Focal liver disease: comparison of dynamic contrast-enhanced CT and T2-weighted fat-suppressed, FLASH, and dynamic gadolinium-enhanced MR imaging at 1.5 T.

Dynamic contrast medium-enhanced computed tomography (CT), T2-weighted fat-suppressed spin-echo (T2FS) magnetic resonance (MR) imaging, and breath-hold T1-weighted fast low-angle shot (FLASH) MR imaging before and after dynamic gadopentetate dimeglumine injection were compared in 73 patients with clinically suspected liver disease. Observer confidence for presence of focal lesions was determined by using receiver operating characteristic analysis. For all MR images, hepatic lesion-liver signal-to-noise ratios were evaluated qualitatively. and resolution and presence of artifacts were evaluated qualitatively. Lesion detection was greatest with T2FS (n = 272) and enhanced FLASH (n = 244) and was statistically greater with both of these than with CT (n = 220) and FLASH (n = 219) (P less than .03). Correct lesion characterization was greatest with enhanced FLASH (n = 236) (P less than .01), followed by CT (n = 199), FLASH (n = 164), and T2FS (n = 144). Enhanced FLASH was particularly successful in characterization of 5-mm- to 1.5-cm-diameter lesions as cystic or solid.     

Malignant lesions of the liver with high signal intensity on T1-Weighted MR images

Our purpose was to identify the histologic types of malignant liver lesions with high signal intensity (SI) on T1-weighted images and to describe the MR imaging features. Thirteen patients with malignant liver lesions high in SI on T1-weighted images were studied with a 1.5-T MR imager using pre- and serial postcontrast spoiled gradient-echo (SGE) sequences (all patients), T2-weighted fat-suppressed spin-echo sequences (all patients), precontrast T1-weighted fat-suppressed spin-echo sequences (five studies in five patients), and precontrast out-of-phase SGE sequences (seven studies in six patients). Images were reviewed retrospectively to determine number of lesions; lesion size; SI of lesions on T1-weighted, T2-weighted, and fat-attenuated T1-weighted images; distribution of high SI in lesions on T1-weighted images; and tumor enhancement pattern. Seven patients had multiple tumors high in SI on T1-weighted images and six patients had solitary tumors. Seventy-two lesions were less than 1.5 cm in diameter and 35 lesions were more than 1.5 cm in diameter. Nine patients had solid malignant lesions and four patients had cystic malignant lesions. All tumors more than 1.5 cm in diameter were heterogeneously high in SI on T1-weighted images, and all tumors less than 1.5 cm were completely homogeneous or homogeneous with a small central hypointense focus. All tumors were more conspicuous on T1-weighted fat-attenuated images, both on excitation spoiled fat-suppressed spin-echo or on out-of-phase SGE images with the exception of one fat-containing hepatocellular carcinoma (HCC). In one patient with melanoma metastases and one patient with multiple myeloma nodules, appreciably more lesions were detected on out-of-phase SGE images. Causes of hyperintensity were considered to be either fat, melanin, central hemorrhage, or high protein content, all of which may be seen in a variety of tumors. Fat-attenuation techniques are helpful in the detection of these lesions.     

Detection of hypervascular malignant foci in borderline lesions of hepatocellular carcinoma: comparison of dynamic multi-detector row CT, dynamic MR imaging and superparamagnetic iron oxide-enhanced MR imaging

The study object was to retrospectively compare the detection rate of hypervascular foci visualized by CT during hepatic arteriography (CTHA) in borderline nodules, which was observed upon cirrhotic livers, on dynamic MDCT, dynamic gadolinium-enhanced MR (dynamic MR), and SPIO-enhanced MR imaging. Eighty-five nodules in 49 patients with cirrhosis were evaluated. When a part of the nodule showed hyperdensity relative to the surrounding areas of the nodule on CTHA, it was defined as "hypervascular focus." The relationships between the dynamic MDCT and dynamic MR and SPIO-enhanced MR imaging findings of these foci were analyzed using X(2) test. Hypervascular foci were detected in 17 (53%) of 32 on the arterial dominant phase of dynamic MDCT, in 19 (37%) of 51 on the arterial dominant phase of dynamic MR and in 6 (26%) of 23 on SPIO-enhanced MR imaging. Arterial dominant phase of dynamic MDCT demonstrated a significantly higher detection rate of hypervascular foci less than 5 mm in diameter than did dynamic and SPIO MR imaging (p<0.05). Hypervascular foci in borderline nodules could be better visualized by dynamic MDCT than by gadolinium- and SPIO-enhanced MR imaging. Dynamic MDCT is recommended for the follow-up examination of hypovascular borderline lesions.     

3T MR扩散加权成像对肝脏转移瘤的诊断价值初探

目的:探讨MR扩散加权成像(DWI)对肝脏转移瘤的诊断价值.方法:对临床确诊的25例肝脏转移瘤患者进行DWI、T2WI及Gd-DTPA-T1WI扫描,观察肝脏转移瘤的信号特征,并统计分析3种序列所检出的转移瘤数目.结果:对于直径大于1.0 cm的32个转移瘤灶,3种序列都准确检出;而直径小于1.0 cm的微小转移瘤,在T2WI上共检出76个,病灶信号均为略高信号;在DWI上共栓出85个,呈高信号;在增强门脉期T1WI上共检出68个,大部分瘤灶呈环状强化或不均匀强化.3种序列对转移瘤的检出差别无显著性意义.结论:DWI对肝脏微小转移瘤的敏感性较高,将DW与T2W、GD-DTPA-T1W 3种序列相结合,可以互相弥补各序列不足之处,将大大提高肝脏微小转移瘤灶的检出率.     

Preoperative detection of hepatic metastases: Comparison of diffusion-weighted, T2-weighted fast spin echo and gadolinium-enhanced MR imaging using surgical and histopathologic findings as standard of reference

Purpose

The purpose of this study was to retrospectively compare the respective sensitivities of diffusion-weighted (DW), T2-weighted fast spin-echo (T2WFSE) and gadolinium chelate-enhanced MR imaging in the preoperative detection of hepatic metastases using intraoperative ultrasonographic and histopathologic findings as the standard of reference.

Materials and methods

Twenty-seven patients with 64 surgically and histopathologically proven hepatic metastases had MR imaging of the liver, including DW, T2WFSE and dynamic gadolinium chelate-enhanced MR imaging. Images from each MR sequence were separately analyzed by two readers with disagreements resolved by consensus readings. The findings on MR images were compared with intraoperative ultrasonographic and histopathologic findings on a lesion-by-lesion basis to determine the sensitivity of each MR sequence. Statistical review of the lesion-by-lesion analysis was performed with the McNemar test.

Results

DW, T2WFSE and gadolinium chelate-enhanced MR imaging allowed the depiction of 54/64 (84.4%; 95% CI: 73.1-92.2%), 44/64 (68.8%; 95% CI: 55.9-79.8%), and 51/64 (79.7%; 95% CI: 67.8-88.7%) hepatic metastases respectively. DW MR images allowed depiction of significantly more hepatic metastases than did T2WFSE and was equivalent to gadolinium chelate-enhanced MR imaging (P = .002 and P = .375, respectively).

Conclusion

DW MR imaging is superior to T2WFSE imaging and equivalent to gadolinium chelate-enhanced MR imaging for the preoperative detection of hepatic metastases. Further studies however are needed to determine at what extent DW MR imaging can be used as an alternative to gadolinium chelate-enhanced MR imaging for the preoperative depiction of hepatic metastases.     

Whole-body MR imaging: evaluation of patients for metastases

PURPOSE: To compare the results of whole-body magnetic resonance (MR) imaging with staging based on computed tomographic (CT), dedicated MR imaging, and nuclear scintigraphic results as standard of reference. MATERIALS AND METHODS: Fifty-one patients with known malignant tumors were included in the study. Patients were placed on a rolling table platform capable of moving the patient rapidly through the isocenter of the magnet bore. The thorax and the abdomen were imaged by using fast breath-hold T2-weighted sequences in the transverse plane. After intravenous administration of a paramagnetic contrast agent, three-dimensional gradient-echo data sets were collected in five stations and covered the body from the skull to the knees. Location and size of cerebral, pulmonary, hepatic, and osseous metastases were documented by two experienced radiologists. Whole-body MR imaging findings were compared with results obtained at skeletal scintigraphy, CT, and dedicated MR imaging. RESULTS: The mean examination time for whole-body MR imaging was 14.5 minutes. All cerebral, pulmonary, and hepatic metastases greater than 6 mm in diameter could be identified with whole-body MR imaging. Small pulmonary metastases were missed with MR imaging, which did not change therapeutic strategies, but MR imaging depicted a single hepatic metastasis that was missed with CT. Skeletal scintigraphy depicted osseous metastases in 21 patients, whereas whole-body MR imaging revealed osseous metastases in 24 patients. The additional osseous metastases seen with MR imaging were confirmed at follow-up examinations but did not result in a change in therapy. Whole-body MR imaging performed on a per-patient basis revealed sensitivity and specificity values of 100%. CONCLUSION: Whole-body MR imaging for the evaluation of metastases compared well with the reference techniques for cerebral, pulmonary, and hepatic lesions. Whole-body MR imaging was more sensitive in the detection of hepatic and osseous metastases than were the reference techniques.     

Detection of acute and treated lesions of hepatosplenic candidiasis: comparison of dynamic contrast-enhanced CT and MR imaging.

Dynamic contrast-enhanced computed tomography (CT) was compared with 1.5-T magnetic resonance (MR) imaging with FLASH (fast low-angle shot), gadolinium-enhanced FLASH (Gd-FLASH), and T2-weighted fat-suppression (T2FS) sequences in 11 patients with hematologic malignancies, five with biopsy-confirmed hepatosplenic candidiasis treated with antifungal chemotherapy and six with a clinical history suggestive of acute hepatosplenic candidiasis. CT and MR images were separately interpreted in a prospective fashion. MR imaging showed lesions compatible with candidiasis in the liver in six patients, the spleen in five, and the kidneys in one. CT showed candidiasis-compatible lesions in the liver in three patients and the spleen in one; no renal lesions were shown. Differences between acute and treated candidal lesions were observed. Gd-FLASH images showed the most liver lesions (n = 106), followed by FLASH (n = 85), T2FS (n = 20), and CT (n = 18). MR imaging performed better than CT in distinguishing candidal hepatic lesions from recurrent lymphoblastic lymphoma in one patient and from hepatic infarcts in another. The results suggest that MR imaging may be superior to CT in detecting lesions of hepatosplenic candidiasis.     

Hemodynamic characterization of focal hepatic lesions: role of ferucarbotran-enhanced dynamic MR imaging using T2-weighted multishot spin-echo echo-planar sequence

PURPOSE: To investigate the role of ferucarbotran-enhanced dynamic MR imaging using multishot spin-echo echo-planar sequence in the evaluation of hemodynamics of focal hepatic lesions. MATERIALS AND METHODS: Sixty-three focal hepatic lesions (24 benign and 39 malignant) from 53 consecutive patients who underwent both ferucarbotran-enhanced MR imaging and dynamic computed tomography (CT) were included in this study. MR imaging was performed with a 1.5-T scanner with a phased-array coil. T2-weighted multishot spin-echo echo-planar sequences (TR/TE = 1714-2813/80 msec) were obtained during a single breathhold before and 15, 60, 120, 180, and 600 seconds after intravenous injection of ferucarbotran. The enhancement patterns of lesions were classified into three categories by a study coordinator on the basis of dynamic CT images as hypervascular, hypovascular, and hemangioma type. The study coordinator created mean contrast-to-noise ratio of lesions vs. time curves for each enhancement pattern for quantitative analyses. Moreover, three radiologists separately and blindly reviewed MR images, and then assigned three confidence scores for the three enhancement patterns to each lesion. Sensitivity, specificity, and receiver operating characteristic analyses were performed. RESULTS: Quantitative analyses showed characteristic enhancement curves for each enhancement pattern. Mean sensitivities/specificities were 0.816/0.882, 0.897/0.863, and 0.800/0.989 for hypervascular, hypovascular, and hemangioma types, respectively. Mean areas under the receiver operating characteristic curve were 0.886 for hypervascular type and 0.913 for hypovascular type. CONCLUSION: Ferucarbotran-enhanced dynamic MR imaging can be used to successfully characterize the hemodynamics of focal hepatic lesions.     

Small (<or= 2 cm) hepatic lesions in colorectal cancer patients: detection and characterization on mangafodipir trisodium-enhanced MRI

OBJECTIVE: The purpose of this study was to evaluate whether mangafodipir trisodium (MnDPDP)-enhanced MRI improves the detection and characterization of small ( 2.0 cm). The differences between MnDPDP-enhanced MRI and helical CT with regard to the detection rates for hepatic lesions and metastases and with regard to the false-positive rates for hepatic metastases were analyzed using the McNemar test. The performances of MnDPDP-enhanced MRI and helical CT in indicating metastases of focal liver lesions were analyzed using receiver operating characteristic curves. RESULTS: No statistically significant differences were seen between MnDPDP-enhanced MRI and helical CT in the detection of all hepatic lesions (p = 0.383) and small lesions (p = 0.210). However, concerning the differentiation between benign and metastatic lesions, MnDPDP-enhanced MRI was superior to helical CT both for all hepatic lesions (p = 0.023) and for small lesions (p = 0.015), and remained better when the analyses were restricted to patients with histopathologic confirmation (p = 0.023 for both). MnDPDP-enhanced MRI changed the diagnosis of hepatic metastasis in nine (13.0%) of 69 patients. Of 12 metastases that were found on MnDPDP-enhanced MRI and missed on helical CT, 11 lesions (91.7%) were small. MnDPDP-enhanced MRI showed a significantly greater detection rate than helical CT for small hepatic metastases (p = 0.022). MnDPDP-enhanced MRI was better when the analyses were restricted to patients with histopathologic confirmation (p = 0.043). CONCLUSION: Although MnDPDP-enhanced MRI is equal to helical CT in detection of both all hepatic lesions and small lesions in patients with colorectal carcinoma, it is superior to CT in characterization of the lesions.     

Hepatic Cavernous Hemangioma in Cirrhotic Liver: Imaging Findings

Objective

To document the imaging findings of hepatic cavernous hemangioma detected in cirrhotic liver.

Materials and Methods

The imaging findings of 14 hepatic cavernous hemangiomas in ten patients with liver cirrhosis were retrospectively analyzed. A diagnosis of hepatic cavernous hemangioma was based on the findings of two or more of the following imaging studies: MR, including contrast-enhanced dynamic imaging (n = 10), dynamic CT (n = 4), hepatic arteriography (n = 9), and US (n = 10).

Results

The mean size of the 14 hepatic hemangiomas was 0.9 (range, 0.5-1.5) cm in the longest dimension. In 11 of these (79%), contrast-enhanced dynamic CT and MR imaging showed rapid contrast enhancement of the entire lesion during the early phase, and hepatic arteriography revealed globular enhancement and rapid filling-in. On contrast-enhanced MR images, three lesions (21%) showed partial enhancement until the 5-min delayed phases. US indicated that while three slowly enhancing lesions were homogeneously hyperechoic, 9 (82%) of 11 showing rapid enhancement were not delineated.

Conclusion

The majority of hepatic cavernous hemangiomas detected in cirrhotic liver are small in size, and in many, hepatic arteriography and/or contrast-enhanced dynamic CT and MR imaging demonstrates rapid enhancement. US, however, fails to distinguish a lesion of this kind from its cirrhotic background.     

Detection of hepatic masses in patients with carcinoma: comparative sensitivities of sonography, CT, and MR imaging

To evaluate the sensitivity of sonography, CT, and MR imaging in the detection of hepatic masses in carcinoma patients, we conducted a prospective study of 75 consecutive patients with gastrointestinal tumors who were admitted for surgical resection of the primary tumor. Sonography was performed with convex transducers of 3.5 and 5.0 MHz. Three noninvasive CT techniques were used: unenhanced CT scans, the incremental bolus dynamic scanning technique, and delayed scanning 4-6 hr after bolus injection of 60 g of iodine. MR images (1.5 T) were acquired as presaturated T1- and T2-weighted spin-echo sequences and as breath-holding fast low-angle shot (FLASH) 60 degrees and FLASH 15 degrees sequences. As it is difficult to distinguish benign from malignant masses solely on the basis of morphologic criteria, the techniques for each imaging method were designed to detect and not to characterize hepatic lesions. Each examination was interpreted blindly, and the results were compared with surgical findings, intraoperative sonography, and biopsy of the liver as the gold standard. All focal hepatic masses verified at surgery, malignant or benign, were included in the analysis. Sixty-five (68%) of 95 focal hepatic masses were detected by CT, 60 lesions (63%) by MR, and 50 lesions (53%) by sonography. Although lesions 1-2 cm were shown almost equally well by CT and MR (74% and 77%, respectively), the detection rate of smaller lesions (less than 1.0 cm) decreased more drastically with MR (31%) than with CT (49%). Sonography had a sensitivity of only 20% with the smaller lesions. All imaging techniques had a sensitivity of 100% for focal hepatic masses larger than 2.0 cm. Our results show that CT has a higher overall sensitivity (68%) than MR and sonography for the detection of focal hepatic masses. When the results of the three procedures are combined, the overall sensitivity is 77%. This is unsatisfactorily low, as CT and MR have a size threshold of about 1.0 cm and are relatively unreliable for the detection of smaller lesions.     

Comparative evaluation of computerized tomography/magnetic resonance (1.5 T) in the detection of brain metastasis]

Forty-four patients with small cell carcinoma of the bronchus underwent CT and MR studies of the brain to detect cerebral metastases. All patients were studied with contrast-enhanced CT scans, short (T1-weighted) and long (T2-weighted), spin-echo (SE) and FLASH 90 degrees MR sequences. Gd-DTPA enhanced SE-T1 and FLASH 90 degrees sequences were also obtained. A quantitative comparison of the results was carried out to assess the sensitivity of the different techniques in the detection of brain metastases according to lesion diameter. Metastases were identified in 19/44 patients (43%). All techniques detected the lesions greater than 2 cm; of the metastases less than 2 cm, 63/124 (51%) were detected only by Gd-DTPA SE-T1 and FLASH sequences and 11 more (9%) only by Gd-DTPA SE-T1 scans. All the lesions identified on enhanced CT scans or on T2-weighted images were easily detected by Gd-DTPA scans. CT sensitivity was higher than that of pre-contrast SE-T1 and FLASH studies and only slightly lower than that of T2-weighted images. As for lesions less than 2 cm, Gd-DTPA T1-weighted sequences had the highest detection rate (124 lesions) versus Gd-DTPA FLASH 90 degrees scans (113 lesions) and precontrast T1-weighted scans (45 lesions). When comparing Gd-DTPA SE-T1 and FLASH 90 degrees sequences in the detection of lesions less than 1 cm, we observed that the latter missed 9% of metastases, mainly due to a high rate of magnetic susceptibility artifacts and to lower contrast resolution. Therefore, Gd-DTPA SE-T1 images still remain the most accurate technique in the assessment of cerebral metastases.     

胃肠道间质瘤肝转移灶的18F-FDG PET/CT显像特点

目的分析胃肠道间质瘤(GIST)肝转移灶¹⁸F-脱氧葡萄糖(FDG)PET/CT显像特点,以提高诊断准确性。方法回顾性分析2013年5月至2019年7月间在福建省肿瘤医院行¹⁸F-FDG PET/CT检查并确诊肝转移的33例GIST患者(男18例,女15例,年龄34~70岁)的临床和影像资料。患者均行¹⁸F-FDG PET/CT早期显像,另有9例后行延迟显像。对患者PET/CT图像行视觉分析,比较病灶与肝本底的放射性摄取,将转移灶分为高代谢、稍高代谢、等或低代谢;计算并比较GIST原发灶与肝转移灶的最大标准摄取值(SUVmax),另分析两者的关系。采用Wilcoxon秩和检验和Spearman秩相关分析数据。结果33例GIST的肝转移患者中,肝转移单发9例,多发24例,共104个病灶。104个肝转移病灶直径为0.8~14.6[2.2(1.5,3.9)]cm,SUVmax为1.4~21.5[3.6(2.4,5.7)]。94.2%(98/104)的病灶边界清楚;65.4%(68/104)的病灶密度均匀(其中2个囊性病灶),34.6%(36/104)的病灶密度不均匀,可见出血、囊变或坏死。PET图像视觉分析中,38.4%(40/104)的病灶为高代谢,26.0%(27/104)的病灶为稍高代谢,35.6%(37/104)的病灶为等或低代谢。24例多发肝转移患者中,79.2%(19/24)同时存在不同代谢水平的病灶。67个代谢增高病灶中,34.3%(23/67)呈均匀代谢,其中13个病灶直径<2.0 cm;65.7%(44/67)呈不均匀代谢,其中36个病灶直径≥2.0 cm。15例GIST同时性肝转移患者的原发灶与肝转移灶SUVmax[9.2(6.8,14.5)与3.8(2.1,6.0)]间呈中等程度相关(rs=0.556,P<0.01);两者差异有统计学意义(z=-5.098,P<0.01)。延迟显像中,13/15的等或低代谢肝转移病灶转为稍高代谢。结论GIST肝转移¹⁸F-FDG PET/CT显像通常边界清楚,常合并囊变、出血或坏死;代谢表现多样;延迟显像有助于低代谢GIST肝转移病灶的诊断。     

Detection of focal hepatic masses: prospective evaluation with CT, delayed CT, CT during arterial portography, and MR imaging

The sensitivities of contrast medium-enhanced computed tomography (CT), delayed CT (DCT), CT during arterial portography (CTAP), and magnetic resonance (MR) imaging for detecting focal liver lesions were prospectively evaluated in eight patients who subsequently underwent hepatic lobectomy or transplantation. Pathologic evaluation of the resected liver specimens demonstrated 37 lesions. The sensitivities were 81% (30 of 37 lesions) for CTAP, 57% (21 of 37 lesions) for MR imaging, 52% (12 of 23 lesions) for DCT, and 38% (14 of 37 lesions) for contrast-enhanced CT. The difference between the sensitivity of CTAP and the sensitivities of the other imaging tests was statistically significant (P less than .004). Of the lesions smaller than 1 cm in diameter, CTAP depicted 61% (11 of 18 lesions), MR imaging 17% (three of 18 lesions), CT 0% (zero of 18 lesions), and DCT 0% (zero of nine lesions). It is concluded that for preoperative detection of focal hepatic masses, CTAP is the most accurate technique available to most radiologists. Patients with primary or secondary hepatic neoplasms who are being considered for hepatic resection should undergo CTAP as part of their preoperative examination.     

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.     

1.5 T MR导向下肝脏恶性肿瘤射频消融治疗技术初探

目的 探讨1.5 T MR引导下对肝脏恶性肿瘤射频消融治疗的可行性.方法 23例44个经病理证实、不能或不愿手术的肝脏恶性肿瘤病灶,其中11例为原发性肝癌、12例为肝转移癌,肿瘤最大径平均(3.3±1.8)cm,均采用MR兼容多极射频针在1.5 T MR引导下进行射频消融治疗.术后MR扫描观察消融情况,消融灶完全覆盖原病灶、范围超出病灶边缘0.5～1.0 cm为消融完全.结果 所有消融均顺利完成,平均手术时间(93±33)min,消融灶均完全覆盖病灶,无胆瘘、膈肌穿孔、黄疸、气胸等并发症发生.射频电极针在MR图像上呈低信号.消融灶在T2WI序列上呈低信号,周围可见薄层高信号环绕;T1WI序列上消融灶呈明显高信号,边界清晰;DWI上消融灶呈等低信号,周围呈环状稍高信号.结论 1.5 T MR引导下肝脏恶性肿瘤射频消融是安全、有效的技术.     

Malignant lesions of the liver identified on T1- but not T2-weighted MR images at 1.5 T

The authors reviewed their 21/2-year experience with a magnetic resonance (MR) imaging protocol for a 1.5-T MR imager that included T2-weighted fat-suppressed spin-echo, T1-weighted breath-hold gradient-echo, and serial dynamic gadolinium-enhanced T1-weighted gradient-echo imaging to identify histologic types of malignant liver lesions more apparent on T1- than on T2-weighted images. MR images of 212 consecutive patients with malignant liver lesions were reviewed. T2-weighted, T1-weighted, and dynamic contrast-enhanced T1-weighted images were examined separately in a blinded fashion. Seven patients demonstrated liver lesions (lymphoma [two patients] and carcinoid, hepatocellular carcinoma, colon adenocarcinoma, transitional cell carcinoma, and melanoma [one patient each]) on T1-weighted images that were inconspicuous on T2-weighted images. In all cases, the lesions were most conspicuous on T1-weighted images obtained immediately after administration of contrast agent. Histologic confirmation was present for all seven patients. The consistent feature among these lesions was that they were hypovascular, due either to a fibrous stroma or to dense monoclonal cellularity. These results suggest that in some patients with hypovascular primary neoplasms, the lesions may be identified only on T1-weighted images, and that immediate postcontrast T1-weighted images are of particular value in demonstrating lesions.     

Liver metastases from pancreatic adenocarcinoma: MR imaging characteristics

PURPOSE: To describe the magnetic resonance imaging spectrum of appearances of liver metastases from pancreatic ductal adenocarcinoma. MATERIALS AND METHODS: We retrospectively evaluated the MRI exams performed between July 1996 and August 2001 in all patients who had liver metastases from pancreatic adenocarcinoma and histopathologic diagnosis from either the primary pancreatic tumor, liver metastases, or both. Sixteen patients were included in the study. All MR studies were performed at 1.5 T with a standard protocol including T1- and T2-weighted images and serial post-gadolinium spoiled gradient echo (SGE) images. Location, size, number, signal characteristics on T1- and T2-weighted images, and pattern of enhancement on serial gadolinium-enhanced SGE images were assessed. RESULTS: The diameter of metastases ranged from a few millimetres to 4 cm, and 12 patients (75%) had only lesions of 1.5 cm or less. Capsular-based liver metastases were found in 13 patients (81%) and three patients had only capsular-based lesions with a diameter under 1.5 cm. Hypervascular lesions were found in six patients (38%) and hypovascular lesions in 10 patients (62%). Perilesional enhancement was present in 10 patients (62%), with six patients (38%) having ring perilesional enhancement and eight patients (50%) having wedge-shaped perilesional enhancement. CONCLUSION: On MR imaging, hepatic metastases from pancreatic adenocarcinoma show a range of enhancement patterns. Hypervascular metastases are not rare. Capsular based distribution, small diameter, and perilesional enhancement are common features. This retrospective study describes the MR imaging spectrum of appearances of liver metastases from pancreatic adenocarcinoma in patients with histopathologic confirmation of the diagnosis.     

Malignant liver lesions: Comparison of spiral CT arterial portography and MR imaging for diagnostic accuracy,cost, and effect on patient management

We compared two imaging techniques, spiral CT arterial portography (CTAP) and MR imaging, for diagnostic accuracy, procedural cost, and effect on management of 26 patients referred for hepatic surgery for suspected limited malignant liver disease. CTAP and MR imaging were done within a 1-week period (19 within 24 hours); the results of the studies were interpreted prospectively by separate reviewers. Surgical data were evaluated in conjunction with imaging data in 10 patients. Lesion detection and segmental involvement were determined and sensitivity and specificity were calculated. Procedural cost was determined from hospital billing codes. Effect on patient management was determined by the referring oncologic surgeon. CTAP and MR imaging showed 185 and 176 true-positive malignant lesions, 15 and zero false-positive malignant lesions, zero and 18 true-negative malignant lesions, and 13 and 22 falsenegative malignant lesions, respectively. CTAP and MR imaging showed 107 and 105 true-positive segments, 11 and zero false-positive segments, 80 and 91 true-negative segments, and four and six false-negative segments, respectively. There was a significant difference in specificity of segmental involvement between MR imaging (1.0 ± 0) compared with CTAP (0.88 ± 0.05), P=.03. Total procedural cost was $3,499 for CTAP and $1,224 for MR imaging. CTAP findings did not change patient management over MR imaging findings in any patient, whereas MR imaging findings resulted in a change in patient management over CTAP findings in seven patients (P=.015). The results of our study suggest that MR imaging has higher diagnostic accuracy and greater effect on patient management than CTAP does and is 64% less expensive.     

Detection of hepatic metastases: comparison of contrast-enhanced CT, unenhanced MR imaging, and iron oxide-enhanced MR imaging

Diagnostic accuracy of contrast-enhanced CT, unenhanced MR imaging, and MR images enhanced with superparamagnetic iron oxide was evaluated in 10 patients with histologically proved hepatic metastases. First, diagnostic performance of the imaging technique with respect to the ability of radiologists to recognize the presence or absence of a metastasis was measured by using receiver-operating-characteristic (ROC) analysis of single images. Second, the total number of lesions (N = 108) detected by "complete" CT and MR examinations was counted. Finally, lesion-liver contrast-to-noise ratios (CNR) were measured in all MR sequences. The area under the ROC curve was .67 +/- .03 for contrast-enhanced CT, .81 +/- .07 for the unenhanced SE 260/14 sequence, and .92 +/- .01 for the iron oxide-enhanced SE 1500/40 sequence. The enhanced SE 1500/40 sequence yielded significantly (p less than .005) greater accuracy than did contrast-enhanced CT. The same sequence detected significantly (p less than .05) more lesions than all other imaging techniques (19% more than the best unenhanced MR sequence and 36% more than contrast-enhanced CT). The enhanced SE 1500/40 sequence also yielded the highest CNR value (19.5 +/- 10.2) of all MR sequences. These results indicate that iron oxide-enhanced MR imaging is a superior imaging technique for the detection of hepatic lesions.