进展期卵巢癌:多参数MR成像显示治疗应答、转移和特殊效应

目的研究多参数MR成像在评价进展期卵巢癌对铂新辅助化疗反应和比较原发性卵巢肿物和转移性疾病两者间的成像参数。材料与方法在一项具有前瞻性控制的研究中评估了一些怀疑患有进展期卵巢癌的病人。研究伦理委员会同意,并具备书面同意书。采用一台3.0T的全身MR     

预测脑卒中的进展:MR磁敏感加权成像与MR灌注成像的比较研究

摘要目的与MR灌注加权成像(PWI)比较,探讨磁敏感加权成像(SWI)在预测脑卒中进展方面的作用。方法对一组(15例)发病24h内的非腔隙性缺血性脑卒中病人的回顾性分析中,我们使用Alberta卒中项目早期CT评分标准(Alberta Stroke Program Early CT Score,ASPECTS)比较了发病初期和发病至少5d后扩散加权成像(DWI)、SWI、PWI上病变的变化。     

Predicting stroke evolution: comparison of susceptibility-weighted MR imaging with MR perfusion

Objectives

To investigate the ability of susceptibility-weighted imaging (SWI) to predict stroke evolution in comparison with perfusion-weighted imaging (PWI).

Methods

In a retrospective analysis of 15 patients with non-lacunar ischaemic stroke studied no later than 24?h after symptom onset, we used the Alberta Stroke Program Early CT Score (ASPECTS) to compare lesions on initial diffusion-weighted images (DWI), SWI, PWI and follow-up studies obtained at least 5?days after symptom onset. The National Institutes of Health Stroke Scale scores at entry and stroke risk factors were documented. The clinical–DWI, SWI–DWI and PWI–DWI mismatches were calculated.

Results

SWI–DWI and mean transit time (MTT)–DWI mismatches were significantly associated with higher incidence of infarct growth (P?=?0.007 and 0.028) and had similar ability to predict stroke evolution (P?=?1.0). ASPECTS values on initial DWI, SWI and PWI were significantly correlated with those on follow-up studies (P?≤?0.026) but not associated with infarct growth. The SWI ASPECTS values were best correlated with MTT ones (ρ?=?0.8, P?Conclusions SWI is an alternative to PWI to assess penumbra and predict stroke evolution. Further prospective studies are needed to evaluate the role of SWI in guiding thrombolytic therapy. Key Points ? SWI can provide perfusion information comparable to MTT ? SWI–DWI mismatch can indicate ischaemic penumbra ? SWI–DWI mismatch can be a predictor for stroke evolution     

Orbital malignant lesions in adults: multiparametric MR imaging

Purpose

To assess the benefit of combining diffusion-weighted imaging and dynamic contrast-enhanced (DCE) MR imaging in the preoperative evaluation of orbital lymphoma and other malignancies in adults.

Materials and methods

This retrospective study was institutional review board-approved and informed consent was waived. Pretreatment MR imaging was performed in 52 patients with malignant orbital lesions. Apparent diffusion coefficient (ADC) and DCE MR parameters were evaluated in 30 patients with orbital lymphoma and 22 patients with other orbital malignancies. Independent-samples t-test or Wilcoxon rank-sum test was used to compare parameters. The diagnostic capability was evaluated by using receiver operating characteristic curve (ROC) analysis.

Results

Lymphoma demonstrated significantly lower mean ADC (P < 0.001), T _max (P = 0.001), enhancement ratio (ER) (P < 0.001), contrast index (CI) (P < 0.001) and significantly higher washout ratio (WR) (P = 0.002) than other malignancies in the orbit. ROC analysis indicated that T _max alone or a combination with ADC and ER showed the optimal sensitivity (96.67%), a combination of ADC and WR showed optimal specificity (95.45%), while a combination of ADC and ER showed optimal accuracy (90.38%) in differentiating lymphoma from other malignancies.

Conclusion

Multiparametric MRI can help to differentiate orbital lymphoma and other malignancies.

     

Sequential combination of intravenous recombinant tissue plasminogen activator and intra-arterial urokinase in acute ischemic stroke

BACKGROUND AND PURPOSE: Combined intravenous (IV) and intra-arterial (IA) thrombolytic therapy may be faster and easier to initiate than monotherapy, and its recanalization rate may be better as well. The sequential combination of recombinant tissue plasminogen activator (rTPA) and urokinase (UK) has synergistic and complementary effects on clot lysis. We prospectively evaluated the effectiveness and safety of sequential combination of IV rTPA and IA UK in acute ischemic stroke. METHODS: IV rTPA was administered to patients with acute stroke within 3 hours of onset. Those whose condition had not improved at the end of rTPA infusion were further treated with selective IA UK. We evaluated baseline and 30-day National Institutes of Health Stroke Scale (NIHSS) scores and 90-day modified Rankin Scale scores. RESULTS: Thirty patients were initially treated with IV rTPA; 24 were further treated with IA UK. Four patients who had rapid reocclusion following initial successful IA therapy received IV abciximab. Fourteen of 24 patients who underwent angiography had an effective perfusion state of Thrombolysis in Myocardial Infarction grade 3 flow. Median baseline and 30-day NIHSS scores were 18 and 2, respectively. Eighteen patients improved to a modified Rankin scale score of 0 or 1 after 90 days. Symptomatic hemorrhage developed in two patients. CONCLUSION: The strategy of using conventional-dose IV rTPA and the sequential combination of IA UK in patients without an early clinical response to IV treatment was safe and feasible. This strategy achieved high complete arterial recanalization rates and good functional outcomes.     

Benign and malignant breast lesions: diagnosis with multiparametric MR imaging

PURPOSE: To both develop and use a tissue signature method for the identification and classification of breast lesions and healthy breast tissue with magnetic resonance (MR) imaging. MATERIALS AND METHODS: Thirty-six patients underwent breast MR imaging (T1- and T2-weighted imaging and three-dimensional T1-weighted imaging with and without contrast material enhancement), followed by biopsy or mastectomy and histopathologic analysis. Tissue cluster analysis was performed by using the iterative self-organizing data technique to identify glandular, adipose, and lesion tissue signature vectors. Glandular and lesion tissue vectors were characterized by angular separation from the reference adipose tissue vector. Differences in angular separation of histologically proved benign and malignant lesion groups were evaluated with an independent t test. The usefulness of the angular separation model for distinguishing benign from malignant lesions was evaluated with nonparametric receiver operating characteristic curve analysis. RESULTS: The model enabled successful identification and characterization of breast lesion tissue clusters in all patients; 18 lesions were benign, and 18 were malignant. Angular separation +/- SD was 17.8 degrees +/- 6.1 degrees between adipose tissue and malignant lesions and 29.0 degrees +/- 11.2 degrees between adipose tissue and benign lesions. Angular separations of benign lesions and malignant lesions were significantly different (P =.002), with a specificity of 78% and sensitivity of 89% at a cutoff value of 21 degrees. Significant differences in angular separation from adipose tissue also were found between glandular tissue and lesion tissue (P <.001) and, in glandular tissue, between patients with benign lesions and those with malignant lesions (P =.04). The area under the receiver operating characteristic curve was 0.84. CONCLUSION: Multispectral analysis of conventional breast MR images based on the iterative self-organizing data model and on measurement of angular separation between tissue signature vectors may enable automated lesion identification and classification.     

Intra-arterial thrombolysis: tissue plasminogen activator and other thrombolytic agents

Recanalization rates with the administration of intravenous tissue plasminogen activator in acute ischemic stroke are low. Adjuvant endovascular techniques that achieve recanalization by direct intra-arterial (IA) delivery of thrombolytics, mechanical clot retrieval, clot aspiration, and stenting may complement intravenous pharmacotherapy. IA thrombolytics can be administered within 6 hours of symptom onset in anterior circulation strokes and within 24 hours in posterior circulation strokes. This review describes the indications, patient selection, and technique for IA administration of thrombolytics.     

Diagnostic and prognostic value of early MR Imaging vessel signs in hyperacute stroke patients imaged <3 hours and treated with recombinant tissue plasminogen activator

BACKGROUND AND PURPOSE: Analogous to the CT hyperattenuated vessel sign (HMCAS), MR imaging may show hypo- or hyperintense vessels in acute ischemic stroke (AIS) patients. We assessed the diagnostic and prognostic strength of early MR imaging vessel signs in AIS patients treated with intravenous thrombolysis (IVT) within 3 hours of the onset of symptoms. METHODS: We studied AIS patients both treated with IVT and stroke MR imaged within 3 hours of the onset of symptoms and at 2 hours and 24 hours after treatment. We assessed the presence or absence of early vessel signs (hyperintense fluid-attenuated inversion recovery sign [FLAIR HVS]; gradient-echo susceptibility vessel sign [GRE SVS]) compared with a combined MR angiography/perfusion-weighted imaging reference and their strength for predicting clinical outcome (favorable vs. poor, independent vs. dependent, or dead, death), recanalization (by clot composition and flow), and hemorrhage in uni- and multivariate analysis. RESULTS: Fifty-six patients (age range, 76 years +/- 13 years; median National Institutes of Health stroke scale score [NIHSSS], 11) met the inclusion criteria. Forty-four patients (78.6%) had a vessel occlusion at baseline; 22 of them (50%) recanalized. Nineteen patients (33.9%) suffered some form of intracranial hemorrhage (ICH), 24 patients (42.9%) had an independent outcome, 18 patients (32.1%) a favorable outcome, and 14 patients died. Compared with our combined reference for vessel status PWI/MRA, the sensitivities of CT HMCAS, FLAIR HVS, and GRE SVS were 40%, 66%, and 34%, respectively, and improved during the hours that followed. Localization was accurately reflected by FLAIR HVS but not by GRE SVS. Only NIHSSS and age were independent predictors for recanalization and all clinical outcomes in multiple logistic regression analysis. CONCLUSION: Although early vessel signs can be helpful in the diagnosis of intravascular disease, they do not independently predict recanalization, ICH, or any of the three clinical outcomes in a multivariate logistic regression model. Thrombus composition as reflected by signal intensity characteristics on GRE and FLAIR does not predict the therapeutic effect of IVT.     

Local intra-arterial fibrinolytic therapy in patients with stroke: urokinase versus recombinant tissue plasminogen activator (r-TPA)

Summary A group of 59 patients with stroke due to acute vertebrobasilar or carotid territory occlusion have been treated by local intra-arterial fibrinolysis (LIF). A high recanalisation rate was accomplished with either urokinase or recombinant tissue plasminogen activator (r-TPA). However, with either substance, even if a high dose was used, recanalisation was a time-consuming process which usually took 120 min. A reasonable explanation for the lack of effectiveness of these plasminogen-activating substances might be a deficit of substrate, e.g. plasminogen, in aged thrombus. LIF was capable of improving clinical outcome in acute vertebrobasilar artery occlusion, reducing mortality to 50% in patients fulfilling inclusion criteria. In the carotid territory multiple occlusions had a poor prognosis while good clinical results could be achieved in occlusions of the proximal middle cerebral artery or single branches.     

Characterization of indium-111 labeled recombinant tissue plasminogen activator for the imaging of thrombi

The in vitro functional properties of recombinant tissue plasminogen activator (rt-PA), its biodistribution in mice, and its pharmacokinetics and clot localization properties in dogs have been investigated after labeling rt-PA with ¹¹¹In. The rt-PA was coupled with the bicyclic anhydride of DTPA using standard methodology. Amidolytic and fibrinolytic assays showed retention of protein activity when rt-PA was conjugated with an average of one DTPA group or less per molecule. Size exclusion HPLC showed each preparation to be radiochemically pure with ¹¹¹In bound exclusively to the attached DTPA groups. Biodistribution in mice showed major accumulation of activity in the liver and kidneys. After administration of 0.5–1.0 mg of the labeled protein to dogs, blood activity decreased with a half time of approximately 5 min in agreement with previous reports of rapid blood clearance. Largely because of decreased blood levels, clot: blood ratios of labeled protein increased rapidly, in one study reaching 6.3 after 31 min, and satisfactory images of fibrin thrombi were obtained. The rt-PA may be labeled with ¹¹¹In without destroying the ability of the protein to localize in clot and images of forming clot can be obtained with this agent within 1 h after administration.     

Characterization of indium-111 labeled recombinant tissue plasminogen activator for the imaging of thrombi

The in vitro functional properties of recombinant tissue plasminogen activator (rt-PA), its biodistribution in mice, and its pharmacokinetics and clot localization properties in dogs have been investigated after labeling rt-PA with 111In. The rt-PA was coupled with the bicyclic anhydride of DTPA using standard methodology. Amidolytic and fibrinolytic assays showed retention of protein activity when rt-PA was conjugated with an average of one DTPA group or less per molecule. Size exclusion HPLC showed each preparation to be radiochemically pure with 111In bound exclusively to the attached DTPA groups. Biodistribution in mice showed major accumulation of activity in the liver and kidneys. After administration of 0.5-1.0 mg of the labeled protein to dogs, blood activity decreased with a half time of approximately 5 min in agreement with previous reports of rapid blood clearance. Largely because of decreased blood levels, clot: blood ratios of labeled protein increased rapidly, in one study reaching 6.3 after 31 min, and satisfactory images of fibrin thrombi were obtained. The rt-PA may be labeled with 111In without destroying the ability of the protein to localize in clot and images of forming clot can be obtained with this agent within 1 h after administration.     

Prostate cancer: multiparametric MR imaging for detection, localization, and staging

This review presents the current state of the art regarding multiparametric magnetic resonance (MR) imaging of prostate cancer. Technical requirements and clinical indications for the use of multiparametric MR imaging in detection, localization, characterization, staging, biopsy guidance, and active surveillance of prostate cancer are discussed. Although reported accuracies of the separate and combined multiparametric MR imaging techniques vary for diverse clinical prostate cancer indications, multiparametric MR imaging of the prostate has shown promising results and may be of additional value in prostate cancer localization and local staging. Consensus on which technical approaches (field strengths, sequences, use of an endorectal coil) and combination of multiparametric MR imaging techniques should be used for specific clinical indications remains a challenge. Because guidelines are currently lacking, suggestions for a general minimal protocol for multiparametric MR imaging of the prostate based on the literature and the authors' experience are presented. Computer programs that allow evaluation of the various components of a multiparametric MR imaging examination in one view should be developed. In this way, an integrated interpretation of anatomic and functional MR imaging techniques in a multiparametric MR imaging examination is possible. Education and experience of specialist radiologists are essential for correct interpretation of multiparametric prostate MR imaging findings. Supportive techniques, such as computer-aided diagnosis are needed to obtain a fast, cost-effective, easy, and more reproducible prostate cancer diagnosis out of more and more complex multiparametric MR imaging data.     

Normal and infarcted myocardium: differentiation with cellular uptake of manganese at MR imaging in a rat model

PURPOSE: To assess whether normal myocardium can be distinguished from infarction at magnetic resonance (MR) imaging with low doses of manganese dipyridoxyl diphosphate (Mn-DPDP). MATERIALS AND METHODS: After 1-hour coronary arterial occlusion and 2-hour reperfusion, three groups of eight rats each were injected with 25, 50, or 100 micromol of Mn-DPDP per kilogram of body weight. The longitudinal relaxation rate (R1) in normal myocardium, reperfused infarction, and blood was repeatedly measured at inversion-recovery echo-planar imaging before and for 1 hour after the administration of contrast material. Afterward, several animals from each group were examined at high-spatial-resolution inversion-recovery spin-echo (SE) MR imaging. RESULTS: Manganese accumulated in normal myocardium but was cleared from reperfused infarction and blood. One hour after the administration of Mn-DPDP, R1 in normal myocardium (1.53 sec(-1) +/- 0.03, 1.73 sec(-1) +/- 0.03, and 1.94 sec(-1) +/- 0.02, respectively, for 25, 50, and 100 micromol/kg) was significantly (P <.05) faster than that of reperfused infarction (0.99 sec(-1) +/- 0.03, 1.11 sec(-1) +/- 0.03, and 1.48 sec(-1) +/- 0.06). Normal myocardium appeared hyperintense on T1-weighted inversion-recovery SE MR images and was clearly distinguishable from reperfused infarction. CONCLUSION: Mn-DPDP-enhanced inversion-recovery echo-planar and SE MR images demonstrated retention of manganese in normal myocardium and clearance of manganese from infarction. Mn-DPDP has characteristics similar to those of widely used thallium and may be useful in the assessment of myocardial viability at MR imaging.     

Diffusion and perfusion MR imaging in stroke

Magnetic resonance imaging (MRI) in stroke makes it possible to visualize the initial infarct in cases of acute cerebral ischemia. Perfusion MRI serves to determine which tissues are additionally at risk of infarction due to persistent hypoperfusion. MRI also allows those examiners with limited experience to reliably confirm an infarct. The most important differential diagnosis of cerebral ischemia, intracerebral hemorrhage, can likewise be recognized with certainty using MRI. Although diffusion and perfusion MRI only demonstrate the pathophysiology of cerebral ischemia approximately, the method is suited for identifying those patients who would profit from reperfusion therapy. Whether MRI is also appropriate as an aid to reaching a prognosis on the risk of secondary hemorrhage has not yet been resolved.     

Sequential ventilation/perfusion imaging of massive pulmonary embolism treated with recombinant tissue plasminogen activator

Pulmonary embolism is a common clinical problem estimated to cause 200,000 deaths per year in the United State. There is increasing interest in early diagnosis and prompt aggressive therapy. A case is reported of a patient with massive pulmonary embolism treated with recombinant tissue plasminogen activator. Ventilation/perfusion imaging was used both to make an early diagnosis as well as to evaluate the efficacy of therapy.     

Cerebral blood volume in a rat model of ischemia by MR imaging at 4.7 T

Perturbation of the cerebral circulation by occlusion of the vertebral arteries and a carotid artery can be visualized by using MR imaging and the intravascular contrast agent Gd-DTPA complexed to albumin. This tracer consistently reduced the T1 relaxation time in the brain and blood. The difference between hemispheres was revealed by less T1 reduction in the occluded hemisphere and by an adjustment in the display contrast of images that revealed the territory of decreased perfusion. These results were confirmed by comparing them with cerebral blood flow using radioactive microspheres and the intravascular blood volume tracer 51Cr-EDTA. This method, combined with high-resolution MR imaging, can be applied to serial noninvasive studies of cerebral blood volume in ischemia and other conditions.     

Intracranial leptomeningeal metastases: comparison of depiction at FLAIR and contrast-enhanced MR imaging

PURPOSE: To compare contrast material-enhanced T1-weighted and fluid-attenuated inversion-recovery (FLAIR) magnetic resonance (MR) images in depicting leptomeningeal metastases. MATERIALS AND METHODS: Malignant lesions detected at cytologic examination of cerebrospinal fluid in 70 patients were reviewed. There were 58 studies in which both FLAIR and contrast-enhanced T1-weighted spin-echo MR images were available. A senior neuroradiologist reviewed the images from each sequence individually and separately for signs of leptomeningeal metastases and assigned a diagnostic rating of positive, indeterminate, or negative. RESULTS: Leptomeningeal metastases were depicted in 38 cases on contrast-enhanced T1-weighted spin-echo images and in 20 cases on FLAIR images. In three cases, leptomeningeal metastases were detected by using only FLAIR images. In 20 cases, leptomeningeal metastases were detected by using only contrast-enhanced T1-weighted spin-echo images. FLAIR imaging has a sensitivity of 34% for cytologically proved leptomeningeal metastases. Gadolinium-enhanced MR imaging has a sensitivity of 66%. CONCLUSION: Used alone, contrast-enhanced T1-weighted images are better than FLAIR images for detecting leptomeningeal metastases. This is particularly true for cases in which leptomeningeal metastases manifest primarily or solely as cranial nerve involvement.     

CT perfusion identifies increased salvage of tissue in patients receiving intravenous recombinant tissue plasminogen activator within 3 hours of stroke onset

BACKGROUND AND PURPOSE: In spite of the advent of thrombolytic therapy, CT-perfusion imaging is currently not fully used for clinical decision-making and not included in published clinical guidelines for management of ischemic stroke. We investigated whether lesion volumes on cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) maps predict final infarct volume and whether all these parameters are needed for triage to intravenous recombinant tissue plasminogen activator (rtPA). We also investigated the effect of intravenous rtPA on affected brain by measuring salvaged tissue volume in patients receiving intravenous rtPA and in controls.MATERIALS AND METHODS: Forty-four patients receiving intravenous rtPA and 19 controls underwent CT perfusion (CTP) studies in the emergency department within 3 hours of stroke onset. Lesion volumes were measured on MTT, CBV, and CBF maps by region-of-interest analysis and were compared with follow-up CT volumes by correlation and regression analysis. The volume of salvaged tissue was determined as the difference between the initial MTT and follow-up CT lesion volumes and was compared between intravenous rtPA-treated patients and controls.RESULTS: No significant difference between the groups was observed in lesion volume assessed from the CTP maps (P > .08). Coefficients of determination for MTT, CBF, and CBV versus follow-up CT lesion volumes were 0.3, 0.3, 0.47, with intravenous rtPA; and 0.53, 0.55, and 0.81 without intravenous rtPA. Regression of MTT on CBF lesion volumes showed codependence (R² = 0.98, P < .0001). Mean salvaged tissue volumes with intravenous rtPA were 21.8 ± 17.1 and 13.2 ± 13.5 mL in controls; these were significantly different by using nonparametric (P < .03) and Fisher exact tests (P < .04).CONCLUSIONS: Within 3 hours of stroke onset, CBV lesion volume does not necessarily represent dead tissue. MTT lesion volume alone can be used to identify the upper limit of the size of abnormally perfused brain. More brain is salvaged in patients with intravenous rtPA than in controls.

CT with physiologic imaging of cerebral perfusion (CTP) is routinely used at many centers around the world to assist in the triage of patients with acute stroke into various therapies, including intravenous thrombolysis with recombinant tissue plasminogen activator (rtPA). The use of CT in the triage process has been driven by the rapidity and wide availability of this imaging technique. Functional maps of cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) are readily constructed on a CT workstation and provide important information about the status of regional brain perfusion. Because giving intravenous rtPA is optimal within 3 hours of stroke ictus, it would be helpful to avoid spending time on those CTP parameters that do not provide critical information and to evaluate only those that directly impact the therapeutic decision.A key consideration in the assessment process of patients having acute stroke symptoms is how much affected brain tissue was already infarcted, how much is inevitably going to die, and how much could be potentially salvaged by therapy. It is this functional information that is being sought by using perfusion imaging and mapping of vascular physiology.^1-5 In the literature, it has been shown that lesion volumes on physiologic maps constructed from initial perfusion imaging in patients assessed in the 6- to 72-hour time window predict the final infarct volume.^6-9 Furthermore, several authors have shown that the volume of the initial CBV deficit approximates the final infarct size and likely represents already irreversibly infarcted tissue.^10,11Because the development of infarction is a dynamic time-dependent process, interpretation of the maps may well vary with the time from ictus. It was our aim in this study to investigate whether the lesion volumes observed on CBV, CBF, and MTT CTP maps, obtained within 3 hours of ictus, also predicted the final infarct volume and whether all these parameters are needed for triage. In addition, we investigated the effect of intravenous rtPA on affected brain tissue by measuring the final salvaged tissue volume in patients receiving intravenous rtPA and in a control group not receiving thrombolytic therapy.