced MR imaging and CT (P = .2). CONCLUSION: Accuracy for gadolinium-enhanced MR imaging and SPIO-enhanced MR imaging was similar. Both techniques were significantly more accurate than CT.     

Imaging of osteoid osteoma with dynamic gadolinium-enhanced MR imaging

PURPOSE: To compare dynamic gadolinium-enhanced T1-weighted magnetic resonance (MR) imaging with nonenhanced T1-weighted and T2-weighted MR imaging and thin-section computed tomography (CT) for the demonstration of osteoid osteomas. MATERIALS AND METHODS: The images of 11 patients with pathologically proven osteoid osteomas who underwent nonenhanced MR imaging, dynamic gadolinium-enhanced MR imaging, and CT were retrospectively reviewed. Images obtained with all three techniques were scored for conspicuity of the osteoid osteoma relative to the surrounding bone. Time-enhancement curves were generated from signal intensity measurements of these lesions and the adjacent bone marrow. The mean imaging scores of the four techniques were compared, and the statistical significance was calculated by using a linear model with terms for method and patient. Pairwise comparisons were made by using the Tukey-Kramer adjustment for multiple comparisons. RESULTS: Compared with CT, dynamic gadolinium-enhanced MR imaging demonstrated the osteoid osteoma equally well in eight of 11 patients and with better conspicuity in three of 11 patients, although this difference was not statistically significant (P =.69). The dynamic gadolinium-enhanced MR images demonstrated the osteoid osteomas significantly better than the nonenhanced T1-weighted (P <.001) and T2-weighted (P <.001) MR images. On the dynamic gadolinium-enhanced MR images, nine (82%) of 11 patients had peak enhancement of the osteoid osteoma in the arterial phase with early partial washout, compared with slower, progressive enhancement of the adjacent marrow. This resulted in greatest lesion to marrow contrast material enhancement in the arterial phase. One osteoid osteoma had peak enhancement in the venous phase, and one showed progressive enhancement through all phases to 150 seconds. CONCLUSION: Osteoid osteomas can be imaged with greater conspicuity by using dynamic gadolinium-enhanced instead of nonenhanced MR imaging and with conspicuity equal to or better than that obtained with thin-section CT.     

Hepatic and hepatocarcinoma magnetic resonance: comparison of the results obtained with paramagnetic (gadolinium) and superparamagnetic (iron oxide particles) contrast media

PURPOSE: To compare prospectively dynamic gadolinium (Gd)-enhanced with superparamagnetic iron oxide (SPIO)-enhanced MRI for the detection of hepatocellular carcinoma (HCC). MATERIAL AND METHODS: Twenty-five patients with histologically proven HCC and liver cirrhosis (28% of them in B or C Child class) underwent dynamic Gd-enhanced MRI and, a few days later, (mean interval: three days) SPIO-enhanced MRI. Only patients with availability of clinical and imaging follow-up for at least seven months were enrolled in this prospective study. Axial dynamic Gd-enhanced imaging was performed with T1 gradient-recalled echo (GRE) sequences. Both axial and sagittal SPIO-enhanced imaging were performed with respiratory triggered T2-weighted turbo spin-echo (TSE) and T1-T2*-weighted GRE sequences. MR images were reviewed by two independent radiologists. The readers scored each lesion for the presence of HCC and assigned confidence levels based on a five-grade scale: 1, definitely or almost definitely absent; 2, possibly present; 3, probably present; 4, definitely present; 5, definitely present with optimal liver/lesion contrast or good liver/lesion contrast and morphological signs (intact capsule, intranodular septa, extra-capsular infiltration), useful for locoregional treatment planning. A positive diagnostic value was assessed for scores of 3 or higher. RESULTS: Gd-enhanced and SPIO-enhanced MRI found 44 lesions. The combined use of TSE and GRE SPIO-enhanced sequences detected 11 more lesions (25% improvement in sensitivity) than Gd-enhanced MRI. One lesion (2.27%) was detected only with Gd-enhanced MRI. Eight of twelve lesions visible with a single contrast agent measured less than 1 cm in diameter. HCC detectability was 75% with Gd-enhanced MRI and 97.7% with SPIO-enhanced MRI. SPIO-enhanced T2-weighted TSE images showed significantly higher diagnostic value than SPIO-enhanced T1-T2*GRE images only in three cases, while nodule morphological characteristics (capsule, septa, different cell differentiation components) were better depicted by TSE images. DISCUSSION AND CONCLUSIONS: In our study the combined use of SPIO-enhanced T2-weighted TSE and T1-T2*-weighted GRE sequences showed higher sensitivity than gadolinium-enhanced GRE dynamic imaging (97.7% versus 75%). These results are at least partly related to our study conditions, that is: 1) MRI was performed with a 1T system, 2) both axial and sagittal SPIO-enhanced imaging were performed with respiratory triggered T2-weighted TSE and T1-T2*-weighted GRE, 3) there was a low freaquency of severe cirrhosis.