Role of functional magnetic resonance imaging in assessing metastatic leiomyosarcoma response to chemoembolization

PURPOSE: To assess the value of functional magnetic resonance (MR) imaging in the evaluation of early tumor response after transarterial chemoembolization (TACE) for metastatic leiomyosarcoma and compare tumor response using functional MR imaging versus traditional imaging response assessment, which is based on tumor size. MATERIALS AND METHODS: We evaluated 31 lesions in 10 patients with liver metastases from leiomyosarcoma using MR imaging studies before and after TACE. Diffusion and contrast-enhanced MR imaging was performed on a 1.5-T unit. Imaging protocol consisted of T2-weighted fast spin-echo images, breath-hold diffusion-weighted echo-planar images, and breath-hold unenhanced and contrast-enhanced T1-weighted 3-dimensional fat-suppressed spoiled gradient-echo images in the arterial phase (20 seconds) and portal venous phase (60 seconds). Parameters evaluated included change in tumor size, enhancement, and apparent diffusion coefficient (ADC) values. Median survival was also calculated for the entire cohort. RESULTS: The 31 lesions evaluated had a mean size of 4.8 cm before treatment. Tumor size decreased only by 2% immediately after treatment. Decrease of tumor enhancement after treatment was significant (P < 0.0001) in the arterial phase (69%) as well as in the portal venous phase (64%). After TACE, mean tumor ADC increased by 20% (P = 0.0015), whereas mean nontreated liver, spleen, and muscle ADC values did not change significantly (P = 0.44, P = 0.287, and P = 0.098, respectively). Patient survival from time of first TACE was 21 months for the entire cohort. CONCLUSION: In patients with leiomyosarcoma and liver metastases who were treated with TACE, significant early changes in the treated lesions occurred on functional MR imaging. These include decrease in tumor enhancement and increase in tumor ADC value, suggesting increasing tumor necrosis and cell death. Changes in tumor size were small and inadequate to assess treatment response, suggesting limitation of the current response criteria in the early assessment of tumor response.     

Assessment of metastatic breast cancer response to chemoembolization with contrast agent enhanced and diffusion-weighted MR imaging

PURPOSE: To assess the value of functional magnetic resonance (MR) imaging in the evaluation of early tumor response after transarterial chemoembolization (TACE) for metastatic breast cancer and to compare tumor response based on functional MR imaging versus traditional assessment based on iodized oil deposition, tumor size, and tumor enhancement. MATERIALS AND METHODS: For 14 patients with metastatic breast cancer, MR imaging studies before and after TACE were evaluated. Diffusion and contrast medium-enhanced MR imaging was performed on a 1.5-T unit. Parameters evaluated included change in tumor size, enhancement, and apparent diffusion coefficient (ADC) values. Median survival was also calculated in the entire cohort. RESULTS: A total number of 27 lesions were evaluated, with a mean diameter of 5.5 cm. Although mean tumor size decreased by 18% after treatment, no tumors met the Response Evaluation Criteria In Solid Tumors (RECIST) for complete response (ie, complete disappearance of target lesions) and only seven of 27 met RECIST for partial response (ie, >30% decrease in target lesion size). After treatment, decrease of tumor enhancement in the arterial (32%) and portal venous (39%) phases was statistically significant (P < .0001). Mean tumor ADC increased by 27% (P < .0001) after TACE, whereas ADC remained unchanged in nontumorous liver, spleen, and kidney. Median survival was 25 months for the entire cohort. CONCLUSION: In patients with breast cancer and liver metastases who were treated with TACE, although changes in tumor size were small, significant early changes in the treated lesions occurred on contrast medium-enhanced and functional MR imaging. These include decrease in tumor enhancement and increase in tumor ADC value, which suggest increasing tumor necrosis and cell death.     

Evaluation of treatment response of chemoembolization in hepatocellular carcinoma with diffusion-weighted imaging on 3.0-T MR imaging

PurposeTo assess the treatment response of hepatocellular carcinoma (HCC) after transarterial chemoembolization with diffusion-weighted imaging and dynamic contrast-enhanced magnetic resonance (MR) imaging with a 3-T system.Materials and MethodsBetween February 2010 and November 2010, 74 patients were treated with chemoembolization in our interventional radiology unit. Twenty-two patients (29%) who had liver MR imaging including diffusion and dynamic contrast-enhanced MR imaging on a 3-T system before and after transarterial chemoembolization were evaluated retrospectively. Tumor size, arterial enhancement, venous washout, and apparent diffusion coefficient (ADC) values of lesions, peritumoral parenchyma, normal liver parenchyma, and spleen were recorded before and after treatment. The significance of differences between ADC values of responding and nonresponding lesions was calculated.ResultsThe study included 77 HCC lesions (mean diameter, 31.4 mm) in 20 patients. There was no significant reduction in mean tumor diameter after treatment. Reduction in tumor enhancement in the arterial phase was statistically significant (P = .01). Tumor ADC value increased from 1.10 × 10^?3 mm²/s to 1.27 × 10^?3 mm²/s after treatment (P < .01), whereas the ADC values for liver and spleen remained unchanged. ADC values from cellular parts of the tumor and necrotic areas also increased after treatment. However, pretreatment ADC values were not reliable to identify responding lesions according to the results of receiver operating characteristic analysis.ConclusionsAfter transarterial chemoembolization, responding HCC lesions exhibited decreases in arterial enhancement and increases in ADC values in cellular and necrotic areas. Pretreatment ADC values were not predictive of response to chemoembolization.     

Diffusion-weighted MR imaging in monitoring the effect of a vascular targeting agent on rhabdomyosarcoma in rats

PURPOSE: To evaluate diffusion-weighted magnetic resonance (MR) imaging for monitoring tumor response in rats after administration of combretastatin A4 phosphate. MATERIALS AND METHODS: Study protocol was approved by local ethical committee for animal care and use. Rhabdomyosarcomas implanted subcutaneously in both flanks of 17 rats were evaluated with 1.5-T MR unit by using four-channel wrist coil. Transverse T2-weighted fast spin-echo sequences, T1-weighted spin-echo sequences before and after gadodiamide administration, and transverse echo-planar diffusion-weighted MR examinations were performed before, 1 and 6 hours, and 2 and 9 days after intraperitoneal injection of vascular targeting agent (combretastatin A4 phosphate, 25 mg/kg). Apparent diffusion coefficient (ADC) was automatically calculated from diffusion-weighted MR imaging findings. These findings were compared with histopathologic results at each time point. For statistical analysis, paired Student t tests with Bonferroni correction for multiple testing were used. RESULTS: T1-weighted images before combretastatin administration showed enhancement of solid tumor tissue but not of central necrosis. At 1 and 6 hours after combretastatin injection, enhancement of solid tissue disappeared almost completely, with exception of small peripheral rim. At 2 and 9 days after combretastatin injection, enhancement progressively reappeared in tumor periphery. ADC, however, showed decrease early after combretastatin injection ([1.26 +/- 0.16]x 10(-3) mm2/sec before, [1.18 +/- 0.17]x 10(-3) mm2/sec 1 hour after [P=.0005] and [1.08 +/- 0.14]x 10(-3) mm(2)/sec 6 hours after [P=.0007] combretastatin A4 phosphate injection), histologically corresponding to vessel congestion and vascular shutdown in periphery but no necrosis. An increase of ADC ([1.79 +/- 0.13]x 10(-3) mm2/sec) (P <.0001) 2 days after combretastatin A4 phosphate injection was paralleled by progressive histologic necrosis. A significant (P <.0001) decrease in ADC 9 days after treatment ([1.41 +/- 0.15]x 10(-3) mm2/sec) corresponded to tumor regrowth. CONCLUSION: In addition to basic relaxation-weighted MR imaging and postgadolinium T1-weighted MR imaging to enable prompt detection of vascular shutdown, diffusion-weighted MR imaging was used to discriminate between nonperfused but viable and necrotic tumor tissues for early monitoring of therapeutic effects of vascular targeting agent.     

动态弥散加权成像对HCC的TACE术疗效评价的临床应用

目的 探讨动态弥散加权成像对HCC的TACE术疗效评价的临床应用价值.方法 对确诊为HCC的46例患者在TACE治疗前1～3天、6h、24h、1个月、3个月采用平扫T1WI、FST2 WI、DWI扫描,术前诊断及术后1～3个月复查均行FST1WI动态增强扫描,DWI序列中弥散梯度因子（b值）分别取600、800、1 000s/mm2,测量ADC值,并与血管造影对比.结果 肿瘤的ADC值在TACE术后较术前升高,术前与术后1个月平均ADC值比较,差异有统计学意义.疗效良好的癌灶术后6h ADC值明显减低,术后24h至术后1、3个月,ADC值呈上升趋势;疗效中等的癌灶术后6h ADC值不均匀减低,术后24h始至术后1、3个月ADC值呈不均匀上升趋势;疗效差的癌灶术后6h ADC值无明显变化,术后24h始至术后1、3个月ADC值呈不均匀轻度降低.结论 动态DWI对HCC的TACE术疗效评估有重要的临床应用价值.     

Evaluating local hepatocellular carcinoma recurrence post‐transcatheter arterial chemoembolization: Is diffusion‐weighted MRI reliable as an indicator?

PURPOSE: To evaluate the detectability of local hepatocellular carcinoma (HCC) recurrence after transcatheter arterial chemoembolization (TACE) by diffusion-weighted MR imaging in correlation with those of gadolinium-enhanced MR imaging. MATERIALS AND METHODS: Respiratory-triggered diffusion-weighted MR images (b factor, 500 s/mm(2); number of averaging, six were obtained in 25 patients with 39 HCCs. Two independent radiologists evaluated diffusion-weighted MR images, gadolinium-enhanced MR images after TACE, and assigned confidence levels for postoperative HCC recurrence. Apparent diffusion coefficients (ADCs) in HCCs were also measured. Sensitivities and specificities were compared using an extension of the McNemar test. Observer performance was also determined by ROC curve analysis. RESULTS: Local recurrences in 14 HCCs and complete tumor necrosis in 25 HCCs after TACE were determined. Sensitivity for the detection of local HCC recurrence was higher on gadolinium-enhanced MR imaging (82%) than on diffusion-weighted MR imaging (60.7%) for the two readers in combination and separately (P < 0.05). Specificities were comparably high for both sequences. Az values were higher for gadolinium-enhanced MR images (0.92) than for diffusion-weighted MR images (0.74) for readers in combination and separately (P < 0.05). Mean ADC values showed an increase after TACE (P < 0.001). CONCLUSION: Diffusion-weighted MR imaging was not found to be a reliable predictor of local HCC recurrence after TACE as compared with gadolinium-enhanced MR imaging.     

Uterine fibroids: diffusion-weighted MR imaging for monitoring therapy with focused ultrasound surgery--preliminary study

PURPOSE: To prospectively determine the feasibility of using diffusion-weighted (DW) imaging and apparent diffusion coefficient (ADC) mapping before (baseline) and after treatment and at 6-month follow-up to monitor magnetic resonance (MR) image-guided focused ultrasound surgical ablation of uterine fibroids. MATERIALS AND METHODS: Informed consent was obtained from patients before treatment with our study protocol, as approved by the institutional review board, and the study complied with the Health Insurance Portability and Accountability Act. Fourteen patients (mean age, 46 years +/- 5 [standard deviation]) who underwent DW imaging were enrolled in this study, and 12 of 14 completed the inclusive MR examination with DW imaging at 6-month follow-up. Treatment was performed by one radiologist with a modified MR image-guided focused ultrasound surgical system coupled with a 1.5-T MR imager. Pre- and posttreatment and 6-month follow-up MR images were obtained by using phase-sensitive T1-weighted fast spoiled gradient-recalled acquisition, T1-weighted contrast material-enhanced, and DW imaging sequences. Total treatment time was 1-3 hours. Trace ADC maps were constructed for quantitative analysis. Regions of interest localized to areas of hyperintensity on DW images were drawn on postcontrast images, and quantitative statistics were obtained from treated and nontreated uterine tissue before and after treatment and at 6-month follow-up. Statistical analysis was performed with analysis of variance. Differences with P < .05 were considered statistically significant. RESULTS: T1-weighted contrast-enhancing fibroids selected for treatment had no hyperintense or hypointense signal intensity changes on the DW images or ADC maps before treatment. Considerably increased signal intensity changes that were localized within the treated areas were noted on DW images. Mean baseline ADC value in fibroids was 1504 mm(-6)/sec2 +/- 290. Posttreatment ADC values for nontreated fibroid tissue (1685 mm(-6)/sec2 +/- 468) differed from posttreatment ADC values for fibroid tissue (1078 mm(-6)/sec2 +/- 293) (P = .001). A significant difference (P < .001) between ADC values for treated (1905 mm(-6)/sec2 +/- 446) and nontreated (1437 mm(-6)/sec2 +/- 270) fibroid tissue at 6-month follow-up was observed. CONCLUSION: DW imaging and ADC mapping are feasible for identification of ablated tissue after focused ultrasound treatment of uterine fibroids.     

Pituitary macroadenomas: preoperative evaluation of consistency with diffusion-weighted MR imaging--initial experience

PURPOSE: To prospectively evaluate use of diffusion-weighted (DW) magnetic resonance (MR) images and apparent diffusion coefficient (ADC) maps for determination of the consistency of macroadenomas. MATERIALS AND METHODS: The study protocol was approved by the institutional ethics committee, and informed consent was obtained from all patients. Twenty-two patients with pituitary macroadenoma (10 men, 12 women; mean age, 54 years +/- 17.09 [standard deviation]; range, 21-75 years) were examined. All patients underwent MR examination, which included T1-weighted spin-echo and T2-weighted turbo spin-echo DW imaging with ADC mapping and contrast material-enhanced T1-weighted spin-echo imaging. Regions of interest (ROIs) were drawn in the macroadenomas and in normal white matter on DW images, ADC maps, and conventional MR images. Consistency of macroadenomas was evaluated at surgery and was classified as soft, intermediate, or hard. Histologic examination was performed on surgical specimens of macroadenomas. Mean ADC values, signal intensity (SI) ratios of tumor to white matter within ROIs on conventional and DW MR images, and degree of enhancement were compared with tumor consistency and with percentage of collagen content at histologic examination by using analysis of variance for linear trend. RESULTS: The mean value of ADC in the soft group was (0.663 +/- 0.109) x 10(-3) mm(2)/sec; in the intermediate group, (0.842 +/- 0.081) x 10(-3) mm(2)/sec; and in the hard group, (1.363 +/- 0.259) x 10(-3) mm(2)/sec. Statistical analysis revealed a significant correlation between tumor consistency and ADC values, DW image SI ratios, T2-weighted image SI ratios, and percentage of collagen content (P < .001, analysis of variance). No other statistically significant correlations were found. CONCLUSION: Findings in this study suggest that DW MR images with ADC maps can provide information about the consistency of macroadenomas.     

Effect of vascular targeting agent in rat tumor model: dynamic contrast-enhanced versus diffusion-weighted MR imaging

PURPOSE: To compare dynamic contrast material-enhanced magnetic resonance (MR) imaging and diffusion-weighted MR imaging for noninvasive evaluation of early and late effects of a vascular targeting agent in a rat tumor model. MATERIALS AND METHODS: The study protocol was approved by the local ethics committee for animal care and use. Thirteen rats with one rhabdomyosarcoma in each flank (26 tumors) underwent dynamic contrast-enhanced imaging and diffusion-weighted echo-planar imaging in a 1.5-T MR unit before intraperitoneal injection of combretastatin A4 phosphate and at early (1 and 6 hours) and later (2 and 9 days) follow-up examinations after the injection. Histopathologic examination was performed at each time point. The apparent diffusion coefficient (ADC) of each tumor was calculated separately on the basis of diffusion-weighted images obtained with low b gradient values (ADC(low); b = 0, 50, and 100 sec/mm(2)) and high b gradient values (ADC(high); b = 500, 750, and 1000 sec/mm(2)). The difference between ADC(low) and ADC(high) was used as a surrogate measure of tissue perfusion (ADC(low) - ADC(high) = ADC(perf)). From the dynamic contrast-enhanced MR images, the volume transfer constant k and the initial slope of the contrast enhancement-time curve were calculated. For statistical analyses, a paired two-tailed Student t test and linear regression analysis were used. RESULTS: Early after administration of combretastatin, all perfusion-related parameters (k, initial slope, and ADC(perf)) decreased significantly (P < .001); at 9 days after combretastatin administration, they increased significantly (P < .001). Changes in ADC(perf) were correlated with changes in k (R(2) = 0.46, P < .001) and the initial slope (R(2) = 0.67, P < .001). CONCLUSION: Both dynamic contrast-enhanced MR imaging and diffusion-weighted MR imaging allow monitoring of perfusion changes induced by vascular targeting agents in tumors. Diffusion-weighted imaging provides additional information about intratumoral cell viability versus necrosis after administration of combretastatin.     

Diffusion-weighted MR: therapeutic evaluation after chemoembolization of VX-2 carcinoma implanted in rabbit liver

RATIONALE AND OBJECTIVES: The study goal was to evaluate the ability of diffusion-weighted imaging (DWI) in assessing the viability of rabbit liver VX-2 tumor after transcatheter arterial chemoembolization (TACE). MATERIALS AND METHODS: VX-2 tumors were grown in the livers of 19 rabbits, and chemoembolization was performed. MR imaging was acquired 1 week after TACE. The rabbits were killed for histologic investigation immediately after MR imaging, and the proportion of viable tumor was calculated based on histopathologic examination. Apparent diffusion coefficient (ADC) values were measured in viable and necrotic tumor portion, and were compared using the paired Student's t test. RESULTS: Viable tumors were absent (n = 3), less than 5% (n = 6), and 5% or more (n = 10) at pathology examination. On DWI, three tumors with no viable portion were interpreted as having no viable portion, but three of six tumors with a viable portion of less than 5% were considered as having no viable portion. The mean ADC values of necrotic and viable tumor were 1.653 +/- 0.126 mm(2)/sec and 0.883 +/- 0.407 mm(2)/sec (b = 1000 sec/mm(2)), respectively, and the ADC values of necrotic tumors were significantly greater than those in viable tumors (p < .01). CONCLUSION: Although DWI is a useful tool for assessing tumor viability, viable tumor may not be detected on DWI when it is too small.     

Diffusion-weighted MR imaging of intracerebral masses: comparison with conventional MR imaging and histologic findings

BACKGROUND AND PURPOSE: The purposes of this study were to find the role of diffusion-weighted MR imaging in characterizing intracerebral masses and to find a correlation, if any, between the different parameters of diffusion-weighted imaging and histologic analysis of tumors. The usefulness of diffusion-weighted imaging and apparent diffusion coefficient (ADC) maps in tumor delineation was evaluated. Contrast with white matter and ADC values for tumor components with available histology were also evaluated. METHODS: Twenty patients with clinical and routine MR imaging/CT evidence of intracerebral neoplasm were examined with routine MR imaging and echo-planar diffusion-weighted imaging. The routine MR imaging included at least the axial T2-weighted fast spin-echo and axial T1-weighted spin-echo sequences before and after contrast enhancement. The diffusion-weighted imaging included an echo-planar spin-echo sequence with three b values (0, 300, and 1200 s/mm(2)), sensitizing gradient in the z direction, and calculated ADC maps. The visual comparison of routine MR images with diffusion-weighted images for tumor delineation was performed as was the statistical analysis of quantitative diffusion-weighted imaging parameters with histologic evaluation. RESULTS: For tumors, the diffusion-weighted images and ADC maps of gliomas were less useful than the T2-weighted spin-echo and contrast-enhanced T1-weighted spin-echo images in definition of tumor boundaries. Additionally, in six cases of gliomas, neither T2-weighted spin-echo nor diffusion-weighted images were able to show a boundary between tumor and edema, which was present on contrast-enhanced T1-weighted and/or perfusion echo-planar images. The ADC values of solid gliomas, metastases, and meningioma were in the same range. In two cases of lymphomas, there was a good contrast with white matter, with strongly reduced ADC values. For infection, the highest contrast on diffusion-weighted images and lowest ADC values were observed in association with inflammatory granuloma and abscess. CONCLUSION: Contrary to the findings of previous studies, we found no clear advantage of diffusion-weighted echo-planar imaging in the evaluation of tumor extension. The contrast between gliomas, metastases, meningioma, and white matter was generally lower on diffusion-weighted images and ADC maps compared with conventional MR imaging. Unlike gliomas, the two cases of lymphomas showed hyperintense signal on diffusion-weighted images whereas the case of cerebral abscess showed the highest contrast on diffusion-weighted images with very low ADC values. Further study is required to find out whether this may be useful in the differentiation of gliomas and metastasis from lymphoma and abscess.     

Multiple sclerosis: diffusion tensor MR imaging for evaluation of normal-appearing white matter

PURPOSE: To determine whether the normal-appearing white matter (NAWM) regions surrounding and remote from multiple sclerosis (MS) plaques have abnormal diffusional anisotropy and to compare anisotropy maps with apparent diffusion coefficient (ADC) maps for sensitivity in the detection of white matter (WM) abnormalities. MATERIALS AND METHODS: Conventional and diffusion tensor magnetic resonance (MR) imaging examinations were performed in 26 patients with MS and in 26 age-matched control subjects. Fractional anisotropy (FA) and ADC maps were generated and coregistered with T2-weighted MR images. Uniform regions of interest were placed on plaques, periplaque white matter (PWM) regions, NAWM regions in the contralateral side of the brain, and WM regions in control subjects to obtain FA and ADC values, which were compared across the WM regions. RESULTS: The mean FA was 0.280 for plaques, 0.383 for PWM, 0.493 for NAWM, and 0.537 for control subject WM. The mean ADC was 1.025 x 10(-3) mm(2)/sec for plaques, 0.786 x 10(-3) mm(2)/sec for PWM, 0.739 x 10(-3) mm(2)/sec for NAWM, and 0.726 x 10(-3) mm(2)/sec for control subject WM. Significant differences in anisotropy and ADC values were observed among all WM regions (P <.001 for all comparisons, except ADC in NAWM vs control subject WM [P =.018]). CONCLUSION: The anisotropy and ADC values were abnormal in all WM regions in the patients with MS and were worse in the periplaque regions than in the distant regions. Diffusion tensor MR imaging may be more accurate than T2-weighted MR imaging for assessment of disease burden.     

Osteosarcoma: preliminary results of in vivo assessment of tumor necrosis after chemotherapy with diffusion- and perfusion-weighted magnetic resonance imaging

PURPOSE: We sought to evaluate diffusion and perfusion weighted 1.5 T magnetic resonance imaging (MRI) in detecting tumor necrosis with histologic correlation after preoperative chemotherapy. MATERIALS AND METHODS: Eight patients (ages 11-19 years) with histologic proven osteosarcoma of the limbs underwent T1- and fat-suppressed T2-weighted spin echo and diffusion-weighted EPI sequences (b value = 700) after 5 cycles of standard chemotherapy. Tumor volume and apparent diffusion coefficients (ADC) were calculated. Tumor signal intensities were measured in dynamic contrast enhanced T1-weighted fast gradient echo-sequences obtained every 3 seconds after an intravenous injection of gadolinium-DTPA. Perfusion parameters of first-pass tracing of contrast medium (time-to-peak, slope of contrast enhancement curve) were calculated, and perfusion maps were established. After MRI, all patients underwent limb resection, and the specimens were investigated macroscopically and histologically. The degree of tumor necrosis was assessed using the histologic Salzer-Kuntschik classification (grades 1-6) after chemotherapy. RESULTS: Necrotic areas, which were confirmed by macroscopic/histologic examination, showed ADC values up to 2.7 (mean, 2.3 +/- 0.2). Viable tumor areas revealed lower apparent diffusion coefficients (mean, 0.8 +/- 0.3). The differences in ADC between viable and necrotic tumor were highly significant (paired t test; P = 0.01). Slopes of necrotic areas ranged from 0.1 up to 5.2%/min (mean, 1.5%/min) and those of viable tumor areas from 2.8 to 31.5%/min (mean, 16.1%/min). The time-to-peak-values (TTPs) ranged from 40 to 210 seconds (mean, 131 seconds, SD 60 seconds) in necrotic tumors and from 30 to 96 seconds (mean, 55 seconds, SD 21) in viable areas of sarcomas. The differences in slope and TTP between viable and necrotic tumor were highly significant. In necrotic areas, the linear correlation between slope (%/min) and ADC (mm/s) and between TTP (s) and ADC were weak, respectively. CONCLUSION: Both dynamic contrast-enhanced MRI and diffusion-weighted MRI permit recognition of tumor necrosis induced by chemotherapy in osteosarcomas. We hypothesized that diffusion-weighted imaging is correlated directly with tumor necrosis. Perfusion-weighted imaging is correlated with microvessel density, vascular permeability, local blood volume, and flow. Therefore, perfusion weighed MRI depicts areas of tumor cell necrosis indirectly.     

Evaluation of therapeutic effectiveness of transarterial chemoembolization for hepatocellular carcinoma: correlation of dynamic susceptibility contrast-enhanced echoplanar imaging and hepatic angiography

The objective of this study was to evaluate the therapeutic effectiveness of transarterial chemoembolization (TACE) for hepatocellular carcinoma (HCC) with dynamic susceptibility contrast-enhanced magnetic resonance imaging (DSC-MRI). Seventeen patients with histopathologically proven HCC were included in this study. All patients underwent MR examinations with conventional T1- and T2-weighted images, gadolinium-enhanced images, and DSC-MRI before TACE treatment. Hepatic blood volume (HBV) maps were reconstructed from the time-intensity curves. The same MRI sequences and techniques were repeated 24 h and 6 weeks after TACE. Serial changes in tumor perfusion on HBV maps were correlated with vascularity in hepatic angiography. All tumors were hypointense on T1-weighted images and hyperintense on T2-weighted images. Heterogeneous enhancement was observed in all tumors before and immediately after TACE. Hyperperfusion was noted in most of the tumors on HBV map before TACE and moderate to marked hypoperfusion following TACE. The degree of tumor perfusion on HBV map correlated well with the vascularity in angiography. In conclusion, the noninvasive nature of DSC-MRI is useful to evaluate the effectiveness of TACE. Invasive procedures, such as angiography, are seldom necessary.     

扩散加权序列动态评估原发性肝癌疗效的应用价值

目的:探讨扩散加权序列动态评估原发性肝癌疗效的价值.方法:对38例行手术、介入、伽玛刀、射频等治疗的原发性肝癌患者行常规MRI、动态增强及DWI序列(b=0、200、500、800 s/mm2)扫描,测量癌性灶的ADC值,术后以病理、血中甲胎蛋白量、血管造影及碘油沉积范围等指标将治疗疗效分为三组(好、中、差),进行肝癌...     

弥散成像在肝细胞肝癌及TACE治疗后的应用

目的：探讨磁共振弥散加权成像（DWI）在肝细胞肝癌（HCC）的应用及介入治疗前后监测肿瘤变化的价值。材料和方法：11例确诊HCC进行屏气状态下多个弥散梯度因子（b值=200s／mm^2、400s／mm^2、600s／mm^2、1000s／mm^2、2000s／mm^2）的弥散加权成像，选用自旋平面回波（SE—EPI）序列（TR／TE=2000／46．7—78．1ms，层厚：8mm，层距：2mm），对肿瘤层面的瘤灶、邻近未累及肝实质区与背景噪声的信号强度（SI）进行测量，并观察经皮插管肝动脉化疗栓塞（TACE）术治疗前后肿瘤表观弥散系数（ADC）值的变化趋势。结果：随着b值的增加，肝脏DWI图像质量呈下降趋势。低b值DWI图像清晰但存在较明显的T2透过效应；高b值时则图像模糊信号接近于背景噪声，当b值取600s／mm^2时，肝癌肿瘤与肝实质之间存在着最佳对比度。介入治疗后肿瘤的ADC值普遍有所增大，其中高b值时两者之间存在统计学差异。结论：屏气状态下DWI在肝脏肿瘤的应用完全可行，ADC值在介入治疗前后的变化趋势可能具有监测肿瘤内部坏死情况的价值。     

Peritumoral brain regions in gliomas and meningiomas: investigation with isotropic diffusion-weighted MR imaging and diffusion-tensor MR imaging

PURPOSE: To retrospectively measure the diffusion-weighted (DW) imaging characteristics of peritumoral hyperintense white matter (WM) and peritumoral normal-appearing WM, as seen on T2-weighted magnetic resonance (MR) images of infiltrative high-grade gliomas and meningiomas. MATERIALS AND METHODS: Seventeen patients with biopsy-proved glioma and nine patients with imaging findings consistent with meningioma and an adjacent hyperintense region on T2-weighted MR images were examined with DW and diffusion-tensor MR imaging. Apparent diffusion coefficients (ADCs) were measured on maps generated from isotropic DW images of enhancing tumor, hyperintense regions adjacent to enhancing tumor, normal-appearing WM adjacent to hyperintense regions, and analogous locations in the contralateral WM corresponding to these areas. Fractional anisotropy (FA) was measured in similar locations on maps generated from diffusion-tensor imaging data. Changes in ADC and FA in each type of tissue were compared across tumor types by using a two-sample t test. P <.05 indicated statistical significance. RESULTS: Mean ADCs in peritumoral hyperintense regions were 1.309 x 10(-3) mm2/sec (mean percentage of 181% of normal WM) for gliomas and 1.427 x 10(-3) mm2/sec (192% of normal value) for meningiomas (no significant difference). Mean ADCs in peritumoral normal-appearing WM were 0.723 x 10(-3) mm2/sec (106% of normal value) for gliomas and 0.743 x 10(-3) mm2/sec (102% of normal value) for meningiomas (no significant difference). Mean FA values in peritumoral hyperintense regions were 0.178 (43% of normal WM value) for gliomas and 0.224 (65% of normal value) for meningiomas (P =.05). Mean FA values for peritumoral normal-appearing WM were 0.375 (83% of normal value) for gliomas and 0.404 (100% of normal value) for meningiomas (P =.01). CONCLUSION: The difference in FA decreases in peritumoral normal-appearing WM between gliomas and meningiomas was significant, and the difference in FA decreases in peritumoral hyperintense regions between these tumors approached but did not reach significance. These findings may indicate a role for diffusion MR imaging in the detection of tumoral infiltration that is not visible on conventional MR images.     

Assessment of tumor response on MR imaging after locoregional therapy

Assessment of tumor response after locoregional therapies is important in determining treatment success and in guiding future therapy. Magnetic resonance imaging plays an important role in evaluating treatment response to new therapies directed toward hepatic lesion treatment. The traditional and accepted criteria to determine tumor response in oncology, namely the Response Evaluation Criteria in Solid Tumors (RECIST) and the European Association for the Study of the Liver (EASL) criteria, use decrease in tumor size and lesion enhancement as an indicator of successful therapy. A more recent evaluation method is the Apparent Diffusion Coefficient (ADC) measured by diffusion-weighted MR imaging. Diffusion-weighted MR imaging and ADC values map the thermally induced motion of water molecules in tissues and thereby are able to provide insight into tumor microstructure. In this article we discuss the role of MR imaging in assessing treatment response after various locoregional therapies. We describe the role of tumor size and lesion enhancement as well as ADC mapping. We also discuss the magnetic resonance imaging findings after radiofrequency ablation (RFA), transarterial chemoembolization (TACE) and radioembolization.     

MR imaging perfusion mismatch: a technique to verify successful targeting of liver tumors during transcatheter arterial chemoembolization

PURPOSE: To evaluate the combined use of transcatheter intraarterial perfusion (TRIP) magnetic resonance (MR) imaging and dynamic contrast-enhanced MR imaging to determine complete tumor targeting during transcatheter arterial chemoembolization (TACE) when performed within an integrated MR imaging-interventional radiology (IR) angiography suite. MATERIALS AND METHODS: Between October 2006 and March 2007, eight consecutive patients with unresectable hepatocellular carcinoma (HCC) successfully underwent TACE in a combined MR imaging-IR suite. All patients were male, with a mean age of 59 years (range, 41-71 years). Tumor enhancement on TRIP MR images before and after TACE were qualitatively compared with dynamic contrast-enhanced MR images obtained after TACE. The authors computed the prevalence of perfusion mismatch. The presence of a perfusion mismatch was judged in a binary fashion. RESULTS: A perfusion match, confirming complete tumor targeting, occurred in six of the eight patients (75%). There was a perfusion mismatch in two patients (25%). Subsequent interrogation showed that the underlying cause of the mismatch was secondary to an unexpected collateral vessel in the first patient and watershed location of the tumor in the second patient. CONCLUSIONS: Performing TACE in an MR imaging-IR suite can facilitate complete tumor targeting. By comparing perfusion images from TRIP and contrast-enhanced MR sequences, the operator gains confidence and can potentially obtain more selective catheter placement during TACE.     

MRI对肝脏上皮样血管平滑肌脂肪瘤与肝细胞肝癌鉴别诊断的价值

目的 比较动态增强磁共振成像(DCE-MRI)和扩散加权成像(DWI)对肝脏上皮样血管平滑肌脂肪瘤(HEAML)和肝细胞肝癌(HCC)鉴别诊断的价值.方法 回顾性分析经手术病理证实的15例HEAML患者和50例HCC患者MR资料,术前均行DCE-MRI和 DWl扫描.观察记录2组病灶的大小、部位、边界、平扫信号特点(包括T1WI、T2WI及DWI),增强模式、中心血管影、有无早期静脉引流、"假包膜",计算表观扩散系数(ADC)值,并对2组病例上述MR征象进行统计学比较分析.结果 所有病例均为单发病灶.15个HEAML病灶8个显示早期静脉引流、11个显示中心血管征、6个有假包膜、5个为"快进快出"强化模式、10个为"快进慢出"强化模式,ADC平均值为(1.15±0.31)×10-3 mm2/s;50个HCC病灶中,6个显示早期静脉引流、5个显示中心血管征、45个有"假包膜"、29个为"快进快出"强化模式,ADC平均值为(1.23±0.29)×10-3 mm2/s.两者在病灶中心血管影、早期静脉引流、"假包膜"征方面差异有统计学意义(P<0.05),在病灶部位、大小、边界、平扫信号特点(包括T1WI,T2WI及DWI)、强化模式、ADC值方面差异无统计学意义(P>0.05).结论 DCE-MRI较DWI更有助于鉴别HEAML和HCC.