Small colorectal liver metastases: Detection with SPIO-enhanced MRI in comparison with gadobenate dimeglumine-enhanced MRI and CT imaging

The aim of this prospective study was to compare the diagnostic role of superparamagnetic iron oxide (SPIO)-enhanced liver magnetic resonance imaging (MRI) versus gadobenate dimeglumine (GbD)-enhanced MRI and computed tomography (CT) investigations for detection of small (less than 1 cm) colorectal liver metastases (LMs) of colorectal cancer. Seventy-eight LMs in 16 patients were evaluated with dynamic CT imaging, GbD-enhanced dynamic MR imaging and SPIO-enhanced MR imaging. Two radiologists were reviewed the LMs seperately. Agreement between the readers and three algorithms was analyzed. Differences between the lesion detection ratios of the methods were analyzed by two proportion z test. Sensitivity values of each modality were also calculated. Interobserver agreement values with kappa analysis were found to be the best for three modalities and kappa values were 0.866, 0.843, and 1.0 respectively. For all 78 LMs, SPIO-enhanced MRI detected all lesions (100% sensitivity). This sensitivity value was higher than GbD-enhanced MRI, and there was a significant difference (p < 0.05). GbD-enhanced MRI depicted 71 lesions and this modality could not detected 7 lesions (91% sensitivity). This modality had moderate sensitivity, and this value is greater than CT imaging, so there was a significant difference also (p < 0.05). Dynamic triphasic CT imaging detected 64 (R1) and 65 (R2) LMs. This modality had the lowest sensitivity (R1: 0.82, R2: 0.83 respectively). Only SPIO-enhanced MRI was able to detect all LMs less than 1 cm. LMs were the best detected with SPIO-enhanced MRI. We recommend SPIO-enhanced MRI to be the primary alternative modality especially for diagnosis of small colorectal LMs.     

Multidetector helical CT plus superparamagnetic iron oxide-enhanced MR imaging for focal hepatic lesions in cirrhotic liver: a comparison with multi-phase CT during hepatic arteriography

The aim of this study was to evaluate multidetector helical computed tomography (MDCT), superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) imaging, and CT arterial portography (CTAP) and CT during hepatic arteriography (CTHA) for the detection and diagnosis of hepatocellular carcinomas (HCC). This included visual correlations of MDCT and SPIO-MR imaging in the detection of HCC using receiver operating characteristic (ROC) analysis. Twenty-five patients with 57 nodular HCCs were retrospectively analyzed. A total of 200 segments, including 49 segments with 57 HCCs, were reviewed independently by three observers. Each observer read four sets of images (set 1, MDCT; set 2, unenhanced and SPIO-enhanced MR images; set 3, combined MDCT and SPIO-enhanced MR images; set 4, combined CTAP and CTHA). The mean Az values representing the diagnostic accuracy for HCCs of sets 1, 2, 3, and 4 were 0.777, 0.814, 0.849, and 0.911, respectively, and there was no significant difference between sets 3 and 4. The sensitivity of set 4 was significantly higher than those of set 3 for all the lesions and for lesions 10 mm or smaller (p<0.05); however, for lesions larger than 10mm, the sensitivities of the two sets were similar. No significant difference in positive predictive value and specificity was observed between set 3 and set 4. Combined MDCT and SPIO-enhanced MR imaging may obviate the need for more invasive CTAP and CTHA for the pre-therapeutic evaluation of patients with HCC more than 10mm.     

Detection of focal hepatic lesions: comparison of unenhanced and SHU 555 A-enhanced MR imaging versus biphasic helical CTAP

The purpose of this study was to compare the diagnostic sensitivity of unenhanced magnetic resonance (MR) imaging, and MR imaging with a new superparamagnetic iron oxide (SPIO)-enhanced contrast agent (SHU 555 A) with biphasic helical computed tomography during arterial portography (CTAP) in patients with focal liver lesions. Eighteen patients with a total of 91 (78 malignant, 13 benign) proven liver lesions underwent unenhanced short tau inversion recovery (STIR), T2-weighted (T2-w) TSE, and SHU 555 A-enhanced T2-w turbo spin-echo (TSE) MR imaging and biphasic helical CTAP. The standard of reference was histopathologic analysis of resected specimens in 59 lesions, intraoperative ultrasound with biopsy in 20 lesions, and CT-guided biopsy and follow-up in 12 lesions. Diagnostic performance of the imaging modalities was compared quantitatively and qualitatively by assessing lesion involvement in liver segments. There were 68 lesions detected on unenhanced T2-w TSE, which resulted in a sensitivity of 75%. With the STIR sequence, 76 lesions were detected, for a sensitivity of 84%, and with SHU 555 A-enhanced MRI, 84 lesions were detected, for a sensitivity of 92%. CTAP detected 88 lesions, for a sensitivity of 97%. The accuracy for unenhanced T2-w TSE was 98%, for STIR 99%, for enhanced-MRI 100%, and for CTAP 95%. The specificity was 100% for SHU 555 A-enhanced MRI and 95% for CTAP. SHU 555 A-enhanced MRI was superior to nonenhanced MRI (P < 0.05) and equivalent to CTAP in terms of sensitivity. Due to the absence of false-positive results on SHU 555 A-enhanced MRI, the specificity and accuracy of enhanced MRI were higher than those of CTAP, but the difference was not statistically significant (P = 0.134).     

The influence of MR field strength on the detection of focal liver lesions with superparamagnetic iron oxide

The purpose of this study was to compare the value of low- vs high-field MR systems in the detection of focal liver lesions after IV administration of iron oxide particles. A prospective study was undertaken which included 20 patients with focal liver lesions on CT or US, or strong clinical suspicion of focal liver disease. Iron oxide particles were administered in an IV drip infusion over 30 min. Magnetic resonance imaging was subsequently performed on a 0.2 and a 1.5-T system. Both examinations were performed in one session. Turbo spin-echo T2-weighted sequences were used for further analysis (at 0.2 T: TR 4050 ms, TE 96 ms; 1.5 T: TR 3000 ms, TE 103 ms). After randomisation, images were analysed by two blinded readers. The evaluation included lesion counts, determination of lesion conspicuity and overall image quality (both graded on a scale 1–5). Quantitative analysis was performed on 29 lesions. Lesion-to-liver signal intensity and contrast-to-noise ratios (CNRs) were calculated. The total lesion count (cumulative counts for two observers) was 59 on the high-field system and 63 on the low-field system. Statistical analysis showed no significant difference. On both systems median value for lesion conspicuity was 3. No statistically significant difference was found. Global image quality was rated higher on the high-field system: 3 vs 2 for the low-field system (p = 0.0017). Quantitative analysis showed no significant difference for lesion-to-liver signal intensity ratios or CNRs. Although subjective image quality is significantly better on the high-field system, this does not result in better lesion detection or better lesion conspicuity. No significant difference in objective quantitative parameters was found in our series. Received 25 June 1996; Revision received 28 October 1996; Accepted 25 November 1996     

大鼠肝硬化肝癌SPIO增强MRI表现与Kupffer细胞的关系

目的：建立二乙基亚硝胺（DENA）诱导的大鼠肝硬化肝细胞癌（HCC）模型,探讨超顺磁性氧化铁（SPIO）增强MRI上肝硬化肝癌信号改变与肝Kupffer细胞（KCs）之间的关系。方法：22只大鼠肝硬化肝癌模型,其中6只为单纯性肝硬化,16只为肝硬化肝癌,对照组为10只清洁级Wistar雄性大白鼠,均行SPIO增强前后T1WI和T2WI扫描,并行病理检查（HE染色及普鲁士蓝染色）,分析肝脏Kupffer细胞数量与SPIO增强后信号之间的关系。结果：普鲁士兰染色切片上肝硬化组织内蓝染Kupffer细胞数量略减少,蓝色颗粒不均匀;高分化肝癌中Kupffer细胞减少,低分化肝癌Kupffer细胞显著减少甚至消失。肝癌与正常肝实质、硬化肝组织相比,Kupffer细胞数量减少,差异有显著性意义（P〈0．001）;正常肝实质与肝硬化组织内Kupffer细胞数量的差异无显著性意义（P＝0．088）。SPIO增强T2WI上,正常肝实质、肝硬化组织信号强度（SI）较增强前明显下降,信号强度下降百分比（PSIL）分别为42％和38％,两组间差异无统计学意义（P＝0．409）;肝癌信号强度较增强前无明显下降,PSIL为12％,明显低于正常肝实质和肝硬化组织（P〈0．001）;SPIO增强后肝癌对比噪声比（CNR）较增强前显著提高（P＝0．002）。SPIO增强T1WI上。正常肝实质及硬化肝组织PSIL分别为15％和6％,而肝癌的信号强度较增强前升高9％,部分小病灶呈不均匀轻度强化,肝癌CNR较增强前明显降低（P〈0．001）。SPIO增强T2WI上,肝组织PSIL与Kupffer细胞数量呈曲线趋势,随着组织内Kupffer细胞数量的增多病灶信号强度下降程度越明显,曲线估计3次模型决定系数R^2为0．920,有显著性意义（P〈0．001）。结论：SPIO增强T2WI上肝脏信号强度改变与Kupffer细胞数量及其吞噬功能有相关性,随着Kupffer细胞增多PSIL呈升高趋势。SPIO增强MRI不?     

Improved focal liver lesion detection: comparison of single-shot spin-echo echo-planar and superparamagnetic iron oxide (SPIO)-enhanced MRI

PURPOSE: To prospectively compare single-shot spin-echo echo-planar imaging (SSSE-EPI) using b = 0, 10, 150, and 400 seconds/mm(2) with standard MRI techniques after intravenous super paramagnetic iron oxide (SPIO) in the detection and characterization of focal liver lesions with focus on small (<10 mm) focal liver lesions. MATERIALS AND METHODS: A total of 25 patients suspected for colorectal liver metastases were included. Number of detected lesions was evaluated. Image quality was compared between SSSE-EPI sequence and post-SPIO (fat-suppressed T1-weighted [T1w] gradient echo [GE], T2-weighted [T2w] turbo spin echo [TSE] and T2* GE) sequences using rank order statistic (RIDIT). Lesion characterization was performed for SSSE-EPI and for all remaining sequences pre- and post-SPIO. Reference standard comprised surgery, biopsy, and/or follow-up. RESULTS: Reference standard demonstrated 25 hemangiomas and 70 metastases. Best lesion detection respectively best image quality (P < 0.05) was achieved with SSSE-EPI (b = 10 seconds/mm(2)) post-SPIO T1w GE and T2w turbo spin echo. Lesion characterization using all sequences pre- and post-SPIO performed best for lesion characterization compared with SSSE-EPI. CONCLUSION: This preliminary study shows the potential of SSSE-EPI as a stand-alone sequence for the detection of liver hemangiomas and metastases when compared with SPIO-enhanced imaging. Sequences pre- and post-SPIO are needed for qualitative lesion characterization.     

Usefulness of free-breathing readout-segmented echo-planar imaging (RESOLVE) for detection of malignant liver tumors: Comparison with single-shot echo-planar imaging (SS-EPI)

Purpose

We aimed to clarify the usefulness of free-breathing readout-segmented echo-planar imaging (RESOLVE), which is multi-shot echo-planar imaging based on a 2D-navigator-based reacquisition technique, for detecting malignant liver tumor.

Materials and methods

In 77 patients with malignant liver tumors, free-breathing RESOLVE and respiratory-triggered single-shot echo-planar imaging (SS-EPI) at 3-T MR unit were performed. We set a scan time up to approximately 5 min (300 s) before examination, measured actual scan time and assessed (1) susceptibility and (2) motion artifacts in the right and left liver lobes (3, no artifact; 1, marked), and (3) detectability of malignant liver tumors (3, good; 1, poor) using a 3-point scale.

Results

The median actual scan time of RESOLVE/SS-EPI was 365/423 s. The median scores of each factor in RESOLVE/SS-EPI were as following in this order: (1) 3/2 (right lobe); 3/3 (left lobe), (2) 2/3 (right lobe); 1/2 (left lobe), and (3) 3/3, respectively. Significant differences were noted between RESOLVE and SS-EPI in all evaluated factors (P < 0.05) except for susceptibility of left lobe and detectability of the lesions.

Conclusion

Despite the effect of motion artifacts, RESOLVE provides a comparable detectability of the lesion and the advantage of reducing scanning time compared with SS-EPI.     

Superparamagnetic iron oxide (SPIO)-enhanced liver MRI with ferucarbotran: efficacy for characterization of focal liver lesions

PURPOSE: To evaluate the efficacy of ferucarbotran in T2-weighted (T2W) fast spin-echo (FSE) and T2*W gradient-echo (GRE) sequences for characterizing focal liver lesions. MATERIALS AND METHODS: In 68 patients, 46 malignant and 22 benign focal liver lesions were evaluated. Precontrast (NCE) T2W FSE images and contrast-enhanced (CE) T2W FSE and T2*W GRE images were obtained on a 1.5T MR system. Based on signal intensity (SI) measurements in focal lesions and liver parenchyma, the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated for all sequences. The percentage of SI loss (PSIL) in focal lesions after contrast agent (CA) application was calculated for the T2W FSE sequence. Qualitative analyses were performed to assess image quality and lesion conspicuity obtained with the CE-T2W FSE and CE-T2*W GRE sequences. RESULTS: The mean PSIL was higher in solid benign lesions than in malignant lesions (39.6% vs. 3.2%, P<0.05). With a threshold PSIL of 25%, the sensitivity and specificity for characterizing malignant lesions were 97.8% and 92.9%, respectively. The mean CNR of the malignant lesions was higher in the CE-T2*W sequence than in the CE- and NCE-T2W FSE sequences (29.9 vs. 22.7 (P<0.01) vs. 12.8 (P<0.01)). CE-T2*W images showed a superior image quality and lesion conspicuity (P<0.05) compared to the CE-T2W FSE sequence. CONCLUSION: The PSIL can be an accurate tool for characterizing benign and malignant lesions. The addition of a CE-T2*W GRE sequence is helpful for the detection and characterization of malignant lesions.     

Quantitative and qualitative comparison of 3.0T and 1.5T MR imaging of the liver in patients with diffuse parenchymal liver disease

Purpose

The purpose of our study was to compare signal characteristics and image qualities of MR imaging at 3.0 T and 1.5 T in patients with diffuse parenchymal liver disease.

Materials and methods

25 consecutive patients with diffuse parenchymal liver disease underwent abdominal MR imaging at both 3.0 T and 1.5 T within a 6-month interval. A retrospective study was conducted to obtain quantitative and qualitative data from both 3.0 T and 1.5 T MRI. Quantitative image analysis was performed by measuring the signal-to-noise ratios (SNRs) and the contrast-to-noise ratios (CNRs) by the Students t-test. Qualitative image analysis was assessed by grading each sequence on a 3- and 4-point scale, regarding the presence of artifacts and image quality, respectively. Statistical analysis consisted of the Wilcoxon signed-rank test.

Results

the mean SNRs and CNRs of the liver parenchyma and the portal vein were significantly higher at 3.0 T than at 1.5 T on portal and equilibrium phases of volumetric interpolated breath-hold examination (VIBE) images (P < 0.05). The mean SNRs were significantly higher at 3.0 T than at 1.5 T on T1-weighted spoiled gradient echo (SGE) images (P < 0.05). However, there were no significantly differences on T2-weighted short-inversion-time inversion recovery (STIR) images. Overall image qualities of the 1.5 T non-contrast T1- and T2-weighted sequences were significantly better than 3.0 T (P < 0.01). In contrast, overall image quality of the 3.0 T post-gadolinium VIBE sequence was significantly better than 1.5 T (P < 0.01).

Conclusions

MR imaging of post-gadolinium VIBE sequence at 3.0 T has quantitative and qualitative advantages of evaluating for diffuse parenchymal liver disease.     

Evaluation of Porcine Pancreatic Islets Transplanted in the Kidney Capsules of Diabetic Mice Using a Clinically Approved Superparamagnetic Iron Oxide (SPIO) and a 1.5T MR Scanner

Objective

To evaluate transplanted porcine pancreatic islets in the kidney capsules of diabetic mice using a clinically approved superparamagnetic iron oxide (SPIO) and a 1.5T MR scanner.

Materials and Methods

Various numbers of porcine pancreatic islets labeled with Resovist, a carboxydextran-coated SPIO, were transplanted into the kidney capsules of normal mice and imaged with a 3D FIESTA sequence using a 1.5T clinical MR scanner. Labeled (n = 3) and unlabeled (n = 2) islets were transplanted into the kidney capsules of streptozotocin-induced diabetic mice. Blood glucose levels and MR signal intensities were monitored for 30 days post-transplantation.

Results

There were no significant differences in viability or insulin secretion between labeled and unlabeled islets. A strong correlation (r² > 0.94) was evident between the number of transplanted islets and T₂ relaxation times quantified by MRI. Transplantation with labeled or unlabeled islets helped restore normal sustained glucose levels in diabetic mice, and nephrectomies induced the recurrence of diabetes. The MR signal intensity of labeled pancreatic islets decreased by 80% over 30 days.

Conclusion

The transplantation of SPIO-labeled porcine islets into the kidney capsule of diabetic mice allows to restore normal glucose levels, and these islets can be visualized and quantified using a 1.5T clinical MR scanner.     

Echo planar MR imaging of the liver: comparison of images with and without motion probing gradients

PURPOSE: To determine whether MR images with motion-probing gradients (MPGs) usefully improve lesion detection in comparison with MR images without MPGs. MATERIALS AND METHODS: Echo planar (EP) images without MPGs and with small and intermediate MPGs (gradient factor b = 2, 18, and 188 second/mm(2), respectively) were acquired for 61 hepatic lesions (21 hepatocellular carcinomas (HCCs), 19 metastases, eight hemangiomas, and 13 cysts). The lesion-to-liver signal intensity ratios (SIRs) of these lesions were calculated using EP images with and without MPGs. Qualitative analysis for detection of HCCs and metastases were also performed between the images without MPGs and with small MPGs. RESULTS: The SIRs of HCCs and metastases for the images with small MPGs were significantly higher than the values for the images without MPGs (P < 0.05), although no significant differences were found in the case of hemangiomas and cysts. In comparison to images without MPGs, images with small MPGs improved lesion detection of three metastases and six HCCs, and worsened lesion detection of two HCCs. CONCLUSION: Images with small MPGs may improve HCC and metastasis detection over images without MPGs.     

Preoperative detection of malignant hepatic tumors: comparison of combined methods of MR imaging with combined methods of CT

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.     

T2-weighted MR imaging of the liver: Qualitative and quantitative comparison of SPACE MR imaging with turbo spin-echo MR imaging

Objective

To qualitatively and quantitatively compare T2-weighted MR imaging of the liver using volumetric spin-echo with sampling perfection with application-optimized contrast using different flip angle evolutions (SPACE) with conventional turbo spin-echo (TSE) sequence for fat-suppressed T2-weighted MR imaging of the liver.

Materials and methods

Thirty-three patients with suspected focal liver lesions had SPACE MR imaging and conventional fat-suppressed TSE MR imaging. Images were analyzed quantitatively by measuring the lesion-to-liver contrast-to-noise ratio (CNR), and the signal-to-noise ratio (SNR) of main focal hepatic lesions, hepatic and splenic parenchyma and qualitatively by evaluating the presence of vascular, respiratory motion and cardiac artifacts. Wilcoxon signed rank test was used to search for differences between the two sequences.

Results

SPACE MR imaging showed significantly greater CNR for focal liver lesions (median = 22.82) than TSE MR imaging (median = 14.15) (P < .001). No differences were found for SNR of hepatic parenchyma (P = .097), main focal hepatic lesions (P = .35), and splenic parenchyma (P = .25). SPACE sequence showed less artifacts than TSE sequence (vascular, P < .001; respiratory motion, P < .001; cardiac, P < .001) but needed a longer acquisition time (228.4 vs. 162.1 s; P < .001).

Conclusion

SPACE MR imaging provides a significantly increased CNR for focal liver lesions and less artifacts by comparison with the conventional TSE sequence. These results should stimulate further clinical studies with a surgical standard of reference to compare the two techniques in terms of sensitivity for malignant lesions.     

Detection of hepatocellular carcinoma (HCC) using super paramagnetic iron oxide (SPIO)‐enhanced MRI: Added value of diffusion‐weighted imaging (DWI)

Purpose:

To evaluate whether diffusion‐weighted imaging (DWI) improves the detection of hepatocellular carcinoma (HCC) on super paramagnetic iron oxide (SPIO)‐enhanced MRI.

Materials and Methods:

This retrospective study group consisted of 30 patients with 50 HCC nodules who underwent MRI at 1.5 Tesla. Two combined MR sequence sets were compared for detecting HCC: SPIO‐enhanced MRI (axial T2‐weighted fast spin‐echo (FSE) and T1‐/T2*‐weighted fast field echo (FFE) scanned before and after administration of ferucarbotran) and SPIO‐enhanced MRI + DWI (SPIO‐enhanced MRI with axial DWI scanned before and after administration of ferucarbotran). Three blinded readers independently reviewed for the presence of HCC on a segment‐by‐segment basis using a four‐point confidence scale. The performance of the two combined MR sequence sets was evaluated using receiver operating characteristic (ROC) analysis.

Results:

The average area under the ROC curve (Az) of the three readers for the SPIO‐enhanced MRI + DWI set (0.870 ± 0.046) was significantly higher that that for the SPIO‐enhanced MRI set (0.820 ± 0.055) (P = .025). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for detection of HCC were 66.0%, 98.0%, 90.0%, and 91.4%, respectively, for the SPIO‐enhanced MRI set, and 70.0%, 98.6%, 92.9%, and 92.4%, respectively, for the SPIO‐enhanced MRI + DWI set.

Conclusion:

The SPIO‐enhanced MRI + DWI set outperformed the SPIO‐enhanced MRI set for depicting HCC. J. Magn. Reson. Imaging 2010; 31: 373–382. © 2010 Wiley‐Liss, Inc.     

Dynamic liver imaging with iron oxide agents: Effects of size and biodistribution on contrast

In vivo effective relaxation rates in normal rat liver were evaluated for four dextran coated iron oxide agents: monocrystal-line iron oxide nanocolloid (MION) with a mean particle diameter of 3.9 nm, a polycrystalline agent (PION) with a larger mean diameter of 12 nm, and these two agents labeled with the asialofetuin (ASF) protein for high hepatocytic receptor binding affinity (MION-ASF and PION-ASF). Using echo planar imaging at 2 Tesla, dose response was measured with high temporal resolution for 3 h after injection of agent, and by comparing with relaxivities in vitro and in brain, dominant in vivo contrast phenomena were elucidated. While transverse relaxivity for PION-ASF exceeded that for MION-ASF by almost a factor of 2 in solution, relaxation rates in vivo became equivalent. Liver relaxation using non-ASF agents was consistent with rapid water exchange between vascular and extravascular compartments, which dominated relaxation as a result of agent accumulation in Kupffer cells.     

Prospective comparison of high- and low-spatial-resolution dynamic MR imaging with sensitivity encoding (SENSE) for hypervascular hepatocellular carcinoma

The purpose of this study was to prospectively evaluate the efficacy of high-spatial-resolution dynamic MRI using sensitivity encoding (SENSE) in detection of hypervascular hepatocellular carcinoma (HCC). Thirty-five patients were included in this prospectively planned study, and 25 patients with 31 HCCs were assigned into three groups and underwent the following sequences: group A (n = 11): three-dimensional fast-gradient-echo (3D-FGE) high-spatial-resolution dynamic MRI (HR-MRI) with SENSE; group B (n = 10): 3D-FGE low-spatial-resolution dynamic MRI (LR-MRI) with SENSE; and group C (n = 14): 3D-FGE/LR-MRI without SENSE. For the quantitative analysis, the lesion-to-liver contrast-to-noise ratio (CNR) between the liver and HCCs was measured. For the qualitative analysis, overall image quality for each group was evaluated with a five-point scale analysis. The sensitivities for detection of HCCs were evaluated. The overall image quality in group A was significantly greater than both groups B and C (P < 0.01). The sensitivity of lesion detection on HAP was not significantly higher in group A (100%) than group C (69.2%; P > 0.05). In our pilot study on a small number of patients, image quality in HR-MRI with SENSE was superior to LR-MRI. A high detection rate was seen with HR-MRI with SENSE in the patients with hypervascular HCCs.     

Differentiation between cavernous hemangiomas and untreated malignant neoplasms of the liver with free-breathing diffusion-weighted MR imaging: Comparison with T2-weighted fast spin-echo MR imaging

Objective

To test interobserver variability of ADC measurements and compare the diagnostic performances of free-breathing diffusion-weighted (FBDW) with that of T2-weighted FSE (T2WFSE) MR imaging for differentiating between cavernous hemangiomas and untreated malignant hepatic neoplasms.

Materials and methods

Thirty-five patients with cavernous hemangiomas and 35 with untreated hepatic malignant neoplasms had FBDW and T2WFSE MR imaging. Hepatic lesions were characterized with ADC measurement and visual evaluation. Interobserver agreement for ADC measurement was calculated. Association between ADC value and lesion type was assessed using univariate analysis. Sensitivity, specificity and accuracy of ADC values and visual evaluation of MR images for the diagnosis of untreated malignant hepatic neoplasm were compared.

Results

ADC measurements showed excellent interobserver correlation (intraclass correlation coefficient = 0.980). Malignant neoplasms had lower ADC values than hemangiomas for the two observers (1.11 × 10⁻³ mm²/s ± .21 × 10⁻³vs. 1.77 × 10⁻³ mm²/s ± .29 × 10⁻³ for observer 1 and 1.11 × 10⁻³ mm²/s ± .19 × 10⁻³vs. 1.79 × 10⁻³ mm²/s ± .32 × 10⁻³ for observer 2) and univariate analysis found significant correlations between lesion type and ADC values. Depending on ADC threshold value, accuracy for the diagnosis of malignant neoplasm varied from 82.9% to 94.3%. Using visual evaluation, FBDW showed better specificity and accuracy than T2WFSE MR images for the diagnosis of malignant neoplasm (97.1% vs. 77.1% and 94.3% vs. 62.9%, respectively).

Conclusion

FBDW imaging provides reproducible quantitative information and surpasses the value of T2WFSE MR imaging for differentiating between cavernous hemangiomas and untreated malignant hepatic neoplasms.     

Benign and malignant hepatocellular tumors: evaluation of tumoral enhancement after mangafodipir trisodium injection on MR imaging

The aim of this work was to study the ability of mangafodipir trisodium (Mn-DPDP)-enhanced MR imaging in differentiating malignant from benign hepatocellular tumors. Eleven patients with pathologically proved hepatocellular carcinomas, six with focal nodular hyperplasias, and one with a single hepatocellular adenoma were examined by spin-echo and gradient-echo T1-weighted sequences before, 1 h after, and 24 h after intravenous injection of Mn-DPDP (5 μmol/kg). Quantitative analysis including enhancement and lesion-to-liver contrast-to-noise ratio, and qualitative analysis including the presence of a central area and a capsule were done on pre- and post-Mn-DPDP-enhanced images. Enhancement was observed in all the tumors with significant improvement (p < 0.05) in contrast-to-noise ratio 1 h after, and 24 h after intravenous injection of Mn-DPDP. There were no significant differences in the mean enhancement and the mean contrast-to-noise ratio (CNR) between benign and malignant tumors. No enhancement was seen within internal areas observed in 7 hepatocellular carcinomas, and in 5 focal nodular hyperplasias, and within capsules which were observed in 9 hepatocellular carcinomas. In our study, Mn-DPDP increased CNR of both benign and malignant tumors but did not enable differentiation between benign and malignant tumors of hepatocellular nature. Received: 7 October 1997; Revision received: 25 February 1998; Accepted: 10 July 1998     

Enhancement characteristics of liver metastases, hepatocellular carcinomas, and hemangiomas with Gd-EOB-DTPA: preliminary results with dynamic MR imaging

Our objective was to study Gd-EOB-DTPA for the characterization of focal liver lesions by means of dynamic MR imaging. A double-blind and randomized dose-ranging phase-2 clinical trial was performed in 31 patients (liver metastases n = 23, hepatocellular carcinoma n = 4, and hemangioma n = 4) at a field strength of 1.0 Tesla. Gd-EOB-DTPA (Schering AG, Berlin, Germany) was administered as an IV bolus (12.5, 25, or 50 μmol/kg body weight) with dynamic T1-weighted MRI during the distribution and cellular uptake of the contrast agent at multiple time points up to 45 min post contrast. Dynamic changes in tumor signal intensity, tumor–liver contrast, enhancement patterns, side effects, and adverse events were evaluated. Monitoring of vital signs revealed no significant changes during bolus injection of Gd-EOB-DTPA. Liver metastases demonstrated an inhomogeneous uptake of Gd-EOB-DTPA during the distribution phase with a washout effect on delayed images > 3 min and highest tumor–liver contrast 20 and 45 min post contrast. Hepatocellular carcinomas showed prolonged enhancement as compared with metastases and hemangiomas. Hemangiomas exhibited an early peripheral–nodular enhancement with subsequent partial or complete filling, persisting enhancement < 10 min following injection of Gd-EOB-DTPA, and delayed washout as compared with liver metastases. Initial clinical experience suggests that Gd-EOB-DTPA as a bolus injectable hepatobiliary MR contrast agent may offer useful features for the characterization of focal liver lesions. Received 4 January 1996; Revision received 13 March 1996; Accepted 4 June 1996