Hepatic lesion detection after superparamagnetic iron oxide enhancement: comparison of five T2-weighted sequences at 1.0 T by using alternative-free response receiver operating characteristic analysis

PURPOSE: To compare the accuracy of five T2-weighted sequences in the detection of liver lesion at magnetic resonance (MR) imaging after superparamagnetic iron oxide (SPIO) enhancement. MATERIALS AND METHODS: Forty-nine candidates for hepatic resection with known coloretal metastases were examined. Before SPIO enhancement, fast spin-echo (SE) images were obtained. After enhancement, the same fast SE sequence and long; TR/short TE, short TE, long TR/TE, and T2-weighted fast low-angle shot (FLASH) sequences were used. All images were viewed independently by four observers who were blinded to the results of the other imaging sequences, the results of the other observers, and the findings at surgery and histopathologic examination. Four weeks after the initial reading, the combined long TR/short TE and long TR/TE dual-echo images were also viewed as an additional set. The alternative free response receiver operating characteristic (ROC) method was used to analyze the results, which were correlated with findings at surgery, intraoperative ultrasonography, and histopathologic examination. RESULTS: Irrespective of lesion size, the accuracy of all sequences after enhancement was significantly greater than that of the nonenhanced fast SE sequence (P < .01). Dual-echo and FLASH sequences were significantly more accurate than the enhanced fast SE sequence (P < .03 or P < .02, respectively). For all lesions, lesions smaller than 1 cm, and lesions 1 cm or larger, mean accuracies were as follows: dual-echo, 0.75, 0.54, and 0.93; FLASH, 0.75, 0.54, and 0.95; and enhanced fast SE, 0.72, 0.49, and 0.92. CONCLUSION: At 1.0 T, dual-echo and FLASH sequences are the most accurate pulse sequences after SPIO enhancement.     

Liver lesions: manganese-enhanced MR and dual-phase helical CT for preoperative detection and characterization comparison with receiver operating characteristic analysis

PURPOSE: The purpose of this study was to compare, by means of receiver operating characteristic (ROC) analysis, dual-phase helical computed tomography (CT) and manganese-enhanced magnetic resonance (MR) imaging in the detection and characterization of hepatic lesions in patients prior to surgery. MATERIALS AND METHODS: Twenty-five patients known to have or suspected of having hepatic lesions who were eligible for surgery underwent dual-phase (ie, arterial and portal phase) helical CT and phased-array MR imaging (ie, unenhanced fast spin-echo T2-weighted imaging and gradient-echo T1-weighted imaging performed before and after administration of mangafodipir trisodium). All images were reviewed independently by three off-site blinded reviewers who separately reviewed the CT scans and MR images. The standard of reference was findings at surgery, intraoperative ultrasonography (US), and histopathologic examination. ROC curves were established to analyze the results for each reader and modality. RESULTS: Ninety-four lesions (77 malignant and 17 benign) were revealed at surgery, intraoperative US, and/or histopathologic examination. The overall rate of lesion detection for the three readers at CT was 81.9% +/- 7.8, 90.4% +/- 5.9, and 76.6% +/- 8.6. At MR imaging, the detection rates were 72.3% +/- 9.0, 71.3% +/- 9.1, and 69.1% +/- 9.3 (P =.001 for the difference between MR and CT). The average rate of false-positive diagnoses in patients was 14.1% at CT and 6.4% at MR imaging (P =.06 for the difference between MR and CT). The mean areas under the alternative-free-response ROC curves were 0.74 for MR and 0.72 for CT (P =.751, not significant). CONCLUSION: In detection and characterization of liver lesions, manganese-enhanced MR imaging and dual-phase helical CT were not statistically different.     

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.     

大鼠种植型肝癌的超顺磁性的氧化铁磁共振增强实验研究

目的 研究正常大鼠的超顺磁性氧化铁（ＳＰＩＯ）剂量梯度－肝脏信号曲线、大鼠种植地癌ＳＰＩＯ增强前后的对比噪声比和检出率。方法 第１组：７２只正常ＳＤ大鼠随机分成１８个样本组,平扫后以０、２、５……２８０ｕｍｏｌＦｅ／ｋｇ１８个ＳＰＩＯ剂量分别做增强扫描,做剂量梯度－肝脏信号曲线。第２组：３８只种植型肝癌模型鼠,共计生成４３个肿瘤,行平扫及ＳＰＩＯ增强扫描,分析肿瘤磁共振强化特点;测量增强前后Ｔ１及     

Pelvic lymph node visualization with MR imaging using local administration of ultra-small superparamagnetic iron oxide contrast

PURPOSE: To determine if interstitial injection of iron oxide particles improves visualization of pelvic lymph nodes at magnetic resonance imaging (MRI) and to determine the effect of injection site on location of visualized nodes. MATERIALS AND METHODS: In nine healthy volunteers, ferumoxtran-10 iron oxide (0.28 mg iron per kg) was injected into the anterior thigh (three subjects) or perianal (three subjects) or periprostatic tissues (three subjects). MRI at 1.5 T was performed before injection and one, three, and seven days after injection. RESULTS: The mean of 30 nodes seen post-injection was greater than the mean of 5.8 seen pre-injection (P < 0.001). After thigh injection, a mean of three internal vs. 36 external nodes were seen. Compared with thigh injection, there was a higher fraction of internal nodes with perianal (mean of nine internal vs. 14 external, P < 0.001) and periprostatic injection (mean of 11 internal vs. five external, P < 0.001). More nodes were seen with gradient-echo sequences than with other sequences (P < 0.001). CONCLUSION: Interstitial injection of iron oxide particles increases visualization of pelvic lymph nodes. Perianal and periprostatic injection increases the number of internal pelvic lymph nodes seen compared with thigh injection.     

Dynamic contrast-enhanced MR imaging and dual-phase helical CT in the preoperative assessment of suspected pancreatic cancer: a comparative study with receiver operating characteristic analysis.

OBJECTIVE: The purpose of this study was to compare dynamic contrast-enhanced MR imaging and dual-phase helical CT in the preoperative assessment of patients with suspected pancreatic carcinoma. SUBJECTS AND METHODS: Thirty-three consecutive surgical candidates (20 men, 13 women; 39-81 years old) were included. MR imaging comprised fast spin-echo (TR/TE 4000/91), fat-suppressed T1-weighted spin-echo (500/15), and T1-weighted breath-hold gradient-echo fast low-angle shot (100/4; flip angle, 80 degrees) images before and after the administration of gadopentetate dimeglumine. Helical CT used 5-mm collimation with a pitch of 1:1.5-1.7; images were obtained 20 and 65-70 sec after injection of 150 ml of contrast material. Two pairs of interpreters who were unaware of the results of the other imaging method independently scored each examination for the presence of a lesion and for surgical resectability using a five-point scale. Results were correlated with surgery (n = 25) or consensus review (n = 8). Receiver operating characteristic methodology was used to analyze the results for resectability, and positive predictive values were calculated. RESULTS: Both MR imaging and helical CT revealed 29 of 31 lesions. In determining lesion resectability, the mean areas under the receiver operating characteristic curves were 0.96 and 0.81 (p = .01) and the positive predictive values were 86.5% and 76% (p = .02) for MR imaging and helical CT, respectively. CONCLUSION: MR imaging and helical CT performed equally well in lesion detection. MR imaging was significantly better in the assessment of resectability of pancreatic tumors.     

MR imaging detection of superparamagnetic iron oxide loaded tris-acryl embolization microspheres

PURPOSE: To assess by magnetic resonance (MR) imaging the detectability of superparamagnetic iron oxide (SPIO)-labeled microspheres (MSs) in vitro on gelose, ex vivo in kidneys from embolized sheep, and in vivo in kidneys from embolized pigs. MATERIALS AND METHODS: With various sizes of SPIO-labeled MSs, common neck and pelvic spin-echo and gradient-echo sequences were acquired on a 1.5-T MR unit. SPIO-labeled MSs of four sizes were embedded in a hydrogel as single MSs or in multiple units, or multiplets. Detection rate on MR imaging was assessed according to the real size and number of MSs. SPIO-loaded and unloaded MSs of four sizes were injected into eight sheep kidneys, which underwent MR and pathologic examinations. For each size, the location of MSs in renal vasculature was determined and compared according to the technique used. Kidneys were embolized in pigs with various amounts of MSs in three sizes. MR was performed immediately after embolization and SPIO-labeled MS detection was assessed according to size, organ, and amount injected. Results SPIO-labeled MSs provide a low signal intensity on T1-weighted sequences, without distortion. In vitro, 28% of 100-300-microm single MSs were detected and more than 80% were detected for larger sizes. MS multiplets were all detected in all sizes. Ex vivo, all sizes of MSs were detected by MR imaging in kidneys, whereas control MSs were not observed. Histologic analysis showed that there was no difference in vascular distribution between SPIO-labeled MS and control MSs, and therefore for each caliber (P > .05). Arterial location of SPIO-labeled MSs was the same on MR imaging and histologic analysis. In vivo, SPIO-labeled MS were detected in the kidney vasculature when volumes greater than 1 mL of 100-300-microm or 500-700-microm MSs were injected. Volumes lower than 1 mL SPIO-labeled MSs were hardly detected in kidneys, regardless of MS size. Conclusions SPIO-labeled MSs are detected by MR imaging with common gradient-echo sequences in vitro in gelose and ex vivo and in vivo in kidneys. SPIO-labeled MSs could allow better control of embolization and thereby enhance efficacy and safety of the procedure.     

Performance of Gd-EOB-DTPA and superparamagnetic iron oxide particles in the detection of primary liver cancer: A comparative study by alternative free-response receiver operating characteristic analysis

The performance of gadolinium-ethoxybenzyl-dieth-ylenetriaminepentaacetic acid (Gd-EOB-DTPA) and superparamagnetic iron oxide (SPIO) particles in detecting liver cancer was compared using alternative free-response receiver operating characteristic (AFROC) analysis, which allowed observers to indicate both the confidence level and the locations of all perceived abnormalities. Axial T1-weighted MR images (1.5 T) pre/post Gd-EOB-DTPA (25 μmol/kg) injection were obtained for 12 rats with chemically induced liver tumors (64 tumors). T2-weighted images (T2WI) were obtained pre/post SPIO (10 μmol/kg) injection for the same animal. Liver signal-to-noise ratio (SNR), tumor-liver contrast-to-noise ratio (CNR), and histopathologic sections corresponding to MR images were obtained. In AFROC, the location and the confidence level for each tumor were indicated independently on MR images by four radiologists. By plotting true-positive fraction and probability of false-positive per image, the area under the AFROC curve (A1) was estimated and statistically analyzed between each sequence. Either drug significantly improved tumor-liver CNR (P < .001) and tumor detection (diameter ≤ 6 mm; P < .05). Gd-EOB-DTPA significantly (P < .05) improved the A1 in T1WI. There was no A1 difference between T2WI + SPIO and T1WI + Gd-EOB-DTPA. Gd-EOB-DTPA-enhanced T1WI showed the same performance as SPIO-enhanced T2WI in detecting liver tumors.     

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.     

Comparison between high-field-strength MR imaging and CT for screening of hepatic metastases: a receiver operating characteristic analysis.

The diagnostic performance of high-field-strength magnetic resonance (MR) imaging (1.5 T) for detection of liver metastases was compared with that of computed tomography (CT). All patients (n = 52) underwent preoperative screening for metastases by means of MR imaging with T1-weighted, proton-density-weighted, and T2-weighted pulse sequences and CT scanning with unenhanced, incremental dynamic bolus-enhanced, and delayed contrast medium-enhanced techniques. Diagnostic performance was evaluated by means of receiver operating characteristic analysis in which 800 images (400 with and 400 without lesions) and five readers (4,000 observations) were used; images were obtained from patients (n = 39) in whom the same anatomic levels were available for all MR imaging and CT studies. Direct comparison between the best MR imaging technique (T2-weighted spin-echo imaging [repetition time, 2,000 msec; echo time, 70 msec]) and the best CT technique (incremental dynamic bolus CT) showed a strong trend of superiority of T2-weighted MR imaging over incremental dynamic bolus CT. No highly statistically significant difference (P greater than or equal to .01), however, was found between these two techniques.     

Hepatic metastases: randomized, controlled comparison of detection with MR imaging and CT

To determine the accuracy of magnetic resonance (MR) imaging relative to computed tomography (CT) in the diagnosis of liver metastases, a randomized, controlled study was conducted of 135 subjects, including 57 with cancer metastatic to the liver, 27 with benign cysts or hemangiomas, and 51 without focal liver disease. The sensitivity of MR imaging for detecting individual metastatic deposits was 64%, significantly greater than 51% for CT (P less than .001); the difference in sensitivity for identifying patients with one or more hepatic metastases was less (82% for MR imaging vs. 80% for CT). In patients without hepatic metastases, the specificity of MR imaging was 99% versus 94% for CT. Significant differences were found between individual MR pulse sequences in detection of individual lesions. The sensitivity of both T1-weighted spin-echo (SE) (64%) and inversion-recovery (IR) (65%) pulse sequences was significantly (P less than .001) greater than either the TE (echo time) 60 msec (43%) or TE 120 msec (43%) T2-weighted pulse sequences. Overall, the accuracy of a single T1-weighted (10-minute) pulse sequence was superior to that of contrast-enhanced CT.     

The diagnosis of splenic lymphoma by MR imaging: value of superparamagnetic iron oxide

This study was designed to evaluate superparamagnetic iron oxide (AMI-25) as a contrast agent for MR to distinguish normal spleens from those diffusely infiltrated by lymphoma. As diffuse splenic involvement lacks visible tumor-tissue boundaries, signal-intensity measurements of spleens were used as a diagnostic criterion in 33 patients (lymphoma, n = 8; benign splenomegaly, n = 5; normal subjects, n = 20). Unenhanced MR images were insensitive (four of eight patients) and nonspecific (20 of 25 patients) in the diagnosis of lymphoma. After injection of superparamagnetic iron oxide (40 mumol Fe/kg), lymphomatous spleens showed a significantly higher signal intensity (p less than .05) than did normal spleens or spleens enlarged by benign disease (hepatic cirrhosis, n = 4; spherocytosis, n = 1). Changes in splenic MR signal intensity unambiguously identified eight of eight lymphomatous spleens and 25 of 25 normal or enlarged spleens that did not contain lymphoma. Phagocytosis of superparamagnetic iron oxide in lymphomatous spleens is reduced because of diffuse displacement of splenic macrophages by lymphoma cells and/or by immunologic suppression of macrophage activity. Our results suggest that superparamagnetic iron oxide (AMI-25) can improve the accuracy of MR imaging in the diagnosis of splenic lymphoma. With further development, this noninvasive technique may reduce the need for diagnostic splenectomy in lymphoma patients.     

Diagnosis of abdominal venous thrombosis by means of spin-echo and gradient-echo MR imaging: analysis with receiver operating characteristic curves

The authors compared the accuracy of spin-echo (SE) and gradient-echo (GRE) magnetic resonance images in diagnosis of abdominal venous thrombosis. Images of 292 abdominal veins in 72 patients were reviewed in a blinded manner by three radiologists, with seven levels of confidence for diagnosis. Corroborative studies proved thrombosis (n = 95) and vessel patency (n = 197). Receiver operating characteristic (ROC) curves were constructed for SE images alone, GRE images alone, and SE and GRE images combined. At specificities of 90% and 95%, thrombi were identified with sensitivities, respectively, of 76% and 63% with SE images, 74% and 58% with GRE images, and 88% and 82% with combined SE and GRE images. The area under the ROC curve for SE and GRE images combined (0.958 +/- 0.011 [standard deviation]) was significantly larger (P less than .001) than that for SE images alone (0.913 +/- 0.018) and GRE images alone (0.921 +/- 0.016). It is concluded that combination of SE and GRE images significantly increases the accuracy of diagnosis of abdominal venous thrombosis.     

Contrast enhancement with GD-EOB-DTPA in MR imaging of hepatocellular carcinoma in mice: A comparison with superparamagnetic iron oxide

The purpose of this study was to evaluate the ability of the new liver-specific magnetic resonance contrast agent gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid (Gd-EOB-DTPA) to detect hepatocellular carcinoma (HCC). Seventeen mice with 66 chemically induced HCCs underwent magnetic resonance imaging with both Gd-EOB-DTPA (30 μmol/kg) and superparamagnetic iron oxide (SPIO; 10 μmol/kg). After enhancement, lesion-to-liver contrast-to-noise ratios (CNRs) of 47 detected HCCs increased negatively from 3.7 ± 10.7 (mean ± SD) to –55.1 ± 25.8 with Gd-EOB-DTPA (P < .001) and increased positively from 10.4 ± 10.4 to 26.1 ± 16.3 with SPIO (P < .001). The improvement of CNR after administration of SPIO was less in smaller lesions (< 4 mm), whereas that after administration of Gd-EOB-DTPA was independent of lesion size. However, Gd-EOB-DTPA positively enhanced four HCCs (8.5%), both highly differentiated (grade 1) and moderately differentiated (grade 2). Gd-EOB-DTPA allows the conspicuous detection of small HCCs; however, moderately differentiated HCCs occasionally may be positively enhanced.     

Dual contrast enhanced magnetic resonance imaging of the liver with superparamagnetic iron oxide followed by gadolinium for lesion detection and characterization

AIM: Iron oxide contrast agents are useful for lesion detection, and extracellular gadolinium chelates are advocated for lesion characterization. We undertook a study to determine if dual contrast enhanced liver imaging with sequential use of ferumoxides particles and gadolinium (Gd)-DTPA can be performed in the same imaging protocol. MATERIALS AND METHODS: Sixteen patients underwent dual contrast magnetic resonance imaging (MRI) of the liver for evaluation of known/suspected focal lesions which included, metastases (n = 5), hepatocellular carcinoma (HCC;n = 3), cholangiocharcinoma(n = 1) and focal nodular hyperplasia (FNH;n = 3). Pre- and post-iron oxide T1-weighted gradient recalled echo (GRE) and T2-weighted fast spin echo (FSE) sequences were obtained, followed by post-Gd-DTPA (0.1 mmol/kg) multi-phase dynamic T1-weighted out-of-phase GRE imaging. Images were analysed in a blinded fashion by three experts using a three-point scoring system for lesion conspicuity on pre- and post-iron oxide T1 images as well as for reader's confidence in characterizing liver lesions on post Gd-DTPA T1 images. RESULTS: No statistically significant difference in lesion conspicuity was observed on pre- and post-iron oxide T1-GRE images in this small study cohort. The presence of iron oxide did not appreciably diminish image quality of post-gadolinium sequences and did not prevent characterization of liver lesions. CONCLUSION: Our results suggest that characterization of focal liver lesion with Gd-enhanced liver MRI is still possible following iron oxide enhanced imaging.Kubaska, S.et al. (2001). Clinical Radiology, 56, 410-415 Copyright 2001 The Royal College of Radiology.     

Preoperative breast cancer staging: MR imaging of the axilla with ultrasmall superparamagnetic iron oxide enhancement

PURPOSE: To evaluate magnetic resonance (MR) imaging with ultrasmall superparamagnetic iron oxide (USPIO) enhancement for preoperative axillary lymph node staging in patients with breast cancer by using histopathologic findings as the standard of reference. MATERIALS AND METHODS: MR imaging was performed with a 1.5-T system within 24-36 hours after the start of intravenous slow-drip infusion of USPIO in 20 patients with breast cancer who were scheduled for surgery, followed by gadolinium-enhanced MR imaging. Lymph nodes were staged prospectively by using newly established criteria, and results were correlated with histologic findings. RESULTS: In two patients, preoperative findings led to a change in therapeutic approach, and neoadjuvant chemotherapy was given; both patients were excluded from statistical analysis. Results of axillary staging with USPIO-enhanced MR imaging were true-positive in nine, true-negative in seven, false-positive in zero, and false-negative in two of 18 patients (sensitivity, 82%; specificity, 100%; positive predictive value, 100%; second reader, kappa = 1.0). Four hundred five lymph nodes were detected with MR imaging. For first and second readers, respectively, lymph node-based sensitivity was 83% and 73% and specificity was 96% and 97% (kappa = 0.68). USPIO as the intravascular contrast agent could not replace gadolinium for assessment of the primary tumor; however, no clinically relevant interaction was seen. Thus, an integrated imaging approach was feasible in all patients. CONCLUSION: USPIO-enhanced MR imaging has the potential to become an adjunct to conventional MR imaging of the breast for preoperative assessment of axillary lymph nodes in patients with breast cancer.     

Hepatic adenomatosis: MRI demonstration with the use of superparamagnetic iron oxide

This case report describes a case of a 38-year-old woman with hepatic adenomatosis. MRI revealed five hyperintense nodular liver lesions on T1-weighted images which were hypo-isointense with the liver parenchyma on T2-weighted images. Serial gadolinium-enhanced images did not reveal distinctive imaging findings. With the use of superparamagnetic iron oxide (SPIO) particles, hyperintense adenomas revealed signal loss on T1-weighted images after SPIO. Two subcapsular adenomas were resected based on MRI findings and histopathology confirmed MRI diagnosis.