海洛因烟雾吸入致海绵状白质脑病的CT、MRI表现

目的 探讨海洛因烟雾吸入所致的海绵状脑病的CT、MRI征象,提高对该病的认识和诊断水平。方法 对4例加热吸食海洛因烟雾的患者进行颅脑CT或MR平扫和增强,MRI常规行SE序列平扫、增强,以及液体衰减反转恢复序列（FLAIR）、磁共振波谱（MRS）检查。结果 2例CT扫描的病例表现为双侧小脑半球、脑干、内囊后肢、大脑脚 、胼胝体压部、大脑后部脑白质对称性低密度灶,无强化。2例MRI检查的病例也表现为相应区域长T1、长T2信号,无强化。FLAIR像呈高信号,小脑病变较大脑明显,顶枕叶病变较额叶显著,MRS显示脑白质变性,乳酸升高。结论 该病的CT及MRI表现较具特征性,结合病史,可作出诊断。     

海洛因白质脑病的CT与MRI诊断

目的 研究CT与MRI对烫吸海洛因蒸汽引起海绵状白质脑病的特征性影像学诊断价值。方法 对2例烫吸海洛因引起的海绵状白质脑病的患者进行了临床和CT与MRI观察，查阅中外文献，对该病影像学特征结合临床表现、病理组织改变进行总结与讨论。结果 2例患者以小脑性共济失调、智力减退为主要临床表现，CT显示对称性分布的小脑白质、大脑白质为主的低密度改变；MRI显示对称性分布的小脑齿状核，大脑半球半卵圆中心、双基底节内囊、中脑、桥脑白质纤维为主的高信号改变。结论 烫吸海洛因引起海绵状白质脑病的CT与MRI影像学改变具有特征性，能为临床诊断提供可靠依据，从而使本病能够得到早期确诊。     

海洛因所致海绵状白质脑病的MRI诊断

目的 阐述海洛因所致海绵状白质脑病的MRI表现及其诊断价值。材料与方法 搜集11例具有吸食海洛因史者的MRI资料,全部患者均进行MRI检查,检查序列包括T1WI、T2WI、FLAIR序列。结果 全部患者幕上半球脑白质、小脑半球、内囊后肢及膝部、胼胝体压部及膝部 见双侧,对称性异常改变,2例患者桥脑中央见椭圆形病变。MRI均表现为T1WI呈低信号,T2WI及FLAIR序列为不均匀或均匀高信号。以小脑半球白质受累最为严重,但其灰质核团未见受累,结论 海洛因所致海绵状白质脑病具有典型的MRI表现,结合病史,MRI诊断具有特异性。     

海洛因海绵状白质脑病的CT和MR表现

目的：总结海洛因海绵状白质脑病的CT及MRI特征。方法：分析5例海洛因海绵状白质脑病的临床特点，影像表现及1例病理所见，总结其CT和MRI的诊断要点。结果：海劣因海绵状白质脑病的CT和MRI特征为：（1）病变广泛累及小脑，大脑白质及脑博干，内囊后肢，多以小脑损害为重，其中以小脑中线两侧对称性边界清楚的类圆形蝴蝶样病灶为特征。（2）病灶双侧对称，边界清楚；（3）CT示病灶为低密度。MRI示病灶为T1WI低信号以及T2WI高信号影；（4）增强病灶无强化。主要的病理改变为脑白质的空泡样变性。结论：海洛因海绵状白质脑病的CT和MR表现为特征性改变，有海洛因烫吸史者，一旦出现小脑受损的表现，应及早行头部影像学检查明确诊断。     

"Chasing the dragon"--imaging of heroin inhalation leukoencephalopathy.

"Chasing the dragon" refers to the inhalation of heroin pyrolysate vapors produced when the freebase form of heroin is heated. Inhalation of these vapors can result in a rare toxic spongiform leukoencephalopathy. The patients may progress through 3 defined clinical stages, with one-quarter reaching the terminal stage, which invariably leads to death. Imaging and, in particular, magnetic resonance imaging (MRI) demonstrates white matter findings that are felt to be specific for this entity and essential in its early diagnosis. We present the typical imaging findings in a pictorial essay format, using images taken from 9 patients who presented within an 18-month period at UBC-affiliated hospitals. These findings include low computed tomography (CT) attenuation and high T2 MRI signal most commonly in the posterior cerebral and cerebellar white matter, cerebellar peduncles, splenium of the corpus callosum, and posterior limb of the internal capsules. In addition, there is often selective, symmetric involvement of the corticospinal tract, the medial lemniscus, and the tractus solitarius. We also present the variable diffusion-weighted imaging and apparent diffusion coefficient findings from 4 of our patients, which to our knowledge, have not been described in the literature.     

Neuroimaging features of heroin inhalation toxicity: "chasing the dragon"

OBJECTIVE: Our objective was to illustrate the dramatic neuroimaging findings of toxic leukoencephalopathy caused by heroin vapor inhalation. CONCLUSION: Symmetric abnormality involving the cerebellar white matter and posterior limb of the internal capsule is characteristic of heroin vapor inhalation toxicity, although involvement may be more extensive, depending on the severity of the condition. MR imaging and CT appear to be essential for making this diagnosis because clinical history is often unreliable and findings at physical examination are nonspecific.     

Comparison of conventional and diffusion-weighted MRI and proton MR spectroscopy in patients with mitochondrial encephalomyopathy,lactic acidosis,and stroke-like events

The mechanism of neurological disturbances in patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is controversial. We studied 12 patients with MELAS using conventional and diffusion weighted MRI (DWI) and MR spectroscopy (MRS), to look at the physiopathology of the stroke-like events. Although conventional MRI showed lesions in all patients, DWI was more sensitive. One patient did not show high signal on DWI 48 h after a from stroke-like episode, but MRS demonstrated a lactate peak in left occipital lobe; 2 weeks after the attack, high signal was demonstrated on the right frontal lobe where MRS had shown a lactate peak. Our findings suggest a possible predictive ability of ¹H-MRS, in showing early MELAS lesions and supports the hypothesis that mitochondrial metabolic dysfunction may precedes abnormalities on DWI.     

Methamphetamine-induced toxic leukoencephalopathy: clinical,radiological and autopsy findings

Toxic leukoencephalopathy represents a process of structural alteration of the white matter. It is caused by substance abuse including drugs such as heroin, cocaine, toluene and ethanol. We reported the clinical, radiological and autopsy findings of a rare case of toxic leukoencephalopathy following chronic methamphetamine (MA) usage. A 34-year-old man with a 3-year history of MA abuse experienced progressive sluggish state, limb weakness, inability to stand and eating disorders, followed by rapid progression to coma and death. Imaging revealed hypodense CT and long T1 and T2 signals in MRI in the white matter of the bilateral periventricular and centrum semiovale regions. Histologically, white matter rarefaction, loss of myelin and axonal injury were observed. This pattern of clinical presentation, radiological manifestations and histological findings show a certain degree of particularity in toxic leukoencephalopathy. Clinically, the condition may be easily misdiagnosed as withdrawal symptoms. In suspected cases, MRI is recommended for diagnosis. The case reported here reminds clinicians and forensic pathologist of the possibility of toxic leukoencephalopathy related to MA abuse.     

MELAS syndrome: imaging and proton MR spectroscopic findings.

PURPOSETo evaluate imaging findings in MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, strokes) syndrome for the presence and location of infarctions and the presence of lactate.METHODSEight patients were studied with MR (n = 8) and CT (n = 2). One patient underwent single-photon emission CT with technetium 99m hexamethyl-propyleneamine oxime and one patient had conventional catheter angiography. One fixed brain was studied with MR imaging. Five patients underwent single volume proton MR spectroscopy. Imaging studies were evaluated for atrophy, edema, and infarctions. Proton MR spectroscopy was visually analyzed for presence or absence of lactate.RESULTSOne patient showed a cerebral infarction, and later a second distant infarction developed. One patient showed a transient area of cortical edema. Two patients had small nonspecific periventricular white matter abnormalities and one patient had diffuse white matter hyperintensities. Two patients had nonspecific MR abnormalities (probably age-related changes), and two had normal MR findings. None had basal ganglia involvement. Proton MR spectroscopy showed presence of lactate in one case with transient cortical edema; in two cases with nonspecific (probably age-related) brain findings; and in two patients with normal MR findings.CONCLUSIONSPatients with MELAS have a variety of MR findings. The fact that proton MR spectroscopy showed lactate in all five cases studied, regardless of MR findings, indicates that proton MR spectroscopy may be more sensitive in the detection of MELAS-associated abnormalities than MR imaging.     

MRI of focal cortical dysplasia

We studied nine cases of focal cortical dysplasia (FCD) by MRI, with surface-rendered 3D reconstructions. One case was also examined using single-voxel proton MR spectroscopy (MRS). The histological features were reviewed and correlated with the MRI findings. The gyri affected by FCD were enlarged and the signal of the cortex was slightly increased on T1-weighted images. The gray-white junction was indistinct. Signal from the subcortical white matter was decreased on T1- and increased on T2-weighted images in most cases. Contrast enhancement was seen in two cases. Proton MRS showed a spectrum identical to that of normal brain. Received: 10 September 1997 Accepted: 6 January 1998     

MRI及MRS对大脑胶质瘤病的诊断及鉴别诊断价值

目的评价MRI及MRS在大脑胶质瘤病的诊断和鉴别诊断中的价值。方法回顾性分析经活检、手术病理证实的6例大脑胶质瘤病患者的MRI和MRS表现特征,并与病理切片进行对照;常规行SE序列平扫及增强、DWI序列成像,其中3例行MRS研究,二维多体素、点分辨法PRESS、TE 144 m s。结果所有病例均侵犯2个脑叶或以上,同时伴胼胝体侵犯6例、基底节和丘脑侵犯4例、脑干侵犯2例。病变区呈长T2、稍长T1异常信号,T2WI、FLAIR上均为高信号,无坏死、钙化,受累区脑组织肿胀,占位效应轻。2例增强扫描见小结节状强化,4例无明显强化。3例MRS表现均有不同程度NAA降低,NAA/Cr比值降低,Cho上升,Cho/Cr和Cho/NAA的比值上升。结论MRI结合MRS对大脑胶质瘤病的诊断及鉴别诊断具有较大价值,结合临床、MRI及MRS是能够作出明确诊断的。     

Reversible MR imaging and MR spectroscopy abnormalities in association with metronidazole therapy

We present a report of MRI and proton MR spectroscopy (MRS) findings in an adolescent patient with Down syndrome and Crohn disease treated with metronidazole. MRI revealed signal abnormalities within the corpus callosum, basal ganglia, and brainstem. Proton MRS examination demonstrated a persistent lactate elevation during metronidazole treatment. Clinical, spectroscopic, and imaging abnormalities resolved with discontinuation of metronidazole.     

Value of diagnosis and differential diagnosis of MRI and MR spectroscopy in gliomatosis cerebri

PURPOSE: The purpose of this study was to characterize gliomatosis cerebri on magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS), and to analyze the value of these two techniques in diagnosis and differential diagnosis of gliomatosis cerebri. MATERIALS AND METHODS: MR images of 14 patients with gliomatosis cerebri were reviewed retrospectively; seven of the patients also underwent MRS (single-voxel point-resolved spectroscopy, and chemical-shift imaging point-resolved spectroscopy). Tumorous were confirmed by surgery and biopsy. The distribution, extension and signal features of lesions were assessed, and the MR spectroscopy results were analyzed. RESULTS: Tumors involved at least two lobes of the brain in all patients. Widespread invasion with isointensity or hypointensity on T1-weighted MR images and hyperintensity on T2-weighted images were found while no prominent necrosis, hemorrhage or contrast enhancement was found. All patients who underwent MRS showed elevated Cho/Cr and Cho/NAA levels as well as decreased NAA/Cr ratios in the abnormal areas on T2-weighted images, three of which showed a lactate doublet. Anaplastic lesions had higher Cho/NAA levels in three cases. Abnormality of metabolism was also seen in the margin of the lesion that was normal on T2-weighted images. CONCLUSION: MRI and MRS are valuable techniques for diagnosis and differential diagnosis of gliomatosis cerebri. Combining clinical information and MRI findings, as well as MRS, is crucial for making a definitive diagnosis.     

Clinico-radiological spectrum of bilateral temporal lobe hyperintensity:a retrospective review

Bilateral temporal lobe hyperintensity (BTH) is a commonly encountered MRI finding in a wide spectrum of clinical conditions and often poses a diagnostic challenge to the radiologist. The purpose of this paper is to elucidate several diseases that manifest as BTH on MRI, based on a retrospective review of cranial MRI of 65 cases seen in our institution between October 2007 and September 2010. We found BTH in different clinical scenarios that included infective diseases (herpes simplex virus, congenital cytomegalovirus infection), epileptic syndrome (mesial temporal sclerosis), neurodegenerative disorders (Alzheimer's disease, frontotemporal dementia, Type 1 myotonic dystrophy), neoplastic conditions (gliomatosis cerebri), metabolic disorders (mitochondrial encephalopathy, lactic acidosis and stroke-like episodes, Wilson's disease, hyperammonemia), dysmyelinating disease (megalencephalic leukoencephalopathy with subcortical cysts), and vascular (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy) and paraneoplastic (limbic encephalitis) disorders. The conventional MRI findings with advanced MRI such as diffusion-weighted imaging, susceptibility-weighted imaging and MR spectroscopy along with laboratory results are potentially helpful in distinguishing the different clinical conditions and thus affect the early diagnosis and clinical outcome.     

常规MRI和1H-MRS成像对假瘤型脱髓鞘病的诊断价值

目的 联合常规MRI和氢质子磁共振波谱(1H-MRS)分析探讨中枢神经系统假瘤型脱髓鞘病变(DPLs)的影像特点.资料与方法 回顾性分析5例经手术证实和4例临床证实的DPLs的MRI表现,其中3例作了多体素和单体素短回波1H-MRS检查.结果 (1)4例表现为局限性肿块伴有轻到中度水肿,3例为不规则病灶,2例为多发病灶.(2)增强扫描:4例为开环样强化,2例为斑片状强化,2例为结节强化,1例为稀疏的轻度强化;3例病灶内侧缘显示多条平行线状血管影延伸到病灶中央,并与邻近的正常脑组织或室管膜下静脉相续.(3)1H-MRS分析:3例均有NAA峰不同程度降低,Cho峰、Lac和Lip峰升高,急性期过后随访Lac和Lip峰明显降低,2例在急性期出现了谷氨酸/谷氨酰胺复合物(β,γ-Glx峰)的升高.结论 DPLsMRI增强显示开环样强化具有特征性,病灶内侧缘扩张的血管影提示脱髓鞘炎症病变;1H-MRS急性期有β,γ-Glx峰的升高和在急性期后随访Lac和Lip峰的降低具有较大价值.     

Role of brain magnetic resonance spectroscopy in the evaluation of suspected mitochondrial diseases in children: Experience in 30 pediatric cases

Introduction

Mitochondrial diseases are a group of inherited disorders caused by derangement of mitochondrial respiration. MR spectroscopy (MRS) has been shown to detect abnormal accumulation of lactate in brain parenchyma and CSF in patients with mitochondrial disorders, but the frequency of detection is largely unknown.

Aim of the work

To evaluate the role of brain MR spectroscopy in the assessment of suspected mitochondrial diseases in the pediatric age group.

Patients and methods

Thirty children with suspected mitochondrial diseases were examined by MRS. Examination was done using multisection technique and multiple echo times mainly short (35 ms) and intermediate (144 ms). Mitochondrial disease criteria scoring system was used to confirm the suspected diagnosis.

Results

All patients showed elevated lactate peak with the CSF being the most sensitive (100%). Among the 30 patients, 26 (86.7%) had elevated levels of blood lactate/pyruvate ratio. Conventional MRI showed highly suggestive features in 15 patients while non specific findings were detected in 11 patients and 4 showed normal appearing brain.

Conclusions

MRS provides a noninvasive tool for the diagnosis of mitochondrial diseases, especially in children with non specific findings on MRI, normal appearing MRI or a normal blood lactate/pyruvate ratio.     

Cerebral gliomas: prospective comparison of multivoxel 2D chemical-shift imaging proton MR spectroscopy,echoplanar perfusion and diffusion-weighted MRI

Developments in MRI have made it possible to use diffusion-weighted MRI, perfusion MRI and proton MR spectroscopy (MRS) to study lesions in the brain. We evaluated whether these techniques provide useful, complementary information for grading gliomas, in comparison with conventional MRI. We studied 17 patients with histologically verified gliomas, adding multivoxel proton MRS, echoplanar diffusion and perfusion MRI the a routine MRI examination. The maximum relative cerebral blood volume (CBV), minimum apparent diffusion coefficient (ADC) and metabolic peak area ratios in proton MRS were calculated in solid parts of tumours on the same slice from each imaging data set. The mean minimum ADC of the 13 high-grade gliomas (0.92+/-0.27 x 10(-3) mm(2)/s) was lower than that of the four low-grade gliomas (1.28+/-0.15 x 10(-3) mm(2)/s) ( P<0.05). Means of maximum choline (Cho)/N-acetylaspartate (NAA), Cho/creatine (Cr), Cho/Cr in normal brain (Cr-n) and minimum NAA/Cr ratios were 5.90+/-2.62, 4.73+/-2.22, 2.66+/-0.68 and 0.40+/-0.06, respectively, in the high-grade gliomas, and 1.65+/-1.37, 1.84+/-1.20, 1.61+/-1.29 and 1.65+/-1.61, respectively, in the low-grade gliomas. Significant differences were found on spectroscopy between the high- and low-grade gliomas ( P<0.05). Mean maximum relative CBV in the high-grade gliomas (6.10+/-3.98) was higher than in the low-grade gliomas (1.74+/-0.57) ( P<0.05). Echoplanar diffusion, perfusion MRI and multivoxel proton MRS can offer diagnostic information, not available with conventional MRI, in the assessment of glioma grade.     

Abnormal cerebral metabolism in polydrug abusers during early withdrawal: A 31P MR spectroscopy study

Phosphorus magnetic resonance spectroscopy (³¹P MRS) at 1.5 T was performed on nine polysubstance abusing men. All nine patients met DSM-III-R criteria for concurrent cocaine and heroin dependence, were neurologically normal, were negative for the human immunodeficiency virus, and had normal clinical brain MRI scans. Patients were scanned 2-7 days after admission to a drug treatment unit. Eleven age-matched control subjects also were studied. The ISIS localized phosphorus spectra were obtained from a 5-cm thick axial brain slice and a 100-cc white matter volume. In the brain slice, the phosphorus metabolite signal expressed as a percentage of total phosphorus signal was 15% higher for phosphomonoesters, 10% lower for nucleotide triphosphates (β-NTP), and 7% lower for total nucleotide phosphates in polydrug abusers compared with those in controls. Phosphodiesters, inorganic phosphate, phosphocreatine, total phosphorus, pH, and free magnesium concentration were unchanged. None of these parameters correlated with the methadone dose or the number of days abstinence. Single photon emission computed tomographic imaging of a subgroup of the patients revealed abnormal cerebral perfusion in 80% of the patients scanned. These data suggest that cerebral high energy phosphate and phospholipid metabolite changes result from long term drug abuse and/or withdrawal and that these changes can be detected and studied by ³¹P MRS.     

Differences in water diffusion and lactate production in two different types of postinfectious encephalopathy

We compared two different types of postinfectious encephalopathy using magnetic resonance imaging (MRI), including diffusion-weighted images and MR spectroscopy. Acute disseminated encephalomyelitis (ADEM) and acute necrotizing encephalopathy (ANE) showed different distribution of abnormal intensity areas and different diffusion of water measured by diffusion-weighted imaging (DWI). Proton MR spectroscopy (MRS) showed lactate production in both cases, which returned to a normal range; the rate of increased lactate production was much lower in the ANE case. Water diffusion showed a difference in pathophysiological background between the two encephalopathies, but the lactate elevation observed by proton MRS did not correlate with clinical severity.