Diagnostic imaging contribution in the early stages of HIV infection of the brain.

The neuropathology of full-blown, symptomatic AIDS, established in many large autopsy series, has been described in great detail and is now universally accepted. In contrast, the natural history of the changes occurring in the central nervous system during the earlier states of HIV-1 infection remains poorly understood. With specific regard to MR imaging, structural abnormalities have been reported early in the course of the illness, with variable incidence, making it difficult to appreciate the significance of these findings, in particular for neurologically asymptomatic individuals. This article analyzes successively neuropathologic studies at the early stages of brain involvement by HIV and shows how imaging techniques contribute to the understanding of what is going on during the so-called "asymptomatic" period, lasting from seroconversion to symptomatic AIDS. The complementary use of clinical imaging and new technical modalities, such as proton spectroscopy MR imaging or functional MR imaging, will provide more specific and sensitive analyses. Animal studies also will contribute in the future by providing a better knowledge of the natural history of the illness and providing a means for testing the efficacy of new medication.

[The epidemiology and cost of AIDS in France]. / Epidémiologie et coût du SIDA en France.

Throughout the world the AIDS epidemic continues and even seems to accelerate in regions previously thought to be untouched. The number of cases has increased by 60% in one year. With its 15,000 seropositive persons and 35,000 cases of declared AIDS, France is the most affected of all European countries. Sexual contamination remains predominant with a relative increase of heterosexual transmissions. However, particularly in the South, transmission is prevalent in intra-venous drug addicts. In all cases worldwide it is the socially deprived, marginal and fragile populations which are the most vulnerable. Various previsions are possible in France, depending on the prophylactic measures applied. In any event, the number of seropositive subjects should be levelling out at the end of this decade, and the prevalence of the disease should stabilized at between 15,000 to 20,000 patients. At present, the cost of AIDS exceeds 5.5 billion francs.

[Early involvement of the central nervous system in HIV infection: screening by MRI (a 5-year follow-up)]. / Atteintes précoces du système nerveux central par le VIH: dépistage par IRM (étude sur 5 ans).

A cohort of 50 initially asymptomatic seropositive patients have been followed for five years. Various clinical evolution have been observed: 21 remain stable, 29 underwent complications that take then to AIDS, 11 died. In any case, invariability of the MRI anomalies seems had to be imputed to primary infection scars.

MRI pattern of progressive multifocal leukoencephalopathy (PML) in AIDS. Pathological correlations.

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease which occurs in immunodepressed subjects and is particularly frequent in AIDS. Some authors having drawn attention to the protean aspect of the disease and claimed that AIDS may lose its basic characteristics and affect the grey matter as well as the white matter, we reviewed a series of 8 patients who had been biopsied and/or autopsied and had been examined at least once by MRI. In this series, contrary to what is regularly observed in toxoplasmic abscesses we did not find any lesion of the grey matter or any mass effect. On the other hand, we confirmed that PLM is not multifocal in all cases and that it course may be interrupted by prolonged remissions. The MRI criteria for PML therefore are reliable, provided multiple T2-weighted slices in coronal plane are performed, clearly showing the anatomy of the white fibres affected. However, it must be borne in mind that HIV-infected patients often have other associated brain pathologies, especially when the immune deficiency increases.

Post-pneumonectomy evaluation of the chest: a prospective comparative study of MRI with CT.

A comparative study of 11 pneumonectomized patients was undertaken in order to evaluate the respective advantages and drawbacks of MRI and CT in post-operative follow-up. Nine patients were healthy at the time of the study and two presented with tumor recurrence. MR examination included 500/40 ms axial, and frontal 800/40-80 ms or 1300/60-120 ms nongated spin echo sequences. MRI was slightly more efficient in identifying vascular stump and main nodal stations, and detected better than CT tumoral and metastatic spread in cancer recurrences. It was as informative as CT in evaluating postpneumonectomy space and bronchial stump. It was noncontributory in the detection of calcifications. Although clips were visible with MRI, their location was less definite than with CT, a potential pitfall when radiotherapy is planned.

[Cerebral MRI in the study of prognostic factors in AIDS. Hypotheses from tests on 15 patients]. / Apport de l'IRM cérébrale à l'étude des facteurs pronostiques du SIDA. Hypothèses à partir de l'examen de 15 patients.

In an attempt to determine factors of predictive value in HIV (human immuno-deficiency virus) seropositive patients, particular attention was payed to symptoms indicating early involvement of the central nervous system (CNS). A cohort of healthy carriers was thus constituted. Follow-up will be carried out every six month including clinical, biological as well as CNS imaging by NMR. Among the first 15 of them, abnormalities could be observed in 4 individuals. Lesions consisted in nodules of high signal in T2 which were localized either in the white matter or thalamic nuclei. No relationship could be demonstrated between the existence of these lesions and various criteria such as age, sex, risk factors and T4 cells count. Such lesions appeared similar to the localizations observed in multiple sclerosis or to the scars of limited vascular accidents. The nature of these lesions is not clear. They certainly indicate early involvement of CNS after primary infection by the HIV virus. They may either represent sequellae of this primary infection or early alterations announcing developing encephalopathy.

[Magnetic resonance imaging: early detection of involvement of the central nervous system in acquired immunodeficiency syndrome]. / Imagerie par résonance magnétique: dépistage précoce des atteintes du système nerveux central au cours du syndrome d'immuno-déficience acquise (SIDA).

Central Nervous System (CNS) involvement, whether primary by the Human Immunodeficiency Virus--HIV--itself, or secondary (toxoplasmosis or lymphoma) is remarkably frequent in AIDS, in 40 to 70% of cases, depending upon the author. In order to study the natural history of this illness, a cohort of 25 asymptomatic seropositive patients have been established. Every 6 months these patients undergo biological and clinical examinations, as well as Magnetic Resonance brain scans. After two examinations at a 6 month's interval, the first results are reported. Out of these 25 cases, 9 present anomalies: One patient with diffuse cerebral atrophy and 8 others with high signal intensity areas on T2 weighted sequences, like those of the Multiple Sclerosis. No relationship could be demonstrated between the existence of these lesions and various criteria such as age, sex, risk factors and T4 cells count. The nature of these lesions is not clear. They certainly indicate early involvement of the CNS after primary infection by the HIV virus. They may either represent scars of the primary infection or early alterations announcing developing encephalopathy.