Use of the FLAIR sequence in the magnetic resonance evaluation of neurocysticercosis

THESES

Use of the FLAIR sequence in the magnetic resonance evaluation of neurocysticercosis (Abstract)^*. Thesis. São Paulo, 2003.

Marcelo dos Santos Guedes^**

Neurocysticercosis is an infectious disease of parasitic origin characterized by the involvement of the central nervous system (CNS) by the larval form of the Taenia solium, being considered one of the more frequent infectious diseases in this location in humans. It represents an important public health problem, for most of the developing countries. Recent data mention 50,000 deaths a year and not less than 20 million people infected by the cysticerci, in the world.

The objectives of this study were: to evaluate the usefulness of the magnetic resonance (MR) FLAIR sequence, in the diagnosis of this disease; to compare the main findings of the FLAIR sequence to the other MR sequences; and to define the preferential location of neurocysticercosis lesions, as well as the apprenticeships in the larval way most found in this series.

We studied prospectively MR exams of 115 patients with neurocysticercosis, with ages varying between 4 and 64 years, presenting intracranial lesions. The MR protocol included T1, T2, FLAIR and T1 weighted images after the injection of the paramagnetic contrast. Two post-contrast sequences were obtained, one immediately after gadolinium injection and the other some minutes afterwards. All MR exams were evaluated by two radiologists separately. Each one of the examiners took notice for every sequence and MR exam of the lesions location (parenchymal, subarachnoid, ventricular or the association of one or more of the previous ones); the total number of lesions, specifying how many were calcified and in how many a scolex could be detected; the lesions topography (supratentorial, infratentorial or both), and the lesions apprenticeship of the larval form: vesicular, colloidal vesicular, nodular or calcified nodular. There were no statistically significant differences between the results obtained by the two examiners, demonstrating internal agreement.

Of the 115 MR exams: 80 (69.6%) presented parenchymal lesions, 11 (9.6%) subarachnoid, 6 (5.2%) ventricular and 18 (15.6%) presented two or more different forms. FLAIR allowed the detection of the largest number of lesions with scolex and in the late enhanced T1-weighted images it was possible to detect the largest number of total lesions. In 32 cases for the examiner A and in 28 for B, the scolex was visualized in just one of the sequences, being this sequence, in 27 and 24 of these cases respectively, the FLAIR sequence. The lesions preferential location was in the supratentorial compartment. Regarding the apprenticeships in the larval way it was observed that in 98.3 to 99.1% of the cases the vesicular apprenticeship existed, in 47.0 to 50.4% the colloidal vesicular, in 65.2 to 69.6% the nodular and in 31.3 to 33% the calcified nodular lesions.

In conclusion: the FLAIR sequence detected the larger number of scOlex, which is considered a criterion for the definitive diagnosis of the disease. The FLAIR sequence demonstrated a larger total number of lesions than the T1 and T2-weighted images, but out of all sequences the late enhanced T1-weighted image allowed visualization of the largest total number of lesions. The parenchymal form was mostly found in this series (69.6% of the patients). Lesions prevailed in the supratentorial location (68.7% to 71.3%). With relationship to the evolutionary apprenticeship in the larval way there was a prevalence of the vesicular stage (98.3 to 99.1% of the cases), associated to at least two stages in 65.2 to 69.6% of the cases and the four stages of the larval way were present among 31.3 to 33.0% of the cases.

Key words: cysticercosis, central nervous system, magnetic resonance imagING, FLAIR sequence.

*

Sequência Flair da ressonância magnética na neurocisticercose (Resumo). Tese (Doutorado), Universidade de São Paulo (Área: Radiologia). Orientador: Cláudia da Costa Leite.

**

Address: Instituto de Radiologia, Hospital das Clínicas FMUSP, Avenida Enéas Carvalho Aguiar 255- 05403-100 São Paulo SP, Brasil.

Publication Dates

• Publication in this collection
  28 Apr 2004
• Date of issue
  Mar 2004