Soft tissue and joint infection

Soft tissue infection may be acute or chronic and may be introduced by the haematogenous route, or by inoculation, including surgical infection, or spread from other areas. The spectrum of infecting organism differs in primary infection, in immunodeficiency or when foreign bodies, including prostheses, are present. Bacterial infections are usually more rapid than those due to fungi or atypical organisms. Inflammation usually begins as cellulitis, proceeding through necrosis to cavitation and abscess formation, sometimes complicated by haemorrhage. Imaging, apart from MRI in selected cases, is rarely helpful in the early stages, but early diagnosis of pyomyositis and necrotizing fasciitis is mandatory. When infection is established, US, CT and MRI all have individual value in diagnosis, including biopsy, and in directing therapy, including percutaneous or surgical drainage or debridement. Both MRI and CT are best suited to monitoring progress. Septic arthritis presents as rapidly progressive, destructive arthritis, and early diagnosis is essential to prevent long-term morbidity. Ultrasound offers the best method of detecting early joint effusion and synovial thickening, but aspiration is usually required for diagnosis. In more advanced stages CT is valuable for revealing destructive changes, and MRI for documenting intra-articular changes and detecting inflammation in surrounding bone.     

CT, MR, and pathology in HIV encephalitis and meningitis

The value and limitations of CT and MR in human immunodeficiency virus (HIV) infection of the brain was determined by a retrospective analysis of the CT scans (22) and MR images (7) in 22 patients with pathologically proved HIV encephalitis (21) or meningitis (1). Our clinical-radiologic-pathologic correlation suggested that, especially in the early stages of the disease, CT and MR were relatively insensitive in detecting the primary changes of HIV encephalitis. The multiple bilateral diffuse microscopic glial nodules with multinucleated giant cells of HIV found at autopsy in both gray and white matter were usually not directly visualized by either CT or MR. Secondary, nonspecific changes, however, were seen. These included cortical atrophy, found in virtually all patients with HIV encephalitis, and HIV-induced foci of demyelination found in the minority of cases. On CT the latter were seen in the white matter as nonenhancing, nonmass-producing areas of low density; on MR they were seen as frequently progressive high-intensity signal abnormalities on T2-weighted images, usually in the periventricular white matter and centrum semiovale. MR was more sensitive in detecting these demyelinative lesions than was CT. The clinical diagnosis of HIV encephalitis usually antedated the radiographic diagnosis. In HIV meningitis, contrast CT was more definitive than MR, showing striking enhancement of the subarachnoid spaces, although MR was more sensitive in detecting the secondary parenchymal changes.     

Imaging liver metastases: review and update

The radiologic diagnosis of liver metastasis involves detection, characterization, and tumor staging. Knowledge of the histopathologic changes that occur with metastases provides the best approach to the accurate interpretation of radiologic imaging findings, and in particular, radiologists need to choose appropriate imaging methods based on such knowledge. Because the majority of metastases are hypovascular, the merits of the routine acquisition of hepatic arterial dominant-phase images by contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI) are disputable. Hepatic arterial dominant-phase images may be obtained when hypervascular tumors are suspected or three-dimensional CT angiography is necessary. And, imaging during the portal venous phase is essential for detecting metastases, evaluating intrahepatic vessel invasion, and for assessing intratumoral necrosis or fibrosis. Equilibrium- to delayed-phase imaging 3-5 min after contrast administration may improve the detection of intratumoral fibrosis, and occasionally lead to more accurate tissue characterization. MRI offers diagnostic information on vascularity, amount of free water, hemorrhage, fibrosis, necrosis, and water molecule diffusion in metastases. And, liver-specific contrast agents like superparamagnetic iron oxide, liposoluble gadolinium chelate, and manganese may improve the MRI-based diagnosis of liver metastases.     

支气管肺癌的影像诊断

肺癌的主要影像检查方法为X线胸片、CT、MRI等,其中高电压胸片、高分辨CT是早期发现及鉴别诊断的最重要的方法。螺旋CT的影像重建技术和MRI对于肿瘤的分期有重要价值。中央型肺癌的早期X线表现为支气管的阻塞性改变,HRCT显示支气管狭窄、管壁增厚及管腔结节。周围型肺癌的早期X线表现为肺内结节或小斑片阴影,HRCT显示结节有分叶、空泡或细支气管气像、边缘毛糙及胸膜凹陷征。CT或MRI增强扫描显示肿瘤明显强化。经皮肺穿刺活检是诊断肺癌的重要方法。螺旋CT对于病变的多平面重建、三维重建及仿真支气管内镜可从多个角度显示病变的形态,对病变的鉴别诊断起辅助作用。对于肺癌转移的诊断方面,CT及MRI可较准确地判断淋巴结转移,三维CT血管重建（CAT）及MR血管成像（MRA）可准确地诊断肿瘤对血管的侵犯。MRI是确定胸壁转移的可靠方法。中心型肺癌需与肺结核及慢性肺炎鉴别,周围型肺癌应与结核球、慢性炎性结节等肺内孤立结节病变鉴别。在充分发挥X线胸片及HRCT检查的基础上,有目的地选择其他影像方法进行综合影像诊断,可提高肺癌的早期诊断及鉴别诊断水平。     

MR findings in leukodystrophy

Summary Up to 5 years ago, the radiological diagnosis of leukodystrophy was based on computed tomography (CT). More recently, magnetic resonance imaging (MRI) has been used to study pathology of the white matter with great success. The abnormalities in eight patients with different types of leukodystrophy are described, using high-field MRI. CT and MRI show comparable sensitivity in detecting the pathological changes of leukodystrophy. MRI seems to be superior in visualizing the extent of the lesions, their precise anatomical location and any involvement of the brain stem and cerebellum. Differential diagnosis among the three types of leukodystrophy by MRI is difficult but may be attempted by some features. Specific diagnosis can be achieved only by laboratory examination or histology. The role of MRI should be to suggest the proper biochemical test at an earlier stage.     

Computed tomography in maple syrup urine disease.

Maple Syrup Urine Disease (MSUD) is an inherited metabolic disorder characterized by a severe, usually lethal, neonatal course in the early stages with pseudotumor cerebri and pathologically documented increased cerebral water content. CT and MRI studies in MSUD are few and the data are overlapping. This study reports CT features before and after dietary treatment in three patients; two with classical MSUD and one with an intermediate variant of MSUD. At diagnosis, CT consistently showed evidence of abnormally high lucidity involving not only white matter, but also areas of grey matter, particularly the pallidum. Furthermore, these CT changes are present both in the acute phase of classical MSUD and in an intermediate variant of the disease. The observed abnormalities evolve favorably under dietary treatment, simultaneously with clinical and neurological improvement. It is concluded that the observed CT changes indicate a diagnosis of MSUD and are relevant findings in the neuroradiologic differential diagnosis in acutely ill newborns, in which a metabolic disease may be not immediately suspected.     

Diagnostic imaging in 13 cases of Rasmussen's encephalitis: can early MRI suggest the diagnosis?

Rasmussen's encephalitis (RE) is a rare, progressive, chronic encephalitis characterised by drug-resistant epilepsy, progressive hemiparesis and mental impairment. It typically involves only one cerebral hemisphere, which becomes atrophic. We present neuroradiological findings in 13 children with RE. MRI was performed in all patients, fluorodeoxyglucose positron-emission tomography (PET) in three, Tc-99m hexamethylpropylenamine oxime single-photon emission computed tomography (SPECT) in two and proton MR spectroscopy ((1)HMRS) in two. MRI showed progression of the hemisphere atrophy, always prevalent in the region primarily involved (13 patients), spread of the abnormal signal in white matter (11) and cortex (10) and progression of atrophy of the head of the caudate nucleus (nine). Associated secondary changes were: atrophy of the contralateral cerebellar hemisphere (in four patients), the ipsilateral hippocampus (in five) and the brain stem (in five). The earliest CT and MRI abnormalities, seen between 1 day and 4 months after the first seizure (in 12 patients examined, nine of whom had MRI) in one cerebral hemisphere included: high signal on T2-weighted images in the cortex (seven patients) and white matter (nine), cortical atrophy usually involving the frontoinsular region, with mild or severe enlargement of the lateral ventricle (eight) and moderate atrophy of the head of the caudate nucleus (seven). Cortical swelling in the early stage of the disease was recognisable only in two patients. PET revealed hypometabolism, SPECT decreased perfusion, and (1)HMRS reduction of N-acetylaspartate in the affected hemisphere. PET and SPECT were usually performed in the late stages and did not provide specific findings. MRI thus demonstrates the progression of RE and may suggest the diagnosis in the early stages, often before the appearance of neurological deficits. Early diagnosis of RE may be crucial for selecting patients for aggressive medical therapy or major surgical interventions such as hemispherectomy.     

Imaging of chest wall infections

A wide variety of infections can affect the chest wall including pyogenic, tuberculous, fungal, and some other unusual infections. These potentially life-threatening disorders are frequent especially among immunocompromised patients but often misdiagnosed by physical examination and radiographs. The purpose of this article is to describe the clinical and imaging features of these different chest wall infections according to the different imaging modalities with emphasis on ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI). The outcome of chest wall infection depends on early diagnosis, severity of the immunosuppression, offending organism, and extent of infection. Because clinical findings and laboratory tests may be not contributive in immunocompromised patients, imaging plays an important role in the early detection and precise assessment of the disease. US, CT, and MRI are all useful: bone destruction is more accurately detected with CT whereas soft tissue involvement are better visualized with US and MRI. CT and US are also used to guide percutaneous biopsy and drainage procedures. MR images are helpful in pre-operative planning of extensive chest wall infections.     

CT and MR imaging findings of malignant cardiac tumors

This article reviews CT and MRI features of malignant cardiac and pericardial tumors, most of which originate from the lung, breast, melanoma, leukemia, or lymphoma through lymphatic, hematogenous, transvenous, and direct pathways. Although echocardiography establishes the diagnosis in most cases, CT and MRI provide additional physical, spatial, and functional information that further aids the evaluation of metastases. For instance, CT provides superior resolution for detecting calcification or fat, while MRI with its direct multiplanar ability more completely characterizes the heart, pericardium, mediastinum, and lungs. MRI also helps elucidate the pathophysiological effects of these tumors on cardiac function through gated cine-loop sequences. Beyond tumor characterization, both modalities can help confirm diagnosis through the addition of contrast, which helps distinguish tumor from myocardium, thrombus, and blood flow artifact. Ultimately, MRI best facilitates surgical planning and posttreatment follow-up in large part because of its unparalleled ability to locate and delimit these tumors.     

Iofetamine HCI I-123 brain scanning in stroke: a comparison with transmission CT

Although IMP scans fail to show fine anatomical details of the brain, because of poor resolution of a single head rotational system, adequate information is offered by the scans to localize most perfusion defects caused by stroke. The following conclusions can be drawn from our study: 1. The planar IMP brain scans processed through the computer are sensitive in the early diagnosis of acute stroke except for small and deeply localized lesions. 2. The SPECT IMP imaging is more sensitive than the planar or transmission CT scans in the early diagnosis of stroke. Semiquantitative evaluations are feasible with IMP SPECT. 3. Neither transmission CT nor IMP SPECT are sensitive in the detection of acute lacunar infarcts. 4. In acute infarction, the transmission CT is usually negative or minimally positive in the early stages, while impaired uptake of IMP occurs immediately after the onset of the stroke. In acute stroke, the extent of the perfusion defect on IMP is usually greater than the abnormality seen on the transmission CT. 5. On followup studies, IMP scans show improved perfusion reflecting physiologic changes, while transmission CT scans show further dense anatomical changes when compared to the initial studies. 6. Hyperemic changes are likely due to collateral circulation or luxury perfusion. This finding suggests that the IMP reflects local cerebral blood flow in strokes.     

Information value of x-ray computed tomography for the detection and control of spondylitis

The information content of early bone changes in computed tomography (CT) of pyogenic non-tuberculous spondylitis and spinal tuberculosis is analysed. The CT findings are compared with conventional x-ray images including tomography. In 3 of 16 patients no indications of osteomyelitis were found by conventional x-ray images, whereas CT revealed paravertebral soft tissue swelling or abscesses and osteolysis and thus established the diagnosis of spondylitis. In one patient the process caused neurologic symptoms by extending into the epidural space. The contributions of CT to the diagnosis of spondylitis are to delineate the extent of soft tissue swelling, to detect small defects in the vertebral bodies, to exclude disc involvement, and to differentiate inflammations and other destructive changes. CT can be used for fine needle localization and aspiration of tissue or pus for histological or bacteriological investigations to establish the pathological diagnosis.     

MRI in inflammatory myopathies

Inflammatory myopathies encompass a group of acquired muscle disorders caused by infectious agents (bacteria, viruses, fungi and parasitic agents) or autoimmune processes (polymyositis, dermatomyositis and other types). In suspected infection sonography, CT and MRI are all able to show edema and fluid collections in soft tissues and muscles; sonography and CT may help guidance of a needle aspiration to establish a correct diagnosis. By offering better tissue differentiation, MRI appears to be more efficient than sonography and CT in diagnosing and managing autoimmune myopathies. MRI is indeed very sensitive to the presence of water and edema, and appears to be a very good indicator for an early diagnosis of diseases. MRI may also help to evaluate the extent and number of lesions, to guide a biopsy in an area of active disease and finally to follow the evolution under therapy. Received: 26 November 1999 Revision requested: 31 January 2000 Revision received: 7 April 2000 Accepted: 3 May 2000     

Herpes-simplex-Virus-Enzephalitis: neuroradiologische Differenzialdiagnose

Herpes simplex virus encephalitis (HSE) is the most frequent viral encephalitis, as a rule with the starting point and centre within the temporal lobe. If untreated, HSE is usually fatal, thus diagnosis has to be established rapidly. Treatment with Acyclovir should begin as soon as possible. As MRI is extremely sensitive in detecting the early inflammatory changes, it should be initially performed, especially as in the early stadium CT may be unspecific. We recommend the following examination protocol: coronar T1-weighted MR imaging before and after administration of gadopentetate dimeglumine, coronar FLAIR sequence and axial T2-weighted imaging. The diagnostic proof is to show the evidence of viral DNA by polymerase chain reaction (PCR) in cerebrospinal liquor.     

Multiples Myelom: Aktuelle Empfehlungen für die Bildgebung

CLINICAL/METHODICAL ISSUE: Imaging in monoclonal plasma cell disease serves to detect end organ damage, i.e., osteoporosis or bone destruction. Diffuse or circumscribed bone marrow infiltration without damage to mineralized bone is so far not regarded as end organ damage. STANDARD RADIOLOGICAL METHODS: Skeletal plain x-ray film survey to detect bone destruction, osteoporosis or fractures. METHODICAL INNOVATIONS: Whole body low-dose computed tomography (CT) and whole body magnetic resonance imaging (MRI) allow a more sensitive assessment of both mineralized bone and bone marrow, with greater patient comfort and in the case of MRI without ionizing radiation. PERFORMANCE: According to the literature, cross-sectional imaging is clearly superior to skeletal surveys and MRI is more sensitive than CT. Every locally destructive lesion will be detectable with MRI but for assessing the damage to mineralized bone CT is indispensible. The sensitivities of positron emission tomography (PET)/CT and MRI are comparable. ACHIEVEMENTS: If available whole body MRI and whole body low dose CT should replace conventional skeletal surveys. This has already been implemented in several centers in Germany. PRACTICAL RECOMMENDATIONS: For the initial diagnosis of monoclonal gammopathy of undetermined significance (MGUS), smoldering multiple myeloma or symptomatic multiple myeloma, a whole-body MRI and a whole body low-dose CT should be performed. For MGUS and asymptomatic myeloma, whole body MRI only should be performed for follow-up until detection of first bone destruction. Patients with symptomatic multiple myeloma and known bone destruction will usually have whole body low-dose CT, supplemented by MRI studies where clinically required.     

腰椎间隙感染的影像学诊断价值

笔者报告应用CT、ECT、X线平片和MR诊断椎间隙感染13例。根据本组X线平片所示,将其分为3期:骨质吸收疏松期,骨质破坏期和增生修复期。作者认为尽管x线平片和断层在椎间隙感染的早期敏感性和特异性较低,但仍是一种简单易行的诊断方法。CT能清楚显示病灶的部位。骨扫描对椎间隙感染具有高度的敏感性。MR比X线平片、CT、ECT更准确、更敏感、更有助于早期诊断。     

A comparison of modern imaging modalities in osteonecrosis of the femoral head

Eleven symptomatic and seven asymptomatic patients, considered to be at high risk of osteonecrosis of the hip, were studied using plain radiography, scintigraphy, computed tomography (CT) with multiplanar reconstruction (MPR), and magnetic resonance imaging (MRI), to determine the precise roles of the various imaging modalities in detecting and staging femoral head osteonecrosis, and to evaluate the incidence in an asymptomatic high-risk patient group. Osteonecrosis was best detected by MRI and was particularly useful for the diagnosis of early disease when other imaging modalities were negative. It is recommended that MRI be performed for the detection of early osteonecrosis, while CT/MPR be used for accurate staging and treatment planning in the established disease.     

X线 CT和磁共振成像在早期强直性脊柱炎骶髂关节病变诊断中的应用价值对比分析

目的分析X线、CT、磁共振成像(MRI)3种检查手段诊断早期强直性脊柱炎骶髂关节病变的应用价值。方法选择我院2018年1月至2019年1月收治的46例早期强直性脊柱炎骶髂关节病变患者开展研究,所有患者均进行X线检查、MRI检查、CT检查,比较3种检查方法的疾病检出率。结果对早期强直性脊柱炎骶髂关节病变典型影像学表现(关节软骨肿胀关节面侵蚀关节面下骨质囊变)的检出率,X线分别是0、52%、39%,MRI为:9%、83%、70%;CT为4%、76%、59%;X线检出率明显低于MRI、CT,比较差异有统计学意义(P<0.05),MRI与CT检出率相差不大,比较差异无统计学意义(P>0.05)。对该病的病变分级总检出率中,X线为48%,CT为85%,MRI为96%,在早期病变(0~Ⅱ级)的检出率中,X线为26%,CT为59%,MRI为65%,X线、CT、MRI在病变分级总检出率、0~Ⅱ级病变检出率的比较差异均有统计学意义(P<0.05),但是在Ⅲ、Ⅳ级病变检出率中差异无统计学意义(P>0.05)。结论X线、CT、MRI检查手段诊断早期强直性脊柱炎骶髂关节病变都具有一定的诊断价值,但MRI的检出率最高,能够准确显示出病变情况,MRI更具诊断优势及应用价值。     

急性骨髓炎的影像学诊断研究进展

急性骨髓炎的影像学诊断技术包括X线平片、超声、CT、MRI及放射性核素显像.早期X线平片的诊断灵敏度低.超声能早期发现深部软组织及骨膜下脓肿,但图像质量取决于操作者的熟练程度.CT能早期观察到微小的骨质改变,但灵敏度较低.MRI可优于其他检查显示髓腔内的病变,但对于死骨、钙化的诊断不如CT灵敏.放射性核素显像剂的种类繁...     

Radiological study of the brain at various stages of human immunodeficiency virus infection: early development of brain atrophy

Summary One hundred and one persons infected with human immunodeficiency virus (HIV-1), in whom other central nervous system infections or diseases were excluded, underwent brain CT and/or MRI at various stages of HIV-1 infection: 29 were asymptomatic (ASX), 35 had lymphadenopathy syndrome (LAS), 17 had AIDS-related complex (ARC), and 20 had AIDS. A control group of 32 HIV-1-seronegative healthy persons underwent brain MRI. The most common finding was brain atrophy, found in 9% of controls, and 31% of ASX cases, 29% of LAS, 59% of ARC and 70% of AIDS. Even the difference between the ASX or LAS groups and controls was significant. The changes were bilateral and symmetrical, and they were more severe at later stages of infection. Infratentorial atrophy was seen in the early stages; supratentorial atrophy became more pronounced at ARC, and generalized atrophy was typical of AIDS. Non-specific small hyperintense foci were found on MRI in 13% of controls and 6–15% of the infected groups. Larger, diffuse, bilateral white matter infiltrates were detected in 4 demented patients with AIDS. Four patients with AIDS and 1 with LAS had focal hyperintense lesions in the internal capsules, lentiform nuclei or thalamus, often bilateral on MRI. One patient with AIDS, examined with CT only, had low density in the lentiform nucleus. Loss of brain parenchyma can occur at an early stage of HIV-1 infection, and the atrophic process becomes more intense at later stages (ARC and AIDS). Parenchymal infiltration, seen as hyperintense areas on MRI, is most often associated with severe clinical symptoms, in the later stages of the disease.     

Magnetic resonance imaging determination of gliomatosis cerebri

Summary Gliomatosis cerebri is a rare condition characterized by diffuse overgrowth of large portions of the brain and spinal cord by glial cells in varying stages of differentiation. The tumor process is primarily an infiltrative, rather than a destructive one. Hence, pre-operative diagnosis by traditional imaging studies, including computed tomography (CT), has been difficult. Magnetic resonance imaging (MRI), with its unique sensitivity for cerebral pathology, is an ideal modality for demonstrating this lesion. We present three cases of gliomatosis cerebri in which high-field MRI clearly delineates the extent of the pathologic process.