[Value of magnetic resonance in the diagnostic definition of neurotoxoplasmosis and in the assessment of the response to pharmacological treatment]. / Valore della Risonanza Magnetica nella definizione diagnostica della neurotoxoplasmosi e nella valutazione della risposta al trattamento farmacologico.

PURPOSE: We investigated the role of Magnetic Resonance Imaging (MRI) in the diagnosis of neurotoxoplasmosis and in the evaluation of drug treatment response. MATERIAL AND METHODS: Twenty-six AIDS patients (22 men and 4 women, mean age 26.7 years) with clinical suspicion of neurotoxoplasmosis were examined. A patient was considered to have neurotoxoplasmosis if there were signs of focal neurologic impairment and a positive/questionable response to the serum test for Toxoplasma gondii. MR images were acquired with T1-weighted spin-echo (SE) and inversion recovery (IR) sequences and with T2-weighted SE sequences. Gd-DTPA was administered in all cases. After the beginning of therapy with sulfadiazine and pyrimethamine all patients were submitted to clinical and neuroradiologic follow-up for 60 days. RESULTS: MR examinations on admission demonstrated at least one brain lesion in all patients and multifocal involvement in 70% of cases. Enhancing lesions were found in 90% of patients (83% ring enhancement, 4% focal enhancement, 3% mixed patterns). The most frequent lesion sites were the basal ganglia and thalami (70%). The brain lesions were subdivided into 4 groups by their morphology and signal patterns. DISCUSSION: The time course of clinical and neuroradiologic responses demonstrates a rapid improvement after the first week of therapy, which stabilized after the second week. Pearson correlation between clinical and neuroradiologic treatment responses showed a nearly linear correlation (r = .97; p < .001). The diagnosis was then confirmed in all patients based on the positive response to the serum test for Toxoplasma gondii (IgG > 12 UI/mL) and/or clinical and neuroradiologic improvement after therapy. DISCUSSION AND CONCLUSIONS: This study demonstrates the accuracy of MRI in the detection of toxoplasmosis brain lesions and in the evaluation of treatment response.

[Stereotactic brain biopsy in AIDS patients: a necessary patient-oriented and cost-effective diagnostic measure?]. / Die stereotaktische Hirnbiopsie bei AIDS-Patienten: eine notwendige, patientenorientierte und kosteneffektive diagnostische Massnahme?

Neurological complications occur in 40% of "human immunodeficiency virus type 1" (HIV-1)-infected patients. Aim of the study was to evaluate the diagnostic yield of stereotactic brain biopsy and non invasive diagnostic procedures (CT, antitoxoplasma antibodies) and to calculate the benefit of the brain biopsy for the patient and the costs of both methods. From October 1989 through September 1995 we biopsied 44 of 2749 (2%) HIV-1-infected patients after non invasive diagnostic procedures had been performed. In 93% of the patients an unambiguous diagnosis was possible based on the biopsy and lead in 73% of the patients to a change of therapy. No complications occurred after biopsy. 40 CTs and 15 MRIs were done. The radiological appearance of toxoplasmosis and non Hodgkin lymphoma (NHL) differed from that of progressive multifocal leucencephalopathy (PML) in respect to enhancement (PML). CT showed a sensitivity of 55% (toxoplasmosis, NHL) and 78% (PML) and a specificity of 83% (PML), 84% (NHL) and 96% (toxoplasmosis), respectively. Antitoxoplasma antibodies showed a sensitivity of 45%, only. The stereotactic brain biopsy was more expensive (20.166,- ATS) than CT, MRI and antitoxoplasma antibodies (4109,- ATS up to 6959,- ATS). We conclude that stereotactic brain biopsy is an efficient and safe and for the patients important diagnostic procedure. In selected patients even expensive investigations should be undertaken considering specific therapy and cost effective homecare.

Intracranial mass lesions in acquired immunodeficiency syndrome: using decision analysis to determine the effectiveness of stereotactic brain biopsy.

We studied the effectiveness of performing a stereotactic brain biopsy in the individual with acquired immunodeficiency syndrome (AIDS) and an intracranial mass lesion who failed 2 weeks of antitoxoplasmosis therapy. We used a decision analysis to compare two different treatment strategies: biopsy and no biopsy. The analysis estimates the average life expectancy for each choice and investigates the sensitivity of these results by varying parameters within the model. In the base case analysis (diagnostic yield of biopsy, 0.89; operative mortality, 0.015; life expectancy of lymphoma untreated and treated, 42 and 120 days), the life expectancy of the biopsy strategy was 98 days compared with 67 days for the no-biopsy strategy, for a net survival benefit of 31 days. Sensitivity analyses revealed that the life expectancy of the biopsy strategy remained greater than the no-biopsy strategy for a wide range of variable specifications. The net survival benefit, however, was sensitive to the diagnostic success rate, the operative mortality, the likelihood of a lymphoma diagnosis, and the life expectancy of patients being diagnosed and treated for lymphoma. These data allow AIDS patients and physicians to learn more about the potential outcomes of the alternative management strategies when an individual fails to respond to empiric antitoxoplasmosis therapy.

Early biopsy versus empiric treatment with delayed biopsy of non-responders in suspected HIV-associated cerebral toxoplasmosis: a decision analysis.

OBJECTIVE: To construct and evaluate a decision analytic model of proposed management strategies for HIV-infected patients presenting with cerebral mass lesions, radiographically compatible with toxoplasmosis, lymphoma, or other etiologies, assuming knowledge of Toxoplasma antibody status in serum. METHODS: Using decision analysis, we evaluated two management strategies, for patients found to be either Toxoplasma-seropositive or -negative, for whom an initial choice was made for early brain biopsy (EB) or for empiric therapy with delayed biopsy (ETDB) of non-responders. The outcome to be optimized was the percentage of patients alive at 12 months. Model variables included predictive value of toxoplasmosis serology, probabilities of treatment response and death within 14-21 days conditional on correct diagnosis, probability of operative death, probabilities of non-diagnostic brain biopsy conditional both on correct diagnosis and prior treatment. RESULTS: One and two-way sensitivity analyses, by Toxoplasma serostatus, led to the following conclusions (1) for Toxoplasma-seropositive patients, ETDB gives nearly equivalent outcomes to EB of all patients; (2) for Toxoplasma-seronegative patients, although both strategies have equivalent outcomes under baseline assumptions, EB is preferred if there are even small survival advantages for early versus delayed diagnosis of lymphoma or other conditions, or if risk of death within 14-21 days of ET exceeds 10% when correct diagnosis is not toxoplasmosis. CONCLUSION: Under plausible assumptions, Toxoplasma-seronegative patients will benefit from an early biopsy strategy.