Assessment of therapeutic response in brain tuberculomas using serial dynamic contrast-enhanced MRI

AIM: To assess the most useful dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) index in the evaluation of the therapeutic response in brain tuberculoma (BT) patients. SUBJECTS AND METHODS: Twenty-three patients with 25 BT lesions were serially evaluated using DCE MRI. All lesions were classified into two groups: group I (n=15) included patients who showed clinical, as well as imaging, improvement; and group II (n=10) included patients with either clinical or radiological deterioration. The group I and group II lesions were examined for up to 12 months at 4 monthly intervals. However, the lesions in five patients of group II were excised following clinical deterioration after 4 months of therapy. The perfusion indices, i.e., relative cerebral blood volume (rCBV), relative cerebral blood flow (rCBF), permeability (k(trans)), and leakage (v(e)), were quantified at each time point. The cellular, necrotic, and total volumes of lesion, together with the oedema volume, were also calculated. RESULTS: All patients in group I and three in group II showed a significant decrease in all perfusion indices, together with the oedema volume, after 1 year. In these three patients in group II, increase in rCBV was associated with increased cellular volume fraction whereas the k(trans), v(e), and oedema volume decreased significantly after 4 months. In five patients in group II who underwent excision of the lesion after 4 months of therapy due to clinical deterioration, the decrease in rCBV was associated with significant increase in k(trans) and oedema volume without any significant change in lesion volume. The rCBV correlated significantly with the cellular volume, whereas k(trans) showed a significant correlation with the v(e) and oedema volume at each time point. CONCLUSION: In BT, changes in k(trans) and oedema volume are associated with a therapeutic response at 4 months, even when there is a paradoxical increase in the lesion volume.     

USPIO-enhanced MRI of highly invasive and highly metastasizing transplanted human squamous cell carcinoma: an experimental study

Objective

The aim of this study was to investigate the signal intensity characteristics of highly invasive and highly metastasizing transplanted human squamous cell carcinoma using ultra-small super-paramagnetic iron oxide (USPIO)-enhanced MRI and to correlate them with USPIO distribution to tumour components revealed by histological examination.

Methods

13 nude mice with transplanted human squamous cell carcinoma in the oral cavity were imaged before and 24 hours after intravenous administration of USPIO. The difference in signal intensity between pre-contrast and post-contrast MR images was visually evaluated. For quantitative analysis, signal intensity within a region of interest was measured. Histological findings were correlated with MR findings. The approximate USPIO concentration was evaluated using USPIO phantoms.

Results

Seven tumours had an area showing signal intensity increase on post-contrast T₁ weighted images. Histopathologically, six of those tumours contained a small amount of iron particles in the stroma. The USPIO concentration was presumed low. Two tumours had an area showing signal intensity decrease on post-contrast T₁ and T₂ weighted images. The areas had a large amount of iron particles in the stroma and the USPIO concentration was presumed high. There was a minimal amount of iron particles in tumour parenchymal cells.

Conclusions

The amount of USPIO accumulation into tumour stroma was considered to affect MR signal intensity. A small amount increases T₁ weighted signal intensity, whereas a large amount decreases T₁ and T₂ weighted intensity. The USPIO accumulation into the tumour parenchyma was not thought to affect MR signal intensity.     

USPIO增强MRI应用于结直肠癌淋巴结微转移的研究进展

淋巴结微转移是早期结直肠癌根治术后复发、转移的可能原因,超小超顺磁性氧化铁(USPIO)磁共振增强淋巴结靶向成像技术可以用于检测淋巴结的微转移.从淋巴结靶向对比剂USPIO的结构和药代动力学、增强成像原理、MRI检查方法、影像分析和诊断标准以及不足等几个方面予以综述.     

Dynamic contrast-enhanced MRI of experimental spinal cord injury: in vivo serial studies.

The progression of experimental spinal cord injury (SCI) was followed with in vivo dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and neurobehavioral studies on postinjury days 0, 2, 4, 7, 10, 14, 17, 21, 28, 35, and 42. Gadopentate dimeglumine (Gd) was administered IV and postcontrast, T(1)-weighted, axial images were acquired repetitively for up to 60 min. Images were analyzed to determine the spatial and temporal evolution of the intensity enhancement. A statistical decision mechanism was developed to objectively detect the enhancement. Strong and rapid enhancement was observed at the epicenter of injury, indicating a significant compromise in blood spinal cord barrier. The enhanced regions in each slice were combined to estimate the area and volume of the lesion. On the day of injury, around 85% of the total cord area at the epicenter showed enhancement within the first 15 min of Gd administration. At the same time, the enhanced volumes attained nearly 40% of the total cord volume and extended axially over 8 mm along the cord. These quantities decreased steadily with time, with a concomitant improvement in the motor functions. The volume of enhancement correlated highly with the neurobehavioral tests (r = -0.87). DCE-MRIs revealed small hyperintense regions distributed inside white matter about two weeks postinjury. Based on histology, these enhancements appear to represent new vessels with "leaky endothelium." Magn Reson Med 45:614-622, 2001.     

Temporal dependence of in vivo USPIO-enhanced MRI signal changes in human carotid atheromatous plaques

Introduction  Ultrasmall superparamagnetic iron oxide (USPIO)-enhanced MRI has been shown to be a useful modality to image activated macrophages in vivo, which are principally responsible for plaque inflammation. This study determined the optimum imaging time-window to detect maximal signal change post-USPIO infusion using T₁-weighted (T₁w), T₂*-weighted (T₂*w) and quantitative T₂* (qT₂*) imaging. Methods  Six patients with an asymptomatic carotid stenosis underwent high resolution T₁w, T₂*w and qT₂* MR imaging of their carotid arteries at 1.5 T. Imaging was performed before and at 24, 36, 48, 72 and 96 h after USPIO (Sinerem™, Guerbet, France) infusion. Each slice showing atherosclerotic plaque was manually segmented into quadrants and signal changes in each quadrant were fitted to an exponential power function to model the optimum time for post-infusion imaging. Results  The power function determining the mean time to convergence for all patients was 46, 41 and 39 h for the T₁w, T₂*w and qT₂* sequences, respectively. When modelling each patient individually, 90% of the maximum signal intensity change was observed at 36 h for three, four and six patients on T₁w, T₂*w and qT₂*, respectively. The rates of signal change decrease after this period but signal change was still evident up to 96 h. Conclusion  This study showed that a suitable imaging window for T₁w, T₂*w and qT₂* signal changes post-USPIO infusion was between 36 and 48 h. Logistically, this would be convenient in bringing patients back for one post-contrast MRI, but validation is required in a larger cohort of patients. Sources of funding: GlaxoSmithKline and The Stroke Association     

Reversibility of experimental acute renal failure in rats: assessment with USPIO-enhanced MR imaging

The purpose of this study was to evaluate the potential reversibility of kidney lesions in an experimental model of acute renal failure using ultra-small particles of iron oxide (USPIO)-enhanced magnetic resonance (MR) imaging. This study was conducted in 21 uninephrectomized rats using a model of iodinated contrast media-induced renal failure. Thirteen rats received selective intraarterial renal administration of diatrizoate (370 mg/ml) and were compared with two control groups, including six animals injected with saline and two noninjected animals. MR imaging was performed 28 hours, 8 days, and 22 days after the procedure. Each MR session included axial and coronal T1- and coronal T2-weighted images before and after intravenous administration of 60 micromol Fe/kg of USPIO. The rats were sacrificed immediately after the last MR session for pathologic evaluation. MR images were qualitatively and quantitatively interpreted with respect to pathologic data, and differences were statistically studied. At day 22, histology showed 4 severely diseased kidneys with focal areas of necrosis, 5 mildly diseased kidneys with tubular vacuolization, and 12 normal kidneys. On quantitative data, a high correlation between the percentage of negative enhancement and histologic data was observed (P < 0.05). Qualitative interpretation showed a sensitivity and specificity of USPIO-enhanced T2-weighted MR images of 88% and 91%, respectively. Follow-up enhancement curves showed a constant increase of intrarenal USPIO negative enhancement in normal kidneys between day 1 and day 22, whereas all severely involved kidneys displayed higher USPIO negative enhancement at day 1 without significant changes over time until day 22. USPIO may be useful for in vivo follow-up of the reversibility of experimentally induced iodinated contrast media renal impairment in animals.     

Diagnostic performance of USPIO-enhanced MRI for lymph-node metastases in different body regions: A meta-analysis

Objectives

USPIO (ultrasmall superparamagnetic iron oxide contrast agent) MRI was a promising imaging modality in the detection of lymph-node metastases. And this meta-analysis is performed to compare the diagnostic accuracy of USPIO-enhanced MRI with non-enhanced MRI, USPIO-enhanced MRI in various body regions, and postcontrast alone for diagnosis of lymph-node metastases.

Methods

A comprehensive and systematic search was conducted in PubMed and EMBASE databases. After a systematic review of the studies, sensitivity, specificity, the Q* value and other measures of accuracy of USPIO-enhanced MRI in the diagnosis of lymph-node metastases were summarized. The overall test performance was based on summary receiver operating characteristic curves.

Results

Summary of ROC curve analysis for per-lymph-node data shows a pooled sensitivity of 0.90 (95% confidential interval [CI]: 0.88-0.91) and overall specificity of 0.96 (95% CI: 0.95-0.97) for USPIO-enhanced MRI, the Q* value for USPIO-enhanced MRI is 0.9195, diagnostic odds ratio (DOR) is 162.28 (95% CI: 91.82-286.81). Non-enhanced MRI had less overall sensitivity 0.39 (95% CI: 0.34-0.43) and specificity 0.90 (95% CI: 0.89-0.91), respectively, the Q* value for USPIO-enhanced MRI was 0.6321, DOR is 5.81 (95% CI: 3.64-9.82). Postcontrast MRI alone had sensitivity 0.85 (95% CI: 0.81-0.88) and specificity 0.93 (95% CI: 0.91-0.95), respectively, the Q* value for USPIO-enhanced MRI was 0.8976, DOR is 76.92 (95% CI: 34.21-172.93). There was significant heterogeneity for studies reporting enhanced MRI and non-enhanced MRI.

Conclusions

This meta-analysis has shown that USPIO-enhanced MRI offers higher diagnostic performance than conventional MRI, and is sensitive and specific for the detection of lymph-node metastases. Postcontrast images alone can equate diagnostic performance pre- and postcontrast MRI has achieved for lymph-node characterization. And the role of USPIO-enhanced MRI in clinical practice still needs to be investigated in future studies.     

Cortical laminar necrosis in brain infarcts: serial MRI

High-signal cortical lesions are observed on T1-weighted images in cases of brain infarct. Histological examination has demonstrated these to be "cortical laminar necrosis", without haemorrhage or calcification. We report serial MRI in this condition in 12 patients with brain infarcts. We looked at high-signal lesions on T1-weighted images, chronological changes in signal intensity and contrast enhancement. High-signal cortical lesions began to appear about 2 weeks after the ictus, were prominent at 1-2 months, then became less evident, but occasionally remained for up to 1.5 years. They gave high signal or were isointense on T2-weighted images and did not give low signal at any stage. Contrast enhancement of these lesions was prominent at 1-2 months, and less apparent from 3 months, but was seen up to 5 months.     

Marchiafava-Bignami disease: serial changes in corpus callosum on MRI

Summary Serial MRI findings of changes in corpus callosum lesions in two cases of Marchiafava-Bignami disease are presented. In both, MRI displayed diffuse swelling of the corpus callosum in the acute stage, thought to represent oedema and demyelination. In the chronic stage, in addition to atrophy of the corpus callosum with presumed focal necrosis, previously undescribed focal hypointensity on T2-weighted images, of unknown cause, was observed in the corpus callosum.This work was supported by a grant from the Korea Radiologic Research Fund (1992)     

高压氧对实验性腹膜粘连的防治作用(论著)

目的：探讨高压氧（ＨＢＯ）对实验性腹膜粘连的防治作用。方法：３６只Ｗｉｓｔａｒ大鼠采用创伤法复制实验性腹膜粘连动物模型，随机分为ＨＢＯ－Ａ组、ＨＢＯ－Ｂ组、ＨＢＯ－Ｃ组和对照组。ＨＢＯ－Ａ组和ＨＢＯ－Ｂ组于创伤后立即行ＨＢＯ治疗，分别治疗１０天和５天。ＨＢＯ－Ｃ组推迟５天才治疗，只治疗５天。创伤后１０天解剖所有大鼠，观察局部肠管色泽，并按腹膜粘连程度按级评分。结果：ＨＢＯ－Ａ组和ＨＢＯ－Ｂ组的腹膜粘连积分分别为１．２５±０．８９和１．６３±０．９２，显著低于对照组３．０８±０．７９（Ｐ＜０．０１），而ＨＢＯ－Ｃ组的腹膜粘连积分为２．８８±０．８３，与对照组相比无统计学差异（Ｐ＞０．０５）。结论：术后及时行ＨＢＯ治疗能防治实验性腹膜粘连。     

Monitoring therapeutic efficacy in breast carcinomas

The aim of imaging during and after neoadjuvant therapy is to document and quantify tumor response: has the tumor size been accurately measured? Certainly, the most exciting information for the oncologists is: can we identify good or nonresponders, and can we predict the pathological response early after the initiation of treatment? This review article will discuss the role and the performance of the different imaging modalities (mammography, ultrasound, magnetic resonance imaging and FDG-PET imaging) for evaluating this therapeutic response. It is important to emphasize that, at this time, clinical examination and conventional imaging (mammography and ultrasound) are the only methods recognized by the international criteria. Magnetic resonance imaging and FDG-PET imaging are very promising for predicting the response early after the initiation of neoadjuvant chemotherapy.     

Fetal MRI in experimental tracheal occlusion

Congenital diaphragmatic hernia (CDH) is associated with a high mortality, which is mainly due to pulmonary hypoplasia and secondary pulmonary hypertension. In severely affected fetuses, tracheal occlusion (TO) is performed prenatally to reverse pulmonary hypoplasia, because TO leads to accelerated lung growth. Prenatal imaging is important to identify fetuses with pulmonary hypoplasia, to diagnose high-risk fetuses who would benefit from TO, and to monitor the effect of TO after surgery. In fetal imaging, ultrasound (US) is the method of choice, because it is widely available, less expensive, and less time-consuming to perform than magnetic resonance imaging (MRI). However, there are some limitations for US in the evaluation of CDH fetuses. In those cases, MRI is helpful because of a better tissue contrast between liver and lung, which enables evaluation of liver herniation for the diagnosis of a high-risk fetus. MRI provides the ability to determine absolute lung volumes to detect lung hypoplasia. In fetal sheep with normal and hyperplastic lungs after TO, lung growth was assessed on the basis of cross-sectional US measurements, after initial lung volume determination by MRI. To monitor fetal lung growth after prenatal TO, both MRI and US seem to be useful methods.     

症状性缺血性脑卒中颈动脉斑块成分的 高分辨MRI分析

目的应用高分辨MRI(HRMRI)探讨颈动脉斑块不同成分在症状性缺血性脑卒中病人中的危险性。方法选取2016年1月—2017年6月于我院行超声检查发现存在颈动脉斑块的病人50例,其中女21例,男29例,年龄43~77岁,平均(61.62±7.96)岁。依据病人近3个月来是否发生过与患侧颈动脉相关的缺血性脑卒中临床症状分为有症状组(22例,存在斑块血管40支)及无症状组(28例,50支),所有病人行3.0 T HRMRI以评估颈动脉血管及斑块内成分。采用χ~2检验或t检验对2组病人的临床资料、斑块成分及血管管腔狭窄程度进行比较,采用logistic回归分析缺血性脑卒中病人症状的独立危险因素。结果检出存在斑块纤维帽破溃(FCR)的血管,症状组15支,检出率为37.5%,无症状组8支,检出率为16.0%,症状组FCR的检出率高于无症状组(P0.05)。检出斑块内出血(IPH)的血管,症状组21支,检出率为52.5%,无症状组15支,检出率为30.0%,症状组IPH的检出率高于无症状组(P0.05)。检出存在斑块钙化(CA)的血管,症状组15支,检出率为37.5%,无症状组13支,检出率为26.0%,2组间检出率差异无统计学意义(P0.05)。症状组管腔狭窄程度为57.64%±13.36%,无症状组为53.86%±11.19%,2组间管腔狭窄程度差异无统计学意义(t=1.460,P=0.148)。FCR在症状性缺血性脑卒中危险性最高(OR=3.012),IPH危险性次之(OR=2.478)。结论 HRMRI可以分析斑块内成分,而这些成分是缺血性脑卒中临床症状发生的危险因素,是斑块易损性的表现。     

MRI of hyperacute stroke in the AChA territory

The purpose of our study was to derive from the anatomical literature an easy-to-use map of the brain areas supplied by the anterior choroidal artery (AChA) and to assess the correspondence between damage within the putative AChA areas and clinical symptoms. A thorough review of the literature led to the recognition of 16 anatomical areas which could be delineated on routine diffusion-weighted MR images. A database of 138 consecutive ischemic stroke patients examined with MRI less than 6 h after symptoms onset was thereafter processed in a retrospective way. Patients presenting with at least one damaged AChA area were selected so as to assess the prevalence of AChA infarction and the clinical correlates of the condition. Fifteen patients (11%) had at least one damaged AChA area. Only two of them had pure AChA-restricted infarction. Contralateral hemiparesis and contralateral hemianesthesia were best predicted by lesions within the tail of the caudate nucleus with a sensitivity of 87% and 83%, respectively. Homonymous hemianopsia best correlated with lesions within the posterior limb of the internal capsule and within the retrolenticular part of the internal capsule, with a sensitivity of 100% and a specificity of 70% for both areas. We concluded that the clinical–radiological correlations did not match the neurophysiological standards, thereby highlighting the limitation of this study, which involved a cohort of acute stroke patients recruited from clinical practice and investigated the clinical impact of these brain lesions, even when documented with the most sensitive imaging modality.     

Diffusion- and perfusion-weighted MRI in therapeutic neurointerventional procedures

We describe three patients in whom we used MRI, including diffusion- and perfusion-weighted imaging (DWI, PWI) in conjunction with endovascular therapy. Two had intracranial aneurysms and one an arteriovenous malformation (AVM). The aneurysms were treated by coil embolisation or detachable balloons for proximal artery occlusion; the AVM was obliterated by intranidal glue injection. All patients had transient or permanent neurological deficits after treatment. The MRI techniques and interventional procedures are described and the DWI and PWI patterns found are correlated with the clinical features. We discuss how the information gained from MRI may increase our understanding of procedure-related complications and its potential impact on our therapeutic interventions, in order to prevent or limit the clinical consequences of such events. Received: 7 April 2000 Accepted: 19 December 2000     

MRI in primary bone tumors: therapeutic implications

The accuracy of preoperative MRI in detecting tumor extent has been evaluated in 35 patients with primary bone neoplasms; intra-osseous extent was measured on MR images and compared with macroslides of surgical specimens in 26 cases. An almost completely accurate prediction of tumor size was obtained with the combined employment of Spin-Echo (SE) and Short Inversion Time Inversion Recovery (STIR) sequences in the various tumors, with the exception of two Ewing's sarcomas. Changes in Signal Intensity (SI) and tumor morphology were identified in those cases which had undergone presurgical chemotherapy; the reduction in SI and in tumor size or the appearance of a more homogeneous signal was correlated with a positive response to cytotoxic therapy. MR imaging fully satisfies surgeon's preoperative requirements in the assessment of therapy-responding neoplasms as well as in local tumor staging in all types of neoplasms, with the exception of Ewing's sarcoma.     

Monitoring the therapeutic efficacy of CA4P in the rabbit VX2 liver tumor using dynamic contrast-enhanced MRI

PURPOSEThe present work aims to evaluate whether dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) can monitor the blocking effect of combretastatin-A4-phosphate (CA4P) on microvessels and assess the therapeutic efficacy.METHODSForty rabbits were implanted VX2 tumor specimens. Two weeks later, serial MRI (T1-weighted imaging, T2-weighted imaging, and DCE) were performed at 0 h, 4 h, 24 h, 3 days, and 7 days after CA4P (10 mg/kg) or saline treatment. The parameters of DCE (K^trans, K_ep, V_e and iAUC60) enhancement of tumor portions were measured. Then all tumor samples were stained to count microvessel density (MVD). Finally, two-way repeated measures ANOVA was used to analyze the difference between and within groups. Correlation between the DCE parameters and MVD was analyzed by using the Pearson correlation and Spearman rank correlation.RESULTSK^trans and iAUC60 values at 4 h after CA4P treatment were significantly lower than those in the control group (D-value: −0.133 min⁻¹, 95%CI: −0.169 to −0.097 min⁻¹, F= 59.109, p < 0.001 for K^trans; D-value: −10.533 mmol/s, 95%CI: −17.147 to −3.919 mmol/s, F= 11.110, and p = 0.003 for iAUC60). In the CA4P group, K^trans and iAUC60 reached the minimum values at 4 h, and both parameters showed significant difference between 4 h and other time points (all p < 0.01). Seven-day values of K^trans (r=0.532, p = 0.016 and r=0.681, p = 0.001, respectively) and iAUC60 (r=0.580, p = 0.007 and r=0.568, p = 0.009, respectively) showed correlation with MVD in both groups, while K_ep and V_e did not show correlation with MVD (p > 0.05).CONCLUSIONThe blocking effect of microvessels after CA4P treatment can be evaluated by DCE-MRI, and the parameters of quantitative K^trans and semi-quantitative iAUC60 can assess the change in tumor angiogenesis noninvasively.

Hepatocellular carcinoma (HCC) has the third highest mortality rate worldwide among cancers (1). Although the 5-year survival rate can reach up to 70% of HCC patients by surgical operation, only less than 30% are suitable for surgery. Transarterial chemoembolization (TACE) treated tumors can stimulate angiogenesis and require repeated treatment (2). As HCC is generally hypervascular, vascular targeting strategies can be used to improve the 5-year survival rate (3).There are two kinds of tumor vascular targeted agents (4): angiogenesis inhibitors (AIs) and vascular disrupting agents (VDAs). AIs can prevent the formation of new blood vessels by inhibiting angiogenesis. VDAs can damage the tumor endothelium directly, shutdown vascular development rapidly and selectively and cause tumor cell ischemia; tumor vascular shutdown occurs within 1 h of administration, and lasts for 24 hours (5, 6). Combretastatin A-4-phosphate (CA4P) is a new-style VDA that progressed into clinical trial stage (7–9).The vascular disrupting effects of VDAs can be assessed by microvessel density (MVD), which is the “gold standard” measurement to evaluate angiogenesis. However, the invasiveness of MVD measurement limits its use (10).During the development of targeted treatments, imaging plays an important role in monitoring the treatment efficacy against malignant tumors (11). Although change in tumor size may not be a reliable method to measure treatment efficacy, plenty of imaging sequences have been developed to overcome the drawbacks of traditional efficacy assessments by size measurement (12–14).DCE-MRI could reflect the microvascular structure and function indirectly, noninvasively and quantitatively, and it has been widely applied to predict and evaluate the treatment response (15). DCE-MRI is expected to be useful in evaluating early vascular disrupting efficacy after CA4P administration. But studies focusing on the changes of DCE parameters at different time points after CA4P administration in the VX2 rabbits have been scarce (16–18). The VX2 liver tumor is supplied by liver artery which is similar with high-grade human HCC, and can be used to simulate the microenvironment of human HCC (19).In this study, we aimed to investigate whether quantitative parameters in DCE-MRI can monitor the change in microvasculature of liver tumors at different time points after CA4P treatment.     

MRI of spontaneous spinal cord infarction: serial changes in gadolinium-DTPA enhancement

Summary Spinal cord infarcts are rare. We report serial MRI studies of a patient with a clinically diagnosed spontaneous spinal cord infarct. The usefulness of gadolinium diethylenetriaminepentaacetic acid-dimeglumine (Gd-DTPA) enhancement is also discussed. Serial MRI with Gd-DTPA is useful to diagnose the spinal cord infarction.