E. Schindler

Primary central nervous system lymphoma in AIDS: a wider spectrum of CT and MRI findings

Abstract Diagnosis of primary central nervous system lymphoma (PCNSL) in patients with AIDS based on radiological findings is still a challenging problem. Our purpose was to review the CT and MRI findings in PCNSL in our patients with AIDS and compare them with those reported in the literature. CT and MRI of 28 patients with AIDS and pathologically confirmed PCNSL were analysed retrospectively for the number of lesions, their site, size, density, signal intensity, contrast enhancement, oedema and mass effect. We found 82 lesions. On CT 45 lesions were found in 22 patients, whereas MRI revealed 66 in 20 patients. The lymphoma was solitary in 20 patients (29 %) and multiple in 20 (71 %). Spontaneous haemorrhage was seen in 7 patients. Contrast-enhanced MRI showed no enhancement in 27.3 % (18/66) of the lesions. In one patient diffuse signal abnormalities in the white matter were seen on T2-weighted images. Our findings suggest that the previously described spectrum imaging characteristics of PCNSL has widened. Neuroradiologists should be aware of the variable appearance in patients with AIDS. Spontaneous haemorrhage, a nonenhancing lesion, or diffuse white matter changes do not exclude lymphoma in an immunocompromised patient.

SPIRAL CT ANGIOGRAPHY WITH DIGITAL SUBTRACTION OF EXTRA- AND INTRACRANIAL VESSELS

Objective A new imaging modality is presented in which a digital subtraction algorithm is applied to spiral CT angiography of extra- and intracranial vessels. Materials and Methods Spiral CT angiography was carried out in 26 patients. When this was done for stereotactic purpose before radiosurgery, a Leksell stereotactic frame was used; in the other cases an atraumatic fixation system was applied. Spiral CT data were acquired twice—before and after contrast agent administration. Then, computerized subtraction of the density values of plain CT from the topographically corresponding enhanced CT was performed. Maximum intensity projection was used to visualize the vessels. Results This method provided significant effacement of nonvascular structures and a considerably improved visualization of extracranial as well as intracranial vessels could be achieved. In some conditions, e.g., to exclude a suspected thrombotic occlusion of the basilar artery, conventional angiography could even be omitted. Conclusion Adequate visualization of extra- and intracranial vessels is possible with spiral CT angiography and digital subtraction. An important scope of this modality could be its contribution to radiosurgical planning and the follow-up after radiotherapy. In some conditions, CT subtraction angiography may possibly supersede conventional subtraction angiography.

Progressive multifocal leukoencephalopathy in AIDS: initial and follow-up CT and MRI

Abstract We sought to determine the value of follow-up CT and MRI in patients with acquired immunodeficiency syndrome (AIDS) and progressive multifocal leukoencephalopathy (PML). We reviewed 50 CT and 19 MRI examinations performed in 21 biopsy- or autopsy-proven cases of PML; 17 patients had follow-up examinations (mean time 5.9 weeks). The radiological examinations were correlated with pathological findings at autopsy. On initial imaging studies, 73 lesions were found. On follow-up, the most striking feature was rapid progression in both size and number of the lesions (from a mean of 3.2 to 6.9 per patient). One third of the patients showed increasing mass effect. A central area suggesting necrosis, of variable size, was found in 12/16 patients. Autopsy revealed macroscopic necrotic changes in the lesions in 11/16 patients.

MRI in patients with general paresis.

Few cases of MRI in neurosyphilis have been reported. We examined the value of MRI in patients with general paresis; MRI was performed on four HIV-negative patients with parenchymatous neurosyphilis. It demonstrated frontal and temporal atrophy, subcortical gliosis and, in one patient, increased ferritin in the basal ganglia. The progression of the lesions on MRI correlated well with the neuropsychiatric disturbances. The MRI findings correlated with the wellknown neuropathological findings. This combination of pathological findings in neurosyphilis has not been described before and we suggest that MRI is of prognostic value in patients with general paresis.

Intraoperative Computed Tomography Guided Neuronavigation: Concepts, Efficiency, and Work Flow

Image-guided surgery is currently considered to be of undisputed value in microsurgical and endoscopical neurosurgery, but one of its major drawbacks is the degradation of accuracy during frameless stereotactic neuronavigation due to brain and/or lesion shift. A computed tomography (CT) scanner system (Philips Tomoscan M) developed for the operating room was connected to a pointer device navigation system for image-guided surgery (Philips EasyGuide system) in order to provide an integrated solution to this problem, and the advantages of this combination were evaluated in 20 cases (15 microsurgical and 5 endoscopic). The integration of the scanner into the operating room setup was successful in all procedures. The patients were positioned on a specially developed scanner table, which permitted movement to a scanning position then back to the operating position at any time during surgery. Contrast-enhanced preoperative CCTs performed following positioning and draping were of high quality in all cases, because a radiolucent head fixation technique was used. The accuracy achieved with this combination was significantly better (1.6:1.22.2). The overall concept is one of working in a closed system where everything is done in the same room, and the efficiency of this is clearly proven in different ways. The most important fact is the time saved in the overall treatment process (about 55 h for one operating room over a 6-month period). The combination of an intraoperative CCT scanner with the pointer device neuronavigation system permits not only the intraoperative control of resection of brain tumors, but also (in about 20% of cases) the identification of otherwise invisible residual tumor tissue by intraoperative update of the neuronavigation data set. Additionally, an image update solves the problem of intraoperative brain and/or tumor shifts during image-guided resection. Having the option of making an intraoperative quality check at any time leads to significantly increased efficiency, improves the operating work flow because of the closed-system concept, and offers an integrated solution for improved patient work flow and clinical outcome.

CNS involvement in AIDS: spectrum of CT and MR findings.

Abstract The brain may be affected by a variety of abnormalities in association with human immunodeficiency virus (HIV) infection. Knowledge of their existence and characteristic imaging features are important to radiologists for detection, diagnosis, and initiation of an appropriate treatment. Although there is a considerable overlap in the imaging characteristics of different entities, some findings are found to be very suggestive of a particular disease. The CT and MR imaging techniques are commonly used in the diagnosis of neurological disorders in acquired immunodeficiency syndrome (AIDS) patients, to verify treatment response and to guide brain biopsy. This review attempts to describe CT and MR features of infectious and malignant brain disorders in HIV-seropositive patients.

Malignant lymphoma of the cranial vault in an HIV-positive patient: imaging findings

Abstract. We describe the CT and MR imaging findings in an HIV-positive patient with malignant non-Hodgkins lymphoma of the cranial vault, a rare site for lymphoma involvement. Autopsy revealed lymphomatous bone lesions, lymphoma in the epidural space, and a large necrotic lymphoma in the soft tissue of the skull.

MRI in a case of Sandhoff's disease

An 18-month-old girl was examined by MRI for progressive psychomotor retardation. T2-weighted images demonstrated abnormal high signal in the putamina and low signal in the thalamus (due probably to calcification). Although the cerebral cortex was markedly atrophic, there were signs of brain enlargement because of swelling of the extensively diseased white matter. The diagnosis of Sandhoffs disease was established by low serum levels of hexosaminidase A and B.

Fetal and early postnatal magnetic resonance imaging – is there a difference?

Abstract Aim: To evaluate whether fetal magnetic resonance imaging (MRI) could replace early postnatal MRI in fetuses with central nervous system (CNS) anomalies. Methods: Thirteen pregnancies presenting with fetal CNS anomalies were investigated using MRI. Indications included ventriculomegaly combined with additional CNS anomaly (n=5), isolated ventriculomegaly (n=2), arachnoid cyst (n=2), holoprosencephaly (n=1), complex malformation syndrome (ns1), Dandy walker malformation (n=1) and midline cyst (n=1). Early postnatal MRI followed within the first six weeks of life. Results: Investigation with early postnatal MRI confirmed the fetal MRI diagnosis in all cases. Investigation with postnatal MRI presented additional information in two cases. However, there was no change in patient care. Conclusions: Fetal MRI should replace early postnatal MRI in infants with CNS anomalies.

Extra-CNS metastases of glioblastoma: CT and MR studies.

The case of a 29-year-old man with glioblastoma and multiple metastases outside the CNS is presented. Cervical lymph node involvement was ascertained with CT and magnetic resonance (MR), and numerous bone metastases were detected with skeletal scintigraphy. The extent of the cervical tumor and its relationship to the carotid artery could be better assessed with MR than with CT. The patient died despite repeat operations, radiotherapy, and intraarterial systemic chemotherapy. The importance of radiological screening for detecting glioblastoma metastases in patients with long survival is discussed.